Contributors to the Fall Issue/Notes

Notes by Wilmer L. McLaughlin, John F. Mendoza, Patrick F. Coughlin, William J. O\u27Connor, Arthur L. Beaudette, Henry M. Shine, Jr., William M. Dickson, and William B. Wombacher

How frequently do clusters occur in hierarchical clustering analysis? A graph theoretical approach to studying ties in proximity

Background: Hierarchical cluster analysis (HCA) is a widely used classificatory technique in many areas of scientific knowledge. Applications usually yield a dendrogram from an HCA run over a given data set, using a grouping algorithm and a similarity measure. However, even when such parameters are fixed, ties in proximity (i.e. two equidistant clusters from a third one) may produce several different dendrograms, having different possible clustering patterns (different classifications). This situation is usually disregarded and conclusions are based on a single result, leading to questions concerning the permanence of clusters in all the resulting dendrograms; this happens, for example, when using HCA for grouping molecular descriptors to select that less similar ones in QSAR studies. Results: Representing dendrograms in graph theoretical terms allowed us to introduce four measures of cluster frequency in a canonical way, and use them to calculate cluster frequencies over the set of all possible dendrograms, taking all ties in proximity into account. A toy example of well separated clusters was used, as well as a set of 1666 molecular descriptors calculated for a group of molecules having hepatotoxic activity to show how our functions may be used for studying the effect of ties in HCA analysis. Such functions were not restricted to the tie case; the possibility of using them to derive cluster stability measurements on arbitrary sets of dendrograms having the same leaves is discussed, e.g. dendrograms from variations of HCA parameters. It was found that ties occurred frequently, some yielding tens of thousands of dendrograms, even for small data sets. Conclusions: Our approach was able to detect trends in clustering patterns by offering a simple way of measuring their frequency, which is often very low. This would imply, that inferences and models based on descriptor classifications (e.g. QSAR) are likely to be biased, thereby requiring an assessment of their reliability. Moreover, any classification of molecular descriptors is likely to be far from unique. Our results highlight the need for evaluating the effect of ties on clustering patterns before classification results can be used accurately. © 2016 Leal et al

The ABO\u27s of Blood Types

For high school age students the blood types can be a useful introduction to heredity. It has been shown, for example, that if both parents are type O, their children must all be type O: it is recessive to A and to B

Disrupción auriculoventricular posterior a reoperación de reemplazo valvular mitral: reparación y evaluación ecocardiográfica

ResumenLa disrupción auriculoventricular después del reemplazo valvular mitral es una rara pero letal complicación. Este caso es el de una mujer de 72 años de edad, con antecedentes de: reemplazo valvular aórtico, mitral, plastia tricúspide y Maze. Se llevó al reemplazo valvular mitral con prótesis Hancock 29 mitral. Se trasladó a la UCI y el curso postoperatorio fue normal hasta las 24 horas después de la cirugía, cuando presentó disnea y requirió soporte inotrópico. Se le realizó un angiotac y un ecocardiograma transtorácico que evidenció pseudoaneurisma ventricular. Fue llevada a cirugía, se inició circulación extracorpórea. Se evidenció disrupción auriculoventricular en el anillo posterior de la válvula mitral (tipo I perforación). La ruptura fue cerrada con un parche mixto de pericardio bovino y dacron con sutura continua. Actualmente, la paciente está en buenas condiciones sin recurrencia. Investigamos: el caso, la etiología, el reparo quirúrgico y la prevención de esta rara complicación y se discute.AbstractAtrioventricular disruption after a mitral valve replacement is a rare but fatal complication. A case of 72 year-old woman is presented. She had a medical history of aortic and mitral valve replacement and Maze and tricuspid valve surgery. Mitral valve replacement was performed with Hancock 29 mitral prosthesis. She was taken to ICU and postoperative progress was normal until 24hours after the surgery, when she developed dyspnea and required inotropic support. A CT angiography and transthoracic echocardiogram were performed, which evidence a ventricular pseudoaneurysm. She was taken to the operating room to start extracorporeal circulation. Atrioventricular disruption was evidenced in the posterior mitral annulus (type I perforation). Rupture was closed with a using a mixed Dacron and bovine pericardial patch with continuous suture. Patient is currently in good condition with no recurrence. Case, etiology, surgical repair and prevention of this rare complication were investigated and discussed

