Collisional parton energy loss in a finite size QCD medium revisited: Off mass-shell effects

We study the collisional energy loss mechanism for particles produced off mass-shell in a finite size QCD medium. The off mass-shell effects introduced are to consider particles produced in wave packets instead of plane waves and the length scale associated to an in-medium particles' life-time. We show that these effects reduce the energy loss as compared to the case when the particles are described as freely propagating from the source. The reduction of the energy loss is stronger as this scale becomes of the order or smaller than the medium size. We discuss possible consequences of the result on the description of the energy loss process in the parton recombination scenario.Comment: 9 pages, 4 figures. Enlarged discussion. References added. Version to appear in Phys. Rev.

On the critical end point in a two-flavor linear sigma model coupled to quarks

We use the linear sigma model coupled to quarks to explore the location of the phase transition lines in the QCD phase diagram from the point of view of chiral symmetry restoration at high temperature and baryon chemical potential. We compute analytically the effective potential in the high- and low-temperature approximations up to sixth order, including the contribution of the ring diagrams to account for the plasma screening properties. We determine the model parameters, namely, the couplings and mass-parameter, from conditions valid at the first order phase transition at vanishing temperature and, using the Hagedorn limiting temperature concept applied to finite baryon density, for a critical baryochemical potential of order of the nucleon mass. We show that when using the set of parameters thus determined, the second order phase transition line (our proxy for the crossover transition) that starts at finite temperature and zero baryon chemical potential converges to the line of first order phase transitions that starts at zero temperature and finite baryon chemical potential to determine the critical end point to lie in the region 5.02<\mu_B^{\mbox{CEP}}/T_c<5.18, 0.14, where $T_c$ is the critical transition temperature at zero baryon chemical potential.Comment: 11 pages, 3 figures, discussion extended, explicit calculations included in appendices and version accepted for publication in EPJ

Chemical and thermal impacts of sprite streamers in the Earth's mesosphere

A one-dimensional self-consistent model has been developed to study the chemical and thermal effects of a single sprite streamer in the Earth's mesosphere. We have used sprite streamer profiles with three different driving current durations (5 ms, 50 ms, and 100 ms) between 50 and 80 km of altitude and considering a kinetic scheme of air with more than 90 chemical species. Our model predicts strong increases in practically all the concentrations of the species studied at the moment of the streamer head passage. Moreover, their densities remain high during the streamer afterglow phase. The concentration of electrons can reach values of up to 10 cm in the three cases analyzed. The model also predicts an important enhancement, of several orders of magnitude above ambient values, of nitrogen oxides and several metastables species. On the other hand, we found that the 4.26 μm IR emission brightness of CO can reach 10 GR at low altitudes (< 65 km) for the cases of intermediate (50 ms) and long (100 ms) driving currents. These results suggest the possibility of detecting sprite IR emissions from space with the appropriate instrumentation. Finally, we found that the thermal impact of sprites in the Earth's mesosphere is proportional to the driving current duration. This produces variations of more than 40 K (in the extreme case of a 100 ms driving current) at low altitudes (< 55 km) and at about 10 s after the streamer head. Key Points Chemical and thermal impacts of sprites in the mesosphere are calculated The calculated concentration of electrons exhibits a significant enhancement The model predicts an increase in the gas temperature at low altitudes.©2016. American Geophysical Union. All Rights Reserved.This work was supported by the Spanish Ministry of Economy and Competitiveness, MINECO, under projects AYA2011-29936-C05-02 and ESP2013-48032-C5-5-R and by the Junta de Andalucia, Proyecto de Excelencia, FQM-5965. F.C.P.R. acknowledges MINECO for the FPI grant BES-2010-042367. A.L. was supported by a Ramon y Cajal contract, code RYC-2011-07801Peer Reviewe

A two dimensional fluid model for TCP/AQM analysis

This work proposes a new mathematical model for the TCP/AQM system that aims to improve the accuracy of existing fluid models, especially with respect to the sequential events that occur in the network. The analysis is based on the consideration of two time bases, one at the queue's router level and the other at the congestion window level, which leads to the derivation of a new nonlinear two-dimensional fluid model for Internet congestion control. To avoid the difficult task of assessing stability of a 2D nonlinear dynamic model, we perform a local stability analysis of a 2D linear TCP AQM model. By constructing a new two dimensional second order Bessel Legendre Lyapunov functional, new matrix inequalities are derived to evaluate the stability of the 0-input system and to synthesize a feedback controller. Finally, two Internet traffic scenarios, with state space matrices for replicability, are presented, demonstrating the validity of the theoretical results.Comment: Active queue management, network assisted congestion control, TCP/AQM, 2D time delay systems, Roesser model, 2D second order bessel Legendre, Lyapuno

Fungal Endophytes of Populus trichocarpa Alter Host Phenotype, Gene Expression, and Rhizobiome Composition.

