1,418 research outputs found

    Ground states in the Many Interacting Worlds approach

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    Recently the Many-Interacting-Worlds (MIW) approach to a quantum theory without wave functions was proposed. This approach leads quite naturally to numerical integrators of the Schr\"odinger equation. It has been suggested that such integrators may feature advantages over fixed-grid methods for higher numbers of degrees of freedom. However, as yet, little is known about concrete MIW models for more than one spatial dimension and/or more than one particle. In this work we develop the MIW approach further to treat arbitrary degrees of freedom, and provide a systematic study of a corresponding numerical implementation for computing one-particle ground and excited states in one dimension, and ground states in two spatial dimensions. With this step towards the treatment of higher degrees of freedom we hope to stimulate their further study.Comment: 16 pages, 8 figure

    Pulmonary hypertension is a manifestation of congestive heart failure and left ventricular diastolic dysfunction in octogenarians with severe aortic stenosis

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    Previous studies have suggested that pulmonary hypertension (PH) in severe aortic stenosis (AS) is a risk factor for operative mortality with aortic valve replacement (AVR). Conversely, others have shown that patients with AS and PH extract a large symptomatic and survival benefit from AVR compared with those patients not treated surgically. We sought to evaluate the prevalence, severity, and mechanism of PH in an elderly patient cohort with severe AS. We prospectively evaluated 41 patients aged ≥80 years with severe AS. All patients underwent cardiac catheterization and transthoracic echocardiography within 24 hours. We found that PH was common in this cohort: 32 patients (78%) had PH; however, the predominant mechanism of PH was left heart congestion. Patients with PH had nearly double the pulmonary artery wedge pressure of patients without PH (23 vs. 13 mmHg; P ≤ 0.001). In patients with PH compared with those without, pulmonary vascular resistance was higher yet still under 3 Wood units (WU; 2.9 vs. 1.5 WU; P = 0.001), and the transpulmonary gradient (11 vs. 7 mmHg; P = 0.01) and diastolic pulmonary gradient (DPG; 3.0 vs. 2.7 mmHg; P = 0.74) were in normal range. Left ventricular diastolic abnormalities were more common in patients with severe AS and PH. Right ventricular (RV) dysfunction was common (13/41 patients, 32%), but the PH and non-PH groups had similar tricuspid annular plane systolic excursion (2.0 vs. 2.3 cm; P = 0.15). Only 2 subjects had both RV dysfunction and an elevated DPG. In conclusion, PH is common in elderly patients with severe AS. This occurs largely due to left heart congestion, with a relative absence of pulmonary vascular disease and RV dysfunction, and as such, PH may serve as a heart failure equivalent in these patients

    Snare-Assisted Valve Positioning of Self-Expanding Valves for Transcatheter Aortic Valve Replacement

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    We describe 4 cases in which technical challenges were anticipated in delivering a self-expanding TAVR valve due to challenging aortic anatomy or a previous placed surgical aortic valve. An upfront snare strategy is described which facilitates valve centralization and atraumatic valve delivery. (Level of Difficulty: Advanced.

    Mechanisms and outcome of severe mitral regulation after inoue balloon valvuloplasty

