1,533 research outputs found
Collectivity in the optical response of small metal clusters
The question whether the linear absorption spectra of metal clusters can be
interpreted as density oscillations (collective ``plasmons'') or can only be
understood as transitions between distinct molecular states is still a matter
of debate for clusters with only a few electrons. We calculate the
photoabsorption spectra of Na2 and Na5+ comparing two different methods:
quantum fluid-dynamics and time-dependent density functional theory. The
changes in the electronic structure associated with particular excitations are
visualized in ``snapshots'' via transition densities. Our analysis shows that
even for the smallest clusters, the observed excitations can be interpreted as
intuitively understandable density oscillations. For Na5+, the importance of
self-interaction corrections to the adiabatic local density approximation is
demonstrated.Comment: 6 pages, 3 figures. To appear in special issue of Applied Physics B,
"Optical properties of Nanoparticles
Galaxy And Mass Assembly (GAMA): end of survey report and data release 2
The Galaxy And Mass Assembly (GAMA) survey is one of the largest contemporary spectroscopic surveys of low redshift galaxies. Covering an area of Ë286 deg2 (split among five survey regions) down to a limiting magnitude of r < 19.8 mag, we have collected spectra and reliable redshifts for 238 000 objects using the AAOmega spectrograph on the Anglo-Australian Telescope. In addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1 nm-1 m. Here, we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. We also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. Finally, we present the second public release of GAMA data. In this release, we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component SĂ©rsic fits, stellar masses, Hα-derived star formation rates, environment information, and group properties for all galaxies with r < 19.0 mag in two of our survey regions, and for all galaxies with r < 19.4 mag in a third region (72 225 objects in total). The data base serving these data is available at http://www.gama-survey.org/
Use of anabolic implants in calves to increase weaning weight and backgrounding gains
The main component of the beef industry in South Carolina is cow/calf operations. Recent advances in implant technology are being utilized to help these producers increase weights at time of sale to feedlots. The objective of this study was to determine how the use of anabolic implants in steer calves at 4 mo of age and at weaning altered weight gain at two different farm locations in South Carolina. Steers ( year 1; n= 161, year 2 n=116) from Edisto REC and Simpson REC were randomly allotted into two treatment groups: 1) no implant or 2) implant at 4 mo of age plus implant at weaning. Weights were obtained at implanting, weaning, and the end of backgrounding. Real-time ultrasound measurements of the ribeye area and fat thickness were collected at the end of the backgrounding period. Data were analyzed with the treatment, location, year, and the interaction in the model. Implanting the steers increased (P\u3c0.001) average daily gains from implanting to weaning, weaning to the end of the backgrounding, and overall by 0.36, 0.15, 0.25 lb/hd/d respectively. Implanting also increased ribeye area by 0.34 in2. Weight and gains of the steers differed by location and year but there were no interactions between location, year, and implant treatment. The use of anabolic implants in steer calves at 4 mo of age and then again at weaning helped to increase weight gain, other desirable carcass traits and produced heavier steers for marketing
Use of anabolic implants in calves to increase weaning weight and backgrounding gains
The main component of the beef industry in South Carolina is cow/calf operations. Recent advances in implant technology are being utilized to help these producers increase weights at time of sale to feedlots. The objective of this study was to determine how the use of anabolic implants in steer calves at 4 mo of age and at weaning altered weight gain at two different farm locations in South Carolina. Steers ( year 1; n= 161, year 2 n=116) from Edisto REC and Simpson REC were randomly allotted into two treatment groups: 1) no implant or 2) implant at 4 mo of age plus implant at weaning. Weights were obtained at implanting, weaning, and the end of backgrounding. Real-time ultrasound measurements of the ribeye area and fat thickness were collected at the end of the backgrounding period. Data were analyzed with the treatment, location, year, and the interaction in the model. Implanting the steers increased (P\u3c0.001) average daily gains from implanting to weaning, weaning to the end of the backgrounding, and overall by 0.36, 0.15, 0.25 lb/hd/d respectively. Implanting also increased ribeye area by 0.34 in2. Weight and gains of the steers differed by location and year but there were no interactions between location, year, and implant treatment. The use of anabolic implants in steer calves at 4 mo of age and then again at weaning helped to increase weight gain, other desirable carcass traits and produced heavier steers for marketing
Evaluation of the Irritable Bowel Syndrome Quality of Life (IBS-QOL) questionnaire in diarrheal-predominant irritable bowel syndrome patients
