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  • 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.
41

Pipelined Forwarding with Energy Balance in Cluster-based Wireless Sensor Networks

Shang, Yao-Yung 16 August 2011 (has links)
Wireless Sensor Network (WSN) is composed of sink and sensors. Sensors transmit data to sink through wireless network after collecting data. Because multi-hop routing and forwarding may be required on WSN, sensors closer to sink will consume more energy than other nodes due to hop-by-hop forwarding. In this Thesis, we propose pipelined forwarding for cluster-based WSN to solve these problems. First, we divide a WSN into several clusters such that the distance between sensors and sink is reduced and packet transmission delay can be decreased. However, since reducing the distance can increase the number of clusters significantly, multiple mobile sinks are embedded in the system to increase overall throughput. Second, we change the direction of pipelined forwarding to avoid from running out of energy of some sensors. We derive mathematical equations to analyze and validate the proposed scheme. From the analytical results, we prove that the proposed scheme can decrease packet transmission delay. The results also show that system throughput can be improved by increasing the length of pipeline and the number of mobile sinks. Finally, we demonstrate that the proposed scheme can increase energy throughput more efficiently than conventional non-pipelined forwarding scheme.
42

THEORETICAL STUDY TO IMPROVE THE ENERGY BALANCE IN WASTEWATER TREATMENT PLANT : Investigation of microalgae photobioreactor in biological treatment step and open algal pond in reject water treatment in Uppsala and Västerås

Marcin, Richard, Mucha, Matej January 2015 (has links)
The self-treatment system of nature cannot handle man-caused high rate water pollution on its own, therefore cleaning in wastewater treatment plant (WWTP) is necessary to avoid eutrophication – excessive enrichment of nature by nutrients. Current technologies applied in WWTPs are old, outdating and highly energy demanding, especially biological treatment step generally requires large amount of energy for aeration of water. The alternative to current system could be microalgae treatment step, which would use green algae to consume pollutants present in the waste water, namely nitrogen, phosphorus and heavy metals. Via photosynthesis it could produce oxygen required for biological oxidation of organic matter. Furthermore carbon source is necessary for microalgal growth, this can be added to the water as CO2 produced in other industries and so decrease global greenhouse gas footprint. Co-digestion of microalgae with undigested wastewater sludge under mesophilic conditions can give a synergic effect for biogas production, therefore harvested and co-digested microalgae could contribute to positive energy balance of WWTP. Full-scale microalgae cultivation in WWTP can be achieved only when good grow is guaranteed. This is a result of many factors, particularly access to nutrients, light condition, water temperature, and pH. The goal of master’s thesis was to understand and evaluate main factors influencing algal growth using literature review, propose design of microalgae treatment step with artificial lights and evaluate energy balance, of wastewater treatment plants in Uppsala and Västerås with new design. The work proposed two different designs of microalgae treatment steps, modelled in Excel and applied to current state of municipal WWTP in Västerås and Uppsala with belonging satellite plants. The first design of microalgae activated photobioreactor (MAASPBR) aimed to replace current biological treatment step. This is possible in Västerås and Uppsala WWTPs if microalgae can consume 75% of total nitrogen (Ntot) and produce at least 13.5 and 2.4 tonne O2/day in Västerås and Uppsala respectively. The sensitivity analysis showed that minimal volumetric algal yield of 0.15 kg/m3 ,day and 0.25 kg/m3 ,day is required for Västerås and Uppsala respectively, when oxygen production rate of 1.92 kg O2/kg microalgae is assumed. Furthermore harvested and co-digested algae with sewage sludge contributes to significant increase of biogas production and negligible transportation energy increase. The second design of open algal pond for reject water (OAPRW) aims to cultivate microalgae on reject water with high concentration of nutrients, generated in sludge centrifuge. The model assumed high algal growth due to excessive amount of nutrients and increased water temperature to 24°C. Results show a possible 23% and 20% electricity saving on blowers in the biological treatment in Västerås and Uppsala respectively. Both models have positive impact on energy balance in all WWTPs, however MAASPBR has greater uncertainties, because this type of photobioreactor has not been tested unlike OAPRW which has been tested in pilot plant scale.
43

