Holography of 3d Flat Cosmological Horizons

We provide a first derivation of the Bekenstein-Hawking entropy of 3d flat cosmological horizons in terms of the counting of states in a dual field theory. These horizons appear in the shifted-boost orbifold of R^{1,2}, the flat limit of non-extremal rotating BTZ black holes. These 3d geometries carry non-zero charges under the asymptotic symmetry algebra of R^{1,2}, the 3d Bondi-Metzner-Sachs (BMS3) algebra. The dual theory has the symmetries of the 2d Galilean Conformal Algebra, a contraction of two copies of the Virasoro algebra, which is isomorphic to BMS3. We study flat holography as a limit of AdS3/CFT2 to semi-classically compute the density of states in the dual, exactly reproducing the bulk entropy in the limit of large charges. Our flat horizons, remnants of the BTZ inner horizons also satisfy a first law of thermodynamics. We comment on how the dual theory reproduces the bulk first law and how cosmological bulk excitations are matched with boundary quantum numbers.Comment: 5 pages; v2: Typos corrected, references update

Split tolerance in horse: importance in the immune balance at the materno-fetal interface

La gestación induce un estado de tolerancia dividida. En esta situación la hembra gestante, aunque es capaz de inducir respuesta inmunológica frente los antígenos fetales, es tolerante a esos mismos antígenos en el útero grávido. El útero grávido es un “sitio inmunológicamente privilegiado” en el que existe una barrera física más o menos inaccesible para el sistema inmunitario materno y una inmunomodulación maternal en la interfase, fundamentales para el establecimiento del equilibrio inmunitario que asegure la supervivencia del feto en dicho ambiente. En este trabajo resaltaremos la aportación del équido en la comprensión de los mecanismos del equilibrio inmunitario en la gestación, ya que es el ejemplo más claro de tolerancia dividida. Se analiza tanto el tipo de placenta epiteliocorial equina y su paralelismo con la humana, como la inmunomodulación existente en la interfase en la que intervienen: hormonas secretadas por células del endometrio materno y del trofoblasto fetal; citoquinas adecuadas para el establecimiento de un microambiente tolerante; células presentadoras de antígeno con comportamiento diferente al usual y por último, la inhibición e inducción de apoptosis en linfocitos T; así como la importante presencia de linfocitos T reguladores TregFoxP3+.Pregnancy induces a state of split tolerance, a situation where although a pregnant female is capable of developing an immune response to fetal antigens, it´s tolerant to those antigens in the pregnant uterus. The pregnant uterus is an “immunological privileged site” where there is a physical barrier more or less inaccessible for the maternal immune system and a maternal immune-modulation at the interface, fundamental for the establishment of the immune balance that must ensure the survival of the fetus in the uterine environment. In this review we highlight the contribution of the horse in the understanding of the pregnancy immune balance mechanisms, because it is the best example of split tolerance. It is analyzed both equine epitheliocorial placenta and it´s parallelism with human placenta, and the immune-modulation at the interface in which are involved: endometrial and trophoblast secreted hormones; cytokines appropriate for the establishment of the tolerant microenvironment; antigen presenting cells with an unusual behavior; T lymphocytes inhibited and induced to apoptosis; and the important presence of T regulatory lymphocytes TregFoxP3+

A chiral qbarqbarqq nonet?

We point out that meson spectrum indicates the existence of a degenerate chiral nonet in the energy region around 1.4 GeV with a slightly inverted spectrum with respect to a qq nonet. Based on this observation, the approximately linear rising of the mass of a hadron with the number of constituent quarks, and the existence of a cuasidegenerate pseudoscalar nonet, we conjecture the existence of a tetraquark chiral nonet in this energy region with chiral symmetry implemented directly. We realize this idea in a chiral model and take into account the mixing of the tetraquark chiral nonet with a conventional qq nonet. We find that the mass spectrum of mesons below 1.5 GeV is consistent with this picture. In general, pseudoscalar states arise as mainly qq states but scalar states turn out to be strong admixtures of qq and tetraquark states.Comment: 8 pages, 3 figure

A chiral model for bar{q}q and bar{q}bar{q}qq$ mesons

We point out that the spectrum of pseudoscalar and scalar mesons exhibits a cuasi-degenerate chiral nonet in the energy region around 1.4 GeV whose scalar component has a slightly inverted spectrum. Based on the empirical linear rising of the mass of a hadron with the number of constituent quarks which yields a mass around $1.4$GeV for tetraquarks, we conjecture that this cuasi-chiral nonet arises from the mixing of a chiral nonet composed of tetraquarks with conventional bar{q}q states. We explore this possibility in the framework of a chiral model assuming a tetraquark chiral nonet around 1.4 GeV with chiral symmetry realized directly. We stress that U_{A}(1) transformations can distinguish bar{q}q from tetraquark states, although it cannot distinguish specific dynamics in the later case. We find that the measured spectrum is consistent with this picture. In general, pseudoscalar states arise as mainly bar{q}q states but scalar states turn out to be strong admixtures of bar{q}q and tetraquark states. We work out also the model predictions for the most relevant couplings and calculate explicitly the strong decays of the a_{0}(1450) and K_{0}^*(1430) mesons. From the comparison of some of the predicted couplings with the experimental ones we conclude that observable for the isovector and isospinor sectors are consistently described within the model. The proper description of couplings in the isoscalar sectors would require the introduction of glueball fields which is an important missing piece in the present model.Comment: 20 pages, 3 figure

Rates of SARS-COV-2 transmission and vaccination impact the fate of vaccine-resistant strains

