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991.
Let R be a ring with unity. The inclusion ideal graph of a ring R, denoted by In(R), is a graph whose vertices are all nontrivial left ideals of R and two distinct left ideals I and J are adjacent if and only if I ? J or J ? I. In this paper, we show that In(R) is not connected if and only if R ? M 2(D) or D 1 × D 2, for some division rings, D, D 1 and D 2. Moreover, we prove that if In(R) is connected, then diam(In(R)) ≤3. It is shown that if In(R) is a tree, then In(R) is a caterpillar with diam(In(R)) ≤3. Also, we prove that the girth of In(R) belongs to the set {3, 6, ∞}. Finally, we determine the clique number and the chromatic number of the inclusion ideal graph for some classes of rings. 相似文献
992.
993.
Let (R, m) be a two-dimensional regular local ring and let A be a finitely generated torsion-free R-module. If A is a complete module, then Dan Katz and Vijay Kodiyalam show A satisfies five conditions. They ask whether these five conditions are equivalent without assuming A to be complete. In a previous paper we determined all implications among these five conditions with one exception. In this paper, with an additional hypothesis on the units of R, we resolve the remaining case. 相似文献
994.
R. Alkofer C. S. Fischer R. Williams 《The European Physical Journal A - Hadrons and Nuclei》2008,38(1):53-60
The U
A(1) problem of QCD is inevitably tied to the infrared behaviour of quarks and gluons with its most visible effect being the
-mass. A dimensional argument of Kogut and Susskind showed that the mixing of the pseudoscalar flavour-singlet mesons with
gluons can provide a screening of the Goldstone pole in this channel if the full quark-quark interaction is strongly infrared
singular as ∼ 1/k
4 . We investigate this idea using previously obtained results for the Landau gauge ghost and gluon propagator, together with
recent determinations for the singular behaviour of the quark-gluon vertex. We find that, even with an infrared vanishing
gluon propagator, the singular structure of the quark-gluon vertex for certain kinematics is apposite for yielding a non-zero
screening mass. 相似文献
995.
A time-dependent periodic Hamiltonian admitting exact solutions is applied to construct a set of universal gates for a quantum
computer. The time evolution matrices are obtained in an explicit form and used to construct logic gates for computation.
A way of obtaining an entanglement operator is discussed, too. The method is based on transformation of soluble time-independent
equations into time-dependent ones by employing a set of special time-dependent transformation operators.
The text was submitted by the authors in English. 相似文献
996.
The conceptual design for a high-sensitivity bunch charge monitor is presented. The device operates with short, spaced bunches.
For optimal performance, the bunch duration should be less than 10 ns and bunch spacing should be more than 100 ns. Sensitivity
of the monitor is close to 10 V per nanocoulomb. The equivalent scheme and the output signal shape are also presented. Such
a monitor seems to be promising for the bunch charge measurements of beams like those in TESLA or ILC projects.
The text was submitted by the authors in English. 相似文献
997.
998.
The DC-350 is an isochronous cyclotron designed in the Flerov Laboratory of Nuclear Reaction (FLNR). It is intended for accelerating
ions with a mass-to-charge ratio A/Z within an interval of 5–10 and with an energy of 3–12 MeV/u at the extraction radius.
These ion beams will be used in nuclear and applied physics experiments. The paper describes the results of a 3D magnet simulation.
The cyclotron magnet and IM90 analiziting-bend magnet of the axial injection channel are studied here. The influence of correction
coils on the cyclotron magnet is calculated. All magnet fields were calculated by MERMAID 3D code [1].
The text was submitted by the authors in English. 相似文献
999.
N. T. Khai T. D. Thiep T. T. An P. V. Cuong N. T. Vinh A. G. Belov O. D. Maslov 《Physics of Particles and Nuclei Letters》2008,5(5):437-440
Bremsstrahlung emission, or radiation loss, is the dominant mechanism of energy dissipation of electrons at relativistic energies
greater than a few MeV when it is subjected to acceleration in the field of the nucleus or of the electrons. In this study,
the Monte Carlo calculations for bremsstrahlung spectra have been described for the case of a thick tungsten target with incident
electron beams from 10 to 50 MeV, where secondary interactions induced by the electrons and photons in the target, such as
energy loss, absorption, scattering, and (e
+, e
−)-pair production effects, were taken into account.
The text was submitted by the authors in English. 相似文献
1000.
N. I. Ayzatsky A. N. Dovbnya V. V. Zakutin N. G. Reshetnyak V. N. Boriskin N. A. Dovbnya V. P. Romas’ko I. A. Chertishchev 《Physics of Particles and Nuclei Letters》2008,5(7):634-637
The reliability and service life of accelerating installations are substantially determined by the lifetime of electron sources.
The accelerator under consideration has a magnetron gun with a channel-free cold secondary-emission cathode in crossed fields
as an electron source [1, 2]. In the present work, the data of the electron beam parameters obtained in the accelerator based
on the magnetron gun with a secondary-emission cathode are given, and possible secondary uses are suggested.
The text was submitted by the authors in English. 相似文献