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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.
131

Evaluation of candidate pheromone blends for mating disruption of the invasive swede midge (Contarinia nasturtii)

Hodgdon, Elisabeth Ann 01 January 2019 (has links)
Swede midge (Contarinia nasturtii, Diptera: Cecidomyiidae) is a small invasive fly that is currently threatening Brassica vegetable and oilseed production in the Northeastern U.S. and Canada. Larvae feed on plant meristems, resulting in deformed leaves, stems, and heads. Extremely low damage thresholds for heading Brassica vegetables, multiple overlapping generations, and lack of effective organic insecticide options present serious challenges for managing this pest. Pheromone mating disruption (PMD), which involves confusing male insects with unnaturally large doses of sex pheromones, is particularly promising for swede midge management because it prevents mating and subsequent oviposition. One major challenge to PMD for swede midge management is that the chiral female pheromone blend, a 1:2:0.02 blend of (2S, 9S)-diacetoxyundecane, (2S, 10S)-diacetoxyundecane and (S)-2-acetoxyundecane, is expensive to synthesize due to the structural complexity of the compounds. Here, we explored three ways to reduce the cost of swede midge PMD: the use of lower-cost racemic pheromones containing all possible stereoisomers, single-component blends, and the possibility of using timed pheromone dispensers by testing for diel patterns of midge reproductive behavior. Although we found that males were not attracted to blends containing the racemic stereoisomers of the main pheromone component, (2S, 10S)-diacetoxyundecane, racemic blends functioned equally as well as chiral blends in confusing males and altering female behavior in PMD systems. We observed 95% and 87% reductions in males caught in monitoring traps in three-component chiral and racemic PMD plots of broccoli, respectively. In addition to confusing males, we also found that females altered their reproductive behavior in response to both chiral and racemic pheromones. Females released pheromones more frequently when exposed to three-component chiral and racemic blends, and were less likely to mate afterward. Single-pheromone treatments containing either chiral or racemic 2,10-diacetoxyundecane neither confused males nor influenced female behavior. We identified a total of eight hours during the day and night when midges do not exhibit mate-seeking behavior, during which programmable PMD dispensers could be turned off to save pheromone inputs. We found that up to 81% of females released pheromones to attract males for mating in the early morning shortly after dawn. Most females emerged in the morning as well, releasing pheromones soon after eclosing. Because midges are receptive to mates shortly after emergence, they may mate at their emergence site. Overall, we found relatively high levels of crop damage in our pheromone-treated plots, likely due to the migration of mated females into our plots. If midges mate at emergence sites, rotation of Brassica vegetable crops may result in overwintered midges emerging in fields where host plants are not currently grown. Further research is needed to determine where midges mate in order to determine where to install PMD dispensers.
132

Challenges of Child Trauma on Adoptive Families' Social and Emotional System

Ford, Jacqueline Yvonne 01 January 2015 (has links)
Adoption-focused psychoeducation is deemed essential in maintaining the permanency of traumatized children within a new family unit. However, adoptive parents of traumatized children struggle to find training to address their unique concerns. Guided by the lens of psychodynamic theory, the purpose of this study was to investigate the challenges faced by adoptive families of traumatized children. Special focus was placed on the social and emotional relationships of the adoptive parents of traumatized children, to identify the realistic expectations towards attachment from the families' perspectives. Fifteen families were randomly selected to participate in this study from a group of 30 parents who adopted traumatized children in Arizona. A phenomenological approach was utilized to gather information from face-to-face and telephone interviews. The data analysis utilized the horizontalization approach which highlighted significant statements that were classified into codes. Thematic categories were drawn and summarized. Textual descriptions evolved from the thematic groups acknowledging their experiences and how these lived experiences guided their decision to adopt a traumatized child. Verification techniques, data mining, journaling, clustering, brainstorming, and peer reviews were used to ensure the quality of data. Emergent themes emphasized the need for adoption-focused training specific to traumatized children. Further research on this phenomenon should determine the significance of specialized psychoeducational training versus general foster care training, before and after adoption. Positive social change may result in tailoring existing training programs to meet the needs of families who adopt traumatized children.
133

