BIOMECHANICAL FACTORS FOR THE ETIOLOGY OF NAVICULAR DISEASE IN SPORTS HORSES

INTRODUCTION: Navicular disease is a common syndrome in sports horses such as gallopers, jumpers and western horses (especially quarter horses; Stashak, 1987). This syndrome causes forelimb lameness due to pain of the navicular bone (distal sesamoid of the horse digit), navicular bursitis and deep flexor tendon (DFT) affection. When horses develop navicular disease, they can no longer be used for competitive purposes, although they may still be useful for breeding purposes. Yet navicular disease is hereditary, although the mechanisms are still unclear. Nevertheless, distinct morphological variations exist in the navicular bone which are also hereditary (Ueltschi et al., 1995). Our hypothesis on the transmission of navicular disease is that morphological variability causes differences in joint load and bone stress. The aim of this study was to analyze the biomechanical effects of morphological variations of the navicular bone. METHODS: We examined 87 horses radiographically. X-rays were taken of the lateral aspects of the front toes. In the radiographs, the rotation center (center of curvature) of the coffin joint (phalanx II-phalanx III and navicular bone-phalanx II) was determined. Based on this, we constructed the lever arms of the acting forces, taking into account the diameter of the DFT. The lever arms of the proximal DFT-force and of the force of the joint between phalanx III and the navicular bone were calculated relative to the lever arm of the distal DFT-force. Taking into consideration the joint angles, we calculated the tendon and joint forces, and joint surface stresses (quasi-static inverse-dynamic calculation). RESULTS: The decisive factor for the differences in navicular mechanics is the proximal DFT lever arm. The smaller it is - relative to the distal lever arm - the more pressure will be concentrated at the distal end of the navicular bone. The larger it is, the more the pressure maxima will be shifted to the middle, and the more favorable the pressure distribution will be. Unfavorable navicular mechanics will thus occur when the bone is over-stressed in its distal border region where the distal arteries enter the bone. CONCLUSIONS: The varying morphology of the navicular bone is therefore a further explanation for the multi-factorial genesis of navicular disease. This knowledge appears all the more important because selective breeding can prevent the hereditary transmission of unfavorable navicular morphology. The radiological examination of the navicular bone is therefore, besides the classic exterior examination, a sensible screening measure for breeding (Ueltschi et al. 1995). Further, radiological examination is a sensible complement to purchase or aptitude tests. REFERENCES: Stashak, T. S. (1987). Adams’ Lameness in Horses. Philadelphia: Lea & Febiger. Ueltschi, G., Hornig, I., Stornetta, D. (1995). Beobachtungen zur Genetik der Podotrochlose. In P. F. Knezevic (Ed.), Orthopädie bei Huf- und Klauentieren. Stuttgart: Schattauer

BIOMECHANICS OF HORSE JUMPING

INTRODUCTION: During jumping, a horse’s body changes its direction of angular movement twice and hence has to undergo the necessary accelerations/ decelerations in order to perform the jump. Clayton (1989) describes the terminology of horse jumping. The aim of this study was to calculate the angular acceleration of the horse’s body, the path of the center of gravity, and to provide an explanation of jump failures. METHODS: Videofilms were made during an international tournament. The fence chosen for this analysis was an oxer of 1.6m height and 1.2m distance between the elements (rails). A video camera Sony DXC-9100 (100 fr./s) and video software (Adobe Premiere 4.2) were used. For 33 horses we measured the angle of a reference line (crupper - withers) relative to the environment. The angular data set vs. time was splined (non-linear least squares, taking consideration of the linear segments) and first and second differentiations were performed to calculate the angular velocity and acceleration using Mathematica 3.0. The path of the center of gravity (constructed according to Sprigings and Leach, 1986) during the suspension phase was also analyzed by means of a parabolic function. RESULTS: Related to angular acceleration, 5 phases can be distinguished: phase 1: acceleration in order to lift the body, 1a) initiated by the front limbs and 1b) continued by the rear limbs, with zero acceleration during the short time interval between 1a and 1b. Phase 2: deceleration of body lift and acceleration of negative angular motion of the jump suspension (generated by the rear limbs). Phase 3: zero acceleration during jump suspension. Phase 4: deceleration of jump suspension and acceleration of body descent (front limbs). Phase 5: deceleration of body descent (rear limbs). The mean values of angular accelerations of phases 1-5 (in rad/s2) were: phase 1a: +30, phase 1b: +20, phase 2: -55, phase 3: 0, phase 4: +40, phase 5: -30. For positive acceleration, the ground reaction force vector is situated in front of the center of gravity, in negative acceleration, behind. The angular impulse (considering body mass, radius of gyration, Dangle and Dtime of the suspension phase) amounted to 200-250 Nms. The knocking down of the rails by the front limbs was mainly due to the jump-off position, the angular body lift and the path of the center of gravity. The knocking down of the rails by the hind limbs was due to flexion in the hip joint instead of extension. CONCLUSIONS: Decisive factors for horse jumping are acceleration during body lift (phases 1a and 1b), the take-off position, the path of the center of gravity, and limb movements, especially for high fences and high speeds (for a reduced winning time). The measurement of the mentioned parameters by means of a videotechnique is hence a valuable tool for aptitude tests. REFERENCES: Clayton, H. M. (1989). Terminology for the Description of Equine Jumping Kinematics. J. Eq. Vet. Sci. 9, 341-348. Sprigings, E., Leach, D. (1986). Standardised Technique for Determining the Centre of Gravity of Body and Limb Segments of Horses. Eq. Vet. J. 18, 43-49

