Search Results (1,410)

This article introduces the R package pspatreg, which is publicly available for download from the Comprehensive R Archive Network, for estimating semiparametric spatial econometric penalized spline (P-Spline) models. These models can incorporate a nonparametric spatiotemporal trend, a spatial lag of the dependent variable, independent variables, noise, and time-series autoregressive noise. The primary functions in this package cover the estimation of P-Spline spatial econometric models using either Restricted Maximum Likelihood (REML) or Maximum Likelihood (ML) methods, as well as the computation of marginal impacts for both parametric and nonparametric terms. Additionally, the package offers methods for the graphical display of estimated nonlinear functions and spatial or spatiotemporal trend maps. Applications to cross-sectional and panel spatial data are provided to illustrate the package’s functionality. Full article

The success of image segmentation is mainly dependent on the optimal choice of thresholds. Compared to bi-level thresholding, multi-level thresholding is a more time-consuming process, so this paper utilizes the gray wolf optimizer (GWO) algorithm to address this issue and enhance accuracy. To acquire the optimal thresholds at different levels, we modify the GWO (MGWO) in terms of leader selection, position update, and mutation. We also use the Otsu method and Kapur entropy as objective functions. The performance of MGWO is compared with other color image segmentation algorithms on ten images from the BSD500 dataset in terms of objective values, variance, signal-to-noise ratio (PSNR), structural similarity index measure (SSIM), and feature similarity index (FSIM). Experimental and non-parametric statistical analyses demonstrate that MGWO performs excellently in the multi-level thresholding segmentation of color images. Full article

Objectives: This study aimed to describe the clinical, optical coherence tomography (OCT) and OCT angiography (OCTA) findings and characteristics in patients with perifoveal exudative vascular anomalous complex (PEVAC) and compare the macular vascular density with the age-matched control group. Methods: We conducted a case–control study to compare demographic information, clinical observations, and OCT/OCTA findings in eyes with PEVAC (n = 5 eyes in 5 patients) and a control group of subjects matched for age (n = 9). The Advanced Retina Imaging (ARI) network algorithms were utilized to evaluate OCTA observations. Statistical analysis was performed by the nonparametric Mann–Whitney U test. Results: Patients with PEVAC had a mean (±SD) age at presentation of 70 ± 12.6 years, the mean follow-up period was 7.8 ± 5.2 months, and unilateral disease was observed. Four out of the five patients in our cohort had a history of systemically treated hypertension and dyslipidemia. Three eyes had lesions in the inner temporal retinal zone, while the remaining two eyes had lesions in the inner inferior or central zone. Retina slab analysis using OCTA showed no significant difference in vascular density parameters between the PEVAC and control groups. Conclusions: Although limited by a small sample size, our study suggests that macular vessel density shows no significant difference between PEVAC cases and control eyes. Full article

Land suitability analyses are crucial for identifying sustainable areas for agricultural crops and developing appropriate land use strategies. Thus, the present study aims to analyze the current and future land suitability for wheat (Triticum aestivum L.) cultivation in Ethiopia. Twelve variables including soil properties, climate variables, and topographic characteristics were used in the evaluation of land suitability. Statistical methods such as Rotated Empirical Orthogonal Functions (REOF), Coefficient of Variation (CV), correlation, and parametric and non-parametric trend analyses were used to analyze the spatiotemporal variability in current and future climate data and identified significant patterns of variability. For future projections of land suitability and climate, this study employed climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) framework, downscaled using regional climate model version 4.7 (RegCM4.7) under two different Shared Socioeconomic Pathway (SSP) climate scenarios: SSP1 (a lower emission scenario) and SSP5 (a higher emission scenario). Under the current condition, during March, April, and May (MAM), 53.4% of the country was suitable for wheat cultivation while 44.4% was not suitable. In 2050, non-suitable areas for wheat cultivation are expected to increase by 1% and 6.9% during MAM under SSP1 and SSP5 climate scenarios, respectively. Our findings highlight that areas currently suitable for wheat may face challenges in the future due to altered temperature and precipitation patterns, potentially leading to shifts in suitable areas or reduced productivity. This study also found that the suitability of land for wheat cultivation was determined by rainfall amount, temperature, soil type, soil pH, soil organic carbon content, soil nitrogen content, and elevation. This research underscores the critical importance of integrating spatiotemporal climate variability with future projections to comprehensively assess wheat suitability. By elucidating the implications of climate change on wheat cultivation, this study lays the groundwork for developing effective adaptation strategies and actionable recommendations to enhance management practices. The findings support the county’s commitment to refining agricultural land use strategies, increasing wheat production through suitability predictions, and advancing self-sufficiency in wheat production. Additionally, these insights can empower Ethiopia’s agricultural extension services to guide farmers in cultivating wheat in areas identified as highly and moderately suitable, thereby bolstering production in a changing climate. Full article

