Initiation Sequence of E‐Cigarette and Cigarette Smoking among US Adolescents: A National Study

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149688/1/ajad12886_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149688/2/ajad12886.pd

A Mathematical Framework for Agent Based Models of Complex Biological Networks

Agent-based modeling and simulation is a useful method to study biological phenomena in a wide range of fields, from molecular biology to ecology. Since there is currently no agreed-upon standard way to specify such models it is not always easy to use published models. Also, since model descriptions are not usually given in mathematical terms, it is difficult to bring mathematical analysis tools to bear, so that models are typically studied through simulation. In order to address this issue, Grimm et al. proposed a protocol for model specification, the so-called ODD protocol, which provides a standard way to describe models. This paper proposes an addition to the ODD protocol which allows the description of an agent-based model as a dynamical system, which provides access to computational and theoretical tools for its analysis. The mathematical framework is that of algebraic models, that is, time-discrete dynamical systems with algebraic structure. It is shown by way of several examples how this mathematical specification can help with model analysis.Comment: To appear in Bulletin of Mathematical Biolog

Dialysate Potassium and Mortality in a Prospective Hemodialysis Cohort.

BackgroundStudies examining the association of dialysate potassium concentration and mortality in hemodialysis patients show conflicting findings. We hypothesized that low dialysate potassium concentrations are associated with higher mortality, particularly in patients with high pre-dialysis serum potassium concentrations.MethodsWe evaluated 624 hemodialysis patients from the prospective Malnutrition, Diet, and Racial Disparities in Kidney Disease study recruited from 16 outpatient dialysis facilities over 2011-2015 who underwent protocolized collection of dialysis treatment characteristics every 6 months. We examined the association of dialysate potassium concentration, categorized as 1, 2, and 3 mEq/L, with all-cause mortality risk in the -overall cohort, and stratified by pre-dialysis serum potassium (< 5 vs. ≥5 mEq/L) using case-mix adjusted Cox models.ResultsIn baseline analyses, dialysate potassium concentrations of 1 mEq/L were associated with higher mortality, whereas concentrations of 3 mEq/L were associated with similar mortality in the overall cohort (reference: 2 mEq/L): adjusted hazard ratios (aHRs; 95% CI) 1.70 (1.01-2.88) and 0.95 (0.64-1.39), respectively. In analyses stratified by serum potassium, baseline dialysate potassium concentrations of 1 mEq/L were associated with higher mortality in patients with serum potassium ≥5 mEq/L but not in those with serum potassium < 5 mEq/L: aHRs (95% CI) 2.87 (1.51-5.46) and 0.74 (0.27-2.07), respectively (p interaction = 0.04). These findings were robust with incremental adjustment for serum potassium, potassium-binding resins, and potassium-modifying medications.ConclusionLow (1 mEq/L) dialysate potassium -concentrations were associated with higher mortality, particularly in hemodialysis patients with high pre-dialysis serum potassium. Further studies are needed to identify therapeutic strategies that mitigate inter-dialytic serum potassium accumulation and subsequent high dialysate serum potassium gradients in this population

Selección de Plantas Acuáticas y Sustratos para el Tratamiento de Efluentes de Predio Lecheros Utilizando Sistemas Wetland

El objetivo del presente estudio fue determinar la combinación “macrófita + sustrato” óptima para el tratamiento de efluentes de tambo, utilizando wetlands subsuperficiales de flujo horizontal (WSFH) a escala laboratorio. Se dispusieron en un invernadero 16 microcosmos simulando WSFHs con diferentes combinaciones de “macrófita + sustrato” por duplicado. Se evaluaron dos sustratos: leca y uno combinado, formado por grava y zeolita, y tres especies de macrófitas (Typha domingensis, Phragmites australis y Canna indica), utilizando efluente real de predio lechero con tratamiento previo. A fin de evaluar la eficiencia de los distintos tratamientos, se determinó: pH, conductividad, nitrógeno total Kjeldahl, amonio, nitrato, nitrito, fósforo total, sólidos suspendidos y demanda química de oxígeno (DQO) en el efluente inicial y final de cada tratamiento. Los WSFHs demostraron ser eficientes para tratar el efluente en estudio, determinándose que el sustrato óptimo fue la leca y las macrófitas más eficientes P. australis y T. domingensis

