Possible origin of β\beta-relaxation in amorphous metal alloys from atomic-mass differences of the constituents

We employ an atomic-scale theory within the framework of nonaffine lattice dynamics to uncover the origin of the Johari-Goldstein (JG) $\beta$-relaxation in metallic glasses (MGs). Combining simulation and experimental data with our theoretical approach, we reveal that the large mass asymmetry between the elements in a La$_{60}$Ni$_{15}$Al$_{25}$ MG leads to a clear separation in the respective relaxation time scales, giving strong evidence that JG relaxation is controlled by the lightest atomic species present. Moreover, we show that only qualitative features of the vibrational density of states determine the overall observed mechanical response of the glass, paving the way for a possible unified theory of secondary relaxations in glasses

Multiple-bounce Smith Microfacet BRDFs using the Invariance Principle

Smith microfacet models are widely used in computer graphics to represent materials. Traditional microfacet models do not consider the multiple bounces on microgeometries, leading to visible energy missing, especially on rough surfaces. Later, as the equivalence between the microfacets and volume has been revealed, random walk solutions have been proposed to introduce multiple bounces, but at the cost of high variance. Recently, the position-free property has been introduced into the multiple-bounce model, resulting in much less noise, but also bias or a complex derivation. In this paper, we propose a simple way to derive the multiple-bounce Smith microfacet bidirectional reflectance distribution functions (BRDFs) using the invariance principle. At the core of our model is a shadowing-masking function for a path consisting of direction collections, rather than separated bounces. Our model ensures unbiasedness and can produce less noise compared to the previous work with equal time, thanks to the simple formulation. Furthermore, we also propose a novel probability density function (PDF) for BRDF multiple importance sampling, which has a better match with the multiple-bounce BRDFs, producing less noise than previous naive approximations

Escaping from pollution: the effect of air quality on inter-city population mobility in China

China faces severe air pollution issues due to the rapid growth of the economy, causing concerns for human physical and mental health as well as behavioral changes. Such adverse impacts can be mediated by individual avoidance behaviors such as traveling from polluted cities to cleaner ones. This study utilizes smartphone-based location data and instrumental variable regression to try and find out how air quality affects population mobility. Our results confirm that air quality does affect the population outflows of cities. An increase of 100 points in the air quality index will cause a 49.60% increase in population outflow, and a rise of 1 μg m−3 in PM2.5 may cause a 0.47% rise in population outflow. Air pollution incidents can drive people to leave their cities 3 days or a week later by railway or road. The effect is heterogeneous among workdays, weekends and holidays. Our results imply that air quality management can be critical for urban tourism and environmental competitiveness

Chip-scale demonstration of hybrid III-V/silicon photonic integration for an FBG interrogator

Silicon photonic integration is a means to produce an integrated on-chip fiber Bragg grating (FBG) interrogator. The possibility of integrating the light source, couplers, grating couplers, de-multiplexers, photodetectors (PDs), and other optical elements of the FBG interrogator into one chip may result in game-changing performance advances, considerable energy savings, and significant cost reductions. To the best of our knowledge, this paper is the first to present a hybrid silicon photonic chip based on III–V/silicon-on-insulator photonic integration for an FBG interrogator. The hybrid silicon photonic chip consists of a multiwavelength vertical-cavity surface-emitting laser array and input grating couplers, a multimode interference coupler, an arrayed waveguide grating, output grating couplers, and a PD array. The chip can serve as an FBG interrogator on a chip and offer unprecedented opportunities. With a footprint of 5mm x 3mm, the proposed hybrid silicon photonic chip achieves an interrogation wavelength resolution of approximately 1 pm and a wavelength accuracy of about ±10 pm. With the measured 1 pm wavelength resolution, the temperature measurement resolution of the proposed chip is approximately 0.1°C. The proposed hybrid silicon photonic chip possesses advantages in terms of cost, manufacturability, miniaturization, and performance. The chip supports applications that require extreme miniaturization down to the level of smart grains

