233 research outputs found

    Investigating the mass-ratio dependence of the prompt-collapse threshold with numerical-relativity simulations

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    The next observing runs of advanced gravitational-wave detectors will lead to a variety of binary neutron star detections and numerous possibilities for multi-messenger observations of binary neutron star systems. In this context a clear understanding of the merger process and the possibility of prompt black hole formation after merger is important, as the amount of ejected material strongly depends on the merger dynamics. These dynamics are primarily affected by the total mass of the binary, however, the mass ratio also influences the postmerger evolution. To determine the effect of the mass ratio, we investigate the parameter space around the prompt-collapse threshold with a new set of fully relativistic simulations. The simulations cover three equations of state and seven mass ratios in the range of 1.0q1.751.0 \leq q \leq 1.75, with five to seven simulations of binary systems of different total mass in each case. The threshold mass is determined through an empirical relation based on the collapse-time, which allows us to investigate effects of the mass-ratio on the threshold mass and also on the properties of the remnant system. Furthermore, we model effects of mass ratio and equation of state on tidal parameters of threshold configurations

    Image sets of perfectly nonlinear maps

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    We present a lower bound on the image size of a dd-uniform map, d1d\geq 1, of finite fields, by extending the methods used for planar maps. In the particularly interesting case of APN maps on binary fields, our bound coincides with the one obtained by Ingo Czerwinski, using a linear programming method. We study properties of APN maps of F2n\mathbb{F}_{2^n} with minimal image set. In particular, we observe that for even nn, a Dembowski-Ostrom polynomial of form f(x)=f(x3)f(x) =f'(x^3) is APN if and only if ff is almost-3-to-1, that is when its image set is minimal. We show that any almost-3-to-1 quadratic map is APN, if nn is even. For nn odd, we present APN Dembowski-Ostrom polynomials on F2n\mathbb{F}_{2^n} with image sizes 2n1 2^{n-1} and 52n35\cdot 2^{n-3}. We present several results connecting the image sets of special APN maps with their Walsh spectrum. Especially, we show that a large class of APN maps has the classical Walsh spectrum. Finally, we prove that the image size of a non-bijective almost bent map contains at most 2n2(n1)/22^n-2^{(n-1)/2} elements.Comment: Minor revision with new references; Theorems 18, 19 are adde

    Neocortical substrates of feelings evoked with music in the ACC, insula, and somatosensory cortex

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    Neurobiological models of emotion focus traditionally on limbic/paralimbic regions as neural substrates of emotion generation, and insular cortex (in conjunction with isocortical anterior cingulate cortex, ACC) as the neural substrate of feelings. An emerging view, however, highlights the importance of isocortical regions beyond insula and ACC for the subjective feeling of emotions. We used music to evoke feelings of joy and fear, and multivariate pattern analysis (MVPA) to decode representations of feeling states in functional magnetic resonance (fMRI) data of n = 24 participants. Most of the brain regions providing information about feeling representations were neocortical regions. These included, in addition to granular insula and cingulate cortex, primary and secondary somatosensory cortex, premotor cortex, frontal operculum, and auditory cortex. The multivoxel activity patterns corresponding to feeling representations emerged within a few seconds, gained in strength with increasing stimulus duration, and replicated results of a hypothesis-generating decoding analysis from an independent experiment. Our results indicate that several neocortical regions (including insula, cingulate, somatosensory and premotor cortices) are important for the generation and modulation of feeling states. We propose that secondary somatosensory cortex, which covers the parietal operculum and encroaches on the posterior insula, is of particular importance for the encoding of emotion percepts, i.e., preverbal representations of subjective feeling.publishedVersio

    Adsorptionsuntersuchungen an Organokieselsäurepolymeren

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    BET-Oberflächen und Isothermen von n-Hexan, Benzen, Wasser und Stickstoff wurden an vier Organokieselsäurepolymeren vermessen, die sich im Vernetzungsgrad der Doppelvierring-Kieselsäureeinheiten Si8O20 und in der Struktur der Brücken unterscheiden. Ein Polymer ist mikroporös, die anderen sind makroporös. Alle Polymere verhalten sich hydrophob. Neben der Adsorption tritt Quellung bei der Einwirkung organischer Adsorptive auf. Die Zusammenhänge zwischen der Länge der Brücken und der Porosität werden diskutiert

    Impact of NDI‐core substitution on the pH‐responsive nature of peptide‐tethered luminescent supramolecular polymers

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    The pH‐responsive nature of two self‐assembled NDI‐peptide amphiphile conjugates is reported. The diethoxy substituted NDI showed a pH‐dependent assembly behaviour, as expected. In contrast, the isopropylamino‐ and ethoxy‐substituted NDI based supramolecular polymer was stable at acidic and basic aqueous conditions. This finding highlights how subtle changes in the molecular design of π‐stacked chromophore‐peptide conjugates have a drastic impact on their equilibrium structure and ultimately functional properties

    Разработка отклонителя для управления направлением скважин при ударно-вращательном бурении

