Numerical study of pattern formation following a convective instability in non-Boussinesq fluids

We present a numerical study of a model of pattern formation following a convective instability in a non-Boussinesq fluid. It is shown that many of the features observed in convection experiments conducted on $CO_{2}$ gas can be reproduced by using a generalized two-dimensional Swift-Hohenberg equation. The formation of hexagonal patterns, rolls and spirals is studied, as well as the transitions and competition among them. We also study nucleation and growth of hexagonal patterns and find that the front velocity in this two dimensional model is consistent with the prediction of marginal stability theory for one dimensional fronts.Comment: 9 pages, report FSU-SCRI-92-6

Autenticidad a partir de RV como método de documentación de patrimonio cultural. Aproximación teórica basada en prácticas de conservación y documetnación

[EN] The visualization of 3D reconstructed artifacts often requires significant computing resources. The implementation of an object in a virtual reality (VR) application even necessitates the reduction of the polygonal mesh. Consequently, the communication and dissemination of “authentic” 3D reconstructions via immersive VR technologies has been a nearly impossible feat for many researchers. However, is the issue really computing resources, or is it rather the notion of authenticity in an “auratic” sense, i.e., an excessive focus on physical evidence and survey data? In the present paper, we will discuss the authenticity requirements for virtual archaeology as set by the Seville Principles(2011), and we will analyse some limitations related to the current approaches. Furthermore, we will propose a pluralistic notion based on the contextualization of 3D objects in VR environments with synesthetic (i.e. multisensory) information. This new notion of authenticity relies on conservation meanings rather than physical features. In line with this approach, two case studies will be commented: the multimodal 3D-documentation of the Jupiter Column(2AD) in Ladenburg, and the VR-based re-enactment of a modern work of art, the audio-kinetic sculpture Kaleidophonic Dog(1967) by Stephan von Huene. These two projects provide valuable data for a revision of the notion of authenticity in both virtual archaeology and art conservation.[ES] La visualización deartefactos reconstruidos en 3D requiere a menudo demasiados recursos computacionales. La implementación en una aplicación de realidad virtual (RV) requiere incluso la reducción de la red poligonal delobjeto.Consecuentemente,la comunicación y la divulgaciónde reconstrucciones 3D “auténticas”representa todavía una tarea casi imposiblepara muchos investigadores. ¿Pero se trata realmente solo de una cuestión de computación, o tiene algo que ver con una noción de autenticidad en un sentido“aurático”, es decir, con un enfoqueexcesivo sobre pruebas materiales y datosmensurables?En esteartículo discutimos los requisitos de autenticidad para la arqueología virtual tal y como se formulan en los “Principios de Sevilla” (2011) y analizamos algunaslimitaciones de los enfoques actuales. Proponemos,además,una noción pluralista basada en la contextualización de objetos 3D en entornos de RV con información sinestésica (es decir, multisensorial). Esta nueva noción de autenticidad se basa más enla conservación de significados que en la conservación de características físicas. En línea con esta propuesta teórica, se comentarán dos casos de estudio: la documentación multimodal 3D de la Columna de Júpiterde Ladenburg (II d.C.) y la recreación en RV de una obra de arte moderno, la escultura audio-cinética Kaleidophonic Dog(1967) de Stephan von Huene. Estos dos proyectos ofrecen experiencias valiosas para una revisión de la noción de autenticidad tanto en la arqueología virtual como en la conservación de arte.This work was supported by the Stadt Karlsruhe (“Interdisziplinärer Fördertopf”) and the HEiKAResearch fonds (HEiKA, Heidelberg Karlsruhe Research Partnership)Muñoz Morcillo, J.; Schaaf, F.; Schneider, RH.; Robertson-Von Trotha, CY. (2017). Authenticity through VR-based documentation of cultural heritage. A theoretical approach based on conservation and documentation practices. Virtual Archaeology Review. 8(16):35-43. doi:10.4995/var.2017.5932.SWORD354381

26Postoperative diagnosis and outcome in patients with revision arthroplasty for aseptic loosening

