Variable major proteins of Borrelia hermsii. Epitope mapping and partial sequence analysis of CNBr peptides.

The variable major proteins (VMP) of serotypes 7 and 21 of the relapsing fever agent Borrelia hermsii were isolated by detergent extraction and high performance liquid chromatography. Cyanogen bromide (CNBr) digestion of the isolated VMP yielded two peptides of apparent molecular weights 20,000 (20 K) and 16 K from VMP7, and three peptides of 14.5, 14, and 7 K mol wt from VMP21. Serotype-specific monoclonal antibodies bound in Western blots to one of each of the two or three CNBr fragments from the homologous VMP. A single monoclonal antibody bound to the whole cells, the isolated VMP, and a CNBr fragment of both serotype 7 and serotype 21. (This crossreactive antibody did not, however, bind to any of four other serotypes examined.) Regional conservation of structure between VMP7 and VMP21 was also shown by amino acid sequence analysis of the N-termini of the five CNBr fragments. One pair of aligned fragments from VMP7 and VMP21 had 80% amino acid homology in sequence; a second pair had 40% homology. The partial amino acid homologies between two VMP suggest that these proteins are products of members of a polygene family

Constraints on the Choice of Work Hours: Agency vs. Specific-Capital

Most models of implicit lifetime contracts imply that at any particular point in time, workers' wages and value of marginal product (VMP) will diverge. As a result, the contract will have to specify hours as well as wages, since firms will desire to prevent workers from working more when the wage is greater than VMP and from working less when the wage is less than VMP. this divergence, combined with the fact that in efficient contracts, the hours are set so that VMP equals the marginal value of leisure, implies that workers will face binding hours constraints. We show that the two major models of lifetime contracts, the agency model and the firm-specific capital model, make opposite predictions regarding the relation between work hours constraints and job tenure. We test these predictions. Our results indicate that neither model of efficient long-term contracts explains the observed pattern of hours constraints. Therefore, we briefly consider other explanations.

Visibility maintenance via controlled invariance for leader-follower Dubins-like vehicles

The paper studies the visibility maintenance problem (VMP) for a leader-follower pair of Dubins-like vehicles with input constraints, and proposes an original solution based on the notion of controlled invariance. The nonlinear model describing the relative dynamics of the vehicles is interpreted as linear uncertain system, with the leader robot acting as an external disturbance. The VMP is then reformulated as a linear constrained regulation problem with additive disturbances (DLCRP). Positive D-invariance conditions for linear uncertain systems with parametric disturbance matrix are introduced and used to solve the VMP when box bounds on the state, control input and disturbance are considered. The proposed design procedure is shown to be easily adaptable to more general working scenarios. Extensive simulation results are provided to illustrate the theory and show the effectiveness of our approachComment: 17 pages, 24 figures, extended version of the journal paper of the authors submitted to Automatic

HANDLING DURABLE AND NONDURABLE FARM INPUT DECISIONS USING A SINGLE THEORETICAL FRAMEWORK

Students in economics are taught that the optimal usage of a nundurable input occurs when the value of its marginal product (VMP) equals its marginal cost (MC). However, this fundamental condition has rarely been extended to durable inputs. Even advanced textbooks have done little to compare and contrast the optimality conditions for durables versus nondurables. This paper outlines and compares a common VMP-MC decision for (1) nondurables in a single-period time horizon, (2) durables in a finite planning horizon, and (3) durables in an infinite planning horizon.Agricultural Finance,