The State of the Circumstellar Medium Surrounding Gamma-Ray Burst Sources and its Effect on the Afterglow Appearance

We present a numerical investigation of the contribution of the presupernova ejecta of Wolf-Rayet stars to the environment surrounding gamma-ray bursts (GRBs), and describe how this external matter can affect the observable afterglow characteristics. An implicit hydrodynamic calculation for massive stellar evolution is used here to provide the inner boundary conditions for an explicit hydrodynamical code to model the circumstellar gas dynamics. The resulting properties of the circumstellar medium are then used to calculate the deceleration of a relativistic, gas-dynamic jet and the corresponding afterglow light curve produced as the shock wave propagates through the shocked-wind medium. We find that variations in the stellar wind drive instabilities that may produce radial filaments in the shocked-wind region. These comet-like tails of clumps could give rise to strong temporal variations in the early afterglow lightcurve. Afterglows may be expected to differ widely among themselves, depending on the angular anisotropy of the jet and the properties of the stellar progenitor; a wide diversity of behaviors may be the rule, rather than the exception.Comment: 17 pages, 7 figures, ApJ in pres

Travel diaries as a source for creative constructions of thepast and the present: The Edward Bliss EmersonCaribbean diary (1831-1832)

The panelists will describe their particular encounters with Edward B. Emerson‟s travel diary, emphasizing their approaches to analyzing its content. They will describe the resources and techniques they employed to expand and contextualize Edward‟s account. They will offer the audience a truly interdisciplinary and creative interpretation of Edward‟s diary that could serve as an example of how to approach other travel diaries. Its diversity of subject and tone will be addressed by a group of scholars from different backgrounds. Collectively, the panelists represent 15 disciplines that provide different viewpoints in the analysis

Transcriptome Metabolic Characterization of Tuber borchii SP1—A New Spanish Strain for In Vitro Studies of the Bianchetto Truffle

Truffles are ascomycete hypogeous fungi belonging to the Tuberaceae family of the Pezizales order that grow in ectomycorrhizal symbiosis with tree roots, and they are known for their peculiar aromas and flavors. The axenic culture of truffle mycelium is problematic because it is not possible in many cases, and the growth rate is meager when it is possible. This limitation has prompted searching and characterizing new strains that can be handled in laboratory conditions for basic and applied studies. In this work, a new strain of Tuber borchii (strain SP1) was isolated and cultured, and its transcriptome was analyzed under different in vitro culture conditions. The results showed that the highest growth of T. borchii SP1 was obtained using maltose-enriched cultures made with soft-agar and in static submerged cultures made at 22 °C. We analyzed the transcriptome of this strain cultured in different media to establish a framework for future comparative studies, paying particular attention to the central metabolic pathways, principal secondary metabolite gene clusters, and the genes involved in producing volatile aromatic compounds (VOCs). The results showed a transcription signal for around 80% of the annotated genes. In contrast, most of the transcription effort was concentrated on a limited number of genes (20% of genes account for 80% of the transcription), and the transcription profile of the central metabolism genes was similar in the different conditions analyzed. The gene expression profile suggests that T. borchii uses fermentative rather than respiratory metabolism in these cultures, even in aerobic conditions. Finally, there was a reduced expression of genes belonging to secondary metabolite clusters, whereas there was a significative transcription of those involved in producing volatile aromatic compounds

The distribution of potential West Nile virus vectors, Culex pipiens pipiens and Culex pipiens quinquefasciatus (Diptera: Culicidae), in Mexico City

