33,195 research outputs found
Medical Information Management System (MIMS): A generalized interactive information system
An interactive information system is described. It is a general purpose, free format system which offers immediate assistance where manipulation of large data bases is required. The medical area is a prime area of application. Examples of the system's operation, commentary on the examples, and a complete listing of the system program are included
Localization-protected order in spin chains with non-Abelian discrete symmetries
We study the non-equilibrium phase structure of the three-state random
quantum Potts model in one dimension. This spin chain is characterized by a
non-Abelian symmetry recently argued to be incompatible with the
existence of a symmetry-preserving many-body localized (MBL) phase. Using exact
diagonalization and a finite-size scaling analysis, we find that the model
supports two distinct broken-symmetry MBL phases at strong disorder that either
break the clock symmetry or a chiral
symmetry. In a dual formulation, our results indicate the existence of a stable
finite-temperature topological phase with MBL-protected parafermionic end zero
modes. While we find a thermal symmetry-preserving regime for weak disorder,
scaling analysis at strong disorder points to an infinite-randomness critical
point between two distinct broken-symmetry MBL phases.Comment: 5 pages, 3 figures main text; 6 pages, 3 figures supplemental
material; Version 2 includes a corrected the form of the chiral order
parameter, and corresponding data, as well as larger system size numerics,
with no change to the phase structur
Particle-hole symmetry, many-body localization, and topological edge modes
We study the excited states of interacting fermions in one dimension with
particle-hole symmetric disorder (equivalently, random-bond XXZ chains) using a
combination of renormalization group methods and exact diagonalization. Absent
interactions, the entire many-body spectrum exhibits infinite-randomness
quantum critical behavior with highly degenerate excited states. We show that
though interactions are an irrelevant perturbation in the ground state, they
drastically affect the structure of excited states: even arbitrarily weak
interactions split the degeneracies in favor of thermalization (weak disorder)
or spontaneously broken particle-hole symmetry, driving the system into a
many-body localized spin glass phase (strong disorder). In both cases, the
quantum critical properties of the non-interacting model are destroyed, either
by thermal decoherence or spontaneous symmetry breaking. This system then has
the interesting and counterintuitive property that edges of the many-body
spectrum are less localized than the center of the spectrum. We argue that our
results rule out the existence of certain excited state symmetry-protected
topological orders.Comment: 9 pages. 7 figure
Third Earth Resources Technology Satellite Symposium. Volume 3: Discipline summary reports
Presentations at the conference covered the following disciplines: (1) agriculture, forestry, and range resources; (2) land use and mapping; (3) mineral resources, geological structure, and landform surveys; (4) water resources; (5) marine resources; (6) environment surveys; and (7) interpretation techniques
Third Earth Resources Technology Satellite Symposium. Volume 2: Summary of results
Summaries are provided of significant results taken from presentations at the symposium along with some typical examples of the applications of ERTS-1 data for solving resources management problems at the national, state, and local levels
Quantum Lattice Fluctuations and Luminescence in C_60
We consider luminescence in photo-excited neutral C_60 using the
Su-Schrieffer-Heeger model applied to a single C_60 molecule. To calculate the
luminescence we use a collective coordinate method where our collective
coordinate resembles the displacement of the carbon atoms of the Hg(8) phonon
mode and extrapolates between the ground state "dimerisation" and the exciton
polaron. There is good agreement for the existing luminescence peak spacing and
fair agreement for the relative intensity. We predict the existence of further
peaks not yet resolved in experiment. PACS Numbers : 78.65.Hc, 74.70.Kn,
36.90+
Future directions in kaonic atom physics
Recent progress and open problems in kaonic atom physics are presented. A
connection between phenomenological deep potentials and the underlying
interaction is established as well as the need for a theory for multinucleon
absorption of kaons. absorption at rest to specific
hypernuclei states is briefly discussed.Comment: 6 pages, 3 figures, proceedings of the EXA2011 conference, to appear
in Hyperfine Interaction
Models of helically symmetric binary systems
Results from helically symmetric scalar field models and first results from a
convergent helically symmetric binary neutron star code are reported here;
these are models stationary in the rotating frame of a source with constant
angular velocity omega. In the scalar field models and the neutron star code,
helical symmetry leads to a system of mixed elliptic-hyperbolic character. The
scalar field models involve nonlinear terms that mimic nonlinear terms of the
Einstein equation. Convergence is strikingly different for different signs of
each nonlinear term; it is typically insensitive to the iterative method used;
and it improves with an outer boundary in the near zone. In the neutron star
code, one has no control on the sign of the source, and convergence has been
achieved only for an outer boundary less than approximately 1 wavelength from
the source or for a code that imposes helical symmetry only inside a near zone
of that size. The inaccuracy of helically symmetric solutions with appropriate
boundary conditions should be comparable to the inaccuracy of a waveless
formalism that neglects gravitational waves; and the (near zone) solutions we
obtain for waveless and helically symmetric BNS codes with the same boundary
conditions nearly coincide.Comment: 19 pages, 7 figures. Expanded version of article to be published in
Class. Quantum Grav. special issue on Numerical Relativit
Polaron Excitations in Doped C60: Effects of Disorders
Effects on C by thermal fluctuations of phonons, misalignment of
C molecules in a crystal, and other intercalated impurities (remaining
C, oxygens, and so on) are simulated by disorder potentials. The
Su-Schrieffer-Heeger--type electron-phonon model for doped C is solved
with gaussian bond disorders and also with site disorders. Sample average is
performed over sufficient number of disorder configurations. The distributions
of bond lengths and electron densities are shown as functions of the disorder
strength and the additional electron number. Stability of polaron excitations
as well as dimerization patterns is studied. Polarons and dimerizations in
lightly doped cases (C) are relatively stable against disorders,
indicated by peak structures in distribution functions. In more heavily doped
cases, the several peaks merge into a single peak, showing the breakdown of
polaron structures as well as the decrease of the dimerization strength.
Possibility of the observation of polaronic lattice distortions and electron
structures in doped C is discussed.Comment: Note: This manusript was accepted for publication in Physical Review
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