• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 82
  • 63
  • 26
  • 18
  • 13
  • 5
  • 4
  • 3
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 276
  • 276
  • 66
  • 65
  • 49
  • 48
  • 42
  • 40
  • 34
  • 33
  • 32
  • 31
  • 28
  • 27
  • 27
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Energy expenditure and mortuary practices at Lyon's Bluff, 22OK520: an evolutionary approach

Elmore, Lorien Stahl 03 May 2008 (has links)
Mortuary analysis has been used in the past to understand social status and social organization. The need for a scientific way to undertake mortuary analysis in achaeology is necessary because too often social status is assumed. This thesis attempts to demonstrate that there is a scientific approach that can be taken in mortuary analysis through the investigation of energy expenditure, a dimension that can measure the attributes of status. The mortuary analysis in this study is carried out using a scientific approach involving the amount of energy expended on burials by looking at burial type, grave goods, and special placement of the burials. Through the use of archival data, this thesis investigates differences seen in the burial population of Lyon’s Bluff (22OK520) in Oktibbeha County, Mississippi through mortuary analysis that looks at burial type, grave goods, and special placement of the burials. Local farmsteads are used as a comparative basis. Through the creation of a paradigm with dimensions of burial treatments and modes of grave goods, it is possible to place all burials at a particular site or group of sites in categories that show the amount of energy expended on burials. From this, comparisons can be made with age and sex, stature, cranial deformation, and spatial location that can aid in the interpretation of mortuary data at a site. The results of this research suggest that at Lyon’s Bluff and the farmsteads used in this study there is an increase in the energy expended on burials through time. This type of research is applicable to both past and future mortuary analysis when there is well-documented information on burial type and burial inclusions.
22

The effect of Methylphenidate on Energy Expenditure in Individuals with Obesity: A Randomized, Double-Blind, Placebo Controlled Pilot Trial

Hafizi, Kaamel 31 May 2019 (has links)
Objectives: Most weight loss medications target reductions in energy intake while neglecting energy expenditure, a critical predictor of weight loss/regain. This pilot study examined the effect of short-acting methylphenidate (MPH) on resting energy expenditure (REE), thermic effect of food (TEF), physical activity energy expenditure (PAEE), and how changes in energy expenditure relate to changes in body composition in youth and adults living with obesity. Methods: This study was a randomized, double-blind, placebo-controlled two-parallel arm study. In total, 19 participants were screened, of which 14 participants were randomized into the study, but complete data was only collected for 12, and only analyzed for 10 participants. Those 10 participants aged 28.8 ± 6.9 yrs. (5 Male, 5 Female) were randomized to receive either MPH (0.5 mg/kg) (n = 5) or placebo (n =5) twice daily for 60 days. Participants’ REE and TEF (indirect calorimetry), were measured at baseline (no drug/placebo), and day 60 post-treatment (drug/placebo). Participants’ PAEE (Actical) was measured between screening and baseline for a 1-week period (no drug/placebo), and on day 53 for a 1-week period (drug/placebo). Participants’ anthropometrics were measured using DEXA at baseline, and day 60 post-treatment. Results: From baseline to day 60, MPH showed a relative difference to placebo in relative REE (Relative REE: F(1, 8) = 4.235, p = 0.074, d = 0.83, 2 = 0.346) of 10%, evidenced by a 6% increase in relative REE kcal/kg (18.53 ± 1.97 Kcal/day/kg at baseline, 19.71 ± 2.52 Kcal/day/kg at final) for the MPH group, and a 4% decrease (19.08 2.36 Kcal/day/kg at baseline, 18.26 ± 2.04 Kcal/day/kg at final) in placebo, translating to moderate-effect size (Cohen’s d=0.63) favouring MPH. From baseline to day 60, there were no significant differences between groups on changes in TEF (TEF AUC: F(1, 8) = 0.079, p = 0.785, d = 0.15, 2 = 0.010) or any PAEE variables such as sedentary behavior (SB: F (1, 8) = 0.455, p = 0.52, d = 0.02, 2 = 0.054), light physical activity (LPA: F (1, 8) = 0.504, p = 0.50, d = 0.16, 2 = 0.059), moderate physical activity (MPA: F (1, 8) = 0.281, p = 0.61, d = 0.19, 2 = 0.034), moderate-to-vigorous physical activity (MVPA: F (1, 8) = 0.120, p = 0.74, d = 0.15, 2 = 0.015), or vigorous physical activity (VPA: F (1, 8) = 3.495, p = 0.098, d = 0.91, 2 = 0.304) . Mean change in body weight (kg) resulted in a weight loss of roughly -2.66 ± 2.00 kg in the MPH group and -1.64 ± 1.41 kg in the placebo group, differences that were not statistically significant. Mean change in both groups for body fat% of -0.33 ± 2.08 %, mean change in fat mass of -1.05 ± 2.59 kg, and finally a mean change in fat-free mass of -0.06 ± 1.19 kg was reported. Changes in relative REE were inversely correlated with changes in body weight (r = -0.599, p = 0.067), body fat (r = -0.524, p = 0.12) and fat mass (r = -0.599, p = 0.096). These associations were stronger in the MPH group. Conclusions: Our data suggests that MPH administration may lead to a meaningful increase in relative REE, and these suggested changes were associated with reductions in adiposity among individuals with obesity. These preliminary findings suggest that MPH should be further examined using a larger sample size and study duration to determine its effectiveness in promoting weight loss and maintenance of weight loss in individuals with obesity, a population at high risk of morbidity and premature mortality.
23

