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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.
541

Effect of consuming ground beef of differing monounsaturated fatty acid content on atherosclerotic cardiovascular disease risk factors in healthy men

Cao, Xiaojuan 15 May 2009 (has links)
Atherosclerotic cardiovascular disease (ASCVD) is currently the most common cause of death in the United States. Some dietary factors contribute importantly to ASCVD and other factors can reduce risk of ASCVD. Oleic acid is a monounsaturated fatty acid (MUFA). Dietary patterns in which oleic acid contributes to a majority of dietary fatty acids are associated with reduced ASCVD risk. These beneficial effects are due to MUFA-induced lipoprotein profile changes such as decreases in low density lipoprotein (LDL) and increases in high density lipoprotein (HDL). LDL oxidation plays a central role in atherosclerosis development as it both initiates and propagates atherosclerosis. HDL is anti-atherogenic as it can attenuate LDL oxidation. HDLs are a class of diverse lipoprotein that varies in protein and enzymatic composition. The paraoxonase (PON) family of enzymes, especially PON1, is primarily expressed in the liver; PON activity in the circulatory system is associated with HDL. Both PON and HDL have been documented to be anti-atherogenic. Other factors such as homocysteine and C-reactive protein (CRP) can also be considered risk factors for ASCVD. However, studies of risk factors in healthy men who consume ground beef with a different content of MUFA are lacking; hence, no conclusive evidence has established whether consuming a high amount of MUFA in the form of ground beef alters the development of atherosclerosis. The overall purpose of this study was to investigate whether the provision of ground beef with a fractionally higher MUFA content could lower or improve several ASCVD risk factors in men who consume ground beef. These risk factors include the metabolic indices of glucose, insulin and homeostasis model assessment (HOMA), inflammation risk factors of CRP and homocysteine and anti-risk factor of paraoxonase. The concentration of homocysteine was determined spectrophotometrically following separation by high pressure liquid chromatography (HPLC). Enzyme-linked imminosorbent assay kits that measured the CRP and insulin concentration in plasma. The significance of the results was determined by subjecting the data to ANOVA using the general linear model for repeated measurement (P<0.05). From this study, it can be concluded that MUFA has a beneficial effect of lowering risks as determined by metabolic indices and lipoprotein profile. Moreover, our study showed that different concentrations of MUFA in ground beef has no effect on PON1 activity, but that increased beef consumption generally reduces PON1 in association with increases in homocysteine concentration while improving indicators of glucose tolerance.
542

Diversity,distribution, and abundance of ground dwelling spiders at Lick Creek Park, College Station, Texas

Henderson, Takesha Yvonne 02 June 2009 (has links)
Lick Creek Park is a 515 acre nature park that was acquired in 1987 by the City of College Station, Texas. The site has a variety of indigenous plant and animal species and is an important natural resource for citizens of the region. There is a long-term commitment to inventory this natural park to monitor the changes as our urban community expands to surround the park. There are 989 species of spiders currently recorded from Texas and 332 of them are known to occur in Brazos County. My focus was on improving the ground spider inventory at Lick Creek Park. Spider collections were made using 18 regularly-sampled pitfall traps distributed evenly among three habitats. Spiders from 24 families, 66 genera, and 111 species were identified from 918 specimens, including 627 immature and 291 adult spiders, captured in pitfall traps from April 2005-April 2006. Of the 111 species found, 45 were represented by one specimen only and 20 were represented by two specimens. Rarefaction analyses indicated that the majority of spider species were readily detectable using pitfall traps and inventoried during this study (111 found and 168 estimated to be present). Simpson’s Diversity measure bootstrap estimates determined species diversity overall to be very diverse (0.966), as did a Shannon Weiner Diversity bootstrap estimate (5.483). Also, Simpson’s measure of species evenness (0.264) indicated a low species evenness. Those species found in only one habitat comprised 50% of the total species, and their densities ranged from 1-5 individuals. Those species found in just two habitats comprised 25% of the total species, and their densities ranged from 2-21 individuals. Species found in all three habitats comprised the remaining 25%, and their densities ranged from 4-53 individuals found. Most species occurred at low densities in this study and this often precluded conducting more detailed analyses. Additional sampling is expected to, first, detect known species occurring in previously unrecorded habitats and, second, to detect species not previously found in the park. This inventory of spiders at Lick Creek will provide a basis for further studies on biodiversity and the assessment of human impact on the environment.
543

