631 research outputs found
The early life history transitions of the bivalve aulacomya atra from the humboldt current system off peru are affected by human exploitation and modulated by El niño-la niña cycle
Understanding the factors and mechanisms that control temporal changes of larval settlement and subsequent recruitment of marine bivalves have strong implications for the management of exploited populations of coastal species and the conservation of benthic communities. Therefore, assessing both organismal and environmental drivers of the reproductive function, gamete release and recruitment is important. This is particularly true for highly productive upwelling coastal areas that are heavily affected by shifts in climatic regimes during the El Niño (EN)-La Niña (LN) cycle. We aimed to assess temporal variation in the transition between gamete release, larval settlement and subsequent recruitment of the commercially- important ribbed mussel (Aulacomya atra) at Bahía Independencia (Peru) over 9 years (1996-2004) - a period that covered strong EN and LN episodes. We also evaluate the environmental factors implied in these changes. To achieve this, we monitored monthly changes of the spawning stock biomass (SSB; a proxy of the capacity for propagule production and release), the number of settled postlarvae on artificial collectors, the density of recruits of A. atra and several environmental parameters. Our results showed a persistent trend of decreasing SSB and recruitment density, most likely related to human exploitation that reduced the population density by one order of magnitude. The SSB was a significant predictor of the number of settled postlarvae, regardless of the occurrence of EN or LN episodes. In contrast, the relationship between SSB and the density of recruits was dependent on the occurrence of EN or LN. The SSB and the larval settlement were heavily reduced during the warm EN in 1997-1998, presumably as a typical response of species of Antarctic origin to warmer-nutrient depleted waters and disturbed circulation patterns within the bay that may favor offshore transport of larvae. Despite this, the density of recruits of A. atra was high during EN, presumably as a result of reduced competition for food and reduced predation, which may overcompensate for the mortality of recruits associated with thermal stress
Data Cleansing Meets Feature Selection: A Supervised Machine Learning Approach
This paper presents a novel procedure to apply in a sequential
way two data preparation techniques from a different nature such as
data cleansing and feature selection. For the former we have experienced
with a partial removal of outliers via inter-quartile range whereas for
the latter we have chosen relevant attributes with two widespread feature
subset selectors like CFS (Correlation-based Feature Selection) and
CNS (Consistency-based Feature Selection), which are founded on correlation
and consistency measures, respectively. Empirical results on seven
difficult binary and multi-class data sets, that is, with a test error rate of
at least a 10%, according to accuracy, with C4.5 or 1-nearest neighbour
classifiers without any kind of prior data pre-processing are outlined.
Non-parametric statistical tests assert that the meeting of the aforementioned
two data preparation strategies using a correlation measure for
feature selection with C4.5 algorithm is significant better, measured with
roc measure, than the single application of the data cleansing approach.
Last but not least, a weak and not very powerful learner like PART
achieved promising results with the new proposal based on a consistency
measure and is able to compete with the best configuration of C4.5. To
sum up, bearing in mind the new approach, for roc measure PART classifier
with a consistency metric behaves slightly better than C4.5 and a
correlation measureMICYT TIN2007-68084-C02- 02MICYT TIN2011-28956-C02-02Junta de Andalucía P11-TIC-752
Deleting or Keeping Outliers for Classifier Training?
This paper introduces two statistical outlier
detection approaches by classes. Experiments on binary and
multi-class classification problems reveal that the partial
removal of outliers improves significantly one or two
performance measures for C4.S and I-nearest neighbour
classifiers. Also, a taxonomy of problems according to the
amount of outliers is proposed.MICYT TIN2007- 68084-C02-02MICYT TIN2011-28956-C02-02Junta de Andalucía Pll-TIC-752
Tackling Ant Colony Optimization Meta-Heuristic as Search Method in Feature Subset Selection Based on Correlation or Consistency Measures
This paper introduces the use of an ant colony optimization
(ACO) algorithm, called Ant System, as a search method in two wellknown
feature subset selection methods based on correlation or consistency
measures such as CFS (Correlation-based Feature Selection) and
CNS (Consistency-based Feature Selection). ACO guides the search using
a heuristic evaluator. Empirical results on twelve real-world classification
problems are reported. Statistical tests have revealed that InfoGain is a
very suitable heuristic for CFS or CNS feature subset selection methods
with ACO acting as search method. The use of InfoGain is shown to be
the significantly better heuristic over a range of classifiers. The results
achieved by means of ACO-based feature subset selection with the suitable
heuristic evaluator are better for most of the problems comparing
with those obtained with CFS or CNS combined with Best First search.MICYT TIN2007-68084- C02-02MICYT TIN2011-28956-C02-02Junta de Andalucía P11-TIC-752
Contested environmental futures: rankings, forecasts and indicators as sociotechnical endeavours
In a world where numbers and science are often taken as the voice of truth and reason, Quantitative Devices (QDs) represent the epitome of policy driven by facts rather than hunches. Despite the scholarly interest in understanding the role of quantification in policy, the actual production of rankings, forecasts, indexes and other QDs has, to a great extent, been left unattended. While appendixes and technical notebooks offer an explanation of how these devices are produced, they exclude aspects of their making that are arbitrarily considered "mundane." It is in the everyday performances at research centres that the micropolitics of knowledge production, imaginaries, and frustrations merge. These are vital dimensions to understand the potential, limitations and ethical consequences of QDs.
