996 results on '"Roy, P. C."'
Search Results
2. TiO2 multi-leg nanotubes for Surface-enhanced Raman scattering
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S, Harini, Gupta, Garima, Roy, Somnath C., and Yalavarthi, Rambabu
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Physics - Chemical Physics - Abstract
In the recent past, significant research efforts have been put forth to fabricate low-cost noble metal-free substrates for surface-enhanced Raman spectroscopy (SERS) applications. Here we propose semiconducting TiO2 multi-leg nanotubes (TiO2 MLNTs, with and without the gold nanoparticle coating) as SERS substrates. TiO2 MLNTs show unique multi-leg morphology compared to the conventional non-multi-leg tubes and possess better light-harvesting properties. TiO2 MLNTs are fabricated with a simple and versatile single-step electrochemical anodization method. Remarkable high SERS sensitivity is observed towards the detection of Methylene blue (MB), up to nM concentration (E.F. ~104). The same is attributed to the resonantly matched photonic absorption edge of TiO2 MLNTs with the wavelength of incident laser probe light. On the other hand, gold nanoparticle-coated TiO2 MLNTs demonstrated further enhancement in SERS sensitivity (E.F. ~105, for nM of MB) facilitated by the synergy that exists between the plasmonic modes (LSPRs) of Au and the photonic absorption mode of TiO2 MLNTs.
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- 2023
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3. An RC Analog of a Double Tuned Circuit
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Dutta Roy, S. C., Joshi, Y. V., and Nelatury, Sudarshan R.
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- 2024
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4. Simulated non-thermal emission from SNR G1.9+0.3
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Villagran, Marco A., Gómez, D. O., Velázquez, P. F., Meyer, D. M. -A., Chiotellis, A., Raga, A. C., Esquivel, A., Toledo-Roy, J. C., Vargas-Rojas, K. M., and Schneiter, E. M.
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Astrophysics - Astrophysics of Galaxies - Abstract
Supernova remnants are the nebular leftover of defunct stellar environments, resulting from the interaction between a supernova blastwave and the circumstellar medium shaped by the progenitor throughout its life. They display a large variety of non-spherical morphologies such as ears that shine non-thermally. % We have modelled the structure and the non-thermal emission of the supernova remnant G1.9+0.3 through 3D magnetohydrodynamic numerical simulations. We propose that the peculiar ear-shaped morphology of this supernova remnant results from the interaction of the its blast wave with a magnetized circumstellar medium, which was previously asymmetrically shaped by the past stellar wind emanating from the progenitor star or its stellar companion. We created synthetic non-thermal radio and x-ray maps from our simulated remnant structure, which are in qualitative agreement with observations, forming ears on the polar directions. Our synthetic map study explains the discrepancies between the measured non-thermal radio and X-ray surface brightness distributions assuming that the Inverse Compton process produces the observed X-ray emission., Comment: Accepted for publication in MNRAS
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- 2023
5. Glucose transporter-2 regulation of VMN GABA neuron metabolic sensor and transmitter gene expression
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Roy, Sagor C., Sapkota, Subash, Pasula, Madhu Babu, Katakam, Sushma, Shrestha, Rami, and Briski, Karen P.
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- 2024
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6. The relation of a cerebrospinal fluid profile associated with Alzheimer’s disease with cognitive function and neuropsychiatric symptoms in sporadic cerebral amyloid angiopathy
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De Kort, Anna M., Kaushik, Kanishk, Kuiperij, H. Bea, Jäkel, Lieke, Li, Hao, Tuladhar, Anil M., Terwindt, Gisela M., Wermer, Marieke J. H., Claassen, Jurgen A. H. R., Klijn, Catharina J. M., Verbeek, Marcel M., Kessels, Roy P. C., and Schreuder, Floris H. B. M.
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- 2024
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7. Splice modulators target PMS1 to reduce somatic expansion of the Huntington’s disease-associated CAG repeat
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McLean, Zachariah L., Gao, Dadi, Correia, Kevin, Roy, Jennie C. L., Shibata, Shota, Farnum, Iris N., Valdepenas-Mellor, Zoe, Kovalenko, Marina, Rapuru, Manasa, Morini, Elisabetta, Ruliera, Jayla, Gillis, Tammy, Lucente, Diane, Kleinstiver, Benjamin P., Lee, Jong-Min, MacDonald, Marcy E., Wheeler, Vanessa C., Mouro Pinto, Ricardo, and Gusella, James F.
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- 2024
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8. A Passive RC Circuit for Wideband Filtering
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Roy, S. C. Dutta and Joshi, Y. V.
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- 2024
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9. The relation of a cerebrospinal fluid profile associated with Alzheimer’s disease with cognitive function and neuropsychiatric symptoms in sporadic cerebral amyloid angiopathy
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Anna M. De Kort, Kanishk Kaushik, H. Bea Kuiperij, Lieke Jäkel, Hao Li, Anil M. Tuladhar, Gisela M. Terwindt, Marieke J. H. Wermer, Jurgen A. H. R. Claassen, Catharina J. M. Klijn, Marcel M. Verbeek, Roy P. C. Kessels, and Floris H. B. M. Schreuder
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Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Patients with sporadic cerebral amyloid angiopathy (sCAA) frequently report cognitive or neuropsychiatric symptoms. The aim of this study is to investigate whether in patients with sCAA, cognitive impairment and neuropsychiatric symptoms are associated with a cerebrospinal fluid (CSF) biomarker profile associated with Alzheimer’s disease (AD). Methods In this cross-sectional study, we included participants with sCAA and dementia- and stroke-free, age- and sex-matched controls, who underwent a lumbar puncture, brain MRI, cognitive assessments, and self-administered and informant-based-questionnaires on neuropsychiatric symptoms. CSF phosphorylated tau, total tau and Aβ42 levels were used to divide sCAA patients in two groups: CAA with (CAA-AD+) or without a CSF biomarker profile associated with AD (CAA-AD-). Performance on global cognition, specific cognitive domains (episodic memory, working memory, processing speed, verbal fluency, visuoconstruction, and executive functioning), presence and severity of neuropsychiatric symptoms, were compared between groups. Results sCAA-AD+ (n=31; mean age: 72 ± 6; 42%, 61% female) and sCAA-AD- (n=23; 70 ± 5; 42% female) participants did not differ with respect to global cognition or type of affected cognitive domain(s). The number or severity of neuropsychiatric symptoms also did not differ between sCAA-AD+ and sCAA-AD- participants. These results did not change after exclusion of patients without prior ICH. Conclusions In participants with sCAA, a CSF biomarker profile associated with AD does not impact global cognition or specific cognitive domains, or the presence of neuropsychiatric symptoms.
