Conservatoire national des arts et métiers

About: Conservatoire national des arts et métiers is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 3573 authors who have published 7127 publications receiving 141430 citations. The organization is also known as: CNAM & Conservatoire des arts et métiers.

Sum-frequency generation of 589 nm light with near-unit efficiency

Abstract: We report on a laser source at 589 nm based on sum-frequency generation of two infrared laser at 1064 nm and 1319 nm. Output power as high as 800 mW are achieved starting from 370 mW at 1319 nm and 770 mW at 1064 nm, corresponding to converting roughly 90% of the 1319 nm photons entering the cavity. The power and frequency stability of this source are ideally suited for cooling and trapping of sodium atoms.

Increased recurrence rates of hepatocellular carcinoma after DAA therapy in a hepatitis C‐infected Egyptian cohort: A comparative analysis

Abstract: In Egypt, hepatocellular carcinoma (HCC) is the most common form of cancer and direct-acting antivirals (DAA) are administered on a large scale to patients with chronic HCV infection to reduce the risk. In this unique setting, we aimed to determine the association of DAA exposure with early-phase HCC recurrence in patients with a history of HCV-related liver cancer. This was a prospective cohort study of an HCV-infected population from one Egyptian specialized HCC management centre starting from the time of successful HCC intervention. The incidence rates of HCC recurrence between DAA-exposed and nonexposed patients were compared, starting from date of HCC complete radiological response and censoring after 2 years. DAA exposure was treated as time varying. Two Poisson regressions models were used to control for potential differences in the exposed and nonexposed group; multivariable adjustment and balancing using inverse probability of treatment weighting (IPTW). We included 116 patients: 53 treated with DAAs and 63 not treated with DAAs. There was 37.7% and 25.4% recurrence in each group after a median of 16.0 and 23.0 months of follow-up, respectively. Poisson regression using IPTW demonstrated an association between DAAs and HCC recurrence with an incidence rate ratio of 3.83 (95% CI: 2.02-7.25), which was similar in the multivariable-adjusted model and various sensitivity analyses. These results add important evidence towards the possible role of DAAs in HCC recurrence and stress the need for further mechanistic studies and clinical trials to accurately confirm this role and to identify patient characteristics that may be associated with this event.

Fecal microbial community in preterm infants

Abstract: The gastrointestinal tract of a healthy fetus is sterile. In full term infants, the bacterial colonization of the gastrointestinal tract has been extensively studied if not entirely understood. During the birth process and rapidly thereafter, microbes from the mother and the surrounding environment colonize the gastrointestinal tract until a dense and complex bacterial community is established. In vaginally delivered neonates, bacteria appear in the stools during the first day of life, with usually Escherichia coli and Enterococcus spp., among the first, followed within the first 5 days by Bifidobacterium spp. Because, at this stage, the composition of the gut bacterial community is strongly influenced by the diet, a shift in the bacterial composition can be observed. By 10 days of age, most healthy full term neonates are colonized with a heterogeneous bacterial flora, with bifidobacteria dominant in breast-fed infants and a more diversified flora in formula-fed infants (1). A dynamic balance exists between the bacterial community, the host physiology, and the diet: all of them influence initial acquisition, subsequent development and eventual stability of the gut ecosystem (2). In contrast, in preterm infants, especially extremely low birth weight preterm infants (weighting less than 1,000 g at birth), bacterial colonization and its consequences on health have not been extensively studied. Many factors influence the biodiversity of the intestinal flora and may increase the risk of gastrointestinal disease such as necrotizing enterocolitis (NEC): immaturity of the main vital functions, the characteristics of the medical environment, from delivery to hospital discharge, the developmental stage of gastrointestinal and immune functions, the mode and environment of delivery, the feeding regimen, the kind of drug therapy (such as antibiotics, corticoids, etc.), or of other therapy (such as oxygenation). In adults, the human cecal flora differs quantitatively and qualitatively from the fecal flora. Facultative anaerobes represented 25% of total bacteria in the cecum versus 1% in the feces (3). So, the biodiversity of the bacterial community should be studied at these different levels of the gastrointestinal tract. For obvious reasons, most of the studies were performed on stool samples. In recent years, the use of ribosomal RNA, in particular, sequences of the 16S rRNA genes, has greatly facilitated the study of gastrointestinal tract ecology because it allows a culture-independent analysis of the fecal microbial community. In adult fecal samples, molecular tools have indicated that 60% to 80% of the total human microflora has not been cultivated (4). Techniques such as polymerase chain reaction, gene sequencing, in situ hybridization, and denaturing gradient gel electrophoresis are routinely used to study gut microbial ecology and have been recently reviewed by Suau (5). So far, only three studies inspected the microbial composition of premature infants using molecular methods (6–8). Thus, the aim of the present review is to describe the composition of fecal microbial community in preterm infants from the colonization of sterile gut, to present the different factors that contribute to its alterations, and to link the gut microflora to diseases such as NEC. This review is essentially based on data collected using traditional bacterial culture from fecal samples.

