Optical determination and identification of organic shells around nanoparticles: application to silver nanoparticles

We present a simple method to prove the presence of an organic shell around silver nanoparticles. This method is based on the comparison between optical extinction measurements of isolated nanoparticles and Mie calculations predicting the expected wavelength of the Localized Surface Plasmon Resonance of the nanoparticles with and without the presence of an organic layer. This method was applied to silver nanoparticles which seemed to be well protected from oxidation. Further experimental characterization via Surface Enhanced Raman Spectroscopy (SERS) measurements allowed to identify this protective shell as ethylene glycol. Combining LSPR and SERS measurements could thus give proof of both presence and identification for other plasmonic nanoparticles surrounded by organic shells

Rumen fermentative activity in the goat and sheep

No Abstract

Oracle-based optimization applied to climate model calibration

In this paper, we show how oracle-based optimization can be effectively used for the calibration of an intermediate complexity climate model. In a fully developed example, we estimate the 12 principal parameters of the C-GOLDSTEIN climate model by using an oracle-based optimization tool, Proximal-ACCPM. The oracle is a procedure that finds, for each query point, a value for the goodness-of-fit function and an evaluation of its gradient. The difficulty in the model calibration problem stems from the need to undertake costly calculations for each simulation and also from the fact that the error function used to assess the goodness-of-fit is not convex. The method converges to a ‘best fit' estimate over 10 times faster than a comparable test using the ensemble Kalman filter. The approach is simple to implement and potentially useful in calibrating computationally demanding models based on temporal integration (simulation), for which functional derivative information is not readily availabl

The Ly<alpha> and Ly<beta> profiles in solar prominences and prominence fine structure

We present the first combined Ly and Ly profiles in solar prominences obtained by the SOHO/SUMER instrument and discuss their important spatial variability with respect to predictions from 1D and multithread models.Comment: Accepted in Solar Physics, 14 pages with 9 figures and 3 Table

Monte-Carlo simulations of the recombination dynamics in porous silicon

A simple lattice model describing the recombination dynamics in visible light emitting porous Silicon is presented. In the model, each occupied lattice site represents a Si crystal of nanometer size. The disordered structure of porous Silicon is modeled by modified random percolation networks in two and three dimensions. Both correlated (excitons) and uncorrelated electron-hole pairs have been studied. Radiative and non-radiative processes as well as hopping between nearest neighbor occupied sites are taken into account. By means of extensive Monte-Carlo simulations, we show that the recombination dynamics in porous Silicon is due to a dispersive diffusion of excitons in a disordered arrangement of interconnected Si quantum dots. The simulated luminescence decay for the excitons shows a stretched exponential lineshape while for uncorrelated electron-hole pairs a power law decay is suggested. Our results successfully account for the recombination dynamics recently observed in the experiments. The present model is a prototype for a larger class of models describing diffusion of particles in a complex disordered system.Comment: 33 pages, RevTeX, 19 figures available on request to [email protected]

Measuring latency distribution of transcallosal fibers using transcranial magnetic stimulation

Background: Neuroimaging technology is being developed to enable non-invasive mapping of the latency distribution of cortical projection pathways in white matter, and correlative clinical neurophysiological techniques would be valuable for mutual verification. Interhemispheric interaction through the corpus callosum can be measured with interhemispheric facilitation and inhibition using transcranial magnetic stimulation. Objective: To develop a method for determining the latency distribution of the transcallosal fibers with transcranial magnetic stimulation. Methods: We measured the precise time courses of interhemispheric facilitation and inhibition with a conditioning-test paired-pulse magnetic stimulation paradigm. The conditioning stimulus was applied to the right primary motor cortex and the test stimulus was applied to the left primary motor cortex. The interstimulus interval was set at 0.1 ms resolution. The proportions of transcallosal fibers with different conduction velocities were calculated by measuring the changes in magnitudes of interhemispheric facilitation and inhibition with interstimulus interval. Results: Both interhemispheric facilitation and inhibition increased with increment in interstimulus interval. The magnitude of interhemispheric facilitation was correlated with that of interhemispheric inhibition. The latency distribution of transcallosal fibers measured with interhemispheric facilitation was also correlated with that measured with interhemispheric inhibition. Conclusions: The data can be interpreted as latency distribution of transcallosal fibers. Interhemispheric interaction measured with transcranial magnetic stimulation is a promising technique to determine the latency distribution of the transcallosal fibers. Similar techniques could be developed for other cortical pathways

Mise en place de la réglementation issue du décret du 11 décembre 2007 pour les digues maritimes des départements côtiers de la Manche et de Bretagne : état d'avancement, exemples marquants et perspectives

