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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.
11

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.
12

PARENTS' KNOWLEDGE OF AND EXPERIENCES WITH THE OHIO NEWBORN SCREENING

Daniels, Molly Serena 15 September 2002 (has links)
No description available.
13

Verktyg för säker kodning : En jämförande studie / Tools for secure coding : A comparative study

Fransson, Robin, Hiltunen, Tommi January 2023 (has links)
Bakgrund I dagens programvara finns det problem som försämrar kvaliteten hos system och ökar kostnaderna. Det är viktigt att tänka på säkerheten redan under programmeringsfasen för att underlätta underhåll. The Open Web Application Security Project (OWASP) erbjuder dokument, verktyg och projekt för att skapa och underhålla produkter på ett säkrare sätt. För att upptäcka säkerhetsproblem i koden kan verktyg för Static Application Security Testing (SAST) användas. SAST-verktyg kan rapportera både false negatives och false positives, därför är det viktigt att undersöka hur precisa verktygen är i sin rapportering. Syfte Studien ämnar kartlägga vilka SAST-verktyg utvecklare kan ta hjälp av för att skriva säkrare kod. Undersökningen skall även jämföra hur bra de är på att hitta sårbarheter i kod och hur stort antal false positives de rapporterar. Metod En sökning gjordes för att samla information om vilka SAST-verktyg som finns tillgängliga och en lista sammanställdes med krav för att kunna genomföra likvärdiga tester. För att utföra testerna användes kod med planterade sårbarheter och resultaten från testerna genererade kvantitativa data som fördes in i en tabell. Resultat I studiens resultat kartlades tolv SAST-verktyg. Från dessa valdes HCL AppScan CodeSweep, Snyk och SonarLint ut för vidare testning. Därefter beräknades recall, precision och false positives för verktygen. Snyk hade 71,43% på både recall och precision och 33,33% false positives. HCL AppScan CodeSweep hade 28,57% på recall, 57,14% på precision och 25% på false positives. SonarLint hittade inga sårbarheter och blev därav inte analyserat. Slutsatser Studien kartlade tolv olika SAST-verktyg och valde tre för likvärdiga tester av JavaScript i Visual Studio Code. Resultaten visade att Snyk presterade bäst gällande rapportering av sårbarheter och hade högre resultat gällande precision, medan HCL AppScan CodeSweep presterade bäst på att undvika false positives. Överlag anses Snyk vara studiens bästa SAST-verktyg då det hade högst resultat på både recall och precision. / Background In today's software, there are issues that degrade system quality and increase costs. It is important to consider security during the programming phase to facilitate maintenance. The Open Web Application Security Project (OWASP) provides documentation, tools, and projects to create and maintain products in a more secure manner. To detect security issues in the code, tools for Static Application Security Testing (SAST) can be used. SAST-tools can report both false negatives and false positives, so it is important to investigate the accuracy of the tools in their reporting. Aim The study aims to map which SAST-tools developers can utilize to write more secure code. The investigation will also compare their effectiveness inidentifying vulnerabilities in code and the numberof false positives they report. Method A search was conducted to gather information on available SAST-tools, and a list was compiled with requirements to perform equivalent tests. To carry out the tests, code with planted vulnerabilities was used, and the test results generated quantitative data that were entered into a table. Results The study's results mapped twelve SAST-tools. From these, HCL AppScan CodeSweep, Snyk, and SonarLint were selected for further testing. Then, the recall, precision, and false positives were calculated for the tools. Snyk achieved 71.43% for both recall and precision and had 33.33% false positives. HCL AppScan CodeSweep achieved 28.57% recall, 57.14% precision, and 25% false positives. SonarLint did not find any vulnerabilities and was therefore not analyzed. Conclusions The study surveyed twelve different SAST-tools and selected three for tests on JavaScript in Visual Studio Code. The results showed that Snyk performed the best in terms of vulnerability reporting and achieved higher precision results, while HCL AppScan CodeSweep excelled in avoiding false positives. Overall, Snyk is considered the best SAST-tool in the study as it had the highest results in both recall and precision.
14

