The impact of muscular dystrophy on limb bone growth and scaling in mice

Muscular loading affects bone growth and the factors determining size and shape. However, it is not known what epigenetic impact muscular dystrophy (dystrophia muscularis) has on limb bone growth or ontogenetic scaling. To assess the effects of two types of muscular dystrophy (genotypes dy/dy and dy2J/dy2J) on limb bone growth, we measured lengths and widths of the right humerus, femur and tibia, and lengths of the ulna and radius from dorsal/ventral radiographs of mice taken over a period of 270 days. Radiographs were taken approximately 3 times a week, and the sampling frequency was gradually reduced to once a month. We plotted measurements from each individual against time and fit a Gompertz equation to the growth of each bone. Parameters of the equation were compared using ANOVA across genotypes and between sexes. Slopes of length versus width were calculated for the limb bones of each individual using linear regression. Slope differences among genotypes and between sexes were tested using ANOVA. Control and dy2J values were significantly longer than those of dy mice in all bones, but there was considerable variation across genotypes for the various width measurements. Sexual dimorphism was found in several measurements, where males were always larger than females. There were few significant differences in limb scaling (lengths vs. widths) among genotypes and almost no scaling differences between sexes despite the size differences. Differences among widths suggest that muscular dystrophy affects different parts of limb bones in different ways. This may be the effect of the type and number of muscular attachments, as well as the usage of the limb. The sexually dimorphic measurements suggest that there are size differences in the skeleton between sexes, regardless of the genotype. Our ontogenetic allometry results indicate that size is affected by the muscular dystrophic condition and by sexual dimorphism, while shape remains largely unchanged.     

Inferring the characteristics of other people: Categories and attribute accessibility.

Investigated how the social inference process operates once a perceiver has activated a particular social category. Three models were tested in an RT paradigm. These models make differing predictions about how the degree of category–attribute association affects the speed and confidence with which an inference is made. In Phase 1, 37 undergraduates assessed the degree of association between a series of life-style attributes and 2 occupational prototypes. In Phase 2, 12 Ss made yes–no judgments about whether these attributes were true of a prototypical category member, and their response latencies and confidence levels were recorded. The "differential accessibility plus contradictions" model was strongly supported. This model states that perceivers make affirming inferences more quickly and confidently about highly associated attributes. When perceivers infer that an attribute is not true of a typical category member, low-associate characteristics can be rejected more quickly and confidently. Inter-S agreement was greater for highly associated attributes. Implications for social perception are discussed. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retardation of jump-up escape responding in rats pretreated with different frequencies of noncontingent electric shock.

Pretreated 5 groups of 5 male albino Sprague-Dawley rats each with either 0, 10, 40, 80, or 160 5-sec, 1.5-ma pulsed shocks. Ss were then given escape training in a jump-up box. The number of failures to escape was an increasing function of pretreatment shock frequency. Ss that showed the retardation effect escaped irregularly with short latencies on some trials and failures to escape on others. After escape training, Ss in the 0-shock pretreatment group were given 80 5-sec, 1.5-ma pulsed shocks and then exposed to additional escape training in the jump-up box. These Ss did not show the retardation effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

TORUS: A step towards bridging the gap between data bases and the casual user

This paper describes TORUS, a natural language understanding system that serves as a front end to a data base management system in order to facilitate communication with casual users. The system employs a semantic network to store knowledge about a data base of student files. This knowledge is used to find the meaning of each input statement, to decide what action to take with respect to the data base, and to select information that must be output in response to the input statement. A prototype version of TORUS has been implemented.     

Behavioral control of exercise in sedentary adults: Studies 1 through 6.

Conducted 6 experiments with 143 healthy sedentary adults who had been unsuccessful in starting or maintaining an exercise regimen to identify behavioral and cognitive procedures that would enhance Ss' adherence to a 3 day/wk exercise (walking/jogging) program. Procedures evaluated included feedback and praise during exercise, various goal-setting strategies, lottery reinforcement, cognitive strategies during the exercise, and relapse-prevention training. Class attendance, exercise program adherence, and fitness data were collected, and self-reported 3-mo follow-up data were also obtained. Results suggest the importance of social support, feedback, and praise during exercise; flexibility in exercise-goal setting; and distraction-based cognitive strategies. Findings are integrated and discussed in terms of the importance and difficulties of shaping and maintaining exercise behaviors. (58 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the detection of structures in noisy pictures

Hough proposed an algorithm for detecting lines in pictures. His algorithm, based on a slope-intercept parameterization of lines, was improved by Duda and Hart through the use of angle-radius parameterization. When pictures contain random noise that cannot be removed, the Duda-Hart procedure can yield unsatisfactory results. This paper presents two modifications of that procedure which compensate for noise. One method is applicable when the distribution of the noise is known and the other can be used when it is not. The proposed modification is also illustrated for circle detection.     

The influence of molecular weight on the large deformation behavior of SBS triblock copolymer elastomers

Engineering stress–strain properties were determined for two polystyrene–polybutadiene–polystyrene (SBS) triblock copolymer elastomers, one consisting of blocks of molecular weight 7000/43000/7000 and the other, 16000/85000/17000. In addition, various blends of these two materials were prepared in order to vary the number-average molecular weight of the blocks in a systematic way while maintaining polystyrene content in the range of 25–28 wt %. Samples were solvent cast from benzene or benzene/heptane mixtures and annealed before testing. Ring specimens were extended to rupture at varying strain rates on an Instron tensile tester. Results indicate that number-average molecular weight has a marked influence on stress–strain behavior over the range of molecular weights and testing conditions employed. The observed behavior is consistent with a systematic increase in the proportion of a mixed interfacial region between the pure polystyrene and polybutadiene domain as molecular weight decreases. The interfacial region contributes to mechanical hystersis, rate sensitivity, and toughness in the SBS materials. Scanning electron photomicrographs of fracture surfaces also showed systematic changes with molecular weight.     

PtSiO2: II. Characterization of the gel and the platinum particles by X-Ray diffraction

Modern techniques for analysis of X-ray diffraction profiles have been applied to several of the platinum-silica gel catalysts described in Part I to determine average platinum crystallite size, percentage exposed, crystallite shape, size distribution, lattice parameter, residual stresses and strains, presence or absence of faulting, and mean-square amplitude of vibration. In addition the surface area of the gel was determined with small-angle scattering (SAS). There is good agreement between the percentage exposed of platinum measured by gas adsorption in Part I and the results reported here, calculated from crystallite sizes, indicating the crystallite size is the true platinum particle size. Crystallites to sizes as small as ≈25 Å have been examined. Furthermore, the crystallites are equiaxed in shape (and definitely not cuboidal) and are strain and defect free, except in the case where the average size is near the pore size of the gel. Size distributions are sharper when the catalyst preparation is by impregnation rather than by ion exchange. The size distributions indicate that there is coalescence of some surface species during preparation rather than coarsening (Ostwald ripening). The meansquare amplitude of vibration of platinum increases by ≈30% as the particles decrease in size from ≈100 to ≈25 Å. There is no change in the lattice parameter greater than ≈0.1%. The gel surface areas determined by SAS are in agreement with those determined in Part I by physisorbtion of nitrogen.