The complex dust formation zone of the AGB star IRC+10216 probed with CARMA 0.25 arcsec angular resolution molecular observations

We present low spectral resolution molecular interferometric observations at 1.2 mm obtained with the Combined Array for Research in Millimetre-wave Astronomy (CARMA) towards the C-rich AGB star IRC+10216. We have mapped the emission of several lines of SiS, H13CN, SiO, and SiC2 in the ground and first excited vibrational states with a high angular resolution of 0.25 arcsec. These observations have allowed us to partially resolve the emission of the envelope at distances from the star <50 stellar radii (R*), where the stellar wind is mainly accelerated. The structure of the molecular emission has been modelled with a 3D radiation transfer code. The emission of line SiS(v=0,J=14-13) is best reproduced with a set of maser emitting arcs arranged between 5 and 20 R*. The abundance of H13CN with respect to H2 decreases from 8e-7 at 1-5 R* to 3e-7 at 20 R*. The SiO observations are explained with an abundance <2e-8 in the shell-like region between 1 and 5 R*. At this point, the SiO abundance sharply increases up to (2-3)e-7. The vibrational temperature of SiO increases by a factor of 2 due North-East between 20 and 50 R*. SiC2 is formed at the stellar surface with an abundance of 8e-7 decreasing down to 8e-8 at 20 R* probably due to depletion on to dust grains. Several asymmetries are found in the abundance distributions of H13CN, SiO, and SiC2 which define three remarkable directions (North-East, South-Southwest, and South-East) in the explored region of the envelope. There are some differences between the red- and blue-shifted emissions of these molecules suggesting the existence of additional asymmetries in their abundance distributions along the line-of-sight.Comment: 22 pages, 16 figures, 9 tables, accepted for publication in MNRA

Origen, concepción y tratamiento del ciclo de vida de los destinos turísticos: una reflexión entorno al modelo de butler

Desde su surgimiento, el Modelo del Ciclo de Vida de los Destinos Turísticos (MCVDT) desarrollado en el año 1980 por Richard Butler, dio lugar a grandes discusiones y generó una vasta literatura enfocada a su aplicación. Extenso ha sido el escrutinio del cual ha sido objeto, y amplias sus adaptaciones. En este trabajo, a través de una revisión bibliográfica, se busca establecer su origen, concepción y tratamiento, que ha llevado a lo largo de más de tres décadas, con la finalidad de determinar su vigencia como modelo estratégico de gestión y planeación dentro del ámbito del turismo así como sus limitantes conceptuales.UAEME

Phenotipic integration does not constrain phenotypic plasticity: differential plasticity of traits is associated to their integration across environments

ResearchUnderstanding constraints to phenotypic plasticity is key given its role on the response of organisms to environmental change. It has been suggested that phenotypic integration, the structure of trait covariation, could limit trait plasticity. However, the relationship between plasticity and integration is far from resolved. Using a database of functional plasticity to drought of a Mediterranean shrub that included 20 ecophysiological traits, we assessed environmentally-induced changes in phenotypic integration and whether integration constrained the expression of plasticity, accounting for the within-environment phenotypic variation of traits. Furthermore, we provide the first test of the association between differential trait plasticity and trait integration across an optimum and a stressful environment. Phenotypic plasticity was positively associated with phenotypic integration in both environments, but this relationship was lost when phenotypic variation was considered. The similarity in the plastic response of two traits predicted their integration across environments, with integrated traits having more similar plasticity. Such variation in the plasticity of traits partly explained the lower phenotypic integration found in the stressful environment. We found no evidence that integration may constitute an internal constraint to plasticity. Rather, we present the first empirical demonstration that differences in plastic responses may involve a major reorganization of the relationships among traits, and challenge the notion that stress generally induces a tighter phenotypeinfo:eu-repo/semantics/publishedVersio

Immature rats show ovulatory defects similar to those in adult rats lacking prostaglandin and progesterone actions

