2,751 research outputs found

    Enumeration of Hypermaps of a Given Genus

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    This paper addresses the enumeration of rooted and unrooted hypermaps of a given genus. For rooted hypermaps the enumeration method consists of considering the more general family of multirooted hypermaps, in which darts other than the root dart are distinguished. We give functional equations for the generating series counting multirooted hypermaps of a given genus by number of darts, vertices, edges, faces and the degrees of the vertices containing the distinguished darts. We solve these equations to get parametric expressions of the generating functions of rooted hypermaps of low genus. We also count unrooted hypermaps of given genus by number of darts, vertices, hyperedges and faces.Comment: 42 page

    DSc - Timothy Rutland Walsh

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    SOUTHERNMOST OCCURRENCE OF THE SUWANNEE COOTER, PSEUDEMYS CONCINNA SUWANNIENSIS (TESTUDINES: EMYDIDAE)

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    The Suwannee Cooter, Pseudemys concinna suwanniensis, the largest member of the speciose turtle family Emydidae, inhabits a small number of rivers that drain into the northeastern Gulf of Mexico along the northwest coast of Florida from just west of Tallahassee to just south of Tampa. The status of this state-protected subspecies in the southernmost of these rivers, the Alafia, is unknown and hence of conservation concern. We provide recent evidence confirming that a reproducing population still exists in this river, and review available specimens and both published and unpublished records documenting the southern limit of distribution. At least within the eastern United States, our observations also extend confirmed knowledge of the geographic occurrence of hatchling turtles overwintering in the nest southward by 285 km

    Extended spectrum ß-lactamase-producing Escherichia coli among backyard poultry farms, farmers, and environments in Thailand

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    Food-producing animals, including poultry, have been considered as potential sources of extended spectrum ß-lactamase (ESBL)-producing Escherichia coli. This study investigates the occurrence and dissemination of ESBL-producing E. coli among backyard poultry farms, farmers, and environments in Northern Thailand. Antimicrobial-resistant phenotypes, resistant determinants, genotypic characterizations, and spread of these isolates were studied. Fecal samples from poultry, farmers, and environments were captured from 27 farms. In total, 587 samples were collected and the overall 27.1% (159/587) of ESBL-producing E. coli isolates were obtained. Among these, ESBL-producing E. coli was isolated from 50% (farmers), 25.9% poultry (24.9% chicken and 36.6% duck) of the fecal samples, and 25.0% of the environmental samples. All isolates demonstrated multidrug resistance, most frequently to ≥ 10 different antimicrobial agents. Molecular analysis of ESBL-encoding genes showed that the predominant gene was blaCTX-M-55 (54.1%), followed by blaCTX-M-14 (28.3%), and blaCTX-M-15 (8.8%). blaCTX-M-27 (3.8%) and blaCTX-M-65 (0.6%) were also detected at low frequencies. Conjugation assays demonstrated that blaCTX-M could be transferred to E. coli J53 with the transfer frequencies ranging from 10−7 to 10−2. Pulsed field gel electrophoresis (PFGE) revealed diverse genotypes, however, identical and closely related PFGE profiles were detected among isolates within and between farms, suggesting the clonal transmission. In addition, our study identified 4 blaCTX-M-27-positive E. coli B2-ST131 isolates. Interestingly, two ST131 isolates, obtained from a farmer and chicken in the same area, showed closely related PFGE profiles. Our results suggest the presence and spread of ESBL-producing E. coli between backyard poultry farms, farmers, and environments in Thailand

    Atrial fibrillation and survival in colorectal cancer

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    BACKGROUND: Survival in colorectal cancer may correlate with the degree of systemic inflammatory response to the tumour. Atrial fibrillation may be regarded as an inflammatory complication. We aimed to determine if atrial fibrillation is a prognostic factor in colorectal cancer. PATIENTS AND METHODS: A prospective colorectal cancer patient database was cross-referenced with the hospital clinical-coding database to identify patients who had underwent colorectal cancer surgery and were in atrial fibrillation pre- or postoperatively. RESULTS: A total of 175 patients underwent surgery for colorectal cancer over a two-year period. Of these, 13 patients had atrial fibrillation pre- or postoperatively. Atrial fibrillation correlated with worse two-year survival (p = 0.04; log-rank test). However, in a Cox regression analysis, atrial fibrillation was not significantly associated with survival. CONCLUSION: The presence or development of atrial fibrillation in patients undergoing surgery for colorectal cancer is associated with worse overall survival, however it was not found to be an independent factor in multivariate analysis

    A one-health approach to antimicrobial resistance

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    Widespread use of antibiotics in animals either as growth promoters or for metaphylaxis may drive the spread of clinically relevant drug resistance genes and pathogens. New work uncovers drug resistance gene patterns from livestock across European farms and finds a correlation with agricultural antibiotic use

    Anthropological and socioeconomic factors contributing to global antimicrobial resistance: a univariate and multivariable analysis

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    Background Understanding of the factors driving global antimicrobial resistance is limited. We analysed antimicrobial resistance and antibiotic consumption worldwide versus many potential contributing factors. Methods Using three sources of data (ResistanceMap, the WHO 2014 report on antimicrobial resistance, and contemporary publications), we created two global indices of antimicrobial resistance for 103 countries using data from 2008 to 2014: Escherichia coli resistance—the global average prevalence of E coli bacteria that were resistant to third-generation cephalosporins and fluoroquinolones, and aggregate resistance—the combined average prevalence of E coli and Klebsiella spp resistant to third-generation cephalosporins, fluoroquinolones, and carbapenems, and meticillin-resistant Staphylococcus aureus. Antibiotic consumption data were obtained from the IQVIA MIDAS database. The World Bank DataBank was used to obtain data for governance, education, gross domestic product (GDP) per capita, health-care spending, and community infrastructure (eg, sanitation). A corruption index was derived using data from Transparency International. We examined associations between antimicrobial resistance and potential contributing factors using simple correlation for a univariate analysis and a logistic regression model for a multivariable analysis. Findings In the univariate analysis, GDP per capita, education, infrastructure, public health-care spending, and antibiotic consumption were all inversely correlated with the two antimicrobial resistance indices, whereas higher temperatures, poorer governance, and the ratio of private to public health expenditure were positively correlated. In the multivariable regression analysis (confined to the 73 countries for which antibiotic consumption data were available) considering the effect of changes in indices on E coli resistance (R2 0·54) and aggregate resistance (R2 0·75), better infrastructure (p=0·014 and p=0·0052) and better governance (p=0·025 and p<0·0001) were associated with lower antimicrobial resistance indices. Antibiotic consumption was not significantly associated with either antimicrobial resistance index in the multivariable analysis (p=0·64 and p=0·070). Interpretation Reduction of antibiotic consumption will not be sufficient to control antimicrobial resistance because contagion—the spread of resistant strains and resistance genes—seems to be the dominant contributing factor. Improving sanitation, increasing access to clean water, and ensuring good governance, as well as increasing public health-care expenditure and better regulating the private health sector are all necessary to reduce global antimicrobial resistance
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