Distributional ratings of performance: Further examination of a new rating format.

Examined several aspects of construct validity evidence for a distributional format by comparing it with a Behavioral Observation Scale (BOS) rating form and determining whether raters were sensitive to differences in performance variability. Raters were assigned to 1 of 2 instructional procedures, 1 of 2 form orderings (BOS or distributional rating first), and 1 of 5 conditions of performance variability. Ss rated an instructor's performance after viewing 4 videotaped excerpts of his lectures. Mean ratings were lower using the distributional format relative to the BOS format. The distributional ratings indicated that Ss were sensitive to the different variability conditions. The potential of distributional ratings for providing a richer source of performance information than more traditional ratings is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of triaxial stress on void growth and yield equations of power-hardening porous materials

In engineering applications, especially for ductile fracture of materials, nucleation, growth and coalescence of voids have often been observed. Currently there is an increase in interest for the effects of voids on the behaviour of engineering materials. In this paper, by the method of combining micro- and macro-parameters, the effects of triaxial stress on the rates of void growth and yield equations are presented for porous materials with power-hardening. The relations between triaxial stress and the rates of void growth for different n-values and yield equations with different n-values and void volume fractions are discussed. Following results have been obtained: For a porous material with power-hardening, the yield equation can be approximately expressed by an elliptical equation in equivalent stress and triaxial stress. Both the long half-axis and the short half-axis of the elliptical equation are functions of the void volume fraction for a given hardening exponent. The triaxial stress has a strong effect on the growth rates of voids. For linear hardening materials, the relation between the growth rate of voids and the triaxial stress is linear. For elastic/perfectly plastic materials with a small void volume fraction, the growth rate of voids can be described in relation to the triaxial stress with an exponential function. The results from this paper are compared with theoretical results from other researchers for elastic/perfectly plastic materials. A good agreement is shown.     

Integration of medium-throughput signal processing algorithms on flexible instruction-set architectures

Integrated circuits in telecommunications and consumer electronics are rapidly evolving towards single chip solutions. New IC architectures are emerging, which combine instruction-set processor cores with customised hardware. This paper describes a high-level synthesis system for integration of real-time signal processing systems on such processor cores. The compiler supports a flexible architectural model. It can handle certain types of incompletely specified architectures, and offers capabilities for retargetable compilation and architectural exploration. Results for a realistic application from the domain of audio processing indicate the feasibility and power of the presented approach.     

Forward Dynamics of Open-Loop Multibody Mechanisms Using an Efficient Recursive Algorithm Based on Canonical Momenta

A new method for establishing the equations of motion of multibodymechanisms based on canonical momenta is introduced in this paper.In absence of constraints, the proposed forward dynamicsformulation results in a Hamiltonian set of 2n first order ODEsin the generalized coordinates q and the canonical momenta p.These Hamiltonian equations are derived from a recursiveNewton–Euler formulation. As an example, it is shown how, in thecase of a serial structure with rotational joints, an O(n)formulation is obtained. The amount of arithmetical operations isconsiderably less than acceleration based O(n) formulations.     

Representing CCS programs by finite predicate/transition nets

Summary A construction is given which for CCS programs (in which every choice and recursion starts sequentially) yields a finite and strict predicate/ transition net. Consistency of this construction is proved not only with respect to the standard interleaving semantics but with respect to the distributed operational semantics of Degano, De Nicola, and Montanari which additionally models the concurrency explicitly.The work presented here has been carried out at the Institute for Informatics of the Technical University of Munich while the author was supported by an Ernst-von-Siemens scholarship     

Intrahelical side chain-side chain contacts: the consequences of restricted rotameric states and implications for helix engineering and design

Intrahelical side chain–side chain (sc–sc) interactionsare assumed to play a crucial role in the formation and stabilityof -helices, yet it was found that only 37.2% of all helicalresidues are involved in such close contacts, assuming a specificminimum contact distance. The majority (58.0%) of these weredetected between residues with amino acid sequence spacing i,i + 4. The low frequency of intrahelical sc–sc contactswith sequence separations i, i + 1 and ii, i + 3, each observedwith only about one-third of the i, i + 4 counts, can be directlyand generally attributed to the absence of the g^- conformationin helices for the dihedral angle X₁- However, if it was assumedthat each side chain may maximally make only one sc–sccontact, as most commonly observed, the percentage of contactingpairs increased relative to the maximum possible pairs for agiven sequence spacing by a factor of {small tilde}4, e.g. from20.9 to 81.7% for i, i + 4 contacts. Stereochemical reasonsare also given for the observation that i, i + 3 contacts arecomposed largely of ion or polar pairs, while hydrophobic residuesdominate the i, i + 4 contacts. No significantly increased densityof intrahelical sc–sc contacts with increasing helix lengthwas found. Although there were generally fewer intrahelicalcontacts between buried helical residues when more contactswere made to the tertiary protein environment, the number ofintrahelical contacts did not increase with increasing solventexposure of the helices. Implications for helix design and thepacking of helices are discussed.     

Occupation-differential construct validity of the Job Content Questionnaire (JCQ) psychological job demands scale with physical job demands items: a mixed methods research

The construct validity of the Job Content Questionnaire (JCQ) psychological demands scale in relationship to physical demands has been inconsistent. This study aims to test quantitatively and qualitatively whether the scale validity differs by occupation. Hierarchical clustering analyses of 10 JCQ psychological and physical demands items were conducted in 61 occupations from two datasets: one of non-faculty workers at a university in the United States (6 occupations with 208 total workers) and the other of a Belgian working population (55 occupations with 13,039 total workers). The psychological and physical demands items overlapped in 13 of 61 occupation-stratified clustering analyses. Most of the overlaps occurred in physically-demanding occupations and involved the two psychological demands items, 'work fast' and 'work hard'. Generally, the scale reliability was low in such occupations. Additionally, interviews with eight university workers revealed that workers interpreted the two psychological demands items differently by the nature of their tasks. The scale validity was occupation-differential. PRACTITIONER SUMMARY: The JCQ psychological job demands scale as a job demand measure has been used worldwide in many studies. This study indicates that the wordings of the 'work fast' and 'work hard' items of the scale need to be reworded enough to differentiate mental and physical job demands as intended, 'psychological.'