Estimating patients' energy requirements: Cancer as a case study.

Reeves, Marina Michelle January 2004 (has links)
The nutritional care and management of patients includes provision of adequate nutrition support to ensure that they attain and maintain a desirable body weight, improve nutritional status and avoid negative outcomes associated with over- or underfeeding. The success of nutrition support relies on accurately estimating energy requirements so that adequate energy and nutrients can be provided to the patient. Energy requirements are most accurately determined by measurement of energy expenditure. Most methods for doing so however are expensive, time-consuming, require trained technicians to perform them and are therefore impractical in the clinical setting. As such, prediction equations, which are easy to use, inexpensive and universally available, are commonly used to estimate the energy requirements of hospitalised patients. The accuracy of these equations however is questionable. Recently, a new portable hand-held indirect calorimeter (MedGem(tm), HealtheTech, USA), which has been promoted for its ease of use and relatively short measurement time, has been validated in healthy subjects but is yet to be validated in patients with illnesses. Weight loss and malnutrition occur commonly in patients with cancer and are often thought to be associated with disturbances in energy metabolism caused by the tumour. Minimising weight loss is an important goal for the nutritional care of patients with cancer. The ability to accurately determine the energy requirements of these patients is therefore essential for the provision of optimal nutrition support. This research project proceeded in two phases. Phase 1 aimed to determine current methods used by dietitians for estimating adult patients' energy requirements using a descriptive study. Results of this study informed phase 2, which aimed to investigate differences in energy expenditure of cancer patients compared to healthy control subjects and to compare different methods for determining energy requirements of people with cancer in the clinical setting. To address phase 1 a national cross-sectional survey of dietitians working in acute care adult hospitals was undertaken to determine their usual dietetic practice with respect to estimating patients' energy requirements. Responses to the survey (n=307, 66.2%) indicated a large variation in dietitians' practice for estimating energy requirements particularly with respect to the application of methods involving injury factors. When applied to a case study, these inconsistencies resulted in an extremely wide range for the calculated energy requirement, suggesting that there is error inherent in the use of prediction methods, which may be associated with negative consequences associated with under- or overfeeding. The types of patients for whom dietitians estimate energy requirements appears to be heavily influenced by feeding method. Initial dietetic education was identified as the main influencing factor in the choice of method for estimation of energy requirements. Phase 2 was addressed using four studies based on the same study population - a case-control study, two clinical validation studies and a measurement methods study. Patients had histologically proven solid tumours, excluding tumours of the breast, prostate and brain, and were undergoing anti-cancer therapy (n=18). Healthy control subjects were group matched to cancer patients by gender, age, height and weight from a purposive sample (n=17). Resting energy expenditure (REE) was measured by respiratory gas exchange using a traditional indirect calorimeter (VMax 229) and the MedGem indirect calorimeter. A measurement methods side-study established that steady state defined as a three-minute period compared to a five-minute period measured REE within clinically acceptable limits. REE was also predicted from a range of prediction equations. Analyses of available data found that REE in cancer patients was not significantly different from healthy subjects, with only a 10% higher REE observed in this sample of cancer patients when adjusted for fat free mass. For both cancer patients and healthy subjects the portable MedGem indirect calorimeter and all prediction equations did not measure or estimate individual REE within clinically acceptable limits compared to the VMax 229 (limits of agreement of approximately -40% to 30% for both the MedGem and prediction equations). Collectively, the results of this research project have indicated that current practical methods for determining patients' energy requirements in a clinical setting do not accurately predict the resting energy expenditure of individual subjects, healthy or with cancer. Greater emphasis should therefore be placed on ensuring intake meets requirements. For this to occur, dietetic practice should be focused on directly monitoring both patients' actual energy intake and patient outcomes, such as weight, body composition and nutritional status, to determine whether energy requirements are being met. This research has led to multiple recommendations for dietetic practice, focusing on the standardisation of education practices. Recommendations for future research address methodological improvements.
24

