Meta-Analytic Methods of Pooling Correlation Matrices for Structural Equation Modeling Under Different Patterns of Missing Data.

Three methods of synthesizing correlations for meta-analytic structural equation modeling (SEM) under different degrees and mechanisms of missingness were compared for the estimation of correlation and SEM parameters and goodness-of-fit indices by using Monte Carlo simulation techniques. A revised generalized least squares (GLS) method for synthesizing correlations, weighted-covariance GLS (W-COV GLS), was compared with univariate weighting with untransformed correlations (univariate r) and univariate weighting with Fisher's z-transformed correlations (univariate z). These 3 methods were crossed with listwise and pairwise deletion. Univariate z and W-COV GLS performed similarly, with W-COV GLS providing slightly better estimation of parameters and more correct model rejection rates. Missing not at random data produced high levels of relative bias in correlation and model parameter estimates and higher incorrect SEM model rejection rates. Pairwise deletion resulted in inflated standard errors for all synthesis methods and higher incorrect rejection rates for the SEM model with univariate weighting procedures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Winifred Starbuck Scott (1906-2003).

Presents the obituary for Winifred Starbuck Scott (1906-2003), who served as American Psychological Association's Division of School Psychology president in 1964-1965. Dr. Scott is noted for her work in the area of school psychology and her extensive involvement in numerous divisions within APA. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ferroelectricity in synthetic metals: Reality and hypotheses

Ferroelectricity is one of the demanded effects in fundamental and applied solid state physics. Till now, the ferroelectrics were available mostly in the inorganic world. The breakthrough of 2000s was an unexpected discovery of the ferroelectricity related to the charge ordering in quasi-1D organic conductors (TMTTF)₂X, and in some layered compounds. The achieved understanding of underlying mechanisms allows to speculate on synthesis of a would-be ferroelectric polymer: it must possess a combination of dimerizations of sites and bonds, one of which must be build-in and another spontaneous. The theory of these “combined Peierls states” predicts an existence of solitons (dimerization kinks) with non-integer variable charges—they are the walls separating domains with opposite electric polarization. The physics of these exotic solitons will serve to describe transient processes in ferroelectric polymers, linking optical- and low-frequency properties. The promising example of such an (AB)_x conjugated polymer has already appeared but was not yet tested for ferroelectricity. A wide chemical search is necessary because of a problematic competition of an anti-ferroelectric phase, whose occurrence depends on complicated details of the interchain coupling.     

Neurocognitive function in monozygotic twins discordant for combat exposure: Relationship to posttraumatic stress disorder.

Neuropsychological deficits have been reported among trauma survivors with posttraumatic stress disorder (PTSD). It is often assumed that these cognitive difficulties are toxic consequences of trauma exposure. Alternatively, they may reflect preexisting characteristics that contribute to the likelihood of developing PTSD. To address this possibility, the authors evaluated cognitive performance in monozygotic twin pairs who were discordant for combat exposure. Pairs were grouped according to whether the combat-exposed brother developed PTSD. The combat-unexposed cotwins of combat veterans with PTSD largely displayed the same performance as their brothers, which was significantly lower than that of non-PTSD combat veterans and their brothers. The results support the notion that specific domains of cognitive function may serve as premorbid risk or protective factors in PTSD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Treatment outcomes for adolescent substance abuse at 4- and 7-month assessments.

This randomized clinical trial evaluated individual cognitive-behavioral therapy (CBT), family therapy, combined individual and family therapy, and a group intervention for 114 substance-abusing adolescents. Outcomes were percentage of days marijuana was used and percentage of youths achieving minimal use. Each intervention demonstrated some efficacy, although differences occurred for outcome measured, speed of change, and maintenance of change. From pretreatment to 4 months, significantly fewer days of use were found for the family therapy alone and the combined interventions. Significantly more youths had achieved minimal use levels in the family and combined conditions and in CBT. From pretreatment to 7 months, reductions in percentage of days of use were significant for the combined and group interventions, and changes in minimal use levels were significant for the family, combined, and group interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bayesian networks for system reliability reassessment

This paper proposes a methodology to apply Bayesian networks to structural system reliability reassessment, with the incorporation of two important features of large structures: (1) multiple failure sequences, and (2) correlations between component-level limit states. The proposed method is validated by analytical comparison with the traditional reliability analysis methods for series and parallel systems. The Bayesian network approach is combined with the branch-and-bound method to improve its efficiency and to facilitate its application to large structures. A framed structure with multiple potential locations of plastic hinges and multiple failure sequences is analyzed to illustrate the proposed method.     

