Microplastics (particles less than 5 mm) numerically dominate marine debris and occur from coastal waters to mid‐ocean gyres, where surface circulation concentrates them. Given the prevalence of plastic marine debris (PMD) and the rise in plastic production, the impacts of plastic on marine ecosystems will likely increase. Microscopic life (the “Plastisphere”) thrives on these tiny floating “islands” of debris and can be transported long distances. Using next‐generation DNA sequencing, we characterized bacterial communities from water and plastic samples from the North Pacific and North Atlantic subtropical gyres to determine whether the composition of different Plastisphere communities reflects their biogeographic origins. We found that these communities differed between ocean basins – and to a lesser extent between polymer types – and displayed latitudinal gradients in species richness. Our research reveals some of the impacts of microplastics on marine biodiversity, demonstrates that the effects and fate of PMD may vary considerably in different parts of the global ocean, and suggests that PMD mitigation will require regional management efforts.
The Clinical Engineering Center of the Northern New England/University of New Hampshire has developed a seminar on electrical safety for members of the nursing profession. This program provides an understanding of basic circuit theory, grounding problems, wiring systems, and electrical safety. Examples are drawn from actual clinical situations. Portions of the seminar are devoted to equipment demonstrations and to a panel discussion which provides the participants with an opportunity to ask questions. Through this experience, the nurses begin to view the function of a Clinical Engineer in a different light, their awareness of the role of the Clinical Engineering Center is expanded, and they become a second line of defense for electrical safety in the hospital.
Abstract Microbiomes play a critical role in promoting a range of host functions. Microbiome function, in turn, is dependent on its community composition. Yet, how microbiome taxa are assembled from their regional species pool remains unclear. Many possible drivers have been hypothesized, including deterministic processes of competition, stochastic processes of colonization and migration, and physiological ‘host‐effect’ habitat filters. The contribution of each to assembly in nascent or perturbed microbiomes is important for understanding host–microbe interactions and host health. In this study, we characterized the bacterial communities in a euryhaline fish and the surrounding tank water during salinity acclimation. To assess the relative influence of stochastic versus deterministic processes in fish microbiome assembly, we manipulated the bacterial species pool around each fish by changing the salinity of aquarium water. Our results show a complete and repeatable turnover of dominant bacterial taxa in the microbiomes from individuals of the same species after acclimation to the same salinity. We show that changes in fish microbiomes are not correlated with corresponding changes to abundant taxa in tank water communities and that the dominant taxa in fish microbiomes are rare in the aquatic surroundings, and vice versa . Our results suggest that bacterial taxa best able to compete within the unique host environment at a given salinity appropriate the most niche space, independent of their relative abundance in tank water communities. In this experiment, deterministic processes appear to drive fish microbiome assembly, with little evidence for stochastic colonization.
A synthesis procedure, easily implemented as a digital computer program, is presented whereby any p \times p matrix Y(s) of real rational functions of the complex frequency variable s can be realized as the short-circuit admittance matrix of a p -port active RC network. The realization requires a minimum number of capacitors- n = degree \{Y(s)\} -and no more than 2(p+n) inverting common ground voltage-controlled voltage sources. All the capacitors and ports are grounded.
A method to reduce the overshoot of the step response of a low-pass filter by including in that response a constant times its second derivative is considered. A technique to determine the value of the constant that minimizes overshoot is presented and applied to four conventional filters. Results of the modification procedure are presented.
