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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.
21

Thyromimetic and Proteomic Analysis of Secondary Wastewater Effluent

Littlehat, Jr., Peter January 2007 (has links)
Wastewater reclamation and reuse is imperative in water-starved areas such as the southwestern United States. In the Tucson Active Management Area, a geographic region defined for the purpose of groundwater management, the total demand for water already exceeds the available water supply, which consists of renewable ground water and the regional entitlement to Central Arizona Project water. Thus, the regional demand cannot be satisfied without resorting to groundwater mining unless water is reclaimed for local beneficial use. Less certain are the acceptable uses for reclaimed water and the nature of use-dependent treatments or water quality requirements that will protect human and ecological health. Disruption of thyroid-mediated actions is among the possible risks from chronic exposure to environmental contaminants. Endocrine disrupting compounds are generally of greater concern in this context than other trace contaminants because of the very low concentrations at which hormones induce physiological responses. Accordingly, a sensitive nuclear-based bioassay system was developed in order to evaluate environmental samples. A luciferase-reporter construct and the human thyroid receptor β (TR-β) construct in the human hepatoma cell line (HepG2) and human medulloblastoma cells (TE671) was evaluated for sensitivity. The transfected cells were exposed to the thyroid hormone, T3, in order to establish a lower thyroid hormone detection limit for the new bioassay procedure. The assay was then applied to environmental samples containing organics concentrated from final effluent derived from a conventional secondary wastewater treatment plant. The effluent samples activated thyroid receptor-mediated transcription. Also in this study, a two-dimensional gel electrophoresis (2D-DIGE) was used as an in vitro bioassay to look for wastewater related alteration of cellular protein expression in the human breast cancer cell T47D. Steps in this bioassay include the one-dimensional separation of proteins by isoelectric focusing followed by orthogonal electrophoresis to isolate the proteins. The consistency of test response was examined for wastewater-dependent up- or down-regulation of protein expression. Some proteins that were upregulated were preliminarily identified via mass spectrometry. Here, the procedure is used to provide direct information regarding the probable effects of residual hormones in treated wastewater on the activities of human, estrogen-responsive cells in cell culture.
22

The Impact of Inventory Leanness and Slack Resources on Supply Chain Resilience: An Empirical Study

Lyons, David J 11 December 2014 (has links)
When a major disruption occurs, an organization’s performance is usually negatively affected. The great recession of 2008 – 2009 was such a disruption which had global implications that had not been seen since the great depression that started in the 1930s. This thesis is intended to contribute to the understanding of how leanness and slack resources affect firm performance in the presence of disruptions that test supply chain resilience, or the ability to restore the firm’s performance to its original condition after encountering stress or a large disturbance. These disruptions may not only affect the firm’s financial performance during the disruption but also well after the disruption has occurred. Two industries with differing supply chains, food and beverage, and electronics and computer, were investigated. The study is based on archival data (N=10,020 and 668 firms) with observations from just before and just after the great recession, a disruption that affected the entire global economy. Our results suggest (1) the effect of inventory leanness and slack resources on firm performance is industry specific; and (2) variation in firm performance is less in the post-disruptive period than in the pre-disrupted period. Overall, our findings call for a contingency perspective to specify the level of inventory leanness and slack resources when determining their impact on firm performance to support supply chain resilience.
23

