Resultados en la cirugía de revisión de la artroplastia de rodilla con aporte de aloinjerto óseo

Hemos realizado un estudio retrospectivo de 12 pacientes (13 rodillas) intervenidos entre 1975 y 2001 de revisión de prótesis de rodilla utilizando aloinjerto óseo, valorando el resultado funcional y clínico. La edad media fue de 62 años. La indicación primaria fue de gonartrosis primaria en 8 casos (9 rodillas), artrosis postraumática en 1 caso y 2 casos de artritis reumatoide. Los defectos óseos fueron clasificados utilizando la clasificación del Anderson Orthopedic Institute Research. Se utilizó aloinjerto de forma fragmentada en 11 casos y de forma estructural en 2. El seguimiento medio fue de 69 meses. En la valoración clínica se utilizó la escala de la Knee Society; la evaluación radiográfica evaluó la existencia de integración del injerto en el huésped. Los 2 casos de artritis reumatoide presentaron infección profunda protésica y que necesitaron de una artrodesis como solución definitiva. El resto de pacientes mostró unos resultados satisfactorios con buena integración del injerto al huésped. La utilización de aloinjerto fragmentado y estructural en la cirugía de revisión protésica de rodilla resuelve de manera satisfactoria la presencia del defecto óseo, aunque en enfermos con algú tipo de inmunopresión, el elevado riesgo de infección profunda en cirugía de revisión nos obliga a extremar las precauciones.We have carried out a retrospective study of 12 patients (13 knees) treated between 1975 and 2001 after failed total knee arthroplasty (TKA), by means of revision surgery using bone allograft. The mean age was of 62 years. The primary indication was degenerative osteoarthritis in 8 cases (9 knees), postraumatic osteoarthritis in 1 case and rheumatoid artritis in 2 cases. The bony defects were classified according to the Anderson's Orthopedic Institute classification. Fragmented allograft was used in 11 cases and structural allograft in 2. The mean follow-up time was of 69 months. Outcome was evaluated through functional and clinical result. For the clinical evaluation the scale of the Knee Society was used; the radiographic evaluation assessed the degree of integration of the graft. The 2 cases of rheumatoid artritis presented deep infection of the TKA that required an arthrodesis for definitive solution. The rest of patients showed satisfactory results with good integration of the bone graft. The use of fragmented and structural allograft in revision surgery of failed TKA solves in a satisfactory way the presence of bony defects, although in patients with some degree of inmunosupression the high risk of deep infection forces to extreme the cautions

Schwinger mechanism for gluons from lattice QCD

Continuum and lattice analyses have revealed the existence of a mass-scale in the gluon two-point Schwinger function. It has long been conjectured that this expresses the action of a Schwinger mechanism for gauge boson mass generation in quantum chromodynamics (QCD). For such to be true, it is necessary and sufficient that a dynamically-generated, massless, colour-carrying, scalar gluon+gluon correlation emerge as a feature of the dressed three-gluon vertex. Working with results on elementary Schwinger functions obtained via the numerical simulation of lattice-regularised QCD, we establish with an extremely high level of confidence that just such a feature appears; hence, confirm the conjectured origin of the gluon mass scale.Comment: 8 pages, 8 figure

Payments for ecosystem services and the fatal attraction of win-win solutions

In this commentary we critically discuss the suitability of payments for ecosystem services and the most important challenges they face. While such instruments can play a role in improving environmental governance, we argue that over-reliance on payments as win-win solutions might lead to ineffective outcomes, similar to earlier experience with integrated conservation and development projects. Our objective is to raise awareness, particularly among policy makers and practitioners, about the limitations of such instruments and to encourage a dialogue about the policy contexts in which they might be appropriate. © 2013 Wiley Periodicals, Inc

Series Solution for the Time-Fractional Coupled mKdV Equation Using the Homotopy Analysis Method

We present new analytical approximated solutions for the space-time fractional nonlinear partial differential coupled mKdV equation. A homotopy analysis method is considered to obtain an infinite series solution. The effectiveness of this method is demonstrated by finding exact solutions of the fractional equation proposed, for the special case when the limit of the integral order of the time derivative is considered. The comparison shows a precise agreement between these solutions