Se considera que las vacunas son la mejor solución para controlar la actual pandemia por SARS-CoV-2. Sin embargo, la proliferación de cepas resistentes a las vacunas puede ser demasiado rápida para que su aplicación alivie la propagación de la pandemia, así como sus consecuencias económicas y sociales. Para cuantificar y caracterizar el riesgo de este escenario, utilizamos un modelo SIR con una dinámica estocástica para estudiar la probabilidad de aparición y transmisión de cepas resistentes a la vacuna. Usando parámetros que repliquen de manera realista la transmisión del SARS-CoV-2, modelizamos el patrón en forma de olas de la pandemia y consideramos el impacto que el ritmo de vacunación y la intensidad de las medidas de contención adoptadas tienen sobre la probabilidad de aparición de cepas resistentes a la vacuna. Como era de esperar, un ritmo rápido de vacunación disminuye la probabilidad de aparición de una cepa resistente a la vacuna. Sin embargo, aunque en principio pueda parecer contraintuitivo, cuando se produce una relajación de las restricciones en el momento en el que la mayoría de la población ya ha sido vacunada, la probabilidad de aparición de una cepa resistente a la vacuna aumenta considerablemente. En consecuencia, un período de contención estricta de la transmisión cerca del final de la campaña de vacunación puede reducir sustancialmente la probabilidad del establecimiento de cepas resistentes a la vacuna. Estos resultados, por tanto, sugieren la conveniencia de mantener las medidas y los protocolos de prevención durante toda la duración de la campaña de vacunación.Vaccines are thought to be the best available solution for controlling the ongoing SARS-CoV-2 pandemic. However, the emergence of vaccine-resistant strains may come too rapidly for current vaccine developments to alleviate the health, economic and social consequences of the pandemic. To quantify and characterize the risk of such a scenario, we created a SIR-derived model with initial stochastic dynamics of the vaccine-resistant strain to study the probability of its emergence and establishment. Using parameters realistically resembling SARS-CoV-2 transmission, we model a wave-like pattern of the pandemic and consider the impact of the rate of vaccination and the strength of non-pharmaceutical intervention measures on the probability of emergence of a resistant strain. As expected, we found that a fast rate of vaccination decreases the probability of emergence of a resistant strain. Counterintuitively, when a relaxation of non-pharmaceutical interventions happened at a time when most individuals of the population have already been vaccinated the probability of emergence of a resistant strain was greatly increased. Consequently, we show that a period of transmission reduction close to the end of the vaccination campaign can substantially reduce the probability of resistant strain establishment. These results, therefore, suggest the convenience of maintaining non-pharmaceutical interventions and prevention protocols throughout the entire vaccination period

Agroforestry Systems in Cuba: Some Aspects of Animal Production

The silvopastoral systems, that nowadays constitute scientific achievements of the Grasses and Forages Research Station Indio Hatuey , have been developed from the results of investigations that were carried out since the 1980s, to improve the productivity of natural pastures through the introduction of valuable herbaceous species and tree legumes. Those investigations also determined the essential elements of pasture management such as the optimal stocking rates for low input systems and suitable methods of grazing to obtain sustainability of grasslands

Robust Allocation of Funds for Nonstructural Flood Risk Mitigation in Coastal Louisiana

Coastal Louisiana is a critical economic, ecological and cultural asset, acting as a major hub for waterborne commerce, fisheries, and the petrochemical industry, and also as one of the world’s unique wetlands. Unfortunately, this rich environment is in great danger from the threat of hurricanes and storm surge flooding. Direct economic losses are estimated to average $2.7 billion per year under current conditions, and this could increase to$12 billion a year, or more, within 50 years if nothing is done. To prevent this catastrophe, Louisiana has developed a Comprehensive Master Plan for a Sustainable Coast, which plans to spend $50 billion, over the next 50 years, between structural (e.g., levees, floodwalls) and nonstructural (e.g., elevating houses, floodproofing) protection measures, and coastal restoration projects, to reduce flood risk and reduce land loss. However, the state is still in the process of developing a strategy for nonstructural risk mitigation and to define what mitigation standards should be set in different parts of the coast. Therefore, this project utilizes the risk model currently used to assess flood risk in coastal Louisiana to evaluate the impact of different potential nonstructural strategies on risk reduction, accounting for both equity and economic considerations. We estimate the risk reduction and other impacts achieved by each strategy and evaluate how much they vary over a wide range of uncertain future scenarios. We intend to identify a robust strategy for allocating the state’s$6 billion budget for nonstructural risk mitigation that will improve upon the current strategy recommended in the coastal Master Plan

Sub-seasonal and mesoscale variability of oceanic circulation at key 'choke' points: an example from the Western Mediterranean

Trabajo presentado en la EGU General Assemby 2014, celebrada del 27 de abril al 2 de mayo de 2014 en Viena (Austria)In order to detect long-term climatic change and to better constrain our modelling of ocean circulation it is increasingly important to understand sub-seasonal variability in this circulation. Monitoring the weekly to monthly variability of ocean currents and associated mesoscale instabilities, then placing this within the context of, and modifying, the seasonal to interannual circulation models is key. SOCIB (the Balearic Islands Coastal Ocean Observing and Forecasting System) has undertaken the monthly monitoring of ocean currents in the Ibiza Channel, a key 80 km ‘choke’ point in the Western Mediterranean basin-scale circulation, using gliders. Here, as in other locations in the global ocean, high frequency variability in the system is observed, in conjunction with a seasonal variability in the main thermohaline circulation. Now, with three years of semi-continuous glider data and 16 years of seasonal ships CTD data, we have greater insight into the high frequency processes that modify and govern the large basin-scale flow variability at this ‘choke’ point and thus better understand the important north/south exchanges of Atlantic (fresher and warmer) and Mediterranean (more saline and colder) watermasses and associated dynamical effectsPeer reviewe