Magneto-elastic oscillations of neutron stars: exploring different magnetic field configurations

We study magneto-elastic oscillations of highly magnetized neutron stars (magnetars) which have been proposed as an explanation for the quasi-periodic oscillations (QPOs) appearing in the decaying tail of the giant flares of soft gamma-ray repeaters (SGRs). We extend previous studies by investigating various magnetic field configurations, computing the Alfv\'en spectrum in each case and performing magneto-elastic simulations for a selected number of models. By identifying the observed frequencies of 28 Hz (SGR 1900+14) and 30 Hz (SGR 1806-20) with the fundamental Alfv\'en QPOs, we estimate the required surface magnetic field strength. For the magnetic field configurations investigated (dipole-like poloidal, mixed toroidal-poloidal with a dipole-like poloidal component and a toroidal field confined to the region of field lines closing inside the star, and for poloidal fields with an additional quadrupole-like component) the estimated dipole spin-down magnetic fields are between 8x10^14 G and 4x10^15 G, in broad agreement with spin-down estimates for the SGR sources producing giant flares. A number of these models exhibit a rich Alfv\'en continuum revealing new turning points which can produce QPOs. This allows one to explain most of the observed QPO frequencies as associated with magneto-elastic QPOs. In particular, we construct a possible configuration with two turning points in the spectrum which can explain all observed QPOs of SGR 1900+14. Finally, we find that magnetic field configurations which are entirely confined in the crust (if the core is assumed to be a type I superconductor) are not favoured, due to difficulties in explaining the lowest observed QPO frequencies (f<30 Hz).Comment: 21 pages, 16 figures, 6 tables, matched to version accepted by MNRAS with extended comparison/discussion to previous wor

Comparison of fiber effect on glycemic index and glycemic load in differents types of bread

Indexación: Scopus; Redalyc.Existen diversos alimentos que contienen como nutriente principal hidratos de carbono, destacando entre ellos el pan por su masivo consumo a nivel mundial. Numerosos estudios se han llevado a cabo con el fin de reducir su índice glicémico, sin embargo, aún existe controversia sobre la acción de la fibra dietética en la disminución del IG en este alimento. Este estudio determinó el efecto de la fibra dietética sobre el índice glicémico y carga glicémica en dos tipos de panes comerciales en 23 individuos sanos quienes consumieron aleatoriamente 3 diferentes productos, de 50 g de carbohidratos cada uno, durante 6 días: pan blanco (PH), pan integral (PF), y solución glucosada como producto de referencia (SG). Se midió glicemia en ayunas y post-prandial a los tiempos 15, 30, 45, 60, 90 y 120 min. La insulina fue medida en el minuto 0 y 120 min. El área bajo la curva de glicemia resultó más baja para ambos tipos de pan PH 13589 ±1557, PF 12005 ±1254 que para el producto de referencia SG 14089 ±1245. Los valores del índice glicémico PH 68,55 ±1,2 y PF 62,10 ±1,3 y carga glicémica PH 16,45 ±1,4 resultaron más bajos para el pan con mayor aporte de fibra 9,93 ± 1,1, sin diferencias en la concentración de insulina, sugiriendo que la cantidad de carbohidratos y tipo de fibra contenidos en el pan integral, pueden considerarse factores intrínsecos en su composición nutricional, capaces de afectar la respuesta glicémica post- ingesta de estos productos en individuos sanos.There are several foods that contain carbohydrates as the main nutrient, being one of the most important the bread for its massive worldwide consumption. Numerous studies have been done in order to reduce its glycemic index, however there is still controversy about the action of dietary fiber in the decrease of GI in this product. In this study, it was determined the effect of dietetic fiber on glycemic index and glycemic load in two types of commercial breads in 23 healthy individuals who randomly consumed 3 different products during 6 days of 50g of carbohydrates each: white bread (PH), whole wheat bread (PE) and glucose solution as reference product (SG). Fasting and postprandial glycemia was measured at times 15, 30, 45, 60, 90 and 120 minutes. Insuline was measured at 0 min and 120 min. The area under de glycemia curve was lower for both bread types PH 13589 ±1557, PF 12005 ±1254 than for the reference product SG 14089 ±1245. The values of the glycemic index PH 68,55 ±1,2 and PF 62,01 ±1,3 and glycemic load PH 16.45 ±1,4 were lower for bread with more amount fiber 9,93 ± 1,1, with no difference in insulin concentration, suggesting that the amount of carbohydrates and fiber type contained in whole wheat bread can be considered intrinsic factors in bread composition, affecting the post-intake glycemic response of this type of products in healthy individuals.http://www.redalyc.org/articulo.oa?id=5594990800

Effect of oat β-glucan on glycemic index and glycemic load of a nutritional supplement sweetened with sucralose in healthy adults: A randomized clinical trial

