Browsing by Subject "Risk factors"

Now showing 1 - 10 of 10
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    Alcohol Abuse: Will it hurt your heart?
    (2012-07-26) Ewart, David
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    Cow mortality in Midwest dairy herds
    (2013-03) Shahid, Muhammad Qamer
    On-farm dairy cow mortality is becoming a significant issue in the US dairy industry. A rise in on-farm mortality among cows indicates compromised cow welfare and also causes economic losses, including value of animal, its replacement cost, the loss of milk production and the extra labor used for its carcass disposal. Recently published studied showed increasing trends in dairy cow mortality in the US and in other countries. Mortality is the primary reason of cows leaving the herd. Various herd and cow level factors have been associated to the rise in mortality over the last couple of decades. The aim of the current study was to describe the mortality patterns among cows in Midwest dairy herds and to identify the cow and herd level risk factors for on farm mortality. Approximately 5.9 million lactation records for cows from 10 Midwest states that calved between January 2006 and December 2010 were analyzed. Herd level mortality rate increased over time, and was higher in larger herds, herds with lower milk yield, and herds with less annual culling. Cow level mortality rate was higher in early lactation, in older cows, in winter and summer. Also, mortality was the main reason of cows leaving the herds in our study. The survival analysis indicated that the hazards of mortality were higher in cows with higher fat to protein ratio, higher fat%, lower milk protein %, higher 1st test day somatic cell score, higher milk urea nitrogen, cows with male calves, cows carrying multiple calves, and increased calving difficulty score. Cow mortality was higher in herds with increased percentage of still births, herds with higher somatic cell score and increased herd calving interval, and larger herds. Cows with higher 1st test day milk yield and in herds with higher milk yield had lower mortality hazards. The results of current study indicate that first test day records especially those indicative of negative energy balance in cows could be helpful to identify animals at high risk of mortality. It was also noted that higher milk yield did not seem to have harmful effects on mortality. In addition, the association between herd level factors and mortality indicated that management quality could be an important factor in lowering on-farm mortality thereby improving cow welfare.
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    Cultural Perspectives on Pathways from Child Maltreatment to Delinquency: A Cross-cultural Mixed Methods Inquiry in the U.S. and South Korea
    (2019-05) Cho, Minhae
    This study explores cultural perspectives on pathways from child maltreatment to delinquency in the U.S. and South Korea (hereafter Korea). The involvement of maltreated youth in delinquency is a persistent global concern. Involvement in the juvenile justice system compounds risks to children already vulnerable due to maltreatment and involvement in the child welfare system (Chapin & Griffin, 2005; Morris & Freundlich, 2004). What constitutes child maltreatment (Kobin, 2002; Wells & Johnson, 2016) and delinquency (Bartollas & Schmalleger, 2014) varies cross-culturally. These various definitions may affect the pathways from child maltreatment to delinquency. Cross-cultural comparative research on crossover youth is particularly important for the design and implementation of culturally sensitive policies and practices that prevent the involvement of maltreated children with diverse cultural backgrounds in the juvenile justice system. Guided by “universalism without uniformity (Shweder & Sullivan, 1993, p. 514)” from developmental cultural psychology, this study employed a cross-cultural, mixed methods study design (Haight & Bidwell, 2016) to examine cultural variations in understanding risks for involvement in delinquency of maltreated children in the U.S. and South Korea. Using an explanatory sequential mixed methods design, the initial quantitative analyses on risk factors for delinquency in both countries were followed by qualitative inquiries for the purpose of triangulation, contextualization, elaboration, and complementarity. In the quantitative component of this study, a prospective, longitudinal cohort study design was used to examine risk factors for delinquency in the U.S. and Korea, respectively. The U.S. quantitative study investigated delinquency rates over a 6-year period and factors associated with the risk of early onset of delinquency for maltreated youth beginning in 3rd grade in academic year 2008-2009. Utilizing an integrated data set from state departments of Education and Human Services, and Judicial Branch, this study tracked the administrative records of 5,200 maltreated children for their first-time delinquency. Approximately 7% of maltreated youth (n = 332) were adjudicated as delinquent over a 6-year period from 3rd to 8th grade. The results of the Cox proportional hazard model indicated significant risk factors for early onset of delinquency in maltreated children: being male, belonging to particular racial minority groups (Black, Native Indian, and Hispanic youth), receiving a diagnosis of emotional/behavioral disabilities, receiving an out-of-school suspension, and experiencing more than three previous maltreatment incidents. The