High Levels of Total Energy Expenditure in Ultra-Endurance Athletes: Is There Evidence for Constraint?

Howard, Kristen Renee 14 May 2024 (has links)
The benefits of an active lifestyle are undisputed, yet our understanding of the contribution of physical activity (PA) to the daily energy budget is limited. The prevailing model of a linear relationship between PA and total energy expenditure (TEE) has been challenged by models that predict an upper limit of TEE (constrained) or a compensatory decrease elsewhere in the budget in response to increased PA (compensated). The purpose of this study was to determine the equation of best fit between PA and TEE using linear and non-linear modeling in the light of existing models. Secondarily, we sought to explore relationships between PA and postulated means of behavioral (time sedentary) and physiologic (i.e. Immune, reproductive) compensation. We measured TEE in 57 healthy weight stable adults (18 to 58 yrs., F = 28) who ranged from being sedentary to ultra-endurance trained runners (0 to 78 mi/wk.) using the doubly labeled water technique and PA and sedentary time using a waist mounted triaxial accelerometer during the same 14-day period. We obtained fasting serum (albumin, cortisol, TNFα, C-reactive protein, free testosterone, TSH and T3), plasma (leptin) and whole blood (WBC with differential) concentrations. Using linear and non-linear modeling, we observed a positive linear relationship between PA (Vector Magnitude Counts per Minute ) and TEE (R2=0.313, Y = 1.427*X + 1930 and adjusted for fat free mass (FFM) R2=0.363, Y = 1.151*X + 2155). We identified no association between PA and RMR ( R2=0.015 and adjusted for FFM R2=0.010). In addition, we observed an association between higher PA and lower % time sedentary (R2=0.723). Although inconsistent, there was a general trend for higher PA but not TEE or its components to be associated with lower immune and reproductive biomarkers. These findings support a conventional linear model though intervention studies will be needed to further address this issue. / Doctor of Philosophy / The health benefits of being physically active are well known. At the same time there is much that is not understood about the relationship between physical activity and how much energy we spend in a day (total energy expenditure). It has been assumed for a long time that the amount of energy we spend is a simple matter of adding the calories burned at rest, digesting food, and exercising and as we exercise more we continue to add an equal number of calories to the daily budget. We call this the linear or additive model – energy spent increases in a straight line as physical activity increases. Because we have techniques for measuring total energy expenditure in people going about their usual lives that were not widely available until recently due to cost, scientists have developed new ideas about how increases in physical activity affect total energy expenditure. The constrained model suggests that there is a cap on how many calories we can burn in a day and that our bodies will save energy in other parts of the budget if our physical activity remains high enough to reach or exceed that cap. The second idea is called the compensated model like the constrained model predicts that the rate we spend energy slows down as we exercise more because the body has saved energy in other parts of the budget (compensation). Researchers don't know for sure if either of these models are correct, so we conducted a study to determine how physical activity and total energy expenditure are related and if our findings agree with either of these models. We were also interested in determining how physical activity is related to energy spent at rest (resting metabolic rate ) and energy spent being active (physical activity energy expenditure). Finally, we wanted to determine ways that the body might compensate. One way is to spend more time sedentary. Another way is to save energy on less urgent needs like the immune and reproductive systems. Our main goal was to create an equation that explain how higher levels of physical activity are related to total energy expenditure and other parts of the energy budget (RMR and physical activity energy expenditure). We also created equations that explain how physical activity is related to sedentary behavior and immune and reproductive markers in the blood. We recruited 57 male and female volunteers that represent a wide range of physical activity levels – from sedentary to ultra-endurance trained runners who routinely run as much as 80 miles per week. We measured the energy they spent and physical activity over 2 weeks. In our sample, we found that physical activity was related to total energy expenditure and physical activity energy expenditure in a linear way. We did not find a cap on the amount of energy spent (constraint). We found that participants who exercised more spent less time sedentary not more meaning that we did not find behavioral compensation. It is possible that there was compensation from the immune system because some of the markers of immune function were lower in people who were more physically active, but it was not consistent in all of the blood markers. A larger study using an exercise intervention is needed to assign causation to the correlation we found.
25

