• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1398
  • 1011
  • 380
  • 88
  • 62
  • 59
  • 45
  • 38
  • 21
  • 19
  • 14
  • 12
  • 11
  • 8
  • 8
  • Tagged with
  • 3655
  • 1140
  • 591
  • 492
  • 382
  • 356
  • 299
  • 251
  • 249
  • 248
  • 229
  • 224
  • 217
  • 215
  • 209
  • 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

Homeostatic Beliefs: Measurement and Future Applications

Burton, Caitlin 11 January 2010 (has links)
“Homeostatic beliefs” (HBs) denote a sense that one’s life path will remain stable in the long-term despite short-term disruptions. Two studies have been undertaken to explore whether HBs exist independent of other constructs, and to develop a scale with which to measure them. In Study 1, 158 undergraduate students completed a draft HB scale and theoretically related scales. Convergent and divergent validity were assessed with correlational and regression analyses: HBs are most strongly related to, but not redundant with, optimism, trait extraversion, and satisfaction with life. Using exploratory factor analysis, a six-item HB scale was derived. Study 2 is in progress, and will assess the construct validity of the HB scale by attempting to manipulate HBs to possibly influence individuals’ reactions to a mortality salience manipulation. We hypothesize that high HBs may buffer individuals from transient disrupting stimuli such as a mortality salience cue.
102

Validation Methodologies for Construction Engineering and Management Research

Liu, Jiali 11 July 2013 (has links)
Validation of results is an important phase in the organization of a researcher’s work. Libraries and the internet offer a number of sources for guidance with respect to conducting validation in a variety of fields. However, construction engineering and management (CEM) is an area for which such information is unavailable. CEM is an interdisciplinary field, comprised of a variety of subjects: human resources management, project planning, social sciences, etc. This broad range means that the choice of appropriate validation methodologies is critical for ensuring a high level of confidence in research outcomes. In other words, the selection of appropriate validation methodologies represents a significant challenge for CEM researchers. To assist civil engineering researchers as well as students undertaking master’s or doctoral CEM studies, this thesis therefore presents a comprehensive review of validation methodologies in this area. The validation methodologies commonly applied include experimental studies, observational studies, empirical studies, case studies, surveys, functional demonstration, and archival data analysis. The author randomly selected 365 papers based on three main perspectives: industry best practices in construction productivity, factors that affect labour productivity, and technologies for improving construction productivity. The validation methodologies that were applied in each category of studies were examined and recorded in analysis tables. Based on the analysis and discussion of the findings, the author summarized the final results, indicating such items as the highest percentage of a particular methodology employed in each category and the top categories in which that methodology was applied. The research also demonstrates a significant increasing trend in the use of functional demonstration over the past 34 years. As well, a comparison of the period from 1980 to 2009 with the period from 2010 to the present revealed a decrease in the number of papers that reported validation methodology that was unclear. These results were validated through analysis of variation (ANOVA) and least significant difference (LSD) analysis. Furthermore, the relationship between the degree of validation and the number of citations is explored. The study showed that the number of citations is positively related to the degree of validations in a specific category, based on the data acquired from the examination of articles in Constructability and Factors categories. However, based on the data acquired from the examination of articles in the year 2010, we failed to conclude that there existed significant difference between clear-validation group and unclear validation group at the 95 % confidence level.
103

A Technical Validation of The PET/SPECT/CT (Triumph) Scanner

Larsson Åkerman, Ludvig January 2011 (has links)
Positron Emission Tomography (PET) plays a very important role in the field of drugdevelopment already in the preclinical phase. This is done by using positron labeled molecules for different approaches/methodologies such as cell analysis, frozen section autoradiography, homogenate binding, organ distribution and at the end in vivo small-animal PET imaging. The technique is also used for integrated animal studies in which both functional information from PET or Single Photon Emission Tomography (SPECT) and structural information from Computed Tomography (CT) are integrated. However, significant improvements in technical aspects of the animal scanner such as resolution (under 1 mm), high sensitivity and ease of the operational procedures have affected the usage of these types of imaging. This study aims to test the technical and operational performance of the FLEX Triumph preclinical PET/SPECT/CT imaging system. Spatial resolution, sensitivity and partial volume effects have been the parameters in focus but a performance comparison between different isotopes and an in vivo mouse study has also been performed. The results show that the Triumph is capable of producing high quality images for all modalities and also high quality PET/CT fusions.
104

