Resting frontal EEG asymmetry as an endophenotype for depression risk: Sex-specific patterns of frontal brain asymmetry.

Resting frontal electroencephalographic (EEG) asymmetry has been hypothesized as a marker of risk for major depressive disorder (MDD), but the extant literature is based predominately on female samples. Resting frontal asymmetry was assessed on 4 occasions within a 2-week period in 306 individuals aged 18–34 (31% male) with (n = 143) and without (n = 163) lifetime MDD as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (American Psychiatric Association, 1994). Lifetime MDD was linked to relatively less left frontal activity for both sexes using a current source density (CSD) reference, findings that were not accounted for solely by current MDD status or current depression severity, suggesting that CSD-referenced EEG asymmetry is a possible endophenotype for depression. In contrast, results for average and linked mastoid references were less consistent but demonstrated a link between less left frontal activity and current depression severity in women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Managing uncertainty and discontinuous condition numbers in geometric computation

We consider operations on subdivision surfaces under the strict robustness requirement that these floating-point computations return an object with the same topological form as the true solution. The problems involved may however be ill-conditioned, and defined in terms of uncertain data, and even supplementary interval arithmetic may not ensure robustness. Trapping mechanisms are therefore proposed to resolve this difficulty.     

Effect of Laser Processing Parameters on the Formation of Intermetallic Compounds in Fe-Al Dissimilar Welding

Fusion welding of steel to aluminum is difficult due to formation of different types of Fe-Al intermetallics (IMs). In this work, 2 mm-thick steel was joined to 6 mm aluminum in overlap configuration using a 8 kW CW fiber laser. A defocused laser beam was used to control the energy input and allow melting of the aluminum alone and form the bond by wetting of the steel substrate. Experimentally, the process energy was varied by changing the power density (PD) and interaction time separately to understand the influence of each of these parameters on the IM formation. It was observed that the IM formation is a complex function of PD and interaction time. It was also found that the mechanical strength of such joint could not be simply correlated to the IM layer thickness but also depends on the area of wetting of the steel substrate by molten aluminum. In order to form a viable joint, PD needs to be over a threshold value where although IM growth will increase, the strength will be better due to increased wetting. Any increase in interaction time, with PD over the threshold, will have negative effect on the bond strength.     

On the power of deep pushdown stacks

Inspired by recent work of Meduna on deep pushdown automata, we consider the computational power of a class of basic program schemes, NPSDS _s , based around assignments, while-loops and non-deterministic guessing but with access to a deep pushdown stack which, apart from having the usual push and pop instructions, also has deep-push instructions which allow elements to be pushed to stack locations deep within the stack. We syntactically define sub-classes of NPSDS _s by restricting the occurrences of pops, pushes and deep-pushes and capture the complexity classes NP and PSPACE. Furthermore, we show that all problems accepted by program schemes of NPSDS _s are in EXPTIME.     

Design Guidelines for Polyethylene Pipe Interface Shear Resistance

Polyethylene pipes are commonly used in pipeline systems. Current methods used to determine the pipe pullout capacity do not consider the effects of diameter changes and cyclic movements that the pipelines may experience. Laboratory tests were performed to study the interface shearing resistance of polyethylene pipes under varying conditions. The tests were performed in a temperature-controlled room, where properties were investigated for thermal variations expected in the field. Two types of tests were performed: pull/push tests and cyclic tests. Test results indicated that reductions in pipe diameter affect the interface shear resistance that develops between the pipe and soil. As the pipe diameter gets smaller, the normal contact stresses at the interface decreases, causing a reduction in the interface shearing resistance directly proportional to the normal stress changes. Cyclic pipe movements also cause significant reduction in pipe pullout resistance. The test results indicated that the polyethylene pipe interface shear resistance can be significantly lower than the one determined using the current methods. This paper presents the test results, findings, and design recommendations for the pullout resistance of buried polyethylene pipes.     

Blood lead (Pb) levels: Further evidence for an environmental mechanism explaining the association between socioeconomic status and psychophysiological dysregulation in children.

Objective: The authors recently reported that blood lead (Pb) was a significant mediator for the positive association between socioeconomic status (SES) and peripheral vascular responses to acute stress in children (B. B. Gump et al., 2007). The present study considers the possibility that Pb may also mediate an association between SES and cortisol responses to acute stress. Design: Early childhood Pb exposure was tested as a mediator for cross-sectional associations between SES and cortisol responses. Main Outcome Measures: The primary outcome was cortisol responses to acute stress in 9.5-year-old children (N = 108). Results: Lower family income was associated with significantly greater cortisol levels following an acute stress task. A mediational analysis confirmed that Pb was a significant mediator for this association. Conclusion: These results reaffirm the importance of considering the chemical environment as well as social and psychological environment when evaluating psychophysiological effects of low SES. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Absorption isotherms for H2(D2)–Pd0.8Ag0.2 (198–323 K)

Isotherms for H₂/D₂–Pd_0.8Ag_0.2 systems have been measured over a low temperature range, 198–323 K. Such low temperature data for this system have not been obtained previously. The absorption kinetics was found to be fast. The isotherms at low temperatures are compared with literature values at or above 313 K, as well as those for H₂(D₂)–Pd systems. The H/D isotope effect and the separation factors in the plateau range over Pd_0.8Ag_0.2 are calculated at various temperatures and discussed, based on the isotherms. Enthalpies are extracted from van’t Hoff plots and compared with calorimetric values and the results from the literature for both absorption and desorption processes. A method is given for using isotherm information from single isotope systems to estimate the separation factor for the mixed isotope systems and this is a helpful tool.The challenge of measuring absorption isotherms at low temperatures and low pressures is discussed. Sample pre-treatment, non-soluble impurity accumulation in an absorption process and thermal transpiration effects are examined.     

Practices,projects and portfolios: Current research trends and new directions

Project portfolio management (PPM) bridges strategy and project management. Traditional research in PPM has primarily investigated the rational, top-down and structural aspects of strategizing. By doing so, it has failed to focus on the underlying practices that are triggered by the strategy and how these practices frame strategy implementation. Practice-based research provides a methodological lens to explore the reality of strategic enactment through the project portfolio. Practice-based perspectives are under-represented in PPM research; therefore the aim of this paper is to provide an agenda for further practice-based research in PPM. Central to this agenda is a concern with various aspects of practice, including its discursivity, representation, dynamic capabilities, leadership and materiality.