A random forest system combination approach for error detection in digital dictionaries

When digitizing a print bilingual dictionary, whether via optical character recognition or manual entry, it is inevitable that errors are introduced into the electronic version that is created. We investigate automating the process of detecting errors in an XML representation of a digitized print dictionary using a hybrid approach that combines rule-based, feature-based, and language model-based methods. We investigate combining methods and show that using random forests is a promising approach. We find that in isolation, unsupervised methods rival the performance of supervised methods. Random forests typically require training data so we investigate how we can apply random forests to combine individual base methods that are themselves unsupervised without requiring large amounts of training data. Experiments reveal empirically that a relatively small amount of data is sufficient and can potentially be further reduced through specific selection criteria.Comment: 9 pages, 7 figures, 10 tables; appeared in Proceedings of the Workshop on Innovative Hybrid Approaches to the Processing of Textual Data, April 201

Reannihilation of self-interacting dark matter

We explore the phenomenology of having a second epoch of dark matter annihilation into dark radiation long after the standard thermal freeze-out. Such a hidden reannihilation process could affect visible sectors only gravitationally. As a concrete realization we consider self-interacting dark matter (SIDM) with a light force mediator coupled to dark radiation. We demonstrate how resonantly Sommerfeld enhanced cross sections emerge to induce the reannihilation epoch. The effect is a temporally local modification of the Hubble expansion rate and we show that the Cosmic Microwave Background (CMB) measurements -- as well as other observations -- have a high sensitivity to observe this phenomenon. Special attention is given to the model region where late kinetic decoupling and strong self-interactions can alleviate several small-scale problems in the cold dark matter paradigm at the same time. Interestingly, we find that reannihilation might here also simultaneously lower the tension between CMB and low-redshift astronomical observations of $H_{0}$ and $\sigma_{8}$. Moreover, we identify reannihilation as a clear signature to discriminate between the phenomenologically otherwise almost identical vector and scalar mediator realizations of SIDM.Comment: Version submitted to journal. Extended with improved estimates and updated plots. 25 pages, 9 figures and 2 table

Uso y cobertura del suelo en las islas macaronésicas de Portugal y España: nuevos métodos para cuantificar y visualizar información de patrones espaciales

