Effect of accuracy constraint on joint coordination during pointing movements.

The purpose of this study was to examine the relative influence of initial hand location on the direction and extent of planar reaching movements. Subjects performed a horizontal-plane reaching task with the dominant arm supported above a table top by a frictionless air-jet system. A start circle and a target were reflected from a horizontal projection screen onto a horizontally positioned mirror, which blocked the subject's view of the arm. A cursor, representing either actual or virtual finger location, was only displayed between each trial to allow subjects to position the cursor in the start circle. Prior to occasional "probe trials," we changed the start location of the finger relative to the cursor. Subjects reported being unaware of the discrepancy between cursor and finger. Our results indicate that regardless of initial hand location, subjects did not alter the direction of movement. However, movement distance was systematically adjusted in accord with the baseline target position. Thus when the hand start position was perpendicularly displaced relative to the target direction, neither the direction nor the extent of movement varied relative to that of baseline. However, when the hand was displaced along the target direction, either anterior or posterior, movements were made in the same direction as baseline trials but were shortened or lengthened, respectively. This effect was asymmetrical such that movements from anterior displaced positions showed greater distance adjustment than those from posterior displaced positions. Inverse dynamic analysis revealed substantial changes in elbow and shoulder muscle torque strategies for both right/left and anterior/posterior pairs of displacements. In the case of right/left displacements, such changes in muscle torque compensated changes in limb configuration such that movements were made in the same direction and to the same extent as baseline trials. Our results support the hypothesis that movement direction is specified relative to an origin at the current location of the hand. Movement extent, on the other hand, appears to be affected by the workspace learned during baseline movement experience.

Research on target acquisition has focused on two features of the task environment – the distance moved and the size of the target in the direction of movement. The present research examined the effect of the size of the target in the direction orthogonal to the direction of movement (typically called the target height) on the time to move to a target. The experiment varied the Index of Difficulty (ID) (by varying the distance moved and the target width) and the target height in a task in which participants moved a cursor from a starting point to the target. The results found that (1) movement time was linearly related to ID at each of three levels of target height, (2) movement time increased as target height decreased, and (3) the slope of the function relating movement time to ID decreased as target height decreased. The discussion addresses two possible explanations for the results, how Fitts’ Law might be modified to take target height into account, and how the results could be applied to user interface design.

Synergic control of the minimum toe clearance in young and older adults during foot swing on treadmill walking in different speeds

There are several key performance objectives of molten carbonate fuel cell systems operating under load perturbations. Among these include: regulation of stack temperature, regulation of differential pressure between anode and cathode, maintaining acceptable fuel utilization and steam-carbon ratio, and electrical load tracking. Utilities are interested in rapid load cycling of carbonate fuel cell systems while the military is interested in the response of carbonate fuel cell systems under sudden application and removal of electrical load. An integrated fuel cell system may endure these types of disturbances while satisfying performance goals, depending largely on the control system. In this paper, the authors examine two important performance variables: fuel utilization and steam-carbon ratio, under both ramping operation and sudden increase in load. Setpoint control laws are proposed for determining the proper steam and natural gas flows corresponding to steady state or transient conditions. In the case of a sudden load increase, they illustrate a trade-off between good load tracking and good utilization/steam-carbon ratio when considering rate constraints on valves.

In the paper, flexible tread element squeeze film analysis is applied to the design of individual tread elements for optimum thin film wet traction. In particular, the effects of tread element shape and dimensions, tread element wear, and the elastic modulus of the tread rubber compound on the rate of fluid film penetration are presented and discussed. The changes sugested herein are made solely on the basis of thin film wet traction--their effect on other important performance variables such as tire noise and wear has not been evaluated, which evaluation is an essential aspect of the total tire design process. /GMRL/

Modeling the effects of ecological engineering on ecosystem health of a shallow eutrophic Chinese lake (Lake Chao)

The use of flexible arm muscle synergies to perform an isometric stabilization task

In 3 experiments, Ss controlled a horizontal lever to track a step input where the degrees of choice of direction and extent of movement were varied systematically. The experiments differed in the way the trials were presented and in the conditions under which these 2 sources of response choice were compared. Increasing choice of direction of movement from 1 to 2 led to an increase in RT of between 34 and 40 msec. No significant increase in RT was found as choice of extent of movement was raised from 1 to 4. Considered with other evidence the results indicate the necessity to distinguish 2 types or levels of decisions associated with response factors. It is suggested that at one level the sequencing of muscle activity is established and at another the fine details of this activity are controlled.

