3,918 research outputs found
Psychosis in Azheimer\u27s Disease
Much of the basic science literature on Alzheimer\u27s Disease (AD) reflects ongoing research into pathophysiology and neuropathology. Yet, despite reports of the association between psychotic symptoms and Alzheimer\u27s disease, relatively little is known about why such symptoms develop in certain patients and not in others. Neuroimaging and genetic studies may provide greater understanding of this association and allow clinicians and researchers to prevent, predict and treat the onset of psychotic symptoms in the future. This paper will review the current literature on the topic of psychosis in Alzheimer\u27s disease and focus on current recommendations for interventions by clinicians and caregivers
The Recurrent Nature of Central Starbursts
New hydrodynamic models with feedback show that feedback driven turbulence
and subsequent relaxation can drive recurrent starbursts, though most of these
bursts fizzle due to premature, asymmetric ignition. Strong bursts are
terminated when the turbulence inflates the multiphase central disk. The period
between bursts is about twice a free-fall time onto the central disk. Transient
spirals and bars are common through the burst cycle.Comment: 7 pages + 3 figs. Conf. paper for "Starbursts: from 30 Doradus to
Lyman Break Galaxies," held at Inst. of Astronomy, Cambridge Univ., Sept.
6-10, 2004. Kluwer Academic Publishers, eds. R. de Grijs and R. M. Gonzalez
Delgado + additional materia
The Wide-Angle Outflow of the Lensed z = 1.51 AGN HS 0810+2554
We present results from X-ray observations of the gravitationally lensed z =
1.51 AGN HS 0810+2554 performed with the Chandra X-ray Observatory and
XMM-Newton. Blueshifted absorption lines are detected in both observations at
rest-frame energies ranging between ~1-12 keV at > 99% confidence. The inferred
velocities of the outflowing components range between ~0.1c and ~0.4c. A strong
emission line at ~6.8 keV accompanied by a significant absorption line at ~7.8
keV is also detected in the Chandra observation. The presence of these lines is
a characteristic feature of a P-Cygni profile supporting the presence of an
expanding outflowing highly ionized iron absorber in this quasar. Modeling of
the P-Cygni profile constrains the covering factor of the wind to be > 0.6,
assuming disk shielding. A disk-reflection component is detected in the
XMM-Newton observation accompanied by blueshifted absorption lines. The
XMM-Newton observation constrains the inclination angle to be < 45 degrees at
90% confidence, assuming the hard excess is due to blurred reflection from the
accretion disk. The detection of an ultrafast and wide-angle wind in an AGN
with intrinsic narrow absorption lines (NALs) would suggest that quasar winds
may couple efficiently with the intergalactic medium and provide significant
feedback if ubiquitous in all NAL and BAL quasars. We estimate the mass-outflow
rate of the absorbers to lie in the range of 1.5 and 3.4 Msolar/yr for the two
observations. We find the fraction of kinetic to electromagnetic luminosity
released by HS 0810+2554 is large (epsilon = 9 (-6,+8)) suggesting that
magnetic driving is likely a significant contributor to the acceleration of
this outflow.Comment: 27 pages, 13 figures, Accepted for publication in Ap
QGP collective effects and jet transport
We present numerical simulations of the SU(2) Boltzmann-Vlasov equation
including both hard elastic particle collisions and soft interactions mediated
by classical Yang-Mills fields. We provide an estimate of the coupling of jets
to a hot isotropic plasma, which is independent of infrared cutoffs. In
addition, we investigate jet propagation in anisotropic plasmas, as created in
heavy-ion collisions. The broadening of jets is found to be stronger along the
beam line than in azimuth due to the creation of field configurations with
B_t>E_t and E_z>B_z via plasma instabilities.Comment: 4 pages, 5 figures. Presented at the 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008),
Jaipur, India, 4-10 Feb 200
Jet broadening in unstable non-Abelian plasmas
We perform numerical simulations of the QCD Boltzmann-Vlasov equation
including both hard elastic particle collisions and soft interactions mediated
by classical Yang-Mills fields. We provide an estimate of the coupling of jets
to a hot plasma which is independent of infrared cutoffs. For weakly-coupled
anisotropic plasmas the local rotational symmetry in momentum space is broken.
The fields develop unstable modes, forming configurations where B_t>E_t and
E_z>B_z. This provides a possible explanation for the experimental observation
that high-energy jets traversing the plasma perpendicular to the beam axis
experience much stronger broadening in rapidity than in azimuth.Comment: 6 pages, 7 figures, version accepted for publication in Phys.Rev.C,
typos fixed, more detailed discussion of q-ha
The quest for hot gas in the halo of NGC 1511
XMM-Newton observations of the starburst galaxy NGC 1511 reveal the presence
of a previously unknown extended hot gaseous phase of its ISM, which partly
extends out of the disk plane. The emission distribution is asymmetric, being
brightest in the eastern half of the galaxy, where also radio continuum
observations suggest the highest level of star formation. Spectral analysis of
the integral 0.2-12 keV X-ray emission from NGC 1511 indicates a complex
emission composition. A model comprising a power law plus thermal plasma
component, both absorbed by foreground gas, cannot explain all details of the
observed spectrum, requiring a third spectral component to be added. This
component can be a second thermal plasma, but other spectral models can be
fitted as well. Its X-ray properties characterize NGC 1511 as a starburst
galaxy. The X-ray-to-infrared luminosity ratio is consistent with this result.
Together with the X-ray data, XMM-Newton obtained UV images of NGC 1511,
tracing massive stars heating the ambient gas, which is then seen in H\alpha
emission. UV, H\alpha and near-infrared imagery suggest that NGC 1511 is
disturbed, most likely by its two small companions, NGC 1511a and NGC 1511b.Comment: 7 pages, 7 figures, accepted for publication in A&
Early Time Evolution of High Energy Heavy Ion Collisions
We solve the Yang-Mills equations in the framework of the
McLerran-Venugopalan model for small times tau after a collision of two nuclei.
An analytic expansion around tau=0 leads to explicit results for the field
strength and the energy momentum tensor of the gluon field at early times. We
then discuss constraints for the energy density, pressure and flow of the
plasma phase that emerges after thermalization of the gluon field.Comment: 4 pages, 1 figure; contribution to Quark Matter 2006; submitted to J.
Phys.
Design of a Methanol Reformer for on-board Production of Hydrogen as Fuel for a 3kW High-temperature Proton Exchange Membrane Fuel Cell Power System
The method of Computational Fluid Dynamics is used to predict the process parameters and select the optimum operating regime of a methanol reformer for on-board production of hydrogen as fuel for a 3 kW High-Temperature Proton Exchange Membrane Fuel Cell power system. The analysis uses a three reactions kinetics model for methanol steam reforming, water gas shift and methanol decomposition reactions on Cu/ZnO/Al2O3 catalyst. Numerical simulations are performed at single channel level for a range of reformer operating temperatures and values of the molar flow rate of methanol per weight of catalyst at the reformer inlet. Two operating regimes of the fuel processor are selected which offer high methanol conversion rate and high hydrogen production while simultaneously result in a small reformer size and a reformate gas composition that can be tolerated by phosphoric acid-doped high temperature membrane electrode assemblies for proton exchange membrane fuel cells. Based on the results of the numerical simulations, the reactor is sized, and its design is optimized
Multiparticle production in the Glasma at NLO and plasma instabilities
We discuss the relation between multi-particle production in the Glasma at
next-to-leading order and the physics of plasma instabilities.Comment: 4 pages, talk at Quark Matter 200
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