4,413 research outputs found
Solar generated quasi-biennial geomagnetic variation
The existence of highly correlated quasi-biennial variations in the geomagnetic field and in solar activity is demonstrated. The analysis uses a numerical filter technique applied to monthly averages of the geomagnetic horizontal component and of the Zurich relative sunspot number. Striking correlations are found between the quasi-biennial geomagnetic variations determined from several magnetic observatories located at widely different longitudes, indicating a worldwide nature of the obtained variation. The correlation coefficient between the filtered Dst index and the filtered relative sunspot number is found to be -0.79 at confidence level greater than 99% with a time-lag of 4 months, with solar activity preceding the Dst variation. The correlation between the unfiltered data of Dst and of the sunspot number is also high with a similar time-lag. Such a timelag has not been discussed in the literature, and a further study is required to establish the mode of sun-earth relationship that gives this time delay
Can realistic interaction be useful for nuclear mean-field approaches?
Recent applications of the M3Y-type semi-realistic interaction to the nuclear
mean-field approaches are presented: (i) Prediction of magic numbers and (ii)
isotope shifts of nuclei with magic proton numbers. The results exemplify that
realistic interaction, which is derived from the base and
interaction, furnish a new theoretical instrument for advancing nuclear
mean-field approaches.Comment: 9 pages including 6 figures, published in EPJA 52, 185 (2016
Investigation of MAGSAT and TRIAD magnetometer data to provide corrective information on high-lattitude external fields
Disturbances in the MAGSAT magnetometer data set due to high latitude phenomena were evaluated. Much of the categorization of disturbances due to Birkeland currents, ionospheric Hall currents, fine structure and wave phenomena was done with the MAGSAT data catalog. A color graphics technique was developed for the display of disturbances from multiple orbits, from which one can infer a 'global-image' of the current systems of the auroral zone. The MAGSAT 4/81 magnetic field model appears to represent the Earth's main field at high latitudes very well for the epoch 1980. MAGSAT's low altitude allows analysis of disturbances in the magnetometer data due to ionospheric electrojet currents. These current distributions were modeled properly for single events as a precursor to the inference of the Birkeland current system. MAGSAT's orbit was approximately shared with that of the Navy/APL TRIAD satellite. This allowed space-time studies of the magnetic disturbance signatures to be performed, the result being an approximately 75% agreement in, as well as high frequency of, signatures due to Birkeland currents. Thus the field-aligned currents are a steady-state participant in the Earth's magnetospheric current system
Magnetic field observations in high beta regions of the magnetosphere
OGO for magnetic field observations in high beta regions of magnetospher
Electronic Money and the Law: Legal Realities and Future Challenges
The following is a translation of Electronic Money and the Law: Legal Realities and Future Challenges, an essay written by Professor Nobuhiko Sugiura in the August 1, 2008 issue of the Japanese periodical Jurisuto. Stored-value cards are growing rapidly in urban areas in Japan, to a degree where they are beginning to challenge cash as a primary method of payment. In this article, Professor Sugiura outlines the growth of stored-value cards, how stored-value cards should be defined, legal structures that currently regulate stored-value cards, and how growth and technological development are likely to affect that legal structure. As Japan’s takes a leadership position in the field, Professor Sugiura’s article provides useful insight into Japanese regulation and how the Japanese are likely to address future legal challenges
Finite-temperature phase transitions in quasi-one-dimensional molecular conductors
Phase transitions in 1/4-filled quasi-one-dimensional molecular conductors
are studied theoretically on the basis of extended Hubbard chains including
electron-lattice interactions coupled by interchain Coulomb repulsion. We apply
the numerical quantum transfer-matrix method to an effective one-dimensional
model, treating the interchain term within mean-field approximation.
Finite-temperature properties are investigated for the charge ordering, the
"dimer Mott" transition (bond dimerization), and the spin-Peierls transition
(bond tetramerization). A coexistent state of charge order and bond
dimerization exhibiting dielectricity is predicted in a certain parameter
range, even when intrinsic dimerization is absent.Comment: to be published in J. Phys. Soc. Jpn., Vol. 76 (2007) No. 1 (5 pages,
4 figures); typo correcte
Metastability in Interacting Nonlinear Stochastic Differential Equations II: Large-N Behaviour
We consider the dynamics of a periodic chain of N coupled overdamped
particles under the influence of noise, in the limit of large N. Each particle
is subjected to a bistable local potential, to a linear coupling with its
nearest neighbours, and to an independent source of white noise. For strong
coupling (of the order N^2), the system synchronises, in the sense that all
oscillators assume almost the same position in their respective local potential
most of the time. In a previous paper, we showed that the transition from
strong to weak coupling involves a sequence of symmetry-breaking bifurcations
of the system's stationary configurations, and analysed in particular the
behaviour for coupling intensities slightly below the synchronisation
threshold, for arbitrary N. Here we describe the behaviour for any positive
coupling intensity \gamma of order N^2, provided the particle number N is
sufficiently large (as a function of \gamma/N^2). In particular, we determine
the transition time between synchronised states, as well as the shape of the
"critical droplet", to leading order in 1/N. Our techniques involve the control
of the exact number of periodic orbits of a near-integrable twist map, allowing
us to give a detailed description of the system's potential landscape, in which
the metastable behaviour is encoded
Power of sequential protocols in hidden quantum channel discrimination
In many natural and engineered systems, unknown quantum channels act on a
subsystem that cannot be directly controlled and measured, but is instead
learned through a controllable subsystem that weakly interacts with it. We
study quantum channel discrimination (QCD) under these restrictions, which we
call hidden system QCD (HQCD). We find that sequential protocols achieve
perfect discrimination and saturate the Heisenberg limit. In contrast, depth-1
parallel and multi-shot protocols cannot solve HQCD. This suggests that
sequential protocols are superior in experimentally realistic situations.Comment: 18pages, 10figure
On the correllation effect in Peierls-Hubbard chains
We reexamine the dimerization, the charge and the spin gaps of a half-filled
Peierls-Hubbard chain by means of the incremental expansion technique. Our
numerical findings are in significant quantitative conflict with recently
obtained results by M. Sugiura and Y. Suzumura [J. Phys. Soc. Jpn. v. 71 (2002)
697] based on a bosonization and a renormalization group method, especially
with respect to the charge gap. Their approach seems to be valid only in the
weakly correlated case.Comment: 7pages,4figures(6eps-files
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