Coordinates transformation and learning control for visually-guided voluntary movement with iteration: A Newton-like method in a function space

In order to control visually-guided voluntary movements, the central nervous system (CNS) must solve the following three computational problems at different levels: (1) determination of a desired trajectory in the visual coordinates, (2) transformation of the coordinates of the desired trajectory to the body coordinates and (3) generation of motor command. In this paper, the second and the third problems are treated at computational, representational and hardware levels of Marr. We first study the problems at the computational level, and then propose an iterative learning scheme as a possible algorithm. This is a trial and error type learning such as repetitive training of golf swing. The amount of motor command needed to coordinate activities of many muscles is not determined at once, but in a step-wise, trial and error fashion in the course of a set of repetitions. Actually, the motor command in the (n+1)-th iteration is a sum of the motor command in then-th iteration plus two modification terms which are, respectively, proportional to acceleration and speed errors between the desired trajectory and the realized trajectory in then-th iteration. We mathematically formulate this iterative learning control as a Newton-like method in functional spaces and prove its convergence under appropriate mathematical conditions with use of dynamical system theory and functional analysis. Computer simulations of this iterative learning control of a robotic manipulator in the body or visual coordinates are shown. Finally, we propose that areas 2, 5, and 7 of the sensory association cortex are possible sites of this learning control. Further we propose neural network model which acquires transformation matrices from acceleration or velocity to motor command, which are used in these schemes.     

Directly observed 15N NMR spectra of uniformly enriched proteins

The proteins cytochrome c2, cytochrome c', and ribulosebisphosphate carboxylase/oxygenase from Rhodospirillum rubrum were enriched in 15N by growth of the organism on 15NH4Cl. The proteins were purified to homogeneity and studied by 15N NMR. Longitudinal and transverse relaxation times as well as the nuclear Overhauser effects were determined for various groups of the proteins which vary in molecular weight from 13,000 to 114,000. The values of these parameters for the amide resonances or for groups thought to be rigid were consistent with the molecular weights of the proteins. Relaxation times of the amino-terminal alpha-amino groups and the side chain nitrogen atoms of arginine and lysine were consistent with much more rapid motion. Nitrogen atoms having bound protons were generally found to be decoupled from the protons by chemical exchange. Demonstrable 1H-15N coupling was taken as an indication that exchange was hindered, either by hydrogen bonding interactions or by inaccessibility of the group to solvent. Histidine side chain nitrogen atoms, which experience a large chemical shift upon protonation/deprotonation, were often found to be broadened beyond detectability by chemical exchange and tautomerization. Strategies for improving sensitivity and for obtaining specific peak assignments are also discussed.     

Ecological description of ground beetle communities (Coleoptera, Carabidae) in northern taiga meadows of Arkhangelsk Region

Species composition and ecological structure of ground beetle population was studied in northern taiga meadows of the Arkhangelsk Region. Meadows in the northern forest zone proved to harbor 91 ground beetle species. Carabid complexes formed in the intrazonal biocenoses of the northern forest zone can be as rich as the family topical groups in the southern forest zone by the number of species and ecological diversity. Ecological properties of the fauna and ground beetle population proved similar in different parts of the forest zone. The proportion of stenobiotic meadow species proved to decrease while that of ecologically plastic ones increased from south to north. The proportion of the genus Harpalus decreased in the ground beetle population while the number of Amara species remained unaltered and their abundance increased. The changes in the species composition caused no transformation of the ecological structure of ground beetle population since they were limited to a single life form or guild.     

Antidiabetic and Anticoagulant Properties of Heparin–Glutamic Acid Complex

Natural heparin complexes proved to activate the anticoagulation system. The obtained experimental data convincingly confirm that glutamic acid alone, and particularly in a complex with heparin, has a considerable preventive potential and efficiently protects experimental animals with induced diabetes mellitus.     

Application of a photosystem II model for analysis of fluorescence induction curves in the 100 ns to 10 s time domain after excitation with a saturating light pulse

A mathematical model of photosystem II (PSII) events was used to analyze chlorophyll fluorescence transients in the time domain from 100 ns to 10 s after excitation with a saturating 10-ns flash, applied as a part of specialized illumination protocol, using preparations of a thermophilic strain of the unicellular green alga, Chlorella pyrenoidosa Chick (using both intact and diuron-treated cells). Analysis of simulation results has proven that particular attention should be given to flash-induced recombination processes, including nonradiative recombination in PSII, while subsequent charge transfer along the electron transport chain of thylakoid membrane can be adequately described by a single reaction of quinone reoxidation. The PSII model was extended by taking inhibition by diuron of the electron transport in the acceptor side of PSII into account, which allowed simulation of fluorescence induction curves observed in the presence of this inhibitor. The model parameters were determined (stromal pH, rate constants of nonradiative recombination, and the initial reduction state of the quinone pool) which provided adequate simulation of experimentally observed ratios of the maximal and initial fluorescence levels (F _m/F ₀).     

The antioxidant characteristics of medicinal plant extracts from Western Siberia

An antioxidant activity of the water-alcohol extracts of leaves of ten herbs from Western Siberia was studied. In vivo the capability of extracts to protect cells of Escherichia coli against the bacteriostatic action of H ₂O₂ and the influence of the extracts on the expression of the antioxidant gene katG coding catalase-hydroperoxidase I were investigated. In vitro the radical-binding activity with DPhPG^· (1,1-diphenyl-2-picrylhydrazyl radical), the chelating capability with ferrozine, and total composition of flavonoids and tannins were determined. The extracts of Filipendula stepposa and Limonium gmelinii were characterized by the highest antioxidant activity. According to data, the test extracts could have an antioxidant effect on bacteria in different ways at once including the direct inhibition of ROS (reactive oxygen species), iron ion chelation and antioxidant gene induction.     

Demonstration of neutralizing autoantibodies against IL-1 alpha in sera from patients with rheumatoid arthritis

We have recently reported the presence of IgG which has a potent inhibitory activity against IL-1 alpha in some sera from patients with rheumatoid arthritis. The mechanism of this inhibition by IgG against IL-1 alpha is now elucidated. IgG with IL-1 alpha-inhibitory activity inhibited the binding of 125I-IL-1 alpha to receptors on rheumatoid synovial cells. In addition, preincubation of synovial cells with the inhibitory IgG did not block the binding of 125I-IL-1 alpha to receptors, suggesting a direct interaction between IgG and IL-1 alpha. To examine which region of the IgG, namely Fab or Fc region, has the inhibitory activity, the IgG was digested with papain, and Fab and Fc fragments were purified. Fab fragments, but not Fc fragments, inhibited both IL-1 alpha-induced thymocyte-proliferation and the binding of 125I-IL-1 alpha to receptors. We further demonstrated that the inhibitory IgG which was bound to protein A Sepharose could bind a significant amount of 125I-IL-1 alpha, whereas only a negligible binding of the radiolabeled ligand was detected when IgG without the inhibitory activity was used as control. Moreover, the binding of 125I-IL-1 alpha to IgG with the inhibitory activity was clearly blocked by Fab fragments of IgG having the inhibitory activity. Finally, affinity-purified IgG over an IL-alpha affinity column showed approximately 100-fold more potent inhibitory activity on IL-1 alpha-induced thymocyte proliferation compared with untreated IgG. From these results, we conclude that IgG molecules with IL-1-alpha-inhibitory activity are neutralizing autoantibodies against IL-1 alpha.