Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Elastic-plastic stress analysis of a thermoplastic composite disc under linear temperature distribution

WOS: 000235778200004In the present study, an elastic-plastic stress analysis is carried out on a composite thermoplastic disc reinforced by steel fibers, curvilinearly. Radial and tangential stresses are obtained under a liner temperature distribution. The magnitude of the tangential stress component for elastic and elastic-plastic cases is higher than that of the radial stress component. The tangential stress component is compressive and tensile on the inner and outer surfaces, respectively and is the highest on the inner surface. The elastic-plastic solution is performed for the plastic region expanded around the inner surface by an analytical formulation and a numerical solution. The solution is also carried out by the finite element method (ANSYS solution). These two solutions give very similar results. The intensities of the residual stress component of the tangential stress and plastic flow are the highest at the inner surface

Elastic-plastic stress analysis of simply supported and clamped aluminum metal-matrix laminated plates with a hole

In this study, an elastic-plastic stress analysis is carried out on simply supported and clamped cross-ply and angle-ply aluminum metal-matrix composite laminated plates with a circular hole. Classical lamination theory with first-order shear deformation theory is used for small deformations. The expansion of the plastic region and residual stress components are obtained on the upper and lower surfaces of the plates by using the finite element method. They are loaded on the upper surface transversely. Loading is gradually increased from the yield point of the plate by 0.0001 MPa at each load step. Load step numbers are chosen as 400, 600 and 800. (C) 2001 Elsevier Science Ltd. All rights reserved

An elastic/plastic solution for a thermoplastic composite cantilever beam loading by bending moment

In this study, an elastic/plastic stress analysis is carried out for a thermoplastic composite cantilever beam loaded by a bending moment at the free end. The composite beam is reinforced by woven steel fibers, at 0, 15, 30 and 45 degrees orientation angles. An analytical solution is performed for satisfying both the governing differential equation in the plane stress case and boundary conditions for small plastic deformations. The solution is carried out under the assumption of the Bernoulli-Navier hypotheses. It is found that the intensity of the residual stress component of sigma (x) is a maximum at the upper and lower surfaces. The composite material is assumed to be as hardening linearly. The Tsai-Hill theory is used as a yield criterion. (C) 2000 Elsevier Science Ltd. All rights reserved

Elastic-plastic stress analysis of simply supported and clamped thermoplastic composite laminated plates loaded transversely

In this study, an elastic-plastic stress analysis is carried out on simply supported and clamped cross-ply and angle-ply steel fiber reinforced thermoplastic composite laminated plates under transverse loading. Classical lamination theory with first order shear deformation theory are used for small plastic deformations. The orientation angles are chosen as [0degrees/90degrees](2), [30degrees/-30degrees](2), [45degrees/-45degrees](2), [60degrees/-60degrees](2) for symmetric and antisymmetric cases. Loading is gradually increased in sequence of 100, 300 and 500. The expansion of the plastic region and the residual stress components are obtained by using the finite element technique

Numerical elastic plastic stress analysis in a woven steel reinforced composite thermoplastic cantilever beam

In this study, an elastic-plastic stress analysis has been carried out in a thermoplastic composite cantilever beam. The thermoplastic composite beam was reinforced by steel woven fibers. The beam was loaded uniformly. The orientation angles were chosen as 0°, 15°, 30° and 45°. The finite element models of the beams were developed by using ANSYS software. The obtained results from the nonlinear analyses show that the residual stress component of σ x is the highest at the fixed end at the upper and lower edges for the 0° orientation. However, it is the highest on or around the elastic plastic boundaries for the 15°, 30° and 45° orientations. The magnitude of the residual stress component of τ xy is found to be the highest at or around the axis of the beam at the fixed end. 30° orientation produces the highest stress component of τ xy around the axis of the beam. Also, it is found that the magnitude of the residual stress component of σ x is higher that that of the τ xy

An elastic-plastic and residual stress analysis of symmetric laminated cantilever beam under a bending moment

WOS: 000188710400006An elastic-plastic stress analysis in symmetric woven steel fiber reinforced polyethylene thermoplastic matrix laminated cantilever beam under a bending moment is studied by using analytical method and the Bernoulli-Euler theory for small plastic deformations. The orientation of the plies is chosen as (0degrees)(4), (15degrees/-15degrees)(2), (30degrees/-30degrees)(2) and (45degrees/-45degrees)(2). The Tsai-Hill theory is used as a yield criterion. Elastic and plastic stresses are the highest at the upper and lower surfaces. The residual stress component of sigma(x) is maximized at the upper and lower surfaces. However. when the plastic region is further expanded, it is the highest at the boundary of the elastic and plastic regions. The magnitude of the residual stress component of sigma(x) is found to be the highest for (0degrees)(4) orientations. The plastic flow is maximized at the upper and lower surfaces for (0degrees)(4) orientations