Development of an Algal Oil Separation Process

Samarasinghe, Nalin 2012 August 1900 (has links)
Microalgae surpass the lipid productivity of terrestrial plants by several folds. However, due to the high moisture content and rigidity of algal cell walls, extraction of lipids from algae is still a significant technological challenge. In this research, an attempt was made to develop an algal lipid separation process which is energy efficient and effective. Algal related research requires a unique set of knowledge in areas of algae culturing, measuring cell concentration, harvesting, cell rupturing and lipid quantification. The first section of this thesis focuses on the state of the art as well as knowledge gained during preliminary studies. The second section of this thesis focuses on selecting a suitable measurement technique for quantification of algal cell disruption induced by homogenization. The selected method, hemocytometry was used to measure the degree of algal cell disruption induced by homogenization. In the third section, various homogenization treatments were evaluated for determining the fraction of cells disrupted during the homogenization. Finally, lipid extraction efficiency of homogenized algae was evaluated using different extraction solvents under different homogenization conditions. Preliminary research concluded that using cell counting is the most suitable technique to measure the effect of high pressure homogenization on concentrated microalgae. It was observed that higher pressure and increased number of passes increase the degree of cell disruption. Concentrated, non stressed samples show best response to homogenization. Out of the three solvents used for solvent extraction, chloroform gave a higher extraction yield at low intensity homogenizations. However at harsher homogenization levels the advantage of chloroform was not significant. Lipid extraction efficiency increases with increased levels of homogenization. However, a significant increase in lipid yields was not detected beyond 20 000 psi and 2 passes of homogenization treatment.
24

Aqueous enzymatic extraction of protein and lipid from the microalgae species Chlamydomonas reinhardtii

Soto Sierra, Laura January 1900 (has links)
Master of Science / Department of Biological & Agricultural Engineering / Lisa R. Wilken / Microalgae has potential as a biofuel feedstock and as a source of valuable bioproducts for a variety of food, feed, nutraceutical, and pharmaceutical industries. However, several challenges are associated with bioproduct extraction from microalgae. The complexity of microalgae cell necessitates use of energy intensive disruption methods but current chemical or mechanical techniques can degrade economically valuable bioproducts. Aqueous enzymatic extraction (AEE), is a non-solvent and environmentally friendly bio-product recovery method that provides an opportunity to design an integrated process for protein and oil fractionation while reducing industrial costs. Based on the mechanistic understanding of biomolecule distribution and compartmentation, an aqueous enzymatic treatment for the release of internally stored proteins and lipid bodies in wild type Chlamydomonas reinhardtii was developed. In this study, we optimized harvesting times that maximized lipid and protein yields in nitrogen depleted cultures of the microalgae Chlamydomonas reinhardtii. Furthermore, an aqueous enzymatic extraction (AEE) treatment was developed. First, four lytic enzymes were tested for their ability to permeate C. reinhardtii cell walls. After cells were permeable, another set of enzymes were tested for their ability to release internally stored bioproducts. Protein recovery and lipid characterization after enzymatic treatment indicated a 54% release of total soluble protein and a localization of lipids to the chloroplast. Additionally, the development of secondary enzyme treatment for chloroplast disruption achieved about 70% total lipids released into the supernatant. Taken together, results indicate the application of an enzymatic treatment scheme for protein and oil recovery as a promising alternative to traditional extraction processes.
25

Reproductive and Growth Responses of the Fathead Minnow (Pimephales Promelas) and Japanese Medaka (Oryzias Latipes) to the Synthetic Progestin, Norethindrone

Paulos, Peter M. 05 1900 (has links)
A commonly prescribed contraceptive, the synthetic progestin norethindrone (NET) inhibits ovulation in humans. However, ecotoxicological data are lacking. Preliminary tests produced an LC50 for NET of > 1.0 mg/L (96-hour, fathead minnow (FHM) and medaka) and a NOEC of 242.0 µg/L, a LOEC of 485.0 µg/L (7-day, growth for FHM and medaka). Reproductive testing revealed a LOEC for fecundity of 24.1 ng/L (21 days, medaka). Further testing confirmed the LOEC of 24.1 ng/L while defining a NOEC of 4.7 ng/L (28 days, medaka). Effect of NET in medaka life-cycle exposure at concentrations exceeding 4.7 ng/L was evident. Few females were present in the 24.7 ng/L exposure concentration, with none in the 104.6 ng/L. Egg production was significantly reduced at concentrations exceeding 4.7 ng/L. Additionally, weight, condition factor and somatic indices were significantly different in males exposed to concentrations exceeding 4.7 ng/L. For fecundity and sexual differentiation; the NOEC was 4.7 ng/L, the LOEC 24.6 ng/L; growth and somatic indices, the NOEC was more appropriately 0.9 ng/L, with effect evident at 4.7 ng/L. Sexual differentiation of the F1 population was similar to the F0. A defining result of this test was development of exceptionally large ovaries in NET- exposed female medaka, perhaps indicative of a threshold limit for exposure in these fish. Results of FHM life-cycle testing were similar, establishing a NOEC for fecundity of 0.9 ng/L, a LOEC of 4.8 ng/L. NET's inhibitory effect on gonadal development was obvious; GSI NOEC for males, 4.8 ng/L, and histological examination confirmed the presence of intersex development at elevated concentrations. Normal physical development and growth were impaired, generally at concentrations exceeding 24.1 ng/L. At exposure concentrations exceeding 4.8 ng/L, external sexual confirmation of fish was difficult; LOEC for finspot development in females, 4.8 ng/L. Sexual determination of the 97.1 ng/L exposure group was impossible; externally, all fish appeared male and internal examination revealed no gonadal development.
26

