208 research outputs found
Light bullets in Bessel optical lattices with spatially modulated nonlinearity
We address the stability of light bullets supported by Bessel optical lattices with out-of-phase modulation of the linear and nonlinear refractive indices. We show that spatial modulation of the nonlinearity significantly modifies the shapes and stability domains of the light bullets. The addressed bullets can be stable, provided that the peak intensity does not exceed a critical value. We show that the width of the stability domain in terms of the propagation constant may be controlled by varying the nonlinearity modulation depth. In particular, we show that the maximum energy of the stable bullets grows with increasing nonlinearity modulation depth.Peer ReviewedPostprint (published version
Growth hormone secretagogues exert differential effects on skeletal muscle calcium homeostasis in male rats depending on the peptidyl/non-peptidyl structure
TheorexigenicandanaboliceffectsinducedbyghrelinandthesyntheticGHsecretagogues(GHSs)
are thought to positively contribute to therapeutic approaches and the adjunct treatment of a
number of diseases associated with muscle wasting such as cachexia and sarcopenia. However,
manyquestionsaboutthepotentialutilityandsafetyofGHSsinboththerapyandskeletalmuscle
functionremainunanswered.Byusingfura-2cytofluorimetrictechnique,wedeterminedtheacute
effectsofghrelin,aswellasofpeptidylandnonpeptidylsyntheticGHSsoncalciumhomeostasis,
a critical biomarker of muscle function, in isolated tendon-to-tendon male rat skeletal muscle
fibers.ThesyntheticnonpeptidylGHSs,butnotpeptidylghrelinandhexarelin,wereabletosignificantlyincreaserestingcytosoliccalcium[Ca2]i.ThenonpeptidylGHS-induced[Ca2]
iincrease
was independent of GHS-receptor 1a but was antagonized by both thapsigargin/caffeine and
cyclosporineA,indicatingtheinvolvementofthesarcoplasmicreticulumandmitochondria.EvaluationoftheeffectsofapseudopeptidylGHSandanonpeptidylantagonistoftheGHS-receptor
1a together with a drug-modeling study suggest the conclusion that the lipophilic nonpeptidyl
structureofthetestedcompoundsisthekeychemicalfeaturecrucialfortheGHS-inducedcalcium
alterationsintheskeletalmuscle.Thus,syntheticGHSscanhavedifferenteffectsonskeletalmuscle
fibersdependingontheirmolecularstructures.Thecalciumhomeostasisdysregulationspecifically
induced by the nonpeptidyl GHSs used in this study could potentially counteract the beneficial
effects associated with these drugs in the treatment of muscle wasting of cachexia- or other
age-related disorders
A novel background reduction strategy for high level triggers and processing in gamma-ray Cherenkov detectors
Gamma ray astronomy is now at the leading edge for studies related both to
fundamental physics and astrophysics. The sensitivity of gamma detectors is
limited by the huge amount of background, constituted by hadronic cosmic rays
(typically two to three orders of magnitude more than the signal) and by the
accidental background in the detectors. By using the information on the
temporal evolution of the Cherenkov light, the background can be reduced. We
will present here the results obtained within the MAGIC experiment using a new
technique for the reduction of the background. Particle showers produced by
gamma rays show a different temporal distribution with respect to showers
produced by hadrons; the background due to accidental counts shows no
dependence on time. Such novel strategy can increase the sensitivity of present
instruments.Comment: 4 pages, 3 figures, Proc. of the 9th Int. Syposium "Frontiers of
Fundamental and Computational Physics" (FFP9), (AIP, Melville, New York,
2008, in press
Black hole entropy in 3D gravity with torsion
The role of torsion in quantum three-dimensional gravity is investigated by
studying the partition function of the Euclidean theory in Riemann-Cartan
spacetime. The entropy of the black hole with torsion is found to differ from
the standard Bekenstein-Hawking result, but its form is in complete agreement
with the first law of black hole thermodynamics.Comment: 17 pages, RevTeX, minor revision
Does hypoglycemia following a glucose challenge test identify a high risk pregnancy?
<p>Abstract</p> <p>Objective</p> <p>An association between maternal hypoglycemia during pregnancy with fetal growth restriction and overall perinatal mortality has been reported. In a retrospective pilot study we found that hypoglycemia was linked with a greater number of special care/neonatal intensive care unit admissions and approached significance in the number of women who developed preeclampsia. That study was limited by its retrospective design, a narrow patient population and the inability to perform multivariate analysis because of the limitations in the data points collected. This study was undertaken to compare the perinatal outcome in pregnancies with hyoglycemia following a glucose challenge test (GCT) to pregnancies with a normal GCT.</p> <p>Methods</p> <p>Obstetric patients (not pre-gestational diabetics or gestational diabetes before 24 weeks were eligible. Women with a 1 hour glucose ≤ 88 mg/dL (4.8 m/mol) following a 50-gram oral GCT were matched with the next patient with a 1 hour glucose of 89–139 mg/dL. Pregnancy outcomes were evaluated.</p> <p>Results</p> <p>Over 22 months, 436 hypoglycemic patients and 434 normal subjects were identified. Hypoglycemia was increased in women < 25 (p = 0.003) and with pre-existing medical conditions (p < 0.001). Hypoglycemia was decreased if pre-pregnancy BMI ≥ 30 (p = 0.008).</p> <p>Preeclampsia/eclampsia was more common in hypoglycemic women. (OR = 3.13, 95% CI 1.51 – 6.51, p = 0.002) but not other intrapartum and perinatal outcomes.</p> <p>Conclusion</p> <p>Hypoglycemic patients are younger, have reduced pre-pregnancy weight, lower BMIs, and are more likely to develop preeclampsia than normoglycemic women.</p
Preventing Falls in Older Californians: State of the Art
In February 2003, the Foundation convened over 150 leaders in academic, legislative, community-based services, consumer advocates, aging network, housing, public health, public safety, and other leaders who worked for two days on a statewide blueprint on fall prevention.  In preparation for the convening, a Preconference White Paper was created and used to build the blueprint.  The California Blueprint describes state-of-the-art approaches to reducing the risks of falls, and the challenges to implementing fall prevention in California. One of the top recommendations from this blueprint was the creation of a coordination center that could serve as a statewide resource and lead efforts in fall prevention.  This recommendation eventually led to the creation of the Fall Prevention Center of Excellence (FPCE)
Neutrinos in a gravitational background: a test for the universality of the gravitational interaction
In this work we propose an extended formulation for the interaction between
neutrinos and gravitational fields. It is based on the parametrized
post-Newtonian aproach, and includes a violation of the universality of the
gravitational interaction which is non diagonal in the weak flavor space. We
find new effects that are not considered in the standard scenario for violation
of the equivalence principle. They are of the same order as the effects
produced by the Newtonian potential, but they are highly directional dependent
and could provide a very clean test of that violation. Phenomenological
consequences are briefly discussed.Comment: 18 pages, revtex, no figure
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