High-Oleic Ground Beef, Exercise, and Risk Factors for Cardiovascular Disease in Men and Postmenopausal Women

Gilmore, Linda Anne 2010 December 1900 (has links)
Sixty-six percent of the ground beef consumed in the U.S. contains 16-30 percent fat by weight, and at the retail level, ground beef fat varies widely with regards to saturated, monounsaturated and trans-fatty acid content. Through two independent studies the effect of fatty acid composition of ground beef on selected cardiovascular disease risk indicators was evaluated. In the first study, 27 free-living normocholesterolemic men completed a three-way crossover dietary intervention. Subjects consumed five, 114-g ground beef patties per week for 5 wk with intervening 4-wk washout periods. Patties contained 24 percent total fat with monounsaturated fatty acid:saturated fatty acid (MUFA:SFA) of either 0.71 (low-MUFA, pasture-fed), 0.83 (mid-MUFA, short-term corn-fed), or 1.10 (high-MUFA, long-term corn-fed). Blood was collected from each subject before and at the end of each diet period. Overall, the ground beef interventions decreased plasma insulin, HDL2, and HDL3 particle diameter and α-linolenic acid (18:2 (n-3)), and increased plasma arachidonic (20:4(n-6)). The greatest increase in HDL cholesterol from baseline (0.07 mmol/L) was after the high-MUFA ground beef intervention. An increase from baseline in LDL particle diameter (0.5 nm) occurred after the mid- and high-MUFA interventions.We concluded that low-MUFA ground beef from pasture/hay-fed cattle was no more “heart healthy” than high-MUFA ground beef from corn-fed cattle as judged by common clinical criteria. In the second study, 19 of 29 post menopausal women completed a two-way crossover design. Subjects consumed five, 114-g ground beef patties per week for 6 wk periods separated by a 4 wk washout period. The low-MUFA patties contained 19.4 percent fat with MUFA:SFA of 0.9. The high-MUFA patties contained 22.5 percent fat with a MUFA:SFA ratio of 1.3. In addition to patty consumption, the subjects completed a bout of exercise during the last week of each phase. Blood was taken before, each diet phase (24 hr before exercise) and 24 hr post exercise. Total cholesterol was increased by the high-MUFA patties with the most significant increase seen in HDL cholesterol, mainly HDL2b subfraction. Lipid-rich lipoprotein fractions were increased with the low-MUFA diet, but not by the high-MUFA diet. Very long chain fatty acids were depressed by low MUFA patty consumption. When unadjusted for plasma volume shifts (raw), exercise decreased triglycerides in all three phases. Raw VLDL cholesterol was reduced after exercise during the intervention phases. Raw RLP and IDL cholesterol were reduced after exercise during the high-MUFA intervention. HDL2b was reduced after exercise during the high-MUFA phase. LDL mean size increased and LDL mean density decreased after exercise during the low-MUFA intervention. HDL mean density increased after exercise during both ground beef interventions. The data indicate that high-oleic ground beef can reduce some cardiovascular disease risk factors and can be a part of a healthful diet. Exercise can have a beneficial impact on cardiovascular disease risk factors independent and in conjunction with ground beef consumption.
544

Sorghum Bran, Chestnut Wood Powder, and Chardonnay Grape Seed Flour Addition Effect on Lipid Oxidation and Color in Ground Beef Patties

