17,793 research outputs found
Experimental Performance of a Solar Air Collector with a Perforated Back Plate in New Zealand
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Apollo cryogenic integrated systems program
The integrated systems program is capable of simulating both nominal and anomalous operation of the Apollo cryogenics storage system (CSS). Two versions of the program exist; one for the Apollo 14 configuration and the other for J Type Mission configurations. The program consists of two mathematical models which are dynamically coupled. A model of the CSS components and lines determines the oxygen and hydrogen flowrate from each storage tank given the tank pressures and temperatures, and the electrical power subsystem and environmental control subsystem flow demands. Temperatures and pressures throughout the components and lines are also determined. A model of the CSS tankage determines the pressure and temperatures in the tanks given the flowrate from each tank and the thermal environment. The model accounts for tank stretch and includes simplified oxygen tank heater and stratification routines. The program is currently operational on the Univac 1108 computer
Observation of HCN hyperfine line anomalies towards low- and high-mass star-forming cores
HCN is becoming a popular choice of molecule for studying star formation in
both low- and high-mass regions and for other astrophysical sources from comets
to high-redshift galaxies. However, a major and often overlooked difficulty
with HCN is that it can exhibit non-local thermodynamic equilibrium (non-LTE)
behaviour in its hyperfine line structure. Individual hyperfine lines can be
strongly boosted or suppressed. In low-mass star-forming cloud observations,
this could possibly lead to large errors in the calculation of opacity and
excitation temperature, while in massive star-forming clouds, where the
hyperfine lines are blended due to turbulent broadening, errors will arise in
infall measurements that are based on the separation of the peaks in a
self-absorbed profile. The underlying line shape cannot be known for certain if
hyperfine anomalies are present. We present a first observational investigation
of these anomalies across a range of conditions and transitions by carrying out
a survey of low-mass starless cores (in Taurus & Ophiuchus) and high-mass
protostellar objects (in the G333 giant molecular cloud) using hydrogen cyanide
(HCN) J=1-0 and J=3-2 emission lines. We quantify the degree of anomaly in
these two rotational levels by considering ratios of individual hyperfine lines
compared to LTE values. We find that all the cores observed show some degree of
anomaly while many of the lines are severely anomalous. We conclude that HCN
hyperfine anomalies are common in both lines in both low-mass and high-mass
protostellar objects, and we discuss the differing hypotheses for the
generation of the anomalies. In light of the results, we favour a line overlap
effect for the origins of the anomalies. We discuss the implications for the
use of HCN as a dynamical tracer and suggest in particular that the J=1-0,
F=0-1 hyperfine line should be avoided in quantitative calculations.Comment: 17 pages, 8 figure
Status, Dispersal, and Breeding Biology of the Exotic Eurasian Collared-Dove (Streptopelia decaocto) in Arkansas
The exotic Eurasian Collared-Dove (Streptopelia decaocto) was first sighted in Arkansas at Harrison (Boone Co.) on 25 June 1989. Since this initial sighting the species has grown in numbers and is now present in 42 of 75 counties across the state. In the spring and summer of 2009 and 2010, 20 nests were observed in the urban areas of Fort Smith (Sebastian County). Fifteen of the 20 nests (75%) were located on human-made structures of which 13 (65%) were on an electrical substation and two (10%) were on utility poles. The remaining 5 nests (25%) were in trees. Mean nest height was 7.62 m (n = 20 nests), and the mean width of the nest site support was 40 cm (n = 6 nests). Thirteen of the 20 nests (65%) yielded fledgling(s). Three focal nests were chosen for intense observation. Nest building lasted 1 to 3 days (mean = 2 days); incubation period was 15 days; and fledging occurred 17-18 days after hatching (n = 3 nests). A total of 6 young fledged from these 3 nests
Analysis of Hydrogen Cyanide Hyperfine Spectral Components towards Star Forming Cores
Although hydrogen cyanide has become quite a common molecular tracing species
for a variety of astrophysical sources, it, however, exhibits dramatic non-LTE
behaviour in its hyperfine line structure. Individual hyperfine components can
be strongly boosted or suppressed. If these so-called hyperfine line anomalies
are present in the HCN rotational spectra towards low or high mass cores, this
will affect the interpretation of various physical properties such as the line
opacity and excitation temperature in the case of low mass objects and infall
velocities in the case of their higher mass counterparts. This is as a
consequence of the direct effects that anomalies have on the underlying line
shape, be it with the line structural width or through the inferred line
strength. This work involves the first observational investigation of these
anomalies in two HCN rotational transitions, J=1!0 and J=3!2, towards both low
