514 research outputs found

    Analysis of IUE observations of CS in Comet Bradfield (1979 l)

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    The high resolution rotational band profiles were fitted with theoretical band profiles which are derived using a Boltzmann temperature of 70 K. A very rapid variation with heliocentric distance for the CS brightness was found. The implications of these results for models of the coma along with the origin of the CS species are discussed

    Modern Observational Techniques for Comets

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    Techniques are discussed in the following areas: astrometry, photometry, infrared observations, radio observations, spectroscopy, imaging of coma and tail, image processing of observation. The determination of the chemical composition and physical structure of comets is highlighted

    Accessing Structural, Electronic, Transport and Mesoscale Properties of Li-GICs via a Complete DFTB Model with Machine-Learned Repulsion Potential

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    Lithium-graphite intercalation compounds (Li-GICs) are the most popular anode material for modern lithium-ion batteries and have been subject to numerous studies—both experimental and theoretical. However, the system is still far from being consistently understood in detail across the full range of state of charge (SOC). The performance of approaches based on density functional theory (DFT) varies greatly depending on the choice of functional, and their computational cost is far too high for the large supercells necessary to study dilute and non-equilibrium configurations which are of paramount importance for understanding a complete charging cycle. On the other hand, cheap machine learning methods have made some progress in predicting, e.g., formation energetics, but fail to provide the full picture, including electrostatics and migration barriers. Following up on our previous work, we deliver on the promise of providing a complete and affordable simulation framework for Li-GICs. It is based on density functional tight binding (DFTB), which is fitted to dispersion-corrected DFT data using Gaussian process regression (GPR). In this work, we added the previously neglected lithium–lithium repulsion potential and extend the training set to include superdense Li-GICs (LiC6−x; x>0) and lithium metal, allowing for the investigation of dendrite formation, next-generation modified GIC anodes, and non-equilibrium states during fast charging processes in the future. For an extended range of structural and energetic properties—layer spacing, bond lengths, formation energies and migration barriers—our method compares favorably with experimental results and with state-of-the-art dispersion-corrected DFT at a fraction of the computational cost. We make use of this by investigating some larger-scale system properties—long range Li–Li interactions, dielectric constants and domain-formation—proving our method’s capability to bring to light new insights into the Li-GIC system and bridge the gap between DFT and meso-scale methods such as cluster expansions and kinetic Monte Carlo simulations

    Breaking the Cycle of Pain In Diabetic Peripheral Neuropathy

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    An attitude of helplessness pervades both patients and health professionals when dealing with the problems of dia betic peripheral neuropathy. Those afflicted are often over whelmed by the pain and find themselves unable to fulfill the daily requirements of their diabetes regimen. The in consistencies in amounts and timing of meals, levels of ac tivity, and scheduling of insulin injections can result in hyperglycemia, a state that has been found to correlate strongly with the occurrence of nerve damage. Thus the pain perpetrates itself. For the health professional, having to confront this devastating pain without objective factors to assess and few scientific treatment measures to offer con tributes to a sense of inadequacy and ignorance. It is fre quently assumed that "nothing can be done." In reality, health professionals do have something to offer the person suffering from this condition. First, they can provide infor mation about the relationship between control and compli cations, and explain the need for the patient to change those behaviors that may be perpetuating the pain. Sec ond, and most importantly, health professionals can con vey support and confidence, without which many patients will be unable to make the changes in their behavior neces sary to resolve their pain.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68854/2/10.1177_014572178501100103.pd

    Intramolecular bonds resolved on a semiconductor surface

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    Noncontact atomic force microscopy (NC-AFM) is now routinely capable of obtaining submolecular resolution, readily resolving the carbon backbone structure of planar organic molecules adsorbed on metal substrates. Here we show that the same resolution may also be obtained for molecules adsorbed on a reactive semiconducting substrate. Surprisingly, this resolution is routinely obtained without the need for deliberate tip functionalization. Intriguingly, we observe two chemically distinct apex types capable of submolecular imaging. We characterize our tip apices by “inverse imaging” of the silicon adatoms of the Si(111)−7×7 surface and support our findings with detailed density functional theory (DFT) calculations. We also show that intramolecular resolution on individual molecules may be readily obtained at 78 K, rather than solely at 5 K as previously demonstrated. Our results suggest a wide range of tips may be capable of producing intramolecular contrast for molecules adsorbed on semiconductor surfaces, leading to a much broader applicability for submolecular imaging protocols

