202 research outputs found
Summability of stochastic processes: a generalization of integration and co-integration valid for non-linear processes
The order of integration is valid to characterize linear processes; but it is not appropriate for non-linear worlds. We propose the concept of summability (a re-scaled partial sum of the process being Op(1)) to handle non-linearities. The paper shows that this new concept, S (d): (i) generalizes I (d); (ii) measures the degree of persistence as well as of the evolution of the variance; (iii) controls the balancedness of non-linear relationships; (iv) opens the door to the concept of co-summability which represents a generalization of co-integration for non-linear processes. To make this concept empirically applicable, an estimator for d and its asymptotic properties are provided. The finite sample performance of subsampling confidence intervals is analyzed via a Monte Carlo experiment. The paper finishes with the estimation of the degree of summability of the macroeconomic variables in an extended version of the Nelson-Plosser database.Co-integration, Co-summability, Integrated processes, Non-linear balanced relationships, Non-linear processes, Summability
Computational Tools for Image Processing, Integration, and Visualization of Simultaneous OCT-FLIM Images of Tissue
Multimodal imaging systems have emerged as robust methods for the characterization of atherosclerotic plaques and early diagnosis of oral cancer. Multispectral wide-field Fluorescence Lifetime Imaging Microscopy (FLIM) has been shown to be a capable optical imaging modality for biomedical diagnosis oral cancer. A fiber-based endoscope combined with an intensified charge-coupled device (ICCD) allows to collect and split the fluorescence emission into multiple bands, from which the fluorescence lifetime decay in each spectral channel can be calculated separately. However, for accurate calculations, it is necessary to gather multiple gates increasing the imaging time. Since this time is critical for real-time in vivo applications. This study presents a novel approach to using Rapid Lifetime Determination (RLD) methods to considerably shorten this time period.
Moreover, the use of a dual-modality system, incorporating Optical Coherence Tomography (OCT) and FLIM, which simultaneously characterizes 3-D tissue morphology and biochemical composition of tissue, leads to the development of robust computational tools for image processing, integration, and visualization of these imaging techniques. OCTFLIM systems provide 3D structural and 2D biochemical tissue information, which the software tools developed in this work properly integrate to assist the image processing, characterization, and visualization of OCT-FLIM images of atherosclerotic plaques.
Additionally, plaque characterization is performed by visual assessment and requires a trained expert for interpretation of the large data sets. Here, we present two novel computational methods for automated intravascular (IV) OCT plaque characterization. The first method is based on the modeling of each A-line of an IV-OCT data set as a linear combination of a number of depth profiles. After estimating these depth profiles by means of an alternating least square optimization strategy, they are automatically classified to predefined tissue types based on their morphological characteristics. The second method is intended to automatically identify macrophage/foam cell clusters in atherosclerotic plaques. Vulnerable plaques are characterized by presenting a necrotic core below a thin fibrous cap, and extensive infiltration of macrophages/foam cells. Thus, the degree of macrophage accumulation is an indicator in determining plaque progression and probability of rupture. In this work, two texture features are introduced, the normalized standard deviation ratio (NSDRatio) and the entropy ratio (ENTRatio), to effectively classify areas in the plaque with macrophage/foam cell infiltration. Since this methodology has low complexity and computational cost, it could be implemented for in vivo real time identification of macrophage/foam cell presence
Computational Tools for Image Processing, Integration, and Visualization of Simultaneous OCT-FLIM Images of Tissue
Multimodal imaging systems have emerged as robust methods for the characterization of atherosclerotic plaques and early diagnosis of oral cancer. Multispectral wide-field Fluorescence Lifetime Imaging Microscopy (FLIM) has been shown to be a capable optical imaging modality for biomedical diagnosis oral cancer. A fiber-based endoscope combined with an intensified charge-coupled device (ICCD) allows to collect and split the fluorescence emission into multiple bands, from which the fluorescence lifetime decay in each spectral channel can be calculated separately. However, for accurate calculations, it is necessary to gather multiple gates increasing the imaging time. Since this time is critical for real-time in vivo applications. This study presents a novel approach to using Rapid Lifetime Determination (RLD) methods to considerably shorten this time period.
Moreover, the use of a dual-modality system, incorporating Optical Coherence Tomography (OCT) and FLIM, which simultaneously characterizes 3-D tissue morphology and biochemical composition of tissue, leads to the development of robust computational tools for image processing, integration, and visualization of these imaging techniques. OCTFLIM systems provide 3D structural and 2D biochemical tissue information, which the software tools developed in this work properly integrate to assist the image processing, characterization, and visualization of OCT-FLIM images of atherosclerotic plaques.
