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13 pages, 860 KiB  
Article
Assessment of the Intra- and Inter-Observer Reliability of Beef Cattle Mobility Scoring Performed by UK Veterinarians and Beef Farmers
by Hannah May Fitzsimmonds, Jay Tunstall, John Fishwick and Sophie Anne Mahendran
Ruminants 2024, 4(4), 463-475; https://doi.org/10.3390/ruminants4040033 (registering DOI) - 16 Oct 2024
Abstract
Background: Lameness in cattle negatively affects welfare and productivity. Early identification of lameness allows for prompt treatment, and mobility scoring allows for herd-level prevalence data to be monitored. The reliability of a four-point mobility scoring system was investigated when used by beef farmers [...] Read more.
Background: Lameness in cattle negatively affects welfare and productivity. Early identification of lameness allows for prompt treatment, and mobility scoring allows for herd-level prevalence data to be monitored. The reliability of a four-point mobility scoring system was investigated when used by beef farmers and veterinary surgeons. Methods: An online questionnaire that contained forty video clips of beef cattle was created for mobility scoring performed by farmers and vets. Results: The Fleiss kappa coefficient for inter-observer agreement across all 81 respondents and all videos was 0.34, which showed fair agreement. Beef farmers generally had lower agreement than vets (0.29 vs. 0.38). Vets had significantly higher inter-observer reliability compared to beef farmers (p = 0.035). Overall, Cohen’s kappa coefficient for intra-observer agreement across all respondents varied from 0.085 (slight agreement) to 0.871 (almost perfect agreement). Limitations: The survey was only available online, which may have limited distribution and engagement. The recruitment of participants was not specific to differing levels of previous experience in mobility scoring. The mobility scoring was not performed in person, which could be more reflective of clinical application. Conclusions: The application of a four-point mobility scoring system for beef cattle had fair inter-observer reliability and a wide range of intra-observer reliability, but this is poorer than previously reported. This presents a challenge for the identification of lame beef cattle at both the individual and herd levels. Full article
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Figure 1

Figure 1
<p>Figure showing how beef farmers and veterinary surgeons scored each of the 40 clips of beef cattle within the survey. Clips number 4 to 30 were score 0 clips, 3 to 35 were score 1, 26 to 37 were score 2, and 31 to 38 were score 3. This includes eight videos that were duplicated, which were repeated twice in the survey to collect data on intra-observer reliability. The duplicated clips are numbers 4 and 14, 1 and 32, 3 and 18, 9 and 40, 26 and 36, 17 and 20, 31 and 39, and 11 and 15, with these pairs indicated with matching symbols.</p>
Full article ">
11 pages, 886 KiB  
Article
Blood Extracellular Vesicles Beyond Circulating Tumour Cells: A Valuable Risk Stratification Biomarker in High-Risk Non-Muscle-Invasive Bladder Cancer Patients
by Valentina Magri, Luca Marino, Francesco Del Giudice, Michela De Meo, Marco Siringo, Ettore De Berardinis, Orietta Gandini, Daniele Santini, Chiara Nicolazzo and Paola Gazzaniga
Biomedicines 2024, 12(10), 2359; https://doi.org/10.3390/biomedicines12102359 (registering DOI) - 16 Oct 2024
Abstract
Non-muscle-invasive bladder cancer (NMIBC) prognosis varies significantly due to the biological and clinical heterogeneity. High-risk stage T1-G3, comprising 15–20% of NMIBCs, involves the lamina propria and is associated with higher rates of recurrence, progression, and cancer-specific mortality. In the present study, we have [...] Read more.
Non-muscle-invasive bladder cancer (NMIBC) prognosis varies significantly due to the biological and clinical heterogeneity. High-risk stage T1-G3, comprising 15–20% of NMIBCs, involves the lamina propria and is associated with higher rates of recurrence, progression, and cancer-specific mortality. In the present study, we have evaluated the enumeration of tumour-derived extracellular vesicles (tdEVs) and circulating tumour cells (CTCs) in high-risk NMIBC patients and their correlation with survival outcomes such as time to progression (TTP), and cancer-specific survival (CSS). Eighty-three high-risk T1-G3 NMIBC patients treated between September 2010 and January 2013 were included. Blood samples were collected before a transurethral resection of the bladder (TURB) and analysed using the CellSearch® system. The presence of at least one CTC was associated with a shorter TTP and CSS. Extending follow-up to 120 months and incorporating automated tdEV evaluation using ACCEPT software demonstrated that tdEV count may additionally stratify patient risk. Combining tdEVs and CTCs improves risk stratification for NMIBC progression, suggesting that tdEVs could be valuable biomarkers for prognosis and disease monitoring. Further research is needed to confirm these findings and establish the clinical significance of tdEVs in early-stage cancers. Full article
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Figure 1
<p>Kaplan–Meier survival curve for time to transition (TTP) according to CTC and tdEV counts.</p>
Full article ">Figure 2
<p>Kaplan–Meier survival curve for cancer-specific survival (CSS) according to CTC and tdEV counts.</p>
Full article ">
16 pages, 2230 KiB  
Article
Computational Analysis of Stiffness Reduction Effects on the Dynamic Behaviour of Floating Offshore Wind Turbine Blades
by Daniel O. Aikhuele and Ogheneruona E. Diemuodeke
J. Mar. Sci. Eng. 2024, 12(10), 1846; https://doi.org/10.3390/jmse12101846 (registering DOI) - 16 Oct 2024
Abstract
This paper describes the study of a floating offshore wind turbine (FOWT) blade in terms of its dynamic response due to structural damage and its repercussions on structural health monitoring (SHM) systems. Using a finite element model, natural frequencies and mode shapes were [...] Read more.
This paper describes the study of a floating offshore wind turbine (FOWT) blade in terms of its dynamic response due to structural damage and its repercussions on structural health monitoring (SHM) systems. Using a finite element model, natural frequencies and mode shapes were derived for both an undamaged and a damaged blade configuration. A 35% reduction in stiffness at node 1 was applied in order to simulate significant damage. Concretely, the results are that the intact blade has a fundamental frequency of 0.16 Hz, and this does not change when damaged, while higher modes exhibit frequency changes: mode 2 drops from 2.05 Hz to 2.00 Hz and mode 3 from 6.15 Hz to 6.01 Hz. The shifts show a critical loss in the capability of handling vibrational energy due to the damage; higher modes (4, 5, and 6) show larger frequency deviations going down to as low as 18.06 Hz in mode 6. The mode shape change is considerable for the edge-wise and flap-wise deflection of the 2D contour plots, indicating possible coupling effects between modes. These results indicate that lower modes are sensitive to stiffness reductions, and the continuous monitoring of the lower harmonic modes early is required to detect damages. These studies have helped to improve blade design, maintenance, and operational safety for FOWT systems. Full article
(This article belongs to the Special Issue Modelling Techniques for Floating Offshore Wind Turbines)
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Figure 1

Figure 1
<p>Schematic diagram of a NREL 5 MW OWT [<a href="#B27-jmse-12-01846" class="html-bibr">27</a>].</p>
Full article ">Figure 2
<p>Magnified view of the contour plot for 35% damage level.</p>
Full article ">Figure 3
<p>The graphical visualization of the mode shapes in undamaged and 35% damaged state.</p>
Full article ">Figure 4
<p>The graphical visualization of the mode shapes in an undamaged state and in states of 5%, 20%, and 35% damage.</p>
Full article ">Figure 5
<p>The graphical representation of the damage level in comparison to the mode number.</p>
Full article ">Figure A1
<p>Visualization Different Damage Levels through Contour Plots.</p>
Full article ">Figure A1 Cont.
<p>Visualization Different Damage Levels through Contour Plots.</p>
Full article ">
28 pages, 9040 KiB  
Article
First Hitting Times on a Quantum Computer: Tracking vs. Local Monitoring, Topological Effects, and Dark States
by Qingyuan Wang, Silin Ren, Ruoyu Yin, Klaus Ziegler, Eli Barkai and Sabine Tornow
Entropy 2024, 26(10), 869; https://doi.org/10.3390/e26100869 (registering DOI) - 16 Oct 2024
Abstract
We investigate a quantum walk on a ring represented by a directed triangle graph with complex edge weights and monitored at a constant rate until the quantum walker is detected. To this end, the first hitting time statistics are recorded using unitary dynamics [...] Read more.
