6,811 research outputs found
Response analysis of an automobile shipping container
The design and development of automobile shipping containers to reduce enroute damage are discussed. Vibration tests were conducted to determine the system structural integrity. A dynamic analysis was made using NASTRAN and the results of the test and the analysis are compared
Near infrared spectroscopy for fibre based gas detection
Gas sensing systems based on fibre optic linked near infra red absorption cells are potentially a flexible and effective tool for monitoring accumulations of hazardous and noxious gases in enclosed areas such as tunnels and mines. Additionally the same baseline technology is readily modified to measure concentrations of hydrocarbon fuels - notably but not exclusively methane, and monitoring emissions of greenhouse gases. Furthermore the system can be readily implemented to provide intrinsically safe monitoring over extensive areas at up to ~250 points from a single interrogation unit. In this paper we review our work on fibre coupled gas sensing systems. We outline the basic principles through which repeatable and accurate self calibrating gas measurements may be realised, including the recover of detailed line shapes for non contact temperature and / or pressure measurements in addition to concentration assessments in harsh environments. We also outline our experience in using these systems in extensive networks operating under inhospitable conditions over extended periods extending to several years
The Infrared and Radio Fluxes Densities of Galactic HII Regions
We derive infrared and radio flux densities of all ~1000 known Galactic HII
regions in the Galactic longitude range 17.5 < l < 65 degree. Our sample comes
from the Wide-Field Infrared Survey Explorer (WISE) catalog of Galactic \hii
regions \citep{anderson2014}. We compute flux densities at six wavelengths in
the infrared (GLIMPSE 8 microns, WISE 12 microns and 22 microns, MIPSGAL 24
microns, and Hi-GAL 70 microns and 160 microns) and two in the radio (MAGPIS 20
cm and VGPS 21 cm). All HII region infrared flux densities are strongly
correlated with their ~20 cm flux densities. All HII regions used here,
regardless of physical size or Galactocentric radius, have similar infrared to
radio flux density ratios and similar infrared colors, although the smallest
regions (pc), have slightly elevated IR to radio ratios. The colors
and , and and reliably select
HII regions, independent of size. The infrared colors of ~22 of HII
regions, spanning a large range of physical sizes, satisfy the IRAS color
criteria of \citet{wood1989} for HII regions, after adjusting the criteria to
the wavelengths used here. Since these color criteria are commonly thought to
select only ultra-compact HII regions, this result indicates that the true
ultra-compact HII region population is uncertain. Comparing with a sample of IR
color indices from star-forming galaxies, HII regions show higher
ratios. We find a weak trend of
decreasing infrared to ~20 cm flux density ratios with increasing , in
agreement with previous extragalactic results, possibly indicating a decreased
dust abundance in the outer Galaxy.Comment: 27 pages, 16 figures, 5 table
Dynamics of Dense Cores in the Perseus Molecular Cloud
We survey the kinematics of over one hundred and fifty candidate (and
potentially star-forming) dense cores in the Perseus molecular cloud with
pointed N2H+(1-0) and simultaneous C18O(2-1) observations. Our detection rate
of N2H+ is 62%, rising to 84% for JCMT SCUBA-selected targets. In agreement
with previous observations, we find that the dense N2H+ targets tend to display
nearly thermal linewidths, particularly those which appear to be starless
(using Spitzer data), indicating turbulent support on the small scales of
molecular clouds is minimal. For those N2H+ targets which have an associated
SCUBA dense core, we find their internal motions are more than sufficient to
provide support against the gravitational force on the cores. Comparison of the
N2H+ integrated intensity and SCUBA flux reveals fractional N2H+ abundances
between 10^-10 and 10^-9. We demonstrate that the relative motion of the dense
N2H+ gas and the surrounding C18O gas is less than the sound speed in the vast
majority of cases (~90%). The point-to-point motions we observe within larger
extinction regions appear to be insufficient to provide support against
gravity, although we sparsely sample these regions.Comment: 49 pages, 20 figures. Accepted for publication in the Astrophysical
Journa
Effects of Elevated Temperature on Gonadal Functions, Cellular Apoptosis, and Oxidative Stress in Atlantic Sea Urchin (Arbacia punctulata)
Increasing surface sea water temperatures effect on growth, reproduction and development in marine organisms. Sea urchins are excellent indicator species and ideal model organisms to focus on. In this study, I tested the effect of higher temperatures on reproductive functions, heat shock protein (HSP, a chaperone protein produced by cells in response to heat stress) and nitrotyrosine protein (NTP, an indicator of reactive nitrogen species, RNS) expressions, cellular apoptosis, and ceolomic fluid (CF, a body fluid which regulates important physiological processes) conditions in Atlantic sea urchin at three different temperatures. Ten sea urchins were placed in each of six aquariums with temperatures of 24 °C (Control), 28 and 32 °C (Higher temperatures) under controlled laboratory conditions for 7 days. Collectively, the results suggest that elevated water temperature acidify CF pH, and increase oxidative stress and cellular apoptosis which might be involved in the impairment of reproductive functions in Atlantic sea urchin
How sex-biased dispersal affects conflict over parental investment
This article is a preprint and has not been peer-reviewed. It is availble from bioRxiv via the DOI in this record.Existing models of parental investment have mainly focused on interactions at the level
of the family, and have paid much less attention to the impact of population-level processes.
Here we extend classical models of parental care to assess the impact of population structure
and limited dispersal. We find that sex-differences in dispersal substantially affect the
amount of care provided by each parent, with the more philopatric sex providing the majority
of the care to young. This effect is most pronounced in highly viscous populations: in
such cases, when classical models would predict stable biparental care, inclusion of a modest
sex difference in dispersal leads to uniparental care by the philopatric sex. In addition,
mating skew also affects sex-differences in parental investment, with the more numerous
sex providing most of the care. However, the effect of mating skew only holds when parents
care for their own offspring. When individuals breed communally, we recover the previous
finding that the more philopatric sex provides most of the care, even when it is the rare sex.
Finally, we show that sex-differences in dispersal can mask the existence of sex-specific
costs of care, because the philopatric sex may provide most of the care even in the face
of far higher mortality costs relative to the dispersing sex. We conclude that sex-biased
dispersal is likely to be an important, yet currently overlooked driver of sex-differences in
parental care.We would like to thank the other members of the Transgen group, Tom
Ezard, Stuart Townley and Jonathan Wells for discussion. The Dutch Academy of Arts and
Sciences (KNAW) and the Lorentz Centre at the University of Leiden, the Netherlands, funded
a week-long workshop on nongenetic effects that contributed to this paper. The authors acknowledge
the use of the UCL Legion High Performance Computing Facility (Legion@UCL),
and associated support services, in the completion of this work. This study was funded by an
EPSRC sandpit grant on transgenerational effects, grant number EP/H031928/1 awarded to RAJ
and an EPSRC-funded 2020 Science fellowship awarded to BK (grant number EP/I017909/1)
Partnership is alive and underpinning healthcare delivery
YesBryan McIntosh, senior lecturer in health management and organisational behaviour at the University of Bradford, explores the role of partnerships in the health service
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