There is currently substantial confusion between the conceptual definition of the metabolic syndrome and the clinical screening parameters and cut-off values proposed by various organizations (NCEP-ATP III, IDF, WHO, etc) to identify individuals with the metabolic syndrome. Although it is clear that in vivo insulin resistance is a key abnormality associated with an atherogenic, prothrombotic, and inflammatory profile which has been named by some the “metabolic syndrome” or by others “syndrome X” or “insulin resistance syndrome”, it is more and more recognized that the most prevalent form of this constellation of metabolic abnormalities linked to insulin resistance is found in patients with abdominal obesity, especially with an excess of intra-abdominal or visceral adipose tissue. We have previously proposed that visceral obesity may represent a clinical intermediate phenotype reflecting the relative inability of subcutaneous adipose tissue to act as a protective metabolic sink for the clearance and storage of the extra energy derived from dietary triglycerides, leading to ectopic fat deposition in visceral adipose depots, skeletal muscle, liver, heart, etc. Thus, visceral obesity may partly be a marker of a dysmetabolic state and partly a cause of the metabolic syndrome. Although waist circumference is a better marker of abdominal fat accumulation than the body mass index, an elevated waistline alone is not sufficient to diagnose visceral obesity and we have proposed that an elevated fasting triglyceride concentration could represent, when waist circumference is increased, a simple clinical marker of excess visceral/ectopic fat. Finally, a clinical diagnosis of visceral obesity, insulin resistance, or of the metabolic syndrome is not sufficient to assess global risk of cardiovascular disease. To achieve this goal, physicians should first pay attention to the classical risk factors while also considering the additional risk resulting from the presence of abdominal obesity and the metabolic syndrome, such global risk being defined as cardiometabolic risk.
Symptomatic CO following TAVI was a rare but life-threatening complication that occurred more frequently in women, in patients receiving a balloon-expandable valve, and in those with a previous surgical bioprosthesis. Lower-lying coronary ostium and shallow sinus of Valsalva were associated anatomic factors, and despite successful treatment, acute and late mortality remained very high, highlighting the importance of anticipating and preventing the occurrence of this complication.
The possibility of recovering the Green's function from the field-field correlations of coda waves in an open multiple scattering medium is investigated. The argument is based on fundamental symmetries of reciprocity, time-reversal invariance, and the Helmholtz-Kirchhoff theorem. A criterion is defined, indicating how sources should be placed inside an open medium in order to recover the Green's function between two passive receivers. The case of noise sources is also discussed. Numerical experiments of ultrasonic wave propagation in a multiple scattering medium are presented to support the argument.Wave propagation in a multiple scattering or reverberating environment has been a subject of interest in a wide variety of domains ranging from solid state physics to optics or acoustics. Ultrasound is particularly interesting because it allows a direct measurement of the field fluctuations, both in amplitude and in phase. In connection with this, a remarkable work by Weaver and Lobkis 1-3 recently showed that the Green's function between two points could be recovered from the field-field correlation of a diffuse ultrasonic field. This amounts to doing ''ultrasonics without a source'' since they showed that thermal noise could be used instead of a direct pulse/echo measurement between the two points. The experiment was carried out in an aluminum block, and the theoretical analysis was based on discrete modal expansion of the field, with random modal amplitudes. Applications are promising: it would be possible to recover the Green's function of a complex medium just by correlating diffuse fields received on passive sensors ͑application to shallow water ocean acoustics, where the field is not diffuse but propagates in a wave guide, was also evoked 4 ͒.However, the basic assumption in the theoretical analysis is that the medium is closed and free of absorption. In a real medium, absorption will tend to cut out the longest scattering ͑or reverberating͒ paths, and discrete modes will not be resolved any more. Similar problems are expected if the medium is open rather than closed ͑actually, in an open medium, the fluctuation-dissipation theorem 3 establishes the result, as long as the field is diffuse in the thermal sense͒. The aim of this letter is to examine whether the Green's function can still be recovered from the correlations of an ultrasonic wave field in an open scattering medium, when a discrete expansion on orthogonal modes is no longer relevant and the field is not thermally diffuse.To that end, we present 2-D numerical experiments of acoustic scattering on rigid inclusions randomly located either in a closed cavity or in a open medium. The wave equation is solved by a finite differences simulation ͑centered scheme͒; the boundary conditions is implemented following Collino's work. 5 Naturally, a finite difference scheme shows numerical dispersion. However, the essential point is that the fundamental symmetries of reciprocity and time reversal still hold in the numerical experiments.To begin with, let us consider...
