Multifractal Properties of Time Series of Synthetic Earthquakes Obtained from a Spring-Block Model.

With the spring-block model proposed by Olami, Feder, and Christensen (OFC), we obtained a time series of synthetic earthquakes with different values of the conservation level (ß), which measures the fraction of the energy that a relaxing block passes to its neighbors. The time series have multifractal characteristics, and we analyzed them with the Chhabra and Jensen method. We calculated the width, symmetry, and curvature parameters for each spectrum. As the value of conservation level increases, the spectra widen, the symmetric parameter increases, and the curvature around the maximum of the spectra decreases. In a long series of synthetic seismicity, we located earthquakes of the greatest magnitude and built overlapping windows before and after them. For the time series in each window, we performed multifractal analysis to obtain multifractal spectra. We also calculated the width, symmetry, and curvature around the maximum of the multifractal spectrum. We followed the evolution of these parameters before and after large earthquakes. We found that the multifractal spectra had greater widths, were less skewed to the left, and were very pointed around the maximum before rather than after large earthquakes. We studied and calculated the same parameters and found the same results in the analysis of the Southern California seismicity catalog. This suggests that there seems to be a process of preparation for a great earthquake and that its dynamics are different from the one that occurs after this mainshock based on the behavior of the parameters mentioned before.

Acantholippia seriphioides: chemical biodiversity of wild populations from the Cuyo region in Argentina / Acantholippia seriphioides: biodiversidad química de poblaciones silvestres de la región de Cuyo de la Argentina

Nineteen samples from the aerial parts in bloom of Acantholippia seriphioides (Verbenaceae) were collected in three provinces belonging to the Cuyo region of Argentina. The essential oils were obtained by hydrodistillation, yielding between 0.57 and 2.46 percent (v/w). On the basis of the 13 main compounds determined by GC-FID-MS, representing the 87.2 and 95.3 percent of the total identified, four chemotypes were determined: carvacrol, thymol, cis and trans-dihydrocarvone and linalool-geraniol. The co-occurrence of different chemotypes in a same population indicates that the sample collection must be carefully done with the aid of an in situ olfactory testing of the plants, since no morphological differences at first sight were observed among them. The results showed in this study suggest that the pattern of variations for this species exists throughout its natural distribution area...

Se colectaron 19 muestras de partes aéreas en floración de Acantholippia seriphioides (Verbenaceae) de tres provincias de la región de Cuyo de la Argentina. Los aceites esenciales fueron obtenidos por hidrodestilación, arrojando rendimientos entre 0.57 y 2.46 por ciento (v/p). A partir de la determinación por GC-FID-MS de los 13 compuestos principales, que representaban entre el 87.2 y 95.3 por ciento del total de los identificados, fueron determinados cuatro quimiotipos: carvacrol, timol, cis y trans-dihidrocarvona, y linalol-geraniol. La co-ocurrencia de diferentes quimiotipos en una misma población indica que la colecta debe ser realizada con la ayuda de un examen olfatorio in situ de la planta, ya que, a primera vista no se observan diferencias morfológicas entre ellas. Los resultados sugieren que el patrón de variación para esta especie existe en toda su área de distribución natural...

Trastornos neuropsiquiátricos en estudiantes universitarios con bajo rendimiento académico de una universidad privada de Medellín / Neuropsychiatric disorders in a sample of university students with academic lower performance of a private Medellin University

El propósito de ésta investigación fue establecer la frecuencia de trastornos neuropsiquiátricos en estudiantes universitarios con bajo rendimiento académico de la Universidad San Buenaventura de la ciudad de Medellín (Colombia). De una población de 300 estudiantes se calculó una muestra aleatoria de 39 sujetos con problemas académicos de diferentes carreras, lo cual correspondió al 13 % de la población, para detectar trastornos cuya frecuencia fuera superior al 2%, con un nivel de confianza del 95% y un poder del 80%. Se utilizó una entrevista estructurada neuropsiquiátrica para adultos (MINI-Plus). Los trastornos que se presentaron con más frecuencia fueron depresión mayor (10.3%) y riesgo de suicidio (10.3%). El 61.5% de los estudiantes de la muestra no reunió criterios para ningún tipo de diagnóstico psiquiátrico.

The purpose of this research was to establish the frequency of neuropsychiatric disorders in college students with poor academic achievement of San Buenaventura University in Medellin- Colombia. From a population of 300 students, a random sample of 39 subjects with academic difficulties from different undergraduate programs which corresponds to 13% of the population was taken, in order to detect disorders with a frequency upper than 2%, a confidence level of 95 % and a power of 80 %. A neuropsychiatric structured interview for adults (Mini-PLUS) was used. 61.5% did not show any neuropsychiatric diagnosis; however, 10.3% presented major depression criteria, and 10.3% suicide risk.