Korean quantitative study investigated the rates of delinquency, the impact of maltreatment on delinquency, and other risk factors for delinquency among South Korean youth. Using Korean Children and Youth Panel Survey data, this quantitative study followed two cohorts of middle (n=2,275) and high (n=2,272) school Korean youth until their first-time self-reported delinquency over a 4-year period from 6th to 9th grade for the middle school cohort and from 9th to 12th grade for the high school cohort. To create complete and balanced data, ten imputation data sets were generated, and the results present the pooled estimates of these data sets. Approximately 19% of middle and 11% of high school youth engaged in delinquency over the 4-year period. Maltreatment was associated with delinquency only for high school youth. The results of the discrete-time hazard model indicated that in both cohorts, males and youth with high levels of aggression were more likely to engage in delinquency. Consistent with the existing research in Western countries, the Korean quantitative study found additional risk factors including high levels of depression, negative attitudes toward school rules, father’s education less than high school, and low levels of self-control. This study also found some risk factors that require understanding of the sociocultural context in Korea including mother’s education more than high school and higher family income. The subsequent qualitative component of this mixed methods study examined cultural perspectives on the risk factors identified in the first two quantitative studies through the interpretations of U.S. and South Korean professionals. Cross-cultural analysis was conducted on data from the in-depth, semi-structured individual interviews with 21 U.S. and 20 Korean professionals serving various roles in the child welfare and juvenile justice systems, including child protection workers, probation officers, attorneys, and judges. The professionals described common and culturally unique risk factors for delinquency in maltreated children. The common risk factors discussed by the U.S. and Korean professionals included: (1) psychosocial vulnerabilities of individual youth; (2) difficulties in parent-child relationships; and (3) challenges to systems’ interventions. Yet their interpretations were culturally nuanced, reflecting differences in the social, cultural, and practice contexts between the two countries: (1) external attribution (U.S.) or internal attribution (Korea) to youth’s psychosocial vulnerabilities; (2) parent history of their own trauma (U.S.) and a lack of parental responsibility (Korea) as as underlying difficulties in the parent-child relationships; and (3) a lack of cross-systems collaboration (U.S.) and a lack of accountability among child-serving systems (Korea) as challenges to systems’ interventions. Professionals’ discussions also revealed culturally unique risk factors in each country: racism (U.S.) and social justification for physical punishment (Korea). As the first cross-cultural, mixed methods study, findings of the current study can contribute to the conceptual understanding of the pathways from maltreatment to delinquency in various cultural contexts. The findings of the current study also can contribute to a broader knowledge base for the training of professionals pertaining to maltreated children at risk for delinquency involved in multiple child serving systems. Furthermore, study findings can facilitate new perspectives among professionals by illuminating their own taken-for-granted assumptions and socialization practices in addressing risks for delinquency in maltreated children. Therefore, findings of this study can promote different ways of thinking to strengthen existing practices and policies as well as to develop culturally tailored interventions that prevent maltreated ethnic minorities from engaging in delinquency.
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    An epidemiological approach to emergency vehicle advanced warning system development: a two-phase study
    (2013-12) Drucker, Christopher Jose
    Motor vehicle crashes involving emergency vehicle (EV; police, fire trucks, ambulances, etc.) and non-EV drivers have been a known problem that contributes to fatal and nonfatal injuries; however, characteristics associated with non-EV drivers, involved in these crashes, have not been examined adequately. This two-phase study involved: Phase 1) data analysis, using The National Highway Traffic Safety Administration's Fatality Analysis Reporting System and the National Automotive Sampling System General Estimates System to identify driver, roadway, environmental, and crash factors, and consequences for non-EV drivers involved in fatal and nonfatal crashes with in-use and in-transport EVs; and Phase 2) design and analysis of the impact of two in-vehicle driver support systems that alert non-EV drivers to approaching EVs in a simulated urban environment, based on driving performance and usability measures under distracting and non-distracting conditions. Phase 1 analysis identified potential factors associated with non-EV drivers by utilizing epidemiological methodologies and multivariate logistic regression modeling. Non-EV drivers were more often involved in nonfatal crashes with EVs when driving: distracted (vs. not distracted; OR = 1.9); with vision obstructed by external objects (vs. no obstruction; OR = 36.4 for obstruction due to buildings); at intersections of four-points or more (vs. no