2,558 research outputs found
Zero Temperature Thermodynamics of Asymmetric Fermi Gases at Unitarity
The equation of state of a dilute two-component asymmetric Fermi gas at
unitarity is subject to strong constraints, which affect the spatial density
profiles in atomic traps. These constraints require the existence of at least
one non-trivial partially polarized (asymmetric) phase. We determine the
relation between the structure of the spatial density profiles and the T=0
equation of state, based on the most accurate theoretical predictions
available. We also show how the equation of state can be determined from
experimental observations.Comment: 10 pages and 7 figures. (Minor changes to correspond with published
version.
WMAP Haze: Directly Observing Dark Matter?
In this paper we show that dark matter in the form of dense matter/antimatter
nuggets could provide a natural and unified explanation for several distinct
bands of diffuse radiation from the core of the Galaxy spanning over 12 orders
of magnitude in frequency. We fix all of the phenomenological properties of
this model by matching to x-ray observations in the keV band, and then
calculate the unambiguously predicted thermal emission in the microwave band,
at frequencies smaller by 10 orders of magnitude. Remarkably, the intensity and
spectrum of the emitted thermal radiation are consistent with--and could
entirely explain--the so-called "WMAP haze": a diffuse microwave excess
observed from the core of our Galaxy by the Wilkinson Microwave Anisotropy
Probe (WMAP). This provides another strong constraint of our proposal, and a
remarkable nontrivial validation. If correct, our proposal identifies the
nature of the dark matter, explains baryogenesis, and provides a means to
directly probe the matter distribution in our Galaxy by analyzing several
different types of diffuse emissions.Comment: 16 pages, REVTeX4. Updated to correspond with published version:
includes additional appendices discussing finite-size effect
Reversing conditional orderings
We analyze some specific aspects concerning conditional orderings and relations among them. To this purpose we define a suitable concept of reversed conditional ordering and prove some related results. In particular we aim to compare the univariate stochastic orderings ≤ st, ≤ hr, and ≤ lr in terms of differences among different notions of conditional orderings. Some applications of our result to the analysis of positive dependence will be detailed. We concentrate attention to the case of a pair of scalar random variables X, Y . Suitable extensions to multivariate cases are possible
Annexin-A5 assembled into two-dimensional arrays promotes cell membrane repair
Eukaryotic cells possess a universal repair machinery that ensures rapid resealing of plasma membrane disruptions. Before resealing, the torn membrane is submitted to considerable tension, which functions to expand the disruption. Here we show that annexin-A5 (AnxA5), a protein that self-assembles into two-dimensional (2D) arrays on membranes upon Ca2+ activation, promotes membrane repair. Compared with wild-type mouse perivascular cells, AnxA5-null cells exhibit a severe membrane repair defect. Membrane repair in AnxA5-null cells is rescued by addition of AnxA5, which binds exclusively to disrupted membrane areas. In contrast, an AnxA5 mutant that lacks the ability of forming 2D arrays is unable to promote membrane repair. We propose that AnxA5 participates in a previously unrecognized step of the membrane repair process: triggered by the local influx of Ca2+, AnxA5 proteins bind to torn membrane edges and form a 2D array, which prevents wound expansion and promotes membrane resealing
Elastic Nd scattering at intermediate energies as a tool for probing the short-range deuteron structure
A calculation of the deuteron polarization observables , ,
, and the differential cross-section for elastic
nucleon-deuteron scattering at incident deuteron energies 270 and 880 MeV in
lab is presented. A comparison of the calculations with two different deuteron
wave-functions derived from the Bonn-CD -potential model and the dressed
bag quark model is carried out. A model-independent approach, based on an
optical potential framework, is used in which a nucleon-nucleon -matrix is
assumed to be local and taken on the energy shell, but still depends on the
internal nucleon momentum in a deuteron.Comment: 15 pages, 4 figure
Cortical folding in Broca's area relates to obstetric complications in schizophrenia patients and healthy controls
Background The increased occurrence of obstetric complications (OCs) in patients with schizophrenia suggests that alterations in neurodevelopment may be of importance to the aetiology of the illness. Abnormal cortical folding may reflect subtle deviation from normal neurodevelopment during the foetal or neonatal period. In the present study, we hypothesized that OCs would be related to cortical folding abnormalities in schizophrenia patients corresponding to areas where patients with schizophrenia display altered cortical folding when compared with healthy controls. Method In total, 54 schizophrenia patients and 54 healthy control subjects underwent clinical examination and magnetic resonance image scanning on a 1.5 T scanner. Information on OCs was collected from original birth records. An automated algorithm was used to calculate a three-dimensional local gyrification index (lGI) at numerous points across the cortical mantle. Results In both schizophrenia patients and healthy controls, an increasing number of OCs was significantly related to lower lGI in the left pars triangularis (p<0.0005) in Broca's area. For five other anatomical cortical parcellations in the left hemisphere, a similar trend was demonstrated. No significant relationships between OCs and lGI were found in the right hemisphere and there were no significant case-control differences in lGI. Conclusions The reduced cortical folding in the left pars triangularis, associated with OCs in both patients and control subjects suggests that the cortical effect of OCs is caused by factors shared by schizophrenia patients and healthy controls rather than factors related to schizophrenia alon
Implications of Pseudospin Symmetry on Relativistic Magnetic Properties and Gamow - Teller Transitions in Nuclei
Recently it has been shown that pseudospin symmetry has its origins in a
relativistic symmetry of the Dirac Hamiltonian. Using this symmetry we relate
single - nucleon relativistic magnetic moments of states in a pseudospin
doublet to the relativistic magnetic dipole transitions between the states in
the doublet, and we relate single - nucleon relativistic Gamow - Teller
transitions within states in the doublet. We apply these relationships to the
Gamow - Teller transitions from to its mirror nucleus .Comment: 17 pages, 2 figures, to be published in PRC. Slightly revised text
with one reference adde
Nuclear medium modifications of the NN interaction via quasielastic () and () scattering
Within the relativistic PWIA, spin observables have been recalculated for
quasielastic () and () reactions on a Ca
target. The incident proton energy ranges from 135 to 300 MeV while the
transferred momentum is kept fixed at 1.97 fm^{-1}. In the present
calculations, new Horowitz-Love--Franey relativistic NN amplitudes have been
generated in order to yield improved and more quantitative spin observable
values than before. The sensitivities of the various spin observables to the NN
interaction parameters, such as (1) the presence of the surrounding nuclear
medium, (2) a pseudoscalar versus a pseudovector interaction term, and (3)
exchange effects, point to spin observables which should preferably be measured
at certain laboratory proton energies, in order to test current nuclear models.
This study also shows that nuclear medium effects become more important at
lower proton energies ( 200 MeV). A comparison to the limited available
data indicates that the relativistic parametrization of the NN scattering
amplitudes in terms of only the five Fermi invariants (the SVPAT form) is
questionable.Comment: 10 pages, 6 Postscript figures, uses psfig.sty and article.sty,
submitted to Phys. Rev.
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