Genetic diversity and ecological success of Staphylococcus aureus strains colonizing humans

The genetic determinants and phenotypic traits which make a Staphylococcus aureus strain a successful colonizer are largely unknown. The genetic diversity and population structure of 133 S. aureus isolates from healthy, generally risk-free adult carriers were investigated using four different typing methods: multilocus sequence typing (MLST), amplified fragment length polymorphism analysis (AFLP), double-locus sequence typing (DLST), and spa typing were compared. Carriage isolates displayed great genetic diversity which could only be revealed fully by DLST. Results of AFLP and MLST were highly concordant in the delineation of genotypic clusters of closely related isolates, roughly equivalent to clonal complexes. spa typing and DLST provided considerably less phylogenetic information. The resolution of spa typing was similar to that of AFLP and inferior to that of DLST. AFLP proved to be the most universal method, combining a phylogeny-building capacity similar to that of MLST with a much higher resolution. However, it had a lower reproducibility than sequencing-based MLST, DLST, and spa typing. We found two cases of methicillin-resistant S. aureus colonization, both of which were most likely associated with employment at a health service. Of 21 genotypic clusters detected, 2 were most prevalent: cluster 45 and cluster 30 each colonized 24% of the carrier population. The number of bacteria found in nasal samples varied significantly among the clusters, but the most prevalent clusters were not particularly numerous in the nasal samples. We did not find much evidence that genotypic clusters were associated with different carrier characteristics, such as age, sex, medical conditions, or antibiotic use. This may provide empirical support for the idea that genetic clusters in bacteria are maintained in the absence of adaptation to different niches. Alternatively, carrier characteristics other than those evaluated here or factors other than human hosts may exert selective pressure maintaining genotypic clusters.

Executive compensation and the performance of the firm

A sample of large industrial corporations is examined to determine whether there is a relationship between the levels of compensation received by the senior executives of those firms and the firms' economic performances. We find consistent evidence of such a relationship, with differences across firms in the total compensation of their three highest-paid officers being positively related to differences in both the common stock returns and operating profitability of the firms. The implication is that compensation packages are designed to reduce agency costs.

Strategies to the success of Online Course Development

Introduction Online courses provide flexible access to education from a distance. However, learners may encounter frustration and disappointment in the learning process for various reasons. Faculties might not be familiar with adult learning principles. The online course developer may have no knowledge, experience, or the skills necessary for developing online courseware. Online course development can take longer time and more resources. It can also take longer time to deliver the course. It is, therefore, important that online course development be made efficient and effective for best student learning. [See PDF for complete abstract]

Locomotor activity of two sympatric slugs: implication for the invasion success of terrestrial invertebrates.

A central focus of invasion biology is to identify the traits that predict which introduced species will become invasive. Behavioral traits related to locomotor activity most likely play a pivotal role in determining a species’invasion success but have rarely been studied, particularly in terrestrial invertebrates. Here, we experimentally investigated the small-scale locomotor activity of two slug species with divergent invasion success in Europe, the highly invasive slug, Arion lusitanicus, and the closely related, non-invasive and native slug, Arion rufus. To do so, we used a multi-state capture-mark-recapture approach, and hypothesized that the invasive slug has a higher moving rate (keeps on moving) and leaving rate (leaves more frequently known places). A total of 221 invasive and 241 non-invasive slugs were individually marked using magnetic transponders and released in three study sites differing in habitat type. The slugs were recaptured using shelter traps, and moving and leaving rates were estimated. Both rates were significantly higher for the invasive slug, demonstrating a higher locomotor activity which might partly explain its invasion success. Our results provide evidence for the recently suggested idea that locomotor activity might be an important trait underlying animal invasions using for the first time terrestrial invertebrates.

A functional collagen adhesin gene, acm, in clinical isolates of Enterococcus faecium correlates with the recent success of this emerging nosocomial pathogen.

