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

Compact Cylindrical Sector Dielectric Resonator Antennas

In this paper, we investigate cylindrical sector Dielectric Resonator Antenna (DRA) geometries that are formed by removing a sector (or equivalently a wedge) of dielectric material from a circular cylinder. The advantage this geometry offers, compared to conventional cylindrical DRAs, are reductions in volume, support of &quot;fractional modes&quot;, and allowance of dual-frequency/dualfeed operation. Approximate theory, simulation and experimental results are provided to support our findings. In particular, a cylindrical sector DRA is demonstrated to have 75% less volume than a conventional cylindrical DRA, with the same resonant frequency, giving it potential for use in wireless communication handsets. I. Introduction Recently, dielectric resonators have been shown to be practical elements for antenna applications and have several merits including high radiation efficiency, flexible feed arrangement, simple geometry and compactness [1], [2]. In this paper, we investigate cylindrical sector Di..

Orthogonal Space Division Multiplexing Through Joint use of Multi-user MIMO Smart Antennas

In this paper, we address the problem of enhancing the performance (including the system capacity and average user bit error probability) of a multi-user multiple-input multiple-output (MIMO) system for communication from one base station to many mobile stations in multipath Rayleigh fading channels. This problem arises in multi-user space division multiplexing (SDM) systems where multiple independent signal streams can be transmitted in the same frequency band and time slot, through the exploitation of multiple antennas at both the base and mobile stations. The objective of this paper is to devise a multi-user linear space-time precoder for simultaneous channel diagonalization of multi-user channels enabling orthogonal space division multiplexing (OSDM). Our approach is based on diagonalizing the multi-user channel matrices and we use a variation of successive Jacobi rotations. The assumption for this scheme is that the BS knows all the channels and the channel dynamics are quasi-stationary over a block of precoded bits as is typical of indoor, low mobility high speed wireless communications