intersection; OR = 2.1); at night (vs. midday; OR = 2.8); and in opposite directions (vs. same directions; OR = 4.8) of the EVs. Fatal crashes were associated with driving on urban roads (vs. rural; OR = 2.2); straight through intersections (vs. same direction; OR = 3.4) of four-points or more (vs. no intersection; OR = 4.9); and at night (vs. midday; OR = 1.6) although these types of crashes were less likely to occur on dark roads (vs. daylight; OR = 0.6). Consequences included increased risk for non-EV drivers to be fatally wounded (vs. no injury; OR = 2.1) among crashes involving at least one fatality. Phase 2 consisted of eighty-five participants completing a driving simulator trial-based experiment in which they encountered EVs crossing four-way intersections. Overall, the analysis indicated improved responses and roadway safety among participants presented with the driver support systems compared to participants presented with no driver support system. Most notably, participants were at decreased risk of collisions with EVs when given a driver support system (vs. no driver support system; OR = 0.3). The presence of the driver support systems did not increase in-vehicle distractions or perceived mental workload of the driving tasks. In addition, drivers indicated a moderate level of trust and reported the systems to be somewhat useful and satisfying.The findings of this two-phase study suggest drivers have difficulties in visually detecting EVs in different environments and that the use of technology may be beneficial as an intervention to mitigate roadway crashes between non-EV and EV drivers. Future research should continue to examine these interactions to identify methods to improve roadway safety.
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    Epidemiological Evaluation Of Uroliths In Selected Animals
    (2017-01) NWAOKORIE, EUGENE
    ABSTRACT This dissertation examined the predominant minerals, as well as the risk and protective factors for urolith formation in ferrets, goats, sheep and horses. Sterile struvite was the predominant mineral in uroliths in ferrets. The mean age of ferrets with struvite uroliths was 3.6 ± 2.8 years and range (0.2 to 9.8 years). Cystine comprised 70 of the 435 (16%) uroliths retrieved from ferrets. The mean age of ferrets with cystine uroliths was 4.1 ± 1.5 years and range (0.5 to 9 years). This was surprising, as one might expect an earlier onset of clinical manifestations of a probable genetic disorder, with the life span of ferrets being reported to be between 5 and 11 years. Cystine uroliths are not rare at all in ferrets as was originally thought. Genetic factors associated with cystine urolithiasis have not yet been reported in ferrets, but a familial pattern of inheritance determined to be a major underlying factor in cystine urolithiasis in dogs and humans suggests that this may be a factor in ferrets and that the parent stock of ferrets in the present study may have been inbred. The mean age of goats with CaCO3 urolith was 3.8 ± 1.8 years and range (0.3 to 14 years). Males are at increased odds for CaCO3 urolith than females. Goats of African descent had a higher risk of developing calcium carbonate uroliths than did goats of non-African descent. The mean age of goats with silica uroliths was 3.1 ± 1.2 years and range (0.2 to 10 years). The bulk of goats with silica were fed grass/pasture (22%). Silica urolith submissions retrieved from goats and submitted to the MUC decreased from 20% between1984 and1998 to 11% between1999 and 2012. More than 57% percent of goats with struvite uroliths were < 1 year of age. Calcium carbonate uroliths rose significantly in North America but not in Europe and Asia from 40% in 1984 to 1998 to 45% in 1999 to 2012. Struvite and magnesium calcium phosphate apatite uroliths decreased significantly in North American continent respectively from 8% and 9% in 1984 to 1998 to 3% and 4% respectively in 1999 to 2012. The mean age of sheep with CaCO3 urolith was 3.4 ± 1.4 years and range (0.8 to 11 years). Calcium carbonate uroliths were common in Dorset, Suffolk and mixed breeds of sheep. These 3 breeds comprised 15 of 29 (52%) of case sheep with calcium carbonate uroliths with data available. The mean age of sheep with magnesium calcium phosphate carbonate (MCPC) uroliths was 1.6 ± 1.2 years and range (0.2 to 9 years). Rambouilette, Suffolk and Hamshire sheep breeds were at high frequency for magnesium calcium phosphate carbonate urolith formation. These 3 breeds comprised 23 of 31 (74%) of case sheep with MCPC uroliths with data available. Magnesium calcium phosphate carbonate uroliths were commonly retrieved from sheep < 1year of age and comprised 23 of 38 (60.5%) of sheep with this condition with age reported. MCPC is more common in male and sexually intact sheep. The mean age of horse with CaCO3 urolith during the study was 13 ± 1.8 years and range (0.3 to 36 years). Quarter and Thorough bred horses comprised 151 of 292 (52%) of all horses with CaCO3 urolith. Horses between the ages of 6 and 17 years old comprised 197 of 323 (61%) horse cases with ages reported. Male horses had higher frequency for CaCO3 uroliths compared to females. Neutered horses had higher frequency for CaCO3 uroliths than sexually intact. Calcium carbonate uroliths in horses were more likely to be retrieved from the lower portions of the urinary tract (85%) of case horses than from the upper portions of the urinary tract (14%). Three (1%) were retrieved from both upper and lower tracts. A typical horse with CaCO3 urolith is a neutered male between the ages of 6 and 17 years old. Seventy-six of 80 (95%) CaCO3 uroliths were retrieved from horses between 1981 and 1997 and submitted to the MUC, while between 1998 and 2014 the amount retrieved from case horses were 227 of 278 (97%) CaCO3 and submitted to the same laboratory. This study identified risk factors associated with urolithiasis in ferrets, goats, sheep and horses; however, these associations do not allow conclusions regarding cause-and-effect relationships. Evaluation of risk and protective factors through epidemiological studies may be useful in the development of recommendations for the prevention and control of urolith formation in these selected animals.
