The gravity method and interpretive techniques for detecting vertical crustal movements

Observations of temporal variations of gravity can be used as an inexpensive and rapid means of detecting, monitoring, and studying crustal deformation associated with many active geological processes. Such observations can yield qualitative or semiquantitative information on elevation changes and, when combined with independent elevation data, can yield information about changes of the subsurface density field arising from both subsurface displacements and temporal variations of the density of materials in the subsurface. The effectiveness of gravity techniques in specific cases of crustal deformation depends on the configuration of the local gravity field, the physical processes involved in the deformation, and the accuracy with which temporal gravity variations can be measured

Asymmetry of temporal cross-correlations in turbulent shear flows

We investigate spatial and temporal cross-correlations between streamwise and normal velocity components in three shear flows: a low-dimensional model for vortex-streak interactions, direct numerical simulations for a nearly homogeneous shear flow and experimental data for a turbulent boundary layer. A driving of streamwise streaks by streamwise vortices gives rise to a temporal asymmetry in the short time correlation. Close to the wall or the bounding surface in the free-slip situations, this asymmetry is identified. Further away from the boundaries the asymmetry becomes weaker and changes character, indicating the prevalence of other processes. The systematic variation of the asymmetry measure may be used as a complementary indicator to separate different layers in turbulent shear flows. The location of the extrema at different streamwise displacements can be used to read off the mean advection speed; it differs from the mean streamwise velocity because of asymmetries in the normal extension of the structures.Comment: 10 pages, 7 Postscript figures (low quality due to downsizing

Dynamische Korrelationen und nichtnormale Verstärkung in turbulenten Scherströmungen

Die Wechselwirkung von Wirbeln in Strömungsrichtung und so genannten 'Streaks' in Scherströmungen nahe von Grenzflächen führt zu einer Asymmetrie der Kreuzkorrelation. Dieser Effekt wird für ein niederdimensionales Modell sowie Daten direkter numerischer Simulationen nachgewiesen und mit Windkanalmessungen turbulenter Randschichten verglichen. Weiterhin wird der der Einfluss viskoelastischer Fluide auf die Asymmetrie der Kreuzkorrelationen untersucht

Dynamische Korrelationen und nichtnormale Verstärkung in turbulenten Scherströmungen

Die Wechselwirkung von Wirbeln in Strömungsrichtung und so genannten 'Streaks' in Scherströmungen nahe von Grenzflächen führt zu einer Asymmetrie der Kreuzkorrelation. Dieser Effekt wird für ein niederdimensionales Modell sowie Daten direkter numerischer Simulationen nachgewiesen und mit Windkanalmessungen turbulenter Randschichten verglichen. Weiterhin wird der der Einfluss viskoelastischer Fluide auf die Asymmetrie der Kreuzkorrelationen untersucht