Enterococcus faecium recently evolved from a generally avirulent commensal into a multidrug-resistant health care-associated pathogen causing difficult-to-treat infections, but little is known about the factors responsible for this change. We previously showed that some E. faecium strains express a cell wall-anchored collagen adhesin, Acm. Here we analyzed 90 E. faecium isolates (99% acm(+)) and found that the Acm protein was detected predominantly in clinically derived isolates, while the acm gene was present as a transposon-interrupted pseudogene in 12 of 47 isolates of nonclinical origin. A highly significant association between clinical (versus fecal or food) origin and collagen adherence (P

Temperature and Resource Availability May Interactively Affect Over-Wintering Success of Juvenile Fish in a Changing Climate

The predicted global warming may affect freshwater systems at several organizational levels, from organism to ecosystem. Specifically, in temperate regions, the projected increase of winter temperatures may have important effects on the over-winter biology of a range of organisms and especially for fish and other ectothermic animals. However, temperature effects on organisms may be directed strongly by resource availability. Here, we investigated whether over-winter loss of biomass and lipid content of juvenile roach (Rutilus rutilus) was affected by the physiologically relatively small (2-5°C) changes of winter temperatures predicted by the Intergovernmental Panel on Climate Change (IPCC), under both natural and experimental conditions. This was investigated in combination with the effects of food availability. Finally, we explored the potential for a correlation between lake temperature and resource levels for planktivorous fish, i.e., zooplankton biomass, during five consecutive winters in a south Swedish lake. We show that small increases in temperature (+2°C) affected fish biomass loss in both presence and absence of food, but negatively and positively respectively. Temperature alone explained only a minor part of the variation when food availability was not taken into account. In contrast to other studies, lipid analyses of experimental fish suggest that critical somatic condition rather than critical lipid content determined starvation induced mortality. Our results illustrate the importance of considering not only changes in temperature when predicting organism response to climate change but also food-web interactions, such as resource availability and predation. However, as exemplified by our finding that zooplankton over-winter biomass in the lake was not related to over-winter temperature, this may not be a straightforward task.

More than just Good Luck. How to Explain the Success of Monte Carlo Simulations

Monte Carlo simulation is a powerful method in many natural and social sciences. But what sort of method is it? And where does its power come from? Are Monte Carlo simulations experiments, theories or something else? The aim of this talk is to answer these questions and to explain the power of Monte Carlo simulations. I provide a classification of Monte Carlo techniques and defend the claim that Monte Carlo simulation is a sort of inference.

Does the educational success of children growing up in stepfamilies differ from children growing up in single parent households?

Within the framework of research into educational inequality, this paper focuses on the educational success of children who experience parental separation prior to the transition from primary into secondary education. Related to this, the first education passage following primary school is observed. The question arises as to whether children growing up in single parent households after parental separation and whether children in this category who in addition experienced the formation of a stepfamily differ from one another and from children growing up in “nuclear families” in regard to their scholastic performance and transition success. For that reason, not only scholastic performance (grades) but also the type of school attended following primary school are of particular interest. Furthermore, differences regarding parental educational decision-making are examined (vgl. Stocké 2007). The analyses are based on data from the longitudinal study "BIKS 8-14" (educational processes, competence development and selection decisions in preschool- and school age) that has been undertaken at the Otto Friedrich University in Bamberg.

The Role of Corruption in Explaining the Electoral Success of New Political Parties in Central and Eastern Europe

More than 20 years after the collapse of the Soviet Union, the electoral volatility in Central and Eastern Europe (CEE) is still remarkably high. A considerable part of the volatility derives from the votes for new political parties, since they are very often on the winning side of elections. This paper examines corruption as potential determinant of their electoral success. It argues that the effect of corruption is twofold: On the onehand, the historically-grown corruption level reduces the electoral success of new political parties due to strong clientelist structures that bind the electorate to the established parties. On the other hand, an increase of the perceived corruption above the traditional corruption level leads to a loss of trust in the political elite and therefore boosts the electoral success of new competitors. A statistical analysis of all democratic elections in CEE between 1996 and 2011 confirms these two counteracting effects.

Evaluation of the success of medical management for presumptive cervical intervertebral disk herniation in dogs.