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    Epidemiology of influenza A viruses of swine: surveilance, airborne detection and dissemination
    (2012-08) Corzo, Cesar Agustin
    Chapter 2: Swine Influenza Active Surveillance in the United States Influenza A virus (IAV) in swine continues to be an important swine respiratory agent along with being a source of concern to public health authorities. While veterinary diagnostic laboratories are a valuable source of information with regards to the identification and genetic characterization of newly emerged virus through passive surveillance, there is still a need for additional surveillance programs that can aid in detecting new viruses in a timely manner. An active surveillance program was performed in 32 pig farms throughout the Midwestern United States between June 2009 and December 2011. Thirty nasal swabs were collected from growing pigs on a monthly basis and tested for IAV by RRT-PCR. During sample collection, data on sample collection date, pig age, pig group respiratory signs, clinical status and vaccination history were recorded. A total of 16,170 nasal swabs from 540 groups of growing pigs were collected from which 746 (4.6 %) nasal swabs and 117 (21.7 %) groups tested positive for IAV, respectively. Throughout the study, IAV was consistently detected in at least one farm except in two months. From the positive groups of pigs, H1N1, H1N2, H3N2, 2009 pandemic H1N1were detected in 18%, 16%, 7.6% and 14.5% of the groups, respectively. In seven groups, H1N2 or H3N2 reassortants containing genes from 2009 pandemic H1N1 were found. There were eight groups in which an H1N2 and the 2009 pandemic H1N1 were identified simultaneously. Groups of pigs were more likely to test positive for IAV during the spring and summer seasons compared to the fall. Age and group respiratory clinical signs were not predictors of group IAV status. This active IAV surveillance program provided quality data and increased the understanding of the current situation of circulating viruses in the U.S. pig population. Further studies in swine should be conducted to increase our knowledge regarding the characteristics of IAV. Chapter 3: Swine influenza virus risk factors in growing pigs Influenza A virus (IAV) is an important cause of respiratory disease in swine. Understanding the epidemiology of the disease is in its early stages and is needed to develop effective control and prevention strategies. A study was conducted to assess the relationship between the presence of IAV in growing pig farms and farm level risk factors. Twenty-six pig farms participated in the study from which 30 nasal swabs from growing pigs were collected on a monthly basis for 12 or 24 consecutive months between 2009 and 2011. Nasal swabs were tested for IAV by RRT-PCR. Weather stations were located at every participating farm for monitoring temperature, relative humidity, light intensity, wind speed and wind gusts. Farm level data was obtained through a questionnaire to assess the relationship between the presence of IAV and farm level characteristics. At the individual level, 4.6% of the nasal swabs from growing pigs tested positive for IAV. Of the monthly groups of pigs from which nasal swabs were collected, 20.8% had at least one positive nasal swab. Positive nasal swabs originated from 23 of the 26 participating farms. Farm type, pig flow and gilt source were associated with the presence of IAV. Environmental temperature and wind speed were associated with the presence of IAV. Overall, this study provides insights into the ecology of IAV which can aid in the development of control and prevention strategies. Chapter 4: Prevalence and risk factors for H1N1 and H3N2 influenza A virus infections in Minnesota turkey premisesInfluenza virus infections can cause respiratory and systemic disease of variable severity and also result in economic losses for the turkey industry. Several subtypes of influenza can infect turkeys causing diverse clinical signs. Influenza subtypes of swine origin have been diagnosed in turkey premises. However, it is not known how common these infections are nor the likely routes of transmission. We conducted a cross-sectional study to estimate the seroprevalence of influenza viruses in turkeys and examine factors associated with infection on Minnesota turkey premises. Results for influenza diagnostic tests and turkey and pig premises location data were obtained from the Minnesota Poultry Testing Laboratory (MPTL) and the Minnesota Board of Animal Health (MBAH) respectively from January 2007 to September 2008. Diagnostic data from 356 premises were obtained, of which 17 premises tested positive for antibodies to influenza A virus by agar gel immunodiffusion (AGID) assay and were confirmed as either H1N1 