Gonadotropin-primed immature rats (GPIR) constitute a widely used model for the study of ovulation. Although the equivalence between the ovulatory process in immature and adult rats is generally assumed, the morphological and functional characteristics of ovulation in immature rats have been scarcely considered. We describe herein the morphological aspects of the ovulatory process in GPIR and their response to classical ovulation inhibitors, such as the inhibitor of prostaglandin (PG) synthesis indomethacin (INDO) and a progesterone (P) receptor (PR) antagonist (RU486). Immature Wistar rats were primed with equine chorionic gonadotropin (eCG) at 21, 23 or 25 days of age, injected with human chorionic gonadotropin (hCG) 48 h later, and sacrificed 16 h after hCG treatment, to assess follicle rupture and ovulation. Surprisingly, GPIR showed age-related ovulatory defects close similar to those in adult rats lacking P and PG actions. Rats primed with eCG at 21 or 23 days of age showed abnormally ruptured corpora lutea in which the cumulus-oocyte complex (COC) was trapped or had been released to the ovarian interstitum, invading the ovarian stroma and blood and lymphatic vessels. Supplementation of immature rats with exogenous P and/or PG of the E series did not significantly inhibit abnormal follicle rupture. Otherwise, ovulatory defects were practically absent in rats primed with eCG at 25 days of age. GPIR treated with INDO showed the same ovulatory alterations than vehicle-treated ones, although affecting to a higher proportion of follicles. Blocking P actions with RU486 increased the number of COC trapped inside corpora lutea and decreased ovulation. The presence of ovulatory defects in GPIR, suggests that the capacity of the immature ovary to undergo the coordinate changes leading to effective ovulation is not fully established in Wistar rats primed with eCG before 25 days of age

ANÁLISE SUSTENTÁVEL DO MODELO DE CICLO DE VIDA. SITUAÇÃO E PERSPECTIVAS DE IXTAPAN DE LA SAL, MÉXICO

Cuando se busca entender la evolución de un destino turístico, el análisis del ciclo de vida es una de las herramientas de gestión y planeación más utilizadas. Sin embargo, existen para su medición, variables limitadas que generalmente se basan en la cantidad de turistas y en el tiempo en que se ha desarrollado la actividad, lo cual deja en un segundo plano la sustentabilidad. En este trabajo, se formula un esquema alternativo de análisis mediante el cual se integran variables de sustentabilidad para establecer los impactos económicos, ambientales y sociales de los turistas actuales y futuros. Así también, se presenta una metodología que estima la curva de evolución de los destinos, para aquellos lugares que no cuentan con información suficiente. Finalmente se concluye que el destino de Ixtapan de la Sal, en México, hoy en día no es sustentable, y un mayor número de turistas solo pondría en riesgo su competitividad

Ecoinnovación en turismo. Una agenda de investigación en torno a las políticas públicas

In this article a literature review is carried out with the aim of analysing the current state of research on public policies on eco-innovation in tourism, to provide a knowledge base on the potential and nature of this object of study. A content analysis of the publications in the Web of Science database was carried out. Starting from open-access articles under a structured search equation, 182 articles from the period between 1991 and 2021 were identified; these were subsequently analysed and classified under the Cloud of Science and Tree of Science software. The results show that the study of eco-innovation and its relationship with public policies in tourism contexts is most advanced in Asian countries, and the literature in Latin American contexts is still at an incipient stage. Research on policies that promote environmental care and regulatory policies that improve ecological processes is identified, highlighting the importance of practices and operational factors. It is concluded that studies on remedial, punitive, and macro-regulatory policies for environmental science and technology are absent.En el presente artículo se realiza una revisión de literatura con el propósito de analizar el estado actual de las investigaciones en torno a las políticas públicas en materia de ecoinnovación en turismo, intentando proporcionar una base de conocimiento sobre el potencial y la naturaleza de este objeto de estudio. Se desarrolla un análisis de contenido de las publicaciones incluidas en la base de datos de Web of Science, partiendo de artículos de acceso abierto bajo una ecuación de búsqueda estructurada. Se identifican 182 artículos del periodo comprendido entre 1991 y 2021, los que posteriormente son analizados y clasificados mediante los softwares Cloud of Science y Tree of Science. Los resultados muestran que el estudio de la ecoinnovación y su relación con las políticas públicas en contextos turísticos se ha llevado a cabo en países asiáticos, y que la literatura en ámbitos latinoamericanos aún se encuentra en una etapa incipiente. Igualmente, se identifican investigaciones que atienden líneas sobre las políticas que promueven el cuidado ambiental, y las políticas reguladoras que mejoran los procesos en materia ecológica, las cuales resaltan la importancia de prácticas y factores operativos. Se concluye que existe una ausencia de estudios sobre políticas reparadoras, sancionadoras y macroreguladoras para la ciencia y tecnología ambiental