PCB126-induced metabolic disruption: effects on liver metabolism and adipocyte development

Gadupudi, Gopi Srinivas 01 December 2016 (has links)
Recently, persistent organic pollutants such as polychlorinated biphenyls (PCBs) were classified as “metabolic disruptors” for their suspected roles is altering metabolic and energy homeostasis through bioaccumulation in liver and adipose tissues. Among PCBs, a specific congener, 3,3',4,4',5-pentachlorobiphenyl (PCB126), is a potent arylhydrocarbon receptor (AhR) agonist and elicits toxicity similar to the classic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). PCB126 levels found in human blood are particularly associated with diabetes and nonalcoholic fatty liver disease (NAFLD) in humans, however the mechanisms are unclear. We hypothesized that the accumulation of PCB126 disrupts carbohydrate and lipid metabolism by altering the functions of liver and adipose tissues. Hence, our objective was to characterize PCB126 induced-metabolic disruption and the underlying molecular mechanisms that cause toxicity. Separate animal studies were performed using a rat model to understand the time- and dose-dependent effects after PCB126 administration. The chronology of PCB126 toxicity showed early decreases in serum glucose level at 9 h, worsened in a time-dependent way until the end of the study at 12 d. Lipid accumulation and the liver pathology also worsened over time between 3 d and 12 d post administration. These observed effects in the liver were also found to be dose-dependent. The decrease in serum glucose was a result of a decrease in the transcript levels of gluconeogenic and glycogenolytic enzymes, necessary for hepatic glucose production and hence the maintenance of steady glucose levels in the blood. Phosphoenolpyruvate carboxykinase (PEPCK-C), the rate limiting enzyme of gluconeogenesis, was found to be significantly decreased upon exposure to PCB126. The expression levels of peroxisome proliferator-activated receptor alpha (Pparα) and some of its targets involved in fatty acid oxidation were also found to be time and dose-dependently decreased upon exposure to PCB126. In an attempt to understand the molecular targets that may cause these dual effects on both gluconeogenic and fatty acid oxidation, we found that PCB126 significantly decreases phosphorylation of the cAMP response element-binding protein (CREB). CREB is a nuclear transcription factor that is activated in the liver through phosphorylation; to switch-on the transcription of enzymes that catalyze gluconeogenesis and fatty acid oxidation, in order to meet energy demands, especially during fasting. Further, to understand the toxicity of PCB126 on adipose tissue, a human pre-adipocyte model that can be differentiated into mature adipocytes was used. In these studies, we found that exposure of preadipocytes to PCB126 resulted in a significant reduction in their ability to differentiate into adipocytes. This results in decreased lipid accumulation in the adipocyte. Reduction in the differentiation by PCB126 was associated with down regulation in transcript levels of a key adipocyte transcription factor, PPARγ and its transcriptional targets necessary for adipogenesis and adipocyte function. These inhibitory effects of PCB126 on the regulation of PPARγ and the initiation of adipogenesis were mediated through activation of AhR. Overall, this work shows that PCB126 disrupts nutrient homeostasis through its effects on the function of target tissues; liver and adipose. PCB126 significantly alters the nutrient homeostasis through its effects on gluconeogenesis and fatty-acid oxidation necessary for glucose and energy regulation during fasting. In addition, PCB126 interrupts the storage functions of adipose tissue by inhibiting adipogenesis and thus disrupts lipid storage and distribution
134

Noncontingent Delivery of Preferred Stimuli to Treat Problem Behavior in the Classroom

Miles, Nicole P. 01 May 2010 (has links)
Students with emotional and behavioral disorders (EBD) have very poor long-term outcomes. Non-contingent reinforcement (NCR) has been used to successfully reduce problem behaviors. NCR is frequently used with populations with severe disabilities and in hospital settings using function based reinforcers. Very few studies have applied the use of NCR to EBD populations, and to students whose cognitive scores fall within the normal range. No studies have examined the use of preferred tangible reinforcers delivered non-contingently with participants with EBD or in classroom settings. This study measured the effects of delivering tangible reinforcers selected through preference assessments on the disruptive and on-task behaviors of three students with EBD in the classroom setting. Results indicate the use of preferred tangibles delivered on a fixed-schedule can be effective in reducing disruptive behavior in the classroom without reducing on-task behaviors, and may, in fact, be effective in increasing on-task behaviors in the classroom.
135

