330 research outputs found
XMM-Newton Observations of PSR B1706-44
We report on the XMM-Newton observations of the young, 102 ms pulsar PSR
B1706-44. We have found that both a blackbody plus power-law and a magnetized
atmospheric model plus power-law provide an excellent fit to the EPIC spectra.
The two scenarios are therefore indistinguishable on a statistical basis,
although we are inclined to prefer the latter on physical grounds. In this
case, assuming a source distance of ~2.3 kpc, the size of the region
responsible for the thermal emission is R~13 km, compatible with the surface of
a neutron star. A comparison of the surface temperature of PSR B1706-44
obtained from this fit with cooling curves favor a medium mass neutron star
with M~1.45 solar masses or M~1.59 solar masses, depending on two different
models of proton superfluidity in the interior. The large collecting area of
XMM-Newton allows us to resolve a substructure in the broad soft X-ray
modulation detected by Chandra, revealing the presence of two separate peaks
with pulsed fractions of 7 +/- 4% and 15 +/- 3%, respectively.Comment: 21 pages, 5 figures, 2 tables, accepted for publication in Ap
Genetics Ignite Focus on Microglial Inflammation in Alzheimer\u27s Disease
In the past five years, a series of large-scale genetic studies have revealed novel risk factors for Alzheimer\u27s disease (AD). Analyses of these risk factors have focused attention upon the role of immune processes in AD, specifically microglial function. In this review, we discuss interpretation of genetic studies. We then focus upon six genes implicated by AD genetics that impact microglial function: TREM2, CD33, CR1, ABCA7, SHIP1, and APOE. We review the literature regarding the biological functions of these six proteins and their putative role in AD pathogenesis. We then present a model for how these factors may interact to modulate microglial function in AD
Intraneuronal Aβ detection in 5xFAD mice by a new Aβ-specific antibody
<p>Abstract</p> <p>Background</p> <p>The form(s) of amyloid-β peptide (Aβ) associated with the pathology characteristic of Alzheimer's disease (AD) remains unclear. In particular, the neurotoxicity of intraneuronal Aβ accumulation is an issue of considerable controversy; even the existence of Aβ deposits within neurons has recently been challenged by Winton and co-workers. These authors purport that it is actually intraneuronal APP that is being detected by antibodies thought to be specific for Aβ. To further address this issue, an anti-Aβ antibody was developed (MOAB-2) that specifically detects Aβ, but not APP. This antibody allows for the further evaluation of the early accumulation of intraneuronal Aβ in transgenic mice with increased levels of human Aβ in 5xFAD and 3xTg mice.</p> <p>Results</p> <p>MOAB-2 (mouse IgG<sub>2b</sub>) is a pan-specific, high-titer antibody to Aβ residues 1-4 as demonstrated by biochemical and immunohistochemical analyses (IHC), particularly compared to 6E10 (a commonly used commercial antibody to Aβ residues 3-8). MOAB-2 did not detect APP or APP-CTFs in cell culture media/lysates (HEK-APP<sub>Swe </sub>or HEK-APP<sub>Swe</sub>/BACE1) or in brain homogenates from transgenic mice expressing 5 familial AD (FAD) mutation (5xFAD mice). Using IHC on 5xFAD brain tissue, MOAB-2 immunoreactivity co-localized with C-terminal antibodies specific for Aβ40 and Aβ42. MOAB-2 did not co-localize with either N- or C-terminal antibodies to APP. In addition, no MOAB-2-immunreactivity was observed in the brains of 5xFAD/BACE<sup>-/- </sup>mice, although significant amounts of APP were detected by N- and C-terminal antibodies to APP, as well as by 6E10. In both 5xFAD and 3xTg mouse brain tissue, MOAB-2 co-localized with cathepsin-D, a marker for acidic organelles, further evidence for intraneuronal Aβ, distinct from Aβ associated with the cell membrane. MOAB-2 demonstrated strong intraneuronal and extra-cellular immunoreactivity in 5xFAD and 3xTg mouse brain tissues.</p> <p>Conclusions</p> <p>Both intraneuronal Aβ accumulation and extracellular Aβ deposition was demonstrated in 5xFAD mice and 3xTg mice with MOAB-2, an antibody that will help differentiate intracellular Aβ from APP. However, further investigation is required to determine whether a molecular mechanism links the presence of intraneuronal Aβ with neurotoxicity. As well, understanding the relevance of these observations to human AD patients is critical.</p
Frequency dependence of orthogonal polarisation modes in pulsars
We have carried out a study of the orthogonal polarisation mode behaviour as
a function of frequency of 18 pulsars, using average pulsar data from the
European Pulsar Network (EPN). Assuming that the radiation consists of two 100%
polarised completely orthogonal superposed modes we separated these modes,
resulting in average pulse profiles of each mode at multiple frequencies for
each pulsar. Furthermore, we studied the frequency dependence of the relative
intensity of these modes. We found in many pulsars that the average pulse
profiles of the two modes differ in their dependence on frequency. In
particular, we found that pulse components that are dominated by one mode tend
to increase in intensity with increasing frequency with respect to the rest of
the profile.Comment: 31 pages, 24 figures, 1 table, accepted by A&A; added references in
introductio
Different Perspectives of a Factory of the Future: An Overview
Digitalfactory,andCloudManufacturingaretwoapproaches that aim at addressing the Factory of the Future, i.e., to provide digital support to manufacturing factories. They find their roots in two different geographical areas, respectively Europe and China, and therefore presents some differences as well as the same goal of building the factory of the future. In this paper, we present both the digital factory and the cloud manufacturing approaches and discuss their differences
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The observed state of the water cycle in the early twenty-first century
Author Posting. © American Meteorological Society, 2015. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 28 (2015): 8289–8318, doi:10.1175/JCLI-D-14-00555.1.This study quantifies mean annual and monthly fluxes of Earth’s water cycle over continents and ocean basins during the first decade of the millennium. To the extent possible, the flux estimates are based on satellite measurements first and data-integrating models second. A careful accounting of uncertainty in the estimates is included. It is applied within a routine that enforces multiple water and energy budget constraints simultaneously in a variational framework in order to produce objectively determined optimized flux estimates. In the majority of cases, the observed annual surface and atmospheric water budgets over the continents and oceans close with much less than 10% residual. Observed residuals and optimized uncertainty estimates are considerably larger for monthly surface and atmospheric water budget closure, often nearing or exceeding 20% in North America, Eurasia, Australia and neighboring islands, and the Arctic and South Atlantic Oceans. The residuals in South America and Africa tend to be smaller, possibly because cold land processes are negligible. Fluxes were poorly observed over the Arctic Ocean, certain seas, Antarctica, and the Australasian and Indonesian islands, leading to reliance on atmospheric analysis estimates. Many of the satellite systems that contributed data have been or will soon be lost or replaced. Models that integrate ground-based and remote observations will be critical for ameliorating gaps and discontinuities in the data records caused by these transitions. Continued development of such models is essential for maximizing the value of the observations. Next-generation observing systems are the best hope for significantly improving global water budget accounting.This research was funded by multiple
grants from NASA’s Energy and Water Cycle
Study (NEWS) program.2016-05-0
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