Evaluation du dépistage du cancer du sein par mammographie : estimation du surdiagnostic, de la participation des femmes après un résultat faux positifs et de l'incidence des cancers de l'intervalle / Evaluation of breast cancer screening with mammography : estimation of overdiagnosis, of participation rates after a false positive result, and of the incidence of interval cancer

Seigneurin, Arnaud 03 October 2011 (has links)
L'intérêt du programme de dépistage du cancer du sein par mammographie résulte de la balance entre la réduction de la mortalité et les effets indésirables du programme. L'objectif de ce travail était d'évaluer trois aspects du programme de dépistage dans le département de l'Isère. Nous avons utilisé une méthode Approximate Bayesian Computation pour estimer le surdiagnostic lié au dépistage par mammographie de cancers non évolutifs. Ils représentaient respectivement 1,5% (IC95% : 0,3% – 2,9%) et 28,0% (IC95% : 2,2% – 59,8%) des cancers invasifs et in situ diagnostiqués. Nous avons réalisé une revue de la littérature des méthodes d'estimation du surdiagnostic et montré sur des données simulées que les méthodes basées sur les taux d'incidence annuels étaient les moins sensibles aux biais. Par ailleurs, l'incidence des cancers de l'intervalle était inférieure lorsque les mammographies étaient réalisées avec deux clichés par sein au lieu d'un seul, aussi bien à 12 que à 24 mois. Enfin, l'exclusion du diagnostic de cancer après la réalisation d'une imagerie supplémentaire, d'une biopsie ou un suivi radiologique diminuait la participation lors de la prochaine invitation au dépistage organisé. En conclusion, l'intérêt du programme de dépistage du cancer du sein par mammographie n'est pas remis en cause avec 1,4 décès évité pour un cancer surdiagnostiqué (in situ ou invasif). / The public health interest of the breast cancer screening program depends on a balance between the reduction of mortality and the side effects of the program. The goal of our work was to evaluate three particular issues of the screening program in Isère, France. We used an Approximate Bayesian Computation method to estimate overdiagnosis resulting from the detection of non progressive breast cancer. Our estimates were 1.5% (95%CI : 0.3% – 2.9%) et 28.0% (95%CI : 2.2% – 59.8%) respectively for invasive and in situ cancers. We realized a review of the methods used to estimate overdiagnosis and we found on simulated data that annual incidence methods were the least influenced by biases. In addition, the incidence of 12 months or 24 months interval cancers was lower with 2-view than with 1-view mammographies. Finally, excluding breast cancer after additional imaging evaluation, clinical and radiological follow-up, or surgical biopsy motivated by abnormal findings on index mammograms results in uniformly decreased subsequent attendance in the routine screening program. To conclude, the interest of the breast cancer screening program was not modified by our results with 1.4 life saved for one overdiagnosed breast cancer (in situ and invasive).
15

An Evaluation of current IDS

Fernandez, Maria del Mar, Porres, Ignacio January 2008 (has links)
<p>With the possibility of connecting several computers and networks the necessity of protecting the whole data and machines from attackers (hackers) that try to get some confident information to use for their own benefit or just destroy or modify valuable information was born. At this point IDS appears to help users, companies or institutions to detect when they are getting compromised. This thesis will cover two main parts: the first one consists of an intense research study about the world of IDS and its environment. Subsequently, we will conclude this part with some points where IDS still needs to be questioned and show up desirable requirements for “the perfect” intrusion detection system. This “perfect” adjective can of course be discussed variously. The second part of the thesis approaches the implementation of the most used open source IDS: Snort. Some basic attacks on the machine where Snort is installed will be performed in order to make the future user see what kind of protection it ensures and the usability of this. There is a brief discussion about two of the main challenges in IDS will follow: analyzing big amounts of packets and encrypted traffic. Finally there are conclusions for a safe computer environment as well as the suggestion that some skilled programmer should give Snort a more friendly interface for every kind of users and a built in programme package which includes webserver, database and other libraries that are needed to run it properly with all its features.</p>
16

