445 research outputs found

    A New Paradigm for Parallel Adaptive Meshing Algorithms

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    Comparison of Alexandrium spp. surface sediment cyst maps from Quartermaster Harbor in 2007 and 2017

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    Quartermaster Harbor (QMH), in central Puget Sound, has historically been a hotspot for the occurrence of the toxic dinoflagellate Alexandrium spp. and associated summer shellfish bed closures. Alexandrium spp. overwinters as cysts in the sediment and germinates into swimming vegetative cells during the summer when conditions are right. Alexandrium spp. produces neurotoxins which can be concentrated in the tissue of filter-feeding shellfish, which in turn can be fatal to humans if ingested. In 2005, the first Puget Sound wide surface sediment cyst mapping survey found QMH to have the highest concentration of Alexandrium spp. cysts in the sound. A more detailed surface sediment Alexandrium spp. cyst map of QMH was constructed in the winter of 2007/2008 using 24 van veen samples. The highest concentration of cysts was in the inner harbor and central western shore of the outer harbor. Cyst concentration was low near the mouth of the harbor, where tidal currents are highest. Water circulation models of QMH by WADOE found that the QMH inner harbor has a residence time of 1-3 months, which could lead to retention and increased concentration of cysts within the harbor. Puget Sound wide surveys in the winters of 2011, 2012 and 2013 once again found high concentrations of Alexandrium spp. cysts in the surface sediments of QMH, although not as high as previously. The same 24 station detailed survey of QMH cysts and sediments was mapped again in 2017 to see if the distribution pattern of cysts in the bay had changed. The general pattern of relative abundance has remained the same, however the concentration overall has decreased slightly to about half of what it was ten years ago. This may be due to biological bloom dynamics controlling the absolute abundance, while physical forcing conditions determine the relative concentration spatial distribution

    Broadening of Plasmonic Resonance Due to Electron Collisions with Nanoparticle Boundary: а Quantum Mechanical Consideration

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    We present a quantum mechanical approach to calculate broadening of plasmonic resonances in metallic nanostructures due to collisions of electrons with the surface of the structure. The approach is applicable if the characteristic size of the structure is much larger than the de Broglie electron wavelength in the metal. The approach can be used in studies of plasmonic properties of both single nanoparticles and arrays of nanoparticles.Comment: 9 page

    Beyond spheres of influence: the myth of the state and Russia’s seductive power in Kyrgyzstan

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    This article questions the analytical value of “spheres of influence” for understanding power and the state in the post-Soviet region and beyond, based on a critical deconstruction of the ontological and epistemological assumptions inherent in the concept. It proposes an alternative reading of power and the state, drawing on the concept of “seductive power” at a distance and Timothy Mitchell’s “state effect.” Rather than the concept of a sphere of influence, a highly politicized concept that conveys an ontology that flattens and divides space, essentializes the state, and relies on an intentionalist account of power, we need an analytical framework that can help us make sense of the multiple, varied spatialities and historical legacies that produce the state and power. I demonstrate this through an extended discussion of Russian power in Kyrgyzstan, a country often described as a Russian client state. Mobilizing recent re-conceptualizations of state and power in anthropology and political geography, I present an analysis of Russia’s seductive power in Kyrgyzstan and the way it contributes to producing Kyrgyz state-ness. I also show how Russia’s Great Power myth is itself evolving and conclude that the differentiated, relational production of space and power in either Kyrgyz or Russian myths of the state is not captured by a the concept of a return to spheres of influence

    Chromosomal-level assembly of the Asian Seabass genome using long sequence reads and multi-layered scaffolding

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    We report here the ~670 Mb genome assembly of the Asian seabass (Lates calcarifer), a tropical marine teleost. We used long-read sequencing augmented by transcriptomics, optical and genetic mapping along with shared synteny from closely related fish species to derive a chromosome-level assembly with a contig N50 size over 1 Mb and scaffold N50 size over 25 Mb that span ~90% of the genome. The population structure of L. calcarifer species complex was analyzed by re-sequencing 61 individuals representing various regions across the species' native range. SNP analyses identified high levels of genetic diversity and confirmed earlier indications of a population stratification comprising three clades with signs of admixture apparent in the South-East Asian population. The quality of the Asian seabass genome assembly far exceeds that of any other fish species, and will serve as a new standard for fish genomics