Background/Objectives: The integration of quality of life (QoL) assessments into dental health evaluations acknowledges the profound impact of oral health on overall well-being. This study aims to compare the impact of implant-supported complete dentures versus conventional complete dentures on oral health-related quality of life (OHRQoL) in elderly Romanian edentulous patients. Methods: This longitudinal study involved 93 initially recruited edentulous patients, with 52 completing the study over an 18-month period. Data collection utilized the OHIP-5 questionnaire, assessing the OHRQoL at baseline with conventional dentures and three months post-implant-supported denture placement. Ethical approval was secured from the Faculty of Medicine and Pharmacy University of Oradea, adhering to the Helsinki Declaration principles. A statistical analysis was conducted using SPSS version 25 and included non-parametric tests for score comparisons and Fisher’s exact test for categorical data. Results: The comparative analysis of the questionnaire responses revealed significant improvements in all five OHRQoL dimensions post-treatment with implant-supported dentures. For instance, the proportion of patients reporting “never” experiencing difficulty chewing any foods increased from 1.9% at baseline to 57.7% post-treatment. Similarly, those reporting “never” experiencing painful aching rose from 3.8% to 76.9%. There was also a notable reduction in discomfort regarding the appearance of mouth, dentures, or jaws from 3.8% reporting “never” at baseline to 75% post-treatment. The improvements in sense of taste and difficulty in performing usual activities saw comparable increases. Conclusions: The findings support the hypothesis that implant-supported complete dentures significantly enhance OHRQoL among elderly edentulous patients compared to conventional dentures, with improvements noted in mastication ability, pain reduction, aesthetics, taste perception, and activity performance. These results underscore the value of prosthetic interventions in dental care to substantially improve patients’ OHRQoL. Full article

Introduction: Metal ions, released from dental alloys due to corrosion, come in contact with the cells of the surrounding tissues and may spread throughout the body via the gastrointestinal system, thus inducing dose-dependent cytopathological effects. This study aimed to assess and compare the salivary cobalt and chromium concentrations in individuals aged 18–65 years with and without dental restorations containing metal alloys. Methods: Participants were divided into two main groups according to the existence of metal alloys in the oral cavity—18 patients had fixed prosthetic restorations made of metal alloys, and 17 patients had no metal objects in their oral cavity. Each main group was subdivided into two subgroups according to the type of saliva sample—with or without additional stimulation. Salivary cobalt and chromium concentrations were measured by inductively coupled plasma mass spectrometry. A non-parametric Mann–Whitney test and Spearman’s rank correlation coefficient were applied, and the level of significance was set to p < 0.05. Results: The results showed that the chromium level in non-stimulated saliva was higher in the group of patients with metal dental restorations. No statistical difference was found in cobalt levels. There was no statistical difference in Co or Cr concentrations in stimulated saliva between the studied groups. A positive correlation was found between Cr and Co concentrations in non-stimulated saliva and between cobalt concentrations in stimulated and non-stimulated saliva. Conclusions: Metal alloys in the oral cavity induced elevated chromium levels in non-stimulated saliva, and a correlation between chromium and cobalt ion concentration was found. A detailed examination of patients and their medical history prior to prosthetic treatment is advisable in order to avoid any undesired health effects. Full article

Generally, playing group management performance and financial management performance of sports clubs are assessed separately. We adopt a non-parametric methodology to assess overall performance, first conceptualising overall management as a production process comprising two serially linked subprocesses, namely, playing group management and financial management. Thereafter, we decompose overall performance to obtain estimates of performance at the subprocess level. Through this procedure, it is possible to determine whether a sports club’s on-field performance or off-field performance or both may contribute towards its inefficiency, if any, in overall management. Further, a model is developed to determine targets for inefficient clubs to become overall efficient. The method is applied to 18 clubs in the Australian rules football league. In the 2021 season, the results reveal that on-field performance, on average, is better than off-field performance, and variability in off-field performance is higher than that of on-field performance. The observed overall management inefficiency is mainly due to inefficiency in financial management. Results are robust to the weighting scheme adopted in the overall efficiency configuration. Full article

