8,245 research outputs found
Thermal scale modeling
Complex system study data indicate that factors associated with multilayer insulation pose major problem in scale modeling, that numerical analysis aids correction for known compromises of scaling criteria, and that probable errors in scale modeling experiments fall within range predicted by statistical analysis
Consumption and Real Exchange Rates in Dynamic Economies with Non-Traded Goods
We examine the possibility that nontraded goods may account for several striking features of international macroeconomic data: large, persistent deviations from purchasing power parity, small correlations of aggregate consumption fluctuations across countries, and substantial international real interest rate differentials. A dynamic, exchange economy is used to show that nontraded goods in principle can account for each of these phenomena. In the theory there is a close relation between fluctuations in consumption ratios and those in bilateral real exchange rates, but we find little evidence for this relation in time series data for eight OECD countries.consumption correlations, purchasing power parity, real exchange rates
Spin solid phases of spin 1 and spin 3/2 antiferromagnets on a cubic lattice
We study spin S=1 and S=3/2 Heisenberg antiferromagnets on a cubic lattice
focusing on spin solid states. Using Schwinger boson formulation for spins, we
start in a U(1) spin liquid phase proximate to Neel phase and explore possible
confining paramagnetic phases as we transition away from the spin liquid by the
process of monopole condensation. Electromagnetic duality is used to rewrite
the theory in terms of monopoles. For spin 1 we find several candidate phases
of which the most natural one is a phase with spins organized into parallel
Haldane chains. For spin 3/2 we find that the most natural phase has spins
organized into parallel ladders. As a by-product, we also write a Landau theory
of the ordering in two special classical frustrated XY models on the cubic
lattice, one of which is the fully frustrated XY model. In a particular limit
our approach maps to a dimer model with 2S dimers coming out of every site, and
we find the same spin solid phases in this regime as well.Comment: 15 pages, 8 figure
Diagnosing Deconfinement and Topological Order
Topological or deconfined phases are characterized by emergent, weakly
fluctuating, gauge fields. In condensed matter settings they inevitably come
coupled to excitations that carry the corresponding gauge charges which
invalidate the standard diagnostic of deconfinement---the Wilson loop. Inspired
by a mapping between symmetric sponges and the deconfined phase of the
gauge theory, we construct a diagnostic for deconfinement that has the
interpretation of a line tension. One operator version of this diagnostic turns
out to be the Fredenhagen-Marcu order parameter known to lattice gauge
theorists and we show that a different version is best suited to condensed
matter systems. We discuss generalizations of the diagnostic, use it to
establish the existence of finite temperature topological phases in
dimensions and show that multiplets of the diagnostic are useful in settings
with multiple phases such as gauge theories with charge matter.
[Additionally we present an exact reduction of the partition function of the
toric code in general dimensions to a well studied problem.]Comment: 11 pages, several figure
Kerr effect as a tool for the investigation of dynamic heterogeneities
We propose a dynamic Kerr effect experiment for the distinction between
dynamic heterogeneous and homogeneous relaxation in glassy systems. The
possibility of this distinction is due to the inherent nonlinearity of the Kerr
effect signal. We model the slow reorientational molecular motion in
supercooled liquids in terms of non-inertial rotational diffusion. The Kerr
effect response, consisting of two terms, is calculated for heterogeneous and
for homogeneous variants of the stochastic model. It turns out that the
experiment is able to distinguish between the two scenarios. We furthermore
show that exchange between relatively 'slow' and 'fast' environments does not
affect the possibility of frequency-selective modifications. It is demonstrated
how information about changes in the width of the relaxation time distribution
can be obtained from experimental results.Comment: 23 pages incl. 6 figures accepted for publication in The Journal of
Chemical Physic
Dipolar spin correlations in classical pyrochlore magnets
We study spin correlations for the highly frustrated classical pyrochlore
lattice antiferromagnets with O(N) symmetry in the limit T->0. We conjecture
that a local constraint obeyed by the extensively degenerate ground states
dictates a dipolar form for the asymptotic spin correlations, at all N 2
for which the system is paramagnetic down to T=0. We verify this conjecture in
the cases N=1 and N=3 by simulations and to all orders in the 1/N expansion
about the solvable N=infinity limit. Remarkably, the N=infinity formulae are an
excellent fit, at all distances, to the correlators at N=3 and even at N=1.
Thus we obtain a simple analytical expression also for the correlations of the
equivalent models of spin ice and cubic water ice, I_h.Comment: 4 pages revtex
Quantum search algorithms on a regular lattice
Quantum algorithms for searching one or more marked items on a d-dimensional
lattice provide an extension of Grover's search algorithm including a spatial
component. We demonstrate that these lattice search algorithms can be viewed in
terms of the level dynamics near an avoided crossing of a one-parameter family
of quantum random walks. We give approximations for both the level-splitting at
the avoided crossing and the effectively two-dimensional subspace of the full
Hilbert space spanning the level crossing. This makes it possible to give the
leading order behaviour for the search time and the localisation probability in
the limit of large lattice size including the leading order coefficients. For
d=2 and d=3, these coefficients are calculated explicitly. Closed form
expressions are given for higher dimensions
DeepA2: A Modular Framework for Deep Argument Analysis with Pretrained Neural Text2Text Language Models
In this paper, we present and implement a multi-dimensional, modular framework for performing deep argument analysis (DeepA2) using current pre-trained language models (PTLMs). ArgumentAnalyst ā a T5 model [Raffel et al. 2020] set up and trained within DeepA2 ā reconstructs argumentative texts, which advance an informal argumentation, as valid arguments: It inserts, e.g., missing premises and conclusions, formalizes inferences, and coherently links the logical reconstruction to the source text. We create a synthetic corpus for deep argument analysis, and evaluate ArgumentAnalyst on this new dataset as well as on existing data, specifically EntailmentBank [Dalvi et al. 2021]. Our empirical findings vindicate the overall framework and highlight the advantages of a modular design, in particular its ability to emulate established heuristics (such as hermeneutic cycles), to explore the modelās uncertainty, to cope with the plurality of correct solutions (underdetermination), and to exploit higher-order evidence
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