Wave Chaos in Elastodynamic Cavity Scattering

The exact elastodynamic scattering theory is constructed to describe the spectral properties of two- and more-cylindrical cavity systems, and compared to an elastodynamic generalization of the semi-classical Gutzwiller unstable periodic orbits formulas. In contrast to quantum mechanics, complex periodic orbits associated with the surface Rayleigh waves dominate the low-frequency spectrum, and already the two-cavity system displays chaotic features.Comment: 7 pages, 5 eps figures, latex (with epl.cls

On the regional variability of dB/dt and its significance to GIC

Faraday's law of induction is responsible for setting up a geoelectric field due to the variations in the geomagnetic field caused by ionospheric currents. This drives geomagnetically induced currents (GICs) which flow in large ground‐based technological infrastructure such as high‐voltage power lines. The geoelectric field is often a localized phenomenon exhibiting significant variations over spatial scales of only hundreds of kilometers. This is due to the complex spatiotemporal behavior of electrical currents flowing in the ionosphere and/or large gradients in the ground conductivity due to highly structured local geological properties. Over some regions, and during large storms, both of these effects become significant. In this study, we quantify the regional variability of dB/dt using closely placed IMAGE stations in northern Fennoscandia. The dependency between regional variability, solar wind conditions, and geomagnetic indices are also investigated. Finally, we assess the significance of spatial geomagnetic variations to modeling GICs across a transmission line. Key results from this study are as follows: (1) Regional geomagnetic disturbances are important in modeling GIC during strong storms; (2) dB/dt can vary by several times up to a factor of three compared to the spatial average; (3) dB/dt and its regional variation is coupled to the energy deposited into the magnetosphere; and (4) regional variability can be more accurately captured and predicted from a local index as opposed to a global one. These results demonstrate the need for denser magnetometer networks at high latitudes where transmission lines extending hundreds of kilometers are present

Neurocognitive Functions in 3- to 15-Year-Old Children : An International Comparison

Objectives: Performance on neurocognitive tasks develops with age, but it is still unknown whether this performance differs between children from different cultures. We compared cross-sectionally the development of neurocognitive functions in 3- to 15-year-old children from three countries: Finland, Italy, and the United States (N=2745). Methods: Language, face memory, emotion recognition, theory of mind, and visuospatial processing subtests from the NEPSY-II standardizations in Finland, Italy, and the United States were used to evaluate if children and adolescents from different linguistic and cultural backgrounds differ in performance on these measures. Results: We found significant differences in performance on the tasks between the countries. Generally, the differences were more pronounced in the younger age groups. Some subtests showed greater country effects than others, performance on these subtests being higher, in general, in one country over the others, or showed different patterns of age associated changes in test performance. Conclusions: Significant differences in neurocognitive performance between children from Finland, Italy, and the United States were found. These findings may be due to cultural or educational differences that impact test performance, or due to factors associated with the adaptation of measures from one culture to another. The finding of performance differences across countries on similar tasks indicate that cross-cultural and background variables impact performance on neuropsychological measures. Therefore, clinicians need to consider a child’s cultural background when evaluating performance on neuropsychological assessments. The results also indicate that future cross-cultural studies are needed to further examine the underlying cultural factors that influence neurocognitive performance. (JINS, 2017, 23, 1–14)Objectives: Performance on neurocognitive tasks develops with age, but it is still unknown whether this performance differs between children from different cultures. We compared cross-sectionally the development of neurocognitive functions in 3- to 15-year-old children from three countries: Finland, Italy, and the United States (N = 2745). Methods: Language, face memory, emotion recognition, theory of mind, and visuospatial processing subtests from the NEPSY-II standardizations in Finland, Italy, and the United States were used to evaluate if children and adolescents from different linguistic and cultural backgrounds differ in performance on these measures. Results: We found significant differences in performance on the tasks between the countries. Generally, the differences were more pronounced in the younger age groups. Some subtests showed greater country effects than others, performance on these subtests being higher, in general, in one country over the others, or showed different patterns of age associated changes in test performance. Conclusions: Significant differences in neurocognitive performance between children from Finland, Italy, and the United States were found. These findings may be due to cultural or educational differences that impact test performance, or due to factors associated with the adaptation of measures from one culture to another. The finding of performance differences across countries on similar tasks indicate that cross-cultural and background variables impact performance on neuropsychological measures. Therefore, clinicians need to consider a child's cultural background when evaluating performance on neuropsychological assessments. The results also indicate that future cross-cultural studies are needed to further examine the underlying cultural factors that influence neurocognitive performance.Peer reviewe

Neurocognitive Functions in 3- to 15-Year-Old Children : An International Comparison