[1] Forecasting the location of an eruption is of primary importance for risk management in volcanic regions. Locating the underground structural changes associated with a potential eruption is also a key issue to better understand the dynamics at work in a volcano. Using recent results in wave physics, we develop an imaging procedure that is based on the sensitivity of multiply scattered waves to weak changes in heterogeneous media. This procedure allows to locate changes in both mechanical and scattering properties of the studied medium. We study ambient seismic noise from 19 broadband stations at the active volcano Piton de la Fournaise on Reunion Island, recorded from June to December 2010. During this period, two volcanic eruptions occurred at two different locations. We calculate the noise cross correlations and study two types of changes in the coda: apparent velocity variations related to changes in the elastic properties of the medium; and, waveform decoherence associated with variations in the scattering, and thus the geological structures. We observe that the temporal variations of both of these parameters provide potential precursors of volcanic eruptions at Piton de la Fournaise. The locations determined from the preeruptive and coeruptive changes in both parameters are in good agreement with the actual eruptive activities. These data demonstrate that the coda of ambient noise correlations contains deterministic information on the locations of the eruptive processes in an active volcano. Our analysis offers an original and significant constraint for the localization of forthcoming volcanic eruptions.Citation: Obermann, A., T. Planès, E. Larose, and M. Campillo (2013), Imaging preeruptive and coeruptive structural and mechanical changes of a volcano with ambient seismic noise,
for the Early Discharge After Transradial Stenting of Coronary Arteries (EASY) Study InvestigatorsBackground-Systematic use of coronary stents and optimized platelet aggregation inhibition has greatly improved the short-term results of percutaneous coronary interventions. Transradial percutaneous coronary interventions have been associated with a low risk of bleeding complications. It is unknown whether moderate-and high-risk patients can be discharged safely the same day after uncomplicated transradial percutaneous coronary interventions. Methods and Results-We randomized 1005 patients after a bolus of abciximab and uncomplicated transradial percutaneous coronary stent implantation either to same-day home discharge and no infusion of abciximab (group 1, nϭ504) or to overnight hospitalization and a standard 12-hour infusion of abciximab (group 2, nϭ501). The primary composite end point of the study was the 30-day incidence of any of the following events: death, myocardial infarction, urgent revascularization, major bleeding, repeat hospitalization, access site complications, and severe thrombocytopenia. The noninferiority of same-day home discharge and bolus of abciximab only compared with overnight hospitalization and abciximab bolus and infusion was evaluated. Two thirds of patients presented with unstable angina and Ϸ20% presented with high-risk acute coronary syndrome prior to the procedure. The incidence of the primary end point was 20.4% in group 1 and 18.2% in group 2 (Pϭ0.017 for noninferiority) with a troponin T-based definition of myocardial infarction; the incidence of the primary end point was 11.1% in group 1 and 9.6% in group 2 (Pϭ0.0004 for noninferiority) with a creatinine kinase myocardial band-based definition of myocardial infarction. No death occurred. Rate of major bleeding in both groups was extremely low at 0.8% and 0.2%, respectively. From 504 patients randomized in group 1, 88% were discharged home the same day. Conclusion-Our data suggest that same-day home discharge after uncomplicated transradial coronary stenting and bolus only of abciximab is not clinically inferior, in a wide spectrum of patients, to the standard overnight hospitalization and a bolus followed by a 12-hour infusion. This novel approach offers a safe strategy for same-day home discharge after uncomplicated coronary intervention. (Circulation. 2006;114:2636-2643.)
