Cooper pairs as bosons

Although BCS pairs of fermions are known not to obey Bose-Einstein (BE) commutation relations nor BE statistics, we show how Cooper pairs (CPs), whether the simple original ones or the CPs recently generalized in a many-body Bethe-Salpeter approach, being clearly distinct from BCS pairs at least obey BE statistics. Hence, contrary to widespread popular belief, CPs can undergo BE condensation to account for superconductivity if charged, as well as for neutral-atom fermion superfluidity where CPs, but uncharged, are also expected to form.Comment: 8 pages, 2 figures, full biblio info adde

Harmonically Trapped Quantum Gases

We solve the problem of a Bose or Fermi gas in $d$-dimensions trapped by $\delta \leq d$ mutually perpendicular harmonic oscillator potentials. From the grand potential we derive their thermodynamic functions (internal energy, specific heat, etc.) as well as a generalized density of states. The Bose gas exhibits Bose-Einstein condensation at a nonzero critical temperature $T_{c}$ if and only if $d+\delta >2$, and a jump in the specific heat at $T_{c}$ if and only if $d+\delta >4$. Specific heats for both gas types precisely coincide as functions of temperature when $d+\delta =2$. The trapped system behaves like an ideal free quantum gas in $d+\delta$ dimensions. For $\delta =0$ we recover all known thermodynamic properties of ideal quantum gases in $d$ dimensions, while in 3D for $\delta =$ 1, 2 and 3 one simulates behavior reminiscent of quantum {\it wells, wires}and{\it dots}, respectively.Comment: 14 pages including 3 figures and 3 table

Multi-connected Momentum Distribution and Fermion Condensation

The structure of the ground state beyond the instability point of the quasiparticle system with Fermi-step momentum distribution is studied within the model of a Fermi liquid with a strong repulsive interaction. A ground state rearrangement occurs as the interaction strength is increased beyond a definite critical value. Numerical investigation of the initial stage of this structural transition shows that there are two temperature regions, corresponding to different scenarios of the rearrangement. While for temperature T larger than some characteristic temperature T_0 the behaviour of the system is the same as that in the case of the fermion condensation, for T<T_0 the intermediate structure with multi-connected quasiparticle momentum distribution arises. The transition of this structure to the fermion condensate at increasing interaction strength is discussed.Comment: 10 pages, 8 postscript figure

Improved Quantum Hard-Sphere Ground-State Equations of State

The London ground-state energy formula as a function of number density for a system of identical boson hard spheres, corrected for the reduced mass of a pair of particles in a sphere-of-influence picture, and generalized to fermion hard-sphere systems with two and four intrinsic degrees of freedom, has a double-pole at the ultimate \textit{regular} (or periodic, e.g., face-centered-cubic) close-packing density usually associated with a crystalline branch. Improved fluid branches are contructed based upon exact, field-theoretic perturbation-theory low-density expansions for many-boson and many-fermion systems, appropriately extrapolated to intermediate densities, but whose ultimate density is irregular or \textit{random} closest close-packing as suggested in studies of a classical system of hard spheres. Results show substantially improved agreement with the best available Green-function Monte Carlo and diffusion Monte Carlo simulations for bosons, as well as with ladder, variational Fermi hypernetted chain, and so-called L-expansion data for two-component fermions.Comment: 15 pages and 7 figure

Phase diagram of the Heisenberg antiferromagnet with four-spin interactions

We study the quantum phase diagram of the Heisenberg planar antiferromagnet with a subset of four-spin ring exchange interactions, using the recently proposed heirarchical mean-field approach. By identifying relevant degrees of freedom, we are able to use a single variational anzatz to map the entire phase diagram of the model and uncover the nature of its various phases. It is shown that there exists a transition between a N\'eel state and a quantum paramagnetic phase, characterized by broken translational invariance. The non-magnetic phase preserves the lattice rotational symmetry, and has a correlated plaquette nature. Our results also suggest that this phase transition can be properly described within the Landau paradigm.Comment: LaTeX 2e, 7 pages, 8 figure

Qualitative analysis of organizational innovations in Spanish public hospitals.