Objectives: Performance on neurocognitive tasks develops with age, but it is still unknown whether this performance differs between children from different cultures. We compared cross-sectionally the development of neurocognitive functions in 3- to 15-year-old children from three countries: Finland, Italy, and the United States (N=2745). Methods: Language, face memory, emotion recognition, theory of mind, and visuospatial processing subtests from the NEPSY-II standardizations in Finland, Italy, and the United States were used to evaluate if children and adolescents from different linguistic and cultural backgrounds differ in performance on these measures. Results: We found significant differences in performance on the tasks between the countries. Generally, the differences were more pronounced in the younger age groups. Some subtests showed greater country effects than others, performance on these subtests being higher, in general, in one country over the others, or showed different patterns of age associated changes in test performance. Conclusions: Significant differences in neurocognitive performance between children from Finland, Italy, and the United States were found. These findings may be due to cultural or educational differences that impact test performance, or due to factors associated with the adaptation of measures from one culture to another. The finding of performance differences across countries on similar tasks indicate that cross-cultural and background variables impact performance on neuropsychological measures. Therefore, clinicians need to consider a child’s cultural background when evaluating performance on neuropsychological assessments. The results also indicate that future cross-cultural studies are needed to further examine the underlying cultural factors that influence neurocognitive performance. (JINS, 2017, 23, 1–14)Objectives: Performance on neurocognitive tasks develops with age, but it is still unknown whether this performance differs between children from different cultures. We compared cross-sectionally the development of neurocognitive functions in 3- to 15-year-old children from three countries: Finland, Italy, and the United States (N = 2745). Methods: Language, face memory, emotion recognition, theory of mind, and visuospatial processing subtests from the NEPSY-II standardizations in Finland, Italy, and the United States were used to evaluate if children and adolescents from different linguistic and cultural backgrounds differ in performance on these measures. Results: We found significant differences in performance on the tasks between the countries. Generally, the differences were more pronounced in the younger age groups. Some subtests showed greater country effects than others, performance on these subtests being higher, in general, in one country over the others, or showed different patterns of age associated changes in test performance. Conclusions: Significant differences in neurocognitive performance between children from Finland, Italy, and the United States were found. These findings may be due to cultural or educational differences that impact test performance, or due to factors associated with the adaptation of measures from one culture to another. The finding of performance differences across countries on similar tasks indicate that cross-cultural and background variables impact performance on neuropsychological measures. Therefore, clinicians need to consider a child's cultural background when evaluating performance on neuropsychological assessments. The results also indicate that future cross-cultural studies are needed to further examine the underlying cultural factors that influence neurocognitive performance.Peer reviewe

Geometrical theory of diffraction and spectral statistics

We investigate the influence of diffraction on the statistics of energy levels in quantum systems with a chaotic classical limit. By applying the geometrical theory of diffraction we show that diffraction on singularities of the potential can lead to modifications in semiclassical approximations for spectral statistics that persist in the semiclassical limit $\hbar \to 0$. This result is obtained by deriving a classical sum rule for trajectories that connect two points in coordinate space.Comment: 14 pages, no figure, to appear in J. Phys.

Periodic Orbit Quantization beyond Semiclassics

A quantum generalization of the semiclassical theory of Gutzwiller is given. The new formulation leads to systematic orbit-by-orbit inclusion of higher $\hbar$ contributions to the spectral determinant. We apply the theory to billiard systems, and compare the periodic orbit quantization including the first $\hbar$ contribution to the exact quantum mechanical results.Comment: revte

Emerging organic compounds in European groundwater

In Europe, emerging organic compounds (EOCs) in groundwater is a growing research area. Prioritisation for monitoring EOCs was formalised in 2019 in Europe through the development of the first voluntary groundwater watch list (GWWL). Despite this, groundwater occurrence data in the peer reviewed literature for Europe has not been reviewed to date. Questions surrounding the effect, toxicity, movement in the subsurface and unsaturated zone make the process of regulating EOC use difficult. The aim in Europe is to develop a unified strategy for the classification, and prioritisation of EOCs to be monitored in groundwater. This paper compiles evidence from the recent published studies from across Europe, since 2012 when the last major literature global review of EOCs in groundwater took place. A total of 39 studies were identified for review based on specific selection criteria (geography, publication date, sample size>10, inclusion of EOCs data). Data on specific compounds, and associated meta-data are compiled and reviewed. The two most frequently detected EOCs, carbamazepine and caffeine, occurred in groundwater at concentrations of up to 2.3 and 14.8 μg/L, respectively

The DNA polymerase of bacteriophage YerA41 replicates its T-modified DNA in a primer-independent manner

Yersinia phage YerA41 is morphologically similar to jumbo bacteriophages. The isolated genomic material of YerA41 could not be digested by restriction enzymes, and used as a template by conventional DNA polymerases. Nucleoside analysis of the YerA41 genomic material, carried out to find out whether this was due to modified nucleotides, revealed the presence of a ca 1 kDa substitution of thymidine with apparent oligosaccharide character. We identified and purified the phage DNA polymerase (DNAP) that could replicate the YerA41 genomic DNA even without added primers. Cryo-electron microscopy (EM) was used to characterize structural details of the phage particle. The storage capacity of the 131 nm diameter head was calculated to accommodate a significantly longer genome than that of the 145 577 bp genomic DNA of YerA41 determined here. Indeed, cryo-EM revealed, in contrast to the 25 angstrom in other phages, spacings of 33-36 angstrom between shells of the genomic material inside YerA41 heads suggesting that the heavily substituted thymidine increases significantly the spacing of the DNA packaged inside the capsid. In conclusion, YerA41 appears to be an unconventional phage that packages thymidine-modified genomic DNA into its capsids along with its own DNAP that has the ability to replicate the genome.Peer reviewe

Edge Diffraction, Trace Formulae and the Cardioid Billiard

We study the effect of edge diffraction on the semiclassical analysis of two dimensional quantum systems by deriving a trace formula which incorporates paths hitting any number of vertices embedded in an arbitrary potential. This formula is used to study the cardioid billiard, which has a single vertex. The formula works well for most of the short orbits we analyzed but fails for a few diffractive orbits due to a breakdown in the formalism for certain geometries. We extend the symbolic dynamics to account for diffractive orbits and use it to show that in the presence of parity symmetry the trace formula decomposes in an elegant manner such that for the cardioid billiard the diffractive orbits have no effect on the odd spectrum. Including diffractive orbits helps resolve peaks in the density of even states but does not appear to affect their positions. An analysis of the level statistics shows no significant difference between spectra with and without diffraction.Comment: 25 pages, 12 Postscript figures. Published versio