Parenting Behaviors and the Occurrence and Co-Occurrence of Depressive Symptoms and Conduct Problems Among African American Children.

The occurrence and co-occurrence of depressive symptoms and conduct problems were examined in the context of parenting behaviors in a community-based sample of 897 African American children and their primary caregivers using a multi-informant, longitudinal design. Parenting behaviors and clinical symptoms were assessed in 2 waves, when the children averaged 10.5 and 12.3 years of age. Parenting behaviors differed significantly according to a child's symptomatology; (a) that is, when a child exhibited no depressive or conduct problems, (b) depressive problems only, (c) conduct problems only, or (d) co-occurring depressive and conduct problems. When parenting behaviors were examined according to changes in children's symptom levels, children whose symptoms increased over time reported increases in hostility and harsh-inconsistent parenting and decreases in warmth and nurturant-involved parenting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

TLM-based modal-extraction approach for the investigation of discontinuities in the rectangular waveguide and the NRD

This paper describes the development of a rigorous transmission-line matrix-based modal-extraction approach to analyze discontinuities in guided-wave structures in general, with particular attention to the nonradiative dielectric waveguide (NRD). The motivation for this paper arose from the need to ascertain the admittance of a slot in the ground plane of an NRD without relying on experimental data. These data enabled one to design an NRD-based slot array following the methodology of Malherbe (1984), Malherbe et al. (1984), and Ghosh et al.(1997). Previous work in this area relied on placing observation points sufficiently remote from the discontinuity in order to ensure the decay of scattered evanescent modes to appreciably low levels. The method discussed here obviates this requirement and allows the evaluation of generalized scattering-matrix coefficients arbitrarily close to the discontinuity, thus significantly reducing the computational overhead. Results pertaining to discontinuities in the NRD and the rectangular waveguide have been presented and shown to give good agreement with those in the literature and with measurements. The perfectly matched layer has been used as an absorbing boundary condition in our simulations. Finally, the results have been verified using the power-conservation and Poynting's theorems.     

It's about timing and change: Pubertal transition effects on symptoms of major depression among African American youths.

Effects of early physical maturation and accelerated pubertal changes on symptoms of major depression were examined in 639 African American children. Three rival hypotheses, early timing, off-time, and stressful change, were tested using 2 waves of data (mean ages = 11 and 13 years). The pubertal effect operates differently according to children's gender and age. For girls, early maturation was consistently associated with elevated levels of depressive symptoms. For boys, early maturers manifested elevated levels of depression only at age 11, but these symptoms subsided by age 13. Boys who experienced accelerated pubertal growth over time displayed elevated symptom levels. Results support the early timing hypothesis for girls and the stressful change hypothesis for boys. Time at assessment is critical when examining boys' pubertal transition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adjusting to changes in the time of reinforcement: Peak interval transitions in rats.

Thirty rats received training on a peak-interval procedure, where a baseline with an 20-s time of reinforcement was interspersed among cyclic transition to other reinforcement time values (10, 20, 30, or 40 s), each of which was either in force for only a single session or for 3 sessions. Peak times were close to the time of reinforcement on the 20-s baseline and tracked the new reinforcement times both closely (but not exactly) and very rapidly. Peak time during transitions was affected by the criterion value in force on the previous session, exhibiting a proactive interference effect. Analysis of individual peak times during a session showed that transitions from lower to higher reinforcement time values were usually characterized by abrupt jumps in peak time, whereas descending transitions were mostly smooth but rapid. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beyond imprisonment of meaning: Technology facilitating redefining

Defining is a natural and necessary response to an ambiguous world, but causes fixation of categories and perspectives. On the basis of two earlier studies of project groups, we came to argue that redefining, and hence constructing various ways in which one perceives and understands something, enables groups to overcome imprisonment in meaning, establishing continuous development and flexibility. In this article, we first build a rationale for facilitating a process of redefining, to be taken into account when designing technology. Departing from this rationale, we discuss features of groupware technology that permit change by being flexible, and evoke redefining by engaging the user more actively. In so doing, we argue to think along new lines in the design of communication and collaboration technology. This paper proposes a specific perspective on technology, facilitating groups to engage in a productive, creative fashion of exploiting meaning potential.     

Imaging large vessels using cosmic-ray muon energy-loss techniques

Imaging the internal structure of large vessels (2–20 m in diameter) is not possible with most traditional imaging methods. The sheer size renders gamma-ray and other high-energy photon, neutron, electrical and acoustic techniques useless, whilst the use of high-energy accelerators required to produce charged-particles of sufficient energy are impractical in most industrial situations. The use of naturally occurring high-energy (GeV) cosmic-ray mu-mesons (muons) provides an effective solution to the penetration problem. The problems of low intensity at near-horizontal angles with the cosmic-ray muon flux are addressed by using energy-loss imaging methods. In other methodologies, using charge-particle energy-loss imaging techniques, only a few events are needed compared to many thousands required if attenuation measurements were to be employed. The energies of horizontal cosmic-ray muons are distributed largely between 0.1 and 1000 GeV with a mean energy of about 50 GeV. Radiation Transport Monte-Carlo methods (GEANT4) have been used to calculate the energy loss for a selection of industrial materials in the energy range of interest. The energy loss of the muons along a ray-sum are modelled and compared to attenuation losses along the ray-sum using energy resolving detectors in coincidence before and after the sample. The energy-loss spectra across different samples are measured, demonstrating that embedded materials can be identified with as few as 10 muons passing through the sample. It is proposed that the imaging modality can be extended into a full tomographic modality allowing material identification within each voxel.     

A new derivation of the agglomerate size distribution for a constant coagulation kernel

The agglomerate size distribution for an assembly of primary particles coagulating with constant kernel K is usually derived from the solution of the relevant deterministic equations. We present an alternative stochastic approach to the problem.     

Light Emission from Highly Reflective Porous Silicon Multilayer Structures

Porous silicon photoluminescence and electroluminescence can be controlled by periodically modulating the material porosity to form high quality multilayer stacks and microcavities. Important issues not yet fully addressed are (a) the precise role played by this microstructuring, given that the luminescence is distributed throughout the entire structure and that the low porosity layers are highly absorbing at short wavelengths, and (b) whether the quality of such microcavities could be sufficient to support lasing. Using both experimental and theoretical techniques, the emission and reflection properties of different porous silicon single and multilayer structures have been investigated in order to understand further and exploit the nature of light propagation within them.     

A response to Bruce (1998) on the Lashley-Hull debate.

Responds to D. Bruce's comments (see record 1998-00831-005) on N. Weidman's original article (see record 1995-00025-001) about the Lashley-Hull debate. The current article addresses the disagreements the author has with Bruce regarding their interpretations of the Lashley-Hull debate. These differences include what actually constituted "the debate," the extent to which the nature-nurture dichotomy was a feature of the debate, and the role of Watson's behaviorism in shaping Lashley's views. The article ends by noting a point on which both authors agree. (PsycINFO Database Record (c) 2010 APA, all rights reserved)