Characterizing the Youngest Herschel-detected Protostars I. Envelope Structure Revealed by CARMA Dust Continuum Observations

We present CARMA 2.9 mm dust continuum emission observations of a sample of 14 Herschel-detected Class 0 protostars in the Orion A and B molecular clouds, drawn from the PACS Bright Red Sources (PBRS) sample (Stutz et al.). These objects are characterized by very red 24 \micron\ to 70 \micron\ colors and prominent submillimeter emission, suggesting that they are very young Class 0 protostars embedded in dense envelopes. We detect all of the PBRS in 2.9 mm continuum emission and emission from 4 protostars and 1 starless core in the fields toward the PBRS; we also report 1 new PBRS source. The ratio of 2.9 mm luminosity to bolometric luminosity is higher by a factor of $\sim$5 on average, compared to other well-studied protostars in the Perseus and Ophiuchus clouds. The 2.9 mm visibility amplitudes for 6 of the 14 PBRS are very flat as a function of uv-distance, with more than 50\% of the source emission arising from radii $<$ 1500 AU. These flat visibility amplitudes are most consistent with spherically symmetric envelope density profiles with $\rho$~$\propto$~R$^{-2.5}$. Alternatively, there could be a massive unresolved structure like a disk or a high-density inner envelope departing from a smooth power-law. The large amount of mass on scales $<$ 1500 AU (implying high average central densities) leads us to suggest that that the PBRS with flat visibility amplitude profiles are the youngest PBRS and may be undergoing a brief phase of high mass infall/accretion and are possibly among the youngest Class 0 protostars. The PBRS with more rapidly declining visibility amplitudes still have large envelope masses, but could be slightly more evolved.Comment: Accepted to ApJ, 40 pages, 9 Figures, 4 Table

Protein Requirements of Pre-Menopausal Female Athletes: Systematic Literature Review

This systematic literature review aimed to determine the protein requirements of pre-menopausal (e.g., 18&ndash;45 years) female athletes and identify if the menstrual cycle phase and/or hormonal contraceptive use influence protein requirements. Four databases were searched for original research containing pre-menopausal female athletes that ingested protein alongside exercise. The Academy of Nutrition and Dietetics Quality Criteria Checklist was used to determine study quality. Fourteen studies, which included 204 recreationally active or competitive females, met the eligibility criteria for inclusion in this review, and all were assessed as positive quality. The estimated average requirement (EAR) for protein intake of pre-menopausal recreational and/or competitive female athletes is similar for those undertaking aerobic endurance (1.28&ndash;1.63 g/kg/day), resistance (1.49 g/kg/day) and intermittent exercise (1.41 g/kg/day) of ~60&ndash;90 min duration. The optimal acute protein intake and influence of menstrual cycle phase or hormonal contraceptive use on protein requirements could not be determined. However, pre- and post-exercise protein intakes of 0.32&ndash;0.38 g/kg have demonstrated beneficial physiological responses in recreational and competitive female athletes completing resistance and intermittent exercise. The protein requirements outlined in this review can be used for planning and assessing protein intakes of recreational and competitive pre-menopausal female athletes

Spitzer and HHT observations of starless cores: masses and environments

We present Spitzer observations of a sample of 12 starless cores selected to have prominent 24 micron shadows. The Spitzer images show 8 and 24 micron shadows and in some cases 70 micron shadows; these spatially resolved absorption features trace the densest regions of the cores. We have carried out a 12CO (2-1) and 13CO (2-1) mapping survey of these cores with the Heinrich Hertz Telescope (HHT). We use the shadow features to derive optical depth maps. We derive molecular masses for the cores and the surrounding environment; we find that the 24 micron shadow masses are always greater than or equal to the molecular masses derived in the same region, a discrepancy likely caused by CO freeze--out onto dust grains. We combine this sample with two additional cores that we studied previously to bring the total sample to 14 cores. Using a simple Jeans mass criterion we find that ~ 2/3 of the cores selected to have prominent 24 micron shadows are collapsing or near collapse, a result that is supported by millimeter line observations. Of this subset at least half have indications of 70 micron shadows. All cores observed to produce absorption features at 70 micron are close to collapse. We conclude that 24 micron shadows, and even more so the 70 micron ones, are useful markers of cloud cores that are approaching collapse.Comment: 41 pages, 28 figures, 5 tables; accepted by Ap

