Dynamics of a driven probe molecule in a liquid monolayer

We study dynamics of a probe molecule, driven by an external constant force in a liquid monolayer on top of solid surface. In terms of a microscopic, mean-field-type approach, we calculate the terminal velocity of the probe molecule. This allows us to establish the analog of the Stokes formula, in which the friction coefficient is interpreted in terms of the microscopic parameters characterizing the system. We also determine the distribution of the monolayer particles as seen from the stationary moving probe molecule and estimate the self-diffusion coefficient for diffusion in a liquid monolayer.Comment: Latex, 7 pages, 1 figur

Selenoprotein gene expression in an intestinal cell line during selenium depletion: a macroarray approach indicates effects on SelW and glutathione peroxidise 1.

The micronutrient selenium (Se) is incoprprated into a renage of selenoproteins involved in numerous biochemical processes within the body

Estimativas populacionais de Dendrobates tinctorius (Anura: Dendrobatidae) em três áreas da Guiana Francesa e primeiro relato de quitridiomicose.

A região Neotropical abriga o maior número de espécies de anuros da Terra e é também uma das regiões em que os anfíbios estão mais ameaçados. No entanto, poucos dados estão atualmente disponíveis para avaliar a situação daspopulações de anfíbios neotropicais. Estudamos três populações de Dendrobates tinctorius na Guiana Francesa (Tresor, Favard e Nouragues) usando o modelo de Captura-Marcação-Recaptura (CMR) para a realização de estimativas robustas da densidade da espécie nesses três locais. Além disso, avaliamos a prevalência do fungo patogênico Batrachochytrium dendrobatidis (Bd) em duaspopulações (Favard and Nouragues). O uso do modelo CMR revelou uma densidade de 4,67 indivíduos/100 m² para Tresor, 8,43 indivíduos/100 m² para Favard e 4,28 indivíduos/100 m² para Nouragues, fornecendo estimativas das densidades populacionais de D. tinctorius na Guiana Francesa com as quais estimativas populacionais futuras poderão ser comparadas. Constatamos que 25 ocasiões de encontro podem ser suficientes para estimativas de uma população estável se as capturas forem concentradas no tempo. Bd foi detectado em ambas as áreas (Favard 7/152, Nouragues 3/18). Propomos, portanto, o início de um acompanhamento de longa-duração dessa espécie em vários locais (dentro e fora de áreas protegidas) da Guiana Francesa, combinando estudos de CMR com ocasiões de encontros concentrados em um curto período de tempo e o monitoramento de Bd.The Neotropics shelter the highest number of frog species on Earth and is also one of the regions where anurans aremost threatened. Nonetheless, few data are available to assess the population status of Neotropical anurans. We studied three populations (Tresor, Favard, and Nouragues) of the poison frog, Dendrobates tinctorius, in French Guiana and used Capture-Mark-Recapture (CMR) to make robust estimations of the species’ density at these three sites. In addition, we assessed the prevalence of the pathogen fungal Batrachochytrium dendrobatidis (Bd) in two populations (Favard and Nouragues). Based on the CMR protocol, the densities of frogs was 8.43 individuals/100 m² at Favard, 4.28 individuals/100 m² at Nouragues and from 2.30 to 4.67 individuals/100 m² at Tresor (depending on the CMR model used); these data provide a baseline for population densities of D. tinctorius in French Guiana, against which future population estimates can be compared. We found that 25 encounter events may be sufficient for stable population estimates, if the captures are concentrated in time. Bd was detected at both sites (Favard 7/152; Nouragues 3/18)

Molecular Weight Dependence of Spreading Rates of Ultrathin Polymeric Films

We study experimentally the molecular weight $M$ dependence of spreading rates of molecularly thin precursor films, growing at the bottom of droplets of polymer liquids. In accord with previous observations, we find that the radial extension R(t) of the film grows with time as R(t) = (D_{exp} t)^{1/2}. Our data substantiate the M-dependence of D_{exp}; we show that it follows D_{exp} \sim M^{-\gamma}, where the exponent \gamma is dependent on the chemical composition of the solid surface, determining its frictional properties with respect to the molecular transport. In the specific case of hydrophilic substrates, the frictional properties can be modified by the change of the relative humidity (RH). We find that \gamma \approx 1 at low RH and tends to zero when RH gets progressively increased. We propose simple theoretical arguments which explain the observed behavior in the limits of low and high RH.Comment: 4 pages, 2 figures, to appear in PR