GPS Watches for Measuring Energy Expenditure during Physical Activity

Hongu, Nobuko, Wise, Jamie M., Orr, Barron J., Wisneski, Kristin D. 10 1900 (has links)
4 pp. / Recently, a number of global positioning system (GPS) devices have been introduced commercially which exploit GPS, transforming frequent measurements of time and location, into an estimate of energy expenditure. This fact sheet reviews how GPS watches (GPS fitness units) measure energy expenditure of individual during physical activity. We list popular GPS watches that are on the market and showed pros and cons of these watches. After our field testing, we decided that Garmin Forenunner 305 is our best pick for the GPS watch. We included information on Geocashing, which is one of popular outdoor activities using GPS receiver or other navigational techniques.
26

The influence of energy expenditure, sex and eating behaviours on energy intake and appetite in young adolescents

Varley, Joanna Louise January 2014 (has links)
Current physical activity recommendations are being met by less than 21 % of children between 5-15 y. Recent Government initiatives are aiming to increase children’s participation in exercise. However, the effects on an imposed bout of exercise-induced energy expenditure (EE) on energy intake (EI) and appetite (hunger, fullness and prospective consumption) in normal weight children have received a limited research focus to date. Therefore, this thesis aimed to investigate how an imposed bout of exercise-induced energy expenditure (EE) on energy intake (EI) and appetite in normal weight children The first study investigated whether 17 habitually active girls were able to accurately increase their EI to match the EE following 60 min moderate intensity walking exercise. On average 17% of the EE was compensated for by an increase in EI. However, the ranged for EI change was -160% to +166% indicating large individual responses. The second study investigated whether 30 min of maximal sprint intermittent sprint cycling exercise would significantly alter EI or appetite in 13 boys and 13 girls. In the boys, hunger and prospective consumption were suppressed whilst fullness increased immediately following the exercise, whilst EI was significantly increased in response to the exercise condition. No significant changes to appetite or EI were observed in the girls. The third study investigated whether a mid-morning snack, moderate intensity cycling exercise (energy matched to snack) or both would alter EI or appetite in 20 boys and 18 girls. Irrespective of sex, hunger and prospective consumption were suppressed whilst fullness increased following the mid-morning snack, however this change in appetite did not alter EI as no significant differences were found between conditions. The fourth study investigated whether 99 recreational sports players (males/females, adults/children) were able to conceptualise their EE following 1 h habitual training into quantifiable amounts of food (chocolate) or drink (sports drink). Only 36 % of the EE from the exercise was met by the estimated amounts of food or drink. Age, sex nor sports participation significantly altered the participants’ accuracy of estimation. The fifth study investigated whether sex or dietary restraint impacted brain activation responses to visual food stimuli in 15 boys and 14 girls between a fed and fasted condition. Significant differences in brain activation were found between conditions, sexes and dietary restraint, potentially suggesting the differences observed in the previous experimental studies could be attributed to neurological alterations between participants. In conclusion, the findings presented demonstrate the changes in EI between young adolescents in response to an imposed bout of exercise are extremely variable. Whilst eating behaviours failed to correspond to the EI differences observed between participants, potentially brain activation differences may be responsible. The sex of the participant is more likely to impact EI and appetite following maximal sprint intensity exercise, more so than a bout of moderate intensity exercise. Future research should focus on determining what underpins the variable change in EI between participants following a bout of exercise.
27

