Are joint torque models limited by an assumption of monoarticularity?

This study determines whether maximal voluntary ankle plantar flexor torque could be more accurately represented using a torque generator that is a function of both knee and ankle kinematics. Iso velocity and isometric ankle plantar flexor torques were measured on a single participant for knee joint angles of 111° to 169° (approximately full extension) using a Contrex M J dynamometer. Maximal voluntary torque was represented by a 19-parameter two-joint function of ankle and knee joint angles and angular velocities with the parameters determined by minimizing a weighted root mean square difference between measured torques and the two-joint function. The weighted root mean square difference between the two-joint function and the measured torques was 10 N-m or 3% of maximum torque. The two-joint function was a more accurate representation of maximal voluntary ankle plantar flexor torques than an existing single-joint function where differences of 19% of maximum torque were found. It is concluded that when the knee is flexed by more than 40°, a two-joint representation is necessary

The effective action for the 4-point functions in abelian open superstring theory

We construct the derivative corrections to the four-point vertices in the abelian open string effective action to all orders in alpha'. The result is based on the structure of the string four-point function. Supersymmnetry of these vertices is guaranteed by the supersymmetry of the F^4 term in the effective action. By this construction we establish the existence of an infinite number of supersymmetry invariants, the number of invariants at order alpha'^n grows linearly with n.Comment: 11 pages, 1 figure, v2: additional remarks in Section 5, added references, v3: additional remarks in Section 4 and minor correction

An isovelocity dynamometer method to determine monoarticular and biarticular muscle parameters

This study aimed to determine whether subject-specific individual muscle models for the ankle plantar flexors could be obtained from single joint isometric and isovelocity maximum torque measurements in combination with a model of plantar flexion. Maximum plantar flexion torque measurements were taken on one subject at six knee angles spanning full flexion to full extension. A planar three-segment (foot, shank and thigh), two muscle (soleus and gastrocnemius) model of plantar flexion was developed. Seven parameters per muscle were determined by minimizing a weighted root mean square difference (wRMSD) between the model output and the experimental torque data. Valid individual muscle models were obtained using experimental data from only two knee angles giving a wRMSD score of 16 N m, with values ranging from 11 to 17 N m for each of the six knee angles. The robustness of the methodology was confirmed through repeating the optimization with perturbed experimental torques (±20%) and segment lengths (±10%) resulting in wRMSD scores of between 13 and 20 N m. Hence, good representations of maximum torque can be achieved from subject-specific individual muscle models determined from single joint maximum torque measurements. The proposed methodology could be applied to muscle-driven models of human movement with the potential to improve their validity

Optimisation of a machine learning algorithm in human locomotion using principal component and discriminant function analyses

Assessment methods in human locomotion often involve the description of normalised graphical profiles and/or the extraction of discrete variables. Whilst useful, these approaches may not represent the full complexity of gait data. Multivariate statistical methods, such as Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA), have been adopted since they have the potential to overcome these data handling issues. The aim of the current study was to develop and optimise a specific machine learning algorithm for processing human locomotion data. Twenty participants ran at a self-selected speed across a 15m runway in barefoot and shod conditions. Ground reaction forces (BW) and kinematics were measured at 1000 Hz and 100 Hz, respectively from which joint angles (°), joint moments (N.m.kg-1) and joint powers (W.kg-1) for the hip, knee and ankle joints were calculated in all three anatomical planes. Using PCA and DFA, power spectra of the kinematic and kinetic variables were used as a training database for the development of a machine learning algorithm. All possible combinations of 10 out of 20 participants were explored to find the iteration of individuals that would optimise the machine learning algorithm. The results showed that the algorithm was able to successfully predict whether a participant ran shod or barefoot in 93.5% of cases. To the authors’ knowledge, this is the first study to optimise the development of a machine learning algorithm

Cleft lip and palate malformations: essential knowledge for the general practitioner

Cleft lip and palate malformations are a common group of congenital abnormalities, and are therefore frequently encountered by the general practitioner, who is often the primary coordinator in the management of these patients. This is especially true in a South African setting, where specialist treatment is not always readily available. An incomplete understanding of the multiple components and complexities of the condition often results in unsatisfactory patient outcomes. This article aims to improve understanding of the condition and demonstrates how a multidisciplinary team approach is essential to successfully manage these patients. The roles of the different team members are described, and include the dentist, orthodontist, paediatrician, geneticist, speech therapist, dietitian, otorhinolaryngologist, as well as plastic and reconstructive and/or maxillofacial surgeon. A flow diagram with the various role players and the timing of their interventions has been designed to simplify the referral pathway. The authors aim to assist the general practitioner with the appropriate referral of patients with cleft lip and palate.Keywords: cleft lip and palate, congenital malformation

Traditional green leafy vegetables as underutilised sources of micronutrients in a rural farming community in south-west Nigeria I: estimation of vitamin C, carotenoids and mineral contents

Objective: To determine the micronutrient composition of fresh and boiled traditional green leafy vegetables (TGLVs).Design: Sixteen TGLVs categorised into cultivated and uncultivated vegetables were analysed for vitamin C (ascorbic acid [AA] and dehydroascorbate [DHAA]), β-carotene, lutein and minerals.Results: Basella alba had the highest AA (72 mg/100 g) content; Vernonia amygdalina (unwashed), had the highest β-carotene and lutein concentrations (14.1 and 29.0 mg/100 g, respectively); Amaranthus hybridus had the highest AA (43 mg/100 g) and β-carotene (9.3 mg/100 g) content, for cultivated sp. Celosia argentea had the highest Fe content; Zn content of all the vegetables was low, 0.4–2.6 mg/100 g. Cooking resulted in significant losses in AA content in all the samples, 19% in B. alba to 100% in Crassocephalum crepidioides. Carotenoid losses were observed in 10 samples and six samples had increased values of β-carotene (12% to 183%) and lutein (64% to double).Conclusion: Traditional green leafy vegetables studied were found to be rich in the micronutrients of interest, especially in carotenoids. Boiling of leafy vegetables, as traditionally done, led to considerable losses of the micronutrients. The micronutrient content of uncultivated leafy vegetables compared well with commonly cultivated species

Traditional green leafy vegetables as underutilised sources of micronutrients in a rural farming community in south-west Nigeria II: consumption pattern and potential contribution to micronutrient requirements

Objective: To determine the consumption pattern of selected households consuming traditional green leafy vegetables (TGLVs) during three seasons and potential contribution to recommended nutrient intakes.Design: Repeated household survey using food frequency questionnaire to obtain consumption pattern of selected TGLVs.Setting and Subjects: Selected households in a small rural farming community: pre-rainy (n = 43), rainy (n = 36) and post-rainy seasons (n = 40).Results: Corchorus olitorius and A. hybridus were the most consumed by > 70% of households across three seasons. A. esculentus and A. viridis were the least consumed TGLVs through all the seasons. Uncultivated and cultivated TGLVs could contribute between 26–> 100% and 18–96%, respectively, of recommended intake for vitamin A for children and women. For young children, both the cultivated and uncultivated TGLVs could contribute more than 50% of their RDA for iron.Conclusion: seasonal availability, and preference for certain species, determine the consumption pattern of the TGLVs studied. Uncultivated and less utilised vegetables have the potential to make significant contributions to the micronutrient requirements of women and children, especially vitamin A and iron if frequently used