1,592 research outputs found
Programa de controle do capim-annoni no Parque Eólico Cerro Chato: diagnóstico e proposições.
Características da invasora e interação com a pastagem natural; A invasão na área de abrangência dos parques eólicos; Adequação do sistema viário para transporte e instalação de aerogeradores; Monitoramento e mapeamento das áreas invadidas nos Parques Eólicos; Percepção do público quanto à invasãobitstream/item/136927/1/Dt-146-online.pd
Derivation of Matrix Product Ansatz for the Heisenberg Chain from Algebraic Bethe Ansatz
We derive a matrix product representation of the Bethe ansatz state for the
XXX and XXZ spin-1/2 Heisenberg chains using the algebraic Bethe ansatz. In
this representation, the components of the Bethe eigenstates are expressed as
traces of products of matrices which act on , the tensor
product of auxiliary spaces. By changing the basis in , we
derive explicit finite-dimensional representations for the matrices. These
matrices are the same as those appearing in the recently proposed matrix
product ansatz by Alcaraz and Lazo [Alcaraz F C and Lazo M J 2006 {\it J. Phys.
A: Math. Gen.} \textbf{39} 11335.] apart from normalization factors. We also
discuss the close relation between the matrix product representation of the
Bethe eigenstates and the six-vertex model with domain wall boundary conditions
[Korepin V E 1982 {\it Commun. Math. Phys.}, \textbf{86} 391.] and show that
the change of basis corresponds to a mapping from the six-vertex model to the
five-vertex model.Comment: 24 pages; minor typos are correcte
Antimicrobial Peptides Pom-1 and Pom-2 from Pomacea poeyana Are Active against Candida auris, C. parapsilosis and C. albicans Biofilms
Recently two peptides isolated from the Cuban freshwater snail Pomacea poeyana (Pilsbry, 1927) were described to have antimicrobial activity against bacterial pathogens. Here we show considerable activities of Pom-1 and Pom-2 to reduce the viability of C. albicans, C. parapsilosis and the less common species C. auris measured as the decrease of metabolic activity in the resazurin reduction assay for planktonic cells. Although these activities were low, Pom-1 and Pom-2 turned out to be highly potent inhibitors of biofilm formation for the three Candida species tested. Whereas Pom-1 was slightly more active against C. albicans and C. parapsilosis as representatives of the more common Candida species Pom-2 showed no preference and was fully active also against biofilms of the more uncommon species C. auris. Pom-1 and Pom-2 may represent promising lead structures for the development of a classical peptide optimization strategy with the realistic aim to further increase antibiofilm properties and other pharmacologic parameters and to generate finally the first antifungal drug with a pronounced dedication against Candida biofilms
Entanglement entropy of two disjoint intervals in c=1 theories
We study the scaling of the Renyi entanglement entropy of two disjoint blocks
of critical lattice models described by conformal field theories with central
charge c=1. We provide the analytic conformal field theory result for the
second order Renyi entropy for a free boson compactified on an orbifold
describing the scaling limit of the Ashkin-Teller (AT) model on the self-dual
line. We have checked this prediction in cluster Monte Carlo simulations of the
classical two dimensional AT model. We have also performed extensive numerical
simulations of the anisotropic Heisenberg quantum spin-chain with tree-tensor
network techniques that allowed to obtain the reduced density matrices of
disjoint blocks of the spin-chain and to check the correctness of the
predictions for Renyi and entanglement entropies from conformal field theory.
