Endohedral terthiophene in zigzag carbon nanotubes: Density functional calculations

The inclusion and encapsulation of terthiophene (T3) molecules inside zigzag single-walled carbon nanotubes (CNTs) is addressed by density functional calculations. We consider the T3 molecule inside five semiconducting CNTs with diameters ranging from 9.6 to 12.7 Ang. Our results show that the T3 inclusion process is exothermic for CNTs with diameters larger than 9.5 Ang. The highest energy gain is found to be of 2 eV, decreasing as the CNT diameter increases. This notable effect of stabilization is attributed to the positively charged CNT inner space, as induced by its curvature, which is able to accommodate the neutral T3 molecule. The band structure of the T3@CNT system shows that T3 preserves its electronic identity inside the CNTs, superimposing their molecular orbitals onto the empty CNT band structure without hybridization. Our results predict that the electronic states added by the T3 molecules would give rise to optical effects and nonradiative relaxation from excited states.Comment: 5 pages, 5 figures, 1 table, accepted in PR

gtfB and spaP virulence genes in Streptococcus mutans strains and their relationship with the DMFT index

Universidad de Talca, Chile; Vásquez Ibarra, Sonia; Lobos Gilabert, Olga; Padilla Espinoza, CarlosObjetivo: El propósito de este estudio fue determinar la presencia de genes de virulencia en cepas de Streptococcus mutans (S. mutans) aisladas desde saliva de individuos de diferentes edades y asociarlas con el índice COPD y ceod según corresponda. Material y método: A partir de un total de 120 individuos de ambos sexos, se conformaron 4 grupos de 30 personas, que se separaron de acuerdo con los siguientes rangos etarios: 3-5, 6-9, 12-15 y mayores de 18 años. A cada individuo se le determinó el índice COPD y ceod según correspondiera y se realizó recuento salival de S. mutans. La detección de los genes de virulencia: gtfB y spaP se realizó por reacción en cadena de la polimerasa convencional. Resultados: Se estableció una asociación positiva entre el recuento bacteriano e índice COPD y ceod. El 100% de las cepas aisladas evidenciaron la presencia del gen gtfB y el 63,6% presentaron el gen spaP. No hubo evidencia estadísticamente significativa que relacionará un alto recuento bacteriano e índice COPD y ceod con la mayor presencia de genes que codifican factores de virulencia en cepas de S. mutans. Resumen: Aim: The aim of this study was to determine the presence of gtfB and spaP virulence genes in Streptococcus mutans strains isolated from saliva taken from individuals of different ages. Material and method: A total of 120 individuals of both sexes were studied. They were assigned to one of 4 groups, with 30 individuals in each one, according to age; 3-5, 6-9, 12-15, and older than 18 years old. DMFT (decayed, missing, and filled teeth) and DMFT indexes were determined in each participant, depending on his/her age. S. mutans microbial counts were performed. The gtfB and spaP virulence genes were detected using conventional PCR. Results: A positive association was found between microbial count and DMFT and DMFT indexes. All the isolated strains demonstrated the presence of gtfB, and 63.6% of the strains had spaP genes. No association was found between high bacterial counts or DMFT and DMFT indexes with the presence of genes that code for virulence factors in S. mutans strains

Lensing by Kerr Black Holes. II: Analytical Study of Quasi-Equatorial Lensing Observables

In this second paper, we develop an analytical theory of quasi-equatorial lensing by Kerr black holes. In this setting we solve perturbatively our general lens equation with displacement given in Paper I, going beyond weak-deflection Kerr lensing to third order in our expansion parameter epsilon, which is the ratio of the angular gravitational radius to the angular Einstein radius. We obtain new formulas and results for the bending angle, image positions, image magnifications, total unsigned magnification, and centroid, all to third order in epsilon and including the displacement. New results on the time delay between images are also given to second order in epsilon, again including displacement. For all lensing observables we show that the displacement begins to appear only at second order in epsilon. When there is no spin, we obtain new results on the lensing observables for Schwarzschild lensing with displacement.Comment: 23 pages; final published versio

