5,597 research outputs found
Constraining the Anomalous Microwave Emission Mechanism in the S140 Star Forming Region with Spectroscopic Observations Between 4 and 8 GHz at the Green Bank Telescope
Anomalous microwave emission (AME) is a category of Galactic signals that
cannot be explained by synchrotron radiation, thermal dust emission, or
optically thin free-free radiation. Spinning dust is one variety of AME that
could be partially polarized and therefore relevant for ongoing and future
cosmic microwave background polarization studies. The Planck satellite mission
identified candidate AME regions in approximately patches that were
found to have spectra generally consistent with spinning dust grain models. The
spectra for one of these regions, G107.2+5.2, was also consistent with
optically thick free-free emission because of a lack of measurements between 2
and 20 GHz. Follow-up observations were needed. Therefore, we used the C-band
receiver (4 to 8 GHz) and the VEGAS spectrometer at the Green Bank Telescope to
constrain the AME mechanism. For the study described in this paper, we produced
three band averaged maps at 4.575, 5.625, and 6.125 GHz and used aperture
photometry to measure the spectral flux density in the region relative to the
background. We found if the spinning dust description is correct, then the
spinning dust signal peaks at GHz, and it explains the excess
emission. The morphology and spectrum together suggest the spinning dust grains
are concentrated near S140, which is a star forming region inside our chosen
photometry aperture. If the AME is sourced by optically thick free-free
radiation, then the region would have to contain HII with an emission measure
of and a physical extent of
. This result suggests the HII
would have to be ultra or hyper compact to remain an AME candidate.Comment: 21 pages, 14 figures. Submitted to Ap
A Statistical Treatment of the Gamma-Ray Burst "No Host Galaxy" Problem: II. Energies of Standard Candle Bursts
With the discovery that the afterglows after some bursts are coincident with
faint galaxies, the search for host galaxies is no longer a test of whether
bursts are cosmological, but rather a test of particular cosmological models.
The methodology we developed to investigate the original "no host galaxy"
problem is equally valid for testing different cosmological models, and is
applicable to the galaxies coincident with optical transients. We apply this
methodology to a family of models where we vary the total energy of standard
candle bursts. We find that total isotropic energies of E<2e52~erg are ruled
out while log(E)~53 erg is favored.Comment: To appear in Ap.J., 514, 15 pages + 7 figures, AASTeX 4.0. Revisions
are: additional author, updated data, and minor textual change
Soluble tau species, not neurofibrillary aggregates, disrupt neural system integration in a tau transgenic model
Neurofibrillary tangles are a feature of Alzheimer disease and other tauopathies, and while they are generally believed to be markers of neuronal pathology, there is little evidence evaluating whether tangles directly impact neuronal function. To investigate the response of cells in hippocampal circuits to complex behavioral stimuli, we used an environmental enrichment paradigm to induce expression of an immediate-early gene, Arc, in the rTg4510 mouse model of tauopathy. These mice reversibly overexpress P301L tau and exhibit substantial neurofibrillary tangle deposition, neuronal loss, and memory deficits. Employing fluorescent in situ hybridization to detect Arc mRNA, we found that rTg4510 mice have impaired hippocampal Arc expression both without stimulation and in response to environmental enrichment; this likely reflects the combination of functional impairments of existing neurons and loss of neurons. However, tangle-bearing cells were at least as likely as non-tangle-bearing neurons to exhibit Arc expression in response to enrichment. Transgene suppression with doxycycline for 6 weeks resulted in increased percentages of Arc-positive cells in rTg4510 brains compared to untreated transgenics, restoring enrichment-induced Arc mRNA levels to that of wild-type controls despite the continued presence of neurofibrillary pathology. We interpret these data to indicate that soluble tau contributes to impairment of hippocampal function, while tangles do not preclude neurons from responding in a functional circuit
Magnetic field dependence of the internal quality factor and noise performance of lumped-element kinetic inductance detectors
We present a technique for increasing the internal quality factor of kinetic
inductance detectors (KIDs) by nulling ambient magnetic fields with a properly
applied magnetic field. The KIDs used in this study are made from thin-film
aluminum, they are mounted inside a light-tight package made from bulk
aluminum, and they are operated near . Since the thin-film
aluminum has a slightly elevated critical temperature (), it therefore transitions before the package (), which also serves as a magnetic shield. On cooldown, ambient
magnetic fields as small as approximately can produce
vortices in the thin-film aluminum as it transitions because the bulk aluminum
package has not yet transitioned and therefore is not yet shielding. These
vortices become trapped inside the aluminum package below
and ultimately produce low internal quality factors in the thin-film
superconducting resonators. We show that by controlling the strength of the
magnetic field present when the thin film transitions, we can control the
internal quality factor of the resonators. We also compare the noise
performance with and without vortices present, and find no evidence for excess
noise beyond the increase in amplifier noise, which is expected with increasing
loss.Comment: 5 pages, 4 figure
Evaluation of two health status measures in adults with growth hormone deficiency
Objective: To evaluate the psychometric properties of two health status measures for adults with growth hormone deficiency (GHD): Nottingham Health Profile (NHP) and Short Form Health Survey (SF-36).