Non-homogenous disks in the chain of matrices

We investigate the generating functions of multi-colored discrete disks with non-homogenous boundary conditions in the context of the Hermitian multi-matrix model where the matrices are coupled in an open chain. We show that the study of the spectral curve of the matrix model allows one to solve a set of loop equations to get a recursive formula computing mixed trace correlation functions to leading order in the large matrix limit.Comment: 25 pages, 4 figure

Medical students learning styles in Latin American and Spanish universities: relation with geographical and curricular contexts

Objetivo. Determinar si los estilos de aprendizaje (EA) de los estudiantes de medicina se correlacionan con el contexto geográfico, con el contexto curricular o con el nivel de la carrera. Sujetos y métodos. El estudio se realizó en 490 estudiantes de las Escuelas de Medicina de las Universidades de Chile (Santiago, Chile), Nacional de Cuyo (Mendoza, Argentina), San Francisco Xavier (Sucre, Bolivia), Zaragoza y País Vasco (España). Se aplicó el cuestionario Honey-Alonso, que valora la preferencia por cada uno de cuatro EA: activo, reflexivo, teórico y pragmático. También se evaluó el EA de acuerdo al modelo de Kolb. Resultados. Al relacionar el EA con el contexto geográfico se observó que mientras los estudiantes de universidades españolas muestran un estilo preferentemente asimilador, siguiendo la denominación de Kolb, para Chile fue el acomodador y para Bolivia los estudiantes se distribuyen entre los estilos asimilador y divergente. Al comparar la distribución de los EA durante el tercer curso de medicina en dos facultades que poseen diferente currículo, no se observaron diferencias significativas. Los EA en una Facultad de Medicina con un currículo basado en asignaturas (Chile) no mostraron diferencias en los tres cursos del estudio (1.o, 3.o y 5.o), siendo preferentes los estilos reflexivo y teórico. Conclusiones. El estudio permitió establecer diferencias significativas entre los estilos de aprendizaje de los estudiantes de Medicina en relación con el contexto geográfico, más que con los diferentes currículos, o a lo largo de los distintos cursos de la carrera.Aim. To establish a correlation between medical student learning styles (LS) and the geographical context, the curricular context and different academic levels. Subjects and methods. The study was performed in 490 undergraduate students from Medical Schools of the Universities of Chile (Santiago, Chile), Nacional de Cuyo (Mendoza, Argentina), San Francisco Xavier (Sucre, Bolivia), Zaragoza and País Vasco (Spain). The instrument used was the Honey-Alonso learning style questionnaire that assesses the student preference for one of four LS: active, reflexive, theoretic and pragmatic. In addition, LS according to the Kolb inventory were also assessed. Results. Using the Kolb inventory, significant differences were found when the LS were correlated with the geographical context. While Spanish students showed a high preference for the assimilator style of learning, Chilean students resulted to be mainly accommodators, and Bolivian students were both assimilators and divergent. Comparing the LS distribution during the third course in two universities with different curricula (problem and lecture based learning), there were no significant differences. LS of medical students from a Medical School with a lecture based curriculum (University of Chile) were not significantly different during the first, the third and the fifth level of their undergraduate students. They showed a significant preference for reflexive and theoretic styles of learning. Conclusions. The present study allowed demonstrating that significant differences among the styles of learning of medical students correlated with the geographical context more than with the different curricula, or along the different courses of the career.Fil: Diaz Veliz, G.. Universidad de Chile; ChileFil: Mora, S.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; ArgentinaFil: Lafuente Sanchez, J. V.. Universidad del País Vasco; EspañaFil: Gargiulo, Pascual Angel. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Bianchi, R.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; ArgentinaFil: Teran, C.. Universidad Andina Simón Bolívar; BoliviaFil: Gorena, D.. Universidad Andina Simón Bolívar; BoliviaFil: Arce, J.. Universidad San Francisco Xavier; BoliviaFil: Escanero Marcen, J. F.. Universidad de Zaragoza; Españ

Promoción de salud bucal en alumnos y trabajadores administrativos y de servicio de la Facultad de Medicina de la Universidad Nacional Mayor de San Marcos

