10,954 research outputs found
Irrational mode locking in quasiperiodic systems
A model for ac-driven systems, based on the
Tang-Wiesenfeld-Bak-Coppersmith-Littlewood automaton for an elastic medium,
exhibits mode-locked steps with frequencies that are irrational multiples of
the drive frequency, when the pinning is spatially quasiperiodic. Detailed
numerical evidence is presented for the large-system-size convergence of such a
mode-locked step. The irrational mode locking is stable to small thermal noise
and weak disorder. Continuous time models with irrational mode locking and
possible experimental realizations are discussed.Comment: 4 pages, 3 figures, 1 table; revision: 2 figures modified, reference
added, minor clarification
Reply to Comment on "Triviality of the Ground State Structure in Ising Spin Glasses"
We reply to the comment of Marinari and Parisi [cond-mat/0002457 v2] on our
paper [Phys. Rev. Lett. 83, 5126 (1999) and cond-mat/9906323]. We show that the
data in the comment are affected by strong finite-size corrections. Therefore
the original conclusion of our paper still stands.Comment: Reply to comment cond-mat/0002457 on cond-mat/9906323. Final version
with minor change
Collective Transport in Arrays of Quantum Dots
(WORDS: QUANTUM DOTS, COLLECTIVE TRANSPORT, PHYSICAL EXAMPLE OF KPZ)
Collective charge transport is studied in one- and two-dimensional arrays of
small normal-metal dots separated by tunnel barriers. At temperatures well
below the charging energy of a dot, disorder leads to a threshold for
conduction which grows linearly with the size of the array. For short-ranged
interactions, one of the correlation length exponents near threshold is found
from a novel argument based on interface growth. The dynamical exponent for the
current above threshold is also predicted analytically, and the requirements
for its experimental observation are described.Comment: 12 pages, 3 postscript files included, REVTEX v2, (also available by
anonymous FTP from external.nj.nec.com, in directory /pub/alan/dotarrays [as
separate files]) [replacement: FIX OF WRONG VERSION, BAD SHAR] March 17,
1993, NEC
A randomised trial evaluating Bevacizumab as adjuvant therapy following resection of AJCC stage IIB, IIC and III cutaneous melanoma : an update
At present, there are no standard therapies for the adjuvant treatment of malignant melanoma. Patients with primary tumours with a high-Breslow thickness (stages IIB and IIC) or with resected loco-regional nodal disease (stage III) are at high risk of developing metastasis and subsequent disease-related death. Given this, it is important that novel therapies are investigated in the adjuvant melanoma setting. Since angiogenesis is essential for primary tumour growth and the development of metastasis, anti-angiogenic agents are attractive potential therapeutic candidates for clinical trials in the adjuvant setting. Therefore, we initiated a phase II trial in resected high-risk cutaneous melanoma, assessing the efficacy of bevacizumab versus observation.
In the interim safety data analysis, we demonstrate that bevacizumab is a safe therapy in the adjuvant melanoma setting with no apparent increase in the surgical complication rate after either primary tumour resection and/or loco-regional lymphadenectomy
First excitations in two- and three-dimensional random-field Ising systems
We present results on the first excited states for the random-field Ising
model. These are based on an exact algorithm, with which we study the
excitation energies and the excitation sizes for two- and three-dimensional
random-field Ising systems with a Gaussian distribution of the random fields.
Our algorithm is based on an approach of Frontera and Vives which, in some
cases, does not yield the true first excited states. Using the corrected
algorithm, we find that the order-disorder phase transition for three
dimensions is visible via crossings of the excitations-energy curves for
different system sizes, while in two-dimensions these crossings converge to
zero disorder. Furthermore, we obtain in three dimensions a fractal dimension
of the excitations cluster of d_s=2.42(2). We also provide analytical droplet
arguments to understand the behavior of the excitation energies for small and
large disorder as well as close to the critical point.Comment: 17 pages, 12 figure
Thermal Rounding of the Charge Density Wave Depinning Transition
The rounding of the charge density wave depinning transition by thermal noise
is examined. Hops by localized modes over small barriers trigger
``avalanches'', resulting in a creep velocity much larger than that expected
from comparing thermal energies with typical barriers. For a field equal to the
depinning field, the creep velocity is predicted to have a {\em
power-law} dependence on the temperature ; numerical computations confirm
this result. The predicted order of magnitude of the thermal rounding of the
depinning transition is consistent with rounding seen in experiment.Comment: 12 pages + 3 Postscript figure
Hysterectomy, endometrial ablation, and levonorgestrel releasing intrauterine system (Mirena) for treatment of heavy menstrual bleeding : cost effectiveness analysis
Peer reviewedPublisher PD
Avalanches and the Renormalization Group for Pinned Charge-Density Waves
The critical behavior of charge-density waves (CDWs) in the pinned phase is
studied for applied fields increasing toward the threshold field, using
recently developed renormalization group techniques and simulations of
automaton models. Despite the existence of many metastable states in the pinned
state of the CDW, the renormalization group treatment can be used successfully
to find the divergences in the polarization and the correlation length, and, to
first order in an expansion, the diverging time scale. The
automaton models studied are a charge-density wave model and a ``sandpile''
model with periodic boundary conditions; these models are found to have the
same critical behavior, associated with diverging avalanche sizes. The
numerical results for the polarization and the diverging length and time scales
in dimensions are in agreement with the analytical treatment. These
results clarify the connections between the behaviour above and below
threshold: the characteristic correlation lengths on both sides of the
transition diverge with different exponents. The scaling of the distribution of
avalanches on the approach to threshold is found to be different for automaton
and continuous-variable models.Comment: 29 pages, 11 postscript figures included, REVTEX v3.0 (dvi and PS
files also available by anonymous ftp from external.nj.nec.com in directory
/pub/alan/cdwfigs
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