Supersymmetry and Rb_{b} in the light of LEP 1.5

We re-examine the possible magnitude of the supersymmetric contribution to R_b\equiv\Gamma(Z^0\to\bar b b)/\Gamma(Z^0\to{\rm all}) in the light of the constraints imposed by the absence of light charginos at LEP~1.5, implementing also other available phenomenological constraints. We find the supersymmetric contribution to be R^{\rm susy}_b < 0.0017, and discuss the extent to which this upper bound could be strengthened by future constraints on the chargino and top-squark masses. Such values of R^{\rm susy}_b tend to disfavor a supersymmetry explanation of the apparent R_b discrepancy

Analysis of modular CMA-ES on strict box-constrained problems in the SBOX-COST benchmarking suite

Box-constraints limit the domain of decision variables and are common in real-world optimization problems, for example, due to physical, natural or spatial limitations. Consequently, solutions violating a box-constraint may not be evaluable. This assumption is often ignored in the literature, e.g., existing benchmark suites, such as COCO/BBOB, allow the optimizer to evaluate infeasible solutions. This paper presents an initial study on the strict-box-constrained benchmarking suite (SBOX-COST), which is a variant of the well-known BBOB benchmark suite that enforces box-constraints by returning an invalid evaluation value for infeasible solutions. Specifically, we want to understand the performance difference between BBOB and SBOX-COST as a function of two initialization methods and six constraint-handling strategies all tested with modular CMA-ES. We find that, contrary to what may be expected, handling box-constraints by saturation is not always better than not handling them at all. However, across all BBOB functions, saturation is better than not handling, and the difference increases with the number of dimensions. Strictly enforcing box-constraints also has a clear negative effect on the performance of classical CMA-ES (with uniform random initialization and no constraint handling), especially as problem dimensionality increases

Comparación de las escalas APACHE II y BISAP en el pronóstico de pancreatitis aguda en un hospital del Perú: Comparison of the APACHE II and BISAP scales in the prognosis of acute pancreatitis in a hospital of Peru

Introduction:&nbsp; Acute pancreatitis continue to be a disease with significant morbidity and mortality. It is diagnosed by clinical criteria and the inflammatory process can lead to organ failure. The objective of the present study was to compare the scales of APACHE II and BISAP in the development of organic failure in acute pancreatitis from a public hospital of Perú. Pacients and methods: An analytical from validation of a diagnostic test. There were clinical records of patients who were hospitalized with the diagnosis of acute pancreatitis in the Internal Medicine service and the Intensive Care Unit were evaluated. The APACHE II and BISAP scales were applied and the ROC curve, the sensitivity, the specificity, the positive and negative predictive value was calculated for each one. SPSSv23 was used for statistical analysis. Results: Were reviewed 146 stories that met the inclusion criteria. An area under the curve of 0.957 was obtained for BISAP and 0.996 for APACHE II; with a sensitivity and specificity for APACHE II of 83% and &nbsp;99%,&nbsp; for BISAP of 66% and 99%. In addition, the positive and negative predictive value for APACHE II is 83% and 99% , &nbsp;for BISAP 80% and 98% . Conclusion: The APACHE II scale was superior for detecting organ failure. It was determined that both scales have high specificity, however the APACHE II scale presented a higher sensitivity than the BISAP scale.Introducción: La pancreatitis aguda continúa siendo una enfermedad con morbilidad y mortalidad significativas. Se diagnostica mediante criterios clínicos y el proceso inflamatorio puede llegar hasta una falla de órganos. El objetivo del presente estudio fue comparar las escalas de APACHE II y BISAP en el desarrollo de falla orgánica en pacientes con pancreatitis aguda de un hospital público del Perú. Pacientes y métodos: Se realizó un estudio de validación de prueba diagnóstica. Se evaluaron las historias clínicas de pacientes que estuvieron hospitalizados con el diagnostico de pancreatitis aguda en el servicio de Medicina Interna y la Unidad de Cuidados Intensivos. Se aplicó las escalas APACHE II y BISAP, se calculó la curva ROC, sensibilidad, especificidad, valor predictivo positivo y negativo. Para el análisis estadístico se utilizó el SPSSv23. Resultados: Se evaluaron 146 historias de pacientes que cumplían con los criterios de inclusión. Se obtuvo un área bajo la curva de 0.957 para BISAP y 0.996 para APACHE II; con una sensibilidad y especificidad para APACHE II de 83% y 99%,&nbsp; para BISAP de 66% y 99%. El valor predictivo positivo y negativo para APACHE II es 83% and 99% y para BISAP 80% y 98%. Conclusiones: La escala de APACHE II fue superior para detectar falla de órganos. Se determinó que ambas escalas poseen alta especificidad, siendo mayor la sensibilidad en la escala BISAP

