Sustainability for Virginia dairy farms requires balancing phosphorus (P) imports and exports at the farm-gate level. Balancing P helps prevent further accumulation of P in farm soils through routine applications of manure, which over time contributes to surface water quality issues. The objectives of this research centered on guiding dairy farms in Virginia toward lower, more sustainable P balance, and without adversely impacting profitability. First, the state of P balance had to be determined for a sample of dairy farms, including risk factors for excessively high P balance. Second, a repeated assessment of P balance on those dairy farms sought to determine any key factors of change in P balance between years. Lastly, a small Virginia dairy farm was used as a case farm to evaluate whether or not it could reduce its P balance while maintaining or improving farm profitability. An initial assessment of 58 dairy farms in Virginia showed that 75% of farms could operate with a P balance less than 18.7 kg ha-1. The two risk factors that led to excessively high P surpluses were the use of poultry litter and excessive P imported with purchased feed. The repeated assessment included 30 of the 58 original dairy farms. Increases of 1.0 kg P ha-1 of total P imports and exports were respectively correlated to a mean P balance increase of 0.76 kg ha-1 and a mean P balance decrease of 0.43 kg ha-1, suggesting that changes in P imports affect changes in P balance more than changes in P exports. Reduced poultry litter use was highly correlated to reduced P balance, and increasing cow manure exports also reduced P balance for the farms with the opportunity. As a significant portion of the farms assessed were small (less than 200 milking cows), a case farm of 105 cows on 100 acres was used to explore how farm profitability could be affected as P balance was reduced through additional acres, increased crop production, and with a grazing-based farming strategy. Results from partial budget analysis showed that after expanding the land base from 100 to 150 acres for crop production, the change in potential net return ranged from $-0.90 to $1.26/cwt of milk, with accompanying changes in P balance ranging from -9.0 to -14.7 lbs/ac. The analysis also showed that changes in potential net returns after converting to a grazing-based system ranged from $-2.14 to $1.39/cwt, with greater change in P balance ranging from -9.7 to -17.8 lbs/ac. The most profitable strategy, generally, for this farm seemed to be expanding the land base and growing a cash crop. Phosphorus balance on Virginia dairy farms can be reduced, potentially without negative impacts on farm net return, though challenges remain for farms with limited land or areas with high density of animal agriculture. / Doctor of Philosophy / Phosphorus (P) is a vital nutrient for crops and livestock, but too much of it in soils leads to surface water quality problems. Sustainability for Virginia dairy farms requires balancing P imports and exports at the farm level. This research centered on guiding dairy farms in Virginia toward lower, more sustainable P balance. An initial assessment of 58 dairy farms in Virginia helped establish a zone of operation, a feasible target toward which the 25% of farms with high P balance could aim. Avoiding poultry litter as a fertilizer choice and limiting P imported with purchased feed were both ways in which some of these farms could lower their P balance. A repeated assessment in a second year showed that reductions in P imported were more likely to reduce P balance than were increasing P exports. In this, reducing the use of poultry litter as a fertilizer was again an effective way of lowering P balance. As a significant portion of the farms assessed were small (less than 200 milking cows), a case farm of 105 cows on 100 acres was used to explore how farm profitability could be affected as P balance was reduced through various management changes. Results showed that after expanding the land base by at least 50 acres for additional crop production, P balance could be significantly reduced while maintaining or increasing the potential net return to the farmer, especially if the farmer can ensure a high milk yield grazing-based operation or if they grow a cash crop like corn or soybeans. Overall, the research suggests that P balance on Virginia dairy farms can be reduced, and that these farms can operate more sustainably, though challenges remain for farms with limited land or areas with high density of animal agriculture.

