7,173 research outputs found

    V. The Semiclassical Foldy-Wouthuysen Transformation and the Derivation of the Bloch Equation for Spin-1/2 Polarised Beams Using Wigner Functions

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    A semiclassical Foldy--Wouthuysen transformation of the Dirac equation is used to obtain the radiationless Bloch equation for the polarisation density.Comment: 7 pages. No figures. Latex. Paper 5 of a set of 5. others are physics/9901038 physics/9901041 physics/9901042 physics/990104

    Spin decoherence in electron storage rings --- more from a simple model

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    This is an addendum to the paper "Some models of spin coherence and decoherence in storage rings" by one of the authors [1] in which spin diffusion in simple electron storage rings is studied. In particular, we illustrate in a compact way, a key implication in the Epilogue of [1], namely that the exact formalism of [1] delivers a rate of depolarisation which can differ from that obtained by the conventional treatments of spin diffusion which rely on the use of the derivative ∂n^/∂η\partial \hat n/\partial\eta [2,3,4]. As a vehicle we consider a ring with a Siberian Snake and electron polarisation in the plane of the ring (Machine II in [1]). For this simple setup with its one-dimensional spin motion, we avoid having to deal directly with the Bloch equation [5,6] for the polarisation density. Our treatment, which is deliberately pedagogical, shows that the use of ∂n^/∂η\partial \hat n/\partial\eta provides a very good approximation to the rate of spin depolarisation in the model considered. But it then shows that the exact rate of depolarisation can be obtained by replacing ∂n^/∂η\partial \hat n/\partial\eta by another derivative as suggested in the Epilogue of [1], while giving a heuristic justification for the new derivative.Comment: 17 page

    Is the View from the Eurotower Purely European? National Divergence and ECB Interest Rate Policy

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    The official view on ECB monetary policy claims that monetary decisions are based solely on average data for the euro zone and that diverging regional developments are disregarded. However, experience from other two tier central banks and theoretical considerations suggest that this official view cannot be accepted without empirical testing. A generalised monetary policy reaction function is developed which allows for an influence of regional divergence. The empirical tests are based on reaction function estimations and a probit model of interest rate decisions for the first years of the euro area. The results offer some first weak support for an impact of regional divergence in ECB decision making. The results further clarify that ignoring a potential national perspective may lead to a serious bias in the estimation of ECB reaction functions. The paper concludes that the correct identification of a possible impact of regional divergence is important for the transparency issue. --ECB,monetary policy,Taylor rule

    Is the View from the Eurotower Purely European? - National Divergence and ECB Interest Rate Policy

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    The official view on ECB monetary policy claims that decisions are based on euro zone data and that diverging regional developments are disregarded. To test empirically whether regional developments have an impact on ECB decisions we develop a generalised monetary policy reaction function which allows for an influence of regional divergence. Reaction function estimations and a probit model of interest rate decisions for the first years of the euro area offer some first weak support for an impact of regional divergence. The results clarify that ignoring a potential national perspective may lead to biased estimates for the ECB reaction function.ECB, monetary policy, Taylor rule

    Computed potential energy surfaces for chemical reactions

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    The work on the NH + NO system which was described in the last progress report was written up and a draft of the manuscript is included in the appendix. The appendix also contains a draft of a manuscript on an Ar + H + H surface. New work which was completed in the last six months includes the following: (1) calculations on the (1)CH2 + H2O, H2 + HCOH, and H2 + H2CO product channels in the CH3 + OH reaction; (2) calculations for the NH2 + O reaction; (3) calculations for the CH3 + O2 reaction; and (4) calculations for CH3O and the two decomposition channels--CH2OH and H + H2CO. Detailed descriptions of this work will be given in manuscripts; however, brief descriptions of the CH3 + OH and CH3 + O2 projects are given

    Re-evaluation of HER2 status in metastatic breast cancer and tumor-marker guided therapy with vinorelbine and trastuzumab

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    Background: HER2 is overexpressed in 20 - 30% of breast cancers. Compared to chemotherapy alone, chemotherapy with trastuzumab improves clinical outcome in patients with HER2- positive metastatic breast cancer ( MBC). In general, HER2 status in a primary lesion predicts the status of metastases, so that biopsy of metastatic lesions appears unnecessary. Case Report: A 39- year old woman was diagnosed with primary breast cancer in November 2000. Using the method and scoring system of the DAKO Hercep Test, the tumor has shown low HER2 expression ( DAKO score 1+). After failure of several chemotherapy regimens for metastatic disease ( liver, skeletal), the patient underwent CT- guided needle biopsy of the liver which showed HER2 positive adenocarcinoma ( DAKO score 3+). In consequence, the patient was treated with vinorelbine ( 30 mg/ m(2) d1,8,15 q4w) and trastuzumab ( 4 mg/ kg loading dose, 2 mg/ kg weekly). During a treatment period of 4 months imaging results as well as tumor marker kinetics indicated an excellent response with sustained decrease of tumor markers. A retrospective analysis of the HER2 shed antigen in metastatic stage revealed excessively increased serum levels and supports HER2 overexpression observed in liver metastasis. The kinetics of the HER2 shed antigen during therapy for metastatic disease were found to be in phase with the kinetics of CEA and CA15- 3. Conclusion: This case report demonstrates that re- evaluation of the HER2 status may be helpful in single patients not sufficiently responding to treatment of metastatic disease. Determination of HER2 overexpression may be facilitated by a determination of the HER2 shed antigen level in peripheral blood

    Space shuttle: Longitudinal and lateral directional stability characteristics of the MDAC high cross range delta wing orbiter

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    Low speed wind tunnel tests on longitudinal and lateral stability of high cross range delta wing space shuttle

    Computed Potential Energy Surfaces for Chemical Reactions

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    A manuscript describing the calculations on the (1)CH2 + H2O, H2 + HCOH, and H2 + H2CO product channels in the CH3 + OH reaction, which were described in the last progress report, has been accepted for publication in J. Chem. Phys., and a copy of the manuscript is included in the appendix. The production of (1)CH2 in this reaction is important in hydrocarbon combustion since (1)CH2 is highly reactive and would be expected to insert into N2, possibly leading to a new source for prompt NO(x) (vide infra). During the last six months new calculations have been carried out for the NH2 + NO system, which is important in the thermal de-NO(x) process

    A New and Unifying Approach to Spin Dynamics and Beam Polarization in Storage Rings

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    With this paper we extend our studies [1] on polarized beams by distilling tools from the theory of principal bundles. Four major theorems are presented, one which ties invariant fields with the notion of normal form, one which allows one to compare different invariant fields, and two that relate the existence of invariant fields to the existence of certain invariant sets and relations between them. We then apply the theory to the dynamics of spin-1/2 and spin-1 particles and their density matrices describing statistically the particle-spin content of bunches. Our approach thus unifies the spin-vector dynamics from the T-BMT equation with the spin-tensor dynamics and other dynamics. This unifying aspect of our approach relates the examples elegantly and uncovers relations between the various underlying dynamical systems in a transparent way
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