Multiple Description Coding for Voice over IP using Sinusoidal Speech Coding

ABSTRACT CELP coders, such as G.729, are often used in VoIP systems as they offer good speech quality in the absence of packet losses. However, their reliance on long-term prediction causes propagation of errors across speech frames, and therefore makes CELP coders more sensitive to packet losses. Sinusoidal coders on the other hand do not rely on long-term prediction, and may be a good alternative for VoIP due to their higher resilience to packet losses. In this paper a comparison is made between CELP and sinusoidal coders in a VoIP application. A packetisation scheme based on Multiple Description Coding (MDC) applied to the sinusoidal coder is presented. The results show that under typical VoIP operating conditions, the sinusoidal coder based systems can outperform CELP based systems at equal bit rate, especially for high packet loss rates

Conceptualisations of landscape differ across European languages

Acknowledgments: Thanks to Peter Sercombe for assistance with English data collection and to Maximilian Hartmann for assisting in the creation of the network visualisations. Funding: This work was funded by a Bank of Sweden Tercentenary Foundation Jubilee Initiative Grant (https://www.rj.se/en), grant ref. NHS14-1665:1. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Autofluorescence endoscopic spectro-imaging and 2D-cartography for in situ localisation and diagnosis of cancerous lesions

Early diagnosis is the most efficient way to struggle against cancer. Among all the existing techniques, optical methods (photodiagnosis from NUV to NIR) show important characteristics required by the physicians : high sensitivity, non-ionising radiations and non-traumatic measurements. They are particularly well suited to the detection of cancers in hollow organs, that are usually superficial and hardly visible with classical endoscopy. This paper describes a methodological approach based on the use of tissue autofluorescence, applicable in clinical endoscopy, and leading to the definition of diagnosis indicators from the spectral parameters. Following a state-of-the-art on autofluorescence spectroscopic (LIFS) and endoscopic imaging methods, we present the efficiency of fibered LIFS in terms of sensitivity and specificity for the diagnosis of esophagus cancerous lesions (clinical study over 25 patients). We then present the technological characteristics of an autofluorescence endoscopic imaging prototype developed in our labs as well as its calibration. A second part is devoted to endoscopic image registration and mosaicing and to optics aberration correction in perspective of the automatic construction of a panoramic image (cartography) of the organ’s explored areas. Finally, exploiting the fluorescence data provided by the imager, the feasibility of the superimposition of spatial and spectral information is validated with a phantom.Le diagnostic précoce est le moyen le plus efficace de lutte contre le cancer. Parmi toutes les techniques possibles, les méthodes optiques (photodiagnostic du proche UV au proche IR) présentent des caractéristiques importantes recherchées par les médecins : grande sensibilité, radiations non ionisantes et mesures atraumatiques. Elles sont particulièrement bien adaptées à la détection des cancers des organes creux, par nature superficiels et difficilement décelables en endoscopie classique. Cet article décrit une approche méthodologique fondée sur l’exploitation de l’autofluorescence tissulaire, applicable en endoscopie clinique, et conduisant à l’élaboration d’indicateurs diagnostiques issus des paramètres spectraux. Après un état de l’art sur les méthodes spectroscopiques (LIFS) et d’imagerie endoscopique d’autofluorescence, nous montrons l’efficacité de la LIFS fibrée en terme de sensibilité et de spécificité pour le diagnostic de lésions cancéreuses de l’oesophage (étude clinique sur 25 patients). Nous présentons ensuite les caractéristiques technologiques et le calibrage du prototype d’imageur endoscopique d’autofluorescence développé. Une seconde partie traite du pré-traitement, du recalage et du mosaïquage des images endoscopiques appliqués à la construction automatique d’une image panoramique (cartographie) à partir de séquences vidéos des zones explorées de l’organe. Finalement, en exploitant les informations de fluorescence fournies par l’imageur, la faisabilité d’une superposition des informations spatiale et spectrale est validée sur fantôme

Theoretical and experimental activities on opacities for a good interpretation of seismic stellar probes

Opacity calculations are basic ingredients of stellar modelling. They play a crucial role in the interpretation of acoustic modes detected by SoHO, COROT and KEPLER. In this review we present our activities on both theoretical and experimental sides. We show new calculations of opacity spectra and comparisons between eight groups who produce opacity spectra calculations in the domain where experiments are scheduled. Real differences are noticed with real astrophysical consequences when one extends helioseismology to cluster studies of different compositions. Two cases are considered presently: (1) the solar radiative zone and (2) the beta Cephei envelops. We describe how our experiments are performed and new preliminary results on nickel obtained in the campaign 2010 at LULI 2000 at Polytechnique.Comment: 6 pages, 4 figures, invited talk at SOHO2