71,668 research outputs found
Freshwater fish and crayfish communities of the tributaries of the Margaret River
Tributaries and headwaters of major rivers are known to be important spawning and nursery habitats of freshwater endemic fishes in south-western Australia (see for example the Collie River in Pen & Potter 1990, and the Blackwood River in Beatty et al. 2006, 2008). Fishes of the Margaret River have previously been examined by Morgan et al. (1998) and Morgan & Beatty (2003) with the monitoring of the functioning of the two fishways on the river documented in Morgan & Beatty (2004, 2007) and Beatty & Morgan (2008). The river is known to be of conservation importance due to it housing five of the eight endemic freshwater fishes of the south-west region, as well as housing the majority (five of the six species) of the Cherax species of freshwater crayfishes found in the south-west; including the Margaret River endemic Critically Endangered Hairy Marron.
Despite this known value and considerable volume of research on the fishes in the main channel of the Margaret River, little is known on the fishes and freshwater crayfishes of the river 19s major tributaries. The aim of this study is to document the freshwater fish distribution in the major tributaries of the Margaret River (i.e. Bramley, Darch, and Yalgardup Brooks) during or close to the breeding period for the majority of the species and to provide a broad assessment and comparison of population demographics of the different species in the different tributaries. This information is required for the formulation of River Action Plans for these systems by the Cape to Cape Catchments Group
Groundbased near-IR observations of the surface of Venus
We present images of the nightside of Venus taken in the near-infrared windows at 1.0, 1.1, 1.18, 1.28, 1.31, and 2.3 microns with the new infrared camera/spectrometer IRIS on the Anglo-Australian Telescope. These data were taken in spectral-mapping mode. This technique involves scanning the telescope perpendicular to the slit, while collecting spectra at successive slit positions across the planet. We produce data cubes with one spectral and two spatial dimensions. Images can be extracted over any wavelength regions. Each image has square pixels of 0.8 inch resolution. We reduced the scattered light from the sunlit crescent in images extracted from each window by subtracting images taken on either side of the window, where the Venus atmosphere is opaque. Unlike the short wavelength windows, which reveal thermal contrasts that originate primarily from the surface and deep atmosphere, the emission in the 2.3 microns window is produced at much higher altitudes (30-40 km). Emission contrasts seen near 2.3 microns are associated with horizontal variations in the cloud optical depths, and have rotation periods of about six days. We detect large contrasts in infrared emission (20-40 percent) across the disc of Venus in the 1.0-, 1.1-, 1.18-, 1.28-, and 1.31-micron images. Contrasts at these wavelengths may be due to a combination of variations in the optical depths of the overlying sulfuric acid clouds and differences in surface emission. Comparison with the 2.3-micron images show that the patterns seen in the 1.28- and 1.31-micron windows are consistent with cloud optical depth variations alone and require no contribution from the surface. However, images at 1.0, 1.1, and 1.8 microns from July 1991 show a dark feature having a contrast that increases with decreasing wavelength. This behavior is contrary to that expected of cloud absorption. Images taken on three successive days in October show another dark feature that is stationary with respect to the surface. These regions of lower emission correspond closely to the high-altitude surface regions of Beta Regio and Aphrodite Terra. The images can potentially reveal the near-infrared emissiveity of the surface of Venus, thereby complementing Magellan radar reflectivity and ground based radio emissivity measurements. The contrast ratio between highlands and plains is much smaller than would be expected for blackbody radiation from the surface along. Unlike at radio wavelengths, where the atmosphere is essentially transparent, at near-infrared wavelengths the atmosphere emits, absorbs, and scatters radiation, and can modify the observed topographically induced contrasts. The additional radiation from the atmosphere reduces the contrast, and further modification would be expected if terrain at different altitudes has different emissivities. A fit to our data therefore requires, and may constrain, a model of the lowest scale height of the atmosphere
Competitive comparison in music: influences upon self-efficacy beliefs by gender
