Excited electronic states from a variational approach based on symmetry-projected Hartree--Fock configurations

Recent work from our research group has demonstrated that symmetry-projected Hartree--Fock (HF) methods provide a compact representation of molecular ground state wavefunctions based on a superposition of non-orthogonal Slater determinants. The symmetry-projected ansatz can account for static correlations in a computationally efficient way. Here we present a variational extension of this methodology applicable to excited states of the same symmetry as the ground state. Benchmark calculations on the C$_2$ dimer with a modest basis set, which allows comparison with full configuration interaction results, indicate that this extension provides a high quality description of the low-lying spectrum for the entire dissociation profile. We apply the same methodology to obtain the full low-lying vertical excitation spectrum of formaldehyde, in good agreement with available theoretical and experimental data, as well as to a challenging model $C_{2v}$ insertion pathway for BeH$_2$. The variational excited state methodology developed in this work has two remarkable traits: it is fully black-box and will be applicable to fairly large systems thanks to its mean-field computational cost

Inestabilidad de laderas en el Valle del Meredal (Asturias, NO de España)

[Resumen] En el valle del Meredal se han identificado 64 movimientos en masa que incluyenmovimientos complejos, deslizamientos rotacionales, flujos y avalanchas rocosas, cuyo desarrollo está condicionado por el diferente comportamiento mecánico de los materiales del sustrato. La aplicación de distintos criterios de cronología relativa basados en el grado de superposición y conservación de las formas ha permitido diferenciar cinco clases de movimientos en masa en cuanto a su edad. Desde el punto de vista regional, la incisión de la red fluvial asociada a los cambios climáticos cuaternarios y a la elevación del margen cantábrico parece ser el factor determinante del origen de esta dinámica.[Abstract] In the Meredal valley 64 landslides, including complex movements, rock slumps,flows and rock avalanches have been identified. The development of these landslides is conditioned by the mechanical behaviour of the different bedrock lithologies. Five chronological classes of movements have been established by applying several relative chronology criteria, as superposition and preservation degree of the landslides. From the regional point of view, fluvial drainage incision linked to quaternary climate changes and to the uplift of the cantabrian margin seems to be determinant in the origin of this dynamics

Optimización de la extracción de aceite de semilla de dátil mediante la ayuda de tecnologías hidrotermales y de ultrasonido

The date seed is a by-product from the date industry. Its use as a source of added-value compounds is of great interest. Oil accounts for 5-13% of the seed’s weight. Soxhlet extraction with organic solvents is the traditional method for obtaining oil from seeds. In this work, hydrothermal pre-treatments and sonication are proposed to make the extraction a more environmentally friendly process. Factors such as sonication time and temperature and hexane-to-seed ratio (H/S) have been considered. Response surface methodology was applied for optimization. Hydrothermal treatments increased oil recovery. H/S was the most influential factor, and was close to 7 mL/g seeds for both samples. 71% recovery was achieved for native seeds after 15 min sonication at 45 ºC, and 80% for 180 ºC-treated seeds after 45 min at 35 ºC when compared to Soxhlet extraction. These conditions comply with our initial aim. Pre-treatments seem to have a negative effect on oil stability, although this observation needs to be confirmed.La semilla de dátil es un subproducto de la industria datilera. Su uso como fuente de compuestos de valor añadido sería muy interesante. El aceite representa el 5-13% del peso de la semilla. La extracción mediante Soxhlet con disolventes orgánicos es el método tradicional para obtener aceite de semillas. En este trabajo se proponen pretratamientos hidrotérmicos y sonicación para diseñar un proceso de extracción más respetuoso con el medio ambiente. Se han considerado factores como el tiempo y la temperatura de sonicación y la proporción hexano/semilla (H/S). La optimización del proceso se llevó a cabo por el método de superficie de respuesta. Los tratamientos hidrotérmicos aumentaron el porcentaje de recuperación. El factor más influyente fue H/S, y su valor óptimo estuvo cerca de 7 mL/g para ambas muestras. La recuperación óptima fue del 71% para las semillas sin tratamiento tras 15 min de sonicación a 45 ºC, y del 80% para las semillas tratadas a 180 ºC después de 45 min a 35 ºC. Estos resultados cumplen con nuestro objetivo inicial. Sin embargo, los pretratamientos parecen tener un efecto negativo sobre la estabilidad del aceite, lo que se confirmará en estudios posteriores

The kinematics of the quadrupolar nebula M1-75 and the identification of its central star