or H3N2 influenza viruses by hemagglutination and neuraminidase inhibition assays. Influenza infection status was associated with proximity to pig premises and flock size. The latter had a sparing effect on influenza status. This study suggests that H1N1 and H3N2 influenza virus infections of turkey premises in Minnesota are an uncommon event. The route of influenza virus transmission could not be determined, however, the findings suggest that airborne transmission should be considered in future studies. Chapter 5: Characterization of the temporal dynamics of airborne influenza A virus detection in acutely infected pigs Influenza A viruses infect many species including avians, mammals and humans. Aerosol transmission is one route that enables the virus to infect populations. This study explored the relationship between number of infected pigs and the probability of detecting influenza virus RNA in bioaerosols through the course of an acute infection. Bioaerosols were collected using a cyclonic collector in two groups of seven week-old pigs that were experimentally infected upon exposure with a contact infected pig (seeder pig). After contact exposure, individual pig nasal swab samples were collected daily and air samples were collected three times per day for eight days. All samples were tested for influenza by RRT-PCR targeting the influenza virus matrix gene. All pigs' nasal swabs became influenza virus RRT-PCR positive upon exposure to the infected seeder pig. Airborne influenza was detected in 58% (25/43) of the air samples collected. Temporal dynamics of influenza virus detection in air samples were in close agreement with the nasal shedding pattern in the infected pigs. First detection of positive bioaerosols occurred 2 days post contact (DPC). Positive bioaerosols were consistently detected between 3 and 6 DPC, a time when most pigs were also shedding virus in nasal secretions. Overall, the odds of detecting a positive air sample increased 2.2 times with every additional nasal swab positive pig in the group. In summary, there was a strong relationship between the number of pigs shedding influenza virus in nasal secretions and the detection of bioaerosols during the course of an acute infection in non-immune population. Chapter 6: Detection of airborne influenza A virus in experimentally infected pigs with maternally derived antibodies.This study assessed whether recently weaned piglets with maternally derived antibodies were able to generate infectious influenza aerosols. Three groups of piglets were assembled based on the vaccination status of the dam. Sows were either non vaccinated (CTRL) or vaccinated with the same (VAC-HOM) strain or a different (VAC-HET) strain than the one used for challenge. Piglets acquired the maternally derived antibodies by directly suckling colostrum from their respective dams. At weaning, pigs were challenged with influenza virus by direct contact with an infected pig (seeder pig) and clinical signs were evaluated. Air samples, collected using a liquid cyclonic air collector, and individual nasal swabs were collected daily for 10 days from each group and tested by matrix real-time reverse transcriptase polymerase chain reaction (RRT-PCR) assay. Virus isolation and titration were attempted for air samples on Madin-Darby canine kidney (MDCK) cells. All individual pigs from both VAC-HET and CTRL groups tested positive during the study but only one pig in the VAC-HOM group was positive by nasal swab RRT-PCR. Influenza virus could not be detected or isolated from air samples from the VAC-HOM group. Influenza A virus was isolated from 3.2% and 6.4% air samples from both the VAC-HET and CTRL groups, respectively. Positive RRT-PCR air samples were only detected in VAC-HET and CTRL groups on day 7 post-exposure. Overall, this study provides evidence that recently weaned pigs with maternally derived immunity without obvious clinical signs of influenza infection can generate influenza infectious aerosols which is relevant to the transmission and the ecology of influenza virus in pigs. Chapter 7: Detection of airborne swine influenza A virus in air samples collected inside, outside and downwind from swine barns Airborne transmission of influenza A virus (IAV) in swine is speculated to be an important route of virus dissemination, but data are scarce. This study attempted to detect airborne IAV by virus isolation and RRT-PCR in air samples under field conditions. This was accomplished by collecting air samples from four acutely infected pig farms and locating air samplers inside the barns, at the external exhaust fans and downwind from the farms and at distances up to 2.1 km. Weather data was also collected to explore the relationship between detection of IAV and temperature, relative humidity and sunlight intensity. IAV was detected in air samples collected in all the farms included in the study. On average, 96% and 85% of the air samples collected inside and at the exhaust fans from positive farms tested positive through RRT-PCR, respectively. Isolation of IAV was possible from air samples collected inside the barn at two of the farms and in one farm from the exhausted air. Influenza virus RNA was detected in air samples collected between 1.5 and 2.1 Km away from the farms. The odds of detecting IAV decreased with distance from the farm and greater levels of sunlight intensity. The results from this study prove evidence of the risk of aerosol transmission in pigs under field conditions and perhaps to other species as well.
