94 results match your criteria: "University and CNRS[Affiliation]"

We explore several random phase approximation (RPA) correlation energy variants within the adiabatic-connection fluctuation-dissipation theorem approach. These variants differ in the way the exchange interactions are treated. One of these variants, named dRPA-II, is original to this work and closely resembles the second-order screened exchange (SOSEX) method.

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The aurophilic interaction is examined in three model systems Au2((3)Σg(+)), (AuH)2, and (HAuPH3)2 which contain interactions of pairs of the Au centers in the oxidation state (I). Several methods are employed ranging from wave function theory-based (WFT) approaches to symmetry-adapted perturbation theory (SAPT) and range-separated hybrid (RSH) density functional theory (DFT) methods. The most promising and accurate approach consists of a combination of the DFT and WFT approaches in the RSH framework.

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Dispersion interaction in hydrogen-chain models.

J Chem Phys

March 2011

CRM2, Institut Jean Barriol, Nancy University and CNRS, 54506 Vandoeuvre-lès-Nancy, France.

We have investigated the dispersion interaction in hydrogen chain models via density functional theory-based symmetry-adapted perturbation theory using the asymptotically corrected PBE0 energy functional. The quasimetallic and the insulating prototype systems were chosen to be hydrogen chains with equally and alternately spaced H(2) units, respectively. The dependence of the dispersion energy on the chain length for quasimetallic and insulating cases has been determined for two chains arranged either in pointing or in parallel geometries.

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Location and identity memory of saccade targets.

Vision Res

February 2011

Laboratorie Psychologie de la Perception, Paris Descartes University and CNRS, 45 rue des Saints Pères, 75006 Paris, France.

While the memory of objects' identity and of their spatiotopic location may sustain transsaccadic spatial constancy, the memory of their retinotopic location may hamper it. Is it then true that saccades perturb retinotopic but not spatiotopic memory? We address this issue by assessing localization performances of the last and of the penultimate saccade target in a series of 2-6 saccades. Upon fixation, nine letter-pairs, eight black and one white, were displayed at 3° eccentricity around fixation within a 20° × 20° grey frame, and subjects were instructed to saccade to the white letter-pair; the cycle was then repeated.

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TNF is essential to control Mycobacterium tuberculosis infection and cannot be replaced by other proinflammatory cytokines. Overproduction of TNF may cause immunopathology, while defective TNF production results in uncontrolled infection. The critical role of TNF in the control of tuberculosis has been illustrated recently by primary and reactivation of latent infection in some patients under pharmacological anti-TNF therapy for rheumatoid arthritis or Crohn's disease.

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The metajudgment of motor responses refers to our ability to evaluate the accuracy of our own actions. Can humans metajudge the duration of their Reaction Times (RTs) to a light-flash and the accuracy of their reproduction of a reference time interval bounded by two light flashes (Anticipatory Response Time, ART)? A series of four distinct experiments shows that RT_Meta and ART_Metajudgments are possible but with accuracies about x2.4 and x3 poorer than the corresponding RT and ART ones.

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Adjuvant activity on murine and human macrophages.

Methods Mol Biol

April 2010

Molecular Immunology and Embryology, University and CNRS, Orleans, France.

Activation of cells of the innate immunity such as macrophages and dendritic cells is critical to mount an adaptive immune response. Recent advances on the understanding of innate immune receptors such as the Toll-like receptors (TLR) and NOD-like receptors (NLR) and the demonstration that microbial products activate specific receptors. This discovery represented a major advance and provided tools to test novel adjuvants in vitro to investigate activation on innate immune cells.

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Article Synopsis
  • Mycobacterium tuberculosis uses special proteins and sugars to change how our immune system works.
  • A specific sugar called PIM(6) or PIM(2) can reduce inflammation by stopping certain signals in our body from being released.
  • This sugar shows promise for helping treat inflammation-related issues and could be used to develop new medicine to help with immune responses.
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Extracellular adenosine triphosphate is able to modulate pancreatic beta-cell function, acting on P2 purinergic ionotropic (P2X) and metabotropic (P2Y) receptors. Physiologically, ATP entrains beta-cells into a common rhythm by coordinating Ca(2+) oscillations; it plays a central role in insulin secretion pulsatility. ATP also triggers a positive feedback signal amplifying glucose-induced insulin release, which argues for a potential pharmacological application.

