Forward Modeling of Transducer Misalignment Effects in Ultrasonic Leaky Wave Measurements

Ultrasonic measurements performed with a pair of acoustic transducers in pitch-catch mode are of common use in the NDE field. In particular, for nearfield leaky wave (LW) measurements which are directed at precise determination of material properties of layered elastic structure in immersion. In LW measurements, the acoustic transducer beams are aligned at angles so as to phase match to one or several of the structure’s leaky (Rayleigh or Lamb) waves. The amplitude and phase of the scattered acoustic energy collected, and converted to an electrical voltage, by the phase-sensitive receiving transducer depends not only on the properties of the structure but also on the parameters of the transducers used, in particular, their apertures and alignment angles. Transducer alignment issues are especially important for transducers that radiate or receive over a narrow angular range

Gamma Rays from Star Formation in Clusters of Galaxies

Star formation in galaxies is observed to be associated with gamma-ray emission. The detection of gamma rays from star-forming galaxies by the Fermi Large Area Telescope (LAT) has allowed the determination of a functional relationship between star formation rate and gamma-ray luminosity (Ackermann et. al. 2012). Since star formation is known to scale with total infrared (8-1000 micrometers) and radio (1.4 GHz) luminosity, the observed infrared and radio emission from a star-forming galaxy can be used to quantitatively infer the galaxy's gamma-ray luminosity. Similarly, star forming galaxies within galaxy clusters allow us to derive lower limits on the gamma-ray emission from clusters, which have not yet been conclusively detected in gamma rays. In this study we apply the relationships between gamma-ray luminosity and radio and IR luminosities derived in Ackermann et. al. 2012 to a sample of galaxy clusters from Ackermann et. al. 2010 in order to place lower limits on the gamma-ray emission associated with star formation in galaxy clusters. We find that several clusters have predicted lower limits on gamma-ray emission that are within an order of magnitude of the upper limits derived in Ackermann et. al. 2010 based on non-detection by Fermi-LAT. Given the current gamma-ray limits, star formation likely plays a significant role in the gamma-ray emission in some clusters, especially those with cool cores. We predict that both Fermi-LAT over the course of its lifetime and the future Cherenkov Telescope Array will be able to detect gamma-ray emission from star-forming galaxies in clusters.Comment: 17 pages, 2 figures, 2 tables. Minor revisions made to match version accepted to Ap

Co-Variation of Tonality in the Music and Speech of Different Cultures

Whereas the use of discrete pitch intervals is characteristic of most musical traditions, the size of the intervals and the way in which they are used is culturally specific. Here we examine the hypothesis that these differences arise because of a link between the tonal characteristics of a culture's music and its speech. We tested this idea by comparing pitch intervals in the traditional music of three tone language cultures (Chinese, Thai and Vietnamese) and three non-tone language cultures (American, French and German) with pitch intervals between voiced speech segments. Changes in pitch direction occur more frequently and pitch intervals are larger in the music of tone compared to non-tone language cultures. More frequent changes in pitch direction and larger pitch intervals are also apparent in the speech of tone compared to non-tone language cultures. These observations suggest that the different tonal preferences apparent in music across cultures are closely related to the differences in the tonal characteristics of voiced speech

The Social-Safety System: Fortifying Relationships in the Face of the Unforeseeable

A model of the social-safety system is proposed to explain how people sustain a sense of safety in the relational world when they are not able to foresee the behavior of others. In this model, people can escape the acute anxiety posed by agents in their personal relational world behaving unexpectedly (e.g., spouse, child) by defensively imposing well-intentioned motivations on the agents controlling their sociopolitical relational world (e.g., President, Congress). Conversely, people can escape the acute anxiety posed by sociopolitical agents behaving unexpectedly by defensively imposing well-intentioned motivations on the agents controlling their personal relational world. Two daily diary studies, a longitudinal study of the 2018 midterm election, and a 3-year longitudinal study of newlyweds supported the hypotheses. On a daily basis, people who were less certain they could trust their romantic partner defended against acutely unforeseeable behavior in one relational world by affirming faith in the well-intentioned motivations of agents in the alternate world. Moreover, when people were more in the personal daily habit of finding safety in the alternate relational world in the face of the unexpected, those who were initially uncertain they could trust their romantic partner later evidenced greater comfort depending on their personal relationship partners

Alu element mutation spectra: Molecular clocks and the effect of DNA methylation

In primate genomes more than 40% of CpG islands are found within repetitive elements. With more than one million copies in the human genome, the Alu family of retrotransposons represents the most successful short interspersed element (SINE) in primates and CpG dinucleotides make up about 20% of Alu sequences. It is generally thought that CpG dinucleotides mutate approximately ten times faster than other dinucleotides due to cytosine methylation and the subsequent deamination and conversion of C→T. However, the disparity of Alu subfamily age estimations based upon CpG or non-CpG substitution density indicates a more complex relationship between CpG and non-CpG substitutions within the Alu elements. Here we report an analysis of the mutation patterns for 5296 Alu elements comprising 20 subfamilies. Our results indicate a relatively constant CpG versus non-CpG substitution ratio of ∼6 for the young (AluY) and intermediate (AluS) Alu subfamilies. However, a more complex non-linear relationship between CpG and non-CpG substitutions was observed when old (AluJ) subfamilies were included in the analysis. These patterns may be the result of the slowdown of the neutral mutation rate during primate evolution and/or an increase in the CpG mutation rate as the consequence of increased DNA methylation in response to a burst of retrotransposition activity ∼35 million years ago. © 2004 Elsevier Ltd. All rights reserved

Different evolutionary fates of recently integrated human and chimpanzee LINE-1 retrotransposons

The long interspersed element-1 (LINE-1 or L1) is a highly successful retrotransposon in mammals. L1 elements have continued to actively propagate subsequent to the human-chimpanzee divergence, ∼ 6 million years ago, resulting in species-specific inserts. Here, we report a detailed characterization of chimpanzee-specific L1 subfamily diversity and a comparison with their human-specific counterparts. Our results indicate that L1 elements have experienced different evolutionary fates in humans and chimpanzees within the past ∼ 6 million years. Although the species-specific L1 copy numbers are on the same order in both species (1200-2000 copies), the number of retrotransposition-competent elements appears to be much higher in the human genome than in the chimpanzee genome. Also, while human L1 subfamilies belong to the same lineage, we identified two lineages of recently integrated L1 subfamilies in the chimpanzee genome. The two lineages seem to have coexisted for several million years, but only one shows evidence of expansion within the past three million years. These differential evolutionary paths may be the result of random variation, or the product of competition between L1 subfamily lineages. Our results suggest that the coexistence of several L1 subfamily lineages within a species may be resolved in a very short evolutionary period of time, perhaps in just a few million years. Therefore, the chimpanzee genome constitutes an excellent model in which to analyze the evolutionary dynamics of L1 retrotransposons. © 2006 Elsevier B.V. All rights reserved