Manual dexterity of older Mexican American adults: a cross-sectional pilot experimental investigation

This paper reports results from an experimental pilot study performed to quantify the manual dexterity of older Mexican American adults. The Purdue pegboard test, a two-arm coordination test, and a hand-tool dexterity test were used in this study. To enable cross-sectional comparisons of manual dexterity measures of older Mexican American adults with young Mexican American adults, these tests were administered to 18 older Mexican American adults aged 63–85 (mean age: 71.3 years, SD: 7.0 years), recruited from senior recreation centers in El Paso, and eighteen young adults aged 21–32 (mean age: 25.6 years, SD: 3.8 years) recruited from the student body at the University of Texas at El Paso. For the Purdue pegboard test, the number of pegs placed in 30 s using the preferred hand, the non-preferred hand, and both hands were first individually monitored. Then, scores on an assembly task using the Purdue pegboard were obtained. For the two-arm coordination test, participants were required to trace a star pattern with a stylus using both hands. The time for task completion and the number of errors made during task performance were monitored. For the hand-tool dexterity test, participants were required to use common hand tools and remove nuts and bolts from one side of a wooden upright, and to assemble nuts and bolts in the corresponding holes on the other side of the upright. The time taken for task completion was recorded. Since modified Levene's test showed equality of variances, two sample t-tests, comparing the mean responses of older adults with the mean responses of young adults for each individual test, were conducted. Results indicate that responses for the older adults were statistically significant different (p<0.001) from young adults for all Purdue pegboard tasks. On the average, older adults performed significantly slower (p<0.001) than young adults on the two-arm coordination test, and committed more errors before task completion (p<0.05). Older adults also took longer to complete the hand-tool dexterity task compared to their younger counterparts (p<0.05). In addition to the t-tests, manual dexterity performance measures from older adults were regressed with age to determine the cross-sectional age effects on manual dexterity measures. Results indicate that all Purdue pegboard performance measures were significantly affected by age (p<0.05). The time to complete the two-arm coordination test was significantly linearly related to age (p<0.05). However, the number of errors committed by older adults in the performance of the two-arm coordination test was not significantly linearly related to age. Time to complete the hand-tool dexterity was also significantly linearly related to age (p<0.05). Accommodating age-related changes in manual dexterity is important for job design in industry, especially in industries employing older adults requiring significant assembly and hand-tool use.

Relevance to industry

Given the aging of the industrial workforce, it is important to understand how manual dexterity is affected by age, so that jobs requiring significant manual dexterity for task initiation, task performance and task completion are designed to fit older adult dexterity levels.     

Interlayer bonding between thermoplastic composites and metals by in-situ polymerization technique

Fiber-metal laminates (FMLs) offer the superior characteristics of polymer composites (i.e., light weight, high strength and stiffness) with the ductility and fracture strength of metals. The bond strength between the two dissimilar materials, composite and metal, dictates the properties and performance of the FMLs. The bonding becomes more critical when the polymer matrix is thermoplastic and hydrophobic in nature. This work employed a novel bonding technique between thermoplastic composites and a metal layer using six different combinations of organic coatings. The flexural, and interlaminar shear strength of the thermoplastic fiber metal laminates (TP-FMLs) were examined to investigate the bond strengths in the different cases along with fracture characteristics revealed from the tested samples using scanning electron microscopy. The viscoelastic performance of the fabricated TP-FMLs were also investigated using the dynamic mechanical thermal analysis method.     

Hartree-Fock-Roothaan wavefunctions for diatomic molecules: III first-row heteronuclear systems,AB, AB±, AB1

Tables of electronic wavefunctions are presented for almost all heteronuclear diatomic systems which arise from combinations of the first-row atoms Li through F. These wavefunctions are obtained for the experimental (or theoretical) internuclear separation and are expansion solutions to the Restricted Hartree-Fock equations with extensive sets of Slater-type functions. The repertory includes the ground states of the systems indicated, several low-lying excited states, and a few positive and negative ions. The results are arranged into sequences for fluorides, AF, oxides, AO, nitrides, AN, etc. The calculations are, in general, restricted to states involving either closed-shell electronic configurations or open-shell configurations with only one incompletely filled open shell. Several of these systems are of doubtful existence, that is, they have not been experimentally characterized, and some should be regarded as arising only from the repulsive interaction of the two atoms involved.     

