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

Thermal elastic-plastic stress analysis of symmetric aluminum metal-matrix composite laminated plates under uniformly distributed temperature

In this study, a thermal elastic-plastic stress analysis is carried out on simply supported symmetric cross-ply (0degrees/90degrees)(2) and angle-ply (5degrees/85degrees)(2), (15degrees/-15degrees)(2), (30degrees/-30degrees)(2), (45degrees/-45degrees)(2), (60degrees/60degrees)(2), (15degrees/60degrees)(2), (15degrees/75degrees)(2), (75degrees/-75degrees)(2) aluminum metal-matrix laminated plates under the uniform temperature distribution across the thickness of the plates. The Tsai-Hill criterion is used as a yield criterion. Differential equations are solved with a sufficiently large number of integration intervals of the temperature. The composite material is assumed to be strain hardening linearly. The magnitude of the residual stress components in the cross-ply laminated plate are higher than those in the angle-ply laminated plates. Plastic yielding occurs in all the laminated plates at the same temperature

An elastic-plastic stress analysis of metal-matrix composite beam loaded transversely

An elastic-plastic stress analysis has been carried out in a stainless steel fiber reinforced aluminum matrix composite beam. The beam is loaded by a single force at its free end. The composite material is assumed perfectly plastic to simplify the investigation. An exact solution is given for the elastic and elastic-plastic regions. Orientation angles of the fiber are chosen as 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees. The plastic zone expands at the upper side of the beam more than at the lower side for 30 degrees, 45 degrees and 60 degrees orientation angles. Residual stress components of sigma (x) and tau (xy) are found in the sections of the beam. The plastic collapse occurs at the different points for the beam of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees orientation angles

Elasto-plastic stress analysis in an adhesively bonded single-lap joint

In this study, an analytical elasto-plastic stress analysis was proposed to determine the shear stress in a ductile adhesively bonded single-lap joint. DP460 adhesive was employed in the present study. The von-Mises criterion was used for checking the yield condition of the adhesive material. In the solution, the shear stress was assumed to be constant across the thickness of the adhesive. Bending moment was neglected in the solution. Analytical results were checked by using the finite element analysis. ANSYS 10 was employed in the numerical solution. Analytical and numerical solutions are found to be in a good agreement (C) 2011 Elsevier Ltd. All rights reserved

Thermal elastic-plastic stress analysis of symmetric aluminum metal-matrix composite laminated plates under linearly distributed temperature

In this study, thermal elastic-plastic stress analysis is carried out on simply supported symmetric cross-ply (0degrees/90degrees)(2) and angle-ply (30degrees/-30degrees)(2), (45degrees/-45degrees)(2), (60degrees/-60degrees)(2) aluminum metal-matrix laminated plates under a linear temperature distribution across the thickness of plates. The temperature distribution is chosen as T-0 and zero at the lower and upper surfaces, respectively. Tsai-Hill theory is used as a yield criterion. Differential equations are solved with a sufficiently large number of integration intervals of the temperature. The composite material is assumed to be strain hardening linearly. The magnitude of the residual stress components of sigma(x) and sigma(y) is the highest at the upper and lower surfaces. Plastic yielding occurs in all the laminated plates at the same temperature

Analysis of multi-layered composite cylinders under hygrothermal loading

In this study, a general stress analysis is developed for thick or thin multi-layered composite cylinders under hygrothermal loadings. The layers are oriented symmetrically and antisymmetrically for [0 degrees/90 degrees](2), [30 degrees/-30 degrees](2), [45 degrees/-45 degrees](2) and [60 degrees/-60 degrees](2) orientations. The solution is carried out on composite cylinders for plane-strain, open end and closed end conditions. Uniform and parabolic temperature distributions are chosen for the thermal loads. All the integration constants are found from the radial stress and displacement in the normal direction of layers. The hygrothermal and other mechanical properties are measured on a glass-epoxy composite layer. Some analytical solutions are compared with the finite element solutions, in which commercial software ANSYS 7.0 is utilized, and close results are obtained between them. (c) 2005 Elsevier Ltd. All rights reserved

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

JOURNAL OF REINFORCED PLASTICS AND COMPOSITES

In this study, an elastic-plastic stress analysis is carried out on symmetric laminated composite beams subjected to a bending moment. The composite beam is to be strain hardening. The Tsai-Hill theory is used as a yield criterion in the solution. The Bernoulli and Euler hypotheses are assumed to be valid. The beam lay-up sequences are chosen as [90degrees/0degrees](s), [30degrees/-30degrees](s), [45degrees/-45degrees](s), and [60degrees/-60degrees](s). The bending moment starting plastic yielding is found to be highest for [30degrees/-30degrees](s) orientation. sigma(x) residual stress component is found to be highest at the upper and lower surfaces. However sigma(x), residual stress component becomes the highest at the elastic and plastic boundary for further expansion of the plastic region. The transverse displacement is obtained at the free end, numerically