When can we compute analytically lookback time, age of the universe, and luminosity distance?

In Friedmann-Lemaître-Robertson-Walker cosmology, it is sometimes possible to compute analytically lookback time, age of the universe, and luminosity distance versus redshift, expressing them in terms of a finite number of elementary functions. We classify these situations using the Chebyshev theorem of integration and providing examples.

DOSIMETRIC CHARACTERISATION OF A SUB-NATURAL BACKGROUND RADIATION ENVIRONMENT FOR RADIOBIOLOGY INVESTIGATIONS.

Living systems have evolved in the presence of naturally occurring ionising radiation. REPAIR is a research project investigating the biological effects of sub-natural background radiation exposure in SNOLAB, a deep-underground laboratory. Biological systems are being cultured within a sub-background environment as well as two control locations (underground and surface). A comprehensive dosimetric analysis was performed. GEANT4 simulation was used to characterise the contribution from gamma, muons and neutrons. Additionally, dose rates from radon, 40K and 14C were calculated based on measured activity concentrations. The total absorbed dose rate in the sub-background environment was 27 times lower than the surface control, at 2.48 ± 0.20 nGy hr-1, including a >400-fold reduction in the high linear energy transfer components. This modelling quantitatively confirms that the environment within SNOLAB provides a substantially reduced background radiation dose rate, thereby setting the stage for future sub-background biological studies using a variety of model organisms.

Model-based estimation of baseball batting metrics.

We introduce an approach to model the batting outcomes of baseball batters based on the weighted likelihood approach and make use of our methodology to estimate commonly used baseball batting metrics. The weighted likelihood allows the sharing of relevant information among players. Specifically, this allows the inference on each batter to make use of the batting data from all other players in the league and, in the process, allows for improved inference. MAMSE (Minimum Averaged Mean Squared Error) weights are used as the likelihood weights. For comparison, we implemented a semi-parametric Bayesian approach based on the Dirichlet process, which enables the borrowing of information across batters while providing a natural clustering mechanism. We demonstrate and compare these approaches using 2018 Major League Baseball (MLB) batters data.

Structurally Related Edaravone Analogues: Synthesis, Antiradical, Antioxidant, and Copper-Chelating Properties.

BACKGROUND: The current therapeutic options available to patients diagnosed with Amyotrophic Lateral Sclerosis (ALS) are limited and edaravone is a compound that has gained significant interest for its therapeutic potential in this condition. OBJECTIVES: The current work was thus undertaken to synthesize and characterize a series of edaravone analogues. METHODS: A total of 17 analogues were synthesized and characterized for their antioxidant properties, radical scavenging potential and copper-chelating capabilities. RESULTS: Radical scavenging and copper-chelating properties were notably observed for edaravone. Analogues bearing hydrogen in position 1 and a phenyl at position 3 and a phenyl in both positions of pyrazol-5 (4H)-one displayed substantial radical scavenging, antioxidants and copper-chelating properties. High accessibility of electronegative groups combined with higher electronegativity and partial charge of the carbonyl moiety in edaravone might explain the observed difference in the activity of edaravone relative to the closely related analogues 6 and 7 bearing hydrogen at position 1 and a phenyl at position 3 (6) and a phenyl in both positions (7). CONCLUSION: Overall, this study reveals a subset of edaravone analogues with interesting properties. Further investigation of these compounds is foreseen in relevant models of oxidative stress-associated diseases in order to assess their therapeutic potential in such conditions.

Three-dimensional-printed membrane-type acoustic metamaterial for low frequency sound attenuation.

Membrane-type acoustic metamaterials have received much attention for low-frequency sound manipulation, especially in the form of decorated membrane resonators. In this paper, such resonators are obtained using fused deposition modeling. Beyond the practical aspects provided by this manufacturing method, the low density of the flexible filament used increases their effectiveness. Indeed, the mass usually added to the membrane center can easily be divided into several disjoint elements. Using rotary inertia of the added structures, new peaks of efficiency in both absorption and normal transmission loss appear when compared to usual decorated membrane resonators.

Numerical analysis of eigenproblem for cavities by a particular integral method with a low frequency approximation of surface admittance.

In this paper, a three-dimensional boundary element method for the eigenanalysis of complex-shaped cavity is presented. A particular integral method is proposed with general absorbing boundary conditions, well suited for determination of the lower modes. In this approach, a polynomial approximation of surface admittance is used with a recent class of compactly supported radial basis function. Two common absorbent models are employed in order to demonstrate the relevance of high-order approximation of the admittance. Resulting eigenproblems of several orders (linear to cubic) are thus performed on basic geometries and a car interior. Results show significant improvements for the computed damped eigenfrequencies and the associated modal reverberation time while using an approximation polynomial matching the surface admittance variation order.

Thickness or phase velocity measurements using the Green's function comparison method.

The acoustic guided wave propagation for plate thickness measurement is generally treated in free space to simplify the formal approach. In this paper, propagation in a closed environment is treated by dealing with plates of finite dimensions and arbitrary geometries and linear boundary conditions. The present approach considers the plate Green's function to be composed of two terms. The first term corresponds to the Green's function of an infinite plate. The second term corresponds to a correction term which, in addition to the first term, satisfies all equations. Assuming the boundary conditions to be linear, it is found that the acoustic wave generated by a point source is proportional to that of a circular array of sources centered on it. By measuring the ratio between the two signals, either the plate velocity or plate thickness can be determined. This new method has been successfully applied to isotropic and anisotropic homogeneous plates of different geometries, on inhomogeneous plates, and also in a passive mode, without an active transmitter.

Measurement of thickness or plate velocity using ambient vibrations.

Assuming the Green's function is linear with respect to the boundary conditions, it is demonstrated that flexural waves detected by a point receiver and a circular array of point receivers centered on the previous receiver are proportional regardless location of the source and geometry of the plate. Therefore determination of plate velocity or thickness is done from the measurement of ambient vibrations without using any emitter. Experimental results obtained with a plate of non regular geometry excited with a single transducer or a remote loudspeaker are shown to verify the theoretical approach.