692 research outputs found
Forage production and utilization in a sprayed Aspen forest in Alberta
In aspen forest in Alberta, Canada, receiving as little as 3 lb/acre of 2,4-D in a single application achieved an annual herbage production of 874 lb/acre 2 years after treatment compared to only 188 lb/acre in the control. Sprayed forest border areas (small aspen) showed a four-fold increase in herbage production. Grasses, sedges, and forbs increased in herbage production in sprayed forests. Only two forbs were detrimentally affected by the herbicides. In the sprayed forest area, even though there was a considerable amount of obstruction, cattle were able to consume 48% of the total herbage and as much as 58% of the green herbage. However, even with the inclusion of 2,4,5-T in the second herbicide application, there were many woody species in the treatment areas with as high or higher densities than in the control.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
Brush control on sandy rangelands in central Alberta
Balsam poplar, aspen, and willows that had invaded subirrigated sandy rangeland were treated with (1) prescribed spring burning, (2) the herbicide 2,4-D ester, and (3) prescribed burning followed by 2,4-D ester. After 5 years, burning and spraying had reduced brush the most. Brush reinvasion was occurring rapidly on all treated areas. Stand openings of about one quarter hectare in an 8 meter high poplar forest resulting from these treatments did persist for at least 5 years. Treatments were effective enough to lower the forest cover and in some cases increase forage production. Repeated burning and spraying substantially reduced the density of reinvading woody suckers.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
A Study of the S=1/2 Alternating Chain using Multiprecision Methods
In this paper we present results for the ground state and low-lying
excitations of the alternating Heisenberg antiferromagnetic chain. Our
more conventional techniques include perturbation theory about the dimer limit
and numerical diagonalization of systems of up to 28 spins. A novel application
of multiple precision numerical diagonalization allows us to determine
analytical perturbation series to high order; the results found using this
approach include ninth-order perturbation series for the ground state energy
and one magnon gap, which were previously known only to third order. We also
give the fifth-order dispersion relation and third-order exclusive neutron
scattering structure factor for one-magnon modes and numerical and analytical
binding energies of S=0 and S=1 two-magnon bound states.Comment: 16 pages, 9 figures. for submission to Phys.Rev.B. PICT files of figs
available at http://csep2.phy.ornl.gov/theory_group/people/barnes/barnes.htm
Action principle formulation for motion of extended bodies in General Relativity
We present an action principle formulation for the study of motion of an
extended body in General Relativity in the limit of weak gravitational field.
This gives the classical equations of motion for multipole moments of arbitrary
order coupling to the gravitational field. In particular, a new force due to
the octupole moment is obtained. The action also yields the gravitationally
induced phase shifts in quantum interference experiments due to the coupling of
all multipole moments.Comment: Revised version derives Octupole moment force. Some clarifications
and a reference added. To appear in Phys. Rev.
Generalized Bernstein--Reznikov integrals
We find a closed formula for the triple integral on spheres in
whose kernel is
given by powers of the standard symplectic form. This gives a new proof to the
Bernstein--Reznikov integral formula in the case. Our method also applies
for linear and conformal structures
Spatial prediction of the concentration of selenium (Se) in grain across part of Amhara Region, Ethiopia
Grain and soil were sampled across a large part of Amhara, Ethiopia in a study motivated by prior evidence of selenium (Se) deficiency in the Region's population. The grain samples (teff, Eragrostis tef, and wheat, Triticum aestivum) were analysed for concentration of Se and the soils were analysed for various properties, including Se concentration measured in different extractants. Predictive models for concentration of Se in the respective grains were developed, and the predicted values, along with observed concentrations in the two grains were represented by a multivariate linear mixed model in which selected covariates, derived from remote sensor observations and a digital elevation model, were included as fixed effects. In all modelling steps the selection of predictors was done using false discovery rate control, to avoid over-fitting, and using an α-investment procedure to maximize the statistical power to detect significant relationships by ordering the tests in a sequence based on scientific understanding of the underlying processes likely to control Se concentration in grain. Cross-validation indicated that uncertainties in the empirical best linear unbiased predictions of the Se concentration in both grains were well-characterized by the prediction error variances obtained from the model. The predictions were displayed as maps, and their uncertainty was characterized by computing the probability that the true concentration of Se in grain would be such that a standard serving would not provide the recommended daily allowance of Se. The spatial variation of grain Se was substantial, concentrations in wheat and teff differed but showed the same broad spatial pattern. Such information could be used to target effective interventions to address Se deficiency, and the general procedure used for mapping could be applied to other micronutrients and crops in similar settings
Stillbirth risk prediction using machine learning for a large cohort of births from Western Australia, 1980–2015
