Time-dependent toroidal compactification proposals and the Bianchi type I model: classical and quantum solutions

In this work we construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. We also find that the presence of extra dimensions in this model can accelerate the isotropization process depending on the momenta moduli values. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology.Comment: LaTeX source, 16 pages, Modified title and additional references. Advances in High Energy Physics, 201

Microplastics in the Antarctic marine system: An emerging area of research

It was thought that the Southern Ocean was relatively free of microplastic contamination; however, recent studies and citizen science projects in the Southern Ocean have reported microplastics in deep-sea sediments and surface waters. Here we reviewed available information on microplastics (including macroplastics as a source of microplastics) in the Southern Ocean. We estimated primary microplastic concentrations from personal care products and laundry, and identified potential sources and routes of transmission into the region. Estimates showed the levels of microplastic pollution released into the region from ships and scientific research stations were likely to be negligible at the scale of the Southern Ocean, but may be significant on a local scale. This was demonstrated by the detection of the first microplastics in shallow benthic sediments close to a number of research stations on King George Island. Furthermore, our predictions of primary microplastic concentrations from local sources were five orders of magnitude lower than levels reported in published sampling surveys (assuming an even dispersal at the ocean surface). Sea surface transfer from lower latitudes may contribute, at an as yet unknown level, to Southern Ocean plastic concentrations. Acknowledging the lack of data describing microplastic origins, concentrations, distribution and impacts in the Southern Ocean, we highlight the urgent need for research, and call for routine, standardised monitoring in the Antarctic marine system

Modelo bayesiano nutricional para el pronóstico de la morbilidad en neonatos

This research aimed to formulate a Bayesian model based on the Naive Bayes algorithm, to predict morbidity in neonates in a case study of pregnant mothers in Metropolitan Lima. The study uses mathematical algorithms for the exploitation of information in prevention of possible health-related problems. 13 predictive nutritional variables proposed by Krauss were raised. The model consists first of all, in the collection of the nutritional information in a controlled way of the pregnant women involved, then, the information is analyzed to determine the relationship of the most influential variables for the model, then the Bayesian model of acyclic characteristic was constructed and directed composed of nodes and edges, because the variables directly affected to the morbidity of the neonate are known and finally the model affected by the statistical results of the nutritional variables is validated, as part of the process of formulating the model and by experts judgment in the topic. The results conclude that the predictive variables that directly influence are: breads, sugars, oils, fats and salt; and conversely: fruits, water, vegetables and vegetables; the model also predicts the morbidity of the newborn with a probability of 92% and an error of 8.0%.Se ha diseñado esta investigación con el objetivo de formular un modelo bayesiano nutricional para el pronóstico de la morbilidad en neonatos de madres gestantes de Lima Metropolitana. Este modelo está basado en algoritmos de Naive Bayes que consiste en clasificar el aprendizaje automático con variables predictoras independientes entre si.Asimismo, se ha aplicado algoritmos matemáticos para la exploración de la información respecto a la prevención de posibles problemas relacionados con la salud. Se utilizó 13 variables nutricionales predictoras propuesta por Krauss.La investigación consitió en primer lugar, en la recopilación de la información nutricional de manera controlada de las gestantes involucradas, luego, se analizó la información para determinar la relación de las variables más influyentes , posteriormente se elaboró el modelo bayesiano de característica acíclica y dirigida compuesta por nodos y aristas, porque se conoce que las variables afectan directamente a la morbilidad del neonato y finalmente se validó el modelo considerando los resultados estadísticos de las variables nutricionales, como parte del proceso de formulacióndel modelo y por juicio de expertos en el tema. En conclusión, las variables predictoras que influyen directamente son: panes, azúcares, aceites, grasas y sal; e indirectamente: frutas, agua, verduras y hortalizas; asimismo el modelo pronostica la morbilidad del neonato con una probabilidad del 92% y un error del 8.0 %

On general flux backgrounds with localized sources

We derive new consistency conditions for string compactifications with generic fluxes (RR, NSNS, geometrical) and localized sources (D-branes, NS-branes, KK-monopoles). The constraints are all related by string dualities and share a common origin in M-theory. We also find new sources of instabilities. We discuss the importance of these conditions for the consistency of the effective action and for the study of interpolating solutions between vacua.Comment: 29 pages, 2 figures, v2: published versio

