Kinematic Foot Types in Youth with Equinovarus Secondary to Hemiplegia

Background Elevated kinematic variability of the foot and ankle segments exists during gait among individuals with equinovarus secondary to hemiplegic cerebral palsy (CP). Clinicians have previously addressed such variability by developing classification schemes to identify subgroups of individuals based on their kinematics. Objective To identify kinematic subgroups among youth with equinovarus secondary to CP using 3-dimensional multi-segment foot and ankle kinematics during locomotion as inputs for principal component analysis (PCA), and K-means cluster analysis. Methods In a single assessment session, multi-segment foot and ankle kinematics using the Milwaukee Foot Model (MFM) were collected in 24 children/adolescents with equinovarus and 20 typically developing children/adolescents. Results PCA was used as a data reduction technique on 40 variables. K-means cluster analysis was performed on the first six principal components (PCs) which accounted for 92% of the variance of the dataset. The PCs described the location and plane of involvement in the foot and ankle. Five distinct kinematic subgroups were identified using K-means clustering. Participants with equinovarus presented with variable involvement ranging from primary hindfoot or forefoot deviations to deformtiy that included both segments in multiple planes. Conclusion This study provides further evidence of the variability in foot characteristics associated with equinovarus secondary to hemiplegic CP. These findings would not have been detected using a single segment foot model. The identification of multiple kinematic subgroups with unique foot and ankle characteristics has the potential to improve treatment since similar patients within a subgroup are likely to benefit from the same intervention(s)

Cross-taxon congruence between predatory arthropods and plants across Mediterranean agricultural landscapes

Although arthropods are among the most diverse, abundant and ecologically important animals in terrestrial ecosystems, they are generally neglected in most biodiversity inventories due to their complex systematics and overwhelming diversity, coupled with the current decline in the number of taxonomists. For this reason, several surrogate groups for arthropod diversity have been proposed, with plants being identified as a good putative cross-taxon indicator. By sampling plants and three groups of ground-dwelling arthropods (rove beetles, ground beetles and spiders) in 300 sites across 15 landscapes including multiple semi-natural and agricultural habitats, we tested for habitat-dependence and scale-dependence in the cross-taxon congruence. Plant species richness was a poor predictor of the species richness of predatory arthropods. Among the predator groups, ground beetles appeared as the best potential surrogate for the other ground-dwelling predators. This is backed by the fact that ground beetles were extremely diverse and abundant in all habitats and are usually easier to identify than both rove beetles and spiders. Decreasing the scale at which the cross-taxon congruence was tested improved the strength of the cross-taxon congruence. Although plant species richness was not a suitable indicator for the diversity of predatory arthropods, vegetation structure played a significant role in influencing cross-taxon congruence in both natural and agricultural habitats. Our results highlight the need to explore the cross-taxon relationships at a fine habitat resolution scale, as strong correlations were obtained only by taking into account habitat identity

Refined localization of human connexin32 gene locus, GJB1, to Xq13.1

Connexins are the peptide subunits of gap junctions that interconnect cells to allow the direct, intercellular transfer of small molecules. Recently, the human connexin32 gene (locus designation GJB1) has been regionally mapped by three other laboratories to Xp11-q13, Xcen-q22, and Xp11-q22. The smallest region of overlap from these studies is Xcen-q13. By using a series of somatic cell hybrid mapping panels and a rat connexin32 cDNA probe, we have localized the human GJB1 locus to a much smaller region in proximal Xq13.1, in interval 8, as described by Lafreniere et al. (8).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30018/1/0000386.pd

Rent Building, Rent Sharing - A Panel Country-Industry Empirical Analysis

Through panel estimates using OECD country-industry statistics, this paper aims to clarify the determinants of rent creation and the mechanisms of rent sharing, and the role of market regulations in these processes. The empirical analysis is carried out in two steps. The first explains the rent creation process. For each country-industry-year observation, the size of rents, measured by the value added price relative to the GDP price, is assumed to depend solely on direct anti-competitive regulations on services and goods. The second step explains the rent sharing process. Three destinations of rents are distinguished for each country-industry-year observation: upstream industries, capital and labour. The main empirical findings are as follows. Regarding the rent creation, direct anti-competitive regulations are associated with a very significant rise in rent size. Concerning the rent sharing, the capital share in value added appears to i) increase with rent size, decrease with anti-competitive regulation in upstream sectors and increase with the industry specific output gap; ii) decrease with the national output gap, increase with the national employment rate and decrease with employment protection regulation; iii) increase with the interaction of rent size and the unemployment rate and decrease with the interaction of rent size and employment protection regulations. These results confirm the existence of three destinations for rents. They also show that the magnitude of each destination depends on the market power of its beneficiary. All these results are robust to a variety of sensitivity checks

Control of interjoint coordination during the swing phase of normal gait at different speeds

