Imidazolium fumarate

In the title compound, C3H5N2 +·C4H3O4 −, the dihedral angle between the imidazolium ring and the plane formed by the fumarate anion is 80.98 (6)°. In the crystal structure, inter­molecular O—H⋯O and N—H⋯O hydrogen bonds form extended chains along [100] and [01], creating a two-dimensional network

On the Specification of Non-functional Properties of Systems by Observation

Domain specific languages play a cornerstone role in Model-Driven Engineering (MDE) for representing models and metamodels. So far, most of the MDE community efforts have focused on the specification of the functional properties of systems. However, the correct and complete specification of some of their non-functional properties is critical in many important distributed application domains, such as embedded systems, multimedia applications or e-commerce services. In this paper we present an approach to specify QoS requirements, based on the observation of the system actions and of the state of its objects. We show how this approach can be used to extend languages which specify behavior in terms of rules, and how QoS characteristics can be easily expressed and reused across models. We show as well how this approach enables the specification of other important properties of systems, such as automatic reconfiguration of the system when some of the QoS properties change.Ministerio de Ciencia e Innovación TIN2008-031087Junta de Andalucía P07-TIC-0318

Evaluación del desempeño medioambiental del sector agrícola de América Latina y el Caribe bajo el supuesto de eficiencia natural y gerencial, utilizando DEA

This study uses the Data Envelopment Analysis to measure the agricultural environmental performance under the assumption of natural and managerial disposability, but also evaluates the Returns to Scale and Damages to Scale in Latin America and the Caribbean during 2012. Seven agricultural variables are analyzed: animal feed, fertilizers, capital stock, labor, land, value of the gross agricultural production and agricultural emissions (CO2eq). The results found that the Bahamas, Brazil, Chile, Costa Rica and Mexico attained the maximum efficiency level in all efficiency measurements. These countries present the best performances compared with the other countries evaluatedEste estudio utiliza el Análisis de Envolventes de Datos para medir el desempeño medioambiental agrícola de América Latina y el Caribe; con suposición de natural y managerial disposability, y rendimientos a escala y daños a escala; durante 2012. Se utilizan siete variables: alimentación animal, fertilizantes, reserva de capital, mano de obra, tierra, valor de la producción agrícola y emisiones agrícolas (CO2eq). Los resultados muestran que las Bahamas, Brasil, Chile, Costa Rica y México alcanzaron el máximo nivel de eficiencia en todas las mediciones de eficiencia. Estos países presentan el mejor desempeño en comparación con el resto de países evaluadosJunta de Andalucía SEJ-132Ministerio de Economia y Competitividad TIN2013-46801-C4-1-rJunta de Andalucía P11-TIC-805

Evaluación del desempeño medioambiental de Sector Agrícola de América Latina y el Caribe utilizando el DEA e Índice de Malmquist

El análisis de la productividad agrícola y su evaluación supone una importante base para elaborar políticas destinadas al desarrollo económico, para garantizar la seguridad alimentaria y mejorar la renta de los agricultores. La literatura es amplia en este tema, si bien son pocos los trabajos que evalúan la eficiencia medioambiental de la agricultura, en particular para América Latina y el Caribe (ALC). Este enfoque es esencial para el diseño de las políticas económicas y ambientales de cualquier Estado y, en definitiva, para el desarrollo sostenible de este sector. Esta investigación utiliza el Análisis Envolvente de Datos para evaluar la eficiencia medioambiental de 25 países de ALC bajo dos conceptos: natural disposability y managerial disposability. Se incorpora al análisis el índice de Malmquist para determinar el grado de desplazamiento, el progreso tecnológico, y la frontera de eficiencia para el periodo de 2000-2012. La medición de este índice se utiliza considerando que existe un cruce entre las fronteras de eficiencias de los dos años consecutivos. Se han considerado seis variables inputs: alimentación animal, fertilizantes, mano de obra agrícola, reserva de capital-cultivo, reserva de capital-ganado y la tierra agrícola; y dos variables outputs: producción agrícola y las emisiones de CO2 equivalente agrícolas. Los resultados indican mayor eficiencia bajo el supuesto de natural disposability siempre por arriba de la eficiencia bajo managerial disposability, sin embargo, en ambas fronteras hay evidencia de mejoras en la productividad debido a los progresos tecnológicos en los países evaluadosMinisterio de Economia y Competitividad TIN2013-46801-C4-1-rMinisterio de Economia y Competitividad P11-TIC-8052Junta de Andalucía P11-TIC-7124Junta de Andalucía SEJ-13

