Combined potential and spin impurity scattering in cuprates

We present a theory of combined nonmagnetic and magnetic impurity scattering in anisotropic superconductors accounting for the momentum-dependent impurity potential. Applying the model to the d-wave superconducting state, we obtain a quantitative agreement with the initial suppression of the critical temperature due to Zn and Ni substitutions as well as electron irradiation defects in the cuprates. We suggest, that the unequal pair-breaking effect of Zn and Ni may be related to a different nature of the magnetic moments induced by these impurities.Comment: 5 pages, 3 tables, RevTex, to be published in Phys. Rev.

Antiferromagnetic Interactions and the Superconducting Gap Function

Spin-fluctuation-mediated superconductivity is conventionally associated with d_{x^2-y^2} pairing. We show that a generalized model of antiferromagnetic spin fluctuations in three dimensions may also yield a state with formal ``s-wave'' (A_{1g}) symmetry but with line nodes at k_z \approx \pm \pi / 2c. We study this new state within both BCS and Eliashberg theories using a realistic band structure and find that it is more stable than the d_{x^2-y^2} (B_{1g}) state over a wide range of parameters. Thus, models of spin-fluctuation-mediated superconductivity must consider both possibilities on an equal footing.Comment: 4 pages, RevTeX with psfig, 2 PostScript figures included in compressed form, one color PostScript figure available by request to [email protected] or [email protected]. Minor changes and updated references from original postin

A educação na 'Constelação pós-nacional': o enfraquecimento da legitimação e do controle democrático, "expertocrático" e ético-profissional

The article discusses current transformations in the education systems worldwide. Focusing on the European Union (EU) and the Organisation for Economic Cooperation and Development (OECD) as policy actors, it argues that these transformations imply a triple economization of education policy which can be observed at all levels of the education sector. The increasing importance of these organizations in educational issues marks a transition to a "postnational constellation" also in the education field insofar as the national educational sovereignty is being at least readjusted. The economization of education policy is however not restricted to bringing education closer to the needs of the economy and to turning its services into tradable goods. Rather, it also impinges on the operative level of education. A logics of production is being implemented in the self-description of the institutions of the education system, which are no longer bureaucratically administered establishments, but are rather conceived of as managerially conducted production business in which entrepreneurial action is needed. This new governance raises the problem of democratic legitimation of political decisions which ideally combines three elements: democratic, expertocratic, and ethico-professional. The article discusses the consequences of a shift in the balance of the three components with reference to Germany.O presente artigo discute as atuais transformações nos sistemas educacionais em todo o mundo. Tendo como foco a União Europeia (UE) e a Organização para a Cooperação e o Desenvolvimento Econômico (OCDE) como atores de políticas, seu argumento é que tais transformações implicam uma tripla "economização" da política educacional, que pode ser constatada em todos os níveis da área educacional. A importância cada vez maior dessas organizações nas questões educacionais configura uma transição para uma "constelação pós-nacional" também na área educacional, na medida em que a soberania educacional nacional está, no mínimo, passando por reajustes. No entanto, a "economização" das políticas educacionais não se limita a aproximar a educação das necessidades da economia e a transformar seus serviços em mercadorias comercializáveis. Ela também afeta o nível operacional da educação. Uma lógica de produção está sendo implementada na descrição realizada pelas próprias instituições do sistema educacional, que deixaram de ser estabelecimentos burocraticamente administrados para ser concebidos como uma atividade comercial gerencialmente controlada, uma atividade na qual uma ação empresarial se faz necessária. Esse novo tipo de administração faz surgir o problema da legitimação democrática das decisões políticas que, em termos ideais, combina três elementos: o democrático, o "expertocrático" e o ético-profissional. O artigo discute as consequências de uma mudança no equilíbrio desses três elementos no caso da Alemanha

The helicity amplitudes A1/2_{1/2} and A3/2_{3/2} for the D13(1520)_{13}(1520) resonance obtained from the γ⃗p⃗→pπ0\vec{\gamma} \vec{p} \to p \pi^0 reaction}

The helicity dependence of the $\vec{\gamma} \vec{p} \to p \pi^0$ reaction has been measured for the first time in the photon energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4$\pi$-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. These data are predominantly sensitive to the $D_{13}(1520)$ resonance and are used to determine its parameters.Comment: 5 pages, 4 figure

First measurement of the Gerasimov-Drell-Hearn integral for Hydrogen from 200 to 800 MeV

