Selection and Agronomic Characterization of Leucaena spp. Genotypes for Cold Tolerance. I. Dry Matter Yield.

Biotypes of Leucaena spp (56) were evaluated in order to identify those with tolerance to low temperature and with desirable characteristics as a forage crop. Selection was done at two phases. Phase I: 92 days old seedlings (n=2800) were subjected at two temperatures treatments during 14 hours: T1= -8 °C and T2= -3 °C. Selection criteria was established as 50% of live leaves remained after treatments were applied. Phase II: Plants that survived phase I were planted at field conditions and agronomic characteristics were measured. Seventeen plants were selected from eleven different biotypes, resulting one from T1 and the rest from T2. Three plants showed good agronomic adaptation and greater chilling tolerance. Only one plant maintained live stem and meristematic tissue after a -8.8 °C freeze occurrence . Plants N° 2, 3, 5, 6, 8, 9, 10, 11, 12, 13, 15 and 16 were the most productive (Dry matter production)

Nonlinear Microscopy Techniques: Principles and Biomedical Applications

Nonlinear optical microscopy techniques have emerged as a set of successful tools within the biomedical research field. These techniques have been successfully used to study autofluorescence signals in living tissues, structural protein arrays, and to reveal the presence of lipid bodies inside the tissular volume. In the first section, the nonlinear contrast technique foundations is described, and also, a practical approach about how to build and combine this setup on a single confocal system platform shall be provided. In the next section, examples of the usefulness of these approaches to detect early changes associated with the progression of different epithelial and connective tissular diseases are presented

Evaluation of 3D image-treatment algorithms applied to optical-sectioning microscopy

La información extraída de especimenes biológicos es inherentemente tridimensional. Los datos tridimensionales (3D) permiten un mejor entendimiento de las estructuras y los eventos biológicos, comparados con sus proyecciones bidimensionales (2D), aunque a veces son más difíciles de manejar. Esto explica porqué actualmente se están investigando y mejorando las técnicas de seccionamiento óptico. El principal objetivo del presente trabajo fue evaluar la relevancia de algoritmos de tratamiento de imágenes, los cuales incluyen métodos de preprocesamiento (tales como promediación de imágenes, corrección de background y normalización de intensidades) y procesamiento (desconvolución de desborroneo y de restauración). Esto se realizó mediante la implementación de un algoritmo de cuantificación basado en el Laplaciano y un detector de puntos brillantes. Los algoritmos se aplicaron a un modelo 3D de adhesión celular en piel, basado en un espécimen comúnmente utilizado por nuestro grupo de investigación. Los resultados indican que ciertos métodos de preprocesamiento son requeridos para mejorar el rendimiento de los algoritmos de procesamiento, mientras que otros no deben ser aplicados para asegurar una adecuada y precisa cuantificación.Information extracted from biological specimens is inherently three-dimensional. Though it is sometimes hard to handle, three-dimensional (3D) data provides greater understanding of biological structures and events than its bidimensional (2D) projections. This explains why optical-sectioning techniques are currently being explored and enhanced. The main objective of the present work was to evaluate the relevance of image-treatment algorithms, which included preprocessing (such as image-averaging, background correction and normalization of intensities) and processing (deblurring and restoration deconvolution) methods. This was done by implementing a quantification algorithm based on the Laplacian and a bright-point detector. Algorithms were applied to a 3D cell-adhesion skin model, based upon a specimen commonly used by our research group. Results indicated that certain preprocessing methods are required to enhance the performance of processing algorithms, while others must not be applied in order to ensure an adequate and precise quantification.IV Workshop de Computación Gráfica, Imágenes y Visualización (WCGIV)Red de Universidades con Carreras en Informática (RedUNCI

Enhancement of an automatic algorithm for deconvolution and quantification of three-dimensional microscopy images

