Assessment of Fitts' Law for Quantifying Combined Rotational and Translational Movements

Objective: To develop a model for human performance in combined translational and rotational movements based on Fitts' law. Background: Fitts' law has been successfully applied to translational movements in the past, providing generalization beyond a specific task as well as performance predictions. For movements involving both translations and rotations, no equivalent theory exists, making comparisons of input devices for these movements more ambiguous. Method: The study consisted of three experiments. In the first two, participants performed either pure translational or pure rotational movements of 1 degree of freedom. The third experiment involved the same movements combined. Results: On average, the performance times for combined movements were equal to the sum of the times for equivalent separate rotational and translational movements. A simple Fitts' law equivalent for combined movements with a similar slope as the separate components was proposed. In addition, a significant degree of coordination of the combined movements was found. This had a strong bias toward a parallel execution in 12 out of 13 participants. Conclusion: Combined movements with rotations and translations of 1 degree of freedom can be approximated using a simple Fitts' law equivalent. The rotational and translational components appear to be coordinated by the central nervous system to generate a parallel execution. Application: The results may help drive human interface designs and provide insights into the coordination of combined movements. Future extensions may be possible for the movements of higher degrees of freedom used in robot teleoperation and virtual reality applications.This work was supported by the Institute for Dexterous Space Robotics (Grant No. NNX06AD23G).Publicad

Dietary practices in pyridoxine non-responsive homocystinuria:A European survey

<p>Background: Within Europe, the management of pyridoxine (B-6) non-responsive homocystinuria (HCU) may vary but there is limited knowledge about treatment practice.</p><p>Aim: A comparison of dietetic management practices of patients with B-6 non-responsive HCU in European centres.</p><p>Methods: A cross-sectional audit by questionnaire was completed by 29 inherited metabolic disorder (IMD) centres: (14 UK, 5 Germany, 3 Netherlands, 2 Switzerland, 2 Portugal, 1 France, 1 Norway, 1 Belgium).</p><p>Results: 181 patients (73% >16 years of age) with HCU were identified. The majority (66%; n= 119) were on dietary treatment (1-10 years, 90%; 11-16 years, 82%; and >16 years, 58%) with or without betaine and 34% (n = 62) were on betaine alone. The median natural protein intake (g/day) on diet only was, by age: 1-10 years, 12 g; 11-16 years, 11 g; and > 16 years, 45g. With diet and betaine, median natural protein intake (g/day) by age was: 1-10 years, 13 g; 11-16 years, 20g; and >16 years, 38g. Fifty-two percent (n = 15) of centres allocated natural protein by calculating methionine rather than a protein exchange system. A methionine-free L-amino acid supplement was prescribed for 86% of diet treated patients. Fifty-two percent of centres recommended cystine supplements for low plasma concentrations. Target treatment concentrations for homocystine/homocysteine (free/total) and frequency of biochemical monitoring varied.</p><p>Conclusion: In B-6 non-responsive HCU the prescription of dietary restriction by IMD centres declined with age, potentially associated with poor adherence in older patients. Inconsistencies in biochemical monitoring and treatment indicate the need for international consensus guidelines. (C) 2013 Elsevier Inc. All rights reserved.</p>

How strict is galactose restriction in adults with galactosaemia? International practice

Dietary management of 418 adult patients with galactosaemia (from 39 centres/12 countries) was compared. All centres advised lactose restriction, 6 restricted galactose from galactosides +/- fruits and vegetables and 12 offal. 38% (n=15) relaxed diet by: 1) allowing traces of lactose in manufactured foods (n=13) or 2) giving fruits, vegetables and galactosides (n=2). Only 15% (n=6) calculated dietary galactose. 32% of patients were lost to dietetic follow-up. In adult galactosaemia, there is limited diet relaxation

Practices in prescribing protein substitutes for PKU in Europe: No uniformity of approach

Background: There appears little consensus concerning protein requirements in phenylketonuria (PKU). Methods: A questionnaire completed by 63 European and Turkish IMD centres from 18 countries collected data on prescribed total protein intake (natural/intact protein and phenylalanine-free protein substitute [PS]) by age, administration frequency and method, monitoring, and type of protein substitute. Data were analysed by European region using descriptive statistics. Results: The amount of total protein (from PS and natural/intact protein) varied according to the European region. Higher median amounts of total protein were prescribed in infants and children in Northern Europe (n. =. 24 centres) (infants &lt;. 1. year, >. 2-3. g/kg/day; 1-3. years of age, >. 2-3. g/kg/day; 4-10. years of age, >. 1.5-2.5. g/kg/day) and Southern Europe (n. =. 10 centres) (infants &lt;. 1. year, 2.5. g/kg/day, 1-3. years of age, 2. g/kg/day; 4-10. years of age, 1.5-2. g/kg/day), than by Eastern Europe (n. =. 4 centres) (infants &lt;. 1. year, 2.5. g/kg/day, 1-3. years of age, >. 2-2.5. g/kg/day; 4-10. years of age, >. 1.5-2. g/kg/day) and with Western Europe (n. =. 25 centres) giving the least (infants &lt;. 1. year, >. 2-2.5. g/kg/day, 1-3. years of age, 1.5-2. g/kg/day; 4-10. years of age, 1-1.5. g/kg/day). Total protein prescription was similar in patients aged >. 10. years (1-1.5. g/kg/day) and maternal patients (1-1.5. g/kg/day). Conclusions: The amounts of total protein prescribed varied between European countries and appeared to be influenced by geographical region. In PKU, all gave higher than the recommended 2007 WHO/FAO/UNU safe levels of protein intake for the general population