753 research outputs found
Turbulent Combustion of Polydisperse Evaporating Sprays with Droplet Crossing: Eulerian Modeling and Validation in the Infinite Knudsen Limit
The accurate simulation of the dynamics of polydisperse evaporating sprays in unsteady gaseous flows with large-scale vortical structures is both a crucial issue for industrial applications and a challenge for modeling and scientific computing. The difficulties encountered by the usual Lagrangian approaches make the use of Eulerian models attractive, aiming at a lower cost and an easier coupling with the carrier gaseous phase. Among these models, the multi-fluid model allows for a detailed description of the polydispersity and size-velocity correlations for droplets of various sizes. The purpose of the present study is twofold. First, we extend the multi-fluid model in order to cope with crossing droplet trajectories by using the quadrature method of moments in velocity phase space conditioned by size. We identify the numerical difficulties and provide dedicated numerical schemes in order to preserve the velocity moment space. Second, we conduct a comparison study and demonstrate the capability of such an approach to capture the dynamics of an evaporating polydisperse spray in a 2-D free jet configuration. We evaluate the accuracy and computational cost of Eulerian models and related discretization schemes vs. Lagrangian solvers and show that, even for finite Stokes number, the standard Eulerian multi-fluid model can be accurate at reasonable cost
Патопсихологические особенности и закономерности развития органических психических расстройств при болезни Паркинсона
Проанализированы особенности эмоционально−потребностной сферы, выраженность личностных особенностей, типы отношения к болезни у пациентов с болезнью Паркинсона (БП) и психическими расстройствами. Выявлены патопсихологические факторы формирования органического депрессивного расстройства (F06.36), органического тревожного расстройства (F06.4), органического эмоционально−лабильного расстройства (F06.6), описаны механизмы их патогенеза. Относительно деменции (F02.3) у больных БП единого патопсихологического механизма ее формирования не обнаружено, основная роль в ее патогенезе принадлежит органическому поражению головного мозга.Проаналізовано особливості емоційно−потребової сфери, виразність особистісних особливостей, типи ставлення до хвороби у пацієнтів із хворобою Паркінсона (ХП) та психічними розладами. Виявлено патопсихологічні фактори формування органічного депресивного розладу (F06.36), органічного тривожного розладу (F06.4), органічного емоційно−лабільного розладу (F06.6), описано механізми їх патогенезу. Щодо деменції (F02.3) у хворих на ХП єдиного патопсихологічного механізму її формування не виявлено, основна роль в її патогенезі належить органічному ураженню головного мозку.The peculiarities of emotion−need sphere, degree of personality peculiarities, types of attitude to the disease were analyzed in patients with Parkinson's disease (PD) and mental disorders. Pathopsychological factors of forming organic depressive disorder (F06.36), organic anxiety disorder (F06.4), organic emotional−labile disorder (F06.6) were revealed. The mechanisms of their pathogenesis were described. As for dementia (F02.3), uniform pathopsychological mechanism of its formation was not revealed in patients with PD. Main role in its pathogenesis is played by organic brain lesions
Vezatin is essential for dendritic spine morphogenesis and functional synaptic maturation.
International audienceVezatin is an integral membrane protein associated with cell-cell adhesion complex and actin cytoskeleton. It is expressed in the developing and mature mammalian brain, but its neuronal function is unknown. Here, we show that Vezatin localizes in spines in mature mouse hippocampal neurons and codistributes with PSD95, a major scaffolding protein of the excitatory postsynaptic density. Forebrain-specific conditional ablation of Vezatin induced anxiety-like behavior and impaired cued fear-conditioning memory response. Vezatin knock-down in cultured hippocampal neurons and Vezatin conditional knock-out in mice led to a significantly increased proportion of stubby spines and a reduced proportion of mature dendritic spines. PSD95 remained tethered to presynaptic terminals in Vezatin-deficient hippocampal neurons, suggesting that the reduced expression of Vezatin does not compromise the maintenance of synaptic connections. Accordingly, neither the amplitude nor the frequency of miniature EPSCs was affected in Vezatin-deficient hippocampal neurons. However, the AMPA/NMDA ratio of evoked EPSCs was reduced, suggesting impaired functional maturation of excitatory synapses. These results suggest a role of Vezatin in dendritic spine morphogenesis and functional synaptic maturation
Quantitative spray analysis of diesel fuel and its emulsions using digital image processing
In the present work, an experimental investigation of spray atomization of different liquids has been carried out. An air-assist atomizer operating at low injection pressures valued (4 and 6 bar) has been used to generate sprays of (diesel fuel, 5, 10, and 15% water-emulsified-diesel), respectively. A Photron-SA4 high speed camera has been used for spray imaging at 2000 fps. 20 time intervals (from 5 to 100 ms with 5 ms time difference) are selected for analysis and comparison. Spray macroscopic characteristics (spray penetration, dispersion, cone angle, axial and dispersion velocities) have been extracted by a proposed technique based on image processing using Matlab, where the maximum and minimum (horizontal and vertical) boundaries of the spray are detected, from which the macroscopic spray characteristics are evaluated. The maximum error of this technique is (1.5% for diesel spray) and a little bit higher for its emulsions
