6,968 research outputs found
Sub-pixel spatial resolution wavefront phase imaging
A phase imaging method for an optical wavefront acquires a plurality of phase images of the optical wavefront using a phase imager. Each phase image is unique and is shifted with respect to another of the phase images by a known/controlled amount that is less than the size of the phase imager's pixels. The phase images are then combined to generate a single high-spatial resolution phase image of the optical wavefront
Spatial and Temporal Stability of Airglow Measured in the Meinel Band Window at 1191.3 nm
We report on the temporal and spatial fluctuations in the atmospheric
brightness in the narrow band between Meinel emission lines at 1191.3 nm using
an R=320 near-infrared instrument. We present the instrument design and
implementation, followed by a detailed analysis of data taken over the course
of a night from Table Mountain Observatory. The absolute sky brightness at this
wavelength is found to be 5330 +/- 30 nW m^-2 sr^-1, consistent with previous
measurements of the inter-band airglow at these wavelengths. This amplitude is
larger than simple models of the continuum component of the airglow emission at
these wavelengths, confirming that an extra emissive or scattering component is
required to explain the observations. We perform a detailed investigation of
the noise properties of the data and find no evidence for a noise component
associated with temporal instability in the inter-line continuum. This result
demonstrates that in several hours of ~100s integrations the noise performance
of the instrument does not appear to significantly degrade from expectations,
giving a proof of concept that near-IR line intensity mapping may be feasible
from ground-based sites.Comment: 15 figures, submitted to PAS
Low-dose RUTF protocol and improved service delivery lead to good programme outcomes in the treatment of uncomplicated SAM: a programme report from Myanmar.
The treatment of uncomplicated severe acute malnutrition (SAM) requires substantial amounts of ready-to-use therapeutic food (RUTF). In 2009, Action Contre la Faim anticipated a shortfall of RUTF for their nutrition programme in Myanmar. A low-dose RUTF protocol to treat children with uncomplicated SAM was adopted. In this protocol, RUTF was dosed according to beneficiary's body weight, until the child reached a Weight-for-Height z-score of ≥-3 and mid-upper arm circumference ≥110 mm. From this point, the child received a fixed quantity of RUTF per day, independent of body weight until discharge. Specific measures were implemented as part of this low-dose RUTF protocol in order to improve service quality and beneficiary support. We analysed individual records of 3083 children treated from July 2009 to January 2010. Up to 90.2% of children recovered, 2.0% defaulted and 0.9% were classified as non-responders. No deaths were recorded. Among children who recovered, median [IQR] length of stay and weight gain were 42 days [28; 56] and 4.0 g kg(-1) day(-1) [3.0; 5.7], respectively. Multivariable logistic regression showed that children older than 48 months had higher odds of non-response to treatment than younger children (adjusted odds ratio: 3.51, 95% CI: 1.67-7.42). Our results indicate that a low-dose RUTF protocol, combined with specific measures to ensure good service quality and beneficiary support, was successful in treating uncomplicated SAM in this setting. This programmatic experience should be validated by randomised studies aiming to test, quantify and attribute the effect of the protocol adaptation and programme improvements presented here
Comparing stakeholder attitudes toward white-tailed deer and rare plant management in Canaan Valley, West Virginia
Canaan Valley, West Virginia, USA provides habitat for many plants considered rare in West Virginia. The local white-tailed deer (Odocoileus virginianus Zimm.) are a popular attraction for visitors as well as resident and nonresident hunters. However, concerns exist over the impact of white-tailed deer herbivory on rare plant communities in the wetlands. We evaluated stakeholder attitudes regarding white-tailed deer management and rare plant conservation by mailing surveys to property owners in Canaan Valley and Tucker County, WV, and providing surveys to visitors at Canaan Valley State Park and National Wildlife Refuge. Individuals that had incurred crop damage were more likely to view the Canaan Valley population as overabundant while nonresident landowners placed higher values on the conservation of rare plants and plant communities in Canaan Valley. We found that hunters were more likely than nonhunters to support white-tailed deer management actions. Results of this survey may help managers to direct management and education goals toward actual rather than perceived stakeholder attitudes
Reproducibility of graph metrics of human brain structural networks
