A model based on clinical parameters to identify myocardial late gadolinium enhancement by magnetic resonance in patients with aortic stenosis: An observational study

Objective With increasing age, the prevalence of aortic stenosis grows exponentially, increasing left heart pressures and potentially leading to myocardial hypertrophy, myocardial fibrosis and adverse outcomes. To identify patients who are at greatest risk, an outpatient model for risk stratification would be of value to better direct patient imaging, frequency of monitoring and expeditious management of aortic stenosis with possible earlier surgical intervention. In this study, a relatively simple model is proposed to identify myocardial fibrosis in patients with a diagnosis of moderate or severe aortic stenosis. Design Patients with moderate to severe aortic stenosis were enrolled into the study; patient characteristics, blood work, medications as well as transthoracic echocardiography and cardiovascular magnetic resonance were used to determine potential identifiers of myocardial fibrosis. Setting The Royal Brompton Hospital, London, UK Participants One hundred and thirteen patients in derivation cohort and 26 patients in validation cohort. Main outcome measures Identification of myocardial fibrosis. Results Three blood biomarkers (serum platelets, serum urea, N-terminal pro-B-type natriuretic peptide) and left ventricular ejection fraction were shown to be capable of identifying myocardial fibrosis. The model was validated in a separate cohort of 26 patients. Conclusions Although further external validation of the model is necessary prior to its use in clinical practice, the proposed clinical model may direct patient care with respect to earlier magnetic resonance imagining, frequency of monitoring and may help in risk stratification for surgical intervention for myocardial fibrosis in patients with aortic stenosis

Drawing the (Color)line: Hemingway's America, Africa, and the Question(ing) of Authority

My examination asserts that Ernest Hemingway's modernity lies beyond mere stylistic technique and aesthetic concerns and finds itself in what perhaps is an inadvertent appreciation of W.E. B. Du Bois' prognostication that race would be the pervasive issue for a "progressive" nation looking to the first decades of the twentieth century. I contend that Hemingway not only shares Faulkner's concerns with the issue of race in America, but that he takes them well beyond the bounds of the South or any particular region and extends them to the rest of the nation. Little to nothing has been said about Hemingway's investment in issues of race; this examination intends to end that relative silence. Hemingway's marked interest in race (de)formation is closely aligned to a vested national interest in and an anxiety over a rapidly changing American racial topography and issues of American (White) identity. The works in this examination become then an expression of what I will call a collective angst in the wake of a perpetually fading color line and, correspondingly, an ever-eroding Anglo power structure. Hemingway's reaction is a simultaneous questioning of (White) self-identity and coveted authoritarian right and a marked re-entrenchment in standard racial typology. The so-called Indian stories work well to explore ideas of miscegenation (I use this term broadly to suggest race mixing and influence in a general sense) and White "vulnerability," and they attest to the author's ambivalence. Hemingway's African American centered stories continue this exploration of color-line transgression and the deconstruction of White identity, with the added element of violence as a possible means to that end. Thus, Africa becomes Hemingway's imaginative enclave of Anglo agency. Moreover, imperial Africa (more specifically, the metaphorical, geopolitical space inhabited by the Anglo) becomes the site within which he, as White subject-self, can control the placement, demarcation, and enforcement of that coveted colorline. This very emphatic racial awareness, nonetheless, is what also draws Hemingway into the realm of the Modern

Strengthening the global system of protected areas post-2020: A perspective from the IUCN World Commission on Protected Areas

Protected areas are the cornerstones of biodiversity conservation and have never been more relevant than at the present time when the world is facing both a biodiversity and a climate change crisis. The International Union for Conservation of Nature (IUCN) World Commission on Protected Areas (WCPA) has been helping to set global standards and best practice guidelines in protected area planning and management for 60 years. Following this guidance, many countries have made significant progress toward their Aichi Target 11 commitments under the Convention on Biological Diversity (CBD). The global community will be coming together at the 15th Conference of the Parties of the CBD to set new biodiversity conservation targets for the next decade, as milestones to 2050 and a vision of “a world living in harmony with nature.” This paper lays out the WCPA perspective on priorities for supporting effective protected and conserved areas for the post-2020 era

Noise and chaos contributions in fast random bit sequence generated from broadband optoelectronic entropy sources

