1,091 research outputs found

    Three-dimensional modelling on the hydrodynamics of a circulating fluidised bed

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    The rapid depletion of oil and the environmentalimpact of combustion has motivated the search for cleancombustion technologies. Fluidised bed combustion (FBC)technology works by suspending a fuel over a fast air inletwhilst sustaining the required temperatures. Using biomassor a mixture of coal/biomass as the fuel, FBC provides alow-carbon combustion technology whilst operating at lowtemperatures. Understanding the hydrodynamic processes influidised beds is essential as the flow behaviours causing heatdistributions and mixing determine the combustion processes.The inlet velocities and different particle sizes influence theflow behaviour significantly, particularly on the transitionfrom bubbling to fast fluidising regimes. Computationalmodelling has shown great advancement in its predictive capabilityand reliability over recent years. Whilst 3D modellingis preferred over 2D modelling, the majority of studies use2D models for multiphase models due to computational costconsideration. In this paper, two-fluid modelling (TFM) isused to model a 3D circulating fluidised bed (CFB) initiallyfocussing on fluid catalytic cracker (FCC) particles. Thetransition from bubbling to fast fluidisation over a rangeof velocities is explored, whilst the effects on the bubblediameter, particle distributions and bed expansion for differentparticle properties including particle sizes are compared. Dragmodels are also compared to study the effects of particleclustering at the meso-scale

    Conducting Successful Supervision: Novel Elements Towards an Integrative Approach

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    In recent years that has been an increasing interest in supervision within the UK's cognitive behaviour therapy (CBT) community. This is because the role of supervision has begun to be recognized in relation to the delivery of effective clinical services (Department of Health, 1998), and because of a clear recognition of the need to ensure that CBT practitioners are competent. Perhaps less well recognized in CBT are a number of interesting educational approaches to supervision, ones that may make supervision more successful. This paper summarizes some of these theories from a CBT perspective. Whilst the evidence base does not yet justify being too prescriptive, it is argued that some of these theories, such as Vygotsky's notion of the “Zone of Proximal Development”, provide helpful prompts for reflecting on CBT supervision. An integrative model is constructed from these theories, with illustrative examples and suggestions for future research

    DOES MENOPAUSAL STATUS INFLUENCE SEXUAL RISK? A CROSS-SECTIONAL ANALYSIS OF THE U.S. NATIONAL HEALTH AND NUTRITION EXAMINATION SURVEY

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    Middle-aged and older adults remain sexually active, but the combination of sexual longevity, inconsistent safe sex practices, and poor condom knowledge, increases their likelihood to risk their sexual health. Menopause may influence sexual risk, as postmenopausal women may engage in risky sexual behaviours, while hormonal changes increase physiological vulnerability to sexually transmitted infections. This project explored whether menopause and type of post-menopause (natural versus surgically- induced) influenced sexual behaviour and herpes simplex virus type 2 (HSV-2) seroprevalence, using logistic regression modeling of the U.S. National Health and Nutrition Examination Survey data. Controlling for confounding, menopause was negatively associated with number of sexual partners, negatively associated with condom use in non-partnered low education women, and positively associated with HSV-2. Type of menopause was not associated with any outcomes. This project highlights a need for improved data on sexual behaviour in older adults

    Evaluation of an Intensive Data Collection System for Tennessee Surface Water Quality Assessment and Watershed Model Calibration

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    Water quality regulators, such as the Tennessee Department of Environment and Conservation, are challenged by data scarcity when identifying surface water quality impairment causes and pollutant sources. Surface water quality model users also seek to identify pollutant sources and design and place best management practices to efficiently improve water quality, but have insufficient data for model calibration. This research documents the design and evaluation of a novel, intensive water quality data collection system consisting of a automatic sampler, bi-weekly grab sampling, and a long term deployment sonde. System design characteristics that were emphasized included a focus on gathering data for common impairment causes (pathogens, siltation, nutrients, and dissolved oxygen-DO) and water quality criteria not currently being evaluated (pH and temperature rate of change and diurnal DO fluctuations). In addition, the system was designed to gather data for watershed model calibration in rural, un-gauged watersheds because agriculture is listed as the predominant source of water quality impairment in Tennessee. Thus, the system was unmanned to reduce labor input, self-powered because of limited access to the electrical grid, provided sample preservation (refrigeration at low pH), and included stage measurement. Two identical prototype systems were installed in adjacent ecoregion 67g watersheds in Greene County, Tennessee: Lick Creek, impaired for pathogens, nutrients, and low DO, and Little Chucky Creek, which is unimpaired and a former ecoregion reference stream. The two primary objectives of this research were to evaluate the system power demand and determine whether a large water quality dataset improved impairment cause and source identification. A 270 watt solar panel power supply ultimately failed at Lick Creek during the summer when the refrigerated sampler cooling demand peaked, but was sufficient at Little Chucky Creek. System power supply design equations are provided, but with optimization the power supply used would likely be sufficient. The data collected did significantly improve insight into impairment cause identification. For example, total phosphorus rather than total nitrogen concentrations and low DO appeared to be a potential cause of impairment at Lick Creek. The system design was reliable and could be used to calibrate watershed models to improve source assessment

    Unconscious processing at the subjective threshold - semantic comprehension?