BACKGROUND: The most common cause of implant failure is aseptic loosening (AL), followed by prosthetic joint infection (PJI). This study evaluates the incidence of PJI among patients operated with suspected AL and whether the diagnosis of PJI was predictive of subsequent implant failure including re-infection, at 2 years of follow up. METHODS: Patients undergoing revision hip or knee arthroplasty due to presumed AL from February 2009 to September 2011 were prospectively evaluated. A sonication fluid of prosthesis and tissue samples for microbiology and histopathology at the time of the surgery were collected. Implant failure include recurrent or persistent infection, reoperation for any reason or need for chronic antibiotic suppression. RESULTS: Of 198 patients with pre-and intraoperative diagnosis of AL, 24 (12.1 %) had postoperative diagnosis of PJI. After a follow up of 31 months (IQR: 21 to 38 months), 9 (37.5 %) of 24 patients in the PJI group had implant failure compared to only 1 (1.1 %) in the 198 of AL group (p 20 CFU) and peri-prosthetic tissue culture were 87.5 % vs 66.7 %, respectively. Specificities were 100 % for both techniques (95 % CI, 97.9-100 %). A greater number of patients with PJI (79.1 %) had previous partial arthroplasty revisions than those patients in the AL group (56.9 %) (p = 0.04). In addition, 5 (55.5 %) patients with PJI and implant failure had more revision arthroplasties during the first year after the last implant placement than those patients with PJI without implant failure (1 patient; 6.7 %) (RR 3.8; 95 % CI 1.4-10.1; p = 0.015). On the other hand, 6 (25 %) patients finally diagnosed of PJI were initially diagnosed of AL in the first year after primary arthroplasty, whereas it was only 16 (9.2 %) patients in the group of true AL (RR 2.7; 95 % CI 1.2-6.1; p = 0.03). CONCLUSIONS: More than one tenth of patients with suspected AL are misdiagnosed PJI. Positive histology and positive peri-implant tissue and sonicate fluid cultures are highly predictive of implant failure in patients with PJI. Patients with greater number of partial hip revisions for a presumed AL had more risk of PJI. Early loosening is more often caused by hidden PJI than late loosening

A clinical method for mapping and quantifying blood stasis in the left ventricle

In patients at risk of intraventrcular thrombosis, the benefits of chronic anticoagulation therapy need to be balanced with the pro-hemorrhagic effects of therapy. Blood stasis in the cardiac chambers is a recognized risk factor for intracardiac thrombosis and potential cardiogenic embolic events. In this work, we present a novel flow image-based method to assess the location and extent of intraventricular stasis regions inside the left ventricle (LV) by digital processing flow-velocity images obtained either by phase-contrast magnetic resonance (PCMR) or 2D color-Doppler velocimetry (echo-CDV). This approach is based on quantifying the distribution of the blood Residence Time (TR) from time-resolved blood velocity fields in the LV. We tested the new method in illustrative examples of normal hearts, patients with dilated cardiomyopathy and one patient before and after the implantation of a left ventricular assist device (LVAD). The method allowed us to assess in-vivo the location and extent of the stasis regions in the LV. Original metrics were developed to integrate flow properties into simple scalars suitable for a robust and personalized assessment of the risk of thrombosis. From a clinical perspective, this work introduces the new paradigm that quantitative flow dynamics can provide the basis to obtain subclinical markers of intraventricular thrombosis risk. The early prediction of LV blood stasis may result in decrease strokes by appropriate use of anticoagulant therapy for the purpose of primary and secondary prevention. It may also have a significant impact on LVAD device design and operation set-up

The Generalife and the arabian ruins of its surroundings: an unknown chapter of the "Nuevos paseos" by Simón de Argote

Los Nuevos paseos (1806-1807) de Simón de Argote constituyen una de las obras más notables escritas sobre la Alhambra y suponen una respuesta ilustrada a las tergiversaciones sobre el pasado romano de Granada del clérigo y arabista Velázquez de Echeverría. Desgraciadamente la obra quedó incompleta porque no llegó a cumplir su objetivo de abarcar las “antigüedades árabes” ubicadas fuera de la ciudadela nazarí. En este artículo se presenta, con anotaciones críticas, un capítulo inédito dedicado al Generalife y a las ruinas de su entorno, el cual fue entregado por su autor al rey José Bonaparte durante su estancia en Granada y se conservó entre los papeles perdidos por el monarca en la batalla de Vitoria. A partir de documentación hallada en muy diversos archivos y publicaciones de la época se arroja luz sobre la mal conocida trayectoria de Simón de Argote y se profundiza en su relación con el general Horace Sebastiani, militar que por orden de Napoleón realizó labores de embajador en Estambul y en otras ciudades de Próximo Oriente, antes de gobernar el Reino de Granada.Simón de Argote’s Nuevos paseos (1806- 1807) is one of the most remarkable works written on the Alhambra. It offers an Enlightenment response to the distortions of the Roman past of Granada of the cleric and Arabist Velázquez de Echeverría. Unfortunately, the work was unfinished because it did not cover all the «Arabian antiques» located outside the Nasrid city. In this article, an unknown chapter about the Generalife and the ruins around is presented, accompanied with critical notes. It was given by the author to King Joseph Bonaparte during his stay in Granada and it was kept among the papers the king had lost at the Battle of Vitoria. The study of the documents found in different archives and publications of that time sheds some light on the mysterious personality of Simón de Argote and deepens in the knowledge of his relationship with General Horace Sebastiani, a military who was embassador in Istanbul and other cities of the Middle East under Napoleon’s order, before he ruled the Kingdom of Granada

