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    Johann Wanek

    The mummification of human tissue undergoes dramatic physicochemical changes as well as morphological alterations originated by decreasing of cell volume and spacing. The exposure to radiation of ancient remains undergoing computed... more
    The mummification of human tissue undergoes dramatic physicochemical changes as well as morphological alterations originated by decreasing of cell volume and spacing. The exposure to radiation of ancient remains undergoing computed tomography imaging is often accompanied by uncertainties regarding DNA damage. Consequently, anthropologists and forensic scientists are highly interested to know the probability of DNA destruction using X-ray imaging. Up to the present there have been no attempts to quantify the contribution of direct effects of sparsely ionizing radiation to desiccated cells embedded in different phantom tissue. The aim of our studies is to investigate the impact of geometry and molecular weight variations to radiation sensitivity of cells following mummification. A computed tomography model is presented for the irradiation of cell nuclei distributed by self-avoiding random walks in 3D (SAW). Results are calculated for nuclei embedded in a cylinder composed of normal ti...
    Previously we developed a low-cost, multi-configurable handheld response system, using a reflective-type intensity modulated fiber-optic sensor (FOS) [1] to accurately gather participants' behavioral responses during functional... more
    Previously we developed a low-cost, multi-configurable handheld response system, using a reflective-type intensity modulated fiber-optic sensor (FOS) [1] to accurately gather participants' behavioral responses during functional magnetic resonance imaging (fMRI). Inspired by the popularity and omnipresence of the fingertip-based touch sensing user interface devices, in this paper we present the design of a prototype fMRI-compatible optical touch stripe (OTS) as an alternative configuration. The prototype device takes advantage of a proven frustrated total internal reflection (FTIR) technique. By using a custom-built wedge-shaped optically transparent acrylic prism as an optical waveguide, and a plano-concave lens to provide the required light beam profile, the position of a fingertip touching the surface of the wedge prism can be determined from the deflected light beams that become trapped within the prism by total internal reflection. To achieve maximum sensitivity, the optical...
    Functional magnetic resonance imaging (fMRI) data should be interpreted in combination and in the context of relevant behavioral measurements. However, the strong magnetic environment of MRI scanner and the supine position of participants... more
    Functional magnetic resonance imaging (fMRI) data should be interpreted in combination and in the context of relevant behavioral measurements. However, the strong magnetic environment of MRI scanner and the supine position of participants in the scanner significantly limit how participants' behavioral responses are recorded. This paper presents the design of a low-cost handheld response system (HRS) with a multi-configurable optomechanical design that utilizes a reflective-type intensity modulated fiber-optic sensor (FOS) and a programmable visual interface to accurately gather participants' behavioral responses during an fMRI experiment. Considering the effects of an input unit design on the participants' performance efficiency across age groups and physical and neurological (dis)ability, the optomechanical system is designed to provide flexibility in the range of an input module with easy change-out feature. Specifically, the input unit can be configured as a binary module such as push buttons or as an analog input device including a scrolling wheel, and one-dimensional joystick (lever arm). To achieve MRI-compatibility, all parts of the unit that are used inside the scanner bore are built from nonferromagnetic and off-the-shelf plastic materials. The MRI compatibility was evaluated on a 3.0 Tesla MRI scanner running echo planar imaging (EPI) and the average time-variant signal-to-noise ratio (tSNR) loss is limited to 2%.
    Following hand function impairment caused by a neurological disorder, the functional level of the upper extremities has to be assessed in the clinical and rehabilitation settings. Current hand function evaluation tests are somewhat... more
    Following hand function impairment caused by a neurological disorder, the functional level of the upper extremities has to be assessed in the clinical and rehabilitation settings. Current hand function evaluation tests are somewhat imprecise. Instrumented gloves allow finger motion monitoring during the performance of skilled tasks, such as grasping objects. As a result, they provide an objective tool for evaluating slight changes in the fine motor skills of the hand. Numerous gloves are based on resistive bend sensors, given that this is an easy to handle, low-cost, and reliable sensing element. When bending is not applied homogeneously along such a sensor, as is the case with finger-joint bending, its output response varies with the sensor's longitudinal position. Our goal is to determine the optimal sensor position with respect to the finger-joint in order to enhance the resolution of the sensors embedded in a glove. The validity of the integrated sensors is evaluated and the accuracy values are given.
    Computed tomography represents the gold standard in forensic and palaeopathological diagnosis. However, the X-rays used may affect the DNA quality through fragmentation and loss of genetic information. Previous work showed that the... more
    Computed tomography represents the gold standard in forensic and palaeopathological diagnosis. However, the X-rays used may affect the DNA quality through fragmentation and loss of genetic information. Previous work showed that the effects of ionizing radiation on dry DNA are non-significant with P < 10(-8), which cannot be detected by means of polymerase chain reaction methods. In the present paper, complete analytical model that characterizes radiation effects on fragmented DNA in dry, wet, and frozen states is described. Simulation of radiation tracks in water phantom cells was performed using the Geant4-DNA toolkit. Cell hits by electrons with energies between 5 and 20 keV were simulated, and the formation of radiolytic products was assessed at a temperature of 298 K. The diffusion coefficient and the mean square displacement of reactive species were calculated by Stokes-Einstein-Smoluchowski relations at 273 K. Finally, DNA fragment damage was estimated using the density dis...
    Many studies have been concerned with the ancient Egyptian mummification method; nevertheless, little effort has been made to explore it experimentally. The goal of this study is to apply evidence-based diagnostic criteria and... more
    Many studies have been concerned with the ancient Egyptian mummification method; nevertheless, little effort has been made to explore it experimentally. The goal of this study is to apply evidence-based diagnostic criteria and state-of-the art methodology in order to improve knowledge on soft tissues preservation and postmortem alterations. Two human lower limbs (LL) from a female donor were (1) “naturally” mummified by dry heat and (2) artificially in natron. At specific time intervals a macroscopic and radiological examination of the LL was performed and skin and muscle samples were taken for histological and biomolecular analysis. Temperature, humidity, pH, and weight of the LL were systematically measured. The mummification by dry heat was stopped after 7 days due
    to unexpected lack of mummification progress. The mummification in natron was completed successfully after 208 days. The humidity, the external temperature, and the pH were proven with Pearson correlation and principal component analysis as important factors for the mummification process. The steady removal of water from the tissues through the
    natron has prevented the putrefaction. This is also evident in the absence of bacteria or fungi through the microbiological analysis. The histological analysis revealed very good preservation of the skin and the muscle tissues. In the muscular sample certain degree of structural disintegration can be seen, particularly affecting the epimysium whilst in the skin sam-
    ples the epidermis, especially the stratum corneum, is mostly affected. The samples show better preservation compared with ancient Egyptian sections and other mummified tissues from historic or forensic context.
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