Hydrometeorological hazards are currently a cause for great concern worldwide. Droughts are among the most recurrent events, causing significant losses. This article presents a study on the duration of droughts in the southernmost state of Brazil, which has a large agricultural sector and experiences frequent drought events. The approach focuses on the economic recovery time of municipalities affected by the drought in 2020, 2022 and 2023, using the total value of invoices issued within each municipality between companies and from companies to consumers. The Kaplan–Meier estimator and Cox regression models are applied, incorporating covariates such as the size of the municipality, geographic location, and primary economic activity sector. The results show that the longest recovery period is concentrated in small cities, particularly in those where agriculture or livestock is the primary economic activity. The greatest resilience is observed in cities within the metropolitan region, where economic activity is more concentrated in services and industry and where populations are generally larger. The study identifies that after each drought event, at least 75% of municipalities achieve economic recovery within 3 months. These findings support better planning for both drought prevention and impact reduction and they are relevant for the development of economic and social policies. Full article

Aiming at the uncertainty of target motion and observation models in multi-maneuvering target tracking (MMTT), this study presents an innovative data-driven approach based on a Gaussian process (GP). Traditional multi-model (MM) methods rely on a predefined set of motion models to describe target maneuvering. However, these methods are limited by the finite number of available models, making them unsuitable for handling highly complex and dynamic real-world scenarios, which, in turn, restricts the adaptability and flexibility of the filter. In addition, traditional methods often assume that observation models follow ideal linear or simple nonlinear relationships. However, these assumptions may be biased in actual application and so lead to degradation in tracking performance. To overcome these limitations, this study presents a learning-based algorithm-leveraging GP. This non-parametric GP approach enables learning an unlimited range of target motion and observation models, effectively mitigating the problems of model overload and mismatch. This improves the algorithm’s adaptability in complex environments. When the motion and observation models of multiple targets are unknown, the learned models are incorporated into the cubature Kalman probability hypothesis density (PHD) filter to achieve an accurate MMTT estimate. Our simulation results show that the presented approach delivers high-precision tracking of complex multi-maneuvering target scenarios, validating its effectiveness in addressing model uncertainty. Full article

Exercise-Induced Pulmonary Hemorrhage (EIPH) is a common pulmonary disease among racehorses, diagnosed by the detection of blood in the trachea after strenuous exercise or the presence of hemosiderophages in the bronchoalveolar lavage fluid (BALF). Although the latter is considered the most sensitive method to diagnose EIPH, it is perceived as a less practical and more invasive procedure compared to tracheal wash (TW) collection among racehorse trainers. The present retrospective study aimed to verify the agreement between Tracheal wash and BALF cytology in assessing EIPH in racehorses. For this purpose, cytological data from 172 patients regarding hemosiderophage percentage, hemosiderin score, and percentage of recent, intermediate, and old EIPH were reviewed, and the simplified Total Hemosiderin Score (sTHS) was calculated. Non-parametric statistical tests were used to assess the difference and the correlation between TW and BALF. The two cytological methods strongly agreed in evaluating EIPH in racehorses for hemosiderophage percentage (ρ = 0.89, p < 0.001), hemosiderin score (k = 0.63, p < 0.001), sTHS (ρ = 0.87, p < 0.001), percentage of recent EIPH (ρ = 0.95, p < 0.001), intermediate EIPH (ρ = 0.92, p < 0.001), and old EIPH (ρ = 0.85, p < 0.001). In conclusion, TW showed to be a reliable method, which might substitute BALF in assessing EIPH in racehorses. Full article

In this paper, we focused on developing copula-based modeling procedures that effectively capture the dependence between response and explanatory variables. Building upon the work of Noh et al. (J. Am. Stat. Assoc. 2013, 108, 676–688) we extended copula-based regression to accommodate both continuous and discrete covariates. Specifically, we explored the construction of copulas to estimate the conditional mean of the response variable given the covariates, elucidating the relationship between copula structures and marginal distributions. We considered various estimation methods for copulas and distribution functions, presenting a diverse array of estimators for the conditional mean function. These estimators range from non-parametric to semi-parametric and fully parametric, offering flexibility in modeling regression relationships. An adapted algorithm is applied to construct copulas and simulations are carried out to replicate datasets, estimate prediction model parameters, and compare with the OLS method. The practicality and efficacy of our proposed methodologies, grounded in the principles of copula-based regression, are substantiated through methodical simulation studies. Full article

Analyzing the reliability of the aging class of life distribution provides important information about how long a product lasts and sustainability measures that are essential for determining the environmental impact and formulating resource-saving plans. The study emphasizes the goodness-of-fit technique of the nonparametric test for the NBRU_mgf class because age data are crucial for applications. Evaluations were conducted using the test’s asymptotic properties and Pitman efficiency methodology for some selected asymmetric probability models, and the outcomes were compared with those of alternative methods. We assessed the test’s power against widely used reliability distributions for some well-known alternative asymmetric distributions, including the Weibull, Gamma, and linear failure rate (LFR) distributions, and provided percentiles for both censored and uncensored data. This study shows the efficacy of the test in various sectors using real-world datasets and comprehensive tables of test statistics. Full article