Recent interest in human brain connectivity has led to the application of graph theoretical analysis to human brain structural networks, in particular white matter connectivity inferred from diffusion imaging and fiber tractography. While these methods have been used to study a variety of patient populations, there has been less examination of the reproducibility of these methods. A number of tractography algorithms exist and many of these are known to be sensitive to user-selected parameters. The methods used to derive a connectivity matrix from fiber tractography output may also influence the resulting graph metrics. Here we examine how these algorithm and parameter choices influence the reproducibility of proposed graph metrics on a publicly available test-retest dataset consisting of 21 healthy adults. The dice coefficient is used to examine topological similarity of constant density subgraphs both within and between subjects. Seven graph metrics are examined here: mean clustering coefficient, characteristic path length, largest connected component size, assortativity, global efficiency, local efficiency, and rich club coefficient. These reproducibility of these network summary measures is examined using the intraclass correlation coefficient (ICC). Graph curves are created by treating the graph metrics as functions of a parameter such as graph density. Functional data analysis techniques are usedto examine differences in graph measures that result from the choice of fiber tracking algorithm. The graph metrics consistently showed good levels of reproducibility as measured with ICC, with the exception of some instability at low graph density levels. The global and local efficiency measures were the most robust to the choice of fiber tracking algorithm
Numerical optimization of integrating cavities for diffraction-limited millimeter-wave bolometer arrays
Far-infrared to millimeter-wave bolometers designed to make astronomical observations are typically encased in integrating cavities at the termination of feedhorns or Winston cones. This photometer combination maximizes absorption of radiation, enables the absorber area to be minimized, and controls the directivity of absorption, thereby reducing susceptibility to stray light. In the next decade, arrays of hundreds of silicon nitride micromesh bolometers with planar architectures will be used in ground-based, suborbital, and orbital platforms for astronomy. The optimization of integrating cavity designs is required for achieving the highest possible sensitivity for these arrays. We report numerical simulations of the electromagnetic fields in integrating cavities with an infinite plane-parallel geometry formed by a solid reflecting backshort and the back surface of a feedhorn array block. Performance of this architecture for the bolometer array camera (Bolocam) for cosmology at a frequency of 214 GHz is investigated. We explore the sensitivity of absorption efficiency to absorber impedance and backshort location and the magnitude of leakage from cavities. The simulations are compared with experimental data from a room-temperature scale model and with the performance of Bolocam at a temperature of 300 mK. The main results of the simulations for Bolocam-type cavities are that (1) monochromatic absorptions as high as 95% are achievable with <1% cross talk between neighboring cavities, (2) the optimum absorber impedances are 400 Ω/sq, but with a broad maximum from ~150 to ~700 Ω/sq, and (3) maximum absorption is achieved with absorber diameters ≥1.5λ. Good general agreement between the simulations and the experiments was found
The impact of economic, political and social globalization on overweight and obesity in the 56 low and middle income countries
This is the final published version. It first appeared at http://www.sciencedirect.com/science/article/pii/S0277953615001744.Anecdotal and descriptive evidence has led to the claim that globalization plays a major role in inducing
overweight and obesity in developing countries, but robust quantitative evidence is scarce. We undertook
extensive econometric analyses of several datasets, using a series of new proxies for different dimensions
of globalization potentially affecting overweight in up to 887,000 women aged 15e49 living in
56 countries between 1991 and 2009. After controlling for relevant individual and country level factors,
globalization as a whole is substantially and significantly associated with an increase in the individual
propensity to be overweight among women. Surprisingly, political and social globalization dominate the
influence of the economic dimension. Hence, more consideration needs to be given to the forms of
governance required to shape a more health-oriented globalization process.The authors were supported by the Centre for Diet and Activity
Research (CEDAR), a UKCRC Public Health Research Centre of
Excellence. Funding from the British Heart Foundation, Economic
and Social Research Council, Medical Research Council, the National
Institute for Health Research, and the Wellcome Trust (087636/Z/
08/Z ESRC: ES/G007462/1), under the auspices of the UK Clinical
Research Collaboration, is gratefully acknowledged
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