11,755 research outputs found

    Using a laser aureole to invert lidar return

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    An aureole generated by a laser beam was studied. The strength of the signal redirected towards a sensor high above the surface by a combination of one scattering event in the marine boundary layer (mbl) and one single reflection event from the ocean surface was estimated. A model of mbl aerosol size distributions was used to estimate Mie scattering for a wide range of meteorolocial conditions. The sea surface reflection was determined from a Gaussian model of the wave slopes. These laser aureoles which were estimated over the wide range of conditions and were normalized by the reflected laser light were found to be highly correlated with the optical depth of the boundary layer. By estimating optical depth from the aureole, the Bernoulli-Riccati inversion of lidar return could be constrained and the inversion accuracy improved. A Monte Carlo program was developed to study the laser aureole generated by up to 8 orders of reflection and scattering. The aureole was generated by a narrow, 10 nsec laser pulse at 1.06 microns and measured by a receiver 10 km above the ocean surface. The original theoretical computation compared well with the Monte Carlo method. When multiple scattereffects were included, the normalized aureole was still highly correlated with the mbl optical depth over the range of conditions

    Pregnancy-associated breast cancer - Special features in diagnosis and treatment

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    For obvious psychological reasons it is difficult to associate pregnancy - a life-giving period of our existence with life-threatening malignancies. Symptoms pointing to malignancy are often ignored by both patients and physicians, and this, together with the greater difficulty of diagnostic imaging, probably results in the proven delay in the detection of breast cancers during pregnancy. The diagnosis and treatment of breast cancer are becoming more and more important, as the fulfillment of the desire to have children is increasingly postponed until a later age associated with a higher risk of carcinoma, and improved cure rates of solid tumors no longer exclude subsequent pregnancies. The following article summarizes the special features of the diagnosis and primary therapy of pregnancy-associated breast cancer with particular consideration of cytostatic therapy

    The exploration of eastern Mediterranean deep hypersaline anoxic basins with MODUS: a significant example of technology spin-off from the Geostar Program

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    A significant example of technological spin-off from the GEOSTAR project is represented by the special-purpose instrumented module, based on the deep-sea ROV MODUS, which was developed in the framework of the EU-sponsored project BIODEEP. The goal to be achieved has been defined as the exploration, through real-time video images, measurements and accurate video-guided sampling, of the deep hypersaline anoxic basins of the eastern Mediterranean Sea at water depths well exceeding 3000 meters. Due to their peculiar characteristics, these basins are one of the most extreme environments on Earth and represent a site of utmost interest for their geochemical and microbial resources. The paper presents the strategies and the main results achieved during the two cruises carried out within the BIODEEP project

    Pricing Options in Incomplete Equity Markets via the Instantaneous Sharpe Ratio

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    We use a continuous version of the standard deviation premium principle for pricing in incomplete equity markets by assuming that the investor issuing an unhedgeable derivative security requires compensation for this risk in the form of a pre-specified instantaneous Sharpe ratio. First, we apply our method to price options on non-traded assets for which there is a traded asset that is correlated to the non-traded asset. Our main contribution to this particular problem is to show that our seller/buyer prices are the upper/lower good deal bounds of Cochrane and Sa\'{a}-Requejo (2000) and of Bj\"{o}rk and Slinko (2006) and to determine the analytical properties of these prices. Second, we apply our method to price options in the presence of stochastic volatility. Our main contribution to this problem is to show that the instantaneous Sharpe ratio, an integral ingredient in our methodology, is the negative of the market price of volatility risk, as defined in Fouque, Papanicolaou, and Sircar (2000).Comment: Keywords: Pricing derivative securities, incomplete markets, Sharpe ratio, correlated assets, stochastic volatility, non-linear partial differential equations, good deal bound

    Van der Waals forces in density functional theory: perturbational long-range electron interaction corrections

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    Long-range exchange and correlation effects, responsible for the failure of currently used approximate density functionals in describing van der Waals forces, are taken into account explicitly after a separation of the electron-electron interaction in the Hamiltonian into short- and long-range components. We propose a "range-separated hybrid" functional based on a local density approximation for the short-range exchange-correlation energy, combined with a long-range exact exchange energy. Long-range correlation effects are added by a second-order perturbational treatment. The resulting scheme is general and is particularly well-adapted to describe van der Waals complexes, like rare gas dimers.Comment: 8 pages, 1 figure, submitted to Phys. Rev.

    Impact of Dosing Intervals on Activity of Gentamicin and Ticarcillin Against Pseudomonas aeruginosa in Granulocytopenic Mice

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    The influence of dosing intervals on the activity of gentamicin and ticarcillin against Pseudomonas aeruginosa was studied in vivo. Granulocytopenic mice infected with P. aeruginosa in the thigh muscle were treated with l-hr or 3-hr injections of gentamicin, ticarcillin, or gentamicin-ticarcillin. Plasma pharmacokinetics of the drugs were correlated with antibacterial activity. Gentamicin injected every 1 hr tended to be less active than gentamicin injected at longer intervals. In contrast, ticarcillin given every 1 hr was significantly more efficacious than equivalent total doses injected every 3 hr. The dosing schedule of gentamicin-ticarcillin was again important for ticarcillin but did not appreciably affect the antibacterial activity of gentamicin. Thus, antimicrobial chemotherapy of P. aeruginosa infections in the granulocytopenic host might be improved by administering ticarcillin rather than gentamicin as a constant infusio

    Spelling in adolescents with dyslexia: errors and modes of assessment

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    In this study we focused on the spelling of high-functioning students with dyslexia. We made a detailed classification of the errors in a word and sentence dictation task made by 100 students with dyslexia and 100 matched control students. All participants were in the first year of their bachelor’s studies and had Dutch as mother tongue. Three main error categories were distinguished: phonological, orthographic, and grammatical errors (on the basis of morphology and language-specific spelling rules). The results indicated that higher-education students with dyslexia made on average twice as many spelling errors as the controls, with effect sizes of d ≥ 2. When the errors were classified as phonological, orthographic, or grammatical, we found a slight dominance of phonological errors in students with dyslexia. Sentence dictation did not provide more information than word dictation in the correct classification of students with and without dyslexia
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