672 research outputs found
Organic Crop Production Overview
This publication provides an overview of the key concepts and practices of certified organic crop production. It also presents perspectives on many of the notions, myths, and issues that have become associated with organic agriculture over time. A guide to useful ATTRA resources and to several non-ATTRA publications is provided
Universal structure of subleading infrared poles in gauge theory amplitudes
We study the origin of subleading soft and collinear poles of form factors
and amplitudes in dimensionally-regulated massless gauge theories. In the case
of form factors of fundamental fields, these poles originate from a single
function of the coupling, denoted G(alpha_s), depending on both the spin and
gauge quantum numbers of the field. We relate G(alpha_s) to gauge-theory matrix
elements involving the gluon field strength. We then show that G(alpha_s) is
the sum of three terms: a universal eikonal anomalous dimension, a universal
non-eikonal contribution, given by the coefficient B_delta (alpha_s) of delta(1
- z) in the collinear evolution kernel, and a process-dependent short-distance
coefficient function, which does not contribute to infrared poles. Using
general results on the factorization of soft and collinear singularities in
fixed-angle massless gauge theory amplitudes, we conclude that all such
singularities are captured by the eikonal approximation, supplemented only by
the knowledge of B_delta (alpha_s). We explore the consequences of our results
for conformal gauge theories, where in particular we find a simple exact
relation between the form factor and the cusp anomalous dimension.Comment: 29 pages, 1 figure; version published on JHEP, two added reference
Subprime and predatory lending in rural America: mortgage lending practices that can trap low-income rural people
This brief examines predatory mortgage loans and the harmful impact they have on rural homeowners and their communities. The report finds that minorities and low-income people are more likely to fall victim to higher-cost loans. The brief includes recommendations for policy changes at the state and federal levels, as well as advice on identifying and avoiding predatory loans
A Sociological Perspective of the Mobile Home in Appalachian Eastern Kentucky
A thesis presented to the faculty of the College of Education and Behavioral Sciences at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Arts in Sociology by Travis Lance George on December 2, 1998
The Role of RFamide-Related Peptide-3 in Age-Related Reproductive Decline in Female Rats.
Reproductive senescence, the point in time when females cease to show estrous cyclicity, is associated with endocrine changes in the hypothalamus, pituitary, and gonads. However, the mechanisms triggering this transition are not well understood. To gain a better understanding of the top-down control of the transition from reproductive competence to a state of reproductive senescence, we investigated middle-aged female rats exhibiting varying degrees of reproductive decline, including individuals with normal cycles, irregular cycles, and complete cessation of cycles. We identified hormonal changes in the brain that manifest before ovarian cycles exhibit any deterioration. We found that females exhibit an increase in RFamide-related peptide-3 (RFRP3) mRNA expression in the hypothalamus in middle age prior to changes in estrous cycle length. This increase is transient and followed by subsequent decreases in kisspeptin (KiSS1) and gonadotropin-releasing hormone (GnRH) mRNA expression. Expression of RFRP3 and its receptor also increased locally in the ovaries with advancing age. While it is well known that aging is associated with decreased GnRH release and downstream disruption of the hypothalamic-pituitary-gonadal (HPG) axis, herein, we provide evidence that reproductive senescence is likely triggered by alterations in a network of regulatory neuropeptides upstream of the GnRH system
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Neurosecretory Protein GL Induces Fat Accumulation in Chicks.
We recently found a previously unidentified cDNA in chicken hypothalamus which encodes the precursor for neurosecretory protein GL (NPGL). A previous study showed that intracerebroventricular (i.c.v.) infusion of NPGL caused body mass gain in chicks. However, it was not clear which part(s) of the body gained mass. In the present study, we investigated which tissues increased in mass after chronic i.c.v. infusion of NPGL in chicks. We found that NPGL increased the masses of the liver, abdominal fat, and subcutaneous fat, while NPGL did not affect the masses of muscles, including pectoralis major, pectoralis minor, and biceps femoris. Oil Red O staining revealed that fat deposition had occurred in the liver. In addition, the size of the lipid droplets in the abdominal fat increased. Furthermore, we found an upregulation of lipogenesis and downregulation of lipolysis in the abdominal fat, but not in the liver. These results indicate that NPGL is involved in fat storage in chicks
The Two-loop Anomalous Dimension Matrix for Soft Gluon Exchange
The resummation of soft gluon exchange for QCD hard scattering requires a
matrix of anomalous dimensions. We compute this matrix directly for arbitrary 2
to n massless processes for the first time at two loops. Using color generator
notation, we show that it is proportional to the one-loop matrix. This result
reproduces all pole terms in dimensional regularization of the explicit
calculations of massless 2 to 2 amplitudes in the literature, and it predicts
all poles at next-to-next-to-leading order in any 2 to n process that has been
computed at next-to-leading order. The proportionality of the one- and two-loop
matrices makes possible the resummation in closed form of the
next-to-next-to-leading logarithms and poles in dimensional regularization for
the 2 to n processes.Comment: 5 pages, 1 figure, revte
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