300 research outputs found

    Theoretical approaches in adsorption: alkali adatom investigations

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    We discuss how different properties at surfaces could require for different theoretical treatments within the first-principles density functional theory. Energies and structures are accurately determined by adopting the supercell geometry. Surface states are more conveniently described by the Green function embedding approach, which is able to take into account a truly semi-infinite solid and hence real continuous spectra. In this way a detailed analysis of discrete and resonant states is provided. We mainly describe the embedding method and provide examples to compare the two approaches. We focus next on the structural and electronic properties of alkali adatoms. The adsorption structure of Na/Cu(001) at low coverages is calculated within the supercell geometry motivated by the results of the Cambridge group on surface diffusion by 3He spin echo scattering. The dispersion, energy, effective mass, and width of surface (quantum well and image) states of alkali atoms on Cu(111) are worked out by the embedding approach and compared with experiments

    A small solitary non-parasitic hepatic cyst causing an intra-hepatic bile duct stricture: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>We report an unusual presentation of a small hepatic cyst causing cholangitis.</p> <p>Case presentation</p> <p>A 70-year-old Asian man was hospitalized for aggravated chronic pain in the right upper portion of his abdomen. Fever developed after admission. Laboratory tests revealed elevated hepatobiliary enzymes, inflammatory markers and carbohydrate antigen 19-9 without hyperbilirubinemia. Ultrasound and computed tomography demonstrated dilatation of the left intra-hepatic bile ducts. Endoscopic retrograde cholangiopancreatography showed that the right intra-hepatic bile ducts were normally filled with contrast medium, but the left intra-hepatic bile ducts were not seen in the confluence. A left hepatectomy was performed because a hidden malignancy could not be excluded. The surgical findings showed no tumor around the bile duct but rather a 2 cm cyst in segment four of Couinaud's category of the liver around the hilum. The pathology report was a solitary non-parasitic hepatic cyst compressing the bile duct.</p> <p>Conclusion</p> <p>A very small solitary hepatic cyst might cause hepatic duct stricture if it is located near the hepatic hilum, and should be considered in the differential diagnosis of a hepatic duct stricture.</p

    Amplitudes With Different Helicity Configurations Of Noncommutative QED

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    The amplitudes of purely photonic and photon{2-fermion processes of non- commutative QED (NCQED) are derived for different helicity configurations of photons. The basic ingredient is the NCQED counterpart of Yang-Mills recursion relations by means of Berends and Giele. The explicit solutions of recursion relations for NCQED photonic processes with special helicity configurations are presented.Comment: 23 pages, 2 figure

    Noncommutative quantum mechanics and Bohm's ontological interpretation

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    We carry out an investigation into the possibility of developing a Bohmian interpretation based on the continuous motion of point particles for noncommutative quantum mechanics. The conditions for such an interpretation to be consistent are determined, and the implications of its adoption for noncommutativity are discussed. A Bohmian analysis of the noncommutative harmonic oscillator is carried out in detail. By studying the particle motion in the oscillator orbits, we show that small-scale physics can have influence at large scales, something similar to the IR-UV mixing

    Expert Consensus Guidelines for Stocking of Antidotes in Hospitals That Provide Emergency Care

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    We provide recommendations for stocking of antidotes used in emergency departments (EDs). An expert panel representing diverse perspectives (clinical pharmacology, medical toxicology, critical care medicine, hematology/oncology, hospital pharmacy, emergency medicine, emergency medical services, pediatric emergency medicine, pediatric critical care medicine, poison centers, hospital administration, and public health) was formed to create recommendations for antidote stocking. Using a standardized summary of the medical literature, the primary reviewer for each antidote proposed guidelines for antidote stocking to the full panel. The panel used a formal iterative process to reach their recommendation for both the quantity of antidote that should be stocked and the acceptable timeframe for its delivery. The panel recommended consideration of 45 antidotes; 44 were recommended for stocking, of which 23 should be immediately available. In most hospitals, this timeframe requires that the antidote be stocked in a location that allows immediate availability. Another 14 antidotes were recommended for availability within 1 hour of the decision to administer, allowing the antidote to be stocked in the hospital pharmacy if the hospital has a mechanism for prompt delivery of antidotes. The panel recommended that each hospital perform a formal antidote hazard vulnerability assessment to determine its specific need for antidote stocking. Antidote administration is an important part of emergency care. These expert recommendations provide a tool for hospitals that offer emergency care to provide appropriate care of poisoned patients

    High and low density patches in simulated liquid water

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    We present insights into the nature of structural heterogeneities in liquid water by characterizing the empty space within the hydrogen bond network. Using molecular dynamics simulations, we show that density fluctuations create regions of empty space characterized by a diverse morphology – from spherical to fractal-like voids. These voids allow for the identification of low and high density patches of the liquid, encompassing short (0.3-0.5 nm) as well as long (1-2 nm) length-scales. In addition, we show that the formation of these patches is coupled to collective fluctuations involving the topology of hydrogen-bonded rings of water molecules. In particular, water molecules in the high density patches tend to be slightly more tetrahedral – which is consistent with the predictions of the hydrophobic effect

    Voluntary self-poisoning as a cause of admission to a tertiary hospital internal medicine clinic in Piraeus, Greece within a year

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    BACKGROUND: Out of 1705 patients hospitalised for various reasons in the 3(rd) Internal Medicine Department of the Regional General Hospital of Nikaea, in Piraeus, 146(8,5%) persons were admitted for drug intoxication between November 1999 and November 2000. METHODS: On average, these persons [male 50(34,2%) – female 96(65,8%)] were admitted to the hospital within 3.7 hours after taking the drug. RESULTS: The drugs that were more frequently taken, alone or in combination with other drugs, were sedatives (67.1%), aspirins and analgesics (mainly paracetamol) (43.5%). 38.3% of patients had a mental illness history, 31.5% were in need of psychiatric help and 45.2% had made a previous suicide attempt. No death occurred during the above period and the outcome of the patients' health was normal. After mental state examination, the mental illnesses diagnosed were depression (20.96%), psychosis (15.32%), dysthymic disorder (16,2%), anxiety disorder (22.58%) and personality disorder (8.87%). CONCLUSIONS: Self-poisoning remains a crucial problem. The use of paracetamol and sedatives are particularly important in the population studied. Interpersonal psychiatric therapy may be a valuable treatment after people tried to poison themselves

    Enabling Universal Memory by Overcoming the Contradictory Speed and Stability Nature of Phase-Change Materials

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    The quest for universal memory is driving the rapid development of memories with superior all-round capabilities in non-volatility, high speed, high endurance and low power. Phase-change materials are highly promising in this respect. However, their contradictory speed and stability properties present a key challenge towards this ambition. We reveal that as the device size decreases, the phase-change mechanism changes from the material inherent crystallization mechanism (either nucleation- or growth-dominated), to the hetero-crystallization mechanism, which resulted in a significant increase in PCRAM speeds. Reducing the grain size can further increase the speed of phase-change. Such grain size effect on speed becomes increasingly significant at smaller device sizes. Together with the nano-thermal and electrical effects, fast phase-change, good stability and high endurance can be achieved. These findings lead to a feasible solution to achieve a universal memory
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