    Catching Element Formation In The Act

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    Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.Comment: 14 pages including 3 figure

    A “Wear and Tear” Hypothesis to Explain Sudden Infant Death Syndrome

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    Sudden infant death syndrome (SIDS) is the leading cause of death among USA infants under 1 year of age accounting for ~2,700 deaths per year. Although formally SIDS dates back at least 2,000 years and was even mentioned in the Hebrew Bible (Kings 3:19), its etiology remains unexplained prompting the CDC to initiate a sudden unexpected infant death case registry in 2010. Due to their total dependence, the ability of the infant to allostatically regulate stressors and stress responses shaped by genetic and environmental factors is severely constrained. We propose that SIDS is the result of cumulative painful, stressful, or traumatic exposures that begin in utero and tax neonatal regulatory systems incompatible with allostasis. We also identify several putative biochemical mechanisms involved in SIDS. We argue that the important characteristics of SIDS, namely male predominance (60:40), the significantly different SIDS rate among USA Hispanics (80% lower) compared to whites, 50% of cases occurring between 7.6 and 17.6 weeks after birth with only 10% after 24.7 weeks, and seasonal variation with most cases occurring during winter, are all associated with common environmental stressors, such as neonatal circumcision and seasonal illnesses. We predict that neonatal circumcision is associated with hypersensitivity to pain and decreased heart rate variability, which increase the risk for SIDS. We also predict that neonatal male circumcision will account for the SIDS gender bias and that groups that practice high male circumcision rates, such as USA whites, will have higher SIDS rates compared to groups with lower circumcision rates. SIDS rates will also be higher in USA states where Medicaid covers circumcision and lower among people that do not practice neonatal circumcision and/or cannot afford to pay for circumcision. We last predict that winter-born premature infants who are circumcised will be at higher risk of SIDS compared to infants who experienced fewer nociceptive exposures. All these predictions are testable experimentally using animal models or cohort studies in humans. Our hypothesis provides new insights into novel risk factors for SIDS that can reduce its risk by modifying current infant care practices to reduce nociceptive exposures

    Oxygen tension regulates the miRNA profile and bioactivity of exosomes released from extravillous trophoblast cells - liquid biopsies for monitoring complications of pregnancy

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    Our understanding of how cells communicate has undergone a paradigm shift since the recent recognition of the role of exosomes in intercellular signaling. In this study, we investigated whether oxygen tension alters the exosome release and miRNA profile from extravillous trophoblast (EVT) cells, modifying their bioactivity on endothelial cells (EC). Furthermore, we have established the exosomal miRNA profile at early gestation in women who develop pre-eclampsia (PE) and spontaneous preterm birth (SPTB). HTR-8/SVneo cells were used as an EVT model. The effect of oxygen tension (i.e. 8% and 1% oxygen) on exosome release was quantified using nanocrystals (Qdot®) coupled to CD63 by fluorescence NTA. A real-time, live-cell imaging system (Incucyte™) was used to establish the effect of exosomes on EC. Plasma samples were obtained at early gestation (<18 weeks) and classified according to pregnancy outcomes. An Illumina TrueSeq Small RNA kit was used to construct a small RNA library from exosomal RNA obtained from EVT and plasma samples. The number of exosomes was significantly higher in EVT cultured under 1% compared to 8% oxygen. In total, 741 miRNA were identified in exosomes from EVT. Bioinformatic analysis revealed that these miRNA were associated with cell migration and cytokine production. Interestingly, exosomes isolated from EVT cultured at 8% oxygen increased EC migration, whilst exosomes cultured at 1% oxygen decreased EC migration. These changes were inversely proportional to TNF-α released from EC. Finally, we have identified a set of unique miRNAs in exosomes from EVT cultured at 1% oxygen and exosomes isolated from the circulation of mothers at early gestation, who later developed PE and SPTB. We suggest that aberrant exosomal signalling by placental cells is a common aetiological factor in pregnancy complications characterised by incomplete SpA remodeling and is therefore a clinically relevant biomarker of pregnancy complications.Grace Truong, Dominic Guanzon, Vyjayanthi Kinhal, Omar Elfeky, Andrew Lai, Sherri Longo, Zarin Nuzhat, Carlos Palma, Katherin Scholz-Romero, Ramkumar Menon, Ben W. Mol, Gregory E. Rice, Carlos Salomo
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