Covid-19 Educational Disruption and Delivery Redesign on Traditional BSN Student NCLEX Performance

Todt, Kendrea, Marek, Greta 14 April 2022 (has links)
Title: Covid-19 Educational Disruption and Delivery Redesign on Traditional BSN Student NCLEX Performance Purpose: The purpose of the study was to understand the educational disruption and delivery redesign (EDDR) caused by the Covid-19 pandemic on ETSU Baccalaureate of Science in Nursing (BSN) students and the impact on the nursing workforce. Student progress was evaluated by exploring student grade point average (GPA), socio economic determinants of health, Assessment Technologies Institute (ATI) Test of Essential Academic Skills (TEAS) scores and ATI comprehensive predictor scores on student first-time National Council Licensure Exam for Registered Nurses (NCLEX-RN) pass rates to evaluate the supply of nurses ready to address the national nursing shortage. Methods: A descriptive longitudinal design with a dose-response analysis was used. A purposive convenience sample of educational records of all traditional BSN students entering the program between Spring 2017 and Fall of 2020 were collected. The primary outcome variable was first-time NCLEX pass rates. COVID-related EDDR was the primary independent variable. Results: Results are forthcoming, as preliminary data is in the analysis phase. Conclusions: The COVID-19 pandemic exacerbated the nursing shortage. Undergraduate nursing education programs are integral to ameliorating the nursing shortage; however, the impact of COVID on traditional BSN education and associated outcomes was not well understood. Study results may provide foundational data to garner HRSA and other educational grants to inform future educational delivery redesigns, improve nursing education, inform educational policy, and improve nursing care delivery and patient outcomes.
27

Disruption i managementkonsultindustrin : Är det nu det händer?

Hellström, Carolina January 2020 (has links)
The Swedish authority ”Tillväxtverket” concludes in the study ”Företagens villkor och verklighet 2020” that the number one obstacle for growth for the SME segment is the lack of the right workforce and right competencies. At a third place, the lack of time for core business and strategic topics are judged the most severe obstacle for growth. Competency, business development and strategic topics are classical areas for management consulting. The academia has predicted that the industry of management consulting will be disrupted since almost ten years. Disruption of the management consulting industry could make management consultancy available to the SME market and, thus contribute to the growth of SMEs. Purpose: The purpose of this study is to identify if small operations consider digital management consulting as relevant and, by this, give an answer on whether the time is now for disruption in the management consulting industry by entering this new segment with digitalized services. Methodology: A quantitative approach is used in this study and the empirical basis is a questionnaire. The respondent-group is based on the smaller segment in the IT-industry. Participants in this study are CEOs and COOs in the industry. Conclusion: Existing research point towards a disruption in the management consulting industry. The basis for disruption is fulfilled; an existing new segment exists, services that can be digitalized exist, the digitalization will enable lower prizing and reduced time-leakage will improve profits, there is also a need for the type of services that can be provided. The quantitative study conducted in this paper to support the above points towards that there is already a usage of external and internal resources for business development amongst small firms in the industry of Professional Services. The conducted survey also contains indications of that previous experience from management consulting will make the decision maker more 4(53) inclined to further explore consulting services. There are also results in the group showing that the experienced group is more positive in relation to “Digital Management Consulting”. The results are not significant for the population and no general conclusions could be drawn from the conducted study. It is suggested to conduct a study over a period of time with a joint approach (both clients and suppliers) to further explore the foundation for disruption in the management consulting industry through a digitalization of services for small and medium sized businesses.
28

