Environmental Comfort Criteria: Weighting and Integration

This paper presents an integration method for evaluating environmental quality in office buildings based on a series of interviews with 50 experts in the field of environmental quality in the built environment. A structured questionnaire was completed by experts during the interviews. The categories of environmental quality considered in this evaluation include lighting comfort, acoustic comfort, thermal comfort, and acceptable indoor air quality. Each category includes a set of performance criteria. Sixty-five performance criteria covering the evaluation of environmental quality in office buildings were extracted from the interviewed experts. The development of this integration method for assessing the environmental quality of built environments is described and an illustration of its application is presented.     

Discrete element simulation of railway ballast: modelling cell pressure effects in triaxial tests

The paper investigates reproducing the effects of confining pressure on the behaviour of scaled railway ballast in triaxial tests in discrete element models (DEM). Previous DEM work, using a standard Hertzian elastic contact law with an elastic–perfectly plastic tangential slip model, has been unable to replicate the behaviour observed in laboratory tests across a range of confining pressures without altering both the material stiffness and the inter-particle friction. A new contact law modelling damage at the contacts between particles is introduced. Particle contact is via spherically-capped conical asperities, which reduce in height if over-stressed. This introduces plasticity to the behaviour normal to the contact surface. In addition, the inter-particle friction angle is varied as a function of normalized contact normal force. At relatively low normal forces the friction angle must be increased for peak mobilized friction angles to match the laboratory data, an effect that is attributed to interlocking at the scale of surface roughness. Simulation results show close agreement with laboratory data.     

Symptom specificity and the prospective generation of life events in adolescence.

The purpose of the present study was to uncover patterns in the generation of life events from symptom profiles and specific depression symptoms in an effort to obtain a fine-grained understanding of the stress-generation phenomenon. A community sample of 161 adolescents completed the Beck Depression Inventory–II (A. T. Beck, 1996) at Time 1, and then 88 returned 1 year later for an assessment of life events using a rigorous contextual interview and rating system. Consistent with hypotheses, and controlling for baseline stress, cognitive-affective symptoms of depression prospectively predicted higher levels of dependent interpersonal life events. In contrast, somatic symptoms prospectively predicted higher levels of independent life events. Further examination of the types of events generated by specific symptoms suggests that different mechanisms may drive specific patterns of symptom-event generation and suggests that broadening the definition of independence may be necessary to capture the full context of event generation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender differences in life events prior to onset of major depressive disorder: The moderating effect of age.

Theoretical models attempting to explain why approximately twice as many women as men suffer from depression often involve the role of stressful life events. However, detailed empirical evidence regarding gender differences in rates of life events that precede onset of depression is lacking, due in part to the common use of checklist assessments of stress that have been shown to possess poor validity. The present study reports on a combined sample of 375 individuals drawn from 4 studies in which all participants were diagnosed with major depressive disorder and assessed with the Life Events and Difficulties Schedule (Bifulco et al., 1989), a state-of-the-art contextual interview and life stress rating system. Women reported significantly more severe and nonsevere, independent and dependent, and other-focused and subject-focused life events prior to onset of depression than did men. Further, these relations were significantly moderated by age, such that gender differences in rates of most types of events were found primarily in young adulthood. These results are discussed in term of their implications for understanding the etiological role of stressful life events in depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stable carbon isotope evidence for intrinsic bioremediation of tetrachloroethene and trichloroethene at area 6, Dover Air Force Base

Area 6 at Dover Air Force Base (Dover, DE) has been the location of an in-depth study by the RTDF (Remediation Technologies Development Forum Bioremediation of Chlorinated Solvents Action Team) to evaluate the effectiveness of natural attenuation of chlorinated ethene contamination in groundwater. Compound-specific stable carbon isotope measurements for dissolved PCE and TCE in wells distributed throughout the anaerobic portion of the plume confirm that stable carbon isotope values are isotopically enriched in 13C consistent with the effects of intrinsic biodegradation. During anaerobic microbial reductive dechlorination of chlorinated hydrocarbons, the light (12C) versus heavy isotope (13C) bonds are preferentially degraded, resulting in isotopic enrichment of the residual contaminant in 13C. To our knowledge, this study is the first to provide definitive evidence for reductive dechlorination of chlorinated hydrocarbons at a field site based on the delta13C values of the primary contaminants spilled at the site, PCE and TCE. For TCE, downgradient wells show delta13C values as enriched as -18.0/1000 as compared to delta13C values for TCE in the source zone of -25.0 to -26.0/1000. The most enriched delta13C value on the site was observed at well 236, which also contains the highest concentrations of cis-DCE, VC, and ethene, the daughter products of reductive dechlorination. Stable carbon isotope signatures are used to quantify the relative extent of biodegradation between zones of the contaminant plume. On the basis of this approach, it is estimated that TCE in downgradient well 236 is more than 40% biodegraded relative to TCE in the proposed source area.     

Verifying the summit bus converter protocols with symbolic model checking

We report on our investigation of a new verification tool, the Symbolic Model Verifier (SMV), created at Carnegie Mellon University. We have successfully, employed this tool to detect deadlock in an industrial design, namely, Hewlett-Packard's Summit bus converter chips. In addition to locating a known deadlock in the original chip design and checking its solution, we successfully detected other previously unknown defects in the design. In our experiments, we were able to verify properties on finite-state models of the circuit with 150 to 200 state variables in a matter of minutes.     

Repeated exposure to stress across the childhood-adolescent period alters rats' anxiety- and depression-like behaviors in adulthood: The importance of stressor type and gender.

This research tests the hypothesis that specific forms of adversity in early life map onto behavioral signs analogous to depression versus anxiety in later life. Male and female rats were exposed to either severe sporadic stress or chronic mild stress during the childhood-adolescent period, and their behavior was tested in adulthood. Males in the severe sporadic stress group showed exaggerated anxiety-related behaviors, as indicated by increases in shock-probe burying and escape-like responses (jumps) from the open arms of the elevated plus-maze. Females exposed to severe sporadic stress displayed no change in burying behavior but did display increases in escape behavior. These same females also exhibited behaviors analogous to depression that manifested as decreased sucrose consumption. The chronic mild stress regime produced effects only in females, including reduced burying, decreased sucrose consumption, and an exaggerated corticosterone response to cold-water immersion stress. Findings reiterate the importance of early life experience to the development of adult psychopathologies and emphasize the need to consider both the type of early experience and gender differences in these analyses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)