Bootstrap prediction intervals in State Space models

Prediction intervals in State Space models can be obtained by assuming Gaussian innovations and using the prediction equations of the Kalman filter, where the true parameters are substituted by consistent estimates. This approach has two limitations. First, it does not incorporate the uncertainty due to parameter estimation. Second, the Gaussianity assumption of future innovations may be inaccurate. To overcome these drawbacks, Wall and Stoffer (2002) propose to obtain prediction intervals by using a bootstrap procedure that requires the backward representation of the model. Obtaining this representation increases the complexity of the procedure and limits its implementation to models for which it exists. The bootstrap procedure proposed by Wall and Stoffer (2002) is further complicated by fact that the intervals are obtained for the prediction errors instead of for the observations. In this paper, we propose a bootstrap procedure for constructing prediction intervals in State Space models that does not need the backward representation of the model and is based on obtaining the intervals directly for the observations. Therefore, its application is much simpler, without loosing the good behavior of bootstrap prediction intervals. We study its finite sample properties and compare them with those of the standard and the Wall and Stoffer (2002) procedures for the Local Level Model. Finally, we illustrate the results by implementing the new procedure to obtain prediction intervals for future values of a real time series.Backward representation, Kalman filter, Local Level Model, Unobserved Components

Caracterización hidrogeológica de la parte noroeste del acuífero Las Sierras

La presente investigación fue realizada en el municipio de Managua, departamento de Managua. Dicha investigación presenta en su desarrollo la caracterización física del área de estudio, en la cual, se tomó en cuenta el clima, precipitación, temperatura, evapotranspiración, taxonomía de suelos y geomorfología. Otros factores considerados durante la investigación fue la geología, debido a que se considera la base de la hidrogeología, ya que es la que se encarga de condicionar el medio en que fluyen las aguas subterráneas; para lograr cumplir con los objetivos se tomó en cuenta la recarga e infiltración, inventario de fuentes de aguas subterráneas (Pozos), hidrodinámica del acuífero, el análisis hidráulico del acuífero, calidad de las aguas y la hidroquímica de las misma

Finanzas II

La presente Balota se refiere a las finanzas y aspectos que la componen, que se pueden definir como una derivación de la economía que trata el tema relacionado con la obtención y gestión del dinero, recursos o capital por parte de una persona o empresa. Las finanzas se refieren a la forma como se obtienen los recursos, a la forma como se gastan o consumen, a la forma como se invierten, pierden o rentabilizan. La investigación se realizó con el interés de conocer la importancia de las finanzas y su impacto en las diferentes etapas donde se toman en cuenta los estados financieros, mercados financieros, decisiones de inversión, decisiones de financiamiento entre otros, logrando así por medio de la investigación un profundo conocimiento en relación al tema y utilizando diferentes medios de información, dicha información estará basada en puntos estratégicos nombrados a continuación: Las divisas y su importancia dentro de las finanzas Conceptos generales de administración financiera Las finanzas como función organizacional de la empresa Objetivos e importancia de la administración financiera Valor y uso de la información financiera para una gestión eficienteTrabajo de suficiencia profesiona

Supercritical extraction of solid materials: a practical correlation related with process scaling

The supercritical fluid extraction (SFE) of vegetal raw materials is a large field of research, innovation and entrepreneurial developments. Optimization of process conditions is usually accomplished in analytical or laboratory scale equipment. Although SFE scaling is essential to attain industrial applications, studies in the literature are scarce. In this work, the kinetic behavior of 19 overall extraction curves (OEC's), obtained by the authors in previous works using NOVALINDUS Platform SFE facilities, and a set of 39 OEC's published by other authors, were considered all together to study SFE scaling. A general trend between the solvent flow rate and Barton kinetic constant was obtained for all extraction curves included in the data base, which comprise 10 different plant materials, temperatures in the range 298–333 K, pressures of 10–30 MPa, extractor volumes from 50 to 5200 cm2, particle diameters from 250 to 1400 μm and bed porosity in the range 0.59–0.97Lopez-Padilla A. Thanks to COLCIENCIAS (568 - 2012) and Medellin Mayor’s Office (Sapiencia/Enlaza Mundos Program, 2013) for the Ph.D. fellowship. This work was financed thanks ALIBIRD, S2013/ABI-2728 (Comunidad de Madrid) projec

One-pot synthesis of lignin-based electrospun oxygen reduction reaction electrocatalysts

