266 research outputs found
The shock compression of microorganism-loaded broths and emulsions: Experiments and simulations
By carefully selecting flyer plate thickness and the geometry of a target capsule for
bacterial broths and emulsions, we have successfully subjected the contents of the capsule to
simultaneous shock and dynamic compression when subjected to a flyer-plate impact
experiment. The capsules were designed to be recovered intact so that post experimental
analysis could be done on the contents. ANSYS® AUTODYN hydrocode simulations were
carried out to interrogate the deformation of the cover plate and the wave propagation in the
fluid. Accordingly, we have shown that microorganisms such as Escherichia coli,
Enterococcus faecalis and Zygosaccharomyces bailii are not affected by this type of loading
regime. However, by introducing a cavity behind the broth we were able to observe limited
kill in the yeast sample. Further, on using this latter technique with emulsions it was shown
that greater emulsification of an oil-based emulsion occurred due to the cavitation that was
introduced
A gas gun based technique for studying the role of temperature in dynamic fracture and fragmentation
Collapsing Arctic coastlines
A holistic and transdisciplinary approach is urgently required to investigate the physical and socio-economic impacts of collapsing coastlines in the Arctic nearshore zone
Prototypes for Content-Based Image Retrieval in Clinical Practice
Content-based image retrieval (CBIR) has been proposed as key technology for computer-aided diagnostics (CAD). This paper reviews the state of the art and future challenges in CBIR for CAD applied to clinical practice
What Happened to Gray Whales during the Pleistocene? The Ecological Impact of Sea-Level Change on Benthic Feeding Areas in the North Pacific Ocean
Gray whales (Eschrichtius robustus) undertake long migrations, from Baja California to Alaska, to feed on seasonally productive benthos of the Bering and Chukchi seas. The invertebrates that form their primary prey are restricted to shallow water environments, but global sea-level changes during the Pleistocene eliminated or reduced this critical habitat multiple times. Because the fossil record of gray whales is coincident with the onset of Northern Hemisphere glaciation, gray whales survived these massive changes to their feeding habitat, but it is unclear how.We reconstructed gray whale carrying capacity fluctuations during the past 120,000 years by quantifying gray whale feeding habitat availability using bathymetric data for the North Pacific Ocean, constrained by their maximum diving depth. We calculated carrying capacity based on modern estimates of metabolic demand, prey availability, and feeding duration; we also constrained our estimates to reflect current population size and account for glaciated and non-glaciated areas in the North Pacific. Our results show that key feeding areas eliminated by sea-level lowstands were not replaced by commensurate areas. Our reconstructions show that such reductions affected carrying capacity, and harmonic means of these fluctuations do not differ dramatically from genetic estimates of carrying capacity.Assuming current carrying capacity estimates, Pleistocene glacial maxima may have created multiple, weak genetic bottlenecks, although the current temporal resolution of genetic datasets does not test for such signals. Our results do not, however, falsify molecular estimates of pre-whaling population size because those abundances would have been sufficient to survive the loss of major benthic feeding areas (i.e., the majority of the Bering Shelf) during glacial maxima. We propose that gray whales survived the disappearance of their primary feeding ground by employing generalist filter-feeding modes, similar to the resident gray whales found between northern Washington State and Vancouver Island
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