BACKGROUND: It has been suggested that the control of unconstrained movements is simplified via the imposition of a kinetic constraint that produces dynamic torques at each moving joint such that they are a linear function of a single motor command. The linear relationship between dynamic torques at each joint has been demonstrated for multijoint upper limb movements. The purpose of the current study was to test the applicability of such a control scheme to the unconstrained portion of the gait cycle – the swing phase. METHODS: Twenty-eight neurologically normal individuals walked along a track at three different speeds. Angular displacements and dynamic torques produced at each of the three lower limb joints (hip, knee and ankle) were calculated from segmental position data recorded during each trial. We employed principal component (PC) analysis to determine (1) the similarity of kinematic and kinetic time series at the ankle, knee and hip during the swing phase of gait, and (2) the effect of walking speed on the range of joint displacement and torque. RESULTS: The angular displacements of the three joints were accounted for by two PCs during the swing phase (Variance accounted for – PC1: 75.1 ± 1.4%, PC2: 23.2 ± 1.3%), whereas the dynamic joint torques were described by a single PC (Variance accounted for – PC1: 93.8 ± 0.9%). Increases in walking speed were associated with increases in the range of motion and magnitude of torque at each joint although the ratio describing the relative magnitude of torque at each joint remained constant. CONCLUSION: Our results support the idea that the control of leg swing during gait is simplified in two ways: (1) the pattern of dynamic torque at each lower limb joint is produced by appropriately scaling a single motor command and (2) the magnitude of dynamic torque at all three joints can be specified with knowledge of the magnitude of torque at a single joint. Walking speed could therefore be altered by modifying a single value related to the magnitude of torque at one joint

Optimal Compensation for Temporal Uncertainty in Movement Planning

Motor control requires the generation of a precise temporal sequence of control signals sent to the skeletal musculature. We describe an experiment that, for good performance, requires human subjects to plan movements taking into account uncertainty in their movement duration and the increase in that uncertainty with increasing movement duration. We do this by rewarding movements performed within a specified time window, and penalizing slower movements in some conditions and faster movements in others. Our results indicate that subjects compensated for their natural duration-dependent temporal uncertainty as well as an overall increase in temporal uncertainty that was imposed experimentally. Their compensation for temporal uncertainty, both the natural duration-dependent and imposed overall components, was nearly optimal in the sense of maximizing expected gain in the task. The motor system is able to model its temporal uncertainty and compensate for that uncertainty so as to optimize the consequences of movement

Strategic Technology Investments in Open Economies

We study a general equilibrium model of international trade with heterogeneous firms, where countries can strategically invest in technology. The countries' motive is to improve firms' productivity, leading to a competitive advantage in international trade. We are interested in how trade liberalization affects this governmental incentive to invest in technology. In the closed economy countries invest if consumers have a sufficiently high preference for varieties. In the open economy we analyze the Nash-equilibrium policy and the cooperative policy. If there are no cross-country investment spillovers, countries strategically compete in their investment levels and increase their investments with higher trade openness. From a social perspective we have an overinvestment problem. If there are cross-country investment spillovers, we differentiate between weak and strong spillovers. In both cases the cooperative solution predicts a positive relationship between investments and trade openness. If there are weak (strong) spillovers, we find a positive (hump-shaped) relationship between technology investments and trade openness in the Nash-equilibrium. From a social perspective we obtain an over (under)-investment problem if spillovers are weak (strong).Der Artikel untersucht strategische Technologieinvestitionen in einem allgemeinen Gleichgewichtsmodell mit heterogenen Firmen. Länder haben die Möglichkeit, durch Technologieinvestitionen die Produktivität ihrer Firmen zu verbessern und ihnen somit einen Konkurrenzvorteil im internationalen Wettbewerb zu geben. In diesem Modellrahmen betrachten wir den Einfluss von Handelsliberalisierung auf den Anreiz in Technologie zu investieren. In geschlossenen Volkswirtschaften investieren Länder dann, wenn Konsumenten eine ausreichend starke Präferenz für Varietäten aufweisen. In der offenen Volkswirtschaft untersuchen wir das Nash-Gleichgewicht sowie die kooperative Lösung. Ohne Spillover-Effekte durch Technologieinvestitionen auf ein anderes Land, erhöhen Länder ihre Investitionsniveaus strategisch mit zunehmender Handelsoffenheit. Dies führt zu, aus wohlfahrtstheoretischer Perspektive, zu hohen Investitionen. Werden länderübergreifende Spillover-Effekte angenommen, so dass ein Land von den Investitionen eines anderen Landes profitiert, differenzieren wir zwischen einem schwachen und einem starken Spillover. In beiden Szenarien ist in der kooperativen Lösung ein positiver Zusammenhang zwischen Handelsliberalisierung und Investitionen zu beobachten. Im Nash-Gleichgewicht beobachten wir im Fall von einem schwachen (starken) Spillover einen positiven (u-förmigen) Zusammenhang zwischen Technologieinvestitionen und zunehmender Handelsoffenheit. Aus wohlfahrtstheoretischer Perspektive weist dieses Szenario ein zu hohes (zu niedriges) Investitionsvolumen auf