Excited states of exciton-polariton condensates in 2D and 1D harmonic traps

We present a theoretical description of Bogolyubov-type excitations of exciton-polariton Bose-Einstein condensates (BECs) in semiconductor microcavities. For a typical two-dimensional (2D) BEC we focus on two limiting cases, the weak-and strong-coupling regimes, where a perturbation theory and the Thomas-Fermi approximation, respectively, are valid. We calculate integrated scattering intensity spectra for probing the collective excitations of the condensate in both considered limits. Moreover, in relation to recent experiments on optical modulation allowing localization of condensates in a trap with well-controlled shape and dimensions, we study the quasi-one-dimensional (1D) motion of the BEC inmicrowires and report the corresponding Bogolyubov excitation spectrum. We show that in the 1D case the characteristic polariton-polariton interaction constant is expressed as g(1) = 3 lambda N/(2L(y)) (lambda is the 2D polariton-polariton interaction parameter in the cavity, N the number of the particles, and L-y the wire cavity width). We reveal some interesting features for 2D and 1D Bogolyubov spectra for both repulsive (lambda > 0) and attractive (lambda < 0) interactions.Fundação para a Ciência e a Tecnologia (FCT) - Portuguese Foundation for Science and Technology Grants: PTDC-FIS-113199-2009, PEst-C/FIS/UI0607/2013CNPq, FAPESP, BrazilRussian Ministry of Education and Science 11.G34.31.006

Formal analytical solutions for the Gross-Pitaevskii equation

Considering the Gross-Pitaevskii integral equation we are able to formally obtain an analytical solution for the order parameter $\Phi (x)$ and for the chemical potential $\mu$ as a function of a unique dimensionless non-linear parameter $\Lambda$. We report solutions for different range of values for the repulsive and the attractive non-linear interactions in the condensate. Also, we study a bright soliton-like variational solution for the order parameter for positive and negative values of $\Lambda$. Introducing an accumulated error function we have performed a quantitative analysis with other well-established methods as: the perturbation theory, the Thomas-Fermi approximation, and the numerical solution. This study gives a very useful result establishing the universal range of the $\Lambda$-values where each solution can be easily implemented. In particular we showed that for $\Lambda <-9$, the bright soliton function reproduces the exact solution of GPE wave function.Comment: 8 figure

Topology driven g-factor tuning in type-II quantum dots

We investigate how the voltage control of the exciton lateral dipole moment induces a transition from singly to doubly connected topology in type-II In As/Ga Asx Sb1−x quantum dots. The latter causes visible Aharonov-Bohm oscillations and a change of the exciton g factor, which are modulated by the applied bias. The results are explained in the frame of realistic →k⋅ →p and effective Hamiltonian models and could open a venue for new spin quantum memories beyond the In As/Ga As realm

The metallicity properties of zCOSMOS galaxies at 0.2<z<0.8

We study the metallicity properties of galaxies in the zCOSMOS sample between 0.2<z<0.8. At z<0.46, where Ha and [NII] are detected, we find the same dependence of metallicity on stellar mass and Star Formation Rate (SFR), the Fundamental Metallicity Relation, found by Mannucci et al. (2010) in SDSS galaxies on a similar redshift range. We extend this relation to higher redshift, 0.49<z<0.8 where the R23 metallicity index can be measured in our data, finding no evidence for evolution, and a metallicity scatter around the relation of about 0.16 dex. This result confirms, with a much higher level of significance with respect to previous works, the absence of evolution of the FMR during the last half of cosmic history.Comment: 9 pages, 7 figures, accepted for publication in MNRA

Electrochemical sulfidation of WS2 nanoarrays:strong dependence of hydrogen evolution activity on transition metal sulfide surface composition

The activity of transition metal sulfides for the hydrogen evolution reaction (HER) can be increased by sulfur-enrichment of active metal-sulfide sites. In this report, we investigate the electrochemical sulfidation of atmospherically aged WS2 nanoarrays with respect to enhancing HER activity. In contrast to MoS2, it is found that sulfidation diminishes HER activity. Electrochemical and XPS experiments suggest the involvement of insoluble tungsten oxides in the altered HER and electron transfer properties. This demonstrates the strong dependence of the transition metal dichalcogenide (TMD) composition with the successful sulfur incorporation and subsequent HER activity

Groups without cultured representatives dominate eukaryotic picophytoplankton in the oligotrophic South East Pacific Ocean

Background: Photosynthetic picoeukaryotes (PPE) with a cell size less than 3 µm play a critical role in oceanic primary production. In recent years, the composition of marine picoeukaryote communities has been intensively investigated by molecular approaches, but their photosynthetic fraction remains poorly characterized. This is largely because the classical approach that relies on constructing 18S rRNA gene clone libraries from filtered seawater samples using universal eukaryotic primers is heavily biased toward heterotrophs, especially alveolates and stramenopiles, despite the fact that autotrophic cells in general outnumber heterotrophic ones in the euphotic zone. Methodology/Principal Findings: In order to better assess the composition of the eukaryotic picophytoplankton in the South East Pacific Ocean, encompassing the most oligotrophic oceanic regions on earth, we used a novel approach based on flow cytometry sorting followed by construction of 18S rRNA gene clone libraries. This strategy dramatically increased the recovery of sequences from putative autotrophic groups. The composition of the PPE community appeared highly variable both vertically down the water column and horizontally across the South East Pacific Ocean. In the central gyre, uncultivated lineages dominated: a recently discovered clade of Prasinophyceae (IX), clades of marine Chrysophyceae and Haptophyta, the latter division containing a potentially new class besides Prymnesiophyceae and Pavlophyceae. In contrast, on the edge of the gyre and in the coastal Chilean upwelling, groups with cultivated representatives (Prasinophyceae clade VII and Mamiellales) dominated. Conclusions/Significance: Our data demonstrate that a very large fraction of the eukaryotic picophytoplankton still escapes cultivation. The use of flow cytometry sorting should prove very useful to better characterize specific plankton populations by molecular approaches such as gene cloning or metagenomics, and also to obtain into culture strains representative of these novel groups