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- 2024
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10. On compensating the source resistance of the familiar Wien bridge networks
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Roy, S C Dutta
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- 2024
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11. The sculpting of rectangular and jet-like morphologies in supernova remnants by anisotropic equatorially-confined progenitor stellar winds
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Velazquez, P. F., Meyer, D. M. -A., Chiotellis, A., Cruz-Alvarez, A. E., Schneiter, E. M., Toledo-Roy, J. C., Reynoso, E. M., and Esquivel, A.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies - Abstract
Thermonuclear and core-collapse supernova remnants (SNRs) are the nebular leftovers of defunct stars. Their morphology and emission properties provide insights into the evolutionary history of the progenitor star. But while some SNRs are spherical, as expected from a point-like explosion expanding into a roughly uniform medium, many others exhibit complex non-spherical morphologies which are often not easily explained. In this work, we use three-dimensional magnetohydrodynamic simulations to show that rectangular and jet-like morphologies can be explained by supernovae (SNe), either type Ia or type II, expanding within anisotropic, bipolar stellar wind bubbles driven by the progenitor star. The stellar wind has an anisotropic density distribution, which channels the SN ejecta differently depending on the anisotropy characteristics. We compute synthetic thermal (X-ray) and non-thermal (synchrotron) emission maps from our numerical simulations to compare with observations. We find rectangular morphologies are generated when the stellar wind has a high mass loss rate and forms a dense, narrow disk at the equatorial region. Instead, a jet-like or ear-like morphology is obtained when the stellar wind develops a wide, dense disk. Stellar winds with low mass-loss rates do not strongly influence the SNR morphology. Finally, our synthetic synchrotron and X-ray maps for the high mass-loss rate case qualitatively agree with the observations of the SNRs G332.5-5.6 and G290.1-0.8., Comment: Accepted to MNRAS
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- 2023
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12. Rectangular core-collapse supernova remnants: application to Puppis A
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Meyer, D. M. -A., Velazquez, P. F., Petruk, O., Chiotellis, A., Pohl, M., Camps-Farina, F., Petrov, M., Reynoso, E. M., Toledo-Roy, J. C., Schneiter, E. M., Castellanos-Ramirez, A., and Esquivel, A.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Core-collapse supernova remnants are the gaseous nebulae of galactic interstellar media (ISM) formed after the explosive death of massive stars. Their morphology and emission properties depend both on the surrounding circumstellar structure shaped by the stellar wind-ISM interaction of the progenitor star and on the local conditions of the ambient medium. In the warm phase of the Galactic plane (n = 1/cm3, T = 8000 K), an organised magnetic field of strength 7 microG has profound consequences on the morphology of the wind bubble of massive stars at rest. In this paper we show through 2.5D magneto-hydrodynamical simulations, in the context of a Wolf-Rayet-evolving 35 Mo star, that it affects the development of its supernova remnant. When the supernova remnant reaches its middle age (15 to 20 kyr), it adopts a tubular shape that results from the interaction between the isotropic supernova ejecta and the anisotropic, magnetised, shocked stellar progenitor bubble into which the supernova blast wave expands. Our calculations for non-thermal emission, i.e. radio synchrotron and inverse Compton radiation, reveal that such supernova remnants can, due to projection effects, appear as rectangular objects in certain cases. This mechanism for shaping a supernova remnant is similar to the bipolar and elliptical planetary nebula production by wind-wind interaction in the low-mass regime of stellar evolution. If such a rectangular core-collapse supernova remnant is created, the progenitor star must not have been a runaway star. We propose that such a mechanism is at work in the shaping of the asymmetric core-collapse supernova remnant Puppis A., Comment: Accepted at MNRAS
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- 2022
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13. Two-year clinical progression in focal and diffuse subtypes of Parkinson’s disease
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Johansson, Martin E., van Lier, Nina M., Kessels, Roy P. C., Bloem, Bastiaan R., and Helmich, Rick C.
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- 2023
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14. Modulating arousal to overcome gait impairments in Parkinson’s disease: how the noradrenergic system may act as a double-edged sword
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Tosserams, Anouk, Bloem, Bastiaan R., Ehgoetz Martens, Kaylena A., Helmich, Rick C., Kessels, Roy P. C., Shine, James M., Taylor, Natasha L., Wainstein, Gabriel, Lewis, Simon J. G., and Nonnekes, Jorik
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- 2023
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15. Immune regulation and blood–brain barrier permeability in cerebral small vessel disease: study protocol of the INflammation and Small Vessel Disease (INSVD) study – a multicentre prospective cohort study
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Roy P C Kessels, Audrey Low, Hugh Markus, Anil Tuladhar, Frank‐Erik de Leeuw, Robin G Morris, Ziad Mallat, Niels P Riksen, Daniel J Tozer, Sanne van Winden, Lupei Cai, Marnix C Maas, Meritxell Nus, Anja van der Kolk, and Rowan Wolters
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Medicine - Abstract
Introduction The INflammation and Small Vessel Disease (INSVD) study aims to investigate whether peripheral inflammation, immune (dys)regulation and blood–brain barrier (BBB) permeability relate to disease progression in cerebral small vessel disease (SVD). This research aims to pinpoint specific components of the immune response in SVD relating to disease progression. This could identify biomarkers of SVD progression, as well as potential therapeutic targets to inform the development and repurposing of drugs to reduce or prevent SVD, cognitive decline and vascular dementia.Methods and analysis INSVD is a prospective observational multicentre cohort study in individuals with symptomatic SVD. This longitudinal study combines comprehensive immunophenotyping of the peripheral blood immune compartment with advanced neuroimaging markers of SVD and BBB permeability. The main SVD marker of interest is white matter microstructure as determined by diffusion tensor imaging, a valuable marker of disease progression owing to its sensitivity to early alterations to white matter integrity. The research is being conducted in two sites—in the UK (Cambridge) and the Netherlands (Nijmegen)—with each site recruiting 100 participants (total n=200). Participants undergo clinical and cognitive assessments, blood draws, and brain MRI at baseline and 2-year follow-up.Ethics and dissemination This study received ethical approval from the local ethics boards (UK: East of England—Cambridge Central Research Ethics Committee (REC) ref: 22/EE/00141, Integrated Research Application System (IRAS) ID: 312 747. Netherlands: Medical Research Ethics Committee (MREC) Oost-Nederland, ref: 2022-13623, NL-number: NL80258.091.22). Written informed consent was obtained from all subjects before the study. Any participant-derived benefits resulting from this research, such as new insights into disease mechanisms or possible novel therapies, will be disseminated to study participants, patient groups and members of the public.Trial registration number NCT05746221.
