269 research outputs found

    Auditory Source Localization by Time Frequency Analysis and Classification of Electroencephalogram Signals

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    The temporal lobe or auditory cortex in the brain is involved in processing auditory stimuli. The auditory data processing capability in the brain changes as a person ages. In this paper, we use the hrtf method to produce sound in different directions as auditory stimulus. Experiments are conducted with auditory stimulation of human subjects. Electroencephalogram (EEG) recording from the subjects are made during the exposure to the sound. A set of time frequency analysis operators consisting of the cyclic short time Fourier transform and the continuous wavelet transform is applied to the pre-processed EEG signal and a classifier is trained with time-frequency power from training data. The support vector machine classifier is then used for source localization of the sound. The paper also presents results with respect to neuronal regions involved in processing multi source sound information

    Efficient enumeration of bosonic configurations with applications to the calculation of non-radiative rates

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    This work presents algorithms for the efficient enumeration of configuration spaces following Boltzmann-like statistics, with example applications to the calculation of non-radiative rates, and an open-source implementation. Configuration spaces are found in several areas of physics, particularly wherever there are energy levels that possess variable occupations. In bosonic systems, where there are no upper limits on the occupation of each level, enumeration of all possible configurations is an exceptionally hard problem. We look at the case where the levels need to be filled to satisfy an energy criterion, for example, a target excitation energy, which is a type of knapsack problem as found in combinatorics. We present analyses of the density of configuration spaces in arbitrary dimensions and how particular forms of kernel can be used to envelope the important regions. In this way, we arrive at three new algorithms for enumeration of such spaces that are several orders of magnitude more efficient than the naive brute force approach. Finally, we show how these can be applied to the particular case of internal conversion rates in a selection of molecules and discuss how a stochastic approach can, in principle, reduce the computational complexity to polynomial time

    Modeling radiative and non-radiative pathways at both the Franck–Condon and Herzberg–Teller approximation level

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    Here, we present a concise model that can predict the photoluminescent properties of a given compound from first principles, both within and beyond the Franck–Condon approximation. The formalism required to compute fluorescence, Internal Conversion (IC), and Inter-System Crossing (ISC) is discussed. The IC mechanism, in particular, is a difficult pathway to compute due to difficulties associated with the computation of required bosonic configurations and non-adiabatic coupling elements. Here, we offer a discussion and breakdown on how to model these pathways at the Density Functional Theory (DFT) level with respect to its computational implementation, strengths, and current limitations. The model is then used to compute the photoluminescent quantum yield (PLQY) of a number of small but important compounds: anthracene, tetracene, pentacene, diketo-pyrrolo-pyrrole (DPP), and Perylene Diimide (PDI) within a polarizable continuum model. Rate constants for fluorescence, IC, and ISC compare well for the most part with respect to experiment, despite triplet energies being overestimated to a degree. The resulting PLQYs are promising with respect to the level of theory being DFT. While we obtained a positive result for PDI within the Franck–Condon limit, the other systems require a second order correction. Recomputing quantum yields with Herzberg–Teller terms yields PLQYs of 0.19, 0.08, 0.04, 0.70, and 0.99 for anthracene, tetracene, pentacene, DPP, and PDI, respectively. Based on these results, we are confident that the presented methodology is sound with respect to the level of quantum chemistry and presents an important stepping stone in the search for a tool to predict the properties of larger coupled systems

    Expression of OX40 Gene and its Serum Levels in Neuromyelitis Optica Patients

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    Neuromyelitis optica (NMO), also known as Devic's disease, is an autoimmune disorder of the central nervous system (CNS) in which immune system cells and antibodies primarily attack the optic nerves and the spinal cord. OX40 (CD134) is a tumor necrosis factor (TNF)-receptor family member expressed primarily on activated CD4 + and CD8 + T-cells. In an autoimmune disease, OX40 is typically up-regulated at sites of inflammation, and increases in the number of peripheral CD4 + T-cells expressing OX40. OX40 and its ligand OX40L are key TNF members that augment T-cell expansion, cytokine production, and promote T-cell survival. The aim of this study was to evaluate and compare of OX40 gene expression and its serum levels in patients with NMO and healthy controls. Twenty sex-/age-matched healthy controls (HC) (median age = 32 years, 15 females/5 males) were engaged for the present study. Expression of OX40 at the transcript level and serum protein levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assays, respectively. The results indicated OX40 expression in patients was significantly lower than in healthy controls (p = 0.001). However, the serum level of OX40 was not significantly different between groups (p = 0.37). In addition, the results indicated that CD134 expression was not age-related (p = 0.041). Overall, this study suggests to us that OX40 levels are not a suitable marker for diagnosis or treatment of NMO. © 2019 Parya Alidadiani et al., published by De Gruyter

