We compute all the massless bosonic three-point and four-point tree amplitudes for the string model of Bluhm, Dolan, and Goddard. These amplitudes are then used to construct the bosonic effective Lagrangians that describe the dynamics of the theory at low energy. These effective Lagrangians are exact up to the quartic interaction terms in field variables, and are significantly different from those for the four-dimensional heterotic string model.
We find plane-fronted torsion waves propagating in the metrically flat spacetime in a gravitational gauge theory formulated in a Riemann-Cartan spacetime with Lagrangian ${R}_{\mathrm{ij}}{R}^{\mathrm{ij}}\ensuremath{-}\frac{1}{3}{R}^{2}$.
The ionospheric features of traveling atmospheric disturbances (TADs) over the Western Pacific region have been observed by the Wuhan, NCU‐DPS, and Cebu ionosondes and the ROCSAT‐1 satellite during the 6–7 April 2000 magnetic storm. The nighttime observations are further compared with the simulation results of the Thermosphere‐Ionosphere Electrodynamics General Circulation Model (TIEGCM). Both observation and model demonstrate that the TADs propagate equatorward with a phase speed of 610–650 m/s. The observations and corresponding TIEGCM simulations show a negative initial correlation between NmF 2 and HmF 2 caused by equatorward wind surges at various locations from midlatitudes to the equator. These qualitative agreements reveal that the TIEGCM is capable of simulating the TADs. The TIEGCM simulations of two locations located in the downwind hemisphere further show decreases in NmF 2 and HmF 2 mainly due to the enhanced transequatorial winds. After lowering the F 2 layer at the two locations, the HmF 2 is raised for several hours and shows slightly enhanced NmF 2 daytime values while the meridional wind is at background magnitude. We propose that this effect is caused by accumulation of plasma transported from northern latitudes. However, we also find that the NmF 2 , HmF 2 , and the lifetimes of HmF 2 uplift phase and equatorial vertical drift in the model results are quantitatively inconsistent with that in the observed data.
In this research, a ray tracing model is built up to simulate the propagation of signal in global positioning system (GPS) radio occultation (RO) mission. When GPS signal propagate through the Earth's atmosphere, it will be bent and delayed due to the gradient atmosphere refractive index and received by low Earth orbit (LEO) satellite. Then the parameter profiles of atmosphere can be retrieved by using the received signal. In the previous research, in order to simplify the simulation, the Earth's atmosphere is assumed as spherical symmetry and the positions of GPS and LEO satellites are not considered in simulations. In the model, the shape of the Earth is assumed as an ellipse. The information of European Centre for Medium-Range Weather Forecasts (ECMWF) is used to construct the refractive index of Earth's atmosphere. And two aiming algorithm are developed to control the initial propagating direction of GPS signal to begin from the prescribed GPS satellite position and end at the LEO satellite position. The model is tested and verified by comparing with analytical and observational data.
We have studied all the massless three-point and massless four-point tree amplitudes of the Bluhm-Dolan-Goddard string model, now including the fermions. In our study, we have decomposed the ten-dimensional spinors into four families of four-dimensional Majorana spinors. With these four-dimensional spinors, we are able to write the effective Lagrangians, inferred from the low-energy limit of the string amplitudes, in terms of four-dimensional fermionic fields. In this four-dimensional form, the Lagrangians contain terms that will describe conventional supergravity within the same family. There will also be interfamily interactions mediated by the neutral vectors and gauge scalars.
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