En trabajos previos hemos diseñado y desarrollado un software para la optimización del procesamiento de imágenes multidimensionales, el cual consiste de un algoritmo automático de desconvolución de restauración (desconvolución con restricción de positividad) y tres indicadores de restauración de la imágenes (Ancho Total a la Mitad del Máximo, Relación Contraste-Ruido y Relación Señal-Ruido) usados para evaluar cuantitativamente la calidad de restauración. Dado que el diseño del algoritmo se implementó en módulos desacoplados, hemos podido incorporar dos nuevos parámetros para evaluar la restauración de imágenes (indicadores tridimensionales basados en la función de Tenegrad) sin realizar cambios significativos en el código. La versión mejorada del algoritmo se utilizó para procesar imágenes tridimensionales utilizando diversas Funciones de Esparcimiento Puntual experimentales; las imágenes se obtuvieron mediante microscopia de campo amplio de fluorescencia del patrón de expresión de E-caderina en la piel de embriones de Rhinella arenarum y de microesferas fluorescentes. Se compararon los indicadores de restauración y el rendimiento de las versiones previa y mejorada del algoritmo. Los resultados indican que los indicadores basados en la función de Tenegrad coinciden con los evaluados previamente y que los nuevos módulos no incrementan significativamente el tiempo de procesamiento.In previous works we designed and developed a software tool for the optimization of multidimensional-image processing, which consisted of an automatic restoration deconvolution method (positive constrained deconvolution) and three image-restoration indicators (Full-Width at Half-Maximum, Contrast-to-Noise Ratio and Signal-to-Noise Ratio) used to assess the quality of restoration qualitatively. Since the algorithm’s design was implemented in uncoupled modules, we were able to introduce two new image-restoration parameters (two three-dimensional Tenegrad-based indicators) without mayor modifications to the script. The enhanced version of the algorithm was used to process raw three-dimensional images using several experimental Point Spread Functions; raw images were obtained by fluorescence wide-field microscopy of epidermal E-cadherin expression in Rhinella arenarum embryos and fluorescent microspheres. The image-restoration indicators and the performance of the previous and enhanced versions of the algorithm were compared. Results show that Tenengrad-based indicators concur with the previously used ones and that the new modules do not increase processing time significantly.Workshop de Computación Gráfica, Imágenes y Visualización (WCGIV)Red de Universidades con Carreras en Informática (RedUNCI

Serpentinites and serpentinites within a fossil subduction channel : La Corea mélange, eastern Cuba

A variety of metaultramafic (serpentinite) rocks in La Corea mélange, Sierra de Cristal, eastern Cuba, show differences in chemical, textural and mineralogical characteristics demonstrating a variety of protoliths. The mélange originated during the Cretaceous as part of the subduction channel associated with the Caribbean island arc. This mélange contains high pressure blocks in a serpentinite matrix and occurs at the base of the large tabular Mayarí-Cristal ophiolite. Two principal groups of serpentinites have been identified in the mélange: a) antigorite serpentinite, mainly composed of antigorite and b) antigorite-lizardite serpentinite, composed of mixtures of antigorite and lizardite and bearing distinctive porphyroblasts of diopsidic clinopyroxene. Antigorite serpentinites are closely related to tectonic blocks of amphibolite (representing subducted MORB) and constitute deep fragments of the serpentinitic subduction channel formed during hydration of the mantle wedge. The composition of the antigorite-lizardite serpentinites and the presence of clinopyroxene porphyroblasts in this type of rock suggest that abyssal lherzolite protoliths transformed into serpentinite before and during incorporation (as tectonic blocks) in the shallow part of the subduction channel. Although the studied rocks have different origin, mineralogical compositions and textures, they display similar PGE compositions, suggesting that these elements experienced no significant redistribution during metamorphism. Both types of serpentinites were exposed together in the La Corea mélange during the Late Cretaceous, during obduction of the overriding Mayarí-Baracoa ophiolitic belt that led to exhumation of the subduction channel (mélange)

