4,682 research outputs found

    Revising the UMLS Semantic Network

    Get PDF
    The integration of standardized biomedical terminologies into a single, unified knowledge representation system has formed a key area of applied informatics research in recent years. The Unified Medical Language System (UMLS) is the most advanced and most prominent effort in this direction, bringing together within its Metathesaurus a large number of distinct source-terminologies. The UMLS Semantic Network, which is designed to support the integration of these source-terminologies, has proved to be a highly successful combination of formal coherence and broad scope. We argue here, however, that its organization manifests certain structural problems, and we describe revisions which we believe are needed if the network is to be maximally successful in realizing its goals of supporting terminology integration

    Chandra Discovery of a Binary Active Galactic Nucleus in Mrk 739

    Full text link
    We have discovered a binary AGN in the galaxy Mrk 739 using Chandra and Swift BAT. We find two luminous L_2-10 keV=1.1*10^43 and 1.0*10^42 erg/s, unresolved nuclei with a projected separation of 3.4 kpc (5.8\pm0.1) coincident with two bulge components in the optical image. The western X-ray source (Mrk 739W) is highly variable (2.5x) during the 4-hour Chandra observation and has a very hard spectrum consistent with an AGN. While the eastern component was already known to be an AGN based on the presence of broad optical recombination lines, Mrk 739W shows no evidence of being an AGN in optical, UV, and radio observations, suggesting the critical importance of high spatial resolution hard X-ray observations (>2 keV) in finding these binary AGN. A high level of star formation combined with a very low L_[O III]/L_2-10 keV ratio cause the AGN to be missed in optical observations. CO observations of the (3-2) and (2-1) lines indicate large amounts of molecular gas in the system that could be driven towards the black holes during the violent galaxy collision and be key to fueling the binary AGN. Mrk 739E has a high Eddington ratio of 0.71 and a small black hole (log M_BH=7.05\pm0.3) consistent with an efficiently accreting AGN. Other than NGC 6240, this stands as the nearest case of a binary AGN discovered to date.Comment: 7 pages, 5 figures, Published in Astrophysical Journal Letters. Reformatted and fixed typos in v

    Who speaks for the future of Earth? How critical social science can extend the conversation on the Anthropocene

    Get PDF
    This paper asks how the social sciences can engage with the idea of the Anthropocene in productive ways. In response to this question we outline an interpretative research agenda that allows critical engagement with the Anthropocene as a socially and culturally bounded object with many possible meanings and political trajectories. In order to facilitate the kind of political mobilization required to meet the complex environmental challenges of our times, we argue that the social sciences should refrain from adjusting to standardized research agendas and templates. A more urgent analytical challenge lies in exposing, challenging and extending the ontological assumptions that inform how we make sense of and respond to a rapidly changing environment. By cultivating environmental research that opens up multiple interpretations of the Anthropocene, the social sciences can help to extend the realm of the possible for environmental politics

    Quark nova imprint in the extreme supernova explosion SN 2006gy

    Full text link
    The extremely luminous supernova 2006gy (SN 2006gy) is among the most energetic ever observed. The peak brightness was 100 times that of a typical supernova and it spent an unheard of 250 days at magnitude -19 or brighter. Efforts to describe SN 2006gy have pushed the boundaries of current supernova theory. In this work we aspire to simultaneously reproduce the photometric and spectroscopic observations of SN 2006gy using a quark nova model. This analysis considers the supernova explosion of a massive star followed days later by the quark nova detonation of a neutron star. We lay out a detailed model of the interaction between the supernova envelope and the quark nova ejecta paying special attention to a mixing region which forms at the inner edge of the supernova envelope. This model is then fit to photometric and spectroscopic observations of SN 2006gy. This QN model naturally describes several features of SN 2006gy including the late stage light curve plateau, the broad H{\alpha} line and the peculiar blue H{\alpha} absorption. We find that a progenitor mass between 20Msun and 40Msun provides ample energy to power SN 2006gy in the context of a QN.Comment: 15 pages, 9 figure