Axions and the Strong CP Problem

Current upper bounds of the neutron electric dipole moment constrain the physically observable quantum chromodynamic (QCD) vacuum angle $|\bar\theta| \lesssim 10^{-11}$. Since QCD explains vast experimental data from the 100 MeV scale to the TeV scale, it is better to explain this smallness of $|\bar\theta|$ in the QCD framework, which is the strong \Ca\Pa problem. Now, there exist two plausible solutions to this problem, one of which leads to the existence of the very light axion. The axion decay constant window, $10^9\ {\gev}\lesssim F_a\lesssim 10^{12} \gev$for a${\cal O}(1)$initial misalignment angle$\theta_1$, has been obtained by astrophysical and cosmological data. For$F_a\gtrsim 10^{12}$GeV with$\theta_1<{\cal O}(1)$, axions may constitute a significant fraction of dark matter of the universe. The supersymmetrized axion solution of the strong \Ca\Pa problem introduces its superpartner the axino which might have affected the universe evolution significantly. Here, we review the very light axion (theory, supersymmetrization, and models) with the most recent particle, astrophysical and cosmological data, and present prospects for its discovery.Comment: 47 pages with 32 figure

Reconfigurable Network for Quantum Transport Simulation

In 1981, Richard Feynman discussed the possibility of performing quantum mechanical simulations of nature. Ever since, there has been an enormous interest in using quantum mechanical systems, known as quantum simulators, to mimic specific physical systems. Hitherto, these controllable systems have been implemented on different platforms that rely on trapped atoms, superconducting circuits and photonic arrays. Unfortunately, these platforms do not seem to satisfy, at once, all desirable features of an universal simulator, namely long-lived coherence, full control of system parameters, low losses, and scalability. Here, we overcome these challenges and demonstrate robust simulation of quantum transport phenomena using a state-of-art reconfigurable electronic network. To test the robustness and precise control of our platform, we explore the ballistic propagation of a single-excitation wavefunction in an ordered lattice, and its localization due to disorder. We implement the Su-Schrieffer-Heeger model to directly observe the emergence of topologically-protected one-dimensional edge states. Furthermore, we present the realization of the so-called perfect transport protocol, a key milestone for the development of scalable quantum computing and communication. Finally, we show the first simulation of the exciton dynamics in the B800 ring of the purple bacteria LH2 complex. The high fidelity of our simulations together with the low decoherence of our device make it a robust, versatile and promising platform for the simulation of quantum transport phenomena

Dirichlet Branes on Orientifolds

We consider the classification of BPS and non-BPS D-branes in orientifold models. In particular we construct all stable BPS and non-BPS D-branes in the Gimon-Polchinski (GP) and Dabholkar-Park-Blum-Zaffaroni (DPBZ) orientifolds and determine their stability regions in moduli space as well as decay products. We find several kinds of integrally and torsion charged non-BPS D-branes. Certain of these are found to have projective representations of the orientifold $\times$ GSO group on the Chan-Paton factors. It is found that the GP orientifold is not described by equivariant orthogonal K-theory as may have been at first expected. Instead a twisted version of this K-theory is expected to be relevant.Comment: 33 pages, LaTeX, 5 figures. v2 typos corrected, references included, (4,s)-branes re-examine

Final results of the EDELWEISS-II WIMP search using a 4-kg array of cryogenic germanium detectors with interleaved electrodes

The EDELWEISS-II collaboration has completed a direct search for WIMP dark matter with an array of ten 400-g cryogenic germanium detectors in operation at the Laboratoire Souterrain de Modane. The combined use of thermal phonon sensors and charge collection electrodes with an interleaved geometry enables the efficient rejection of gamma-induced radioactivity as well as near-surface interactions. A total effective exposure of 384 kg.d has been achieved, mostly coming from fourteen months of continuous operation. Five nuclear recoil candidates are observed above 20 keV, while the estimated background is 3.0 events. The result is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 4.4x10^-8 pb is excluded at 90%CL for a WIMP mass of 85 GeV. New constraints are also set on models where the WIMP-nucleon scattering is inelastic.Comment: 23 pages, 5 figures; matches published versio