We investigate a quantum walk on a ring represented by a directed triangle graph with complex edge weights and monitored at a constant rate until the quantum walker is detected. To this end, the first hitting time statistics are recorded using unitary dynamics interspersed stroboscopically by measurements, which are implemented on IBM quantum computers with a midcircuit readout option. Unlike classical hitting times, the statistical aspect of the problem depends on the way we construct the measured path, an effect that we quantify experimentally. First, we experimentally verify the theoretical prediction that the mean return time to a target state is quantized, with abrupt discontinuities found for specific sampling times and other control parameters, which has a well-known topological interpretation. Second, depending on the initial state, system parameters, and measurement protocol, the detection probability can be less than one or even zero, which is related to dark-state physics. Both return-time quantization and the appearance of the dark states are related to degeneracies in the eigenvalues of the unitary time evolution operator. We conclude that, for the IBM quantum computer under study, the first hitting times of monitored quantum walks are resilient to noise. However, a finite number of measurements leads to broadening effects, which modify the topological quantization and chiral effects of the asymptotic theory with an infinite number of measurements. Full article
(This article belongs to the Special Issue Quantum Walks for Quantum Technologies)
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Figure 1

Figure 1
<p>Scheme of the tight-binding model for a ring with three sites (<math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">0</mn> <mo>〉</mo> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">1</mn> <mo>〉</mo> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">2</mn> <mo>〉</mo> </mrow> </semantics></math>) pierced by a magnetic flux <math display="inline"><semantics> <mi>α</mi> </semantics></math>, corresponding to a directed or chiral triangle graph with complex edge weights, for two different measurement protocols. <math display="inline"><semantics> <mi>γ</mi> </semantics></math> denotes the strength of the hopping matrix element. Left panel: The on-site protocol measures periodically only the target state <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">0</mn> <mo>〉</mo> </mrow> </semantics></math>. Right panel: the tracking protocol periodically measures all sites. The measurement is indicated with a measuring device. In both cases, the hitting time is the first time when the system is detected in state <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">0</mn> <mo>〉</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 2
<p>Parameters where two or three eigenvalues of the unitary <span class="html-italic">U</span> are degenerate (phase factor matching diagram). In the plain <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>γ</mi> <mi>τ</mi> <mo>,</mo> <mi>α</mi> <mo>)</mo> </mrow> </semantics></math>, the phase factors <math display="inline"><semantics> <mrow> <mo form="prefix">exp</mo> <mo>(</mo> <mo>−</mo> <mi>i</mi> <msub> <mi>E</mi> <mi>k</mi> </msub> <mi>τ</mi> <mo>)</mo> </mrow> </semantics></math> with <math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> </mrow> </semantics></math> match in pairs or triplets. Colors describe the matching of two phase factors, for example, <math display="inline"><semantics> <mrow> <mo form="prefix">exp</mo> <mrow> <mo>(</mo> <mo>−</mo> <mi>i</mi> <msub> <mi>E</mi> <mn>0</mn> </msub> <mi>τ</mi> <mo>)</mo> </mrow> <mo>=</mo> <mo form="prefix">exp</mo> <mrow> <mo>(</mo> <mo>−</mo> <mi>i</mi> <msub> <mi>E</mi> <mn>1</mn> </msub> <mi>τ</mi> <mo>)</mo> </mrow> </mrow> </semantics></math> in red, and similarly for the pairs <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>E</mi> <mn>0</mn> </msub> <mo>,</mo> <msub> <mi>E</mi> <mn>2</mn> </msub> <mo>)</mo> </mrow> </semantics></math> (green) and <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>E</mi> <mn>1</mn> </msub> <mo>,</mo> <msub> <mi>E</mi> <mn>2</mn> </msub> <mo>)</mo> </mrow> </semantics></math> (orange). The matching of all three phase factors is shown as blue circles or a blue line at <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math> indicating the Zeno regime. Examples where three phase factors match are <math display="inline"><semantics> <mrow> <mrow> <mo>(</mo> <mi>α</mi> <mo>,</mo> <mi>γ</mi> <mi>τ</mi> <mo>)</mo> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <mn>0</mn> <mo>,</mo> <mn>0</mn> <mo>)</mo> </mrow> <mo>,</mo> <mrow> <mo>(</mo> <mn>0</mn> <mo>,</mo> <mn>2</mn> <mi>k</mi> <mi>π</mi> <mo>/</mo> <mn>3</mn> <mo>)</mo> </mrow> <mo>,</mo> <mrow> <mo>(</mo> <mi>π</mi> <mo>/</mo> <mn>6</mn> <mo>,</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> <mo>)</mo> </mrow> <mo>,</mo> <mrow> <mo>(</mo> <mi>π</mi> <mo>/</mo> <mn>3</mn> <mo>,</mo> <mn>2</mn> <mi>k</mi> <mi>π</mi> <mo>/</mo> <mn>3</mn> <mo>)</mo> </mrow> <mo>,</mo> <mrow> <mo>(</mo> <mi>π</mi> <mo>/</mo> <mn>2</mn> <mo>,</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> <mo>)</mo> </mrow> <mo>,</mo> <mo>…</mo> </mrow> </semantics></math>. The two dashed vertical lines (<math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>) as well as the horizontal bands (<math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> </mrow> </semantics></math>) indicate the parameter regime considered for the computation of the first hitting return time on <math display="inline"><semantics> <mrow> <mi>I</mi> <mi>B</mi> <msub> <mi>M</mi> <mi>S</mi> </msub> <mi>h</mi> <mi>e</mi> <mi>r</mi> <mi>b</mi> <mi>r</mi> <mi>o</mi> <mi>o</mi> <mi>k</mi> <mi>e</mi> </mrow> </semantics></math>. The phase factor matching diagram is obtained experimentally by studying the dark states (on-site protocol) in Figure 5c.</p>
Full article ">Figure 3
<p>(<b>a</b>) Classical simulation of the mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> for the on-site protocol as a function of <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and <math display="inline"><semantics> <mi>α</mi> </semantics></math>. For <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, three phase factors match (dark blue), for <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, two phase factors match (medium blue) and for <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>, all phase factors are different (white). The paths through the parameter space labeled as (I), (II), (III) and (IV) are indicated with red dashed lines and correspond to (<b>c</b>–<b>f</b>), respectively. Compared to the phase factor matching diagram in <a href="#entropy-26-00869-f002" class="html-fig">Figure 2</a>, the lines are broadened due to finite <span class="html-italic">N</span>. (<b>b</b>) Quantum circuit for two qubits representing the three localized states for the on-site protocol with the initial state <math display="inline"><semantics> <mrow> <mrow> <mo>|</mo> <mn mathvariant="bold">0</mn> <mo>〉</mo> </mrow> <mo>=</mo> <mrow> <mo>|</mo> <mn>01</mn> <mo>〉</mo> </mrow> </mrow> </semantics></math>, where the unitary <math display="inline"><semantics> <mrow> <mi>U</mi> <mo>=</mo> <mo form="prefix">exp</mo> <mrow> <mo>(</mo> <mo>−</mo> <mi>i</mi> <mi>H</mi> <mi>τ</mi> <mo>)</mo> </mrow> </mrow> </semantics></math> and measurements are applied alternately. Only the upper qubit is measured, since we need to detect the state <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">0</mn> <mo>〉</mo> </mrow> </semantics></math> while we do not want to receive the information that allows us to distinguish the states <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">1</mn> <mo>〉</mo> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">2</mn> <mo>〉</mo> </mrow> </semantics></math>. (<b>c</b>–<b>f</b>) Mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> recorded on IBM Sherbrooke (light blue circles), obtained with the asymptotic theory for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>→</mo> <mo>∞</mo> </mrow> </semantics></math> (black solid lines) and simulated for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> (blue dashed lines): (<b>c</b>) [path (I)] <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> versus <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>. (<b>d</b>) [path (II)] When <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>, we almost always find <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>. As explained in the text, this is related to the removal of energy-level degeneracy when the magnetic flux is turned on. Note that some fine structure details predicted by the asymptotic theory, for <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>, are washed out in the experiment, see the three nearby dips that merge into one resonance here. (<b>e</b>) [path (III)] Mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> as a function of <math display="inline"><semantics> <mi>α</mi> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> </mrow> </semantics></math>. <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> develops a plateau, as well as additional transitions that are absent for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>→</mo> <mo>∞</mo> </mrow> </semantics></math>. (<b>f</b>) [path (IV)] Mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> </mrow> </semantics></math> as a function of <math display="inline"><semantics> <mi>α</mi> </semantics></math>. In this example, clearly the asymptotic theory is not predictive, while finite time simulations agree with experiments.</p>
Full article ">Figure 4
<p>(<b>a</b>) Classical simulation of the mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> for the tracking protocol as a function of <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and <math display="inline"><semantics> <mi>α</mi> </semantics></math>. For <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, three phase factors match (dark blue), and for <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>, all phase factors are different (white). Paths through the parameter space labeled (I), (II), (III) and (IV) are indicated with red dashed lines and correspond to (<b>c</b>–<b>f</b>), respectively. Compared to the phase factor matching diagram in <a href="#entropy-26-00869-f002" class="html-fig">Figure 2</a>, the dark blue areas are broadened due to finite <span class="html-italic">N</span>. (<b>b</b>) Quantum circuit for two qubits representing the three localized states for the tracking protocol with the initial state <math display="inline"><semantics> <mrow> <mrow> <mo>|</mo> <mn mathvariant="bold">0</mn> <mo>〉</mo> </mrow> <mo>=</mo> <mrow> <mo>|</mo> <mn>00</mn> <mo>〉</mo> </mrow> </mrow> </semantics></math>, where the unitary <math display="inline"><semantics> <mrow> <mi>U</mi> <mo>=</mo> <mo form="prefix">exp</mo> <mrow> <mo>(</mo> <mo>−</mo> <mi>i</mi> <mi>H</mi> <mi>τ</mi> <mo>)</mo> </mrow> </mrow> </semantics></math> and the measurements are applied alternately. (<b>c</b>–<b>f</b>) Mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> recorded on IBM Sherbrooke (light blue circles), obtained with the asymptotic theory for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>→</mo> <mo>∞</mo> </mrow> </semantics></math> (black solid line) and simulated for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> (blue dashed line): (<b>c</b>) [path (I)] <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> versus <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>. <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> is quantized (<math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>), and its value, for almost any choice of <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math>, differs by unity from the on-site measurement protocol, the case presented in <a href="#entropy-26-00869-f003" class="html-fig">Figure 3</a>c when <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>. (<b>d</b>) [path (II)] For finite magnetic flux <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>, the transitions to <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> are absent except in the Zeno limit at <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>→</mo> <mo>∞</mo> </mrow> </semantics></math>. This is different for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math>. The result for <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math> shows a transition to approximately <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> at <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3.63</mn> </mrow> </semantics></math>. (<b>e</b>) [path (III)] Mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> </mrow> </semantics></math>. For <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> develops additional transitions that are absent for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>→</mo> <mo>∞</mo> </mrow> </semantics></math> (<b>f</b>) [path (IV)] Mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> </mrow> </semantics></math> as a function of <math display="inline"><semantics> <mi>α</mi> </semantics></math>. We see a clear broadening effect of the resonance, while in (<b>d</b>,<b>e</b>), broadened resonances show up, which are not present in the asymptotic theory.</p>
Full article ">Figure 5
<p>Detection probability <math display="inline"><semantics> <mrow> <mn>0</mn> <mo>≤</mo> <msub> <mi>P</mi> <mi>det</mi> </msub> <mo>≤</mo> <mn>1</mn> </mrow> </semantics></math> as a function of the sampling time <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and the phase <math display="inline"><semantics> <mi>ϕ</mi> </semantics></math> as well as <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and magnetic flux <math display="inline"><semantics> <mi>α</mi> </semantics></math> obtained from IBM Sherbrooke with <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math> for the on-site and tracking protocol. The dark blue color corresponds to <math display="inline"><semantics> <mrow> <msub> <mi>P</mi> <mi>det</mi> </msub> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math> (dark state), while the white color corresponds to <math display="inline"><semantics> <mrow> <msub> <mi>P</mi> <mi>det</mi> </msub> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> (bright state). (<b>a</b>) <math display="inline"><semantics> <msub> <mi>P</mi> <mi>det</mi> </msub> </semantics></math> as a function of <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and <math display="inline"><semantics> <mi>ϕ</mi> </semantics></math> for the on-site protocol. Dark states are found when <math display="inline"><semantics> <mrow> <mi>ϕ</mi> <mo>=</mo> <mi>π</mi> </mrow> </semantics></math> is the result of destructive interference and for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>→</mo> <mn>0</mn> </mrow> </semantics></math> due to the Zeno effect. Additional horizontal bands show dark states, which are found when the time of revival in the initial state is the same as the sampling time <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>. (<b>b</b>) <math display="inline"><semantics> <msub> <mi>P</mi> <mi>det</mi> </msub> </semantics></math> as a function of <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and <math display="inline"><semantics> <mi>ϕ</mi> </semantics></math> (<math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>) for the tracking protocol. The dark states found for <math display="inline"><semantics> <mrow> <mi>ϕ</mi> <mo>=</mo> <mi>π</mi> </mrow> </semantics></math> for the on-site protocol turn bright when the tracking method is used, since the latter breaks spatial symmetry, while the former does not. The horizontal dark bands are due to revivals that forbid detection of the system in the target state. (<b>c</b>,<b>d</b>) <math display="inline"><semantics> <msub> <mi>P</mi> <mi>det</mi> </msub> </semantics></math> as a function of <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and magnetic flux <math display="inline"><semantics> <mi>α</mi> </semantics></math> (<math display="inline"><semantics> <mrow> <mi>ϕ</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>). The on-site protocol (<b>c</b>) and the tracking protocol (<b>d</b>) exhibit vastly different trends, i.e., dark states are present in the tracking protocol where three phase factors match and in the on-site protocol where two and three phase factors match. As explained in the text, (<b>c</b>) yields the phase factor matching diagram shown in <a href="#entropy-26-00869-f002" class="html-fig">Figure 2</a>, while (<b>d</b>) corresponds to three phase factors matching, which are indicated by blue circles in <a href="#entropy-26-00869-f002" class="html-fig">Figure 2</a>.</p>