    Towards an explanation for the 30 Dor (LMC) Honeycomb nebula - the impact of recent observations and spectral analysis

    Full text link
    The unique Honeycomb nebula, most likely a peculiar supernova remnant, lies in 30 Doradus in the Large Magellanic Cloud. Due to its proximity to SN1987A, it has been serendipitously and intentionally observed at many wavelengths. Here, an optical spectral analysis of forbidden line ratios is performed in order to compare the Honeycomb high-speed gas with supernova remnants in the Galaxy and the LMC, with galactic Wolf-Rayet nebulae and with the optical line emission from the interaction zone of the SS433 microquasar and W50 supernova remnant system. An empirical spatiokinematic model of the images and spectra for the Honeycomb reveals that its striking appearance is most likely due to a fortuitous viewing angle. The Honeycomb nebula is more extended in soft X-ray emission and could in fact be a small part of the edge of a giant LMC shell revealed for the first time in this short wavelength domain. It is also suggested that a previously unnoticed region of optical emission may in fact be an extension of the Honeycomb around the edge of this giant shell. A secondary supernova explosion in the edge of a giant shell is considered for the creation of the Honeycomb nebula. A microquasar origin of the Honeycomb nebula as opposed to a simple supernova origin is also evaluated.Comment: 12 pages, 9 figures, accepted for publication in MNRA

    Jamming transitions in cancer

    Get PDF
    The traditional picture of tissues, where they are treated as liquids defined by properties such as surface tension or viscosity has been redefined during the last few decades by the more fundamental question: under which conditions do tissues display liquid-like or solid-like behaviour? As a result, basic concepts arising from the treatment of tissues as solid matter, such as cellular jamming and glassy tissues, have shifted into the current focus of biophysical research. Here, we review recent works examining the phase states of tissue with an emphasis on jamming transitions in cancer. When metastasis occurs, cells gain the ability to leave the primary tumour and infiltrate other parts of the body. Recent studies have shown that a linkage between an unjamming transition and tumour progression indeed exists, which could be of importance when designing surgery and treatment approaches for cancer patient

    Dissecting a supernova impostor's circumstellar medium: MUSEing about the SHAPE of eta Carinae's outer ejecta

    Get PDF
    Aims. The role of episodic mass loss is one of the outstanding questions in massive star evolution. The structural inhomogeneities and kinematics of their nebulae are tracers of their mass-loss history. We conduct a three-dimensional morpho-kinematic analysis of the ejecta of η Car outside its famous Homunculus nebula. Methods. We carried out the first large-scale integral field unit observations of η Car in the optical, covering a field of view of 1′× 1′ centered on the star. Observations with the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) reveal the detailed three-dimensional structure of η Car’s outer ejecta. Morpho-kinematic modeling of these ejecta is conducted with the code SHAPE. Results. The largest coherent structure in η Car’s outer ejecta can be described as a bent cylinder with roughly the same symmetry axis as the Homunculus nebula. This large outer shell is interacting with the surrounding medium, creating soft X-ray emission. Doppler velocities of up to 3000 km s-1 are observed. We establish the shape and extent of the ghost shell in front of the southern Homunculus lobe and confirm that the NN condensation can best be modeled as a bowshock in the orbital/equatorial plane. Conclusions. The SHAPE modeling of the MUSE observations provides a significant gain in the study of the three-dimensional structure of η Car’s outer ejecta. Our SHAPE modeling indicates that the kinematics of the outer ejecta measured with MUSE can be described by a spatially coherent structure, and that this structure also correlates with the extended soft X-ray emission associated with the outer debris field. The ghost shell immediately outside the southern Homunculus lobe hints at a sequence of eruptions within the time frame of the Great Eruption from 1837–1858 or possibly a later shock/reverse shock velocity separation. Our 3D morpho-kinematic modeling and the MUSE observations constitute an invaluable dataset to be confronted with future radiation-hydrodynamics simulations. Such a comparison may shed light on the yet elusive physical mechanism responsible for η Car-like eruptions