Ethyl glucuronide, a new biochemical marker for acute alcohol intake : studies on possible causes for false-negative or false-positive results /

Dahl, Helen, January 2006 (has links)
Lic.-avh. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 3 uppsatser.
17

Utility of Considering Multiple Alternative Rectifications in Data Cleaning

January 2013 (has links)
abstract: Most data cleaning systems aim to go from a given deterministic dirty database to another deterministic but clean database. Such an enterprise pre&ndash;supposes that it is in fact possible for the cleaning process to uniquely recover the clean versions of each dirty data tuple. This is not possible in many cases, where the most a cleaning system can do is to generate a (hopefully small) set of clean candidates for each dirty tuple. When the cleaning system is required to output a deterministic database, it is forced to pick one clean candidate (say the "most likely" candidate) per tuple. Such an approach can lead to loss of information. For example, consider a situation where there are three equally likely clean candidates of a dirty tuple. An appealing alternative that avoids such an information loss is to abandon the requirement that the output database be deterministic. In other words, even though the input (dirty) database is deterministic, I allow the reconstructed database to be probabilistic. Although such an approach does avoid the information loss, it also brings forth several challenges. For example, how many alternatives should be kept per tuple in the reconstructed database? Maintaining too many alternatives increases the size of the reconstructed database, and hence the query processing time. Second, while processing queries on the probabilistic database may well increase recall, how would they affect the precision of the query processing? In this thesis, I investigate these questions. My investigation is done in the context of a data cleaning system called BayesWipe that has the capability of producing multiple clean candidates per each dirty tuple, along with the probability that they are the correct cleaned version. I represent these alternatives as tuples in a tuple disjoint probabilistic database, and use the Mystiq system to process queries on it. This probabilistic reconstruction (called BayesWipe&ndash;PDB) is compared to a deterministic reconstruction (called BayesWipe&ndash;DET)&mdash;where the most likely clean candidate for each tuple is chosen, and the rest of the alternatives discarded. / Dissertation/Thesis / M.S. Computer Science 2013
18

An Evaluation of current IDS

Fernandez, Maria del Mar, Porres, Ignacio January 2008 (has links)
With the possibility of connecting several computers and networks the necessity of protecting the whole data and machines from attackers (hackers) that try to get some confident information to use for their own benefit or just destroy or modify valuable information was born. At this point IDS appears to help users, companies or institutions to detect when they are getting compromised. This thesis will cover two main parts: the first one consists of an intense research study about the world of IDS and its environment. Subsequently, we will conclude this part with some points where IDS still needs to be questioned and show up desirable requirements for “the perfect” intrusion detection system. This “perfect” adjective can of course be discussed variously. The second part of the thesis approaches the implementation of the most used open source IDS: Snort. Some basic attacks on the machine where Snort is installed will be performed in order to make the future user see what kind of protection it ensures and the usability of this. There is a brief discussion about two of the main challenges in IDS will follow: analyzing big amounts of packets and encrypted traffic. Finally there are conclusions for a safe computer environment as well as the suggestion that some skilled programmer should give Snort a more friendly interface for every kind of users and a built in programme package which includes webserver, database and other libraries that are needed to run it properly with all its features.
19

Evaluation of false positive results in microbial inhibitor tests for screening antibiotics in goat milk