Characterization, stability and solubility of co-amorphous systems of glibenclamide and L-arginine at different pH

Purpose: To investigate the stability and solubility of co-amorphous systems of glibenclamide (GBC) with L-arginine (L-Arg) at different pH values. Methods: Three co-amorphous solids of GBC and L-Arg were obtained by fast solvent evaporation using 2:1, 1:1 and 1:2 stoichiometries. All co-amorphous systems were characterized by XRPD, FTIR, RAMAN and NMR-solid state as well as thermal techniques such as DSC and TGA. The stability of coamorphous systems was evaluated by indicative stability and stability in relevant physiological media was measured at different pH values. Results: The chemical characterization suggest that there was no proton transference between L-Arg and GBC indicative of co-amorphous solids. Stability studies showed that all the co-amorphous solids are unstable under humid conditions and only the co-amorphous system of GBC: L-Arg 1:2 was stable in all the pH values tested. Solubility studies at different pH values showed that the co-amorphous GBC: L-Arg 1:1 and 1:2, showed increasing solubility values even at pH < 7 (0.6468 mg/mL at pH 1.2 for coamorphous GBC: L-Arg 1:2 at the first hour) where free GBC was not soluble. Conclusion: Co-amorphous systems of GBC and L-Arg, is an interesting strategy to increase the solubility of poorly-soluble drugs at acidic pH values Keywords: Co-amorphous; Glibenclamide; L-Arginine; Solubility; Stabilit

Skin lesion detection and classification using convolutional neural network for deep feature extraction and support vector machine

Pigmented skin lesion identification is essential for detecting harmful pathologies related to this large organ, especially cancer. An analysis of the different methods and projects developed to diagnose these illnesses throughout the years showed that they had become very useful tools to identify melanoma, dermatofibroma, and basal cell carcinoma, among other types of cancer, are seen through the use of new computer-aided technologies. The most common diagnosis is based on dermoscopy and the dermatologist expertise that can improve accuracy with image detection techniques and classification by computer. Therefore, this study aims to develop software models able to detect and classify skin cancer. The following work is based on the use of dermoscopy images obtained from the HAM10000 dataset, a database with 10000 images previously tested and validated for research use. The main process is divided into three relevant parts: image segmentation, feature extraction (FE) using ten different pre-trained Convolutional Neural Networks (CNNs), and Support Vector Machine (SVM) to establish a classification model. According to the results, the models of classification performed very well using the image segmentation step, showing average accuracies between 80.67% (Xception) and 90% (Alexnet). In contrast to the process without using image segmentation, where no method reached 60%. AlexNet plus SVM model showed the minor running time and presented the higher accuracy rate (90.34%) for the correct identification and classification of the seven categories of cutaneous lesions taken into account

Concerted changes in tropical forest structure and dynamics: evidence from 50 South American long-term plots

