TESTING FOR DISEQUILIBRIUM IN THE DEMAND FOR AGRICULTURAL INPUTS

A dynamic system of cost-share equations for agricultural inputs is used to test for the presence of input disequilibrium. This dynamic system incorporates a disequilibrium adjustment process into input-share equations derived from a translog cost function. The disequilibrium process is represented as a generalized partial adjustment model where disequilibrium in one input may affect other inputs. Results from this analysis suggest applications of translog share systems to agriculture under static equilibrium assumptions are inappropriate.Demand and Price Analysis, Research Methods/ Statistical Methods,

Integrated simulation and control of servo-driven end effector

This paper discusses the development of a Controls Lab Station for the rapid-prototyping of control systems and hardware-in-the-loop simulation. The Controls Lab Station consists of an IBM-compatible PC and the MX3 1 Development System from Integrated Motions, Inc. Functionality is achieved through a mix of standard and custom software packages. The proper use of the system is outlined including the overall design cycle concept. The integration of system components is summarized, and specific control experiments are discussed using a specific plant. The chosen plant is a servo-driven gripper with finger-mounted force sensors, capable of supporting both position and force control. The custom designed gripper interface box and software utilities are discussed. Several learn-by-example control experiments for the gripper are explained in detail, and the results presented

Cranial and trunk neural crest cells use different mechanisms for attachment to extracellular matrices

We have used a quantitative cell attachment assay to compare the interactions of cranial and trunk neural crest cells with the extracellular matrix (ECM) molecules fibronectin, laminin and collagen types I and IV. Antibodies to the β_1 subunit of integrin inhibited attachment under all conditions tested, suggesting that integrins mediate neural crest cell interactions with these ECM molecules. The HNK-1 antibody against a surface carbohydrate epitope under certain conditions inhibited both cranial and trunk neural crest cell attachment to laminin, but not to fibronectin. An antiserum to α_1 intergrin inhibited attachment of trunk, but not cranial, neural crest cells to laminin and collagen type I, though interactions with fibronectin or collagen type IV were unaffected. The surface properties of trunk and cranial neural crest cells differed in several ways. First, trunk neural crest cells attached to collagen types I and IV, but cranial neural crest cells did not. Second, their divalent cation requirements for attachment to ECM molecules differed. For fibronectin substrata, trunk neural crest cells required divalent cations for attachment, whereas cranial neural crest cells bound in the absence of divalent cations. However, cranial neural crest cells lost this cation-independent attachment after a few days of culture. For laminin substrata, trunk cells used two integrins, one divalent cation-dependent and the other divalent cation-independent (Lallier, T. E. and Bronner-Fraser, M. (1991) Development 113, 1069–1081). In contrast, cranial neural crest cells attached to laminin using a single, divalent cation-dependent receptor system. Immunoprecipitations and immunoblots of surface labelled neural crest cells with HNK-1, α_1 integrin and β_1 integrin antibodies suggest that cranial and trunk neural crest cells possess biochemically distinct integrins. Our results demonstrate that cranial and trunk cells differ in their mechanisms of adhesion to selected ECM components, suggesting that they are non-overlapping populations of cells with regard to their adhesive properties

Rewarding Persistence: Effects of a Performance-Based Scholarship Program for Low-Income Parents

This report describes the impacts of a performance-based scholarship program with a counseling component on academic success and persistence among low-income parents. Students who participated in the program, which was operated at two New Orleans-area colleges as part of MDRC's multisite Opening Doors demonstration, were more likely to stay in school, get higher grades, and earn more credits

A crab is not a fish: unique aspects of the crustacean endocrine system and considerations for endocrine toxicology

International audienceCrustaceans—and arthropods in general—exhibit many unique aspects to their physiology. These include the requirement to moult (ecdysis) in order to grow and reproduce, the ability to change color, and multiple strategies for sexual differentiation. Accordingly, the endocrine regulation of these processes involves hormones, receptors, and enzymes that differ from those utilized by vertebrates and other non-arthropod invertebrates. As a result, environmental chemicals known to disrupt endocrine processes in vertebrates are often not endocrine disruptors in crustaceans; while, chemicals that disrupt endocrine processes in crustaceans are often not endocrine disruptors in vertebrates. In this review, we present an overview of the evolution of the endocrine system of crustaceans, highlight endocrine endpoints known to be a target of disruption by chemicals, and identify other components of endocrine signaling that may prove to be targets of disruption. This review highlights that crustaceans need to be evaluated for endocrine disruption with consideration of their unique endocrine system and not with consideration of the endocrine system of vertebrates

Effect of magnetic field on the phase transition in a dusty plasma

The formation of self-consistent crystalline structure is a well-known phenomenon in complex plasmas. In most experiments the pressure and rf power are the main controlling parameters in determining the phase of the system. We have studied the effect of externally applied magnetic field on the configuration of plasma crystals, suspended in the sheath of a radio-frequency discharge using the Magnetized Dusty Plasma Experiment (MDPX) device. Experiments are performed at a fixed pressure and rf power where a crystalline structure is formed within a confining ring. The magnetic field is then increased from 0 to 1.28 T. We report on the breakdown of the crystalline structure with increasing magnetic field. The magnetic field affects the dynamics of the plasma particles and first leads to a rotation of the crystal. At higher magnetic field, there is a radial variation (shear) in the angular velocity of the moving particles which we believe leads to the melting of the crystal. This melting is confirmed by evaluating the variation of the pair correlation function as a function of magnetic field.Comment: 9 pages, 5 figure

HIV and STI Risk for Young Blacks in High Prevalence Areas: Implications for Health Equity in Communities Hosting Historically Black Colleges and Universities (HBCUs)

Background Every year, thousands of young, black, high school graduates who are seeking higher education, attend one of the 105 historically black colleges and universities (HBCUs) located primarily in the south and east. The objective of the research was to examine the geographic proximity of HBCUs to areas of high HIV and STI disease burden among college age people to assess infectivity of potential sex partners in the areas surrounding HBCUs. Methods We examined the 14 states reporting the greatest HIV diagnoses burden among persons age 20-24 years old and STI burden among persons age 15 to 24 years old available for 2010. The Geographic Information System was used to create a spatially referenced data base of state level HIV and STI disease rates and HBCU zip codes to answer the question “How many HBCUs are in this location?” Maps were created to show HBCU locations in states along with the associated HIV and STI disease burden. Findings Results suggest high HIV and STI disease burden in the general population of persons ages 15-24 in 10 states with 4 or more Historically Black Colleges and Universities (HBCU) and an overall high rate of HIV and STI exposure in the pool of potential sex partners. Less risky behavior by minority young adults attending HBCUs could potentially translate to high risk for contracting the diseases because of high prevalence in surrounding communities. Public Health Message Public health agencies may want to consider prioritizing HBCUs for enhanced HIV and STI prevention collaborative efforts in those areas with a high burden of HIV and other STIs