Background Diarrhea-predominant irritable bowel syndrome (IBS-d) significantly diminishes the health-related quality of life (HRQOL) of patients. Psychological and social impacts are common with many IBS-d patients reporting comorbid depression, anxiety, decreased intimacy, and lost working days. The Irritable Bowel Syndrome Quality of Life (IBS-QOL) questionnaire is a 34-item instrument developed and validated for measurement of HRQOL in non-subtyped IBS patients. The current paper assesses this previously-validated instrument employing data collected from 754 patients who participated in a randomized clinical trial of a novel treatment, eluxadoline, for IBS-d. Methods Psychometric methods common to HRQOL research were employed to evaluate the IBS-QOL. Many of the historical analyses of the IBS-QOL validations were used. Other techniques that extended the original methods were applied where more appropriate for the current dataset. In IBS-d patients, we analyzed the items and substructure of the IBS-QOL via item reduction, factor structure, internal consistency, reproducibility, construct validity, and ability to detect change. Results This study supports the IBS-QOL as a psychometrically valid measure. Factor analyses suggested that IBS-specific QOL as measured by the IBS-QOL is a unidimensional construct. Construct validity was further buttressed by significant correlations between IBS-QOL total scores and related measures of IBS-d severity including the historically-relevant Irritable Bowel Syndrome Adequate Relief (IBS-AR) item and the FDAâs Clinical Responder definition. The IBS-QOL also showed a significant ability to detect change as evidenced by analysis of treatment effects. A minority of the items, unrelated to the IBS-d, performed less well by the standards set by the original authors. Conclusions We established that the IBS-QOL total score is a psychometrically valid measure of HRQOL in IBS-d patients enrolled in this study. Our analyses suggest that the IBS-QOL items demonstrate very good construct validity and ability to detect changes due to treatment effects. Furthermore, our analyses suggest that the IBS-QOL items measure a univariate construct and we believe further modeling of the IBS-QOL from an item response theory (IRT) approach under both non-treatment and treatment conditions would greatly further our understanding as item-based methods could be used to develop a short form
Radar plots: A novel modality for displaying disparate data on the efficacy of eluxadoline for the treatment of irritable bowel syndrome with diarrhea
BackgroundPatients with irritable bowel syndrome with diarrhea (IBSâD) experience a range of abdominal and bowel symptoms; successful management requires alleviation of this constellation of symptoms. Eluxadoline, a locally active mixed ÎŒâ and Îșâopioid receptor agonist and ÎŽâopioid receptor antagonist, is approved for the treatment of IBSâD in adults based on the results of 2 Phase 3 studies. Radar plots can facilitate comprehensive, visual evaluation of diverse but interrelated efficacy endpoints.MethodsTwo doubleâblind, placeboâcontrolled, Phase 3 trials (IBSâ3001 and IBSâ3002) randomized patients meeting Rome III criteria for IBSâD to twiceâdaily eluxadoline 75 or 100 mg or placebo. Radar plots were prepared showing pooled Weeks 1â26 response rates for the primary efficacy composite endpoint (simultaneous improvement in abdominal pain and stool consistency), stool consistency, abdominal pain, urgencyâfree days, and adequate relief, and change from baseline to Week 26 in IBSâD global symptom score, abdominal discomfort, abdominal pain, abdominal bloating, and daily number of bowel movements.Key ResultsThe studies enrolled 2428 patients. Eluxadoline increased Weeks 1â26 responder proportions vs placebo for the composite endpoint, stool consistency, abdominal pain, urgencyâfree days, and adequate relief. Changes from baseline to Week 26 in IBSâD global symptom score, abdominal discomfort, abdominal pain, abdominal bloating, and number of bowel movements were greater with eluxadoline vs placebo.Conclusions and InferencesData presentation in radar plot format facilitates interpretation across multiple domains, demonstrating that eluxadoline treatment led to improvements vs placebo across 13 endpoints representing the range of symptoms experienced by patients with IBSâD.Data presentation in radar plot format can facilitate evaluation of the diverse array of symptoms and outcomes that are relevant to a symptomâbased condition like irritable bowel syndrome with diarrhea (IBSâD). In 2 Phase 3 trials, eluxadoline treatment improved stool consistency and frequency, abdominal pain, bloating and discomfort, feelings of urgency, global symptom score, and adequate relief. Radar plots provide a visual demonstration of improvements with eluxadoline across 13 endpoints encompassing the diverse constellation of symptoms experienced by patients with IBSâD.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145265/1/nmo13331_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145265/2/nmo13331.pd
H-ATLAS/GAMA: the nature and characteristics of optically red galaxies detected at submillimetre wavelengths
We combine Herschel/SPIRE sub-millimeter (submm) observations with existing multi-wavelength data to investigate the characteristics of low redshift, optically red galaxies detected in submm bands. We select a sample of galaxies in the redshift range 0.01â€zâ€0.2, having >5Ï detections in the SPIRE 250 micron submm waveband. Sources are then divided into two sub-samples of red and blue galaxies, based on their UV-optical colours. Galaxies in the red sample account for â4.2 per cent of the total number of sources with stellar masses Mââł1010 Solar-mass. Following visual classification of the red galaxies, we find that âł30 per cent of them are early-type galaxies and âł40 per cent are spirals. The colour of the red-spiral galaxies could be the result of their highly inclined orientation and/or a strong contribution of the old stellar population.
