1,188 research outputs found
DETERMINANTS OF RESTRUCTURED FARM LOAN PERFORMANCE
A probabilistic model is applied to cross-sectional data to identify determinants of post-restructure performance of Federal Land Bank loans. The results indicate that restructured loans were sensitive to factors that determine the debt repayment burden and the repayment ability of the restructured farm operations. Loan performance is found to be relatively more sensitive to the levels of the post-restructure interest rate and cash farm income than to the financial structure and leverage position of the restructured farm. The relationships between the post-restructure interest rate, cash farm income level, and the probability of loan performance are illustrated.Agricultural Finance,
Exact nonadditive kinetic potentials for embedded density functional theory
We describe an embedded density functional theory (DFT) protocol in which the nonadditive kinetic energy component of the embedding potential is treated exactly. At each iteration of the KohnâSham equations for constrained electron density, the ZhaoâMorrisonâParr constrained search method for constructing KohnâSham orbitals is combined with the King-Handy expression for the exact kinetic potential. We use this formally exact embedding protocol to calculate ionization energies for a series of three- and four-electron atomic systems, and the results are compared to embedded DFT calculations that utilize the ThomasâFermi (TF) and the ThomasâFermiâvon Weisacker approximations to the kinetic energy functional. These calculations illustrate the expected breakdown due to the TF approximation for the nonadditive kinetic potential, with errors of 30%â80% in the calculated ionization energies; by contrast, the exact protocol is found to be accurate and stable. To significantly improve the convergence of the new protocol, we introduce a density-based switching function to map between the exact nonadditive kinetic potential and the TF approximation in the region of the nuclear cusp, and we demonstrate that this approximation has little effect on the accuracy of the calculated ionization energies. Finally, we describe possible extensions of the exact protocol to perform accurate embedded DFT calculations in large systems with strongly overlapping subsystem densities
Uteroplacental bleeding disorders during pregnancy: do missing paternal characteristics influence risk?
BACKGROUND: Several studies have assessed the risks of uteroplacental bleeding disorders in relation to maternal characteristics. The association between uteroplacental bleeding disorders and paternal characteristics, however, has received considerably less attention. Data on paternal demographics, notably race and age, from birth certificate data are becoming increasingly incomplete in recent years. This pattern of increasingly underreporting of paternal demographic data led us to speculate that pregnancies for which paternal characteristics are partially or completely missing may be associated with increased risk for uteroplacental bleeding disorders. The objective of this study is to examine the association between placenta previa and placental abruption and missing paternal age and race. METHODS: A retrospective cohort study using U.S. linked birth/infant death data from 1995 through 2001 (n = 26,336,549) was performed. Risks of placenta previa and placental abruption among: (i) pregnancies with complete paternal age and race data; (ii) paternal age only missing; (iii) paternal race only missing; and (iv) both paternal age and race missing, were evaluated. Relative risk (RR) with 95% confidence interval (CI) for placenta previa and placental abruption by missing paternal characteristics were derived after adjusting for confounders. RESULTS: Adjusted RR for placental abruption were 1.30 (95% CI 1.24, 1.37), 1.00 (95% CI 0.95, 1.05), and 1.08 (95% CI 1.06, 1.10) among pregnancies with "paternal age only", "paternal race only", and "both paternal age and race" missing, respectively. The increased risk of placental abruption among the "paternal age only missing" category is partly explained by increased risks among whites aged 20â29 years, and among blacks aged â„30 years. However, no clear patterns in the associations between missing paternal characteristics and placenta previa were evident. CONCLUSION: Missing paternal characteristics are associated with increased risk of placental abruption, likely mediated through low socio-economic conditions
Gauge-invariant correlation functions in light-cone superspace
We initiate a study of correlation functions of gauge-invariant operators in
N=4 super Yang-Mills theory using the light-cone superspace formalism. Our
primary aim is to develop efficient methods to compute perturbative corrections
to correlation functions. This analysis also allows us to examine potential
