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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.
101

Feeding and oviposition behavior of tobacco hornworms, Manduca sexta, in relation to Myo-inositol

Nelson, Nancy Marie, 1968- January 1996 (has links)
The purpose of this thesis is to examine the role that myo-inositol plays in feeding and oviposition by the tobacco hornworm, Manduca sexta. The results show that; (1) of all of the compounds tested only myo-inositol and epi-inositol consistently elicited a rapid, phasic-tonic firing response from taste receptors, (2) inositol is a feeding stimulant for both fifth and third stage M. sexta larvae, (3) M. sexta larvae do not need dietary inositol for normal growth and development, but females need dietary inositol as larvae for egg production as adults, (4) inositol is also a utilizable carbohydrate for M. sexta larvae and considering its relative abundance in Solanaceous plants, it may serve as an important carbohydrate source, (5) inositol does not appear to be important in oviposition, (6) inositol is correlated to protein levels in young tomato and tobacco plants.
102

Livestock demographics, management practices, and attitudinal orientations of native livestock producers on the Navajo Reservation

Kramer, Brett Andrew January 1999 (has links)
Livestock production characteristics on the Navajo Reservation were studied to quantify and characterize herd demographics, feeding practices, management practices, marketing practices, and attitudinal orientations of producers. A stratified random (by grazing Agency) sample of the population (n = 10,000) yielded 125 possible respondents from each Agency. Face to face interviews were conducted by Navajo district grazing committeemen in the fall of 1997 for a total of 257 completed surveys. Navajo livestock producers were subsistence-level producers, who battled low birthing rates, slightly elevated mortality rates, diminished resource capacity, and challenges to economical feeding regimes. Most Navajos believed that livestock were an important part of their family's financial well-being; the Reservation was overgrazed; and that Navajos should be allowed to fence their land over their neighbors' objections. Navajo livestock production can be improved through education and greater articulation of the resource base. More detailed data collection is warranted to provide greater insight into production characteristics.
103

Assessment of response variables in bovine models of pain and stress, with and without meloxicam

Mosher, Ruby A. January 1900 (has links)
Doctor of Philosophy / Department of Diagnostic Medicine and Pathobiology / Ronette Gehring / The absence of pain management for common husbandry procedures, such as dehorning and castration of cattle, is considered to be an important animal welfare consideration, but there are currently no drugs approved by the FDA for the purpose of providing pain relief in cattle. The FDA’s Center for Veterinary Medicine (CVM) recognizes the need for the availability of pain-relieving drugs and has encouraged research into the development of behavioral and physiologic measures which can reliably demonstrate the effectiveness in that species. The USDA has also recognized this need by providing grants for research into investigating pain models for cattle that can be used for the development of pain mitigation methods. The studies reported in this dissertation were funded by the USDA and the American Association of Bovine Practitioners. They add to the body of knowledge from which a pain model in cattle may eventually be validated for use in the drug approval process and also contribute to knowledge base for a candidate non-steroidal anti-inflammatory drug for convenient use in cattle. The study reported in Chapter 2 was conducted to support research of a candidate pain-assessment variable, substance P. This study provides future researchers with recommended sample handling procedures for obtaining reliable and repeatable results, which is important if substance P is to be validated as pain biomarker in cattle. The study in Chapter 3 investigated the use of several variables for use in a pain model. The results provided researchers, veterinarians and policy-makers with evidence to support the common practice of castrating and dehorning calves at the same time rather than as individual procedures separated by a healing interim. The study in Chapter 4 investigated the pharmacokinetics of oral meloxicam when administered to juvenile ruminant and pre-ruminant calves. This study added to the growing knowledge base of the pharmacokinetics of oral meloxicam in cattle and also provided practitioners with practical information concerning the administration of the drug in milk replacer. Chapter 5 investigated the use of oral meloxicam in a production setting and indicated that meloxicam administration prior to surgical castration may reduce the incidence of respiratory disease in the post-surgical period.
104

Unrealistically Optimistic Consumers: a Selective Hypothesis Testing Account for Optimism in Predictions of Future Behavior