Tonatiuh, un trazador de rayos basado en simulación de Monte Carlo y con licencia GNU GPL

[Resumen] Tonatiuh es un trazador de rayos, basado en simulación de Monte Carlo. Es especialmente útil para el cálculo de mapas de flujo y eficiencias ópticas de cualquier sistema termosolar, incluyendo estructuras complejas y campos de heliostatos. Pretende estar en la vanguardia de las herramientas de simulación de plantas termosolares. Desde 2006, el desarrollo de Tonatiuh está liderado por el departamento de Energía Solar Térmica del CENER. Tonatiuh trabaja bajo licencia GNU GPL, es de código abierto y su uso es libre. Desde el CENER se anima a la utilización de Tonatiuh, así como a la participación en su desarrollo y extensión, especialmente a las universidades, centros tecnológicos y empresas del sector. El presente documento muestra algunas de las herramientas y aplicaciones incorporadas en Tonatiuh, a través de dos ejemplos.https://doi.org/10.17979/spudc.978849749808

The Telomerase Reverse Transcriptase Subunit from the Dimorphic Fungus Ustilago maydis

In this study, we investigated the reverse transcriptase subunit of telomerase in the dimorphic fungus Ustilago maydis. This protein (Trt1) contains 1371 amino acids and all of the characteristic TERT motifs. Mutants created by disrupting trt1 had senescent traits, such as delayed growth, low replicative potential, and reduced survival, that were reminiscent of the traits observed in est2 budding yeast mutants. Telomerase activity was observed in wild-type fungus sporidia but not those of the disruption mutant. The introduction of a self-replicating plasmid expressing Trt1 into the mutant strain restored growth proficiency and replicative potential. Analyses of trt1 crosses in planta suggested that Trt1 is necessary for teliospore formation in homozygous disrupted diploids and that telomerase is haploinsufficient in heterozygous diploids. Additionally, terminal restriction fragment analysis in the progeny hinted at alternative survival mechanisms similar to those of budding yeast

Field evaluation of a rapid immunochromatographic dipstick test for the diagnosis of cholera in a high-risk population

BACKGROUND: Early detection of cholera outbreaks is crucial for the implementation of the most appropriate control strategies. METHODS: The performance of an immunochromatographic dipstick test (Institute Pasteur, Paris, France) specific for Vibrio cholerae O1 was evaluated in a prospective study in Beira, Mozambique, during the 2004 cholera season (January-May). Fecal specimens were collected from 391 patients with acute watery nonbloody diarrhea and tested by dipstick and conventional culture. RESULTS: The overall sensitivity and specificity of the rapid test compared to culture were 95% (95% confidence interval [CI]: 91%–99%) and 89% (95% CI: 86%–93%), respectively. After stratification by type of sample (rectal swab/bulk stool) and severity of diarrhea, the sensitivity ranged between 85% and 98% and specificity between 77% and 97%. CONCLUSION: This one-step dipstick test performed well in the diagnosis of V. cholerae O1 in a setting with seasonal outbreaks where rapid tests are most urgently needed