Romero Rueda, Tamara 31 March 2015 (has links)
Goat milk is primarily destined for the production of fermented products, in particular cheese. Therefore, the control of antibiotic residues in milk is of great importance, since these could have negative repercussions on technological properties of the milk as well as on the health of consumers. In milk quality control programs, microbial inhibitor tests are widely applied to detect antibiotics during the screening stage. However, tests are non-specific and may be affected by substances other than antimicrobials which could inhibit the growth of the test micro-organism, causing false positive results. The aim of this thesis was to evaluate the interference, related to the presence of different contaminants in goat milk, on the response of microbial inhibitor tests commonly used in Spain to detect antibiotics (BRT MRL, Delvotest SP-NT MCS and Eclipse 100 tests). The influence of the physicochemical characteristics of goat milk on the false positive outcomes in microbial screening tests was also investigated. The suitability of microbial inhibitor tests for screening antibiotics in colostrum secretions was studied by analysing antibiotic-free colostrum and milk samples from forty-three Murciano-Granadina goats, collected every 12 hours during the first week post-partum. Microbial inhibitor tests were not suitable for the analysis of goat colostrum because they presented a high percentage of doubtful and positive results (up 37.2% in the 36 hours after partum). To evaluate the effect of caprine colostrum on the microbial test response, antimicrobial-free goat milk spiked with different concentrations of colostrum was analysed to calculate the inhibitory concentrations producing 5% of positive results. The highest interferences were obtained for the addition of colostrum from 12 to 24 hours post-partum and the colostrum concentrations producing 5% positive results were between 5.1 and 34.6%. The BRT MRL was the test the most affected. In another study, the interference of detergents and disinfectants used for the cleaning of milking equipment and milk storage tanks of dairy farms was investigated. Antimicrobial-free goat milk was spiked with eight concentrations of different cleaning products (5 acid, 5 alkaline, 5 domestic washing-up liquids, and 1 disinfectant) and analysed using microbial screening tests. The presence of acid detergent and disinfectant based on sodium hypochlorite in goat milk did not affect the microbial test response. However, alkaline detergents at concentrations ≥ 1 ml/l could lead to false positive results in microbial inhibitor tests (up to 16.7%) and from 4 ml/l on 100% positive results were obtained. Regarding the products used for home use, and those used on farms and small size dairies, washing-up liquid containing sodium laureth sulphate and ethanol had the greatest effects on microbial inhibitor tests, even starting from a relatively low concentration (1 ml/l). On the other hand, the presence of a relatively low concentration of detergents in goat milk (0.5 ml/l) slightly modified the detection capability of the microbial inhibitor tests for amoxicillin, ampicillin, benzylpenicillin, and cloxacillin, although the detection of these drugs at MRL (safe level) was not compromised. Antiparasitic agent residues in goat milk could be another possible cause of false positive results in microbial screening tests. An in vitro study to evaluate the effect of seven parasiticides commonly used in dairy goats was carried out. Further two studies, where albendazole and ivermectin were applied to two groups of dairy goats in lactation were performed. It should be noted that the parasiticide ivermectin is banned for the treatment of animals producing milk for human consumption, although its inclusion in this study was considered interesting to understand the potential effect of their residues in milk, in the event the practice was performed illegally. In the in vitro study, raw antibiotic-free milk from goats was spiked individually with eight different concentrations of albendazole, closantel, diclazuril, febendazole, levamisole, diazinon, and ivermectin. The microbial inhibitor test results showed a great variability according to the test and the drug under study. Of the tests considered, the BRT MRL test was the most sensitive to antiparasitic agents, with the lowest concentrations of antiparasitic agent causing 5, 10, and 50% of positive results. Generally, closantel and diazinon were the antiparasitic agents that produced higher interferences in all tests, since low concentrations already resulted in positive results, while only higher concentrations of diclazuril and ivermectin showed an inhibitory effect. To evaluate the effect of albendazole residues on the microbial inhibitor test response, eighteen healthy Murciano-Granadina goats in mid-lactation were treated with a single oral administration of the commercially available albendazole registered for dairy sheep (7.5 mg/kg b.w. of active compound) with a withdrawal period of 4 days for milk production in ovine. Albendazole and its metabolite residues in goat milk after under cascade treatment were not detected above MRL from the third day post-administration. However, a high occurrence of non-compliant results was obtained for the BRT MRL test during the first six days after treatment, suggesting that factors related to the albendazole application other than the drug concentration are able to affect the microbial inhibitor test response in some cases. Regarding the ivermectin study, twenty-eight Murciano-Granadina goats infested with Sarcoptes scabiei var. caprae were treated with a subcutaneous injection of ivermectin (200 μg/kg b.w.), with a second dose applied seven days after the first treatment. Drug residues in goat milk were recorded during the first fifteen days of the experiment with concentrations ranging from 8.13 to 24.25 ng/ml. In addition, all the microbial screening tests seem to be affected by the ivermectin treatment, with BRT MRL the most affected (20%) compared with Delvotest SP-NT MCS and Eclipse 100 (6.6 and 5.7%, respectively). These positive results cannot be associated with the ivermectin concentration in goat milk, as the concentrations measured were lower than the inhibitory concentrations as reported in a previous in vitro study for these microbial tests. Thus, as suggested by some authors, interferences could be related to changes or alterations caused by the application of the parasiticide agent or by the parasitic disease itself, which could affect the immune response of the animals favouring the presence of inhibitory substances in milk. The study of the effect of the goat milk composition on the specificity (rate of false positive results) of microbial inhibitor tests for screening antibiotics was also considered. Thus, individual goat milk samples (n=200) were analysed by microbial inhibitor tests using both visual and instrumental classification of the test results. The highest specificity values were obtained for the instrumental interpretation of the test results (94-99% vs 90-96%) due to the occurrence of samples with intermediate colorations (green-yellow, yellow-blue) making the visual classification more difficult and subjective. A relation was found between positive results in BRT MRL and Eclipse 100 tests and an elevated fat content in the goat milk. Positive outcomes in Eclipse 100 were associated with the butyric acid concentration in the milk. Further, the Delvotest SP-NT MCS test response was affected by elevated pH values, high lactoferrrin and myristoleic acid concentrations in the goat milk. This percentage of positive results could be minimized by a pre-treatment prior to microbial inhibitor test analysis, such as fat removal by centrifugation (3,100 g for 10 min at 4 ºC) and/or heating (80 ºC for 10 min). Undoubtedly, improvements on the specificity of the microbial inhibitor tests for screening antibiotics in goat milk are desirable to avoid the destruction of milk compliant for human due to the occurrence of false positive results. The related financial losses affect farmers and dairies. However, it should be noted that the presence of contaminants in goat milk could be avoided by applying good farming practices designed to ensure that milk is obtained from healthy animals under proper hygienic conditions so ensuring the food safety of goat milk and related dairy products. / Romero Rueda, T. (2015). Evaluation of false positive results in microbial inhibitor tests for screening antibiotics in goat milk [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48552 / TESIS
20

