Measurement of the diameter of Mercury by the Hertzsprung method on November 7, 1960

Measurement of Mercury /planet/ diameter by Hertzsprung metho

A new biophysical decompression model for estimating the risk of articular bends during and after decompression

International audienceThe biophysical models that intend to predict the risk of decompression sickness after a change of pressure are not numerous. Few approaches focus in particular on joints as target tissues, with the aim to describe properly the mechanisms inducing pain. Nevertheless, for this type of decompression incidents, called , no model proved to fit the empirical results for a broad range of exposures and decompression procedures. We present here an original biophysical decompression model for describing the occurrence of articular bends. A target joint is broken down into two parts that exchange inert gases with the blood by perfusion and with each other by diffusion over distances of a few millimeters. This diffusion pathway allows the slow amplification of microbubbles growing during and after decompression, consistent with the possible delayed occurrence of bends. The diffusion coefficients introduced into this model are larger than those introduced into most modern decompression models. Their value remains physical (#10m/s). Inert gas exchanges and the formation, amplification and resorption of microbubbles during and after decompression were simulated. We used a critical gas volume criterion for predicting the occurrence of bends. A risk database extracted from COMEX experience and other published studies was used for the correlation of model parameters not known . We considered a large range of exposure, and the commonly used inert gases nitrogen and helium. This correlation phase identified the worst biophysical conformations most likely to lead to the formation, in tissues such as tendons, of a large number of microbubbles recruited from pre-existing gas nuclei during decompression. The risk of bends occurrence was found to be linked to the total separated gas volume generated during and after decompression. A clamping phenomenon occurs soon after the start of decompression, greatly slowing the gas exchanges controlled especially by the oxygen window. This model, which reproduces many empirical findings, may be considered both descriptive and predictive

Flow patterns and heat transfer in a square cross-section micro condenser working at low mass fluxes

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Flow patterns and heat transfer in an air-cooled square cross-section micro condenser were investigated. The test section consisted of a borosilicate square micro channel, of inner and outer hydraulic diameters of 0.49 mm and 0.6 mm respectively, and a length of 100 mm. The transparent material of the micro channel allowed the visualization of the different condensation flow patterns. The imposed mass velocities were ranging between 1 and 10 kg m-2 s-1. In this range of mass fluxes, three main flow regimes were identified: Annular regime, intermittent regime, and spherical bubbles regime. Then, the isolated bubbles zone (the end of the intermittent zone + the spherical bubbles zone) was particularly studied. A specific experimental procedure was developed, basing on bubble tracking, in order to determine accurately the hydraulic and thermal parameters profiles in this zone according to the axial position in the micro channel, such as the vapour quality profile x(z). Thanks to energy balance, the liquid temperature profile Tl(z) in the isolated bubbles zone was determined for different initial values. A thermal non-equilibrium between the liquid and vapour phases was identified. Therefore, the latent heat flux was then quantified and compared to the total heat flux in this zone.FNRAE (MATRAS) and the Microgravity Application Program of the European Space Agenc

Reducing calcium-mediated endoplasmic reticulum stress could attenuate beta-amyloid peptide neurotoxicity

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Research strategies in molecular signaling of neuronal apoptosis in Alzheimer's disease

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Metaflammasome components in the human brain: a role in dementia with alzheimer's pathology?

Epidemiological and genetic studies have identified metabolic disorders and inflammation as risk factors for Alzheimer's disease (AD). Evidence in obesity and type-2 diabetes suggests a role for a metabolic inflammasome (“metaflammasome”) in mediating chronic inflammation in peripheral organs implicating IKKβ (inhibitor of nuclear factor kappa-B kinase subunit beta), IRS1 (insulin receptor substrate 1), JNK (c-jun N-terminal kinase), and PKR (double-stranded RNA protein kinase). We hypothesized that these proteins are expressed in the brain in response to metabolic risk factors in AD. Neocortex from 299 participants from the MRC Cognitive Function and Ageing Studies was analysed by immunohistochemistry for the expression of the phosphorylated (active) form of IKKβ [pSer176/180], IRS1 [pS312], JNK [pThr183/Tyr185] and PKR [pT451]. The data were analyzed to investigate whether the proteins were expressed together and in relation with metabolic disorders, dementia, Alzheimer's pathology and APOE genotype. We observed a change from a positive to a negative association between the proteins and hypertension according to the dementia status. Type-2 diabetes was negatively related with the proteins among participants without dementia; whereas participants with dementia and AD pathology showed a positive association with JNK. A significant association between IKKβ and JNK in participants with dementia and AD pathology was observed, but not in those without dementia. Otherwise, weak to moderate associations were observed among the protein loads. The presence of dementia was significantly associated with JNK and negatively associated with IKKβ and IRS1. Cognitive scores showed a significant positive relationship with IKKβ and a negative with IRS1, JNK and PKR. The proteins were significantly associated with pathology in Alzheimer's participants with the relationship being inverse or not significant in participants without dementia. Expression of the proteins was not related to APOE genotype. These findings highlight a role for these proteins in AD pathophysiology but not necessarily as a complex

Radiative lifetime measurements of rubidium Rydberg states

We have measured the radiative lifetimes of ns, np and nd Rydberg states of rubidium in the range 28 < n < 45. To enable long-lived states to be measured, our experiment uses slow-moving Rb atoms in a magneto-optical trap (MOT). Two experimental techniques have been adopted to reduce random and systematic errors. First, a narrow-bandwidth pulsed laser is used to excite the target Rydberg state, resulting in minimal shot-to-shot variation in the initial state population. Second, we monitor the target state population as a function of time delay from the laser pulse using a short-duration, millimetre-wave pulse that is resonant with a one- or two-photon transition. We then selectively field ionize the monitor state, and detect the resulting electrons with a micro-channel plate. This signal is an accurate mirror of the target state population, and is uncontaminated by contributions from other states which are populated by black body radiation. Our results are generally consistent with other recent experimental results obtained using a less sensitive method, and are also in excellent agreement with theory.Comment: 27 pages,6 figure

Reliability and Validity Evidence of Scores on the French Version of the Questionnaire about Interpersonal Difficulties for Adolescents

This study examined the reliability and validity evidence drawn from the scores of the French version of the Questionnaire about Interpersonal Difficulties for Adolescents (QIDA) in a sample of 957 adolescents (48.5% boys) ranging in age from 11 to 18 years (M = 14.48, SD = 1.85). A principal axis factoring (PAF) and confirmatory factor analyses (CFA) were performed to determine the fit of the factor structure of scores on the QIDA. PAF and CFA replicated the previously identified correlated five-factor structure of the QIDA: Assertiveness, Heterosexual Relationships, Public Speaking, Family Relationships, and Close Friendships. The QIDA yielded acceptable reliability scores for French adolescents. Validity evidence of QIDA was also established through correlations with scores on the School Anxiety Inventory and the Social Anxiety Scale for Adolescents. Most of the correlations were positive and exceeded the established criteria of statistical significance, but the magnitude of these varied according to the scales of the QIDA. Results supported the reliability and validity evidence drawn from the scores of the French version of the QIDA