Significant Subgraph Mining with Multiple Testing Correction

The problem of finding itemsets that are statistically significantly enriched in a class of transactions is complicated by the need to correct for multiple hypothesis testing. Pruning untestable hypotheses was recently proposed as a strategy for this task of significant itemset mining. It was shown to lead to greater statistical power, the discovery of more truly significant itemsets, than the standard Bonferroni correction on real-world datasets. An open question, however, is whether this strategy of excluding untestable hypotheses also leads to greater statistical power in subgraph mining, in which the number of hypotheses is much larger than in itemset mining. Here we answer this question by an empirical investigation on eight popular graph benchmark datasets. We propose a new efficient search strategy, which always returns the same solution as the state-of-the-art approach and is approximately two orders of magnitude faster. Moreover, we exploit the dependence between subgraphs by considering the effective number of tests and thereby further increase the statistical power.Comment: 18 pages, 5 figure, accepted to the 2015 SIAM International Conference on Data Mining (SDM15

Sobre la posible existencia de indicadores polínicos en mieles argentinas de importación

Se estudia el espectro pol i nice de doce muestras de miel importada de Argentina. Los pr incipal es taxones en ellas representados son los siguientes: Eucal yptus, Helianthus , Echium, Fabaceae , Umbeliferae y Carduus. En al gunas muestras se detecta l a presencia de granos de polen pertenecientes a ciertas Onograceae y Polygonaceae que pueden ser útiles para di stinguir estas mieles de las de origen españolThe pollen spectrum of twelve samples of honey f r om Argentina were studied . The m a in taxa present were found to be : Eucalypt us, Helianthus 1 Echi um 1 Fabaceae 1 Umbellif erae y Carduus o In some samples the presence of pol l en grains belonging to certain Onograceae and Polygonaceae were encountered and t hese taxa are considered to be useful cr i teria to distinguish this han e y from that of Spanish ori gin

Different moments in the participatory stage of the secondary students’ abstraction of mathematical conceptions

This study provides support to the characteristics of participatory and anticipatory stages in secondary school pupils’ abstraction of mathematical conceptions. We carried out clinical task-based interviews with 71 secondary-school pupils to obtain evidence of the different constructed mathematical conceptions (Participatory Stage) and how they were used (Anticipatory Stage). We distinguish two moments in the Participatory Stage based on the coordination of information from particular cases by activity-effect reflection which, in some cases, lead to a change of focus enabling secondary-school pupils to achieve a reorganization of their knowledge. We argue that (a) the capacity of perceiving regularities in sets of particular cases is a characteristic of activity-effect reflection in the abstraction of mathematical conceptions in secondary school, and (b) the coordination of information by pupils provides opportunities for changing the attention-focus from the particular results to the structure of properties

Stress-tolerant Wild Plants: a Source of Knowledge and Biotechnological Tools for the Genetic Improvement of Stress Tolerance in Crop Plants

Over the next few decades we must boost crop productivity if we are to feed a growing world population, which will reach more than 9×109 people by 2050; and we should do it in the frame of a sustainable agriculture, with an increasing scarcity of new arable land and of water for irrigation. For all important crops, average yields are only a fraction-somewhere between 20% and 50%-of record yields; these losses are mostly due to drought and high soil salinity, environmental conditions which will worsen in many regions because of global climate change. Therefore, the simplest way to increase agricultural productivity would be to improve the abiotic stress tolerance of crops. Considering the limitations of traditional plant breeding, the most promising strategy to achieve this goal will rely on the generation of transgenic plants expressing genes conferring tolerance. However, advances using this approach have been slow, since it requires a deep understanding of the mechanisms of plant stress tolerance, which are still largely unknown. Paradoxically, most studies on the responses of plants to abiotic stress have been performed using stress-sensitive species-such as Arabidopsis thaliana-although there are plants (halophytes, gypsophytes, xerophytes) adapted to extremely harsh environmental conditions in their natural habitats. We propose these wild stress-tolerant species as more suitable models to investigate these mechanisms, as well as a possible source of biotechnological tools (‘stress tolerance’ genes, stress-inducible promoters) for the genetic engineering of stress tolerance in crop plants

A fixed point theorem without convexity

The purpose of this paper is to extend Himmelberg's fixed point theorem replacing the usual convexity in topological vector spaces by an abstract topological notion of convexity which generalizes classical convexity as well as several metric convexity structures found in the literature. We prove the existence, under weak hypotheses, of a fixed point for a compact approachable map and we provide sufficient conditions under which this result applies to maps whose values are convex in the abstract sense mentionned above

Construcción del concepto múltiplo común en el dominio de los números naturales

El objetivo de esta investigación fue caracterizar el proceso de construcción del concepto de múltiplo común de dos números naturales como parte del esquema de divisibilidad en estudiantes de educación secundaria. A partir de un análisis cualitativo de entrevistas clínicas en las que los estudiantes resolvían y justificaban su proceso de resolución de un problema, identificamos dos momentos cognitivos en el proceso constructivo del concepto de múltiplo común generado durante la resolución del problema. Estos momentos fueron caracterizados teniendo en cuenta cómo los estudiantes generaban casos particulares y coordinaban o no la información procedente de éstos. Esta caracterización proporciona información sobre cómo los estudiantes empiezan a concebir que un número pueda adoptar diferentes papeles en las relaciones multiplicativas del esquema de divisibilidad como parte constituyente del aprendizaje de los números.The purpose of this research was to characterize the construction process of common multiple of two whole numbers as a part of divisibility scheme in Secondary School students. From the analysis of clinical interviews with Secondary School students when solving a word-problem and justifying their decisions, we identify two cognitive moments in the constructive process generated in some cases in the context of problem solving. These cognitive moments were characterized regarding how students generated particular cases and were or were not able to coordinate the information arising from them. The characterization provides us with information about the way in which students begin to conceive that a number can play different roles in the divisibility scheme

Polychromy of late gothic civil architecture: a world heritage monument case in Spain

[EN] The Silk Exchange of Valencia, Spain, is one of the best examples of late Gothic civil architecture in Europe, and was declared a World Heritage Monument by UNESCO in 1996. Prior to cleaning and conservation, technical examination identified the original pigments used to paint the walls, keys, vaults, arches and columns in the main hall, the Contract Hall. Cross sections of remnants of original colour (blue, green, red, gold, etc.) were investigated with optical microscopy, scanning electron microscopy with energy dispersive X-ray analysis, X-ray diffraction techniques and UV light. The study has revealed that the original paint today remains only in very limited areas. Evidence for a later maintenance operation of repainting was also found in the inscription that runs around the Contract Hall. The information has been very useful for deciding on the cleaning and conservation process.This work has been supported by Universidad Politécnica de Valencia’s Forum Unesco -University and Heritage and by Valencia City Council under the project: “Study and Diagnosis of Pathological Manifestations of the Stone and Project and Construction Management of Cleaning and Conservation of the Silk Exchange of Valencia "Ramirez, MJ.; Saiz Mauleón, MB.; Curiel-Esparza, J.; Llinares, J.; Soriano, M. (2013). Polychromy of late gothic civil architecture: a world heritage monument case in Spain. Mediterranean Archaeology and Archaeometry. 13(2):121-126. http://hdl.handle.net/10251/99866S12112613