A direct measurement of the helicity dependence of the total photoabsorption cross section on the proton was carried out at MAMI (Mainz) in the energy range 200 < E_gamma < 800 MeV. The experiment used a 4$\pi$ detection system, a circularly polarized tagged photon beam and a frozen spin target. The contributions to the Gerasimov-Drell-Hearn sum rule and to the forward spin polarizability $\gamma_0$ determined from the data are 226 \pm 5 (stat)\pm 12(sys) \mu b and -187 \pm 8 (stat)\pm 10(sys)10^{-6} fm^4, respectively, for 200 < E_\gamma < 800 MeV.Comment: 6 pages, 3 figures, 3 table

Faithful Squashed Entanglement

Squashed entanglement is a measure for the entanglement of bipartite quantum states. In this paper we present a lower bound for squashed entanglement in terms of a distance to the set of separable states. This implies that squashed entanglement is faithful, that is, strictly positive if and only if the state is entangled. We derive the bound on squashed entanglement from a bound on quantum conditional mutual information, which is used to define squashed entanglement and corresponds to the amount by which strong subadditivity of von Neumann entropy fails to be saturated. Our result therefore sheds light on the structure of states that almost satisfy strong subadditivity with equality. The proof is based on two recent results from quantum information theory: the operational interpretation of the quantum mutual information as the optimal rate for state redistribution and the interpretation of the regularised relative entropy of entanglement as an error exponent in hypothesis testing. The distance to the set of separable states is measured by the one-way LOCC norm, an operationally-motivated norm giving the optimal probability of distinguishing two bipartite quantum states, each shared by two parties, using any protocol formed by local quantum operations and one-directional classical communication between the parties. A similar result for the Frobenius or Euclidean norm follows immediately. The result has two applications in complexity theory. The first is a quasipolynomial-time algorithm solving the weak membership problem for the set of separable states in one-way LOCC or Euclidean norm. The second concerns quantum Merlin-Arthur games. Here we show that multiple provers are not more powerful than a single prover when the verifier is restricted to one-way LOCC operations thereby providing a new characterisation of the complexity class QMA.Comment: 24 pages, 1 figure, 1 table. Due to an error in the published version, claims have been weakened from the LOCC norm to the one-way LOCC nor

Synthesis and Characterization of Ag/ZnO Nanoparticles for Bacteria Disinfection in Water.

peer reviewedIn this study, two green synthesis routes were used for the synthesis of Ag/ZnO nanoparticles, using cassava starch as a simple and low-cost effective fuel and Aloe vera as a reducing and stabilizing agent. The Ag/ZnO nanoparticles were characterized and used for bacterial disinfection of lake water contaminated with Escherichia coli (E. coli). Characterization indicated the formation of a face-centered cubic structure of metallic silver nanoparticles with no insertion of Ag into the ZnO hexagonal wurtzite structure. Physicochemical and bacteriological analyses described in "Standard Methods for the Examination of Water and Wastewater" were used to evaluate the efficiency of the treatment. In comparison to pure ZnO, the synthesized Ag/ZnO nanoparticles showed high efficiencies against Escherichia coli (E. coli) and general coliforms present in the lake water. These pathogens were absent after treatment using Ag/ZnO nanoparticles. The results indicate that Ag/ZnO nanoparticles synthesized via green chemistry are a promising candidate for the treatment of wastewaters contaminated by bacteria, due to their facile preparation, low-cost synthesis, and disinfection efficiency

Enhanced Recovery After Surgery (ERAS) for gastrointestinal surgery, part 2:consensus statement for anaesthesia practice

Background The present interdisciplinary consensus review proposes clinical considerations and recommendations for anaesthetic practice in patients undergoing gastrointestinal surgery with an Enhanced Recovery after Surgery (ERAS) programme. Methods Studies were selected with particular attention being paid to meta-analyses, randomized controlled trials and large prospective cohort studies. For each item of the perioperative treatment pathway, available English-language literature was examined and reviewed. The group reached a consensus recommendation after critical appraisal of the literature. Results This consensus statement demonstrates that anaesthesiologists control several preoperative, intraoperative and postoperative ERAS elements. Further research is needed to verify the strength of these recommendations. Conclusions Based on the evidence available for each element of perioperative care pathways, the Enhanced Recovery After Surgery (ERAS ®) Society presents a comprehensive consensus review, clinical considerations and recommendations for anaesthesia care in patients undergoing gastrointestinal surgery within an ERAS programme. This unified protocol facilitates involvement of anaesthesiologists in the implementation of the ERAS programmes and allows for comparison between centres and it eventually might facilitate the design of multi-institutional prospective and adequately powered randomized trials