Open-loop implementation of feedbacks in parametric optimization problems for incompletely determined systems with distributed parameters

A constructive method for the design and real-time implementation of parameterized open-loop controls in the optimal feedback control of ensembles of trajectories of incompletely determined parabolic systems with distributed parameters is proposed. This method uses reduction to semiinfinite optimization problems, alternance properties of their solutions, and additional information about fundamental laws of the application domain. The practical application of the results is illustrated by the example of controlling nonstationary temperature fields under multiple disturbances, which is a problem of independent interest.     

Numerical methods for estimation of the attraction domain in the problem of control of the wheeled robot

The problem of controlling the wheeled robot was considered. In the robot model used, the current curvature of the trajectory of the objective point which is related by simple algebraic expressions with the angle of rotation of the front wheels was taken as the control parameter. Boundedness of the angle of rotation of the robot front wheels imposes bilateral constraints on the control. The control constraints influence strongly the transients of the robot entering the desired trajectory. Additionally, the nature of the transients depends on the initial conditions. The aim of the paper was to construct the attraction domain guaranteeing the given rate of the transients. The quadratic Lyapunov function was used to approximate this domain. The problem of determining the quadratic Lyapunov functions was reduced to the standard mathematical verification for solvability of the system of linear matrix inequalities. For the case where the aim of control is to drive the robot objective point to the straight segment of the trajectory, the results of calculations of the stability domains were presented for various formulations of the problem.     

Psychosocial effects of level of information and severity of disease on head-and-neck cancer patients

This study examined the psychosocial effects of levels of information available to patients and compared them with those of disease severity. A questionnaire with multiple-choice and open-ended questions assessing quality of life in various domains (e.g., fears and worries, functioning in the family) and scales assessing anxiety, anger, and depression were administered to patients and their partners or closest relatives. The subjects were 55 head-and-neck cancer patients (40 men and 15 women) in disease stages I to IV, grades of tumors G1 to G3-4, with disease durations ranging from three months to 21 years. They were divided into three groups on the basis of the amounts of information they had about their disease and prognosis, and again on the basis of disease severity, based on stages and patients' evaluations. The numbers of psychosocial variables differentiating significantly between the groups deviated significantly from chance in both groupings. The results showed more effects for information than for disease severity. The highly informed were better adjusted in interpersonal relations and had more intimacy with family, but had more fears, anxiety, changes in their lives, worries about health, and concern with physical symptoms. The reports of partners were fewer and lent some support to those of patients. Disease severity affected mostly fears, anxiety, and worries about health.     

J proteins catalytically activate Hsp70 molecules to trap a wide range of peptide sequences

Proteins of the Hsp70 family of ATPases, such as BiP, function together with J proteins to bind polypeptides in numerous cellular processes. Using a solid phase binding assay, we demonstrate that a conserved segment of the J proteins, the J domain, catalytically activates BiP molecules to bind peptides in its immediate vicinity. The J domain interacts with the ATP form of BiP and stimulates hydrolysis resulting in the rapid trapping of peptides, which are then only slowly released upon nucleotide exchange. Activation by the J domain allows BiP to trap peptides or proteins that it would not bind on its own. These results explain why BiP and probably all other Hsp70s can interact with a wide range of substrates and suggest that the J partner primarily determines the substrate specificity of Hsp70s.     

Intergroup competition for the provision of binary public goods.

An experimental paradigm is proposed for investigating interpersonal conflicts under conditions of intergroup competition. The paradigm constitutes an n-person game with imperfect and incomplete information in which the n players are divided into two groups, are each assigned monetary endowment, and must then decide independently and anonymously whether to keep the endowment or contribute it to the group's benefit. The group with the larger sum of contributions is provided with a monetary reward (binary public good), which is shared equally among all of its members regardless of their decision. Two alternative models are proposed and their testable implications are derived and discussed. Both assume maximization of expected utility, but their assumptions about the expectations each player holds about the decisions of the remaining players are different. The effects of predecisional communication are examined and several extensions of the basic paradigm are outlined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Light chain-dependent regulation of Kinesin's interaction with microtubules

We have investigated the mechanism by which conventional kinesin is prevented from binding to microtubules (MTs) when not transporting cargo. Kinesin heavy chain (HC) was expressed in COS cells either alone or with kinesin light chain (LC). Immunofluorescence microscopy and MT cosedimentation experiments demonstrate that the binding of HC to MTs is inhibited by coexpression of LC. Association between the chains involves the LC NH2-terminal domain, including the heptad repeats, and requires a region of HC that includes the conserved region of the stalk domain and the NH2 terminus of the tail domain. Inhibition of MT binding requires in addition the COOH-terminal 64 amino acids of HC. Interaction between the tail and the motor domains of HC is supported by sedimentation experiments that indicate that kinesin is in a folded conformation. A pH shift from 7.2 to 6.8 releases inhibition of kinesin without changing its sedimentation behavior. Endogenous kinesin in COS cells also shows pH-sensitive inhibition of MT binding. Taken together, our results provide evidence that a function of LC is to keep kinesin in an inactive ground state by inducing an interaction between the tail and motor domains of HC; activation for cargo transport may be triggered by a small conformational change that releases the inhibition of the motor domain for MT binding.     

Automated system of control of multiple-factor tests on a special-purpose stand for strength testing of structural elements

The structure of an automated complex developed by the authors for investigating strength properties of structural elements is examined. A complex set of problems on the formation, high-quality processing, and analysis of results and software for a wide spectrum of simulated effects is solved with the help of a two-level automated control system which provides for program control of acceleration, declaration, heating, and cooling of the tested elements. A set of new technical means is presented which facilitate considerable extension of the functional possibilities of the stand and reduction in the time for the tests.Translated from Problemy Prochnosti, No. 5, pp. 116–120, May, 1990.     

Mechanisms of ultra-low friction by hollow inorganic fullerene-like MoS2 nanoparticles

Inorganic Fullerene-like (IF)-MoS₂ nanoparticles were tested under boundary lubrication and ultra-high vacuum (UHV) and were found to give an ultra-low friction coefficient in both cases compared to hexagonal (h)-MoS₂ material. Previous works made by Rapoport et al. with IF-WS₂ revealed that the benefit effect of the inorganic fullerene-like materials decreases at high loads and sliding velocities. Nevertheless, under the conditions used in our experiments using high contact pressure (maximum pressure above 1.1 GPa in oil and 400 MPa in high vacuum) and slow sliding velocities (1.7 mm/s in oil test and 1 mm/s in high vacuum), friction always decreases and stabilizes at about 0.04 for 800 cycles in both cases. Therefore, IF-MoS₂ material appears to be a good candidate for use in various environments in regard to other MoS₂ crystal structures. Wear mechanisms were investigated using both High Resolution TEM and surface analyses (XPS) on the wear tracks. Wear particles collected from the flat wear scar show several morphologies, suggesting at least two lubricating mechanisms. As spherical particles are found in the wear debris, rolling may be a possible event. However, flattened and unwrapped IF-MoS₂ particles are often observed after friction. In this case, low friction is thought to be due either to sliding between IF-MoS₂ external flattened planes or to slip between individual unwrapped MoS₂ sheets.