Permits vs. Offsets Under Investment Uncertainty

A global crediting mechanism would enable developing countries without binding emissions reduction targets to participate in the international carbon market. Linking the framework on Reducing Emissions from Deforestation and Forest Degradation (REDD) as an offset program to major cap-and-trade programs is a particularly promising approach to increase both climate finance and cost-efficiency. However, the coexistence of permits and offsets also creates a classic case of interaction effects. In this paper, we explore how the availability of multiple compliance instruments affects energy investment incentives. Alternative trading and linkage schemes are compared using a real options model of firm-level investment decisions under stochastic prices and the ability to delay investments. We first isolate the critical design factors that drive private investments in the energy sector. We then identify policy regimes that balance the different concerns in the polarized debate for and against the inclusion of forest carbon offsets

FINGER AND THUMB FORCES DURING BOWLING SHOTS

The purpose of this study was to measure the forces exerted to a bowling ball by thumb and fingers during two different shots. For this task, an instrumented bowling ball was designed and produced, which allowed for force measurement and display of vector diagrams. The highest force is applied by the thumb (up to 120N), followed by middle and the ring finger. The overall moment applied to the ball by thumb and fingers during twisting of the ball reaches 3 Nm

Genetic and environmental influences on eating behavior - a study of twin pairs reared apart or reared together

This study examined the relative influence of genetic versus environmental factors on specific aspects of eating behavior. Adult monozygotic twins (22 pairs and 3 singleton reared apart, 38 pairs and 9 singleton reared together, age 18-76 years, BMI 17-43 kg/m2) completed the Three Factor Eating Questionnaire. Genetic and environmental variance components were determined for the three eating behavior constructs and their subscales using model-fitting univariate and multivariate analyses. Unique environmental factors had a substantial influence on all eating behavior variables (explaining 45-71% of variance), and most strongly influenced external locus for hunger and strategic dieting behavior of restraint (explaining 71% and 69% of variance, respectively). Genetic factors had a statistically significant influence on only 4 variables: restraint, emotional susceptibility to disinhibition, situational susceptibility to disinhibition, and internal locus for hunger (heritabilities were 52%, 55%, 38% and 50%, respectively). Common environmental factors did not statistically significantly influence any variable assessed in this study. In addition, multivariate analyses showed that disinhibition and hunger share a common influence, while restraint appears to be a distinct construct. These findings suggest that the majority of variation in eating behavior variables is associated with unique environmental factors, and highlights the importance of the environment in facilitating specific eating behaviors that may promote excess weight gain.R01 AR046124 - NIAMS NIH HHS; R01 MH065322 - NIMH NIH HHS; T32 HL069772 - NHLBI NIH HHS; R37 DA018673 - NIDA NIH HHS; R01 DK073321 - NIDDK NIH HHS; R01 DA018673 - NIDA NIH HH

Climate change induced transformations of agricultural systems: insights from a global model

Climate change might impact crop yields considerably and anticipated transformations of agricultural systems are needed in the coming decades to sustain affordable food provision. However, decision-making on transformational shifts in agricultural systems is plagued by uncertainties concerning the nature and geography of climate change, its impacts, and adequate responses. Locking agricultural systems into inadequate transformations costly to adjust is a significant risk and this acts as an incentive to delay action. It is crucial to gain insight into how much transformation is required from agricultural systems, how robust such strategies are, and how we can defuse the associated challenge for decision-making. While implementing a definition related to large changes in resource use into a global impact assessment modelling framework, we find transformational adaptations to be required of agricultural systems in most regions by 2050s in order to cope with climate change. However, these transformations widely differ across climate change scenarios: uncertainties in large-scale development of irrigation span in all continents from 2030s on, and affect two-thirds of regions by 2050s. Meanwhile, significant but uncertain reduction of major agricultural areas affects the Northern Hemisphere's temperate latitudes, while increases to non-agricultural zones could be large but uncertain in one-third of regions. To help reducing the associated challenge for decision-making, we propose a methodology exploring which, when, where and why transformations could be required and uncertain, by means of scenario analysis

Оптимізація комплексного лікування гнійно-некротичних інфекцій м’яких тканин

В останні роки спостерігається збільшення числа хворих із генералізованими формами гнійно-некротичних інфекцій м’яких тканин (ГНІМТ), при яких клініку різних форм сепсису реєструють у 65,5–78,4 % випадків, при цьому на частку тяжкого сепсису припадає 2–18 %. На високому рівні зберігається показник смертності при даній патології, складаючи від 19 до 70 %. Незважаючи на безліч запропонованих підходів до лікування, досі залишається спірним питання про терміни й об’єм операційного втручання, дренування та санацію гнійного вогнища при генералізованих формах інфекції