598 research outputs found

    Ultrahigh finesse Fabry-Perot superconducting resonator

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    We have built a microwave Fabry-Perot resonator made of diamond-machined copper mirrors coated with superconducting niobium. Its damping time (Tc = 130 ms at 51 GHz and 0.8 K) corresponds to a finesse of 4.6 x 109, the highest ever reached for a Fabry-Perot in any frequency range. This result opens novel perspectives for quantum information, decoherence and non-locality studies

    In search of phylogenetic congruence between molecular and morphological data in bryozoans with extreme adult skeletal heteromorphy

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    peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=tsab20© Crown Copyright 2015. This document is the author's final accepted/submitted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it

    Quantum jumps of light recording the birth and death of a photon in a cavity

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    A microscopic system under continuous observation exhibits at random times sudden jumps between its states. The detection of this essential quantum feature requires a quantum non-demolition (QND) measurement repeated many times during the system evolution. Quantum jumps of trapped massive particles (electrons, ions or molecules) have been observed, which is not the case of the jumps of light quanta. Usual photodetectors absorb light and are thus unable to detect the same photon twice. They must be replaced by a transparent counter 'seeing' photons without destroying them3. Moreover, the light has to be stored over a duration much longer than the QND detection time. We have fulfilled these challenging conditions and observed photon number quantum jumps. Microwave photons are stored in a superconducting cavity for times in the second range. They are repeatedly probed by a stream of non-absorbing atoms. An atom interferometer measures the atomic dipole phase shift induced by the non-resonant cavity field, so that the final atom state reveals directly the presence of a single photon in the cavity. Sequences of hundreds of atoms highly correlated in the same state, are interrupted by sudden state-switchings. These telegraphic signals record, for the first time, the birth, life and death of individual photons. Applying a similar QND procedure to mesoscopic fields with tens of photons opens new perspectives for the exploration of the quantum to classical boundary

    Inter-hemispheric EEG coherence analysis in Parkinson's disease : Assessing brain activity during emotion processing

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    Parkinson’s disease (PD) is not only characterized by its prominent motor symptoms but also associated with disturbances in cognitive and emotional functioning. The objective of the present study was to investigate the influence of emotion processing on inter-hemispheric electroencephalography (EEG) coherence in PD. Multimodal emotional stimuli (happiness, sadness, fear, anger, surprise, and disgust) were presented to 20 PD patients and 30 age-, education level-, and gender-matched healthy controls (HC) while EEG was recorded. Inter-hemispheric coherence was computed from seven homologous EEG electrode pairs (AF3–AF4, F7–F8, F3–F4, FC5–FC6, T7–T8, P7–P8, and O1–O2) for delta, theta, alpha, beta, and gamma frequency bands. In addition, subjective ratings were obtained for a representative of emotional stimuli. Interhemispherically, PD patients showed significantly lower coherence in theta, alpha, beta, and gamma frequency bands than HC during emotion processing. No significant changes were found in the delta frequency band coherence. We also found that PD patients were more impaired in recognizing negative emotions (sadness, fear, anger, and disgust) than relatively positive emotions (happiness and surprise). Behaviorally, PD patients did not show impairment in emotion recognition as measured by subjective ratings. These findings suggest that PD patients may have an impairment of inter-hemispheric functional connectivity (i.e., a decline in cortical connectivity) during emotion processing. This study may increase the awareness of EEG emotional response studies in clinical practice to uncover potential neurophysiologic abnormalities

    The Danish multicentre randomized study of fibrinolytic therapy vs. primary angioplasty in acute myocardial infarction (the DANAMI-2 trial)::outcome after 3 years follow-up.

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      Udgivelsesdato: 2007-Oct-23Background The DANAMI-2 trial showed that in patients with ST-elevation myocardial infarction (STEMI), a strategy of inter-hospital transfer for primary angioplasty was superior to on-site fibrinolysis at 30 days follow-up. This paper reports on the pre-specified long-term composite endpoint at 3 years follow-up in DANAMI-2. Methods and results We randomized 1572 patients with STEMI to primary angioplasty or intravenous alteplase; 1129 patients were enrolled at 24 referral hospitals and 443 patients at 5 angioplasty centres. Ninety-six percent of inter-hospital transfers for angioplasty were completed within 2 h. No patients were lost to follow-up. The composite endpoint (death, clinical re-infarction, or disabling stroke) was reduced by angioplasty when compared with fibrinolysis at 3 years (19.6 vs. 25.2%, P = 0.006). For patients transferred to angioplasty compared with those receiving on-site fibrinolysis, the composite endpoint occurred in 20.1 vs. 26.7% (P = 0.007), death in 13.6 vs. 16.4% (P = 0.18), clinical re-infarction in 8.9 vs. 12.3% (P = 0.05), and disabling stroke in 3.2 vs. 4.7% (P = 0.23). Conclusion The benefit of transfer for primary angioplasty based on the composite endpoint was sustained after 3 years. For patients with characteristics as those in DANAMI-2, primary angioplasty should be the preferred treatment strategy when inter-hospital transfer can be completed within 2 h

    A Taylor Model Based Description of the proof stress of magnesium AZ31 during hot working

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    A series of hot-compression tests and Taylor-model simulations were carried out with the intention of developing a simple expression for the proof stress of magnesium alloy AZ31 during hot working. A crude approximation of wrought textures as a mixture of a single ideal texture component and a random background was employed. The shears carried by each deformation system were calculated using a full-constraint Taylor model for a selection of ideal orientations as well as for random textures. These shears, in combination with the measured proof stresses, were employed to estimate the critical resolved shear stresses for basal slip, prismatic slip, ⟨c+a⟩ second-order pyramidal slip, and { } twinning. The model thus established provides a semianalytical estimation of the proof stress (a one-off Taylor simulation is required) and also indicates whether or not twinning is expected. The approach is valid for temperatures between ∼150 °C and ∼450 °C, depending on the texture, strain rate, and strain path
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