Decays Z' -> \gamma\gamma\gamma{} and Z -> \gamma\gamma\gamma{} in the minimal 331 model

The possibility of a significant effect of exotic particles on the Z'->\gamma\gamma\gamma{} and Z->\gamma\gamma\gamma{} decays is investigated in the context of the minimal 331 model. This model, which is based in the SU_C(3)xSU_L(3)xU_X(1) gauge group, predicts the existence of many exotic charged particles that can significantly enhance the decay widths. It is found that the standard model prediction for the Z->\gamma\gamma\gamma{} decay remains essentially unchanged, as the new physics effects quickly decouples. On the other hand, it is found that the contributions of the new exotic quarks and gauge bosons predicted by this model lead to a branching fraction for the Z'->\gamma\gamma\gamma{} decay of about 10^(-6), which is about three orders of magnitude larger than that of the Z->\gamma\gamma\gamma{} decay.Comment: 20 pages and 20 figure

Evaluation of macroseismic intensities in Mexico from recent earthquakes using ¿Sintió un sismo? (Did you feel it?)

Macroseismic investigations with data collected through online surveys has acquired relevance in recent years. Its easy access and low cost allow assessments of the severity of an earthquake from its effects as observed by the population. Furthermore, it is possible to generate attenuation curves for a particular region, visualize the condition of the buildings from a zip code-averaged distribution map, and estimate possible site effects. In regions without a good coverage of seismic networks, macroseismic intensities have proved to be a substitute for instrumental data. In this paper intensity maps for four earthquakes in different regions of Mexico are presented, based on data from the database of ¿Sintió un sismo? program, an online survey implemented in 2014. Less attenuation was found in areas considered tectonically stable than in those considered as active regions. RESUMEN Las investigaciones macrosísmicas utilizando datos recolectados a partir de encuestas en línea han adquirido un gran auge en los últimos años. Su fácil acceso y bajo costo permiten realizar evaluaciones de la severidad del sismo a partir de los efectos observados por la población. Además es posible generar curvas de atenuación para una región en particular, visualizar el estado de las construcciones y los posibles efectos de sitio. En regiones donde no se tiene una buena cobertura de redes sísmicas, las intensidades macrosísmicas han demostrado ser un gran sustituto de datos instrumentales. En este trabajo se presentan mapas de intensidades macrosísmicas para cuatro sismos en distintos puntos del país. Los datos se obtuvieron de la base de datos del programa ¿Sintió un sismo?, una encuesta en línea implementada en el 2014. Encontramos que la atenuación es menor en zonas consideradas tectónicamente estables que en regiones activas

In situ surface coverage analysis of RuO₂-catalysed HCl oxidation reveals the entropic origin of compensation in heterogeneous catalysis

In heterogeneous catalysis, rates with Arrhenius-like temperature dependence are ubiquitous. Compensation phenomena, which arise from the linear correlation between the apparent activation energy and the logarithm of the apparent pre-exponential factor, are also common. Here, we study the origin of compensation and find a similar dependence on the rate-limiting surface coverage term for each Arrhenius parameter. This result is derived from an experimental determination of the surface coverage of oxygen and chlorine species using temporal analysis of products and prompt gamma activation analysis during HCl oxidation to Cl2 on a RuO2 catalyst. It is also substantiated by theory. We find that compensation phenomena appear when the effect on the apparent activation energy caused by changes in surface coverage is balanced out by the entropic configuration contributions of the surface. This result sets a new paradigm in understanding the interplay of compensation effects with the kinetics of heterogeneously catalysed processes