False Positives II – Chlorophenols identification towards HPLC-DAD-MS analysis compared with ISO 17070:2015 technique

Defeo, Gustavo Adrián, Borgheresi, Miria, De Cicco, Manila, Carpignani, Bianca 28 June 2019 (has links)
Content: The restriction of certain dangerous substances according to REACH (Registration, Evaluation, Authorisation of Chemicals as well as the Restricted Substances Lists (RSL) requirements promoted by various renowned brands obliges tanneries to everyday more numerous analysis with undesired conflictual situations on false positive tests results. This situation is worsened by the voluntary reduction of requested detection limits far below the levels recommended by the accepted ISO methods. On this context, ISO 17070:2015 was extended in its current version from the determination of pentachlorophenol to tetrachlorophenol, trichlorophenol, dichlorophenol and monochlorophenol isomers. Some brands also included under this technique the ortho phenyl phenol (OPP) analysis, requesting a quantification limit below 1 mg/kg for all analytes. The present paper proposes a new HPLC-DAD-MS direct method for the verification of chlorophenols positive cases, and its extension to leather chemicals analysis, as well as the discrimination among false positive cases and real positive ones. The paper also illustrates case studies reporting differences in the quantification of the said analytes and the chlorophenol scission in different analytical conditions. Take-Away: False positives verification of the presence of chlorophenols. Quicker method respect to the current ISO 17070:2015 standard. Method reliable on Leather chemicls chlorophenos research. Generation of chlorophenols from certain AOX substances.

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