Real-time simulation of three-dimensional shoulder girdle and arm dynamics

Electrical stimulation is a promising technology for the restoration of arm function in paralyzed individuals. Control of the paralyzed arm under electrical stimulation, however, is a challenging problem that requires advanced controllers and command interfaces for the user. A real-time model describing the complex dynamics of the arm would allow user-in-the-loop type experiments where the command interface and controller could be assessed. Real-time models of the arm previously described have not included the ability to model the independently controlled scapula and clavicle, limiting their utility for clinical applications of this nature. The goal of this study therefore was to evaluate the performance and mechanical behavior of a real-time, dynamic model of the arm and shoulder girdle. The model comprises seven segments linked by eleven degrees of freedom and actuated by 138 muscle elements. Polynomials were generated to describe the muscle lines of action to reduce computation time, and an implicit, first-order Rosenbrock formulation of the equations of motion was used to increase simulation step-size. The model simulated flexion of the arm faster than real time, simulation time being 92% of actual movement time on standard desktop hardware. Modeled maximum isometric torque values agreed well with values from the literature, showing that the model simulates the moment-generating behavior of a real human arm. The speed of the model enables experiments where the user controls the virtual arm and receives visual feedback in real time. The ability to optimize potential solutions in simulation greatly reduces the burden on the user during development

Causes of early neonatal respiratory distress in the former Venda - a community-based study

Objective: To determine in a rural black population the incidence of common forms of respiratory distress (RD) and low birth weight (LBW), the mortality from RD and the perinatal mortality rate (PMR). Design: A prospective study in a context in which about 90% of the community's births take place within the health service and unwell neonates are transferred to hospital. Setting: The Donald Fraser health ward, Northern Province (then Venda), which serves a population of about 180 000 through 21 clinics and health centres and a 450 bed hospital. Subjects: 7 539 infants born alive between 1 February 1992 and 31 January 1993, of whom 48 developed RD. Outcome measures: Hjalmarson's classification of RD, modified for local conditions. Criteria depended on clinical signs, chest radiography, neutrophil count in blood and gastric aspirate, blood cultures and postmortem examination. Results: RD 6.4/1 000 livebirths (95% Cl 4.6 - 8.2); infection 2.6/1 000 livebirths (95% Cl 1.4 - 3.7); hyaline membrane disease (HMD) 0.9/1 000 livebirths (95% Cl 0.2 - , .6); pulmonary maladaptation (transient tachypnoea) 0.8/1 000 livebirths (95% Cl 0.2 - 1.4); mortality from RD 2.1/1 000 livebirths (95% CILl - 3.2); incidence of LBW 7.9% (95% Cl 7.3 - 8.5); PMR 19.8/1 000 livebirths (95% Cl 17-23). Conclusion: A strikingly Jow incidence of neonatal AD in general and of HMD in particular was found in a rural black population, probably related to a low LBW incidence. Infection was the commonest cause of RD.S Afr Med J 1996; 86; 1413-1<i1

Calculating the random guess scores of multiple-response and matching test items

For achievement tests, the guess score is often used as a baseline for the lowest possible grade for score to grade transformations and setting the cut scores. For test item types such as multiple-response, matching and drag-and-drop, determin-ing the guess score requires more elaborate calculations than the more straight-forward calculation of the guess score for True-False and multiple-choice test item formats. For various variants of multiple-response and matching types with respect to dichotomous and polytomous scoring, methods for determining the guess score are presented and illustrated with practical applications. The implica-tions for theory and practice are discussed

Effect of Fuel Properties on Spray Development from a Multi-Hole DISI Engine Injector

Extensive literature exists on spray development, mixing and combustion regarding engine modeling and diagnostics using single-component and model fuels. However, often the variation in data between different fuels, particularly relating to spray development and its effect on combustion, is neglected or overlooked. By injecting into a quiescent chamber, this work quantifies the differences in spray development from a multi-hole direct-injection spark-ignition engine injector for two single-component fuels (iso-octane and n-pentane), a non-fluorescing multi-component model fuel which may be used for in-cylinder Laser Induced Fluorescence experiments, and several grades of pump gasoline (with and without additives). High-speed recordings of the sprays were made for a range of fuel temperatures and gas pressures. It is shown that a fuel temperature above that of the lowest boiling point fraction of the tested fuel at the given gas pressure causes a convergence of the spray plumes. Increasing the fuel temperature increases this convergence, whilst an associated increased rate of evaporation tends to reduce the penetration of individual plumes. The convergence increases gradually with increasing fuel temperature until all plumes combine to form a single wider plume with a penetration rate greater than that of the individual plumes. When all plumes are converged to form a single plume along a central axis to all the plumes, any further increase in fuel temperature at the given gas pressure acts to increase the rate of evaporation of the fuel. At experiments up to 180 °C fuel temperature and down to 0.3 bar absolute gas pressure, none of the tested fuels were found to spontaneously vaporize; all observed spray formations being a gradual evolution. Increasing the gas pressure at any given fuel temperature, leads to an increase in the boiling temperature of all components of that fuel and, hence, diminishes these effects. Copyright © 2007 SAE International

Effectiveness of manual therapy for chronic tension-type headache: a pragmatic, randomised, clinical trial

To evaluate the effectiveness of manual therapy (MT) in participants with chronic tension-type headache (CTTH)

Mutant mitochondrial elongation factor G1 and combined oxidative phosphorylation deficiency

Although most components of the mitochondrial translation apparatus are encoded by nuclear genes, all known molecular defects associated with impaired mitochondrial translation are due to mutations in mitochondrial DNA. We investigated two siblings with a severe defect in mitochondrial translation, reduced levels of oxidative phosphorylation complexes containing mitochondrial DNA (mtDNA)–encoded subunits, and progressive hepatoencephalopathy. We mapped the defective gene to a region on chromosome 3q containing elongation factor G1 (EFG1), which encodes a mitochondrial translation factor. Sequencing of EFG1 revealed a mutation affecting a conserved residue of the guanosine triphosphate (GTP)–binding domain. These results define a new class of gene defects underlying disorders of oxidative phosphorylation