Full article ">Figure 6
<p>Simulation of the difference of the total detection probability <math display="inline"><semantics> <mrow> <mi mathvariant="sans-serif">Δ</mi> <msub> <mi>P</mi> <mi>det</mi> </msub> <mo>=</mo> <msub> <mi>P</mi> <mi>det</mi> </msub> <mrow> <mo>(</mo> <mrow> <mrow> <mo>|</mo> </mrow> <msub> <mi>ψ</mi> <mi>in</mi> </msub> <mrow> <mo>〉</mo> </mrow> </mrow> <mo>=</mo> <mrow> <mo>|</mo> <mn mathvariant="bold">1</mn> <mo>〉</mo> </mrow> <mo>)</mo> </mrow> <mo>−</mo> <msub> <mi>P</mi> <mi>det</mi> </msub> <mrow> <mo>(</mo> <mrow> <mrow> <mo>|</mo> </mrow> <msub> <mi>ψ</mi> <mi>in</mi> </msub> <mrow> <mo>〉</mo> </mrow> </mrow> <mo>=</mo> <mrow> <mo>|</mo> <mn mathvariant="bold">2</mn> <mo>〉</mo> </mrow> <mo>)</mo> </mrow> </mrow> </semantics></math> with the different initial states <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">1</mn> <mo>〉</mo> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mo>|</mo> <mn mathvariant="bold">2</mn> <mo>〉</mo> </mrow> </semantics></math>, which are not the target states as a function of the sampling time <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math>, and magnetic flux <math display="inline"><semantics> <mi>α</mi> </semantics></math> (<math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math>) for the on-site (<b>upper panel</b>) and tracking protocol (<b>lower panel</b>).</p>
Full article ">Figure 7
<p>Simulation of the mean return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> versus <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> </mrow> </semantics></math> and <span class="html-italic">N</span> for <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>. (<b>a</b>) For <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> (red dashed line), the fine structure at <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>≈</mo> <mn>3.49</mn> <mo>,</mo> <mspace width="4pt"/> <mn>3.63</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mn>3.78</mn> </mrow> </semantics></math> predicted by asymptotic theory <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>→</mo> <mo>∞</mo> </mrow> </semantics></math> is washed out, unlike the case where <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math> (blue solid line). (<b>b</b>) At <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3.63</mn> </mrow> </semantics></math>, a transition from <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math> to <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and back is present for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> (red dashed line), which is absent for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math> (blue solid line). (<b>c</b>) Mean <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> versus <span class="html-italic">N</span> for <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>≈</mo> <mn>3.63</mn> </mrow> </semantics></math> (blue solid line, on-site protocol), <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <mo>(</mo> <mo form="prefix">sin</mo> <mo>(</mo> <mn>0.5</mn> <mo>+</mo> <mi>π</mi> <mo>/</mo> <mn>6</mn> <mo>)</mo> <mo>+</mo> <mo form="prefix">cos</mo> <mo>(</mo> <mn>0.5</mn> <mo>)</mo> <mo>)</mo> </mrow> </semantics></math> (green dotted-dashed line, tracking protocol) and <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <mo>(</mo> <mo form="prefix">sin</mo> <mo>(</mo> <mn>0.5</mn> <mo>+</mo> <mi>π</mi> <mo>/</mo> <mn>6</mn> <mo>)</mo> <mo>+</mo> <mo form="prefix">cos</mo> <mo>(</mo> <mn>0.5</mn> <mo>)</mo> <mo>)</mo> </mrow> </semantics></math> (red dashed line, on-site protocol). For an increasing number of midcircuit measurements, there is a transition from <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> to <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math> (tracking protocol) that drives the system to the high-temperature limit. For the on-site protocol exactly at <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <mo>(</mo> <mo form="prefix">sin</mo> <mo>(</mo> <mn>0.5</mn> <mo>+</mo> <mi>π</mi> <mo>/</mo> <mn>6</mn> <mo>)</mo> <mo>+</mo> <mo form="prefix">cos</mo> <mo>(</mo> <mn>0.5</mn> <mo>)</mo> <mo>)</mo> </mrow> </semantics></math>, a crossover is observed from <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> to <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, and for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>≈</mo> <mn>3.63</mn> </mrow> </semantics></math>, a crossover between three topological phases from <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> to <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 8
<p>(<b>a</b>) The transition from <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math> to <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and back is widened due to the finite time of the experiment. We compare IBM quantum processor results (light blue circles) and theory <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>2</mn> <mo>−</mo> <mo form="prefix">exp</mo> <mo>(</mo> <mo>−</mo> <mi>b</mi> <mo>)</mo> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mi>b</mi> <mo>)</mo> </mrow> </semantics></math> with <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mi>N</mi> <mrow> <mo>(</mo> <mn>2</mn> <mo>/</mo> <mn>9</mn> <mo>)</mo> </mrow> <msup> <mrow> <mo>(</mo> <mn>3</mn> <mi>γ</mi> <mi>τ</mi> <mo>−</mo> <mn>2</mn> <mi>π</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> (red dashed line) and simulation (blue solid line). (<b>b</b>) The transition from <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math> to <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> and back is widened due to the finite time of the experiment. We compare IBM quantum processor results (light blue circles) and theory <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> <mo>=</mo> <mn>3</mn> <mo>−</mo> <mn>2</mn> <mo form="prefix">exp</mo> <mo>(</mo> <mo>−</mo> <mi>b</mi> <mo>/</mo> <mn>2</mn> <mo>)</mo> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mi>b</mi> <mo>/</mo> <mn>2</mn> <mo>)</mo> </mrow> </semantics></math> with <math display="inline"><semantics> <mrow> <mi>b</mi> <mo>=</mo> <mi>N</mi> <mrow> <mo>(</mo> <mn>2</mn> <mo>/</mo> <mn>9</mn> <mo>)</mo> </mrow> <msup> <mrow> <mo>(</mo> <mn>3</mn> <mi>γ</mi> <mi>τ</mi> <mo>−</mo> <mn>2</mn> <mi>π</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> (red dashed line) and simulation (blue solid line).</p>
Full article ">Figure 9
<p>The null measurement probability versus <span class="html-italic">N</span> for <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math> for the tracking and on-site protocol. The parameters for the tracking protocol are <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3.63</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math> (magenta, dashed), and <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math> (grey, dashed dotted), and for the on-site protocol <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3.63</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math> (black, dotted), and <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math> (blue, solid). The null measurement rate slows down considerably near special sampling rates at <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>γ</mi> <mi>τ</mi> <mo>,</mo> <mi>α</mi> <mo>)</mo> <mo>=</mo> <mo>(</mo> <mn>3.63</mn> <mo>,</mo> <mn>0.5</mn> <mo>)</mo> </mrow> </semantics></math> for both protocols.</p>
Full article ">Figure 10
<p>Mean first return time <math display="inline"><semantics> <mrow> <mo>〈</mo> <mi>n</mi> <mo>〉</mo> </mrow> </semantics></math> as a function of <span class="html-italic">N</span> for <math display="inline"><semantics> <mrow> <mi>p</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math> (black dotted line), <math display="inline"><semantics> <mrow> <mi>p</mi> <mo>=</mo> <mn>1</mn> <mo>%</mo> </mrow> </semantics></math> (blue solid line) and <math display="inline"><semantics> <mrow> <mi>p</mi> <mo>=</mo> <mn>5</mn> <mo>%</mo> </mrow> </semantics></math> (red dashed line). The measurement protocols and parameters are (<b>a</b>) on-site, <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, on-site, (<b>b</b>) on-site <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, and (<b>c</b>) tracking, <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>.</p>
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<p>(<b>a</b>) Phase factor matching diagram and paths through the parameter space labeled (I), (II), (III), and (IV), which are indicated with red dashed lines and correspond to (<b>c</b>–<b>f</b>), respectively. The eigenvalues close to one lead to additional dips and plateaus in the mean return time, whereas the eigenvalues exactly equal to one indicate transitions for the theory <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>→</mo> <mo>∞</mo> </mrow> </semantics></math>. (<b>b</b>) Illustration of the on-site measurement protocol. (<b>c</b>–<b>f</b>) Eigenvalue spectrum of the survival operator for the same parameters used for the mean return time in <a href="#entropy-26-00869-f003" class="html-fig">Figure 3</a>. (<b>c</b>) For <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>, the eigenvalues are one for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <mn>3</mn> <mo>,</mo> <mn>4</mn> <mi>π</mi> <mo>/</mo> <mn>3</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mn>6</mn> <mi>π</mi> <mo>/</mo> <mn>3</mn> </mrow> </semantics></math>, leading to transitions in the mean return time [path (I)]. (<b>d</b>) For <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>, the eigenvalues are one for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>≈</mo> <mn>0</mn> <mo>,</mo> <mn>1.82</mn> <mo>,</mo> <mn>3.50</mn> <mo>,</mo> <mn>3.62</mn> <mo>,</mo> <mn>3.78</mn> <mo>,</mo> <mn>5.44</mn> </mrow> </semantics></math>. The three eigenvalues <math display="inline"><semantics> <mrow> <mo>|</mo> <mi>λ</mi> <mo>|</mo> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>≈</mo> <mn>3.50</mn> <mo>,</mo> <mn>3.62</mn> <mo>,</mo> <mn>3.78</mn> </mrow> </semantics></math> are very close, so almost three phase factors match, leading to a transition to one of the mean return times [path (II)]. In (<b>e</b>) [path (III)] and (<b>f</b>) [path (IV)], <math display="inline"><semantics> <mrow> <mo>|</mo> <mi>λ</mi> <mo>|</mo> </mrow> </semantics></math> is close to one between <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>≈</mo> <mn>0.3</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>≈</mo> <mn>0.7</mn> </mrow> </semantics></math> leading to a plateau for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math>.</p>
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<p>(<b>a</b>) Phase factor matching diagram and paths through the parameter space labeled (I), (II), (III), and (IV), which are indicated with red dashed lines and correspond to (<b>c</b>–<b>f</b>), respectively. (<b>b</b>) Illustration of the tracking protocol. (<b>c</b>–<b>f</b>) The eigenvalues of <math display="inline"><semantics> <msub> <mi>G</mi> <mi>tar</mi> </msub> </semantics></math> for the same parameters as the mean return time in <a href="#entropy-26-00869-f004" class="html-fig">Figure 4</a>. Two nearly degenerate eigenvalues close to one lead to additional dips in the mean return time, while two degenerate eigenvalues exactly at one indicate transitions for the theory <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>→</mo> <mo>∞</mo> </mrow> </semantics></math>. (<b>c</b>) For <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>, the eigenvalues are degenerate, and one for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <mn>3</mn> <mo>,</mo> <mn>4</mn> <mi>π</mi> <mo>/</mo> <mn>3</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mn>6</mn> <mi>π</mi> <mo>/</mo> <mn>3</mn> </mrow> </semantics></math>, which leads to transitions of the mean return time [path (I)]. (<b>d</b>) For <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3.63</mn> </mrow> </semantics></math>, the eigenvalues are almost degenerate and one, which leads to a transition for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math> due to finite resolution effects [path (II)]. (<b>e</b>) For <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>3</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> </mrow> </semantics></math>, the eigenvalues are almost degenerate and one for <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>≈</mo> <mn>0.3</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>≈</mo> <mn>0.7</mn> </mrow> </semantics></math> [path (III)]. (<b>f</b>) For <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mn>2</mn> <mi>π</mi> <mo>/</mo> <msqrt> <mn>3</mn> </msqrt> </mrow> </semantics></math>, the eigenvalues are degenerate and one for <math display="inline"><semantics> <mrow> <mi>γ</mi> <mi>τ</mi> <mo>=</mo> <mi>π</mi> <mo>/</mo> <mn>6</mn> </mrow> </semantics></math> indicating a transition for all <span class="html-italic">N</span> [path (IV)].</p>
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<p>The same as <a href="#entropy-26-00869-f005" class="html-fig">Figure 5</a> but as a simulation. We observe that the experiment and the simulations agree very well for <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math>.</p>
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10 pages, 1699 KiB  
Article
Development of Malate Biosensor-Containing Hydrogels and Living Cell-Based Sensors
by Nathan J. Ricks, Monica Brachi, Kevin McFadden, Rohit G. Jadhav, Shelley D. Minteer and Ming C. Hammond
Int. J. Mol. Sci. 2024, 25(20), 11098; https://doi.org/10.3390/ijms252011098 (registering DOI) - 16 Oct 2024
Abstract
Malate is a key intermediate in the citric acid cycle, an enzymatic cascade that is central to cellular energy metabolism and that has been applied to make biofuel cells. To enable real-time sensing of malate levels, we have engineered a genetically encoded, protein-based [...] Read more.