International audienceDuring the last 4 years, chaotic waveforms for random number generation found a deep interest within the community of analogue broadband chaotic optical systems. Earlier investigations on chaos-based RNG were proposed in the 90s and early 2000, however mainly based on piecewise linear (PL) 1D map, with bit rate determined by analog electronic processing capabilities to provide the PL nonlinear function of concern. Optical chaos came with promises for much higher bit rate, and entropy sources based on high complexity (high dimensional) continuous time (differential) dynamics. More specifically in 2009, Reidler et al. published a paper entitled "An optical ultrafast random bit generator", in which they presented a physical system for a random number generator based on a chaotic semiconductor laser. This generator is claimed to reach potentially the extremely high rate of 300 Gb/s. We report on analysis and experiments of their method, which leads to the discussion about the actual origin of the obtained randomness. Through standard signal theory arguments, we show that the actual binary randomness quality obtained from this method, can be interpreted as a complex mixing operated on the initial analogue entropy source. Our analysis suggests an explaination about the already reported issue that this method does not necessarily require any specific deterministic property (i.e. chaos) from the physical signal used as the physical source of entropy. The bit stream randomness quality is found to result from "aliasing" phenomena performed by the post-processing method, both for the sampling and the quantization operations. As an illustration, such random bit sequences extracted from different entropy sources are investigated. Optoelectronic noise is used as a non deterministic entropy source. Electro-optic phase chaotic signal, as well as simulations of its deterministic model, are used as deterministic entropy sources. In all cases, the extracted bit sequence reveals excellent randomness

The improvement of Mo/4H-SiC Schottky diodes via a P2O5 surface passivation treatment

Molybdenum (Mo)/4H-silicon carbide (SiC) Schottky barrier diodes have been fabricated with a phosphorus pentoxide (P2O5) surface passivation treatment performed on the SiC surface prior to metallization. Compared to the untreated diodes, the P2O5-treated diodes were found to have a lower Schottky barrier height by 0.11 eV and a lower leakage current by two to three orders of magnitude. Physical characterization of the P2O5-treated Mo/SiC interfaces revealed that there are two primary causes for the improvement in electrical performance. First, transmission electron microscopy imaging showed that nanopits filled with silicon dioxide had formed at the surface after the P2O5 treatment that terminates potential leakage paths. Second, secondary ion mass spectroscopy revealed a high concentration of phosphorus atoms near the interface. While only a fraction of these are active, a small increase in doping at the interface is responsible for the reduction in barrier height. Comparisons were made between the P2O5 pretreatment and oxygen (O2) and nitrous oxide (N2O) pretreatments that do not form the same nanopits and do not reduce leakage current. X-ray photoelectron spectroscopy shows that SiC beneath the deposited P2O5 oxide retains a Si-rich interface unlike the N2O and O2 treatments that consume SiC and trap carbon at the interface. Finally, after annealing, the Mo/SiC interface forms almost no silicide, leaving the enhancement to the subsurface in place, explaining why the P2O5 treatment has had no effect on nickel- or titanium-SiC contacts

Real-time measurements of spontaneous breathers and rogue wave events in optical fibre modulation instability

Modulation instability is a fundamental process of nonlinear science, leading to the unstable breakup of a constant amplitude solution of a physical system. There has been particular interest in studying modulation instability in the cubic nonlinear Schrödinger equation, a generic model for a host of nonlinear systems including superfluids, fibre optics, plasmas and Bose–Einstein condensates. Modulation instability is also a significant area of study in the context of understanding the emergence of high amplitude events that satisfy rogue wave statistical criteria. Here, exploiting advances in ultrafast optical metrology, we perform real-time measurements in an optical fibre system of the unstable breakup of a continuous wave field, simultaneously characterizing emergent modulation instability breather pulses and their associated statistics. Our results allow quantitative comparison between experiment, modelling and theory, and are expected to open new perspectives on studies of instability dynamics in physics