<p>Abstract</p> <p>Background</p> <p><it>Culex </it>spp. mosquitoes are considered to be the most important vectors of West Nile virus (WNV) detected in at least 34 species of mosquitoes in the United States. In North America, <it>Culex pipiens pipiens, Culex pipiens quinquefasciatus</it>, and <it>Culex tarsalis </it>are all competent vectors of WNV, which is considered to be enzootic in the United States and has also been detected in equines and birds in many states of Mexico and in humans in Nuevo Leon. There is potential for WNV to be introduced into Mexico City by various means including infected mosquitoes on airplanes, migrating birds, ground transportation and infected humans. Little is known of the geographic distribution of <it>Culex pipiens </it>complex mosquitoes and hybrids in Mexico City. <it>Culex pipiens pipiens </it>preferentially feed on avian hosts; <it>Culex pipiens quinquefasciatus </it>have historically been considered to prefer mammalian hosts; and hybrids of these two species could theoretically serve as bridge vectors to transmit WNV from avian hosts to humans and other mammalian hosts. In order to address the potential of WNV being introduced into Mexico City, we have determined the identity and spatial distribution of <it>Culex pipiens </it>complex mosquitoes and their hybrids.</p> <p>Results</p> <p>Mosquito larvae collected from 103 sites throughout Mexico City during 2004-2005 were identified as <it>Culex, Culiseta </it>or <it>Ochlerotatus </it>by morphological analysis. Within the genus <it>Culex</it>, specimens were further identified as <it>Culex tarsalis </it>or as belonging to the <it>Culex pipiens </it>complex. Members of the <it>Culex pipiens </it>complex were separated by measuring the ratio of the dorsal and ventral arms (DV/D ratio) of the male genitalia and also by using diagnostic primers designed for the <it>Ace.2 </it>gene. <it>Culex pipiens quinquefasciatus </it>was the most abundant form collected.</p> <p>Conclusions</p> <p>Important WNV vectors species, <it>Cx. p. pipiens</it>, <it>Cx. p. quinquefasciatus </it>and <it>Cx. tarsalis</it>, are all present in Mexico City. Hybrids of <it>Cx. p. pipiens </it>and <it>Cx. p. quinquefasciatus </it>were also collected and identified. The presence and abundance of these WNV competent vectors is a cause for concern. Understanding the distribution of these vectors can help improve viral surveillance activities and mosquito control efforts in Mexico City.</p

Fusarium Mycotoxins and Metabolites that Modulate Their Production

The genus Fusarium is a group of fungi producing several types of toxins with toxicological effect in both humans and animals. Such fungi are commonly found in soils so it can contaminate various types of crops, preferably cereals, leading to significant economic losses. Relative humidity, storage temperature and various handling in cereales increase the possibility of contamination by Fusarium toxins. Cereals naturally have secondary metabolites that may help attenuate contamination by these toxins, but it is necessary to know strategies and mechanisms that generate inactivation mycotoxins. This chapter reviews relevant information about cereal mycotoxin contamination, as well as the production of cereal secondary metabolites as a strategy to reduce the possibility of mycotoxin contamination

On the nature of long-range contributions to pair interactions between charged colloids in two dimensions

We perform a detailed analysis of solutions of the inverse problem applied to experimentally measured two-dimensional radial distribution functions for highly charged latex dispersions. The experiments are carried out at high colloidal densities and under low-salt conditions. At the highest studied densities, the extracted effective pair potentials contain long-range attractive part. At the same time, we find that for the best distribution functions available the range of stability of the solutions is limited by the nearest neighbour distance between the colloidal particles. Moreover, the measured pair distribution functions can be explained by purely repulsive pair potentials contained in the stable part of the solution.Comment: 6 pages, 5 figure

MINERvA neutrino detector response measured with test beam data

The MINERvA collaboration operated a scaled-down replica of the solid scintillator tracking and sampling calorimeter regions of the MINERvA detector in a hadron test beam at the Fermilab Test Beam Facility. This article reports measurements with samples of protons, pions, and electrons from 0.35 to 2.0 GeV/c momentum. The calorimetric response to protons, pions, and electrons are obtained from these data. A measurement of the parameter in Birks' law and an estimate of the tracking efficiency are extracted from the proton sample. Overall the data are well described by a Geant4-based Monte Carlo simulation of the detector and particle interactions with agreements better than 4%, though some features of the data are not precisely modeled. These measurements are used to tune the MINERvA detector simulation and evaluate systematic uncertainties in support of the MINERvA neutrino cross section measurement program.Comment: as accepted by NIM

Analysis of the Zonula occludens Toxin Found in the Genome of the Chilean Non-toxigenic Vibrio parahaemolyticus Strain PMC53.7