Malate is a key intermediate in the citric acid cycle, an enzymatic cascade that is central to cellular energy metabolism and that has been applied to make biofuel cells. To enable real-time sensing of malate levels, we have engineered a genetically encoded, protein-based fluorescent biosensor called Malon specifically responsive to malate by performing structure-based mutagenesis of the Cache-binding domain of the Citron GFP-based biosensor. Malon demonstrates high specificity and fluorescence activation in response to malate, and has been applied to monitor enzymatic reactions in vitro. Furthermore, we successfully incorporated Malon into redox polymer hydrogels and bacterial cells, enabling analysis of malate levels in these materials and living systems. These results show the potential for fluorescent biosensors in enzymatic cascade monitoring within biomaterials and present Malon as a novel tool for bioelectronic devices. Full article
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Graphical abstract

Graphical abstract
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<p>Design and characterization of DcuS–cpGFP and Malon biosensors for malate. (<b>A</b>) The malate responsive Cache domain, DcuS, was linked to GFP to generate DcuS–cpGFP. Alternatively, the DcuS-binding pocket was grafted to the previously engineered Citron biosensor to generate Malon. (<b>B</b>) Normalized fluorescence response in vitro for biosensors to 100 mM of malate or other Krebs cycle intermediates. (<b>C</b>) Fluorescence binding assays to determine binding affinities.</p>
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<p>In vitro enzyme assays were analyzed with Malon. (<b>A</b>) Schematic of the enzyme reactions being assessed. Fumarase converts fumarate to malate, and malate dehydrogenase (MDH) oxidizes malate to oxaloacetate by reducing NAD<sup>+</sup> to NADH, or vice versa. (<b>B</b>) Malon fluorescence in enzyme reactions with fumarate and 0, 100 nM, or 1 μM fumarase, compared to direct detection of 15 mM malate. (<b>C</b>) Malon fluorescence in enzyme reactions with 0 or 1 μM MDH pre-equilibrated with malate upon NAD<sup>+</sup> injection. (<b>D</b>) Same as part C, except pre-equilibrated with oxaloacetate upon NADH injection.</p>
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<p>Application of Malon to generate malate-sensing hydrogels and living cells. (<b>A</b>,<b>B</b>) Transparent ITO electrodes were coated with the crosslinked NQ-LPEI hydrogel polymer premixed with the Malon sensor and placed in a transparent well immersed in phosphate buffer solution pH 7.5 and visualized with a fluorescence confocal microscope before (<b>A</b>) and after (<b>B</b>) the addition of 50 mM malate. (<b>C</b>) Quantitation of mean fluorescence on electrodes before and after malate addition (also see <a href="#app1-ijms-25-11098" class="html-app">Figure S8</a>). (<b>D</b>) The <span class="html-italic">E. coli</span> CitT transporter is an antiporter that transports malate and other C4 dicarboxylic acids into the cell. (<b>E</b>) Cellular fluorescence measured by flow cytometry of <span class="html-italic">E. coli</span> cells expressing Malon and induced with varying amounts of IPTG for CitT overexpression in the presence of 20 mM malate. Shown are data for three biological replicates with standard deviation.</p>
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14 pages, 848 KiB  
Review
The Emerging Applications of Raman Spectroscopy in Clinical Oncology: A Narrative Review Focused on Circulating Tumor DNA Detection and Therapeutic Drug Monitoring
by Sathya Narayanan, Yuling Wang and Howard Gurney
Onco 2024, 4(4), 335-348; https://doi.org/10.3390/onco4040023 (registering DOI) - 16 Oct 2024
Viewed by 139
Abstract
Raman spectroscopy is a technique which involves quantitative and qualitative molecular analysis based on the interaction between incident light and isolation of scattered wavelengths in generating a molecular fingerprint. It has a broad array of potential scientific applications, encompassing areas as diverse as [...] Read more.
Raman spectroscopy is a technique which involves quantitative and qualitative molecular analysis based on the interaction between incident light and isolation of scattered wavelengths in generating a molecular fingerprint. It has a broad array of potential scientific applications, encompassing areas as diverse as food science and forensics. However, it may also be highly useful in clinical oncology. A recent focus of research in oncology has been in achieving the individualisation of care. Two important strategies to achieve a so-called “precision oncology” approach may include the detection of circulating tumour DNA (ctDNA) in more objectively evaluating treatment response and guiding de-escalation and intensification approaches in systemic therapy and therapeutic drug monitoring (TDM). Therapeutic drug monitoring involves the quantitation of plasma drug levels in order to tailor medication dosing in optimizing outcomes. The existing approaches to characterize small molecules, such as fluorescence-based and chromatographic strategies, may be limited by high costs, long turnaround times, and bulky equipment. Surface-enhanced Raman spectroscopy (SERS) may be deployed by utilizing a handheld device, with the potential for point of care, rapid turnaround, low-cost assessment of clinically relevant parameters, and prompt implementation of attendant changes in treatment. Although there is a growing body of data supporting the implementation of TDM and evaluation of ctDNA in achieving precision medicine, the uptake of such approaches remains relatively limited outside of clinical trials. As stated, the nature of existing analytical methodologies may prove to be a significant barrier to the routine clinic-based implementation of such approaches. Therefore, we provide the existing evidence for SERS in alleviating these barriers. We also provide insights into how SERS could contribute to clinical oncology. Full article
(This article belongs to the Special Issue The Evolving Landscape of Contemporary Cancer Therapies)
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<p>Phenomenon of Raman scattering as an incident light source interacts with the analyte sample.</p>
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<p>Potential roles for ctDNA analysis in oncology.</p>
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20 pages, 4225 KiB  
Review
Strategic Integration: A Cross-Disciplinary Review of the fNIRS-EEG Dual-Modality Imaging System for Delivering Multimodal Neuroimaging to Applications
by Jiafa Chen, Kaiwei Yu, Yifei Bi, Xing Ji and Dawei Zhang
Brain Sci. 2024, 14(10), 1022; https://doi.org/10.3390/brainsci14101022 (registering DOI) - 16 Oct 2024
Viewed by 200
Abstract
Background: Recent years have seen a surge of interest in dual-modality imaging systems that integrate functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) to probe brain function. This review aims to explore the advancements and clinical applications of this technology, emphasizing the synergistic [...] Read more.
