Using Whole-Group Metabolic Rate and Behaviour to Assess the Energetics of Courtship in Red-Sided Garter Snakes

Reproductive effort is an important aspect of life history as reproductive success is arguably the most important component of fitness. Males tend to compete for access to females and, in the process, expend their energetic capital on mate searching, maleemale competition and courtship rather than directly on offspring. Red-sided garter snakes, Thamnophis sirtalis parietalis, are an exceptional model for studying energetic costs of courtship and mating as they fast during the spring mating season, which segregates the cost of energy acquisition from the cost of courtship and mating. However, measuring an individual male\u27s metabolic rate during courtship is complicated by the fact that male courtship behaviour in redsided garter snakes is dependent on both the detection of a female sexual attractiveness pheromone and on facilitated courtship (i.e. vigorous courtship is only exhibited in the presence of other males). Thus, traditional techniques of placing a mask over the head of individuals would prevent male courtship behaviour, and single animals placed in a flow-through chamber would not yield ecologically realistic levels of courtship, which are only seen in the context of a mating aggregation in this species. Because of these difficulties, we placed groups of males in a flow-through metabolic chamber together with a single female whose respiratory gases were vented outside the chamber to yield a whole-group metabolic rate during competitive courtship. We also measured the standard metabolic rates (SMR) of the males individually for comparison with active metabolic rates. Conservative estimates of peak group metabolic rates during courtship are 10e20 times higher than resting group metabolic rate, which was 1.88 times higher than SMR. These measurements, coupled with the fact that these males are aphagous during the breeding, indicates that costs of courtship may be high for males and has implications for the male mating tactics in this system

First Results from a 1.3 cm EVLA Survey of Massive Protostellar Objects: G35.03+0.35

We have performed a 1.3 centimeter survey of 24 massive young stellar objects (MYSOs) using the Expanded Very Large Array (EVLA). The sources in the sample exhibit a broad range of massive star formation signposts including Infrared Dark Clouds (IRDCs), UCHII regions, and extended 4.5 micron emission in the form of Extended Green Objects (EGOs). In this work, we present results for G35.03+0.35 which exhibits all of these phenomena. We simultaneously image the 1.3 cm ammonia (1,1) through (6,6) inversion lines, four methanol transitions, two H recombination lines, plus continuum at 0.05 pc resolution. We find three areas of thermal ammonia emission, two within the EGO (designated the NE and SW cores) and one toward an adjacent IRDC. The NE core contains an UCHII region (CM1) and a candidate HCHII region (CM2). A region of non-thermal, likely masing ammonia (3,3) and (6,6) emission is coincident with an arc of 44 GHz methanol masers. We also detect two new 25 GHz Class I methanol masers. A complementary Submillimeter Array 1.3 mm continuum image shows that the distribution of dust emission is similar to the lower-lying ammonia lines, all peaking to the NW of CM2, indicating the likely presence of an additional MYSO in this protocluster. By modeling the ammonia and 1.3 mm continuum data, we obtain gas temperatures of 20-220 K and masses of 20-130 solar. The diversity of continuum emission properties and gas temperatures suggest that objects in a range of evolutionary states exist concurrently in this protocluster.Comment: To appear in Astrophysical Journal Letters Special Issue on the EVLA. 16 pages, 3 figures. Includes the complete version of Figure 3, which was unable to fit into the journal article due to the number of panel

The Protocluster G18.67+0.03: A Test Case for Class I Methanol Masers as Evolutionary Indicators for Massive Star Formation

We present high angular resolution Submillimeter Array (SMA) and Karl G. Jansky Very Large Array (VLA) observations of the massive protocluster G18.67+0.03. Previously targeted in maser surveys of GLIMPSE Extended Green Objects (EGOs), this cluster contains three Class I methanol maser sources, providing a unique opportunity to test the proposed role of Class I masers as evolutionary indicators for massive star formation. The millimeter observations reveal bipolar molecular outflows, traced by 13CO(2-1) emission, associated with all three Class I maser sources. Two of these sources (including the EGO) are also associated with 6.7 GHz Class II methanol masers; the Class II masers are coincident with millimeter continuum cores that exhibit hot core line emission and drive active outflows, as indicated by the detection of SiO(5-4). In these cases, the Class I masers are coincident with outflow lobes, and appear as clear cases of excitation by active outflows. In contrast, the third Class I source is associated with an ultracompact HII region, and not with Class II masers. The lack of SiO emission suggests the 13CO outflow is a relic, consistent with its longer dynamical timescale. Our data show that massive young stellar objects associated only with Class I masers are not necessarily young, and provide the first unambiguous evidence that Class I masers may be excited by both young (hot core) and older (UC HII) MYSOs within the same protocluster.Comment: Astrophysical Journal Letters, accepted. emulateapj, 7 pages including 4 figures and 1 table. Figures compressed. v2: coauthor affiliation updated, emulateapj versio

