473 research outputs found
Classification of Singular Fibres on Rational Elliptic Surfaces in Characteristic Three
We determine and list all possible configurations of singular fibres on
rational elliptic surfaces in characteristic three. In total, we find that 267
distinct configurations exist. This result complements Miranda and Persson's
classification in characteristic zero, and Lang's classification in
characteristic two.Comment: 40 Pages. Minor typos correcte
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The ISSI international study team on the martian PBL – status report and plan
Dynamical processes in the Martian boundary layer provide the means of communication between surface ice deposits and the free atmosphere, and the means of lifting dust from the surface. The boundary layer is therefore one of the most important components of the Martian climate system. The Martian boundary layer differs from that of the Earth in that it is more strongly forced, it is deeper, and the relative importance of radiative and convective heat fluxes in the lower boundary layer can be quite different. In order to understand the Martian boundary layer, a combination of theoretical, modeling and observational studies are necessary. Interactions between theorists, modelers, and observational scientists are needed to make progress and to provide a basis for analysis of data expected from Phoenix, Mars Science Laboratory, ExoMars and other future landed missions (such as a surface network mission), or missions such as balloons or other aircraft operating in the neutral atmosphere. The prime goal of this project under the auspices of the International Space Science Institute (ISSI) is to review and assess the current knowledge and understanding of Martian planetary boundary layer and its interactions with the surface and free atmosphere. We aim to promote international communication and collaboration to enhance the rate of acquisition of knowledge and understanding. This will be achieved through an International Study Team and publication of overview papers and individual reports on recent advances in this area
Realization of efficient quantum gates with a superconducting qubit-qutrit circuit
Building a quantum computer is a daunting challenge since it requires good
control but also good isolation from the environment to minimize decoherence.
It is therefore important to realize quantum gates efficiently, using as few
operations as possible, to reduce the amount of required control and operation
time and thus improve the quantum state coherence. Here we propose a
superconducting circuit for implementing a tunable system consisting of a
qutrit coupled to two qubits. This system can efficiently accomplish various
quantum information tasks, including generation of entanglement of the two
qubits and conditional three-qubit quantum gates, such as the Toffoli and
Fredkin gates. Furthermore, the system realizes a conditional geometric gate
which may be used for holonomic (non-adiabatic) quantum computing. The
efficiency, robustness and universality of the presented circuit makes it a
promising candidate to serve as a building block for larger networks capable of
performing involved quantum computational tasks.Comment: 27 pages including technical supplementary information, 9 figures,
comments are most welcom
Joint density-functional theory for electronic structure of solvated systems
We introduce a new form of density functional theory for the {\em ab initio}
description of electronic systems in contact with a molecular liquid
environment. This theory rigorously joins an electron density-functional for
the electrons of a solute with a classical density-functional theory for the
liquid into a single variational principle for the free energy of the combined
system. A simple approximate functional predicts, without any fitting of
parameters to solvation data, solvation energies as well as state-of-the-art
quantum-chemical cavity approaches, which require such fitting.Comment: Fixed typos and minor updates to tex
NGC 7468: a galaxy with an inner polar disk
We present our spectroscopic observations of the galaxy NGC 7468 performed at
the 6-m Special Astrophysical Observatory telescope using the UAGS long-slit
spectrograph, the multipupil fiber spectrograph MPFS, and the scanning
Fabry-Perot interferometer (IFP). We found no significant deviations from the
circular rotation of the galactic disk in the velocity field in the regions of
brightness excess along the major axis of the galaxy (the putative polar ring).
Thus, these features are either tidal structures or weakly developed spiral
arms. However, we detected a gaseous disk at the center of the galaxy whose
rotation plane is almost perpendicular to the plane of the galactic disk. The
central collision of NGC 7468 with a gas-rich dwarf galaxy and their subsequent
merging seem to be responsible for the formation of this disk.Comment: 8 pages, 6 figures, accepted in Astronomy Letters, 2004, vol 30., N
9, p. 58
Phase-Control of Photoabsorption in Optically Dense Media
We present a self-consistent theory, as well as an illustrative application
to a realistic system, of phase control of photoabsorption in an optically
dense medium. We demonstrate that, when propagation effects are taken into
consideration, the impact on phase control is significant. Independently of the
value of the initial phase difference between the two fields, over a short
scaled distance of propagation, the medium tends to settle the relative phase
so that it cancels the atomic excitation. In addition, we find some rather
unusual behavior for an optically thin layer.Comment: 5 pages, 3 figures, submitted to PR
Relationship between gender and levels of loneliness and anxiety in students
This article discusses issues related to the relationship between gender and feelings of loneliness and anxiety in students. An empirical and theoretical study of the interaction of gender and feelings of loneliness and anxiety is carried out, the results are presentedВ данной статье рассмотрены вопросы, касающиеся взаимосвязи половой принадлежности и чувств одиночества и тревожности у студентов. Проведено эмпирическое и теоретическое исследование взаимодействия половой принадлежности и чувств одиночества и тревожности, представлены результат
Toroidal optical dipole traps for atomic Bose-Einstein condensates using Laguerre-Gaussian beams
We theoretically investigate the use of red-detuned Laguerre-Gaussian (LG)
laser beams of varying azimuthal mode index for producing toroidal optical
dipole traps in two-dimensional atomic Bose-Einstein condensates. Higher-order
LG beams provide deeper potential wells and tighter confinement for a fixed
toroid radius and laser power. Numerical simulations of the loading of the
toroidal trap from a variety of initial conditions is also given.Comment: 12 pages, 5 figures, submitted to Phys. Rev.
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