High-pressure greenschist to blueschist facies transition in the Maimón Formation (Dominican Republic) suggests mid-Cretaceous subduction of the Early Cretaceous Caribbean Arc

The Maimón Formation (Cordillera Central, Dominican Republic) is formed of metamorphosed bi-modal mafic-felsic volcanic rocks and sedimentary horizons of Early Cretaceous age deposited in the forearc of the nascent Caribbean island arc. Two structural-metamorphic zones depict an inverted metamorphic gradient: the Ozama shear zone, which records intense mylonitic and phyllonitic deformation and ubiquitous metamorphic recrystallization, tectonically overlies the much less deformed and variably recrystallized rocks of the El Altar zone. The presence of ferri-winchite and high-Si phengite, first reported in this paper, in the peak metamorphic assemblage of rocks of the Ozama shear zone (actinolite + phengite + chlorite + epidote + quartz + albite ± ferri-winchite ± stilpnomelane) point to subduction-related metamorphism. Pseudosection calculations and intersection of isopleths indicate peak metamorphic conditions of ~ 8.2 kbar at 380 °C. These figures are consistent with metamorphism in the greenschist/blueschist facies transition, burial depths of ~ 25-29 km and a thermal gradient of ~ 13-16 °C/km. Our new data dispute previous models pointing to metamorphism of Maimón rocks under a steep thermal gradient related to burial under a hot peridotite slice. Instead, we contextualize the metamorphism of the Maimón Formation in a subduction scenario in which a coherent slice of the (warm) Early Cretaceous forearc was engulfed due to intra-arc complexities and regional-scale-driven tectonic processes operating in the late Early Cretaceous. Integration of our findings with previous studies on metamorphic complexes in Hispaniola suggests that a major tectonic event affecting the whole arc system took place at c. 120-110 Ma

Cellular outline segmentation using fractal estimators

Segmentation in biological images is essential for the determination of biological parameters that allow the construction of models of several biological problems. This helps to establish clear relationships between those models and the parameter estimation, and for elaboration of key experiments that give support to biological theories. Segmentation is the process of qualitative or quantitative information extraction (shape, texture, physical and geometric properties, among others). These quantities are needed to compute the biological descriptors for further classification (v.g., cell counting, development stage assessment, and many others). This process is almost always supervised (i.e., human assisted), since the quality of the images that are produced with classic microscopy technologies have defects that in general disallow the application of unsupervised segmentation techniques. In this paper we investigate the use of the a local fractal dimension estimation as an image descriptor for microscopy images. This local descriptor appears to be robust enough to perform unsupervised or semisupervised segmentations, specifically in our study. We applied this technique on microscopy images of amphibian embryos' skin in which, using immunofluorescence techniques, we have labeled the cell adhesion molecule E-Cadherin. This molecule is one of the key factors of the Ca2+- dependent cell-cell adhesion. Segmentation of the cellular outlines was performed using a processing workflow, which can be repeatedly applied to a set of similar images, from which information is extracted for characterization and eventual quantification purposes.Facultad de Informátic

An Alternative Scenario on the Origin of Ultra-High Pressure (UHP) and Super-Reduced (SuR) Minerals in Ophiolitic Chromitites: A Case Study from the Mercedita Deposit (Eastern Cuba)