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- 2024
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16. Stanene: State of the Art and Future Prospects
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Rani, Sanju, Suganthi, K., and Roy, Somnath C.
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- 2023
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17. Comparative Study of Morphological Variation in Bi-functional ZnCo2O4 Nanostructures for Supercapacitor and OER Applications
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Gupta, Garima, Kumar, U. Naveen, Khatun, Nasima, Thomas, Tiju, and Roy, Somnath C.
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- 2023
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18. Shunted Bandpass RC Ladder Networks with over Unity Gain
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Roy, S. C. Dutta and Joshi, Y. V.
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- 2023
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19. Ab initio study of the density dependence of the Gr\'{u}neisen parameter at pressures up to 360 GPa
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Roy, Umesh C. and Sarkar, Subir K.
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Condensed Matter - Materials Science ,Physics - Computational Physics - Abstract
Ab initio calculations based on the Density Functional Theory are used to show that the Debye frequency is a linear function of density to a high accuracy for several elemental solids at pressures (at least) up to 360 GPa. This implies that the ratio of density over the (Debye-frequency-based) vibrational Gr\"{u}neisen parameter is a linear function of density in this region. Numerical data from first principles calculations for several systems at temperatures up to 2000K suggest that this is also true for the thermal Gr\"{u}neisen parameter in the same range of pressure. Our analytical form of the vibrational Gr\"{u}neisen parameter is applied to an implementation of the Lindemann's melting criterion to obtain a simple extrapolation formula for the melting temperatures of materials at higher densities. This prediction is tested against available experimental and numerical data for several elemental solids.
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- 2021
20. The Development of a Performance Validity Test (PVT) for Indonesia
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Widhi Adhiatma, Marc P. H. Hendriks, Magdalena S. Halim, and Roy P. C. Kessels
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performance validity test (pvt) ,malingering ,underperformance ,suboptimal effort ,neuropsychology ,Psychology ,BF1-990 - Abstract
Neuropsychological tests are proliferating in Indonesia. So far, unfortunately, it is not accompanied by the development of a performance validity test (PVT). According to international neuropsychological standards, using PVTs is essential to determine the validity of the neuropsychological test results. To date, there is no single standardized PVT available in Indonesia. In this article, we describe (1) the concept of performance validity testing, (2) the detection strategy, and (3) the procedure of PVT. Furthermore, several factors which affect PVT failure and its implication on the interpretation of a neuropsychological assessment are discussed. Considering the importance of PVTs incorporation and that it has become a standard by some neuropsychological associations, it is crucial to develop PVTs in Indonesia. Finally, the utilization of PVT should be performed cautiously, as many factors might influence the PVT result.
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- 2023
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21. Electronic Structure of Graphene/TiO$_2$ Interface: Design and Functional Perspectives
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Mishra, Shashi B., Roy, Somnath C., and Nanda, B. R. K.
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We propose the design of low strained and energetically favourable mono and bilayer graphene overlayer on anatase TiO$_2$ (001) surface and examined the electronic structure of the interface with the aid of first principle calculations. In the absence of hybridization between surface TiO$_2$ and graphene states, dipolar fluctuations govern the minor charge transfer across the interface. As a result, both the substrate and the overlayer retain their pristine electronic structure. The interface with the monolayer graphene retains its gapless linear band dispersion irrespective of the induced epitaxial strain. The potential gradient opens up a few meV bandgap in the case of Bernal stacking and strengthens the interpenetration of the Dirac cones in the case of hexagonal stacking of the bilayer graphene. The difference between the macroscopic average potential of the TiO$_2$ and graphene layer(s) in the heterostructure lies in the range 3 to 3.13 eV, which is very close to the TiO$_2$ bandgap ($\sim$ 3.2 eV). Therefore, the proposed heterostructure will exhibit enhanced photo-induced charge transfer and the graphene component will serve as a visible light sensitizer., Comment: 31 pages, 14 figures
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- 2020
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22. Birch's law at elevated temperatures
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Roy, Umesh C. and Sarkar, Subir K.
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Condensed Matter - Materials Science ,Physics - Geophysics - Abstract
Birch's law in high pressure physics postulates a linear relationship between elastic wave speed and density and one of its most well known applications is in investigations into the composition of the inner core of the Earth using the Preliminary Reference Earth Model as the primary source of constraints. However, it has never been subjected to high precision tests even at moderately elevated temperatures. Here we carry out such a test by making use of the Density Functional Theory of electronic structure calculation and the Density Functional Perturbation Theory of calculating the phonon dispersion relation. We show that a recently proposed modification to the Birch's law is consistently satisfied more accurately than its original version. This modified version states that it is the product of elastic wave speed and one-third power of density that should be a linear function of density. We have studied the cases of platinum, palladium, molybdenum and rhodium with cubic unit cell and iron with hexagonal-close-packed unit cell with temperatures up to 1500K and pressures up to about 360 GPa. We also examine the genericity of the validity of a recently proposed extension of the Birch's law according to which elastic wave speed is a linear function of temperature at a given density. Within the error bars of our calculation, we find that this is consistent with our data for the four cubic materials at temperatures up to 3300 K., Comment: 35 pages, 20 figures
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- 2020
23. Some interesting properties of the first Hall network
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Roy, S C Dutta and Nelatury, Sudarshan Rao
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- 2023
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24. Modulating arousal to overcome gait impairments in Parkinson’s disease: how the noradrenergic system may act as a double-edged sword
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Anouk Tosserams, Bastiaan R. Bloem, Kaylena A. Ehgoetz Martens, Rick C. Helmich, Roy P. C. Kessels, James M. Shine, Natasha L. Taylor, Gabriel Wainstein, Simon J. G. Lewis, and Jorik Nonnekes
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Arousal ,Gait ,Parkinson’s disease ,Freezing of gait ,Locus coeruleus ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract In stressful or anxiety-provoking situations, most people with Parkinson’s disease (PD) experience a general worsening of motor symptoms, including their gait impairments. However, a proportion of patients actually report benefits from experiencing—or even purposely inducing—stressful or high-arousal situations. Using data from a large-scale international survey study among 4324 people with PD and gait impairments within the online Fox Insight (USA) and ParkinsonNEXT (NL) cohorts, we demonstrate that individuals with PD deploy an array of mental state alteration strategies to cope with their gait impairment. Crucially, these strategies differ along an axis of arousal—some act to heighten, whereas others diminish, overall sympathetic tone. Together, our observations suggest that arousal may act as a double-edged sword for gait control in PD. We propose a theoretical, neurobiological framework to explain why heightened arousal can have detrimental effects on the occurrence and severity of gait impairments in some individuals, while alleviating them in others. Specifically, we postulate that this seemingly contradictory phenomenon is explained by the inherent features of the ascending arousal system: namely, that arousal is related to task performance by an inverted u-shaped curve (the so-called Yerkes and Dodson relationship). We propose that the noradrenergic locus coeruleus plays an important role in modulating PD symptom severity and expression, by regulating arousal and by mediating network-level functional integration across the brain. The ability of the locus coeruleus to facilitate dynamic ‘cross-talk’ between distinct, otherwise largely segregated brain regions may facilitate the necessary cerebral compensation for gait impairments in PD. In the presence of suboptimal arousal, compensatory networks may be too segregated to allow for adequate compensation. Conversely, with supraoptimal arousal, increased cross-talk between competing inputs of these complementary networks may emerge and become dysfunctional. Because the locus coeruleus degenerates with disease progression, finetuning of this delicate balance becomes increasingly difficult, heightening the need for mental strategies to self-modulate arousal and facilitate shifting from a sub- or supraoptimal state of arousal to improve gait performance. Recognition of this underlying mechanism emphasises the importance of PD-specific rehabilitation strategies to alleviate gait disability.