Tanner, Robin James 21 April 2008 (has links)
Individuals tend to make unrealistically optimistic self assessments about themselves and their future behavior. While little studied in marketing, unrealistic optimism by consumers may have negative consequences for both marketers and consumers. This dissertation proposes and explores a selective hypothesis testing view of unrealistic optimism. Specifically, I propose that consumers adopt the tentative hypothesis that they will behave in an ideal fashion when predicting their future behavior. They then selectively test this hypothesis by accessing information consistent with it, with the ultimate consequence being unrealistically optimistic predictions of future behavior. To validate this theory I use the following experimental paradigm. I have individuals first provide an idealized estimate for the behavior of interest (e.g., In an ideal world, how often would you exercise next week?) and then provide a second estimate (e.g., How often will you exercise next week?). The idea here is that by making the idealized nature of the ideal behavior salient consumers will be less likely to test a hypothesis of ideal behavior when subsequently providing an estimate. In a series of ten studies, I find that prior consideration of idealistic performance does indeed temper optimism in subsequent self-assessments (henceforth post-ideal estimates). Specifically, post-ideal estimates are free of relative optimism versus expectations of others behaviors, are more reflective of actual past behavior, and better predict actual future behavior. Furthermore, this attenuation of optimism is mediated by increased consideration of realistic thoughts and is moderated by both expertise and decisiveness. All of these results are consistent with selective hypothesis testing being a key driver of unrealistic optimism. Additionally I demonstrate that the debiasing effect of my method extends from behaviors to above average (and in some cases below average) views of traits and abilities. As such my work raises the possibility that selective hypothesis testing underlies a wide variety of self assessment biases. Having found strong support for my selective hypothesis testing view of unrealistic optimism, I also explore the potential consequences that unrealistic optimism may have for consumer decisions. In particular, I demonstrate that unrealistically optimistic predictions of future behavior appear to be associated with greater willingness to pay for socially desirable products (e.g., treadmills) and that attenuation of such optimism can reduce willingness to pay. Some researchers have argued that unrealistic optimism with respect to future behavior causes people to make vice choices in the present because they expect to make virtuous choices in the future (Kahn and Dhar 2007). If so, then the current research suggests one way to help consumers from falling into the trap of justifying vice behaviors with optimistically held views about future actions. / Dissertation
105

Identification of seminal proteins related to fertility of bulls

McCauley, Tod Christopher, 1965- January 1998 (has links)
These studies were conducted to determine the chemical identity of heparin binding proteins in semen that are related to fertility of bulls. The first study describes the isolation and identification of a 31,000 dalton fertility-associated antigen (FAA). FAA was found to have significant primary structure homology to a recently described novel DNase I-like protein. The physiological significance of the similarities between FAA and a protein homologous to DNase I is unknown at this time as no function has been described for the DNase I-like protein. The second study describes the isolation and identification of a 24,000 dalton seminal heparin binding protein. It was found to be similar, if not identical, to tissue inhibitor of metalloproteinase-2 (TIMP-2). TIMP-2 regulates matrix metalloprotease activity and therefore, potentially plays a key role in the structural makeup of the extracellular matrix. These findings suggest that regulation of enzymatic activity in seminal fluid is in large part a function of heparin binding proteins that have been correlated to fertility of bulls, one being a potentially novel extracellular nuclease and a second acting as a specific inhibitor of metalloprotease activity. In addition to the ability to modulate capacitation of sperm, seminal heparin binding proteins likely are key players in protecting sperm and male reproductive tract tissues from enzymatic hydrolysis. The proteins identified in this dissertation represent novel additions to the previously described seminal heparin binding protein families. Clearly, these data indicate a growing complexity of seminal fluid and implicate a novel Dnase I-like protein and TIMP-2 in affecting cellular events related to fertility potential of males.
106

Modeling habitat use of a fringe greater sage-grouse population at multiple spatial scales

Burnett, Anya Cheyenne 21 September 2013 (has links)
<p> While range-wide population declines have prompted extensive research on greater sage-grouse (<i>Centrocercus urophasianus</i>), basic information about southern periphery populations, such as the Bald Hills population in southern Utah, has not been documented. The objective of this research was to determine habitat preferences and space use patterns of the Bald Hills sage-grouse population which occurs in an area of high potential for renewable energy development. I tracked 66 birds via VHF telemetry in 2011 and 2012 and surveyed vegetation plots throughout the study area. I found that the population was primarily one-stage migratory with seasonal distributions that did not correspond well with previously developed suitable habitat maps (based on local biologist knowledge and lek data) for all seasons; I also found that mean home range sizes ranged from 82 km<sup>2</sup> to 157 km<sup>2 </sup>.</p><p> Nesting hens did not select for any measured vegetation characteristics within the study area, while brood-rearing hens selected for high forb cover. Birds at summer sites (non-reproductive bird locations during the summer season) selected for greater grass and forb cover and lower shrub cover compared with random sites. Overall, Bald Hills sage-grouse used areas with greater shrub canopy cover and lower grass and forb cover than recommended in habitat guidelines. </p><p> Ten predictor variables were used to model suitable seasonal habitat using Maximum Entropy (maxent). All models were created for the Bald Hills population and projected to the Bureau of Land Management Cedar City Field Office management area and produced excellent model fit (AUC > 0.900). The Bald Hills population had similar nesting and winter habitat preferences as other populations but different brood-rearing and summer habitat preferences. I found local management techniques to be an important driver of seasonal habitat selection; birds selected for areas that had undergone habitat treatments (such as broadcast burn and crushing) within the previous 10 years. My results indicated the Bald Hills periphery population occupies marginal habitat and has adapted unique seasonal habitat preferences. Managers of isolated, fringe, and low-density populations should develop locally specific management guidelines to address the unique adaptations and ensure the persistence of these populations. </p>
107