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The basic reciprocity between individual parts and collective organization constitutes a key scientific question spanning the biological and social sciences. Such reciprocity is accompanied by the absence of direct linkages between levels of description giving rise to what is often referred to as the aggregation or nonequivalence problem between levels of analysis. This issue is encountered both in neuroscience and economics.

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Toll like receptor - potential drug targets in infectious disease.

Infect Disord Drug Targets

December 2008

Molecular Immunology and Embryology, University and CNRS, Orleans, France.

Toll like receptors (TLR) play a critical role in the recognition and response of pathogens by the innate immune system. Pathogen engagement of the TLR-MyD88 pathway favours the development of a protective Th1-biased T cell response. Interruption of TLR recognition or signalling has profound effects on innate immunity.

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Previous studies have shown that a saccade is coded in a specific reference frame according to its goal: to aim for a new object or to explore an object which has already been fixated. In a two saccade sequence, the second saccade aiming for a new object is programmed in a retinocentric reference frame in which the spatial location of the second object is stored in spatial memory before the first saccade and updated after its execution. The second saccade exploring the same object is coded in an oculocentric reference frame in which object size is directly transformed into a fixed motor vector, encoded in motor memory before the first saccade and simply applied after its execution.

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Studying cognitive brain functions by functional magnetic resonance imaging (fMRI) requires appropriate stimulation devices that do not interfere with the magnetic fields. Since the emergence of fMRI in the 90s, a number of stimulation devices have been developed for the visual and auditory modalities. Only few devices, however, have been developed for the somesthesic modality.

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In the antisaccade task, subjects must execute an eye movement away from a visual target. Correctly executing an antisaccade requires inhibiting a prosaccade toward the visual target and programming a movement to the opposite side. This movement could be based on the inversion of the visual vector, corresponding to the distance between the fixation point and the visual target, or the motor vector of the unwanted prosaccade.

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Purpose: When saccade amplitude is systematically inadequate relative to the desired target position, the saccadic system adaptively modifies the amplitude of subsequent saccades so as to recover precise targeting capabilities. The effect of saccadic adaptation on saccade metrics (amplitude, direction) is well documented, but the effect on dynamics (velocity, duration, acceleration, deceleration) remains to be fully elucidated.

Methods: The dynamics of adapted saccades were compared with that of baseline saccades of similar amplitudes.

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Motor space structures perceptual space: evidence from human saccadic adaptation.

Brain Res

October 2007

Laboratoire de Psychologie et Neurosciences Cognitives, Paris Descartes University and CNRS, FRE 2987, 71 Avenue E Vaillant, 92 774, Boulogne-Billancourt, France.

Saccadic adaptation is the progressive correction of systematic saccade targeting errors. When a saccade to a particular target is adapted, saccades within a spatial window around the target, the adaptation field, are affected as a function of their distance from the adapted target. Furthermore, previous studies suggest that saccadic adaptation might modify the perceptual localization of objects in space.

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Mycobacterium tuberculosis lipomannans (LMs) modulate the host innate immune response. The total fraction of Mycobacterium bovis BCG LM was shown both to induce macrophage activation and pro-inflammatory cytokines through Toll-like receptor 2 (TLR2) and to inhibit pro-inflammatory cytokine production by lipopolysaccharide (LPS)-activated macrophages through a TLR2-independent pathway. The pro-inflammatory activity was attributed to tri- and tetra-acylated forms of BCG LM but not the mono- and di-acylated ones.

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Purinergic P2Y-receptor agonists amplify glucose-induced insulin secretion from pancreatic beta-cells, thus offering new opportunities for the treatment of type 2 diabetes. However, little is known about which subtypes of purinergic P2Y receptors are expressed in these cells. The INS-1 beta-cell line is used as a model of pancreatic beta-cells, expressing most of their properties.

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