Sensitivity of CERES-Maize simulated yields to uncertainty in soil properties and daily solar radiation

Gaps between distributions of closely related species have been noted in the literature but little empirical research exists to explain these patterns. One hypothesis is poor habitat quality occurs within the gaps and therefore prevents species from inhabiting these areas. Multiple examples of gaps between species distributions can be found among different species of pocket gophers. The objective of this research was to analyze a zone of separation between Geomys bursarius and Cratogeomys castanops in southwest Kansas. Habitat suitability maps were produced using Maxent (3.3.2) for each species throughout the study area. Values of habitat suitability and important habitat variables were compared between locations within the zone of separation and presence localities. The most important variable for predicting habitat suitability for G. bursarius was percent sand, while both percent sand and clay were important for C. castanops. Habitats within the zone of separation were significantly less suitab...

The novel biomarker-based ABC (age, biomarkers, clinical history)-bleeding risk score for patients with atrial fibrillation: a derivation and validation study

Using an angular measurement which takes into account direction, speed and extent of movement, the postural sway of 78 girls was studied both in a suggestion and in a non-suggestion situation. Although the scores obtained under the 2 conditions differed significantly, the 2 distributions showed the same direction of skewness and both had a single mode at zero. Correlations found were: between the suggestion and non-suggestion scores, .24 ( P = .05 to .02); between suggestion scores and frequency of reported dreaming, .34 ( P less than .01); and between suggestion scores and order of presentation for the experiment, .45 ( P less than .01). (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Radar is a very powerful tool in determining the position, speed and direction of movement, horizontal and vertical extent of the cyclone. Besides, the radar observations can also be expected to provide more vital information on the shape, size and behaviour of the eye of a cyclone. These features are very important input information for cyclone forecasting, especially in assessing the intensity of the cyclone. An effort has been made here to document the above features of a cyclone that struck the east Godavari coast in November 1996.
 
 The cyclone formed over central Bay of Bengal in the afternoon of 5 November 1996 and intensified into a severe cyclonic storm with a core of hurricane winds next day. The cyclone was tracked by Cyclone Detection Radar (CDR) Visakhapatnam from the initial stage of its formation till it crossed the coast near Kakinada. In this paper, the radar track of the cyclone over sea, along with the size. shape and behaviour of the eye as observed on radar have been discussed. The variation of other parameters like eyewall width, radius of maximum reflectivity and wall cloud height and relationship between eyewall width and eye diameter have also been discussed.

Purpose. Behavioural and psychological disorders after traumatic brain injury (TBI) are very common. The purposes of this study were to estimate the frequency of these problems in our sample, to evaluate the effectiveness of cognitive behavioural therapy (CBT) and to assess the predictive value of important clinical variables for the treatment outcome.Method. Forty patients aged 4–18 years were included in this study. Twenty-eight patients received CBT at our Institute (clinical group), while 12 patients did not receive any treatment at all (control group). The CBCL/4-18 and the VABS were administered to parents at the beginning of the study and after 12 months.Results. A high frequency of psychological and behavioural problems was found in both groups of patients. After CBT, the clinical group showed a significant advantage on several CBCL scales and a greater increase in adaptive behaviour on the VABS Socialisation domain. The Glasgow Coma Scale score, days of unconsciousness and age at injury were not predictors of the severity of psychological problems at the follow-up for the patients of the clinical group.Conclusions. Our results suggest that CBT is an effective intervention for young patients with psychological problems after TBI.

In the previous chapter, we used logistic regression to model binary variables and proportions. In this chapter, we will use another type of generalized linear model, Poisson regression, to model counts. Many medical and epidemiological investigations are concerned with the incidence of diseases in populations. Here, a number of people are followed up and the onset of a disease recorded for each person. The data can then be summarized by counting the total number of occurrences of the disease in different subgroups of subjects sharing the same values of the important explanatory variables. The dependent variable is therefore a count.KeywordsPoisson RegressionDispersion ParameterIncidence Rate RatioDeviance ResidualExpected CountThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.