On the transmission of light through a single rectangular hole

In this Letter we show that a single rectangular hole exhibits transmission resonances that appear near the cutoff wavelength of the hole waveguide. For light polarized with the electric field pointing along the short axis, it is shown that the normalized-to-area transmittance at resonance is proportional to the ratio between the long and short sides, and to the dielectric constant inside the hole. Importantly, this resonant transmission process is accompanied by a huge enhancement of the electric field at both entrance and exit interfaces of the hole. These findings open the possibility of using rectangular holes for spectroscopic purposes or for exploring non-linear effects.Comment: Submitted to PRL on Feb. 9th, 200

Phase-locking of a Nonlinear Optical Cavity via Rocking: Transmuting Vortices into Phase Patterns

We report experimental observation of the conversion of a phase-invariant nonlinear system into a phase-locked one via the mechanism of rocking [G. J. de Valcarcel and K. Staliunas, Phys. Rev. E 67, 026604 (2003)]. This conversion results in that vortices of the phase-invariant system are being replaced by phase patterns such as domain walls. The experiment is carried out on a photorefractive oscillator in two-wave mixing configuration.A model for the experimental device is given that reproduces the observed behavior.Comment: 9 pages and 4 figure

Endoplasmic reticulum aminopeptidase 1 (ERAP1) polymorphism relevant to inflammatory disease shapes the peptidome of the birdshot chorioretinopathy-associated HLA-A∗29:02 Antigen

Birdshot chorioretinopathy is a rare ocular inflammation whose genetic association with HLA-A∗29:02 is the highest between a disease and a major histocompatibility complex (MHC) molecule. It belongs to a group of MHCI- Associated inflammatory disorders, also including ankylosing spondylitis, psoriasis, and Behç et's disease, for which endoplasmic reticulum aminopeptidases (ERAP) 1 and/or 2 have been identified as genetic risk factors. Since both enzymes are involved in the processing of MHC-I ligands, it seems reasonable that common peptide- mediated mechanisms may underlie the pathogenesis of these diseases. In this study, comparative immunopeptidomics was used to characterize >5000 A∗29:02 ligands and quantify the effects of ERAP1 polymorphism and expression on the A∗29:02 peptidome in human cells. The peptides predominant in an active ERAP1 context showed a higher frequency of nonamers and bulkier amino acid side chains at multiple positions, compared with the peptides predominant in a less active ERAP1 background. Thus, ERAP1 polymorphism has a large influence, shaping the A∗29:02 peptidome through length-dependent and length-independent effects. These changes resulted in increased affinity and hydrophobicity of A∗29:02 ligands in an active ERAP1 context. The results reveal the nature of the functional interaction between A∗29:02 and ERAP1 and suggest that this enzyme may affect the susceptibility to birdshot chorioretinopathy by altering the A∗29:02 peptidome. The complexity of these alterations is such that not only peptide presentation but also other potentially pathogenic features could be affectedThis work was supported by grants SAF2011/25681 (Plan Nacional de I+D+i) to JALC, Binational Science Foundation Grant 2009393 to AA, and an institutional grant of the Fundacion Ramon Areces to the CBMS

Anatomía de la madera de Abies spp. del área mediterránea: aproximación filética

An analysis was made of the wood anatomy of seven species, one subspecies and two varieties of the genus Abies from the Mediterranean area (A. alba, A. borisii-regis, A. cephalonica, A. cilicica, A. nordmanniana, A. nordmanniana subsp. equi-trojani, A. numidica, A. pinsapo, A. pinsapo var. marocana and A. pinsapo var. tazaotana) in order to find phyletically relevant features to help clarify and complement the evolutionary patterns based on molecular studies. The wood structure within the genus was qualitatively similar, except for specific features characteristic of certain provenances. However, the wood biometry allowed the different taxa to be grouped in accordance with their anatomical similarity. A. alba, A. pinsapo, A. pinsapo var. marocana and A. pinsapo var. tazaotana possess biometric features which distinguish them from the other Mediterranean firs. Furthermore, A. numidica showed biometric features which distinguish it from the eastern firs (A. borisii-regis, A. cephalonica, A. cilicica, A. nordmanniana and A. nordmanniana subsp. equi-trojani) and place it closer to certain Iberian populations of A. pinsapo. The maximum ray height in number of cells, frequency of rays with more than 30 cells and tracheid length can be regarded as specific patterns of the Mediterranean fir phylum.En este trabajo se ha analizado la anatomía de la madera de siete especies, una subespecie y dos variedades del género Abies procedentes del área mediterránea (A. alba, A. borisii-regis, A. cephalonica, A. cilicica, A. nordmanniana, A. nordmanniana subsp. equi-trojani, A. numidica, A. pinsapo, A. pinsapo var. marocana y A. pinsapo var. tazaotana) con el fin de buscar caracteres filéticamente relevantes que ayuden a clarificar y complementar los patrones evolutivos basados en estudios moleculares. Las maderas estudiadas fueron cualitativamente similares, exceptuando ciertos caracteres propios de algunas procedencias. No obstante, la biometría de la madera permitió agrupar los diferentes taxones según su afinidad anatómica. A. alba, A. pinsapo, A. pinsapo var. marocana y A. pinsapo var. tazaotana mostraron caracteres biométricos afines que los distinguen del resto de abetos mediterráneos. Por otro lado, A. numidica mostró caracteres biométricos que lo distinguen de los abetos orientales (A. borisii-regis, A. cephalonica, A. cilicica, A. nordmanniana y A. nordmanniana subsp. equi-trojani) y lo asemejan a determinadas poblaciones ibéricas de A. pinsapo. La altura máxima de radios en número de células, la frecuencia de radios de más de 30 células y la longitud de traqueidas, pueden ser considerados como patrones específicos del phylum de los abetos mediterráneos