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    Die Kombination einer Membran mit einer katalytischen Reaktion in einem Membranreaktor ist eines der Konzepte multifunktionaler Reaktoren zur Prozessintensivierung. Eine industriell besonders interessante Anwendung ist dabei die Darstellung von Synthesegas durch partielle Oxidation von Methan zu Kohlenmonoxid und Wasserstoff, wobei der Sauerstoff durch eine gemischtleitende Perowskit-Membran aus Luft zudosiert wird. Es ist gelungen, entsprechende Perowskit-Membranen als Hohlfasern mit einer volumenbezogenen Membranfläche von bis zu 500 m<sup>2</sup>/m<sup>3</sup> durch einen ökonomischen Spinnprozess zu entwickeln. Unter Laborbedingungen konnten langzeitstabil Synthesegas (CO, H<sub>2</sub>) mit einer CO-Selektivität von 95 % bei 95 % CH<sub>4</sub>-Umsatz erzeugt und die Ergebnisse durch eine detaillierte mathematische Modellierung beschrieben werden. Copyright © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [accessed February 8th 2013

    24S‐hydroxycholesterol: cellular effects and variations in brain diseases

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    The adult brain exhibit a characteristic cholesterol homeostasis, with low synthesis rate and active catabolism. Brain cholesterol turnover is possible thanks to the action of the enzyme Cytochrome P450 46A1 (CYP46A1) or 24-cholesterol hydroxylase, that transforms cholesterol into 24S-hydroxycholesterol (24S-HC). But before crossing the blood-brain barrier (BBB), this oxysterol that is the most abundant in the brain can act locally, affecting the functioning of neurons, astrocytes, oligodendrocytes, and vascular cells. The first part of this review addresses different aspects of 24S-HC production and elimination from the brain. The second part concentrates in the effects of 24S-HC at the cellular level, describing how this oxysterol affects cell viability, amyloid beta production, neurotransmission, and transcriptional activity. Finally, the role of 24S-HC in Alzheimer, Huntington and Parkinson diseases, multiple sclerosis and amyotrophic lateral sclerosis, as well as the possibility of using this oxysterol as predictive and/or evolution biomarker in different brain disorders is discussed.Fil: Sodero, Alejandro Omar. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentin

    Diagnostic biomarkers for adult haemophagocytic lymphohistiocytosis in critically ill patients (HEMICU): a prospective observational study protocol

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    INTRODUCTION: Haemophagocytic lymphohistiocytosis (HLH) in adults is characterised by toxic immune activation and a sepsis-like syndrome, leading to high numbers of undiagnosed cases and mortality rates of up to 68%. Early diagnosis and specific immune suppressive treatment are mandatory to avoid fatal outcome, but the diagnostic criteria (HLH-2004) are adopted from paediatric HLH and have not been validated in adults. Experimental studies suggest biomarkers to sufficiently diagnose HLH. However, biomarkers for the diagnosis of adult HLH have not yet been investigated. METHODS AND ANALYSIS: The HEMICU (Diagnostic biomarkers for adult haemophagocytic lymphohistiocytosis in critically ill patients) study aims to estimate the incidence rate of adult HLH among suspected adult patients in intensive care units (ICUs). Screening for HLH will be performed in 16 ICUs of Charité - Universitätsmedizin Berlin. The inclusion criteria are bicytopaenia, hyperferritinaemia (≥500 µg/L), fever or when HLH is suspected by the clinician. Over a period of 2 years, we expect inclusion of about 100 patients with suspected HLH. HLH will be diagnosed if at least five of the HLH-2004 criteria are fulfilled, together with an expert review; all other included patients will serve as controls. Second, a panel of potential biomarker candidates will be explored. DNA, plasma and serum will be stored in a biobank. The primary endpoint of the study is the incidence rate of adult HLH among suspected adult patients during ICU stay. Out of a variety of measured biomarkers, this study furthermore aims to find highly potential biomarkers for the diagnosis of adult HLH in ICU. The results of this study will contribute to improved recognition and patient outcome of adult HLH in clinical routine

    Apolipoprotein E-dependent load of white matter hyperintensities in Alzheimer’s disease: a voxel-based lesion mapping study

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    Introduction: White matter (WM) magnetic resonance imaging (MRI) hyperintensities are common in Alzheimer’s disease (AD), but their pathophysiological relevance and relationship to genetic factors are unclear. In the present study, we investigated potential apolipoprotein E (APOE)-dependent effects on the extent and cognitive impact of WM hyperintensities in patients with AD. Methods: WM hyperintensity volume on fluid-attenuated inversion recovery images of 201 patients with AD (128 carriers and 73 non-carriers of the APOE ε4 risk allele) was determined globally as well as regionally with voxel-based lesion mapping. Clinical, neuropsychological and MRI data were collected from prospective multicenter trials conducted by the German Dementia Competence Network. Results: WM hyperintensity volume was significantly greater in non-carriers of the APOE ε4 allele. Lesion distribution was similar among ε4 carriers and non-carriers. Only ε4 non-carriers showed a correlation between lesion volume and cognitive performance. Conclusion: The current findings indicate an increased prevalence of WM hyperintensities in non-carriers compared with carriers of the APOE ε4 allele among patients with AD. This is consistent with a possibly more pronounced contribution of heterogeneous vascular risk factors to WM damage and cognitive impairment in patients with AD without APOE ε4-mediated risk
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