Survival and activity patterns of snowshoe hares (Lepus americanus) in interior Alaska

Feierabend, Dashiell S. 24 October 2013 (has links)
<p> Snowshoe hare (<i>Lepus americanus</i>) survival depends on the interaction of habitat characteristics with numerous biological and environmental variables. In boreal regions where considerable habitat heterogeneity exists, hares balance food availability with predation risk by moving among habitats seasonally, but it is largely unknown how often they move at shorter time scales. I investigated the seasonal effects of habitat, weather, and individual hare characteristics on survival and movement in two common but fundamentally different boreal habitats. Survival was highest in summer, for hares with higher body condition, and in black spruce rather than early successional forest. Hares moved among core use areas in different habitats twice per day on average, using more open areas at night when they were presumably feeding on preferred browse. Movement rates were lowest in mid-afternoon when hares appeared to be resting under dense cover. Behavior of individuals varied greatly with some hares repeatedly moving up to 1 km between defined patches in less than 5 hours and others remaining roughly within a 1 ha area. These findings illustrate the complexity of snowshoe hare ecology in an area where habitat variation promotes daily movement of hares among radically different habitats over a few hundred meters.</p>
108

Effect of laminar shear stress on gene regulation, protein synthesis, and protein secretion by cultured human endothelial cells

Diamond, Scott Lee January 1990 (has links)
To test the hypothesis that wall shear stress generated by blood flow may regulate endothelial cell expression of blood clot dissolving proteins or vasoactive proteins, an in vitro perfusion system was used to expose human umbilical vein endothelial cell monolayers to well defined, laminar fluid flow. Protein production studies utilized immunoassays, while semi-quantitative studies of messenger RNA levels in a small numbers of cells required a reverse transcription/polymerase chain reaction technique. Secretion by endothelial cells of the two main regulators of the fibrinolytic (ie blood clot dissolving) system, tissue plasminogen activator (tPA) and plasminogen activator inhibitor, type 1 (PAI-1) were not affected by exposure to venous levels of shear stress (4 dynes/cm$\sp2$). However, at arterial shear stresses of 15 and 25 dynes/cm$\sp2$, the tPA secretion rate was 2.1 and 3.0 times greater, respectively, than the basal tPA secretion rate. PAI-1 secretion was unstimulated by shear stress over the entire physiological range. The tPA mRNA level was many fold higher ($>$10 fold) in endothelial cells sheared for 24 hours than in stationary controls. The mRNA level of the common house-keeping gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was found to be the same in control and sheared cells. The fact that GAPDH was unregulated indicates selectively in cellular response to shear stress in addition to validating the PCR technique. Endothelin (ET), a 21-amino acid peptide secreted by endothelial cells, has vasoconstrictor and mitogenic activity for vascular smooth muscle cells. Fluid shear stress of 25 dynes/cm$\sp2$ caused a rapid and sustained drop in endothelin production after only 2 hours exposure to shear stress. Endothelin secretion was not affected by venous shear stress of 4 dynes/cm$\sp2$. The mRNA level for endothelin in cells exposed to shear stress was almost undetectable, indicating that the drop in protein secretion is due to a drop in transcription of the message RNA for endothelin. The mRNA level of basic fibroblast growth factor (bFGF) was found to be the same in cells sheared for 24 hours as in controls. Enhancement of the fibrinolytic potential of endothelial cells in response to hemodynamic forces involves transcriptional events and could explain the deposition of fibrin in low shear zones near arterial bifurcations. Flow-regulated ET expression may explain the inverse correlation of fluid shear stress with: (1) the localization of atherosclerotic lesions near vessel bifurcations and; (2) the severity of intimal hyperplasia in surgical vein bypass grafts and vessel anastomotic sites.
109

Supplementing soybean meal with Camelina (Camelina sativa) in tilapia diets and optimizing commercial tilapia diets for use in intensive systems in the Western region of the United States