Background: Recent years have seen a surge of interest in dual-modality imaging systems that integrate functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) to probe brain function. This review aims to explore the advancements and clinical applications of this technology, emphasizing the synergistic integration of fNIRS and EEG. Methods: The review begins with a detailed examination of the fundamental principles and distinctive features of fNIRS and EEG techniques. It includes critical technical specifications, data-processing methodologies, and analysis techniques, alongside an exhaustive evaluation of 30 seminal studies that highlight the strengths and weaknesses of the fNIRS-EEG bimodal system. Results: The paper presents multiple case studies across various clinical domains—such as attention-deficit hyperactivity disorder, infantile spasms, depth of anesthesia, intelligence quotient estimation, and epilepsy—demonstrating the fNIRS-EEG system’s potential in uncovering disease mechanisms, evaluating treatment efficacy, and providing precise diagnostic options. Noteworthy research findings and pivotal breakthroughs further reinforce the developmental trajectory of this interdisciplinary field. Conclusions: The review addresses challenges and anticipates future directions for the fNIRS-EEG dual-modal imaging system, including improvements in hardware and software, enhanced system performance, cost reduction, real-time monitoring capabilities, and broader clinical applications. It offers researchers a comprehensive understanding of the field, highlighting the potential applications of fNIRS-EEG systems in neuroscience and clinical medicine. Full article
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<p>Comparison of the resolutions of commonly used functional brain-imaging techniques.</p>
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<p>fNIRS-EEG dual-modality imaging system fusion method for assessing brain functions.</p>
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<p>Accompanying symptoms of ADHD in children and adolescents.</p>
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<p>Visualization of the fNIRS-EEG dual-modality imaging system for diagnosing children with ADHD [<a href="#B29-brainsci-14-01022" class="html-bibr">29</a>]. (<b>a</b>) EEG electrodes were placed on the Fz (frontal), Pz (parietal), Oz (occipital) and Cz (central) locations according to the international 10–20 system. A band with optical fiber probes was placed on the forehead for fNIRS data acqusition. Data acquisition system has been shown on a control subject. (<b>b</b>) Spatial profiles of the fNIRS channels and the ROIs locations. (<b>c</b>) The source-detector and 16 optode (channel) measurement locations registered on fNIR probe. (<b>d</b>) The flowchart of the study (the signals belong to a random control and ADHD subject). (<b>e</b>) ROC Curve for MLP (AUC = 0.92). (<b>f</b>) ROC Curve for SVM (AUC = 0.859). (<b>g</b>) ROC Curve for NB (AUC = 0.937).</p>
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<p>Visualization of the fNIRS-EEG dual-modality imaging system for studying IQ estimation [<a href="#B49-brainsci-14-01022" class="html-bibr">49</a>]. (<b>a</b>) The overall scheme of the IQ estimation procedure. (<b>b</b>) IQ Experiment Flowchart. (<b>c</b>) the location of EEG electrodes. (<b>d</b>) fNIRS Optodes placement (<b>e</b>) channel configuration for problem solving task.</p>
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<p>Visualization of the fNIRS-EEG dual-modality imaging system for studying infantile spasms [<a href="#B57-brainsci-14-01022" class="html-bibr">57</a>]. (<b>a</b>) fNIRS: a patch composed of four pairs of optical fibers (each wavelength corresponds to one thread in each team), containing four transmitters and one detector. (<b>b</b>) fNIRS: a detector has been positioned in the middle of the forehead. (<b>c</b>) fNIRS: Hemodynamics observed over multiple distances via fNIRS spectroscopic technique graphs. (<b>d</b>) fNIRS: Normalized range values of [HbO] for the four source-detector distances in the period of −5 to 25 s vs source-detector distances (1.5, 2, 2.5, 3 cm) for the 6 patients. (<b>e</b>) EEG: layout of nine electrodes (10–20 system configurations, with a frontal reference). (<b>f</b>) A time-frequency response (TFR) of the deltoid EMG determined the onset of each infantile spasms (T0). infantile spasms onset was always characterized by a sudden increase in the deltoid EMG power of all frequency bands between 0 and 100 Hz. (<b>g</b>) A two-phase hemodynamic change started with the onset of EMG activation (as determined in a time-frequency analysis).</p>
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<p>Visualization of the fNIRS-EEG dual-modality imaging system for the study of epilepsy [<a href="#B67-brainsci-14-01022" class="html-bibr">67</a>]. (<b>a</b>) Sketch plot of the patient evaluation, continuous encephalography and fNIRS data acquisition, and data analysis procedures (<b>b</b>) Hemodynamic changes associated with nonconvulsive seizures. (<b>c</b>) Hemodynamic changes associated with BS bursts. (<b>d</b>) Hemodynamic changes associated with burst suppression suppressions. (<b>e</b>) Hemodynamic changes associated with periodic discharges.</p>
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<p>Visualization of the fNIRS-EEG dual-modality imaging system for studying depth of anesthesia [<a href="#B69-brainsci-14-01022" class="html-bibr">69</a>]. (<b>a</b>) Proposed multimodal anesthesia depth monitoring system. (<b>b</b>) Clinical trial environment. (<b>c</b>) Flowchart of the deep-learning algorithm. (<b>d</b>) Clinical results for propofol-induced general anes-thesia and ketamine-induced general anesthesia.</p>
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20 pages, 1849 KiB  
Article
Diffusion Augmented Complex Inverse Square Root for Adaptive Frequency Estimation over Distributed Networks
by Pucha Song, Jinghua Ye, Kang Yan and Zhengyan Luo
Symmetry 2024, 16(10), 1375; https://doi.org/10.3390/sym16101375 (registering DOI) - 16 Oct 2024
Viewed by 186
Abstract
Using adaptive filtering to estimate the frequency of power systems has become a popular trend. In recent years, however, few studies have been performed on adaptive frequency estimations in non-stationary noise environments. In this paper, we propose the distributed complex inverse square root [...] Read more.
Using adaptive filtering to estimate the frequency of power systems has become a popular trend. In recent years, however, few studies have been performed on adaptive frequency estimations in non-stationary noise environments. In this paper, we propose the distributed complex inverse square root algorithm and distributed augmented complex inverse square root algorithm for the frequency estimation of power systems based on the widely linear model and the inverse square root cost function, where the function can restrain both positive and negative large errors, based on its symmetry. Moreover, the wireless sensor networks support monitoring and adaptation for the frequency estimation in the distributed networks, and the proposed approach can ensure good robustness of the balanced or unbalanced three-phase power system with the help of a local complex-value voltage signal generated by Clark’s transformation. In addition, the bound of step size is driven by the global vectors, and that low computation complexity do not hinder those performances. The results of several experiments demonstrate that our algorithms can effectively estimate the frequency in impulsive noise environments. Full article
(This article belongs to the Section Computer)
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<p>The experimental flow of the frequency estimation.</p>
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<p>The links of the cost function with different <math display="inline"><semantics> <mi>λ</mi> </semantics></math>.</p>
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<p>The structure of distributed network.</p>
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<p>The variance of frequency estimation both D-CISR and CISR algorithms with <math display="inline"><semantics> <mrow> <mi>S</mi> <mi>N</mi> <mi>R</mi> <mo>=</mo> <mn>40</mn> </mrow> </semantics></math> dB, <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>.</p>
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<p>The variance of frequency estimation both D-ACISR and ACISR algorithms with <math display="inline"><semantics> <mrow> <mi>S</mi> <mi>N</mi> <mi>R</mi> <mo>=</mo> <mn>50</mn> </mrow> </semantics></math> dB, <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>.</p>
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<p>The frequency estimation links of D-CISR and the existing algorithms with <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>.</p>
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<p>The frequency estimation links of D-ACISR and the existing algorithms with <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>.</p>
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<p>The global variance and bias of frequency estimation in unbalanced condition with <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>.</p>
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<p>The global variance and bias of frequency estimation in balanced condition with <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>.</p>
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<p>The performances of the proposed algorithms with the mutation of frequency, <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>.</p>
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<p>The links of the proposed algorithms with a ramp change in frequency, <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>.</p>
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<p>The links of the proposed algorithms with a ramp change in frequency, <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>r</mi> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>.</p>
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<p>Frequency tracking links for a real-world unbalanced three-phase system. (<b>a</b>) The real data of the unbalanced three-phase voltage; (<b>b</b>) the curves of tracking performance for all algorithms.</p>
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16 pages, 2895 KiB  
Article
Accuracy Assessment of NOAA IMS 4 km Products on the Tibetan Plateau with Landsat-8 OLI Images
by Duo Chu
Atmosphere 2024, 15(10), 1234; https://doi.org/10.3390/atmos15101234 (registering DOI) - 15 Oct 2024
Viewed by 236
Abstract
The NOAA IMS (Interactive Multisensor Snow and Ice Mapping System) is a blended snow and ice product based on active and passive satellite sensors, ground observation, and other auxiliary information, providing the daily cloud-free snow cover extent in the Northern Hemisphere (NH) and [...] Read more.
The NOAA IMS (Interactive Multisensor Snow and Ice Mapping System) is a blended snow and ice product based on active and passive satellite sensors, ground observation, and other auxiliary information, providing the daily cloud-free snow cover extent in the Northern Hemisphere (NH) and having great application potential in snow cover monitoring and research in the Tibetan Plateau (TP). However, accuracy assessment of products is crucial for various aspects of applications. In this study, Landsat-8 OLI images were used to evaluate and validate the accuracy of IMS products in snow cover monitoring on the TP. The results show that (1) average overall accuracy of IMS 4 km products is 76.0% and average mapping accuracy is 88.3%, indicating that IMS 4 km products are appropriate for large-scale snow cover monitoring on the TP. (2) IMS 4 km products tend to overestimate actual snow cover on the TP, with an average commission rate of 45.4% and omission rate of 11.7%, and generally present that the higher the proportion of snow-covered area, the lower the probability of omission rate and the higher the probability of commission rate. (3) Mapping accuracy of IMS 4 km snow cover on the TP generally is higher at the high altitudes, and commission and omission errors increase with the decrease of elevation. (4) Compared with less regional representativeness of ground observations, the spatial characteristics of snow cover based on high-resolution remote sensing data are much more detailed, and more reliable verification results can be obtained. (5) In addition to commission and omission error metrics, the overall accuracy and mapping accuracy based on the reference image instead of classified image can better reveal the general monitoring accuracy of IMS 4 km products on the TP area. Full article
(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)
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<p>Study area and location of Landsat-8 OLI images selected for validation. The background image is snow cover extent from IMS 4 km products on 25 December 2018.</p>
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<p>IMS 4 km snow cover extent in the NH on 25 February 2018.</p>
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<p>First 10 Landsat-8 band 6-3-2 composite images (<b>a1</b>,<b>a2</b>) and corresponding snow cover maps at 1 km spatial resolution of Landsat-8 (<b>b1</b>,<b>b2</b>) and IMS (<b>c1</b>,<b>c2</b>) in row. The date, path, and row of Landsat-8 OLI images are shown at the top of images.</p>
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<p>Overall accuracy of IMS 4 km products on the TP based on Landsat-8 images.</p>
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<p>Omission and commission errors of IMS 4 km products on the TP based on Landsat-8 images.</p>
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<p>(<b>a</b>) Spatial distribution of accuracy errors of IMS 4 km products on 8 January 2018. (<b>b</b>) Accuracy errors of IMS 4 km products along with elevations on 8 January 2018.</p>
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<p>(<b>a</b>) Spatial distribution of accuracy errors of IMS 4 km products on 19 January 2017. (<b>b</b>) Accuracy errors of IMS 4 km products along with elevations on 19 January 2017.</p>
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13 pages, 950 KiB  
Article
Application of Quantitative Magnetic Resonance Imaging (QMRI) to Evaluate the Effectiveness of Ultrasonic Atomization of Water in Truffle Preservation
by Alessia Marino, Marco Leonardi, Alessandra Zambonelli, Mirco Iotti and Angelo Galante
J. Fungi 2024, 10(10), 717; https://doi.org/10.3390/jof10100717 (registering DOI) - 15 Oct 2024
Viewed by 224
Abstract
Truffles of the Tuber genus (Pezizales, Ascomycetes) are among the most valuable and expensive foods, but their shelf life is limited to 7–10 days when stored at 4 °C. Alternative preservation methods have been proposed to extend their shelf life, though they may [...] Read more.
