173,740 research outputs found
On Inhomogeneity of a String Bit Model for Quantum Gravity
We study quantum gravitational effect on a two-dimensional open universe with
one particle by means of a string bit model. We find that matter is necessarily
homogeneously distributed if the influence of the particle on the size of the
universe is optimized.Comment: 16 pages, LaTeX2
Unitary Irreducible Representations of a Lie Algebra for Matrix Chain Models
There is a decomposition of a Lie algebra for open matrix chains akin to the
triangular decomposition. We use this decomposition to construct unitary
irreducible representations. All multiple meson states can be retrieved this
way. Moreover, they are the only states with a finite number of non-zero
quantum numbers with respect to a certain set of maximally commuting linearly
independent quantum observables. Any other state is a tensor product of a
multiple meson state and a state coming from a representation of a quotient
algebra that extends and generalizes the Virasoro algebra. We expect the
representation theory of this quotient algebra to describe physical systems at
the thermodynamic limit.Comment: 46 pages, no figure; LaTeX2e, amssymb, latexsym; typos correcte
Large-N Yang-Mills Theory as Classical Mechanics
To formulate two-dimensional Yang-Mills theory with adjoint matter fields in
the large-N limit as classical mechanics, we derive a Poisson algebra for the
color-invariant observables involving adjoint matter fields. We showed
rigorously in J. Math. Phys. 40, 1870 (1999) that different quantum orderings
of the observables produce essentially the same Poisson algebra. Here we
explain, in a less precise but more pedagogical manner, the crucial topological
graphical observations underlying the formal proof.Comment: 8 pages, 3 eps figues, LaTeX2.09, aipproc macros needed; conference
proceeding of MRST '99 (10-12 May, 1999, Carleton University, Canada
A Lie Algebra for Closed Strings, Spin Chains and Gauge Theories
We consider quantum dynamical systems whose degrees of freedom are described
by matrices, in the planar limit . Examples are
gauge theoires and the M(atrix)-theory of strings. States invariant under U(N)
are `closed strings', modelled by traces of products of matrices. We have
discovered that the U(N)-invariant opertors acting on both open and closed
string states form a remarkable new Lie algebra which we will call the heterix
algebra. (The simplest special case, with one degree of freedom, is an
extension of the Virasoro algebra by the infinite-dimensional general linear
algebra.) Furthermore, these operators acting on closed string states only form
a quotient algebra of the heterix algebra. We will call this quotient algebra
the cyclix algebra. We express the Hamiltonian of some gauge field theories
(like those with adjoint matter fields and dimensionally reduced pure QCD
models) as elements of this Lie algebra. Finally, we apply this cyclix algebra
to establish an isomorphism between certain planar matrix models and quantum
spin chain systems. Thus we obtain some matrix models solvable in the planar
limit; e.g., matrix models associated with the Ising model, the XYZ model,
models satisfying the Dolan-Grady condition and the chiral Potts model. Thus
our cyclix Lie algebra described the dynamical symmetries of quantum spin chain
systems, large-N gauge field theories, and the M(atrix)-theory of strings.Comment: 52 pages, 8 eps figures, LaTeX2.09; this is the published versio
Nonmonotonic behavior of resistance in a superconductor-Luttinger liquid junction
Transport through a superconductor-Luttinger liquid junction is considered.
When the interaction in the Luttinger liquid is repulsive, the resistance of
the junction with a sufficiently clean interface shows nonmonotonic
temperature- or voltage-dependence due to the competition between the
superconductivity and the repulsive interaction. The result is discussed in
connection with recent experiments on single-wall carbon nanotubes in contact
with superconducting leads.Comment: Revtex4, 2 eps figure files, slightly revised from an earlier version
submitted to PRL on 2001.12.
A micro cell lysis device
A new micromachined cell lysis device is developed. It is designed for miniature bio-analysis systems where cell lysing is needed to obtain intracellular materials for further analysis such as DNA identification. It consists of muti-electrode pairs to apply electric fields to cells. We adopt the means of using electric field lysing because it can greatly simplify purification steps for preparation of biological samples, when compared to conventional chemical methods. Yeast, Chinese cabbage, radish cells and E. coli are tested with the device. The lysis of yeast, Chinese cabbage, radish cells is observed by a microscope. The experimental observation suggests E. coli are also lysed by the pulsed electric field. The range of electric field for the lysis is on the order of 1 kV/cm to 10 kV/cm. In addition, for practical reasons, we reduce the voltage required for lysing to less than 10 V by making the electrode gap on the order of microns
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