Energy balance and breast cancer : mechanistic studies

Nogueira, Leticia Maciel 07 January 2011 (has links)
Obesity is one the few modifiable risk factors for breast cancer. Hence, an evaluation of the metabolic and cancer inhibitory effects of the obesity reversing strategies, calorie restriction (CR) and exercise, is important for breast cancer prevention. Additionally, a better understanding of the mechanisms underlying the effects of these interventions on cancer will provide scientific basis for therapeutic recommendations, and facilitate the identification of therapeutic agents for breast cancer treatment in obese patients. We found that CR is more effective than exercise in reversing the metabolic and cancer enhancing effects of obesity. Even at comparable levels of adiposity, CR effects on insulin resistance, energy balance related hormones levels, and metabolic genes expression in adipose tissue were more profound than those of exercise. The mechanism by which CR influences tumor progression is thought to involve molecules that respond to energy balance changes and control cell growth, such as the insulin-like growth factor-1 (IGF-1) and the mammalian target of rapamycin (mTOR). The mTOR inhibitor rapamycin decreased mammary tumor burden to levels comparable to CR. While established tumors did not display decreased mTOR activity, constitutively active mTOR was capable of overcoming some of the inhibitory effects of CR on tumor cells invasion and migration. Effects of increasing levels of CR on gene expression indicate that 30% and 40% CR, but not 20% CR, induce beneficial metabolic changes in the liver. However, 40% CR also increases apoptosis of hepatic cells which appears to be detrimental for the liver. IGF-1 infusion partially overcame the beneficial effects of CR on expression of tumor-related genes in the mammary fat pad and on mammary tumor growth. Taken together, our data show that CR, but not exercise, is able to reverse the metabolic and tumorigenic effects of obesity. Furthermore, the IGF-1 and mTOR pathways may mediate, at least in part, many of the beneficial effects of CR on metabolism and tumor progression. / text
44

Energy balance, inflammation, and tumor progression : the role of NF-[kappa]B

Harvey, Alison Elise 16 June 2011 (has links)
Obesity is an established risk and progression factor for many types of cancer, including pancreatic and colon cancer, and is characterized by abnormal metabolic hormone production and a chronic low-grade state of inflammation. However, the links between obesity, hormones, inflammation and tumorigenesis in colon and pancreatic tissue are poorly understood. Calorie restriction (CR), an anti-obesity dietary regimen with potent anticancer effects, reduces serum metabolic hormones and protumorigenic cytokines. Insulin-like growth factor (IGF)-1 is a metabolic hormone that activates NF-[kappa]B, a key regulator of inflammation. NF-[kappa]B is a transcription factor that mediates transcription of many cancer- and inflammation-related genes and is upregulated in both colon and pancreatic cancer. We hypothesized that CR inhibits colon and pancreatic tumor cell growth through modulation of hormone-stimulated NF-[kappa]B activation and protumorigenic gene expression. To test this hypothesis, we used CR and ad libitum feeding to generate a lean and overweight (control) phenotype, respectively; in C57BL/6 mice transplanted with MC38 colon cancer cells or Panc 02 pancreatic cancer cells, and analyzed the effect of diet on circulating hormone levels, markers of inflammation, and tumor growth. We also investigated the in vitro effects of IGF-1 on NF-[kappa]B activation and downstream protumorigenic gene expression in MC38 and Panc 02 cells. CR, relative to control diet, reduced body weight, circulating IGF-1 levels, and transplanted MC38 and Panc 02 tumor growth, as well as protumorigenic gene expression in the MC38 and Panc 02 tumor microenvironment. IGF-1 increased cell viability, NF-[kappa]B nuclear translocation and DNA binding, transcriptional activation, and downstream gene expression of inflammation and other protumorigenic genes in MC38 colon cancer cells and Panc 02 pancreatic cancer cells in vitro. Knockdown studies of NF-[kappa]B in Panc 02 cells using si-RNA established that the IGF-1-induced increase in protumorigenic gene expression is mediated, at least partially, through an NF-[kappa]B-dependent mechanism. In conclusion, these findings in models of pancreatic and colon cancer help clarify the links between obesity, IGF-1, NF-[kappa]B-mediated inflammation, and cancer. This work provides the underpinnings for several new molecular targets and strategies to test in model systems and translational studies for preventing or controlling obesity-related cancer. / text
45