Sedimentary record of metal contamination in the Seine River during the last century

Abstract: The time evolution of heavy metal contamination in the Seine River catchment is documented through the analysis of sediment cores sampled at three different sites: in upstream Seine River where agricultural activity is predominant, in the Oise River (a tributary of the Seine River) characterized by intensive industrial activity, and downstream Seine River where various kinds of activities (agricultural, industrial and urban activities) are mixed. The chronology of the cores is obtained through 137 Cs and 210 Pb dating. Only cores with a clear dating are selected for the study. Concentrations of Pb, Cd, Cu, Zn, Cr, As, Sb and Hg are analyzed by neutron activation, inductively coupled plasma-atomic emission spectrometry, inductively coupled plasma-mass spectrometry and atomic absorption spectroscopy after sediment dissolution. The maximum of pollution is registered during the 1960–1970 decade in the Oise River site, and 10 years later in the downstream Seine River. The sites are compared, showing some specific signatures. The different occurrence of every metal at each site is discussed. The present level of pollution is lower in the Oise River, compared to that of the downstream site. The decrease of the metallic pollution is discussed in each site considering its origins and history, as well as recent French and EU environmental policy implementation.

An experiment of muon radiography at Mt Etna (Italy)

Abstract: Interactions of conduit geometry with gas–liquid flows control volcanic activity, implying that the evaluation of volcanic hazards requires quantitative understanding of the inner structure of the volcano. The more established geophysical imaging techniques suffer from inherent ambiguity, may require spatially dense measurements in active areas and may not provide sufficient spatial resolution in the uppermost part of the conduit system. It is thus desirable to develop new imaging techniques allowing a better spatial resolution of a volcano's upper feeding system, with reduced ambiguity and a low level of risk for operators. Muon particles can be utilized to image the internal density distribution of volcanic structures. The principle of muon radiography is essentially the same as X-ray radiography, except for substituting penetrating particles in place of photons. Muons are more attenuated by higher density parts inside the target and thus information about its inner structure are obtained from the differential muon absorption. We report on a muon-imaging experiment that was conducted at Mt Etna in 2010. The target structure was one of the summit craters of the volcano. This experiment was performed using a muon telescope suitably designed to withstand the harsh conditions in the summit zone of a high volcano. We found a marked difference between synthetic and observed attenuation of muons through the target. This discrepancy is likely due to the bias on the observed flux, arising from false muon tracks. They are caused by low-energy particles that, by chance, hit simultaneously the two matrixes of the telescope, leading to detection of a false positive. We separated the useful from the unwanted signal through a first-order model of the background noise. The resulting signal is compared with the corresponding synthetic flux. Eventually, we found regions of higher-and lower-than-expected muon flux, that are possibly related to inner features of the target crater.