3,392 research outputs found
Magnetized strange quark matter and magnetized strange quark stars
Strange quark matter could be found in the core of neutron stars or forming
strange quark stars. As is well known, these astrophysical objects are endowed
with strong magnetic fields which affect the microscopic properties of matter
and modify the macroscopic properties of the system. In this paper we study the
role of a strong magnetic field in the thermodynamical properties of a
magnetized degenerate strange quark gas, taking into account beta-equilibrium
and charge neutrality. Quarks and electrons interact with the magnetic field
via their electric charges and anomalous magnetic moments. In contrast to the
magnetic field value of 10^19 G, obtained when anomalous magnetic moments are
not taken into account, we find the upper bound B < 8.6 x 10^17 G, for the
stability of the system. A phase transition could be hidden for fields greater
than this value.Comment: 9 pages, 9 figure
Flavored axions and the flavor problem
A Peccei-Quinn~(PQ) symmetry is proposed, in order to generate in the
Standard Model~(SM) quark sector a realistic mass matrix ansatz with five
texture-zeros. Limiting our analysis to Hermitian mass matrices we show that
this requires a minimum of 4 Higgs doublets. This model allows assigning values
close to 1 for several Yukawa couplings, giving insight into the origin of the
mass scales in the SM. Since the PQ charges are non-universal the model
features Flavor-Changing Neutral Currents~(FCNC) at the tree level. From the
analytical expressions for the FCNC we report the allowed region in the
parameter space obtained from the measurements of branching ratios of
semileptonic meson decays.Comment: 20 pages, 2 figure
Southern Annular Mode-like changes in southwestern Patagonia at centennial timescales over the last three millennia
Late twentieth-century instrumental records reveal a persistent southward shift of the Southern Westerly Winds during austral summer and autumn associated with a positive trend of the Southern Annular Mode (SAM) and contemporaneous with glacial recession, steady increases in atmospheric temperatures and CO2 concentrations at a global scale. However, despite the clear importance of the SAM in the modern/future climate, very little is known regarding its behaviour during pre-Industrial times. Here we present a stratigraphic record from Lago Cipreses (51S), southwestern Patagonia, that reveals recurrent B200-year long dry/warm phases over the last three millennia, which we interpret as positive SAM-like states. These correspond in timing with the Industrial revolution, the Mediaeval Climate Anomaly, the Roman and Late Bronze Age Warm Periods and alternate with cold/wet multicentennial phases in European palaeoclimate records. We conclude that SAM-like changes at centennial timescales in southwestern Patagonia represent in-phase interhemispheric coupling of palaeoclimate over the last 3,000 years through atmospheric teleconnections.Fil: Moreno, Patricio. Universidad de Chile; ChileFil: Vilanova, Isabel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Villa Martinez, R.. Universidad de Chile; ChileFil: Garreaud, R. D.. Universidad de Chile; ChileFil: Rojas, M.. Universidad de Chile; ChileFil: De Pol Holz, R.. Universidad de Chile; Chil
Robust outlier detection in high-density surface electromyographic signals
Conf Proc IEEE Eng Med Biol Soc. 2010;2010:4850-3. PubMed PMID: 2109664
Linear response theory of activated surface diffusion with interacting adsorbates
Activated surface diffusion with interacting adsorbates is analyzed within
the Linear Response Theory framework. The so-called interacting single
adsorbate model is justified by means of a two-bath model, where one harmonic
bath takes into account the interaction with the surface phonons, while the
other one describes the surface coverage, this leading to defining a
collisional friction. Here, the corresponding theory is applied to simple
systems, such as diffusion on flat surfaces and the frustrated translational
motion in a harmonic potential. Classical and quantum closed formulas are
obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on
the corrugated Cu(001) surface, is presented and discussed within the classical
context as well as within the framework of Kramer's theory. Quantum corrections
to the classical results are also analyzed and discussed.Comment: 40 pages, 4 figure
Phosphate levels as a possible state marker in panic disorder: preliminary study of a feasible laboratory measure for routine clinical practice.
Low serum phosphate level is considered one of the metabolic adaptations to the respiratory alkalosis induced by hyperventilation associated with panic disorder. The aim of this study was to assess phosphatemia as a possible state marker for panic disorder.
Methods
Sixteen panic disorder patients underwent clinical assessment with a semi-structured interview, a set of rating scales and the self-rated State and Trait Anxiety Inventory (STAI), as well as extraction of venous blood samples at baseline and after 12 weeks of pharmacological treatment. Ten healthy volunteers of similar sex, age and educational level filled out the STAI and gave blood samples at baseline and 12 weeks later.
Results
The median (25th–75th percentiles) of phosphate levels (mg/dl) was 2.68 (2.22–3.18) among patients and 4.13 (3.74–4.70) among healthy volunteers respectively (P < 0.001). Seven (44%) patients and no healthy volunteers presented low serum phosphate (<2.50 mg/dl) at baseline; this patient abnormality was corrected in all cases after successful treatment. At baseline, the age-adjusted correlation between phosphate levels and state-anxiety was −0.66 (P < 0.001) among all 26 participants and −0.51 (P = 0.05) among the 16 panic disorder patients.
Conclusions
Measurement of phosphate levels could be easily introduced into clinical practice as a possible marker for chronic hyperventilation in panic disorder, although further investigations with larger sample sizes are necessary to characterize panic disorder patients with low versus normal phosphate levels.The study received institutional support from the Institute of Neurosciences of the University of Granada.
The authors had access to all data from the study, both what is reported and what is unreported, and complete freedom to direct its analysis and reporting, without influence, editorial direction, or censorship from the institution supporting the study
Nitric oxide modulates interleukin-2-induced proliferation in CTLL-2 cells
The role of the L-arginine–nitric oxide metabolic pathway was explored for interleukin-2-induced proliferation in the cytotoxic T lymphocyte clone CTLL-2. Specific inhibition of nitric oxide synthase significantly diminished, in a concentration-dependent manner, 3H-thymidine uptake of CTLL-2 cells in response to different concentrations of interleukin 2. Withdrawal of L-arginine from culture medium resulted as potent as the higher inhibition obtained when blocking nitric oxide synthase with L-arginine analogues. Furthermore, intermedial concentrations of Larginine and exogenous nitric oxide donors were found for achieving optimal IL2-induced proliferation of CTLL-2. These findings prompted us to suggest that intra- and/or inter-cellular nitric oxide signalling may contribute to the modulation of the IL2 mitogenic effect upon cytotoxic T lymphocytes
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