Browsing by Subject "human"
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Item A quantitative man-machine model for cyber security efficiency analysis(Texas A&M University, 2007-04-25) Jung, Sung-OhThe analysis of security defense processes is of utmost importance in the management of various cyber-security attacks, which are increasing in scope and rapidity. Organizations need to optimize their resources based on a sound understanding of the level of their security defense processes' efficiency and the impact of their investment. Modeling and characterization of the dynamics of cyber security management are essential to risk prediction, damage assessment, and resource allocations. This dissertation addresses the interactions between human factors and information systems. On the basis of the spiral life cycle model of software development processes, we develop a realistic, holistic security attack-defense model - Man-Machine Model (M3), which combines human factors and information systems' (i.e., machine) states under an integrated analytical framework. M3 incorporates man and machine components. The man component is comprised of several variables such as Skill & Knowledge (SKKN) and Teamwork Quality (TWQ). The machine component is composed of variables such as traffic volume and the amount of downtime. M3 enables the analysis of intrusion detection and incident response process efficiency, i.e., security defense team performance. With data analysis, we formulate and test four major research hypotheses based on the data collected during security experiments. Through hypothesis testing, we evaluate regression models to estimate the security defense team performance (i.e. efficiency) at different levels of human intelligence (e.g., skill and knowledge) and teamwork (e.g., teamwork quality). We assess the fitness and significance of the regression models, and verify their assumptions. Based on these results, organizations can hire those who have an appropriate level of skill and knowledge when it concerns investments to increase the level of skill and knowledge of security personnel. They also can attempt to increase the level of skill and knowledge of security personnel.Item The relationship between the level of antibiotic use and resistance among enteric bacteria in a multi-site integrated human and swine population(2009-05-15) Christian, Kristi LynnThe objective of this longitudinal study was to study the relationship between changes in prevalence of resistant enteric bacteria associated with mean monthly doses (MMD) of various antibiotics used in each of two host species. From January 2004 ? January 2007, monthly composite swine fecal samples and human wastewater samples representing various production and occupational cohorts, respectively, were collected from 19 geographically unique locations in east- and south-central Texas. Bacterial isolates cultivated on CHROMagar-E.coliTM and DifcoTM mEnterococcus (ME) were tested for susceptibility to multiple antibiotics by microbroth dilution using the SensititreTM system. The relationship between the prevalence of resistant bacteria, sampling period, and antibiotic use within each host species was assessed in a generalized linear model adjusted for the dependence of responses within location using a binomial distribution and logit link function in STATA? ver. 9.2. For the swine E. coli isolates, the relationship between tetracycline resistance and level of chlortetracycline (CTC) use in swine illustrated a dose-response relationship, with odds ratios (OR) of 1.20 and 1.81 (P < 0.05) for second- and third-level categories of MMD relative to baseline (zero-use) respectively. When considered by swine production groups, intake boar isolates had an elevated relative odds of resistance to tetracycline (OR = 1.51, P < 0.05), and the nursery units had an elevated odds (OR = 2.61, P < 0.05) of exhibiting resistance to ceftiofur, relative to pigs housed in the farrowing barns. Regarding swine Enterococci isolates, those swine from locations that utilized tylosin had an elevated OR of 3.54 (P < 0.05) of exhibiting resistance to tylosin, relative to those locations that used no tylosin. At this juncture, an apparent occupational risk of harboring tetracycline-resistant E. coli, and the apparent sparing effect (Enterococcus spp.) associated with exposure to swine production, remain unexplained. This study demonstrated that the prevalences of tetracycline- and tylosin-resistant enteric bacteria swine were dependent on CTC and tylosin use in feed, respectively. Swine production group-effects on the prevalence of tetracycline, ceftiofur, and erythromycin resistance were also important. This study provides a better understanding of the relationships between antibiotic prescribing practices at the ecologic level and the relative odds of carriage of resistant bacteria within two host species in a vertically integrated agri-food system.