Naphthenic Acids Disrupt Courtship in Silurana tropicalis

Zhang, Wo Su 30 September 2020 (has links)
Neuroendocrine processes coordinate the behavioural, physiological, and seasonal aspects of reproduction. Some chemicals can disrupt the hypothalamus-pituitary-gonadal axis, impacting reproductive health. Naphthenic acids (NAs), the carboxylic acids in petroleum, are of emerging concern as they contaminate coastlines after oil spills and aquatic ecosystems of the Athabasca oil sands area. They are acutely toxic in fish and tadpoles and possibly endocrine disrupting at sublethal levels. I characterized courtship behaviours and disruption by NAs in the Western clawed frog, Silurana tropicalis. Courtship primarily consists of males producing low trills and achieving amplexus, a mating position where a male clasps a female. Adult frogs were exposed for five days to 20 mg/L NA, a dose low enough to not affect physical activity. In males, absolute calling activity was reduced. Other acoustic parameters such as dominant frequency, click rate, and trill length were not affected. Injecting human chorionic gonadotropin had a slight rescue effect. Vocalization and amplexus were both inhibited after exposure and restored after 2 weeks of recovery. However, calling behaviour did not predict competitive ability or mating success. In females, NA exposure reduced mating success, possibly through decreased attractiveness or receptivity. Receptivity can be indicated by attraction towards the sound of mating calls (phonotaxis), which is cryptic and subjective. I created an apparatus that measures phonotaxis by placing speakers inside traps with infrared lights to detect the time of entry. This novel method is widely applicable for low-visibility observations and studies of choice and preference. This work shows that an aquatic contaminant can reduce mating success in otherwise healthy frogs, and provides a detailed foundation for further investigation.
29

Criticality Analysis of Surface Transportation Infrastructures based on Freight Flow Network Optimization

Al Khaled, Abdullah 11 May 2013 (has links)
The purpose of this dissertation is to develop models and solution approaches to identify the critical hierarchies of railroad and surface transportation network infrastructures, and to facilitate re-routing options that will be necessary for traffic management decision makings in the event of a disaster. We focus on building mathematical models for routing/re-routing of traffic considering the congestion effects which are obvious in the disrupted networks due to disaster. Based on these models, the critical hierarchies of infrastructures are determined. For railroad, we develop two different models: the first one considers ‘unit’ train re-routing and the other one considers Train Design approach. For intermodal system, the optimization model facilitates optimal re-routing of traffic using three surface transportation modes: highway, railway and waterway, considering the congestion characteristics of each mode. For the first model of railroad routing, the optimization model optimally routes unit trains based on a minimum cost network flow formulation with nonlinear objective function. The nonlinear objective function is approximated with a piece-wise linear function to make the model computationally tractable. The second model, known as Train Design optimization, is a highly combinatorial and complex optimization problem. The developed model’s computational complexity suggests us to use heuristic solution procedures. We develop a special heuristic algorithm to route the traffic in the congested network. In this heuristic procedure, we divide the problem into two sub-problems (SPs): SP-1 is termed as Block-to-Train Assignment (BTA) problem, and SP-2 is termed as Train Routing (TR) problem. BTA problem provides a feasible solution that includes the minimum number of required trains with the pick-up and drop-off points of the blocks carried by these trains, and TR problem ensures the optimal routing of these trains. Similar to railroad, an optimization model is developed for optimal routing/rerouting of traffic using the intermodal network. It is a mixed integer programming (MIP) problem, which is not practical to solve for real-world problem instances within reasonable amount of time. Linear relaxation to this model provides a very good lower bound closer to optimal solution. Therefore, we implemented our case-study for a realworld intermodal transportation system of five U.S. states.
30