Truffles of the Tuber genus (Pezizales, Ascomycetes) are among the most valuable and expensive foods, but their shelf life is limited to 7–10 days when stored at 4 °C. Alternative preservation methods have been proposed to extend their shelf life, though they may alter certain quality parameters. Recently, a hypogeal display case equipped with an ultrasonic humidity system (HDC) was developed, extending the shelf life to 2–3 weeks, depending on the truffle species. This study assesses the efficacy of HDC in preserving Tuber melanosporum and Tuber borchii ascomata over 16 days, using quantitative magnetic resonance imaging (QMRI) to monitor water content and other parameters. Sixteen T. melanosporum and six T. borchii ascomata were stored at 4 °C in an HDC or a static fridge (SF) as controls. QMRI confirmed that T. borchii has a shorter shelf life than T. melanosporum under all conditions. HDC reduced the rate of shrinkage, water, and mass loss in both species. Additionally, the Apparent Diffusion Coefficient (ADC), longitudinal relaxation time (T1), and transverse relaxation time (T2), which reflect molecular changes, decreased more slowly in HDC than SF. QMRI proves useful for studying water-rich samples and assessing truffle preservation technologies. Further optimization of this method for industrial use is needed. Full article
(This article belongs to the Special Issue New Perspectives on Tuber Fungi)
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<p>Variation in ascoma parameters and associated trend lines throughout the period of MRI investigation. (<b>a</b>) ascoma mass of <span class="html-italic">T. borchii</span>; (<b>b</b>) ascoma mass of <span class="html-italic">T. melanosporum</span>; (<b>c</b>) MRI-estimated volume of <span class="html-italic">T. borchii</span> ascomata; (<b>d</b>) MRI-estimated volume of <span class="html-italic">T. melanosporum</span> ascomata; (<b>e</b>) free water fraction of <span class="html-italic">T. borchii</span> ascomata; (<b>f</b>) free water fraction of <span class="html-italic">T. melanosporum</span> ascomata. Data from ascomata preserved in the hypogeal display case (HDC) and the static fridge (SF) are visualized in grey (triangles and dotted line) and black (circles and solid line), respectively.</p>
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<p>Comparison of ascoma mass (<b>a</b>,<b>b</b>), MRI-estimated volume (<b>c</b>,<b>d</b>) and free water fraction (<b>e</b>,<b>f</b>) percentage reduction between ascomata stored in the static fridge (SF, gray boxes) and the hypogeal display case (HDC, white boxes). (<b>a</b>,<b>c</b>,<b>e</b>) <span class="html-italic">T. borchii</span> ascomata; (<b>b</b>,<b>d</b>,<b>f</b>) <span class="html-italic">T. melanosporum</span> ascomata. Percentage reductions and statistics were calculated on the differences between values obtained in the first MRI round of measurement and those obtained in the following rounds. Symbols: <span class="html-italic">p</span> &lt; 0.06; * <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001; ns<sup>†</sup> <span class="html-italic">p</span> &lt; 0.07.</p>
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27 pages, 13145 KiB  
Article
Diagnosis, Management and Outcome of Truncus Arteriosus Communis Diagnosed during Fetal Life—Cohort Study and Systematic Literature Review
by Agnes Wittek, Ruben Plöger, Adeline Walter, Brigitte Strizek, Annegret Geipel, Ulrich Gembruch, Ricarda Neubauer and Florian Recker
J. Clin. Med. 2024, 13(20), 6143; https://doi.org/10.3390/jcm13206143 (registering DOI) - 15 Oct 2024
Viewed by 247
Abstract
Background/Objectives: Truncus arteriosus communis (TAC) is a rare congenital heart defect characterized by a single arterial trunk that supplies systemic, pulmonary, and coronary circulations. This defect, constituting approximately 1–4% of congenital heart diseases, poses significant challenges in prenatal diagnosis, management, and postnatal [...] Read more.
Background/Objectives: Truncus arteriosus communis (TAC) is a rare congenital heart defect characterized by a single arterial trunk that supplies systemic, pulmonary, and coronary circulations. This defect, constituting approximately 1–4% of congenital heart diseases, poses significant challenges in prenatal diagnosis, management, and postnatal outcomes. Methods: A retrospective analysis was conducted at the local tertiary referral center on cases of TAC diagnosed prenatally between 2019 and 2024. Additionally, a systematic literature review was performed to evaluate the accuracy of prenatal diagnostics and the presence of associated anomalies in fetuses with TAC and compare already published data with the local results. The review included studies that especially described the use of fetal echocardiography, the course and outcome of affected pregnancies, and subsequent management strategies. Results: The analysis of local prenatal diagnoses revealed 14 cases. Of the 11 neonates who survived to birth, the TAC diagnosis was confirmed in 7 instances. With all seven neonates undergoing surgery, the intention-to-treat survival rate was 86%, and the overall survival rate was 55%. By reviewing published case series, a total of 823 TAC cases were included in the analysis, of which 576 were diagnosed prenatally and 247 postnatally. The presence of associated cardiac and extracardiac manifestations as well as genetic anomalies was common, with a 22q11 microdeletion identified in 27% of tested cases. Conclusions: Advances in prenatal imaging and early diagnosis have enhanced the management of TAC, allowing for the detailed planning of delivery and immediate postnatal care in specialized centers. The frequent association with genetic syndromes underscores the importance of genetic counseling in managing TAC. An early surgical intervention remains crucial for improving long-term outcomes, although the condition is still associated with significant risks. Long-term follow-up studies are essential to monitor potential complications and guide future management strategies. Overall, a coordinated multidisciplinary approach from prenatal diagnosis to postnatal care is essential for improving outcomes for individuals with TAC. Full article
(This article belongs to the Special Issue Ultrasound Diagnosis of Obstetrics and Gynecologic Diseases)
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<p>(<b>a</b>,<b>b</b>): Truncus arteriosus type 1 at 31 + 4 weeks. (<b>a</b>) Perimembranous outlet VSD as interventricular communication with the broad common arterial trunk in the overriding position. (<b>b</b>) In the color Doppler mode, the filling of the common arterial trunk from both ventricles and the posterior branch of one pulmonary artery can be seen (aortic dominance); aliasing or a high variance, which indicates a stenosis of the truncal valve, is not present.</p>
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<p>(<b>a</b>–<b>c</b>): Truncus arteriosus type 1 at 22 + 0 weeks in B-mode (<b>a</b>,<b>b</b>) und with color doppler (<b>c</b>).</p>
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<p>(<b>a</b>,<b>b</b>): Truncus arteriosus type 4 with interrupted aortic arch type b at 23 + 5 weeks. (<b>a</b>) The 2DE shows the ventricular outlet part with the overriding common trunk, the truncal valve as well as the wide truncus pulmonalis and the hypoplastic ascending aorta (pulmonary dominance); (<b>b</b>) The color Doppler mode shows the outflow from both ventricles into the common arterial trunk and further into the pulmonary trunk as well as into the hypoplastic aorta.</p>
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<p>(<b>a</b>–<b>c</b>): Truncus arteriosus type 1 at 22 + 0 weeks. (<b>a</b>) In the color Doppler mode, the filling of the common arterial trunk from both ventricles and the confluent origin of both pulmonary arteries from the posterior side of the aorta is visualized (aortic dominance), as well as aliasing and high variance as indications of disturbed blood flow due to stenosis of the truncal valve. (<b>b</b>) The spectral Doppler examination confirms the presence of a stenotic truncal valve by a high maximum velocity (peak systolic velocity: 3.0 m/s; maximum pressure gradient (ΔPmax: 36 mm Hg) and wide variation of the blood flow. (<b>c</b>) In another fetus with truncus arteriosus type A2 at 34 + 1 weeks, there is both a relevant stenosis and a severe regurgitation of the truncal valve; during systole, the tubular antegrade flow with a peak velocity of 2.40 m/s can be recognized; during diastole, the insufficiency of the truncal valve with a peak velocity of 3.30 m/s can be recognized.</p>
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<p>Literature selection process according to PRISMA guidelines.</p>
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<p><b>Classification of TAC subtypes.</b> (<b>a</b>) Use of different classification systems by the included case series. (<b>b</b>) Number of different TAC subtypes in reviewed studies (including the cases of this study) using the modified Van Praagh classification in 2000 [<a href="#B9-jcm-13-06143" class="html-bibr">9</a>]. <b>Large aorta type (A1–2)</b>: TAC with confluent or near confluent pulmonary arteries (PA); <b>large aortic type of one PA (A3)</b>: TAC with absence of one unilateral proximal PA and the presence of ductus arteriosus or collateral arteries, which supply the lungs in the absence of a pulmonary artery branch from the truncus; <b>large pulmonary type (A4):</b> TAC with aortic hypoplasia resulting from interrupted aortic arch or severe aortic coarctation; A1–A4 refers to original Van Praagh classification [<a href="#B2-jcm-13-06143" class="html-bibr">2</a>], CE = Collet and Edwards, Types 1–3 [<a href="#B1-jcm-13-06143" class="html-bibr">1</a>].</p>
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<p>Assignment of TAC cases in the included studies [<a href="#B9-jcm-13-06143" class="html-bibr">9</a>,<a href="#B13-jcm-13-06143" class="html-bibr">13</a>,<a href="#B17-jcm-13-06143" class="html-bibr">17</a>,<a href="#B18-jcm-13-06143" class="html-bibr">18</a>,<a href="#B19-jcm-13-06143" class="html-bibr">19</a>,<a href="#B20-jcm-13-06143" class="html-bibr">20</a>,<a href="#B21-jcm-13-06143" class="html-bibr">21</a>,<a href="#B22-jcm-13-06143" class="html-bibr">22</a>,<a href="#B23-jcm-13-06143" class="html-bibr">23</a>,<a href="#B24-jcm-13-06143" class="html-bibr">24</a>,<a href="#B25-jcm-13-06143" class="html-bibr">25</a>,<a href="#B26-jcm-13-06143" class="html-bibr">26</a>,<a href="#B28-jcm-13-06143" class="html-bibr">28</a>,<a href="#B29-jcm-13-06143" class="html-bibr">29</a>,<a href="#B30-jcm-13-06143" class="html-bibr">30</a>,<a href="#B31-jcm-13-06143" class="html-bibr">31</a>] to the three subtypes of the modified Van Praagh classification [<a href="#B4-jcm-13-06143" class="html-bibr">4</a>]: type A1–2: TAC with confluent or near confluent pulmonary arteries (PA) (large aorta type); type A3: TAC with absence of one PA (large aorta type of one PA), the other PA supplied by patent arterial duct); type A4: TAC with interrupted aortic arch or coarctation (large PA type). A1–A4 refers to the original Van Praagh classification [<a href="#B2-jcm-13-06143" class="html-bibr">2</a>], CE = Collet and Edwards, types 1–3 [<a href="#B1-jcm-13-06143" class="html-bibr">1</a>]. * does not represent all cases, other subtypes were not specified.</p>
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<p><b>Comparison of overall survival of prenatally diagnosed TAC cases of the current study and reported case series:</b> In the current study, 64% of prenatally diagnosed cases resulted in live births, with an 86% intention-to-treat survival and 55% overall survival. The literature review shows 56% live births, 75% intention-to-treat survival, and 39% overall survival, indicating better survival rates in the current study.</p>
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31 pages, 7846 KiB  
Review
Perspectives in Aptasensor-Based Portable Detection for Biotoxins
by Congying Li, Ziyuan Zhu, Jiahong Yao, Zhe Chen and Yishun Huang
Molecules 2024, 29(20), 4891; https://doi.org/10.3390/molecules29204891 (registering DOI) - 15 Oct 2024
Viewed by 269
Abstract
Biotoxins are pervasive in food and the environment, posing significant risk to human health. The most effective strategy to mitigate the risk arising from biotoxin exposure is through their specific and sensitive detection. Aptasensors have emerged as pivotal tools, leveraging aptamers as biorecognition [...] Read more.
