An infrared diagnostic for magnetism in hot stars

Magnetospheric observational proxies are used for indirect detection of magnetic fields in hot stars in the X-ray, UV, optical, and radio wavelength ranges. To determine the viability of infrared (IR) hydrogen recombination lines as a magnetic diagnostic for these stars, we have obtained low-resolution (R~1200), near-IR spectra of the known magnetic B2V stars HR 5907 and HR 7355, taken with the Ohio State Infrared Imager/Spectrometer (OSIRIS) attached to the 4.1m Southern Astrophysical Research (SOAR) Telescope. Both stars show definite variable emission features in IR hydrogen lines of the Brackett series, with similar properties as those found in optical spectra, including the derived location of the detected magnetospheric plasma. These features also have the added advantage of a lowered contribution of stellar flux at these wavelengths, making circumstellar material more easily detectable. IR diagnostics will be useful for the future study of magnetic hot stars, to detect and analyze lower-density environments, and to detect magnetic candidates in areas obscured from UV and optical observations, increasing the number of known magnetic stars to determine basic formation properties and investigate the origin of their magnetic fields.Comment: 4 pages, accepted for publication in A&

Професорові П.Ю. Гриценку шістдесят

У ці світлі осінні дні наукова спільнота святкує славний ювілей — 60-річчя директора Інституту української мови Національної академії наук України, завідувача відділу діалектології, доктора філологічних наук, професора Павла Юхимовича Гриценка

Important Teacher Qualities for Integrating Blended Learning in Higher Education

Blended learning is widely accepted in Peruvian higher education for a number of reasons, including the fact that it allows students more leeway to accommodate their own unique schedule and learning needs. The present qualitative research investigates the qualities of effective teachers that are crucial to the successful implementation of blended learning from the vantage point of experts, who can gain valuable insight into the causes of organizational problems and the best strategies for resolving them. There are seven positive characteristics of blended learning teachers, such as the ability to recognize the need for pedagogical change or the confidence to incorporate technology into learning processes, and four negative characteristics, such as a lack of familiarity with blended learning or anxiety about students use of technology. Blended learning in higher education is investigated here to identify the factors that influence it

Drought impact in the Bolivian Altiplano agriculture associated with the El Niño–Southern Oscillation using satellite imagery data

Drought is a major natural hazard in the Bolivian Altiplano that causes large agricultural losses. However, the drought effect on agriculture varies largely on a local scale due to diverse factors such as climatological and hydrological conditions, sensitivity of crop yield to water stress, and crop phenological stage among others. To improve the knowledge of drought impact on agriculture, this study aims to classify drought severity using vegetation and land surface temperature data, analyse the relationship between drought and climate anomalies, and examine the spatio-temporal variability of drought using vegetation and climate data. Empirical data for drought assessment purposes in this area are scarce and spatially unevenly distributed. Due to these limitations we used vegetation, land surface temperature (LST), precipitation derived from satellite imagery, and gridded air temperature data products. Initially, we tested the performance of satellite precipitation and gridded air temperature data on a local level. Then, the normalized difference vegetation index (NDVI) and LST were used to classify drought events associated with past El Niño–Southern Oscillation (ENSO) phases. It was found that the most severe drought events generally occur during a positive ENSO phase (El Niño years). In addition, we found that a decrease in vegetation is mainly driven by low precipitation and high temperature, and we identified areas where agricultural losses will be most pronounced under such conditions. The results show that droughts can be monitored using satellite imagery data when ground data are scarce or of poor data quality. The results can be especially beneficial for emergency response operations and for enabling a proactive approach to disaster risk management against droughts

Mantle dynamics of the Andean Subduction Zone from continent-scale teleseismic S-wave tomography

The Andean Subduction Zone is one of the longest continuous subduction zones on Earth. The relative simplicity of the two-plate system has makes it an ideal natural laboratory to study the dynamics in subduction zones. We measure teleseismic S and SKS traveltime residuals at >1000 seismic stations that have been deployed across South America over the last 30 yr to produce a finite-frequency teleseismic S-wave tomography model of the mantle beneath the Andean Subduction Zone related to the Nazca Plate, spanning from ~5°N to 45°S and from depths of ~130 to 1200 km. Within our model, the subducted Nazca slab is imaged as a fast velocity seismic anomaly. The geometry and amplitude of the Nazca slab anomaly varies along the margin while the slab anomaly continues into the lower mantle along the entirety of the subduction margin. Beneath northern Brazil, the Nazca slab appears to stagnate at ~1000 km depth and extend eastward subhorizontally for >2000 km. South of 25°S the slab anomaly in the lower mantle extends offshore of eastern Argentina, hence we do not image if a similar stagnation occurs. We image several distinct features surrounding the slab including two vertically oriented slow seismic velocity anomalies: one beneath the Peruvian flat slab and the other beneath the Paraná Basin of Brazil. The presence of the latter anomaly directly adjacent to the stagnant Nazca slab suggests that the plume, known as the Paraná Plume, may be a focused upwelling formed in response to slab stagnation in the lower mantle. Additionally, we image a high amplitude fast seismic velocity anomaly beneath the Chile trench at the latitude of the Sierras Pampeanas which extends from ~400 to ~1000 km depth. This anomaly may be the remnants of an older, detached slab, however its relationship with the Nazca-South America subduction zone remains enigmatic.Fil: Rodríguez, Emily E.. University of Arizona; Estados UnidosFil: Portner, Daniel Evan. No especifíca;Fil: Beck, Susan L.. University of Arizona; Estados UnidosFil: Rocha, Marcelo P.. Universidade do Brasília; BrasilFil: Bianchi, Marcelo B.. Universidade de Sao Paulo; BrasilFil: Assumpção, Marcelo. Universidade de Sao Paulo; BrasilFil: Ruiz, Mario. Escuela Politécnica Nacional; EcuadorFil: Alvarado, Patricia Monica. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Condori, Cristobal. Universidade do Brasília; BrasilFil: Lynner, Colton. University Of Delaware; Estados Unido

