Standardized incidence ratio of the COVID-19 pandemic: a case study in a Midwestern state

ABSTRACTMotivationThe Coronavirus disease 2019 (COVID-19) has made a dramatic impact around the world, with some communities facing harsher outcomes than others. We sought to understand how counties in the state of South Dakota (SD) fared compared to expected based on a reference population and what factors contributed to negative outcomes from the pandemic in SD.MethodsThe Standardized Incidence Ratios (SIR) of all counties, using age-adjusted and crude adjusted hospitalization and death rates were computed using the SD age-adjusted rate as a reference population. In addition, a penalized generalized linear regression model was used to identify factors that are associated with COVID-19 hospitalization and death rates. This model was then used to compute a new SIR after controlling for other socio-demographic and -economic factors.ResultsWe identified counties that had more or less severe outcomes than what would be expected based on the rate of SD after age adjustment. Additionally, race, education, and testing rate were some of the significant factors associated with the outcome. The SIR values after controlling for these additional factors showed change in magnitude from the range of 4 times more severe to 1.5 times more severe out-come than what is expected. Interestingly the lower end of this interval did not have a major change.ConclusionThe age adjusted SIR model used in this study allowed for the identification of counties with more or less severe than what is expected based on the state rate. These counties tended to be those with high nonwhite percentage, which mostly included counties with American Indian reservations. Although several predictors are associated with hospitalization and deaths, the penalized model confirmed what is already reported in literature that race and education level have a very high association with the outcome variables. As can be expected the further adjusted SIR mostly changed in those counties with higher than expected outcomes. We believe that these results may provide useful information to improve the implementation of mitigation strategies to curb the damage of this or future pandemics by providing a way for data-driven resource allocation.

THE PUSHOUT STRENGTH OF CONCRETE PAVEMENT SLAB AND CLAY SOIL LAYERS

The frictional forces between the concrete slab and base has been combined with the movements of the horizontal slab that have been induced by variations of the moisture and temperature in concrete slabs. The frictional drag that acts on the slab bottom as a result of base friction is in an opposite horizontal slab displacement direction, and resist movements of the horizontal slab. A condition of smoother interface provides lower resistance to slab movement. On the other hand, rough interfaces are beneficial in the reduction of the load-related stresses. As bonding degree between slab and foundation affects the friction that has been mobilized at interface, a realistic evaluation of friction of the interface is required for the rational designs of the concrete pavement. In this work, push-off test has been performed. Based upon results of the friction tests, the friction characteristics of concrete and soil have been researched. The parameters that influence the maximal displacement and friction coefficient are (interface state, rate of movement) for friction and (rate of movement, interface condition) for the displacements, respectively. Finally, once the applied force reaches a stable state, the frictional force increases dramatically. The most important influence on this force is the interface state, which is accompanied by movement rate. The change of the interface from a smooth to a rough surface increases the overall coefficient of friction.

Inelastic rate coefficients for collisions of C4H− with H2

Carbon-chain anions were recently detected in the interstellar medium. These very reactive species are used as tracers of the physical and chemical conditions in a variety of astrophysical environments. However, the Local Thermodynamical Equilibrium conditions are generally not fulfilled in these environments. Therefore, collisional as well as radiative rates are needed to accurately model the observed emission lines. We determine in this work the state-to-state rate coefficients of C4H− in collision with both ortho- and para-H2. A new ab initio 4D potential energy surface was computed using explicitly-correlated coupled cluster procedures. This surface was then employed to determine rotational excitation and de-excitation cross sections and rate coefficients for the first 21 rotational levels (up to rotational level j1 = 20) using the close-coupling method, while the coupled-state approximation was used to extend the calculations up to j1 = 30. State-to-state rate coefficients were obtained for the temperature range 2–100 K. The differences between the ortho- and para-H2 rate coefficients are found to be small.

Resolved fine and hyperfine state-to-state rate coefficients for the rotational transitions of C3N induced by collision with He

The fine and hyperfine resolved state-to-state rate coefficients for the rotational (de)excitation of C3N by collision with helium are computed. To this aim a two dimensional potential energy surface is calculated for this system. The recoupling method is used to obtain the fine and hyperfine structure resolved rate coefficients from spin-free Close Coupling calculations. These results are compared with those given by the Infinite Order Sudden Approximation and the M-randomizing Limit. General propensity rules for the transitions are also found and analyzed.

Amplification characteristics in active tapered segmented cladding fiber with large mode area

A kind of tapered segmented cladding fiber (T-SCF) with large mode area (LMA) is proposed, and the mode and amplification characteristics of T-SCFs with concave, linear, and convex tapered structures are investigated based on finite-element method (FEM) and few-mode steady-state rate equation. Simulation results indicate that the concave tapered structure can introduce high loss for high-order modes (HOMs) that is advantageous to achieve single-mode operation, whereas the convex tapered structure provides large effective mode area that can help to mitigate nonlinear effects. Meanwhile, the small-to-large amplification scheme shows further advantages on stripping off HOMs, and the large-to-small amplification scheme decreases the heat load density induced by the high-power pump. Moreover, single-mode propagation performance, effective mode area, and heat load density of the T-SCF are superior to those of tapered step index fiber (T-SIF). These theoretical model and numerical results can provide instructive suggestions for designing high-power fiber lasers and amplifiers.

The Natural Rate of Interest and the Optimal Rate of Interest in the Steady State

The “natural rate of interest” is the hypothetical, risk-free real rate of interest that would obtain in a closed economy, if net public debt were zero. It is considerably less than the optimal steady-state rate of interest, which is equal to the system’s growth rate. This holds for a very general “meta-model.” The fundamental equation of capital theory holds on the optimal steady-state path: T = Z − D, where T is the overall economic period of production, Z is the representative private “waiting period” of consumers and D is the public debt ratio. Prosperity is at least 30% lower at the natural rate of interest than at the optimal rate.