Using two participant observations as the starting point, this thesis offers a comprehensive critical analysis of the processes through which university-based research centres create QDs that represent the world. It addresses how researchers conceive quantitative data. It pays attention to the discourses of hope and expectation embedded in the devices. Finally, it considers the ethics of creating devices that cannot be replicated independently of their place of production.
Two QDs were analysed: the Violence Early Warning System (ViEWS) and the Environmental Performance Index (EPI). At Uppsala University, researchers created ViEWS to forecast the probability of drought-driven conflicts within the next 100 years. The EPI, produced at the Yale Centre for Environmental Law and Policy, ranks the performance of countries' environmental policies. This thesis challenges existing claims within Science and Technology Studies and the Sociology of Quantification that QDs co-produce knowledge within their realms. I argue that these devices act as vehicles for sociotechnical infrastructures to be consolidated with little debate among policymakers, given their understanding as scientific and objective tools. Moreover, for an indicator to be incorporated within a QD, it needs to be deemed as relevant for those making the devices but also valuable enough to have been previously quantified by data providers. Even more, existing sociotechnical inequalities, power relations and epistemic injustices could impede disadvantaged communities' (e.g., in the Global South) ability to challenge metrics originated in centres in the Global North. This thesis, therefore, demonstrates how the future QDs propose is unilateral and does not acknowledge the myriad possibilities that might arise from a diversity of worldviews. In other words, they cast a future designed to fit under the current status quo.
In sum, through two QDs focused on environmental-related, this thesis launches an inquiry into the elements that make up the imaginaries they propose following the everyday life of their producers. To achieve this, I discuss two core elements. First, the role of tacit knowledge and sociotechnical inequalities in reinforcing power relations between those with the means to quantify and those who might only accommodate proposed futures. Second, the dynamics between research centres and data providers in relation to what is quantified. By scrutinising mundanity, this work is a step forward in understanding the construction of sociotechnical imaginaries and infrastructures
Mérida, clave en la fundación de la Orden de Santiago
En este articulo se expone qué la razón por la cual la Orden de los Fratres de Caceras se transformó en la Orden Militar de Santiago, a instancias del obispo de Compostela, radicó en que, a cambio de unos beneficios que éste concedió a Pedro Fernández, el maestre de los cacereños, la nueva Orden, en su avance reconquistador hacia el Sur, no debería reclamar la restauración de la sede arzobispal de Mérida, trasladada interinamente a Santiago mientras su sede emeritense estuviera ocupada por los musulmanes.In this article we are golng to expose that the reason for which the Order of the Fratres of Cáceres was transformed into the Military Order of Santiago at the request of the bishop of Compostela was possible because in exchange for some benefits that he gave Pedro fernández, the Knight of the cecereños, the new Orden in its reconquest advance to the South, shouldn't reclaim the retornatlon of the archiepiscopal see of Mérida, moved temporally to Santiago while it was occupied by the Moslem
A developmental model for the pathogenenesis of cardiac arterio-ventricular fistulae
Coronary Artery Fistulae (CAF) are congenital coronary artery (CA) anomalies consisting of an abnormal communication of a coronary artery with either a cardiac chamber or a large cardiac vessel. Although their incidence in the Western population is low, CAF can lead to complications such as myocardial hypertrophy, endocarditis, heart dilatation and cardiac failure. CAFs can appear as an isolated anomaly or linked to some other forms of congenital heart disease like Left Ventricular Non-Compaction (LVNC) and intrinsic CA anatomy anomalies, but their etiology remains unknown. In this work we have used two different experimental models (transgenic mice and avian embryos) to investigate on the developmental mechanics of CAF formation. In order to tackle this goal, we have manipulated epicardial development and ventricular wall compaction, two inextricably related developmental events during coronary embryogenesis. Conditional integrin α4 gene deletion in the septum transversum/proepicardial (ST/PE) region (G2-Gata4+) disrupts early epicardium development and reduces cardiomyocyte proliferation, leading to the thinning of the ventricular compact myocardial layer. Reduction in compact myocardium thickness associates to the presence of multiple ventricular myocardial discontinuities