Uso de Macromoléculas sobre la Tasa de Maduración y Desarrollo Embrionario in vitro de Ovocitos Bovinos

The effect of four supplements with macromolecules on the rate of nuclear maturation, oocyte division at 48 h and embryo development at 7 days post-fertilization was evaluated. Ovaries were collected in the slaughterhouse; oocytes with two or more layers of cells were selected and matured on TCM-99 enriched with macromolecule supplements: Polyvinylpyrrolidone (PVP), polyvinylalcohol (PVA), Bovine serum albumin (BSA), Foetal bovine serum (SFB). Oocytes were cultivated at 39 °C with 5% of CO2. Nuclear maturation was evaluated at 24 hours, classifying them as germinal vesicle, metaphase I, anaphasetelophase, metaphase II and degenerated. For the evaluation of the oocyte division and embryo development, oocytes were matured under the same conditions and fertilized with spermatozoa during 18 hours in KSOM-AA culture media, and then transferred to SOF culture media for 48 h. Significant differences on nuclear maturation (Metaphase II) were only observed between PVA and SFB (p<0.05). Furthermore, none significant differences on rate of division and embryonic development between treatments were observed. These results indicate that the macromolecule supplements provide similar conditions and requirements for the progression from metaphase I to metaphase II.Se evaluó el efecto de cuatro suplementos de macromoléculas sobre la tasa de maduración nuclear, división de ovocitos a las 48 horas y desarrollo embrionario a los siete días pos-fecundación. Se colectaron ovarios de camal, se aspiraron los folículos y se seleccionaron los ovocitos con dos o más capas de células para ser madurados en medio TCM-99 enriquecido con macromoléculas: Polivinil pirrolidona (PVP), Polivinil alcohol (PVA), Albúmina sérica bovina (BSA), Suero fetal bovino (SFB). Los ovocitos se cultivaron a 39 °C y con 5% de CO2. Se evaluó la maduración nuclear a las 24 h, calificándolos como vesícula germinal, metafase I, anafase-telofase, metafase II y degenerados. Para evaluar la división y desarrollo embrionario, otro grupo de ovocitos fueron madurados bajo las mismas condiciones y fecundados por 18 h en medio de cultivo KSOM-AA, y trasferidos al medio de cultivo SOF por 48 h. Solo hubo diferencias estadísticas en maduración nuclear (Metafase II) entre los grupos suplementados con PVA y SFB (p<0.05). Asimismo, no hubo diferencias entre tratamientos en la tasa de división y desarrollo embrionario. Los resultados indican que los suplementos de macromoléculas proporcionan condiciones y requerimientos similares para la progresión desde estadios de metafase I a metafase II

Effects of grazing pressure on plant species composition and water presence on bofedales in the Andes mountain range of Bolivia

Bofedales are high-Andean peatland plant communities with high capacity for water retention, which are regarded as oases of biodiversity. These areas have great social and economic value for livestock grazing, which plays an important role in their vegetation dynamics. However, the effects of increased livestock pressure on vegetation composition and surface water have not yet been clarified. The goal of this study was to assess the impact of current grazing practices on bofedal vegetation, species diversity and function. Specifically, the study aimed to (1) quantify carrying capacity and stocking rate in grazed bofedales and (2) quantify the effects of grazing pressure on plant composition and the extents of bare soil and surface water. Biomass and stocking rate estimates for 25 bofedales along the Cordillera Real (Tropical Andes, Bolivia) showed that all bofedales were overgrazed (carrying capacity/stocking rate (CC/SR) <1). Regression analyses showed significant decreases in number of plant species, species dominance, diversity and percent surface water as CC/SR declined (p < 0.05). Bofedales are negatively affected by increased grazing pressure and potentially affected by changes in livestock species. These pressures, combined with land use changes and climate change, could result in long-term negative effects for the ecological functioning and sustainability of bofedales