363 research outputs found

    X-Ray Computed Tomography: Semiautomated Volumetric Analysis of Late-Stage Lung Tumors as a Basis for Response Assessments

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    Background. This study presents a semiautomated approach for volumetric analysis of lung tumors and evaluates the feasibility of using volumes as an alternative to line lengths as a basis for response evaluation criteria in solid tumors (RECIST). The overall goal for the implementation was to accurately, precisely, and efficiently enable the analyses of lesions in the lung under the guidance of an operator. Methods. An anthropomorphic phantom with embedded model masses and 71 time points in 10 clinical cases with advanced lung cancer was analyzed using a semi-automated workflow. The implementation was done using the Cognition Network Technology. Results. Analysis of the phantom showed an average accuracy of 97%. The analyses of the clinical cases showed both intra- and interreader variabilities of approximately 5% on average with an upper 95% confidence interval of 14% and 19%, respectively. Compared to line lengths, the use of volumes clearly shows enhanced sensitivity with respect to determining response to therapy. Conclusions. It is feasible to perform volumetric analysis efficiently with high accuracy and low variability, even in patients with late-stage cancer who have complex lesions

    Palaeoenvironmental significance of middle Oxfordian deep marine deposits from La Manga Formation, Neuquén Basin, Argentina

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    The Callovian-Oxfordian of the Neuquén Basin (Argentina) is characterized by an extensive marine carbonate system (La Manga Formation) with a predominance of shallow and middle ramp deposits, although locally in tectonically controlled settings, deeper deposits also formed. These middle Oxfordian deeper deposits consist of mudstone-wackestone carbonates alternating with black shales and show marked centimetre-scale rhythmicity, probably controlled by the Earth’s orbit parameters, mainly precession and eccentricity. The present study was designed to examine these deposits in terms of their sedimentology, geochemistry, and small-scale stratigraphy in Arroyo Los Blancos, southern Mendoza Province, where they are exceptionally well exposed and preserved. Results indicate that the sediments were deposited in an anoxic to dysoxic, relatively deep, sea-floor environment as revealed by the presence of: a) organic-rich shales, b) undisrupted lamination in most facies, c) pyrite framboids, and d) absence or scarcity of trace fossils and benthic fauna. Thin beds of graded wackestone-packstone and accumulations of thin shells of Bositra bivalves indicate sporadic reworking of the sea floor by weak currents. Organic petrology, Rock-Eval pyrolysis and thermal maturity indicators were used to characterize TOC and different types of organic matter. Low pyrolysis S yields along with low hydrogen indices suggest poor kerogen convertibility. Vitrinite reflectance (%Ro) ranged from 2.39 to 2.97 with an average of 2.70. The thermal alteration index (TAI) was 4+(5), indicating overmaturity. A tectono-sedimentary model is proposed for these deposits. According to this model, the relatively deep, organic-matter rich facies of La Manga Formation would have been deposited in the deepest zones of topographic lows controlled by tilting and differential subsidence of tectonic blocks bounded by normal faults.These faults were probably inherited from previous extensional tectonics of Late Triassic - Early Jurassic age.Facultad de Ciencias Naturales y Muse

    Palaeoenvironmental significance of middle Oxfordian deep marine deposits from La Manga Formation, Neuquén Basin, Argentina

