THE ROLE OF PREVIOUS ANTERIOR CRUCIATE LIGAMENT INJURY ON THE VARIABILITY OF JOINT KINEMATICS AND COORDINATION DURING A MATCH SPECIFIC LAND-CUT TASK

This study compared the movement and coordination variability of the previously injured leg of ACL injured subjects (ACLr, n=9), against their non-injured leg and a control (nACL, n=9) leg. The variability of lower limb joint angles and couplings were calculated during a land-cut task (n=20). The previously injured leg had less variability than the noninjured leg in the knee rotation–knee abd-adduction coupling, and more variability than the nACL leg in frontal and transverse knee joint angles and hip rotation–knee abdadduction coupling. Reduced coordination variability could produce a more repetitive loading pattern linked to cartilage degeneration. Increased movement and coordination variability may stem from proprioceptive deficits on the previously injured leg and decrease the ability to adapt to perturbations

Sampling techniques for adult Afrotropical malaria vectors and their reliability in the estimation of entomological inoculation rate

Various entomological indicators and sampling techniques are used to monitor and evaluate the impact of many vector control interventions. A number of methods have been used in sampling mosquitoes for the purpose of estimating the entomological inoculation rate (EIR) and each is subject to some bias or shortcomings. It was the aim of this paper to critically evaluate the most common mosquito sampling techniques in relation to their reliability in the estimation of EIR. The techniques include man-landing, light trap, light trap/bednet combination and odour-baited traps. Although man-landing technique is the most reliable, it however, expose the catcher to mosquito-borne infections. On the other hand, light traps have been found to capture mosquitoes with higher sporozoite rates as compared to those from human bait catch thus leading to an overestimation of EIR. From an epidemiological point of view, the use of light-trapbed net combination is an approach that is more meaningful than using light trap alone because, a light trap functions more efficiently when placed near the normal flight paths of mosquitoes such as inside huts or under the eaves. Unfortunately, it has been shown that estimates of EIR are influenced by trap position, hence affecting the number caught and the sporozoite rates. A variety of bednets have been used to sample mosquitoes attracted to man. Studies have shown that bednet traps normally catch fewer mosquitoes than do human baits outside them. Although the collections by indoor resting technique give a good estimate of the mean house density in a given area, they may not necessarily give a good estimate of EIR. Thus the development of improved sampling systems based on an improved understanding of hostoriented behaviour is needed. Moreover, there is need to standardise all the sampling techniques in use to enable us make valid comparisons between various studies done by different people and in different areas. In this article, the inherent limitations of conventional mosquito sampling techniques when used in estimating the EIR are discussed. Keywords: malaria vector, sampling, traps, entomological inoculation rate, Africa Tanzania Health Research Bulletin Vol. 7(3) 2005: 117-12

Mechanical energy storage device for hip disarticulation

An artificial leg including a trunk socket, a thigh section hingedly coupled to the trunk socket, a leg section hingedly coupled to the thigh section and a foot section hingedly coupled to the leg section is outlined. A mechanical energy storage device is operatively associated with the artificial leg for storage and release of energy during the normal walking stride of the user. Energy is stored in the mechanical energy storage device during a weight-bearing phase of the walking stride when the user's weight is on the artificial leg. Energy is released during a phase of the normal walking stride, when the user's weight is removed from the artificial leg. The stored energy is released from the energy storage device to pivot the thigh section forwardly about the hinged coupling to the trunk socket

Pulper vertical de 12 m3 de capacitat

El present Projecte Final de Carrera té com a títol “Pulper vertical de 12m3 de capacitat” i el principal objectiu que persegueix és la de dissenyar aquesta màquina i donar la informació suficient per a la seva fabricació, si es donés el cas. Un pulper és una màquina que intervé en la fabricació de paper tant si és a partir de cel·lulosa com a partir d’altre paper reciclat. El pulper és la primera d’una llarga cadena de màquines que es necessiten per a obtenir aquest paper i la seva missió és la de fer una primera barreja entre el paper reciclat i/o la cel·lulosa amb aigua al 4-5% de paper. Aquesta barreja posteriorment es millorarà i s’anirà progressivament premsant i assecant fins arribar al paper pròpiament dit. Un pulper consta d’un recipient, que en el nostre cas tindrà un volum operatiu de 12 m3 i estarà fet de xapa d’acer i d’un ròtor (amb eix vertical) que està format per diversos elements com l’hèlix, l’eix, els rodaments, la carcassa, etc. La transmissió d’aquest pulper serà per corretja i també està englobada i dissenyada en aquest projecte. En aquest projecte s’han perseguit també altres objectius a part del de dissenyar pròpiament el pulper, ja sigui per decisió del projectista com per requeriments de la màquina en si mateixa, per tal de que tingui un funcionament idoni. S’ha intentat simplificar la màquina en tot el possible amb diverses accions com la de treure la lubricació posant rodaments autolubricats per tal de facilitar el muntatge i desmuntatge del pulper per a la seva neteja. També s’ha perseguit el proporcionar una superfície el més llisa possible a l’interior del recipient del pulper per evitar problemes amb l’adherència de fibres de paper als diferents òrgans de la màquina i així, una erosió excessivament ràpida. S’han aïllat les zones que contenen líquid per tal de que no hi apareguin fuites que facin perdre rendiment a la màquina i desgastin els diferents elements del pulper. Com a últim objectiu important també citar que s’ha perseguit acabar amb el disseny de la màquina amb un pressupost assumible i competitiu en la mesura de les possibilitats del projectista

Don't break a leg: Running birds from quail to ostrich prioritise leg safety and economy in uneven terrain

