3,635 research outputs found
Financial survivability of beginning dairy farms : a simulation of Tennessee dairies
Economic survivability of the farm operation continues to be a problem in agricultural. The dairy operation has a large financial strain on beginning resources in order for the farm enterprise to survive and be an economic success. This study used FLIPSIM, a farm level simulation model, to determine the impact of a farmer\u27s beginning ratio of equity to assets and beginning level of annual milk production on the financial success of a beginning dairy enterprise. FLIPSIM, a recursive farm-level model which can be run stochastically, was chosen for the simulation study.
FLIPSIM simulates the production, marketing, and financial management of a farm over a specified planning horizon. The model is stochastic in that crop yields and prices and milk and cow prices were assumed to follow a multivariate empirical distribution.
Data needed for the simulation model were collected from various sources. A 1988 survey of Tennessee beginning dairy farmers was used as the base data. The survey data was supplemented by data from various farm production records, budgets, and state and national statistics. The combination of information from these sources is used for FLIPSIM to simulate conditions faced by a representative farm.
Under the conditions of this study, beginning equity and milk production levels of 35 percent and 10,000 - 12,000 pounds, 50 percent equity and 10,000 - 12,000 pounds, and 20 percent equity and 14,000 - 16,000 pounds proved to be the most economically successful. The two remaining scenarios of 20 percent equity and 10,000 - 12,000 pounds milk production and 20 percent equity and 12,000 - 14,000 pounds milk production represent the beginning farmer, with a low equity ratio and few or no years of dairy experience. Of these two scenarios, the higher milk production level allows the farm a greater probability of survival and economic success.
It appears that under the conditions assumed in this study, a beginning diary farmer has a high probability of survival and being an economic success. Even with the lowest equity level and milk production level assumed, the farm has a better than 60 percent chance it will survive and be an economic success
NMR and NQR parameters of ethanol crystal
Electric field gradients and chemical shielding tensors of the stable
monoclinic crystal phase of ethanol are computed. The projector-augmented wave
(PAW) and gauge-including projector-augmented wave (GIPAW) models in the
periodic plane-wave density functional theory are used. The crystal data from
X-ray measurements, as well as the structures where either all atomic, or only
hydrogen atom positions are optimized in the density functional theory are
analyzed. These structural models are also studied by including the
semi-empirical Van der Waals correction to the density functional theory.
Infrared spectra of these five crystal models are calculated
Data From: Active Transportation Counts from Existing On-Street Signal and Detection Infrastructure
This study’s objective was to use data from existing traffic signal infrastructure to estimate pedestrian volumes. Pedestrian push-button actuations were collected from signal controller logs at 49 intersections in western Oregon and an additional 16 intersections in eastern Oregon. These actuations were then compared to observed pedestrian counts, totaling over 34,000 people, obtained from video recordings. After exploring various options, a simple quadratic relationship was modeled using a single measure of pedestrian signal activity: the number of push-button presses (filtered to remove multiple presses within 15 seconds). The model’s predictions showed a correlation of 0.86 with observed pedestrian volumes and had an average error of ±2.4 pedestrians per hour. These results suggest that existing traffic signal infrastructure data can be used to estimate pedestrian volumes in Oregon with reasonable accuracy. Using such pedestrian volume estimates can lead to improvements in pedestrian traffic monitoring, safety assessments of exposure, and equity and health analyses
An Extension to Models for Cosmic String Formation
The canonical Monte-Carlo algorithm for simulating the production of
string-like topological defects at a phase transition is extended by
introducing a distribution of domain sizes. A strong correlation is found
between the fraction in the form of `infinite' string and the variance of the
volume of the regions of constant phase.Comment: Revised version to appear in Phys. Lett. B. Several minor
corrections, including title change. 5 pages Latex with 5 postscript figures
(uuencoded and compressed). Also available through anonymous ftp from
ftp://euclid.tp.ph.ic.ac.uk/papers/ or on WWW at
http://euclid.tp.ph.ic.ac.uk/Papers
Galaxy Mass, Metallicity, Radius and Star Formation Rates
Working with 108,786 Sloan Digital Sky Survey low redshift galaxies we have
examined the relation between galaxy mass, metallicity, radius, and star
formation rates primarily in the central portions of galaxies. We subdivided
the redshift range covered in our sample, 0.07<z<0.3, into three narrower
redshift bins, and three sets of radial size. We show that for 72% of the
galaxies the observed gas metallicities, Zx, are consistent with (i) a
quantitative physical relation for star formation through episodic infall of