    Growth and Fatty Acid Composition of Marine Microalga Nannochloropsis SP in Medium Enriched with Magnesium

    Full text link
    Micro-algae are to be an attractive way to produce bio-diesel due to high photosynthetic yields and lipid accumulation in cells. This high productivity combined with possibility to uptake CO2 stimulated its utilization as a biological mitigation method of CO2, at once as an alternative renewable source of energy. Growth characteristics and chemical composition of micro-algae can be altered by culture environment. Nutrient sufficiency,included magnesium element (Mg2+) is important factors on overall biochemical composition. In study, Nannochloropsis sp was cultivated in Erlenmeyer 250 ml containing 200 ml f/2 medium. There are three groups of treatment with different levelof magnesium (Mg2+), i.e. 0 (M0); 0.1mgL-1 (M1); and 1.0 mgL-1 (M2). All treatment was designed triplicate in batch system. Culture was then aerated continuously with sterile atmospheric air (1.5 L.min-1). Cells were harvested on 25th day after inoculation and analyzed. Data showed that Chlorophyll-a increased linearly with time and maximum at 18th days of growth period, i.e. 23.57; 26.44; and 27.74mgL-1, for M0; M1; and M2,respectively. Chlorophyll-a content decreased significantly when pH dropped to 5-6.Enrichment with Mg2+ increased the chlorophyll-a content 12.2-17.7%. Dry cell reached 375-400mgL-1 in all treatment. Lipid content of Nannochloropsis sp in control (M0) is 55.3%, higher than M1 and M2. Saturated fatty acid tends to increase from 80.70 (M0)to 96.70 (M1) and 94.53% (M2). Fatty acid of M0 and M1 was composed dominantly by palmitic acid (C16:0), i.e. 49.19-70.75% total fatty acids. Meanwhile, M2 treatment was dominantly by lauric acid (C12:0), i.e. 32.98%

    Investigation of congestive heart failure in beef cattle in a feedyard at a moderate altitude in western Nebraska

    Get PDF
    Right-sided congestive heart failure (brisket disease) commonly occurs in cattle raised at elevations \u3e2,500– 3,500 m. We investigated clinical cases resembling brisket disease at a western Nebraska feedyard at a moderate altitude (1,369 m). Over a 15-mo period (2009–2010), we examined 17 cases (16 steers and 1 heifer), all purebred Angus. All animals had clinical right-sided heart failure: brisket and ventral abdominal edema, and severe chronic passive congestion of the liver. Gross examination confirmed right ventricular hypertrophy (left ventricle plus septum: right ventricle weight ratio mean: 1.33 vs. 2.8–4.0 reference interval). Microscopically, all 17 cases had interstitial fibrosis (mean score: 2.4 ± 0.8) and 6 had replacement fibrosis of the right ventricle, whereas 14 had interstitial fibrosis (mean score: 1.2 ± 0.2) and 0 had replacement fibrosis of the left ventricle. Lesions of arteriosclerosis were seen in 9 of 16 cases in 51 of 571 (8.9%) right ventricular coronary arteries, and in 10 of 16 cases in 52 of 366 (14.2%) left ventricular coronary arteries. The probability of coronary arteriosclerosis was greater in papillary ventricular muscle (OR = 11.3; p \u3c 0.0001), left ventricle (OR = 4.8; p \u3c 0.0001), and larger arteries (OR = 1.01; p \u3c 0.0001). Pulmonary arteries and arterioles had lesions compatible with hypoxia-induced pulmonary hypertension. We hypothesize that moderate hypobaric conditions significantly contributed to disease in cattle genetically predisposed to hypoxia-induced pulmonary hypertension. Adiposity, coronary arteriosclerosis, and left ventricular fibrosis may have contributed to the condition; however, the cattle died prior to development of advanced obesity
    • …
    corecore