It is found that irrespective of their morphological types, red and blue sources occupy environments with more or less similar densities (i.e., the ÎŁ5 parameter). From the analysis of the spectral energy distributions (SEDs) of galaxies in our samples based on MAGPHYS, we find that galaxies in the red sample (of any morphological type) have dust masses similar to those in the blue sample (i.e. normal spiral/star-forming systems). However, in comparison to the red-spirals and in particular blue systems, red-ellipticals have lower mean dust-to-stellar mass ratios. Besides galaxies in the red-elliptical sample have much lower mean star-formation/specific-star-formation rates in contrast to their counterparts in the blue sample. Our results support a scenario where dust in early-type systems is likely to be of an external origin
Nano-optical concept design for light management
Efficient light management in optoelectronic devices requires nanosystems
where high optical qualities coincide with suitable device integration. The
requirement of chemical and electrical passivation for integrating
nanostrutures in e.g. thin film solar cells points towards the use of
insulating and stable dielectric material, which however has to provide high
scattering and near-fields as well. We investigate metal@dielectric core-shell
nanoparticles and dielectric nanorods. Whereas core-shell nanoparticles can be
simulated using Mie theory, nanorods of finite length are studied with the
finite element method. We reveal that a metallic core within a thin dielectric
shell can help to enhance scattering and near-field cross sections compared to
a bare dielectric nanoparticle of the same radius. A dielectric nanorod has
the benefit over a dielectric nanosphere in that it can generate much higher
scattering cross sections and also give rise to a high near-field enhancement
along its whole length. Electrical benefits of e.g. Ag@oxide nanoparticles in
thin-film solar cells and ZnO nanorods in hybrid devices lie in reduction of
recombination centers or close contact of the nanorod material with the
surrounding organics, respectively. The optical benefit of dielectric shell
material and elongated dielectric nanostructures is highlighted in this paper
Eluxadoline Benefits Patients With Irritable Bowel Syndrome With Diarrhea in a Phase 2 Study
Background & AimsSimultaneous agonism of the ÎŒ-opioid receptor and antagonism of the ÎŽ-opioid receptor can reduce abdominal pain and diarrhea in patients with irritable bowel syndrome with diarrhea (IBS-D) without constipating side effects. We evaluated the efficacy and safety of a minimally absorbed, ÎŒ-opioid receptor agonist and ÎŽ-opioid receptor antagonist (eluxadoline) in a phase 2 study in patients with IBS-D.MethodsWe randomly assigned 807 patients to groups that received oral placebo twice daily or 5, 25, 100, or 200 mg oral eluxadoline for 12 weeks. The primary end point was clinical response at week 4, defined by a mean reduction in daily pain score from baseline of â„30%, and of at least 2 points on 0â10 scale, as well as a stool consistency score of 3 or 4 on the Bristol Stool Scale (1â7) for at least 66% of daily diary entries during that week.ResultsSignificantly more patients receiving 25 mg (12.0%) or 200 mg (13.8%) eluxadoline met the primary end point of clinical response than patients given placebo (5.7%; P < .05). Patients receiving eluxadoline at 100 mg and 200 mg also had greater improvements in bowel movement frequency and urgency, global symptoms, quality of life, and adequate relief assessments (P < .05). Additionally, patients receiving 100 mg (28.0%) or 200 mg (28.5%) eluxadoline were significantly more likely than those receiving placebo (13.8%; P < .005) to meet the US Food and Drug Administration response end point during the full 12 weeks of the study. Eluxadoline was well tolerated with a low incidence of constipation.ConclusionsIn a phase 2 study of the mixed ÎŒ-opioid receptor agonist/ÎŽ-opioid receptor antagonist eluxadoline vs placebo in patients with IBS-D, patients given eluxadoline were significantly more likely to be clinical responders, based on a composite of improvement in abdominal pain and stool consistency. Further study of eluxadoline is warranted to assess its potential as a treatment for IBS-D. ClinicalTrials.gov number, NCT0113027
High Resolution, Differential, Near-infrared Transmission Spectroscopy of GJ 1214b
The nearby star GJ 1214 hosts a planet intermediate in radius and mass
between Earth and Neptune, resulting in some uncertainty as to its nature. We
have observed this planet, GJ 1214b, during transit with the high-resolution,
near-infrared NIRSPEC spectrograph on the Keck II telescope, in order to
characterize the planet's atmosphere. By cross-correlating the spectral changes
through transit with a suite of theoretical atmosphere models, we search for
variations associated with absorption in the planet atmosphere. Our
observations are sufficient to rule out tested model atmospheres with
wavelength-dependent transit depth variations >5e-4 over the wavelength range
2.1 - 2.4 micron. Our sensitivity is limited by variable slit loss and telluric
transmission effects.
We find no positive signatures but successfully rule out a number of
plausible atmospheric models, including the default assumption of a gaseous,
H-dominated atmosphere in chemical equilibrium. Such an atmosphere can be made
consistent if the absorption due to methane is reduced. Clouds can also render
such an atmosphere consistent with our observations, but only if they lie
higher in the atmosphere than indicated by recent optical and infrared
measurements.
When taken in concert with constraints from other groups, our results support
a consensus model in which the atmosphere of GJ 1214b contains significant H
and He, but where methane is depleted. If this depletion is the result of
photochemical processes, it may also produce a haze that suppresses spectral
features in the optical.Comment: 32 pages, 15 figures, preprint, accepted to ApJ, responded to
referee's comments. Comments welcom
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