Mortierella and Ilyonectria genera include common species of soil fungi that are frequently detected as root endophytes in many plants, including Populus spp. However, the ecological roles of these and other endophytic fungi with respect to plant growth and function are still not well understood. The functional ecology of two key taxa from the P. trichocarpa rhizobiome, M. elongata PMI93 and I. europaea PMI82, was studied by coupling forest soil bioassays with environmental metatranscriptomics. Using soil bioassay experiments amended with fungal inoculants, M. elongata was observed to promote the growth of P. trichocarpa. This response was cultivar independent. In contrast, I. europaea had no visible effect on P. trichocarpa growth. Metatranscriptomic studies revealed that these fungi impacted rhizophytic and endophytic activities in P. trichocarpa and induced shifts in soil and root microbial communities. Differential expression of core genes in P. trichocarpa roots was observed in response to both fungal species. Expression of P. trichocarpa genes for lipid signaling and nutrient uptake were upregulated, and expression of genes associated with gibberellin signaling were altered in plants inoculated with M. elongata, but not I. europaea. Upregulation of genes for growth promotion, downregulation of genes for several leucine-rich repeat receptor kinases, and alteration of expression of genes associated with plant defense responses (e.g., jasmonic acid, salicylic acid, and ethylene signal pathways) also suggest that M. elongata manipulates plant defenses while promoting plant growth

Factors associated with post-traumatic stress disorder symptoms in the post-quarantine context of the COVID-19 pandemic in Peruvian medical students

Background: In March 2020, the Peruvian state introduced quarantine as a measure to control the spread of SARS-CoV-2. It has been suggested that being in quarantine is associated with the development of symptoms of Post-traumatic Stress Disorder (PTSD). The present study aims to explore the factors associated with the development of PTSD in a post-quarantine context due to COVID-19 in medical students. Objectives: To evaluate the factors associated with the development of post-quarantine PTSD symptoms in medical students from a Peruvian university. Methods: Analytical cross-sectional study. The objective will be developed after the lifting of the quarantine in Peru. Medical students enrolled during the 2020-01 academic cycle of the Peruvian University of Applied Sciences will be included. To collect the outcome variable (PTSD), the Impact of Event Scale - Revised (IES-R) will be used. The associated factors will be collected through a form that will be validated by experts and piloted in the field. The crude and adjusted coefficients will be calculated, using bivariate and multivariate linear regression models, respectively. We will use the “manual forward selection” technique to obtain a final model with minimally sufficient fit. After each model comparison and decision, multicollinearity will be evaluated with the variance inflation factor and matrix of independent variables. Results: Not having health insurance, having relatives or close friends who contracted the disease and having a lower family income are factors associated with PTSD in the post-quarantine context of the COVID-19 pandemic in medical students at a Peruvian university. Conclusions: Clinical evaluation is important for medical students with a high probability of having PTSD symptoms. We recommend conducting a longitudinal study to identify causality and other unstudied factors related to PTSD.Revisión por pare

Coupling between atmospheric layers in gaseous giant planets due to lightning-generated electromagnetic pulses

©2014. American Geophysical Union. All Rights Reserved. Atmospheric electricity has been detected in all gaseous giants of our solar system and is therefore likely present also in extrasolar planets. Building upon measurements from Saturn and Jupiter, we investigate how the electromagnetic pulse emitted by a lightning stroke affects upper layers of a gaseous giant. This effect is probably significantly stronger than that on Earth. We find that electrically active storms may create a localized but long-lasting layer of enhanced ionization of up to 103 cm-3 free electrons below the ionosphere, thus extending the ionosphere downward. We also estimate that the electromagnetic pulse transports 107 J to 1010 J toward the ionosphere. There emissions of light of up to 108 J would create a transient luminous event analogous to a terrestrial >elve.> Key Points The EMP from lightning has a stronger effect in gaseous planets than on EarthThe EMP creates ionization and light upper atmosphere of Saturn and JupiterLight emitted by the EMP is one tenth of the light from the lightning strokeThis work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under projects AYA2011-29936-C05-02 and ESP2013-48032-C5-5-R and by the Junta de Andalucia, Proyecto de Excelencia FQM-5965. D. D. and Y.Y. were supported by the Israeli Ministry of Science, scholarship in Memory of Col. Ilan Ramon and by the Israeli Science Foundation grant 117/09.Peer Reviewe