Several widespread changes in the ecology of old-growth tropical forests have recently been documented for the late twentieth century, in particular an increase in stem turnover (pan-tropical), and an increase in above-ground biomass (neotropical). Whether these changes are synchronous and whether changes in growth are also occurring is not known. We analysed stand-level changes within 50 long-term. monitoring plots from across South America spanning 1971-2002. We show that: (i) basal area (BA: sum of the cross-sectional areas of all trees in a plot) increased significantly over time (by 0.10 +/- 0.04 m(2) ha(-1) yr(-1), mean +/- 95% CI); as did both (ii) stand-level BA growth rates (sum of the increments of BA of surviving trees and BA of new trees that recruited into a plot); and (iii) stand-level BA mortality rates (sum of the cross-sectional areas of all trees that died in a plot). Similar patterns were observed on a per-stem basis: (i) stem density (number of stems per hectare; 1 hectare is 10(4) m(2)) increased significantly over time (0.94 +/- 0.63 stems ha(-1) yr(-1)); as did both (ii) stem recruitment rates; and (iii) stem mortality rates. In relative terms, the pools of BA and stem density increased by 0.38 +/- 0.15% and 0.18 +/- 0.12% yr(-1), respectively. The fluxes into and out of these pools-stand-level BA growth, stand-level BA mortality, stem recruitment and stem mortality rates-increased, in relative terms, by an order of magnitude more. The gain terms (BA growth, stem recruitment) consistently exceeded the loss terms (BA loss, stem mortality) throughout the period, suggesting that whatever process is driving these changes was already acting before the plot network was established. Large long-term increases in stand-level BA growth and simultaneous increases in stand BA and stem density imply a continent-wide increase in resource availability which is increasing net primary productivity and altering forest dynamics. Continent-wide changes in incoming solar radiation, and increases in atmospheric concentrations of CO2 and air temperatures may have increased resource supply over recent decades, thus causing accelerated growth and increased dynamism across the world's largest tract of tropical forest

Bases para la configuración del sistema de investigación de la cadena de la papa en colombia

En torno a la investigación sobre la problemática del sector papicultor en Colombia se han dado cita gran número de entidades, dentro de las cuales son de destacar Institutos de Investigación como el ICA, universidades como la Universidad Nacional de Colombia, específicamente la Facultad de Agronomía en sus programas de pre y postgrado, Fedepapa, casas comerciales, Sociedades de Investigación, etc. De las investigaciones adelantadas sobre tal problemática, muchas no han repercutido en un mejoramiento de la población involucrada a lo largo de los eslabones que conforman la cadena de este importante rubro de producción, en razón, en gran parte, a la carencia en el país de un sistema de investigación que regule y coordine acciones atinentes a enfrentar los problemas más relevantes y prioritarios de orden técnico y socioeconómico que afectan el gremio papicultor. Sin embargo, no se puede desconocer que la cadena de la papa se ha beneficiado de algunos programas de investigación, especialmente realizados por el ICA a lo largo de su existencia, tal es el caso del desarrollo de variedades, muchas de las cuales mantienen su vigencia comercial, por ser apropiadas para las condiciones ambientales Colombianas.Several research organizations, including the U.N., especifically the Agriculture School in its undergraduate and graduate programs, ICA, the Federation of Potato growers, comercial agrochemical companies, research associations, etc have joined forces around the problems that plague the potato growers in Colombia. Much research has been carried out on this issue, but relatively few has had an impact on the improvement of living conditions for the peasantry involved along the chain of production and marketing processes, due to the lack of a system that coordinates actions regarding the most relevant and urgent problems of the potato guild in the technical and socioeconomic spheres. Nonetheless, the potato growers have undoubtedly benefitted from the achievements of past research, especially by the Colombia n Agricultural Institute (ICA) regarding the development of improved potato varieties, several of them still used for commercial purposes

Data from an international multi-centre study of statistics and mathematics anxieties and related variables in university students (the smarvus dataset)

This large, international dataset contains survey responses from N = 12,570 students from 100 universities in 35 countries, collected in 21 languages. We measured anxieties (statistics, mathematics, test, trait, social interaction, performance, creativity, intolerance of uncertainty, and fear of negative evaluation), self-efficacy, persistence, and the cognitive reflection test, and collected demographics, previous mathematics grades, self-reported and official statistics grades, and statistics module details. Data reuse potential is broad, including testing links between anxieties and statistics/mathematics education factors, and examining instruments’ psychometric properties across different languages and contexts.2-s2.0-85176239315Mayı

Riesgo de caries dental en pacientes de tres a seis años que acuden a la clínica de la de la Universidad Nacional Federico Villarreal

