Quasiparticle spectral weights of Gutzwiller-projected high T_c superconductors

We analyze the electronic Green's functions in the superconducting ground state of the t-J model using Gutzwiller-projected wave functions, and compare them to the conventional BCS form. Some of the properties of the BCS state are preserved by the projection: the total spectral weight is continuous around the quasiparticle node and approximately constant along the Fermi surface. On the other hand, the overall spectral weight is reduced by the projection with a momentum-dependent renormalization, and the projection produces electron-hole asymmetry in renormalization of the electron and hole spectral weights. The latter asymmetry leads to the bending of the effective Fermi surface which we define as the locus of equal electron and hole spectral weight.Comment: 6 pages, 5 figures; x-labels on Figs. 1 and 2 corrected, footnote on particle number corrected, references adde

SIMULATION OPTIMIZATION FOR THE INVENTORY MANAGEMENT OF HEALTHCARE SUPPLIES

[EN] This article covers the inventory management of healthcare supplies problem. Based on the mathematical programming model set out by [1], a causal model and a flow chart were developed to outline the simulation model, which was to be later applied to a highly specialized medical institution that performs high-risk heart surgery, such as catheterizations and angioplasties. With this simulation model, a purchases plan with 21 healthcare supplies was obtained that contemplates all the problem¿s restrictions: purchasing policy (safety stock, available budget); the warehouse¿s physical reality (warehouse capacity); characteristics of supplies (useful life, service level); and suppliers (price, capacity and size of lots or rounding value). Different indicators were also considered, such as service levels, costs of purchases, stockouts costs and inventory maintenance costs. The results obtained with the simulation model came very close to the mathematical programming results, but the computing times were considerably shorter.This work was supported by the Spanish Ministry of Science, Innovation and Universities project entitled 'Optimisation of zero-defects production technologies enabling supply chains 4.0 (CADS4.0)' (RTI2018-101344-B-I00) and the Operational Program of the European Regional Development Fund (ERDF) of the Valencian Community 2014-2020 IDIFEDER/2018/025.Buschiazzo, M.; Mula, J.; Campuzano-Bolarin, F. (2020). SIMULATION OPTIMIZATION FOR THE INVENTORY MANAGEMENT OF HEALTHCARE SUPPLIES. International Journal of Simulation Modelling. 19(2):255-266. https://doi.org/10.2507/IJSIMM19-2-514S25526619

Programa Jatropha Colombia :genética, agronomía, poscosecha y desarrollo agroindustrial del piñon de Colombia (2008-2012)

A partir de las experiencias de Asia, África y Centro América en la especie Jatropha curcas, Corpoica ha estructurado el Programa de Investigación en Jatropha. Este programa pretende identificar, en el corto plazo, las variedades más sobresalientes desde el punto de vista agronómico y de calidad del aceite, de un grupo de materiales comerciales introducidos en el país y que fueron colectadas en diferentes zonas agroecológicas. A partir de la información generada, será posible efectuar recomendaciones de carácter regional acerca de los materiales con mejor comportamiento, de modo que sirvan al sector productivo para establecer plantaciones comerciales

Renormalization of spectral lineshape and dispersion below Tc in Bi2Sr2CaCu2O8+d

Angle-resolved photoemission (ARPES) data in the superconducting state of Bi2Sr2CaCu2O8+d show a kink in the dispersion along the zone diagonal, which is related via a Kramers-Kronig analysis to a drop in the low-energy scattering rate. As one moves towards (pi,0), this kink evolves into a spectral dip. The occurrence of these anomalies in the dispersion and lineshape throughout the zone indicate the presence of a new energy scale in the superconducting state.Comment: New Figure 3 with expanded discussio

Momentum dependence of the superconducting gap in NdFeAsO1-xFx single crystals measured by angle resolved photoemission spectroscopy

We use angle resolved photoemission spectroscopy (ARPES) to study the momentum dependence of the superconducting gap in NdFeAsO1-xFx single crystals. We find that the Gamma hole pocket is fully gapped below the superconducting transition temperature. The value of the superconducting gap is 15 +- 1.5 meV and its anisotropy around the hole pocket is smaller than 20% of this value. This is consistent with an isotropic or anisotropic s-wave symmetry of the order parameter or exotic d-wave symmetry with nodes located off the Fermi surface sheets. This is a significant departure from the situation in the cuprates, pointing to possibility that the superconductivity in the iron arsenic based system arises from a different mechanism.Comment: 4 pages, 3 figure

Doping dependence of superconducting gap in YBa_2Cu_3O_y from universal heat transport

Thermal transport in the T -> 0 limit was measured as a function of doping in high-quality single crystals of the cuprate superconductor YBa_2Cu_3O_y. The residual linear term kappa_0/T is found to decrease as one moves from the overdoped regime towards the Mott insulator region of the phase diagram. The doping dependence of the low-energy quasiparticle gap extracted from kappa_0/T is seen to scale closely with that of the pseudogap, arguing against a non-superconducting origin for the pseudogap. The presence of a linear term for all dopings is evidence against the existence of a quantum phase transition to an order parameter with a complex (ix) component.Comment: 2 pages, 2 figures, submitted to M2S-Rio 2003 Proceeding

Cellular, molecular and functional characterisation of YAC transgenic mouse models of Friedreich Ataxia

Copyright © 2014 Anjomani Virmouni et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This article has been made available through the Brunel Open Access Publishing Fund.Background - Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder, caused by a GAA repeat expansion mutation within intron 1 of the FXN gene. We have previously established and performed preliminary characterisation of several human FXN yeast artificial chromosome (YAC) transgenic FRDA mouse models containing GAA repeat expansions, Y47R (9 GAA repeats), YG8R (90 and 190 GAA repeats) and YG22R (190 GAA repeats). Methodology/Principal Findings - We now report extended cellular, molecular and functional characterisation of these FXN YAC transgenic mouse models. FXN transgene copy number analysis of the FRDA mice demonstrated that the YG22R and Y47R lines each have a single copy of the FXN transgene while the YG8R line has two copies. Single integration sites of all transgenes were confirmed by fluorescence in situ hybridisation (FISH) analysis of metaphase and interphase chromosomes. We identified significant functional deficits, together with a degree of glucose intolerance and insulin hypersensitivity, in YG8R and YG22R FRDA mice compared to Y47R and wild-type control mice. We also confirmed increased somatic GAA repeat instability in the cerebellum and brain of YG22R and YG8R mice, together with significantly reduced levels of FXN mRNA and protein in the brain and liver of YG8R and YG22R compared to Y47R. Conclusions/Significance - Together these studies provide a detailed characterisation of our GAA repeat expansion-based YAC transgenic FRDA mouse models that will help investigations of FRDA disease mechanisms and therapy.European Union, Ataxia UK and FARA