[ES] Conocer la opinión de directivos y clínicos de hospitales públicos sobre los institutos clínicos. dio cualitativo que trata de responder a preguntas realizadas a gerentes y clínicos sobre las innovaciones organizativas que afectan a más de un nivel de intervención de la gestión sanitaria. Se aplican como técnicas: a) entrevistas en profundidad semiestructuradas con la finalidad de señalar los comportamientos, experiencias, opiniones, conocimientos y otros aspectos personales e institucionales objeto del estudio, y b) grupos de discusión, con un grupo de discusión control y dos grupos de discusión estudio se busca la interacción de los grupos para obtener distintos tipos de información relativos al desarrollo de las ideas, operatividad, grado de consenso y disenso en los temas tratados. Realizada la comparación entre el grupo de control y los grupos de estudio, se pone de relieve que las nuevas formas organizativas incrementaron el valor en los siguientes conceptos: economía de contratos, delegación de funciones, descentralización administrativa, incentivación, aversión al riesgo, reingeniería de procesos, continuidad asistencial, competitividad, liderazgo, sistemas de información y orientación al cliente. Existe un creciente interés de los clínicos por las innovaciones organizativas hospitalarias, postura ambivalente en los gestores clínicos ante los cambios de rol de sus respectivas responsabilidades. Se evidencia la resistencia a los cambios. No existe un modelo único de «instituto», dependiendo los modelos existentes de influencias particulares en cuanto a factores internos (cohesión y liderazgo) y externos (entorno, tamaño y tecnología). El incipiente desarrollo de innovaciones pone de relieve la necesidad de cambios en el estilo y naturaleza de la estructura directiva (composición, funciones, responsabilidades). [EN] To determine the opinion of chief executive officers (CEOs) and physicians in public hospitals concerning new managerial trends. We performed a qualitative study designed to determine the opinion of CEOs and physicians on the organizational innovations that affect more than one level of health management intervention. In-depth semi-structured interviews were conducted to identify behavior, experiences, opinions, knowledge and other personal and institutional aspects related to the study's aim. Focus groups (two study groups and one control group) were also used. Interaction between groups was used to obtain different types of information on the development of ideas, operational capacity, and the degree of consensus and disagreement on the subjects discussed. Comparison between the control and the study groups revealed that the new management trends added value in the following areas: economy of contracts, delegation, administrative decentralization, incentives, risk avoidance, process re-engineering, heath care continuity, competitiveness, leadership, information systems and client centeredness. Physicians are showing increased interest in organizational innovations while CEOs are ambivalent about their changing role and respective responsibilities. There is evidence of resistance to change. There is no single institutional model; institutional design depends on internal factors (cohesion and leadership) and external factors (environment, size and technology). The incipient development of innovations reveals the need for changes in the style and characteristics of management structure (composition, functions, responsibilities).S

Descripción anatómica del esqueleto apendicular del carpincho (Hydrochoerus hydrochaeris)

El “carpincho” es una de las especies autóctonas del nordeste argentino y asume importancia económica, evidenciada por los numerosos programas nacionales y regionales para su explotación. La información anatómica sobre el esqueleto apendicular de esta especie es escasa. El objetivo de este trabajo fue describir los huesos de las extremidades (esqueleto apendicular) del Hydrochoerus hydrochaeris, ordenados topográficamente de proximal a distal, utilizando la nomenclatura anatómica veterinaria, así como compararlos con los de otras especies. Los huesos se obtuvieron por maceración, siendo luego tratados con hipoclorito de sodio al 20%. Las descripciones anatómicas se avalaron con registros fotográficos. El análisis osteológico apendicular comprendió cuatro segmentos, tanto para miembros anteriores (escápula, brazo, antebrazo, mano) como posteriores (coxal, muslo, pierna, pie), los cuales revelaron particularidades osteológicas propias de la especie. Se espera que los estudios anatómicos de H. hydrochaeris contribuyan a mejorar su manejo sanitario y productivo

Complement proteins regulating macrophage polarisation on biomaterials

[EN] One of the events occurring when a biomaterial is implanted in an host is the protein deposition onto its surface, which might regulate cell responses. When a biomaterial displays a compromised biocompatibility, distinct complement pathways can be activated to produce a foreign body reaction. In this article, we have designed different types of biomaterial surfaces to study the inflammation process. Here, we used different concentrations of (3-glycidoxypropyl)-trimethoxysilane (GPTMS), an organically-modified alkoxysilane as a precursor for the synthesis of various types of sol-gel materials functionalizing coatings for titanium implants to regulate biological responses. Our results showed that greater GPTMS surface concentrations induced greater secretion of TNF-alpha and IL-10 on RAW 264.7 macrophages. When implanted into rabbit tibia, osseointegration decreased with higher GPTMS concentrations. Interestingly, higher deposition of complement-related proteins C-reactive protein (CRP) and ficolin-2 (FCN2), two main activators of distinct complement pathways, was observed. Taking all together, inflammatory potential increase seems to be GPTMS concentration-dependent. Our results show that a greater adsorption of complement proteins can condition macrophage polarization.This work was supported by MINECO [MAT2017-86043-R]; Universitat Jaume I [Predoc/2014/25, UJI-B2017-37]; Basque Government [IT611-13, Predoc/2016/1/0141]; University of the Basque Country [UFI11/56]; CIC bioGUNE is supported by Basque Department of Industry, Tourism and Trade (Etortek and Elkartek programs), ProteoRed-ISCIII [PRB3 IPT17/0019]; CIBERehd Network and Severo Ochoa Grant [SEV-2016-0644]. Authors would like to thank Antonio Coso and Jaime Franco (GMI-Ilerimplant) for their inestimable contribution to this study, and Raquel Oliver, Jose Ortega (UJI), René van Rheden, Vicent Cuijpers (Radboudumc) and Iraide Escobes (CIC bioGUNE) for their valuable technical assistance.Araújo-Gomes, N.; Romero-Gavilán, F.; Zhang, Y.; Martínez-Ramos, C.; Elortza, F.; Azkargorta, M.; Martín De Llano, JJ.... (2019). Complement proteins regulating macrophage polarisation on biomaterials. Colloids and Surfaces B Biointerfaces. 181:125-133. https://doi.org/10.1016/j.colsurfb.2019.05.039S12513318