let $pounds$ be the category of locally compact abelian groups and $a,cin pounds$. in this paper, we define component extensions of $a$ by $c$ and show that the set of all component extensions of $a$ by $c$ forms a subgroup of $ext(c,a)$ whenever $a$ is a connected group. we establish conditions under which the component extensions split and determine lca groups which are component projective. ...

[1] A pulse-like disturbance traveling across the Los Angeles basin was observed on 12 October 2001 with seismographs of the TriNet network. This wave had a period of about 1000 s and a propagation speed of about 10 m/s, much slower than seismic waves. The seismograph data were compared with barograph data, and a good correlation was found so the wave was determined to be atmospheric in origin....

We show here that the standard physical model used by Vriend et al. to analyse seismograph data, namely a nondispersive bulk propagation, does not apply to the surface layer of sand dunes. According to several experimental, theoretical and field results, the only possible propagation of sound waves in a dry sand bed under gravity is through an infinite, yet discrete, number of dispersive surfac...

Abstract This paper presents the depth inversion of Rayleigh wave group velocity to obtain an S-wave model from seismic ambient noise cross-correlation in western Java, Indonesia. study utilizes vertical component data a temporary seismograph network deployed 2016, which was used previous estimate fundamental mode maps. In this study, Neighborhood Algorithm applied invert velocities into 1D she...