Meteorological differences between Rabots glaciär and Storglaciären and its impact on ablation

Eriksson, Pia January 2014 (has links)
In the Kebnekaise Massif, Northern Sweden, the west facing glacier, Rabots glaciär, is loosing volume at a significantly higher rate than east facing, Storglaciären. By analyzing data from automatic weather stations situated on the ablation area on the glaciers we investigated the effect of meteorological differences on ablation. There was a difference in micro-climate between Rabots glaciär and Storglaciären. Generally Storglaciären had slightly warmer and drier air, had less or a thinner cloud layer but more precipitation. On both glaciers a glacier wind is dominant but high wind velocities were common especially on Storglaciären indicating a larger influence from the synoptic system. There was a good correlation for temperature and vapor pressure between the glaciers that indicate that both glaciers are strongly affected by the synoptic system. The meteorological parameters have similar effect on the ablation on the glaciers. Temperature, vapor pressure and the turbulent heat fluxes are the only meteorological parameters that suggest a linear affect on ablation. Net shortwave radiation contribute with the greatest amount of energy for ablation but decreased in relative importance as the temperature increased. Shortwave radiation, sensible and latent heat contributed with a total 184Wm-2 on Rabots glaciär and 222Wm-2 on Storglaciären. Rabots glaciär seem to have a significantly greater relative importance of the turbulent heat fluxes than Storglaciären. Although the differences in micro-climate were not great, using the ablation for Storglaciären to estimate ablation on Rabots glaciär would over estimate the ablation with 0.5m w.e..
46

Effects of Conjugated Linoleic Acid on Lipid Metabolism and Energy Balance in Dairy Cows

Kay, Jane Kirrily January 2006 (has links)
Three experiments were conducted for this dissertation with the goals to; 1) determine conjugated linoleic acid (CLA) effects on net-energy balance (EBAL) and milk production parameters during periods of nutrient/energy stress, and 2) investigate temporal CLA effects on mammary lipogenic gene expression. Study one was designed to determine if abomasal CLA infusion could reduce milk fat synthesis and partition nutrients towards alternative milk components in feed restricted rotationally grazed dairy cows. Data indicate abomasally-infusing CLA reduced milk fat synthesis in nutrient restricted grazing dairy cows and improved calculated EBAL and milk protein production. Another period of transitory stress experienced by the lactating dairy cow is immediately postpartum and study two objectives were to feed rumen inert-CLA to evoke milk fat depression (MFD) and investigate production and bioenergetic parameters. Data indicated a high CLA dose (3 x greater than needed in established lactation) inhibited milk fat synthesis immediately postpartum and improved calculated EBAL in grazing dairy cows. A curvilinear relationship existed between the severity of CLA-induced MFD and milk yield response. Moderate CLA-induced MFD (<~35%) tended to increase milk yield whereas severe MFD (>~35%) diminished this response. Previous research speculated that extensive MFD might decrease Δ⁹-desaturase (stearoyl CoA desaturase; SCD) and subsequent membrane fluidity to such an extent as to adversely affect cellular functions and inhibit milk secretion, thus decreasing milk yield. However, SCD inhibition was temporally independent in the present study, offering little support for the aforementioned theory. Mammary sensitivity to CLA increased as lactation progressed and previous speculations attributed this to reduced contribution of de novo synthesised fatty acids or increased competition from circulating non-esterified fatty acids immediately postpartum. However, data indicate that de novo fatty acids and milk fat trans-10, cis-12 CLA content don’t appreciably change during early lactation, (even though MFD became more severe) offering little support for either hypothesis. Study three investigated the effects of intravenous CLA infusion on temporal expression of mammary lipogenic genes to determine if trans-10, cis-12 CLA down regulates expression of a key gene (i.e. acetyl CoA carboxylase, ACC, the rate limiting enzyme in de novo fatty acid synthesis) and reduction in other mammary lipid synthesis genes is due to lack of substrate (i.e. malonyl CoA), or an alternative indirect mechanism. Data indicated however, that mammary lipogenic genes (ACC, fatty acid synthetase and SCD) followed a similar temporal pattern, providing more support for a global regulator (i.e. sterol regulatory element binding protein-1, peroxisome proliferator-activated receptor-γ or nuclear factor- κB) rather than a specific key enzyme effect.
47

