1,280 research outputs found
Simulations of a Multipactor-Inhibited Waveguide Geometry
Studies of multipactor resonances in coaxial and hollow waveguide via standard particle trajectory and secondary emission numerical simulation techniques are presented. Agreement between simulations and experimentally observed multipactor barriers gives confidence in results of simulation studies of a wedge-shaped hollow waveguide geometry that shows promise of being far less susceptible to multipactor resonances than standard coax and hollow rectangular waveguides
NOVEL COMPOUNDS AS POTENTIAL ALZHEIMER\u27S DISEASE THERAPEUTICS AND INHIBITORS OF THE NLRP3 INFLAMMASOME
Alzheimer’s disease is a devastating neurodegenerative disorder and the leading cause of dementia. The disease manifests via several pathologies including neuroinflammation, oxidative stress, metal ion dyshomeostasis, and cell death. To address the multifaceted nature of this disorder, the design of several diverse compounds, targeting many pathological effects, was generated. First, a series of compounds based on curcumin and diosgenin were synthesized following the bivalent design strategy. Two compounds were discovered to have neuroprotective ability, anti-oxidative function, and anti-Aß oligomerization (AßO) properties. A second set of molecules was also designed, wherein a hybrid compound strategy was utilized. Three hybrids were to shown to protect MC65 cells from Aß-induced toxicity and to have significant anti-oxidative activity. Mechanistic studies propose that protection is through disruption of interactions between AßOs and partner proteins. Furthermore, one hybrid was also shown to be able to pass the BBB. Lastly, studies of glyburide, an anti-diabetic medication, have shown an off-target anti-inflammatory effect specific for the NLRP3 inflammasome, which has been implicated in AD development. Therefore, a series of glyburide analogs were synthesized and characterized. One analog was able to successfully inhibit the NLRP3 inflammasome and reduce IL-1ß expression without affecting blood glucose. In vivo studies demonstrated an ability to prevent or ameliorate adverse inflammation-related outcomes in murine inflammatory models. Altogether, these investigations have yielded three novel series of compounds, all capable of modifying Alzheimer’s disease pathology. These results warrant future investigations into the development, optimization, and characterization of these analogs as potential treatments for Alzheimer’s disease
Viscosity of an ideal relativistic quantum fluid: A perturbative study
We show that a quantized ideal fluid will generally exhibit a small but
non-zero viscosity due to the backreaction of quantum soundwaves on the
background. We use an effective field theory expansion to estimate this
viscosity to first order in perturbation theory. We discuss our results, and
whether this estimate can be used to obtain a more model-independent estimate
of the "quantum bound" on the viscosity of physical systemsComment: Accepted for publication, Phys.Rev.D. Discussion slightly clarified
and extended, references added, error in calculation fixed. COnclusions
unchange
Shape dependence of two-cylinder Renyi entropies for free bosons on a lattice
Universal scaling terms occurring in Renyi entanglement entropies have the
potential to bring new understanding to quantum critical points in free and
interacting systems. Quantitative comparisons between analytical continuum
theories and numerical calculations on lattice models play a crucial role in
advancing such studies. In this paper, we exactly calculate the universal
two-cylinder shape dependence of entanglement entropies for free bosons on
finite-size square lattices, and compare to approximate functions derived in
the continuum using several different ansatzes. Although none of these ansatzes
are exact in the thermodynamic limit, we find that numerical fits are in good
agreement with continuum functions derived using the AdS/CFT correspondence, an
extensive mutual information model, and a quantum Lifshitz model. We use fits
of our lattice data to these functions to calculate universal scalars defined
in the thin-cylinder limit, and compare to values previously obtained for the
free boson field theory in the continuum.Comment: 7 pages, 5 figures, 1 tabl
A Hybrid Model for QCD Deconfining Phase Boundary
Intensive search for a proper and realistic equations of state (EOS) is still
continued for studying the phase diagram existing between quark gluon plasma
(QGP) and hadron gas (HG) phases. Lattice calculations provide such EOS for the
strongly interacting matter at finite temperature () and vanishing baryon
chemical potential (). These calculations are of limited use at finite
due to the appearance of notorious sign problem. In the recent past,
we had constructed a hybrid model description for the QGP as well as HG phases
where we make use of a new excluded-volume model for HG and a
thermodynamically-consistent quasiparticle model for the QGP phase and used
them further to get QCD phase boundary and a critical point. Since then many
lattice calculations have appeared showing various thermal and transport
properties of QCD matter at finite and . We test our hybrid
model by reproducing the entire data for strongly interacting matter and
predict our results at finite so that they can be tested in future.