Improved postmortem diagnosis of <i>taenia saginata</i> cysticercosis

Scandrett, William Bradley 15 August 2007 (has links)
Bovine cysticercosis is a zoonotic disease for which cattle are the intermediate hosts of the human tapeworm <i>Taenia saginata</i>. Routine inspection measures are implemented in Canada by the Canadian Food Inspection Agency (CFIA), and similarly elsewhere, for the postmortem detection of larval parasite cysts (cysticerci) in beef destined for human consumption. Detection is based on the gross examination of traditional carcass predilection sites, although it is recognized that the parasite has no true predilection for a particular tissue or site. In order to evaluate the efficacy of the inspection protocol currently implemented in Canada, a study was undertaken to determine the distribution of <i>T. saginata</i> cysticerci in tissues of experimentally infected cattle. Forty-two cross-bred beef cattle were divided into five groups of 5-12 animals each and inoculated orally with either 10000, 5000, 1000, 100 or 10 <i>T. saginata</i> eggs obtained from cases of human taeniosis in Thailand. From 47 to 376 days post-inoculation (DPI), ten animals inoculated with 5000 eggs were killed and the carcasses partitioned into 31 tissue sites. These consisted of the traditionally inspected tissue sites of heart, masseter and pterygoid muscles, tongue, oesophagus, and diaphragm (membranous and crura); as well as non-traditional sites of lung, liver and 20 additional muscles or muscle groups. After the routine inspection for cysticerci of traditional tissue sites, tissues from all sites were each cut into approximately 0.5 cm thick slices and the total number of parasitic cysts and cyst density (cysts/g of tissue) were determined for each site. Traditional sites were similarly evaluated for the remaining 32 animals that were killed between 117 and 466 DPI. Sites were ranked based on cyst density. In the animals for which non-traditional sites were also evaluated, no sites had higher cyst densities than those traditionally inspected. When only traditional sites for all animals were compared, the heart ranked highest overall, although not significantly different from masseter, and was the most frequently affected site. The traditional site of oesophagus was among the poorest of all sites for detection of cysticerci. The heart was confirmed as the site of choice for detection of bovine cysticercosis based on high cyst density and frequency of infection. There was also enhanced visibility of parasite lesions in the heart due to the relatively early degeneration and resultant gross pathology that occurs in cardiac muscle. More thorough examination of the heart is recommended during post-mortem inspection for this parasite, particularly when examining animals from an infected herd. <p>Currently, confirmation by CFIA of suspect cysticerci recovered during meat inspection relies on gross, stereomicroscopic, or standard histological examination. Although degenerating cysticerci are more likely to be detected and submitted for diagnosis, they often cannot be definitively identified by these methods. A recently developed monoclonal antibody-based immunohistochemical (IHC) assay for post-mortem diagnosis of this parasite was optimized and standardized. The IHC method was compared to the currently used histological assay using 169 degenerated known-positive <i>T. saginata</i> cysticerci collected from the experimental infections in the first study and from field submissions, and known-negative specimens and lesions of various etiologies from non-infected cattle. The use of the IHC assay identified significantly more known-positive bovine cysticerci (91.7%) than the histological method (38.5%), and non-specifically reacted only with the other cestode species examined. Since <i>T. saginata</i> is the only larval cestode typically found in the muscle of cattle, this cross-reactivity is not significant and the IHC assay will be a useful tool for the identification of lesions caused by degenerated bovine cysticerci.<p>This research provided evidence to support changes to the current post-mortem inspection, detection and diagnostic procedures and will contribute to more effective and efficient control of bovine cysticercosis.
105

Feil-metoden - En deltagande observation

Berg, Pontus January 2011 (has links)
No description available.
106

Transitive and Symmetric Nonrigid Image Registration

Chou, Yi-Yu 12 April 2004 (has links)
The main topic of this thesis is nonrigid image registration for medical applications. We start with an overview and classification of existing registration techniques. We develop a general nonrigid image registration algorithm. It uses spline functions to describe the deformation and uses multi-scale strategy to search for the optimal transformation. Then we present a new registration operator that is transitive and symmetric. We investigate the theoretical implication of these properties and apply this operator to the registration of sequences of MR cardiac images. In the second part of the thesis, two methods, one 2D and one 3D, for validation of nonrigid image registration algorithms are proposed and compared to a manual validation strategy. Both methods provide pairs of deformed images as well as corresponding true displacement fields with known accuracy. Nonrigid registration algorithms can be run on the pairs of images and their outputs can be compared to the true displacement fields that were generated manually by five observers. While these phantom validation studies do not provide physically correct deformations, they are certainly a useful way to test the algorithm's ability to recover various deformation patterns.
107

Characterization and evaluation of Escherichia coli biotype I strains for use as surrogates for enteric pathogens in validation of beef carcass interventions

Cabrera-Diaz, Elisa 15 May 2009 (has links)
Antimicrobial interventions implemented in slaughter establishments for the reduction of enteric pathogens on beef carcasses must be validated to demonstrate efficacy under commercial operation conditions. Validation studies can be conducted using surrogates which are nonpathogenic organisms that respond to a particular treatment in a manner equivalent to a target pathogen. The purpose of this study was to identify surrogates for enteric pathogens to validate antimicrobial interventions on beef carcasses. The growth, attachment, resistance properties as well as the response to interventions on beef carcasses of nonpathogenic fluorescent protein-marked E. coli strains were evaluated and compared to E. coli O157:H7 and Salmonella strains. Growth curves were performed in tryptic soy broth at 37°C and it was demonstrated that in general, growth parameters were not different among surrogates and target pathogens. Thermal resistance was compared in phosphate buffered saline (PBS) at 55, 60 and 65°C; D-values of surrogates were not different or were higher than those of target pathogens. The acid resistance of surrogates was not different to that of E. coli O157:H7 in PBS acidified with lactic acid at pH 2.5, 3.0 and 3.5. Some Salmonella serotypes were found to be less acid resistant than the surrogates. Survival of surrogates after storage at low temperatures (4°C and -18°C) was not different or was longer than survival of E. coli O157:H7 and Salmonella. Additionally, the cell surface hydrophobicity and attachment to beef carcasses surfaces was not different among surrogates and pathogens. Antimicrobial interventions were applied on carcass surfaces under laboratory controlled conditions. After application of hot water washes, D-values were not different among surrogates and pathogens, while no differences were observed in log reductions (CFU/cm2) among surrogates and pathogens when 2% L-lactic acid sprays at 25 and 55°C were applied, regardless of the temperature and volume of the acid solution. The response of surrogates to water washes and lactic acid sprays on beef carcasses was also evaluated in commercial slaughter facilities. Reductions of surrogates were not different to those of aerobic plate count, coliforms and E. coli. However, the surrogates showed less variation and provided more consistent results than traditional indicators.
108

