Feedback equilibrium control during human standing

Equilibrium maintenance during standing in humans was investigated with a 3-joint (ankle, knee and hip) sagittal model of body movement. The experimental paradigm consisted of sudden perturbations of humans in quiet stance by backward displacements of the support platform. Data analysis was performed using eigenvectors of motion equation. The results supported three conclusions. First, independent feedback control of movements along eigenvectors (eigenmovements) can adequately describe human postural responses to stance perturbations. This conclusion is consistent with previous observations (Alexandrov et al., 2001b) that these same eigenmovements are also independently controlled in a feed-forward manner during voluntary upper-trunk bending. Second, independent feedback control of each eigenmovement is sufficient to provide its stability. Third, the feedback loop in each eigenmovement can be modeled as a linear visco-elastic spring with delay. Visco-elastic parameters and time-delay values result from the combined contribution of passive visco-elastic mechanisms and sensory systems of different modalities     

Karyotypes of three Garra species from Ethiopia

Three cyprinid species from Ethiopia, Garra dembeensis, G. makiensis , and G. quadrimaculata , were found to be characterized by the chromosome numbers (2n) of 50 and by the arm numbers of 82, 84, and 88, respectively.     

Radiation inactivation of alpha-chymotrypsin in aqueous solutions. The nature of the dose-response relationship

A study was made of possible reasons for deviations of the dose--response curves from the exponential function at low (less than or equal to 10(-6) M) and high (greater than or equal to 10(-4) M) initial concentrations of the enzyme. Factors influencing the degree of the deviation and type of the dependence of the radiation and chemical yield on the initial concentration of the enzyme are discussed. The data obtained are compared with those reported in the literature.     

Spatiotemporal patterns of macrophage migration inhibitory factor (Mif) expression in the mouse placenta

Background  

Macrophage migration inhibitory factor (MIF) has special pro-inflammatory roles, affecting the functions of macrophages and lymphocytes and counter-regulating the effects of glucocorticoids on the immune response. The conspicuous expression of MIF during human implantation and early embryonic development also suggests this factor acts in reproductive functions. The overall goal of this study was to evaluate Mif expression by trophoblast and embryo placental cells during mouse pregnancy.     

Karyological study of some cyprinid species from Ethiopia. The ploidy differences between large and small Barbus of Africa

Chromosome sets of nine species of Barbus and a species of Varicorhinus from Ethiopia were investigated. All large Barbus ( B. bynni, B. intermedius, B. ethiopicus ) and V. beso are shown to have 2N =150, whereas all small Barbus ( B. anema, B. kerstenii, B. paludinosus , and three unidentified (probably undescribed) species have 2N = 50. Based on the karyological data and on the published morphological data, an independent origin of small and large Barbus of Africa is suggested. The authors believe that large Barbus of Africa constitute a monophyletic group and that this group has no sister-group relationships with any of the small Barbus of Africa.