Tesis de la Universidad Complutense de Madrid, Facultad de Geografía e Historia, Departamento de Geografía Humana, leída el 23/11/2016The aim of this research is to propose novel methods for quantifying and visualizing geographical information, in order to aid the spatial planning decision-making process when addressing land use and land cover patterns. In doing so, several modeling and geographic visualization methods are developed and demonstrated by using the Macaronesian islands of Portugal and Spain as study areas. Macaronesia is a biogeographical region consisting of several archipelagos in the Atlantic Ocean belonging to three countries: Portugal, Spain, and Cape Verde. This research encompasses three archipelagos: the Azores, Madeira, and the Canary Islands. From these three archipelagos, the four most densely populated islands were further selected for the land use and land cover assessments: São Miguel, Madeira, Tenerife, and Gran Canaria. A common feature of the Macaronesian islands is that, ever since European colonization in the fifteenth century, up until the mid-twentieth century, anthropogenic land change was predominately attributable to agricultural activities consuming forests and natural areas. In the mid-twentieth century, owing to profound social and economic changes, the tertiary sector started its rise in becoming the main economic sector. Because the secondary sector in this region has always been minor, this substantial shift to the tertiary sector would dictate a progressive abandonment of the primary sector. Hence, agricultural areas started to recede. As a result, the last decades of the twentieth century were marked by a significant shift in land use dynamics. Agricultural activities ceased to be the main driving force of land change and were replaced by a rampant increase of the artificial surfaces, mainly on the southern coastal areas, where tourism-related and real estate pressure constitute a major impact on the landscape. A direct consequence of this pressure was the drastic transformation across the islands’ leeward coastal landscapes...El objetivo principal de esta investigación es proponer nuevos métodos para cuantificar y visualizar información geográfica, con el fin de facilitar el proceso de toma de decisiones en relación a los patrones de uso y ocupación del suelo. De este modo, se desarrollan y aplican varios métodos de modelación y visualización geográfica, utilizando las islas macaronésicas de Portugal y España como áreas de estudio. La Macaronesia es una región biogeográfica que integra varios archipiélagos en el Océano Atlántico pertenecientes a tres países: Portugal, España y Cabo Verde. Esta investigación abarca tres archipiélagos: Azores, Madeira y Canarias. Para una evaluación detallada de uso y cobertura del suelo se seleccionaron las cuatro islas más densamente pobladas: San Miguel, Madeira, Tenerife y Gran Canaria. Una característica común a las islas macaronésicas es que, desde de la colonización en el siglo XV hasta mediados del siglo XX, el cambio antropogénico del suelo se debió principalmente a las actividades agrícolas, que ocuparon bosques y áreas naturales. A mediados del siglo XX, debido a profundos cambios sociales y económicos, el sector terciario empezó su ascenso para convertirse en el principal sector económico. Debido a que el sector secundario en esta región siempre ha tenido una importancia menor, este proceso de terciarización de la economía supuso un progresivo abandono del sector primario. Por lo tanto, las áreas agrícolas comenzaron a experimentar un claro retroceso. Como resultado de este proceso, las últimas décadas del siglo XX se caracterizaron por un cambio significativo en las dinámicas de uso y cobertura del suelo. Las actividades agrícolas dejaron de ser la principal fuerza impulsora en el cambio de lo suelo y fueron reemplazadas por el aumento desenfrenado de las superficies artificiales, principalmente en las zonas costeras del sur, donde el turismo y la especulación inmobiliaria ejercen una gran presión sobre el paisaje. Consecuencia directa de esta presión fueron las drásticas transformaciones de los paisajes costeros de las islas...Esta investigação tem como principal objectivo propor novos métodos para quantificar e visualizar informação geográfica, de modo a auxiliar o processo de tomada de decisão quando seja necessário analisar padrões de uso e ocupação do solo. Ao longo da investigação são apresentados vários métodos de modelação e visualização geográfica, usando como área de estudo as ilhas da Macaronésia pertencentes a Portugal e Espanha. A Macaronésia é uma região biogeográfica no Oceano Atlântico constituída por vários arquipélagos pertencentes a três países: Portugal, Espanha e Cabo Verde. Este trabalho de investigação abrange três arquipélagos: os Açores, a Madeira e as Ilhas Canárias. Para uma avaliação mais detalhada quanto ao uso e ocupação do solo, foram seleccionadas as quatro ilhas mais densamente povoadas: São Miguel, Madeira, Gran Canaria e Tenerife. Uma característica comum às ilhas da Macaronésia reside na particularidade de, desde a sua colonização no século XV, até meados do século XX, as alterações antropogénicas do solo terem estado predominantemente associadas às actividades agrícolas que consumiram extensas áreas de floresta e espaços naturais. Em meados do século XX, devido a profundas alterações sociais e económicas, o sector terciário iniciou a sua ascensão para se tornar o principal sector económico. Uma vez que, nesta região, o sector secundário foi sempre pouco significativo, a terciarização da actividade económica ditou um progressivo abandono do sector primário. Deste modo, as áreas agrícolas começaram a recuar. Como resultado deste processo, as últimas décadas do século XX foram marcadas por uma mudança significativa na dinâmica de uso e ocupação do solo nas ilhas desta região. As actividades agrícolas deixaram de ser a principal força motriz para as alterações no uso do solo, sendo substituídas pelo aumento galopante das superfícies artificiais, principalmente nas áreas costeiras do sul, onde as actividades relacionadas com o turismo e a especulação imobiliária causaram um grande impacto na paisagem, e contribuiram para a transformação drástica do litoral sotavento das ilhas...Depto. de GeografíaFac. de Geografía e HistoriaTRUEunpu

Expansion properties of Double Standard Maps

For the family of Double Standard Maps $f_{a,b}=2x+a+\frac{b}{\pi} \sin2\pi x \quad\pmod{1}$ we investigate the structure of the space of parameters $a$ when $b=1$ and when $b\in[0,1)$. In the first case the maps have a critical point, but for a set of parameters $E_1$ of positive Lebesgue measure there is an invariant absolutely continuous measure for $f_{a,1}$. In the second case there is an open nonempty set $E_b$ of parameters for which the map $f_{a,b}$ is expanding. We show that as $b\nearrow 1$, the set $E_b$ accumulates on many points of $E_1$ in a regular way from the measure point of view

Imitation Learning Datasets: A Toolkit For Creating Datasets, Training Agents and Benchmarking

Imitation learning field requires expert data to train agents in a task. Most often, this learning approach suffers from the absence of avail- able data, which results in techniques being tested on its dataset. Creating datasets is a cumbersome process requiring researchers to train expert agents from scratch, record their interactions and test each benchmark method with newly created data. Moreover, creating new datasets for each new technique results in a lack of consistency in the evaluation process since each dataset can drastically vary in state and action distribution. In response, this work aims to address these issues by creating Imitation Learning Datasets, a toolkit that allows for: (i) curated expert policies with multithreaded support for faster dataset creation; (ii) readily available datasets and techniques with precise measurements; and (iii) sharing implementations of common imitation learning techniques

Urban form analysis employing land cover and spatial metrics: the case of the Lisbon Metropolitan Area