Quantitative Determination of HD Internal State Distributions via (2+1) REMPI

The relationship between quantum state populations and ion signals in (2+1) resonance-enhanced multiphoton ionization (REMPI) detection of HD is investigated both experimentally, by measurements of hot-nozzle population distributions, and theoretically, by calculations of the two-photon E,F ¹Σ_g⁺—X¹Σ_g⁺ transition moments. The experimental and theoretical relative rotational cross-sections are in good agreement for v″ = 0 and v″ = 1, but differ for v″ = 2 and for the relative vibrational cross-sections. Arguments are presented that saturation of the E,F-X transition is the main cause of these discrepancies. In spite of the presence of saturation, this calibration gives confidence in determining the relative internal state populations of HD from its (2+1) REMPI spectrum.     

Relationship between dishabituation, sensitization, and inhibition of the gill- and siphon-withdrawal reflex in Aplysia californica: Effects of response measure, test time, and training stimulus.

Previous studies have raised questions about the relationships between habituation, dishabituation, sensitization, and inhibition of reflex responses. To explore this issue further, a systematic study of these simple forms of learning was carried out in unrestrained Aplysia in which the amplitude as well as the duration of both the gill- and siphon-withdrawal reflexes were measured after either tailshock or mantle shock. The results suggest that transient reflex inhibition is not an invariant effect of noxious stimulation but depends instead on the response measure, test time, and type of noxious stimulus. Furthermore, the results suggest that dishabituation and sensitization may not involve different processes at the behavioral level; rather the observed differences between them may be due largely to an interaction between habituation and inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A simulation of the enthalpies of fusion of unplasticized poly(vinyl chloride)

Enthalpies of fusion were measured by differential scanning calorimetry for PVC compounds processed within the range 150°–220°C by twin-screw extrusion or compression molding. It was observed that the effects of polymer molar mass (K-value) or sample formulation on values of the experimental enthalpy change follow identical pattern as effects of the same parameter on elastic response established by rheometry. It was assumed that the “amorphous” phase is made up of a matrix of locally ordered chain segments and occluded free-volume and that this matrix constitutes what is described as “secondary crystallinity” of bulk PVC. On the basis of this assumption, a model was developed incorporating a parameter for the contribution of enthalphy of relaxation of free volume to the observed enthalpy of fusion of the secondary crystallinity. Graphical comparison of the simulated enthalpy changes with the measured values produced accurate measures of the critical temperature where a change in melt flow activation energy has been established by rheometry. The comparison further predicts that if PVC was processed below 190°C, an increase in shear intensity should reduce the free-volume content of the product, while processing above 200°C should result in the converse. Also, with increasing processing temperature above 200°C a shear-independent linear decrease in free-volume of the bulk product is suggested to be operative. Thus, the material produced by extrusion or compression molding between 190 and 200°C should be least dense and least crystalline in line with previous observations.     

On the finite element solution of an exterior boundary value problem

This paper compares three methods for dealing with an exterior boundary value problem by the Finite Element Method, one of which involves using an infinite element. The methods are illustrated by application to the problem of ground water flow round a tunnel with permeable invert. The use of a special trial function with a variable parameter in the infinite element gives a particularly efficient method of solution.     

A comparison of self-reported drug use with a urine drug screen in a working population: Correction.

Reports an error in the original article by R. Bharucha-Reid et al (Experimental and Clinical Psychopharmacology, 1995, Vol 3 [3], 280–286). Rachel Kaufmann was inadvertently misspelled. (The following abstract of this article originally appeared in record 1996-92908-001.) This study summarized information on 162 workers who completed urine screen and self-report concerning drug use. It is the first to compare self-report of drug use in the workplace with a urine screen in which individual participant (nonaggregate) data were used. The findings indicate that agreement between the 2 methods of drug detection, although statistically significant, is at best only moderate. The level of agreement was consistent for segments of the sample when divided by sociodemographic characteristics. Although urine screen may be the more reliable and accurate method of detecting prevalence of drug use, self-report must be considered to assess drug use histories and the role of other variables. These 2 methods should be considered as complementary assessment techniques; the appropriate method depends on the conditions and purposes of the drug use study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personal and peers' word associations in relation to children's false recognition errors.

Attempted to show that false recognition errors would be more frequently elicited by children's personal associates to a set of target words than by associates based on peer norms; Ss were 80 White middle-class 2nd and 5th graders (mean ages, 7.6 and 10.6 yrs, respectively). In Session 1 Ss gave oral associations to 34 words. In the 1st phase of Session 2, target words were each read aloud once and Ss were required to memorize them; in the 2nd phase Ss worked for 5 min on a maze task to prevent rehearsal; and in the final phase, a 40-item recognition list was read. Ss determined whether a word was one they had been asked to remember. As predicted, responses occurred with decreasing frequency to target, personal, peer, and control words. Consistent with the expectation that personal associates would more frequently elicit false recognition errors than would peer associates, the difference between personal and control responses was larger than the difference between peer and control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)