RECONSTRUCTION OF HIGH ARCTIC WINTER SURFACE ENERGY FLUXES

Pike-Thackray, Colin 05 August 2011 (has links)
Throughout the late 20th and early 21st century, the global temperature has been on the rise, a process that has been accelerated in the Arctic. The Arctic surface temperatures have risen at a factor of 3 greater rate than the global average, leading to the term Arctic Amplification of climate change. In this study, the enhanced warming of the Arctic, and the enhancement at the Arctic surface in comparison to the warming of the atmosphere aloft, is investigated through a reconstruction of the past surface energy balance by a model driven by downwelling irradiance reconstructed using radiosonde profiles and the radiative transfer code SBDART. The downwelling irradiance is shown to be increasing over the time-period of 1994-2009, and the sources of this increase are diagnosed. The time-evolution of the surface flux terms are discussed, and the sensitivity of the surface temperature to changes in atmospheric temperature is investigated.
48

Eating Frequency, Within-Day Energy Balance, And Adiposity In Free-Living Adults Consuming Self-Selected Diets

Shaw, Ayla C 23 March 2015 (has links)
Background: The relationship between eating frequency (EF) and adiposity is surrounded by controversy. Numerous cross-sectional studies have been performed on the subject, yet the results are mixed. While some of these studies show an inverse relationship between EF and adiposity, this is likely due to underreporting of EF and total energy intake when diets are self-reported. In studies where underreporting was taken into account, EF is positively associated with both energy intake and adiposity. Intervention trials have failed to show a significant effect of EF on energy intake or weight change, but only a small number exist. Objective: In this study, we examined associations among EF, energy intake, and adiposity in free living adults consuming self-selected diets. In conducting this analysis, two common methodological problems in this research area were addressed: 1) the lack of consideration of energy balance fluctuations throughout the day, and 2) a tendency not to account for implausible reporting of energy intake. We hypothesized that individuals with higher EF would have higher BMI, percentage body fat, and energy intake. Additionally individuals with greater fluctuations in energy balance will have higher BMI, percentage body fat, and EF. Methods: We performed a secondary analysis of data collected as part of a previous study in our laboratory on diet and energy regulation (unpublished). One hundred and twenty-six participants were enrolled (62.4 % female, and 75.2% Caucasian), and one participant dropped the study due to pregnancy. Mean ±SD age, BMI, and percentage body fat of the remaining 125 participants were 29.8 ±12.2 years, 24.5±3.9 kg/m2, and 27.8±9.8% respectively. We analyzed one day of dietary intake collected using a multiple pass 24 hour recall. Energy intake was calculated by NDS (Nutrition Data System for Research, version 2011 (n=36) and version 2010 (n=89)). An eating occasion was defined as any occurrence of energy intake > 0 kcal separated by at least 1 hour. EF was defined as the number of eating occasions per day. A specifically designed spreadsheet that generates within-day energy balance was used to produce estimates of hourly energy balance. We also used total energy expenditure measured by doubly labeled water and the Huang et al. (2005)1 method to identify implausible reporters (cutoff for plausibility was reported energy intake (REI) within ±16.8% of TEE) and conducted Pearson’s correlations and regression analysis in both the total sample and a subsample in which implausible energy intake reporters were excluded from analysis. Results: We identified 59.2% of the sample as implausible reporters (n=74; 47 under-reported and 27 over-reported). Mean ±SD EF and energy intake were 4.7±1.5 and 2356±964 kcal in the total sample and 4.8±1.6 and 2371±689 kcal in the plausible sample. In the total sample EF was positively correlated to energy intake among women (r=0.244, p=0.032). No other significant relationships were observed between EF and either energy intake, BMI, or percentage body fat, in the total or plausible sample. In the total sample, maximum energy deficit > 400 kcal in a 24 hours period was significantly and positively correlated with percentage body fat (r=0.211,p=0.019) and negatively correlated with EF (r=-0.243, p=0.007) when controlling for sex and age. Separating the sample by sex we observed significant positive correlation between percentage body fat and maximum energy deficit in men (r=0.382, p=0.009) but not in women. No significant relationships between fluctuations in energy balance and percentage body fat were observed in the plausible sample. Conclusion: No evidence was found to suggest a relationship between EF and adiposity. The significant positive relationships observed between maximum energy deficit and adiposity in the total sample are consistent with previous findings. The number of implausible reporters identified in our analysis supports that over and under-reporting is a major issue associated with self-reporting of dietary intake.
49

