48,726 research outputs found
Regional mapping of the crustal structure in southern California from receiver functions
Lateral variations of the crustal structure in southern California are determined from receiver function (RF) studies using data from the Southern California Seismic Network broadband stations and Los Angeles Regional Seismic Experiment surveys. The results include crustal thickness estimates at the stations themselves, and where possible, cross sections are drawn. The large-scale Moho depth variation pattern generally correlates well with the current status of the Mesozoic batholith: Deep Moho of 35–39 km is observed beneath the western Peninsula Ranges, Sierra Nevada, and San Bernardino Mountains, where the batholith is relatively intact, and shallow Moho of 26–32 km is observed in the Mojave Desert, where the batholith is highly deformed and disrupted. High-resolution lateral variations of the crustal structure for individual geographic provinces are investigated, and distinctive features are identified. The crustal structure is strongly heterogeneous beneath the central Transverse Ranges, and deep Moho of 36–39 km is locally observed beneath several station groups in the western San Gabriel Mountains. Moho is relatively flat and smooth beneath the western Mojave Desert but gets shallower and complicated to the east. Anomalous RFs are observed at two stations in the eastern Mojave Desert, where a Moho step of ∼8–10 km is found between the NW and SE back-azimuthal groups of station DAN in the Fenner Valley. Asymmetric extension of the Salton Trough is inferred from the Moho geometry. Depth extension of several major faults, such as the San Andreas Fault and San Gabriel Fault, to the Moho is inferred
To mesh or not to mesh: flexible wireless indoor communication among mobile robots in industrial environments
Mobile robots such as automated guided vehicles become increasingly important in industry as they can greatly increase efficiency. For their operation such robots must rely on wireless communication, typically realized by connecting them to an existing enterprise network. In this paper we motivate that such an approach is not always economically viable or might result in performance issues. Therefore we propose a flexible and configurable mixed architecture that leverages on mesh capabilities whenever appropriate. Through experiments on a wireless testbed for a variety of scenarios, we analyse the impact of roaming, mobility and traffic separation and demonstrate the potential of our approach
Spin transfer torque enhancement in dual spin valve in the ballistic regime
The spin transfer torque in all-metal dual spin valve, in which two
antiparallelly aligned pinned ferromagnetic layers are on the two sides of a
free ferromagnetic layer with two thin nonmagnetic spacers in between, is
studied in the ballistic regime. It is argued that, similar to the results in
the diffusion regime, the spin transfer torque is dramatically enhanced in
comparison to that in a conventional spin valve although no spin accumulation
exists at the magnetic-nonmagnetic interfaces. Within the Slonczewski's
approach, an analytical expression of the torque on the free magnetic layer is
obtained, which may serve as a theoretical model for the micromagnetic
simulation of the spin dynamics in dual spin valve. Depending on the
orientation of free layer and the degree of electron polarization, the spin
transfer torque enhancement could be tens times. The general cases when
transmission and reflection probabilities of free layer are different from zero
or one are also numerically calculated.Comment: 8 pages, 5 figure
Palmatine inhibits TRIF-dependent NF-kB pathway against inflammation induced by LPS in goat endometrial epithelial cells
A two component jet model for the X-ray afterglow flat segment in short GRB 051221A
In the double neutron star merger or neutron star-black hole merger model for
short GRBs, the outflow launched might be mildly magnetized and neutron rich.
The magnetized neutron-rich outflow will be accelerated by the magnetic and
thermal pressure and may form a two component jet finally, as suggested by
Vlahakis, Peng & K\"{o}nigl (2003). We show in this work that such a two
component jet model could well reproduce the multi-wavelength afterglow
lightcurves, in particular the X-ray flat segment, of short GRB 051221A. In
this model, the central engine need not to be active much longer than the
prompt ray emission.Comment: 11 pages, 2 figure; Accepted for publication by ApJ
The optimally-sampled galaxy-wide stellar initial mass function - Observational tests and the publicly available GalIMF code
Here we present a full description of the integrated galaxy-wide initial mass
function (IGIMF) theory in terms of the optimal sampling and compare it with
available observations. Optimal sampling is the method we use to discretize the
IMF into stellar masses deterministically. Evidence has been indicating that
nature may be closer to deterministic sampling as observations suggest a
smaller scatter of various relevant observables than random sampling would
give, which may result from a high level of self-regulation during the star
formation process. The variation of the IGIMFs under various assumptions are
documented. The results of the IGIMF theory are consistent with the empirical
relation between the total mass of a star cluster and the mass of its most
massive star, and the empirical relation between a galaxy's star formation rate
(SFR) and the mass of its most massive cluster. Particularly, we note a natural
agreement with the empirical relation between the IMF's power-law index and a
galaxy's SFR. The IGIMF also results in a relation between the galaxy's SFR and
the mass of its most massive star such that, if there were no binaries,
galaxies with SFR M/yr should host no Type II supernova
events. In addition, a specific list of initial stellar masses can be useful in
numerical simulations of stellar systems. For the first time, we show
optimally-sampled galaxy-wide IMFs (OSGIMF) which mimics the IGIMF with an
additional serrated feature. Finally, A Python module, GalIMF, is provided
allowing the calculation of the IGIMF and OSGIMF in dependence on the
galaxy-wide SFR and metallicity.Comment: 15 pages, 15 figures, A&A, in press; paper remains unchanged
(version1 equals version2); the GalIMF module is downloadable at githu
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