1,055 research outputs found
The effects of an altered photoperiod upon the migratory orientation in the White-throated Sparrow (Zonoirichia albicollis)
A variety of cues are available that a nocturnal migratory bird might use to orient during its journey. Perhaps the best established is their use of the information available in the celestial sky. But how much information do they gain? Experiments have shown that the apparent nightly movement of the stars caused by the earth\u27s rotation aids in providing the bird a north-south axis or compass information (Emlen, 1967b; Gauthreaux, 1969). In addition, certain constellations in the northern circumpolar region are crucial for this axis determination (Emlen, 1967b). The celestial sky also changes in a regular manner with the seasons. Although the configuration of the constellations remains the same,\u27 their location appears to change throughout the year due to the earth\u27s revolution around the sun. Does this seasonal shift contribute to the major reversals of direction taken each year by migratory birds
Development of the preterm infant gut microbiome: a research priority.
The very low birth weight (VLBW) infant is at great risk for marked dysbiosis of the gut microbiome due to multiple factors, including physiological immaturity and prenatal/postnatal influences that disrupt the development of a normal gut flora. However, little is known about the developmental succession of the microbiota in preterm infants as they grow and mature. This review provides a synthesis of our understanding of the normal development of the infant gut microbiome and contrasts this with dysbiotic development in the VLBW infant. The role of human milk in normal gut microbial development is emphasized, along with the role of the gut microbiome in immune development and gastroenteric health. Current research provides evidence that the gut microbiome interacts extensively with many physiological systems and metabolic processes in the developing infant. However, to the best of our knowledge, there are currently no studies prospectively mapping the gut microbiome of VLBW infants through early childhood. This knowledge gap must be filled to inform a healthcare system that can provide for the growth, health, and development of VLBW infants. The paper concludes with speculation about how the VLBW infants' gut microbiome might function through host-microbe interactions to contribute to the sequelae of preterm birth, including its influence on growth, development, and general health of the infant host
RISK-RETURN ANALYSIS OF INCORPORATING ANNUAL LEGUMES AND LAMB GRAZING WITH DRYLAND CROP ROTATIONS
Profitability and risk, 1988-2001, are examined for lamb-grazed field pea as a fallow alternative with wheat, or an extended wheat-sunflower-millet rotation. Switching from conventional wheat-fallow to an extended rotation with grazed-peas increases profitability (2.3% to 7.3%), and reduces risk (below 0% target in only 2 versus 7 of 14 years).Crop Production/Industries,
Clinical utility of ultrasound guidance for intra-articular knee injections: a review
Intra-articular corticosteroid and hyaluronic acid injections provide short-term symptom amelioration for arthritic conditions involving structural damage or degenerative changes in the knee. Conventional palpation-guided anatomical injections frequently result in inaccurate needle placement into extra-articular tissue and adjacent structures. The purpose of this review was to determine the effect of ultrasound guidance on the accuracy of needle placement, clinical outcomes, and cost-effectiveness in comparison with anatomical landmark-guided intra-articular large joint injections, with particular emphasis on the knee. A total of 13 relevant studies were identified; five studied the knee, seven studied the shoulder, one used both the knee and shoulder, and none studied the hip. Ultrasound was used in seven studies; the remaining studies utilized air arthrography, fluoroscopy, magnetic resonance arthrography, or magnetic resonance imaging. Across all studies (using all imaging modalities and all joints), needle placement accuracy ranged from 63% to 100% with ultrasound and from 39% to 100% with conventional anatomical guidance. Imaging guidance improved the accuracy of intra-articular injections of the knee (96.7% versus 81.0%, P < 0.001) and shoulder (97.3% versus 65.4%, P < 0.001). In particular, ultrasound guidance of knee injections resulted in better accuracy than anatomical guidance (95.8% versus 77.8%, P < 0.001), yielding an odds ratio of 6.4 (95% confidence interval 2.9–14). Ultrasound guidance notably improves injection accuracy in the target intra-articular joint space of large joints including the knee. The enhanced injection accuracy achieved with ultrasound needle guidance directly improves patient-reported clinical outcomes and cost-effectiveness
Statistical Computations with AstroGrid and the Grid
We outline our first steps towards marrying two new and emerging
technologies; the Virtual Observatory (e.g, AstroGrid) and the computational
grid. We discuss the construction of VOTechBroker, which is a modular software
tool designed to abstract the tasks of submission and management of a large
number of computational jobs to a distributed computer system. The broker will
also interact with the AstroGrid workflow and MySpace environments. We present
our planned usage of the VOTechBroker in computing a huge number of n-point
correlation functions from the SDSS, as well as fitting over a million CMBfast
models to the WMAP data.Comment: Invited talk to appear in "Proceedings of PHYSTAT05: Statistical
Problems in Particle Physics, Astrophysics and Cosmology
Controlling the False Discovery Rate in Astrophysical Data Analysis
The False Discovery Rate (FDR) is a new statistical procedure to control the
number of mistakes made when performing multiple hypothesis tests, i.e. when
comparing many data against a given model hypothesis. The key advantage of FDR
is that it allows one to a priori control the average fraction of false
rejections made (when comparing to the null hypothesis) over the total number
of rejections performed. We compare FDR to the standard procedure of rejecting
all tests that do not match the null hypothesis above some arbitrarily chosen
confidence limit, e.g. 2 sigma, or at the 95% confidence level. When using FDR,
we find a similar rate of correct detections, but with significantly fewer
false detections. Moreover, the FDR procedure is quick and easy to compute and
can be trivially adapted to work with correlated data. The purpose of this
paper is to introduce the FDR procedure to the astrophysics community. We
illustrate the power of FDR through several astronomical examples, including
the detection of features against a smooth one-dimensional function, e.g.
seeing the ``baryon wiggles'' in a power spectrum of matter fluctuations, and
source pixel detection in imaging data. In this era of large datasets and high
precision measurements, FDR provides the means to adaptively control a
scientifically meaningful quantity -- the number of false discoveries made when
conducting multiple hypothesis tests.Comment: 15 pages, 9 figures. Submitted to A
Nonparametric Inference for the Cosmic Microwave Background
The Cosmic Microwave Background (CMB), which permeates the entire Universe,
is the radiation left over from just 380,000 years after the Big Bang. On very
large scales, the CMB radiation field is smooth and isotropic, but the
existence of structure in the Universe - stars, galaxies, clusters of galaxies
- suggests that the field should fluctuate on smaller scales. Recent
observations, from the Cosmic Microwave Background Explorer to the Wilkinson
Microwave Anisotropy Project, have strikingly confirmed this prediction. CMB
fluctuations provide clues to the Universe's structure and composition shortly
after the Big Bang that are critical for testing cosmological models. For
example, CMB data can be used to determine what portion of the Universe is
composed of ordinary matter versus the mysterious dark matter and dark energy.
To this end, cosmologists usually summarize the fluctuations by the power
spectrum, which gives the variance as a function of angular frequency. The
spectrum's shape, and in particular the location and height of its peaks,
relates directly to the parameters in the cosmological models. Thus, a critical
statistical question is how accurately can these peaks be estimated. We use
recently developed techniques to construct a nonparametric confidence set for
the unknown CMB spectrum. Our estimated spectrum, based on minimal assumptions,
closely matches the model-based estimates used by cosmologists, but we can make
a wide range of additional inferences. We apply these techniques to test
various models and to extract confidence intervals on cosmological parameters
of interest. Our analysis shows that, even without parametric assumptions, the
first peak is resolved accurately with current data but that the second and
third peaks are not.Comment: Invited review for "Statistical Science". Accepted for publication in
Feburary 2004 journa
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