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    Family violence exposure and Associated risk factors to child PTSD in a Mexican sample
    (2012-11) Erolin, Kara Sukja
    This dissertation study examines the interactional effects of trauma exposure on parent-child relationships with 87 mother-child dyads from a child maltreatment population in Monterrey, Mexico. The relational impact of trauma on youth is salient given the important role that the parent/caregiver plays in a child's life. Data from four standardized instruments of a larger study piloting an innovative multi-method assessment protocol was examined to gain a cultural and contextual understanding of trauma and family violence exposure and associated risk factors of child PTSD in this sample. Findings indicated high levels of exposure to any potentially traumatic stressor in children and mothers, particularly violence in the home and community. Socioeconomic and sociocultural cultural factors such as poverty, traditional gender role socialization, and excessive community violence were associated with greater PTSD symptomatology in children and mothers in this sample. Results from this study support the need for more family-based research to explore intra- and extrafamilial influences on parent-child relationship and the impact of larger cultural and community factors on the development of PTSD. Implications for families, practitioners, researchers, social institutions within the community and government, and the larger global community are discussed.
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    Risk factors associated with implant failure
    (2013-04) Schmalz, Emily Marie
    Objective and Background: Implants have become a predictable treatment for the replacement of missing teeth. However, they are not without problems. It is important to understand the relationship between implant failure and patient- and implant-level factors. Therefore, the purpose of this retrospective chart review was to explore patient- and implant-level factors associated with implant failure, defined here as the loss, removal, or scheduled removal of the implant. Methods: Data were abstracted from charts of patients at the University of Minnesota School of Dentistry. Patient-level variables included current smoking status, gender, age, self-reported diabetes, and history of bisphosphonate use. Implant-level variables included implant brand, location, whether sinus or bone augmentation was done, immediate or delayed implant placement and restoration type. Data were entered into a custom, web-based data file. Implant failure was defined as the loss or planned removal of the fixture. Descriptive statistics were computed for patient- and implant-level variables. Hazard ratios (HR) and p-values were calculated using Cox proportional hazards regression. The relationship between the variables and implant failures were explored in both univariable and multivariable analyses. We analyzed data for all implants and separately for implants placed in the posterior maxilla. Results: Smoking was the only patient-level variable associated with implant failure in the univariable analyses (P=0.0109, HR=2.13). Sinus grafting material significantly affected implant failure in both univariable and multivariable analyses (P=<0.0001). Implant-level variables such as length, jaw region, alveolar ridge grafting, and sinus grafting both prior to and at the time of implant placement were not significantly associated with failures (P=>0.05) in the univariable analysis. In the multivariable analysis, overdentures had a failure rate 2.95 times greater than single crowns. In addition, sinus grafting material (P=<0.0001) and bone grafting material (P=0.006) were also significant in the multivariable analysis for all sites. When limiting the multivariable analysis to posterior maxillary sites only bone grafting material was no longer significant, while both restoration type and sinus grafting material remained statistically significant. Interestingly, timing of ridge augmentation, either prior to or at the time of implant placement did not affect implant failure (HR=0.97). Conclusions: Overall, implants are a predictable treatment option. Smoking negatively affects implant success. Implants supporting overdentures have higher failure rates when compared to those supporting single or multiple fixed restorations and fixed-detachable appliances. Self-reported diabetes, use of bisphosphonates and timing of ridge augmentation were not associated with implant failure.