Roybal, Tabitha Lynn 2010 December 1900 (has links)
Natural, plant-based tannin antioxidants are capable of inhibiting lipid oxidation in ground beef and may be possible alternatives to industry synthetic and natural standards of BHA/BHT and rosemary extract, respectively. Ground beef was purchased on three different days, each defining a batch during study 1. Treatments, added based on meat weight, included a control, 0.2 percent rosemary (RM), 0.02 percent BHA/BHT, 0.5 percent Chardonnay grape seed flour (CG), 0.1 percent and 0.25 percent chestnut wood flour (CN), and 0.25 percent and 0.5 percent of four sorghum bran varieties: black (BS), black with tannin (BTS), white (WS), and high tannin (TS). Patties, formed in duplicate, were randomly designated as cooked or raw and by 0 to 5 day storage, and were aerobically stored at 4 degrees C. Cooked patties were analyzed using the TBARS method. Raw patties were analyzed for subjective and objective color, number of ingredient specks, and pH. In study 2, six treatments were chosen for sensory evaluation including a control, 0.2 percent RM, 0.02 percent BHA/BHT, 0.5 percent CG, 0.1 percent CN, and 0.5 percent BTS. Preparation, and raw and cooked analysis occurred similar to study 1. Additional patties were made for day 1 consumption by consumer panelists. In study 1, all treatments except 0.25 percent WS reduced TBARS values over time compared to 0.2 percent RM. Four treatments (0.5 percent BTS, 0.5 percent CG, 0.25 percent CN, and 0.1 percent CN) showed no significant increase in TBARS values over storage. BS and BTS yielded the lowest color space values (CIE L*, a*, and b*; P<0.0001). Ingredient specks were possible color measurement influences. In both studies antioxidant addition reduced TBARS values over time compared to the control (P<0.0001), and percent discoloration was highest in patties containing a sorghum treatment (P<0.0001). Patties containing 0.1 percent CN were significantly favored in terms of overall like (P<0.0002) and flavor like (P<0.0001). Patties containing 0.2 percent RM were ranked lowest in overall and flavor like, and ground beef-like bite. Patties containing 0.5 perent CG were least liked according to tenderness level (P<0.005). These results indicate that CG, CN, and certain varieties of sorghum bran can be added to pre-cooked ground beef products and provide better antioxidant protection than currently used ingredients of BHA/BHT and rosemary extract.
545

An Economic Analysis of Stream Restoration in an Urban Watershed: Austin, Texas.

Huang, Chi-Ying 2012 May 1900 (has links)
By 2006, the U.S. government has spent $15 billion to address the degradation of urban streams, including erosion of stream banks, disconnection of rivers from the floodplain, and disturbance of surface runoff pathways. Bank stabilization is one of the most prevalent restoration activities in urban stream restoration. Unfortunately, most stream restoration projects have been undertaken without a pre- or post-evaluation of the impact of stream restoration on real value in the area. All restoration projects beg the question: Did the money spent on the project result in greater benefits to stream stability as well as to adjacent properties? The Walnut Creek watershed, located in Austin, Texas, has experienced varying stages of urbanization since the 1990s. One of the streams, the Walnut Creek tributary, was restored in 2003. The purpose of this study is to assess the impact of stream restoration on housing values. We applied the hedonic pricing method to evaluate the changes in housing value associated with housing and environmental characteristics. Repeat ground photography was utilized to assess stream restoration activities at spatial and temporal scales. Our results suggest that the stream restoration project resulted in significant positive impacts on housing values in the periods of restoration (8.3%) and restoration adjustment (10.7%). However, the project did not enhance the values of houses on the floodplain. In addition, results show that erosion had continuous negative impacts on housing values. Overall, the restoration project contributed to the greater benefits during the restoration adjustment period right after restoration by an increase of 1% of the average housing value for each property on the restoration site. In this study, the benefits of stream restoration project were minimal since bank stabilization was the main activity considered in this stream restoration project. Nevertheless, restoration enhances the stability of the stream banks, minimizes erosion problems, and presents an enhanced aesthetic beauty of the stream in Austin, Texas.
546

A Study of Car Body Effects on the Performance of Vehicle Antennas

Lin, Meng-yi 29 December 2004 (has links)
In this study, we establish a car body PEC model by using a NEC-2-based numerical software. Based on this model, we then carry out a series of simulations and analysis in the FM band concerning the effects of various car structures on antenna patterns. The results have been compared with those available in open literature in order to verify our model. The simulation results show that the roof support pillars significantly affect the antenna patterns. We investigate the ripples caused by the finite ground plane in the antenna patterns, and propose a new edge treatment technique. Our results indicate that a significant reduction of these unwanted ripples can be obtained, if the proposed technique is applied. The effect of car glasses and human body is also taken into consideration. At last, the issue of studying the effects at higher frequencies is addressed. Two approaches are used, including UTD, and PO. Satisfactory results are obtained.
547

