Use of ultrasonography to facilitate surgical removal of non-enteric foreign bodies in 17 dogs

Plant material foreign bodies may cause vague clinical signs at the time of initial presentation but can progress to cause persistent or recurrent abscessation, sinus tract formation and debilitating disease, due to migration of the foreign body, severe tissue reaction and secondary infection. Ultrasonography is a non-invasive technique that can be used to identify precisely the presence, location and size of radiolucent foreign bodies. Early identification of foreign bodies using ultrasonography facilitates surgical retrieval before further migration and tissue injury occur. This paper reviews the ultrasonographic findings and outcome in 17 dogs with non-enteric, radiolucent, plant material foreign bodies.     

Role of mobile DNA in the evolution of vancomycin-resistant Enterococcus faecalis

The complete genome sequence of Enterococcus faecalis V583, a vancomycin-resistant clinical isolate, revealed that more than a quarter of the genome consists of probable mobile or foreign DNA. One of the predicted mobile elements is a previously unknown vanB vancomycin-resistance conjugative transposon. Three plasmids were identified, including two pheromone-sensing conjugative plasmids, one encoding a previously undescribed pheromone inhibitor. The apparent propensity for the incorporation of mobile elements probably contributed to the rapid acquisition and dissemination of drug resistance in the enterococci.     

Linking models of polymerization and dynamics to predict branched polymer structure and flow

We present a predictive scheme connecting the topological structure of highly branched entangled polymers, with industrial-level complexity, to the emergent viscoelasticity of the polymer melt. The scheme is able to calculate the linear and nonlinear viscoelasticity of a stochastically branched "high-pressure free radical" polymer melt as a function of the chemical kinetics of its formation. The method combines numerical simulation of polymerization with the tube/entanglement physics of polymer dynamics extended to fully nonlinear response. We compare calculations for a series of low-density polyethylenes with experiments on structural and viscoelastic properties. The method provides a window onto the molecular processes responsible for the optimized rheology of these melts, connecting fundamental science to process in complex flow, and opens up the in silico design of new materials.     

Behavioral responses of bottlenose dolphins, Tursiops truncatus, to gillnets and acoustic alarms

Along the east coast of the United States, by-catches of bottlenose dolphins, Tursiops truncatus, in gillnet fisheries exceed removal levels set under the US Marine Mammal Protection Act. One measure proposed to reduce this mortality is the use of acoustic alarms, or pingers, which have proven effective in reducing by-catches of other small cetaceans, but have not been tested with bottlenose dolphins. We examined the responses of bottlenose dolphins to a commercial gillnet equipped with functional (active) and non-functional (control) Dukane NetMark® 1000 alarms near Fort Macon, NC. Between 5 April and 10 May 2001 we used a theodolite to track 59 groups of dolphins around the net. Choice of treatment was random each day and the two shore-based observers were unaware of whether alarms were active (13 days) or controls (9 days). There were no significant differences in the number of groups observed (P=0.315; 1−β=0.835) or in the closest observed approach to the net (P=0.307; 1−β=0.828) between treatments. However, dolphins entered a circular buffer approximately 100 m around the net more frequently with control than active alarms (P=0.015). We conclude that some dolphins responded to the alarms by avoiding the net, but caution that the potential efficacy of alarms is confounded by dolphin behavior. Most dolphins were aware of the net, regardless of the status of alarms, and some dolphins fed on fish in the net or discarded by the fishing vessel. We believe that it would be unwise to use pingers in these fisheries because of the limited behavioral responses we observed in our experiment. Furthermore, the responses we observed are likely to diminish or change over time as dolphins habituate or sensitize to these alarms. Further research is required to understand the behavior responsible for entanglement.