Evaluation of the Estrogenic and Osmoregulatory Impacts of Exposure to 4-Nonylphenol Pollution in the Estuarine Arrow Goby, Clevelandia ios

Johnson, Kaitlin Marie 01 June 2016 (has links) (PDF)
Recent evidence indicates that some of California’s coastal estuaries are contaminated with the chemical 4-nonylphenol (4-NP). Tissue burdens of 4-NP detected in the intertidal arrow goby (Clevelandia ios) in California are among the highest recorded worldwide, however, it remains unknown whether these fish are impacted by this 4-NP contamination. 4-NP is an established endocrine disrupting compound with estrogenic properties that can alter reproductive function. Furthermore, evidence that estrogens can modulate iono- and osmo-regulatory function in fishes implies that estuarine fishes exposed to 4-NP may also experience an impaired ability to maintain hydromineral balance. In Chapter 1 of this research, the time course of detectable xenoestrogen biomarker responses including gene transcripts encoding vitellogenins (vtgA and vtgC), choriogenins (chgL and chgHm), and estrogen receptors esr1 and esr2a were examined using quantitative real-time reverse transcription PCR (qRT-PCR) in adult male arrow gobies exposed to either 4-NP or E2. Specifically, adult gobies were treated with 4-NP at 10 μg/L (low 4-NP dose), or 4-NP at 100 μg/L (high 4-NP dose), ethanol vehicle (negative control), or 17β-estradiol (E2) at 50 ng/L (positive control) for 21 days. This 21 day exposure period was following by a 21 day depuration period to assess the time pattern of biomarker recovery. Results from these experiments indicated that 4-NP can induce increases in relative mRNA levels encoding vitellogenins, choriogenins, and estrogen receptor esr1 – but not esr2a – in the liver within 72 hrs, and that these transcriptional changes return to pre-exposure levels within 12 days of the termination of 4-NP or E2 exposure. In sum, these findings validate the use of mRNA levels for several estrogen-responsive genes as accurate biomarkers for short-term 4-NP exposure in the arrow goby. In Chapter 2, I evaluated the effects of 4-NP and E2 exposures on the osmoregulatory ability of C. ios. I exposed adult arrow gobies to 4-NP (10 μg/L or 100 μg/L) or E2 (50 ng/L) for 14 days, and then transferred the fish from a 33 ppt salinity (control) environment to either 20 ppt, or 5 ppt conditions. Whole body water content was then measured, and the relative mRNA levels for the ion channels Na+/K+/2Cl--cotransporter1 (nkcc1) and Na+/H+ exchanger-3 (nhe3), and the aquaporin water channel aquaporin-3 (aqp3) were quantified in the gill epithelium by qRT-PCR. Results showed that fish treated with 4-NP exhibited higher whole body water content, suggesting that 4-NP exposure results in excessive water uptake during hypoosmotic challenge. 4-NP treated gobies also exhibited elevated nkcc1 and reduced nhe3 and aqp3 mRNAs in the gill even prior to transfer of fish from the 33 ppt acclimation salinity. At 6 hrs after salinity transfer, transcripts encoding nkcc1 remained elevated in the gill epithelium of 4-NP treated gobies transferred to 20 ppt or maintained at 33 ppt (salinity control), while nhe3 and aqp3 mRNAs were still less abundant in gills of these fish. These findings point to impaired maintenance of water balance in gobies exposed to 4-NP, with those changes in fluid homeostasis possibly mediated in part by changes in gill ionic regulation. Taken as a entirety, the findings provided by this research reinforces accumulating data showing the potential for 4-NP to disrupt reproductive physiology in vertebrates, and points to the possibility that 4-NP may impair the ability of fish to regulate ion and water balance under changing salinity conditions.

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