"Galilean turbulence" : disruption and the bible in the poetry of W.B.Yeats

Horne, Nicholas Lawrence Unknown Date (has links) (PDF)
Disturbance has been recognised as a presence in Yeats’s poetry for some time, although its discussion has not been extensive. The purpose of this thesis is to explore a particular type of disturbance in Yeat’s poetry that has not yet been investigated: disruption, and its relation to the Bible. I argue that disruption, in its meanings of interruption, disorder, fracturing, and division, is a distinct presence in a number of Yeat’s poems, and that it manifests in three key categories: disruption relating to Yeatsian poiesis, Yeat’s interest in and use of instances of disruption in the Bible, and disruption of the Bible itself. / I begin by considering “The Second Coming” as a notable instance of disruption and its religious and biblical resonances. I argue that this work, in reference to an instance of disruption in the Bible, undergoes textual disruption close to its centre. I develop an account of the poem as divided into opposing texts, identities, and prophetic currents, all in close relation to the Bible. I then turn to a range of contextual matters raised by the discussion of “The Second Coming”. Starting with a consideration of religion and the Bible in Yeat’s artistic vision, I argue that these two factors are important to Yeat’s envisioning of art and that disruption is deeply involved with both. Following this I investigate the relation between disruption and the Bible itself, demonstrating that disruption is a strong presence in the biblical narrative. I then consider Yeat’s reception of the Bible, focusing on Yeat’s perception of the Authorised Version and on Blake as a precursor. I argue that the Authorised Version was significant for Yeats, and that Blake was influential in demonstrating the poetic possibilities of biblically-related disruption for Yeats. / After discussing these contextual matters I embark upon a wider survey of biblically-related disruption in Yeat’s poetry. First, I consider a group of poems from one of Yeat’s earlier poetic books, The Wind Among the Reeds. I argue that these works, through the figure of the biblical wind, explore the conjunction of disruption and the Bible in each of the three categories of disruption outlined above. I then turn to a second set of poems that I group together due to a shared theme of inspiration. I argue that these works also engage with disruption and the Bible, particularly in relation to the category of disruption relating to the act of poiesis. The last group of poems that I consider are concerned with central events in the life of Christ. I argue that these works demonstrate a dynamic exploration of disruption and the Bible in relation to these events, focusing particularly on the nature of Christ as God and Saviour. I then proceed to a consideration of disruption in Yeats apart from its expression in the poetry. Seeking to gain a deeper insight into disruption as an element of Yeatsian poiesis, I consider some relevant theoretical perspectives before suggesting that disruption in Yeats can be constructively interpreted in terms of potentiality.
136

