1,442 research outputs found
Results from the CDMS II Experiment
I report recent results and the status of the Cryogenic Dark Matter Search
(CDMS II) experiment at the Soudan Underground Laboratory in Minnesota, USA. A
blind analysis of data taken by 30 detectors between October 2006 and July 2007
found zero events consistent with WIMPs elastically scattering in our Ge
detectors. This resulted in an upper limit on the spin-independent,
WIMP-nucleon cross section of 6.6 x 10^-44 cm^2 (4.6 x 10^-44 cm^2 when
combined with our previous results) at the 90% C.L. for a WIMP of mass 60
GeV/c^2. In March 2009 data taking with CDMS II stopped in order to install the
first of 5 SuperTowers of detectors for the SuperCDMS Soudan project. Analysis
of data taken between August 2007 and March 2009 is ongoing.Comment: 5 pages, 4 figures, to appear in the proceedings of the TAUP09
conference (Rome, July 1st-5th 2009
Moving Beyond Niche Models: Habitat Suitability for Nesting White-Headed Woodpeckers
Ecological niche models of habitat suitability are attractive due to their conceptual interpretation and use of presence-only data. Niche models have potential to exploit a variety of presence-only data sources, such as museum records, limited effort surveys, ancillary field observations, and citizen science programs. Limitations of niche models, however, substantially reduce their utility in management situations, in particular, the inability to independently evaluate habitat covariates for their relative influence. Generalized linear models, i.e., logistic regression, provide this ability, but require both presence and absence data. We present an approach that overcomes the limitation of niche models while retaining the use of presence-only data. The generation of pseudo-absences, derived from areas of low suitability as determined by the niche model, allow use of logistic regression to produce robust models of habitat suitability. The approach also has the added benefit of reducing contamination (false absences) among absence data that occurs with simple random sample approaches. We discuss the pseudo-absence approach in an example of modeling habitat suitability for nesting white-headed woodpeckers (Picoides albolarvatus)
Preconceptual care for couples seeking fertility treatment, an evidence-based approach
There is accumulating evidence demonstrating that positive lifestyle modification and the optimization of the preconceptual period can influence the reproductive potential for both men and women. However, a large percentage of couples attending fertility clinics with potential to improve preconception habits may not always receive appropriate preconceptual advice. In addition, supplements and adjuncts that promise to increase fertility treatment success rates are marketed to infertile patients despite lack of convincing evidence supporting their benefit. This review aims to identify possible associations between lifestyle factors for couples seeking fertility treatment and fertility treatment outcomes and to offer possible explanations of the biological basis of these associations. An electronic search was conducted from 1978 through July 2019 linking preconceptual behaviors for women and men with the outcome of fertility treatment. The literature search explored the importance of numerous factors, including smoking, caffeine, alcohol, obesity, physical exercise, recreational drugs, stress, diet, supplements, alternative medicine, environmental factors, and pollutants. Some associations were found to be more significant than others. The preconceptual period is undeniably a delicate and important window which should not be overlooked during fertility counseling. Simple lifestyle modifications could positively influence fertility treatment outcomes. Fertility teams, consisting of clinicians, fertility nurses, dieticians, psychologists, exercise advisors and others, should dedicate time to offer evidence-based preconceptual advice and targeted interventions to couples seeking fertility treatment
Theoretical Analysis for Obtaining Physical Properties of Composite Electrodes
A theoretical analysis is presented that allows in situ measurements of the physical properties of a composite electrode, namely, the electronic conductivity, the ionic conductivity, the exchange-current density, and the double-layer capacitance. Use is made of the current-voltage responses of the composite electrode to dc and ac polarizations under three different experimental configurations. This analysis allows the physical properties to be obtained even when the various resistances in the composite (e.g., ionic, electronic, and charge-transfer) are of comparable values
Avian Community Response To A Recent Mountain Pine Beetle Epidemic
Recent epidemics of mountain pine beetles (Dendroctonus ponderosae) will fundamentally alter forests of the Intermountain West, impacting management decisions related to fire, logging, and wildlife habitat. We evaluated effects of a recent mountain pine beetle epidemic on site occupancy dynamics of > 60 avian species in four study units dominated by ponderosa pine (Pinus ponderosa) in the Helena National Forest. Point count data were collected during the avian breeding seasons (May-Jul) of 2003-2006 (pre-epidemic) and again during 2009-2010 (post-epidemic). We used a Bayesian hierarchical model that accounts for detection probability to obtain occupancy estimates for rare and elusive species as well as common ones. We estimated occupancy and detection for all species with respect to the occurrence of the beetle outbreak, live tree density at fine scale (1 ha), and live tree density at coarse (landscape) scale (100 ha). Preliminary analyses focus on trends in occupancy for species of interest, such as the American Three-toed Woodpecker (Picoides tridactylus), as well as patterns of occupancy for nesting and foraging guilds. Results indicated diverse responses among species, with occupancy rates increasing for some and declining for others
Effect of implanted metal impurities on superconducting tungsten films
The superconducting transition temperature of more than 30 thin-film tungsten samples was measured using a dilution refrigerator. The samples were fabricated using a 99.999% pure tungsten target and a dc magnetron sputtering system. Individual films were then doped with metal impurity ions using an accurate ion implantation technique. The effect of the metal–ion doping on the superconducting transition temperature was measured for samples with superconducting transitions in the range of 40–150 mK. Magnetic dopant species including Ni, Co, and Fe resulted in suppressed values of the tungsten Tc. The suppression was linear with increasing dopant concentration, for concentrations up to tens of ppm. For higher concentrations of magnetic atoms, the data are consistent with the Abrikosov–Gor\u27kov theory [Soviet Physics JETP 12, 1243 (1961)] modified by antiferromagnetic impurity–impurity interactions. By contrast, tungsten films implanted with Mg or Cr showed little change in Tc after doping. In this article, we present data from cryogenic experiments on these films. We also present x-ray diffraction (XRD) spectra for a subset of the films. Our XRD data confirm that the observed suppression in Tc for the magnetically doped samples is not due to any structural changes (e.g., lattice distortion or damage) induced by the implantation process
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The alpha1 subunit of the GABA(A) receptor modulates fear learning and plasticity in the lateral amygdala.
Synaptic plasticity in the amygdala is essential for emotional learning. Fear conditioning, for example, depends on changes in excitatory transmission that occur following NMDA receptor activation and AMPA receptor modification in this region. The role of these and other glutamatergic mechanisms have been studied extensively in this circuit while relatively little is known about the contribution of inhibitory transmission. The current experiments addressed this issue by examining the role of the GABA(A) receptor subunit alpha1 in fear learning and plasticity. We first confirmed previous findings that the alpha1 subunit is highly expressed in the lateral nucleus of the amygdala. Consistent with this observation, genetic deletion of this subunit selectively enhanced plasticity in the lateral amygdala and increased auditory fear conditioning. Mice with selective deletion of alpha1 in excitatory cells did not exhibit enhanced learning. Finally, infusion of a alpha1 receptor antagonist into the lateral amygdala selectively impaired auditory fear learning. Together, these results suggest that inhibitory transmission mediated by alpha1-containing GABA(A) receptors plays a critical role in amygdala plasticity and fear learning
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