Dialectometric analysis of language variation in Twitter

In the last few years, microblogging platforms such as Twitter have given rise to a deluge of textual data that can be used for the analysis of informal communication between millions of individuals. In this work, we propose an information-theoretic approach to geographic language variation using a corpus based on Twitter. We test our models with tens of concepts and their associated keywords detected in Spanish tweets geolocated in Spain. We employ dialectometric measures (cosine similarity and Jensen-Shannon divergence) to quantify the linguistic distance on the lexical level between cells created in a uniform grid over the map. This can be done for a single concept or in the general case taking into account an average of the considered variants. The latter permits an analysis of the dialects that naturally emerge from the data. Interestingly, our results reveal the existence of two dialect macrovarieties. The first group includes a region-specific speech spoken in small towns and rural areas whereas the second cluster encompasses cities that tend to use a more uniform variety. Since the results obtained with the two different metrics qualitatively agree, our work suggests that social media corpora can be efficiently used for dialectometric analyses.Comment: 10 pages, 7 figures, 1 table. Accepted to VarDial 201

On-surface synthesis of functional organic nanostructures

The improvement of electronic device efficiency is currently based on the miniaturization of existing electronic devices. The manufacturing costs of reducing the size of semiconductor based circuits below 10 nm is unfeasible for companies. To overcome this limitation, other materials are currently being developed to fabricate equivalent electronic circuits with smaller dimensions. In this context, on-surface synthesis (OSS) is a bottom-up manufacturing technique based on the reaction of molecules to achieve a well-defined organic structure. The atomic precision of OSS allows to create functional organic molecules for molecular electronic devices. Scanning probe microscopy techniques are the most common microscopy techniques used to analyze on-surface synthesized structures. In this thesis, we present the synthesis by OSS and characterization by scanning tunneling microscopy (STM) and spectroscopy (STS) techniques of functional nanostructures. The synthesized manganese phthalocyanine (MnPc) includes in the phthalocyanine ring four diarylethylene moieties (DAE). The DAE moiety is an optically active group. This organo-metallic complex with optically active groups and the Mn in its structure could work as a magneto-optical transducer. We have successfully induced reversible switches with the STM tip between the assigned open and closed configurations of the DAE moiety. The other organic structures synthesized by OSS studied in this thesis are chiral graphene nanoribbons (ch-GNRs) on Ag(001). Combining STM and STS techniques we have studied the evolution of the electronic structure of ch-GNRs depending on their width and length. Furthermore, when the ch-GNRs are relocated on top of MgO monoloayers grown on the same Ag(001) substrate by means of atomic manipulation, a combination of charge transfer and electronic localization gives rise to a critical discretization of the extended edge states. This causes unprecedented long life times of the ribbon’s electronic states and spin splitting of the frontier orbitals ascribed to electron-electron correlations. Finally, we have evaluated the suitability of the ch-GNR/MgO monolayer/Ag(001) system as a molecular spin polarized transistor.<br /

TREES AS ECOLOGICAL TEMPLATES FOR TROPICAL LITTER ARTHROPOD COMMUNITIES

My dissertation spans five chapters on diverse topics on the ecology and taxonomy of ants in tropical regions. In Chapter 1, I explored if tree species identity explained litter arthropod biodiversity. In Chapter 2, I explored if tree species identity shape the structure of brown food webs. In Chapter 3, I reviewed the systematic status of the Neotropical ant genus Tatuidris. In Chapter 4, I conducted an experiment to explore the consecuences of high ant abundance in brown food webs. In Chapter 5, I explored mechanisms of ant species co-existence using trait- and phylogenetic-based test of community composition

Mapping continental Ecuadorian ant species

Ecuador is considered a megadiverse country but information on the distribution and conservation of its ant species is scarce and scattered through the literature. Here we review 150 years of published literature to assemble the first comprehensive species list of continental Ecuadorian ants (excluding the Galapagos Islands). Our main goals are to provide support to online tools (www.theantsofecuador.com), and to serve as a reference to the various research initiatives currently being done in the country. We found 2,124 ant records, from 679 ant species, in 180 localities, reported in 149 articles. We used a subset of this database (i.e. 1,111 records left after removal of duplicates and records with no locality info) to review the Ecuadorian regions, provinces, and national parks covered by the list. For a tropical country, both the number of records per ant species (mean=1.8, SD=1.9) and the number of ant species per locality (mean=6.2, SD=29.7) are extremely low. Moreover, the ant records in our list are biased towards three provinces (Orellana, 410 ant records and 378 ant spp.; Sucumbios, 212 and 177; Pichincha, 129 and 92), one region (Oriente, 779 records and 487 ant species) and non-protected areas (777 ant records and 510 ant spp.). Endemic ants are poorly covered by the Ecuadorian system of protected areas. This study highlights the gaps and opportunities in ant research for the country

Diagnóstico del impacto económico en la ganadería lechera del Ecuador durante la pandemia del SARS-cov-2.