Comparison of methods for DNA extraction from Candida albicans

Dadgar, Ashraf January 2006 (has links)
<p>Invasive Candida infection is an increasing cause of morbidity and mortality in the immunocompromised patient. Molecular diagnosis based on genomic amplification methods, such as real time PCR, has been reported as an alternative to conventional culture for early detection of invasive candidiasis. The template DNA extraction step has been the major limitation in most reported nucleic acid based assays, due to problems in breaking fungal cell walls and incomplete purification in PCR inhibitor substances.</p><p>The aim of this study was to compare enzymatic cell wall disruption using recombinant lyticase with mechanical disruption using glass beads. The QIAamp tissue kit was compared with two automated DNA extraction robots, the BioRobot M48 and NucliSens easyMAG, to determine their sensitivity, reliability and duration for DNA release of C. albicans. Mechanical cell wall disruption shortened and facilitated the extraction procedure, but the quantity of released DNA was significantly lower than when enzymatic cell wall disruption was used. Use of robots did not significantly shorten the DNA extraction time, compared with manual DNA extraction. However the NucliSens easyMAG resulted in a higher yield of target DNA compared to the BioRobot M48 and the manual QIAamp tissue kit.</p> / <p>Invasiva svampinfektioner är ett stort problem hos patienter med dåligt immunförsvar. Förekomst av invasiva svampinfektioner har ökat under senare år och medför hög dödlighet. En svampinfektion som inte snabbt diagnostiseras och behandlas kan bli livshotande om patientens kondition är dålig. Candida albicans är den vanligaste orsaken till invasiva svampinfektioner. Med traditionell svampidentifiering kan det ta dagar till veckor att isolera och artbestämma svampen. En snabbare metod att detektera Candida är att använda sig av molekylärbiologiska metoder som påvisar svampens arvsmassa, DNA. Svampar har en cellvägg som är svår att bryta ner och därför är DNA extraktionssteget ett av de mest rapporterade problemen vid DNA svampdiagnostik.</p><p>Syftet med denna studie var att jämföra enzymatisk och mekanisk cellväggsnedbrytning av C. albicans med hjälp av enzymet lyticase respektive glaskulor. Vi jämförde också en manuell metod med två automatiska robotar för att bestämma deras känslighet, tillförlitlighet och tidsåtgång för DNA-extraktion från C. albicans. De slutsatser som nåtts är att den enzymatiska cellväggsnedbrytningen var känsligare men betydligt mer tidskrävande än den mekaniska cellväggsnedbrytningen. Denna studie visade även att en av de automatiska systemen extraherade signifikant mer DNA än den manuella metoden.</p>
137

Differentiation of Brain and Reproductive Organs in Birds : Effects of Environmental Contaminants

Axelsson, Jeanette January 2008 (has links)
The first objective of this thesis was to investigate effects of endocrine disruptors on the developing brain and gonads of bird embryos. The substances studied were the insecticide methoxychlor, and nine UV-filters (3-benzylidene camphor (3BC), 4 methyl benzylidene camphor (4MBC), benzophenone (BP) 1,2 and 3, 4 hydroxy benzophenone (4 HB), 4 dihydroxy benzophenone (4DHB), benzyl salicylate (BS), and ethyl-4-aminobenzoate Et-PABA)), commonly used in cosmetic products. Some of these substances have no estrogenic effect in vitro, but have been shown to be estrogenic in vivo. The PCB-mixture Clophen A50 is a well-known inducer of biotransformation enzymes and was co-administered with methoxychlor and the UV-filters 3BC and 4MBC. Exposure to 3BC or 4MBC caused ovotestis formation and malformations of the Müllerian ducts in Japanese quail embryos. Co-exposure to one of these compounds and Clophen A50 enhanced the effects, indicating that Clophen A50 potentiates the effects of the UV-filters. Embryonic co-exposure to Clophen A50 and methoxychlor caused a disturbed male sexual behaviour. The metabolites of methoxychlor are estrogen receptor (ER)α-selective, which indicates that the effects on behaviour following embryonic treatment were mediated by ERα. Another objective in this thesis was to localize estrogen receptors (ERs) in the brain of adult and embryonic Japanese quail. The ER localization provides a basis for mechanistic studies on effects of endocrine disruptors, by the identification of estrogen-responsive areas in the brain. We found that ERβ, not previously implicated in sex-differentiation of the brain, was the only ER-subtype present in a sexually dimorphic brain area during differentiation. In conclusion, the estrogenic effects of 3BC, 4MBC and methoxychlor were increased by co-exposure to PCB. These results raise concern since many wildlife species, as well as humans, carry large body burdens of persistent organic pollutants like PCBs, which potentially can interact and enhance the effects of other endocrine disruptors.
138

Analysis Of An Options Contract In A Dual Sourcing Supply Chain Under Disruption Risk

Kole, Huseyin 01 September 2012 (has links) (PDF)
In this study, value of demand information and the importance of option contracts are investigated for a supply chain consisting of a buyer and two suppliers in a single period setting. One supplier is cheap but prone to disruptions whereas the other one is perfectly reliable but expensive. At the beginning of the period, buyer orders from the unreliable supplier and reserves from the reliable supplier through a contract that gives buyer an option to use reserved units after getting disruption information of first supplier. We introduce three models which differ in terms of the level of information available when the ordering decisions are made. In the full information model, the options are exercised after getting disruption and demand information / in the partial information model, the options are exercised after getting disruption information before demand information. In the no information model, there is no options contract and units are ordered from the reliable supplier when buyer has no information about demand and disruption. Through the analysis of these models, we explore the value of advance demand and disruption information in the presence of an options contract.
139