Intrachromosomal Looping Is Required for Activation of Endogenous Pluripotency Genes during Reprogramming

SummaryGeneration of induced pluripotent stem cells (iPSCs) by defined factors is an extremely inefficient process, because there is a strong epigenetic block preventing cells from achieving pluripotency. Here we report that virally expressed factors bound to the promoters of their target genes to the same extent in both iPSCs and unreprogrammed cells (URCs). However, expression of endogenous pluripotentcy genes was observed only in iPSCs. Comparison of local chromatin structure of the OCT4 locus revealed that there was a cohesin-complex-mediated intrachromosomal loop that juxtaposes a downstream enhancer to the gene’s promoter, enabling activation of endogenous stemness genes. None of these long-range interactions were observed in URCs. Knockdown of the cohesin-complex gene SMC1 by RNAi abolished the intrachromosomal interaction and affected pluripotency. These findings highlight the importance of the SMC1-orchestrated intrachromosomal loop as a critical epigenetic barrier to the induction of pluripotency

Interruption of intrachromosomal looping by CCCTC binding factor decoy proteins abrogates genomic imprinting of human insulin-like growth factor II

CCCTC binding factor (CTCF) mutants that cannot bind components of the polycomb repressive complex-2 (PRC2) do not form the chromatin loops that regulate monoallelic gene expression

A Common SMAD7 Variant Is Associated with Risk of Colorectal Cancer: Evidence from a Case-Control Study and a Meta-Analysis

<div><h3>Background</h3><p>A common genetic variant, rs4939827, located in <em>SMAD7</em>, was identified by two recent genome-wide association (GWA) studies to be strongly associated with the risk of colorectal cancer (CRC). However, the following replication studies yielded conflicting results.</p> <h3>Method and Findings</h3><p>We conducted a case-control study of 641 cases and 1037 controls in a Chinese population and then performed a meta-analysis, integrating our and published data of 34313 cases and 33251 controls, to clarify the relationship between rs4939827 and CRC risk. In our case-control study, the dominant model was significant associated with increased CRC risk [Odds Ratio (OR) = 1.46; 95% confidence interval (95% CI), 1.19–1.80]. The following meta-analysis further confirmed this significant association for all genetic models but with significant between-study heterogeneity (all <em>P</em> for heterogeneity <0.1). By stratified analysis, we revealed that ethnicity, sample size, and tumor sites might constitute the source of heterogeneity. The cumulative analysis suggested that evident tendency to significant association was seen with adding study samples over time; whilst, sensitive analysis showed results before and after removal of each study were similar, indicating the highly stability of the current results.</p> <h3>Conclusion</h3><p>Results from our case-control study and the meta-analysis collectively confirmed the significant association of the variant rs4939827 with increased risk of colorectal cancer. Nevertheless, fine-mapping of the susceptibility loci defined by rs4939287 should be imposed to reveal causal variant.</p> </div

Traitement d’image pour la détection d’objet et le problème d’appariement de graphe : du développement sous Matlab à une infrastructure GPU