Quantification of stillbirth risk has potential to support clinical decision-making. Studies that have attempted to quantify stillbirth risk have been hampered by small event rates, a limited range of predictors that typically exclude obstetric history, lack of validation, and restriction to a single classifier (logistic regression). Consequently, predictive performance remains low, and risk quantification has not been adopted into antenatal practice. The study population consisted of all births to women in Western Australia from 1980 to 2015, excluding terminations. After all exclusions there were 947,025 livebirths and 5,788 stillbirths. Predictive models for stillbirth were developed using multiple machine learning classifiers: regularised logistic regression, decision trees based on classification and regression trees, random forest, extreme gradient boosting (XGBoost), and a multilayer perceptron neural network. We applied 10-fold cross-validation using independent data not used to develop the models. Predictors included maternal socio-demographic characteristics, chronic medical conditions, obstetric complications and family history in both the current and previous pregnancy. In this cohort, 66% of stillbirths were observed for multiparous women. The best performing classifier (XGBoost) predicted 45% (95% CI: 43%, 46%) of stillbirths for all women and 45% (95% CI: 43%, 47%) of stillbirths after the inclusion of previous pregnancy history. Almost half of stillbirths could be potentially identified antenatally based on a combination of current pregnancy complications, congenital anomalies, maternal characteristics, and medical history. Greatest sensitivity is achieved with addition of current pregnancy complications. Ensemble classifiers offered marginal improvement for prediction compared to logistic regression
Stillbirth risk prediction using machine learning for a large cohort of births from Western Australia, 1980–2015
Quantification of stillbirth risk has potential to support clinical decision-making. Studies that have attempted to quantify stillbirth risk have been hampered by small event rates, a limited range of predictors that typically exclude obstetric history, lack of validation, and restriction to a single classifier (logistic regression). Consequently, predictive performance remains low, and risk quantification has not been adopted into antenatal practice. The study population consisted of all births to women in Western Australia from 1980 to 2015, excluding terminations. After all exclusions there were 947,025 livebirths and 5,788 stillbirths. Predictive models for stillbirth were developed using multiple machine learning classifiers: regularised logistic regression, decision trees based on classification and regression trees, random forest, extreme gradient boosting (XGBoost), and a multilayer perceptron neural network. We applied 10-fold cross-validation using independent data not used to develop the models. Predictors included maternal socio-demographic characteristics, chronic medical conditions, obstetric complications and family history in both the current and previous pregnancy. In this cohort, 66% of stillbirths were observed for multiparous women. The best performing classifier (XGBoost) predicted 45% (95% CI: 43%, 46%) of stillbirths for all women and 45% (95% CI: 43%, 47%) of stillbirths after the inclusion of previous pregnancy history. Almost half of stillbirths could be potentially identified antenatally based on a combination of current pregnancy complications, congenital anomalies, maternal characteristics, and medical history. Greatest sensitivity is achieved with addition of current pregnancy complications. Ensemble classifiers offered marginal improvement for prediction compared to logistic regression
An investigation into the use of a movement assessment protocol for under 14 rugby league players in a talent development environment
This study investigated the use of a movement assessment protocol for under-14 rugby league players by evaluating the relationships between chronological age, maturation, and anthropometry, and fitness and qualitative movement assessments (QMA) of 84 rugby league players within a talent development environment. A one-way ANOVA showed Quartile 1 players were more mature, taller (173.0±7.4 vs 165.0±8.0 cm) and heavier (72.5 vs 58.7 kg) than Quartile 4 players, with no difference evident for fitness or QMA measures. Earlier maturing players had significantly greater upper body power (5.39±0.46 vs 4.42±0.68 m), 20m speed (3.48±0.14 vs 3.65±0.19s) and power pass QMA (13.88±2.18 vs 12.00±1.98) than later maturing players. Body mass was positively related to power pass fitness (r=0.50) and QMA (r=0.22) scores, with negative relationships found for vertical jump performance (r=-0.24), sprint QMA (r=-.29) and turn off either foot QMA (r=-0.26). There is a need to educate coaches about the use of both fitness testing and qualitative movement assessments to identify talented U14 rugby league players, which potentially reduces relative age and maturational biases
Male bisexual arousal: A matter of curiosity?
Conflicting evidence exists regarding whether bisexual-identified men are sexually aroused to both men and women. We hypothesized that a distinct characteristic, level of curiosity about sexually diverse acts, distinguishes bisexual-identified men with and without bisexual arousal. Study 1 assessed men's (n = 277) sexual arousal via pupil dilation to male and female sexual stimuli. Bisexual men were, on average, higher in their sexual curiosity than other men. Despite this general difference, only bisexual-identified men with elevated sexual curiosity showed bisexual arousal. Those lower in curiosity had responses resembling those of homosexual men. Study 2 assessed men's (n = 72) sexual arousal via genital responses and replicated findings of Study 1. Study 3 provided information on the validity on our measure of sexual curiosity by relating it to general curiosity and sexual sensation seeking (n = 83). Based on their sexual arousal and personality, at least two groups of men identify as bisexual
- …