50,836 research outputs found

    Lock acquisition studies for advanced interferometers

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    This document describes some results of time domain simulation for a Fabry-Perot cavity with Advanced LIGO parameters. Future interferometer will employ a high power laser and high finesse cavities. Lock acquisition of arm cavity will be more difficult due to the optical instabilities which are caused by very high power inside the cavity. According to this simulation, the arm cavity should be locked with very low power, and additional hard/software techniques will be needed to establish the first fringe lock. In this paper, possibility of using a new algorithm called 'Guidelock' and a suspension point interferometer are discussed. After lock is acquired, alignment controls must be engaged before increasing the power. This simulation predicts that alignment optical instabilities show up due to a shift of high power beam axis, and they can be stabilized by proper alignment controls

    Is Cabibbo-Kobayasi-Maskawa Matrix Unitary?

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    First, we give summary of the present values of CKM matrix elements. Then, we discuss whether CKM matrix is unitary or not, and how we can find out if it is not unitary.Comment: 8 pages, 1 figur

    Translation-finite sets, and weakly compact derivations from \lp{1}(\Z_+) to its dual

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    We characterize those derivations from the convolution algebra â„“1(Z+)\ell^1({\mathbb Z}_+) to its dual which are weakly compact. In particular, we provide examples which are weakly compact but not compact. The characterization is combinatorial, in terms of "translation-finite" subsets of Z+{\mathbb Z}_+, and we investigate how this notion relates to other notions of "smallness" for infinite subsets of Z+{\mathbb Z}_+. In particular, we show that a set of strictly positive Banach density cannot be translation-finite; the proof has a Ramsey-theoretic flavour.Comment: v1: 14 pages LaTeX (preliminary). v2: 13 pages LaTeX, submitted. Some streamlining, renumbering and minor corrections. v3: appendix removed. v4: Modified appendix reinstated; 14 pages LaTeX. To appear in Bull. London Math. Soc

    Lymphoma caused by intestinal microbiota.

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    The intestinal microbiota and gut immune system must constantly communicate to maintain a balance between tolerance and activation: on the one hand, our immune system should protect us from pathogenic microbes and on the other hand, most of the millions of microbes in and on our body are innocuous symbionts and some can even be beneficial. Since there is such a close interaction between the immune system and the intestinal microbiota, it is not surprising that some lymphomas such as mucosal-associated lymphoid tissue (MALT) lymphoma have been shown to be caused by the presence of certain bacteria. Animal models played an important role in establishing causation and mechanism of bacteria-induced MALT lymphoma. In this review we discuss different ways that animal models have been applied to establish a link between the gut microbiota and lymphoma and how animal models have helped to elucidate mechanisms of microbiota-induced lymphoma. While there are not a plethora of studies demonstrating a connection between microbiota and lymphoma development, we believe that animal models are a system which can be exploited in the future to enhance our understanding of causation and improve prognosis and treatment of lymphoma
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