245 research outputs found

    INTRODUCTION TO ELECTRONIC ANALOGUE COMPUTING

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    The design, operation, applications, limitations, and programming of an electronic analog computer are described. (C.J.G.

    Relativistic Effects in the Scalar Meson Dynamics

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    A separable potential formalism is used to describe the ππ\pi\pi and KK‾K\overline{K} interactions in the scalar-isoscalar states in the energy range from the ππ\pi\pi threshold up to 1.4 GeV. Introduction of relativistic propagators into a system of Lippmann-Schwinger equations leads to a very good description of the data (χ2=0.93\chi^{2}=0.93 per one degree of freedom). Three poles are found in this energy region: fo(500) (M=506±10M=506\pm 10 MeV, Γ=494±5\Gamma=494\pm 5 MeV), fo(975) (M=973±2M=973\pm 2 MeV, Γ=29±2\Gamma=29\pm 2 MeV) and fo(1400) (M=1430±5M=1430\pm 5 MeV, Γ=145±25\Gamma=145\pm 25 MeV). The fo(975) state can be interpreted as a KK‾K\overline{K} bound state. The fo(500) state may be associated with the often postulated very broad scalar resonance under the KK‾K\overline{K} threshold (sometimes called σ\sigma or ϵ\epsilon meson). The scattering lengths in the ππ\pi\pi and KK‾K\overline{K} channels have also been obtained. The relativistic approach provides qualitatively new results (e.g. the appearance of the fo(500)) in comparison with previously used nonrelativistic approach.Comment: 30 pages in LaTeX + 5 figures available on request. Preprint Orsay No IPNO/TH 93-3

    LaAlO3 stoichiometry found key to electron liquid formation at LaAlO3/SrTiO3 interfaces

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    Emergent phenomena, including superconductivity and magnetism, found in the two-dimensional electron liquid (2-DEL) at the interface between the insulators LaAlO3 and SrTiO3 distinguish this rich system from conventional two-dimensional electron gases at compound semiconductor interfaces. The origin of this 2-DEL, however, is highly debated with focus on the role of defects in the SrTiO3 while the LaAlO3 has been assumed perfect. Our experiments and first principles calculations show that the cation stoichiometry of the nominal LaAlO3 layer is key to 2-DEL formation: only Al-rich LaAlO3 results in a 2-DEL. While extrinsic defects including oxygen deficiency are known to render LaAlO3/SrTiO3 samples conducting, our results show that in the absence of such extrinsic defects, an interface 2-DEL can form. Its origin is consistent with an intrinsic electronic reconstruction occurring to counteract a polarization catastrophe. This work provides a roadmap for identifying other interfaces where emergent behaviors await discovery

    Wet Adhesion and Adhesive Locomotion of Snails on Anti-Adhesive Non-Wetting Surfaces

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    Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted), texture (smooth, rough or granular) or wetting property (hydrophilic or hydrophobic) via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces

    Feed-Forward Microprocessing and Splicing Activities at a MicroRNA–Containing Intron

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    The majority of mammalian microRNA (miRNA) genes reside within introns of protein-encoding and non-coding genes, yet the mechanisms coordinating primary transcript processing into both mature miRNA and spliced mRNA are poorly understood. Analysis of melanoma invasion suppressor miR-211 expressed from intron 6 of melastatin revealed that microprocessing of miR-211 promotes splicing of the exon 6–exon 7 junction of melastatin by a mechanism requiring the RNase III activity of Drosha. Additionally, mutations in the 5′ splice site (5′SS), but not in the 3′SS, branch point, or polypyrimidine tract of intron 6 reduced miR-211 biogenesis and Drosha recruitment to intron 6, indicating that 5′SS recognition by the spliceosome promotes microprocessing of miR-211. Globally, knockdown of U1 splicing factors reduced intronic miRNA expression. Our data demonstrate novel mutually-cooperative microprocessing and splicing activities at an intronic miRNA locus and suggest that the initiation of spliceosome assembly may promote microprocessing of intronic miRNAs

    Normal tissue toxicity after small field hypofractionated stereotactic body radiation

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    Stereotactic body radiation (SBRT) is an emerging tool in radiation oncology in which the targeting accuracy is improved via the detection and processing of a three-dimensional coordinate system that is aligned to the target. With improved targeting accuracy, SBRT allows for the minimization of normal tissue volume exposed to high radiation dose as well as the escalation of fractional dose delivery. The goal of SBRT is to minimize toxicity while maximizing tumor control. This review will discuss the basic principles of SBRT, the radiobiology of hypofractionated radiation and the outcome from published clinical trials of SBRT, with a focus on late toxicity after SBRT. While clinical data has shown SBRT to be safe in most circumstances, more data is needed to refine the ideal dose-volume metrics

    Chromophobe renal cell cancer - review of the literature and potential methods of treating metastatic disease

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    Chromophobe renal cell carcinoma (ChRCC) is a subtype of renal cell carcinoma (RCC). ChRCC is diagnosed mainly in 6th decade of life. An incidence of ChRCC is similar in both men and woman. Eighty six percent of ChRCCs cases are diagnosed in stage 1 or 2. Prognosis of ChRCC is better than in other types of RCC. Five- and 10-year disease free survival (DFS) for ChRCC was 83.9% and 77.9%, respectively. Expression of immunohistological markers: cytokeratins (CK), vimentin, epithelial membrane antigen (EMA), CD10 could be potentially helpful in diagnosis of different subtypes of RCC. From all conventional RCC, CD 117 was detected (overexpression) in membrane of cells ChRCC

    Vinorelbine plus trastuzumab combination as first-line therapy for HER 2-positive metastatic breast cancer patients: an international phase II trial

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    The aim of this international phase II trial was to determine the efficacy and safety profile of weekly vinorelbine plus trastuzumab as first-line chemotherapy for women with HER 2-overexpressing metastatic breast cancer. Sixty-nine patients with tumours overexpressing HER 2 received vinorelbine: 30 mg m−2 week−1 and trastuzumab: 4 mg kg−1 on day 1 as a loading dose followed by 2 mg kg−1 week−1 starting on day 8. Sixty-two patients were evaluable for response and 69 patients were evaluable for toxicity. The overall response rate was 62.9%. The median time to response was 8.4 weeks, the median duration of response was 17.5 months, the median progression-free survival was 9.9 months (95% CI, 5.6–12.1) and the one-year progression-free survival was 39.1%. The median survival for all patients was 23.7 months (95% CI, 18.4–32.6). This regimen was safe: grade 3–4 neutropenia were observed over 17.7% of courses in 83.8% of patients, with only two episodes of febrile neutropenia (0.1%) in two patients (2.9%). Only one patient discontinued treatment due to grade 3 symptomatic cardiac dysfunction that resolved with therapy. Vinorelbine plus trastuzumab is one of the most active treatment regimens for patients with HER 2-positive metastatic breast cancer and demonstrates a very favourable safety profile allowing prolonged treatment with long-term survival. This study has been presented in part at the following conferences: The San Antonio Breast Cancer Symposium, San Antonio, TX, USA, 2003; The American Society of Clinical Oncology, Orlando, FL, USA, 2005
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