Planck 2013 results. XXII. Constraints on inflation

We analyse the implications of the Planck data for cosmic inflation. The Planck nominal mission temperature anisotropy measurements, combined with the WMAP large-angle polarization, constrain the scalar spectral index to be ns = 0:9603 _ 0:0073, ruling out exact scale invariance at over 5_: Planck establishes an upper bound on the tensor-to-scalar ratio of r < 0:11 (95% CL). The Planck data thus shrink the space of allowed standard inflationary models, preferring potentials with V00 < 0. Exponential potential models, the simplest hybrid inflationary models, and monomial potential models of degree n _ 2 do not provide a good fit to the data. Planck does not find statistically significant running of the scalar spectral index, obtaining dns=dln k = 0:0134 _ 0:0090. We verify these conclusions through a numerical analysis, which makes no slowroll approximation, and carry out a Bayesian parameter estimation and model-selection analysis for a number of inflationary models including monomial, natural, and hilltop potentials. For each model, we present the Planck constraints on the parameters of the potential and explore several possibilities for the post-inflationary entropy generation epoch, thus obtaining nontrivial data-driven constraints. We also present a direct reconstruction of the observable range of the inflaton potential. Unless a quartic term is allowed in the potential, we find results consistent with second-order slow-roll predictions. We also investigate whether the primordial power spectrum contains any features. We find that models with a parameterized oscillatory feature improve the fit by __2 e_ _ 10; however, Bayesian evidence does not prefer these models. We constrain several single-field inflation models with generalized Lagrangians by combining power spectrum data with Planck bounds on fNL. Planck constrains with unprecedented accuracy the amplitude and possible correlation (with the adiabatic mode) of non-decaying isocurvature fluctuations. The fractional primordial contributions of cold dark matter (CDM) isocurvature modes of the types expected in the curvaton and axion scenarios have upper bounds of 0.25% and 3.9% (95% CL), respectively. In models with arbitrarily correlated CDM or neutrino isocurvature modes, an anticorrelated isocurvature component can improve the _2 e_ by approximately 4 as a result of slightly lowering the theoretical prediction for the ` <_ 40 multipoles relative to the higher multipoles. Nonetheless, the data are consistent with adiabatic initial conditions

Growth of few-wall carbon nanotubes with narrow diameter distribution over Fe-Mo-MgO catalyst by methane/acetylene catalytic decomposition

Few-wall carbon nanotubes were synthesized by methane/acetylene decomposition over bimetallic Fe-Mo catalyst with MgO (1:8:40) support at the temperature of 900°C. No calcinations and reduction pretreatments were applied to the catalytic powder. The transmission electron microscopy investigation showed that the synthesized carbon nanotubes [CNTs] have high purity and narrow diameter distribution. Raman spectrum showed that the ratio of G to D band line intensities of IG/ID is approximately 10, and the peaks in the low frequency range were attributed to the radial breathing mode corresponding to the nanotubes of small diameters. Thermogravimetric analysis data indicated no amorphous carbon phases. Experiments conducted at higher gas pressures showed the increase of CNT yield up to 83%. Mössbauer spectroscopy, magnetization measurements, X-ray diffraction, high-resolution transmission electron microscopy, and electron diffraction were employed to evaluate the nature of catalyst particles

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

Speciation-controlled incipient wetness impregnation: A rational synthetic approach to prepare sub-nanosized and highly active ceria–zirconia supported gold catalysts

On the basis of calculated thermodynamic species distribution diagrams and by appropriately controlling the pH of aqueous HAuCl4 solutions, it has been possible to prepare, using a Speciation-controlled Incipient Wetness Impregnation (ScIWI) approach, Au catalysts supported on ceria–zirconia mixed oxides featuring both high gold loadings and excellent metal dispersions. This rational synthesis method is carried out at room temperature. It is both much simpler, in equipment terms, and less expensive than widely used Deposition–Precipitation (DP). Moreover, the use of ScIWI allows overcoming the severe limitations of previously assayed impregnation methods. With this procedure it is possible to prepare active catalysts in CO oxidation with high efficiency in terms of gold precursor usage, i.e. minimizing Au losses during synthesis. Therefore this, quite amenable, novel strategy for the facile preparation of highly dispersed supported gold catalysts gathers the necessary requirements for both its use at lab scale and an easy scaling-up to industrial levels