Antigenic variation in the African trypanosome: molecular mechanisms and phenotypic complexity

Antigenic variation is an immune evasion strategy that has evolved in viral, bacterial and protistan pathogens. In the African trypanosome this involves stochastic switches in the composition of a variant surface glycoprotein (VSG) coat, using a massive archive of silent VSG genes to change the identity of the single VSG expressed at a time. VSG switching is driven primarily by recombination reactions that move silent VSGs into specialized expression sites, though transcription-based switching can also occur. Here we discuss what is being revealed about the machinery that underlies these switching mechanisms, including what parallels can be drawn with other pathogens. In addition, we discuss how such switching reactions act in a hierarchy and contribute to pathogen survival in the face of immune attack, including the establishment and maintenance of chronic infections, leading to host-host transmission

Feeding Techniques To Increase Calf Growth In The First Two Months Of Life

End of project reportData from Cornell University and the University of Illinois in the USA suggested that average daily liveweight gains of 900 to 1000 g/calf/day could be achieved from birth to weaning provided the calf milk replacer (CMR) is formulated to meet the calf’s amino acid requirements for such a rate of gain. Their findings suggested a daily milk replacer DM allowance of 1250 to 1500 g/d with a crude protein content of 26 to 30%. A series of studies were undertaken, at ARINI with home born dairy calves and at Grange Beef Research Centre with purchased dairy calves, to determine the effect of increasing the daily milk replacer DM allowance and or increasing the crude protein content of the CMR on calf performance.The main outcomes of these studies were There was no growth or intake response in any of the studies to increasing the crude protein content of the CMP from 23% to 28%. Calf growth rates responded to increasing the dailymilk replacer allowance from 600 to 1200 g/day for both home bred and purchased calves. However, the effect was not significant post-weaning in any of the studies. In all of the studies (for both home reared and purchased calves) feeding a high level of CMRdecreased concentrate DM intake. However, the calves concentrate intakes were similar post-weaning. The home bred calves with free access to the milk replacer feeders failed to consume their 1200 g/day allowance. Calves offered 600 or 1200 g of CMR/day had average consumption of 554 and 944 g/d, respectively, in the milk feeding period. Feeding a high (1200 g/d) compared to a low level (600 g/d) CMRdiet for the first 56 days had no significant effect on carcass weight or carcass characteristics when purchased male calves were slaughtered off an ad libitum concentrate diet after 388 days. The final carcass weights were 231 and 240 kg for the respective 600 and 1200 g/d CMR. Reducing the fat content of the CMRfrom 18% to 12% did not have any effect on concentrate intake or liveweight gain

Computer and Internet Use by Great Plains Farmers

This study uses data from a 2001 survey of Great Plains farmers to explore the adoption, usage patterns, and perceived benefits of computers and the Internet. Adoption results suggest that exposure to the technology through college, outside employment, friends, and family is ultimately more influential than farmer age and farm size. Notably, about half of those who use the Internet for farm-related business report zero economic benefits from it. Whether a farmer perceives that the Internet generates economic benefits depends primarily on how long the farmer has used the Internet for farm business and for what purposes.agriculture, competitiveness, net benefits, technology adoption, Research and Development/Tech Change/Emerging Technologies,

Computer and Internet Use by Great Plains Farmers

We use data from a 2001 survey of Great Plains farmers to explore the adoption, usage patterns, and perceived benefits of computers and the Internet. Our adoption results suggest that exposure to the technology through college, outside employment, friends, and family is ultimately more influential than farmer age and farm size. Notably, about half of those who use the Internet for farm-related business report zero economic benefits from it. Whether a farmer perceives that the Internet generates economic benefits depends primarily on how long the farmer has used the Internet for farm business and for what purposes.Farm Management, Research and Development/Tech Change/Emerging Technologies,

Productivity Growth, Technological Progress, and Technical Efficiency in the Heartland and Southern Cotton States:1996-1999.

Given recent concerns expressed about the structural transformation of agriculture and the health of the family farm this study provides a measure of the economic health of small and large farms at the state level. We use nonparametric frontier methods to measure and explain changes in the efficiency, productivity, and technological change of U.S. farms, employing USDAs annual 1996 to 1999 surveys of farms. Our results for the corn and cotton states analyzed identify particularly weak economic performance of small farms in Iowa, Louisiana, Oklahoma, and Wisconsin and of large farms in Missouri, Oklahoma, and South Carolina. Our results also indicate strong performance of small farms in several states. Thus, these results give policy makers a more detailed and up to date view of the overall economic health of the agricultural sector in the states analyzed than has previously been possible with aggregate state level analyses.Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,

EFFECTIVE COSTS AND CHEMICAL USE IN U.S. AGRICULTURAL PRODUCTION: BENEFITS AND COSTS OF USING THE ENVIRONMENT AS A "FREE" INPUT

This study uses a cost-function-based model of production processes in U.S. agriculture to represent producers' input and output decisions, and the implied costs of reductions in risk associated with leaching and runoff from agricultural chemical use. The model facilitates evaluation of the statistical significance of measured shadow values for "bad" outputs, and their input- and output-specific components, with a focus on the impacts on pesticide demand and its quality and quantity aspects. The shadow values of risk reduction are statistically significant, and imply increased demand for effective pesticides over time that stem largely from improvements in quality due to embodied technology, and that vary substantively by region.Environmental Economics and Policy, Farm Management,

