Secondary frost heave in freezing soils

Frost heave describes the phenomenon whereby soil freezing causes upwards surface motion due to the action of capillary suction imbibing water from the unfrozen region below. The expansion of water on freezing is a small part of the overall surface heave and it is the flow of water towards the freezing front which is largely responsible for the uplift. In this thesis, we analyse a model of frost heave due to Miller (1972, 1978) which is referred to as `secondary frost heave'. Secondary frost heave is characterised by the existence of a `partially frozen zone', underlying the frozen soil, in which ice and water coexist in the pore space. In the first part of the thesis we follow earlier work of Fowler, Krantz and Noon where we show that the Miller model for incompressible soils can be dramatically simplified. The second part of the thesis then uses this simplification procedure to develop simplified models for saline and compressible soils. In the latter case, the development of the theory leads to the consideration of non-equilibrium soil consolidation theory and the formation of segregated massive ice within permafrost. The final part of the thesis extends the simplified Miller model to the analysis of differential frost heave and the formation of patterned ground (e.g. earth hummocks and stone circles). We show that an instability mechanism exists which provides a plausible theory for the formation of these types of patterned ground

Instabilities and turbulence in highly ionized plasmas in a magnetic field Semiannual status report, 1 Sep. 1970 - 28 Feb. 1971

Instabilities and turbulence in highly ionized plasmas in magnetic field related to problems of thrustors for manned space flight and plasma generated energ

Looking forward to going back? The experience of career decision-making for first-time mothers and the implications for coaches

The career penalty for professional women who become mothers is well known, while research scrutiny of career decision-making itself appears to have been largely overlooked. This study explores the experience of six London-based professional women, using Interpretative Phenomenological Analysis (IPA) techniques to develop insights into the high-commitment behaviours which underpin female professional career identity; the effects of group norms, cultural messages and employer practices on women’s decision-making; and, the solitary experience of establishing new narratives as a professional mother. It develops insights and implications for organisations and the coaching profession, to better support new mothers with their career decisions

Experiences of aspiring school principals receiving coaching as part of a leadership development programme

Purpose This paper adds depth to our understanding of how coaching works by exploring the experiences of 14 aspiring school principals who received one-to-one leadership coaching as part of a leadership development programme. Design/methodology/approach This study adopts a phenomenological approach. Individual semi-structured interviews were conducted with the participants. Thematic analysis was used to code the data and identify themes. Findings This paper reports on four themes based on the experiences of the participants: having time to reflect, feeling safe to explore, focussing on what's important for me and experiencing positive emotions. Research limitations/implications The findings are unique to the participants who volunteered to take part in this study and therefore not representative of a general population of aspiring educational leaders. Further research is needed into the possible benefits of coaching to support educators undergoing leadership training. Practical implications The findings raise a potential dilemma within the teaching profession about the use of educators' time; while they need to give time and attention to multiple stakeholders, they also need to protect time for their own development and self-reflection. Based on the reported experiences of the participants in this study, it is recommended that coaching be considered a component of professional development for educational leaders. Originality/value This paper adds to the growing research base for coaching in education, providing a unique insight into the experiences of aspiring school principals who received one-to-one leadership coaching as part of a leadership development programme

Ecosystem processes, land cover, climate, and human settlement shape dynamic distributions for golden eagle across the western US

Species–environment relationships for highly mobile species outside of the breeding season are often highly dynamic in response to the collective effects of everchanging climatic conditions, food resources, and anthropogenic disturbance. Capturing dynamic space-use patterns in a model-based framework is critical as model inference often drives place-based conservation planning. We applied dynamic occupancy models to broad-scale golden eagle Aquila chrysaetos survey data collected annually from 2006 to 2012 during the late summer post-fledging period in the western US. We defined survey sites as 10 km transect segments with a 1 km buffer on either transect side (n = 3540). Derived estimates of occupancy were low (4.4–7.9%) and turnover rates – the probability that occupied sites were newly occupied – were high (88–94%), demonstrating that annual transiency in occupancy dominates late summer behavior for golden eagles. Despite low philopatry during late summer, variation in golden eagle occupancy could be explained by a suite of land cover and annual-varying covariates including gross primary productivity, drought severity, and human disturbance. Our summary of 13 years of predicted occupancy by golden eagles across the western United States identified areas that are consistently used and that may contribute significantly to golden eagle conservation. Restricting development and targeting mitigation efforts in these areas offers practitioners a framework for conservation prioritization

Calibration and Cross-Validation of Accelerometery for Estimating Movement Skills in Children Aged 8-12 Years

This study sought to calibrate triaxial accelerometery, worn on both wrists, waist and both ankles, during children’s physical activity (PA), with particular attention to object control motor skills performed at a fast and slow cadence, and to cross-validate the accelerometer cut-points derived from the calibration using an independent dataset. Twenty boys (10.1 ±1.5 years) undertook seven, five-minute bouts of activity lying supine, standing, running (4.5kmph−1) instep passing a football (fast and slow cadence), dribbling a football (fast and slow cadence), whilst wearing five GENEActiv accelerometers on their non-dominant and dominant wrists and ankles and waist. VO2 was assessed concurrently using indirect calorimetry. ROC curve analysis was used to generate cut-points representing sedentary, light and moderate PA. The cut-points were then cross-validated using independent data from 30 children (9.4 ± 1.4 years), who had undertaken similar activities whilst wearing accelerometers and being assessed for VO2. GENEActiv monitors were able to discriminate sedentary activity to an excellent level irrespective of wear location. For moderate PA, discrimination of activity was considered good for monitors placed on the dominant wrist, waist, non-dominant and dominant ankles but fair for the non-dominant wrist. Applying the cut-points to the cross-validation sample indicated that cut-points validated in the calibration were able to successfully discriminate sedentary behaviour and moderate PA to an excellent standard and light PA to a fair standard. Cut-points derived from this calibration demonstrate an excellent ability to discriminate children’s sedentary behaviour and moderate intensity PA comprising motor skill activity.N/

Achieving equity through 'gender autonomy': the challenges for VET policy and practice

This paper is based on research carried out in an EU Fifth Framework project on 'Gender and Qualification'. The research partners from five European countries investigated the impact of gender segregation in European labour markets on vocational education and training, with particular regard to competences and qualifications. The research explored the part played by gender in the vocational education and training experiences of (i) young adults entering specific occupations in child care, electrical engineering and food preparation/service (ii) adults changing occupations