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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.

On the Effect of False Positives in Group and Individual Testing of Blood for the Presence of HIV

Malina, Regina 12 1900 (has links)
In this thesis we develop a model which allows us to evaluate Modified Dorfman's and Modified Sterrett's group testing procedures in the presence of false positive classification error that can be used for screening blood for HIV. Performance measures derived are the expected number of tests per sample and the corresponding coefficient of variation. The procedures differ from the original ones by the fact that groups and samples are retested certain number of times before they are classified as positive. Modified Individual testing procedure and the procedure currently used by Canadian Red Cross are also evaluated and all four testing strategies are compared. Numerical analysis illustrates that group testing is more efficient than alternatives. / Thesis / Master of Science (MSc)

Identifying and documenting false positive patterns generated by static code analysis tools

Reynolds, Zachary P. 18 July 2017 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Static code analysis tools are known to flag a large number of false positives. A false positive is a warning message generated by a static code analysis tool for a location in the source code that does not have any known problems. This thesis presents our approach and results in identifying and documenting false positives generated by static code analysis tools. The goal of our study was to understand the different kinds of false positives generated so we can (1) automatically determine if a warning message from a static code analysis tool truly indicates an error, and (2) reduce the number of false positives developers must triage. We used two open-source tools and one commercial tool in our study. Our approach led to a hierarchy of 14 core false positive patterns, with some patterns appearing in multiple variations. We implemented checkers to identify the code structures of false positive patterns and to eliminate them from the output of the tools. Preliminary results showed that we were able to reduce the number of warnings by 14.0%-99.9% with a precision of 94.2%-100.0% by applying our false positive filters in different cases.

Understanding the Effect of Morphine on the Accuracy of Nuclear Hepatobiliary Imaging Through a Case Study

Dhadvai, Sandeep 08 May 2017 (has links)
A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Many patients present with upper abdominal pain and receive some type of pain relieving therapy prior to gallbladder imaging. The physiologic effect of morphine and other analgesics on gallbladder function has been well‐studied. What hasn’t been studied as much are the implications on clinical practice and the decision about whether morphine is the best option to use in suspected chronic gallbladder disease. This case study serves to illustrate the influence of morphine in a patient who underwent both inpatient and outpatient hepatobiliary scintigraphy with dramatically different results. This case study perfectly shows the considerations that must be taken when using morphine because it eliminates many confounding variables; the only difference in the patient at the time of initial and subsequent presentation was the presence of morphine.

Factors influencing accuracy of referral and the likelihood of false positive referral by optometrists in Bradford, United Kingdom

Davey, Christopher J., Scally, Andy J., Green, Clare, Mitchell, E.S., Elliott, David B. 21 November 2015 (has links)
Yes / Aims: Levels of false positive referral to ophthalmology departments can be high. This study aimed to evaluate commonality between false positive referrals in order to find the factors which may influence referral accuracy. Methods: In 2007/08, a sample of 431 new Ophthalmology referrals from the catchment area of Bradford Royal Infirmary were retrospectively analysed. Results: The proportion of false positive referrals generated by optometrists decreases with experience at a rate of 6.2% per year since registration (p < 0.0001). Community services which involved further investigation done by the optometrist before directly referring to the hospital were 2.7 times less likely to refer false positively than other referral formats (p = 0.007). Male optometrists were about half as likely to generate a false positive referral than females (OR = 0.51, p = 0.008) and as multiple/corporate practices in the Bradford area employ less experienced and more female staff, independent practices generate about half the number of false positive referrals (OR = 0.52, p = 0.005). Conclusions: Clinician experience has the greatest effect on referral accuracy although there is also a significant effect of gender with women tending to refer more false positives. This may be due to a different approach to patient care and possibly a greater sensitivity to litigation. The improved accuracy of community services (which often refer directly after further investigation) supports further growth of these schemes. / This study was funded by the University of Bradford.


Steffens, Rachel Fancher 01 January 2008 (has links)
Benign breast biopsy (BBB) can be a stressful experience for many women. Few studies have examined the specific aspects of the BBB more and less distressing. However, no research studies have examined demographic and clinical variables as they relate to distress associated with specific aspects of the BBB or the informational interests of women following a BBB. This study evaluated the magnitude of distress associated with each aspect of the BBB (additional mammography, waiting for the results of the mammography, being informed of needing a biopsy, etc.) as well as the clinical (family history of BC in first degree relative, history of BBB, and type of biopsy) and demographic (age and education) variables as correlates of distress associated with each aspect of a BBB. Additionally, we examined health information interests in women following a BBB and the manner in which women preferred to have this health information communicated.

