GROUND BEEF: IMPLICATIONS FOR THE SOUTHEASTERN U.S. BEEF INDUSTRY

Livestock Production/Industries,

EVALUATING INCENTIVE PAYMENT PROGRAMS THROUGH AGGREGATE PRODUCTION RESPONSE: THE CASE OF MOHAIR

Production Economics,

Deformation and crystallization of Zr-based amorphous alloys in homogeneous flow regime

The purpose of this study is to experimentally investigate the interaction of inelastic deformation and microstructural changes of two Zr-based bulk metallic glasses (BMGs): Zr_(41.25)Ti_(13.75)Cu_(12.5)Ni_(10)Be_(22.5) (commercially designated as Vitreloy 1 or Vit1) and Zr_(46.75)Ti_(8.25)Cu_(7.5)Ni_(10)Be_(27.5) (Vitreloy 4, Vit4). High-temperature uniaxial compression tests were performed on the two Zr alloys at various strain rates, followed by structural characterization using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Two distinct modes of mechanically induced atomic disordering in the two alloys were observed, with Vit1 featuring clear phase separation and crystallization after deformation as observed with TEM, while Vit4 showing only structural relaxation with no crystallization. The influence of the structural changes on the mechanical behaviors of the two materials was further investigated by jump-in-strain-rate tests, and flow softening was observed in Vit4. A free volume theory was applied to explain the deformation behaviors, and the activation volumes were calculated for both alloys

A note on 4-rank densities

For certain real quadratic number fields, we prove density results concerning 4-ranks of tame kernels. We also discuss a relationship between 4-ranks of tame kernels and 4-class ranks of narrow ideal class groups. Additionally, we give a product formula for a local Hilbert symbol.Comment: 9 page

The Red-Cockaded Woodpecker Cavity Tree: A Very Special Pine

The adaptation of red-cockaded woodpeckers (Picoides borealis) to fire-maintained southern pine ecosystems has included the development of behaviors that permit the species to use living pines for their cavity trees. Their adaptation to pine ecosystems has also involved a major adjustment in the species\u27 breeding system to cooperative breeding, probably in response to the extended time period required to excavate a completed cavity in a living pine and the relative rarity of completed cavities for nesting. The characteristics of live pines make them variable in their suitability as cavity trees, leading to the evolution of selection behavior among woodpeckers. Red-cockaded woodpeckers require a very special type of pine for their cavity tree. Potential cavity trees must be sufficiently old because only older pines have heartwood of sufficient diameter to physically house a woodpecker cavity without breaching the resin producing sapwood. Older pines also have a larger diameter of heartwood higher in the pine, permitting higher cavity placement, well away from frequent fires. Older pines also have a higher occurrence rate of red heart fungus (Phellinus pini), which decays the heartwood allowing cavity excavation to proceed more quickly. The potential cavity tree also needs to have relatively thin sapwood, which reduces the time the woodpecker must spend excavating through living xylem tissue that exudes sticky pine resin when pecked. Red-cockaded woodpeckers scale loose bark from the bole of their cavity trees and excavate resin wells above and below cavity entrances. These behaviors create a resin barrier that is very effective in deterring predation by rat snakes (Elaphe spp.). Thus, the ability of pines to produce adequate resin is also important to the woodpecker. Red-cockaded wood- peckers can detect the pine\u27s ability to produce resin and select pines that are high producers. Higher yields of resin likely create better barriers against rat snakes. The socially dominant breeding male red-cockaded woodpecker selects the cavity tree that produces the most resin for its roost tree, which during spring becomes the group\u27s nest tree. Our recent research suggests that red-cockaded woodpeckers also select pines with particular resin chemistries. High concentrations of diterpenes may increase resin viscosity, stickiness, irritability, or other factors that may be important for creating a barrier against rat snakes

The Red-Cockaded Woodpecker\u27s Role in the Southern Pine Ecosystem, Population Trends and Relationships with Southern Pine Beetles

This study reviews the overall ecological role of the Red-cockaded Woodpecker (Picoides borealis)in the southern pine ecosystem. It is the only North American woodpecker species to become well adapted to a landscape that was relatively devoid of the substrate typically used by woodpeckers for cavity excavation (i.e. snags and decayed, living hardwoods). Its adaptation to use living pines for cavity excavation has expanded the use of this fire-disclimax ecosystem for numerous other cavity-using species. As such, the Red-cockaded Woodpecker represents an important keystone species of fire-disclimax pine ecosystems of the South. Historically, populations of this woodpecker and other cavity dependent species decreased dramatically with the logging of the southern pine forests between 1870 and 1930. Woodpecker populations continued to decline into the 1980s as a result of inadequate old-growth pine habitat, and suppression of fire which permitted encroachment of hardwoods into the previously pine-dominated ecosystem. Management practices initiated after 1988 have resulted in woodpecker population increases on Texas national forests. Cavity-tree mortality and southern pine beetle (Dendrocconus frontalis) infestation of cavity trees on the Angelina National Forest in eastern Texas were studied from 1983 through 1996. The intensive management activities initiated to stabilize severely declining woodpecker populations in 1989 may have increased beetle infestation rates of cavity trees in loblolly (Pinus taeda) and shortleaf (Pinus echinata) pine habitat resulting in a net loss of cavity trees over the past seven years. Initial results suggest that beetle-caused mortality of cavity trees may be related in part to ambient southern pine beetle population levels in surrounding forest stands

Investigating the Mechanism of JC Polyomavirus Endocytosis

The majority of the human population is infected with JC polyomavirus (JCPyV), which establishes an asymptomatic infection in the kidney of healthy individuals. In immunosuppressed individuals, the virus spreads to the brain and attacks glial cells, causing progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease. With limited treatments available, an improved understanding of the virus-host cell interactions during JCPyV infection is crucial for developing effective PML therapies. JCPyV internalization into host cells requires the serotonin 5- hydroxytryptamine type 2 (5-HT2) receptors. The mechanism by which the 5-HT2Rs mediate viral entry has not yet been characterized, yet it is thought to occur by clathrin- mediated endocytosis (CME). The objective of this research is to determine whether key 5-HT2R scaffolding proteins that mediate clathrin-dependent endocytosis are required for JCPyV infection. Reduction of cellular adaptor protein 2 (AP2), adaptor protein 180 (AP180), and clathrin by siRNA significantly reduced JCPyV infection, yet inhibition of calmodulin using a chemical calmodulin inhibitor had minimal effect on JCPyV infection. Taken together, these findings suggest these specific 5-HT2R scaffolding proteins are crucial for JCPyV infection. Additionally, this research is not limited to our understanding of JCPyV viral pathogenesis, a significant human pathogen with the potential to cause fatality, but can also be applied to understanding other neurotropic viruses or other viruses that enter by CME