A 2-yr field study was conducted to reduce nutrient losses from Virginia dairy farms through nutritional and herd management practices. Ten collaborator herds were identified, all at state DHIA average or better for milk yield and days open. Baseline feed samples and ration information were collected for 2 mo and analyzed for phosphorus (P) and nitrogen (N). Feeds were analyzed monthly, and monthly DHIA milk yield, milk composition, milk urea N (MUN), and reproductive data were recorded. Blood and fecal samples were collected from 25 cows/herd every 3 mo to monitor P excretion and blood urea N. Nutrient balances were developed for each farm for N and P at the start of the study and following ration and management changes. Collaborator herds imported, on average, 290% more N and 320% more P onto the farm than was removed through milk, culled animals, crop sales, or manure sales. By following NRC (1989) recommendations, collaborator farms could reduce N inputs by 21% and P inputs by 45%. Minimizing P in purchased feed, purchased feeds/cow, purchased feeds/ha, and total P input could cause significant reductions in P balance for participating collaborator herds. None of the N variables tested (purchased feed, purchased feed/cow, purchased feed/ha, and total N input) provided significant reductions. / Master of Science

Falls from heights are the fourth leading cause of occupational injury and fatality in the United States. In particular, construction workers such as roofers are often exposed to high risk environments. Recent research has reported that a leading cause of falls among workers is a loss of balance. Therefore, in moving towards reducing the number of occupational falls, further investigation of balance and factors that influence postural control is necessary. The effect of neuromuscular fatigue has been addressed by many investigators; however, few studies have examined the effect of localized fatigue in muscles not located in the lower extremities. Because low back fatigue is so prevalent during manual labor, this investigation determined to study the effects of lumbar extensor fatigue on balance. Chapter 1 includes a complete review of current literature addressing the effects of muscular fatigue on measures of balance. Chapter 2 details an initial investigation of lumbar extensor fatigue on center of pressure (COP) based measures of postural sway and examines the effect of fatiguing rate. Chapter 3 examines the effects of different levels of lumbar extensor fatigue and expands on the previous investigation by examining center of mass (COM) movement and incorporating additional measures of postural control. The results of these investigations indicate that lumbar extensor fatigue affects both COP and COM measures of postural sway, and might also lead to an increased reliance on feedforward postural control mechanisms. These findings contribute to understanding of effects of fatigue on balance and may aid the future design of interventions aimed at fall prevention. / Master of Science

Ankle arthritis is a debilitating condition that causes severe pain and decreased function in the affected limb on the order of end-stage hip arthrosis, end-stage kidney disease, and congestive heart failure. Total ankle replacement is a viable surgical option for treating end-stage ankle arthritis, but few have studied its effects on balance over time. Therefore, the purpose of this study was to test the accuracy of a single-marker method of tracking center of mass, evaluate center of pressure measurements in total ankle replacement patients, and analyze lower extremity joint contributions over a two-year recovery period. Subjects stood on two force platforms for ten seconds in different conditions, and relevant variables were calculated from the force platform and 3D motion capture data. Results showed that increasing recovery time restored partial symmetry between the surgical and non-surgical limbs in ground reaction force, ankle range of motion, and ankle and hip moment contribution in static balance tasks. Furthermore, the ankle and hip may have different roles in postural stability. The results of the studies suggest that total ankle replacement is an effective treatment for end-stage ankle arthritis in terms of restoring postural stability. While patients may not have returned to the level of healthy control subjects, they are more functional and more stable after a two-year recovery period. While further work is needed, the results are encouraging for the outlook of ankle arthritis patients who may need total ankle replacement surgery. / Master of Science / Ankle arthritis is a debilitating condition that causes severe pain and decreased function in the affected limb on the order of end-stage hip arthrosis, end-stage kidney disease, and congestive heart failure. Total ankle replacement is a viable surgical option for treating end-stage ankle arthritis, but few have studied its effects on balance over time. Therefore, the purpose of this study was to test the accuracy a simplified method to track the center of gravity of the human body, evaluate center of pressure (the point where the force of body weight acts) measurements in total ankle replacement patients, and analyze lower extremity joint contributions to balance over a two-year recovery period. Subjects stood on two force measurement platforms for ten seconds in different conditions, and relevant variables were calculated from the force platform and 3D motion capture data. Results showed that increasing recovery time restored partial symmetry between the surgical and non-surgical limbs in weight-bearing force, center of pressure excursion, and ankle and hip contributions to stability. The results of the study suggest that total ankle replacement is an effective treatment for end-stage ankle arthritis in terms of restoring balance. While patients may not have returned to the level of healthy people, the results suggest they are more stable after a two-year recovery period. While further work is needed, the results are encouraging for the outlook of ankle arthritis patients who may need total ankle replacement surgery.