Automatically finding correspondences between object features in images is of main interest for several applications, as object detection and tracking, flow velocity estimation, identification, registration, and many derived tasks. In this thesis, we address feature correspondence within the general framework of graph matching optimization and with the principal aim to contribute, at a final step, to the design of new and parallel algorithms and their implementation on GPU (Graphics Processing Unit) systems. Graph matching problems can have many declinations, depending on the assumptions of the application at hand. We observed a gap between applications based on local cost objective functions, and those applications with higher-order cost functions, that evaluate similarity between edges of the graphs, or hyperedges when considering hypergraphs. The former class provides convolution-based algorithms already having parallel GPU implementations. Whereas, the latter class puts the emphasis on geometric inter-feature relationships, transforming the correspondence problem to a purely geometric problem stated in a high dimensional space, generally modeled as an integer quadratic programming, for which we did not find GPU implementations available yet.Two complementary approaches were adopted in order to contribute to addressing higher-order geometric graph matching on GPU. Firstly, we study different declinations of feature correspondence problems by the use of the Matlab platform, in order to reuse and provide state-of-the-art solution methods, as well as experimental protocols and input data necessary for a GPU platform with evaluation and comparison tools against existing sequential algorithms, most of the time developed in Matlab framework. Then, the first part of this work concerns three contributions, respectively, to background and frame difference application, to feature extraction problem from images for local correspondences, and to the general graph matching problem, all based on the combination of methods derived from Matlab environment. Secondly, and based on the results of Matlab developments, we propose a new GPU framework written in CUDA C++ specifically dedicated to geometric graph matching but providing new parallel algorithms, with lower computational complexity, as the self-organizing map in the plane, derived parallel clustering algorithms, and distributed local search method. These parallel algorithms are then evaluated and compared to the state-of-the-art methods available for graph matching and following the same experimental protocol. This GPU platform constitutes our final and main proposal to contribute to bridging the gap between GPU development and higher-order graph matching.Déterminer des mises en correspondance d’objet, ou de caractéristiques d’objet, dans des images présente un grand intérêt pour beaucoup d’applications telles que la détection et le suivi de cible, l’estimation du flot optique, l’identification, et d’autres tâches dérivées. Dans cette thèse, nous abordons le problème de mise en correspondance dans le cadre général de l’optimisation de l’appariement de graphe, dans le but de contribuer, comme résultat final, au développement de nouveaux algorithmes parallèles implémentés sur plateforme GPU (Graphics Processing Unit). Le problème d’appariement de graphe peut être décliné de diverses manières suivant l’application considérée. Nous observons un fossé entre les applications basées sur des fonctions de coût locales et les applications avec des fonctions de coût d’ordre supérieur, évaluant la similarité entre les arêtes du graphe, ou les hyperliens lorsqu’il s’agit d’un hypergraphe. La première classe d’applications comporte des algorithmes de résolution basés sur des calculs de convolution et possède déjà des implémentations parallèles sur GPU. La deuxième classe d’applications met l’accent sur les relations géométriques entre caractéristiques extraites de l’image, transformant le problème de mise en correspondance en un programme quadratique en nombre entiers avec contraintes, pour lequel nous n’avons pas trouvé de solution GPU accessible actuellement.Deux types d’approche ont été adoptées pour contribuer à la problématique d’appariement de graphe sur GPU. Premièrement, nous étudions différentes déclinaisons de cette problématique via l’utilisation de la plateforme Matlab afin de pouvoir réutiliser et fournir des solutions représentatives de l’état de l’art, ainsi que des protocoles d’expérimentation et des données d’entrée nécessaires pour une plateforme GPU dédiée à l’évaluation et la comparaison avec les algorithmes séquentiels sur Matlab. Ainsi, une première partie du travail concerne trois contributions respectivement, aux techniques de soustraction d’arrière-plan et de différence d’image pour la détection, au problème d’extraction de caractéristiques pour la mise en correspondance, et au problème général d’appariement de graphe, toutes basées sur la combinaison de méthodes issues de l’environnement Matlab. Deuxièmement, nous proposons une infrastructure logicielle GPU nouvelle, écrite en CUDA C++, spécifiquement adaptée au problème d’appariement de graphe géométrique, proposant de nouveaux algorithmes parallèles de complexité calculatoire plus réduite, tels que les cartes auto-organisatrices dans le plan, des algorithmes de cluster qui en sont dérivés, et des recherches locales distribuées. Ces algorithmes parallèles sont évalués et comparés aux approches de l’état de l’art pour le problème d’appariement de graphe, en suivant un protocole d’expérimentation identique. Cette plateforme GPU constitue notre principale proposition pour contribuer à combler le fossé entre développement GPU et son application au problème général d’appariement de graphe

Ultrastructure of spermatozoa in three cicada species from China (Hemiptera, Cicadomorpha, Cicadidae)

Volume: 776Start Page: 61End Page: 8