P. E. Hillman's research while affiliated with Cornell University and other places

... In FDA, the first step is to predict individual trajectories using the subjects' available measurements. Once a curve is fitted to each subject, treating each curve as a sample unit, different analyses can be performed on the curves [1,23,34,36]. In our working data set, let y ij represent the SADS of the ith HIV positive patient at the jth time point. ...

... This information also gives insight into the effect of different cooling systems on additional heat losses. To the best of our knowledge, this is the first study to determine the total evaporative water loss rate from dairy cows at a daily level, which can avoid some sources of errors associated with different sweating rates between different skin regions, and cyclic sweating patterns (Berman, 1957;Gebremedhin et al., 2008;Liang et al., 2009;de Souza et al., 2018). With the design of our experiment, we were able to estimate the total evaporative water loss from cows as well as separate it between skin evaporation and respiratory evaporation. ...

... Increases in body temperature are typically the first signs of sickness in livestock, in conjunction with differences in behavior such as listlessness, lethargy, and decreased feed intake (Johnson, 2002). Aside from illness, changes in body temperature have also been associated with differences in stress responsiveness as well as differences associated with natural variations in breed and sex (Carroll et al., 2011;Godfrey et al., 2017;Vinkers et al., 2013). Measurement of body temperature is an important practice in any livestock operation, and the ability to measure frequent body temperature without causing undue stress is becoming a more pertinent issue in order to maintain and improve animal well-being (Sellier et al., 2014). ...

... Regarding rectal temperature and respiratory rate in pregnant ewes, these physiological variables were expected to be higher in pregnant animals due to the increased metabolic rate resulting from pregnancy and also because the developing fetus loses heat through the fetal circulation and uterine wall, and fetal heat production represents an extra thermal load on the mother (Yaqub et al., 2017). However, in the present study the rectal temperature was seen to be slightly lower in pregnant ewes, it is believed that it may be part of a physiological response to help protect the developing fetus from exposure to elevated temperatures in the uterus during the last trimester of pregnancy, even that the fetus is reasonably well developed at this time (Godfrey et al., 2017). This lower rectal temperature seen in pregnant ewes may have been due to heat dissipation mainly through sweating and sensitive heat exchange and to a lesser extent through respiratory rate. ...

... he day in the different areas of the barn (mainly in the feeding alley, excluding feeding cows, where the cooling by surface was installed) (Fig. 6) . The increase of this normal behaviour, because standing improves heat dissipation, is a consequence of the greater difficulties in maintaining thermal balance of the STLM compared with the SAMM cows. Hillman et al. (2005) observed that, with or without free stall spray cooling, cows stood and sought cooling when their core body temperatures reached 38.9°C.4 Hourly average of animals lying in the free stalls (as percentage of total cows in the pen) recorded during the days of a hotter period (28 July to 8 August 2004) recorded in the two pens (SAMM free s ...

... Studies with adult animals have observed that animals with a dark external surface are more subject to heat stress than those of light colour, presenting greater absorbance of different wavelengths. In contrast, lighter hairs show greater reflectance, absorbing smaller amounts of thermal energy (Gebremedhin and Hillman, 1997;Silva et al., 2003;Maia et al., 2005). The small body size and a relatively large surface about its mass are striking characteristics in new-born animals, making them efficient heat sinks and more susceptible to variations in the thermal environment, when compared to adult animals (Cain et al., 2006;McManus et al., 2009). ...

... Artificial shade is in the forefront of environmental modification to mitigate the negative impacts of heat stress and to improve welfare of beef cattle, particularly in tropical environments where animals face high levels of short-wave solar radiation (1,2). The benefits of shade for animals come from reducing radiant heat gain (3,4), body heat storage (5), evaporative cooling through panting and sweating (6)(7)(8)(9) and by increasing the frequency of beneficial behaviors (e.g., lying down, ruminating, and playing (10)(11)(12). ...

... Few of the farmers, however, were aware of the benefits of using sprayers, misters, dynamic ventilation and wetting for keeping animals cool. Many studies have reported that applying water directly to the skin of animals and using water spraying alleviates heat stress (Gebremedhin et al., 2010). Increasing air movement by fans in a hot and humid climate reduces rectal temperature, respiration and pulse rates and increases the milk yield of dairy cows (Calamari et al., 1995). ...

... Besides a higher THI, the duration of exposure to high THI reflects the true impact of heat stress on the animals, thus affecting animal health and productivity. Animals have been shown to perform best only if the THI remains below the critical threshold during the relaxation period (Spiers et al., 2001;Lee and Hillman, 2007), and a THI of less than 64 for at least 6 h could reduce the potential harms of heat stress (Igono et al., 1992). Data indicated that the diurnal variation of the THI and WS occurred during the four hottest summer months (June to September), inferring current environmental conditions at both sites ( Figure 5). ...

... Lying down reduces heat from a warm surface and increases the efficiency of respiration in ruminants [15]. Previous studies have suggested that time spent lying down increases and standing time decreases when cattle are provided with shade [36,37]. Therefore, beef steer behaviors, including standing and lying down, are important eye-tracking indicators during HS. ...