Development of a standard fall data format for signals from body-worn sensors : the FARSEEING consensus.

Objective measurement of real-world fall events by using body-worn sensor devices can improve the understanding of falls in older people and enable new technology to prevent, predict, and automatically recognize falls. However, these events are rare and hence challenging to capture. The FARSEEING (FAll Repository for the design of Smart and sElf-adapaive Environments prolonging INdependent livinG) consortium and associated partners strongly argue that a sufficient dataset of real-world falls can only be acquired through a collaboration of many research groups. Therefore, the major aim of the FARSEEING project is to build a meta-database of real-world falls. To establish this meta-database, standardization of data is necessary to make it possible to combine different sources for analysis and to guarantee data quality. A consensus process was started in January 2012 to propose a standard fall data format, involving 40 experts from different countries and different disciplines working in the field of fall recording and fall prevention. During a web-based Delphi process, possible variables to describe participants, falls, and fall signals were collected and rated by the experts. The summarized results were presented and finally discussed during a workshop at the 20th Conference of the International Society of Posture and Gait Research 2012, in Trondheim, Norway. The consensus includes recommendations for a fall definition, fall reporting (including fall reporting frequency, and fall reporting variables), a minimum clinical dataset, a sensor configuration, and variables to describe the signal characteristics.

The effect of walking poles on the knee adduction moment in patients with varus gonarthrosis.

OBJECTIVES: (1) Test the hypothesis that walking poles decrease the external knee adduction moment during gait in patients with varus gonarthrosis, and (2) explore potential mechanisms. DESIGN: Thirty-four patients with medial compartment knee osteoarthritis (OA) and varus alignment underwent three dimensional (3D) gait analysis with and without using walking poles. Conditions were randomized and walking speed was maintained ±5% of the self-selected speed of the initial condition. The pole held in the hand of the unaffected side was instrumented with a compression load cell. RESULTS: Student's t tests for paired samples indicated small but statistically significant increases (P < 0.001) in knee adduction moment (calculated from inverse dynamics) for its first peak, second peak and angular impulse when using the poles; mean increases (95% confidence interval - CI) were 0.17%BW*Ht (0.08, 0.27), 0.17%BW*Ht (0.04, 0.30) and 0.15%BW*Ht*s (0.09, 0.22), respectively. There was a decrease (P = 0.015) in vertical ground reaction force (-0.02 BW (-0.04, -0.01)), yet increase (P < 0.001) in its frontal plane lever arm about the knee (0.30 cm (0.15, 0.44)), at the time of the first peak knee adduction moment. Pole force in the vertical direction was inversely related (r = -0.34, P = 0.05) to the increase in first peak adduction moment. CONCLUSION: Although results are variable among patients, and may be related to individual technique, these overall findings suggest that walking poles do not decrease knee adduction moments, and therefore likely do not decrease medial compartment loads, in patients with varus gonarthrosis. Decreases in knee joint loading should not be used as rationale for walking pole use in these patients.

Cognitive demands of executing postural reactions: does aging impede attention switching?

A new dual-task paradigm was used to investigate age-related differences in attentional dynamics during rapid balancing reactions evoked by small, unpredictable antero-posterior platform movements. The perturbations were delivered while subjects performed a continuous visuo-motor pursuit-tracking task. Onset of significant deviation in tracking was inferred to indicate switching of attentional resources between tracking and balancing tasks. Although tracking deviation was equally likely to occur subsequent to postural perturbation in healthy young and older adults, deviation onset was delayed, on average, by 67% (123 ms) in the older subjects. Delay in onset of tracking deviation correlated with subsequent delay in generating the peak stabilizing postural response at the ankle. These results suggest that impaired attentional dynamics may exacerbate postural instability in older adults.

An evaluation of the ergonomics of three computer keyboards.

The influence of keyboard design on hand position, typing productivity and keyboard preference was evaluated by comparing two segmented alternative designs with the linear standard keyboard. The FIXED alternative keyboard featured a split angle of 12 degrees and a moderate lateral inclination angle of 10 degrees. The adjustable OPEN alternative keyboard was used with a 15 degrees split setting, which resulted in a marked 42 degrees of demiboard lateral inclination. Sixteen typists, who completed 10 h of training on both alternative keyboards, were videotaped while typing set texts on all three keyboards. Forearm and wrist angles based on three-dimensional video analyses were significantly different (p<0.05) among the three designs tested. Both alternative keyboards placed the forearm and wrist closer to neutral positions than did the standard keyboard. While the OPEN keyboard reduced pronation, it simultaneously increased radial deviation. The FIXED keyboard kept the forearm in moderate pronation and the wrist closer to neutral. More time was spent in neutral and moderate ranges of wrist motion when subjects typed on the FIXED compared with the other two designs. With respect to the standard keyboard, typing productivity was reduced by 10% on the FIXED and 20% on the OPEN designs. No significant difference in preference was found between the standard and FIXED keyboards, both of which were preferred over the OPEN. It was concluded that, of the three keyboards evaluated, the FIXED design incorporated moderate changes to the standard keyboard. These changes promoted a more natural hand position while typing thereby reducing the potential for cumulative trauma disorders of the wrist. In addition, the FIXED design preserved a reasonable level of productivity and was well accepted by users.

Determination of high-spin iron(III)-nitroxyl distances in spin-labeled porphyrins by time-domain EPR.

Continuous wave EPR spectra of the nitroxyl signals for four spin-labeled high-spin (h.s.) Fe(III) porphyrins showed partially resolved splittings at temperatures near 4 K. Axial ligands were fluoride, chloride, or bromide. As temperature was increased to 20 to 30 K the iron-nitroxyl splitting collapsed due to increasing rates of iron relaxation. Electron spin-echo (ESE) spectroscopy showed that above about 6 K collapse of the iron-nitroxyl spin-spin splitting caused a dramatic increase in the nitroxyl phase memory relaxation rates. Electron spin relaxation rates were determined for Fe(tetratolylporphyrin)X, X = F, Cl, Br, in toluene solution by ESE or inversion recovery at 4.5 to 6 K and by analysis of the temperature-dependent contributions to the continuous wave EPR linewidths between about 10 and 120 K. Above about 10 K iron relaxation rates increase in the order X = F < Cl < Br, which is the order of increasing zero-field splitting. Saturation recovery data for two spin-labeled h.s. iron(III) porphyrins between about 15 and 120 K and for two additional spin-labeled h.s. iron(III) porphyrins between about 85 and 120 K demonstrated that interaction with the h. s. iron enhanced the electron spin relaxation rate of the spin label. The saturation recovery curves for the nitroxyl were analyzed to determine interspin distances using a modified version of the Bloembergen equation and independently determined iron relaxation rates. Interspin distances were between 11.6 and 15.0 A, were independent of axial ligand, and were in good agreement with values obtained previously for low-spin Fe(III) and Cu(II) analogs.