Background/Objectives: The increasing rates of nurse turnover pose significant challenges to healthcare systems, negatively impacting patient outcomes and increasing operational costs. Despite the recognized importance of retaining nursing staff, factors contributing to turnover intentions, such as job dissatisfaction and burnout, remain inadequately addressed. Developing job crafting skills among nurses can be a proactive strategy to mitigate these issues, leading to a more engaged and committed workforce. The aim of this study was to analyze nurses’ job crafting and its relationship with the intention to stay at their working hospitals or to leave the nursing profession. Methods: A cross-sectional, correlational study was conducted with a sample of 284 registered nurses using a self-reported online questionnaire with the standardized Spanish version of the Job Crafting Scale. Mann–Whitney U and Kruskal–Wallis nonparametric tests were used to determine statistically significant differences between two or more different groups for the job crafting variable, respectively. The Spearman correlation coefficient was calculated to explore the relationships between variables. Results: Mean scores obtained for the Job Crafting Scale indicated that nurses in the study had a high level of job crafting. Nurses with lower scores for the ‘Decreasing hindering job demands’ subscale had a significantly lower intention to stay at their workplace. Greater ‘Decreasing hindering job demands’ scores were significantly associated with a lower intention to leave the nursing profession. Lower nurses’ intention to leave the nursing profession was significantly associated with a greater intention to stay at hospitals. Conclusions: Improving ‘Decreasing hindering job demands’ job crafting skills to “decrease hindering job demands” through workload management, time management training, supportive supervision, resource availability, autonomy encouragement, promotion of team collaboration, and mental health support. It could lead to greater retention of nurses in their workplaces and in the nursing profession. Nursing managers and leaders should consider improving the job crafting skill “Decrease Hindering Job Demands” among nurses as a potential strategy for effective retention of nurses to address the challenges of the global nursing shortage. Full article

This paper presents nonparametric predictive inference for discrete lifetime data. While lifetimes are mostly treated as continuous random variables in statistics, there are scenarios where time observations are recorded as discrete values, for example, in actuary, where lifetimes are often recorded as integers in years. The presented method provides lower and upper probabilities for a variety of events of interest involving discrete lifetimes, with examples provided for illustration. Furthermore, the discrete-time situation is considered for inference of the reliability of systems, with discrete-time data for components of different types and using the survival signature to combine inference on components’ reliability to quantify the overall system reliability. Full article

Strengthening primary healthcare (PHC) is vital for enhancing efficiency and improving access, clinical outcomes, and population well-being. The World Health Organization emphasizes the role of effective PHC in reducing healthcare costs and boosting productivity. With growing healthcare demands and limited resources, efficient management is critical. Background/Objectives: Building on this point, this study aimed to evaluate the efficiency of PHC units across Greece, focusing on Health Centers (HCs) and Local Health Units (ToMYs). The objective was to assess their efficiency levels and identify factors contributing to observed inefficiencies. This study explores a novel research area by being the first to assess the efficiency of restructured primary healthcare facilities in Greece, utilizing 2019 data—the first year operational data became available for the newly established ToMY facilities following recent healthcare reforms. Methods: We applied a comprehensive suite of non-parametric methods, including Data Envelopment Analysis (DEA) under variable, constant, increasing, and decreasing returns to scale (VRS, CRS, IRS/NDRS, DRS/NIRS) assumptions, along with the Free Disposal Hull (FDH) model, all oriented toward output maximization. Efficiency scores were refined using bootstrapping to calculate 95% confidence intervals, and efficient units were ranked via the super-efficiency model. Outliers were identified and removed through the data cloud algorithm. For the first time at this scale, the final sample included the vast majority of PHC facilities in Greece—234 Health Centers and 94 Local Health Units—with inputs categorized into three human resource types: medical, nursing/paramedical, and administrative/other staff. Outputs encompassed scheduled visits, emergency visits, and pharmaceutical prescription visits. This diverse and comprehensive application of DEA methods represents a novel approach to evaluating PHC efficiency in Greece, with potential relevance to broader healthcare contexts. Results: The analysis revealed significant inefficiencies and differences in technical efficiency between HCs and ToMYs. HCs could nearly double their outputs (VRS score: 1.92), while ToMYs could increase theirs by 58% (VRS score: 1.58). Scale efficiency scores were closer, with HCs slightly more aligned with their optimal scale (1.17 vs. 1.20 for ToMYs). Conclusions: There is significant potential to improve efficiency in PHC, with variations depending on unit characteristics and regional differences. This evaluation provides a foundation for policymakers to identify areas for improvement and enhance the overall performance of healthcare services in Greece. Full article