Supporting place-specific interaction through a physical/digital assembly

This article examines visitor interactions with and through a physical/digital installation designed for an open-air museum that displays historic buildings and ways of life from the past. The installation was designed following the “Assembly” design scheme proposed by Fraser et al. (2003), and centred around five principles for the design of interactive experiences. We discuss how the Assembly framework was adapted and applied to our work on the installation called Reminisce, and we then present qualitative data gathered through the shadowing and naturalistic observations of small groups of visitors using Reminisce during their exploration of the museum. Through these data excerpts we illustrate how interaction occurred among visitors and with the assembly. We reflect on the guiding principles of the adapted Assembly framework and on their usefulness for the design of place-specific interactional opportunities in heritage settings. Results from the empirical study show that the adapted Assembly principles provide HCI researchers and designers with ways in which to flexibly support collocated interactions at heritage sites across artefacts and locations in ways that both complement and enrich the physical setting of the visit and its character

Left ventricular remodeling and hypertrophy in patients with aortic stenosis:insights from cardiovascular magnetic resonance

<p>Abstract</p> <p>Background</p> <p>Cardiovascular magnetic resonance (CMR) is the gold standard non-invasive method for determining left ventricular (LV) mass and volume but has not been used previously to characterise the LV remodeling response in aortic stenosis. We sought to investigate the degree and patterns of hypertrophy in aortic stenosis using CMR.</p> <p>Methods</p> <p>Patients with moderate or severe aortic stenosis, normal coronary arteries and no other significant valve lesions or cardiomyopathy were scanned by CMR with valve severity assessed by planimetry and velocity mapping. The extent and patterns of hypertrophy were investigated using measurements of the LV mass index, indexed LV volumes and the LV mass/volume ratio. Asymmetric forms of remodeling and hypertrophy were defined by a regional wall thickening <b>≥</b>13 mm and >1.5-fold the thickness of the opposing myocardial segment.</p> <p>Results</p> <p>Ninety-one patients (61±21 years; 57 male) with aortic stenosis (aortic valve area 0.93±0.32cm2) were recruited. The severity of aortic stenosis was unrelated to the degree (r²=0.012, P=0.43) and pattern (P=0.22) of hypertrophy. By univariate analysis, only male sex demonstrated an association with LV mass index (P=0.02). Six patterns of LV adaption were observed: normal ventricular geometry (n=11), concentric remodeling (n=11), asymmetric remodeling (n=11), concentric hypertrophy (n=34), asymmetric hypertrophy (n=14) and LV decompensation (n=10). Asymmetric patterns displayed considerable overlap in appearances (wall thickness 17±2mm) with hypertrophic cardiomyopathy.</p> <p>Conclusions</p> <p>We have demonstrated that in patients with moderate and severe aortic stenosis, the pattern of LV adaption and degree of hypertrophy do not closely correlate with the severity of valve narrowing and that asymmetric patterns of wall thickening are common.</p> <p>Trial registration</p> <p>ClinicalTrials.gov Reference Number: NCT00930735</p

A novel cardiovascular magnetic resonance risk score for predicting mortality following surgical aortic valve replacement

The increasing prevalence of patients with aortic stenosis worldwide highlights a clinical need for improved and accurate prediction of clinical outcomes following surgery. We investigated patient demographic and cardiovascular magnetic resonance (CMR) characteristics to formulate a dedicated risk score estimating long-term survival following surgery. We recruited consecutive patients undergoing CMR with gadolinium administration prior to surgical aortic valve replacement from 2003 to 2016 in two UK centres. The outcome was overall mortality. A total of 250 patients were included (68 ± 12 years, male 185 (60%), with pre-operative mean aortic valve area 0.93 ± 0.32cm2, LVEF 62 ± 17%) and followed for 6.0 ± 3.3 years. Sixty-one deaths occurred, with 10-year mortality of 23.6%. Multivariable analysis showed that increasing age (HR 1.04, P = 0.005), use of antiplatelet therapy (HR 0.54, P = 0.027), presence of infarction or midwall late gadolinium enhancement (HR 1.52 and HR 2.14 respectively, combined P = 0.12), higher indexed left ventricular stroke volume (HR 0.98, P = 0.043) and higher left atrial ejection fraction (HR 0.98, P = 0.083) associated with mortality and developed a risk score with good discrimination. This is the first dedicated risk prediction score for patients with aortic stenosis undergoing surgical aortic valve replacement providing an individualised estimate for overall mortality. This model can help clinicians individualising medical and surgical care