gas of metallicity Zi = 0.125x10^-3 +/- 1.25x10^-3; (ii) thorough mixing of
infalling and native gas before onset of star formation; (iii) a star formation
rate (SFR) proportional to the 3/2 power of the infalling mass rate, Mi; and
(iv) intermittent quiescent phases devoid of star formation during which the
native gas in a galaxy exhibits a characteristic elevated gas metallicity, Z0,
dependent on galaxy mass, M*, and a characteristic ratio of stellar mass to
native mass of gas, Mg. Most if not all our star-forming galaxies with M* <
2.0x10^10 Msun, and many with M* > 2.0x10^10 Msun and large radii appear fed by
infall. Smaller massive galaxies with high Zx and high star formation rates
show more complex behavior. A mean-field-theory toy model for the physics of
infall accounts for the (SFR) \propto Mi^(3/2) relation and permits us to
estimate the mean densities and velocities of clumps of baryonic matter
traversing the dark matter halos in which the SDSS galaxies may be embedded.Comment: 34 pages plus bibliography and supplementary figures, 3 main figures,
131 supplementary online figures, ascii data tables availabl
Postnatal β2 adrenergic treatment improves insulin sensitivity in lambs with IUGR but not persistent defects in pancreatic islets or skeletal muscle
Placental insufficiency causes intrauterine growth restriction (IUGR) and disturbances in glucose homeostasis with associated β adrenergic receptor (ADRβ) desensitization. Our objectives were to measure insulin-sensitive glucose metabolism in neonatal lambs with IUGR and to determine whether daily treatment with ADRβ2 agonist and ADRβ1/β3 antagonists for 1 month normalizes their glucose metabolism. Growth, glucose-stimulated insulin secretion (GSIS) and glucose utilization rates (GURs) were measured in control lambs, IUGR lambs and IUGR lambs treated with adrenergic receptor modifiers: clenbuterol atenolol and SR59230A (IUGR-AR). In IUGR lambs, islet insulin content and GSIS were less than in controls; however, insulin sensitivity and whole-bodyGUR were not different from controls.Of importance, ADRβ2 stimulation with β1/β3 inhibition increases both insulin sensitivity and whole-body glucose utilization in IUGR lambs. In IUGR and IUGR-AR lambs, hindlimb GURs were greater but fractional glucose oxidation rates and ex vivo skeletal muscle glucose oxidation rates were lower than controls. Glucose transporter 4 (GLUT4) was lower in IUGR and IUGR-AR skeletal muscle than in controls but GLUT1 was greater in IUGR-AR. ADRβ2, insulin receptor, glycogen content and citrate synthase activity were similar among groups. In IUGR and IUGR-AR lambs heart rates were greater, which was independent of cardiac ADRβ1 activation. We conclude that targeted ADRβ2 stimulation improved whole-body insulin sensitivity but minimally affected defects in GSIS and skeletal muscle glucose oxidation. We show that risk factors for developing diabetes are independent of postnatal catch-up growth in IUGR lambs as early as 1 month of age and are inherent to the islets and myocytes
All-sky Galactic radiation at 45 MHz and spectral index between 45 and 408 MHz
Aims: We study the Galactic large-scale synchrotron emission by generating a
reliable all-sky spectral index map and temperature map at 45 MHz. Methods: We
use our observations, the published all-sky map at 408 MHz, and a
bibliographical compilation to produce a map corrected for zero-level offset
and extragalactic contribution. Results: We present full sky maps of the
Galactic emission at 45 MHz and the Galactic spectral index between 45 and 408
MHz with an angular resolution of 5\degs. The spectral index varies between 2.1
and 2.7, reaching values below 2.5 at low latitude because of thermal free-free
absorption and its maximum in the zone next to the Northern Spur.Comment: A&A accepte
EPW: A program for calculating the electron-phonon coupling using maximally localized Wannier functions
EPW (Electron-Phonon coupling using Wannier functions) is a program written
in FORTRAN90 for calculating the electron-phonon coupling in periodic systems
using density-functional perturbation theory and maximally-localized Wannier
functions. EPW can calculate electron-phonon interaction self-energies,
electron-phonon spectral functions, and total as well as mode-resolved
electron-phonon coupling strengths. The calculation of the electron-phonon
coupling requires a very accurate sampling of electron-phonon scattering
processes throughout the Brillouin zone, hence reliable calculations can be
prohibitively time-consuming. EPW combines the Kohn-Sham electronic eigenstates
and the vibrational eigenmodes provided by the Quantum-ESPRESSO package [1]
with the maximally localized Wannier functions provided by the wannier90
package [2] in order to generate electron-phonon matrix elements on arbitrarily
dense Brillouin zone grids using a generalized Fourier interpolation. This
feature of EPW leads to fast and accurate calculations of the electron-phonon
coupling, and enables the study of the electron-phonon coupling in large and
complex systems.Comment: 6 figure
Spatiotemporal Parameters of Gait Among Adolescent Athletes with Concussion When Performing a Visuospatial Cognitive Task
# Background
Adolescent athletes aged 10 to 19 years are at the highest risk of experiencing sport-related concussions (SRCs). Despite the known deficits and battery of assessments following concussion, postural stability during dual-task gait remains understudied in this population.