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    [EN] The Callovian-Oxfordian of the Neuquén Basin (Argentina) is characterized by an extensive marine carbonate system (La Manga Formation) with a predominance of shallow and middle ramp deposits, although locally in tectonically controlled settings, deeper deposits also formed. These middle Oxfordian deeper deposits consist of mudstone-wackestone carbonates alternating with black shales and show marked centimetre-scale rhythmicity, probably controlled by the Earth’s orbit parameters, mainly precession and eccentricity. The present study was designed to examine these deposits in terms of their sedimentology, geochemistry, and small-scale stratigraphy in Arroyo Los Blancos, southern Mendoza Province, where they are exceptionally well exposed and preserved. Results indicate that the sediments were deposited in an anoxic to dysoxic, relatively deep, sea-floor environment as revealed by the presence of: a) organic-rich shales, b) undisrupted lamination in most facies, c) pyrite framboids, and d) absence or scarcity of trace fossils and benthic fauna. Thin beds of graded wackestone-packstone and accumulations of thin shells of Bositra bivalves indicate sporadic reworking of the sea floor by weak currents. Organic petrology, Rock-Eval pyrolysis and thermal maturity indicators were used to characterize TOC and different types of organic matter. Low pyrolysis S yields along with low hydrogen indices suggest poor kerogen convertibility. Vitrinite reflectance (%Ro) ranged from 2.39 to 2.97 with an average of 2.70. The thermal alteration index (TAI) was 4+(5), indicating overmaturity. A tectono-sedimentary model is proposed for these deposits. According to this model, the relatively deep, organic-matter rich facies of La Manga Formation would have been deposited in the deepest zones of topographic lows controlled by tilting and differential subsidence of tectonic blocks bounded by normal faults.These faults were probably inherited from previous extensional tectonics of Late Triassic - Early Jurassic age.[ES] El Calloviense-Oxfordiense en el norte de la Cuenca Neuquina (Argentina) estuvo caracterizado por el desarrollo de un amplio sistema de rampa carbonatada (Formación La Manga) en el que predominaron los depósitos de rampa media y somera aunque localmente, y debido a control tectónico, pudieron acumularse depósitos más profundos. Estos depósitos, de edad Oxfordiense medio, están expuestos y preservados excepcionalmente en la zona de Arroyo Los Blancos, al sur de la provincia de Mendoza, y su estudio sedimentológico, geoquímico y estratigráfico representan el objetivo de este trabajo. Consisten en carbonatos (mudstone-wackestone) con acumulaciones de finas conchas de bivalvos de tipo Bositra que indican retrabajamientos esporádicos del sustrato marino debido a corrientes de baja intensidad. Se han caracterizado diferentes tipos de materia orgánica y TOC mediante petrología orgánica, Rock-Eval Pyrolisis e indicadores de madurez térmica. Los bajos valores en el campo del S unido al también bajo índice de H sugieren una baja convertibilidad de Kerógeno. La reflectancia de la vitrinita (%Ro) tiene un rango que oscila entre 2,39 y 2,97, con una media de 2,70, mientras que el índice de alteración térmico (TAI) es de 4+(5) indicando sobremaduración. Se propone también un modelo tectono-sedimentario para estos depósitos. En este modelo, estas facies relativamente profundas y ricas en materia orgánica de la Formación La Manga estarían depositadas en la parte más deprimida de bajos topográficos controlados por una subsidencia diferencial y de pulsos en bloques marcados por fallas normales heredadas probablemente de una tectónica extensional durante el Triásico Superior-Jurásico Inferior.Peer reviewe

    Warming Up Density Functional Theory

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    Density functional theory (DFT) has become the most popular approach to electronic structure across disciplines, especially in material and chemical sciences. Last year, at least 30,000 papers used DFT to make useful predictions or give insight into an enormous diversity of scientific problems, ranging from battery development to solar cell efficiency and far beyond. The success of this field has been driven by usefully accurate approximations based on known exact conditions and careful testing and validation. In the last decade, applications of DFT in a new area, warm dense matter, have exploded. DFT is revolutionizing simulations of warm dense matter including applications in controlled fusion, planetary interiors, and other areas of high energy density physics. Over the past decade or so, molecular dynamics calculations driven by modern density functional theory have played a crucial role in bringing chemical realism to these applications, often (but not always) with excellent agreement with experiment. This chapter summarizes recent work from our group on density functional theory at non-zero temperatures, which we call thermal DFT. We explain the relevance of this work in the context of warm dense matter, and the importance of quantum chemistry to this regime. We illustrate many basic concepts on a simple model system, the asymmetric Hubbard dimer

    Spontaneous formation and stability of small GaP fullerenes

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    We report the spontaneous formation of a GaP fullerene cage in ab-initio Molecular Dynamics simulations starting from a bulk fragment. A systematic study of the geometric and electronic properties of neutral and ionized GaP clusters suggests the stability of hetero-fullerenes formed by a compound with zincblend bulk structure. We find that GaP fullerenes up to 28 atoms have high symmetry, closed electronic shells, large HOMO-LUMO energy gaps and do not dissociate when ionized. We compare our results for GaP with those obtained by other groups for the corresponding BN clusters.Comment: To appear on PRL, 4 pages, 1 figure, Late

    Ab initio Equation of State data for hydrogen, helium, and water and the internal structure of Jupiter

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    The equation of state of hydrogen, helium, and water effects interior structure models of giant planets significantly. We present a new equation of state data table, LM-REOS, generated by large scale quantum molecular dynamics simulations for hydrogen, helium, and water in the warm dense matter regime, i.e.for megabar pressures and temperatures of several thousand Kelvin, and by advanced chemical methods in the complementary regions. The influence of LM-REOS on the structure of Jupiter is investigated and compared with state-of-the-art results within a standard three-layer model consistent with astrophysical observations of Jupiter. Our new Jupiter models predict an important impact of mixing effects of helium in hydrogen with respect to an altered compressibility and immiscibility.Comment: to appear in ApJ in August 2008, 11 figure

    Cold atmospheric pressure plasma for treatment of chronic wounds: drug or medical device?

