54,187 research outputs found
Catching crabs: a case study in local-scale English conservation
Wells-next-the-Sea and Cromer in Norfolk (England) both rely upon their local
crab populations, since crabbing (gillying) is a major part of their tourist
industry. Compared to a control site with no crabbing, crabs from Wells harbour
and Cromer pier were found to have nearly six times the amount of limb damage.
Crabs caught by the general public had more injuries than crabs caught in
controlled conditions, suggesting the buckets in which the crabs were kept were
to blame. Since there is much evidence that such injuries have negative impacts
on the survival and reproductive success of the shore crab, this is taken as
evidence of non-lethal injury from humans having a population-level effect on
these animals. Questionnaire data demonstrated a public lack of awareness and
want for information, which was then used to obtain funding to produce a
leaflet campaign informing the public of how to crab responsibly. All data
collected is available online at http://dx.doi.org/10.6084/m9.figshare.979288
Radio Images of 3C 58: Expansion and Motion of its Wisp
New 1.4 GHz VLA observations of the pulsar-powered supernova remnant 3C 58
have resulted in the highest-quality radio images of this object to date. The
images show filamentary structure over the body of the nebula. The present
observations were combined with earlier ones from 1984 and 1991 to investigate
the variability of the radio emission on a variety of time-scales. No
significant changes are seen over a 110 day interval. In particular, the upper
limit on the apparent projected velocity of the wisp is 0.05c. The expansion
rate of the radio nebula was determined between 1984 and 2004, and is
0.014+/-0.003%/year, corresponding to a velocity of 630+/-70 km/s along the
major axis. If 3C 58 is the remnant of SN 1181, it must have been strongly
decelerated, which is unlikely given the absence of emission from the supernova
shell. Alternatively, the low expansion speed and a number of other arguments
suggest that 3C 58 may be several thousand years old and not be the remnant of
SN 1181.Comment: 12 pages; accepted for publication in the Astrophysical Journa
Momentum Analyticity and Finiteness of the 1-Loop Superstring Amplitude
The Type II Superstring amplitude to 1-loop order is given by an integral of
-functions over the moduli space of tori, which diverges for real
momenta. We construct the analytic continuation which renders this amplitude
well defined and finite, and we find the expected poles and cuts in the complex
momentum plane.Comment: 10pp, /UCLA/93/TEP/
Continental-scale patterns of pathogen prevalence: a case study on the corncrake
Pathogen infections can represent a substantial threat to wild populations, especially those already limited in size. To determine how much variation in the pathogens observed among fragmented populations is caused by ecological factors, one needs to examine systems where host genetic diversity is consistent among the populations, thus controlling for any potentially confounding genetic effects. Here, we report geographic variation in haemosporidian infection among European populations of corncrake. This species now occurs in fragmented populations, but there is little genetic structure and equally high levels of genetic diversity among these populations. We observed a longitudinal gradient of prevalence from western to Eastern Europe negatively correlated with national agricultural yield, but positively correlated with corncrake census population sizes when only the most widespread lineage is considered. This likely reveals a possible impact of local agriculture intensity, which reduced host population densities in Western Europe and, potentially, insect vector abundance, thus reducing the transmission of pathogens. We conclude that in the corncrake system, where metapopulation dynamics resulted in variations in local census population sizes, but not in the genetic impoverishment of these populations, anthropogenic activity has led to a reduction in host populations and pathogen prevalence
A Review of the Monitoring of Market Power The Possible Roles of TSOs in Monitoring for Market Power Issues in Congested Transmission Systems
The paper surveys the literature and publicly available information on market power monitoring in electricity wholesale markets. After briefly reviewing definitions, strategies and methods of mitigating market power we examine the various methods of detecting market power that have been employed by academics and market monitors/regulators. These techniques include structural and behavioural indices and analysis as well as various simulation approaches. The applications of these tools range from spot market mitigation and congestion management through to long-term market design assessment and merger decisions. Various market-power monitoring units already track market behaviour and produce indices. Our survey shows that these units collect a large amount of data from various market participants and we identify the crucial role of the transmission system operators with their access to dispatch and system information. Easily accessible and comprehensive data supports effective market power monitoring and facilitates market design evaluation. The discretion required for effective market monitoring is facilitated by institutional independence.Electricity, liberalisation, market power, regulation
Study of cosmic rays above 0.3 EeV using Flyâs Eyeâmuon array coincidence
The Flyâs Eye (FE) and the Michigan Muon Array (MA) simultaneously detect Extensive Air Showers (EAS) from EeV Enrgy primaries. Combining data from both experiments during analysis yields a reliable measurement of Depth of Shower Maximum (Xmax), and gives a measurement of the Muon Lateral Distribution (MLD)<1km from the Shower core. The MLD densities agree with previously measured values.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87434/2/184_1.pd
The unusual distribution of molecular gas and star formation in Arp 140
We investigate the atomic and molecular interstellar medium and star
formation of NGC 275, the late-type spiral galaxy in Arp 140, which is
interacting with NGC 274, an early-type system. The atomic gas (HI)
observations reveal a tidal tail from NGC 275 which extends many optical radii
beyond the interacting pair. The HI morphology implies a prograde encounter
between the galaxy pair approximately 1.5 x 10**8 years ago. The Halpha
emission from NGC 275 indicates clumpy irregular star-formation, clumpiness
which is mirrored by the underlying mass distribution as traced by the Ks-band
emission. The molecular gas distribution is striking in its anti-correlation
with the {HII regions. Despite the evolved nature of NGC 275's interaction and
its barred potential, neither the molecular gas nor the star formation are
centrally concentrated. We suggest that this structure results from stochastic
star formation leading to preferential consumption of the gas in certain
regions of the galaxy. In contrast to the often assumed picture of interacting
galaxies, NGC 275, which appears to be close to merger, does not display
enhanced or centrally concentrated star formation. If the eventual merger is to
lead to a significant burst of star formation it must be preceded by a
significant conversion of atomic to molecular gas as at the current rate of
star formation all the molecular gas will be exhausted by the time the merger
is complete.Comment: 13 paper, accepted my Monthly Notices of the Royal Astronomical
Societ
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