In order to match these predictions, we have extrapolated the numerical results
by properly taking into account the corrections induced by the finite length of
the blocks to the leading scaling behavior.Comment: 37 pages, 23 figure
Universal corrections to scaling for block entanglement in spin-1/2 XX chains
We consider the R\'enyi entropies in the one dimensional spin-1/2
Heisenberg XX chain in a magnetic field. The case n=1 corresponds to the von
Neumann ``entanglement'' entropy. Using a combination of methods based on the
generalized Fisher-Hartwig conjecture and a recurrence relation connected to
the Painlev\'e VI differential equation we obtain the asymptotic behaviour,
accurate to order , of the R\'enyi entropies
for large block lengths . For n=1,2,3,10 this constitutes the 3,6,10,48
leading terms respectively. The o(1) contributions are found to exhibit a rich
structure of oscillatory behaviour, which we analyze in some detail both for
finite and in the limit .Comment: 25 pages, 5 figure
Universal parity effects in the entanglement entropy of XX chains with open boundary conditions
We consider the Renyi entanglement entropies in the one-dimensional XX
spin-chains with open boundary conditions in the presence of a magnetic field.
In the case of a semi-infinite system and a block starting from the boundary,
we derive rigorously the asymptotic behavior for large block sizes on the basis
of a recent mathematical theorem for the determinant of Toeplitz plus Hankel
matrices. We conjecture a generalized Fisher-Hartwig form for the corrections
to the asymptotic behavior of this determinant that allows the exact
characterization of the corrections to the scaling at order o(1/l) for any n.
By combining these results with conformal field theory arguments, we derive
exact expressions also in finite chains with open boundary conditions and in
the case when the block is detached from the boundary.Comment: 24 pages, 9 figure
On R\ue9nyi entropies of disjoint intervals in conformal field theory
We study the R\ue9nyi entropies of N disjoint intervals in the conformal field theories describing the free compactified boson and the Ising model. They are computed as the 2N-point function of twist fields, by employing the partition function of the model on a particular class of Riemann surfaces. The results are written in terms of Riemann theta functions. The prediction for the free boson in the decompactification regime is checked against exact results for the harmonic chain. For the Ising model, matrix product state computations agree with the conformal field theory result once the finite size corrections have been taken into account. \ua9 2014 IOP Publishing Ltd and SISSA Medialab srl
Surgical treatment for colorectal cancer: Analysis of the influence of an enhanced recovery programme on long-term oncological outcomes-a study protocol for a prospective, multicentre, observational cohort study
Introduction The evidence currently available from enhanced recovery after surgery (ERAS) programmes concerns their benefits in the immediate postoperative period, but there is still very little evidence as to whether their correct implementation benefits patients in the long term. The working hypothesis here is that, due to the lower response to surgical aggression and lower rates of postoperative complications, ERAS protocols can reduce colorectal cancer-related mortality. The main objective of this study is to analyse the impact of an ERAS programme for colorectal cancer on 5-year survival. As secondary objectives, we propose to analyse the weight of each of the predefined items in the oncological results as well as the quality of life. Methods and analysis A multicentre prospective cohort study was conducted in patients older than 18 years of age who are scheduled to undergo surgery for colorectal cancer. The study involved 12 hospitals with an implemented enhanced recovery protocol according to the guidelines published by the Spanish National Health Service. The intervention group includes patients with a minimum implementation level of 70%, and the control group includes those who fail to reach this level. Compliance will be studied using 18 key performance indicators, and the results will be analysed using cancer survival indicators, including overall survival, cancer-specific survival and relapse-free survival. The time to recurrence, perioperative morbidity and mortality, hospital stay and quality of life will also be studied, the latter using the validated EuroQol Five questionnaire. The propensity index method will be used to create comparable treatment and control groups, and a multivariate regression will be used to study each variable. The Kaplan-Meier estimator will be used to estimate survival and the log-rank test to make comparisons. A p value of less than 0.05 (two-tailed) will be considered to be significant. Ethics and dissemination Ethical approval for this study was obtained from the Aragon Ethical Committee (C.P.-C.I. PI20/086) on 4 March 2020. The findings of this study will be submitted to peer-reviewed journals (BMJ Open, JAMA Surgery, Annals of Surgery, British Journal of Surgery). Abstracts will be submitted to relevant national and international meetings.The present research study was awarded a Ministerio de Ciencia e
Innovación health research project grant (PI19/00291) from the Carlos III Institute
of the Spanish National Health Service as part of the 2019 call for Strategic Action
in Health
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