Indexación: Scopus; RedalycLas propiedades hipoglicemiantes del β-glucano de avena son de interés para la industria alimentaria y el área clínica, por sus potenciales beneficios sobre la salud al disminuir la respuesta glicémica, el nivel sérico de lipoproteínas de baja densidad y el índice glicémico de los alimentos. Existen suplementos nutricionales específicos para diabéticos edulcorados con sucralosa cuyo índice glicémico y carga glicémica aún no han sido establecidos. El efecto del β-glucano de avena sobre el índice glicémico y carga glicémica de un suplemento nutricional edulcorado con sucralosa, fue determinado en 13 adultos sanos (6 hombres y 7 mujeres), quienes consumieron aleatoriamente 4 alimentos en días distintos, de 50 g de carbohidratos cada uno: suplemento nutricional para diabéticos (FN), suplemento nutricional con β-glucano (FN- β), y como productos de referencia: solución glucosada (SG) y pan blanco (PB). Se midió glicemia en ayunas y post- prandial a los tiempos 15, 30, 45, 60, 90 y 120 min. El área bajo la curva de glicemia resultó más baja para ambas fórmulas (FN) 12697±993, (FN-β) 11584 ±1171, que para los productos de referencia:(SG) 13900±1245, y (PB) 13267 ± 1557. Los valores de índice glicémico (FN) 67,02 ± 5,69, así como la carga glicémica resultaron intermedios y más bajos para el suplemento con β-glucano incorporado (FN –β) 59,8 ± 6,2; sin diferencias en la concentración de insulina, sugiriendo que la adición del β-glucano derivado de la avena reduce la velocidad de absorción intestinal de la glucosa, efecto que podría estudiarse en diabéticos.The hypoglycemic properties of oat β-glucan is of interest for the food industry and clinical area, for potencial health benefits by reducing glycemic response, serum low-density lipoprotein cholesterol, and glycemic index of meals. There are specific nutritional supplements for diabetics sweetened with sucralose whose glycemic index and glycemic load has not been established. Effect of oat β-glucan on glycemic index and glycemic load of a nutritional supplement sweetened with sucralose in healthy adults was determined in 13 healthy subjects (6 men and 7 women) old that consumed randomly 4 meals of 50 g of carbohydrates each in different days: a nutritional supplement for diabetics (FN), the nutritional supplement with β-glucan incorporated (FN-β) and two reference food, glucose solution (SG) and white bread (PB). Fasting and postprandial glycemia was measured at times 15, 30, 45, 60, 90 and 120 min. The area under the glycemia curve was lower for both formulas (FN) 12697±993, (FN-β) 11584 ±1171 than for reference products (SG) 13900±1245, y (PB) 13267 ± 1557. The values of glycemic index (GI) (FN) 67, 02 ± 5,69 and glycemic load were intermediate and more lower for the supplement with β-glucan incorporated (FN –β) 59, 8 ± 6,2, with no difference of insulin concentration . Suggesting that the addition of oat-derived β-glucan reduces the rate of intestinal absorption of glucose. This effect should be studied in diabetic.http://www.redalyc.org/articulo.oa?id=5594990800

Mutational Analysis of Photosystem I of Synechocystis sp. PCC 6803: The Role of Four Conserved Aromatic Residues in the j-helix of PsaB

Photosystem I is the light-driven plastocyanin-ferredoxin oxidoreductase in the photosynthetic electron transfer of cyanobacteria and plants. Two histidyl residues in the symmetric transmembrane helices A-j and B-j provide ligands for the P700 chlorophyll molecules of the reaction center of photosystem I. To determine the role of conserved aromatic residues adjacent to the histidyl molecule in the helix of B-j, we generated six site-directed mutants of the psaB gene in Synechocystis sp. PCC 6803. Three mutant strains with W645C, W643C/A644I and S641C/V642I substitutions could grow photoautotrophically and showed no obvious reduction in the photosystem I activity. Kinetics of P700 re-reduction by plastocyanin remained unaltered in these mutants. In contrast, the strains with H651C/L652M, F649C/G650I and F647C substitutions could not grow under photoautotrophic conditions because those mutants had low photosystem I activity, possibly due to low levels of proteins. A procedure to select spontaneous revertants from the mutants that are incapable to photoautotrophic growth resulted in three revertants that were used in this study. The molecular analysis of the spontaneous revertants suggested that an aromatic residue at F647 and a small residue at G650 may be necessary for maintaining the structural integrity of photosystem I. The (P700+ - P700) steady-state absorption difference spectrum of the revertant F647Y has a ∼5 nm narrower peak than the recovered wild-type, suggesting that additional hydroxyl group of this revertant may participate in the interaction with the special pair while the photosystem I complexes of the F649C/G650T and H651Q mutants closely resemble the wild-type spectrum. The results presented here demonstrate that the highly conserved residues W645, W643 and F649 are not critical for maintaining the integrity and in mediating electron transport from plastocyanin to photosystem I. Our data suggest that an aromatic residue is required at position of 647 for structural integrity and/or function of photosystem I

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

Expansion of Signal Transduction Pathways in Fungi by Extensive Genome Duplication

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