O índice de nutrição de nitrogênio no GS 3.3 é uma ferramenta eficaz para ajustar o nitrogênio necessário para alcançar a produtividade de trigo atingível

Current nitrogen (N) fertilization schedule for spring wheat was developed under a dominant crop-pasture rotation. After the year 2002, this cropping system was converted to continuous annual cropping systems under no-till, reducing soil N supply capacity progressively. Additionally, highest grain yield of new varieties increased N demand. The required additional N fertilizer can be adjusted by monitoring nutritional status of the crop. Our objectives were: i) to determine optimal N status at different phenological stages; ii) to quantify the wheat yield gap explained by N supply deficit, and iii) to assess the critical nitrogen nutrition index (NNI) value as a predictor of response to N fertilizer applied at GS 3.3. We adjusted the nitrogen dilution curve (Nc=4.17DM-0.31), deriving a critical NNI at GS 3.3 (NNI=1.24). Depending on soil N supply capacity and NNI at GS 3.3, wheat yield gap attributed to N supply deficit varied from 0 to 2.74 Mg ha⁻¹, averaging 0.76 Mg ha⁻¹. The critical NNI proposed at GS 3.3 was effective to diagnose the N crop demand to reach the attainable yield under different scenarios.El esquema actual de fertilización con nitrógeno (N) para el trigo de primavera se desarrolló bajo una rotación dominante de cultivo-pastura. Después de 2002, este sistema se convirtió en un sistema de cultivo anual continuo con labranza cero, reduciendo progresivamente la capacidad de suministro de N del suelo. Además, el mayor rendimiento en grano de las nuevas variedades aumentó la demanda de N. El fertilizante nitrogenado adicional requerido se puede ajustar monitoreando el estado nutricional del cultivo. Nuestros objetivos fueron: i) determinar el estado óptimo de N en diferentes etapas fenológicas; ii) cuantificar la brecha de rendimiento del trigo explicada por el déficit de suministro de N, y iii) evaluar el valor crítico del índice de nutrición nitrogenada (INN) como predictor de respuesta al agregado de fertilizante nitrogenado en GS 3.3. Ajustamos la curva de dilución de nitrógeno (Nc=4,17MS-0,31), derivando un INN crítico en GS 3.3 (INN=1,24). Según la capacidad de suministro de N del suelo y el INN en GS 3.3, la brecha de rendimiento del trigo atribuida al déficit de suministro de N varió de 0 a 2,74 Mg ha⁻¹, con un promedio de 0,76 Mg ha⁻¹. El INN crítico propuesto en GS 3.3 fue efectivo para diagnosticar la demanda de N del cultivo y lograr el rendimiento alcanzable en diferentes escenarios.O esquema atual de fertilização com nitrogênio (N) para o trigo de primavera foi desenvolvido sob uma rotação dominante de cultivo e pastagem. A partir de 2002, esse sistema passou a ser um sistema de cultivo anual contínuo com plantio direto, reduzindo progressivamente a capacidade de suprimento de N do solo. Além disso, o maior rendimento de grãos das novas variedades aumentou a demanda por N. O fertilizante de nitrogênio adicional necessário pode ser ajustado monitorando o estado nutricional da cultura. Nossos objetivos foram: i) determinar o estado ótimo do N em diferentes estágios fonológicos; ii) quantificar a lacuna de produtividade do trigo explicada pelo déficit de oferta de N e iii) avaliar o valor crítico do índice de nutrição de nitrogênio (INN) como preditor de resposta à adição de fertilizante nitrogenado no GS 3.3. Ajustamos a curva de diluição de nitrogênio (Nc=4,17MS-0,31), derivando um INN crítico em GS 3,3 (INN=1,24). De acordo com a capacidade de suprimento de N do solo e do INN no GS 3.3, a diferença de produtividade do trigo atribuída ao déficit de suprimento de N variou de 0 a 2,74 Mg ha⁻¹, com média de 0,76 Mg ha⁻¹. O INN crítico proposto em GS 3.3 foi eficaz para diagnosticar a demanda de N da cultura para atingir o rendimento alcançável em diferentes cenários

Small-spatial scale variations of nebular properties and the abundance discrepancy in three Galactic HII regions