The link between the shaping of bipolar planetary nebulae and their central stars is still poorly understood. The kinematics and shaping of the multipolar nebula M 1-75 are hereby investigated, and the location and nature of its central star are briefly discussed. Fabry-Perot data from GHaFAS on the WHT sampling the Doppler shift of the [N II] 658.3 nm line are used to study the dynamics of the nebula, by means of a detailed 3-D spatio-kinematical model. Multi-wavelength images and spectra from the WFC and IDS on the INT, and from ACAM on the WHT, allowed us to constrain the parameters of the central star. The two pairs of lobes, angularly separated by ~22 degrees, were ejected simultaneously approx. ~3500-5000 years ago, at the adopted distance range from 3.5 to 5.0 kpc. The larger lobes show evidence of a slight degree of point symmetry. The shaping of the nebula could be explained by wind interaction in a system consisting of a post-AGB star surrounded by a disc warped by radiative instabilities. This requires the system to be a close binary or a single star which engulfed a planet as it died. On the other hand, we present broad- and narrow-band images and a low S/N optical spectrum of the highly-reddened, previously unnoticed star which is likely the nebular progenitor. Its estimated V-I colour allows us to derive a rough estimate of the parameters and nature of the central star.Comment: 8 pages, 6 figures, accepted for publication in Astronomy & Astrophysic

Systematic identification of phenotypically enriched loci using a patient network of genomic disorders

Background Network medicine is a promising new discipline that combines systems biology approaches and network science to understand the complexity of pathological phenotypes. Given the growing availability of personalized genomic and phenotypic profiles, network models offer a robust integrative framework for the analysis of "omics" data, allowing the characterization of the molecular aetiology of pathological processes underpinning genetic diseases. Methods Here we make use of patient genomic data to exploit different network-based analyses to study genetic and phenotypic relationships between individuals. For this method, we analyzed a dataset of structural variants and phenotypes for 6,564 patients from the DECIPHER database, which encompasses one of the most comprehensive collections of pathogenic Copy Number Variations (CNVs) and their associated ontology-controlled phenotypes. We developed a computational strategy that identifies clusters of patients in a synthetic patient network according to their genetic overlap and phenotype enrichments. Results Many of these clusters of patients represent new genotype-phenotype associations, suggesting the identification of newly discovered phenotypically enriched loci (indicative of potential novel syndromes) that are currently absent from reference genomic disorder databases such as ClinVar, OMIM or DECIPHER itself. Conclusions We provide a high-resolution map of pathogenic phenotypes associated with their respective significant genomic regions and a new powerful tool for diagnosis of currently uncharacterized mutations leading to deleterious phenotypes and syndromes

Bases psicobiológicas de la adicción a cocaína

El principal mecanismo de acción de la cocaína es la inhibición de la recaptación de dopamina y noradrenalina, produciendo un aumento de estos neurotransmisores en la sinapsis. El consumo agudo de cocaína produce una serie de cambios bastante conocidos en el sistema cerebral de recompensa. Sin embargo, el consumo crónico, produce, además, otra serie de cambios a nivel molecular que llevan al sujeto desde una situación de consumo puntual, a una situación de dependencia. Se han propuesto diferentes teorías explicativas de este fenómeno como la sensibilización del incentivo, o la homeostasis y alostasis neuroquímica, planteamientos basados en el condicionamiento clásico y operante. Por otra parte, se ha señalado la intervención de diferentes moléculas y vías de segundos mensajeros, que producen, en última instancia, una serie de cambios neuronales mantenidos a muy largo plazo, probablemente permanentes, que se podrían relacionar con la vulnerabilidad a las recaídas, propia de la adicción a cocaína, incluso años después de abandonar el consumo

Revisiting the link between business strategy and performance: Evidence from hotels

This paper aims to investigate the competitive success factors for hotel companies and examine the link between business strategy and performance. Using a structured questionnaire, the researchers collected data from hotel managers in Spain. Study results suggest that a firm’s assets and strategies have a greater influence on performance than industry forces do. This lack of direct influence by industry forces is due to the sector’s specific characteristics, which cannot be overlooked during analysis. Based on these research findings, theoretical and managerial implications and future research are presented

Scanning Electron Microscope Study of Wohlfahrtia magnifica (Schiner, 1862) (Diptera: Sarcophagidae) I. Structures with Parasitic and Possible Taxonomic Meaning

The larval development of Wohlfahrtia magnifica (the most important dipteran causing sheep myiasis in the Palearctic region) has been studied by means of scanning electron microscopy. The ultrastructure of mouth-hooks, oral ridges, labial lobes, body spines and anterior and posterior peritremes is described for the first time. Their possible adaptations to a parasitic lifeway are also discussed. Thus, the use of new structures in the Sarcophagidae taxonomy is proposed from the point of view of their ultrastructure and adaptative morphology