Job stress among humanitarian aid workers

Objective: This thesis examined the prevalence of burnout, alcohol consumption, and psychological distress and their association with stress-related working conditions – defined either in terms of the Effort-Reward Imbalance (ERI) model, or the ERI model combined with the Job Demand-Control-Support (job strain) model (DCS) – in two large-scale international samples of humanitarian aid workers. The studies herein were the first in the extant literature to examine organisational stressors using job stress models in this occupational group. Furthermore, given the paucity of previous research on the subjective stress-related experiences of humanitarian aid workers, this thesis also contains an interview-based study that explored how humanitarian aid workers perceived the transactional stress process. One key characteristic of this thesis was that both quantitative and qualitative approaches were utilised to provide a deep and ecologically valid understanding of the stressor-strain relationship. Identifying the links between stressful aspects of work and both psychological and behavioural health outcomes may help inform the design of sector-specific health interventions. Methods: A mixed-methods approach was adopted to allow for a thorough examination of the prevalence of health and health-related behavioural outcomes, their relationship to stress-related working conditions (psychosocial stressors), and the concept of work-related stress in the population under study. Survey designs were used for Study 1 and 2 and involved the administration of a structured questionnaire. For the first study (Parts 1-2, Organisation A), logistic regression analyses were run based on a cross-sectional survey (N = 1,980) conducted separately for men and women to investigate the relations between ERI and both burnout (Part 1) and heavy alcohol consumption (Part 2) while controlling for demographic and occupational characteristics. In Study 2 (Organisation B), logistic regression analyses were based on a cross-sectional survey (N = 283) conducted separately for men and women to investigate the independent and combined relations between the ERI and DCS models and psychological distress while controlling for demographic and occupational characteristics. The final study was interview-based (Study 3, Organisation B) and it explored how humanitarian aid workers (N = 58) employed by a United Nations-aligned organisation perceived the transactional stress process. Results: The prevalence rates for the burnout components were as follows: high emotional exhaustion—36% for women and 27% for men; high depersonalisation—9% and 10%; and low personal achievement—47% and 31% for women and men, respectively. Intermediate and high ERI scores were associated with a significantly increased risk of high emotional exhaustion, with mixed findings for depersonalisation and personal achievement. The prevalence of heavy alcohol consumption among women (18%) was higher than the corresponding rate for men (10%), lending support for the effort-reward perspective only among women. Intermediate and high ERI scores in women was associated with a three-fold risk of heavy alcohol consumption. The results broadly suggest that occupational stressors from the ERI and DCS models, both individually and in combination, are significantly associated with psychological distress. A thematic analysis undertaken within the qualitative study revealed several main themes. An emergency culture was found where most employees felt compelled to offer an immediate response to humanitarian needs. The rewards of humanitarian work were perceived as motivating and meaningful, and employees experienced a strong identification with humanitarian goals and reported high engagement. Constant change and urgent demands were reported by the participants to result in work overload. Finally, managing work-life boundaries, and receiving positive support from colleagues and managers, helped buffer perceived stress, work overload, and negative health outcomes. Conclusions: The results of the present thesis convincingly demonstrate the usefulness of the ERI model as a framework for investigating burnout and heavy alcohol consumption among humanitarian aid workers. Furthermore, the findings demonstrate the independent and combined predictive effects of components of two alternative job stress models (ERI and DCS) on psychological distress. Taken together, the findings underscore the deleterious associations between work-related psychosocial hazards and mental and behavioural health outcomes. Specifically, unique insights were obtained about the work-related stress process in relation to humanitarian aid workers – for example, the emergency culture shaping organisational norms. The results suggest that interventions based on these two influential theories, and supplemented by knowledge on role-specific stressors evident in the sector, hold promise for reducing health outcomes. The practical implications of the results are discussed and suggestions are made in the light of the present research and stress theory

Using Recession Analysis to Characterize Watershed Responses to Drought

In the face of climate change droughts are predicted to become more persistent, further intensifying the need for accurately predicting the timing and magnitude of summer streamflow in rivers. In order to determine the sensitivity of a watershed to drought, there is a need to describe what these drought conditions will look like and to quantify how severe the effects on the rivers and aquifers will be. Discrepancies between model predictions and observed streamflow motivate us to improve our current understanding of watershed responses to drought in order to better characterize it. This dissertation attempts to identify issues surrounding the current understanding of watershed responses to drought. First, we introduce a methodology that can greatly expand the number of watersheds analyzed using recession analysis with water height instead of discharge. Using water height for recession analysis instead of discharge reduces the fieldwork associated with data collection and thus with the same resources more watersheds can be characterized using water height alone. Second, we focused on quantifying the impacts of different recession analysis methods on the parameter estimations and consequences for drought sensitivity interpretation. We conclude that analyzing the recessions collectively is flawed and that analysis should consider individual recessions in order to quantify watershed responses to different hydrological scenarios. Third, we examined how hillslope drainage pathways and residence time varies during a drought event and the associated effects of modeling the process in 2D vs 3D. In 3D, the hillslope drainage path rotates from stream perpendicular to stream parallel as the contributing driving gradient changes with the lowering water table. This results in an increased path length and residence time that is not captured in a 2D model, ultimately changing the timing and magnitude of aquifer contributions to streamflow during drought. While this dissertation has developed a framework for better understanding and predicting streamflow during drought, there are still opportunities to improve the characterization by monitoring more small watersheds, describing the variability in individual recession at low flows, and gaining a deeper understanding of drainage timescale. Knowing how streams and aquifers will respond to drought in future climate scenarios has great implications for water management as it may enable us to identify watersheds that are sensitive or resilient to future drought

