NONCONSTANT PRICE EXPECTATIONS AND ACREAGE RESPONSE: THE CASE OF COTTON PRODUCTION IN GEORGIA

An adaptive regression model is used to examine the relative importance of cash and government support prices in determining cotton production over time. The results show that the cash price is more important as a source of price information for cotton producers than the government program price. The cash price was shown to have a greater influence on acreage response in every year, including periods thought to be dominated by government commodity programs.Adaptive regression, Cotton acreage response, Price expectations, Crop Production/Industries,

Day-to-day Variability of Stuttering

Variability has long been known to be a primary feature of the disorder of stuttering (Bloodstein & Bernstein Ratner, 2008; Costello & Ingham, 1984; Yaruss, 1997a, 1997b). Many factors that affect variability have been investigated (Brown, 1937; Johnson & Brown, 1935; Quarrington, Conway, & Siegel, 1962) yet the typical range of variability experienced by speakers remains unknown. This study will examine the speech of six adult speakers in three spontaneous speaking situations and two reading tasks. The frequency, duration, and types of stuttered events that occur on the tasks will be compared within and between speakers. The focus will be on describing variability in stuttering frequency and duration within speakers and attempting to detect consistent patterns between speakers

High-level Cryptographic Abstractions

The interfaces exposed by commonly used cryptographic libraries are clumsy, complicated, and assume an understanding of cryptographic algorithms. The challenge is to design high-level abstractions that require minimum knowledge and effort to use while also allowing maximum control when needed. This paper proposes such high-level abstractions consisting of simple cryptographic primitives and full declarative configuration. These abstractions can be implemented on top of any cryptographic library in any language. We have implemented these abstractions in Python, and used them to write a wide variety of well-known security protocols, including Signal, Kerberos, and TLS. We show that programs using our abstractions are much smaller and easier to write than using low-level libraries, where size of security protocols implemented is reduced by about a third on average. We show our implementation incurs a small overhead, less than 5 microseconds for shared key operations and less than 341 microseconds (< 1%) for public key operations. We also show our abstractions are safe against main types of cryptographic misuse reported in the literature

Enriched iron(III)-reducing bacterial communities are shaped by carbon substrate and iron oxide mineralogy

© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 3 (2012): 404, doi:10.3389/fmicb.2012.00404.Iron (Fe) oxides exist in a spectrum of structures in the environment, with ferrihydrite widely considered the most bioavailable phase. Yet, ferrihydrite is unstable and rapidly transforms to more crystalline Fe(III) oxides (e.g., goethite, hematite), which are poorly reduced by model dissimilatory Fe(III)-reducing microorganisms. This begs the question, what processes and microbial groups are responsible for reduction of crystalline Fe(III) oxides within sedimentary environments? Further, how do changes in Fe mineralogy shape oxide-hosted microbial populations? To address these questions, we conducted a large-scale cultivation effort using various Fe(III) oxides (ferrihydrite, goethite, hematite) and carbon substrates (glucose, lactate, acetate) along a dilution gradient to enrich for microbial populations capable of reducing Fe oxides spanning a wide range of crystallinities and reduction potentials. While carbon source was the most important variable shaping community composition within Fe(III)-reducing enrichments, both Fe oxide type and sediment dilution also had a substantial influence. For instance, with acetate as the carbon source, only ferrihydrite enrichments displayed a significant amount of Fe(III) reduction and the well-known dissimilatory metal reducer Geobacter sp. was the dominant organism enriched. In contrast, when glucose and lactate were provided, all three Fe oxides were reduced and reduction coincided with the presence of fermentative (e.g., Enterobacter spp.) and sulfate-reducing bacteria (e.g., Desulfovibrio spp.). Thus, changes in Fe oxide structure and resource availability may shift Fe(III)-reducing communities between dominantly metal-respiring to fermenting and/or sulfate-reducing organisms which are capable of reducing more recalcitrant Fe phases. These findings highlight the need for further targeted investigations into the composition and activity of speciation-directed metal-reducing populations within natural environments.This work was supported by a National Science Foundation Graduate Research Fellowship under grant no. DGE-0946799 and DGE-1144152 awarded to Christopher J. Lentini

Strategies for Wildlife Disease Surveillance

Epidemiologic surveillance is defined by the Centers for Disease Control and Prevention (CDC) as the ongoing systematic and continuous collection, analysis, and interpretation of health data\u27: The objective of surveillance is to generate data for rapid response to the detection of a disease of concern to apply prevention, control, or eradication measures as well as to evaluate such interventions. This is distinct from disease monitoring, which usually does not involve a particular response to disease detection. Surveillance for wildlife diseases has increased in importance due to the emergence and re-emergence of wildlife diseases that are threats to human, animal, and ecosystem health, or could potentially have a negative economic impact. It has been estimated that 75% of emerging human diseases are zoonotic in origin, of which the majority originate from wildlife (Taylor et al. 2001). However, there are unique challenges concerning wildlife disease surveillance such that disease and pathogens can be very difficult to detect and measure in wild animals. These challenges have been described previously (Wobeser 2006), but one of the primary issues is that disease in wildlife often goes unrecognized, especially in remote locations. Furthermore, sick and dead animals are very difficult to detect, as animals will disguise the signs of illness or hide when diseased. Carcasses from diseased animals are also rapidly removed by scavengers or will rapidly decompose, rendering them suboptimal for diagnostic purposes. There is also a lack of validated diagnostic tests for most wildlife disease agents as well as baseline data. The paucity of laboratory capacity with expertise in wildlife disease diagnostic investigation is also an impediment. Finally, surveillance networks for wildlife diseases that perform field investigations and report disease events are under-developed in most regions of the world. Despite these challenges, a number of very important epidemiological surveillance projects have been ongoing or recently developed, and some examples are described in this chapter. The examples are mostly drawn from the experiences of the U.S. Geological Survey National Wildlife Health Center (NWHC) and are provided to illustrate the different surveillance strategies and sampling techniques that can be used and have proven successful. Some future directions for wildlife disease surveillance are also suggested

Characterization of Borrelia Burgdorferi BlyA and BlyB Proteins: a Prophage-Encoded Holin-Like System

The conserved cp32 plasmid family of Borrelia burgdorferi was recently shown to be packaged into a bacteriophage particle (C. H. Eggers and D. S. Samuels, J. Bacteriol. 181:7308-7313, 1999), This plasmid encodes BlyA, a 7.4-kDa membrane-interactive protein, and BlyB, an accessory protein, which were previously proposed to comprise a hemolysis system. Our genetic and biochemical evidence suggests that this hypothesis is incorrect and that BlyA and BlyB function instead as a prophage-encoded holin or holin-like system for this newly described bacteriophage, An Escherichia coli mutant containing the blyAB locus that was defective for the normally cryptic host hemolysin SheA was found to be nonhemolytic, suggesting that induction of sheA by blyAB expression was responsible for the hemolytic activity observed previously, Analysis of the structural features of BlyA indicated greater structural similarity to bacteriophage-encoded holins than to hemolysins, Consistent with holin characteristics, subcellular localization studies with E. coli and B. burgdorferi indicated that BlyA is solely membrane associated and that BlyB is a soluble protein. Furthermore, BlyA exhibited a holin-like function by promoting the endolysin-dependent lysis of an induced lambda lysogen that was defective in the holin gene. Finally, induction of the cp32 prophage in B. burgdorferi dramatically stimulated blyAB expression. Our results provide the first evidence of a prophage-encoded holin within Borrelia