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- 2023
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25. Two-year clinical progression in focal and diffuse subtypes of Parkinson’s disease
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Martin E. Johansson, Nina M. van Lier, Roy P. C. Kessels, Bastiaan R. Bloem, and Rick C. Helmich
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Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Heterogeneity in Parkinson’s disease (PD) presents a barrier to understanding disease mechanisms and developing new treatments. This challenge may be partially overcome by stratifying patients into clinically meaningful subtypes. A recent subtyping scheme classifies de novo PD patients into three subtypes: mild-motor predominant, intermediate, or diffuse-malignant, based on motor impairment, cognitive function, rapid eye movement sleep behavior disorder (RBD) symptoms, and autonomic symptoms. We aimed to validate this approach in a large longitudinal cohort of early-to-moderate PD (n = 499) by assessing the influence of subtyping on clinical characteristics at baseline and on two-year progression. Compared to mild-motor predominant patients (42%), diffuse-malignant patients (12%) showed involvement of more clinical domains, more diffuse hypokinetic-rigid motor symptoms (decreased lateralization and hand/foot focality), and faster two-year progression. These findings extend the classification of diffuse-malignant and mild-motor predominant subtypes to early-to-moderate PD and suggest that different pathophysiological mechanisms (focal versus diffuse cerebral propagation) may underlie distinct subtype classifications.
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- 2023
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26. Game-supported cognitive strategy training for slowed information processing speed after acquired brain injury: study protocol for a randomised controlled trial
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Roy P C Kessels, Amy C Abelmann, Inti A Brazil, Luciano Fasotti, and Dirk Bertens
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Medicine - Abstract
Introduction Many individuals with acquired brain injury tend to experience problems with slowed information processing speed (IPS). A potentially beneficial and cost-effective supplement for cognitive rehabilitation of impaired IPS may be the implementation of serious gaming that focuses on compensatory learning as part of cognitive training. However, most digital platforms used during cognitive rehabilitation focus on restoring cognitive function and evidence for skill transfer from digital practice to everyday life is lacking. This study aims to investigate the efficacy of a game-supported cognitive strategy training. The training combines a well-validated time pressure management cognitive strategy training, targeting slowed IPS, with a novel game and a mobile application. The game-supported training focuses on the generalisation of strategy-use to untrained tasks in everyday life.Methods and analysis The study is designed as a randomised controlled trial in which the experimental group (Karman Line — Tempo module: an 8-week game-supported cognitive strategy training) will be compared with an active control group (CogniPlus training: an 8-week computerised cognitive function training). Data from 60 individuals with acquired brain injury (30 per group, ages between 16 and 75) will be collected at baseline (T0), post-treatment (T1) and at 3-month follow-up (T2). The primary outcome measure is an objective assessment of compensatory strategy use in an untrained experimental task. The secondary outcome is the attainment of trained and untrained treatment goals assessed by goal attainment scaling. Pre-training and post-training data will be analysed using a 2×2 repeated measure analysis of variance.Ethics and dissemination This study has been approved by the medical review ethics committee CMO Region Arnhem and Nijmegen (NL74818.091.20) and is registered in the Netherlands Trial Register. Research findings will be published in peer-reviewed journals and presented at conferences.Trial registration number NL9437; The Netherlands Trial Register.
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- 2023
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27. Quantum Mechanical Process of Carbonate Complex Formation and Large Scale Anisotropy in the Adsorption Energy of CO$_2$ on Anatase TiO$_2$ (001) Surface
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Mishra, Shashi B., Choudhary, Aditya, Roy, Somnath C., and Nanda, B. R. K.
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Condensed Matter - Materials Science - Abstract
Adsorption of CO$_2$ on a semiconductor surface is a prerequisite for its photocatalytic reduction. Owing to superior photocorrosion resistance, nontoxicity and suitable band edge positions, TiO$_2$ is considered to be the most efficient photocatalyst for facilitating redox reactions. However, due to the absence of adequate understanding of the mechanism of adsorption, the CO$_2$ conversion efficiency on TiO$_2$ surfaces has not been maximized. While anatase TiO$_2$ (101) is the most stable facet, the (001) surface is more reactive and it has been experimentally shown that the stability can be reversed and a larger percentage (up to ~ 89%) of the (001) facet can be synthesized in the presence fluorine ions. Therefore, through density functional calculations we have investigated the CO$_2$ adsorption on TiO$_2$ (001) surface. We have developed a three-state quantum-mechanical model that explains the mechanism of chemisorption, leading to the formation of a tridentate carbonate complex. The electronic structure analysis reveals that the CO$_2$-TiO$_2$ interaction at the surface is uniaxial and long ranged, which gives rise to anisotropy in binding energy (BE). It negates the widely perceived one-to-one correspondence between coverage and BE and infers that the spatial distribution of CO$_2$ primarily determines the BE. A conceptual experiment is devised where the CO$_2$ concentration and flow direction can be controlled to tune the BE within a large window of ~1.5 eV. The experiment also reveals that a maximum of 50% coverage can be achieved for chemisorption. In the presence of water, the activated carbonate complex forms a bicarbonate complex by overcoming a potential barrier of ~0.9 eV., Comment: 22 pages, 11 figures
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- 2018
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28. Review of Thin Film Transistor Gas Sensors: Comparison with Resistive and Capacitive Sensors
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Singh, A. K., Chowdhury, N. K., Roy, Somnath C., and Bhowmik, B.
