7,276 research outputs found
No X-Ray Excess from the HESS J1741-302 Region except a New Intermediate Polar Candidate
With the Suzaku satellite, we observed an unidentified TeV gamma-ray source
HESS J1741302 and its surroundings. No diffuse or point-like X-ray sources
are detected from the bright southern emission peak of HESS J1741302. From
its neighborhood, we found a new intermediate polar candidate at the position
of (\alpha, \delta)_{\rm J2000.0} = (\timeform{17h40m35.6s},
\timeform{-30D14m16s}), which is designated as Suzaku J174035.6301416. The
spectrum of Suzaku J174035.6301416 exhibits emission lines at the energy of
6.4, 6.7 and 7.0 keV, which can be assigned as the K lines from
neutral, He-like and H-like iron, respectively. A coherent pulsation is found
at a period of 432.1 0.1 s. The pulse profile is quasi-sinusoidal in the
hard X-ray band (48 keV), but is more complicated in the soft X-ray band
(13 keV). The moderate period of pulsation, the energy flux, and the
presence of the iron K lines indicate that Suzaku J174035.6301416 is
likely an intermediate polar, a subclass of magnetized white dwarf binaries
(cataclysmic variables).
Based on these discoveries, we give some implications on the origin of GCDX
and brief comments on HESS J1741302 and PSR B173730.Comment: Accepted by PAS
CaMKIIalpha interacts with multi-PDZ domain protein MUPP1 in spermatozoa and prevents spontaneous acrosomal exocytosis
The success of acrosomal exocytosis, a complex process with a variety of inter-related steps, relies on the coordinated interaction of participating signaling molecules. Since the acrosome reaction resembles Ca(2+)-regulated exocytosis in neurons, we investigated whether cognate neuronal binding partners of the multi-PDZ domain protein MUPP1, which recruits molecules that control the initial tethering and/or docking between the acrosomal vesicle and the plasma membrane, are also expressed in spermatozoa, and whether they contribute to the regulation of acrosomal secretion. We observed that CaMKIIalpha colocalizes with MUPP1 in the acrosomal region of epididymal spermatozoa where the kinase selectively binds to a region encompassing PDZ domains 10-11 of MUPP1. Furthermore, we found that pre-treating mouse spermatozoa with a CaMKII inhibitor that directly blocks the catalytic region of the kinase, as well as a competitive displacement of CaMKIIalpha from PDZ domains 10-11, led to a significant increase in spontaneous acrosomal exocytosis. Since Ca(2+)-calmodulin releases CaMKIIalpha from the PDZ scaffolding protein, MUPP1 represents a central signaling platform to dynamically regulate the assembly and disassembly of binding partners pertinent to acrosomal secretion, thereby precisely adjusting an increase in Ca(2+) to synchronized fusion pore formation
(Biphenyl-2-yl)bromidobis(2-methyltetrahydrofuran-[kappa]O)magnesium(II)
In the title Grignard reagent, [MgBr(C12H9)(C5H10O)2], the Mg centre adopts a distorted tetrahedral MgCO2Br arrangement. The dihedral angle between the two aromatic rings of the biphenyl residue is 44.00 (14)°. Each molecule incorporates one R- and one S-configured 2-methyltetrahydrofuran molecule. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(CâC) = 0.007 Ă
; R factor = 0.045; wR factor = 0.108; data-to-parameter ratio = 17.4
The Formation and Fragmentation of Disks around Primordial Protostars
The very first stars to form in the Universe heralded an end to the cosmic
dark ages and introduced new physical processes that shaped early cosmic
evolution. Until now, it was thought that these stars lived short, solitary
lives, with only one extremely massive star, or possibly a very wide binary
system, forming in each dark matter minihalo. Here we describe numerical
simulations that show that these stars were, to the contrary, often members of
tight multiple systems. Our results show that the disks that formed around the
first young stars were unstable to gravitational fragmentation, possibly
producing small binary and higher-order systems that had separations as small
as the distance between the Earth and the Sun.Comment: This manuscript has been accepted for publication in Science. This
version has not undergone final editing. Please refer to the complete version
of record at http://www.sciencemag.org
Experimental and computational analyses reveal that environmental restrictions shape HIV-1 spread in 3D cultures
Here, using an integrative experimental and computational approach, Imle et al. show how cell motility and density affect HIV cell-associated transmission in a three-dimensional tissue-like culture system of CD4+ T cells and collagen, and how different collagen matrices restrict infection by cell-free virions
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