Design: (1) A cross-sectional survey of adults with treated or untreated GHD, to assess reliability and validity of the questionnaires. (2) A randomised, placebo-controlled study of 3 months’ GH withdrawal from GH-treated adults, to assess the questionnaires’ sensitivity to change.
Patients: (1) Cross-sectional survey of 157 patients with severe GHD (peak GH
Measurements: The NHP and SF-36 were used once in the cross-sectional survey, but twice in the GH-withdrawal study, at baseline and end-point (after 3 months).
Results: (1) Cross-sectional survey. Both questionnaires had high internal consistency reliability with subscale Cronbach’s alphas of > 0.73 (NHP) and > 0.78 (SF 36). Calculation of a NHP Total score, occasionally reported in the literature, was shown to be inadvisable. Overall, patients with GHD were found to have significantly worse perceived functioning than the UK general population in SF 36 subscales of General Health, Pain, Social Functioning, Role-Emotional, Role-Physical, and Vitality. Whilst neither questionnaire found significant differences between GH-treated and non-GH-treated patients, there were correlations with duration of GH treatment (p
Conclusions: The SF-36 is a better measure than the NHP of health status of people with GHD, owing to its greater discriminatory power with ability to detect lesser degrees of disability. It also has superior sensitivity to some sub-group differences and superior sensitivity to change than the NHP. The SF-36 is highly acceptable to respondents, and has very good internal consistency reliability. The SF-36 is recommended to measure the health status of adults with GHD
Sub-Antarctic and High Antarctic Notothenioid Fishes: Ecology and Adaptational Biology Revealed by the ICEFISH 2004 Cruise of RVIB Nathaniel B. Palmer
The goal of the ICEFISH 2004 cruise, which was conducted on board RVIB Nathaniel B. Palmer and traversed the transitional zones linking the South Atlantic to the Southern Ocean, was to compare the evolution, ecology, adaptational biology, community structure, and population dynamics of Antarctic notothenioid fishes relative to the cool/temperate notothenioids of the sub-Antarctic. To place this work in a comprehensive ecological context, cruise participants surveyed the benthos and geology of the biogeographic provinces and island shelves on either side of the Antarctic Polar Front (or Antarctic Convergence). Genome-enabled comparison of the responses of cold-living and temperate notothenioids to heat stress confirmed the sensitivity of the former to a warming Southern Ocean. Successful implementation of the international and interdisciplinary ICEFISH research cruise provides a model for future exploration of the sub-Antarctic sectors of the Indian and Pacific Oceans
The origin of GEMS in IDPs as deduced from microstructural evolution of amorphous silicates with annealing
We present laboratory studies of the micro-structural evolution of an
amorphous ferro-magnesian silicate, of olivine composition, following thermal
annealing under vacuum. Annealing under vacuum was performed at temperatures
ranging from 870 to 1020 K. After annealing spheroidal metallic nano-particles
(2-50 nm) are found within the silicate films. We interpret this microstructure
in terms of a reduction of the initial amorphous silicate FeO component,
because of the carbon-rich partial pressure in the furnace due to pumping
mechanism. Annealing in a controlled oxygen-rich atmosphere confirms this
interpretation. The observed microstructures closely resemble those of the GEMS
(Glass with Embedded Metal and Sulphides) found in chondritic IDPs
(Interplanetary Dust Particles). Since IDPs contain abundant carbonaceous
matter, a solid-state reduction reaction may have occurred during heating in
the hot inner regions of the proto-solar disc. Related to this, the presence of
forsterite grains grown from the amorphous precursor material clearly
demonstrates that condensation from gaseous species is not required to explain
the occurrence of forsterite around young protostars and in comets. Forsterite
grains in these environments can be formed directly in the solid phase by
thermal annealing of amorphous ferro-magnesian silicates under reducing
conditions.Comment: 4 pages, 2 figures. Accepted for publication A&A Letter to the Edito
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