Nutrient absorption and energy expenditure in growing pigs fed high-fiber diets supplemented with enzymes

Agyekum, Atta Kofi January 2016 (has links)
Fiber-rich (HF) diets are typically supplemented with enzymes to improve their nutritive value and to offset their negative effects on pig growth. However, studies on enzyme effect in pigs have yielded inconsistent results on nutrient digestibility and growth. Although the inconsistencies observed could be explained by differences in substrate and experimental conditions and enzyme characteristics among studies, how enzymes influence metabolic and physiological responses in pigs is still not clear. Therefore, three experiments were conducted, using 3 dietary treatments (control, HF and HF diet supplemented with enzymes), to elucidate the effects of supplementing an HF diet with enzymes in growing pigs. Experiment one investigated HF and enzyme supplementation on energy and nutrient digestibility, digesta volatile fatty acid (VFA) concentrations, and gut microbial profile in pigs. Compared with the HF diet, enzymes improved dry matter, starch, energy and some amino acid (AA), but not nitrogen digestibility. Further, the enzymes stimulated the growth of gut bacterial groups, which have xylanolytic and cellulolytic properties in the HF-fed pigs, but enzymes did not influence digesta VFA concentration or fiber fermentation. Experiment 2 evaluated the effects of enzyme supplementation on growth performance, glucose uptake in jejunum tissue samples mounted in Ussing chambers, and intestinal nutrient transporter mRNA levels in pigs. Diet had no effect on feed intake and jejunal glucose uptake. The enzymes influenced nutrient transporter mRNA levels but did not improve pig growth rate and feed efficiency relative to the HF diet. The third experiment investigated the effect of supplementing the HF diet with enzymes on postprandial portal vein-drained viscera (PDV) nutrient fluxes and energy expenditure (measured as O2 consumption) by the PDV and whole-animal in pigs. Diet had no effect on energy expenditure. The HF diet reduced portal glucose, VFA and essential AA absorption and insulin production. Enzyme supplementation improved portal glucose and VFA absorption, but not essential AA absorption and insulin production. Overall, improvements in nutrient utilization due to enzyme supplementation did not improve the growth rate of pigs, which appears to be due to the lack of enzyme effect on essential AA and energy use by the PDV and insulin production / October 2016
28

Energetický výdej a utilizace nutričních substrátů u pacientů se sepsí v průběhu hospitalizace na JIP / Energy expenditure and utilization of nutritive substrates in septic patients during hospitalization in ICU

Hladová, Eliška January 2014 (has links)
The aim of this work were examinations of septic patiens to determinate energy expenditure and the utilization of nutritional substrates and to compare results of examinations to standart recommendations of ESPEN for patient's nutrition. For investigations was used indirect calorimetry. Our group of septic patients consisted of three men and three women from 58 to 73 years old. The lenght of the hospital stay was different, so the group was heterogenous and each patient was in different phase of sepsis. Five of six patients were in hypermetabolism. The value of energy expenditure was from 87,3 % to 176,2 %. Average energy expenditure was 1790,3 ± 414,9 kcal/ kg/ day and average energy of nutrition was 2080,2 ± 754,7kcal/ kg/ day. As for nutritional substrates, average income of carbohydrates was 257,9 ± 109,9 g/ den. Average utilization of carbohydrates was 83,9 ± 62,1 g/ day. So the intake of carbohydrates were significantly higher, than the utilization. Average income of lipids was 63,6 ± 15,7 g/ day and average utilization was 102,1 ± 61,8 g/ day. There was also significant diference between lipid utilization and lipid intake. Average income of proteins was 127,4 ± 61,7 g/ day. Average utilization of proteins was 132,5 ± 53,6 g/ day. To conclusion, the results of examinations, measured by...
29

Klidový energetický výdej u polytraumatických pacientů. / Resting energy expenditure at polytraumatic patients.

