Line Ratios Reveal N2H+ Emission Originates Above the Midplane in TW Hydrae

Line ratios for different transitions of the same molecule have long been used as a probe of gas temperature. Here we use ALMA observations of the N2H+ J~=~1-0 and J~=~4-3 lines in the protoplanetary disk around TW Hya to derive the temperature at which these lines emit. We find an averaged temperature of 39~K with a one sigma uncertainty of 2~K for the radial range 0.8-2'', significantly warmer than the expected midplane temperature beyond 0.5'' in this disk. We conclude that the N2H+ emission in TW Hya is not emitting from near the midplane, but rather from higher in the disk, in a region likely bounded by processes such as photodissociation or chemical reprocessing of CO and N2 rather than freeze out.Comment: Accepted for publication in ApJ Letters, 5 pages, 1 figur

Survival of Fecal Contamination Indicator Organisms in Soil

Soils amended with human or animal waste may result in pathogen contamination of ground and surface water. Because temperature has been shown to affect pathogen survival, two laboratory studies were conducted to evaluate the impact of extremes in temperature on bacterial and viral pathogen indicator die-off in soil. A Captina silt loam was amended with broiler litter (0.1 g/g dry soil), septic tank effluent, or Escherichia coli (ATCC 13706) culture (both at 0.04 and 0.1 mL/g dry soil in the two respective studies), incubated at 5 and 35°C, and analyzed over time to determine the number of fecal coliform, E. coli, and coliphage remaining. Pathogen indicator die-off rate constants (k) for all indicator- temperature-treatment combinations were determined by first-order kinetics. For all three pathogen indicators, die-off was significantly more rapid at 35°C than at 5°C. In both studies, fecal coliform die-off rates were not different from E. coli die-off rates across each temperature-treatment combination. Levels of these bacterial indicators appeared in a ratio of 1:0.94 with 95% confidence intervals at 0.89 and 0.99 in the E. coli- and litter-amended soils. Die-off of the viral indicator was significantly slower than the die-off of the bacterial indicators at 5°C in litter-amended soil. Die-off of the bacterial indicator, E. coli, in soil amended with E. coli culture was not significantly different than die-off in soil amended with broiler litter at 5 or 35°C in the two studies. Because the higher incubation temperature increased die-off rates for all three indicators, it is expected that the potential for contamination of ground and surface water decreases with increasing temperature

An Archaic-Woodland Site in Calhoun County, S.C., 38CL4

https://scholarcommons.sc.edu/archanth_books/1023/thumbnail.jp

Health Transfers: An Application of Health-Health Analysis to Assess Food Safety Regulations

The authors apply a Health-Health Analysis to risks associated with harvesting Gulf oysters to evaluate that approach to managing health and safety risks

On the methanol emission detection in the TW Hya disc: the role of grain surface chemistry and non-LTE excitation

The recent detection of gas-phase methanol (CH$_3$OH) lines in the disc of TW Hya by Walsh et al. provided the first observational constraints on the complex O-bearing organic content in protoplanetary discs. The emission has a ring-like morphology, with a peak at $\sim 30-50$ au and an inferred column density of $\sim 3-6\times10^{12}$ cm$^{-2}$. A low CH$_3$OH fractional abundance of $\sim 0.3-4\times 10^{-11}$ (with respect to H$_2$) is derived, depending on the assumed vertical location of the CH$_3$OH molecular layer. In this study, we use a thermo-chemical model of the TW Hya disc, coupled with the ALCHEMIC gas-grain chemical model, assuming laboratory-motivated, fast diffusivities of the surface molecules to interpret the CH$_3$OH detection. Based on this disc model, we performed radiative transfer calculations with the LIME code and simulations of the observations with the CASA simulator. We found that our model allows to reproduce the observations well. The CH$_3$OH emission in our model appears as a ring with radius of $\sim60$ au. Synthetic and observed line flux densities are equal within the rms noise level of observations. The synthetic CH$_3$OH spectra calculated assuming local thermodynamic equilibrium (LTE) can differ by up to a factor of 3.5 from the non-LTE spectra. For the strongest lines, the differences between LTE and non-LTE flux densities are very small and practically negligible. Variations in the diffusivity of the surface molecules can lead to variations of the CH$_3$OH abundance and, therefore, line flux densities by an order of magnitude.Comment: Accepted for publication in MNRAS, 8 pages, 8 figure

Table of contents and editorial information for Vol. 10, no. 2, Spring 1983

Table of contents and editorial information for Vol. 10, no. 2, Spring 198

Public Perception and Influential Sources Toward Child Welfare Services

The purpose of this study is to answer the following questions: “What is the current public attitude toward public child welfare services and what sources of information have been used to formulate these attitudes?” In answering these questions, child welfare agencies would have a better understanding of what populations to promote public outreach, education, or further community involvement based on demographics and/or which venues to implement such outreach. This study provides information on previous studies where researchers have looked at the general role of social work and used the gathered information to assess public sentiment. In past research there has been discrepancy in the outcomes of this data. Past research has also incorporated news media and the portrayal of child welfare social workers, but has not attempted to measure the impacts of media and the public’s perception of the profession. With recent societal events, it has become more evident that public perception can be a driving force in policy change. The intent of this study is to identify individual demographic information (e.g., race/ethnicity, income level, household size, prior child welfare system involvement, etc.) that would show a significant relationship with a developed scale to measure participants’ attitude or sentiment toward child welfare social work. To obtain participants, a link to the developed survey was posted to multiple social media pages where the primary subject included the Victor Valley region of San Bernardino County, California. Participants were also asked to repost the link to the survey to their social media pages in order to increase participant numbers. For this project, 183 participants completed the survey to completion. Due to the level of measurement of the variables, multiple data analysis techniques were used in order to identify relationships between the independent demographic variables and the score on the sentiment scale. These techniques include t-tests, ANOVA, and correlation. Of the variables measured for statistical significance, only the participants past levels of child welfare services involvement showed significance. This was especially true for participants who had experiences both as a minor and as a parent. Income level, news sources, and other demographic identifiers did not show statistically significant differences in sentiment toward child welfare social work. With the information from this study, child welfare agencies might implement further outreach to the identified populations in order to provide further support. This information can also identify which specific factors contribute to the negative perceptions through qualitative analysis

Educational Considerations, vol. 10(2) Full Issue

Educational Considerations, vol. 10(2) Spring 1983 - Full issu