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 Científicas 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

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

Enhanced optical properties of Cd–Mg-co-doped ZnO nanoparticles induced by low crystal structure distortion

The growth of CdxMg0.125-xZn0.875O nanoparticles with yellow-orange luminescence is achieved up to 2.5 at. % Cd via a modified sol–gel process. X-ray diffraction analysis confirmed that all the nanoparticles have the hexagonal wurtzite structure. It is found that Cd doping has a considerable effect on the crystal size, microstrain, band gap, and photoluminescence of the Mg0·125Zn0·875O structure, originating from a preferred crystallographic orientation along the (101) plane of the wurtzite structure. The shift and broadening of the E2(high) mode observed in the Raman spectra due to growth-induced strain corroborates the small distortion observed in the X-ray diffraction data. The optical band gap varies from 3.21 eV to 2.74 eV, being redshifted with increasing Cd concentration (from 0 at. % to 2.5 at. %). The photoluminescence obtained with an excitation wavelength of 325 nm has a broad yellow-orange emission peak at around 640 nm due to transitions related to oxygen vacancies and interstitial oxygen atoms. We located the yellow-orange emission in the chromaticity coordinate diagram in the 2683–2777 K colour temperature region, demonstrating that CdxMg0.125-xZnO0.875 nanoparticles have potential applications in white light-emitting diodes.publishe