18,295 research outputs found
Magnetic Susceptibility of the Quark Condensate and Polarization from Chiral Models
We compute the magnetic susceptibility of the quark condensate and the
polarization of quarks at zero temperature and in a uniform magnetic
background. Our theoretical framework consists of two chiral models that allow
to treat self-consistently the spontaneous breaking of chiral symmetry: the
linear model coupled to quarks, dubbed quark-meson model, and the
Nambu-Jona-Lasinio model. We also perform analytic estimates of the same
quantities within the renormalized quark-meson model, both in the regimes of
weak and strong fields. Our numerical results are in agreement with the recent
literature; moreover, we confirm previous Lattice findings, related to the
saturation of the polarization at large fields.Comment: 13 pages, 4 figure
Therapy of Canine Hyperlipidemia with Bezafibrate.
BackgroundBezafibrate (BZF) is effective in the treatment of hypertriglyceridemia in human patients, but there are no data on its use in dogs.ObjectiveTo assess the safety of BZF in hyperlipidemic dogs and its efficacy in decreasing serum triglyceride (TG) and cholesterol (CHO) concentrations.AnimalsForty-six dogs, 26 females and 20 males, mean (±SD) age of 9 (±3) years, with TG ≥150 mg/dL (33 dogs also were hypercholesterolemic [>300 mg/dL]).MethodsProspective, uncontrolled clinical trial. Dogs were treated with bezafibrate once daily, using 200 mg tablets at a dosage of 4-10 mg/kg (depending on body weight). Serum TG and CHO concentrations and alanine aminotransferase (ALT) and creatine kinase (CK) activity before and after 30 days of treatment were compared.ResultsSixteen dogs (34.8%) had primary hyperlipidemia, and 30 dogs (65.2%) had secondary hyperlipidemia (including spontaneous hyperadrenocorticism [41.3%, n = 19/46], chronic treatment with glucocorticoids [10.8%, n = 5/46], and hypothyroidism [15.2%, n = 7/46]). After 30 days, serum TG concentration normalized (<150 mg/dL) in 42 dogs (91.3%) and CHO concentration normalized (<270 mg/dL) in 22 of 33 dogs (66.7%). There was no difference in baseline TG concentration between the primary and secondary hyperlipidemia subgroups, but the decrease in TG concentration after treatment was greater in the primary hyperlipidemia subgroup. No adverse effects were observed, but ALT activity decreased significantly after 30 days of treatment.Conclusions and clinical importanceOver 30 days, BZF was safe and effective in treatment of primary and secondary hyperlipidemia in dogs
Gravitino Dark Matter and Neutrino Masses in Partial Split Supersymmetry
Partial Split Supersymmetry with bilinear R-parity violation allows to
reproduce all neutrino mass and mixing parameters. The viable dark matter
candidate in this model is the gravitino. We study the hypothesis that both
possibilities are true: Partial Split Supersymmetry explains neutrino physics
and that dark matter is actually composed of gravitinos. Since the gravitino
has a small but non-zero decay probability, its decay products could be
observed in astrophysical experiments. Combining bounds from astrophysical
photon spectra with the bounds coming from the mass matrix in the neutrino
sector we derive a stringent upper limit for the allowed gravitino mass. This
mass limit is in good agreement with the results of direct dark matter
searches.Comment: 22 pages, 3 figure
Polynomial growth of volume of balls for zero-entropy geodesic systems
The aim of this paper is to state and prove polynomial analogues of the
classical Manning inequality relating the topological entropy of a geodesic
flow with the growth rate of the volume of balls in the universal covering. To
this aim we use two numerical conjugacy invariants, the {\em strong polynomial
entropy } and the {\em weak polynomial entropy }. Both are
infinite when the topological entropy is positive and they satisfy
. We first prove that the growth rate of the volume of
balls is bounded above by means of the strong polynomial entropy and we show
that for the flat torus this inequality becomes an equality. We then study the
explicit example of the torus of revolution for which we can give an exact
asymptotic equivalent of the growth rate of volume of balls, which we relate to
the weak polynomial entropy.Comment: 22 page
Chiral magnetic effect in the PNJL model
We study the two-flavor Nambu--Jona-Lasinio model with the Polyakov loop
(PNJL model) in the presence of a strong magnetic field and a chiral chemical
potential which mimics the effect of imbalanced chirality due to QCD
instanton and/or sphaleron transitions. Firstly we focus on the properties of
chiral symmetry breaking and deconfinement crossover under the strong magnetic
field. Then we discuss the role of on the phase structure. Finally the
chirality charge, electric current, and their susceptibility, which are
relevant to the Chiral Magnetic Effect, are computed in the model.Comment: Some reference added. Minor revisions. One figure added. To appear on
Phys. Rev.
Estimates of multipolar coefficients to search for cosmic ray anisotropies with non-uniform or partial sky coverage
We study the possibility to extract the multipolar moments of an underlying
distribution from a set of cosmic rays observed with non-uniform or even
partial sky coverage. We show that if the degree is assumed to be upper bounded
by , each multipolar moment can be recovered whatever the coverage, but with
a variance increasing exponentially with the bound if the coverage is zero
somewhere. Despite this limitation, we show the possibility to test predictions
of a model without any assumption on by building an estimate of the
covariance matrix seen through the exposure function.Comment: 20 pages, 8 figure
A Spitzer view of protoplanetary disks in the gamma Velorum cluster
We present new Spitzer Space Telescope observations of stars in the young ~5
Myr gamma Velorum stellar cluster. Combining optical and 2MASS photometry, we
have selected 579 stars as candidate members of the cluster. With the addition
of the Spitzer mid-infrared data, we have identified 5 debris disks around
A-type stars, and 5-6 debris disks around solar-type stars, indicating that the
strong radiation field in the cluster does not completely suppress the
production of planetesimals in the disks of cluster members. However, we find
some evidence that the frequency of circumstellar primordial disks is lower,
and the IR flux excesses are smaller than for disks around stellar populations
with similar ages. This could be evidence for a relatively fast dissipation of
circumstellar dust by the strong radiation field from the highest mass star(s)
in the cluster. Another possibility is that gamma Velorum stellar cluster is
slightly older than reported ages and the the low frequency of primordial disks
reflects the fast disk dissipation observed at ~5 Myr.Comment: Accepted for publication in the Astrophysical Journal: 32 pages; 11
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