Previous studies have shown that small changes can be monitored in a scattering medium by observing phase shifts in the coda. Passive monitoring of weak changes through ambient noise correlation has already been applied to seismology, acoustics, and engineering. Usually, this is done under the assumption that a properly reconstructed Green function (GF), as well as stable background noise sources, is necessary. In order to further develop this monitoring technique, a laboratory experiment was performed in the 2.5 MHz range in a gel with scattering inclusions, comparing an active (pulse-echo) form of monitoring to a passive (correlation) one. Present results show that temperature changes in the medium can be observed even if the GF of the medium is not reconstructed. Moreover, this article establishes that the GF reconstruction in the correlations is not a necessary condition: The only condition to monitoring with correlation (passive experiment) is the relative stability of the background noise structure.
BACKGROUND Aortic valve calcification (AVC) load measures lesion severity in aortic stenosis (AS) and is useful for diagnostic purposes. Whether AVC predicts survival after diagnosis, independent of clinical and Doppler echocardiographic AS characteristics, has not been studied. OBJECTIVES This study evaluated the impact of AVC load, absolute and relative to aortic annulus size (AVCdensity), on overall mortality in patients with AS under conservative treatment and without regard to treatment. METHODS In 3 academic centers, we enrolled 794 patients (mean age, 73 ± 12 years; 274 women) diagnosed with AS by Doppler echocardiography who underwent multidetector computed tomography (MDCT) within the same episode of care. Absolute AVC load and AVCdensity (ratio of absolute AVC to cross-sectional area of aortic annulus) were measured, and severe AVC was separately defined in men and women. RESULTS During follow-up, there were 440 aortic valve implantations (AVIs) and 194 deaths (115 under medical treatment). Univariate analysis showed strong association of absolute AVC and AVCdensity with survival (both, p < 0.0001) with a spline curve analysis pattern of threshold and plateau of risk. After adjustment for age, sex, coronary artery disease, diabetes, symptoms, AS severity on hemodynamic assessment, and LV ejection fraction, severe absolute AVC (adjusted hazard ratio [HR]: 1.75; 95% confidence interval [CI]: 1.04 to 2.92; p = 0.03) or severe AVCdensity (adjusted HR: 2.44; 95% CI: 1.37 to 4.37; p = 0.002) independently predicted mortality under medical treatment, with additive model predictive value (all, p ≤ 0.04) and a net reclassification index of 12.5% (p = 0.04). Severe absolute AVC (adjusted HR: 1.71; 95% CI: 1.12 to 2.62; p = 0.01) and severe AVCdensity (adjusted HR: 2.22; 95% CI: 1.40 to 3.52; p = 0.001) also independently predicted overall mortality, even with adjustment for time-dependent AVI. CONCLUSIONS This large-scale, multicenter outcomes study of quantitative Doppler echocardiographic and MDCT assessment of AS shows that measuring AVC load provides incremental prognostic value for survival beyond clinical and Doppler echocardiographic assessment. Severe AVC independently predicts excess mortality after AS diagnosis, which is greatly alleviated by AVI. Thus, measurement of AVC by MDCT should be considered for not only diagnostic but also risk-stratification purposes in patients with AS.
Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the COVID-19 pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic noise reduction on record. While the reduction is strongest at surface seismometers in populated areas, this seismic quiescence extends for many kilometers radially and hundreds of meters in depth. This provides an opportunity to detect subtle signals from subsurface seismic sources that would have been concealed in noisier times and to benchmark sources of anthropogenic noise. A strong correlation between seismic noise and independent measurements of human mobility suggests that seismology provides an absolute, real-time estimate of population dynamics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
334 Leonard St
Brooklyn, NY 11211
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.