The Relationships Between Real Time Energy Balance, Hunger, and Body Composition

Delk, Ashley 09 July 2014 (has links)
The Relationships Between Real Time Energy Balance, Hunger, and Body Composition Delk A, Benardot D, Nucci A, & Thompson WR. Georgia State University Introduction: Previous research has indicated that hunger is associated with the quantity, volume, and macronutrient composition of food intake. Hunger has never been assessed from the viewpoint of real time energy balance, although there is limited research on hunger and eating frequency. Purpose: The purpose of this study was to evaluate the relationships between real time energy balance, hunger, and body composition in college students between the ages of 18-30. Methods: Participants were assessed for body composition using a Tanita scale and energy balance was determined on an hourly basis using NutriTiming® software. A hunger scale was used to assess participant hunger every hour. Results: There is a statistically significant relationship for the entire population between energy balance average and body fat percent (R= -0.376; P=0.037). Hours spent in energy deficient is positively associated with body fat percent (R=0.467; P=0.008), while hours spent in an optimal energy balance is negatively associated with body fat percent (R= -0.465; P=0.009). Hours spent in an energy balance surplus (+400 kcals) were not significantly associated with body fat percent. However, hours spent in an anabolic state (>0 kcals) was negatively associated with body fat percent (R=-.457; P=.010). Conversely, hours spent in a catabolic state (<0 kcals) were positively associated with body fat percent (R=.457; P=0.10). Using linear regression analysis with body fat percentage as the dependent variables and age, height, weight, gender, and hours in optimal energy balance, we determined that we could predict a large amount of variance in body fat percentage (R= .931; P= <.001). The only time during the day that there was a significant correlation between body fat percent and hunger was at 5pm (R= -0.391, P = 0.029). Conclusions: These data suggest that that the more time spent in energy deficit is associated with a higher body fat percent. This should encourage college students between the age of 18-30 to avoid restrictive eating patterns and strive to maintain optimal energy balance in order to achieve a low body fat percent.
50

Physico-chemical and shelf-life between baked and extruded pet foods

Gibson, Michael W. January 1900 (has links)
Master of Science / Grain Science and Industry / Sajid Alavi / The U.S. pet food market was approximately worth $22 billion in 2013. Further growth is predicted at a pace faster than most major human food product categories. More than 60% of pet food products are processed using extrusion, and a significant proportion is produced using baking. However, research is lacking on fundamental process and product differences between extrusion and baking. The current study focuses on this aspect and also in-depth characterization of process and product quality. Three iso-nutritional diets were formulated for dry expanded dog food using 0%, 7% and 15% fresh meat inclusion. Major variations between diets were inclusion rates of mechanically deboned chicken, cereal grains, and poultry fat. Each diet was processed with a single screw extruder using various thermal and/or mechanical energy inputs (obtained by varying pre-conditioner stem injection and/or extruder screw speeds). Diets were also processed by baking using a 30 foot experimental oven at 425°F, although the fresh meat inclusion was at 0%, 10% and 20% levels. Proximate analysis of products was conducted. Products were also characterized for physico-chemical properties such as bulk density, piece density, expansion ratio, degree of gelatinization and textural attributes. As fresh meat inclusion increased (0–15%), expansion ratio (4.1–3.5) decreased irrespective of extrusion treatment. Expansion was not evident in the baked kibbles, and bulk and piece densities were up to 56% higher for baked versus extruded kibbles. Textural analysis of extruded kibbles revealed serrated force-deformation response, typical of cellular products, with peak hardness of 2.9–1.5 kgf. On the other hand, baked products had a ‘smooth’ force-deformation response with higher peak hardness than extruded products (up to 3 kgf). Microbial counts for baked products were higher than extruded products, and rancidity profiles as obtained from gas chromatography also had marked differences. The extrusion process was characterized by detailed mass and energy balance analyses, and compared with baking that lacks mechanical energy input. Results from this study provide a useful bench-mark for dry expanded pet food product quality and commonly used processing technologies.

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