نتایج جستجو برای: 421
تعداد نتایج: 3662 فیلتر نتایج به سال:
The extremely rapid burst of TeV photons from Mkn 421 (15 May 1996) can be reconciled with the standard properties of a relativistic γ-ray emitting jet (bulk Lorentz factor Γ ∼ 10; size ∼ 10 cm) if one assumes that the electrons are accelerated in conical shocks with both opening and viewing angles ≈ 1/Γ. If the injection time and the cooling time are much less than the photon crossing time, an...
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BACKGROUND In French Guiana, a French overseas territory in South America, 6 to 10 thousands undocumented persons work illegally in gold mining sites in the Amazonian forest. Precarious life conditions lead to poor health but few data exist on the health status of illegal gold miners in French Guiana. The objective of this article was to describe the sociodemographic and health status of this v...
The soft X-ray background shows a general enhancement toward the inner region of the Galaxy. But whether this enhancement is a local feature (e.g., a superbubble within a distance of < ∼ 200 pc) and/or a phenomenon related to energetic outflows from the Galactic center/bulge remains unclear. Here we report a comparative X-ray emission and absorption study of diffuse hot gas along the sight line...
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