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    Our thoughts and behaviours can sometimes be influenced by stimuli that we are not consciously aware of having seen. For example, the presentation of a word that is blocked from entering conscious visual perception through masking can subsequently influence the cognitive processing of a further target word. However, the idea that unconscious cognition is sophisticated enough to process the semantic meaning of subliminal stimuli is controversial. This thesis attempts to explore the extent of subliminal priming. Empirical research centering on subjective methods of measuring conscious knowledge is presented in a series of three articles. The first article investigates the subliminal priming of negation. A series of experiments demonstrates that unconscious processing can accurately discriminate between two nouns beyond chance performance when subliminally instructed to either pick or not pick a given noun. This article demonstrates not only semantic processing of the instructional word, but also unconscious cognitive control by following a two-word subliminal instruction to not choose the primed noun. The second article investigates subliminal priming of active versus passive verb voice by presenting a prime sentence denoting one of two characters as either active or passive and asking which of two pictorial representations best matches the prime. The series of experiments demonstrates that overall, participants were able to identify the correct image for both active and passive conditions beyond chance expectations. This article suggests that individuals are able to process the meaning of word combinations that they are not aware of seeing. The third article attempts to determine whether subliminal processing is sophisticated enough to allow for the activation of specific anxieties relating to relationships. Whilst the findings reveal a small subliminal priming effect on generalised anxiety, the evidence regarding the subliminal priming of very specific anxieties is insensitive. The unconscious is shown in these experiments to be more powerful than previously supposed in terms of the fine grained processing of the semantics of word combinations, though not yet in terms of the fine grained resolution of emotional priming

    Development and validation of the Facial Affect Learning and Memory Test (Falmt) and Facial Identification of Affect Task (Fiat)

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    The neurocognitive assessment of visuospatial memory has begun to receive attention and has been recognized as being important in the understanding of overall memory processing. Additionally, there has been an increased emphasis on emotion processing, particularly affect discrimination and attention bias. However, little information is currently available on learning and memory for emotional information. Because emotion is expressed to a large extent through nonverbal means, a nonverbal test of emotion learning would be valuable, although no such test currently exists. The aim of the current study was to establish normative performance characteristics, convergent and divergent validity for two newly developed measures of emotionally valenced visuospatial learning and memory, the Facial Affect Learning and Memory Test (FALMT) and the Facial Identification of Affect Task (FIAT). The FALMT was developed in order to examine aspects of emotional visuospatial memory in a manner analogous to non emotional visuospatial learning tasks (e.g. Biber Figure Learning Test), as well as verbal assessments of learning and memory, such as the California Verbal Learning Test (CVLT). The FIAT was developed as a measure of facial affect discrimination, and represents a complementary assessment to the FALMT in the assessment of visuospatial learning and memory of emotional stimuLi For the FALMT, learning across trials, interference effects, loss of information over the delay period, and serial position effects were measured. This study gathered initial evidence of the validity and reliability of these newly developed neuropsychological assessments

    The effect of local life circumstances on female probationers\u27 offending

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    This article examines the influence of change in local life circumstances on the short-term criminal behavior of female drug-abusing probationers. Using a binomial hierarchical generalized linear model, we examine the probability that certain “discrete life events” act to modify or change criminal behavior in the short term. The findings indicate that participants\u27 involvement in conventional activities results in the decreased likelihood of engaging in nondrug crimes but an increased likelihood of drug dealing. Faced with this contradiction, we suggest that the dynamics of offending are altered by the nature of the criminal activity itself and the way in which gender structures criminal involvement

    Does the job matter? Comparing correlates of stress among treatment and correctional staff in prisons

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    The wealth of literature on stress in the correctional workplace focused on correctional officers, frequently ignoring treatment personnel employed in these same institutions. This study advanced the literature on correctional workplace stress by: (1) testing for differences in workplace stress between correctional officers and treatment personnel, (2) examining personal and environmental factors to determine whether distinct precursors to stress existed for these two groups, and (3) utilizing multiple measures of stress. Self-report survey data from 3,794 employees in ten adult prisons in a southwestern state demonstrated that both groups of employees reported moderately high levels of job stress and stress-related health concerns. Apart from perceptions of safety, sources of stress as well as protective factors against stress were similar for both groups with environmental factors demonstrating the most robust impact

    The Effect of Local Life Circumstances on Victimization of Drug‐Involved Women

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    While numerous studies have examined female victimization in the general population, fewer studies have focused specifically on high‐risk populations such as drug‐involved females. Of the existing literature, the Lifestyle Exposure and/or Routine Activities theory is frequently used to examine the antecedent conditions and correlates of female victimization. This study employs a dynamic modeling approach to examine the effect of short‐term change (i.e., monthly) in local life circumstances on female victimization within a criminogenic population. Results demonstrated that risk of victimization increased in months a woman was in a relationship, lived with a significant other and/or her children, engaged in criminogenic behavior, or lived in an transitory situation. Contrary to traditional theoretical expectations, conventional employment did not reduce a women’s likelihood of victimization

    Will no-ownership work for apparel? The endowment effect and perceived risk of collaborative consumption

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    Collaborative consumption (CC) has significantly changed the way people consume resources from everyday goods to non-product assets. In the apparel marketplace, four CC modes are currently facilitated: short-term renting, subscription-based renting, swapping, and consigning. However, despite the rapid growth of CC, adoption has been slow particularly in the apparel industry. Based on the endowment effect, this study proposes two antecedents of perceived risk of CC including a sense of ownership and possession-self association, and hypothesizes that these constructs positively affect perceived risk of CC, which in turn impedes adoption of CC. Two additional moderators (consumers\u27 involvement with apparel products, consumers\u27 emotional attachment to apparel) in the relationship between possession-self bond and perceived risk were also suggested. Using the consumer data collected though a US market research firm, the research model was tested across four different CC modes for apparel. The results of hypotheses testing and implications are discussed
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