10,564 research outputs found
The solar wind effect on cosmic rays and solar activity
The relation of cosmic ray intensity to solar wind velocity is investigated, using neutron monitor data from Kiel and Deep River. The analysis shows that the regression coefficient of the average intensity for a time interval to the corresponding average velocity is negative and that the absolute effect increases monotonously with the interval of averaging, tau, that is, from -0.5% per 100km/s for tau = 1 day to -1.1% per 100km/s for tau = 27 days. For tau 27 days the coefficient becomes almost constant independently of the value of tau. The analysis also shows that this tau-dependence of the regression coefficiently is varying with the solar activity
Nonlinear input-normal realizations based on the differential eigenstructure of hankel operators
This paper investigates the differential eigenstructure of Hankel operators for nonlinear systems. First, it is proven that the variational system and the Hamiltonian extension with extended input and output spaces can be interpreted as the GĂÂąteaux differential and its adjoint of a dynamical input-output system, respectively. Second, the GĂÂąteaux differential is utilized to clarify the main result the differential eigenstructure of the nonlinear Hankel operator which is closely related to the Hankel norm of the original system. Third, a new characterization of the nonlinear extension of Hankel singular values are given based on the differential eigenstructure. Finally, a balancing procedure to obtain a new input-normal/output-diagonal realization is derived. The results in this paper thus provide new insights to the realization and balancing theory for nonlinear systems.
Finite Temperature Renormalization of the - and -Models at Zero Momentum
A self-consistent renormalization scheme at finite temperature and zero
momentum is used together with the finite temperature renormalization group to
study the temperature dependence of the mass and the coupling to one-loop order
in the - and -models. It is found that the critical
temperature is shifted relative to the naive one-loop result and the coupling
constants at the critical temperature get large corrections. In the high
temperature limit of the \phiff-model the coupling decreases.Comment: 16 pages, plain Latex, NORDITA-92/38
QED Radiative Corrections to the Non-annihilation Processes Using the Structure Function and the Parton Shower
Inclusion of the QED higher order radiative corrections in the two-photon
process, e+e- -> e+e- mu+mu-, is examined by means of the structure function
and the parton shower. Results are compared with the exact
calculations and give a good agreement. These two methods should be universally
applicable to any other non-annihilation processes like the single-W
productions in the e+e- collisions. In this case, however, the energy scale for
the evolution by the renormalization-group equation should be chosen properly
depending on the dominant diagrams for the given process. A method to find the
most suitable energy scale is proposed.Comment: 17 pages, LaTeX, 5 figure
Correlating Methane Production to Microbiota in Anaerobic Digesters Fed Synthetic Wastewater
A quantitative structure activity relationship (QSAR) between relative abundance values and digester methane production rate was developed. For this, 50 triplicate anaerobic digester sets (150 total digesters) were each seeded with different methanogenic biomass samples obtained from full-scale, engineered methanogenic systems. Although all digesters were operated identically for at least 5 solids retention times (SRTs), their quasi steady-state function varied significantly, with average daily methane production rates ranging from 0.09 ± 0.004 to 1 ± 0.05 L-CH4/LR-day (LR = Liter of reactor volume) (average ± standard deviation). Digester microbial community structure was analyzed using more than 4.1 million partial 16S rRNA gene sequences of Archaea and Bacteria. At the genus level, 1300 operational taxonomic units (OTUs) were observed across all digesters, whereas each digester contained 158 ± 27 OTUs. Digester function did not correlate with typical biomass descriptors such as volatile suspended solids (VSS) concentration, microbial richness, diversity or evenness indices. However, methane production rate did correlate notably with relative abundances of one Archaeal and nine Bacterial OTUs. These relative abundances were used as descriptors to develop a multiple linear regression (MLR) QSAR equation to predict methane production rates solely based on microbial community data. The model explained over 66% of the variance in the experimental data set based on 149 anaerobic digesters with a standard error of 0.12 L-CH4/LR-day. This study provides a framework to relate engineered process function and microbial community composition which can be further expanded to include different feed stocks and digester operating conditions in order to develop a more robust QSAR model
QED Radiative Correction for the Single-W Production using a Parton Shower Method
A parton shower method for the photonic radiative correction is applied to
the single W-boson production processes. The energy scale for the evolution of
the parton shower is determined so that the correct soft-photon emission is
reproduced. Photon spectra radiated from the partons are compared with those
from the exact matrix elements, and show a good agreement. Possible errors due
to a inappropriate energy-scale selection or due to the ambiguity of energy
scale determination are also discussed, particularly for the measurements on
triple gauge-couplings.Comment: 17 pages, 6 Postscript figure
- âŠ