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- 2022
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29. Understanding the Effects of Lactose Hydrolysis Modeling on the Main Oligosaccharides in Goat Milk Whey Permeate
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Thum, Caroline, Weinborn, Valerie, Barile, Daniela, McNabb, Warren C, Roy, Nicole C, and de Moura Bell, Juliana Maria Leite Nobrega
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Medicinal and Biomolecular Chemistry ,Organic Chemistry ,Chemical Sciences ,Animals ,Aspergillus oryzae ,Goats ,Hexoses ,Hydrogen-Ion Concentration ,Hydrolysis ,Lactose ,Milk ,Models ,Chemical ,Neuraminic Acids ,Oligosaccharides ,Temperature ,Whey ,Whey Proteins ,beta-Galactosidase ,lactose hydrolysis ,goat milk oligosaccharides ,beta-galactosidase ,transgalactosylation ,whey ,mass spectrometry ,processing ,β-galactosidase ,Theoretical and Computational Chemistry ,Medicinal and biomolecular chemistry ,Organic chemistry - Abstract
Enzymatic hydrolysis of lactose is a crucial step to improve the efficiency and selectivity of membrane-based separations toward the recovery of milk oligosaccharides free from simple sugars. Response surface methodology was used to investigate the effects temperature (25.9 to 54.1 °C) and amount of enzyme (0.17 to 0.32% w/w) at 1, 2, and 4 h of reaction on the efficiency of lactose hydrolysis by Aspergillus oryzae β-galactosidase, preservation of major goat whey oligosaccharides, and on the de-novo formation of oligosaccharides. Lactose hydrolysis above 99% was achieved at 1, 2, and 4 h, not being significantly affected by temperature and amount of enzyme within the tested conditions. Formation of 4 Hexose (Hex) and 4 Hex 1 Hex and an increased de-novo formation of 2 Hex 1 N-Acetyl-Neuraminic Acid (NeuAc) and 2 Hex 1 N-Glycolylneuraminic acid (NeuGc) was observed in all treatments. Overall, processing conditions using temperatures ≤40 °C and enzyme concentration ≤0.25% resulted in higher preservation/formation of goat whey oligosaccharides.
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- 2019
30. “Nourish to Flourish”: complementary feeding for a healthy infant gut microbiome—a non-randomised pilot feasibility study
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Lovell, Amy L., Eriksen, Hannah, McKeen, Starin, Mullaney, Jane, Young, Wayne, Fraser, Karl, Altermann, Eric, Gasser, Olivier, Kussmann, Martin, Roy, Nicole C., McNabb, Warren C., and Wall, Clare R.
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- 2022
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31. Note on a new bridged-T null network
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Dutta Roy, S C
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- 2022
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32. Long-term cognitive, psychosocial, and neurovascular complications of unilateral head and neck irradiation in young to middle-aged adults
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Pruijssen, Judith T., Wenmakers, Ashwin, Kessels, Roy P. C., Piai, Vitoria, Meijer, Frederick J. A., Pegge, Sjoert A. H., Loonen, Jacqueline J., Tuladhar, Anil M., Hansen, Hendrik H. G., Kaanders, Johannes H. A. M., and Wilbers, Joyce
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- 2022
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33. Revisiting passive RC networks with over unity gain
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Dutta Roy, S C
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- 2022
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34. Long-term cognitive, psychosocial, and neurovascular complications of unilateral head and neck irradiation in young to middle-aged adults
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Judith T. Pruijssen, Ashwin Wenmakers, Roy P. C. Kessels, Vitoria Piai, Frederick J. A. Meijer, Sjoert A. H. Pegge, Jacqueline J. Loonen, Anil M. Tuladhar, Hendrik H. G. Hansen, Johannes H. A. M. Kaanders, and Joyce Wilbers
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Head and neck cancer ,Radiotherapy ,Cognition ,Fatigue ,Quality of life ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background With a growing, younger population of head and neck cancer survivors, attention to long-term side-effects of prior, often radiotherapeutic, treatment is warranted. Therefore, we studied the long-term cognitive effects in young adult patients irradiated for head and neck neoplasms (HNN). Methods Young to middle-aged adults with HNN (aged 18-40 years) and treated with unilateral neck irradiation ≥ 5 years before inclusion underwent cardiovascular risk and neuropsychological assessments and answered validated questionnaires regarding subjective cognitive complaints, fatigue, depression, quality of life, and cancer-specific distress. Additionally, magnetic resonance imaging (MRI) of the brain was performed to assess white matter hyperintensities (WMH), infarctions, and atrophy. Results Twenty-nine patients (aged 24–61, 13 men) median 9.2 [7.3–12.9] years post-treatment were included. HNN patients performed worse in episodic memory (Z-score = -1.16 [-1.58–0.34], p
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- 2022
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35. Origin of the bilateral structure of the supernova remnant G296.5+10
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Moranchel-Basurto, A., Velázquez, P. F., Giacani, E., Toledo-Roy, J. C., Schneiter, E. M., De Colle, F., and Esquivel, A.