Ramotar-John, Badule Pamila 21 October 2014 (has links)
<p> The feed production cost in tilapia diets is driven by the prices of its ingredients such as fishmeal (FM) and soybean meal (SBM). Fishmeal and soymeal combined with other ingredients provides fish with the nutrients required for growth and sustaining life. Soybean meal is used as an alternative to fishmeal, but prices for this traditional ingredient have increased significantly in recent years as a result of high market demand from other industries. Consequently, there has been an increase interest by tilapia nutritionists and feed manufacturers to find less expensive, alternative feedstuffs for use in tilapia diets. </p><p> Camelina <i>(Camelina sativa)</i> is an oil seed crop grown in higher latitudes especially along the US - Canada border, northern China and northern Europe. Camelina after removal of most of the edible oil has been proposed as a fish feed ingredient. </p><p> A sixty-day feeding trial was conducted and diets were formulated to contain various levels of camelina inclusion (0, 5, 10, 15, 20 and 25%) for the &ldquo;camelina meal&rdquo; while the &ldquo;camelina oil&rdquo; was formulated to contain one level (4.7%) of oil and was divided as &ldquo;raw&rdquo; and 4.7 &ldquo;wash&rdquo;. The results indicated that that fishes fed diets containing camelina ingredients had growth performance and feed utilization results that were similar to fish fed the commercial diet (P>0.05). There were significant differences (P&lt;0.05) for body organ indices and body composition. The 15% camelina meal diet was the lowest cost experimental diet per kilogram gain and therefore, this alternative ingredient might be a potential replacement for soymeal in a more cost effective feed formulation. </p><p> The fatty acid composition of tilapia fillets was also analyzed at the end of the feeding trial. The inclusion of camelina meal and oil in tilapia diets resulted in significant increases in the Omega-3/Omega-6 ratio in fillets when compared to the control. The 15% camelina meal provided the best results of the experimental diets yielding significantly higher polyunsaturated fatty acid (PUFA) and lower saturated fatty aid (SFA) than the control diet. </p><p> On a commercial scale, tilapia commercial feeds differ in both formulated nutrient levels and ingredient composition. In intensive system culture, natural food is limited making it important that all nutrients are supplied through a complete pelleted diet. An advantage to feeding a pelleted diet is that the pellet-type feed enables the farmers, feed formulators and manufactures to design a diet that provides an optimal nutritional mix for tilapia. </p><p> Precise levels in the protein and lipid percentages of tilapia diets can reduce feed costs and also reduce the amount of underutilized protein and lipids stored as fat in tilapia. Feed comprises of over 60% of the variable cost in the intensive aquaculture operation; if feed prices were to increase, it would be a substantial amount for tilapia producers to absorb. Therefore an improved diet formulation designed for tilapia can increase profitability. </p><p> Results indicated that the experimental diets (28% Crude Protein (CP)-Amino Acid (AA), 28% CP and 40% CP) performed similar to the control diet (32% CP) as it relates to fish growth. The experiment conducted on a commercial scale at an operating farm found that feeding tilapia the lowest protein level diets (28% CP) resulted in higher biomass gain per raceway, biomass gain per fish and significantly higher protein efficiency ratio (PER) when compared to the control diet (32% CP). The 28% CP diet also had the second best FCR value and most importantly higher returns based on its FCR when compared to the control diet (32% CP).</p>
110

Maternal transfer of metals in live-bearing fish (Cyprinodontiformes| Poeciliinae)

Cazan, Alfy Morales 26 July 2014 (has links)
<p> This study assessed the occurrence and impacts of maternal metal transfer in live-bearing fish. The occurrence was investigated in two different species (<i>Gambusia affinis</i>and <i>Heterandria formosa</i>), while the impacts were studied only in <i>G. affinis.</i> Occurrence and impacts were addressed by exposing gravid females for 10 days to 0.15 &mu;M of copper or cadmium, transferring the fish to clean water, monitoring their reproduction and collecting newborn offspring for further analyses of their health and reproductive success. </p><p> Maternal transfer of copper and cadmium occured in both study species. Metal levels decreased in subsequent broods and in broods born later after a female's exposure. Metal exposure impacted the reproductive success of exposed-females; effects included smaller broods and more broods were aborted broods or contained dead offspring. Many effects remained for second broods developing well after the exposure. </p><p> The maternal metal exposure also impacted the offspring's health. Newborn offspring were smaller at birth, had reduced calcium levels, had a lowered metal tolerance, and had cellular membrane damage. When these offspring grew up, they had an increased rate of malformations, a smaller size at sexual maturity, increased gestation time and fewer broods. In spite of the impacts on life history parameters found in the laboratory, effects on population dynamics were very limited for greenhouse mesocosm populations established with the offspring of exposed females. </p><p> Effects for the essential metal (copper) and the nonessential metal (cadmium) were generally similar. A few effects, like those on body size, were evident for copper but not for cadmium. However, several of the more severe impacts, like the increase in malformations and reductions in the number of broods, were greatest for the offspring of the cadmium-exposed females. </p><p> This is the first report demonstrating negative impacts resulting from a short-term maternal metal exposure in live-bearing fishes. Effects were evident not just for reproduction of exposed-females but also for their offspring's health and reproduction. The latter continued beyond the offspring that were developing during exposure. This study demonstrated that the internal development in live-bearing fish may not spare the developing young from impacts caused by a metal-contaminated environment.</p>

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