D-SERINE CONTRIBUTES TO β-AMYLOID-DEPENDENT PATHOPHYSIOLOGYIN ALZHEIMER’S DISEASE
International audienceB fEPSP/PFV ra>o 0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 WT 5xFAD 5xFAD/SR-/-+ D-s e ri n e + D-s e ri n e + D-s e ri n e Key regulators of the structural and funcFonal brain plasFcity, the N-methyl-D-aspartate subtype of glutamate receptors (NMDARs) requires the binding of the co-agonist D-serine to be acFvated. In Alzheimer's disease (AD), soluble oligomers of the beta-amyloid pepFde (Aßo) affect NMDARs possibly through mechanisms involving changes in D-serine levels since Aßo sFmulate in vitro the producFon of the co-agonist. In this study, we asked whether D-serine contributes in vivo to morpho-funcFonal NMDAR-related deregulaFons mediated by Aßo. Behavioral analysis combined to electrophysiological recordings at CA1/CA3 hippocampal synapses have been thus conducted in the 5xFAD transgenic mice model of amyloïdogenesis displaying marked increase in Aßo rates and compared to 5xFAD animals in which the homozygous gene of the serine racemase (SR) that synthesizes D-serine, has been jointly invalidated. Our results therefore show that deleFon of serine racemase prevents memory-related behavioral deficits observed in mice with prominent features of amyloidogenesis as well as impairment of NMDAR-dependent funcFonal plasFcity, suggesFng a significant contribuFon of D-serine in NMDAR-dependent β-amyloid-related pathophysiology of Alzheimer's disease. EXPERIMENTAL PROCEDURES 1) Behavioral analysis: 8-min spontaneous alternaFon test was performed in a Y maze apparatus to assess working memory performances in 10-12 months of aged mice. Successive entry of the three arms of the maze was considered as an alternaFon. The percentage of alternaFon was calculated as follows: number of alternaFons / (total number of arms visited-2) x 100. 2) Electrophysiology: Hippocampal slices (400 µm thickness) were cut from two groups of WT, 5xFAD/SR +/+ and 5xFAD/SR-/-mice aged 3-4 or 10-12 months. Field excitatory postsynapFc potenFals (fEPSPs) and presynapFc fiber volley (PFV) were extracellularly recorded in CA1 stratum radiatum aner electrical sFmulaFon of Schaffer collaterals. Input/output curves of the fEPSP/PFV raFo of isolated NMDAr-mediated fEPSPs were constructed in a low magnesium medium supplemented with the non-NMDAr antagonist NBQX (10µM) before and 15 min aner addiFon of D-serine (100 µM). High frequency (HFS)-induced long-term potenFaFon (LTP) was studied in control medium aner tetanic sFmulaFon consisFng in one train at 100 Hz delivered for 1 sec. TesFng sFmulaFon was then resumed for 60 min aner HFS. 3) Semi-quanFtaFve immunoblopng analysis: Hippocampal Fssue was homogenized in protein lysis buffer. The membranes were probed with anFbodiesaginst GluN1 (1:750
New 3-hit model of schizophrenia: behavioral and electrophysiological investigations
International audienc
PADRÃO DE ATIVIDADE DIURNA DO CAVALO-MARINHO Hippocampus reidi NO ESTADO DO RIO DE JANEIRO
The objective of this study was to characterize the diurnal patterns ofactivity of Hippocampus reidi and determine its behavioral repertoire during this period of activity. Behavioral observations were made between 07:00h and 19:30h at five different sites in Rio de Janeiro state, during whichall recorded behaviors of each observed individual were quantified over one hour. A total of 90h of observation were made, 30h for females, 30h for pregnant males and 30h for non-pregnant males. The results suggest thatseahorses are very active during the day. Swimming and foraging were the most frequent behaviors observed. Non-pregnant males presented a similar behavioral repertoire to females, while pregnant males were lessactive during the day.El presente estudio tuvo como objetivo caracterizar el patrón de actividaddiurno de la especie de caballito de mar Hippocampus reidi, si la esta presenta picos de actividad y cuáles son los comportamientos relacionados a la actividad diurna. Fueron realizadas observaciones del comportamiento entre las 07:00h y las 19:30h en cinco playas del estado de Rio de Janeiro, observando los comportamientos presentes y la duración de cada comportamiento a lo largo de una hora para cada individuo observado. Fueron realizadas un total de 90h, siendo 30 para hembras, 30 para machos incubando y 30 para machos no incubando. Los caballitos de mar presentaron un comportamiento bastante activo a lo largo de todo o período de observación, siendo los comportamientos de natación y alimentación los más frecuentes. Los machos que no estaban en estado de incubación mostraron un comportamiento activo similar al de las hembras. Por otro lado los machos en estado de incubación se mostraron poco activos a lo largo de todo el día.O presente estudo teve como objetivo caracterizar o padrão de atividade durante o período diurno da espécie de cavalo-marinho Hippocampus reidi, se a mesma apresenta picos de atividade e quais são os comportamentos relacionados a esta atividade diurna. Foram realizadas observações comportamentais de 07:00h às 19:30h em cinco praias do estado do Rio de Janeiro, observando os comportamentos presentes e a duração de cada comportamento ao longo de uma hora para cada indivíduo observado. Foi realizado um total de 90h, sendo 30 para fêmeas, 30 para machos incubando e 30 para machos não incubando. Os cavalos-marinhos apresentaram comportamento bastante ativo ao longo de todo o período de observação, sendo os comportamentos de natação e alimentação os mais freqüentes. Os machos que não estavam em estado de incubação mostraram comportamento ativo similar ao das fêmeas. Por outro lado os machos em estado de incubação mostraram-se pouco ativos ao longo de todo o dia
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