Šimandl, Ondřej January 2013 (has links)
The aim of this study was to determine and evaluate resting energy expenditure (REE) and the utilization of nutritional substrates in 14 polytrauma patients in the ICU. Was also assessed level of impact Overhydration (OH) on the accuracy of the determination. Diagnostic investigations using indirect calorimetry (IC) was performed in 9 men and 5 women (age 30 ± 15 years, BMI 27.5 ± 9.4 kg·m-2) with polytrauma (ISS 41 ± 16). For more accurate sizing of REE and extent of utilization of nutritional substrates were used equations derived from the equation of Weir, not Softwear calorimeter. Using IC volumes were determined only inspired an expired oxygen and carbon dioxide. To determine the rate of OH was used bioimpedance analysis methods using BCM. Almost 86% (8 men and 4 women) examined patients showed hypermetabolism. Average REE value was 2241.38 ± 854.27 kcal·day-1, which represented an average increase of prediction of 38.09 ± 49.09% due to the physiological condition. A statistically significant relationship was demonstrated between REE determined using the Weir equation according and the Harris-Bennedict equation without (P = 0,01) with deduction of OH (P = 0,007) only in men. In clinical practice, significant correlations were established between the REE-IC and BSA (P < 0,01), LTM (P < 0,05),...
30

Regulation of energy expenditure by mitochondrial dynamics in brown adipose tissue from subcellular to whole body level

Mahdaviani, Kiana 15 June 2016 (has links)
Obesity is a disorder of energy imbalance in which energy intake exceeds energy expenditure (EEX). Brown adipose tissue (BAT) is unique in that it can increase whole body EEX when it is adrenergically activated. The thermogenic capacity of BAT is mediated by mitochondrial uncoupling through the activation of Uncoupling Protein 1 which uncouple respiration from ATP production. Mitochondria is a dynamic organelle that undergo continuous cycles of fusion and fission. Alteration in mitochondrial dynamics correlates with changes in energy efficiency in different cell types; however, its role in regulating EEX in BAT has not been investigated. Here we describe that mitochondrial dynamics is a physiological regulator of adrenergically-induced changes in EEX in BAT. Norepinephrine (NE) induces mitochondrial fragmentation in brown adipocytes (BA) though posttranslational modifications - phosphorylation and proteolytic cleavage -of mitochondrial dynamic proteins. NE-induced EEX is reduced in fission-deficient brown adipocytes while forced mitochondrial fragmentation increases the respiration in response to exogenous free fatty acids (FFAs) indicating increase in EEX. We further investigated whether forced mitochondrial fragmentation in BAT could be utilized as an approach to increase whole body EEX is response to FFA in vivo. We found that a mouse model with forced mitochondrial fragmentation in BAT (BAT-Mitofusin2-KO) gained less body weight and less fat mass and remained more glucose tolerant and insulin sensitive under high fat diet (HFD) compared to the wild type. Additionally, FFA oxidation was enhanced in BAT-Mitofusin2-KO mice indicated by lower respiratory exchange ratio. We also found that subcellular heterogeneity in dynamics leads to the generation of subpopulations of mitochondria with diverse bioenergetics characteristics within the same cell. We described that a subpopulation of mitochondria surrounding the lipid droplet in BA had higher ATP synthesis capacity, supported by higher ATP synthase protein expression and elongated morphology. We suggest that this subpopulation of mitochondria is responsible for addressing the ATP demand of the BA when it is not activated. In conclusion, changes to mitochondrial dynamics are required for BAT thermogenic activity and for the control of EEX efficiency from sub-cellular to the whole body level. Additionally, mitochondrial dynamics in BAT can regulate fatty acid oxidation. / 2018-06-15T00:00:00Z

Page generated in 0.0636 seconds