Cognitive and Behavioral Contributions to Depression Severity, Quality of Life, and Functioning Among People Living With HIV in South Africa

•Impact of rumination and behavioral activation on depression in HIV is unknown.•This is particularly the case in resource-limited global settings like South Africa.•Models showed higher levels of rumination significantly associated with depression.•Behavioral activation (BA) is an important treatment target for this population.•Models showed lower levels of BA significantly associated with depression.•Only BA significantly associated with quality of life and functional impairment. Cognitive-behavioral treatments for depression typically address both behavioral (e.g., activation) and cognitive (e.g., rumination) components, and consequently improve quality of life (QOL) and function in high-resource settings. However, little is known about the cross-cultural applicability and relative contribution of these components to depression symptom severity, QOL, and functional impairment in South Africa and other resource-limited global settings with high HIV prevalence rates. Persons with HIV (N = 274) from a peri-urban community outside Cape Town, South Africa, were administered multiple measures of depression (Hamilton Depression Scale, Centre for Epidemiological Studies Depression Scale, South African Depression Scale), cognitive and behavioral components related to depression (Ruminative Response Scale, Behavioral Activation for Depression Scale), and measures of QOL and functioning (Sheehan Disability Scale, Quality of Life Enjoyment and Satisfaction Scale—Short Form). Multiple linear regression models were fit to assess the relative contribution of behavioral and cognitive components to depression severity, QOL, and functional impairment in this population. Models accounting for age and sex revealed that lower levels of behavioral activation (BA) were significantly associated with all measures of depression, as well as with QOL and functional impairment (all ps < .01). Rumination was associated with all measures of depression (all ps < .01), but not with QOL or functional impairment. The consistent and unique association of BA with depression, QOL, and functional impairment bolsters its importance as a treatment target for this population

HOPS 136: An Edge-On Orion Protostar Near the End of Envelope Infall

Edge-on protostars are valuable for understanding the disk and envelope properties of embedded young stellar objects, since the disk, envelope, and envelope cavities are all distinctly visible in resolved images and well constrained in modeling. Comparing Two Micron All Sky Survey, Wide-field Infrared Survey Explorer, Spitzer, Herschel, and APEX photometry and an IRAM limit from 1.2 to 1200 μm, Spitzer spectroscopy from 5 to 40 μm, and high-resolution Hubble imaging at 1.60 and 2.05 μm to radiative transfer modeling, we determine envelope and disk properties for the Class I protostar HOPS 136, an edge-on source in Orion's Lynds 1641 region. The source has a bolometric luminosity of 0.8 L_☉, a bolometric temperature of 170 K, and a ratio of submillimeter to bolometric luminosity of 0.8%. Via modeling, we find a total luminosity of 4.7 L_☉ (larger than the observed luminosity due to extinction by the disk), an envelope mass of 0.06  M_☉, and a disk radius and mass of 450 AU and 0.002 M_☉. The stellar mass is highly uncertain but is estimated to fall between 0.4 and 0.5 M_☉. To reproduce the flux and wavelength of the near-infrared scattered-light peak in the spectral energy distribution, we require 5.4 × 10^(−5)  M_☉ of gas and dust in each cavity. The disk has a large radius and a mass typical of more evolved T Tauri disks in spite of the significant remaining envelope. HOPS 136 appears to be a key link between the protostellar and optically revealed stages of star formation

A Comparison of Pedagogical Knowledge Structures of Preservice Students and Teacher Educators in Two Institutions

Understanding how the knowledge structures of preservice teachers develop as expertise is acquired would seem to be an important aspect of teacher preparation. The purpose of this study was to compare the pedagogical knowledge structures about effective teaching of preservice teachers and teacher educators in the professional preparation programs of two different institutions. Two groups of preservice teachers at two different points in their preparation program at each of the two institutions were asked to complete a concept map (Roehler et al., 1987) about effective teaching. One group completed the concept map just after the first teaching methods course, and the other group completed the map just prior to student teaching. These data were compared with concept maps of teacher educators at each institution. Quantitative and qualitative data revealed differences between the groups of preservice teachers and between the preservice teachers and the teacher educators