No / Within this chapter, we explore the use of participant photo-elicitation methods in studying how people manage their daily episodes or incidences of work-life balance. Participant photo-elicitation methods rely upon research participants taking their own photographs of a subject as guided by the researcher(s). In addressing this particular technique, we explore some important methodological issues for HRM researchers who seek to use these methods and explain how this type pop methodology has much to offer when studying HR issues such as work-life balance. We conclude that one of the major benefits of the method is the role of photographs as a "conversational technology" (Gammack & Stephens, 1994, p. 76) in encouraging participants to talk and reflect.

No / A multivariate analysis identified six predictors to explain positive work-life balance (WLB) among 1,566 teleworkers. Time flexibility variables were found to be most dominant. Gender or having dependent children was not significant. These results demonstrated that controlling working hours was the most important ability for sampled teleworkers to achieve positive WLB.

No / Visual impairment is an important risk factor for falls, but relatively little is known about how it affects stair negotiation. The present study determined how medio-lateral (ML) dynamics of stepping and single limb support stability when stepping up or down to a new level were affected by blurring the vision of healthy elderly subjects. Twelve elderly subjects (72.3±4.2years) were analysed performing single steps up and single steps down to a new level (7.2, 14.4 and 21.6cm). Stepping dynamics were assessed by determining the ML ground reaction force (GRF) impulse, lateral position of the centre of mass (CM) relative to the supporting foot (average horizontal ML distance between CM and CP during single support) and movement time. Stability was determined as the rms fluctuation in ML position of the centre of pressure (CP) during single support. Differences between optimal and blurred visual conditions were analysed using a random effects model. Duration of double and single support, and the ML GRF impulse were significantly greater when vision was blurred, while the average CM¿CP ML distance and ML stability was reduced. ML stability decreased with increasing step height and was further decreased when stepping down than when stepping up. These findings indicate that ML balance during stepping up and down was significantly affected by blurring vision. In particular, single limb support stability was considerably reduced, especially so during stepping down. The findings highlight the importance of accurate visual feedback in the precise control of stepping dynamics when stepping up or down to a new level, and suggest that correcting common visual problems, such as uncorrected refractive errors and cataract may be an important intervention strategy in improving how the elderly negotiate stairs.

No

Yes / Both flexible working and worklife balance (WLB) are important issues for the midwifery profession and can have both positive and negative consequences for midwives working in the National Health Service (NHS). This study examined midwives’ views and experiences of flexible working, work-life balance and the implications for the midwifery profession.

<p><em>How do additional data of the same and/or different type contribute to reducing model parameter and predictive uncertainties?</em> This was the question addressed with two models – the HBV hydrological water balance model and the ICBM soil carbon balance model – that were used to investigate the usefulness of the Generalized Likelihood Uncertainty Estimation (GLUE) method for calibrations and uncertainty analyses.  The GLUE method is based on threshold screening of Monte Carlo simulations using so-called informal likelihood measures and subjective acceptance criterion. This method is highly appropriate for model calibrations when errors are dominated by epistemic rather than stochastic uncertainties.  The informative value of data for model calibrations was investigated with numerous calibrations aimed at conditioning posterior parameter distributions and boundaries on model predictions.  The key results demonstrated examples of: 1) redundant information in daily time series of hydrological data; 2) diminishing returns in the value of continued time series data collections of the same type; 3) the potential value of additional data of a different type; 4) a means to effectively incorporate fuzzy information in model calibrations; and 5) the robustness of estimated parameter uncertainty for portability of a soil carbon model between and tropical climate zones.  The key to obtaining these insights lied in the methods of uncertainty analysis used to produce them.  A paradigm for selecting between formal and informal likelihood measures in uncertainty analysis is presented and discussed for future use within a context of climate related environmental modeling.</p>