Conical Intersections: Relaxation,Dephasing, and Dynamics in a Simple Model

Conical intersections occur on potential energy surfaces of many medium-sized and larger molecules. Their investigation, which has been ongoing for more than six decades, shows that vibronic coupling and relaxation behaviors at conical intersections can become quite complex and show large quantum effects. We present calculations of dynamical behavior in very simple (two-dimensional, degenerate, non-displaced) conical intersection models. The focus is placed on the effects of bath interactions on conical behavior—that is, the extent to which electronic dephasing, nuclear relaxation, and electronic relaxation affect the initially excited wave packet evolving on conical intersection surface. The calculations are carried through using a density matrix picture, with a Lindblad semi-group formalism to characterize relaxation. We observe large quantum effects that act particularly on true conical structures (anti-symmetric with respect to the mixing coordinate), as opposed to comparable-strength interactions without this symmetry. Significant changes in excited-state population decay, and even larger and more striking changes in the (observable) bleach recovery signal, are found.     

Cognitive, behavioral, and family factors in the differentiation of depressive and anxiety disorders during childhood.

Contribution of cognitive, behavioral, and family environment variables to the differentiation of depressive and anxiety disorders in children was explored. 59 children from Grades 4–7 (14 diagnosed with a depressive disorder, 16 diagnosed with depressive and anxiety disorders, 11 diagnosed with an anxiety disorder, and 18 nondisturbed controls) completed measures of the depressive cognitive triad, depressive cognitions, social skills, family environment, and maladaptive family messages. Results of a stepwise discriminant function analysis indicated that 2 discriminant functions composed of 7 variables from the cognitive, behavioral, and family environment domains accounted for 91% of the between-groups variance. Results suggest that depressive disorders can be distinguished from anxiety disorders on the basis of ratings of cognition, social skills, and family environment. Implications for existing research and a model of depression during childhood are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Homophobia and the politics of objectivism: Commentary on Rosenbaum's (1995) "Comment."

Rosenbaum (1995) argued that the 1992 and 1993 volumes of Psychoanalytic Psychology detracted from the image of psychologists as being within science because they included articles about homophobia in psychoanalytic theory and practice. Labeling those who view homosexuality as a pathology "homophobic" is political, according to Rosenbaum, because such labeling is objective and neutral. I deconstruct Rosenbaum's use of the notions of objectivism and neutrality, and conclude that they function as masks for politics, ideology, and values. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electricity produced from renewable energy sources—What target are we aiming for?

In 2001, the European Commission (hereafter “EC”) formulated an ambitious target of 21% of total community electricity consumption to be generated with renewable energy sources by 2010. Moreover, national indicative targets per Member State were specified. In practice, the latter are implemented in all Member States as national production targets, achievable exclusively through an increase of the domestic production of electricity produced from renewable energy sources (hereafter “RES-E”). However, in this article it will be shown that this is not in line with the EC's intent. Looking at the legislative process resulting in the Directive on the promotion of RES-E, it is demonstrated that instead the EC aimed for European trade in renewable electricity through national consumption targets.     

Implantation Studies on Silicon-Doped GaN

Silicon-doped GaN layers grown by low-pressure metalorganic vapor-phase epitaxy with Si concentrations ranging from 2 × 10¹⁷ Si/cm³ to 9.2 × 10¹⁸ Si/cm³ were investigated by means of the perturbed angular correlation (PAC) technique applied to implanted ¹¹¹In(Cd). An undoped GaN film is used as a reference. The Si atoms replace Ga atoms in the lattice, and silicon, being a group IV element, acts as a donor on the Ga site and contributes one extra electron to the conduction band. Hall-effect measurements confirmed that the free charge carrier density is essentially increased and of the order of the silicon concentration. PAC investigations of the annealing behavior after implantation of the ¹¹¹In probes show that best recovery is achieved after annealing at 1200 K and that high silicon concentrations make GaN films more stable at high temperatures. Further, it was found that the temperature dependence of the electric field gradient is reduced by increasing Si concentrations.     

IT service climate,antecedents and IT service quality outcomes: Some initial evidence

Although many IT service management frameworks exist, we still have limited theoretical understanding of IT service quality within a broader nomological network. Building on recent conceptual work on the IT service climate construct, this study empirically establishes it as a predictor of IT service quality using survey data from both IT units and their clients. Also examined was a set of antecedents which provide a foundation upon which a favorable service climate can be built. The IT service climate instrument, when incorporated into employee feedback initiatives, can provide guidance to IT executives about practices to improve service quality.     

Modeling and fabrication of micro tools by pulsed electrochemical machining

Accurate and precise micro tools are essential for the micromachining of complex micro features in a wide range of engineering materials including metals and ceramics. Existing micro tool fabrication processes suffer from drawbacks such as surface cracks, residual stress and deformations. Electrochemical machining of micro tools is proposed in this work to overcome these limitations. In this research, a mathematical model has been developed to predict the diameter of the micro tool fabricated. Experimental verification of the model using an in-house built micro electrochemical machining system reveals good correlation with theoretical predictions. Using the procedure described in this paper, very high aspect ratio (280–450) tungsten micro tools have been produced.     

Microstructure of eutectic 80Au/20Sn solder joint in laser diode package

Laser diodes (LD) are usually bonded onto heat sinks for the purposes of heat dissipation, mechanical support and electrical interconnect. In this study, energy dispersive X-ray analysis (EDX) and electron backscatter diffraction (EBSD) are employed to investigate the microstructure evolution of 80Au/20Sn solder joint in LD package. During reflow, Pt-Sn and (Au, Ni)Sn IMCs were formed at the respective LD/solder and solder/heatsink interfaces, while δ, β and ζ′ phases of Au/Sn intermetallics were found in the solder joint. The Au-rich β and ζ′ phases in the solder joint limit the growth of interfacial IMCs. Chip shear testing showed that the failure occurred within the LD, with partial brittle fracture at the GaAs substrate and partial interfacial delamination at the GaAs/SiN interface. The strong solder bond can be attributed to the high mechanical strength of 80Au/20Sn solder, which provides improved stability for high temperature applications.     

Dual mechanism model for fluid particle breakup in the entire turbulent spectrum

This work provides an in-depth understanding of different breakup mechanisms for fluid particles in turbulent flows. All the disruptive and cohesive stresses are considered for the entire turbulent energy spectrum and their contributions to the breakup are evaluated. A new modeling framework is presented that bridges across turbulent subranges. The model entails different mechanisms for breakup by abandoning the classical limitation of inertial models. The predictions are validated with experiments encompassing both breakup regimes for droplets stabilized by internal viscosity and interfacial tension down to the micrometer length scale, which covers both the inertial and dissipation subranges. The model performance ensures the reliability of the framework, which involves different mechanisms. It retains the breakup rate for inertial models, improves the predictions for the transition region from inertia to dissipation, and bridges seamlessly to Kolmogorov-sized droplets.