Resource Re-Allocation During the COVID-19 Pandemic in a Suburban Hospital System: Implications for Outpatient Hip and Knee Arthroplasty

The COVID pandemic of 2020 has emerged as a global threat to patients, health care providers, and to the global economy. Owing to this particular novel and highly infectious strain of coronavirus, the rapid community spread and clinical severity of the subsequent respiratory syndrome created a substantial strain on hospitals and health care systems around the world. The rapid surge of patients presenting over a small period for emergent clinical care, admission to the hospital, and intensive care units with many requiring mechanically assisted ventilators for respiratory support demonstrated the potential to overwhelm health care workers, hospitals, and health care systems. The purpose of this article is to describe an effective system for redeployment of health care supplies, resources, and personnel to hospitals within a suburban academic hospital system to optimize the care of COVID patients, while treating orthopedic patients in an equally ideal setting to maximize their surgical and clinical care. This article will provide a particular focus on the current and future role of a specialty hip and knee hospital and its partnering ambulatory surgery center in the context of an outpatient arthroplasty program

Application of the Lienard-Wiechert solution to a lightning return stroke model

The electric and magnetic fields associated with the lightning return stroke are expressed as a convolution of the current waveform shape and the fields generated by a moving charge of amplitude one (i.e., the Lienard-Wiechert solution for a unit charge). The representation can be used to compute the fields produced by a current waveform of non-uniform velocity that propagates along a filament of arbitrary, but finite, curvature. To study numerically the effects of linear charge acceleration and channel curvature two simple channel models are used: the linear and the hyperbolic

Spaceborne meteorological radar studies

Various radar designs and methods are studied for the estimation of rainfall parameters from space. An immediate goal is to support the development of the spaceborne radar that has been proposed for the Tropical Rain Measuring Mission (TRMM). The effort is divided into two activities: a cooperative airborne rain measuring experiment with the Radio Research Laboratory of Japan (RRL), and the modelling of spaceborne weather radars. An airborne rain measuring experiment was conducted at Wallops Flight Facility in 1985 to 1986 using the dual-wavelength radar/radiometer developed by RRL. The data are presently being used to test a number of methods that are relevant to spaceborne weather radars. An example is shown of path-averaged rain rates as estimated from three methods: the standard reflectivity rain rate method (Z-R), a dual-wavelength method, and a surface reference method. The results from the experiment shows for the first time the feasibility of using attenuation methods from space. The purposes of the modelling are twofold: to understand in a quantitative manner the relationships between a particular radar design and its capability for estimating precipitation parameters and to help devise and test new methods. The models are being used to study the impact of various TRMM radar designs on the accuracy of rain rate estimation as well as to test the performance of range-profiling algorithms, the mirror-image method, and some recently devised graphical methods for the estimation of the drop size distribution

An application of the Braunbeck method to the Maggi-Rubinowicz field representation

The Braunbek method is applied to the generalized vector potential associated with the Maggi-rubinowicz representation. Under certain approximations, an asymptotic evaluation of the vector potential is obtained. For observation points away from caustics or shadow boundaries, the field derived from this quantity is the same as that determined from the geometrical theory of diffraction on a singly diffracted edge ray. An evaluation of the field for the simple case of a plane wave normally incident on a circular aperture is presented showing that the field predicted by the Maggi-Rubinowicz theory is continuous across the shadow boundary

Rain rate range profiling from a spaceborne radar

At certain frequencies and incidence angles the relative invariance of the surface scattering properites over land can be used to estimate the total attenuation and the integrated rain from a spaceborne attenuation-wavelength radar. The technique is generalized so that rain rate profiles along the radar beam can be estimated, i.e., rain rate determination at each range bin. This is done by modifying the standard algorithm for an attenuating-wavelength radar to include in it the measurement of the total attenuation. Simple error analyses of the estimates show that this type of profiling is possible if the total attenuation can be measured with a modest degree of accuracy

