44 research outputs found

    Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea

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    Breakup of the near-continuous winter sea ice into discrete summer ice floes is an important transition that dictates the evolution and fate of the marginal ice zone (MIZ) of the Arctic Ocean. During the winter of 2014, more than 50 autonomous drifting buoys were deployed in four separate clusters on the sea ice in the Beaufort Sea, as part of the Office of Naval Research MIZ program. These systems measured the ocean-ice-atmosphere properties at their location whilst the sea ice parameters in the surrounding area of these buoy clusters were continuously monitored by satellite TerraSAR-X Synthetic Aperture Radar. This approach provided a unique Lagrangian view of the winter-to-summer transition of sea ice breakup and floe size distribution at each cluster between March and August. The results show the critical timings of a) temporary breakup of winter sea ice coinciding with strong wind events and b) spring breakup (during surface melt, melt ponding and drainage) leading to distinctive summer ice floes. Importantly our results suggest that summer sea ice floe distribution is potentially affected by the state of winter sea ice, including the composition and fracturing (caused by deformation events) of winter sea ice, and that substantial mid-summer breakup of sea ice floes is likely linked to the timing of thermodynamic melt of sea ice in the area. As the rate of deformation and thermodynamic melt of sea ice has been increasing in the MIZ in the Beaufort Sea, our results suggest that these elevated factors would promote faster and more enhanced breakup of sea ice, leading to a higher melt rate of sea ice and thus a more rapid advance of the summer MIZ

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

    Grey whale (Eschrichtius robustus) in Norwegian waters 2000 years ago

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    The modern distribution of the grey whale (Eschrichtius robustus) is restricted to the North Pacific Ocean, but during the Holocene it occurred also in the North Atlantic Ocean, perhaps as recently as the 17th century. In the western Atlantic, subfossil bones of 12 specimens of grey whale have previously been reported, whereas in the eastern Atlantic there are at least 25 subfossil remains of grey whale from the postglacial period, mostly from the Netherlands, along with one in Belgium, three in England and one in Sweden, ranging in age from approximately 10,000 to a few hundred years ago. Here we utilise a new method of identifying species from fragmentary bones, using collagen fingerprinting, to screen 373 cetacean remains from along the Norwegian coast, including the remains of at least one grey whale specimen dating to 1930–1750 years ago, which was recovered from Kringlevågen in the municipality of Solund (61°, 01″ N, 4°73″E). This find, confirmed by ancient DNA analysis, is the most northerly record of this locally extinct species and increases our understanding of grey whale palaeobiogeography in the North Atlantic

    Nanodentures and Mechanical Electrodynamics: Three-Dimensional Relative Orientation of Plasmonic Nanoarches from Absorption Spectra

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    We propose a general theme, labeled mechanical electrodynamics, where the relative three-dimensional (3-D) orientation of particles with nontrivial geometries is tracked based on the details of the absorption spectrum beyond a one-dimensional (1-D) distance dependence. Specifically, we simulate absorption spectra of a subwavelength denture-like nanostructure with freely moving parts. The nanodentures are made of two gold nanoarches that either open and close or rotate about a single arch base (hinge rotation). We show how the absorption spectrum for the nanodentures changes depending on orientation and position. There is a ∼0.1–0.2 eV shift in absorbance peak frequencies as the denture closes, corresponding to an increased coupling between the two gold arches, while a hinge rotation results in a depletion of one absorbance peak (1.48 eV) with the simultaneous emergence of a new absorbance peak at lower frequencies (0.88 eV). The unique spectral signature of each position and orientation of the nanodentures points to a variety of applications. One will be experimentally tracking and measuring orientation and position of plasmonic-coupled nanoparticles using simple methods such as UV–vis or IR spectral analysis. Additionally, the denture structure will tune in and out of different plasmon resonance frequencies, or turn “on and off,” depending on its orientation. The simulations were performed efficiently by the recent near-field (NF) approach, which is a time-dependent Poisson algorithm that shares a lot of the machinery of full-fledged Maxwell equations but allows for much larger time steps and therefore can treat large systems
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