COMPARING FUNCTIONAL DATA ANALYSIS AND HYSTERESIS LOOPS WHEN TESTING TREATMENTS FOR REDUCING HEAT STRESS IN DAIRY COWS

Various techniques are commonly used to reduce heat stress, including sprayers and misters, shading, and changes in feed. Oftentimes studies are performed where researchers do not control the times when animals use shading or other means available to reduce heat stress, making it hard to test differences between treatments. Two methods are used on data from a study where Holstein cows were given free access to weight activated “cow showers.” Functional data analysis can be used to model body temperature as a function of time and environmental variables such as the Heat Load Index. Differences between treatment groups can be tested using a Functional Bayesian MCMC model. Alternatively hysteresis loops, such as the ellipse, formed by a plot of air temperature or the Heat Load Index against body temperature over the course of a day can be estimated and their parameters used to test differences between cows with access to showers and cows without. Results from an R package hysteresis, which can estimate these loops and their parameters are illustrated. Functional data analysis allows for looser assumptions regarding the body temperature curve and the ability to look for differences between groups at specific time points, while hysteresis loops give the ability to look at heat stress over the course of a day holistically in terms of parameters such as amplitude, lag, internal heat load and central values

COMPARISON OF SAS PROC NLIN AND NLMIXED FOR PARAMETER ESTIMATION IN PET MODEL

Cattle body temperatures were measured under semi-controlled hot cyclic chamber temperatures. The four-parameter nonlinear PET model, is used to estimate body temperature in cattle challenged by heat stress. For each steer, the parameters can be estimated by the Nlin procedure and the sensitivity of each animal can be studied. It is also desirable to generalize the results by using the Nlmixed procedure to combine both the fixed and random effects. When comparing the results from the two procedures, we found heterogeneity among animals and/or days caused convergence problems for proc Nlmixed. Simulation studies were used to study how deviations from homogeneity effected the accuracy of parameter estimates, coverage of confidence intervals, and measures of nonlinear behavior when using the PET model to describe the dynamics of heat stress in cattle

Total lung capacity by plethysmography and high-resolution computed tomography in COPD

Jamie L Garfield, Nathaniel Marchetti, John P Gaughan, Robert M Steiner, Gerard J CrinerDepartment of Pulmonary and Critical Care Medicine and Department of Radiology, Temple University School of Medicine, Philadelphia, Pennsylvania, USAAim: To characterize and compare total lung capacity (TLC) measured by plethysmography with high-resolution computed tomography (HRCT), and to identify variables that predict the difference between the two modalities.Methods: Fifty-nine consecutive patients referred for the evaluation of COPD were retrospectively reviewed. Patients underwent full pulmonary function testing and HRCT within 3 months. TLC was obtained by plethysmography as per American Thoracic Society/European Respiratory Society standards and by HRCT using custom software on 0.75 and 5 mm thick contiguous slices performed at full inspiration (TLC).Results: TLC measured by plethysmography correlated with TLC measured by inspiratory HRCT (r = 0.92, P < 0.01). TLC measured by plethysmography was larger than that determined by inspiratory HRCT in most patients (mean of 6.46 ± 1.28 L and 5.34 ± 1.20 L respectively, P < 0.05). TLC measured by both plethysmography and HRCT correlated significantly with indices of airflow obstruction (forced expiratory volume in 1 second/forced vital capacity [FVC] and FVC%), static lung volumes (residual volume, percent predicted [RV%], total lung capacity, percent predicted [TLC%], functional residual capacity, percent predicted [FRC%], and inspiratory capacity, percent predicted), and percent emphysema. TLC by plethysmography and HRCT both demonstrated significant inverse correlations with diffusion impairment. The absolute difference between TLC measured by plethysmography and HRCT increased as RV%, TLC%, and FRC% increased. Gas trapping (RV% and FRC%) independently predicted the difference in TLC between plethysmography and HRCT.Conclusion: In COPD, TLC by plethysmography can be up to 2 L greater than inspiratory HRCT. Gas trapping independently predicts patients for whom TLC by plethysmography differs significantly from HRCT.Keywords: lung capacity, plethysmography, high-resolution computed tomography, gas trapping, lung volume measurement error

CHARACTERIZING THERMAL HYSTERESIS IN BODY TEMPERATURE FOR A HEAT STRESSED STEER

Studies have shown that exposure of animals to a high ambient temperature environment poses serious threats to their health, performance and productivity. Above a certain threshold an animal\u27s body temperature (Tb) appears to be driven by the hot ambient temperature (Ta). For steers challenged by heat stress, the Tb-Ta relationship shows a dramatic increase in Tb per unit change of Ta and the dynamics of the Tb-Ta relationship follow a pattern which depends on whether Ta is increasing or decreasing. A delay becomes noticeable in a steer’s thermo-regulatory response to Ta when Ta is controlled to be sinusoidal in the steer’s heat stress chamber. In other words, Tb lags behind Ta. Consequently when plotted in a Tb-Ta phase diagram, a hysteresis effect appears in the form of a hysteresis loop, indicating the steer is thermally challenged. The hysteresis loop shows a rotated elliptical pattern which depends on the delay (or lag) between Tb and Ta. The angle of rotation of the hysteresis loop indicates the correlation (and lag) between Tb and Ta. The area of the elliptical hysteresis loop can be used to quantify the amount of heat stress during the period of thermal challenge. For example, results of a thermal challenge of 32±7oC applied to a Hereford steer showed, the delay is longer (4 hr lag) and ellipse is larger in an acute stage than in a chronic stage (3 hr lag). A greater delay (or lag) suggests more time is needed to dissipate the heat stress. This result suggests, steers in an acute stage require more energy to dissipate heat than steers in a chronic stage

The Impact of Heat Load on Cattle

Heat stress and cold stress have a negative influence on cattle welfare and productivity. There have been some studies investigating the influence of cold stress on cattle, however the emphasis within this review is the influence of heat stress on cattle. The impact of hot weather on cattle is of increasing importance due to the changing global environment. Heat stress is a worldwide phenomenon that is associated with reduced animal productivity and welfare, particularly during the summer months. Animal responses to their thermal environment are extremely varied, however, it is clear that the thermal environment influences the health, productivity, and welfare of cattle. Whilst knowledge continues to be developed, managing livestock to reduce the negative impact of hot climatic conditions remains somewhat challenging. This review provides an overview of the impact of heat stress on production and reproduction in bovines

Long term care provision, hospital length of stay and discharge destination for hip fracture and stroke patients : ESCHRU Report to Department of Health, March 2013

Expenditure on long term care is expected to rise, driven by an ageing population. Coordination between health and long term care is increasingly a priority for policymakers. Elderly individuals living at home who suffer trauma, such as hip fracture or stroke, generally require immediate acute hospital care, followed by long term care and assistance which can be provided either in their home or in a residential or nursing home. However, little is known about the effects of one sector on the other. This study examines the association between formal long term care supply and the probability of being discharged to a long-term care institution (a nursing home or a care home) and length of stay in hospital for patients admitted for hip fracture or stroke

An integrated system to survey boat-based recreational fishing in Western Australia 2011/12

The Department of Fisheries developed an integrated system involving several survey methods to provide a more robust approach for obtaining annual estimates of recreational catch by boat based fishers at both state-wide and bioregional levels. These surveys, which used the recently implemented Recreational Fishing from Boat Licence (RFBL) as the basis for sampling, were the most comprehensive ever conducted in Western Australia. They not only provided estimates of catch and effort but provided the information for the validation of these estimates by enabling comparisons across the various methods