Validation of Sanitation Procedures to Prevent the Cross Contact with Allergens During the Processing of Pork Products

Winkler, Dawna 2009 August 1900 (has links)
This study was conducted to develop and validate cleaning procedures for different processing equipment of varying complexity and to determine the efficacy of two different allergen tests. Following introduction of selected allergens to processing equipment, two treatments were applied - water wash or scrub/sanitize ? and a no clean was also evaluated. The equipment used consisted of a slicer, grinder, injector, vacuum tumbler, and plastic lugs. To introduce the allergen to the slicer, nine ready-to-eat hams were used. One hundred twenty-two kilograms of pork trim were ground, and a milk allergen was incorporated into the meat. The injector was contaminated with a food allergen by injecting boneless pork loins with a marinade containing soy flour. The slicer, grinder, injector, tumbler, and lugs were then subjected to randomized treatments. The results showed that the water wash and scrub/sanitize treatments did not differ significantly among the pieces of equipment tested. This study supported that both water wash and scrub/sanitize treatments can effectively removed allergens to a level below the industry threshold of 5 ppm.
109

Validation of Hot Water and Lactic Acid Sprays for the Reduction of Enteric Pathogens on the Surface of Beef Carcasses

Wright, Kyle D. 2009 December 1900 (has links)
Escherichia coli O157:H7 and Salmonella have emerged as the most common foodborne enteric pathogens causing human illness from the consumption of beef. By mandate of the U.S. Department of Agriculture (USDA), Food Safety and Inspection Service (FSIS), the industry has implemented a Hazard Analysis and Critical Control Points (HACCP) system that utilize intervention technologies for controlling, preventing, and/or reducing enteric pathogens. In addition, USDA-FSIS has mandated that each facility must validate, monitor, and verify the effectiveness of each intervention implemented to eliminate E. coli O157:H7 and Salmonella. For this study, microbial decontamination interventions at two beef slaughter facilities were validated to demonstrate effectiveness in eliminating or reducing enteric pathogens. The facilities selected utilized either a lactic acid spray treatment or a combination of hot water followed by a lactic acid treatment. At both facilities, mesophilic plate counts (MPC) were significantly (P < 0.05) reduced, and E. coli and coliforms were eliminated below detectable limits at both facilities. No Salmonella positive samples were detected after either facility's intervention sequence. The framework used in this research to validate interventions can also be utilized in the future for yearly verification of the effectiveness of each intervention.
110

The Method of Manufactured Universes for Testing Uncertainty Quantification Methods

Stripling, Hayes Franklin 2010 December 1900 (has links)
The Method of Manufactured Universes is presented as a validation framework for uncertainty quantification (UQ) methodologies and as a tool for exploring the effects of statistical and modeling assumptions embedded in these methods. The framework calls for a manufactured reality from which "experimental" data are created (possibly with experimental error), an imperfect model (with uncertain inputs) from which simulation results are created (possibly with numerical error), the application of a system for quantifying uncertainties in model predictions, and an assessment of how accurately those uncertainties are quantified. The application presented for this research manufactures a particle-transport "universe," models it using diffusion theory with uncertain material parameters, and applies both Gaussian process and Bayesian MARS algorithms to make quantitative predictions about new "experiments" within the manufactured reality. To test further the responses of these UQ methods, we conduct exercises with "experimental" replicates, "measurement" error, and choices of physical inputs that reduce the accuracy of the diffusion model's approximation of our manufactured laws. Our first application of MMU was rich in areas for exploration and highly informative. In the case of the Gaussian process code, we found that the fundamental statistical formulation was not appropriate for our functional data, but that the code allows a knowledgable user to vary parameters within this formulation to tailor its behavior for a specific problem. The Bayesian MARS formulation was a more natural emulator given our manufactured laws, and we used the MMU framework to develop further a calibration method and to characterize the diffusion model discrepancy. Overall, we conclude that an MMU exercise with a properly designed universe (that is, one that is an adequate representation of some real-world problem) will provide the modeler with an added understanding of the interaction between a given UQ method and his/her more complex problem of interest. The modeler can then apply this added understanding and make more informed predictive statements.

Page generated in 0.0443 seconds