62 research outputs found
Quantum Annealing Effect on Entropic Slowing Down in Frustrated Decorated Bond System
We propose that the importance of the quantum annealing procedure to find the
ground state of frustrated decorated bond systems where 'entropic slowing down'
happens due to peculiar density of states. Here, we use the time dependent
Schr\"odinger equation to analyze the real time dynamics of the process. It is
found that the quantum annealing is very efficient comparing to the thermal
annealing for searching the ground state of the systems. We analyze the
mechanism of quantum annealing from a view point of adiabatic process.Comment: 2 pages, 4 figures, proceedings of ICM200
Quantum Field Induced Orderings in Fully Frustrated Ising Spin Systems
We study ordering mechanisms which are induced by the quantum fluctuation in
fully frustrated Ising spin systems. Since there are many degenerated states in
frustrated systems, "order by thermal disorder" often takes place due to a kind
of entropy effect. To consider "order by quantum disorder" in fully frustrated
Ising spin systems, we apply transverse field as quantum fluctuation. There
exists a ferromagnetic correlation in each sublattice. The sublattice
correlation at zero temperature is enlarged due to transverse field. The
quantum fluctuation enhances the solid order at zero temperatures. This is an
example of quantum field induced ordering in fully frustrated systems. We also
study a case in which the transverse field induces a reentrant behavior as
another type of order by quantum disorder, and compare correspondent cases in
the classical systems.Comment: 3 pages, 4 figures, submitted to Proceedings of Symposia "Nanoscience
and Quantum Physics
Theory and Applications of Non-Relativistic and Relativistic Turbulent Reconnection
Realistic astrophysical environments are turbulent due to the extremely high
Reynolds numbers. Therefore, the theories of reconnection intended for
describing astrophysical reconnection should not ignore the effects of
turbulence on magnetic reconnection. Turbulence is known to change the nature
of many physical processes dramatically and in this review we claim that
magnetic reconnection is not an exception. We stress that not only
astrophysical turbulence is ubiquitous, but also magnetic reconnection itself
induces turbulence. Thus turbulence must be accounted for in any realistic
astrophysical reconnection setup. We argue that due to the similarities of MHD
turbulence in relativistic and non-relativistic cases the theory of magnetic
reconnection developed for the non-relativistic case can be extended to the
relativistic case and we provide numerical simulations that support this
conjecture. We also provide quantitative comparisons of the theoretical
predictions and results of numerical experiments, including the situations when
turbulent reconnection is self-driven, i.e. the turbulence in the system is
generated by the reconnection process itself. We show how turbulent
reconnection entails the violation of magnetic flux freezing, the conclusion
that has really far reaching consequences for many realistically turbulent
astrophysical environments. In addition, we consider observational testing of
turbulent reconnection as well as numerous implications of the theory. The
former includes the Sun and solar wind reconnection, while the latter include
the process of reconnection diffusion induced by turbulent reconnection, the
acceleration of energetic particles, bursts of turbulent reconnection related
to black hole sources as well as gamma ray bursts. Finally, we explain why
turbulent reconnection cannot be explained by turbulent resistivity or derived
through the mean field approach.Comment: 66 pages, 24 figures, a chapter of the book "Magnetic Reconnection -
Concepts and Applications", editors W. Gonzalez, E. N. Parke
Designs and Production Technology of Sickle Elements in Late Neolithic Wadi Ziqlab, Northern Jordan
Abstract : This paper examines sickle elements from Late Neolithic agricultural settlements in the southern Levant with a particular focus on the tool morphology and the production technology. The results of the examination suggest that two Late Neolithic farmsteads in Wadi Ziqlab share greater morphological similarity of sickle elements than do other sites of the same cultural group (the Wadi Rabah culture) in other regions. However, the technological analyses of sickle elements suggest that the two farmsteads in Wadi Ziqlab had different patterns in some technological practices during the production processes, including the blank production, the extent of retouch, backing technique, and possibly the sequence of retouching processes.
Based on these results, the subsequent discussion aims at explaining the standardized design of sickle elements and their varied production technology observed in Wadi Ziqlab, particularly focusing on several factors, including chronology, geography, the mechanical functions of sickle elements, and the mechanical logistics of production technology. After examining these factors, I will briefly discuss social contexts that may have been related to the production practices of sickle elements.Résumé : Cette étude examine les éléments de faucille des établissements agricoles du Néolithique Récent dans le Sud du Levant ; l 'attention se porte plus particulièrement sur la morphologie des outils et la technologie de production. Les résultats de l'analyse suggèrent que les deux établissements du Wadi Ziqlab présentent une plus grande similarité morphologique des éléments de faucille que ne le font dans les autres régions les sites de même culture (Wadi Rabah). Les analyses technologiques des éléments de faucille suggèrent pourtant que les deux fermes du Wadi Ziqlab usaient de modes différents dans leurs technologies que ce soient celle de la production et de la sélection du support (éclats vs lames), l'étendue de la retouche et la retouche (denticulation, dos, troncature).
En se fondant sur ces résultats, la discussion cherche à comprendre comment s 'est effectuée à la fois la standardisation des éléments de faucille et la variation dans les techniques de production observée sur les sites du Wadi Ziqlab. Plusieurs facteurs sont pris en compte : chronologie, géographie, fonctions mécaniques des éléments de faucilles, et logiques mécaniques des technologies de production. Après l 'examen de ces facteurs, une brève discussion porte sur les contextes sociaux qui peuvent avoir exercé une influence sur les mécanismes de production d'éléments de faucille.Kadowaki Seiji. Designs and Production Technology of Sickle Elements in Late Neolithic Wadi Ziqlab, Northern Jordan . In: Paléorient, 2005, vol. 31, n°2. pp. 69-85
Holocene book review: A Holocene prehistoric sequence in the Egyptian Red Sea area: the Tree Shelter
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