El objetivo del presente estudio fue determinar el riesgo de caries dental que presentan los pacientes de tres a seis años que acudieron a la clínica de la Universidad Nacional Federico Villarreal en el año 2011. La muestra fue de 50 niños de ambos sexos que cumplieron con los criterios de inclusión y exclusión, a quienes se les realizó una encuesta y una evaluación del índice de higiene oral para determinar la presencia y nivel de riesgo de caries dental. Los resultados obtenidos fueron que en los factores de riesgo de caries dental estudiados en la presente investigación están presentes indistintamente la edad y el sexo. El factor de riesgo más prevalente es el cepillado dental con 21 casos, seguido del factor visita al odontólogo con 19 casos. El riesgo de caries dental más prevalente es el “Riesgo Bajo” con un 40.8%, seguido de 37.6% con un “Riesgo Mediano” y 21.8% presentan “Riesgo Alto”. Al relacionar los valores se determinó que no hay diferencias significativas de los factores de riesgo de caries dental en relación al sexo, encontrándose diferencias altamente significativas entre los niveles de caries dental y la presencia de los factores de riesgo.Palabras claves: caries dental, riesgo, factores de riesg

Características Tecnológicas de la fibra blanca de Alpaca Huacaya en la zona Altoandina de Apurímac

The study aimed to estimate five technological characteristics of the white fibre of Huacaya alpaca of a rural community of the Andean region of Apurimac, Peru. Fibre samples (n=405) were taken from the middle of the rib area prior to shearing. The variables studied were: mean diameter of fibre (MDF), coefficient of variation of fibre diameter (CVDF), comfort index (IC), curvature index (ICur) and spinning fineness (FiHi), by sex and age group according to teeth (DL=Deciduous teeth; 2D=2 permanent teeth; 4D=4 teeth; BLL=all teeth). The MDF for males and females was 19.6 and 20.1 µm respectively (p<0.05), where values increased with age (p<0.05). No statistical difference was found by sex or age for CVDF. The IC was 96.8% in males and 95.5% in females (p<0.05), decreasing with age (p<0.05). The ICur was similar between sexes and difference due to age was only observed between DL with 4D and BLL (p<0.05). The FiHi was different between sexes (p<0.05) and between Dl and BLL (p<0.05). Significant and positive relationships was found between MDF with FiHi and IC with ICur, and negatives between MDF with IC, MDF with ICur, IC with FiHi, ICur with FiHi, and ICur with CVDF. These results indicate that in this area of the country there are alpacas with good potential in fibre quality.Con el objeto de estimar cinco características tecnológicas de la fibra de alpaca Huacaya color blanco en una comunidad de la zona altoandina de Apurímac, Perú, se evaluaron 405 muestras tomadas de la zona media del costillar, previa a la esquila. Las variables estudiadas fueron: media del diámetro de fibra (MDF), coeficiente de variación del diámetro de la fibra (CVDF), índice de confort (IC), índice de curvatura (ICur) y finura al hilado (FiHi), según sexo y grupo etario de acuerdo a la dentadura (DL=Dientes de leche; 2D=2 dientes; 4D=4 dientes; BLL=boca llena). La MDF para machos y hembras fue de 19.6 y 20.1 µm, respectivamente (p<0.05), donde los valores amentaron con la edad (p<0.05). No hubo diferencias en el CVDF por sexos ni entre grupos etarios. El IC fue de 96.8% en machos y 95.5% en hembras (p<0.05), disminuyendo conforme aumenta la edad (p<0.05). El ICur fue similar entre sexos y la diferencia entre edades solo se aprecia entre DL con 4D y BLL (p<0.05). La FiHi fue diferente entre sexos (p<0.05) y entre los grupos etarios DL y BLL (p<0.05). Se encontraron relaciones significativas positivas entre MDF con FiHi y IC con ICur y negativas entre MDF con IC, MDF con ICur, IC con FiHi, ICur con FiHi e ICur con CVDF. Los resultados indican que en esta zona del país existen alpacas con buen potencial en calidad de fibra