23,085 research outputs found
AGRICULTURAL AND RECREATIONAL IMPACTS FROM SURFACE FLOW CHANGES DUE TO GOLD MINING OPERATIONS
Nevada ranks third in the world in gold production. In order to operate the massive open pit gold mines, the State of Nevada granted mining companies a temporary permit to pump groundwater from near the open pits and dispose of it. Certain instream flows have nearly doubled relative to average historical flows in recent years. Following pit closure, surface flows will likely decline from historical levels. This study measures the impacts of these changing water supplies on downstream agricultural and recreational users. We argue that the creation of temporary changes in water rights for the downstream users would likely mitigate future losses both groups are expected to experience.Resource /Energy Economics and Policy,
GLM+ Delivers Improved Natural Resource Management and Production Outcomes to Extensive Grazing Properties in the Savannas of Semi-Arid North Queensland, Australia
Native pastures are the main feed resource on extensive cattle grazing properties (each usually \u3e25,000 ha) in the savannas of semi-arid north Australia and it is widely accepted that condition of many important land types is declining. A wealth of resource information is publicly available but it is usually complex in nature, diffuse and not presented in terms readily understood by land managers. Extension agencies have also moved towards information delivery using group processes that are not readily accepted by remote land managers. The GLM+ program uses concepts and tools from the Grazing Land Management (GLM) workshop (Chilcott et al., 2003) and also incorporates and builds on producer experience. It is delivered on-property to individual management teams who identify their own resources, the condition of those resources, and opportunities to manage for improved land condition. Its use is described in this paper
X-ray emission mechanisms in accreting white dwarfs
In this chapter we consider the processes which can lead to X-ray emission
from different types of cataclysmic variable stars (CVs). CVs are
semi-detached, binary star systems where material is transferred from the donor
star (also known as the companion or secondary star) onto the white dwarf
primary. CVs are divided into several sub-classes based on the observed
phenomenology in the optical and X-ray bands, which, in turn, is largely
defined by the magnetic field strength of the accretor. In non-magnetic
systems, a variety of observed behaviours are identified, depending on the
accretion rate: novae, dwarf novae, nova-like variables, symbiotic binaries and
supersoft sources are all examples of non-magnetic CVs. In magnetic systems
(polars and intermediate polars, or AM Her and DQ Her systems, respectively),
the accretion flow is channelled to polar regions, and the observational
appearance is different. X-rays are typically produced through hot or energetic
processes, and in CVs they are formed via shocks (within a boundary layer or
accretion column, or through interactions either internal to the nova ejecta,
or between the ejecta and a stellar wind) or from hydrogen burning (either
steady fusion, or a thermonuclear runaway). All of these different types of
accreting white dwarfs are discussed here, considering both spectral and
temporal variability in the different populations.Comment: 48 pages (though pages 36 onwards consist entirely of references, due
to a poorly designed style file!), 15 figures. Invited (and accepted) chapter
for the Handbook of X-ray and Gamma-ray Astrophysic
Neural superposition and oscillations in the eye of the blowfly
Neural superposition in the eye of the blowfly Calliphora erythrocephala was investigated by stimulating single photoreceptors using corneal neutralization through water immersion. Responses in Large Monopolar Cells (LMCs) in the lamina were measured, while stimulating one or more of the six photoreceptors connected to the LMC. Responses to flashes of low light intensity on individual photoreceptors add approximately linearly at the LMC. Higher intensity light flashes produce a maximum LMC response to illumination of single photoreceptors which is about half the maximum response to simultaneous illumination of the six connecting photoreceptors. This observation indicates that a saturation can occur at a stage of synaptic transmission which precedes the change in the post-synaptic membrane potential.
Stimulation of single photoreceptors yields high frequency oscillations (about 200 Hz) in the LMC potential, much larger in amplitude than produced by simultaneous stimulation of the six photoreceptors connected to the LMC. It is discussed that these oscillations also arise from a mechanism that precedes the change in the postsynaptic membrane potential.
Brief for Appellant Second Annual Benton National Moot Court Competition Briefs, 17 J. Marshall L. Rev. 1005 (1984)
Recommended from our members
Evolutionary bi-stability in pathogen transmission mode
Many pathogens transmit to new hosts by both infection (horizontal transmission) and transfer to the
infected host's offspring (vertical transmission). These two transmission modes require speci®c adap-
tations of the pathogen that can be mutually exclusive, resulting in a trade-off between horizontal and
vertical transmission. We show that in mathematical models such trade-offs can lead to the simultaneous
existence of two evolutionary stable states (evolutionary bi-stability) of allocation of resources to the two
modes of transmission. We also show that jumping between evolutionary stable states can be induced by
gradual environmental changes. Using quantitative PCR-based estimates of abundance in seed and vege-
tative parts, we show that the pathogen of wheat, Phaeosphaeria nodorum, has jumped between two
distinct states of transmission mode twice in the past 160 years, which, based on published evidence,
we interpret as adaptation to environmental change. The ®nding of evolutionary bi-stability has impli-
cations for human, animal and other plant diseases. An ill-judged change in a disease control
programme could cause the pathogen to evolve a new, and possibly more damaging, combination of
transmission modes. Similarly, environmental changes can shift the balance between transmission
modes, with adverse effects on human, animal and plant health
High-efficiency WSi superconducting nanowire single-photon detectors for quantum state engineering in the near infrared
We report on high-efficiency superconducting nanowire single-photon detectors
based on amorphous WSi and optimized at 1064 nm. At an operating temperature of
1.8 K, we demonstrated a 93% system detection efficiency at this wavelength
with a dark noise of a few counts per second. Combined with cavity-enhanced
spontaneous parametric down-conversion, this fiber-coupled detector enabled us
to generate narrowband single photons with a heralding efficiency greater than
90% and a high spectral brightness of
photons/(smWMHz). Beyond single-photon generation at large rate,
such high-efficiency detectors open the path to efficient multiple-photon
heralding and complex quantum state engineering
Events leading up to the June 2015 outburst of V404 Cyg
On 2015 June 15 the burst alert telescope (BAT) on board {\em Swift} detected
an X-ray outburst from the black hole transient V404 Cyg. We monitored V404 Cyg
for the last 10 years with the 2-m Faulkes Telescope North in three optical
bands (V, R, and i). We found that, one week prior to this outburst, the
optical flux was 0.1--0.3 mag brighter than the quiescent orbital modulation,
implying an optical precursor to the X-ray outburst. There is also a hint of a
gradual optical decay (years) followed by a rise lasting two months prior to
the outburst. We fortuitously obtained an optical spectrum of V404 Cyg 13 hours
before the BAT trigger. This too was brighter () than
quiescence, and showed spectral lines typical of an accretion disk, with
characteristic absorption features of the donor being much weaker. No He II
emission was detected, which would have been expected had the X-ray flux been
substantially brightening. This, combined with the presence of intense
H emission, about 7 times the quiescent level, suggests that the disk
entered the hot, outburst state before the X-ray outburst began. We propose
that the outburst is produced by a viscous-thermal instability triggered close
to the inner edge of a truncated disk. An X-ray delay of a week is consistent
with the time needed to refill the inner region and hence move the inner edge
of the disk inwards, allowing matter to reach the central BH, finally turning
on the X-ray emission.Comment: Accepted by ApJ Letter, 7 pages, 5 figure
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