Bird Behaviour during Prey-Predator Interaction in a Tropical Forest in México

Birds emit alarm calls, considered as honest signals, because they communicate the presence of a predator or potential threat. We evaluated behavioural events of birds responding to vocal and visual stimuli of a nocturnal predator (black-and-white owl Ciccaba nigrolineata) and a diurnal predator (collared forest falcon Micrastur semitorquatus). We analysed variations in behavioural events seasonally (reproductive and nonbreeding) and by bird size, as well as their relationship with the vegetation structure and landscape. The study was performed during the breeding (March-May) and non-breeding seasons (February, June and July) of 2016 in Chiapas, Mexico. We used four transects with different vegetation types and land uses. The most frequent behavioural response by birds to the vocal stimuli of the black-and-white owl and the collared forest-falcons was vocal, during the breeding season, and small species responded the most to the stimuli (p = 0.008) and (p < 0.015), respectively. We identified two vegetation and two landscape variables associated in 36% of probability for the prey to respond to black-and-white owl vocal stimuli, three variables of vegetation and one of the landscape in 37% for the collared forest-falcon stimuli. Potential prey animals modify the behaviour, which allows them to detect, evade or confront a predator

Comparison of two-step transient evoked otoacoustic emissions (TEOAE) and automated auditory brainstem response (AABR) for universal newborn hearing screening programs

Producción CientíficaBoth transitory auditory otoemissions (TEOAE) and automated auditory brainstem responses (AABR) are considered adequate methods for universal hearing screening. The goal of this study was to compare the results obtained with each device, applying the same screening procedure. MATERIALS AND METHODS:From 2001 to 2003, all the newborns in our health area (2454 infants) were evaluated with TEOAE (ILO92, otodynamics) and all those born from 2004 to 2006 (3117) were evaluated with AABR (AccuScreen, Fischer-Zoth). The population studied included all well newborns and those admitted to neonatal intensive care units (NICU). The first screening was normally undertaken with well babies during the first 48h of life, before hospital discharge. Infants referred from this first step underwent a second screening after hospital discharge, before they were a month old. RESULTS:The results from each study group were compared and analyzed for significant differences. TEOAE screening yielded 10.2% fail results from the first screening step; AABR gave 2.6%. In the second screening step, 2% of the newborns screened with TEOAE were referred, whereas 0.32% of those screened with AABR were referred. These differences are statistically significant. CONCLUSIONS:Although AABR screening tests involve a slightly higher cost in time and money than TEOAE, the results obtained compensate this difference. AABR gives fewer false positives and a lower referral rate; the percent of infants lost during follow-up is consequently smaller. Therefore, in our environment, universal newborn auditory screening with AABR is more effective than that with TEOAE

Graphene Materials to Remove Organic Pollutants and Heavy Metals from Water: Photocatalysis and Adsorption

Since graphene was isolated from graphite, different researches have been developed around it. The versatility of graphene properties and their derivates, such as graphene oxide or doped and functionalized graphene materials have expanded the possible applications of these nanostructures. The areas studied of graphene include the following: nanocomposites, drug delivery, transistors, quantum dots, optoelectronic, storage energy, sensors, catalyst support, supercapacitors, among others. However, other important field of these materials is their applications in environment, mainly in the removal of pollutants in water. In this context, there are two possible alternatives to use graphene materials in water purification: photocatalysis and adsorption. In the first case, the key is related to the bandgap and semiconductors properties of these materials, also the versatility of different graphene structures after the oxidation or functionalization, play an important role to get different arrangements useful in photocatalysis and avoid recombination, one of the problems of typical semiconductors photocatalysts. In the second case, surface area and useful chemical groups in carbon material give different options to produce efficient adsorbents depending on different synthesis conditions. Thus, this book chapter covers a review of the photocatalytic activity of graphene materials with emphasis in the removal of organic pollutants and heavy metals from water, in the next topics: graphene-based semiconductor photocatalyst and graphene oxide as photocatalyst. On the other hand, the chapter also discusses the research related to the removal of organic compounds and heavy metals using graphene materials as adsorbents, the topics in this second part are as follows: graphene and graphene oxide as adsorbent of heavy metals from water, graphene, and graphene oxide as adsorbent of organic pollutants from water, functionalized graphene materials as adsorbent of water pollutants, carbon nanomaterials vs. graphene as adsorbents. Therefore, the book chapter presents a review and the discussion of the keys that play an important role in the advances in the research of graphene materials as photocatalysts. In addition, the isotherms and kinetic that produce these materials as adsorbents are also reviewed and discussed, because adsorption process in these materials is important to remove pollutants from water, but also for adsorption is a first step to achieve photocatalyst. The future of this topic in graphene materials is also analyzed