Carvajal y la voluntad de ser arquitecto: La construcción del proyecto y la belleza eficaz

Javier Carvajal Ferrer (Barcelona 1926–Madrid 2013) aúna magisterio y praxis de tal modo que es imposible acercarse a su obra sin tener en cuenta su docencia y, al revés, no puede entenderse su discurso en las aulas si, a la vez, no se transita por sus proyectos. Más aún, para Carvajal el proyecto arquitectónico es el ámbito específico de la investigación del profesor y el mecanismo de eficacia por el que el profesional debe dar una respuesta coherente a la teoría y a la praxis. Este texto pretende evocar algunas de las virtudes de su obra arquitectónica y de las enseñanzas de su labor docente, ejemplificadas en dos de sus proyectos más emblemáticos. Uno, su proyecto más alabado, el Pabellón de España para la Feria Mundial de Nueva York (1964–65) del que se cumplen cincuenta años. El otro, el más polémico, la Torre de Valencia en Madrid (1970–1973). Y hacerlo investigando sobre el rigor y la belleza de unos planos que él mismo dibujaba. Ambas obras ilustran, además, aspectos relevantes de su propia personalidad que inevitablemente se imbrican en su febril actividad como arquitecto y docente, y muestran cómo su firme confianza en la calidad del proyecto sigue siendo la mejor contribución a la evolución de la arquitectura. Autenticidad, vocación, voluntad, exigencia, precisión, rigor, perfección, coherencia o ilusión, se resumen en uno de sus célebres mensajes a los alumnos: “Sueñen con lo posible”.Javier Carvajal Ferrer (Barcelona, 1926–Madrid, 2013) combined teaching and practice so that it is impossible to approach his work without considering his teaching and, conversely, we cannot understand his speech in classrooms if, at the same time, we do not examine his projects. Moreover, for Carvajal the architectural project is the specific field of the professor’s research and the efficacy mechanism by which the practitioner must give a coherent response to both theory and praxis. This text aims to evoke some of the virtues of his architectural work and the lessons of his teaching, exemplified in two of his most emblematic projects: first, his most praised project, the Spanish Pavilion for the World’s Fair in New York (1964–65), which marks fifty years; and the other project—more controversial—the Valencia Tower in Madrid (1970–73) by researching the rigor and beauty of the plans that he drew himself. Both works also illustrate important aspects of his personality that inevitably overlap in his feverish activity as an architect and professor, and show how his strong confidence in the quality of the project remains as the best contribution to the evolution of architecture. Authenticity, vocation, will, dedication, precision, rigor, perfection, consistency, and illusion are summarized in one of his famous messages to students: “Dream of the possible”

Very Large Baseline Array observations of Mrk 6 : probing the jet-lobe connection

We present the results of high-resolution VLBI (very long baseline interferometry) observations at 1.6 and 4.9 GHz of the radio-loud Seyfert galaxy, Mrk 6. These observations are able to detect a compact radio core in this galaxy for the first time. The core has an inverted spectral index (α1.6 4.9 = +1.0 ± 0.2) and a brightness temperature of 1 × 108 K. Three distinct radio components, which resemble jet elements and/or hotspots, are also detected. The position angles of these elongated jet elements point not only to a curved jet in Mrk 6, but also towards a connection between the AGN and the kpc-scale radio lobes/bubbles in this galaxy. Firmer constraints on the star formation rate provided by new Herschel observations (SFR <0.8 M⊙ yr-1) make the starburst-wind-powered bubble scenario implausible. From plasma speeds, obtained via prior Chandra X-ray observations, and ram pressure balance arguments for the interstellar medium and radio bubbles, the north-south bubbles are expected to take 7.5 × 106 yr to form, and the east-west bubbles 1.4 × 106 yr. We suggest that the jet axis has changed at least once in Mrk 6 within the last ≈107 yr. A comparison of the nuclear radio-loudness of Mrk 6 and a small sample of Seyfert galaxies with a subset of low-luminosity FR I radio galaxies reveals a continuum in radio properties.Peer reviewe

