32,767 research outputs found

    Audiovisual temporal correspondence modulates human multisensory superior temporal sulcus plus primary sensory cortices

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    The brain should integrate related but not unrelated information from different senses. Temporal patterning of inputs to different modalities may provide critical information about whether those inputs are related or not. We studied effects of temporal correspondence between auditory and visual streams on human brain activity with functional magnetic resonance imaging ( fMRI). Streams of visual flashes with irregularly jittered, arrhythmic timing could appear on right or left, with or without a stream of auditory tones that coincided perfectly when present ( highly unlikely by chance), were noncoincident with vision ( different erratic, arrhythmic pattern with same temporal statistics), or an auditory stream appeared alone. fMRI revealed blood oxygenation level-dependent ( BOLD) increases in multisensory superior temporal sulcus (mSTS), contralateral to a visual stream when coincident with an auditory stream, and BOLD decreases for noncoincidence relative to unisensory baselines. Contralateral primary visual cortex and auditory cortex were also affected by audiovisual temporal correspondence or noncorrespondence, as confirmed in individuals. Connectivity analyses indicated enhanced influence from mSTS on primary sensory areas, rather than vice versa, during audiovisual correspondence. Temporal correspondence between auditory and visual streams affects a network of both multisensory ( mSTS) and sensory-specific areas in humans, including even primary visual and auditory cortex, with stronger responses for corresponding and thus related audiovisual inputs

    Etude numérique de la convection naturelle dans une enceinte fermée inclinée

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    La méthode de Lattice Boltzmann (LBM), des Différences Finies Explicites (DFE), Hybride combinant les deux méthodes précédentes et la méthode des Eléments finis (EF) sont utilisées afin de simuler la convection naturelle se développant dans une cavité de section droite carrée, contenant de l’air. Deux parois opposées sont à la température Tc et les deux autres à Tf avec Tc>Tf. La cavité est inclinée de 45° par rapport à l’horizontal. Les équations de transfert et les conditions aux limites sont adimensionnalisées et discrétisées. Une série de simulations est faite pour différentes valeurs du nombre de Rayleigh, c'est à dire pour différentes valeurs de l'écart de température entre les parois chaudes et les parois froides. L'analyse comparative des différentes méthodes montre que, pour les faibles nombres de Rayleigh, leurs performances sont à peu près les mêmes. Lorsque ce nombre augmente, la méthode LBM exige un maillage très fin du domaine d'étude, donc un temps de calcul beaucoup plus long. Par ailleurs, les simulations faites à l'aide des quatre méthodes ont toutes montré que pour Ra = 105 le régime est oscillant amorti, il est oscillant périodique à un nombre de Rayleigh Ra = 2.105 et chaotique à un nombre de Rayleigh Ra = 1,2.106. Le principal avantage de la méthode LBM par rapport aux autres réside dans la simplicité de sa mise en oeuvre.Mots-clés: convection naturelle, chaos, méthode de Lattice Boltzmann, methode des différences finies. Numerical Study of natural convection in an inclined enclosureLattice Boltzmann Method (LBM ) , Finite Difference Explicit ( DFE ) , Hybrid combines the two previous methods and Finite Elements (FE) are used to study numerically natural convection inside a square air-filled cavity. Two opposite walls are in the temperature Tc and the the two another one in Tf,with Tc>Tf. The cavity is inclined to 45° relative to the horizontal plan. The dimensionless transfer equations and boundary conditions are discretised. A series of simulations is made for various values of Rayleigh number, that is for different values of the temperature difference between the heated and cooled walls. A comparative analysis of results given by different methods shows that for low Rayleigh numbers their performance is almost the same. When this number increases, LBM method requires a very fine mesh of the study area, so a much longer calculation time. In addition, simulations using four methods show that for Ra = 105 the system is damped oscillating, it is oscillating periodic for Ra = 2.105 and oscillating chaotic for Ra = 1,2.106. The main advantage of the LBM method compared to other lies in the simplicity of its implementation.Keywords: natural convection, chaos - Lattice Boltzmann Method , finite difference method

    Evidence for frequent incest in a cooperatively breeding mammal.

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    As breeding between relatives often results in inbreeding depression, inbreeding avoidance is widespread in the animal kingdom. However, inbreeding avoidance may entail fitness costs. For example, dispersal away from relatives may reduce survival. How these conflicting selection pressures are resolved is challenging to investigate, but theoretical models predict that inbreeding should occur frequently in some systems. Despite this, few studies have found evidence of regular incest in mammals, even in social species where relatives are spatio-temporally clustered and opportunities for inbreeding frequently arise. We used genetic parentage assignments together with relatedness data to quantify inbreeding rates in a wild population of banded mongooses, a cooperatively breeding carnivore. We show that females regularly conceive to close relatives, including fathers and brothers. We suggest that the costs of inbreeding avoidance may sometimes outweigh the benefits, even in cooperatively breeding species where strong within-group incest avoidance is considered to be the norm

    GCalignR: An R package for aligning gas-chromatography data for ecological and evolutionary studies.

