The Production of Anti-Matter in our Galaxy

The discovery of a single anti-helium nucleus in the cosmic ray flux would definitely point toward the existence of stars and even of entire galaxies made of anti-matter. The presence of anti-nuclei in cosmic rays has actually profound implications on the fundamental question of the baryon asymmetry of the universe. It is therefore crucial to determine the amount of anti-matter which our own galaxy already produces through the spallation of high-energy protons on the interstellar gas of the galactic disk. We have used here a coalescence model to assess the amount of anti-deuterium and anti-helium 3 present in cosmic rays together with anti-protons. The propagation of cosmic rays in the galaxy is described through a two-zone diffusion model which correctly describes the observed abundances. We find that the antideuterium/proton ratio exceeds $10^{-9}$ above a momentum per anti-nucleon of about 4 GeV/c. Would the universe be purely made of matter, the AMS collaboration should be able to detect a few anti-deuterons during the space station stage of the experiment. However, the antihelium3/proton abundance does not exceed $4 10^{-13}$. Heavier anti-nuclei are even further suppressed.Comment: 15 pages, 2 figure

Functional Stability of Unliganded Envelope Glycoprotein Spikes among Isolates of Human Immunodeficiency Virus Type 1 (HIV-1)

The HIV-1 envelope glycoprotein (Env) spike is challenging to study at the molecular level, due in part to its genetic variability, structural heterogeneity and lability. However, the extent of lability in Env function, particularly for primary isolates across clades, has not been explored. Here, we probe stability of function for variant Envs of a range of isolates from chronic and acute infection, and from clades A, B and C, all on a constant virus backbone. Stability is elucidated in terms of the sensitivity of isolate infectivity to destabilizing conditions. A heat-gradient assay was used to determine T90 values, the temperature at which HIV-1 infectivity is decreased by 90% in 1 h, which ranged between ∼40 to 49°C (n = 34). For select Envs (n = 10), the half-lives of infectivity decay at 37°C were also determined and these correlated significantly with the T90 (p = 0.029), though two ‘outliers’ were identified. Specificity in functional Env stability was also evident. For example, Env variant HIV-1ADA was found to be labile to heat, 37°C decay, and guanidinium hydrochloride but not to urea or extremes of pH, when compared to its thermostable counterpart, HIV-1JR-CSF. Blue native PAGE analyses revealed that Env-dependent viral inactivation preceded complete dissociation of Env trimers. The viral membrane and membrane-proximal external region (MPER) of gp41 were also shown to be important for maintaining trimer stability at physiological temperature. Overall, our results indicate that primary HIV-1 Envs can have diverse sensitivities to functional inactivation in vitro, including at physiological temperature, and suggest that parameters of functional Env stability may be helpful in the study and optimization of native Env mimetics and vaccines

Holographic determination of demineralization of bones

Patients with osteomalacia often complain of back pain or diffuse peripheral bone aches where a mechanical component warrants closer investigations. In order to study the stress-strain patterns in whole human bones and the influence of the degree of calcification upon these patterns, normal bones are submitted to stress and holographic studies are performed prior to and after demineralization. Interpretation of fringes is delicate because the type of loading must be the same in all the experiments with the same bone. Or the demineralization can change non uniformaly the nature of the osseous inhomogeneous structure and caution must be taken to avoid resulting change namely in momentum. Displacements components must be determined in each face of the bone and the calcul of stresses is made in a first step with assumption of equivalent homogeneous material. The problems arrizing in the machanical behaviour of bones are studied experimentally with the various stress analysis techniques. Among these holographical interferometry proved to be particularly well suited because of its high sensitivity, the rough bone surface needs no preparation and it yields the whole deformation field of the surface. Unfortunately the mechanical comportment of the osseous material depends of many factors and the demineralization namely can change non uniformaly the nature of the inhomogeneous structures like bones and caution must be taken for the interpretation of holographic fringes :Because of structural variations in bones, apparently similar types of loading can be different namely by evolution of the position of the neutral axis for momentum. Those phenomena will be analysed in different examples. If estimation of demineralization effect is desired, for instance by measurement of appropriated change in elastic modulus, it is important to know any variation in the loading conditions due to specific changes of the material. The first problem considered concerned the measure of Young's modulus E and Poisson's ration of a tigh-bone or tibia. Small test specimens of constant rectangular section are cut out and submitted to pure bending. Classical double exposure holograms are recorded, with the directions of lighting n1 and observation n2 of the specimen nearly parallel to the normal Oz by use of a mirror. (cfr Figure 1). © 1980 SPIE.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Effect of a pulse injection of methylprednisolone on the biological parameters of bone metabolism in patients with rheumatoid arthritis

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Regional bone calcium turnover rate in rheumatoid arthritis: comparison with the disease activity

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Métabolisme osseux dans l'arthrite rhumatoïde

English AbstractJournal Articleinfo:eu-repo/semantics/publishe

Evaluation de la scintigraphie articulaire au pyrophosphate et au fibrinogène marqués par le technetium 99m dans la polyarthrite rhumatoïde (PR) et dans d'autres arthropathies.

Clinical TrialJournal Articleinfo:eu-repo/semantics/publishe

Bone mass in rheumatoid arthritis

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