Brief of Amici Curiae Administrative Law Scholars in Support of Petitioner in SEC v. Jarkesy

This is an amicus brief that several scholars have filed in the Supreme Court in SEC v. Jarkesy. The brief argues that (1) the double-for-cause removal requirement of Free Enterprise Fund v. PCAOB should not apply to ALJs at the SEC; and (2) the Seventh Amendment does not apply to administrative adjudication at the SEC

Configurable Multi-Purpose Processor

Advancements in technology have allowed the miniaturization of systems used in aerospace vehicles. This technology is driven by the need for next-generation systems that provide reliable, responsive, and cost-effective range operations while providing increased capabilities such as simultaneous mission support, increased launch trajectories, improved launch, and landing opportunities, etc. Leveraging the newest technologies, the command and telemetry processor (CTP) concept provides for a compact, flexible, and integrated solution for flight command and telemetry systems and range systems. The CTP is a relatively small circuit board that serves as a processing platform for high dynamic, high vibration environments. The CTP can be reconfigured and reprogrammed, allowing it to be adapted for many different applications. The design is centered around a configurable field-programmable gate array (FPGA) device that contains numerous logic cells that can be used to implement traditional integrated circuits. The FPGA contains two PowerPC processors running the Vx-Works real-time operating system and are used to execute software programs specific to each application. The CTP was designed and developed specifically to provide telemetry functions; namely, the command processing, telemetry processing, and GPS metric tracking of a flight vehicle. However, it can be used as a general-purpose processor board to perform numerous functions implemented in either hardware or software using the FPGA s processors and/or logic cells. Functionally, the CTP was designed for range safety applications where it would ultimately become part of a vehicle s flight termination system. Consequently, the major functions of the CTP are to perform the forward link command processing, GPS metric tracking, return link telemetry data processing, error detection and correction, data encryption/ decryption, and initiate flight termination action commands. Also, the CTP had to be designed to survive and operate in a launch environment. Additionally, the CTP was designed to interface with the WFF (Wallops Flight Facility) custom-designed transceiver board which is used in the Low Cost TDRSS Transceiver (LCT2) also developed by WFF. The LCT2 s transceiver board demodulates commands received from the ground via the forward link and sends them to the CTP, where they are processed. The CTP inputs and processes data from the inertial measurement unit (IMU) and the GPS receiver board, generates status data, and then sends the data to the transceiver board where it is modulated and sent to the ground via the return link. Overall, the CTP has combined processing with the ability to interface to a GPS receiver, an IMU, and a pulse code modulation (PCM) communication link, while providing the capability to support common interfaces including Ethernet and serial interfaces boarding a relatively small-sized, lightweight package

Chlamydia muridarum Genital and Gastrointestinal Infection Tropism Is Mediated by Distinct Chromosomal Factors

Some members of the genus Chlamydia, including the human pathogen Chlamydia trachomatis, infect multiple tissues, including the genital and gastrointestinal (GI) tracts. However, it is unknown if bacterial targeting to these sites is mediated by multifunctional or distinct chlamydial factors. We previously showed that disruption of individual large clostridial toxin homologs encoded within the Chlamydia muridarum plasticity zone were not critical for murine genital tract infection. Here, we assessed whether cytotoxin genes contribute to C. muridarum GI tropism. Infectivity and shedding of wild-type (WT) C. muridarum and three mutants containing nonsense mutations in different cytotoxin genes, tc0437, tc0438, and tc0439, were compared in mouse genital and GI infection models. One mutant, which had a nonsense mutation in tc0439, was highly attenuated for GI infection and had a GI 50% infectious dose (ID50) that was 1,000 times greater than that of the WT. GI inoculation with this mutant failed to elicit anti-chlamydial antibodies or to protect against subsequent genital tract infection. Genome sequencing of the tc0439 mutant revealed additional chromosomal mutations, and phenotyping of additional mutants suggested that the GI attenuation might be linked to a nonsense mutation in tc0600 The molecular mechanism underlying this dramatic difference in tissue-tropic virulence is not fully understood. However, isolation of these mutants demonstrates that distinct chlamydial chromosomal factors mediate chlamydial tissue tropism and provides a basis for vaccine initiatives to isolate chlamydia strains that are attenuated for genital infection but retain the ability to colonize the GI tract and elicit protective immune responses

How stigma impacts on people with psychosis: The mediating effect of self-esteem and hopelessness on subjective recovery and psychotic experiences

This study aimed to examine how stigma impacts on symptomatic and subjective recovery from psychosis, both concurrently and longitudinally. We also aimed to investigate whether self-esteem and hopelessness mediated the observed associations between stigma and outcomes. 80 service-users with psychosis completed symptom (Positive and Negative Syndrome Scale) and subjective recovery measures (Process of Recovery Questionnaire) at baseline and 6-months later, and also completed the King Stigma Scale, the Self-Esteem Rating Scale and the Beck Hopelessness Scale at baseline. In cross sectional regression and multiple mediation analyses of the baseline data, we found that stigma predicted both symptomatic and subjective recovery, and the effects of stigma on these outcomes were mediated by hopelessness and self-esteem. When the follow-up data were examined, stigma at baseline continued to predict recovery judgements and symptoms. However, self-esteem only mediated the effect of stigma on PANSS passive social withdrawal. Self-esteem and hopelessness should be considered in interventions to reduce the effects of stigma. Interventions that address the current and long-term effects of stigma may positively affect outcome for people being treated for psychosis