Institutional research productivity in industrial/organizational psychology.

Updated the report of W. M. Cox and V. Catt (see record 1978-21651-001) by determining the 40 top contributing institutions to the Journal of Applied Psychology, 1976–1982, and assessed the generalizability of productivity rankings based solely on contributions to this journal. A number of industrial and organizational psychologists were asked to indicate all the journals in which psychologists in the field were likely to publish. Five journals suggested by these nominators were used for comparison in the review. A list of the 40 most productive graduate programs based on these 5 journals is included. Results show the inadequacy of Cox and Catt's decision to base productivity ratings solely on contributions to 1 journal. Using 5 journals, 4 programs were catapulted into the top 10 rankings, while 7 programs dropped from top rankings in the Cox study (1970–1975) to below the 65th rank in the present study. Using only the Journal of Applied Psychology contributions, 2 of these programs ranked in the top 10, 1976–1982. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxygen content of the fixative is important in the interpretation of the ultrastructure of ischaemic myocardium

Isolated rat hearts were subjected to 15, 45, or 60 minutes of global ischaemia and then fixed by perfusion at 37°C with glutaraldehyde containing various amounts of oxygen. This either had been bubbled with 100% oxygen (PO₂ 620 mm Hg) or with 100% nitrogen (PO₂ 40 mm Hg) immediately before use, or it had been routinely prepared and stored exposed to atmospheric oxygen (PO₂ 245 mm Hg). The ultrastructure of myocytes and endothelial cells subjected to 15 minutes of ischaemia was not affected by the treatment of the fixative. However, when the tissue subjected to longer periods of ischaemia was fixed with routinely prepared or oxygen-bubbled glutaraldehyde, ultrastructural changes characteristic of reoxygenation damage were uniformly evident in both the microvasculature and myocytes. These qualitatively distinct changes included mitochondrial swelling, cell swelling, endothelial bleb formation, and narrowing of capillary lumina. These abnormalities were not observed in tissue fixed with nitrogen-bubbled glutaraldehyde. These findings indicate that deliberate steps should be taken to reduce or eliminate dissolved oxygen from the fixatives used to study ischaemic tissues. Otherwise artefactual reoxygenation damage in vitro may occur and make valid ultrastructural interpretation difficult or impossible.     

Measurement and statistics: An examination of construct validity.

Uses principles of latent trait theory to derive conditions under which mean differences on an observed variable are indicative of mean differences on an underlying construct, focusing on the logistic curve as a model for describing the relation between the observed variable and construct. In this situation, and with normally distributed scores on the construct, a t test comparing groups on the observed variable produces correct inferences at the construct level only if group variances on the construct are homogeneous or the difficulty level of the test equals the mean ability level of the examinees. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A microbubble-powered bioparticle actuator

We present the results of a device that uses controllable microbubble actuation to manipulate bioparticles. In order to create a useful device for controlling the position of bioparticles, predictable microfluidic actuation is crucial. The goal of this project was to develop fundamental technology that can be used to manipulate single bioparticles (e.g., cells). We use a thermal bubble actuation method to accomplish this goal. Microbubbles have the advantages of relatively simple electronics and fabrication but can be difficult to control. In this paper, we describe two specific accomplishments: the use of micromachined nucleation cavities to precisely localize thermal bubbles and to achieve controllable bubble formation temperatures and bubble dissipation and the demonstration of controllable microbubbles in a new device for particle sorting.     

Demonstration of a semiconductor external cavity laser using a UVwritten grating in a planar silica waveguide

The authors report the first demonstration of a semiconductor external cavity waveguide laser, modulated at 2.5 Gbit/s over 100 km of standard optical fibre using a UV written grating in a planar silica waveguide as the feedback element     

Optimal allocation of assessment time in randomized pretest-posttest designs.

The widely used pretest–posttest design traditionally consists of a pretest and a posttest of equal lengths. However, greater statistical power can usually be achieved by using a posttest that is somewhat longer than the pretest. This article provides a method for calculating the optimal allocation of pretest and posttest assessment units so as to maximize power and presents the accompanying reduction in required sample size for a range of parameter values. When insufficient information is available to estimate the optimal location precisely, the effects of allocating 75% of the assessment units to the posttest are evaluated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optical signal processing using integrated multi-element SOA-MZI switch arrays for packet switching

The use of discrete but interconnected SOA-MZI switches for performing logical and highly functional processing tasks, demonstrating the multi-functional potential of the photonic switching elements is discussed. An all-optical 3R burst-mode receiver consisting of four SOA-MZI switches and operating error-free with 40-Gb/s optical bursts, proving that interconnection of multiple switching units can lead to the realisation of key network node functionalities offering increased intelligence at the physical layer is presented. In order to allow for easier interconnectivity between the SOA-MZI switches and to provide compactness and cost effectiveness to the developed subsystems, the integration of multiple switches into the same platform is proposed. To this end, the implementation of the first integrated quadruple SOA-MZI switch array is reported, increasing the integration density level and reducing packaging and pigtailing costs. Finally, possible applications of integrated multiple switch arrays are discussed, indicating their suitability for producing compact circuits performing common processing tasks in a multi-wavelength environment, as well as their potential to lead to the development of an all-optical high-speed packet switched node by implementing critical packet switching functionalities in a compact and efficient way.     

BMP-2 and BMP-4, but not BMP-6, increase the number of adrenergic cells which develop in quail trunk neural crest cultures

Isolated rat liver mitochondria were incubated under various metabolic conditions to determine their membrane potential (MMP) as measured continuously by a tetraphenylphosphonium (TPP+)-selective electrode. By flow cytometry, a parallel analysis of fluorescence emissions observing single mitochondria stained with the lipophilic cation 5,5',6,6'-tetrachloro-1,1'3,3'-tetraethylbenzimidazolcarbocyanine iodide (JC-1) revealed linear correlation between the median orange fluorescence (FL2) due to J-aggregate formations and MMP values measured by TPP+. No correlation was detected with the green fluorescence (FL1) emission. A significantly higher correlation appeared between the FL2/FL1 ratio and MMP values. Within the same mitochondrial population, cytofluorimetric analysis revealed the presence of various classes of organelles with different MMP, whose distribution was dependent on metabolic condition. The highest functional heterogeneity was found in deenergized mitochondria, while the highest homogeneity was observed during the first phase of the phosphorylative process. Thus, these data suggest that the cytofluorimetric use of JC-1 provides direct experimental evidence for the hypothesis of functional mitochondrial heterogeneity, at least with respect to their membrane potential.     

Approximation algorithms for minimizing segments in radiation therapy

Intensity modulated radiation therapy (IMRT) is one of the most effective modalities for modern cancer treatment. The key to successful IMRT treatment hinges on the delivery of a two-dimensional discrete radiation intensity matrix using a device called a multileaf collimator (MLC). Mathematically, the delivery of an intensity matrix using an MLC can be viewed as the problem of representing a non-negative integral matrix (i.e., the intensity matrix) by a linear combination of certain special non-negative integral matrices called segments, where each such segment corresponds to one of the allowed states of the MLC. The problem of representing the intensity matrix with the minimum number of segments is known to be NP-complete. In this paper, we present two approximation algorithms for this matrix representation problem. To the best of our knowledge, these are the first algorithms to achieve non-trivial performance guarantees for multi-row intensity matrices.