SA-Mediated Regulation and Control of Abiotic Stress Tolerance in Rice

Environmental or abiotic stresses are a common threat that remains a constant and common challenge to all plants. These threats whether singular or in combination can have devastating effects on plants. As a semiaquatic plant, rice succumbs to the same threats. Here we systematically look into the involvement of salicylic acid (SA) in the regulation of abiotic stress in rice. Studies have shown that the level of endogenous salicylic acid (SA) is high in rice compared to any other plant species. The reason behind this elevated level and the contribution of this molecule towards abiotic stress management and other underlying mechanisms remains poorly understood in rice. In this review we will address various abiotic stresses that affect the biochemistry and physiology of rice and the role played by SA in its regulation. Further, this review will elucidate the potential mechanisms that control SA-mediated stress tolerance in rice, leading to future prospects and direction for investigation.     

Distributed control over structured and packet‐dropping networks

In this paper we consider distributed control of n dynamic agents to optimize an overall system performance metric. Due to limited communication resources, there exist structured interconnections among the agents and the interest is placed on synthesizing a suitably distributed control law to provide a given performance level. Based on a Youla–Kucera (Y–K) parameterization approach, the problem of designing a distributed controller to deliver given performance levels for different network topologies is shown to be convex in the Y–K parameter Q. Furthermore, if in addition to structured interconnections, packet drops exist in information transmission among the agents, we provide convex conditions to guarantee mean square (MS) stability and to optimize ℋ︁₂ system performance. The proposed method is also extended to deal with systems of triangular structure. Copyright © 2007 John Wiley & Sons, Ltd.     

Insights in High-Temperature Superconductivity from the Study of Films and Heterostructures Synthesized by Molecular Beam Epitaxy

Using molecular beam epitaxy, we synthesize atomically smooth thin films, multilayers and superlattices of cuprate high-temperature superconductors (HTS). Such heterostructures enable novel experiments that probe the basic physics of HTS. For example, we have established that HTS and antiferromagnetic phases separate on Ångstrom scale, while the pseudo-gap state apparently mixes with HTS over an anomalously large length scale (“Giant Proximity Effect”). Here, we briefly review our most recent experiments on such films and superlattices. The new results include an unambiguous demonstration of strong coupling of in-plane charge excitations to out-of-plane lattice vibrations and the discovery of interface HTS.     

An Overview of Scaling Laws in Ad Hoc and Cognitive Radio Networks

Currently, wireless communications are changing along the lines of three main thrusts. The first is the introduction of secondary spectrum licensing (SSL). Regulations on the usage of licensed spectra are being loosened, encouraging unused primary spectrum to be licensed, often in an opportunistic manner, to secondary devices. The second is the introduction of cognitive radios. These wireless devices are able to sense and adapt in a “smart” manner to their wireless environment, making them prime candidates to becoming secondary users in SSL initiatives. Finally, as we approach the communication limits of point-to-point channels, and as wireless devices become cheap and ubiquitous, the focus is shifting from single to multiple communication links, or networks. In this paper, we provide an overview of the recently established theoretical limits, in the form of sum-rates, or throughput, of two main types of networks: ad hoc networks, in which the devices are homogeneous, and cognitive networks, in which a mixture of primary and secondary (or cognitive) devices are present. We summarize and provide intuition on how the throughput of a network scales with its number of nodes n, as n → ∞, under different network and node capability assumptions.