Area distribution of two-dimensional random walks on a square lattice

The algebraic area probability distribution of closed planar random walks of length N on a square lattice is considered. The generating function for the distribution satisfies a recurrence relation in which the combinatorics is encoded. A particular case generalizes the q-binomial theorem to the case of three addends. The distribution fits the L\'evy probability distribution for Brownian curves with its first-order 1/N correction quite well, even for N rather small.Comment: 8 pages, LaTeX 2e. Reformulated in terms of q-commutator

Photo-Thermoelectric Effect at a Graphene Interface Junction

We investigate the optoelectronic response of a graphene interface junction, formed with bilayer and single-layer graphene, by photocurrent (PC) microscopy. We measure the polarity and amplitude of the PC while varying the Fermi level by tuning a gate voltage. These measurements show that the generation of PC is by a photo-thermoelectric effect. The PC displays a factor of ~10 increase at the cryogenic temperature as compared to room temperature. Assuming the thermoelectric power has a linear dependence on the temperature, the inferred graphene thermal conductivity from temperature dependent measurements has a T^{1.5} dependence below ~100 K, which agrees with recent theoretical predictions

Cysteine cathepsins control hepatic NF-κB-dependent inflammation via sirtuin-1 regulation

Sirtuin-1 (SIRT1) regulates hepatic metabolism but its contribution to NF-κB-dependent inflammation has been overlooked. Cysteine cathepsins (Cathepsin B or S, CTSB/S) execute specific functions in physiological processes, such as protein degradation, having SIRT1 as a substrate. We investigated the roles of CTSB/S and SIRT1 in the regulation of hepatic inflammation using primary parenchymal and non-parenchymal hepatic cell types and cell lines. In all cells analyzed, CTSB/S inhibition reduces nuclear p65-NF-κB and κB-dependent gene expression after LPS or TNF through enhanced SIRT1 expression. Accordingly, SIRT1 silencing was sufficient to enhance inflammatory gene expression. Importantly, in a dietary mouse model of non-alcoholic steatohepatitis, or in healthy and fibrotic mice after LPS challenge, cathepsins as well as NF-κB-dependent gene expression are activated. Consistent with the prominent role of cathepsin/SIRT1, cysteine cathepsin inhibition limits NF-κB-dependent hepatic inflammation through the regulation of SIRT1 in all in vivo settings, providing a novel anti-inflammatory therapeutic target in liver disease.This study was supported by grants from the Instituto de Salud Carlos III (PI13/00374 to MM), Ministerio de Economía y Competitividad (SAF2015-69944-R to JFC, SAF2013-47246-R to AC, SAF2015-66515-R to AM) and co-funded by FEDER (Fondo Europeo de Desarrollo Regional, Unión Europea. “Una manera de hacer Europa”); center grant P50-AA-11999 from Research Center for Liver and Pancreatic Diseases (US-NIAAA to JFC); and by CIBERehd. AT is a recipient of a FPU fellowship recipient from the Ministerio de Educación, Cultura y Deporte.Peer Reviewe

An efficient algorithm to calculate intrinsic thermoelectric parameters based on Landauer approach

The Landauer approach provides a conceptually simple way to calculate the intrinsic thermoelectric (TE) parameters of materials from the ballistic to the diffusive transport regime. This method relies on the calculation of the number of propagating modes and the scattering rate for each mode. The modes are calculated from the energy dispersion (E(k)) of the materials which require heavy computation and often supply energy relation on sparse momentum (k) grids. Here an efficient method to calculate the distribution of modes (DOM) from a given E(k) relationship is presented. The main features of this algorithm are, (i) its ability to work on sparse dispersion data, and (ii) creation of an energy grid for the DOM that is almost independent of the dispersion data therefore allowing for efficient and fast calculation of TE parameters. The inclusion of scattering effects is also straight forward. The effect of k-grid sparsity on the compute time for DOM and on the sensitivity of the calculated TE results are provided. The algorithm calculates the TE parameters within 5% accuracy when the K-grid sparsity is increased up to 60% for all the dimensions (3D, 2D and 1D). The time taken for the DOM calculation is strongly influenced by the transverse K density (K perpendicular to transport direction) but is almost independent of the transport K density (along the transport direction). The DOM and TE results from the algorithm are bench-marked with, (i) analytical calculations for parabolic bands, and (ii) realistic electronic and phonon results for $Bi_{2}Te_{3}$.Comment: 16 Figures, 3 Tables, submitted to Journal of Computational electronic