Additionally, plaque characterization is performed by visual assessment and requires a trained expert for interpretation of the large data sets. Here, we present two novel computational methods for automated intravascular (IV) OCT plaque characterization. The first method is based on the modeling of each A-line of an IV-OCT data set as a linear combination of a number of depth profiles. After estimating these depth profiles by means of an alternating least square optimization strategy, they are automatically classified to predefined tissue types based on their morphological characteristics. The second method is intended to automatically identify macrophage/foam cell clusters in atherosclerotic plaques. Vulnerable plaques are characterized by presenting a necrotic core below a thin fibrous cap, and extensive infiltration of macrophages/foam cells. Thus, the degree of macrophage accumulation is an indicator in determining plaque progression and probability of rupture. In this work, two texture features are introduced, the normalized standard deviation ratio (NSDRatio) and the entropy ratio (ENTRatio), to effectively classify areas in the plaque with macrophage/foam cell infiltration. Since this methodology has low complexity and computational cost, it could be implemented for in vivo real time identification of macrophage/foam cell presence
Summability of stochastic processes: a generalization of integration for non-linear processes
The order of integration is valid to characterize linear processes; but it is not appropriate for non-linear worlds. We propose the concept of summability (a re-scaled partial sum of the process being O-p(1)) to handle non-linearities. The paper shows that this new concept, S (delta): (i) generalizes I (delta); (ii) measures the degree of persistence as well as of the evolution of the variance; (iii) controls the balancedness of non-linear relationships; (iv) opens the door to the concept of co-summability which represents a generalization of co-integration for non-linear processes. To make this concept empirically applicable, an estimator for delta and its asymptotic properties are provided. The finite sample performance of subsampling confidence intervals is analyzed via a Monte Carlo experiment. The paper finishes with the estimation of the degree of summability of the macroeconomic variables in an extended version of the Nelson-Plosser database.Financial support from SEJ-2007-63098, ECO-2010-19357, CONSOLIDER 2010 (CSD 2006-00016), and EXCELECON S-2007/HUM-044 grants is gratefully acknowledged
La contribución de la mujer en la economÃa rural de Castilla y León
La participación de la mujer en el tejido socioeconómico de las zonas rurales se ha visto frecuentemente infravalorada. Sin embargo, desde hace pocos años existe una clara conciencia por parte de los poderes públicos de que la inclusión de la mujer en las estrategias de dinamización socioeconómica del mundo rural es fundamental para fijar población y generar renta y empleo. El objetivo de este trabajo se centra en determinar la contribución económica de la mujer en el desarrollo del medio rural de la Comunidad Autónoma de Castilla y León. Para ello, se ha analizado la relación existente entre el grado de desarrollo de los municipios rurales y las caracterÃsticas socioeconómicas de las mujeres que los habitan. Para alcanzar tal fin, se han empleado tres tipos de técnicas multivariantes: el análisis de componentes principales, la regresión múltiple y el análisis de conglomerados. Los resultados alcanzados permiten afirmar que la participación económica y social de la mujer en el medio rural de Castilla y León se configura como una condición indispensable para alcanzar un mayor bienestar y nivel de desarrollo en esas zonas.Género, desarrollo rural, métodos cuantitativos, Castilla y León (España)., Agricultural and Food Policy, J16, O18, R23,
Manganese and zinc in acidic agricultural soils from Central Spain: Distribution and phytoavailability prediction with chemical extraction tests
The extractability and distribution of manganese (Mn) and zinc (Zn) were evaluated in acidic agricultural soils from Central Spain. Both single (0.1 M hydrochloride [HCl] and 0.05 M ethylenediaminetetraacetate [EDTA]) and sequential extraction procedures (SEP) (modified Tessier procedure and Community Bureau of Reference [BCR] protocol) were applied to 29 representative soils that belong to the Alfisol, Inceptisol, and Entisol orders. Average relative Mn extractabilities with respect to the total content (16.6% for HCl and 31.9% for EDTA) were higher than those of Zn (7.7% for HCl and 6.5% for EDTA). Manganese was mainly released in the oxide-bound phase of both SEP (33.1% for modified Tessier and 48.9% for BCR), whereas Zn was predominantly found in the residual fraction (49.1% for modified Tessier and 31.4% for BCR). Significant correlations were only found between the amounts of extractable Zn and the oxide-bound fraction in both SEP. Few relationships were established between Zn fractions extracted by the BCR procedure and those obtained with the Tessier method. Both metal concentrations in spring barley (Hordeum vulgare L., cv Beka) grown in 11 selected soils and the calculated soil/plant transfer coefficients (soil/plant concentration factor (CF), mean values of 31.2 for Mn and 196 for Zn) were poorly (or not at all) correlated with the different extracted soil fractions (single and sequential). A number of empirical equations have been obtained by regression analyses to predict the Mn and Zn uptake by barley, with soil metal forms and some soil characteristics as components (pH for Mn and organic matter for Zn). Values of R2 in the equations were relatively low (<68%). Single-extraction techniques produced worse results than SEP for the evaluation of Mn phytoavailability. The modified Tessier procedure provided better predictions of Zn uptake by plants than BCR, but not better than those obtained with the HCl extraction method
