Quantum Quench in the Transverse Field Ising chain I: Time evolution of order parameter correlators

We consider the time evolution of order parameter correlation functions after a sudden quantum quench of the magnetic field in the transverse field Ising chain. Using two novel methods based on determinants and form factor sums respectively, we derive analytic expressions for the asymptotic behaviour of one and two point correlators. We discuss quenches within the ordered and disordered phases as well as quenches between the phases and to the quantum critical point. We give detailed account of both methods.Comment: 65 pages, 21 figures, some typos correcte

Diversidade de bactérias diazotróficas endofíticas de milho em cultivos convencional e agroecológico.

Diferentes gêneros de bactérias diazotróficas, além de fixar N2 atmosférico, também promovem o crescimento de plantas pela produção de hormônios vegetais e disponibilização de outros nutrientes como o fósforo. O objetivo deste trabalho foi isolar e identificar bactérias diazotróficas endofíticas de milho (Zea mays L.) sob plantio direto e convencional, em sistema agroecológico e convencional. O isolamento foi realizado em meios de cultura livres de N (LGI, JNFb e JMV), totalizando 86 isolados. Por meio do sequenciamento do gene 16S DNAr foram identificadas bactérias dos gêneros Burkholderia spp., Agrobacterium spp., Enterobacter spp., Stenotrophomonas spp., Rhizobium spp., Pseudoxanthomonas sp., Microbacterium sp., Sphingomonas sp., Klebsiella spp., Bacillus sp., Xanthomonas sp., Leclercia sp., Pantoea sp., Dyella sp. e Pseudomonas spp. O gênero Burkholderia representou 30% dos isolados, seguido de Agrobacterium com 14%. O milho sob cultivo agroecológico apresentou mais isolados de bactérias endofíticas (24%). Assim, sistemas menos sujeitos a ações antrópicas parecem ser hotspots de diversidade para isolamento de microrganismos com potencial para promoção de crescimento vegetal.Fertbio

Corrections to scaling in entanglement entropy from boundary perturbations

We investigate the corrections to scaling of the Renyi entropies of a region of size l at the end of a semi-infinite one-dimensional system described by a conformal field theory when the corrections come from irrelevant boundary operators. The corrections from irrelevant bulk operators with scaling dimension x have been studied by Cardy and Calabrese (2010), and they found not only the expected corrections of the form l^(4-2x) but also unusual corrections that could not have been anticipated by finite-size scaling arguments alone. However, for the case of perturbations from irrelevant boundary operators we find that the only corrections that can occur to leading order are of the form l^(2-2x_b) for boundary operators with scaling dimension x_b < 3/2, and l^(-1) when x_b > 3/2. When x_b=3/2 they are of the form l^(-1)log(l). A marginally irrelevant boundary perturbation will give leading corrections going as log(l)^(-3). No unusual corrections occur when perturbing with a boundary operator.Comment: 8 pages. Minor improvements and updated references. Published versio

Entropy inequalities from reflection positivity

We investigate the question of whether the entropy and the Renyi entropies of the vacuum state reduced to a region of the space can be represented in terms of correlators in quantum field theory. In this case, the positivity relations for the correlators are mapped into inequalities for the entropies. We write them using a real time version of reflection positivity, which can be generalized to general quantum systems. Using this generalization we can prove an infinite sequence of inequalities which are obeyed by the Renyi entropies of integer index. There is one independent inequality involving any number of different subsystems. In quantum field theory the inequalities acquire a simple geometrical form and are consistent with the integer index Renyi entropies being given by vacuum expectation values of twisting operators in the Euclidean formulation. Several possible generalizations and specific examples are analyzed.Comment: Significantly enlarged and corrected version. Counterexamples found for the most general form of the inequalities. V3: minor change

Quasi-local conserved charges and spin transport in spin-1 integrable chains

We consider the integrable one-dimensional spin-1 chain defined by the Zamolodchikov-Fateev (ZF) Hamiltonian. The latter is parametrized, analogously to the XXZ spin-1/2 model, by a continuous anisotropy parameter and at the isotropic point coincides with the well-known spin-1 Babujian-Takhtajan Hamiltonian. Following a procedure recently developed for the XXZ model, we explicitly construct a continuous family of quasi-local conserved operators for the periodic spin-1 ZF chain. Our construction is valid for a dense set of commensurate values of the anisotropy parameter in the gapless regime where the isotropic point is excluded. Using the Mazur inequality, we show that, as for the XXZ model, these quasi-local charges are enough to prove that the high-temperature spin Drude weight is non-vanishing in the thermodynamic limit, thus establishing ballistic spin transport at high temperature

Carbono orgânico e atributos microbiológicos em solo agrícola com diferentes níveis de produtividade de soja em sistema de plantio direto.

Atributos microbiológicos e bioquímicos do solo são geralmente negligenciados ao se relacionar a fertilidade do solo e a produtividade das culturas, em que o carbono orgânico (C) apresenta papel chave. O objetivo deste trabalho foi avaliar alguns bioindicadores de qualidade de solo e relacioná-los com o teor de C do solo em áreas de produção comercial com diferentes níveis de produtividade de soja sob sistema de plantio direto. Amostras compostas de solo foram obtidas na profundidade 0-10 cm, em 6 áreas agrícolas em Ponta Grossa, PR. Os dados foram submetidos à análise de correlação de Pearson e regressão múltipla. A regressão múltipla mostrou que a produtividade é influenciada principalmente pelo teor de C orgânico no solo, e a correlação simples de Pearson mostrou-se significativa entre o C orgânico e a biomassa microbiana de carbono (BMC), biomassa microbiana de nitrogênio (BMN), capacidade de troca de cátions (CTC) e atividades enzimáticas. Conclui-se que há uma relação entre a produtividade de grãos de soja e a atividade microbiana no solo, em que o C orgânico apresenta papel chave.Fertbio

Robotic treatment of colorectal endometriosis: technique, feasibility and short-term results

background: Deep infiltrating endometriosis (DIE) is a complex disease that impairs the quality of life and the fertility of women. Since a medical approach is often insufficient, a minimally invasive approach is considered the gold standard for complete disease excision. Roboticassisted surgery is a revolutionary approach, with several advantages compared with traditional laparoscopic surgery. methods: From March 2010 to May 2011, we performed 22 consecutive robotic-assisted complete laparoscopic excisions of DIE endometriosis with colorectal involvement. All clinical data were collected by our team and all patients were interviewed preoperatively and 3 and 6 months post-operatively and yearly thereafter regarding endometriosis-related symptoms. Dysmenorrhoea, dyschezia, dyspareunia and dysuria were evaluated with a 10-point analog rating scale. results: There were 12 patients, with a median larger endometriotic nodule of 35 mm, who underwent segmental resection, and 10 patients, with a median larger endometriotic nodule of 30 mm, who underwent complete nodule debulking by colorectal wall-shaving technique. No laparotomic conversions were performed, nor was any blood transfusion necessary. No intra-operative complications were observed and, in particular, there were no inadvertent rectal perforations in any of the cases treated by the shaving technique. None of the patients had ileostomy or colostomy. No major post-operative complications were observed, except one small bowel occlusion 14 days post-surgery that was resolved in 3 days with medical treatment. Post-operatively, a statistically significant improvement of patient symptoms was shown for all the investigated parameters. conclusions: To our knowledge, this is the first study reporting the feasibility and short-term results and complications of laparoscopic robotic-assisted treatment of DIE with colorectal involvement.We demonstrate that this approach is feasible and safe, without conversion to laparotomy