The biomechanical importance of the scaphoid-centrale fusion during simulated knuckle-walking and its implications for human locomotor evolution.

Inferring the locomotor behaviour of the last common ancestor (LCA) of humans and African apes is still a divisive issue. An African great-ape-like ancestor using knuckle-walking is still the most parsimonious hypothesis for the LCA, despite diverse conflicting lines of evidence. Crucial to this hypothesis is the role of the centrale in the hominoid wrist, since the fusion of this bone with the scaphoid is among the clearest morphological synapomorphies of African apes and hominins. However, the exact functional significance of this fusion remains unclear. We address this question by carrying out finite element simulations of the hominoid wrist during knuckle-walking by virtually generating fused and unfused morphologies in a sample of hominoids. Finite element analysis was applied to test the hypothesis that a fused scaphoid-centrale better withstands the loads derived from knuckle-walking. The results show that fused morphologies display lower stress values, hence supporting a biomechanical explanation for the fusion as a functional adaptation for knuckle-walking. This functional interpretation for the fusion contrasts with the current inferred positional behaviour of the earliest hominins, thus suggesting that this morphology was probably retained from an LCA that exhibited knuckle-walking as part of its locomotor repertoire and that was probably later exapted for other functions.

Differences in EMG Burst Patterns During Grasping Dexterity Tests and Activities of Daily Living.

The aim of this study was to characterize the muscle activation patterns which underlie the performance of two commonly used grasping patterns and compare the characteristics of such patterns during dexterity tests and activities of daily living. EMG of flexor digitorum and extensor digitorum were monitored from 6 healthy participants as they performed three tasks related to activities of daily living (picking up a coin, drinking from a cup, feeding with a spoon) and three dexterity tests (Variable Dexterity Test-Precision, Variable Dexterity Test-Cylinder, Purdue Pegboard Test). A ten-camera motion capture system was used to simultaneously acquire kinematics of index and middle fingers. Spatiotemporal aspects of the EMG signals were analyzed and compared to metacarpophalangeal joint angle of index and middle fingers. The work has shown that a common rehabilitation test such as the Purdue Pegboard test is a poor representation of the muscle activation patterns for activities of daily living. EMG and joint angle patterns from the Variable Dexterity Tests which has been designed to more accurately reflect a range of ADl's were consistently comparable with tasks requiring precision and cylinder grip, reaffirming the importance of object size and shape when attempting to accurately assess hand function.

Analyzing finger interdependencies during the Purdue Pegboard Test and comparative activities of daily living.

STUDY DESIGN: Bench and cross-sectional study. INTRODUCTION: Information obtained from dexterity tests is an important component of a comprehensive examination of the hand. PURPOSE OF THE STUDY: To analyze and compare finger interdependencies during the performance of the Purdue Pegboard Test (PBT) and comparative daily tasks. METHODS: A method based on the optoelectronic kinematic analysis of the precision grip style and on the calculation of cross-correlation coefficients between relevant joint angles, which provided measures of the degree of finger coordination, was conducted on 10 healthy participants performing the PBT and 2 comparative daily living tasks. RESULTS: Daily tasks showed identifiable interdependencies patterns between the metacarpophalangeal joints of the fingers involved in the grip. Tasks related to activities of daily living resulted in significantly higher cross-correlation coefficients across subjects and movements during the formation and manipulation phases of the tasks (0.7-0.9), whereas the release stage produced significantly lower movement correlation values (0.3-0.7). Contrarily, the formation and manipulation stages of the PBT showed low finger correlation across most subjects (0.2-0.6), whereas the release stage resulted in the highest values for all relevant movements (0.65-0.9). DISCUSSION: Interdependencies patterns were consistent for the activities of daily living but differ from the patterns observed from the PBT. CONCLUSIONS: The PBT does not compare well with the whole range of finger movements that account for hand performance during daily tasks. LEVEL OF EVIDENCE: Not applicable.

Food for thought?--A UK pilot study testing a methodology for compositional domestic food waste analysis.

Recent media attention has amply demonstrated the need for changes in our society regarding waste. The cost of waste is rising, European legislation is driving forward waste reduction policies and industry is being made responsible for the waste that all products make. This legislation is also driving a reduction in biodegradable municipal waste. In general there are a number of factors ranging from the media, financial and political to environmental, that are driving forward an agenda to decrease both general waste and food waste going to landfill. A necessary requirement of such an agenda is a benchmark of the current composition and scale of both general waste and food waste. Hence, this can then be used as a measure to demonstrate improvement. A measurement methodology and the benchmark data already exists for general waste. However, there is little or no previous work about the compositional make up of food waste. This paper discusses the necessity for a compositional food waste analysis and the pros and cons of various food waste measurement methodologies. Results for a specific methodology are illustrated and suggestions for a revision of this methodology are proposed.

The use of uncertainty analysis as a food waste estimation tool.

Food waste going to landfill is a significant environmental issue with 33% of all food we buy simply being thrown away. Not only is this extremely wasteful but rotting food produces gases that are harmful to the environment and contributes to global warming. The UK government is committed to reducing the amount of household waste directly being disposed of at landfills by 10.1 million tonnes over 20 years from 2000 (Waste Composition Analysis: Guidance for Local Authorities, Defra, 2004). As part of this the Waste Reduction Action Programme was set up to fund and facilitate innovative solutions to reduce waste to landfill. Part of that process was to assess bids by solution providers with regards the effectiveness of the technologies that they were offering. This was found to be a non-trivial task, with multiple input parameters and large variations in data. Establishing which parameters have the greatest effect on food waste estimation was therefore essential in any decision-making process. However, the large number of unknowns, assumptions and parameters makes this understanding both difficult and time consuming. A branch of mathematics known as uncertainty analysis can be used to analyse these types of situations quickly and effectively and is easily adapted to understanding of food waste estimation. This paper outlines the techniques used to develop an internet-based decision-making tool and demonstrates the methodology used with simple case studies.