Cursorial ground birds are paragons of bipedal running that span a 500-fold mass range from quail to ostrich. Here we investigate the task-level control priorities of cursorial birds by analysing how they negotiate single-step obstacles that create a conflict between body stability (attenuating deviations in body motion) and consistent leg force–length dynamics (for economy and leg safety). We also test the hypothesis that control priorities shift between body stability and leg safety with increasing body size, reflecting use of active control to overcome size-related challenges. Weight-support demands lead to a shift towards straighter legs and stiffer steady gait with increasing body size, but it remains unknown whether non-steady locomotor priorities diverge with size. We found that all measured species used a consistent obstacle negotiation strategy, involving unsteady body dynamics to minimise fluctuations in leg posture and loading across multiple steps, not directly prioritising body stability. Peak leg forces remained remarkably consistent across obstacle terrain, within 0.35 body weights of level running for obstacle heights from 0.1 to 0.5 times leg length. All species used similar stance leg actuation patterns, involving asymmetric force–length trajectories and posture-dependent actuation to add or remove energy depending on landing conditions. We present a simple stance leg model that explains key features of avian bipedal locomotion, and suggests economy as a key priority on both level and uneven terrain. We suggest that running ground birds target the closely coupled priorities of economy and leg safety as the direct imperatives of control, with adequate stability achieved through appropriately tuned intrinsic dynamics

Don't break a leg: Running birds from quail to ostrich prioritise leg safety and economy in uneven terrain

Cursorial ground birds are paragons of bipedal running that span a 500-fold mass range from quail to ostrich. Here we investigate the task-level control priorities of cursorial birds by analysing how they negotiate single-step obstacles that create a conflict between body stability (attenuating deviations in body motion) and consistent leg force–length dynamics (for economy and leg safety). We also test the hypothesis that control priorities shift between body stability and leg safety with increasing body size, reflecting use of active control to overcome size-related challenges. Weight-support demands lead to a shift towards straighter legs and stiffer steady gait with increasing body size, but it remains unknown whether non-steady locomotor priorities diverge with size. We found that all measured species used a consistent obstacle negotiation strategy, involving unsteady body dynamics to minimise fluctuations in leg posture and loading across multiple steps, not directly prioritising body stability. Peak leg forces remained remarkably consistent across obstacle terrain, within 0.35 body weights of level running for obstacle heights from 0.1 to 0.5 times leg length. All species used similar stance leg actuation patterns, involving asymmetric force–length trajectories and posture-dependent actuation to add or remove energy depending on landing conditions. We present a simple stance leg model that explains key features of avian bipedal locomotion, and suggests economy as a key priority on both level and uneven terrain. We suggest that running ground birds target the closely coupled priorities of economy and leg safety as the direct imperatives of control, with adequate stability achieved through appropriately tuned intrinsic dynamics

Understanding the agility of running birds: Sensorimotor and mechanical factors in avian bipedal locomotion

Birds are a diverse and agile lineage of vertebrates that all use bipedal locomotion for at least part of their life. Thus birds provide a valuable opportunity to investigate how biomechanics and sensorimotor control are integrated for agile bipedal locomotion. This review summarizes recent work using terrain perturbations to reveal neuromechanical control strategies used by ground birds to achieve robust, stable and agile running. Early experiments in running guinea fowl aimed to reveal the immediate intrinsic mechanical response to an unexpected drop ('pothole') in terrain. When navigating the pothole, guinea fowl experience large changes in leg posture in the perturbed step, which correlates strongly with leg loading and perturbation recovery. Analysis of simple theoretical models of running has further confirmed the crucial role of swing-leg trajectory control for regulating foot contact timing and leg loading in uneven terrain. Coupling between body and leg dynamics results in an inherent trade-off in swing leg retraction rate for fall avoidance versus injury avoidance. Fast leg retraction minimizes injury risk, but slow leg retraction minimizes fall risk. Subsequent experiments have investigated how birds optimize their control strategies depending on the type of perturbation (pothole, step, obstacle), visibility of terrain, and with ample practice negotiating terrain features. Birds use several control strategies consistently across terrain contexts: 1) independent control of leg angular cycling and leg length actuation, which facilitates dynamic stability through simple control mechanisms, 2) feedforward regulation of leg cycling rate, which tunes foot-contact timing to maintain consistent leg loading in uneven terrain (minimizing fall and injury risks), 3) load-dependent muscle actuation, which rapidly adjusts stance push-off and stabilizes body mechanical energy, and 4) multi-step recovery strategies that allow body dynamics to transiently vary while tightly regulating leg loading to minimize risks of fall and injury. In future work, it will be interesting to investigate the learning and adaptation processes that allow animals to adjust neuromechanical control mechanisms over short and long timescales

Hubbard ladders in a magnetic field

The behavior of a two leg Hubbard ladder in the presence of a magnetic field is studied by means of Abelian bosonization. We predict the appearance of a new (doping dependent) plateau in the magnetization curve of a doped 2-leg spin ladder in a wide range of couplings. We also discuss the extension to N-leg Hubbard ladders

The walking robot project

A walking robot was designed, analyzed, and tested as an intelligent, mobile, and a terrain adaptive system. The robot's design was an application of existing technologies. The design of the six legs modified and combines well understood mechanisms and was optimized for performance, flexibility, and simplicity. The body design incorporated two tripods for walking stability and ease of turning. The electrical hardware design used modularity and distributed processing to drive the motors. The software design used feedback to coordinate the system and simple keystrokes to give commands. The walking machine can be easily adapted to hostile environments such as high radiation zones and alien terrain. The primary goal of the leg design was to create a leg capable of supporting a robot's body and electrical hardware while walking or performing desired tasks, namely those required for planetary exploration. The leg designers intent was to study the maximum amount of flexibility and maneuverability achievable by the simplest and lightest leg design. The main constraints for the leg design were leg kinematics, ease of assembly, degrees of freedom, number of motors, overall size, and weight