Use of irradiated human amnion as a matrix for limbal stem cell culture.

Several ocular diseases affect the corneal surface; the development of effective technologies for the treatment of corneal lesions has brought about an improvement in the quality of life of affected patients. The aim of this study is to culture and characterize limbal stem cells cultured on gamma ((60)Co) radiosterilized human amnion (RHA). Limbal stem cells were isolated from ten preserved samples of corneal transplant. The cells were cultured since primary culture until expanded cells on RHA and stained with monoclonal antibodies to establish their immunophenotype, after which cytokeratin 12 and Vimentin were positive by immunohistochemistry. The immunophenotype remained constant since primary culture until expanded cells in RHA. The RHA and cells construct were structurally integrated. Immunohistochemistry was cytokeratin 12, Vimentin positive, and cytokeratin 19 negative. In vitro limbal cells maintain a constant epithelial transition immunophenotype in culture up to primary culture until expanded cells on RHA.

Description and interpretation of the bracts epidermis of Gramineae (Poaceae) with rotated image with maximum average power spectrum (RIMAPS) technique.

During the last few years, RIMAPS technique has been used to characterize the micro-relief of metallic surfaces and recently also applied to biological surfaces. RIMAPS is an image analysis technique which uses the rotation of an image and calculates its average power spectrum. Here, it is presented as a tool for describing the morphology of the trichodium net found in some grasses, which is developed on the epidermal cells of the lemma. Three different species of grasses (herbarium samples) are analyzed: Podagrostis aequivalvis (Trin.) Scribn. & Merr., Bromidium hygrometricum (Nees) Nees & Meyen and Bromidium ramboi (Parodi) Rúgolo. Simple schemes representing the real microstructure of the lemma are proposed and studied. RIMAPS spectra of both the schemes and the real microstructures are compared. These results allow inferring how similar the proposed geometrical schemes are to the real microstructures. Each geometrical pattern could be used as a reference for classifying other species. Finally, this kind of analysis is used to determine the morphology of the trichodium net of Agrostis breviculmis Hitchc. As the dried sample had shrunk and the microstructure was not clear, two kinds of morphology are proposed for the trichodium net of Agrostis L., one elliptical and the other rectilinear, the former being the most suitable.

Influence of wine fermentation temperature on the synthesis of yeast-derived volatile aroma compounds.

The yeast Saccharomyces cerevisiae synthesises a variety of volatile aroma compounds during wine fermentation. In this study, the influence of fermentation temperature on (1) the production of yeast-derived aroma compounds and (2) the expression of genes involved in aroma compounds' metabolism (ADH1, PDC1, BAT1, BAT2, LEU2, ILV2, ATF1, ATF2, EHT1 and IAH1) was assessed, during the fermentation of a defined must at 15 and 28 degrees C. Higher concentrations of compounds related to fresh and fruity aromas were found at 15 degrees C, while higher concentrations of flowery related aroma compounds were found at 28 degrees C. The formation rates of volatile aroma compounds varied according to growth stage. In addition, linear correlations between the increases in concentration of higher alcohol and their corresponding acetates were obtained. Genes presented different expression profiles at both temperatures, except ILV2, and those involved in common pathways were co-expressed (ADH1, PDC1 and BAT2; and ATF1, EHT1 and IAH1). These results demonstrate that the fermentation temperature plays an important role in the wine final aroma profile, and is therefore an important control parameter to fine-tune wine quality during winemaking.

Quantitative study of Xanthosoma violaceum leaf surfaces using RIMAPS and variogram techniques.

Two new imaging techniques (rotated image with maximum averaged power spectrum (RIMAPS) and variogram) are presented for the study and description of leaf surfaces. Xanthosoma violaceum was analyzed to illustrate the characteristics of both techniques. Both techniques produce a quantitative description of leaf surface topography. RIMAPS combines digitized images rotation with Fourier transform, and it is used to detect patterns orientation and characteristics of surface topography. Variogram relates the mathematical variance of a surface with the area of the sample window observed. It gives the typical scale lengths of the surface patterns. RIMAPS detects the morphological variations of the surface topography pattern between fresh and dried (herbarium) samples of the leaf. The variogram method finds the characteristic dimensions of the leaf microstructure, i.e., cell length, papillae diameter, etc., showing that there are not significant differences between dry and fresh samples. The results obtained show the robustness of RIMAPS and variogram analyses to detect, distinguish, and characterize leaf surfaces, as well as give scale lengths. Both techniques are tools for the biologist to study variations of the leaf surface when different patterns are present. The use of RIMAPS and variogram opens a wide spectrum of possibilities by providing a systematic, quantitative description of the leaf surface topography.