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    Understanding animal movements to inform bovine tuberculosis surveillance: a framework for a targeted approach
    (2013-08) do Rosario Ribeiro Lima, Joao Paulo
    Bovine tuberculosis (bTB) is a zoonotic disease that affects domestic and wildlife species. In recent years in the US, a novel scenario for bTB has arisen, characterized by sporadic outbreaks in cattle populations across the country and by spillover of the infection to wildlife. The cattle production system in the US continues to change, with the number of cattle farms declining but the number of cattle per farm increasing. Furthermore, cattle are moved long distances for trade and production purposes. Also the drought has encouraged a large number of cattle to move from severely affected southern states to northern states, such as Minnesota with available feed and water resources. This reality poses a threat to the biosecurity of the Minnesota cattle population and agricultural industry, due to the risk of introduction of bTB from which the state is now free. The objective of the studies presented here was to develop a new framework for bTB surveillance based on risk profiling of herds and regions. The fundamental concept from which the current work originates is that infectious disease transmission is not a random process but is modulated by risk factors that enhance its occurrence. The primarily concern in disease-free areas such as the state of Minnesota should be the identification of those key players, in this case farms and/or regions, that are at higher risk of disease introduction, and secondly to identify those farms and/or regions that would cause greater impact in the cattle population and wildlife populations if infected. The ultimate goal is to develop a targeted approach to bTB surveillance in order to increase system accuracy and cost-effectiveness which, although effective in the past, has failed recently to prevent continuing outbreaks in US cattle and wildlife populations. The combination of the studies presented in this doctoral dissertation provides a systems approach to bTB surveillance, especially at the wildlife and cattle interface. It develops a framework for a targeted surveillance system by developing approaches to identify at risk cattle premises and regions where disease is both more likely to be introduced and spread.
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    Violence against educators.
    (2011-09) Wei, Chia
    Introduction Physical and non-physical violence are recognized as a major public health issue in the work environment and one commonly ignored population that may experience work-related violence is teachers/educators. However, to date, there has been no apparent investigation to examine the relations between various exposures of interest and rates of violence, based on hours worked by educators. The objective of the current study was to identify the potential risks for both physical assault (PA) and nonphysical violence (NPV) against licensed Minnesota educators, based on hours exposed. Methods The target study population was licensed kindergarten through grade 12 educators in Minnesota, who were identified in the Minnesota Department of Education database as of 2003. A random sample of 26,000 educators was selected from this database to determine eligibility; 6,469 eligible participants were included in the study. Data were collected between April 27, 2005 and March 31, 2006, using specially designed mailed questionnaires. PA and NPV event data were collected from respondents for a 12-month time period prior to their respective survey completion dates. Injury rates per 100,000 working hours were calculated, using generalized linear models with Poisson distribution for both PA and NPV events among educators. Multivariate analyses utilized calculated rate ratios to determine the strength of the association between exposures of interest and injury outcomes (PA and NPV); selection of confounders for multiple regression with Poisson distribution was based on Directed Acyclic Graphs, following the methods described by Greenland and colleagues. Results Among all eligible respondents, the majority was female (77%). The total NPV rates were higher than the total PA rates (26.37 and 5.31, respectively). For the four subcategories of NPV, the total rates were: threat (34.82); sexual harassment (7.58); verbal abuse (55.48); and bullying (19.62). Multivariate analyses for respective PA and NPV models revealed increased rate ratios for: educators who were not married (1.28, 1.20) versus married; worked in public alternative (1.73, 1.93), compared to public schools; those who worked in special education (4.39, 1.45) and in multiple activities (4.01, 1.41), compared with standard classroom teaching; and worked with class sizes less than ten (2.71, 1.43), compared to ten to < 25 students. Decreased risks for respective PA and NPV models were identified for: males (0.73, 0.85), compared with females; those who worked as educators for 20-29 (0.66, 0.66), and >30 (0.55, 0.60) years, compared to less than ten years; and worked in their current school for more than 20 (0.39, 0.80) versus less than five years. Conclusions Results from this study provided information about factors associated with increased and decreased risks for violence against educators, based on hours exposed. This information provides a basis for further investigation and consideration of possible intervention strategies to reduce violence in the school environment.