5,081 research outputs found

    Evolution of entanglement within classical light states

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    We investigate the evolution of quantum correlations over the lifetime of a multi-photon state. Measurements reveal time-dependent oscillations of the entanglement fidelity for photon pairs created by a single semiconductor quantum dot. The oscillations are attributed to the phase acquired in the intermediate, non-degenerate, exciton-photon state and are consistent with simulations. We conclude that emission of photon pairs by a typical quantum dot with finite polarisation splitting is in fact entangled in a time-evolving state, and not classically correlated as previously regarded

    Decoding the Brain: Neural Representation and the Limits of Multivariate Pattern Analysis in Cognitive Neuroscience

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    Since its introduction, multivariate pattern analysis (MVPA), or “neural decoding”, has transformed the field of cognitive neuroscience. Underlying its influence is a crucial inference, which we call the Decoder’s Dictum: if information can be decoded from patterns of neural activity, then this provides strong evidence about what information those patterns represent. Although the Dictum is a widely held and well-motivated principle in decoding research, it has received scant philosophical attention. We critically evaluate the Dictum, arguing that it is false: decodability is a poor guide for revealing the content of neural representations. However, we also suggest how the Dictum can be improved on, in order to better justify inferences about neural representation using MVPA

    Effective antibiotic conservation by emergency antimicrobial stewardship during a drug shortage

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    We present the first description of an antimicrobial stewardship program (ASP) used to successfully manage a multi-antimicrobial drug shortage. Without resorting to formulary restriction, meropenem utilization decreased by 69% and piperacillin-tazobactam by 73%. During the shortage period, hospital mortality decreased (P=.03), while hospital length of stay remained unchanged.Infect Control Hosp Epidemiol 2017;38:356–359</jats:p

    Improved fidelity of triggered entangled photons from single quantum dots

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    We demonstrate the on-demand emission of polarisation-entangled photon pairs from the biexciton cascade of a single InAs quantum dot embedded in a GaAs/AlAs planar microcavity. Improvements in the sample design blue shifts the wetting layer to reduce the contribution of background light in the measurements. Results presented show that >70% of the detected photon pairs are entangled. The high fidelity of the (|HxxHx>+|VxxVx>)/2^0.5 state that we determine is sufficient to satisfy numerous tests for entanglement. The improved quality of entanglement represents a significant step towards the realisation of a practical quantum dot source compatible with applications in quantum information.Comment: 9 pages. Paper is available free of charge at http://www.iop.org/EJ/abstract/1367-2630/8/2/029/, see also 'A semiconductor source of triggered entangled photon pairs', R. M. Stevenson et al., Nature 439, 179 (2006

    Importance of site of infection and antibiotic selection in the treatment of carbapenem-resistant Pseudomonas aeruginosa sepsis

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    ABSTRACT In a retrospective analysis of 215 patients with carbapenem-resistant Pseudomonas aeruginosa sepsis, we observed a significantly higher risk of mortality associated with respiratory tract infection (risk ratio [RR], 1.20; 95% confidence interval [CI], 1.04 to 1.39; P = 0.010) and lower risk with urinary tract infection (RR, 0.80; 95% CI, 0.71 to 0.90; P = 0.004). Aminoglycoside monotherapy was associated with increased mortality, even after adjusting for confounders (adjusted RR, 1.72; 95% CI, 1.03 to 2.85; P = 0.037), consistent across multiple sites of infection. </jats:p

    Vancomycin-Associated Leukocytoclastic Vasculitis

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    Vancomycin is U.S. Food and Drug Administration (FDA) approved for treatment of serious infections caused by methicillin-resistant Staphylococcus aureus (MRSA) or in individuals who have failed, cannot tolerate, or are allergic to other antibiotics. Very few cases of vancomycin-associated leukocytoclastic vasculitis have been published. We report on a patient who developed pruritus and palpable purpura in both lower extremities after receiving six days of intravenous vancomycin. Skin biopsy revealed leukocytoclastic vasculitis

    Giant Stark effect in the emission of single semiconductor quantum dots

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    We study the quantum-confined Stark effect in single InAs/GaAs quantum dots embedded within a AlGaAs/GaAs/AlGaAs quantum well. By significantly increasing the barrier height we can observe emission from a dot at electric fields of -500 kV/cm, leading to Stark shifts of up to 25 meV. Our results suggest this technique may enable future applications that require self-assembled dots with transitions at the same energy

    Diffuse Intramuscular Lipomatosis of a Lower Limb

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    Patient. A 40-year-old man presented with a swelling of the left thigh which had been increasing in size over 10 months. Surgery confirmed a diagnosis of lipoma. After 6 months, another swelling appeared, this time in the left calf. Ultrasound-guided biopsies revealed that the tissue showed appearances consistent with intramuscular lipoma. No further surgery was performed and the man is to be reviewed regularly, with possible debulking if necessary
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