This study profiles gender differences in instrumental performance self-efficacy perceptions of high school students (Nâ=â87) over the course of a three-day orchestra festival in which students competed against one another for rank-based seating and then rehearsed and performed as a group. Reported self-beliefs rose significantly for the sample over the course of the festival. Self-efficacy beliefs of females were significantly lower than those of males before the seating audition and first rehearsal, but were no longer different by the midpoint of the festival. Survey free-response data were coded according to Bandura's (1997 Bandura, A. 1997. Self-efficacy: The Exercise of Control. New York: W. H. Freeman.) four sources of self-efficacy. A 52% drop in the frequency of student comments regarding competitive comparison appeared at the same point in which female self-efficacy beliefs were no longer different from those of males. Results support past research to suggest that males and females may respond differently to rank-based competition versus social support
Oxygen Absorption in Cooling Flows
The inhomogeneous cooling flow scenario predicts the existence of large
quantities of gas in massive elliptical galaxies, groups, and clusters that
have cooled and dropped out of the flow. Using spatially resolved, deprojected
X-ray spectra from the ROSAT PSPC we have detected strong absorption over
energies ~0.4-0.8 keV intrinsic to the central ~1 arcmin of the galaxy, NGC
1399, the group, NGC 5044, and the cluster, A1795. These systems have amongst
the largest nearby cooling flows in their respective classes and low Galactic
columns. Since no excess absorption is indicated for energies below ~0.4 keV
the most reasonable model for the absorber is warm, collisionally ionized gas
with T=10^{5-6} K where ionized states of oxygen provide most of the
absorption. Attributing the absorption only to ionized gas reconciles the large
columns of cold H and He inferred from Einstein and ASCA with the lack of such
columns inferred from ROSAT, and also is consistent with the negligible atomic
and molecular H inferred from HI, and CO observations of cooling flows. The
prediction of warm ionized gas as the product of mass drop-out in these and
other cooling flows can be verified by Chandra, XMM, and ASTRO-E.Comment: 4 pages (2 figures), Accepted for publication in ApJ Letters, no
significant changes from previous submitted versio
Vacuum polarization near cosmic string in RS2 brane world
Gravitational field of cosmic strings in theories with extra spatial
dimensions must differ significantly from that in the Einstein's theory. This
means that all gravity induced properties of cosmic strings need to be revised
too. Here we consider the effect of vacuum polarization outside a straight
infinitely thin cosmic string embedded in a RS2 brane world. Perturbation
technique combined with the method of dimensional regularization is used to
calculate for a massless scalar field.Comment: 8 pages, RevTeX
Micro-Structured Ferromagnetic Tubes for Spin Wave Excitation
Micron scale ferromagnetic tubes placed on the ends of ferromagnetic CoTaZr
spin waveguides are explored in order to enhance the excitation of Backward
Volume Magnetostatic Spin Waves. The tubes produce a closed magnetic circuit
about the signal line of the coplanar waveguide and are, at the same time,
magnetically contiguous with the spin waveguide. This results in a 10 fold
increase in spin wave amplitude. However, the tube geometry distorts the
magnetic field near the spin waveguide and relatively high biasing magnetic
fields are required to establish well defined spin waves. Only the lowest
(uniform) spin wave mode is excited.Comment: 3 pages, 3 figure
Analysis of ZDDP content and thermal decomposition in motor oils using NAA and NMR
Zinc dialkyldithiophosphates (ZDDPs) are one of the most common anti-wear
additives present in commercially-available motor oils. The ZDDP concentrations
of motor oils are most commonly determined using inductively coupled plasma
atomic emission spectroscopy (ICP-AES). As part of an undergraduate research
project, we have determined the Zn concentrations of eight
commercially-available motor oils and one oil additive using neutron activation
analysis (NAA), which has potential for greater accuracy and less sensitivity
to matrix effects as compared to ICP-AES. The 31P nuclear magnetic resonance
(31P-NMR) spectra were also obtained for several oil additive samples which
have been heated to various temperatures in order to study the thermal
decomposition of ZDDPs.Comment: Manuscript has been accepted for publication in Physics Procedia as
part of the proceedings of the 23rd International Conference on Application
of Accelerators in Research and Industry (CAARI 2014
Remote Detection of Saline Intrusion in a Coastal Aquifer Using Borehole Measurements of Self-Potential
Funded by NERC CASE studentship . Grant Number: NE/I018417/1Peer reviewedPublisher PD
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