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    AbstractObjectives. The purpose of this study was to assess the incidence, mechanism and outcome of severe mitral regurgitation after treatment of mitral stenosis with percutaneous mitral valvuloplasty using the Inoue balloon.Background. Severe mitral regurgitation occurs in up to 15% of percutaneous balloon valvuloplasty procedures for acquired mitral stenosis. The incidence and mechanism of production of mitral regurgitation with the recently introduced single-ballon lnone technique have not been characterized.Methods. We examined the incidence, mechanism, predictors and outcome of severe mitral regurgitation after Inoue balloon valvuloplasty in 280 patients in the North American multicenter registry. Twenty-one patients who developed either clinically significant or angiographically severe regurgitation were identified, and their echocardiograms were reviewed to determine the mechanism of regurgitation. These patients were then compared with the remaining patients without severe regurgitation to identify predictors of this outcome.Results. The incidence of severe regurgitation in this study was 7.5%, and the mean grade of angiographic regurgitation in these patients increased from 0.9 ± 1.0 to 2.8 ± 0.7 (p < 0.05). The most common cause of regurgitation (43%) was rupture of clhordae tendineae to the anterior or posterior mitral leaflet. Tearing of a leaflet (usually the posterior one) occurred in 30% of patients; and no recognizable structural abnormality, with wide splitting of the commissures and a central regurgitant jet, was present in five patients (26%). All patients with definite posterior leaflet tears had heavily calcified leaflet. Patients who developed severe regurgitation had fewer balloon inflations and a higher grade of preexisting mitral regurgitation but were otherwish similar to the remaining patients without severe regurgitation. During 6-month follow-up, 71% of the patients with severe regurgitation were treated surgically; the grade of regurgitation decreased in four patients (19%), and five (24%) not required mitral valve replacement during 18 ± 5 month of follow-up.Conclusions. Severe mitral regurgitation is a relatively infrequent complication of Inoue balloon valvutoplasty and results from disruption of the valve integrity, chordal rapture and leaflet tearing. Careful balloon positioning may help avoid chordal rapture, and heavily calcified posterior lesflets may be at greater risk of tearing. Most patients who develop severe regurgitation will require nonemergency mitral valve replacement

    Percutaneous Closure of an Aortic Pseudoaneurysm Due to Saphenous Vein Graft Dehiscence With an Amplatzer Vascular Plug

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    Tàpies Puig, Antoni; Garcés, Jordi; Sòria, EnricPla general de l'entrada a l'espai de reflexió on s'aprecia el fons un díptic de 3 per 5 metres amb la silueta campana

    A sound-sensitive source of alpha oscillations in human non-primary auditory cortex

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    The functional organization of human auditory cortex can be probed by characterizing responses to various classes of sound at different anatomical locations. Along with histological studies this approach has revealed a primary field in posteromedial Heschl's gyrus (HG) with pronounced induced high-frequency (70-150 Hz) activity and short-latency responses that phase-lock to rapid transient sounds. Low-frequency neural oscillations are also relevant to stimulus processing and information flow, however their distribution within auditory cortex has not been established. Alpha activity (7-14 Hz) in particular has been associated with processes that may differentially engage earlier versus later levels of the cortical hierarchy, including functional inhibition and the communication of sensory predictions. These theories derive largely from the study of occipitoparietal sources readily detectable in scalp electroencephalography. To characterize the anatomical basis and functional significance of less accessible temporal-lobe alpha activity we analyzed responses to sentences in seven human adults (four female) with epilepsy who had been implanted with electrodes in superior temporal cortex. In contrast to primary cortex in posteromedial HG, a non-primary field in anterolateral HG was characterized by high spontaneous alpha activity that was strongly suppressed during auditory stimulation. Alpha-power suppression decreased with distance from anterolateral HG throughout superior temporal cortex, and was more pronounced for clear compared to degraded speech. This suppression could not be accounted for solely by a change in the slope of the power spectrum. The differential manifestation and stimulus-sensitivity of alpha oscillations across auditory fields should be accounted for in theories of their generation and function.SIGNIFICANCE STATEMENTTo understand how auditory cortex is organized in support of perception, we recorded from patients implanted with electrodes for clinical reasons. This allowed measurement of activity in brain regions at different levels of sensory processing. Oscillations in the alpha range (7-14 Hz) have been associated with functions including sensory prediction and inhibition of regions handling irrelevant information, but their distribution within auditory cortex is not known. A key finding was that these oscillations dominated in one particular non-primary field, anterolateral Heschl's gyrus, and were suppressed when subjects listened to sentences. These results build on our knowledge of the functional organization of auditory cortex and provide anatomical constraints on theories of the generation and function of alpha oscillations

