Crack path instabilities in DCDC experiments in the low speed regime

We studied the low speed fracture regime (0.1mm/s - 1nm/s) in different glassy materials (soda-lime glass, glass-ceramics) with variable but controlled length scale of heterogeneity. The chosen mechanical system enabled us to work in pure mode I (tensile) and at a fixed load on DCDC (double cleavage drilled compression) specimen. The internal residual stresses of studied samples were carefully relaxed by appropriate thermal treatment. By means of optical and atomic force (AFM) microscopy techniques fracture surfaces have been examined. We have shown for the first time that the crack front line underwent an out-of-plane oscillating behavior as a result of a reproducible sequence of instabilities. The wavelength of such a phenomenon is in the micrometer range and its amplitude in the nanometer range. These features were observed for different glassy materials providing that a typical length scale characterizing internal heterogeneities was lower than a threshold limit estimated to few nanometers. This effect is the first clear experimental evidence of crack path instabilities in the low speed regime in a uniaxial loading experiment. This phenomenon has been interpreted by referring to the stability criterion for a straight crack propagation as presented by Adda-Bedia et al. (Phys. Rev. Letters (1996) 76} p1497).Comment: 16 pages, 10 figures, submitted to Journal of Non-Crystalline Solid

P53 germline mutations in childhood cancers and cancer risk for carrier individuals

The family history of cancer in children treated for a solid malignant tumour in the Paediatric Oncology Department at Institute Gustave-Roussy, has been investigated. In order to determine the role of germline p53 mutations in genetic predisposition to childhood cancer, germline p53 mutations were sought in individuals with at least one relative (first- or second-degree relative or first cousin) affected by any cancer before 46 years of age, or affected by multiple cancers. Screening for germline p53 mutation was possible in 268 index cases among individuals fulfilling selection criteria. Seventeen (6.3%) mutations were identified, of which 13 were inherited and four were de novo. Using maximum likelihood methods that incorporate retrospective family data and correct for ascertainment bias, the lifetime risk of cancer for mutation carriers was estimated to be 73% for males and nearly 100% for females with a high risk of breast cancer accounting for the difference. The risk of cancer associated with such mutations is very high and no evidence of low penetrance mutation was found. These mutations are frequently inherited but de novo mutations are not rare. © 2000 Cancer Research Campaig

Thermal fracture as a framework for quasi-static crack propagation

We address analytically and numerically the problem of crack path prediction in the model system of a crack propagating under thermal loading. We show that one can explain the instability from a straight to a wavy crack propagation by using only the principle of local symmetry and the Griffith criterion. We then argue that the calculations of the stress intensity factors can be combined with the standard crack propagation criteria to obtain the evolution equation for the crack tip within any loading configuration. The theoretical results of the thermal crack problem agree with the numerical simulations we performed using a phase field model. Moreover, it turns out that the phase-field model allows to clarify the nature of the transition between straight and oscillatory cracks which is shown to be supercritical.Comment: 19 pages, 8 figure

Non-conventional sources of peptides presented by MHC class I

Effectiveness of immune surveillance of intracellular viruses and bacteria depends upon a functioning antigen presentation pathway that allows infected cells to reveal the presence of an intracellular pathogen. The antigen presentation pathway uses virtually all endogenous polypeptides as a source to produce antigenic peptides that are eventually chaperoned to the cell surface by MHC class I molecules. Intriguingly, MHC I molecules present peptides encoded not only in the primary open reading frames but also those encoded in alternate reading frames. Here, we review recent studies on the generation of cryptic pMHC I. We focus on the immunological significance of cryptic pMHC I, and the novel translational mechanisms that allow production of these antigenic peptides from unconventional sources

Main inherited neurodegenerative cerebellar ataxias, how to recognize them using magnetic resonance imaging?

International audienc

Where did the first divorced people live in Paris and its suburbs?

International audienceFollowing the law of 1884 that re-authorised divorce in France, divorce was more frequent in the large cities before spreading to other urban areas and then to rural ones. Divorce rates were especially high in the Seine département from 1884 to the eve of the First World War. In this region, divorced people lived more frequently in Paris than in the suburbs. More precisely, they resided more often on the Right Bank of the Seine in Paris proper (intra-muros) and, as an extension of this area, in the suburban cities to the west and, to the east, around the Bois de Vincennes. A comparison of the share of divorced men and women to the economic, demographic and cultural characteristics of the 20 Paris arrondissements and 74 suburban municipalities in the Seine département shows that a portion of the spatial distribution can be explained by the occupational structures of the area. Divorced people seldom lived in the most rural areas. This urban/rural divide can be explained by two main factors that can be complementary: the economic possibility to divorce – and here we will add the economic possibility for women to leave live alone after a divorce – and the social and cultural acceptance of divorc

Exenatide decreases liver fat content and epicardial adipose tissue in patients with obesity and type 2 diabetes: a prospective randomized clinical trial using magnetic resonance imaging and spectroscopy.

Aim To conduct a prospective randomized trial to investigate the effect of glucagon-like peptide-1 (GLP-1) analogues on ectopic fat stores. Methods A total of 44 obese subjects with type 2 diabetes uncontrolled on oral antidiabetic drugs were randomly assigned to receive exenatide or reference treatment according to French guidelines. Epicardial adipose tissue (EAT), myocardial triglyceride content (MTGC), hepatic triglyceride content (HTGC) and pancreatic triglyceride content (PTGC) were assessed 45min after a standardized meal with 3T magnetic resonance imaging and proton magnetic resonance spectroscopy before and after 26weeks of treatment. Results The study population had a mean glycated haemoglobin (HbA1c) level of 7.5±0.2% and a mean body mass index of 36.1±1.1 kg/m2. Ninety five percent had hepatic steatosis at baseline (HTGC≥5.6%). Exenatide and reference treatment led to a similar improvement in HbA1c (−0.7±0.3% vs. −0.7±0.4%; p=0.29), whereas significant weight loss was observed only in the exenatide group (−5.5±1.2 kg vs. −0.2±0.8 kg; p=0.001 for the difference between groups). Exenatide induced a significant reduction in EAT (−8.8±2.1%) and HTGC (−23.8±9.5%), compared with the reference treatment (EAT: −1.2±1.6%, p=0.003; HTGC: +12.5±9.6%, p=0.007). No significant difference was observed in other ectopic fat stores, PTGC or MTGC. In the group treated with exenatide, reductions in liver fat and EAT were not associated with homeostatic model assessment of insulin resistance index, adiponectin, HbA1c or fructosamin change, but were significantly related to weight loss (r=0.47, p=0.03, and r=0.50, p=0.018, respectively). Conclusion Our data indicate that exenatide is an effective treatment to reduce liver fat content and epicardial fat in obese patients with type 2 diabetes, and these effects are mainly weight loss dependent.</p