and focal endocardial extrusion. This same phenotype can be experimentally reproduced in chick embryos using a cryocauterization method (Palmquist-Gomes et al., 2016). Our results suggest that the partial absence of epicardium in α4integrin;G2-Gata4Cre mouse embryos and the cryoinjury in avian embryos generate myocardial discontinuities in the embryonic ventricular wall, which promote endocardial extrusion towards the pericardial cavity and the early contact of the endocardium with coronary progenitors at the epicardial surface of the heart. In the case of avian embryos, this phenomenon leads to precocious smooth muscle differentiation from epicardial mesenchymal cells, and the formation of pouch-like structures that closely resemble CAF. We conclude that anomalous compact myocardial embryonic growth can originate CAF.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
A developmental model for the pathogenenesis of cardiac arterio-ventricular fistulae
Coronary Artery Fistulae (CAF) are congenital coronary artery (CA) anomalies consisting of an abnormal communication of a coronary artery with either a cardiac chamber or a large cardiac vessel. Although their incidence in the Western population is low, CAF can lead to complications such as myocardial hypertrophy, endocarditis, heart dilatation and cardiac failure. CAFs can appear as an isolated anomaly or linked to some other forms of congenital heart disease like Left Ventricular Non-Compaction (LVNC) and intrinsic CA anatomy anomalies, but their etiology remains unknown. In this work we have used two different experimental models (transgenic mice and avian embryos) to investigate on the developmental mechanics of CAF formation. In order to tackle this goal, we have manipulated epicardial development and ventricular wall compaction, two inextricably related developmental events during coronary embryogenesis. Conditional integrin α4 gene deletion in the septum transversum/proepicardial (ST/PE) region (G2-Gata4+) disrupts early epicardium development and reduces cardiomyocyte proliferation, leading to the thinning of the ventricular compact myocardial layer. Reduction in compact myocardium thickness associates to the presence of multiple ventricular myocardial discontinuities and focal endocardial extrusion. This same phenotype can be experimentally reproduced in chick embryos using a cryocauterization method (Palmquist-Gomes et al., 2016). Our results suggest that the partial absence of epicardium in α4integrin;G2-Gata4Cre mouse embryos and the cryoinjury in avian embryos generate myocardial discontinuities in the embryonic ventricular wall, which promote endocardial extrusion towards the pericardial cavity and the early contact of the endocardium with coronary progenitors at the epicardial surface of the heart. In the case of avian embryos, this phenomenon leads to precocious smooth muscle differentiation from epicardial mesenchymal cells, and the formation of pouch-like structures that closely resemble CAF. We conclude that anomalous compact myocardial embryonic growth can originate CAF.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
TALFi: una herramienta para teoría de autómatas y lenguajes formales
TALFi es una aplicación cuyo objetivo es ser una herramienta para el aprendizaje y el uso de diversos algoritmos aplicados al tratamiento de autómatas. Con TALFi podemos crear autómatas y ver sus transformaciones en otros autómatas, gracias a los diferentes algoritmos que se pueden aplicar sobre ellos. Es una herramienta de fácil uso, capaz de ser usada en un terminal o bajo una interfaz gráfica. La aplicación se puede ejecutar bajo previa instalación en un equipo o vía internet. TALFi dispone de una base de datos con diversos ejemplos de autómatas, la cual puede ser ampliada por el usuario con nuevos autómatas creados por él mismo. Además la aplicación posee una base de datos con ejercicios que también puede ser extendida, pero en este caso sólo por el administrador. La aplicación está pensada para ser una herramienta de ayuda para los estudiantes que cursen asignaturas donde se traten temas de lenguajes formales y autómatas.
[ABSTRACT]
TALFi is an application whose goal is to be a tool for learning and using various algorithms dealing with automata. With TALFi you can create automata and view the automata transformations into other automata by using the different algorithms that can be applied to them. The program is easy to use and it can be used in a shell or a graphical interface. The application can be used online through the Internet or it can be installed in any computer to be used offline. TALFi has a database with examples of automata. These examples can be extended by the user with new automata created by himself. The application also has a database with exercises that can be extended by an administrator. The application is designed to be used by students learning Subjects about formal languages and automata
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