Brain Aromatase in the guppy, Poecilia reticulata : Distribution, control and role in behaviour

Hallgren, Stefan January 2009 (has links)
Oestrogens are produced by aromatisation of androgens by the aromatase enzyme. In the vertebrate brain this synthesis has vital functions in nerve protection, cell proliferation and nerve development during injury respectively brain development. Brain oestrogens are also crucial in activating certain reproductive and aggressive behaviours in mammals and birds. Teleosts have remarkably high activity of brain aromatase (bAA) compared to mammals and birds; 100-1000 times higher in brain regions like the hypothalamus, pre-optic area and optic tectum. The role of brain oestrogens in teleost behaviour is, however, less clear than in e.g. songbirds and rodents. This thesis studies the potential role of brain aromatase and brain oestrogens in the reproductive behaviour of the guppy male (Poecilia reticulata), how guppy brain aromatase responds to steroids and is distributed in the adult brain. The thesis shows that male behaviour can be affected by brain aromatase. Reduction of bAA by aromatase inhibitor treatment reduced the sexual behaviours sigmoid display and gonopodium swinging (I) and oestrogen receptor blocking with an oestrogen antagonist reduced the number of successful mating attempts (II). The anatomical study (IV) showed that brain aromatase is distributed in areas of the adult guppy brain that are connected to reproductive control and behaviour in vertebrates. Guppy bAA is stimulated by both androgens and oestrogens (III) but is more sensitive to oestrogens, especially in males, and could thus be used as an indicator of endocrine disruption at low concentrations found in the environment. The thesis can also conclude that females possess more brain aromatase than males, and that although it is expressed in the same pattern throughout the brain in both genders the enzymatic activity is differently distributed between the sexes. / Aromatase and androgens in fish reproductive behaviour
140

Roles of ERα and ERβ in Normal and Disrupted Sex Differentiation in Japanese Quail

Mattsson, Anna January 2008 (has links)
Exposure to xenoestrogens during development has been shown to impair sexual differentiation in various species. The major aim of this thesis was to elucidate the respective roles of the two estrogen receptors ERα and ERβ in normal and disrupted differentiation of sex organs and copulatory behavior in the Japanese quail (Coturnix japonica). The expression of ERα mRNA was much stronger than that of ERβ mRNA in the gonads and Müllerian ducts (embryonic oviducts) in early embryos. By contrast, ERβ seemed to be predominantly expressed in regions of the embryonic brain that are associated with male sexual behavior. Embryos were exposed to the selective ERα agonists propyl-pyrazole-triol (PPT) and 16α-lactone-estradiol (16α-LE2). The estrogens 17β-estradiol (E2) and 17α-ethynylestradiol (EE2), which activate both ERα and ERβ, were used as positive controls. All substances impaired reproductive organ differentiation. The effects observed included oviductal malformations in females and partial development of oviducts in males. All substances also induced testis feminization (ovotestis) in male embryos. The male copulatory behavior was severely impaired by the positive controls but was unaffected by PPT and 16α-LE2 at doses that disrupted sex organ differentiation. A higher dose of 16α-LE2 significantly suppressed the behavior. However, it is possible that this effect was caused by cross-activation of ERβ. The substances also induced hepatic expression of mRNA encoding the egg-yolk proteins vitellogenin II and very low-density apolipoprotein II, which are commonly used as indicators of estrogen exposure. In conclusion, the results suggest that ERα is important for female reproductive organ differentiation. Excess activation of ERα by xenoestrogens impairs differentiation in both females and males and induces hepatic expression of egg-yolk proteins. The results also indicate that ERα alone cannot mediate demasculinization of male copulatory behavior in quail, although further studies are needed to test this hypothesis.

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