Grain Boundary Responses to Heterogeneous Deformation in Tantalum Polycrystals

The evolution of heterogeneous deformation in a tantalum polycrystal was examined during a three-point bending experiment using electron backscatter pattern mapping. Slip bands formed at strains as low as 1%, and they became more intense with strain. Heterogeneous deformation was evident as intragranular orientation gradients as large as 30° were observed after a strain of about 8%. Nonmonotonic changes in the local average misorientation distribution were observed, implying that dislocation substructure developed in a complex manner. Slip bands were analyzed using plane traces computed from local orientation information. With the assumption of uniaxial stress, Schmid factors for favorable slip systems were identified for each grain and compared with observations, showing evidence for macroscopic activity on both {110} and {112} slip systems. Reconstructed boundary data were used to estimate the geometric potential for slip transfer at grain boundaries. The correlations indicated that when active slip systems were favorably oriented for slip transfer across the boundary, it was often observed in the form of continuous slip bands aligned across the boundary. In boundaries where geometrical alignment and Schmid factors were not favorable for slip transfer, there was a higher likelihood to form ledges (topographic discontinuities) along the grain boundaries. Dislocation pileups at grain boundaries were also correlated with a low potential for slip transfer.     

Development and validation of the Caregiver Empowerment Scale: A resource for working with family caregivers of persons with traumatic brain injury.

Objective: To use multitrait analysis to determine the measurement structure of the Caregiver Empowerment Scale (CES). Participants: An American sample of 87 adult primary family caregivers of persons with traumatic brain injury (TBI). Results: A four-factor structure was identified including factor 1 (Advocacy Self-Efficacy), factor 2 (Community Self-Efficacy), factor 3 (Caregiver Self-Efficacy), and factor 4 (Personal Self-Efficacy). Conclusions: The CES provides clinicians and researchers a means to assess self-perceived coping abilities of family caregivers of persons with TBI. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Diets deficient in rumen undegraded protein did not depress milk production

The objective of this study was to evaluate the National Research Council's recommendations for feeding levels of rumen undegraded protein (RUP) for cows fed a one-group total mixed ration. Sixty Holstein cows were paired by parity (1 to 6) and DIM (23 to 315) and were randomly assigned to one of two treatment sequences. Diets contained alfalfa silage (30% diet DM) and corn silage (26% diet DM), and were isonitrogenous (16% CP) and isocaloric (1.71 Mcal/kg). Soybean meal, protected soybean meal (Soy Best), and urea were used to make ration protein fractions that were predicted to be 35 or 29% RUP. The 35% RUP diet was formulated to provide 98 and 105% of the average requirement for RUP and rumen degraded protein (RDP), respectively. The ration containing 29% RUP provided 79 and 117% of average required RUP and RDP, respectively. All cows were group-fed the high RUP diet during a 2-wk pretreatment period, and then were fed one ration for 4 wk followed by the other for 4 wk according to their assigned treatment sequence. Data were collected in the last wk of each period. Mean milk production, milk fat, and milk protein were 32.6 kg/d, 4.35%, and 3.36%, respectively, with no treatment differences. Treatment response was not affected by degree of predicted RUP deficiency. National Research Council requirements for RUP may be too high for cows fed diets similar in energy to a one-group total mixed ration. Alternatively, estimates of RUP content of feedstuffs may be low.     

Correlation of Structure and Photoelastic Response in Tin Phosphate Glass

Recently an empirical model was established to predict the photoelastic response of a glass based on its composition and the crystalline structure of its constituents. In the present work the model was tested in detail by comparing the local structure assessed by a combination of nuclear magnetic resonance and Mössbauer spectroscopy with the model predictions and the measured photoelastic response. The system investigated was (SnO)_x(P₂O₅)_1−x. It was found that while the original simple model based on data on the pure components predicted the composition of the zero stress-optic glass to within about 15 mol%, inclusion of data on mixed systems, more reflective of the true glass structure, gave substantial improvement of the prediction. This finding further confirms the relation of local bonding structure to the photoelastic response of glass.     

Hair analysis in sled dogs (Canis lupus familiaris) illustrates a linkage of mercury exposure along the Yukon River with human subsistence food systems

The dog has been an important biomedical research model and hair samples from sled dogs could be used as a biomarker of exposure to metals. Hair samples were used as a non-invasive indicator of mercury exposure in sled dogs fed commercial food and traditional village diets. Sled dog populations living in rural New York and Alaska were sampled in 2005 and 2006. Total mercury (THg) content was determined on the entire hair sample in sled dogs from reference sites in North Creek, New York and Salcha Alaska. Both sites fed a commercial feed for high performance dogs and had mean THg levels of 36.6 ng/g for New York sled dogs while Alaskan sled dogs, occasionally supplemented with fish oil showed THg mean of 58.2 ng/g. These THg levels are below levels that are suggested to cause adverse effects and should be considered baseline levels. Yukon River sled dogs had higher THg, ranging from 139 to 15,800 ng/g and showed decreasing mean levels from the delta area to upriver. There were significant differences between THg in the dogs from Russian Mission (10,908.3+/-3028 ng/g), the farthest west village, and Ft. Yukon (1822.4+/-1747 ng/g), the farthest east village. All village dogs along the Yukon had higher THg levels than the THg mean level (657+/-273 ng/g) of hair from ancient dogs of the Seward Peninsula.     

Anomalous factor structure of the WISC—R for diabetic children.

The factor structure of the Wechsler Intelligence Scale for Children—Revised (WISC—R) was analyzed with 95 diabetic children (aged 8–16 yrs), 97 regionally and demographically matched controls, and an age- and race-matched sample from the WISC—R standardization sample (n?=?1,405). Controls exhibited a 3-factor IQ structure, consistent with the standardization sample. Diabetic Ss exhibited a 4-factor structure, with the Perceptual Organization factor splitting in two. Picture Completion (PC) and Picture Arrangement (PA) formed a visual discrimination factor, and Block Design and Object Assembly created a spatial conceptual factor. Among the diabetic Ss, the PC and PA subtests did not act as traditional measures of nonverbal intelligence, and the performance of diabetic Ss on the visual discrimination factor may reflect mild visual atypicalities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)