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
In the present work we have modeled the supernova remnant (SNR) G296.5+10, by means of 3D magnetohydrodynamics (MHD) simulations. This remnant belongs to the bilateral SNR group and has an additional striking feature: the rotation measure (RM) in its eastern and western parts are very different. In order to explain both the morphology observed in radio-continuum and the RM, we consider that the remnant expands into a medium shaped by the superposition of the magnetic field of the progenitor star with a constant Galactic magnetic field. We have also carried out a polarization study from our MHD results, obtaining synthetic maps of the linearly polarized intensity and the Stokes parameters. This study reveals that both the radio morphology and the reported RM for G$296.5+10$ can be explained if the quasi-parallel acceleration mechanism is taking place in the shock front of this remnant., Comment: 9 pages, 7 figures, accepted for publication in MNRAS
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- 2017
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36. A 3D MHD simulation of SN 1006: a polarized emission study for the turbulent case
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Velázquez, P. F., Schneiter, E. M., Reynoso, E. M., Esquivel, A., De Colle, F., Toledo-Roy, J. C., Gómez, D. O., Sieyra, M. V., and Moranchel-Basurto, A.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Three dimensional magnetohydrodynamical simulations were carried out in order to perform a new polarization study of the radio emission of the supernova remnant SN 1006. These simulations consider that the remnant expands into a turbulent interstellar medium (including both magnetic field and density perturbations). Based on the referenced-polar angle technique, a statistical study was done on observational and numerical magnetic field position-angle distributions. Our results show that a turbulent medium with an adiabatic index of 1.3 can reproduce the polarization properties of the SN 1006 remnant. This statistical study reveals itself as a useful tool for obtaining the orientation of the ambient magnetic field, previous to be swept up by the main supernova remnant shock., Comment: 8 pages, 7 figures, accepted for publication in MNRAS
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- 2017
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37. The Development of a Short Form of the Indonesian Version of the Wechsler Adult Intelligence Scale—Fourth Edition
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Christiany Suwartono, Marc P. H. Hendriks, Lidia L. Hidajat, Magdalena S. Halim, and Roy P. C. Kessels
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classification accuracy ,psychological assessment ,intelligence testing ,reliability ,short forms ,validity ,Social sciences (General) ,H1-99 - Abstract
(1) Background: The Wechsler intelligence scales are very popular in clinical practice and for research purposes. However, they are time consuming to administer. Therefore, researchers and psychologists have explored the possibility of shorter test battery compositions. (2) Methods: In this study, we investigated 13 potential short forms of the Indonesian version of the Wechsler Adult Intelligence Scale—Fourth Edition (WAIS-IV-ID). An existing standardization data set of 1745 Indonesian participants collected for the validation of the WAIS-IV-ID was used to examine the short forms’ validity. These ranged from 2-subtest versions to 7-subtest versions. Regression analyses with goodness-of-fit measures were performed, and regression equations were determined for each short form to estimate the Full Scale IQ (FSIQ) score. Discrepancies between the FSIQ and the estimated FSIQ (FSIQEst) scores were examined and classification accuracies were calculated for each short form (% agreement of intelligence classification between the FSIQEst and FSIQ). (3) Results: None of the 13 short form FSIQEst values significantly differed from the FSIQ scores based on the full WAIS-IV-ID, and strong correlations were observed between each of these values. The classification accuracies of the short forms were between 56.8% and 81.0%. The 4-subtest short form of the WAIS-IV-ID consisting of the subtests Matrix Reasoning, Information, Arithmetic, and Coding had the optimal balance between best classification values and a short administration duration. The validity of this short form was demonstrated in a second study in an independent sample (N = 20). (4) Conclusions: Based on the results presented here, the WAIS-IV-ID short forms are able to reliably estimate the FSIQ, with a significant shorter administration duration. The WAIS-IV-ID short form consisting of four subtests, Matrix Reasoning, Information, Arithmetic, and Coding, was the best version according to our criteria.
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- 2023
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38. Long-Term Brain Structure and Cognition Following Bariatric Surgery
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Custers, Emma, primary, Vreeken, Debby, additional, Kleemann, Robert, additional, Kessels, Roy P. C., additional, Duering, Marco, additional, Brouwer, Jonna, additional, Aufenacker, Theo J., additional, Witteman, Bart P. L., additional, Snabel, Jessica, additional, Gart, Eveline, additional, Mutsaerts, Henk J. M. M., additional, Wiesmann, Maximilian, additional, Hazebroek, Eric J., additional, and Kiliaan, Amanda J., additional
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- 2024
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39. Immune regulation and blood–brain barrier permeability in cerebral small vessel disease: study protocol of the INflammation and Small Vessel Disease (INSVD) study – a multicentre prospective cohort study
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Low, Audrey, primary, van Winden, Sanne, additional, Cai, Lupei, additional, Kessels, Roy P C, additional, Maas, Marnix C, additional, Morris, Robin G, additional, Nus, Meritxell, additional, Tozer, Daniel J, additional, Tuladhar, Anil, additional, van der Kolk, Anja, additional, Wolters, Rowan, additional, Mallat, Ziad, additional, Riksen, Niels P, additional, Markus, Hugh, additional, and de Leeuw, Frank‐Erik, additional
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- 2024
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40. Characterization of atmospheric pressure H2O/O2 gliding arc plasma for the production of OH and O radicals
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Roy, N. C., Hafez, M. G., and Talukder, M R
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Physics - Plasma Physics - Abstract
Atmospheric pressure steam/oxygen plasma is generated by a 88 Hz, 6kV AC power supply. The properties of the produced plasma are investigated by optical emission spectroscopy (OES). The relative intensity, rotational, vibrational, excitation temperatures and electron density are studied as function of applied voltage, electrode spacing and oxygen flow rate. The rotational and vibrational temperatures are determined simulating the bands with the aid of LIFBASE simulation software. The excitation temperature is obtained from the CuI transition taking non-thermal equilibrium condition into account employing intensity ratio method. The electron density is approximated from the H_{\alpha} Stark broadening using the Voigt profile fitting method. It is observed that the rotational and vibrational temperatures are decreased with increasing electrode spacing and O2 flow rate, but increased with the applied voltage. The excitation temperature is found to increase with increasing applied voltage and O2 flow rate, but decrease with electrode spacing. The electron density is increased with increasing applied voltage while it seems to downward trend with increasing electrode spacing and O2 flow rate.
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- 2016
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41. Diagnostics of atmospheric pressure capillary DBD oxygen plasma jet
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Roy, N. C., Talukder, M. R., and Pramanik, B. K.
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Physics - Plasma Physics - Abstract
Atmospheric pressure capillary dielectric barrier oxygen discharge plasma jet is developed to generate non-thermal plasma using unipolar positive pulse power supply. Both optical and electrical techniques are used to investigate the characteristics of the produced plasma as function of applied voltage and gas flow rate. Analytical results obtained from the optical emission spectroscopic data reveal the gas temperature, rotational temperature, excitation temperature and electron density. Gas temperature and rotational temperature are found to decrease with increasing oxygen flow rate but increase linearly with applied voltage. It is exposed that the electron density is boosting up with enhanced applied voltage and oxygen flow rate, while the electron excitation temperature is reducing with rising oxygen flow rate. Electrical characterization demonstrates that the discharge frequency is falling with flow rate but increasing with voltage. The produced plasma is applied preliminarily to study the inactivation yield of Fusarium oxysporum infected potato samples.
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- 2015
42. The soft and hard X-rays thermal emission from star cluster winds with a supernova explosion
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Castellanos-Ramirez, A., Rodriguez-Gonzalez, A., Esquivel, A., Toledo-Roy, J. C., Olivares, J., and Velazquez, P. F.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
Massive young star clusters contain dozens or hundreds of massive stars that inject mechanical energy in the form of winds and supernova explosions, producing an outflow which expands into their surrounding medium, shocking it and forming structures called superbubbles. The regions of shocked material can have temperatures in excess of 10$^6$ K, and emit mainly in thermal X-rays (soft and hard). This X-ray emission is strongly affected by the action of thermal conduction, as well as by the metallicity of the material injected by the massive stars. We present three-dimensional numerical simulations exploring these two effects, metallicity of the stellar winds and supernova explosions, as well as thermal conduction., Comment: 14 pages, 12 figures. MNRAS. Accepted
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- 2015
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43. Early-Stage Alzheimer's Disease Affects Fast But Not Slow Adaptive Processes in Motor Learning.