Supernova Resonance--scattering Line Profiles in the Absence of a Photosphere

In supernova spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following the photosphere's recession. Most treatments and analyses of post-photospheric optical spectra of supernovae assume that forbidden-line emission comprises most if not all spectral features. However, evidence exists which suggests that some spectra exhibit line profiles formed via optically thick resonance-scattering even months or years after the supernova explosion. To explore this possibility we present a geometrical approach to supernova spectrum formation based on the "Elementary Supernova" model, wherein we investigate the characteristics of resonance-scattering in optically thick lines while replacing the photosphere with a transparent central core emitting non-blackbody continuum radiation, akin to the optical continuum provided by decaying 56Co formed during the explosion. We develop the mathematical framework necessary for solving the radiative transfer equation under these conditions, and calculate spectra for both isolated and blended lines. Our comparisons with analogous results from the Elementary Supernova code SYNOW reveal several marked differences in line formation. Most notably, resonance lines in these conditions form P Cygni-like profiles, but the emission peaks and absorption troughs shift redward and blueward, respectively, from the line's rest wavelength by a significant amount, despite the spherically symmetric distribution of the line optical depth in the ejecta. These properties and others that we find in this work could lead to misidentification of lines or misattribution of properties of line-forming material at post-photospheric times in supernova optical spectra.Comment: 37 pages, 24 figures; accepted for publication in ApJ Supplement Serie

Abundant cyanopolyynes as a probe of infall in the Serpens South cluster-forming region

We have detected bright HC7N J = 21-20 emission toward multiple locations in the Serpens South cluster-forming region using the K-Band Focal Plane Array at the Robert C. Byrd Green Bank Telescope. HC7N is seen primarily toward cold filamentary structures that have yet to form stars, largely avoiding the dense gas associated with small protostellar groups and the main central cluster of Serpens South. Where detected, the HC7N abundances are similar to those found in other nearby star forming regions. Toward some HC7N `clumps', we find consistent variations in the line centroids relative to NH3 (1,1) emission, as well as systematic increases in the HC7N non-thermal line widths, which we argue reveal infall motions onto dense filaments within Serpens South with minimum mass accretion rates of M ~ 2-5 M_sun Myr^-1. The relative abundance of NH3 to HC7N suggests that the HC7N is tracing gas that has been at densities n ~ 10^4 cm^-3, for timescales t < 1-2 x 10^5 yr. Since HC7N emission peaks are rarely co-located with those of either NH3 or continuum, it is likely that Serpens South is not particularly remarkable in its abundance of HC7N, but instead the serendipitous mapping of HC7N simultaneously with NH3 has allowed us to detect HC7N at low abundances in regions where it otherwise may not have been looked for. This result extends the known star-forming regions containing significant HC7N emission from typically quiescent regions, like the Taurus molecular cloud, to more complex, active environments.Comment: 19 pages, 13 figures, accepted to MNRAS. Version with full resolution figures available at http://www.dunlap.utoronto.ca/~friesen/Friesen_HC7N.pd

Near-infrared line identification in type Ia supernovae during the transitional phase

We present near-infrared synthetic spectra of a delayed-detonation hydrodynamical model and compare them to observed spectra of four normal type Ia supernovae ranging from day +56.5 to day +85. This is the epoch during which supernovae are believed to be undergoing the transition from the photospheric phase, where spectra are characterized by line scattering above an optically thick photosphere, to the nebular phase, where spectra consist of optically thin emission from forbidden lines. We find that most spectral features in the near-infrared can be accounted for by permitted lines of Fe II and Co II. In addition, we find that [Ni II] fits the emission feature near 1.98 {\mu}m, suggesting that a substantial mass of 58Ni exists near the center of the ejecta in these objects, arising from nuclear burning at high density. A tentative identification of Mn II at 1.15 {\mu}m may support this conclusion as well.Comment: accepted to Ap

The Initial Conditions of Clustered Star Formation III. The Deuterium Fractionation of the Ophiuchus B2 Core

We present N2D+ 3-2 (IRAM) and H2D+ 1_11 - 1_10 and N2H+ 4-3 (JCMT) maps of the small cluster-forming Ophiuchus B2 core in the nearby Ophiuchus molecular cloud. In conjunction with previously published N2H+ 1-0 observations, the N2D+ data reveal the deuterium fractionation in the high density gas across Oph B2. The average deuterium fractionation R_D = N(N2D+)/N(N2H+) ~ 0.03 over Oph B2, with several small scale R_D peaks and a maximum R_D = 0.1. The mean R_D is consistent with previous results in isolated starless and protostellar cores. The column density distributions of both H2D+ and N2D+ show no correlation with total H2 column density. We find, however, an anticorrelation in deuterium fractionation with proximity to the embedded protostars in Oph B2 to distances >= 0.04 pc. Destruction mechanisms for deuterated molecules require gas temperatures greater than those previously determined through NH3 observations of Oph B2 to proceed. We present temperatures calculated for the dense core gas through the equating of non-thermal line widths for molecules (i.e., N2D+ and H2D+) expected to trace the same core regions, but the observed complex line structures in B2 preclude finding a reasonable result in many locations. This method may, however, work well in isolated cores with less complicated velocity structures. Finally, we use R_D and the H2D+ column density across Oph B2 to set a lower limit on the ionization fraction across the core, finding a mean x_e, lim >= few x 10^{-8}. Our results show that care must be taken when using deuterated species as a probe of the physical conditions of dense gas in star-forming regions.Comment: ApJ accepte

