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Articles 1 - 8 of 8
Full-Text Articles in Entire DC Network
A Comparison Of Commonly Used Accelerometer Based Activity Monitors In Controlled And Free-Living Environment, Yuri Feito
Doctoral Dissertations
This dissertation was designed to determine the effects of body mass index (BMI) and walking speed on activity monitor outputs. A secondary purpose was to compare the activity monitors’ performance in a free-living environment. In the first experiment, 71 participants wore three waist-mounted activity monitors (Actical, ActiGraph, and NL-2000) and an ankle-mounted device (StepWatch 3) while walking on a treadmill (40, 67 and 94 m/min). The tilt angle of each device was measured. The Actical recorded 26% higher activity counts (P < 0.01) in obese persons with a tilt <10 degrees, compared to normal weight persons. The ActiGraph was unaffected by BMI or tilt angle. In the second experiment, the steps recorded by the devices were compared to actual steps. Speed had the greatest influence on the accuracy these devices. At 40 m/min, the ActiGraph was the least accurate device for normal weight (38%), overweight (46%) and obese (48%) individuals. The Actical, NL-2000 and StepWatch averaged 65%, 73% and 99% of steps taken, respectively. Lastly, several generations of the ActiGraph (7164, GT1M, and GT3X), and other research grade activity monitors (Actical; ActivPAL; and Digi-Walker) were compared to a criterion measure of steps. Fifty-six participants performed treadmill walking (40, 54, 67, 80 and 94 m/min) and wore the devices for 24-hours under free-living conditions. BMI did not affect step count accuracy during treadmill walking. The StepWatch, PAL, and the AG7164 were the most accurate across all speeds; the other devices were only accurate at the faster speeds. In the free-living environment, all devices recorded about 75% of StepWatch-determined steps, except the AG7164 (99%). Based on these findings, we conclude that BMI does not affect the output of these activity monitors. However, waist-borne activity monitors are highly susceptible to under-counting steps at walking speeds below 67 m/min, or stepping rates below 100 steps/min. An activity monitor worn on the ankle is less susceptible to these speed effects and provides the greatest accuracy for step counting.
Selected Hormonal And Neurotransmitter Mechanisms Regulating, James L. Sartin, Joseph A. Daniel, Brian K. Whitlock, Robyn R. Wilborn
Selected Hormonal And Neurotransmitter Mechanisms Regulating, James L. Sartin, Joseph A. Daniel, Brian K. Whitlock, Robyn R. Wilborn
Faculty Publications and Other Works -- Large Animal Clinical Sciences
Appetite control is a major issue in normal growth and in suboptimal growth performance settings. A number of hormones, in particular leptin, activate or inhibit orexigenic or anorexigenic neurotransmitters within the arcuate nucleus of the hypothalamus, where feed intake regulation is integrated. Examples of appetite regulatory neurotransmitters are the stimulatory neurotransmitters neuropeptide Y (NPY), agouti-related protein (AgRP), orexin and melanin-concentrating hormone and the inhibitory neurotransmitter, melanocyte-stimulating hormone (MSH). Examination of messenger RNA (using in situ hybridization and realtime PCR) and proteins (using immunohistochemistry) for these neurotransmitters in ruminants has indicated that physiological regulation occurs in response to fasting for several …
Changes In Plasma Concentrations Of Leptin In Ewes During Pregnancy, Joseph A. Daniel, A B. Milam, M E. Gafnea, Brian K. Whitlock, D H. Keisler
Changes In Plasma Concentrations Of Leptin In Ewes During Pregnancy, Joseph A. Daniel, A B. Milam, M E. Gafnea, Brian K. Whitlock, D H. Keisler
Animal Science Publications and Other Works
Previous research has demonstrated circulating concentrations of leptin increase in ewes during mid pregnancy then decline in late pregnancy and early lactation. The objective of this study was to more narrowly define the timing of changes in circulating concentrations of leptin with pregnancy in ewes. Katahdin ewes (n= 19) located at latitude 34.275 and longitude -85.183 (Mount Berry, GA) were utilized. Blood samples were collected weekly via jugular veinpuncture beginning immediately before ram exposure on September 23 and continuing until 4 weeks post-lambing. Ewes were exposed to a ram fitted with a marking harness for a 63 day breeding season. …