DETERMINANTS OF ENERGY CONSUMPTION: A REVIEW OF THE PHILIPPINE ENERGY SECTOR

Energy is considered a vital component of economic growth and human development. When its availability is disrupted, several economic sectors could not function fully to its extent. Energy consumption is influenced by several variables that affect it directly or indirectly. This study was conducted to evaluate the impact of GDP, industrialization, urbanization, trade openness, financial development, and FDI on the energy consumption of the Philippines; and to present the trend of each variable from 1971 to 2014. Data on energy consumption, GDP, industrialization, urbanization, trade openness, financial development, and FDI of the Philippines from 1971 to 2014 were sourced from the World Development Indicators published by the World Bank. The Ordinary Least Squares (OLS) regression analysis was used to analyze and identify those factors that significantly affect the energy consumption of the Philippines. Results indicated that GDP, industrialization, urbanization, and financial development significantly affect the energy consumption of the Philippines. These determinants have p-values that are lower than the 5% significance level. Thus, this study provides the policy and decision-makers with ample information for decisive decision-making in the Philippine energy sector.  Article visualizations

Clasificación por Capacidad de uso Mayor de las Tierras de la Comunidad Campesina de San Damián de Cascapara, Yungay, Ancash

- 1 -   Taking into account the great diversity of the physical environment, where family farming is developed, the study of land classification by greater Use Capacity of the agricultural lands of the San Damián Peasant Community was carried out in order to know the use (what crops can be conducted in the areas studied), the problems or limitations that these lands may have, and the most appropriate management practices that should be applied. The results showed that due to the ruggedness of the terrain, of the 300 hectares covered by the study, the largest areas correspond to land suitable for pasture (P) with 114 hectares, (38,28%), then there are lands suitable for permanent crops (C) 94,60 ha (31,53%), then there are the protection areas (X), with 55,66 ha (18,55%); then there are the lands suitable for forestry (F) with 19,21 hectares (6,40%) and finally there are the best lands, suitable for diversified agriculture (A) with 15,69 hectares, which represent only 5,23% of the total areas studied. Of course, the peasant producer uses the land according to his own criteria, but always maintaining biodiversity, rational management and a limited use of agrochemicals.Teniendo en cuenta la gran diversidad del entorno físico, en donde se desarrolla la agricultura familiar, se realizó el estudio de clasificación de tierras por Capacidad de Uso Mayor, de las tierras agrícolas de la Comunidad Campesina San Damián, con la finalidad de conocer el uso (que cultivos se pueden conducir en las áreas estudiadas), los problemas o limitaciones que pueden tener estas tierras, y las prácticas de manejo más apropiadas que se deben aplicar. Los resultados demostraron que debido a lo agreste del terreno, de las 300 has que abarcó el estudio, las mayores áreas corresponden a las tierras aptas para pastos (P) con114 has, (38,28%), luego están las tierras aptas para cultivos permanentes (C) 94,60 (31,53%), enseguida están las áreas de protección ( X), con 55,66 has (18,55%); enseguida están las tierras aptas para forestales ( F) con 19,21 has (6,40%) y por último se encuentran las mejores tierras, aptas para una agricultura diversificada (A) con 15,69 has, que representan solo el 5,23% del total de las áreas estudiadas. Desde luego, el productor campesino utiliza las tierras de acuerdo con su propio criterio, pero siempre manteniendo la biodiversidad, el manejo racional y un limitado uso de agroquímicos

Potencial antioxidante de residuos agroindustriales de tres frutas de alto consumo en el Tolima

Este trabajo evaluó las propiedades antioxidantes de los residuos agroindustriales de mora de castilla (Rubus glaucus), maracuyá (Passiflora edulis) y tomate de árbol (Cyphomandra betacea), tres frutas de alto consumo en el Tolima mediante la determinación de la capacidad antiradical (ABTS y DPPH), Capacidad Antioxidante Total Hidrosoluble, Poder Reductor Férrico y Actividad Antinitrosativa. Los resultados fueron contrastados con el contenido fenólico total y de pigmentos antociánicos de cada uno de los subproductos estudiados, mostrando a los residuos de R. glaucus como el material con mayor aporte de compuestos antioxidantes