Variations in the sero-prevalence of antibody to brucella infection by cow, farm and area factors were investigated for three contrasting districts in Kenya: Samburu, an arid and pastoral area: Kiambu, a tropical highland area; and Kilifi, a typical tropical coastal area. Cattle were selected by a two-stage cluster sampling procedure and visited once between August 1991 and 1992. Schall's algorithm, a statistical model suitable for multi-level analysis was used. Using this model, older age, free grazing and large herd size (> or = 31) were associated with higher seroprevalence. Also, significant farm-to-farm, area-to-area and district-to-district variations were estimated. The patterns of high risk districts and areas seen were consistent with known animal husbandry and movement risk factors, but the larger than expected farm-to-farm variation within high risk areas and districts could not be explained. Thus, a multi-level method provided additional information beyond conventional analyses of sero-prevalence data.

Background The purpose of this study was to assess the safety and feasibility of performing robot-assisted pediatric surgery using the da Vinci Surgical System in a variety of surgical procedures. Methods A retrospective review of 144 robot-assisted pediatric surgical procedures performed in our institution between June 2004 and December 2007 was done. The procedures included the following: 39 fundoplications; 34 cholecystectomies; 25 gastric bandings; 13 splenectomies; 4 anorectal pull-through operations for imperforate anus; 4 nephrectomies; 4 appendectomies; 4 sympathectomies; 3 choledochal cyst excisions with hepaticojejunostomies; 3 inguinal hernia repairs; two each of the following: liver cyst excision, repair of congenital diaphragmatic hernia, Heller's myotomy, and ovarian cyst excision; and one each of the following: duodeno-duodenostomy, adrenalectomy, and hysterectomy. Results A total of 134 procedures were successfully completed without conversion; 7 additional cases were converted to open surgery, and 3 were converted to laparoscopic surgery. There were no system failures (e.g., setup joint, arm, or camera malfunction; power error; monocular or binocular loss; metal fatigue or break of surgeon's console hand piece; software incompatibility). There was one esophageal perforation and two cases of transient dysphagia following Nissen fundoplication. The mean patient age was 8.9 years, and the mean patient weight was 57 kg. Conclusions Robot-assisted surgery appears to be safe and feasible for a number of pediatric surgical procedures. Further system improvement and randomized studies are required to evaluate the benefits, if any, and the long-term outcomes of robotic surgery.

We consider the probability‐weighted moment and the maximum‐likelihood estimators of two parameters in the log‐logistic distribution. Quantile estimators are obtained using both methods. The distributional properties of these estimators are studied in large samples, via asymptotic theory, and in small and moderate samples, via Monte Carlo simulation. The distribution is shown to be appropriate for a wide variety of meteorological data.

The objective of this study was to analyze the survivorship of dairy cows after displaced abomasum was diagnosed. Survivorship from the calving preceeding diagnosis of displaced abomasum to removal from the herd was investigated for cows that were diagnosed with displaced abomasum compared with herdmates. For cows that were diagnosed with displaced abomasum, factors that affected survivorship from the diagnosis of the disease to removal were investigated. Data from a total of 135 cows that had been diagnosed with displaced abomasum and 373 controls matched by herd and lactation number were available from a database at the University of Guelph. The hazard rate of removal from the herd was estimated using proportional hazard regression adjusted for intraherd correlation. Diagnosis of displaced abomasum significantly increased the hazarad rate of removal from the herd. For cows that were diagnosed with displaced abomasum the hazard rate of removal increased as parity increased. However, the hazard rate decreased with recurrent displaced abomasum and with higher days in milk at diagnosis of the disease. Although the 305-d milk production of cows that were diagnosed with displaced abomasum was lower during the lactation when the disease was diagnosed, 305-d milk production was not associated with removal of cows with that disease from the herd. Milk production during subsequent lactations did not differ between cows that were diagnosed with displaced abomasum and control cows. Low milk production during the subsequent lactations increased the hazard of removal of cows with that disease from the herd.

Recent advances in human genetics have led to a renewed interest in statistical methods for the detection of linkage from family data--for example, between marker loci and disease traits. Statistical analysis of linkage between two loci is carried out almost exclusively by means of the lod (log-odds) score test, equivalent to a likelihood ratio test. The current practice is to declare genetic linkage between loci when the maximum lod score exceeds 3. As will be discussed here, the lod-score approach is not appropriate for the detection of linkage from heterogeneous data, e.g., when families consist of a mixture of linked and unlinked types. Heterogeneity may arise, for example, when rare mutations at different genetic loci are responsible for the same disease trait. As an alternative approach to account for possible heterogeneity in the detection of linkage, we propose the application of large-sample test statistics that are members of Neyman's class of C(alpha), or partial score tests. The convergence of the proposed test statistics to their asymptotic distributions is investigated via Monte Carlo simulation for typical study designs applicable in human genetics.