A new feature in the spectrum of the Large Magellanic Cloud hypergiant HDE 269896

Complejo Astronómico El Leoncito (CASLEO), operated under agreement among Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Secretaría de Ciencia y Tecnología (SeCyT), and the Universities of La Plata, Córdoba, and San Juan, Argentina We have found strong selective emission of the N II 5000 Å complex in the spectrum of the LMC hypergiant HDE 269896, ON9.7 Ia +. Because this object also has anomalously strong He II λ4686 emission for its spectral type, an unusually wide range of ionization in its extended atmosphere is indicated. The published model of this spectrum does not reproduce these emission features, but we show that increased nitrogen and helium abundances, together with small changes in other model parameters, can do so. The morphological and possible evolutionary relationships of HDE 269896, as illuminated by the new spectral features, to other denizens of the OB Zoo are discussed. This object may be in an immediate pre-WNVL (Very Late WN) state, which is in turn the quiescent state of at least some luminous blue variables. More generally, the N II spectrum in HDE 269896 provides a striking demonstration of the occurrence of two distinctly different kinds of line behavior in O-type spectra: normal absorption lines that develop P Cygni profiles at high wind densities, and selective emission lines from the same ions that do not. Further analysis of these features will advance understanding of both atomic physics and extreme stellar atmospheres.Facultad de Ciencias Astronómicas y Geofísica

A new feature in the spectrum of the Large Magellanic Cloud hypergiant HDE 269896

Complejo Astronómico El Leoncito (CASLEO), operated under agreement among Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Secretaría de Ciencia y Tecnología (SeCyT), and the Universities of La Plata, Córdoba, and San Juan, Argentina We have found strong selective emission of the N II 5000 Å complex in the spectrum of the LMC hypergiant HDE 269896, ON9.7 Ia +. Because this object also has anomalously strong He II λ4686 emission for its spectral type, an unusually wide range of ionization in its extended atmosphere is indicated. The published model of this spectrum does not reproduce these emission features, but we show that increased nitrogen and helium abundances, together with small changes in other model parameters, can do so. The morphological and possible evolutionary relationships of HDE 269896, as illuminated by the new spectral features, to other denizens of the OB Zoo are discussed. This object may be in an immediate pre-WNVL (Very Late WN) state, which is in turn the quiescent state of at least some luminous blue variables. More generally, the N II spectrum in HDE 269896 provides a striking demonstration of the occurrence of two distinctly different kinds of line behavior in O-type spectra: normal absorption lines that develop P Cygni profiles at high wind densities, and selective emission lines from the same ions that do not. Further analysis of these features will advance understanding of both atomic physics and extreme stellar atmospheres.Facultad de Ciencias Astronómicas y Geofísica

Spectral Variations of Of?p Oblique Magnetic Rotator Candidates in the Magellanic Clouds

Optical spectroscopic monitoring has been conducted of two O stars in the Small and one in the Large Magellanic Cloud, the spectral characteristics of which place them in the Of?p category, which has been established in the Galaxy to consist of oblique magnetic rotators. All of these Magellanic stars show systematic spectral variations typical of the Of?p class, further strengthening their magnetic candidacy to the point of virtual certainty. The spectral variations are related to photometric variations derived from OGLE data by Naze et al. (2015) in a parallel study, which yields rotational periods for two of them. Now circular spectropolarimetry is required to measure their fields, and ultraviolet spectroscopy to further characterize their low-metallicity, magnetically confined winds, in support of hydrodynamical analyses.Comment: 18 pages, 6 figures, accepted for publication by A

Bright Fluorescent Chemosensor Platforms for Imaging Endogenous Pools of Neuronal Zinc

AbstractA series of new fluorescent Zinpyr (ZP) chemosensors based on the fluorescein platform have been prepared and evaluated for imaging neuronal Zn2+. A systematic synthetic survey of electronegative substitution patterns on a homologous ZP scaffold provides a basis for tuning the fluorescence responses of “off-on” photoinduced electron transfer (PET) probes by controlling fluorophore pKa values and attendant proton-induced interfering fluorescence of the metal-free (apo) probes at physiological pH. We further establish the value of these improved optical tools for interrogating the metalloneurochemistry of Zn2+; the novel ZP3 fluorophore images endogenous stores of Zn2+ in live hippocampal neurons and slices, including the first fluorescence detection of Zn2+ in isolated dentate gyrus cultures. Our findings reveal that careful control of fluorophore pKa can minimize proton-induced fluorescence of the apo probes and that electronegative substitution offers a general strategy for tuning PET chemosensors for cellular studies. In addition to providing improved optical tools for Zn2+ in the neurosciences, these results afford a rational starting point for creating superior fluorescent probes for biological applications

Students’ Views on the Nature of Science in an Interdisciplinary First-Year Science Program: Content Analysis of a Weekly Reflection Activity