Colloque National Digues Maritimes et Fluviales de Protection contre les Submersions, Aix-en-Provence, FRA, 12-/06/2013 - 14/06/2013National audienceIn France, a national Decree signed on the 11th of December 2007 has significantly strengthened the safety obligations of the fluvial and coastal dike owners. In February 2010, the Xynthia catastrophic storm resulted in an increased awareness of those working on coastal dikes whether they are owners - such as local authorities, owners syndicate ... - or State control authorities.Furthermore, the importance of the French Flash Flood Prevention Program is growing and the first grants for the dike reinforcement have been issued.In this context, three specialized teams of the "regional directions for the environment " (ie the regional level of the French state administration responsible for the control of dike safety) working on the coastline of the English Channel (ie &amp;#8220;La Manche&amp;#8221;) present in this paper:&amp;#8226; a quick overlook of the inventory of coastal and river dikes;&amp;#8226; the feedback of the damage caused by the Xynthia storm in the French region of Calvados;&amp;#8226; the state-of-progress of the implementation of the regulations created by the 2007 Decree;&amp;#8226; Some examples of dike owners who partnered up in order to conduct assessment survey on their embankment system or to realize dikereinforcement work.Le décret de décembre 2007 a significativement renforcé les prescriptions de sécurité s'appliquant aux responsables des digues de protection contre les submersions d'origine fluviale et/ou maritime.La tempête catastrophique Xynthia de février 2010 a sensibilisé de nombreux acteurs agissant dans le domaine des digues de défense maritime - que ceux-ci relèvent de la Maîtrise d'Ouvrage (collectivités territoriales etassociations de défense contre la mer, pour l'essentiel) comme de la mission de Contrôle (DDTM puis DREAL) - pour une mise en oeuvre efficace et pragmatique de cette réglementation. Enfin, le Plan de lutte contre lesSubmersions rapides monte en puissance avec la labellisation des premiers dossiers de travaux de confortement.Dans ce contexte, plusieurs services de DREAL intervenant dans les départements côtiers de la Manche et de Bretagne s'associent pour proposer la présente communication qui vise à :&amp;#8226; dresser un rapide état des lieux du recensement et du classement des digues de front de mer ou de cours d'eau sous influence maritime sur ces côtes, dans lesquelles sont parfois englobés des éléments naturels tels que des cordons dunaires ;&amp;#8226; rapporter le retour d'expérience suite à la tempête Xynthia et les dégâts qu'elle a causés sur les digues du département du Calvados ;&amp;#8226; préciser l'avancement de la mise oeuvre du décret de 2007 ;&amp;#8226; présenter quelques exemples de mutualisation et de regroupement de la maîtrise d'ouvrage pour la conduite des études à l'échelle de systèmesd'endiguement ainsi que pour la réalisation de travaux

Assessing the consequences of gestational diabetes mellitus on offspring's cardiovascular health: MySweetHeart Cohort study protocol, Switzerland.

Gestational diabetes mellitus (GDM) is a state of glucose intolerance with onset during pregnancy. GDM carries prenatal and perinatal risks as well as long-term risks for the mother and her child. GDM may be involved in the foetal programming of long-term cardiovascular health. However, evidence is sparse and the effect of GDM on cardiovascular health is unknown. To address these issues, we will conduct MySweetHeart Cohort study. The objectives are to assess the effect of GDM on offspring's cardiovascular health early in life by using surrogate markers of cardiovascular disease and atherosclerosis. This is a cohort study of 100 offspring of women with GDM and 100 offspring of women without GDM. At inclusion, a baseline assessment of the mothers will be conducted through means of self-report questionnaires, a researcher-administrated interview, blood pressure and anthropometric measurements, and a maternal blood sampling. Between the 30th and 34th weeks of gestation, a foetal echography will be performed to assess the foetal cardiac structure and function, the fetomaternal circulation and the hepatic volume. At birth, maternal and neonatal characteristics will be assessed. An echocardiography will be performed to assess cardiac structure and function 2-7 days after birth; carotid intima-media thickness will be also measured to assess vascular structure. MySweetHeart Cohort is linked to MySweetHeart Trial (clinicaltrials.gov/ct2/show/NCT02890693), a randomised controlled trial assessing the effect of a multidimensional interdisciplinary lifestyle and psychosocial intervention to improve the cardiometabolic and mental health of women with GDM and their offspring. A long-term follow-up of children is planned. Ethical approval has been obtained through the state Human Research Ethics Committee of the Canton de Vaud (study number 2016-00745). We aim to disseminate the findings through regional, national and international conferences and through peer-reviewed journals. ClinicalTrials.gov (clinicaltrials.gov/ct2/show/NCT02872974)

Accurate spectroscopy of Sr atoms

We report the frequency measurement with an accuracy in the 100 kHz range of several optical transitions of atomic Sr : $^1S_0- ^3P_1$ at 689 nm, $^3P_1- ^3S_1$ at 688 nm and $^3P_0- ^3S_1$ at 679 nm. Measurements are performed with a frequency chain based on a femtosecond laser referenced to primary frequency standards. They allowed the indirect determination with a 70 kHz uncertainty of the frequency of the doubly forbidden 5s^2^1S_0- 5s5p^3P_0 transition of $^{87}$Sr at 698 nm and in a second step its direct observation. Frequency measurements are performed for $^{88}$Sr and $^{87}$Sr, allowing the determination of $^3P_0$, $^3P_1$ and $^3S_1$ isotope shifts, as well as the $^3S_1$ hyperfine constants.Comment: 12 pages, 16 figure

On the state dependency of fast feedback processes in (palaeo) climate sensitivity

Palaeo data have been frequently used to determine the equilibrium (Charney) climate sensitivity $S^a$, and - if slow feedback processes (e.g. land ice-albedo) are adequately taken into account - they indicate a similar range as estimates based on instrumental data and climate model results. Most studies implicitly assume the (fast) feedback processes to be independent of the background climate state, e.g., equally strong during warm and cold periods. Here we assess the dependency of the fast feedback processes on the background climate state using data of the last 800 kyr and a conceptual climate model for interpretation. Applying a new method to account for background state dependency, we find $S^a=0.61\pm0.06$ K(Wm$^{-2}$)$^{-1}$ using the latest LGM temperature reconstruction and significantly lower climate sensitivity during glacial climates. Due to uncertainties in reconstructing the LGM temperature anomaly, $S^a$ is estimated in the range $S^a=0.55-0.95$ K(Wm$^{-2}$)$^{-1}$.Comment: submitted to Geophysical Research Letter