Biotoxins are pervasive in food and the environment, posing significant risk to human health. The most effective strategy to mitigate the risk arising from biotoxin exposure is through their specific and sensitive detection. Aptasensors have emerged as pivotal tools, leveraging aptamers as biorecognition elements to transduce the specificity of aptamer-target interactions into quantifiable signals for analytical applications, thereby facilitating the meticulous detection of biotoxins. When integrated with readily portable devices such as lateral flow assays (LFAs), personal glucose meters (PGMs), smartphones, and various meters measuring parameters like pH and pressure, aptasensors have significantly advanced the field of biotoxin monitoring. These commercially available devices enable precise, in situ, and real-time analysis, offering great potential for portable biotoxin detection in food and environmental matrices. This review highlights the recent progress in biotoxin monitoring using portable aptasensors, discussing both their potential applications and the challenges encountered. By addressing these impediments, we anticipate that a portable aptasensor-based detection system will open new avenues in biotoxin monitoring in the future. Full article
(This article belongs to the Special Issue Applied Analytical Chemistry: Second Edition)
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<p>(<b>a</b>) Fundamental assemblies required for the construction of LFA; (<b>b</b>) Schematic diagram illustrating aptamer-based LFA. Reprinted with permission from Ref. [<a href="#B63-molecules-29-04891" class="html-bibr">63</a>]. Copyright 2023, Elsevier.</p>
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<p>(<b>a</b>) Working principle of Cy5-labeled LFA aptasensor for detection of OTA. Reprinted with permission from Ref. [<a href="#B69-molecules-29-04891" class="html-bibr">69</a>]. Copyright 2018, MDPI. (<b>b</b>) Schematic representation of fluorescent LFA aptasensor based on QD for OTA analysis. Reprinted with permission from Ref. [<a href="#B73-molecules-29-04891" class="html-bibr">73</a>]. Copyright 2011, Royal Society of Chemistry. (<b>c</b>) Mechanism diagram of UCNP-labeled LFA aptasensor for OTA detection. Reprinted with permission from Ref. [<a href="#B78-molecules-29-04891" class="html-bibr">78</a>]. Copyright 2018, Springer Nature.</p>
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<p>(<b>a</b>) Schematic illustration of PGM-based aptasensor for detecting OTA via a structure-switching aptamer. Reprinted with permission from Ref. [<a href="#B82-molecules-29-04891" class="html-bibr">82</a>]. Copyright 2016, Royal Society of Chemistry. (<b>b</b>) Schematic representation of PGM-based aptasensor for AFB1 analysis by DNA walking machine. Reprinted with permission from Ref. [<a href="#B84-molecules-29-04891" class="html-bibr">84</a>]. Copyright 2018, American Chemical Society. (<b>c</b>) Mechanism diagram of PGM-based aptasensor for AFB1 detection using the “dual gates” locked nanodevice. Reprinted with permission from Ref. [<a href="#B86-molecules-29-04891" class="html-bibr">86</a>]. Copyright 2019, American Chemical Society. (<b>d</b>) Schematic diagram of aptasensor based on DMSNs-I nanoreactors with PGM as readout for detecting AFB1. Reprinted with permission from Ref. [<a href="#B87-molecules-29-04891" class="html-bibr">87</a>]. Copyright 2021, Elsevier.</p>
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<p>(<b>a</b>) Schematic diagram of the smartphone-based colorimetric aptasensor for AFB1 detection. Reprinted with permission from Ref. [<a href="#B98-molecules-29-04891" class="html-bibr">98</a>]. Copyright 2023, Elsevier. (<b>b</b>) Mechanism diagram of the smartphone-based fluorescent aptasensor for ZEN detection. Reprinted with permission from Ref. [<a href="#B102-molecules-29-04891" class="html-bibr">102</a>]. Copyright 2024, Elsevier. (<b>c</b>) Schematic representation of the amplified visual electrochemiluminescence detection of AFM1. Reprinted with permission from Ref. [<a href="#B103-molecules-29-04891" class="html-bibr">103</a>]. Copyright 2018, Elsevier. (<b>d</b>) Schematic diagram of portable electrochemical aptasensor for MC-LR detection. Reprinted with permission from Ref. [<a href="#B104-molecules-29-04891" class="html-bibr">104</a>]. Copyright 2022, Elsevier.</p>
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<p>(<b>a</b>) Schematic illustration of a pressure meter-based aptasensor applied to OTA. Reprinted with permission from Ref. [<a href="#B107-molecules-29-04891" class="html-bibr">107</a>]. Copyright 2017, American Chemical Society. (<b>b</b>) Schematic protocol for AFB1 monitoring based on aptamer identification and a thermometer readout. Reprinted with permission from Ref. [<a href="#B109-molecules-29-04891" class="html-bibr">109</a>]. Copyright 2019, American Chemical Society. (<b>c</b>) Principle explanation of pH meter-based portable analysis of AFB1 coupled with an aptamer-crosslinked hydrogel. Reprinted with permission from Ref. [<a href="#B110-molecules-29-04891" class="html-bibr">110</a>]. Copyright 2018, Elsevier. (<b>d</b>) Overview of combining a catalytic hairpin assembly with pregnancy test strip for highly accurate monitoring of AFB1, OTA and ZEN. Reprinted with permission from Ref. [<a href="#B111-molecules-29-04891" class="html-bibr">111</a>]. Copyright 2022, Elsevier. (<b>e</b>) Working principle of DNA hydrogels with aptamer cross-links combining microfluidic chips for monitoring OTA. Reprinted with permission from Ref. [<a href="#B112-molecules-29-04891" class="html-bibr">112</a>]. Copyright 2015, American Chemical Society.</p>
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18 pages, 4442 KiB  
Article
Integrating Learning-Driven Model Behavior and Data Representation for Enhanced Remaining Useful Life Prediction in Rotating Machinery
by Tarek Berghout, Eric Bechhoefer, Faycal Djeffal and Wei Hong Lim
Machines 2024, 12(10), 729; https://doi.org/10.3390/machines12100729 (registering DOI) - 15 Oct 2024
Viewed by 279
Abstract
The increasing complexity of modern mechanical systems, especially rotating machinery, demands effective condition monitoring techniques, particularly deep learning, to predict potential failures in a timely manner and enable preventative maintenance strategies. Health monitoring data analysis, a widely used approach, faces challenges due to [...] Read more.
The increasing complexity of modern mechanical systems, especially rotating machinery, demands effective condition monitoring techniques, particularly deep learning, to predict potential failures in a timely manner and enable preventative maintenance strategies. Health monitoring data analysis, a widely used approach, faces challenges due to data randomness and interpretation difficulties, highlighting the importance of robust data quality analysis for reliable monitoring. This paper presents a two-part approach to address these challenges. The first part focuses on comprehensive data preprocessing using only feature scaling and selection via random forest (RF) algorithm, streamlining the process by minimizing human intervention while managing data complexity. The second part introduces a Recurrent Expansion Network (RexNet) composed of multiple layers built on recursive expansion theories from multi-model deep learning. Unlike traditional Rex architectures, this unified framework allows fine tuning of RexNet hyperparameters, simplifying their application. By combining data quality analysis with RexNet, this methodology explores multi-model behaviors and deeper interactions between dependent (e.g., health and condition indicators) and independent variables (e.g., Remaining Useful Life (RUL)), offering richer insights than conventional methods. Both RF and RexNet undergo hyperparameter optimization using Bayesian methods under variability reduction (i.e., standard deviation) of residuals, allowing the algorithms to reach optimal solutions and enabling fair comparisons with state-of-the-art approaches. Applied to high-speed bearings using a large wind turbine dataset, this approach achieves a coefficient of determination of 0.9504, enhancing RUL prediction. This allows for more precise maintenance scheduling from imperfect predictions, reducing downtime and operational costs while improving system reliability under varying conditions. Full article
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<p>Visual summary of the methodological steps.</p>
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<p>High-speed shaft positioning in a 2 MW wind turbine and the cracked inner race of a high-speed bearing: (<b>a</b>) schematic representation of the wind turbine gearbox, illustrating the high-speed shaft’s location; (<b>b</b>) cracked inner race of a high-speed bearing. Both images (<b>a</b>,<b>b</b>) are adapted from [<a href="#B23-machines-12-00729" class="html-bibr">23</a>,<a href="#B25-machines-12-00729" class="html-bibr">25</a>], respectively, and are licensed under CC BY open access. The original images have been enhanced using content-aware techniques, denoising, and editing for improved clarity.</p>
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<p>Overview of raw data: (<b>a</b>) energy levels for cage, ball, inner race, and outer race; (<b>b</b>) shaft tick progression over time; (<b>c</b>) gearing load represented by RPM; (<b>d</b>) HI variation.</p>
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<p>Hyperparameters of the RF regressor.</p>
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<p>Feature importance results obtained by a Bayesian optimized RF regressor.</p>
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<p>Simplified flow diagram of the architecture of the proposed RexNet approach.</p>
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<p>Comparative analysis of the studied models’ training performance: (<b>a</b>) training loss over epochs for each model; (<b>b</b>) bar chart of the Area Under the Loss Curve (AULC), quantifying the overall loss behavior.</p>
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<p>RUL comparison and residual analysis: (<b>a</b>) training set, a comparison between actual (ideal) and predicted RUL for LSTM and RexNet models; (<b>b</b>) testing set, a comparison between actual (ideal) and predicted RUL for LSTM and RexNet models; (<b>c</b>) training set residuals, the difference between actual and predicted RUL; (<b>d</b>) testing set residuals, the difference between actual and predicted RUL.</p>
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<p>Residual normal distributions: (<b>a</b>) training set, a comparison of residual distributions for LSTM and RexNet models, highlighting the variability and error margins in each model’s predictions; (<b>b</b>) testing set, a comparison of residual distributions for LSTM and RexNet models, illustrating the accuracy and generalization of the models on unseen data.</p>
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24 pages, 6268 KiB  
Article
Development and Validation of a Portable EIT System for Real-Time Respiratory Monitoring
by Fabian Alvarado-Arriagada, Bruno Fernández-Arroyo, Samuel Rebolledo and Esteban J. Pino
Sensors 2024, 24(20), 6642; https://doi.org/10.3390/s24206642 (registering DOI) - 15 Oct 2024
Viewed by 301
Abstract
This work contributes to the improvement of novel medical technologies for the prevention and treatment of diseases. Electrical impedance tomography (EIT) has gained attention as a valuable tool for non-invasive monitoring providing real-time insights. The purpose of this work is to develop and [...] Read more.