    Automated extraction of single H atoms with STM: tip state dependency

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    The atomistic structure of the tip apex plays a crucial role in performing reliable atomic-scale surface and adsorbate manipulation using scanning probe techniques. We have developed an automated extraction routine for controlled removal of single hydrogen atoms from the H:Si(100) surface. The set of atomic extraction protocols detect a variety of desorption events during scanning tunneling microscope (STM)-induced modification of the hydrogen-passivated surface. The influence of the tip state on the probability for hydrogen removal was examined by comparing the desorption efficiency for various classifications of STM topographs (rows, dimers, atoms, etc). We find that dimer-row-resolving tip apices extract hydrogen atoms most readily and reliably (and with least spurious desorption), while tip states which provide atomic resolution counter-intuitively have a lower probability for single H atom removal

    Smart and Sustainable Offices (SSO): Presentación de un enfoque holístico para implementar la próxima generación de oficinas

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    The Smart Sustainable Offices project (SSO) is a product of years of research with large sets of data collected from more than 30 office buildings in Switzerland, Sweden, and Spain. Based on scientific evidence, the concept of SSO, initially conceived as a research plan to address the interdependencies between office users and their working environment in a European context, is now used as a qualitative and quantitative mixed method approach for office diagnosis and ideation. At the current stage, the SSO methodology aims to implement a new paradigm of user-oriented, lower carbon footprint and resilient office design solutions. The main strategy is articulated around the “office DNA” of every organisation, decoded as a compound of work patterns, operational and individual needs, and their potential to define design criteria. The practical application of SSO and its tentative findings exemplified through three pilot test office-demonstrators are described in this paper.El proyecto Smart Sustainable Offices (SSO) es un producto de años de investigación y cientos de miles de datos recogidos en más de 30 edificios de oficinas de Suiza, Suecia y España. Inicialmente concebido para investigar las interdependencias entre usuarios de oficinas y su entorno de trabajo en un contexto europeo, ha terminado convertido en un modelo mixto cualitativo y cuantitativo para el diagnóstico e ideación de oficinas, apoyado en evidencias científicas. Actualmente, la metodología SSO pretende implementar un nuevo paradigma de oficinas orientadas al usuario, con menor huella ambiental y espacios resilientes. La estrategia principal se articula alrededor del «ADN de la oficina» de cada organización, descodificado como un compuesto de patrones de trabajo, necesidades operativas e individuales, junto a su potencial para definir criterios de diseño. La práctica de SSO y los resultados provisionales de estudios piloto en tres oficinas demostrativas son descritos en este artículo

    Sclerosing Mesenteritis

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    Background: A 55-year-old Caucasian man presented with weight loss, cramping abdominal pains, an increasing abdominal circumference and diarrhea. Physical examination showed no abnormalities besides a puffy abdomen. His past medical history included a recent subcutaneous swelling in the neck, histologically compatible to a benign solitary fibrous tumor. All blood results were within normal limits. Abdominal ultrasonography showed a tumor with diameter of 6.7 cm, probably originating from the pancreas, with ascites and retroperitoneal lymphadenopathy. This was followed by a CT scan. CT scan of the abdomen was repeated following therapy

    On the exchange of intersection and supremum of sigma-fields in filtering theory

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    We construct a stationary Markov process with trivial tail sigma-field and a nondegenerate observation process such that the corresponding nonlinear filtering process is not uniquely ergodic. This settles in the negative a conjecture of the author in the ergodic theory of nonlinear filters arising from an erroneous proof in the classic paper of H. Kunita (1971), wherein an exchange of intersection and supremum of sigma-fields is taken for granted.Comment: 20 page
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