1,148 research outputs found

    Hegelian Spirits in Sellarsian Bottles

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    Though Wilfrid Sellars portrayed himself as a latter-day Kantian, I argue here that he was at least as much a Hegelian. Several themes Sellars shares with Hegel are investigated: the sociality and normativity of the intentional, categorial change, the rejection of the given, and especially their denial of an unknowable thing-in-itself. They are also united by an emphasis on the unity of things—the belief that things do ‘‘hang together.’’ Hegel’s unity is idealist; Sellars’ is physicalist; the differences are substantial, but so are the resonances

    Empirical Analysis of Aerial Camera Filters for Shoreline Mapping

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    Accurate, up-to-date national shoreline is critical in defining the territorial limits of the Unites States, updating nautical charts, and managing coastal resources. The National Oceanic and Atmospheric Administration (NOAA) delineates the interpreted shoreline photogrammetrically using tide-coordinated stereo photography acquired with black-and-white infrared emulsion. In this paper, we present the results of a two-phased study aimed at quantifying the effect of camera filter selection on the interpreted shoreline when utilizing this method of shoreline mapping

    Is voice therapy an effective treatment for dysphonia? A randomised controlled trial

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    OBJECTIVES: To assess the overall efficacy of voice therapy for dysphonia. DESIGN: Single blind randomised controlled trial. SETTING: Outpatient clinic in a teaching hospital. Participants: 204 outpatients aged 17-87 with a primary symptom of persistent hoarseness for at least two months. INTERVENTIONS: After baseline assessments, patients were randomised to six weeks of either voice therapy or no treatment. Assessments were repeated at six weeks on the 145 (71%) patients who continued to this stage and at 12-14 weeks on the 133 (65%) patients who completed the study. The assessments at the three time points for the 70 patients who completed treatment and the 63 patients in the group given no treatment were compared. MAIN OUTCOME MEASURES: Ratings of laryngeal features, Buffalo voice profile, amplitude and pitch perturbation, voice profile questionnaire, hospital anxiety and depression scale, clinical interview schedule, SF-36. RESULTS: Voice therapy improved voice quality as assessed by rating by patients (P=0.001) and rating by observer (P<0.001). The treatment effects for these two outcomes were 4.1 (95% confidence interval 1.7 to 6.6) points and 0.82 (0.50 to 1.13) points. Amplitude perturbation showed improvement at six weeks (P=0.005) but not on completion of the study. Patients with dysphonia had appreciable psychological distress and lower quality of life than controls, but voice therapy had no significant impact on either of these variables. CONCLUSION: Voice therapy is effective in improving voice quality as assessed by self rated and observer rated methods

    Gradient Echo Quantum Memory for Light using Two-level Atoms

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    We propose a quantum memory for light that is analogous to the NMR gradient echo. Our proposal is ideally perfectly efficient and provides simplifications to current 3-level quantum memory schemes based on controlled inhomogeneous broadening. Our scheme does not require auxiliary light fields. Instead the input optical pulse interacts only with two-level atoms that have linearly increasing Stark shifts. By simply reversing the sign of the atomic Stark shifts, the pulse is retrieved in the forward direction. We present analytical, numerical and experimental results of this scheme. We report experimental efficiencies of up to 15% and suggest simple realizable improvements to significantly increase the efficiency.Comment: 4 pages, 4 figure

    Dynamic decoherence control of a solid-state nuclear quadrupole qubit

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    We report on the application of a dynamic decoherence control pulse sequence on a nuclear quadrupole transition in Pr3+:Y2SiO5Pr^{3+}:Y_2SiO_5 . Process tomography is used to analyse the effect of the pulse sequence. The pulse sequence was found to increase the decoherence time of the transition to over 30 seconds. Although the decoherence time was significantly increased, the population terms were found to rapidly decay on the application of the pulse sequence. The increase of this decay rate is attributed to inhomogeneity in the ensemble. Methods to circumvent this limit are discussed.Comment: 4 pages, 6 figure

    Photon Echoes Produced by Switching Electric Fields

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    We demonstrate photon echoes in Eu3+^{3+}:Y2_{2}SiO5_{5} by controlling the inhomogeneous broadening of the Eu3+^{3+} 7^{7}F0↔5_{0}\leftrightarrow^{5}D0_{0} optical transition. This transition has a linear Stark shift and we induce inhomogeneous broadening by applying an external electric field gradient. After optical excitation, reversing the polarity of the field rephases the ensemble, resulting in a photon echo. This is the first demonstration of such a photon echo and its application as a quantum memory is discussed.Comment: improved introduction, including theoretical outline of the relvant quantum memory proposa

    A Maitland–Japp inspired synthesis of dihydropyran-4-ones and their stereoselective conversion to functionalised tetrahydropyran-4-ones

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    The Maitland–Japp reaction has been extended to the synthesis of highly functionalised dihydropyran-4-ones. These dihydropyran-4-ones can in turn be converted stereoselectively into tetrahydropyran-4-ones with tertiary and quaternary stereocentres via the one-pot addition of hydride or carbon nucleophiles and trapping with carbon electrophiles. The utility of this method is demonstrated by providing access to the functionalised tetrahydropyran units present in a component of the Civet fragrance and the anticancer polyketide lasonolide A

    Quantum storage on subradiant states in an extended atomic ensemble

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    A scheme for coherent manipulation of collective atomic states is developed such that total subradiant states, in which spontaneous emission is suppressed into all directions due to destructive interference between neighbor atoms, can be created in an extended atomic ensemble. The optimal conditions for creation of such states and suitability of them for quantum storage are discussed. It is shown that in order to achieve the maximum signal-to-noise ratio the shape of a light pulse to be stored and reconstructed using a homogeneously broadened absorbtion line of an atomic system should be a time-reversed regular part of the response function of the system. In the limit of high optical density, such pulses allow one to prepare collective subradiant atomic states with near flat spatial distribution of the atomic excitation in the medium.Comment: V2: considerably revised (title, text). V3: minor changes - final version as published in PR
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