In order to face the challenges of urban planning, there is an increasing need to monitor and quantify urban occupation. This study, conducted within the research project "FURBS: Sustainable Urban Form - Methodological development for Portugal (PTDC/GEO/69109/2006), seeks to examine the urban form of the Lisbon Metropolitan Area (LMA), and its occupation between 1990 and 2000, using spatial metrics. The LMA congregates nearly 3 million inhabitants, around 26% of the Portuguese total population. A relevant characteristic of the region is that it has been subject to a constant opening of new areas of urbanization, which had caused in this region, an increase of 18.6% of housing units between 1991 and 2001, while the total population grew only 4.3%. In this study, we sought to apply the use of spatial metrics to CORINE Land Cover urban classes, analysing the evolution of urban area with a wide range of spatial metrics in order to quantify the urban evolution in the region. Spatial metrics have been used in ecology studies where they are known as landscape metrics. These metrics represent the geometric characteristics of the landscape units and the spatial relationships between them. Only recently these metrics started to be used to analyse and classify the urban form in a more systematic way. The applications of quantitative indicators are one of the methodologies showing greatest potential in characterizing urban form, allowing researchers a tool to evaluate the urban form. In a nutshell we aim to contribute to the knowledge of the LMA and to the development of one of the most innovative approaches to the study of urban dynamics.Peer Reviewe

Synthesis and characterization of amorphous poly(ethylene oxide)/poly(trimethylene carbonate) polymer blend electrolytes

Solid Polymer Electrolytes (SPEs) have been proposed as substitutes for conventional non-aqueous electrolytes in various electrochemical devices. These promising materials may be of interest in various practical devices including batteries, sensors and electrochromic displays as they can offer high performance in terms of specific energy and specific power (batteries), safe operation, form flexibility in device arquitecture and low manufacturing costs. Many different host polymers have been characterized over the last 30 years, however a relatively un-explored strategy involves the use of interpenetrating blends incorporating two or more polymers. Electrolyte systems based on interpenetrating blends of known host polymers, poly(ethylene oxide) and poly(trimethylene carbonate), doped with lithium perchlorate, were prepared by co-dissolution in acetonitrile. This combination of polymer components results in the formation of a material that may be applicable in batteries and electrochromic devices. The results of characterization of polymer electrolyte systems based on interpenetrating blends of amorphous poly(ethylene oxide) and poly(trimethylene carbonate) host matrices, with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as guest salt, are described in this study. Electrolytes with compositions of n between 5 and 15 (where n represents the total number of cation-coordinating units per lithium ion) were obtained as flexible, transparent and free-standing films that were characterized by measurements of conductivity, cyclic voltammetry, differential scanning calorimetry and thermogravimetry.Fundação para a Ciência e Tecnologia (FCT

Photophysics of sunscreen molecules in the gas phase : a stepwise approach towards understanding and developing next-generation sunscreens

The relationship between exposure to ultraviolet (UV) radiation and skin cancer urges the need for extra photoprotection, which is presently provided by widespread commercially available sunscreen lotions. Apart from having a large absorption cross section in the UVA and UVB regions of the electromagnetic spectrum, the chemical absorbers in these photoprotective products should also be able to dissipate the excess energy in a safe way, i.e. without releasing photoproducts or inducing any further, harmful, photochemistry. While sunscreens are tested for both their photoprotective capability and dermatological compatibility, phenomena occurring at the molecular level upon absorption of UV radiation are largely overlooked. To date, there is only a limited amount of information regarding the photochemistry and photophysics of these sunscreen molecules. However, a thorough understanding of the intrinsic mechanisms by which popular sunscreen molecular constituents dissipate excess energy has the potential to aid in the design of more efficient, safer sunscreens. In this review, we explore the potential of using gas-phase frequency- and time-resolved spectroscopies in an effort to better understand the photoinduced excited-state dynamics, or photodynamics, of sunscreen molecules. Complementary computational studies are also briefly discussed. Finally, the future outlook of expanding these gas-phase studies into the solution phase is considered

Urban form analysis employing land cover and spatial metrics: the case of the Lisbon Metropolitan Area

In order to face the challenges of urban planning, there is an increasing need to monitor and quantify urban occupation. This study, conducted within the research project "FURBS: Sustainable Urban Form - Methodological development for Portugal (PTDC/GEO/69109/2006), seeks to examine the urban form of the Lisbon Metropolitan Area (LMA), and its occupation between 1990 and 2000, using spatial metrics. The LMA congregates nearly 3 million inhabitants, around 26% of the Portuguese total population. A relevant characteristic of the region is that it has been subject to a constant opening of new areas of urbanization, which had caused in this region, an increase of 18.6% of housing units between 1991 and 2001, while the total population grew only 4.3%. In this study, we sought to apply the use of spatial metrics to CORINE Land Cover urban classes, analysing the evolution of urban area with a wide range of spatial metrics in order to quantify the urban evolution in the region. Spatial metrics have been used in ecology studies where they are known as landscape metrics. These metrics represent the geometric characteristics of the landscape units and the spatial relationships between them. Only recently these metrics started to be used to analyse and classify the urban form in a more systematic way. The applications of quantitative indicators are one of the methodologies showing greatest potential in characterizing urban form, allowing researchers a tool to evaluate the urban form. In a nutshell we aim to contribute to the knowledge of the LMA and to the development of one of the most innovative approaches to the study of urban dynamics.Peer Reviewe