74 research outputs found
Interplay between Zamolodchikov-Faddeev and Reflection-Transmission algebras
We show that a suitable coset algebra, constructed in terms of an extension
of the Zamolodchikov-Faddeev algebra, is homomorphic to the
Reflection-Transmission algebra, as it appears in the study of integrable
systems with impurity.Comment: 8 pages; a misprint in eq. (2.14) and (2.15) has been correcte
On String S-matrix, Bound States and TBA
The study of finite J effects for the light-cone AdS superstring by means of
the Thermodynamic Bethe Ansatz requires an understanding of a companion 2d
theory which we call the mirror model. It is obtained from the original string
model by the double Wick rotation. The S-matrices describing the scattering of
physical excitations in the string and mirror models are related to each other
by an analytic continuation. We show that the unitarity requirement for the
mirror S-matrix fixes the S-matrices of both theories essentially uniquely. The
resulting string S-matrix S(z_1,z_2) satisfies the generalized unitarity
condition and, up to a scalar factor, is a meromorphic function on the elliptic
curve associated to each variable z. The double Wick rotation is then
accomplished by shifting the variables z by quarter of the imaginary period of
the torus. We discuss the apparent bound states of the string and mirror
models, and show that depending on a choice of the physical region there are
one, two or 2^{M-1} solutions of the M-particle bound state equations sharing
the same conserved charges. For very large but finite values of J, most of
these solutions, however, exhibit various signs of pathological behavior. In
particular, they might receive a finite J correction to their energy which is
complex, or the energy correction might exceed corrections arising due to
finite J modifications of the Bethe equations thus making the asymptotic Bethe
ansatz inapplicable.Comment: 77 pages, 6 figures, v2: the statement about the periodicity
condition for mirror fermions corrected; typos corrected; references added,
v3: misprints correcte
Spontaneous symmetry breaking in the non-linear Schrodinger hierarchy with defect
We introduce and solve the one-dimensional quantum non-linear Schrodinger
(NLS) equation for an N-component field defined on the real line with a defect
sitting at the origin. The quantum solution is constructed using the quantum
inverse scattering method based on the concept of Reflection-Transmission (RT)
algebras recently introduced. The symmetry of the model is generated by the
reflection and transmission defect generators defining a defect subalgebra. We
classify all the corresponding reflection and transmission matrices. This
provides the possible boundary conditions obeyed by the canonical field and we
compute these boundary conditions explicitly. Finally, we exhibit a phenomenon
of spontaneous symmetry breaking induced by the defect and identify the
unbroken generators as well as the exact remaining symmetry.Comment: discussion on symmetry breaking has been improved and examples adde
Yang-Mills Correlation Functions from Integrable Spin Chains
The relation between the dilatation operator of N=4 Yang-Mills theory and
integrable spin chains makes it possible to compute the one-loop anomalous
dimensions of all operators in the theory. In this paper we show how to apply
the technology of integrable spin chains to the calculation of Yang-Mills
correlation functions by expressing them in terms of matrix elements of spin
operators on the corresponding spin chain. We illustrate this method with
several examples in the SU(2) sector described by the XXX_1/2 chain.Comment: 27 pages, 3 figures, harvma
Lipopolysaccharide O-Antigen Biosynthesis in Shigella-Dysenteriae Serotype 1 - Analysis of the Plasmid-Carried Rfp Determinant
The impact of provider availability and legal restrictions on the demand for abortions by young women
Which States Will Restrict Abortions? Predictions from Votes in the House of Representatives
In response to the Supreme Court's rulings in Webster v. Reproductive Services and Planned Parenthood of Southeastern Pennsylvania v. Casey, which increased the ability of states to restrict abortions, many state legislatures have reexamined their abortion policies. Several recent studies use a variety of methods to predict whether states will restrict abortion access. These studies have utilized congressional votes on abortion legislation, past state laws restricting abortions, or current attitudes by state legislators and governors. Each method has its merits and limitations. This paper uses recent votes in the states' House of Representatives pertaining to abortion issues to predict the likelihood of significant abortion restrictions. These results are compared with rankings from other recent studies. Copyright 1994 by The Policy Studies Organization.
Von der Entwicklung bis zur modellhaften Implementierung eines Konzeptes zum Entlassmanagement - ein Ergebnistransfer am Beispiel der Innovationsfondsprojekte EMSE und USER
Impact of epicardial adipose tissue volume upon left ventricular dysfunction in patients with mild-to-moderate aortic stenosis: A post-hoc analysis.
BACKGROUND:Aortic stenosis (AS) may lead to diastolic dysfunction and later on heart failure (HF) with preserved left ventricular ejection fraction (HFpEF) via increased afterload and left-ventricular (LV) hypertrophy. Since epicardial adipose tissue (EAT) is a metabolically active fat depot that is adjacent to the myocardium and can influence cardiomyocytes and LV function via secretion of proinflammatory cytokines, we hypothesized that high amounts of EAT, as assessed by computed tomography (CT), may aggravate the development and severity of LV hypertrophy and diastolic dysfunction in the context of AS. METHODS:We studied 50 patients (mean age 71 ± 9 years; 9 women) in this preliminary study with mild or moderate AS and mild to severe LV diastolic dysfunction (LVDD), diagnosed by echocardiography, who underwent non-contrast cardiac CT and echocardiography. EAT parameters were measured on 2nd generation dual source CT. Conventional two-dimensional echocardiography and Tissue Doppler Imaging (TDI) was performed to assess LV function and to derive myocardial straining parameter. All patients had a preserved LV ejection fraction > 50%. Data was analysed using Pearson's correlation. RESULTS:Only weak correlation was found between EAT volume or density and E/é ratio as LVDD marker (r = -.113 p = .433 and r = .260, p = .068 respectively). Also, EAT volume or density were independent from Global Strain Parameters (r = 0.058 p = .688 and r = -0.207 p = .239). E/é ratio was strongly associated with LVDD (r = .761 p≤0.0001) and Strain Parameters were moderately associated with LV Ejection Fraction (r = -.669 p≤0.001 and r = -.454 P≤0.005). CONCLUSIONS:In this preliminary study in patients with AS, the EAT volume and density as assessed by CT correlated only weakly with LVDD, as expressed by the commonly used E/é ratio, and with LV strain function. Hence, measuring EAT volume and density may neither contribute to the prediction nor upon the severity of LVDD, respectively
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