579 research outputs found
Max E. G. Bartels and the Javan lapwing Vanellus macropterus
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Prospects for SIMPLE 2000: A large-mass, low-background Superheated Droplet Detector for WIMP searches
SIMPLE 2000 (Superheated Instrument for Massive ParticLE searches) will
consist of an array of eight to sixteen large active mass ( g)
Superheated Droplet Detectors(SDDs) to be installed in the new underground
laboratory of Rustrel-Pays d'Apt. Several factors make of SDDs an attractive
approach for the detection of Weakly Interacting Massive Particles (WIMPs),
namely their intrinsic insensitivity to minimum ionizing particles, high
fluorine content, low cost and operation near ambient pressure and temperature.
We comment here on the fabrication, calibration and already-competitive first
limits from SIMPLE prototype SDDs, as well as on the expected immediate
increase in sensitivity of the program, which aims at an exposure of 25
kg-day during the year 2000. The ability of modest-mass fluorine-rich detectors
to explore regions of neutralino parameter space beyond the reach of the most
ambitious cryogenic projects is pointed out.Comment: 19 pages, 10 figures included. New Journal of Physics, in pres
Halo independent comparison of direct dark matter detection data
We extend the halo-independent method of Fox, Liu, and Weiner to include
energy resolution and efficiency with arbitrary energy dependence, making it
more suitable for experiments to use in presenting their results. Then we
compare measurements and upper limits on the direct detection of low mass
( GeV) weakly interacting massive particles with spin-independent
interactions, including the upper limit on the annual modulation amplitude from
the CDMS collaboration. We find that isospin-symmetric couplings are severely
constrained both by XENON100 and CDMS bounds, and that isospin-violating
couplings are still possible at the lowest energies, while the tension of the
higher energy CoGeNT bins with the CDMS modulation constraint remains. We find
the CRESST II signal is not compatible with the modulation signals of DAMA and
CoGeNT.Comment: version slightly longer than the first, with 3 additional figures and
the latest XENON100 bound added. 7 pages, 5 figure
Max E. G. Bartels and the Javan Lapwing Vanellus macropterus
The Javan Lapwing Vanellus macropterus was (and just possibly still is) a bird species endemic to Java, although there is debatable nineteenth century evidence of its occurrence on Sumatra. It has not been seen since 1940, and indeed almost nothing has ever been published on the species (the scant details are assembled in BirdLife Internafional's Threatened birds of Asia, in prep.). However, the Swiss German plantation owner Max E. G. Bartels (1871 1936; see Stresemann 1937, Rozendaal 1981) kept extensive manuscript and typescript notes on Javan birds, which he clearly intended to publish at one stage. These are held at the National Museum of Natural History Naturalis, Leiden, Netherlands. The notes contain an invaluable summary of Bartels's experience of the Javan Lapwing. This material has been selected, condensed and reworked into the entry on the species in Threatened birds of Asia, but because it is a unique record (and because there are items of information which do not concern conservation and were therefore not used in BirdLife's account), we felt it would be worthwhile reproducing the entries in its entirety in the interests of science and posterity. The translation, from German, is ours
Museum DNA reveals the demographic history of the endangered Seychelles warbler
The importance of evolutionary conservation – how understanding evolutionary forces can help guide conservation decisions – is widely recognized. However, the historical demography of many endangered species is unknown, despite the fact that this can have important implications for contemporary ecological processes and for extinction risk. Here, we reconstruct the population history of the Seychelles warbler (Acrocephalus sechellensis) – an ecological model species. By the 1960s, this species was on the brink of extinction, but its previous history is unknown. We used DNA samples from contemporary and museum specimens spanning 140 years to reconstruct bottleneck history. We found a 25% reduction in genetic diversity between museum and contemporary populations, and strong genetic structure. Simulations indicate that the Seychelles warbler was bottlenecked from a large population, with an ancestral Ne of several thousands falling to <50 within the last century. Such a rapid decline, due to anthropogenic factors, has important implications for extinction risk in the Seychelles warbler, and our results will inform conservation practices. Reconstructing the population history of this species also allows us to better understand patterns of genetic diversity, inbreeding and promiscuity in the contemporary populations. Our approaches can be applied across species to test ecological hypotheses and inform conservation
Superheated Microdrops as Cold Dark Matter Detectors
It is shown that under realistic background considerations, an improvement in
Cold Dark Matter sensitivity of several orders of magnitude is expected from a
detector based on superheated liquid droplets. Such devices are totally
insensitive to minimum ionizing radiation while responsive to nuclear recoils
of energies ~ few keV. They operate on the same principle as the bubble
chamber, but offer unattended, continuous, and safe operation at room
temperature and atmospheric pressure.Comment: 15 pgs, 4 figures include
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