Coherent electron-phonon coupling and polaron-like transport in molecular wires

We present a technique to calculate the transport properties through one-dimensional models of molecular wires. The calculations include inelastic electron scattering due to electron-lattice interaction. The coupling between the electron and the lattice is crucial to determine the transport properties in one-dimensional systems subject to Peierls transition since it drives the transition itself. The electron-phonon coupling is treated as a quantum coherent process, in the sense that no random dephasing due to electron-phonon interactions is introduced in the scattering wave functions. We show that charge carrier injection, even in the tunneling regime, induces lattice distortions localized around the tunneling electron. The transport in the molecular wire is due to polaron-like propagation. We show typical examples of the lattice distortions induced by charge injection into the wire. In the tunneling regime, the electron transmission is strongly enhanced in comparison with the case of elastic scattering through the undistorted molecular wire. We also show that although lattice fluctuations modify the electron transmission through the wire, the modifications are qualitatively different from those obtained by the quantum electron-phonon inelastic scattering technique. Our results should hold in principle for other one-dimensional atomic-scale wires subject to Peierls transitions.Comment: 21 pages, 8 figures, accepted for publication in Phys. Rev. B (to appear march 2001

Surface Screening Charge and Effective Charge

The charge on an atom at a metallic surface in an electric field is defined as the field-derivative of the force on the atom, and this is consistent with definitions of effective charge and screening charge. This charge can be found from the shift in the potential outside the surface when the atoms are moved. This is used to study forces and screening on surface atoms of Ag(001) c$(2\times 2)$ -- Xe as a function of external field. It is found that at low positive (outward) fields, the Xe with a negative effective charge of -0.093 $|{e}|$ is pushed into the surface. At a field of 2.3 V \AA$^{-1}$ the charge changes sign, and for fields greater than 4.1 V \AA$^{-1}$ the Xe experiences an outward force. Field desorption and the Eigler switch are discussed in terms of these results.Comment: 4 pages, 1 figure, RevTex (accepted by PRL

Construction and immunogenicity evaluation of recombinant influenza A viruses containing chimeric hemagglutinin genes derived from genetically divergent influenza A H1N1 subtype viruses

Citation: McCormick, K., Jiang, Z., Zhu, L., Lawson, S. R., Langenhorst, R., Ransburgh, R., . . . Fang, Y. (2015). Construction and immunogenicity evaluation of recombinant influenza A viruses containing chimeric hemagglutinin genes derived from genetically divergent influenza A H1N1 subtype viruses. Plos One, 10(6). doi:10.1371/journal.pone.0127649Background and Objectives: Influenza A viruses cause highly contagious diseases in a variety of hosts, including humans and pigs. To develop a vaccine that can be broadly effective against genetically divergent strains of the virus, in this study we employed molecular breeding (DNA shuffling) technology to create a panel of chimeric HA genes. Methods and Results: Each chimeric HA gene contained genetic elements from parental swine influenza A viruses that had a history of zoonotic transmission, and also from a 2009 pandemic virus. Each parental virus represents a major phylogenetic clade of influenza A H1N1 viruses. Nine shuffled HA constructs were initially screened for immunogenicity in mice by DNA immunization, and one chimeric HA (HA-129) was expressed on both a A/Puerto Rico/8/34 backbone with mutations associated with a live, attenuated phenotype (PR8LAIV- 129) and a A/swine/Texas/4199-2/98 backbone (TX98-129). When delivered to mice, the PR8LAIV- 129 induced antibodies against all four parental viruses, which was similar to the breadth of immunity observed when HA-129 was delivered as a DNA vaccine. This chimeric HA was then tested as a candidate vaccine in a nursery pig model, using inactivated TX98-129 virus as the backbone. The results demonstrate that pigs immunized with HA-129 developed antibodies against all four parental viruses, as well as additional primary swine H1N1 influenza virus field isolates. Conclusion: This study established a platform for creating novel genes of influenza viruses using a molecular breeding approach, which will have important applications toward future development of broadly protective influenza virus vaccines. © 2015 McCormick 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