Indexación: Scopus.Vibrio parahaemolyticus non-toxigenic strains are responsible for about 10% of acute gastroenteritis associated with this species, suggesting they harbor unique virulence factors. Zonula occludens toxin (Zot), firstly described in Vibrio cholerae, is a secreted toxin that increases intestinal permeability. Recently, we identified Zot-encoding genes in the genomes of highly cytotoxic Chilean V. parahaemolyticus strains, including the non-toxigenic clinical strain PMC53.7. To gain insights into a possible role of Zot in V. parahaemolyticus, we analyzed whether it could be responsible for cytotoxicity. However, we observed a barely positive correlation between Caco-2 cell membrane damage and Zot mRNA expression during PMC53.7 infection and non-cytotoxicity induction in response to purified PMC53.7-Zot. Unusually, we observed a particular actin disturbance on cells infected with PMC53.7. Based on this observation, we decided to compare the sequence of PMC53.7-Zot with Zot of human pathogenic species such as V. cholerae, Campylobacter concisus, Neisseria meningitidis, and other V. parahaemolyticus strains, using computational tools. The PMC53.7-Zot was compared with other toxins and identified as an endotoxin with conserved motifs in the N-terminus and a variable C-terminal region and without FCIGRL peptide. Notably, the C-terminal diversity among Zots meant that not all of them could be identified as toxins. Structurally, PMC53.7-Zot was modeled as a transmembrane protein. Our results suggested that it has partial 3D structure similarity with V. cholerae-Zot. Probably, the PMC53.7-Zot would affect the actin cytoskeletal, but, in the absence of FCIGRL, the mechanisms of actions must be elucidated. © Copyright © 2020 Pérez-Reytor, Pavón, Lopez-Joven, Ramírez-Araya, Peña-Varas, Plaza, Alegría-Arcos, Corsini, Jaña, Pavez, del Pozo, Bastías, Blondel, Ramírez and García.https://www.frontiersin.org/articles/10.3389/fcimb.2020.00482/ful

Vector field as a quintessence partner

We derive generic equations for a vector field driving the evolution of flat homogeneous isotropic universe and give a comparison with a scalar filed dynamics in the cosmology. Two exact solutions are shown as examples, which can serve to describe an inflation and a slow falling down of dynamical ``cosmological constant'' like it is given by the scalar quintessence. An attractive feature of vector field description is a generation of ``induced mass'' proportional to a Hubble constant, which results in a dynamical suppression of actual cosmological constant during the evolution.Comment: 14 pages, LaTeX file, iopart class, discussion extended, reference adde

ALMA Observations of Asteroid 3 Juno at 60 Kilometer Resolution

We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum images of the asteroid 3 Juno obtained with an angular resolution of 0.042 arcseconds (60 km at 1.97 AU). The data were obtained over a single 4.4 hr interval, which covers 60% of the 7.2 hr rotation period, approximately centered on local transit. A sequence of ten consecutive images reveals continuous changes in the asteroid's profile and apparent shape, in good agreement with the sky projection of the three-dimensional model of the Database of Asteroid Models from Inversion Techniques. We measure a geometric mean diameter of 259pm4 km, in good agreement with past estimates from a variety of techniques and wavelengths. Due to the viewing angle and inclination of the rotational pole, the southern hemisphere dominates all of the images. The median peak brightness temperature is 215pm13 K, while the median over the whole surface is 197pm15 K. With the unprecedented resolution of ALMA, we find that the brightness temperature varies across the surface with higher values correlated to the subsolar point and afternoon areas, and lower values beyond the evening terminator. The dominance of the subsolar point is accentuated in the final four images, suggesting a reduction in the thermal inertia of the regolith at the corresponding longitudes, which are possibly correlated to the location of the putative large impact crater. These results demonstrate ALMA's potential to resolve thermal emission from the surface of main belt asteroids, and to measure accurately their position, geometric shape, rotational period, and soil characteristics.Comment: 8 pages, 3 figures, 2 tables, accepted for publication in the Astrophysical Journal Letter