5,194 research outputs found
On the existence of self-similar spherically symmetric wave maps coupled to gravity
We present a detailed analytical study of spherically symmetric self-similar
solutions in the SU(2) sigma model coupled to gravity. Using a shooting
argument we prove that there is a countable family of solutions which are
analytic inside the past self-similarity horizon. In addition, we show that for
sufficiently small values of the coupling constant these solutions possess a
regular future self-similarity horizon and thus are examples of naked
singularities. One of the solutions constructed here has been recently found as
the critical solution at the threshold of black hole formation.Comment: 15 pages, LaTe
On the equivalence of two deformation schemes in quantum field theory
Two recent deformation schemes for quantum field theories on the
two-dimensional Minkowski space, making use of deformed field operators and
Longo-Witten endomorphisms, respectively, are shown to be equivalent.Comment: 14 pages, no figure. The final version is available under Open
Access. CC-B
Warped Convolutions, Rieffel Deformations and the Construction of Quantum Field Theories
Warped convolutions of operators were recently introduced in the algebraic
framework of quantum physics as a new constructive tool. It is shown here that
these convolutions provide isometric representations of Rieffel's strict
deformations of C*-dynamical systems with automorphic actions of R^n, whenever
the latter are presented in a covariant representation. Moreover, the device
can be used for the deformation of relativistic quantum field theories by
adjusting the convolutions to the geometry of Minkowski space. The resulting
deformed theories still comply with pertinent physical principles and their
Tomita-Takesaki modular data coincide with those of the undeformed theory; but
they are in general inequivalent to the undeformed theory and exhibit different
physical interpretations.Comment: 34 page
Delay-Exponent of Bilayer Anytime Code
In this paper, we study the design and the delay-exponent of anytime codes
over a three terminal relay network. We propose a bilayer anytime code based on
anytime spatially coupled low-density parity-check (LDPC) codes and investigate
the anytime characteristics through density evolution analysis. By using
mathematical induction technique, we find analytical expressions of the
delay-exponent for the proposed code. Through comparison, we show that the
analytical delay-exponent has a close match with the delay-exponent obtained
from numerical results.Comment: Accepted for presentation in ITW-2014. 5 Pages, 3 Figure
Finite Length Analysis of LDPC Codes
In this paper, we study the performance of finite-length LDPC codes in the
waterfall region. We propose an algorithm to predict the error performance of
finite-length LDPC codes over various binary memoryless channels. Through
numerical results, we find that our technique gives better performance
prediction compared to existing techniques.Comment: Submitted to WCNC 201
Deformations of Fermionic Quantum Field Theories and Integrable Models
Considering the model of a scalar massive Fermion, it is shown that by means
of deformation techniques it is possible to obtain all integrable quantum field
theoretic models on two-dimensional Minkowski space which have factorizing
S-matrices corresponding to two-particle scattering functions S_2 satisfying
S_2(0) = -1. Among these models there is for example the Sinh-Gordon model. Our
analysis provides a complement to recent developments regarding deformations of
quantum field theories. The deformed model is investigated also in higher
dimensions. In particular, locality and covariance properties are analyzed.Comment: 20 page
An operator expansion for integrable quantum field theories
A large class of quantum field theories on 1+1 dimensional Minkowski space,
namely, certain integrable models, has recently been constructed rigorously by
Lechner. However, the construction is very abstract and the concrete form of
local observables in these models remains largely unknown. Aiming for more
insight into their structure, we establish a series expansion for observables,
similar but not identical to the well-known form factor expansion. This
expansion will be the basis for a characterization and explicit construction of
local observables, to be discussed elsewhere. Here, we establish the expansion
independent of the localization aspect, and analyze its behavior under
space-time symmetries. We also clarify relations with deformation methods in
quantum field theory, specifically, with the warped convolution in the sense of
Buchholz and Summers.Comment: minor corrections and clarifications, as published in J. Phys A; 24
page
String-- and Brane--Localized Causal Fields in a Strongly Nonlocal Model
We study a weakly local, but nonlocal model in spacetime dimension
and prove that it is maximally nonlocal in a certain specific quantitative
sense. Nevertheless, depending on the number of dimensions , it has
string--localized or brane--localized operators which commute at spatial
distances. In two spacetime dimensions, the model even comprises a covariant
and local subnet of operators localized in bounded subsets of Minkowski space
which has a nontrivial scattering matrix. The model thus exemplifies the
algebraic construction of local observables from algebras associated with
nonlocal fields.Comment: paper re-written with a change of emphasis and new result
Rebutting Obviousness in the Pharmaceutical Industry: Secondary Considerations of Analogs
Pharmaceutical companies depend on patent protection to recuperate the high costs of research and development. In regards to the patentability of structurally related compounds, the courts must decide whether a compound is obvious in view of its structurally similar prior art. In general, a compound is non-obvious over the structurally related prior art if the compound exhibits unexpected results. However, placing primary emphasis on a compound\u27s unexpected properties is out of step with the realities of drug development. For example, during drug development, chemists will modify a compound\u27s structure until they produce a compound that exhibits optimal pharmakinetic properties. This iterative process relies on the perseverance of scientists to pave the road to drug discovery-not unexpected results.
This Note advocates for the elevation of the failure of others to make a drug that benefits society and the long-felt but unmet need for that treatment in the obviousness inquiry. These factors highlight the underappreciated realities of the drug discovery process, the immense effort that precedes a drug\u27s delivery to market, and the profound effect pharmaceuticals can have on disease treatment. In giving greater credence to the failure of others to develop a drug and the unmet need for that treatment, courts can resolve the current disconnect between the laboratory and patent law. By rewarding innovators that embark on a logical research plan that ends in the development of a beneficial drug, patent law will encourage companies to invest in drug development and produce drugs that benefit society
- …