Owing to their adequate combination of high surface area, electrical conductivity and electrochemical resistance, carbon fibers has been used for a long time as a catalyst supports and gas diffusion layers in the electrodes of fuel cells. However, the use of high amounts of noble metals in the cathode is hampering the commercial utilization of fuel cells. We have recently demonstrated that the electrospinning of lignin, a widely available and non-expensive biopolymer, allows the production of porous carbon cloths, which have been already utilized as electrodes for methanol oxidation and supercapacitors. In this work, we propose the electrospinning of lignin and noble/non-noble metal precursors for one-pot production of ORR catalysts. Fe, Co, Pd and Pt salts have been incorporated onto lignin-ethanol solutions and have been electrospun in microsized, metal-decorated lignin fibers. The stabilization and carbonization of these fibers have produced carbon electrodes with supported metallic nanoparticles up to 10 % wt. loading, avoiding the use of further impregnation steps. In addition, the incorporation of metal precursors in the lignin solution enhances the development of mesoporosity in the resulting carbon fibers, a desirable feature for increasing mass transfer rate when used as electrocatalyst, without compromising their electrical conductivity. The electrochemical characterization has confirmed that these carbon cloths are promising ORR catalysts that could be useful for the reducing the amount of noble metals in the electrodes or for allowing the use of non-noble metals as catalysts.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO/FEDER CTQ2015-68654-R MINECO/FEDER CTQ2015-66080-R MINECO PTA2015-11464-

Stellar energy loss rates beyond the standard model

It is known that the dipolemoments of the neutrino lead to important astrophysical and cosmological effects. In this regard, within the context of a U(1)B−L model, we develop and present novel analytical formulas to assess the effects of the anomalous magnetic moment and electric dipole moment of the neutrino on the stellar energy loss rates through some common physical process of pair-annihilation e+e− → (γ, Z, Z ) → ν¯ν. Our results show that the stellar energy loss rates strongly depend on the effective magnetic moment of the neutrino, but also on the parameters which characterize the adopted U(1)B−L mode

Metal-Organic Nanocapsules with Functionalized s-Heptazine Ligands

A metalloorganic capsule was synthesized where the ligand is a derivative of heptazine with three carboxylic groups that are coordinated to CuII cations, forming paddle-wheel motifs. Each nanocapsule is neutral, with 12 CuII centers and 8 ligands adopting a rhombicuboctahedron shape. It has almost 3 nm diameter, and the main intermolecular interactions in the solid are π··· π stacking between the C6N7 heptazine moieties. The nanocapsules can form monolayers deposited on graphite as observed by atomic force microscopy, which confirms their stability in solution

HERRAMIENTA SOFTWARE PARA LA IMPLEMENTACIÓN DE ALGORITMOS BASADOS EN TÉCNICAS METAHEURÍSTICAS, ORIENTADOS A OPTIMIZAR EL ESTABLECIMIENTO DE RUTAS PARA EL FLUJO DE INFORMACIÓN EN COMUNICACIONES DE MULTIDIFUSIÓN

En las transmisiones multicast, la optimización en el establecimiento de rutas es un área de especial interés en la comunidad académica. La necesidad de este tipo de transmisiones se pueden ver en las aplicaciones relacionadas con la telemedicina, la educación, el trabajo a la distancia, entretenimiento, etc. El objetivo de este trabajo es ser capaz de crear una herramienta de software que propone una o un conjunto de rutas a seguir en el momento de hacer una transmisiónmulticast. Esta ruta o un conjunto de rutas son el resultado de la ejecución de los algoritmos de recocido simulado y búsqueda tabú, cuyo principal objetivo es optimizar  funciones Hop Count, Delay, Cost and Bandwidth consumption

Update on indications, complications, and outcomes of scleral contact lenses

Background: The role of scleral contact lenses (SCLs) has increasingly expanded since the first lens was fitted more than a century ago. While it was initially prescribed for the management of severely compromised corneas, the indications for modern SCL use have expanded to include less severe diseases. In this review, we aimed to provide an up-to-date overview of the current indications, complications, and outcomes for the various types of SCLs. Methods: In this narrative review, we thoroughly searched the PubMed/MEDLINE database for literature published from January 1980 to November 2021. Only relevant up-to-date English references were included. Furthermore, the figures in this manuscript were derived from our unit’s patient documentation. Results: Currently, SCLs can successfully be used to manage ocular surface diseases, visually rehabilitate irregular corneas, and correct irregular refractive errors. Although newer materials have yielded the same visual outcomes with fewer complications, these consequences still occur in approximately one-third of contact lens wearers, including difficulties in insertion and/or removal, discomfort or pain, and developing either halos, blurriness, or haze. Even though most of these complications are minor and can be easily treated, a good practice is essential to avoid sight-threatening complications such as microbial keratitis. Conclusions: SCLs are indispensable in ophthalmic clinics. The development of better-quality SCLs has increased the number of indications and improved the achievable visual rehabilitation. The future of developing improvements in SCL design, materials, and fit, and the expansion of their indication range is promising