726 research outputs found

    Fractoluminescence characterization of the energy dissipated during fast fracture of glass

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    Fractoluminescence experiments are performed on two kinds of silicate glasses. All the light spectra collected during dynamic fracture reveal a black body radiator behaviour, which is interpreted as a crack velocity-dependent temperature rise close to the crack tip. Crack velocities are estimated to be of the order of 1300 m.s−1^{-1} and fracture process zones are shown to extend over a few nanometers.Comment: Accepted for publication in Europhysics Letters; 5 pages; 4 figure

    The impact of multiple deployments on military spouses

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    This mixed method, exploratory, retrospective study explores the impact of multiple deployments on military spouses. Previous studies have focused on single deployments while looking at stress, coping styles and stages of deployment. This study is exploring the afore mentioned topics with the stipulation that the spouse has to have experienced at least two deployments. Eighty spouses from all branches of the military, except the Coast Guard, participated in this study. The spouses completed an online survey where they were asked multiple choice, scaling and open-ended questions comparing the first and second/subsequent deployments. The questions were designed to learn more about the stages of deployment, emotions felt during each stage of deployment, and coping strategies used during deployments. Findings of this study were consistent with earlier studies that focused on single deployments. Spouses reported that there was no change in the perception of the difficulty of deployments whether the spouse had deployed once or multiple times, spouses found the second or subsequent deployment as difficult as the first. Spouses reported that the stage of the actual deployment was the most difficult, and that the spouses felt stress through all stages of deployment. The spouses stated that keeping busy was the main coping strategy used to help them through the deployments. Finally, spouses stated that no matter how many deployments they had experienced, it doesn\u27t get easier

    Qualitative extension of the EC′ Zone Diagram to a molecular catalyst for a multi-electron, multi-substrate electrochemical reaction

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    Traverse the EC′ Zone Diagram with a molecular H 2 -evolving electrocatalyst through systematic variation of the acid p K a , scan rate, acid concentration and catalyst concentration

    Inelastic interaction mean free path of negative pions in tungsten

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    The inelastic interaction mean free paths lambda of 5, 10, and 15 GeV/c pions were measured by determining the distribution of first interaction locations in a modular tungsten-scintillator ionization spectrometer. In addition to commonly used interaction signatures of a few (2-5) particles in two or three consecutive modules, a chi2 distribution is used to calculate the probability that the first interaction occurred at a specific depth in the spectrometer. This latter technique seems to be more reliable than use of the simpler criteria. No significant dependence of lambda on energy was observed. In tungsten, lambda for pions is 206 plus or minus 6 g/sq cm

    Human cancers over express genes that are specific to a variety of normal human tissues

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    We have analyzed gene expression data from 3 different kinds of samples: normal human tissues, human cancer cell lines and leukemic cells from lymphoid and myeloid leukemia pediatric patients. We have searched for genes that are over expressed in human cancer and also show specific patterns of tissue-dependent expression in normal tissues. Using the expression data of the normal tissues we identified 4346 genes with a high variability of expression, and clustered these genes according to their relative expression level. Of 91 stable clusters obtained, 24 clusters included genes preferentially expressed either only in hematopoietic tissues or in hematopoietic and 1-2 other tissues; 28 clusters included genes preferentially expressed in various non-hematopoietic tissues such as neuronal, testis, liver, kidney, muscle, lung, pancreas and placenta. Analysis of the expression levels of these 2 groups of genes in the human cancer cell lines and leukemias, identified genes that were highly expressed in cancer cells but not in their normal counterparts, and were thus over expressed in the cancers. The different cancer cell lines and leukemias varied in the number and identity of these over expressed genes. The results indicate that many genes that are over expressed in human cancer cells are specific to a variety of normal tissues, including normal tissues other than those from which the cancer originated. It is suggested that this general property of cancer cells plays a major role in determining the behavior of the cancers, including their metastatic potential.Comment: To appear in PNA

    The release of the prothoracicotropic hormone in the tobacco hornworm, Manduca sexta, is controlled intrinsically by juvenile hormone

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    Pupal development is elicited early in the last larval instar of the tobacco hornworm, Manduca sexta (Johannson), by a precise temporal and quantitative increase in the haemolymph titre of 20-hydroxyecdysone. This increase in the titre is referred to as the pupal commitment peak, and it occurs once the titre of juvenile hormone (JH) has dropped. If the haemolymph titre of JH remains elevated at this time due to topical application of the hormone or of its analogue ZR512, commitment is delayed or inhibited in a dose-dependent manner. This delay or inhibition is due to the curtailment of the commitment peak in the ecdysteroid titre, which results from a failure of the prothoracic glands (PG) to increase the synthesis/secretion of the premoulting hormone, ecdysone. Since the PG from ZR512- and JH 1-treated larvae are capable of being activated in vitro by the prothoracicotropic hormone (PTTH), the effect of JH on the PG does not involve suppression of gland sensitivity to PTTH. The locus of the JH effect was determined to be the brain-retrocerebral complexes (Br-CC-CA), on the basis of experiments which tested the effect of implanted Br-CC-CA from pre-commitment larvae treated with JH on the occurrence of pupal commitment in head-ligated larval hosts. The implanted, JH-treated Br-CC-CA exhibited a delayed release of PTTH, and the effect was at concentrations of JH that were physiological. These results argue that JH functions to control the time during the last larval instar when pupal commitment occurs by dictating when PTTH will undergo gated release
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