A primary aim of science education is to teach students how to interpret and engage with scientific information. To do so effectively requires an adequate understanding of the nature of science (NOS)—in other words, what science is and how it works. There is a long history of evidence to suggest that many undergraduate students struggle to properly understand NOS. While the specific factors contributing to misinformed views on NOS may be difficult to tease apart, the way in which students learn about science at the undergraduate level is a significant contributor. We implemented a reflection activity in a unique first-year program at a large Canadian university in order to promote student learning of NOS. Through the students’ reflections, we identified how certain pedagogical approaches, many of which deviate from traditional teaching methods used throughout undergraduate science education, can positively impact student comprehension of NOS. Our experiences support the use of reflective practices in promoting critical thinking and the development of more nuanced student views of NOS. Click here to read the corresponding ISSOTL blog post

High Passage MIN6 Cells Have Impaired Insulin Secretion with Impaired Glucose and Lipid Oxidation

Type 2 diabetes is a metabolic disorder characterized by the inability of beta-cells to secrete enough insulin to maintain glucose homeostasis. MIN6 cells secrete insulin in response to glucose and other secretagogues, but high passage (HP) MIN6 cells lose their ability to secrete insulin in response to glucose. We hypothesized that metabolism of glucose and lipids were defective in HP MIN6 cells causing impaired glucose stimulated insulin secretion (GSIS). HP MIN6 cells had no first phase and impaired second phase GSIS indicative of global functional impairment. This was coupled with a markedly reduced ATP content at basal and glucose stimulated states. Glucose uptake and oxidation were higher at basal glucose but ATP content failed to increase with glucose. HP MIN6 cells had decreased basal lipid oxidation. This was accompanied by reduced expressions of Glut1, Gck, Pfk, Srebp1c, Ucp2, Sirt3, Nampt. MIN6 cells represent an important model of beta cells which, as passage numbers increased lost first phase but retained partial second phase GSIS, similar to patients early in type 2 diabetes onset. We believe a number of gene expression changes occurred to produce this defect, with emphasis on Sirt3 and Nampt, two genes that have been implicated in maintenance of glucose homeostasis.These authors have no support or funding to report

A new feature in the spectrum of the Large Magellanic Cloud hypergiant HDE 269896

Complejo Astronómico El Leoncito (CASLEO), operated under agreement among Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Secretaría de Ciencia y Tecnología (SeCyT), and the Universities of La Plata, Córdoba, and San Juan, Argentina We have found strong selective emission of the N II 5000 Å complex in the spectrum of the LMC hypergiant HDE 269896, ON9.7 Ia +. Because this object also has anomalously strong He II λ4686 emission for its spectral type, an unusually wide range of ionization in its extended atmosphere is indicated. The published model of this spectrum does not reproduce these emission features, but we show that increased nitrogen and helium abundances, together with small changes in other model parameters, can do so. The morphological and possible evolutionary relationships of HDE 269896, as illuminated by the new spectral features, to other denizens of the OB Zoo are discussed. This object may be in an immediate pre-WNVL (Very Late WN) state, which is in turn the quiescent state of at least some luminous blue variables. More generally, the N II spectrum in HDE 269896 provides a striking demonstration of the occurrence of two distinctly different kinds of line behavior in O-type spectra: normal absorption lines that develop P Cygni profiles at high wind densities, and selective emission lines from the same ions that do not. Further analysis of these features will advance understanding of both atomic physics and extreme stellar atmospheres.Facultad de Ciencias Astronómicas y Geofísica

Variance Decomposition of the Continuous Assessment of Interpersonal Dynamics (CAID) system: Assessing sources of influence and reliability of observations of parent-teen interactions

The Continuous Assessment of Interpersonal Dynamics (CAID) is an observational tool that measures warmth and dominance dynamics in real time and is sensitive to individual, dyadic, and contextual influences. Parent-adolescent interpersonal dynamics, which conceptually map onto parenting styles, are an integral part of positive adolescent adjustment and protect against risky outcomes. The current study’s goal was to test the degree to which sources of influence on CAID data observed in a previous study of married couples generalize to a sample of parent-adolescent dyads. We examined data from ten raters who rated moment-to-moment warmth and dominance using CAID in a sample of 61 parent-adolescent dyads (N = 122) who were largely non-Hispanic White (62%) or African American (30%) based on parent report (adolescent M age = 14; 57% female). Dyads interacted in four different discussion segments (situations). We applied Generalizability Theory to delineate several sources of variance in CAID parameters and estimated within and between-person reliability. Results revealed a number of different influences, including the person, kinsperson (adolescent versus parent), dyad, rater, situation, and interactions among these factors, on ratings of parent-adolescent interpersonal behavior. These results largely replicate results from married couples, suggesting that the factors that influence ratings of interpersonal interactions largely generalize across sample types