A Package-level Power Plane with Ultra-wide band Ground Bounce Noise Rejection

Wang, Ting-Kuang 11 July 2005 (has links)
Transient current surges resulted from the simultaneous switching of output buffers in the high-speed digital circuits can induce significant ground bounce noise (GBN) on the chip, package, and printed circuit board (PCB). The GBN not only causes the signal integrity (SI) problems, such as glitches or timing push-out of signal traces, but also increases the electromagnetic interference (EMI) in the high-speed digital circuits. With the design trends of digital circuits toward higher speed, low voltage level, smaller volume, the impact of GBN has become one of the most important issues that determine the performance of electronic products. Adding decoupling capacitors between the power and ground planes is a typical way to suppress the GBN. However, they are not effective at the frequencies higher than 600MHz due to their inherent lead inductance. Recently, a new idea for eliminating the GBN is proposed by designing electromagnetic bandgap (EBG) structure with high impedance surface (HIS) on the ground or power plane. Several new EBG power/ground plane designs have been proposed to broaden the stopband bandwidth for suppressing the GBN. However there are some drawbacks, such as high cost, large area occupation and complicated fabrication process. In this paper, we propose a novel Hybrid EBG power planes for PCB or package to suppress the GBN. Its extinctive behavior of broadband suppression of GBN (over 10GHz) is demonstrated experientially and numerically. Finally, we combine the periodic high-low dielectric material with the EBG power plane to control the position and bandwidth of stopband.
548

Effect of Thinning on Ground-dwelling Beetle Communities in a Taiwania Plantation

Hung, Mei-jhu 26 July 2005 (has links)
The spatial distribution and monthly fluctuation of beetle species were studied in the experimental forests of Liu-Kuei Station, Taiwan Forestry Research Institute, Taiwan. Beetles were surveyed using pitfall traps from January to December, 2004. Our result showed that species richness, abundance and Shannon diversity of beetles were significant higher in Natural Forest than those of the others, and species richness and abundance were lowest in Taiwania Plantation. The composition and trophic structure of beetle community in the Thinning Plantation resulting from thinning were compared with that in the Taiwania Plantation and natural forest. Beetles communities of Natural Forest, Taiwania Plantation and Thinning Plantation were separated from each other by ordination (PCA), meaning three forest stands have distinct species assemblages. The three group assemblages were also revealed by cluster analysis. The ground-surface air humidity, litter litter depth and herbs cover were major environment factors influencing the beetle distribution. The relative size of trophic guilds in the Thinning Plantation has changed compared to Taiwania Plantation. Detritivores increased significantly in the Thinning Plantation, suggested an increase of nutrient-cycle in the Plantation. Eight dominant beetle families that were Carabidae, Scarabaeidae, Curculionidae, Staphylinidae, Scydmaenidae, Erotylidae, Nitidulidae and Biphyllidae showed different pattern of population fluctuation. The peak mainly from March to June, and Curculionidae, Scarabaeidae, Nitidulidae also show a moderate peak in August and September. In the two plantation areas, most dominant taxa showed a similarly fluctuation patterns, which are slightly different to those of Natural Forest.
549

A Fast Method with the Genetic Algorithm to Evaluate Power Delivery Networks

Lee, Fu-Tien 20 July 2007 (has links)
In recent high-speed digital circuits, the simultaneous switching noise (SSN) or ground bounce noise (GBN) is induced due to the transient currents flowing between power and ground planes during the state transitions of the logic gates. In order to¡@analyze the effect of GBN on power delivery systems effectively and accurately, the impedance of power/ground is an important index to evaluate power delivery systems. In the operating frequency bandwidth, the power impedance must be less than the target impedance. The typical way to suppress the SSN is adding decoupling capacitors to create a low impedance path between power and ground planes. By using the admittance matrix method, we can evaluate the effect of decoupling capacitors mounted on PCB fast and accurately reducing the time needed from the empirical or try-and-error design cycle. In order to reduce the cost of decoupling capacitors, the genetic algorithm is employed to optimize the placement of decoupling capacitors to suppress the GBN. The decoupling capacitor are not effective in the GHz frequency range due to their inherent lead inductance. The electromagnetic bandgap(EBG) structure can produce a stopband to prevent the noise from disperseing at higher frequency. Combining decoupling capacitors with EBG structure to find the optimum placement for suppression of the SSN by using the genetic algorithm.
550

FDTD modeling of Ground Bounce effects on the Signal integrity and Electromagnetic interference in the high-speed PCB

Lin, Jih-Jong 06 July 2000 (has links)
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