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Sutter, Katrin, Oostwoud Wijdenes, Leonie, van Beers, Robert J., Claassen, Jurgen A. H. R., Kessels, Roy P. C., and Medendorp, W. Pieter
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- 2024
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44. Neuroimaging Parameters Are Not Associated With Chronic Post-stroke Fatigue in Young Stroke Patients
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Esther M. Boot, Sanne A. J. H. van de Camp, Noortje A. Maaijwee, Renate M. Arntz, Roy P. C. Kessels, Frank-Erik de Leeuw, and Anil M. Tuladhar
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young stroke ,post-stroke fatigue ,voxel-based lesion symptom mapping ,brain network ,graph theory ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
IntroductionPost-stroke fatigue is frequently present in young adults, but its underlying mechanism is still unclear. The aim of the study was to investigate the association between lesion location, network efficiency and chronic post-stroke fatigue based on voxel-based lesion-symptom mapping and structural network connectivity analysis.Patients and MethodsOne hundred and thirty five young patients, aged 18–50 years, with a first-ever transient ischemic attack or cerebral infarction from the Follow-Up of Transient ischemic attack and stroke patients and Unelucidated Risk factor Evaluation (FUTURE) study, underwent 1.5T MRI and were assessed for fatigue using the self-report Checklist Individual Strength. Stroke lesions were manually segmented, and structural network efficiency was calculated using the diffusion MRI-based brain networks and graph theory for each patient. Univariate and multivariate analyses was performed to study the associations between MRI parameters and chronic post-stroke fatigue. In addition, we used voxel-based lesion-symptom mapping to analyze the relationship between the lesion location and chronic post-stroke fatigue.ResultsMean age at index event was 39.0 years (SD ± 8.2), and mean follow-up duration was 11.0 years (SD ± 8.0). 50 patients (37%) had post-stroke fatigue. Voxel-based lesion-symptom mapping showed no significant relation between stroke lesions and the presence of chronic post-stroke fatigue. Furthermore, there were no significant associations between the lesion size or network efficiency, and the presence of chronic post-stroke fatigue.DiscussionWe did not find any association between stroke characteristics (lesion location and size) and chronic post-stroke fatigue (CIS20-R), nor associations between structural brain network connectivity and post-stroke fatigue on the long term in young stroke patients.
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- 2022
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45. An asymmetric jet launching model for the protoplanetary nebula CRL 618
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Velazquez, P. F., Riera, A., Raga, A. C., and Toledo-Roy, J. C.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
We propose an asymmetrical jet ejection mechanism in order to model the mirror symmetry observed in the lobe distribution of some protoplanetary nebulae (pPNe), such as the pPN CRL 618. 3D hydrodynamical simulations of a precessing jet launched from an orbiting source were carried out including an alternation in the ejections of the two outflow lobes, depending on which side of the precessing accretion disk is hit by the accretion column from a Roche lobe-filling binary companion. Both synthetic optical emission maps and position-velocity (PV) diagrams were obtained from the numerical results with the purpose of carrying out a direct comparison with observations. Depending on the observer's point of view, multipolar morphologies are obtained which exhibit a mirror symmetry at large distances from the central source. The obtained lobe sizes and their spatial distribution are in good agreement with the observed morphology of the pPN CRL 618. We also obtain that the kinematic ages of the fingers are similar to those obtained in the observations., Comment: 13 pages, 6 figures, submitted to the Astrophysical Journal
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- 2014
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46. A Stellar Wind Origin for the G2 Cloud: Three-Dimensional Numerical Simulations
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De Colle, Fabio, Raga, A. C., Contreras-Torres, Flavio F., and Toledo-Roy, Juan C.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present 3D, adaptive mesh refinement simulations of G2, a cloud of gas moving in a highly eccentric orbit towards the galactic center. We assume that G2 originates from a stellar wind interacting with the environment of the Sgr A* black hole. The stellar wind forms a cometary bubble which becomes increasingly elongated as the star approaches periastron. A few months after periastron passage, streams of material begin to accrete on the central black hole with accretion rates $\dot{M} \sim 10^{-8}$ M$_\odot$ yr$^{-1}$. Predicted Br$\gamma$ emission maps and position-velocity diagrams show an elongated emission resembling recent observations of G2. A large increase in luminosity is predicted by the emission coming from the shocked wind region during periastron passage. The observations, showing a constant Br$\gamma$ luminosity, remain puzzling, and are explained here assuming that the emission is dominated by the free-wind region. The observed Br$\gamma$ luminosity ($\sim 8 \times 10^{30}$ erg s$^{-1}$) is reproduced by a model with a $v_w=50$ km s$^{-1}$ wind velocity and a $10^{-7}$ M$_\odot$ yr$^{-1}$ mass loss rate if the emission comes from the shocked wind. A faster and less dense wind reproduces the Br$\gamma$ luminosity if the emission comes from the inner, free wind region. The extended cometary wind bubble, largely destroyed by the tidal interaction with the black hole, reforms a few years after periastron passage. As a result, the Br$\gamma$ emission is more compact after periastron passage., Comment: 6 pages, 5 figures, submitted to the Astrophysical Journal Letters
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- 2014
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47. Effects of long-term sleep disruption on cognitive function and brain amyloid-β burden: a case-control study
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Jana Thomas, Sharon J. Ooms, Lara J. Mentink, Jan Booij, Marcel G. M. Olde Rikkert, Sebastiaan Overeem, Roy P. C. Kessels, and Jurgen A. H. R. Claassen
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Sleep disruption ,Shift work ,Alzheimer’s disease ,Amyloid-β ,Cognitive function ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Recent evidence indicates that disrupted sleep could contribute to the development of Alzheimer’s disease by influencing the production and/or clearance of the amyloid-β protein. We set up a case-control study to investigate the association between long-term work-induced sleep disruption, cognitive function, and brain amyloid-β burden. Methods Nineteen male maritime pilots (aged 48–60 years) with chronic work-related sleep disruption and a sex-, age-, and education-matched control sample (n = 16, aged 50–60 years) with normal sleep completed the study. Primary sleep disorders were ruled out with in-lab polysomnography. Additional sleep measurements were obtained at home using actigraphy, sleep-wake logs, and a single-lead EEG device. Cognitive function was assessed with a neuropsychological test battery, sensitive to early symptomatic Alzheimer’s disease. Brain amyloid-β burden was assessed in maritime pilots using 18F-flutemetamol amyloid PET-CT. Results Maritime pilots reported significantly worse sleep quality (Pittsburgh Sleep Quality Index (PSQI) = 8.8 ± 2.9) during work weeks, compared to controls (PSQI = 3.2 ± 1.4; 95% CI 0.01 to 2.57; p = 0.049). This was confirmed with actigraphy-based sleep efficiency (86% ± 3.8 vs. 89.3% ± 4.3; 95% CI 0.43 to 6.03; p = 0.03). Home-EEG recordings showed less total sleep time (TST) and deep sleep time (DST) during work weeks compared to rest weeks (TST 318.56 (250.21–352.93) vs. TST 406.17 (340–425.98); p = 0.001; DST 36.75 (32.30–58.58) vs. DST 51.34 (48.37–69.30); p = 0.005)). There were no differences in any of the cognitive domains between the groups. For brain amyloid-β levels, mean global cortical standard uptake value ratios of 18F-flutemetamol were all in the normal range (1.009 ± 0.059; 95% CI 0.980 to 1.037), confirmed by visual reads. Conclusions Capitalizing on the particular work-rest schedule of maritime pilots, this study with a small sample size observed that long-term intermittent sleep disruption had no effects on global brain amyloid-β levels or cognitive function.