The promotion of the health is a process that give to the people the instruments to lead a better control for the health care. In this process participing the patients, the family, the community, the heath services and the autority`s health. There is a little information about the promotion of the dental health at the San Marcos University. The results show that thre is not an effective program of dental diseases prevention whitin the students and workers of the Faculty of Medicine at San Marcos University.La promoción de la salud es el proceso que proporciona la proporción, los elementos para ejercer un mayor control sobre su propia salud y mejorarla. En este proceso intervienen los individuos, familias, comunidades, servicio de salud y autoridades sanitarias. Existe escasa información sobre la promoción de la salud bucal en la U.N.M.S.M. Los resultados señalan la falta de cultura sobre la salud bucal y sus medios de prevención en los estudiantes y trabajadores no docentes de la Facultad de Medicina de la U.N.M.S.M

Boolean dynamics revisited through feedback interconnections

Boolean models of physical or biological systems describe the global dynamics of the system and their attractors typically represent asymptotic behaviors. In the case of large networks composed of several modules, it may be difficult to identify all the attractors. To explore Boolean dynamics from a novel viewpoint, we will analyse the dynamics emerging from the composition of two known Boolean modules. The state transition graphs and attractors for each of the modules can be combined to construct a new asymptotic graph which will (1) provide a reliable method for attractor computation with partial information; (2) illustrate the differences in dynamical behavior induced by the updating strategy (asynchronous, synchronous, or mixed); and (3) show the inherited organization/structure of the original network’s state transition graph.publishe

Species-speciWc defense strategies of vegetative versus reproductive blades of the PaciWc kelps Lessonia nigrescens and Macrocystis integrifolia

Chemical defense is assumed to be costly and therefore algae should allocate defense investments in a way to reduce costs and optimize their overall fitness. Thus, lifetime expectation of particular tissues and their contribution to the fitness of the alga may affect defense allocation. Two brown algae common to the SE Pacific coasts, Lessonia nigrescens Bory and Macrocystis integrifolia Bory, feature important ontogenetic differences in the development of reproductive structures; in L. nigrescens blade tissues pass from a vegetative stage to a reproductive stage, while in M. integrifolia reproductive and vegetative functions are spatially separated on different blades. We hypothesized that vegetative blades of L. nigrescens with important future functions are more (or equally) defended than reproductive blades, whereas in M. integrifolia defense should be mainly allocated to reproductive blades (sporophylls), which are considered to make a higher contribution to fitness. Herein, within-plant variation in susceptibility of reproductive and vegetative tissues to herbivory and in allocation of phlorotannins (phenolics) and N-compounds was compared. The results show that phlorotannin and N-concentrations were higher in reproductive blade tissues for both investigated algae. However, preferences by amphipod grazers (Parhyalella penai) for either tissue type differed between the two algal species. Fresh reproductive tissue of L. nigrescens was more consumed than vegetative tissue, while the reverse was found in M. integrifolia, thus confirming the original hypothesis. This suggests that future fitness function might indeed be a useful predictor of anti-herbivore defense in large, perennial kelps. Results from feeding assays with artificial pellets that were made with air-dried material and extract-treated Ulva powder indicated that defenses in live algae are probably not based on chemicals that can be extracted or remain intact after air-drying and grinding up algal tissues. Instead, anti-herbivore defense against amphipod mesograzers seems to depend on structural traits of living algae

Shape recognition through multi-level fusion of features and classifiers

Shape recognition is a fundamental problem and a special type of image classification, where each shape is considered as a class. Current approaches to shape recognition mainly focus on designing low-level shape descriptors, and classify them using some machine learning approaches. In order to achieve effective learning of shape features, it is essential to ensure that a comprehensive set of high quality features can be extracted from the original shape data. Thus we have been motivated to develop methods of fusion of features and classifiers for advancing the classification performance. In this paper, we propose a multi-level framework for fusion of features and classifiers in the setting of gran-ular computing. The proposed framework involves creation of diversity among classifiers, through adopting feature selection and fusion to create diverse feature sets and to train diverse classifiers using different learn-Xinming Wang algorithms. The experimental results show that the proposed multi-level framework can effectively create diversity among classifiers leading to considerable advances in the classification performance