This work contributes to the improvement of novel medical technologies for the prevention and treatment of diseases. Electrical impedance tomography (EIT) has gained attention as a valuable tool for non-invasive monitoring providing real-time insights. The purpose of this work is to develop and validate a novel portable EIT system with a small form factor for respiratory monitoring. The device uses a 16-electrode architecture with adjacent stimulation and measurement patterns, an integrated circuit current source and a single high-speed ADC operating with multiplexers to stimulate and measure across all electrodes. Tests were conducted on 25 healthy subjects who performed a pulmonary function test with a flowmeter while using the EIT device. The results showed a good performance of the device, which was able to recognize all respirations correctly, and from the EIT signals and images, correlations of 96.7% were obtained for instantaneous respiratory rate and 96.1% for tidal volume prediction. These results validate the preliminary technical feasibility of the EIT system and demonstrates its potential as a reliable tool for non-invasive respiratory assessment. The significance of this work lies in its potential to democratize advanced respiratory monitoring technologies, making them accessible to a wider population, including those in remote or underserved areas. Full article
(This article belongs to the Section Intelligent Sensors)
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<p>Block diagram of the EIT device.</p>
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<p>Differential circuit with Operational amplifier. DAC1 is channel 1 of the DAC, connected internally to CW generator, and DAC2 is channel 2 with a constant voltage value.</p>
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<p>Schematics of the current source. In (<b>a</b>) the OTA connection, and in (<b>b</b>) the amplifiers with both differential outputs.</p>
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<p>Multiplexer connection diagram. <span class="html-italic">A</span> and <span class="html-italic">B</span> are the stimulation current multiplexers with <math display="inline"><semantics> <mrow> <mi>i</mi> <mo>+</mo> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>i</mi> <mo>−</mo> </mrow> </semantics></math> as inputs coming from the current source. <span class="html-italic">C</span> and <span class="html-italic">D</span> are the voltage multiplexers with <math display="inline"><semantics> <mrow> <mi>v</mi> <mo>+</mo> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>v</mi> <mo>−</mo> </mrow> </semantics></math> as differential voltage outputs. The 12 <math display="inline"><semantics> <mrow> <mi>A</mi> <mi>B</mi> <mi>C</mi> </mrow> </semantics></math> selectors are connected to the microcontroller on independent digital outputs.</p>
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<p>Connection of the INA with the floating <math display="inline"><semantics> <msub> <mi>R</mi> <mi>G</mi> </msub> </semantics></math> pins, the <math display="inline"><semantics> <mrow> <mi>v</mi> <mo>−</mo> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>v</mi> <mo>+</mo> </mrow> </semantics></math> inputs on the high-pass filters and the reference voltage follower.</p>
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<p>Implemented DRL circuit, connected to the <math display="inline"><semantics> <msub> <mi>R</mi> <mi>G</mi> </msub> </semantics></math> pins of the INA. In this case, the gain resistor of <math display="inline"><semantics> <mrow> <mn>500</mn> <mspace width="4pt"/> <mi mathvariant="normal">Ω</mi> </mrow> </semantics></math> is divided into two resistors of <math display="inline"><semantics> <mrow> <mn>250</mn> <mspace width="4pt"/> <mi mathvariant="normal">Ω</mi> </mrow> </semantics></math> each.</p>
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<p>Connection between the ADC and the microcontroller.</p>
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<p>Circuit with positive and negative voltage regulators.</p>
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<p>Decoded raw voltage signal. Vertical lines separate the measurements, the first data are discarded.</p>
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<p>Raw and filtered differential voltage signal.</p>
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<p>Voltage profile of a frame. The vertical lines separate the stimulation current patterns.</p>
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<p>Voltage measurements for a subject with normal breathing and respiratory maneuvers at times 180 s and 250 s.</p>
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<p>Electrode placement for female subjects. From (<b>left</b>) to (<b>right</b>): right lateral view, posterior view, anterior view, left lateral view.</p>
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<p>Filtered volume signal. (<b>Top</b>): flow signal with integration range limits on the x-axis, (<b>middle</b>): the volume signal and the filter output, and (<b>below</b>): the frequency components of interest of the volume signal and the applied filter.</p>
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<p>Correlation between voltage signal and volume signal (Reference). The legend shows the Pearson correlation coefficient <span class="html-italic">r</span> for the original clipped signal and for the shifted signal.</p>
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<p>Current source signals. (<b>a</b>) Output of the ESP32 CW generator with amplitude 3.3 Vpp, and offset 1.65 V. (<b>b</b>) Output of the differential circuit with amplitude 72.8 mVp, and offset 0 V. Graphs produced by oscilloscope data. SNR: signal-to-noise ratio.</p>
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<p>EIT device photo showing: (<b>A</b>) microcontroller unit, (<b>B</b>) voltage-controlled current source, (<b>C</b>) multiplexers stage, (<b>D</b>) voltage amplification and filters, (<b>E</b>) power circuitry, and (<b>F</b>) electrode connectors.</p>
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<p>Voltages with highest correlation with volume for a subject. The volume signal is shown in black (right axis), while the voltage signals are shown in color (left axis). In the legend, the measurements are shown with their <span class="html-italic">r</span> coefficient.</p>
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<p>Measurements with the highest correlation per subject. On the x-axis are the 25 subjects, and each bar identifies the measurement with the highest correlation. The horizontal lines indicate mean and standard deviation.</p>
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<p>Peak detection for voltage and volume. On the left axis is the voltage signal with the highest correlation and on the right axis is the volume signal. The marks with ∇ correspond to peaks and with <math display="inline"><semantics> <mo>Δ</mo> </semantics></math> to valleys.</p>
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<p>Comparison of instantaneous respiratory rate between volume signal and voltage signal for the 25 subjects. (<b>a</b>) Plot of correlation between both variables with its equation, Pearson <span class="html-italic">r</span> and Spearman <math display="inline"><semantics> <mi>ρ</mi> </semantics></math> correlation coefficients, with their respective <span class="html-italic">p</span>-values. (<b>b</b>) Bland–Altman plot of mean between both variables vs. their difference, the median and the limits of conformity defined by the reproducibility coefficient (RPC) and interquartile range (IQR) with the formula <math display="inline"><semantics> <mrow> <mrow> <mi>R</mi> <mi>P</mi> <mi>C</mi> <mo>=</mo> <mn>1.45</mn> </mrow> <mo> </mo> <mrow> <mi>I</mi> <mi>Q</mi> <mi>R</mi> <mo>=</mo> <mn>1.45</mn> <mspace width="4pt"/> <mo>(</mo> <mn>0.0543</mn> <mo>)</mo> </mrow> </mrow> </semantics></math>.</p>
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<p>Image reconstruction. On the left the image shows a selected pixel at position (11, 25). On the right, the plot shows the variations of the selected pixel over time across all frames (<b>top</b>), along with the volume signal as a reference (<b>bottom</b>).</p>
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<p>Average correlation of pixels with volume for the 25 subjects.</p>
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<p>Breaths detected in the three minutes of recording with normal breathing for all subjects with volume annotations in blue, voltage signal in orange and pixel value in yellow.</p>
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<p>(<b>a</b>) Calculation of TV per breath for the volume signal and (<b>b</b>) amplitude corresponding to the same breath for the voltage signal.</p>
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<p>Comparison of TV between volume predictions from EIT voltage and volume signals from flowmeter for the 25 subjects. (<b>a</b>) Plot of correlation between both variables, Pearson <span class="html-italic">r</span> and Spearman <math display="inline"><semantics> <mi>ρ</mi> </semantics></math> correlation coefficients, with their respective <span class="html-italic">p</span>-values. (<b>b</b>) Bland–Altman plot with median and limits of conformity.</p>
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10 pages, 1724 KiB  
Article
Associations between Systemic and Dental Diseases in Elderly Korean Population
by Se Hoon Kahm and SungEun Yang
Medicina 2024, 60(10), 1693; https://doi.org/10.3390/medicina60101693 (registering DOI) - 15 Oct 2024
Viewed by 412
Abstract
Background and Objectives: Modernization and population aging have increased the prevalence of systemic diseases, such as diabetes and hypertension, which are often accompanied by various dental diseases. Our aim was to investigate associations between common dental conditions and major systemic diseases in an [...] Read more.
Background and Objectives: Modernization and population aging have increased the prevalence of systemic diseases, such as diabetes and hypertension, which are often accompanied by various dental diseases. Our aim was to investigate associations between common dental conditions and major systemic diseases in an elderly Korean population. Materials and Methods: Utilizing electronic medical record data from 43,525 elderly patients, we examined the prevalence of systemic diseases (diabetes, hypertension, rheumatoid arthritis, osteoporosis, dementia) and dental conditions (caries, periodontal disease, pulp necrosis, tooth loss). The analysis focused on the correlations between these diseases. Results: Significant associations were found between systemic diseases and an increased prevalence of dental conditions. Patients with systemic diseases, especially those with multiple conditions, had higher incidences of periodontal disease and tooth loss. The correlation was particularly strong in patients with diabetes and rheumatoid arthritis. Interestingly, temporomandibular joint disorder was less frequent in this cohort. Conclusions: The findings highlight the importance of integrated dental care in managing systemic diseases in elderly populations. Enhanced dental monitoring and proactive treatment are essential due to the strong association between systemic diseases and dental conditions. Collaboration between dental and medical professionals is crucial for comprehensive care that improves health outcomes and quality of life for elderly patients. Full article
(This article belongs to the Special Issue Boundaries between Oral and General Health)
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Figure 1

Figure 1
<p>Flow diagram for the determination of the study population for assessment.</p>
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<p>Distribution of included patients by sex and age.</p>
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<p>Odds ratios of single systemic diseases for dental disease. The red line represents Odds Ratio = 1.0. Values to the right indicate a higher observation of the dental diseases.</p>
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<p>Odds ratios of complex systemic diseases for dental disease. The red line represents Odds Ratio = 1.0. Values to the right indicate a higher observation of the dental diseases.</p>
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<p>Odds ratios of single and complex systemic diseases for dental diseases. The red line represents Odds Ratio = 1.0. Values to the right indicate a higher observation of the dental diseases.</p>
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