New experimental test of strain-gradient plasticity theory: metal foil sandwich structures in flexure

Experimental tests of strain-gradient plasticity theory rely on studies of the size effect (smaller is stronger) in micromechanical testing. The plastic strain gradient is varied by varying the size of the specimen. This confounds the direct effects of the size and the effects of the strain gradient. We propose experiments on foil sandwich structures in which these parameters are separated. Preliminary results suggest that it is the foil thickness that determines the strength, not the strain gradient.     

含有新算符的代数运算规则学习的有效样例设计

为了探索含有新算符的代数运算规则学习的有效样例设计方式,分别采用“转换标记法”和“解释法”设计“指-对数转换”运算和对数运算的样例,考察了初中三年级学生代数运算规则样例学习的迁移效果。结果显示：(1)采用“转换标记法”设计的样例可以明显提高“指-对数转换”规则样例学习的迁移效果;(2)采用“解释法”设计的运算样例,能够明显促进“对数运算规则”的样例学习迁移效果,并与被试的基础知识有关。     

Illegitimate tasks as assessed by incumbents and supervisors: converging only modestly but predicting strain as assessed by incumbents,supervisors, and partners

ABSTRACT

Illegitimate tasks are tasks that violate norms about what an employee can reasonably be expected to do. Representing a relatively recent stressor concept, illegitimate tasks have been linked to strain, but so far have been assessed only by self-report. The current multisource study investigates to what extent supervisors’ assessments of illegitimate tasks converge with incumbents’ self-reports of illegitimate tasks and predict three kinds of strain, namely psychological strain (incumbent report of exhaustion), behavioural strain (supervisors report of incivility), and family strain (partner report of work-family conflict). Low convergence between assessments was expected due to idiosyncratic appraisals but also to differing perspectives of supervisors and incumbents due to their roles, as described by the newly developed roles-as-perspectives theory proposed in this paper. Data from 166 triads were analysed by structural equation modelling and Relative Weight Analysis. Results showed that convergence between incumbent and supervisor reports of illegitimate tasks was rather low; it was higher when the supervisor had a limited span of control. Illegitimate tasks were associated with all three types of strain for both self- and supervisor reports of illegitimate tasks, indicating that the detrimental effects of illegitimate tasks cannot be explained by common method biases alone and that incumbents and supervisors have overlapping but not identical concepts of illegitimate tasks.     

Redesigning work through idiosyncratic deals

This study links idiosyncratic deals (i-deals) to job design theory. It investigates the impact of individually negotiated job changes on performance, self-efficacy, and psychological strain through their intervening effects on work design. Based on a sample of 187 health care professionals employed by a hospital in Germany, three types of work design-related i-deals were investigated: (1) task, (2) career, and (3) flexibility i-deals. Consistent with hypotheses, the three types of i-deal had differential effects on work characteristics, and each in turn related to different outcomes. Specifically, job autonomy mediated the task i-deals—job performance relationship; skill acquisition mediated the career i-deals—occupational self-efficacy relationship; and reduced work overload mediated the flexibility i-deals—emotional and affective irritation relationships. Leader–Member Exchange was confirmed as an antecedent of all three types of i-deals. Task, career, and flexibility i-deals are discussed as ways to make work more intrinsically motivating, ensure one’s professional advancement, and balance workplace stressors.     

Internal stress and defect-related free volume in submicrocrystalline Ni studied by neutron diffraction and difference dilatometry

A combined study of neutron diffraction and difference dilatometry on submicrocrystalline Ni prepared by high pressure torsion aims at studying the anisotropic behaviour during dilatometry and its relation to internal stress and structural anisotropy. Macroscopic stresses were undetectable in the dilatometer samples. Along with specific tests such as post cold-rolling, this shows that an observed anisotropic length change upon annealing is not caused by internal stress, but can be explained by the inherent microstructure, i.e. the anisotropic annealing of relaxed vacancies at grain boundaries of shape-anisotropic crystallites.     