    Nurse-Midwives’ Knowledge and Promotion of Lactational Amenorrhea and Other Natural Family-Planning Methods for Child Spacing

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    The purpose of this study was to describe and assess certified nurse-midwives’ (CNMs) knowledge and promotion of two modalities for child spacing, natural family-planning (NFP) and the lactational amenorrhea method (LAM). One thousand two hundred CNMs were randomly selected from a national membership list and mailed a 24-item questionnaire on NFP and LAM. Of the 514 respondents (42.8% return rate), 450 (87.5%) were currently practicing as CNMs. Respondents had an average age of 46 years, with an average of 10 years of practice. CNMs ranked NFP as the ninth most used and the eighth most effective family-planning method in their practice, with an average perceived method-effectiveness of 88% and use-effectiveness of 70%. Although most respondents felt somewhat prepared during their education program to provide NFP, only 22% would offer NFP as a family-planning option for child spacing

    A Sound-Sensitive Source of Alpha Oscillations in Human Non-Primary Auditory Cortex

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    Copyright © 2019 Billig, Herrmann et al. The functional organization of human auditory cortex can be probed by characterizing responses to various classes of sound at different anatomical locations. Along with histological studies this approach has revealed a primary field in posteromedial Heschl\u27s gyrus (HG) with pronounced induced high-frequency (70-150 Hz) activity and short-latency responses that phase-lock to rapid transient sounds. Low-frequency neural oscillations are also relevant to stimulus processing and information flow, however, their distribution within auditory cortex has not been established. Alpha activity (7-14 Hz) in particular has been associated with processes that may differentially engage earlier versus later levels of the cortical hierarchy, including functional inhibition and the communication of sensory predictions. These theories derive largely from the study of occipitoparietal sources readily detectable in scalp electroencephalography. To characterize the anatomical basis and functional significance of less accessible temporal-lobe alpha activity we analyzed responses to sentences in seven human adults (4 female) with epilepsy who had been implanted with electrodes in superior temporal cortex. In contrast to primary cortex in posteromedial HG, a non-primary field in anterolateral HG was characterized by high spontaneous alpha activity that was strongly suppressed during auditory stimulation. Alpha-power suppression decreased with distance from anterolateral HG throughout superior temporal cortex, and was more pronounced for clear compared to degraded speech. This suppression could not be accounted for solely by a change in the slope of the power spectrum. The differential manifestation and stimulus-sensitivity of alpha oscillations across auditory fields should be accounted for in theories of their generation and function.SIGNIFICANCE STATEMENT To understand how auditory cortex is organized in support of perception, we recorded from patients implanted with electrodes for clinical reasons. This allowed measurement of activity in brain regions at different levels of sensory processing. Oscillations in the alpha range (7-14 Hz) have been associated with functions including sensory prediction and inhibition of regions handling irrelevant information, but their distribution within auditory cortex is not known. A key finding was that these oscillations dominated in one particular non-primary field, anterolateral Heschl\u27s gyrus, and were suppressed when subjects listened to sentences. These results build on our knowledge of the functional organization of auditory cortex and provide anatomical constraints on theories of the generation and function of alpha oscillations

    Convergence calls: multimedia storytelling at British news websites

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    This article uses qualitative interviews with senior editors and managers from a selection of the UK's national online news providers to describe and analyse their current experimentation with multimedia and video storytelling. The results show that, in a period of declining newspaper readership and TV news viewing, editors are keen to embrace new technologies, which are seen as being part of the future of news. At the same time, text is still reported to be the cornerstone for news websites, leading to changes in the grammar and function of news video when used online. The economic rationale for convergence is examined and the article investigates the partnerships sites have entered into in order to be able to serve their audience with video content. In-house video is complementing syndicated content, and the authors examine the resulting developments in newsroom training and recruitment practices. The article provides journalism and interactive media scholars with case studies on the changes taking place in newsrooms as a result of the shift towards multimedia, multiplatform news consumption
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