Posterior stabilized designs in modern total knee arthroplasty: Vestigial organs

Clinical difference between posterior-stabilized (PS) and cruciate-retaining (CR) designs in total knee arthroplasty has remained elusive for decades. This classic debate has been given pause due to futile efforts to prove one design superior over the other. Recently, anterior-lipped and more conforming CR bearings have emerged to substitute for the posterior-cruciate ligament (PCL), if absent, damaged or resected, and obviate the need for the archaic cam-post mechanism of a traditional PS design. Advantages of avoiding a PS TKA include eliminating the risk of box cut induced femoral condylar fracture, operative efficiency by removing procedural steps, removing the articulation that is a source of wear, post deformation, breakage, or dislocation, and eliminating patellar clunk

Simultaneous ocean cross-section and rainfall measurements from space with a nadir-pointing radar

A method to determine simultaneously the rainfall rate and the normalized backscattering cross section of the surface was evaluated. The method is based on the mirror reflected power, p sub m which corresponds to the portion of the incident power scattered from the surface to the precipitation, intercepted by the precipitation, and again returned to the surface where it is scattered a final time back to the antenna. Two approximations are obtained for P sub m depending on whether the field of view at the surface is either much greater or much less than the height of the reflection layer. Since the dependence of P sub m on the backscattering cross section of the surface differs in the two cases, two algorithms are given by which the path averaged rain rate and normalized cross section are deduced. The detectability of P sub m, the relative strength of other contributions to the return power arriving simultaneous with P sub m, and the validity of the approximations used in deriving P sub m are discussed

Radiation from a current filament driven by a traveling wave

Solutions are presented for the electromagnetic fields radiated by an arbitrarily oriented current filament located above a perfectly conducting ground plane and excited by a traveling current wave. Both an approximate solution, valid in the fraunhofer region of the filament and predicting the radiation terms in the fields, and an exact solution, which predicts both near and far field components of the electromagnetic fields, are presented. Both solutions apply to current waveforms which propagate along the channel but are valid regardless of the actual waveshape. The exact solution is valid only for waves which propagate at the speed of light, and the approximate solution is formulated for arbitrary velocity of propagation. The spectrum-magnitude of the fourier transform-of the radiated fields is computed by assuming a compound exponential model for the current waveform. The effects of channel orientation and length, as well as velocity of propagation of the current waveform and location of the observer, are discussed. It is shown that both velocity of propagation and an effective channel length are important in determining the shape of the spectrum

Simulation of radiation from lightning return strokes: The effects of tortuosity

A Monte Carlo simulation has been developed for the electromagnetic fields radiated from a tortuous lightning channel. This was done using a piecewise linear model for the channel and employing for each element the field radiated by a traveling wave on an arbitrarily oriented filament over a conducting plane. The simulation reproduces experimental data reasonably well and had been used to study the effects of tortuousity on the fields radiated by return strokes. Tortuosity can significantly modify the radiated waveform, tending to render it less representative of the current pulse and more nearly unipolar than one would expect based on the theory for a long straight channel. In the frequency domain the effect of tortuosity is an increase in high frequency energy as compared with an equivalent straight channel. The extent of this increase depends on the mean length of the elements comprising the channel and can be significant

Vector analogues of the Maggi-Rubinowicz theory of edge diffraction

The Maggi-Rubinowicz technique for scalar and electromagnetic fields is interpreted as a transformation of an integral over an open surface to a line integral around its rim. Maggi-Rubinowicz analogues are found for several vector physical optics representations. For diffraction from a circular aperture, a numerical comparison between these formulations shows the two methods are in agreement. To circumvent certain convergence difficulties in the Maggi-Rubinowicz integrals that occur as the observer approaches the shadow boundary, a variable mesh integration is used. For the examples considered, where the ratio of the aperture diameter to wavelength is about ten, the Maggi-Rubinowicz formulation yields an 8 to 10 fold decrease in computation time relative to the physical optics formulation