Effect Of Leukemia Inhibitory Factor On Feed Intake And Body Temperature In Sheep, James L. Sartin, D L. Marks, Brian K. Whitlock, Joseph A. Daniel, Barbara P. Steele
Effect Of Leukemia Inhibitory Factor On Feed Intake And Body Temperature In Sheep, James L. Sartin, D L. Marks, Brian K. Whitlock, Joseph A. Daniel, Barbara P. Steele
Animal Science Publications and Other Works
Leukemia inhibitory factor (LIF) has been suggested to function as a potent inhibitor of feed intake in rodents. These studies were designed to determine whether LIF was found in the ovine hypothalamus and whether LIF inhibited feed intake in sheep. Sheep hypothalami were used to clone LIF to indicate presence of the gene in the hypothalamus. The sequence was similar to published data. Another group of sheep were provided intraventricular (ICV) cannulas and injected with doses of LIF at 250, 500, 1000 and 2500 ng per sheep, ICV. Feed intake was inhibited by the 1000 and 2500 ng dose (trt, …
Changes In Plasma Concentrations Of Growth Hormone And Luteinizing Hormone In Ewes Following Central And Peripheral Treatment With Kisspeptin, Brian K. Whitlock, Joseph A. Daniel, Barbara P. Steele, James L. Sartin
Changes In Plasma Concentrations Of Growth Hormone And Luteinizing Hormone In Ewes Following Central And Peripheral Treatment With Kisspeptin, Brian K. Whitlock, Joseph A. Daniel, Barbara P. Steele, James L. Sartin
Animal Science Publications and Other Works
Kisspeptin (KP), a neuroendocrine regulator of gonadotropin releasing hormone, has been hypothesized as an integrator of nutrition and hormones critical to metabolism and regulation of reproduction. Recent evidence suggests growth hormone (GH) secretion may be influenced by KP. The objective of this study was to determine if the GH stimulatory effect of KP is due to actions on the hypothalamus or anterior pituitary gland in ewes. Adult ovariectomized ewes (n=8) were fitted with intracerebroventricular (ICV) cannula to facilitate central administration of experimental treatments. Ewes received one of eight treatments [four intravenously (IV) and four ICV]. Peripheral treatments [0 (Veh), 100, …
Accuracy Of Physical Activity Monitors In Pregnant Women, Christopher P. Connolly
Accuracy Of Physical Activity Monitors In Pregnant Women, Christopher P. Connolly
Masters Theses
Purpose: To determine the step count accuracy of three pedometers and one accelerometer in pregnant women during treadmill walking. Methods: Subjects were 30 women in the second or third trimester (20-36 weeks) who were screened for pregnancy-related risk factors. Each subject was fitted with a belt containing three physical activity monitors: Yamax Digiwalker SW-200 (DW), New Lifestyles NL 2000 (NL), and GT3X Actigraph accelerometer (ACT). The Omron HJ-720 (HJ) was placed in the pants pocket. Subjects walked at 54, 67, 80, and 94 m•min-1 for two minutes each. Actual steps were determined by an investigator using a hand-tally counter. Percentage …
Early Vessel Evolution And The Diversification Of Wood Function: Insights From The Malagasy Canellales, Patrick Joseph Hudson
Early Vessel Evolution And The Diversification Of Wood Function: Insights From The Malagasy Canellales, Patrick Joseph Hudson
Masters Theses
Xylem vessels have long been proposed as a key innovation for the ecological diversification of angiosperms by providing a breakthrough in hydraulic efficiency to support high rates of photosynthesis and growth. However, recent studies demonstrated that angiosperm woods with structurally ‘primitive’ vessels did not have greater whole stem hydraulic capacities as compared to vesselless angiosperms. As an alternative to the hydraulic superiority hypothesis, the heteroxylly hypothesis proposes that subtle hydraulic efficiencies of primitive vessels over tracheids enabled new directions of functional specialization in the wood. However, the functional properties of early heteroxyllous wood remain unknown. We selected the two species …
Farm Focus - Spring 2010, Brian K. Whitlock, Matt Welborn, Maria Prado, Amy Plummer
Farm Focus - Spring 2010, Brian K. Whitlock, Matt Welborn, Maria Prado, Amy Plummer
Faculty Publications and Other Works -- Large Animal Clinical Sciences
No abstract provided.