OBJECTIVE To determine the success of medical management of presumptive cervical disk herniation in dogs and variables associated with treatment outcome. DESIGN Retrospective case series. ANIMALS Dogs (n=88) with presumptive cervical disk herniation. METHODS Dogs with presumptive cervical and thoracolumbar disk herniation were identified from medical records at 2 clinics and clients were mailed a questionnaire related to the success of therapy, clinical recurrence of signs, and quality of life (QOL) as interpreted by the owner. Signalment, duration and degree of neurologic dysfunction, and medication administration were determined from medical records. RESULTS Ninety-seven percent of dogs (84/87) with complete information were described as ambulatory at initial evaluation. Successful treatment was reported for 48.9% of dogs with 33% having recurrence of clinical signs and 18.1% having therapeutic failure. Bivariable logistic regression showed that non-steroidal anti-inflammatory drug (NSAID) administration was associated with success (P=.035; odds ratio [OR]=2.52). Duration of cage rest and glucocorticoid administration were not significantly associated with success or QOL. Dogs with less-severe neurologic dysfunction were more likely to have a successful outcome (OR=2.56), but this association was not significant (P=.051). CONCLUSIONS Medical management can lead to an acceptable outcome in many dogs with presumptive cervical disk herniation. Based on these data, NSAIDs should be considered as part of the therapeutic regimen. Cage rest duration and glucocorticoid administration do not appear to benefit these dogs, but this should be interpreted cautiously because of the retrospective data collection and use of client self-administered questionnaire follow-up. CLINICAL RELEVANCE These results provide insight into the success of medical management for presumptive cervical disk herniation in dogs and may allow for refinement of treatment protocols.

Evaluation of the success of medical management for presumptive thoracolumbar intervertebral disk herniation in dogs.

OBJECTIVE To determine the success of medical management of presumptive thoracolumbar disk herniation in dogs and the variables associated with treatment outcome. STUDY DESIGN Retrospective case series. ANIMALS Dogs (n=223) with presumptive thoracolumbar disk herniation. METHODS Medical records from 2 clinics were used to identify affected dogs, and owners were mailed a questionnaire about success of therapy, recurrence of clinical signs, and quality of life (QOL) as interpreted by the owner. Signalment, duration and degree of neurologic dysfunction, and medication administration were determined from medical records. RESULTS Eighty-three percent of dogs (185/223) were ambulatory at initial evaluation. Successful treatment was reported for 54.7% of dogs, with 30.9% having recurrence of clinical signs and 14.4% classified as therapeutic failures. From bivariable logistic regression, glucocorticoid administration was negatively associated with success (P=.008; odds ratio [OR]=.48) and QOL scores (P=.004; OR=.48). The duration of cage rest was not significantly associated with success or QOL. Nonambulatory dogs were more likely to have lower QOL scores (P=.01; OR=2.34). CONCLUSIONS Medical management can lead to an acceptable outcome in many dogs with presumptive thoracolumbar disk herniation. Cage rest duration does not seem to affect outcome and glucocorticoids may negatively impact success and QOL. The conclusions in this report should be interpreted cautiously because of the retrospective data collection and the use of client self-administered questionnaire follow-up. CLINICAL RELEVANCE These results provide an insight into the success of medical management for presumptive thoracolumbar disk herniation in dogs and may allow for refinement of treatment protocols.

A retrospective analysis of factors influencing the success of autotransplanted posterior teeth

BACKGROUND Survival and success rates of tooth transplantations even after long follow-up periods have been shown to be very high. Nevertheless, it is important to analyse factors potentially influencing these rates. The aim of this study was to assess the influence on success of potential factors. METHODS The research was based on a retrospective analysis of clinical and radiological data from a sample of 59 subjects (75 transplanted teeth). The follow-up period varied from 0.44 to 12.28 years (mean 3.95 years). Success rates were calculated and depicted with Kaplan-Meier plots. Log-rank tests were used to analyse the effect of root development stage, apex width, the use of enamel matrix proteins or the surgeon on success of transplantations. RESULTS Results for success of premolar transplantations were comparable with already published data, while molars performed worse than shown in other studies. The surgeon performing the transplantation (p = 0.001) and tooth type (p ≤ 0.001) were significantly associated with transplantation success. Use of enamel matrix proteins (p = 0.10), root development stage (p = 0.13), the recipient area (p = 0.48) and apex width (p = 0.59) were not significantly associated with success. CONCLUSIONS Molar transplantations were not as successful as premolar transplantations; however, success rates varied greatly depending on the surgeon's experience. The use of enamel matrix proteins as well as root development stage, the recipient area and apex width did not show significant associations with success of tooth transplantations.