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    Chemical cues are arguably the most fundamental means of animal communication and play an important role in mate choice and kin recognition. Consequently, there is growing interest in the use of gas chromatography (GC) to investigate the chemical basis of eco-evolutionary interactions. Both GC-MS (mass spectrometry) and FID (flame ionization detection) are commonly used to characterise the chemical composition of biological samples such as skin swabs. The resulting chromatograms comprise peaks that are separated according to their retention times and which represent different substances. Across chromatograms of different samples, homologous substances are expected to elute at similar retention times. However, random and often unavoidable experimental variation introduces noise, making the alignment of homologous peaks challenging, particularly with GC-FID data where mass spectral data are lacking. Here we present GCalignR, a user-friendly R package for aligning GC-FID data based on retention times. The package was developed specifically for ecological and evolutionary studies that seek to investigate similarity patterns across multiple and often highly variable biological samples, for example representing different sexes, age classes or reproductive stages. The package also implements dynamic visualisations to facilitate inspection and fine-tuning of the resulting alignments and can be integrated within a broader workflow in R to facilitate downstream multivariate analyses. We demonstrate an example workflow using empirical data from Antarctic fur seals and explore the impact of user-defined parameter values by calculating alignment error rates for multiple datasets. The resulting alignments had low error rates for most of the explored parameter space and we could also show that GCalignR performed equally well or better than other available software. We hope that GCalignR will help to simplify the processing of chemical datasets and improve the standardization and reproducibility of chemical analyses in studies of animal chemical communication and related fields

    Activity- and reactivity-based proteomics: Recent technological advances and applications in drug discovery.

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    Activity-based protein profiling (ABPP) is recognized as a powerful and versatile chemoproteomic technology in drug discovery. Central to ABPP is the use of activity-based probes to report the activity of specific enzymes or reactivity of amino acid types in complex biological systems. Over the last two decades, ABPP has facilitated the identification of new drug targets and discovery of lead compounds in human and infectious disease. Furthermore, as part of a sustained global effort to illuminate the druggable proteome, the repertoire of target classes addressable with activity-based probes has vastly expanded in recent years. Here, we provide an overview of ABPP and summarise the major technological advances with an emphasis on probe development

    Histopathologic parameters as predictors of response to endoscopic sinus surgery in nonallergic patients with chronic rhinosinusitis

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    OBJECTIVE: To estimate the predictable value of histopathologic parameters in chronic rhinosinusitis (CRS) for response to endoscopic sinus surgery (ESS). - - - - - STUDY DESIGN: Symptomatology was rated in 100 patients prior to as well as 12 and 24 months after surgery. Specimens taken during the procedure were examined and scored for goblet cells, subepithelial thickening, mast cells, and eosinophils. Multiple regression analysis was performed to predict the total score of subjective symptoms before treatment by histopathologic parameters. The correlation between histopathologic parameters and postoperative symptoms was then evaluated. - - - - - RESULTS: Goblet cells were the best predictor correlating with 5 symptoms. Subepithelial thickening correlated with 4 symptoms. Mast cell infiltration correlated with 3 symptoms. Eosinophilic infiltration correlated with only one symptom (P<0.05). - - - - - CONCLUSION: Certain histopathologic parameters in CRS are predictive of favorable response to ESS. - - - - - SIGNIFICANCE: Pathologic evaluation may help the ENT surgeon to predict the persistence of certain CRS symptoms after ESS, even in patients at low risk for surgical failure. - - - - - EBM rating: C-4

    Updates on polyurethane and its multifunctional applications in biomedical engineering

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    Polyurethanes (PUs) have properties that make them promising in biomedical applications. PU is recognized as one of the main families of blood and biocompatible materials. PU plays a vital role in the design of medical devices in various medical fields. The structure of PU contains two segments: soft and hard. Its elastomeric feature is due to its soft segment, and its excellent and high mechanical property is because of its hard segment. It is possible to achieve specific desirable and targeted properties by changing the soft and hard chemical structures and the ratio between them. The many properties of PU each draw the attention of different medical fields. This work reviews PU highlighted properties, such as biodegradability, biostability, shape memory, and improved antibacterial activity. Also, because PU has a variety of applications, this review restricts its focus to PU's prominent applications in tissue engineering, cardiovascular medicine, drug delivery, and wound healing. In addition, it contains a brief review of PU's applications in biosensors and oral administration

    Theory of Photon Blockade by an Optical Cavity with One Trapped Atom

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    In our recent paper [1], we reported observations of photon blockade by one atom strongly coupled to an optical cavity. In support of these measurements, here we provide an expanded discussion of the general phenomenology of photon blockade as well as of the theoretical model and results that were presented in Ref. [1]. We describe the general condition for photon blockade in terms of the transmission coefficients for photon number states. For the atom-cavity system of Ref. [1], we present the model Hamiltonian and examine the relationship of the eigenvalues to the predicted intensity correlation function. We explore the effect of different driving mechanisms on the photon statistics. We also present additional corrections to the model to describe cavity birefringence and ac-Stark shifts. [1] K. M. Birnbaum, A. Boca, R. Miller, A. D. Boozer, T. E. Northup, and H. J. Kimble, Nature 436, 87 (2005).Comment: 10 pages, 6 figure
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