Line Profiles of Cores within Clusters: I. The Anatomy of a Filament

Observations are revealing the ubiquity of filamentary structures in molecular clouds. As cores are often embedded in filaments, it is important to understand how line profiles from such systems differ from those of isolated cores. We perform radiative transfer calculations on a hydrodynamic simulation of a molecular cloud in order to model line emission from collapsing cores embedded in filaments. We model two optically thick lines, CS(2-1) and HCN(1-0), and one optically thin line, N2H+(1-0), from three embedded cores. In the hydrodynamic simulation, gas self-gravity, turbulence, and bulk flows create filamentary regions within which cores form. Though the filaments have large dispersions, the N2H+(1-0) lines indicate subsonic velocities within the cores. We find that the observed optically thick line profiles of CS(2-1) and HCN(1-0) vary drastically with viewing angle. In over 50% of viewing angles, there is no sign of a blue asymmetry, an idealised signature of infall motions in an isolated spherical collapsing core. Profiles which primarily trace the cores, with little contribution from the surrounding filament, are characterised by a systematically higher HCN(1-0) peak intensity. The N2H+(1-0) lines do not follow this trend. We demonstrate that red asymmetric profiles are also feasible in the optically thick lines, due to emission from the filament or one-sided accretion flows onto the core. We conclude that embedded cores may frequently undergo collapse without showing a blue asymmetric profile, and that observational surveys including filamentary regions may underestimate the number of collapsing cores if based solely on profile shapes of optically thick lines.Comment: 18 pages, 14 figures, 5 tables Submitted to Ap

The Portrait of Teacher Talk and Language Choices in EFL Classroom: Insights for Children’s Language Learning

The present study focused on teachers’ perceptions of how teacher talk works in the classroom and some challenges they might encounter during initiating interaction to encourage students.  A classroom observation was done to portray the data of the learning process and teachers’ interview was also conducted to discover insights about teacher talk and the challenges encountered in the classroom interaction. Findings demonstrated that the teachers enacted dominant English communication as the input rather than using students’ first language. They felt increasing the use of the target language would be more challenging as it is influenced by some aspects from both teachers and students’ motivation, attitude, and proficiency. In addition, teacher talk is varied in some extents based on the teacher and student factors. The findings also showed that teacher talk mostly occurred in the form of asking questions, giving directions, explaining the lesson, and praising the students. In addition, as the students were considered young learners, it was found that classroom interaction and language choice must be adjustable in order to make communication become more effective.   Keywords: teacher talk, perception, challenge, language choice, primary level

The Herschel Orion Protostar Survey: Luminosity and Envelope Evolution

The Herschel Orion Protostar Survey obtained well-sampled 1.2–870 μm spectral energy distributions (SEDs) of over 300 protostars in the Orion molecular clouds, home to most of the young stellar objects (YSOs) in the nearest 500 pc. We plot the bolometric luminosities and temperatures for 330 Orion YSOs, 315 of which have bolometric temperatures characteristic of protostars. The histogram of the bolometric temperature is roughly flat; 29% of the protostars are in Class 0. The median luminosity decreases by a factor of four with increasing bolometric temperature; consequently, the Class 0 protostars are systematically brighter than the Class I protostars, with a median luminosity of 2.3 L_☉ as opposed to 0.87 L_☉. At a given bolometric temperature, the scatter in luminosities is three orders of magnitude. Using fits to the SEDs, we analyze how the luminosities corrected for inclination and foreground reddening relate to the mass in the inner 2500 au of the best-fit model envelopes. The histogram of the envelope mass is roughly flat, while the median-corrected luminosity peaks at 15 L_☉ for young envelopes and falls to 1.7 L_☉ for late-stage protostars with remnant envelopes. The spread in luminosity at each envelope mass is three orders of magnitude. Envelope masses that decline exponentially with time explain the flat mass histogram and the decrease in luminosity, while the formation of a range of stellar masses explains the dispersion in luminosity

Spitzer Observations of L429: A Near-collapse or Collapsing Starless Core

We present Spitzer infrared observations of the starless core L429. The IR images of this core show an absorption feature, caused by the dense core material, at wavelengths <= 70 micron. The core has a steep density profile, and reaches A_V > 35 mag near the center. We show that L429 is either collapsing or in a near-collapse state.Comment: 5 pages, 3 figures, emulateapj format, accepted for publication in ApJ