An assessment of completeness and medical coding of Medicare Advantage hospitalizations in two national data sets.

Objective: To compare the Encounter Data System (EDS) and Medicare Provider Analysis and Review (MedPAR) completeness and medical coding of Medicare Advantage hospitalizations.

Data Sources: FY 2016-FY 2019 data limited to hospitals paid under Medicare's Inpatient Prospective Payment System.

Study Design: Secondary data analysis.

Asymptotics of the meta-atom: plane wave scattering by a single Helmholtz resonator.

Using a combination of multipole methods and the method of matched asymptotic expansions, we present a solution procedure for acoustic plane wave scattering by a single Helmholtz resonator in two dimensions. Closed-form representations for the multipole scattering coefficients of the resonator are derived, valid at low frequencies, with three fundamental configurations examined in detail: the thin-walled, moderately thick-walled and extremely thick-walled limits. Additionally, we examine the impact of dissipation for extremely thick-walled resonators, and also numerically evaluate the scattering, absorption and extinction cross-sections (efficiencies) for representative resonators in all three wall thickness regimes.

Deeply subwavelength giant monopole elastodynamic metacluster resonators.

The giant monopole resonance is a well-known phenomenon, employed to tune the dynamic response of composite materials comprising voids in an elastic matrix which has a bulk modulus much greater than its shear modulus, e.g. elastomers.

Thermo-viscous damping of acoustic waves in narrow channels: A comparison of effects in air and water.

Recent work in the acoustic metamaterial literature has focused on the design of metasurfaces that are capable of absorbing sound almost perfectly in narrow frequency ranges by coupling resonant effects to visco-thermal damping within their microstructure. Understanding acoustic attenuation mechanisms in narrow, viscous-fluid-filled channels is of fundamental importance in such applications. Motivated by recent work on acoustic propagation in narrow, air-filled channels, a theoretical framework is presented that demonstrates the controlling mechanisms of acoustic propagation in arbitrary Newtonian fluids, focusing on attenuation in air and water.

Variation in chest pain emergency department admission rates and acute myocardial infarction and death within 30 days in the Medicare population.

Objectives: The objective was to assess the relationship between emergency department (ED) admission rates for Medicare beneficiaries with chest pain and outcomes, specifically 30-day rates of acute myocardial infarction (AMI) and mortality.

Methods: Using a 20% random sample of Medicare beneficiaries in 2009, 158,295 beneficiaries with a primary diagnosis of chest pain at the conclusion of their ED visits were selected to assess outcomes based on the decision to hospitalize or discharge home. The proportions of these patients admitted to inpatient or observation status at 2,219 U.