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    Objective: The use of cold atmospheric pressure plasma (CAPP) as a new therapeutic option to aid the healing of chronic wounds appears promising. Currently, uncertainty exists regarding their classification as medical device or medical drug. Because the classification of CAPP has medical, legal, and economic consequences as well as implications for the level of preclinical and clinical testing, the correct classification is not an academic exercise, but an ethical need. Method: A multidisciplinary team of physicians, surgeons, pharmacists, physicists and lawyers has analysed the physical and technical characteristics as well as legal conditions of the biological action of CAPP. Results: It was concluded that the mode of action of the locally generated CAPP, with its main active components being different radicals, is pharmacological and not physical in nature. Conclusion: Depending on the intended use, CAPP should be classified as a drug, which is generated by use of a medical device directly at the point of therapeutic application

    Carbon clusters near the crossover to fullerene stability

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    The thermodynamic stability of structural isomers of C24\mathrm{C}_{24}, C26\mathrm{C}_{26}, C28\mathrm{C}_{28} and C32\mathrm{C}_{32}, including fullerenes, is studied using density functional and quantum Monte Carlo methods. The energetic ordering of the different isomers depends sensitively on the treatment of electron correlation. Fixed-node diffusion quantum Monte Carlo calculations predict that a C24\mathrm{C}_{24} isomer is the smallest stable graphitic fragment and that the smallest stable fullerenes are the C26\mathrm{C}_{26} and C28\mathrm{C}_{28} clusters with C2v\mathrm{C}_{2v} and Td\mathrm{T}_{d} symmetry, respectively. These results support proposals that a C28\mathrm{C}_{28} solid could be synthesized by cluster deposition.Comment: 4 pages, includes 4 figures. For additional graphics, online paper and related information see http://www.tcm.phy.cam.ac.uk/~prck

    Palaeoenvironmental significance of middle Oxfordian deep marine deposits from La Manga Formation, Neuquén Basin, Argentina

    Get PDF
    The Callovian-Oxfordian of the Neuquén Basin (Argentina) is characterized by an extensive marine carbonate system (La Manga Formation) with a predominance of shallow and middle ramp deposits, although locally in tectonically controlled settings, deeper deposits also formed. These middle Oxfordian deeper deposits consist of mudstone-wackestone carbonates alternating with black shales and show marked centimetre-scale rhythmicity, probably controlled by the Earth’s orbit parameters, mainly precession and eccentricity. The present study was designed to examine these deposits in terms of their sedimentology, geochemistry, and small-scale stratigraphy in Arroyo Los Blancos, southern Mendoza Province, where they are exceptionally well exposed and preserved. Results indicate that the sediments were deposited in an anoxic to dysoxic, relatively deep, sea-floor environment as revealed by the presence of: a) organic-rich shales, b) undisrupted lamination in most facies, c) pyrite framboids, and d) absence or scarcity of trace fossils and benthic fauna. Thin beds of graded wackestone-packstone and accumulations of thin shells of Bositra bivalves indicate sporadic reworking of the sea floor by weak currents. Organic petrology, Rock-Eval pyrolysis and thermal maturity indicators were used to characterize TOC and different types of organic matter. Low pyrolysis S yields along with low hydrogen indices suggest poor kerogen convertibility. Vitrinite reflectance (%Ro) ranged from 2.39 to 2.97 with an average of 2.70. The thermal alteration index (TAI) was 4+(5), indicating overmaturity. A tectono-sedimentary model is proposed for these deposits. According to this model, the relatively deep, organic-matter rich facies of La Manga Formation would have been deposited in the deepest zones of topographic lows controlled by tilting and differential subsidence of tectonic blocks bounded by normal faults.These faults were probably inherited from previous extensional tectonics of Late Triassic - Early Jurassic age.Facultad de Ciencias Naturales y Muse
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