Suspect screening of maternal serum to identify new environmental chemical biomonitoring targets using liquid chromatography-quadrupole time-of-flight mass spectrometry.

The use and advantages of high-resolution mass spectrometry (MS) as a discovery tool for environmental chemical monitoring has been demonstrated for environmental samples but not for biological samples. We developed a method using liquid chromatography-quadrupole time-of-flight MS (LC-QTOF/MS) for discovery of previously unmeasured environmental chemicals in human serum. Using non-targeted data acquisition (full scan MS analysis) we were able to screen for environmental organic acids (EOAs) in 20 serum samples from second trimester pregnant women. We define EOAs as environmental organic compounds with at least one dissociable proton which are utilized in commerce. EOAs include environmental phenols, phthalate metabolites, perfluorinated compounds, phenolic metabolites of polybrominated diphenyl ethers and polychlorinated biphenyls, and acidic pesticides and/or predicted acidic pesticide metabolites. Our validated method used solid phase extraction, reversed-phase chromatography in a C18 column with gradient elution, electrospray ionization in negative polarity and automated tandem MS (MS/MS) data acquisition to maximize true positive rates. We identified "suspect EOAs" using Agilent MassHunter Qualitative Analysis software, to match chemical formulas generated from each sample run with molecular formulas in our unique database of 693 EOAs assembled from multiple environmental literature sources. We found potential matches for 282 (41%) of the EOAs in our database. Sixty-five of these suspect EOAs were detected in at least 75% of the samples; only 19 of these compounds are currently biomonitored in National Health and Nutrition Examination Survey. We confirmed two of three suspect EOAs by LC-QTOF/MS using a targeted method developed through LC-MS/MS, reporting the first confirmation of benzophenone-1 and bisphenol S in pregnant women's sera. Our suspect screening workflow provides an approach to comprehensively scan environmental chemical exposures in humans. This can provide a better source of exposure information to help improve exposure and risk evaluation of industrial chemicals

Reuse as heuristic : from transmission to nurture in learning activity design

In recent years a combination of ever more flexible and sophisticated Web technologies and an explosion in the quantity of online content has sparked learning technologists around the world to pursue the promise of the 'reusable learning object' or RLO with the idea that RLOs could be reused in different educational contexts, thereby providing greater overall flexibility and return on investment. In 2002 the ACETS Project undertook a three-year study in the UK to investigate whether RLOs worked in practice and how the pursuit of reuse affected the teacher and their teaching. Teachers working in healthcare-related subjects in Higher and Further Education were asked to create an original learning design or activity from third-party digital resources and to reflect both on the process and its outcomes. The expectation was that teachers would be the ones selecting and reusing third-party materials. This paper describes how one of the ACETS exemplifiers reinterpreted this remit, challenged the anticipated transmissive model of learning, and instead, gave their students an opportunity to create their own original learning designs and learning activities from third-party digital resources. By describing the educational enhancements, the resulting heightened levels of critical thinking, and sensitivity to patient needs, 'reuse' will be shown to be an effective heuristic for student self-direction and professional development

Diploid \u3ci\u3eAllium ramosum\u3c/i\u3e from East Mongolia: A Missing Link for the Origin of the Crop Species \u3ci\u3eA. tuberosum\u3c/i\u3e?

In eastern Mongolia, a diploid close relative of the tetraploid (4x) crop species Allium tuberosum and its closest wild relative A. ramosum (4x) was found and characterized by karyotype analysis and with molecular marker techniques. An earlier analyses revealed A. ramosum to be sister of the crop but excluded it as its progenitor. At that time a putative diploid cytotype of A. ramosum was hypothesized as a potential progenitor taxon of the tetraploids. New phylogenetic analyses of chloroplast and nuclear DNA sequences including the recently found cytotype (A. aff. tuberosum) together with A. tuberosum and A. ramosum accessions revealed a sister group relationship of both species, with A. aff. tuberosum having sequences very similar or identical with A. ramosum. Two fingerprint analyses (RAPD, SCoT) resulted in phylogenetic trees where aff. tuberosum grouped basal to A. ramosum, although the two taxa are morphologically and ecologically clearly differentiated. We conclude that East Mongolian aff. tuberosum is not the progenitor of A. tuberosum but that it might belong to a stock of ancient lineages that gave rise to both tetraploid taxa