El objetivo de la presente investigación fue conocer acerca de los costos de operación que conlleva el mantener una ganadería lechera en el Ecuador durante la pandemia del SARS-CoV-2. La información utilizada fue obtenida mediante la búsqueda sistemática en la Sede Web, revistas indexadas, repositorios nacionales e internacionales, trabajos de titulación y artículos científicos, basándose en una revisión descriptiva de las principales características de las ganaderías lecheras en el Ecuador antes, durante y después de la pandemia, donde se analizó lo siguiente: los costó de producción que se llevan a cabo en una ganadería lechera para determinar el costo del litro de leche, los cuales de acuerdo a distintos actores son costos fijos, variables y unitarios que a su vez se clasifican en distintas variables dependiendo el tipo de sistema de crianza y tecnificación de cada uno de ellos; el precio pagado al productor; el consumo per cápita a nivel nacional; la crisis económica que está atravesando el país debido a la disminución del precio de comercialización de la leche por la pandemia y las razas bovinas lecheras que más predominan. Se determinó que los costó de producción de los pequeños productores a diferencia de los medianos y grandes, van a perdida ya que obtienen un costo litro de leche mayor al precio establecido por el estado, el mismo que ha tenido un incremento negativo durante y después de la pandemia, el consumo per cápita en 2020 fue 90-100 lt/hab/año y para el 2021 de 103-110 lt/hab/año. Concluyendo que se debe llevar contabilidad de los ingresos y egresos dentro de una ganadería para poder determinar si está siendo rentable, por lo que se recomienda realizar investigaciones que permitan a los productores conocer la importancia de los costos de operación en la producción lechera.The objective of this research was to learn about the operating costs involved in maintaining dairy cattle in Ecuador during the SARS-CoV-2 pandemic. The information used was obtained through a systematic search on the Web site, indexed journals, national and international repositories, titling papers and scientific articles, based on o descriptive review of the main characteristics of dairy cattle in Ecuador before, during and after the pandemic. In this research was analyzed: the production costs that are carried out in a dairy cattle to determine the cost of the liter of milk, which according to different actors are fixed costs, variables and units which in turn are classified into different variables depending on the type of breeding and technofication system of each of them; the price paid to the producer; the consumption per capita at the national level; the economic crisis that the country is going through due to the decrease in the marketing price of milk due to the pandemic and the dairy cattle breeds that predominate the most. It was determined that the production costs of small producers, unlike the medium and large ones, are going to be lost because they obtain a cost liter of milk higher than the price established by the state, the same one that has had a negative increase during and after the pandemic, per capita consumption in 2020 was 90-100 lt/inhab/year and in 2021 it was 103-110 lt/inhab/year. Concluding that it is necessary to keep accounting of the income and expenses within a livestock to be able to determine if it is being profitable, so it is recommended to carry out research that allows the producers to know the importance of the costs of operation in the milk production

El cáncer de próstata confinado al órgano: diagnóstico excesivo y tratamiento innecesario

El sobrediagnóstico y el sobretratamiento son, muy probablemente, los efectos adversos más importantes del cribado en el cáncer de próstata. Asociadas a ellos tenemos que aceptar incertidumbres negativas en cuanto a la calidad de vida, el costo y la rentabilidad. Un porcentaje importante de los pacientes –aproximadamente un 40%– se encuadran dentro de lo que llamamos grupo de bajo riesgo de progresión. Este “cáncer” no implica una progresión inexorable a la metástasis y la muerte, por lo tanto su mejor forma de tratamiento sea, probablemente, la vigilancia clínica.Over-diagnosis and over-treatment are very likely the most significant adverse effects of screening on prostate cancer. Associated with them we have to accept negative uncertainties as to the quality of life, cost and profitability. A significant percentage of patients –approximately 40%– falls within what we call low-risk group for progression. This «cancer» does not imply an inexorable progression to metastasis and death and therefore its best form of treatment is likely clinical surveillance.Medicin

Towards Keypoint Guided Self-Supervised Depth Estimation

This paper proposes to use keypoints as a self-supervision clue for learning depth map estimation from a collection of input images. As ground truth depth from real images is difficult to obtain, there are many unsupervised and self-supervised approaches to depth estimation that have been proposed. Most of these unsupervised approaches use depth map and ego-motion estimations to reproject the pixels from the current image into the adjacent image from the image collection. Depth and ego-motion estimations are evaluated based on pixel intensity differences between the correspondent original and reprojected pixels. Instead of reprojecting the individual pixels, we propose to first select image keypoints in both images and then reproject and compare the correspondent keypoints of the two images. The keypoints should describe the distinctive image features well. By learning a deep model with and without the keypoint extraction technique, we show that using the keypoints improve the depth estimation learning. We also propose some future directions for keypoint-guided learning of structure-from-motion problems