# Purpose
The purpose of this study was to evaluate the dual-task cost (DTC) in adolescents with an acute or chronic SRC compared to reference values from healthy athlete peers for spatiotemporal parameters of gait during walking with and without a concurrent visuospatial memory task presented on a hand-held tablet. Researchers hypothesized that adolescents during the acute phase of concussion would be likely to experience a greater DTC compared to healthy peers in at least one spatiotemporal parameter of gait when walking within the dual-task paradigm.
# Study Design
Cross-sectional, observational cohort design
# Methods
Adolescents with concussion were recruited to participate. Subjects were divided into acute and chronic categories based on significant differences in the neuropsychological function after a period of 28 days. They walked at a self-selected speed along the 5.186-meter GAITRite® Walkway System with and without a concurrent visuospatial cognitive task presented on a hand-held tablet. Outcomes included normalized velocity (m/s), step length (m), and double limb (DLS) and single limb support (SLS) (defined as the percent of a gait cycle ). The data were then compared to the previously published reference values established using the same methods in the healthy athlete participants for all spatiotemporal parameters of gait.
# Results
Data was collected on 29 adolescent athletes with SRC. Among males (15.53+/-1.12 years) with SRC, 20% of acute and 10% of chronic cases experienced a greater DTC compared to healthy athlete reference values. A similarly increased DTC was experienced by 83% of acute and 29% of chronic SRC cases for females (15.58+/-1.16 years).
# Conclusions
Adolescent athletes with concussion may continue demonstrating deficits in gait capabilities even in the chronic phase, and compensatory gait strategies were not the same between males and females. Dual-task cost assessment using the GAITRite® may be a valuable adjunct to comprehensive analysis of gait following SRC.
# Level of Evidence
Biomarkers of oxidant stress, insulin sensitivity and endothelial activation in rheumatoid arthritis: a cross-sectional study of their association with accelerated atherosclerosis
<p>Abstract</p> <p>Background</p> <p>Women with rheumatoid arthritis (RA) have increased morbidity and mortality due to coronary heart disease. Chronic systemic inflammation is known to accelerate atherosclerosis and increase arterial stiffness in patients, but other mechanisms may also be involved. Biomarkers of oxidant stress, inflammation, insulinaemia and endothelial dysfunction were measured in blood and urine from 46 RA patients and 48 age-matched controls. Plaque formation and intima-medial thickness (IMT) were measured using B-mode carotid Doppler scan.</p> <p>Findings</p> <p>The prevalence of plaque was increased (p = 0.042) in RA patients between 50–59 years old compared to the same age group in controls. 8-isoprostane (p = 0.004), C-reactive protein (p < 0.001), interleukin-6 (p < 0.001), insulin (p = 0.035), adiponectin (p = 0.012), vascular cell adhesion molecule (VCAM) (p = 0.029) and E-selectin (p < 0.001) were all increased while selenium (p = 0.003) and LDL-cholesterol (p = 0.025) were both decreased in all RA patients. 8-isoprostane correlated with 10 year cardiac risk (r = 0.55, p < 0.001), VCAM with IMT (r = 0.37, p = 0.012) and E-selectin with rheumatoid factor titre (r = 0.43, p = 0.003) in RA patients. In the control group, age, carotid IMT, VCAM, systolic blood pressure and smoking status were all associated with plaque development whereas in RA patients only age was associated with plaque.</p> <p>Conclusion</p> <p>The burden of atherosclerosis is particularly increased in middle-aged women with RA. Patients with RA have increased levels of oxidant stress, inflammation, insulin and soluble adhesion molecules. As the association between classical risk factors was much weaker in RA patients compared to controls, these additional factors may be more important in the accelerated development of atheroma in RA.</p
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