TREM2 deficiency attenuates neuroinflammation and protects against neurodegeneration in a mouse model of tauopathy

Significance Alzheimer’s disease (AD) is the most common cause of dementia and is a major public health problem for which there is currently no disease-modifying treatment. There is an urgent need for greater understanding of the molecular mechanisms underlying neurodegeneration in patients to create better therapeutic options. Recently, genetic studies uncovered novel AD risk variants in the microglial receptor, triggering receptor expressed on myeloid cells 2 (TREM2). Previous studies suggested that loss of TREM2 function worsens amyloid-β (Aβ) plaque-related toxicity. In contrast, we observe TREM2 deficiency mitigates neuroinflammation and protects against brain atrophy in the context of tau pathology. These findings indicate dual roles for TREM2 and microglia in the context of amyloid versus tau pathology, which are important to consider for potential treatments targeting TREM2.</jats:p

Factor XIIIa-positive dermal dendritic cells and HLA-DR expression in radial versus vertical growth-phase melanomas

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72186/1/j.1600-0560.1998.tb01740.x.pd

Stellar disks and halos of the edge-on spiral galaxies: NGC 891, NGC 4144 and NGC 4244

The results of the stellar photometry of the images ACS/WFC and WFPC2 of the HST are used to study stellar population and spatial distribution of stars in three edge-on galaxies: NGC 891, NGC 4144 and NGC 4244. The measuring of the number density of the old stars revealed two stellar substructures in these galaxies: thick disk and halo. The borders of these substructures consisting mainly of red giants, are determined by the change of number density gradient of the old stars. The revealed halos have flattened shapes and extend up to 25 kpc from the galaxy planes. The obtained results of number density distributions of different type stars perpendicular to the galaxy planes allow us to verify our stellar model of spiral galaxies. Using the determination of the tip of red giant branch (TRGB method) we have derived the following distances: D = 9.82 Mpc (NGC 891), D = 7.24 Mpc (NGC 4144), D = 4.29 Mpc (NGC 4244).Comment: 18 pages, 9 figures. accepted to Astrofizic

Broadband Observations of the Afterglow of GRB 000926: Observing the Effect of Inverse Compton Scattering and Evidence for a High-Density Environment

GRB 000926 has one of the best-studied afterglows to-date, with multiple X-ray observations, as well as extensive multi-frequency optical and radio coverage. Broadband afterglow observations, spanning from X-ray to radio frequencies, provide a probe of the density structure of the circumburst medium, as well as of the ejecta energetics, geometry, and the physical parameters of the relativistic blastwave resulting from the explosion. We present an analysis of {\em Chandra X-ray Observatory} observations of this event, along with {\em Hubble Space Telescope} and radio monitoring. We combine these data with ground-based optical and IR observations and fit the synthesized afterglow lightcurve using models where collimated ejecta expand into a surrounding medium. We find that we can explain the broadband lightcurve with reasonable physical parameters only if the cooling is dominated by inverse Compton scattering. Excess X-ray emission in the broadband spectrum indicates that we are directly observing a contribution from inverse Compton scattering. It is the first time this has been observed in a GRB afterglow, and it implies that the GRB exploded in a reasonably dense (n~30 cm^{-3}) medium, consistent with a diffuse interstellar cloud environment.Comment: 16 pages, 5 figures Accepted for publication in the Astrophysical Journa

GRB 010921: Strong Limits on an Underlying Supernova from HST

GRB 010921 was the first HETE-2 GRB to be localized via its afterglow emission. The low-redshift of the host galaxy, z=0.451, prompted us to undertake intensive multi-color observations with the Hubble Space Telescope with the goal of searching for an underlying supernova component. We do not detect any coincident supernova to a limit 1.34 mag fainter than SN 1998bw at 99.7% confidence, making this one of the most sensitive searches for an underlying SN. Analysis of the afterglow data allow us to infer that the GRB was situated behind a net extinction (Milky Way and the host galaxy) of A_V ~ 1.8 mag in the observer frame. Thus, had it not been for such heavy extinction our data would have allowed us to probe for an underlying SN with brightness approaching those of more typical Type Ib/c supernovae

Stellar Subsystems of the Galaxy NGC 2366

Hubble Space Telescope archive data are used to perform photometry of stars in seven fields at the center and periphery of the galaxy NGC2366. The variation of the number density of stars of various ages with galactocentric radius and along the minor axis of the galaxy are determined. The boundaries of the thin and thick disks of the galaxy are found. The inferred sizes of the subsystems of NGC2366 ($Z_{thin} = 4$ kpc and $Z_{thick} = 8$ kpc for the thin and thick disks, respectively) are more typical for spiral galaxies. Evidence for a stellar halo is found at the periphery of NGC2366 beyond the thick disk of the galaxy.Comment: 16 pages, 4 figures, Astronomy Reports, 2008,v. 52, n.1, p. 1

Domain-specific regular acceleration

The regular model-checking approach is a set of techniques aimed at exploring symbolically infinite state spaces. These techniques proceed by representing sets of configurations of the system under analysis by regular languages, and the transition relation between these configurations by a transformation over such languages. The set of reachable configurations can then be computed by repeatedly applying the transition relation, starting from a representation of the initial set of configurations, until a fixed point is reached. In order for this computation to terminate, it is generally needed to introduce so-called acceleration operators, the purpose of which is to explore in one computation step infinitely many paths in the transition graph of the system. A simple form of acceleration operator is one that is associated to a cycle in the transition graph, computing the set of states that can be obtained by following this cycle arbitrarily many times. The computation of acceleration operators is strongly dependent on the type of the data values that are manipulated by the system, and on the symbolic representation chosen for handling sets of such values. In this survey, we describe acceleration operators suited for the regular state-space exploration of systems relying on FIFO communication channels, as well as those based on integer and real variables