subtleties which may arise when calculating off-shell quantities in light-cone
gauge. We comment on the intriguing possibility that the manifest N=4
supersymmetry in this approach may allow for a compact description of entire
multiplets and their correlation functions.Comment: 35 pages, several figure
Maximally Supersymmetric Yang-Mills in five dimensions in light-cone superspace
We formulate maximally supersymmetric Yang-Mills theory in five dimensions in
light-cone superspace. The light-cone Hamiltonian is of the quadratic form and
the theory can be understood as an oxidation of the N=4 Super Yang-Mills Theory
in four dimensions. We specifically study three-point counterterms and show how
these counterterms vanish on-shell. This study is a preliminary to set up the
technique in order to study possible four-point counterterms.Comment: 25 pages, typos corrected, references adde
The Kinematic Algebra From the Self-Dual Sector
We identify a diffeomorphism Lie algebra in the self-dual sector of
Yang-Mills theory, and show that it determines the kinematic numerators of
tree-level MHV amplitudes in the full theory. These amplitudes can be computed
off-shell from Feynman diagrams with only cubic vertices, which are dressed
with the structure constants of both the Yang-Mills colour algebra and the
diffeomorphism algebra. Therefore, the latter algebra is the dual of the colour
algebra, in the sense suggested by the work of Bern, Carrasco and Johansson. We
further study perturbative gravity, both in the self-dual and in the MHV
sectors, finding that the kinematic numerators of the theory are the BCJ
squares of the Yang-Mills numerators.Comment: 29 pages, 5 figures. v2: references added, published versio
Welfare Challenges of Dairy Cows in India Identified Through On-Farm Observations
India has the largest population of dairy cattle in the world at over 48 million animals, yet there has been little formal assessment of their welfare reported. Through observations of dairy cows on 38 farms in Kerala, India, we aimed to investigate the welfare of these animals and the practicality of animal-based assessments within common farming systems. Substantial welfare challenges were identified. All cows were close-tied (less than 1 m length) via a halter that pierced the nasal septum when housed, which was for the entire day (50% of farms) or part thereof. When outside access was available, it was also usually restricted by close-tying, longline tether, or hobbling. Ad libitum water was only available on 22% of farms and food access was also restricted (mean of 4.3 hrs/day). Future work should focus on encouraging dairy farmers in India to improve the welfare of their dairy cattle by ceasing to tie and tether cattle or at least providing tied and tethered cattle with exercise opportunities, unlimited access to drinking water and a readier supply of food (especially quality green forage/fodder); clean housing more frequently; provide strategies to prevent heat stress; breed cattle suited to environmental conditions and with increased resistance to heat stress; carry out welfare assessments more regularly using a validated protocol; rectify the causes of poor welfare. Such changes could substantially improve the welfare of tens of millions of cattle
Multiwavelength evidence for a 15-year periodic activity in the symbiotic nova V1016 Cygni
The ~15.1 years period found in the long-term UBV photoelectric and
photographic photometry of the symbiotic nova V1016 Cyg is detected also in the
(J-K) colour index and in the UV continuum and emission line fluxes from IUE
and HUT spectra. It could be interpreted either as the effect of recurrent
enhanced mass loss episodes from the Mira type variable companion to a hot
component along its ultra-wide orbit (proposed from recent HST observations) or
the true orbital period of the inner, unresolved binary of a triple system. A
410-day delay of the maximum of UV emission lines fluxes with respect to the
maximum of continuum was found. The pulsation period of the Mira type variable
was improved to 474+/-6 days.Comment: 7 pages, 7 PostScript figures. Accepted for pubblication in A&
Proof of all-order finiteness for planar beta-deformed Yang-Mills
We study a marginal deformation of N=4 Yang-Mills, with a real deformation
parameter beta. This beta-deformed model has only N=1 supersymmetry and a
U(1)xU(1) flavor symmetry. The introduction of a new superspace star-product
allows us to formulate the theory in N=4 light-cone superspace, despite the
fact that it has only N=1 supersymmetry. We show that this deformed theory is
conformally invariant, in the planar approximation, by proving that its Green
functions are ultra-violet finite to all orders in perturbation theory.Comment: 27 pages, several figures; v3: minor correction
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