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- 2020
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48. Development and preliminary evaluation of the QUALIKO: an observational quality of life instrument for patients with Korsakoff’s syndrome
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Peter M. ten Klooster, Yvonne C. M. Rensen, Jorrit F. Postma, and Roy P. C. Kessels
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Korsakoff’s syndrome ,Nursing homes ,Psychometrics ,Quality of life ,Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
Abstract Background To develop a Korsakoff-specific measure of quality of life (QoL), to be rated by professional caregivers, and to field-test its psychometric properties in a sample of patients with Korsakoff’s syndrome (KS) living in a specialized nursing home. Methods A research version of the QUALIKO was developed based on an existing instrument for dementia (the QUALIDEM), literature review and two rounds of surveys among expert professionals involved in the care for patients with KS. Next, QoL was independently rated using the preliminary QUALIKO for 77 patients with KS by two primary caregivers. Results The research QUALIKO consisted of 48 items describing observable behaviors across ten aspects of QoL relevant to patients with KS. Six items demonstrated poor scalability in the field test. The remaining 42 items all formed subscales with moderate to strong scalability according to Mokken scale analysis. Reliability was acceptable to good across both raters for all subscales (Mokken rho’s = 0.70–0.90), except for the two 2-item subscales of negative affect and positive self-image (Mokken rho’s = 0.47–0.71). Inter-observer agreement was excellent for five subscales (ICCs = 0.75–0.89) and fair to moderate for the other five subscales (ICCs = 0.59–0.72). The multidimensional internal structure was confirmed and all subscales were significantly correlated with primary caregivers’ global ratings of QoL except for positive self-image. Missing item values were low and floor and ceiling effects acceptable for most subscales. Conclusions The QUALIKO holds promise as a feasible, reliable, and valid measure of QoL in residential KS patients. Future research in larger samples is needed to confirm the psychometric dimensionality of the instrument, to gather normative data and to examine its test-retest reliability.
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- 2020
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49. Objective cognitive performance and subjective complaints in patients with chronic Q fever or Q fever fatigue syndrome
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Daphne F. M. Reukers, Justine Aaronson, Joris A. F. van Loenhout, Birte Meyering, Koos van der Velden, Jeannine L. A. Hautvast, Cornelia H. M. van Jaarsveld, and Roy P. C. Kessels
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Coxiella Burnetii ,Post-infectious fatigue syndrome ,Bacterial endocarditis ,Neuropsychological test ,Performance validity ,Cognitive symptoms ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Primary aim of this study was to compare cognitive performance of patients with chronic Q fever or Q fever fatigue syndrome (QFS) to matched controls from the general population, while taking performance validity into account. Second, we investigated whether objective cognitive performance was related to subjective cognitive complaints or psychological wellbeing. Methods Cognitive functioning was assessed with a neuropsychological test battery measuring the domains of processing speed, episodic memory, working memory and executive functioning. Tests for performance validity and premorbid intelligence were also included. Validated questionnaires were administered to assess self-reported fatigue, depressive symptoms and cognitive complaints. Results In total, 30 patients with chronic Q fever, 32 with QFS and 35 controls were included. A high percentage of chronic Q fever patients showed poor performance validity (38%) compared to controls (14%, p = 0.066). After exclusion of participants showing poor performance validity, no significant differences between patients and controls were found in the cognitive domains. QFS patients reported a high level of cognitive complaints compared to controls (41.2 vs 30.4, p = 0.023). Cognitive complaints were not significantly related to cognitive performance in any of the domains for this patient group. Conclusions The high level of self-reported cognitive complaints in QFS patients does not indicate cognitive impairment. A large proportion of the chronic Q fever patients showed suboptimal mental effort during neuropsychological assessment. More research into the underlying explanations is needed. Our findings stress the importance of assessing cognitive functioning by neuropsychological examination including performance validity, rather than only measuring subjective cognitive complaints.
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- 2020
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50. The short-term effects of sedentary behaviour on cerebral hemodynamics and cognitive performance in older adults: a cross-over design on the potential impact of mental and/or physical activity
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Carlijn M. Maasakkers, René J. F. Melis, Roy P. C. Kessels, Paul A. Gardiner, Marcel G. M. Olde Rikkert, Dick H. J. Thijssen, and Jurgen A. H. R. Claassen
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Cerebral vasculature ,Cognitive decline ,Dementia ,Physical inactivity ,Sitting ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Sedentary behaviour might be a potential risk factor for cognitive decline. However, the short-term effects of sedentary behaviour on (cerebro) vascular and cognitive performance in older people are unknown. Methods We used a cross-over design with 22 older adults (78 years, 9 females) to assess the short-term hemodynamic and cognitive effects of three hours uninterrupted sitting and explored if these effects can be counteracted with regular (every 30 min) two-minute walking breaks. In addition, we investigated if low versus high mental activity during the three hours of sitting modified these effects. Before and after each condition, alertness, executive functioning, and working memory were assessed with the Test of Attentional Performance battery. Additionally, cerebral blood flow velocity (Transcranial Doppler) and blood pressure (Finapres) were measured in rest, and during sit-to-stand and CO2 challenges to assess baroreflex sensitivity, cerebral autoregulation, and cerebral vasomotor reactivity. Results No short-term differences were observed in cognitive performance, cerebral blood flow velocity, baroreflex sensitivity, cerebral autoregulation, or cerebral vasomotor reactivity across time, or between conditions. Blood pressure and cerebrovascular resistance increased over time (8.6 mmHg (5.0;12.1), p
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- 2020
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