应变率显像评价尿毒症EF正常患者左心室局部功能

为探讨应变率显像(SRI)技术评价尿毒症左心室射血分数(EF)正常患者左心室局部功能的价值,对41例尿毒症EF正常患者及20例健康自愿者左心室心肌纵向SRI曲线进行分析,测量各曲线收缩峰值应变率(SRs)、舒张早期峰值应变率(SRe)、舒张晚期峰值应变率(SRa)并计算SRe/SRa。结果显示,尿毒症组左心室各节段SRs、SRe、SRe/SRa均低于对照组(P0.05)。因此,尿毒症EF正常患者已经存在局部心肌舒缩功能障碍,并且这种障碍可以被SRI技术敏感、定量地评价。     

Behavioral consequences of agonistic experiences in the male S3 (Tryon Maze Dull) rat

Aggression occurring during an initial confrontation between two rats may result in significant behavioral changes in one or both animals. The present experiment was designed to study behavioral changes occurring in the course of an agonistic interaction and the consequences of winning or losing. In order to ensure winning, male CPB-S3 Tryon Maze Dull) rats were confronted with males of a more aggressive strain (Long Evans); and to ensure losing they were confronted with those of a less aggressive strain Wistar). Winners were tested against losers, this test being repeated after an interval of 17 days. Winners and losers were also tested with naive S3 opponents. Possible effects of winning and losing in nonagonistic behavioral tests were then examined. These measured open field activity, passive avoidance learning, and masculine sexual behavior. The results replicate and extend earlier findings using a different strain, indicating that significant and relatively permanent behavioral changes are induced in male winners and losers. Behavioral change is most prominent in the losers. Despite the behavioral differences between winners and losers in tests for agonistic behavior, no consistent differences were noted in any of the other behavioral tests.     

Variable-ratio schedules as variable-interval schedules with linear feedback loops.

The mathematical theory of linear systems has been used successfully to describe responding on variable-interval (VI) schedules. In the simplest extension of the theory to the variable-ratio (VR) case, VR schedules are treated as if they were VI schedules with linear feedback loops. The assumption entailed by this approach, namely, that VR and VI-plus-linear-feedback schedules are equivalent, was tested by comparing responding on the two types of schedule. Four human subjects' lever pressing produced monetary reinforcers on five VR schedules, and on five VI schedules with linear feedback loops that reproduced the feedback properties of the VR schedules. Pressing was initiated by instructions in 2 subjects, and was shaped by successive approximation in the other 2. The different methods of response initiation did not have differential effects on behavior. For each of the 4 subjects, the VR and the comparable VI-plus-linear-feedback schedules generated similar average response rates and similar response patterns. The subjects' behavior on both types of schedule was similar to that of avian and rodent species on VR schedules. These results indicate that the assumption entailed by the VI-plus-linear-feedback approach to the VR case is valid and, consequently, that the approach is worth pursuing. The results also confute interresponse-time theories of schedule performance, which require interval and ratio contingencies to produce different response rates.     

Newly observed microscopic planar defects on {111} in natural diamond

Abstract

Circular disc-crack-like defects randomly distributed on {111} planes have been discovered by 300kV transmission electron microscopy in diamond that had crystallized on non-faceted growth surfaces of mean orientation {100}. In a sample of ～ 100 defects, disc diameters were narrowly distributed about a mean of 1·2 μm and one in seven discs were located on a coplanar stacking fault of average diameter 2 μm. Discs totally enclosed within the specimen exhibit concentric moiré fringes covering their image areas when viewed obliquely, showing them to be dilated into thin lenticles. Internal pressures, deduced from moiré-fringe counts on six lenticles, were in the range 1·5 to 1·8 GPa.     

Fractal growth of graphite nodules in iron

It has been found from a large number of statistical tests that graphite nodules in malleable iron grow with time according to a power law. The growth of the nodules and their fractal dimension have been investigated experimentally as a function of annealing time. Based on the assumption of carbon-diffusion-controlled growth in the initial stage, the growth equation is R _G = K ₁ t ^1/(D-1), where R _G is the radius of the graphite nodules, t the time, D the fractal dimension and K ₁ a constant. Assuming cementite-dissolution-controlled growth in the later stages of growth, the relation is R _G = K ₃ t ^3/D , where K ₃ is a constant. The fractal dimension, or the aggregate state of the graphite nodules, strongly influences the growth process.