7,665 research outputs found
Interstellar Gas in Low Mass Virgo Cluster Spiral Galaxies
We have measured the strengths of the [C II] 158 micron, [N II] 122 micron,
and CO (1 - 0) lines from five low blue luminosity spiral galaxies in the Virgo
Cluster, using the Infrared Space Observatory and the NRAO 12m millimeter
telescope. Two of the five galaxies have high L([C II)]/L(CO) and L(FIR)/L(CO)
ratios compared to higher mass spirals. These two galaxies, NGC 4294 and NGC
4299, have L([C II])/L(CO) ratios of >14,300 and 15,600, respectively, which
are similar to values found in dwarf irregular galaxies. This is the first time
that such enhanced L([C II])/L(CO) ratios have been found in spiral galaxies.
This result may be due to low abundances of dust and heavy elements, which can
cause the CO (1 - 0) measurements to underestimate the molecular gas content.
Another possibility is that radiation from diffuse HI clouds may dominate the
[C II] emission from these galaxies. Less than a third of the observed [C II]
emission arises from HII regions.Comment: 24 pages, Latex, 2 Figures, 6 Tables To appear in the Astronomical
Journal, July 199
The graceful exit in pre-big bang string cosmology
We re-examine the graceful exit problem in the pre-big bang scenario of
string cosmology, by considering the most general time-dependent classical
correction to the Lagrangian with up to four derivatives. By including possible
forms for quantum loop corrections we examine the allowed region of parameter
space for the coupling constants which enable our solutions to link smoothly
the two asymptotic low-energy branches of the pre-big bang scenario, and
observe that these solutions can satisfy recently proposed entropic bounds on
viable singularity free cosmologies.Comment: 14 pages, 6 figures, JHEP class. Added new section on the classical
correction and reference
Individualisation of time-motion analysis : a method comparison and case report series
© Georg Thieme Verlag KG. This study compared the intensity distribution of time-motion analysis data, when speed zones were categorized by different methods. 12 U18 players undertook a routine battery of laboratory- and field-based assessments to determine their running speed corresponding to the respiratory compensation threshold (RCT), maximal aerobic speed (MAS), maximal oxygen consumption (vVO 2max ) and maximal sprint speed (MSS). Players match-demands were tracked using 5 Hz GPS units in 22 fixtures (50 eligible match observations). The percentage of total distance covered running at high-speed (%HSR), very-high speed (%VHSR) and sprinting were determined using the following speed thresholds: 1) arbitrary; 2) individualised (IND) using RCT, vVO 2max and MSS; 3) individualised via MAS per se; 4) individualised via MSS per se; and 5) individualised using MAS and MSS as measures of locomotor capacities (LOCO). Using MSS in isolation resulted in 61 % and 39 % of player's % HSR and % VHSR, respectively, being incorrectly interpreted, when compared to the IND technique. Estimating the RCT from fractional values of MAS resulted in erroneous interpretations of % HSR in 50 % of cases. The present results suggest that practitioners and researchers should avoid using singular fitness characteristics to individualise the intensity distribution of time-motion analysis data. A combination of players' anaerobic threshold, MAS, and MSS characteristics are recommended to individualise player-tracking data
The Nature of the Low-Metallicity ISM in the Dwarf Galaxy NGC 1569
We are modeling the spectra of dwarf galaxies from infrared to submillimeter
wavelengths to understand the nature of the various dust components in
low-metallicity environments, which may be comparable to the ISM of galaxies in
their early evolutionary state. The overall nature of the dust in these
environments appears to differ from those of higher metallicity starbursting
systems. Here, we present a study of one of our sample of dwarf galaxies, NGC
1569, which is a nearby, well-studied starbursting dwarf. Using ISOCAM, IRAS,
ISOPHOT and SCUBA data with the Desert et al. (1990) model, we find consistency
with little contribution from PAHs and Very Small Grains and a relative
abundance of bigger colder grains, which dominate the FIR and submillimeter
wavelengths. We are compelled to use 4 dust components, adding a very cold dust
component, to reproduce the submillimetre excess of our observations.Comment: 4 pages, 4 postscript figures. Proceedings of "Infrared and
Submillimeter Astronomy. An International Colloquium to Honor the Memory of
Guy Serra" (2002
Sonic boom simulation by means of low-pressure sources
Sonic boom simulation by low pressure source
The 158 micron (CII) mapping of galaxies: Probing the atomic medium
Using the MPE/UCB Far-infrared Imaging Fabry-Perot Interferometer (FIFI) on the Kuiper Airborne Observatory (KAO), we have made large scale maps of (CII) in the spiral galaxies NGC 6946, NGC 891, M83 and the peculiar elliptical Cen A, thus allowing for the first time, detailed studies of the spatial distribution of the FIR line emission in external galaxies. We find that the (CII) emission comes from a mixture of components of interstellar gas. The brightest emission is associated with the nuclear regions, a second component traces the spiral arms as seen in the nearly face on spiral galaxies NGC 6946 and M83 and the largest star forming/H2 regions contained within them, and another extended component of low brightness can be detected in all of the galaxies far from the nucleus, beyond the extent of CO emission
Spacecraft instrument calibration and stability
The following topics are covered: instrument degradation; the Solar Backscatter Ultraviolet (SBUV) Experiment; the Total Ozone Mapping Spectrometer (TOMS); the Stratospheric Aerosol and Gas Experiment 1 (SAGE-1) and SAGE-2 instruments; the Solar Mesosphere Explorer (SME) UV ozone and near infrared airglow instruments; and the Limb Infrared Monitor of the Stratosphere (LIMS)