We present results of long-slit spectroscopy in several slit positions that cover different morphological structures of the central parts of three bright Galactic HII regions: M8, M17 and NGC7635. We study the spatial distributions of a large number of nebular parameters such as the extinction coefficient, line fluxes, physical conditions and ionic abundances at the maximum spatial resolution attainable with our instrumentation. Particularly, our goal is to study the behaviour of the abundance discrepancy factor of O^{2+}, ADF(O^{2+}), defined as the logarithmic difference of the O^{2+} abundances derived from collisionally excited and recombination lines. We find that the ADF(O^{2+}) remains fairly constant along the slit positions of M8 and M17. In the case of NGC7635, we only detect the OII recombination lines in the integrated spectrum along the whole slit, where the ADF(O^{2+}) reaches a remarkably high value of about 0.59 dex. We compare our results with previous ones obtained for the Orion Nebula. We find several evidences that suggest the presence of a candidate to Herbig-Haro object in M8.Comment: 18 pages, 9 figures. Table A1 available only in the online version. Accepted for publication in MNRAS

Dissipation-driven generation of two-qubit entanglement mediated by plasmonic waveguides

We study the generation of entanglement between two distant qubits mediated by the surface plasmons of a metallic waveguide. We show that a V-shaped channel milled in a flat metallic surface is much more efficient for this purpose than a metallic cylinder. The role of the misalignments of the dipole moments of the qubits, an aspect of great importance for experimental implementations, is also studied. A careful analysis of the quantum-dynamics of the system by means of a master equation shows that two-qubit entanglement generation is essentially due to the dissipative part of the effective qubit-qubit coupling provided by the surface plasmons. The influence of a coherent external pumping, needed to achieve a steady state entanglement, is discussed. Finally, we pay attention to the question of how to get information experimentally on the degree of entanglement achieved in the system.Comment: 13 pages, 12 figure

The evolution of the footwall to the Ronda subcontinental mantle peridotites: insights from the Nieves Unit (western Betic Cordillera)

Strongly heterogeneous deformation and extreme metamorphic gradients characterize the dominantly carbonate Nieves Unit in the footwall to the Ronda mantle extrusion wedge in the western Betic Cordillera. A well-developed foliation and mineral lineation, together with isoclinal intrafolial folds, occur in silicate-bearing, calcite or dolomite marbles within a c. 1.5 km thick metamorphic aureole underlying the peridotites. For the inferred maximum pressure of 300 MPa, petrological investigations allow us to define temperature ranges for the main zones of the metamorphic aureole: >510 °C (probably c. 700 °C) for the forsterite zone; 510–430 °C for the diopside zone; 430–360 °C for the tremolite zone; 360–330 °C for the phlogopite zone. Field structural analysis integrated with petrological, microstructural and electron backscatter diffraction textural data document large finite strains consistent with general shear within the metamorphic aureole, associated with NW-directed thrusting of the peridotites. On the other hand, post-kinematic silicate growth suggests that heat diffusion from the high-temperature peridotites continued after the final emplacement of the Ronda mantle extrusion wedge, leading to final zoning of the metamorphic aureole and to local partial annealing of calcite marble textures, particularly in the highest-temperature zone of the thermally softened footwall carbonates. Following substantial cooling, renewed crustal shortening affected the whole Nieves Unit, resulting in widespread development of NE–SW-trending meso-scale folds

Body-axis organization in tetrapods: a model-system to disentangle the developmental origins of convergent evolution in deep time

Convergent evolution is a central concept in evolutionary theory but the underlying mechanism has been largely debated since On the Origin of Species. Previous hypotheses predict that developmental constraints make some morphologies more likely to arise than others and natural selection discards those of the lowest fitness. However, the quantification of the role and strength of natural selection and developmental constraint in shaping convergent phenotypes on macroevolutionary timescales is challenging because the information regarding performance and development is not directly available. Accordingly, current knowledge of how embryonic development and natural selection drive phenotypic evolution in vertebrates has been extended from studies performed at short temporal scales. We propose here the organization of the tetrapod body-axis as a model system to investigate the developmental origins of convergent evolution over hundreds of millions of years. The quantification of the primary developmental mechanisms driving body-axis organization (i.e. somitogenesis, homeotic effects and differential growth) can be inferred from vertebral counts, and recent techniques of three-dimensional computational biomechanics have the necessary potential to reveal organismal performance even in fossil forms. The combination of both approaches offers a novel and robust methodological framework to test competing hypotheses on the functional and developmental drivers of phenotypic evolution and evolutionary convergence

Experiencia con un repositorio de ejercicios de programación en un campus virtual: de una colección de libre acceso a otra guiada por la progresión del estudiante

El Campus Virtual es el entorno en el que se ha implementado una Virtualización de Casos Prácticos para facilitar el aprendizaje activo de la materia “Introducción a la programación” en la Universidad Complutense de Madrid. El carácter multidisciplinar de esta colección de casos prácticos los hace útiles en diversas titulaciones de la citada universidad. En este artículo se presenta la evolución que ha experimentado la Virtualización de Casos Prácticos, desde una colección de libre acceso a contenidos hasta la actual con un acceso controlado por la progresión del estudiante.Peer Reviewe