7,358 research outputs found
On non-vanishing of twisted symmetric and exterior square L-functions for GL(n)
Let π be a cuspidal representation of GLn(AF), where AF is the ring of adeles of a number field F
Arthur Packets and the Ramanujan Conjecture
The purpose of this paper is to show that under a part of generalized
Arthur's A-packet conjecture, locally generic cuspidal automorphic
representations of a quasisplit group over a number field are of Ramanujan
type, i.e., are tempered at almost all places. The A-packet conjecture allows
one to reduce the problem to a special case of a general local question about
the components of the corresponding Langlands L-packet which is then answered
here in its generality
Cosmology of a higher derivative scalar theory with non-minimal Maxwell coupling
Higher derivative scalar field theory in curved space-time belongs to the
GLPV theory coupled non-minimally to the Maxwell field is considered. We will
show that the theory admits two independent exact de Sitter solutions in the
FRW background, one driven by the cosmological constant and the other by the
GLPV scalar field. The dynamical system analysis of the theory shows that these
two exact solutions are stable fixed points. Also, cosmological perturbations
over these solutions shows that the cosmological constant based solution is
healthy at linear level but the GLPV based solution suffers from a gradient
instability in the scalar sector. This proves that the cosmological constant is
needed in the GLPV-Maxwell system in order to have a healthy de Sitter
solution.Comment: 16 page
Space Communications Artificial Intelligence for Link Evaluation Terminal (SCAILET)
A software application to assis end-users of the Link Evaluation Terminal (LET) for satellite communication is being developed. This software application incorporates artificial intelligence (AI) techniques and will be deployed as an interface to LET. The high burst rate (HBR) LET provides 30 GHz transmitting/20 GHz receiving, 220/110 Mbps capability for wideband communications technology experiments with the Advanced Communications Technology Satellite (ACTS). The HBR LET and ACTS are being developed at the NASA Lewis Research Center. The HBR LET can monitor and evaluate the integrity of the HBR communications uplink and downlink to the ACTS satellite. The uplink HBR transmission is performed by bursting the bit-pattern as a modulated signal to the satellite. By comparing the transmitted bit pattern with the received bit pattern, HBR LET can determine the bit error rate BER) under various atmospheric conditions. An algorithm for power augmentation is applied to enhance the system's BER performance at reduced signal strength caused by adverse conditions. Programming scripts, defined by the design engineer, set up the HBR LET terminal by programming subsystem devices through IEEE488 interfaces. However, the scripts are difficult to use, require a steep learning curve, are cryptic, and are hard to maintain. The combination of the learning curve and the complexities involved with editing the script files may discourage end-users from utilizing the full capabilities of the HBR LET system. An intelligent assistant component of SCAILET that addresses critical end-user needs in the programming of the HBR LET system as anticipated by its developers is described. A close look is taken at the various steps involved in writing ECM software for a C&P, computer and at how the intelligent assistant improves the HBR LET system and enhances the end-user's ability to perform the experiments
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