    OX40 gene and serum protein expression profiles in patients with Parkinson's disease

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    Objective: Inflammation of the immune system and the central nervous system has been known as an important predisposing factor for Parkinson's disease (PD). Increased expression of OX40 protein (CD134) is a known factor for increased inflammation and initiation of NF-kappa-B signaling pathway in different diseases. We aimed to investigate the expression of OX40 at the transcript and serum protein levels. Materials and Methods: Twenty individuals with PD and 20 healthy individuals, as controls, were enrolled in this casecontrol study. Expression of OX40 at the transcript level and serum protein levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assays respectively. Results: The mean expression level of OX40 was increased in patients but not at a significant level (P>0.05). Consistently, the mean serum concentration of OX40 showed a mild, but non-significant, increase in the patients (P>0.05). Conclusion: We conclude that OX40 expression at either the transcript or protein level has no diagnostic utility in asymptomatic PD. This shows the need for clinical, cellular and interventional research to detect new robust biomarkers. © 2018 Royan Institute (ACECR). All Rights Reserved

    OX40 gene and serum protein expression profiles in patients with Parkinson's disease

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    Objective: Inflammation of the immune system and the central nervous system has been known as an important predisposing factor for Parkinson's disease (PD). Increased expression of OX40 protein (CD134) is a known factor for increased inflammation and initiation of NF-kappa-B signaling pathway in different diseases. We aimed to investigate the expression of OX40 at the transcript and serum protein levels. Materials and Methods: Twenty individuals with PD and 20 healthy individuals, as controls, were enrolled in this casecontrol study. Expression of OX40 at the transcript level and serum protein levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assays respectively. Results: The mean expression level of OX40 was increased in patients but not at a significant level (P>0.05). Consistently, the mean serum concentration of OX40 showed a mild, but non-significant, increase in the patients (P>0.05). Conclusion: We conclude that OX40 expression at either the transcript or protein level has no diagnostic utility in asymptomatic PD. This shows the need for clinical, cellular and interventional research to detect new robust biomarkers. © 2018 Royan Institute (ACECR). All Rights Reserved

    Fluorescence characterization of clinically-important bacteria

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    Healthcare-associated infections (HCAI/HAI) represent a substantial threat to patient health during hospitalization and incur billions of dollars additional cost for subsequent treatment. One promising method for the detection of bacterial contamination in a clinical setting before an HAI outbreak occurs is to exploit native fluorescence of cellular molecules for a hand-held, rapid-sweep surveillance instrument. Previous studies have shown fluorescence-based detection to be sensitive and effective for food-borne and environmental microorganisms, and even to be able to distinguish between cell types, but this powerful technique has not yet been deployed on the macroscale for the primary surveillance of contamination in healthcare facilities to prevent HAI. Here we report experimental data for the specification and design of such a fluorescence-based detection instrument. We have characterized the complete fluorescence response of eleven clinically-relevant bacteria by generating excitation-emission matrices (EEMs) over broad wavelength ranges. Furthermore, a number of surfaces and items of equipment commonly present on a ward, and potentially responsible for pathogen transfer, have been analyzed for potential issues of background fluorescence masking the signal from contaminant bacteria. These include bedside handrails, nurse call button, blood pressure cuff and ward computer keyboard, as well as disinfectant cleaning products and microfiber cloth. All examined bacterial strains exhibited a distinctive double-peak fluorescence feature associated with tryptophan with no other cellular fluorophore detected. Thus, this fluorescence survey found that an emission peak of 340nm, from an excitation source at 280nm, was the cellular fluorescence signal to target for detection of bacterial contamination. The majority of materials analysed offer a spectral window through which bacterial contamination could indeed be detected. A few instances were found of potential problems of background fluorescence masking that of bacteria, but in the case of the microfiber cleaning cloth, imaging techniques could morphologically distinguish between stray strands and bacterial contamination
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