Effect of low-Raman window position on correlated photon-pair generation in a chalcogenide Ge11.5As24Se64.5 nanowire
We investigated correlated photon-pair generation via spontaneous four-wave mixing in an integrated chalcogenideGe11.5As24Se64.5photonicnanowire. The coincidence to accidental ratio, a key measurement for the quality of correlated photon-pair sources, was measured to be only 0.4 when the photon pairs were generated at 1.9 THz detuning from the pump frequency due to high spontaneous Raman noise in this regime. However, the existence of a characteristic low-Raman window at around 5.1 THz in this material's Raman spectrum and dispersion engineering of the nanowire allowed us to generate photon pairs with a coincidence to accidental ratio of 4.5, more than 10 times higher than the 1.9 THz case. Through comparing the results with those achieved in chalcogenide As2S3waveguides which also exhibit a low Raman-window but at a larger detuning of 7.4 THz, we find that the position of the characteristic low-Raman window plays an important role on reducing spontaneous Raman noise because the phonon population is higher at smaller detuning. Therefore the ultimate solution for Raman noise reduction in Ge11.5As24Se64.5 is to generate photon pairs outside the Raman gain band at more than 10 THz detuning
Leading Edge Boundary Layer Suction Device for the Cal Poly Rolling Road Wind Tunnel
Over the course of three quarters from Fall of 2016 to Spring of 2017, our team designed and built a boundary layer suction device. The boundary layer suction device has three main functions: a scoop that redirects most of the boundary layer air out of the wind tunnel, fans that suck the remaining boundary layer air through a porous plate and ducting and out of the wind tunnel, and a transition bridge that transitions the remaining air smoothly onto the rolling road. The wind tunnel is owned by Cal Poly and the rolling road is a new addition to it. By the end of our project, the rolling road was not yet functional. A variable-frequency drive (VFD) will be installed over the summer and belt suction fans will also be installed. Once these are in place, the rolling road can be used.
We were successful in building our device and installing it, but once the rolling road is functional, further iterations can be made on our device. The framing and ducting will likely stay in place without further iterations. However, which fans are used can be changed around. We designed our device with an American Fan model AF-10 in mind, but this fan cannot be used until the VFD is installed. There are other fans that can be repurposed and tested on this device as well, though. And, if necessary, a more powerful fan could be purchased.
The lid, consisting of the scoop, porous plate, and transition bridge, was also designed to be flexible enough for further iterations. All three of its components are separate pieces that fasten to each other and the lid itself is separate from the rest of the assembly and is only meant to attach to it during tests. Two issues could crop up with the scoop: less air than expected being redirected through the scoop, and the scoop creating flow separation. If the latter issue occurs, a new scoop could be made with the angle (currently 10 degrees) reduced. If the former issue occurs, a new scoop could be made with longer overhang, or ducting could be made from where the flow is redirected, to the end of the tunnel.
The following report details the process we went through to make this device. It provides details on the design process, final design analysis, manufacturing results, and test plans that show our progress from project ideation all the way to design acceptance and verification
"Always paracetamol, they give them paracetamol for everything": a qualitative study examining Eastern European migrants' experiences of the UK health service.
BACKGROUND: The enlargement of the European Union since 2004 has led to an increase in the number of Eastern European migrants living in the UK. The health of this group is under-researched though some mixed evidence shows they are at higher risk of certain physical health conditions such as heart attacks, strokes, HIV and alcohol use and have poorer mental health. This is compounded by poor or insecure housing, low pay, isolation and prejudice. We aimed to understand the health needs and health service experiences of the Eastern European population in a town in Northern England. METHODS: Five semi structured one-to-one and small group interviews and five focus groups were conducted with 42 Eastern European participants between June and September 2014. The majority of participants were Polish and other participants were from Belarus, Hungary, Latvia, Russia, Slovakia and Ukraine. The data were analysed using thematic framework analysis. RESULTS: Key findings included a good understanding the UK health service structure and high registration and use of general practice/primary care services. However, overall, there were high levels of dissatisfaction, frustration and distrust in General Practitioners (GP). The majority of participants viewed the GP as unhelpful and dismissive; a barrier to secondary/acute care; reluctant to prescribe antibiotics; and that GPs too often advised them to take paracetamol (acetaminophen) and rest. CONCLUSIONS: Overwhelmingly participants had strong opinions about access to primary care and the role of the general practitioners. Although the design of the UK health service was well understood, participants were unhappy with the system of GP as gatekeeper and felt it inferior to the consumer-focused health systems in their country of origin. More work is needed to promote the importance of self-care, reduce antibiotic and medication use, and to increase trust in the GP
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