Renormalizability of a quark-gluon model with soft BRST breaking in the infrared region

We prove the renormalizability of a quark-gluon model with a soft breaking of the BRST symmetry, which accounts for the modification of the large distance behavior of the quark and gluon correlation functions. The proof is valid to all orders of perturbation theory, by making use of softly broken Ward identities.Comment: 20 pages, no figures. Preprint number added in v2

Nonlocal Transport Processes and the Fractional Cattaneo-Vernotte Equation

The Cattaneo-Vernotte equation is a generalization of the heat and particle diffusion equations; this mathematical model combines waves and diffusion with a finite velocity of propagation. In disordered systems the diffusion can be anomalous. In these kinds of systems, the mean-square displacement is proportional to a fractional power of time not equal to one. The anomalous diffusion concept is naturally obtained from diffusion equations using the fractional calculus approach. In this paper we present an alternative representation of the Cattaneo-Vernotte equation using the fractional calculus approach; the spatial-time derivatives of fractional order are approximated using the Caputo-type derivative in the range (0,2]. In this alternative representation we introduce the appropriate fractional dimensional parameters which characterize consistently the existence of the fractional space-time derivatives into the fractional Cattaneo-Vernotte equation. Finally, consider the Dirichlet conditions, the Fourier method was used to find the full solution of the fractional Cattaneo-Vernotte equation in analytic way, and Caputo and Riesz fractional derivatives are considered. The advantage of our representation appears according to the comparison between our model and models presented in the literature, which are not acceptable physically due to the dimensional incompatibility of the solutions. The classical cases are recovered when the fractional derivative exponents are equal to 1

Deep XMM-Newton observation of the Eta Chamaleontis cluster

The members of the Eta Chamaleontis cluster are in an evolutionary stage in which disks are rapidly evolving. It also presents some peculiarities, such as the large fraction of binaries and accretion disks, probably related with the cluster formation process. Its proximity makes this stellar group an ideal target for studying the relation between X-ray emission and those stellar parameters. The main objective of this work is to determine general X-ray properties of the cluster members in terms of coronal temperature, column density, emission measure, X-ray luminosity and variability. We also aim to establish the relation between the X-ray luminosity of these stars and other stellar parameters, such as binarity and presence of accretion disks. A study of flare energies for each flare event and their relation with some stellar parameters is also performed. We used proprietary data from a deep XMM-Newton observation pointed at the core of the Eta Chamaleontis cluster. Specific software for the reduction of XMM-Newton data was used for the analysis of our observation. For the detection of sources, we used the wavelet-based code PWDetect. General coronal properties were derived from plasma model fitting. We also determined variability of the Eta Chamaleontis members in the EPIC field-of-view. A total of six flare-like events were clearly detected in five different stars. For them, we derived coronal properties during the flare events and pseudo-quiescent state separately. In our observations, stars that underwent a flare event have higher X-ray luminosities in the pseudo-quiescent state than cluster members with similar spectral type with no indications of flaring, independently whether they have an accretion disk or not. Observed flare energies are typical of both pre-main and main-sequence M stars. We detected no difference between flare energies of stars with and without an accretion disk.Comment: Accepted for publication in Astronomy and Astrophysics. 12 pages, 30 individual figure

Herramientas informáticas para el estudio de los recursos genéticos

En el CNRG además de la conservación de los recursos genéticos, se realizan estudios de nivel informático que incluye la descripción y modelación de la distribución geográfica de las especies conservadas, así como el análisis del genoma y diversidad. A través de herramientas informáticas, es posible determinar el contenido genómico y como este cambia o responde a diversas condiciones ambientales. Por otro lado, con el apoyo de la modelación espacial y los sistemas de información geográfica se ha realizado la planeación y evaluación en las colectas, para determinar la distribución actual y potencial de las especies conservadas. Además, sirven para conocer las condiciones ambientales del suelo, clima y relieve, en las que dichas colectas se desarrollan. El continúo avance y desarrollo de tecnologías informáticas ha permitido realizar estudios cada vez más complejos. La ciencia de datos (data science), ha permitido el modelado y caracterización de los recursos genéticos. Así la bioinformática y los sistemas de información geográfica, son herramientas que contribuyen al conocimiento y conservación de la biodiversidad