mass starless cores and high mass protostellar objects. The degree of anomaly
in these two rotational transitions is considered by computing the ratios of
neighboring hyperfine lines in individual spectra. Results indicate some degree
of anomaly is present in all cores considered in our survey, the most likely
cause being line overlap effects among hyperfine components in higher
rotational transitions.Comment: 8th Serbian Conference on Spectral Line Shapes in Astrophysics,
Divicibare; 8 pages, 5 figure
A Search for Biomolecules in Sagittarius B2 (LMH) with the ATCA
We have used the Australia Telescope Compact Array to conduct a search for
the simplest amino acid, glycine (conformers I and II), and the simple chiral
molecule propylene oxide at 3-mm in the Sgr B2 LMH. We searched 15 portions of
spectrum between 85 and 91 GHz, each of 64 MHz bandwidth, and detected 58
emission features and 21 absorption features, giving a line density of 75
emission lines and 25 absorption lines per GHz stronger than the 5 sigma level
of 110 mJy. Of these, 19 are transitions previously detected in the
interstellar medium, and we have made tentative assignments of a further 23
features to molecular transitions. However, as many of these involve molecules
not previously detected in the ISM, these assignments cannot be regarded with
confidence. Given the median line width of 6.5 km/s in Sgr B2 LMH, we find that
the spectra have reached a level where there is line confusion, with about 1/5
of the band being covered with lines. Although we did not confidently detect
either glycine or propylene oxide, we can set 3 sigma upper limits for most
transitions searched. We also show that if glycine is present in the Sgr B2 LMH
at the level of N = 4 x 10^{14} cm^{-2} found by Kuan et al. (2003) in their
reported detection of glycine, it should have been easily detected with the
ATCA synthesized beam size of 17.0 x 3.4 arcsec^{2}, if it were confined to the
scale of the LMH continuum source (< 5 arcsec). This thus puts a strong upper
limit on any small-scale glycine emission in Sgr B2, for both of conformers I
and II.Comment: 12 pages, 2 figures, 5 tables, accepted by MNRA
Health Research Participants' Preferences for Receiving Research Results
BACKGROUND: Participants in health research studies typically express interest in receiving results from the studies in which they participate. However, participants’ preferences and experiences related to receiving results are not well understood. In general, existing studies have had relatively small sample sizes and typically address specific and often sensitive issues within targeted populations. METHODS: The present study used an online survey to explore attitudes and experiences of registrants in ResearchMatch, a large database of past, present, and potential health research participants. Survey respondents provided information related to whether or not they received research results from studies in which they participated, the methods used to communicate results, their satisfaction with results, and when and how they would like to receive research results from future studies. 70,699 ResearchMatch registrants were notified of the study’s topic. Of the 5,207 registrants who requested full information about the study, 3,381 respondents completed the survey. RESULTS: Approximately 33% of respondents with previous health research participation reported receiving results. Approximately half of respondents with previous research participation reported no opportunity to request results. However, almost all respondents said researchers should always or sometimes offer results to participants. Respondents expressed particular interest in results related to their (or a loved one's) health, as well as information about studies’ purposes and any medical advances based on the results. In general, respondents’ most preferred dissemination methods for results were email and website postings. The least desirable dissemination methods for results included Twitter, conference calls, and text messages. Across all results, we compare the responses of respondents with and without previous research participation experience, and those who have worked in research organizations vs. those who have not. Compared to respondents who have previous participation experience, a greater proportion of respondents with no participation experience indicated that results should always be shared with participants. Likewise, respondents with no participation experience placed higher importance on the receipt of each type of results information included in the survey. CONCLUSIONS: We present findings from a survey assessing attitudes and experiences of a broad sample of respondents that addresses gaps in knowledge related to participants’ preferences for receiving results. The study’s findings highlight the potential for inconsistency between respondents’ expressed preferences to receive specific types of results via specific methods and researchers’ unwillingness or inability to provide them. We present specific recommendations to shift the approach of new studies to investigate participants’ preferences for receiving research results
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