4,394 research outputs found

    Triple resonant four-wavemixing boosts the yield of continuous coherent VUV generation

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    Continuous-wave coherent radiation in the vacuum ultraviolet (VUV)wavelength region at 121 nm will be essential for future laser-cooling of trapped antihydrogen [1]. Cold antihydrogen will enable both tests of the fundamental symmetry between matter and antimatter at unprecedented experimental precision [2] and also experiments in antimatter gravity [3]. Another fascinating application of narrowband continuous laser radiation in the VUV is quantum information processing using single trapped ions in Rydberg-states [4, 5]. Here we describe highly efficient continuous four-wave mixing in the VUV by using three different fundamental wavelengths with a sophisticated choice of detunings to resonances of the nonlinear medium. Up to 6 microwatts of vacuum ultraviolet radiation at 121 nm can be generated which corresponds to an increase of three orders of magnitude in efficiency.Comment: 11 pages, 3 figure

    Advanced Conducting Project

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    Hallelujah (from Mount of Olives ) by Ludwig van Beethoven -- Lo! How a Rose E\u27er Blooming by Hugo Distler -- O Praise the Lord of Heaven by William Billings -- If Ye Love Me, Keep My Commandments by Thomas Tallis -- Cantate Domino by Giovanni Croce -- Ave Verum by Charles Gounod -- Domine Feli Unigenite (from Gloria ) by Antonio Vivaldi -- Bogoroditse Devo by Serge Rachmaninoff -- I\u27ve Been in the Storm So Long by Jeffrey L. Ames -- Ain\u27t That Good News by Moses Hogan -- O Magnum Mysterium by Morten Lauridsen -- Hallelujah Chorus (from The Messiah ) by George Frideric Handel

    Approximation theory for boundary layer suction through individual slits

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    The basic concepts of influencing boundary layers are summarized, especially the prevention of flow detachment and the reduction of frictional resistance. A mathematical analysis of suction through a slit is presented with two parameters, for thickness and for shape of the boundary layer, being introduced to specify the flow's velocity profile behind the slit. An approximation of the shape parameter produces a useful formula, which can be used to determine the most favorable position of the slit. An aerodynamic example is given

    Clinical relevance of circulating tumour cells in the bone marrow of patients with SCCHN

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    Background: Clinical outcome of patients with head and neck squamous cell carcinoma (SCCHN) depends on several risk factors like the presence of locoregional lymph node or distant metastases, stage, localisation and histologic differentiation of the tumour. Circulating tumour cells in the bone marrow indicate a poor prognosis for patients with various kinds of malignoma. The present study examines the clinical relevance of occult tumour cells in patients suffering from SCCHN. Patients and Methods: Bone marrow aspirates of 176 patients suffering from SCCHN were obtained prior to surgery and stained for the presence of disseminated tumour cells. Antibodies for cytokeratin 19 were used for immunohistochemical detection with APAAP on cytospin slides. Within a clinical follow-up protocol over a period of 60 months, the prognostic relevance of several clinicopathological parameters and occult tumour cells was evaluated. Results: Single CK19-expressing tumour cells could be detected in the bone marrow of 30.7% of the patients. There is a significant correlation between occult tumour cells in the bone marrow and relapse. Uni- and multivariate analysis of all clinical data showed the metastases in the locoregional lymph system and detection of disseminated tumour cells in the bone marrow to be statistically highly significant for clinical prognosis. Conclusion: The detection of minimal residual disease underlines the understanding of SCCHN as a systemic disease. Further examination of such cells will lead to a better understanding of the tumour biology, as well as to improvement of diagnostic and therapeutic strategies

    The International Linear Collider beam dumps

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    The ILC beam dumps are a key part of the accelerator design. At Snowmass 2005, the current status of the beam dump designs were reviewed, and the options for the overall dump layout considered. This paper describes the available dump options for the baseline and the alternatives and considers issues for the dumps that require resolution.Comment: Prepared for 2005 International Linear Collider Physics and Detector Workshop and 2nd ILC Accelerator Workshop, Snowmass, Colorado, 14-27 Aug 200

    Continuous Lyman-alpha generation by four-wave mixing in mercury for laser-cooling of antihydrogen

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    Cooling antihydrogen atoms is important for future experiments both to test the fundamental CPT symmetry by high-resolution laser spectroscopy and also to measure the gravitational acceleration of antimatter. Laser-cooling of antihydrogen can be done on the strong 1S-2P transition at the wavelength of Lyman-alpha (121.6nm). A continuous-wave laser at the Lyman-alpha wavelength based on solid-state fundamental lasers is described. By using a two-photon and a near one photon resonance a scan across the whole phasematching curve of the four-wave mixing process is possible. Furthermore the influence of the beam profile of one fundamental beam on the four-wave mixing process is studied.Comment: 4 pages, 4 figure

    Revisiting the Impact of ERP Systems on Business Value: A Triangulation Method

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    The present study will examine the impact of Enterprise Resource Planning (ERP) investment on business value. While there is considerable amount research on the impact of IT investments on business performance, few studies have provided empirical evidence about the business value of ERP investments. Case studies have shown positive impacts of ERP implementations. However, there are many cases where ERP systems have caused serious financial and operational problems. The present study attempts to provide evidence about the impact of ERP investments on business value by comparing the reaction of investors to ERP investment announcements with senior managers’ perceptions (ex ante) about the net benefits of the ERP system after its implementation (ex post), the proposed research in progress will shed some light on the conflicting results

    Precision Measurements of Higgs Couplings: Implications for New Physics Scales

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    The measured properties of the recently discovered Higgs boson are in good agreement with predictions from the Standard Model. However, small deviations in the Higgs couplings may manifest themselves once the currently large uncertainties will be improved as part of the LHC program and at a future Higgs factory. We review typical new physics scenarios that lead to observable modifications of the Higgs interactions. They can be divided into two broad categories: mixing effects as in portal models or extended Higgs sectors, and vertex loop effects from new matter or gauge fields. In each model we relate coupling deviations to their effective new physics scale. It turns out that with percent level precision the Higgs couplings will be sensitive to the multi-TeV regime.Comment: Invited review for Journal of Physics G, 33pp; v2: references added and improved discussion of operator basis in section 2.

    Observation of Spin Flips with a Single Trapped Proton

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    Radio-frequency induced spin transitions of one individual proton are observed for the first time. The spin quantum jumps are detected via the continuous Stern-Gerlach effect, which is used in an experiment with a single proton stored in a cryogenic Penning trap. This is an important milestone towards a direct high-precision measurement of the magnetic moment of the proton and a new test of the matter-antimatter symmetry in the baryon sector

    Capstone Engineering Design Projects For Community Colleges

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    Capstone engineering design courses have been a feature at research universities and four-year schools for many years.  Although such classes are less common at two-year colleges, the experience is equally beneficial for this population of students.  With this in mind, Madison College introduced a project-based Engineering Design course in 2007.  This paper explores Madison College’s experience over the past decade offering this class.  Unique challenges and opportunities for engineering design courses at two-year colleges are discussed.  Our findings include several recommended practices to benefit colleges and universities at any level that are creating new engineering design courses. 
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