The origin of the assemblage of ultra-high pressure (UHP), super-reduced (SuR) and several crustally derived phases in ophiolitic chromitites is still hotly debated. In this paper, we report, for the first time, this assemblage of phases in ophiolitic chromitites of the Caribbean. We studied the Mercedita chromitite deposit in the eastern Cuban ophiolitic complexes. The mineral phases were characterized using microRaman spectroscopy, energy-dispersive spectroscopy with a scanning electron microscope (SEM-EDS), X-ray microdiffraction and electron microprobe analyses. Mineral concentrates were prepared using hydroseparation techniques. We have identified oriented clinopyroxene lamellae in chromite, oriented rutile lamellae in chromite, moissanite hosted in the altered matrix of the chromitite, graphite-like amorphous carbon, corundum and SiO2 hosted in healed fractures in chromite grains, and native Cu and Fe-Mn alloy recovered in heavy-mineral concentrates obtained by hydroseparation. This assemblage may correspond to UHP-SuR conditions, implying recycling of chromitite in the mantle or formation of the chromite grains at deep mantle depths, followed by emplacement at a shallow level in the mantle. However, the chromitite bodies contain gabbro sills oriented parallel to the elongation of the chromitite lenses, and these show no evidence of HP/UHP metamorphism. Therefore, the identified "exotic" phases may not be indicative of UHP. They formed independently as oriented clinopyroxene lamellae in chromite during cooling (clinopyroxene and rutile), in super-reduced microenvironments during the serpentinization processes, and by transference of subducted crustal material to the mantle wedge via cold plume

Garnierites and garnierites: Textures, mineralogy and geochemistry of garnierites in the Falcondo Ni-laterite deposit, Dominican Republic

Garnierites (Ni-Mg-bearing phyllosilicates) are significant ore minerals in Ni-laterites of the hydrous silicate-type. In the Falcondo Ni-laterite deposit (Dominican Republic), garnierites are found within the saprolite horizon mainly as fracture-fillings and thin coatings on joints. Field observations indicate an important role of active brittle tectonics during garnierite precipitation. Different greenish colours and textures can be distinguished, which correspond to different mineral phases, defined according to X-ray diffraction (XRD) and electron microprobe (EMP) analyses: a) talc-like (10 Å-type), b) serpentine-like (7 Å-type), c) a mixture of talc- and serpentine-like, and d) sepiolite-like types. Compositional data indicate continuous Mg-Ni solid solution along the joins lizardite-népouite (serpentine-like), kerolite-pimelite (talc-like) and sepiolite-falcondoite (sepiolite-like). In general, talc-like garnierite is dominant in Falcondo Ni-laterite and displays higher Ni contents than serpentine-like garnierites. EMP analyses showing deviations from the stoichiometric Mg-Ni solid solutions of serpentine and talc are best explained by talc- and serpentine-like mixing at the nanoscale. A detailed textural study by means of quantified X-ray element imaging provides a wealth of new information about the relationships between textural position, sequence of crystallization and mineral composition of the studied garnierite samples. These results indicate several stages of growth with variable Ni content, pointing to recurrent changes in the physicalchemical conditions during garnierite precipitation. In addition, our detailed mineralogical study of the Falcondo garnierites revealed that the different types identified have characteristic H2O content and SiO2/MgO ratios, which play important roles during the pyrometallurgy process

Segmentación de contornos celulares utilizando estimadores fractales

La segmentación en imágenes biológicas es de importancia crucial para la determinación de descriptores que permitan, entre otras cosas, elaborar modelos de diversos procesos biológicos, cotejar parámetros en dichos modelos, y proponer o rebatir teorías. Sin embargo, el proceso de segmentación de la información necesaria para el cómputo de los descriptores es casi siempre un proceso asistido, dado que la calidad de las imágenes que se pueden generar con la tecnología actual de microscopía clásica, adolecen de defectos que impiden el uso adecuado de técnicas de segmentación autónoma. En este trabajo se propone el uso de la dimensión fractal box (FBD) como descriptor local, para la segmentación de imágenes de microscopía de la piel de embriones de anfibios en las que, usando técnicas de imnunofluorescencia, se ha marcado E-Cadherina, una molécula de adhesión celular, expresada en membranas celulares y responsable de la adhesión dependiente de Ca2+. El propósito del presente trabajo fue elaborar un workflow de procesamiento para ser aplicado sin supervisión a un grupo no determinado de imágenes de la misma naturaleza, de las que se intenta extraer la información requerida para los propósitos de caracterización y eventual cuantificación.Red de Universidades con Carreras en Informática (RedUNCI