769 research outputs found
The development of a method for generating patterns for garments that conform to the shape of the human body.
Correlation Functions of Coulomb Branch Operators
We consider the correlation functions of Coulomb branch operators in
four-dimensional N=2 Superconformal Field Theories (SCFTs) involving exactly
one anti-chiral operator. These extremal correlators are the "minimal"
non-holomorphic local observables in the theory. We show that they can be
expressed in terms of certain determinants of derivatives of the four-sphere
partition function of an appropriate deformation of the SCFT. This relation
between the extremal correlators and the deformed four-sphere partition
function is non-trivial due to the presence of conformal anomalies, which lead
to operator mixing on the sphere. Evaluating the deformed four-sphere partition
function using supersymmetric localization, we compute the extremal correlators
explicitly in many interesting examples. Additionally, the representation of
the extremal correlators mentioned above leads to a system of integrable
differential equations. We compare our exact results with previous perturbative
computations and with the four-dimensional tt^* equations. We also use our
results to study some of the asymptotic properties of the perturbative series
expansions we obtain in N=2 SQCD.Comment: 47 pages, 6 figures. v2: typos corrected and references adde
Magnetothermal Transport in Spin-Ladder Systems
We study a theoretical model for the magnetothermal conductivity of a
spin-1/2 ladder with low exchange coupling () subject to a strong
magnetic field . Our theory for the thermal transport accounts for the
contribution of spinons coupled to lattice phonon modes in the one-dimensional
lattice. We employ a mapping of the ladder Hamiltonian onto an XXZ spin-chain
in a weaker effective field B_{eff}=B-B_{0}B_{0}=(B_{c1}+B_{c2})/2B{\rm
Br_4(C_5H_{12}N)_2}$ (BPCB).Comment: 14 pages, 4 figure
Nernst Effect as a Signature of Quantum Fluctuations in Quasi-1D Superconductors
We study a model for the transverse thermoelectric response due to quantum
superconducting fluctuations in a two-leg Josephson ladder, subject to a
perpendicular magnetic field B and a transverse temperature gradient. The
off-diagonal Peltier coefficient (\alpha_{xy}) and the Nernst effect are
evaluated as functions of B and the temperature T. The Nernst effect is found
to exhibit a prominent peak close to the superconductor-insulator transition
(SIT), which becomes progressively enhanced at low T. In addition, we derive a
relation to diamagnetic response: \alpha_{xy}= -M/T_0, where M is the
equilibrium magnetization and T_0 a plasma energy in the superconducting legs.Comment: An extended (and hopefully more comprehensible) version of an earlier
postin
Colored Non-Crossing Euclidean Steiner Forest
Given a set of -colored points in the plane, we consider the problem of
finding trees such that each tree connects all points of one color class,
no two trees cross, and the total edge length of the trees is minimized. For
, this is the well-known Euclidean Steiner tree problem. For general ,
a -approximation algorithm is known, where is the
Steiner ratio.
We present a PTAS for , a -approximation algorithm
for , and two approximation algorithms for general~, with ratios
and
Progression of Patient Cohorting in Response to COVID-19 at the Jefferson Methodist Emergency Department
While COVID-19 and it’s various complications are a source of a substantial number of Emergency Department (ED) visits, many patients still arrive to the ED for non-COVID-19 indications.
Due to pre-existing construction which was halted by the pandemic, external space for a tent configuration was unavailable.
In effort to decrease patient, staff and nurse exposure to COVID, a system of cohorting was created to assure uninterrupted service in a manner as safe as possible for all involved.
Given the uncertainty of patient volumes and the potential for a high burden of disease similar to our colleagues in New York and New Jersey, this system was created in stages to dynamically flex to the needs of the department
Correlated disordered interactions on Potts models
Using a weak-disorder scheme and real-space renormalization-group techniques,
we obtain analytical results for the critical behavior of various q-state Potts
models with correlated disordered exchange interactions along d1 of d spatial
dimensions on hierarchical (Migdal-Kadanoff) lattices. Our results indicate
qualitative differences between the cases d-d1=1 (for which we find nonphysical
random fixed points, suggesting the existence of nonperturbative fixed
distributions) and d-d1>1 (for which we do find acceptable perturbartive random
fixed points), in agreement with previous numerical calculations by Andelman
and Aharony. We also rederive a criterion for relevance of correlated disorder,
which generalizes the usual Harris criterion.Comment: 8 pages, 4 figures, to be published in Physical Review
Simple Wriggling is Hard unless You Are a Fat Hippo
We prove that it is NP-hard to decide whether two points in a polygonal
domain with holes can be connected by a wire. This implies that finding any
approximation to the shortest path for a long snake amidst polygonal obstacles
is NP-hard. On the positive side, we show that snake's problem is
"length-tractable": if the snake is "fat", i.e., its length/width ratio is
small, the shortest path can be computed in polynomial time.Comment: A shorter version is to be presented at FUN 201
- …