Incorporated Diffusion Ordered Heteronuclear Multiple Bond Correlation Spectroscopy, 3D iDOSY-HMBC. Merging of Diffusion Delay with Long Polarization Transfer Delay of HMBC
3D iDOSY-HMBC pulse sequences allow the simplification of HMBC data of mixtures via separation in the diffusion domain. The presented methods utilize incorporated DOSY approach, iDOSY, where the existing delays of the basic pulse sequence are utilized for diffusion attenuation. In the simplest form of the proposed 3D iDOSY-HMBC sequences, no extra delays or RF-pulses were required, only two diffusion gradients were added within HMBC polarization transfer delay.Peer reviewe
Extending and Measuring the Quality of Fresh-Cut Fruit and Vegetables: a Review
The market sales of ready - to - use vegetables have grown rapidly in recent decades as a result of changes in consumer attitudes especially consumption of fresh-cut lettuce and carrot due to their use in prepared salads. Chlorine solutions have been widely used to sanitise fruit and vegetables in the fresh-cut industry. However, the association of chlorine with the possible formation of carcinogenic chlorinated compounds in water has called into question the use of chlorine in food processing. There is a real need to find alternatives for preservation of fresh-cut fruit and vegetables in order to improve the efficacy of washing treatments. Alternatives or modified methods have been proposed as antioxidants, irradiation, ozone, organics acids, modified atmosphere packaging, whey permeate etc.: however, none have yet gained widespread acceptance by the industry. For this reason the devlopment of alternatives and markers in order to measure the efficacy of these alternatives are needed
Análisis de métodos en la gestión de almacenes, en el periodo 2005 -2018: revisión sistemática de la literatura científica
El objetivo de la presente revisión sistemática es identificar y analizar los métodos en la gestión de almacenes en el periodo 2005-2018 con la finalidad de promover la gestión adecuada de los almacenes. Para lograr ello, se ha desarrollado la presente revisión sistemática en cuatro capítulos.
En el primero, se presenta el estudio y parte del desarrollo de la revisión sistemática, donde se incluye el desarrollo de la introducción, la formulación de la pregunta de investigación, la justificación objeto de estudio y el planteamiento del objetivo general y específicos. Para ello, las fuentes de información empleadas corresponden a base de datos entre las que se encuentran: Ebsco, Scienciedirect, Redalyc, Scielo, Google Académico, Repositorio de la Pontificia Universidad Católica del Perú, Repositorio de la Universidad Privada del Norte, Repositorio de la Universidad Cesar Vallejo. En el segundo, se presenta la planificación de la metodología donde se incluye el tipo de estudio, relación de fuentes de búsqueda, criterios de selección, exclusión y descarte de duplicados para recolección de información. En el tercero, se presentan los resultados de la presenta revisión sistemática, donde se evidencio que 14 artículos presentan el método ABC, 3 artículos presentan el método 5S´, 2 artículos presentan el método MRP y 5 artículos presentan el método FIFO, asimismo se identificó los países de latinos donde fueron materia de análisis y estudio. Como capítulo final se incluyen las conclusiones de cada método encontrado en la gestión de almacenes: Método ABC, Método 5S´, Método MRP y Método FIFO
Plasma polymers from oregano secondary metabolites: Antibacterial and biocompatible plant-based polymers
Bacterial infection of chronic wounds is a major healthcare problem that affects the quality of life of millions of patients worldwide and leads to a substantial healthcare cost burden. This project focused on the manufacture of a potential wound healing agent. Plasma polymers from oregano secondary metabolites (PP-OSMs) were fabricated by radiofrequency plasma-enhanced chemical vapor deposition (RF-PECVD) in continuous and pulse plasma modes at room temperature. The surface, biocompatibility, and antibacterial properties of the PP-OSMs were investigated. Polymers fabricated by RF-PECVD retained the functional groups of OSMs, promoted human dermal fibroblast adhesion, inhibited Staphylococcus aureus attachment, and eliminated Pseudomonas aeruginosa. The PP-OSM coatings are potential candidates for use in medical applications where cell biocompatibility and antibacterial properties are required
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