The Assessment of Escherichia coli as an Indicator of Microbial Quality of Irrigation Waters used for Produce

Brassill, Natalie A. January 2013 (has links)
Escherichia coli is a bacterial species that lives in the gut of all warm-blooded animals, fish, birds as well as reptiles and is commonly used as an indicator of fecal contamination in water. This project assessed currently used culture based media for the detection of E. coli in irrigation waters used in Arizona and California, and will present recommendations towards the most reliable media for the evaluation of irrigation waters used for produce. Currently, no microbial indicator standards exist for irrigation waters used for produce production in the United States. The produce industry suggests that the recreational water standard guideline (126 E. coli/100 ml) established by the United States Environmental Protection Agency (USEPA) be used. There is concern that the false positive rate of E. coli detection may be high in these waters giving false indications of the level of risk from enteric pathogens. This project evaluated three commercially available media for E. coli detection to test irrigation waters from three agricultural areas (Yuma and Maricopa, AZ and Imperial Valley, CA) and then assessed false positive rates by utilizing Polymerase Chain Reaction (PCR) and DNA sequencing of the bacterial isolates. The media that were chosen for evaluation were (1) MI Agar, (2) IDEXX Colilert Quanti-Tray® and (3) m-ColiBlue24® broth, all evaluation media accepted by the USEPA and widely used in the monitoring of irrigation water quality by the produce industry. Four hundred and fifty 1-L irrigation water grab samples were collected between March 2012 and November 2012. The samples were analyzed for both cultural counts and water quality parameters including temperature, salinity and pH. Isolates positive and negative for E. coli were then selected and assessed utilizing PCR and DNA sequencing. The false positive rate of each method was found to be high, with MI Agar, m-ColiBlue24® broth and the IDEXX Colilert Quanti-Tray® at an accuracy of 67%, 72%, and 51% respectively. A false positive result is reported when presumptive E. coli sub cultured from the media is found to be non-E. coli through molecular analysis. Overall the IDEXX Colilert Quanti-Tray® performed at a greater rate of accuracy than the other two media evaluated, however, high false positive rates may lead to inaccurate assessment of water quality.

The Epidemiology and Health System Impact of Medium-Chain Acyl-CoA Dehydrogenase Deficiency Among Affected Children and Those with False Positive Newborn Screening Results in Ontario, Canada

Karaceper, Maria D January 2014 (has links)
Objective: To describe the epidemiology and health system impact of medium-chain acyl-CoA dehydrogenase deficiency (MCADD) in Ontario. Methods: Following a review of methods to estimating robust health event rates for small populations, this study described health services use among infants diagnosed with MCADD or received a false positive newborn screening result for MCADD from April 2006 through March 2010. Each cohort was compared with screen negative infants by linking to databases encompassing physician visits, emergency department care, and hospitalizations. Results: Relative to comparison birth cohorts, children with MCADD (n=40) experienced significantly higher rates of all health service types, regardless of age at the time of visit; infants with false positive results for MCADD (n=43) experienced significantly higher rates of physician visits and hospitalizations in the first year of life only. Conclusion: This study makes an important contribution to the limited existing research describing the health system impact of rare diseases.

Lowering the Number of False Positive Responses to Electric Pulp Tests by Qualifying Patient Response

Lee, Katherine JS 01 January 2015 (has links)
The electric pulp test (EPT) has been shown to be a valuable tool in assessing pulp vitality. One of its drawbacks, however, is its high number of false positives. The purpose of this study was to determine if qualifying the type of sensation elicited by the test could lower the percentage of false positive responses. A retrospective chart review of an eleven-month period was conducted, examining all patients with necrotic teeth tested with the EPT. Of 189 teeth, when the patient responded to EPT at first sensation 23.3% of teeth were incorrectly identified as vital. When the patient was asked to respond only if they felt an uncomfortable sensation, the false positive rate was lowered to 8.5%, a statistically significant difference. No association was found between the teeth reclassified as necrotic and age, gender, type of tooth, or number of canals.

Change Starts With Journal Editors: In Response to Makel (2014)

McBee, Matthew T., Matthews, Michael S. 01 February 2014 (has links)
The editors of the Journal of Advanced Academics comment on Makel (2014). The replicability crisis in psychology is summarized in terms of three focal issues: the "file drawer" problem, lack of replication studies, and the null hypothesis significance testing paradigm. The authors argue that journal editors are uniquely positioned to address all three of these problems via the adoption of new policies for review and publication.

Development of an Innovative Detection Technology for Escherichia Coli O157:H7

Gu, Qian 12 May 2012 (has links)
Escherichia coli O157:H7 detection in food is conducted mainly by DNA/PCR, immunoassay or conventional methods. However, all the methods require multiple incubation steps. Antibiotic and isolation agars were found as the main factors that lead to false-positive results. An improved rapid detection method was developed by decreasing detection time and enhancing easiness of detection without the need for any analytical instrumentation. A combination of selective ingredients and temperature was utilized to allow the growth of Escherichia coli O157:H7 in the detection. The detection method minimized the effects of the main false positive bacteria, Pseudomonas spp. and Enterobacter spp. The sensitivity, specificity and accuracy of the 24h detection method in foodstuffs were 96.2%, 99.6% and 97.0%, respectively when the original inoculation was 10-100cfu/g in food. This method can be utilized to detect Escherichia coli O157:H7 in foodstuffs more rapidly, economically and conveniently when compared to the methods that are currently used.

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