Clinical Correlation Between Computerized Tomography Findings and Pathologic Diagnosis in Patients Surgically Treated for Complex Renal Cysts in a Colombian Tertiary Center

IntroductionRecent data have reexamined the historical rates of malignancy observed in Bosniak IIF and III cystic lesions, and this has led to an endorsement of the use of active surveillance as the standard of care for Bosniak III renal cysts by affirming that overtreatment rates for this subgroup are close to 50%. In light of this, the present study describes the correlation between imaging studies and pathologic diagnosis in patients surgically treated for complex renal cysts in Colombia.Materials and methodsThis is a retrospective, descriptive, and observational study. We analyzed the medical histories of patients who had been surgically treated for complex renal cysts between 2010 and 2018 in the urology department of a tertiary center in Bogota, Colombia. The exclusion criteria were incomplete clinical histories and absent diagnostic images or their official interpretation.ResultsOut of the 235 urological procedures performed, nine were excluded. And 6.19% (n = 14) were cases of surgically treated complex renal cysts; 38.46% were compatible with Bosniak 46.15% were Bosniak III, and 15.38% were Bosniak IV. The percentage of renal cancer as revealed by the histopathological study was 60, 66.7 and 100 for renal cysts Bosniak IIF, III, and IV, respectively; 77.7% of these confirmed oncological cases had received a diagnosis of clear cell renal carcinoma.ConclusionsIn our study, the percentage of malignancy in patients with renal cysts Bosniak IIF and III was found to be greater compared to the findings in the recent medical literature. We believe that the management offered to the population with complex renal cysts in Colombia should be tailored to the individual risk characteristics of each patient

Real space manifestations of coherent screening in atomic scale Kondo lattices

The interaction among magnetic moments screened by conduction electrons drives quantum phase transitions between magnetically ordered and heavy-fermion ground states. Here, starting from isolated magnetic impurities in the Kondo regime, we investigate the formation of the finite size analogue of a heavy Fermi liquid. We build regularly-spaced chains of Co adatoms on a metallic surface by atomic manipulation. Scanning tunneling spectroscopy is used to obtain maps of the Kondo resonance intensity with sub-atomic resolution. For sufficiently small interatomic separation, the spatial distribution of Kondo screening does not coincide with the position of the adatoms. It also develops enhancements at both edges of the chains. Since we can rule out any other interaction between Kondo impurities, this is explained in terms of the indirect hybridization of the Kondo orbitals mediated by a coherent electron gas, the mechanism that causes the emergence of heavy quasiparticles in the thermodynamic limit.Financial support was provided by the Spanish Plan Nacional de I+ D+ i (grants MAT 2013-46593-C6-3-P, MAT2016-78293-C6-6-R, MAT2015-66888-C3-2-R, and FIS2015-64886-C5-3-P), Charles University (programme PRIMUS/Sci/09) and the European Union through programmes Interreg-POCTEFA (grant TNSI/EFA194/16) and H2020-EINFRA-5-2015 MaX Center of Excellence (grant no. 676598). M. M.-L., M. P., and D. S. acknowledge the use of SAI at Universidad de Zaragoza. R. R. acknowledges The Severo Ochoa Centers of Excellence Program (grant no. SEV-2017-0706) and Generalitat de Catalunya (grant no. 2017SGR1506 and the CERCA Programme)

Differential validity and slant on the predictability of the admisson tests to the chilean universities (PSU)

La preocupación por la equidad en la medición educacional ha llevado a desarrollar diversos procedimientos para evaluar el potencial sesgo asociado a características sociodemográficas de los examinados. Estos procedimientos incluyen la validez y la predicción diferencial de los tests. En el primer caso, se analiza el grado de asociación entre los tests y alguna variable criterio (como el rendimiento académico), comparando dicha asociación entre grupos. En el segundo caso, se trata de establecer si la capacidad predictiva de los instrumentos de medición es equivalente para diversos grupos de examinados, comparando los errores de predicción. Empleando esta metodología con datos de las Pruebas de Selección Universitaria chilenas de Matemática y de Lenguaje y Comunicación, además de las Notas de Educación Media (como predictores) y el rendimiento académico de los estudiantes en el primer año de sus estudios universitarios (como criterio), se calcularon y compararon indicadores de validez y predicción diferencial según género y dependencia de los establecimientos educacionales. Los resultados, que presentan un patrón semejante al observado con pruebas de admisión norteamericanas, revelan una leve presencia de validez diferencial, especialmente cuando se considera el género de los estudiantes, revelando una consistente pero leve subpredicción del rendimiento de las mujere