Stress management competency framework in English policing

Background The UK Health and Safety Executive’s Stress Management Competency Framework and associated questionnaire, the Stress Management Competency Indicator Tool (SMCIT), address line managers’ behaviours across four competency areas. The application in policing remains unexplored. Aims This study profiled English police officers’ perception of their line managers’ competencies in the framework areas. The odds of experiencing poor mental wellbeing and work attitudes associated with having a line manager with a development need on each competency area were tested. Methods Two hundred and sixty-three police officers completed a survey comprising the SMCIT and measures of psychological distress, resilience and work engagement. Bivariate correlations were calculated to identify patterns of relationships between variables. Binary logistic regression analyses tested the odds of psychological distress caseness, low resilience and low work engagement being associated with officers’ perception of their line manager having a development need on the SMCIT criteria. Results Approximately half the participants reported their line manager had a development need on the ‘Managing and Communicating Existing and Future Work’, ‘Managing the Individual Within the Team’ and ‘Reasoning and Managing Difficult Situations’ competencies, and one quarter on the ‘Respectful and Responsible: Managing Emotions and Having Integrity’ competency. Officers’ rating of their line manager having a development need on the four competency areas was associated with up to four-fold elevated odds of each undesirable state. Conclusions The framework competency areas are relevant to English policing and offer a basis for stress reduction interventions targeted at line managers’ behaviours

Job stress among humanitarian aid workers

Objective: This thesis examined the prevalence of burnout, alcohol consumption, and psychological distress and their association with stress-related working conditions – defined either in terms of the Effort-Reward Imbalance (ERI) model, or the ERI model combined with the Job Demand-Control-Support (job strain) model (DCS) – in two large-scale international samples of humanitarian aid workers. The studies herein were the first in the extant literature to examine organisational stressors using job stress models in this occupational group. Furthermore, given the paucity of previous research on the subjective stress-related experiences of humanitarian aid workers, this thesis also contains an interview-based study that explored how humanitarian aid workers perceived the transactional stress process. One key characteristic of this thesis was that both quantitative and qualitative approaches were utilised to provide a deep and ecologically valid understanding of the stressor-strain relationship. Identifying the links between stressful aspects of work and both psychological and behavioural health outcomes may help inform the design of sector-specific health interventions. Methods: A mixed-methods approach was adopted to allow for a thorough examination of the prevalence of health and health-related behavioural outcomes, their relationship to stress-related working conditions (psychosocial stressors), and the concept of work-related stress in the population under study. Survey designs were used for Study 1 and 2 and involved the administration of a structured questionnaire. For the first study (Parts 1-2, Organisation A), logistic regression analyses were run based on a cross-sectional survey (N = 1,980) conducted separately for men and women to investigate the relations between ERI and both burnout (Part 1) and heavy alcohol consumption (Part 2) while controlling for demographic and occupational characteristics. In Study 2 (Organisation B), logistic regression analyses were based on a cross-sectional survey (N = 283) conducted separately for men and women to investigate the independent and combined relations between the ERI and DCS models and psychological distress while controlling for demographic and occupational characteristics. The final study was interview-based (Study 3, Organisation B) and it explored how humanitarian aid workers (N = 58) employed by a United Nations-aligned organisation perceived the transactional stress process. Results: The prevalence rates for the burnout components were as follows: high emotional exhaustion—36% for women and 27% for men; high depersonalisation—9% and 10%; and low personal achievement—47% and 31% for women and men, respectively. Intermediate and high ERI scores were associated with a significantly increased risk of high emotional exhaustion, with mixed findings for depersonalisation and personal achievement. The prevalence of heavy alcohol consumption among women (18%) was higher than the corresponding rate for men (10%), lending support for the effort-reward perspective only among women. Intermediate and high ERI scores in women was associated with a three-fold risk of heavy alcohol consumption. The results broadly suggest that occupational stressors from the ERI and DCS models, both individually and in combination, are significantly associated with psychological distress. A thematic analysis undertaken within the qualitative study revealed several main themes. An emergency culture was found where most employees felt compelled to offer an immediate response to humanitarian needs. The rewards of humanitarian work were perceived as motivating and meaningful, and employees experienced a strong identification with humanitarian goals and reported high engagement. Constant change and urgent demands were reported by the participants to result in work overload. Finally, managing work-life boundaries, and receiving positive support from colleagues and managers, helped buffer perceived stress, work overload, and negative health outcomes. Conclusions: The results of the present thesis convincingly demonstrate the usefulness of the ERI model as a framework for investigating burnout and heavy alcohol consumption among humanitarian aid workers. Furthermore, the findings demonstrate the independent and combined predictive effects of components of two alternative job stress models (ERI and DCS) on psychological distress. Taken together, the findings underscore the deleterious associations between work-related psychosocial hazards and mental and behavioural health outcomes. Specifically, unique insights were obtained about the work-related stress process in relation to humanitarian aid workers – for example, the emergency culture shaping organisational norms. The results suggest that interventions based on these two influential theories, and supplemented by knowledge on role-specific stressors evident in the sector, hold promise for reducing health outcomes. The practical implications of the results are discussed and suggestions are made in the light of the present research and stress theory