Coherent State Description of the Ground State in the Tavis-Cummings Model and its Quantum Phase Transitions

Quantum phase transitions and observables of interest of the ground state in the Tavis-Cummings model are analyzed, for any number of atoms, by using a tensorial product of coherent states. It is found that this "trial" state constitutes a very good approximation to the exact quantum solution, in that it globally reproduces the expectation values of the matter and field observables. These include the population and dipole moments of the two-level atoms and the squeezing parameter. Agreement in the field-matter entanglement and in the fidelity measures, of interest in quantum information theory, is also found.The analysis is carried out in all three regions defined by the separatrix which gives rise to the quantum phase transitions. It is argued that this agreement is due to the gaussian structure of the probability distributions of the constant of motion and the number of photons. The expectation values of the ground state observables are given in analytic form, and the change of the ground state structure of the system when the separatrix is crossed is also studied.Comment: 38 pages, 16 figure

Medición de los rendimientos a escala y daños a escala en la evaluación natural y managerial del sector agrícola de América Latina y el Caribe, utilizando DEA

Este trabajo analiza la eficiencia unificada bajo tres enfoques natural disposability, managerial disposability, y bajo los dos anteriores juntos natural y managerial disposability. Además analiza los tipos de Rendimientos a Escala (RTS) y los Daños a Escala (DTS), en el sector agrícola de América Latina y El Caribe (ALC) durante el año 2012. Las diferentes medidas se estiman utilizando la técnica matemática no paramétrica Análisis de Envolvente de Datos (DEA), para la evaluación medioambiental, que permite descomponer el desempeño agrícola en medidas de eficiencia. Para ello, se utilizan las ocho variables convencionales de la agricultura: la alimentación animal, consumo de fertilizantes, reserva de capital-cultivo, reserva de capital-ganado, población económicamente activa, la tierra agrícola, valor de la producción agrícola y emisiones agrícolas. Los resultados obtenidos indican una mayor eficiencia bajo natural disposability en los países evaluados. Bajo este enfoque, la mayoría de los países presentan RTS constantes y RTS decrecientes, mientras bajo managerial disposability tienden a DTS constantes y DTS crecientesMinisterio de Economia y Competitividad TIN2013-46801-C4-1-rMinisterio de Economia y Competitividad P11-TIC-8052Junta de Andalucía P11-TIC-7124Junta de Andalucía SEJ-13

Study through Geant4, for Time Resolution characterization of different detectors arrays coupled with two SiPMs, as a function of: the scintillator plastic material, its volumetric dimensions and the location of the radiation emission source

The high time resolution detectors are relevant in those experiments or simulations were the particles to detect, have a very short time of flight (TOF), and due this it´s required that the detections times are ranged between ns. & ps.Using Geant4 software, it was made thirty simulations of coupled detectors to plastic scintillators with two silicon photomultipliers (SiPMs) located on the scintillator’s central sides. To characterize the time resolution, it was required to quantify the optical photons that reach the Score in a certain time, which are generated by muons on the surface of the plastic scintillator. Different configurations of muon beams were simulated at energy of 1 GeV, to interact with the configuration of the scintillator material of its corresponding arrangement. The simulations were made varying three parameters: the scintillator material “BC404 & BC422”, its size, and the location of the radiation source. Fifteen simulations correspond to BC404 material & fifteen simulations to BC422 material respectively. The first five simulations consisted in varying the scintillator’s volumetric size and collocate the muons beam guided randomly distributed over it, the next five simulations differentiate from setting up a directly centered beam, and the last five simulations for guide the beam on the left lower corner of each scintillator.The best time resolution achieved was σ= 8.67 +/− 0.26 ps., reported by the detector with BC422 scintillator material which has a volume of 20x20x3 mm3