Finally we demonstrate the utility of the model in fixing the precise location,
the order of the phase transition and the nature of CP existing on the QCD
phase diagram. We thus emphasize the suitability of the hybrid model as
formulated here in providing a realistic EOS for the strongly interacting
matter.Comment: 22 pages, 10 figures. corrected version published in Physical Review
D. arXiv admin note: substantial text overlap with arXiv:1201.044
Impedance of a Rectangular Beam Tube with Small Corrugations
We consider the impedance of a structure with rectangular, periodic
corrugations on two opposing sides of a rectangular beam tube. Using the method
of field matching, we find the modes in such a structure. We then limit
ourselves to the the case of small corrugations, but where the depth of
corrugation is not small compared to the period. For such a structure we
generate analytical approximate solutions for the wave number , group
velocity , and loss factor for the lowest (the dominant) mode
which, when compared with the results of the complete numerical solution,
agreed well. We find: if , where is the beam pipe width and is
the beam pipe half-height, then one mode dominates the impedance, with
( is the depth of corrugation),
, and , which (when replacing by
) is the same scaling as was found for small corrugations in a {\it round}
beam pipe. Our results disagree in an important way with a recent paper of
Mostacci {\it et al.} [A. Mostacci {\it et al.}, Phys. Rev. ST-AB, {\bf 5},
044401 (2002)], where, for the rectangular structure, the authors obtained a
synchronous mode with the same frequency , but with .
Finally, we find that if is large compared to then many nearby modes
contribute to the impedance, resulting in a wakefield that Landau damps.Comment: 18 pages, 6 figures, 1 bibliography fil
3-[(E)-2-(5,7-Dichloro-8-hydroxyquinolin-2-yl)vinyl]-4-hydroxyphenyl acetate
The two symmetry independent molecules of the title compound, C19H13Cl2NO4, show similar conformations with the acetyl group twisted strongly relative to the remaining, virtually flat (r.m.s. deviations = 0.0173 and 0.0065 Å), part of the molecule. The hydroxyl groups of the 8-hydroxyquinoline residues are involved in intramolecular O—H⋯N hydrogen bonds, which, in one case, forms a part of a three-center interaction. Intermolecular O—H⋯O hydrogen bonds assemble the molecules into a one-dimensional polymeric structure extended along the a axis. The 4-hydroxyphenyl group of one molecule forms an O—H⋯O hydrogen bond, in which the hydroxyl H atom is disordered, with its inversion center counterpart
Ferrite-damped higher-order mode study in the Brookhaven energy-recovery linac cavity
A superconducting energy-recovery linac (ERL) is under construction at Brookhaven National Laboratory (BNL) to serve as a test bed for an application to upgrades of the Relativistic Heavy Ion Collider (RHIC). The damping of higher-order modes in the superconducting five-cell cavity is of paramount importance and represents the topic of this paper. Achieving the damping by the exclusive use of two ferrite absorbers and the adoption of a space-saving step instead of the conventional taper are part of the exploratory study. Absorber properties which are portable to simulation programs for the ERL cavity have been obtained by measuring the absorber as a ferrite-loaded pill-box cavity. Measured and simulated results for the lowest dipole modes in the prototype copper cavity with one absorber are discussed. First room-temperature measurements of the fully assembled niobium cavity string are presented which confirm the effective damping of higher-order modes by the ferrite absorbers, and which give credibility to the simulated R over Q's in the ERL.open1
Charge dependent azimuthal correlations in Pb--Pb collisions at TeV
Separation of charges along the extreme magnetic field created in non-central
relativistic heavy--ion collisions is predicted to be a signature of local
parity violation in strong interactions. We report on results for charge
dependent two particle azimuthal correlations with respect to the reaction
plane for Pb--Pb collisions at TeV recorded in 2010 with
ALICE at the LHC. The results are compared with measurements at RHIC energies
and against currently available model predictions for LHC. Systematic studies
of possible background effects including comparison with conventional
(parity-even) correlations simulated with Monte Carlo event generators of
heavy--ion collisions are also presented.Comment: Published in the proceedings of "Quark Matter 2011", Annecy-Franc
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