5,804 research outputs found
Importance of Sea Contribution to Nucleons
We studied the statistical model of nucleons consisting of sea having various
quark-gluon Fock states in addition to valence quarks. Using statistical
consideration and taking 86% of the total Fock states contributing to the low
energy properties of nucleon, we aim to find the contributions to these
properties coming from the scalar, vector and tensor sea. We checked its
validity against the assumption where the contributions from scalar and tensor
sea have been suppressed and justified to be unimportant. We took the
approximation that sea is getting a zero contribution from H_0 G_\bar10 and H_1
G_\bar10 in three gluon states. Under above considerations, the calculated
magnetic moment, spin distribution and weak decay coupling constant ratio for
proton and neutron states have been tabulated. We hereby confirm that the
suppression of the scalar and tensor sea leads to modification in the
parameters of the nucleons showing deviation from the experimental data.Comment: 13 pages, 5 figures, To be published in NP
Autonomous reconfigurable GPS/INS navigation and pointing system for rendezvous and docking
The briefing describes work using the Global Positioning System to determine position of spacecraft and the development of computer tools to utilize these position determinations to enable autonomous rendezvous. Using GPS data in conjunction with Inertial Navigation Systems (INS) provides the capability for absolute spacecraft navigation, navigation of one spacecraft relative to another, and attitude determination. Some results presented are based on limited observations, though simulation results are documented. A GPS/INS navigation flight experiment could provide a platform for evaluating approaches for autonomous operation and reconfigurability of the navigation and attitude determination subsystem for future space vehicles. Current emphasis is on the development and demonstration of an Onboard Mission Manager (OMM) and a Multi-Mode Navigation Kalman filter. Sensor data will be handed over to the OMM, which will determine the appropriate response and generate commands for the Kalman filter to use to reconfigure itself. Global Positioning System measurements and INS data will be processed in the integrated navigation filter and used to compute errors in position, velocity, and attitude. Inertial Navigation Systems instrument errors (biases, scale factors, etc.) also can be estimated. The OMM then will use a knowledge base to determine appropriate system response. The GPS is good for missions that have attitude pointing accuracy requirements within the 100 to 200 arcsecond range
Field dependent nilpotent symmetry for gauge theories
We construct the field dependent mixed BRST (combination of BRST and
anti-BRST) transformations for pure gauge theories. These are shown to be an
exact nilpotent symmetry of both the effective action as well as the generating
functional for certain choices of the field dependent parameters. We show that
the Jacobian contributions for path integral measure in the definition of
generating functional arising from BRST and anti-BRST part compensate each
other. The field dependent mixed BRST transformations are also considered in
field/antifield formulation to show that the solutions of quantum master
equation remain invariant under these. Our results are supported by several
explicit examples.Comment: 25 pages, No figures, Revte
Status of reaction theory for studying rare isotopes
Reactions are an important tool to study nuclear structure and for extracting
reactions relevant for astrophysics. In this paper we focus on deuteron induced
reactions which can provide information on neutron shell evolution as well as
neutron capture cross sections. We review recent work on the systematic
comparison of the continuum discretized coupled channel method, the adiabatic
wave approximation and the Faddeev momentum-space approach. We also explore
other aspects of the reaction mechanism and discuss in detail difficulties
encountered in the calculations.Comment: 7 pages, 5 figures, proceeding for HITES 201
An Innovative Approach for Modeling Crop Yield Response to Fertilizer Nutrients
Fertilizer recommendations seldom account for agro-climatic conditions, which are important factors that determine the response to fertilizer and the optimal rate of fertilizer. The nitrogen fertilizer response to open pollinated and hybrid canola types will also impact optimal nitrogen rates. This study used quantile regression to model canola yield response to nitrogen fertilizer. Quantile regression can apply different weights to the residuals, facilitating a response estimation where the agro-climatic conditions are not limiting and the yield response is due to the variable of interest. The economically optimal levels of fertilizers were calculated using the proposed and the conventional least squares procedures of the two canola types in western Canada. Results showed that the effects of nitrogen fertilizer on yield depended on the canola type and on the estimation procedure. Optimal levels of nitrogen for open-pollinated canola were estimated as 91, 115, and 134 kg ha-1 for severe, moderate and low levels of agro-climatic constraints. Hybrid had a higher yield potential, and also required more nitrogen fertilizer (137, 142, and 158 kg ha-1). Unlike conventional approach, proposed approach could benefit producer by recommending less (more) fertilizer when the crop response to fertilizer is expected to be low (high) due to agro-climatic conditions.Crop Production/Industries,
AN OPERATIONAL APPROACH FOR EVALUATING INVESTMENT RISK: AN APPLICATION TO THE NO-TILL TRANSITION
Roy’s safety-first rule is used to provide measures popular with farmers of short and long term business risk associated with various no-till transition strategies over an investment horizon. The short run rule provided more sensitivity to inter-year financial risk than other commonly used criteria. Results revealed that speed of adoption influenced the probability of successful transition more than did the sequence of drill acquisition methods. Higher equity and larger farms had a greater chance of transition success. Slow acreage expansion with a custom or rental drill reduces risk until a no-till yield penalty is eliminated.Investment risk, Monte Carlo simulation, no-till, rent- purchase, risk, safety-first, technology adoption, transition strategy
QIP = PSPACE
We prove that the complexity class QIP, which consists of all problems having
quantum interactive proof systems, is contained in PSPACE. This containment is
proved by applying a parallelized form of the matrix multiplicative weights
update method to a class of semidefinite programs that captures the
computational power of quantum interactive proofs. As the containment of PSPACE
in QIP follows immediately from the well-known equality IP = PSPACE, the
equality QIP = PSPACE follows.Comment: 21 pages; v2 includes corrections and minor revision
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