3-Nitro­benzoic acid–3-methyl-4-nitro­pyridine 1-oxide (1/1)

The title adduct, C7H5NO4·C6H6N2O3, forms part of an ongoing study of the design of non-centrosymmetric systems based on 3-methy-4-nitro­pyridine 1-oxide. The components of the adduct are linked by inter­molecular O—H⋯O hydrogen bonds. The rings of the two components are nearly planar, with a dihedral angle of 11.9 (2)° between the planes. The supra­molecular structure shows that mol­ecules of the title complex are linked into sheets by a combination of strong O—H⋯O and weak C—H⋯O hydrogen bonds

Field enhancement and spectral features of hexagonal necklaces of silver nanoparticles for enhanced nonlinear optical processes

Access to the online abstract in the journal: https://doi.org/10.1364/OE.26.022394 © 2018 Optical Society of America. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reservedThe nonlinear properties of hybrid metallic-dielectric systems are attracting great interest due to their potential for the enhancement of frequency conversion processes at nanoscale dimensions. In this work, we theoretically and experimentally address the correlation between the near field distribution of hexagonal plasmonic necklaces of silver nanoparticles formed on the surface of a LiNbO3 crystal and the second harmonic generation (SHG) produced by this nonlinear crystal in the vicinities of the necklaces. The spectral response of the hexagonal necklaces does not depend on the polarization direction and is characterized by two main modes, the absorptive high-energy mode located in the UV spectral region and the lower energy mode, which is strongly radiant and extends from the visible to the near infrared region. We show that the spatial distribution of the enhanced SHG is consistent with the local field related to the low energy plasmon mode, which spectrally overlaps the fundamental beam. The results are in agreement with the low absorption losses of this mode and the two-photon character of the nonlinear process and provide deeper insight in the connection between the linear and nonlinear optical properties of the hybrid plasmonic-ferroelectric system. The study also highlights the potential of hexagonal necklaces as useful plasmonic platforms for enhanced optical processes at the nanoscaleSpanish Ministry of Economy and Competitiveness (MINECO) under project MAT2016- 76106-R and the Comunidad de Madrid (grant S2013/MIT-2740). C.T. acknowledges funding from the VILLUM Foundation (Villum Investigator, grant no. 16498). L.E.B and M.O.R also acknowledges financial support from the Spanish Ministry of Economy and Competitiveness, through The “María de Maeztu” Programme for Units of Excellence in R&D (MDM-2014-0377

Acrysof® toric intraocular lens implantation in cataract surgery

Aim: To assess the medium term outcomes of Acrysof® toric intraocular lens implantation in 54 patients (54 eyes). Methods: Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), preoperative astigmatism, residual postoperative astigmatism, and global average and model-specific intraocular lens (IOL) rotation grade were analyzed. Results: At 2-months of follow-up,the mean UCVA was 0.83 (SD: 0.14) Snellen scale, with 73.9% of the patients ≥0.8, and 32.6% with 1.0. Mean BCVA achieved was 0.94 (SD: 0.10). Mean preoperatory astigmatism was –2.25 diopters (D) (SD: 0.78), and mean postoperative astigmatism was -0.32 D (SD: 0.56), with significant differences between both groups (p<0.001). Model-specific mean residual astigmatism was –0.1 D for T3, –0.27 D for T4 and –0.43 D for T5, without significant differences between the three models (p=0.483). Mean IOL-axis rotation grade was 3.87±3.25 degrees, with 91.6% of implanted lens within 10° of predicted axis. Discussion: T3, T4 and T5 Acrysof® Toric intraocular lenses can correct preoperative astigmatism with a high success rate in terms of UCVA, and residual postoperative astigmatism, with minimum IOL-rotation grade at 2 months follow-up period