Kaplan-Meier V- and U-statistics

In this paper, we study Kaplan-Meier V- and U-statistics respectively defined as $\theta(\widehat{F}_n)=\sum_{i,j}K(X_{[i:n]},X_{[j:n]})W_iW_j$ and $\theta_U(\widehat{F}_n)=\sum_{i\neq j}K(X_{[i:n]},X_{[j:n]})W_iW_j/\sum_{i\neq j}W_iW_j$, where $\widehat{F}_n$ is the Kaplan-Meier estimator, $\{W_1,\ldots,W_n\}$ are the Kaplan-Meier weights and $K:(0,\infty)^2\to\mathbb R$ is a symmetric kernel. As in the canonical setting of uncensored data, we differentiate between two asymptotic behaviours for $\theta(\widehat{F}_n)$ and $\theta_U(\widehat{F}_n)$. Additionally, we derive an asymptotic canonical V-statistic representation of the Kaplan-Meier V- and U-statistics. By using this representation we study properties of the asymptotic distribution. Applications to hypothesis testing are given

Exploring the Interplay between CAD and FreeFem++ as an Energy Decision-Making Tool for Architectural Design

The energy modelling software tools commonly used for architectural purposes do not allow a straightforward real-time implementation within the architectural design programs. In addition, the surrounding exterior spaces of the building, including the inner courtyards, hardly present a specific treatment distinguishing these spaces from the general external temperature in the thermal simulations. This is a clear disadvantage when it comes to streamlining the design process in relation to the whole-building energy optimization. In this context, the present study aims to demonstrate the advantages of the FreeFem++ open source program for performing simulations in architectural environments. These simulations include microclimate tests that describe the interactions between a building architecture and its local exterior. The great potential of this mathematical tool can be realized through its complete system integration within CAD (Computer-Aided Design) software such as SketchUp or AutoCAD. In order to establish the suitability of FreeFem++ for the performance of simulations, the most widely employed energy simulation tools able to consider a proposed architectural geometry in a specific environment are compared. On the basis of this analysis, it can be concluded that FreeFem++ is the only program displaying the best features for the thermal performance simulation of these specific outdoor spaces, excluding the currently unavailable easy interaction with architectural drawing programs. The main contribution of this research is, in fact, the enhancement of FreeFem++ usability by proposing a simple intuitive method for the creation of building geometries and their respective meshing (pre-processing). FreeFem++ is also considered a tool for data analysis (post-processing) able to help engineers and architects with building energy-efficiency-related tasks

Quantitative Intensity Harmonization of Dopamine Transporter SPECT Images Using Gamma Mixture Models

PURPOSE: Differences in site, device, and/or settings may cause large variations in the intensity profile of dopamine transporter (DAT) single-photon emission computed tomography (SPECT) images. However, the current standard to evaluate these images, the striatal binding ratio (SBR), does not efficiently account for this heterogeneity and the assessment can be unequivalent across distinct acquisition pipelines. In this work, we present a voxel-based automated approach to intensity normalize such type of data that improves on cross-session interpretation. PROCEDURES: The normalization method consists of a reparametrization of the voxel values based on the cumulative density function (CDF) of a Gamma distribution modeling the specific region intensity. The harmonization ability was tested in 1342 SPECT images from the PPMI repository, acquired with 7 distinct gamma camera models and at 24 different sites. We compared the striatal quantification across distinct cameras for raw intensities, SBR values, and after applying the Gamma CDF (GDCF) harmonization. As a proof-of-concept, we evaluated the impact of GCDF normalization in a classification task between controls and Parkinson disease patients. RESULTS: Raw striatal intensities and SBR values presented significant differences across distinct camera models. We demonstrate that GCDF normalization efficiently alleviated these differences in striatal quantification and with values constrained to a fixed interval [0, 1]. Also, our method allowed a fully automated image assessment that provided maximal classification ability, given by an area under the curve (AUC) of AUC = 0.94 when used mean regional variables and AUC = 0.98 when used voxel-based variables. CONCLUSION: The GCDF normalization method is useful to standardize the intensity of DAT SPECT images in an automated fashion and enables the development of unbiased algorithms using multicenter datasets. This method may constitute a key pre-processing step in the analysis of this type of images.Instituto de Salud Carlos III FI14/00497 MV15/00034Fondo Europeo de Desarrollo Regional FI14/00497 MV15/00034ISCIII-FEDER PI16/01575Wellcome Trust UK Strategic Award 098369/Z/12/ZNetherland Organization for Scientific Research NWO-Vidi 864-12-00

Motivational and demotivational factors, as well as identifying prominent strategies for adult English learners of the educational entity Fundación Intercultura Bogotá. D.C.

El presente estudio de investigación tiene como propósito determinar los factores que estimulan el aprendizaje en inglés para identificar estrategias comunicativas de interés para los estudiantes de la institución educativa Fundación Intercultura en Bogotá. A partir de su involucramiento, y de las relaciones que existen en correspondencia con la identificación de la motivación, enfatizando los factores intrínsecos, extrínsecos y distractores, se utilizaron los elementos principales para proponer un estudio que permitiera analizar y reflexionar sobre cómo resaltar el interés en las clases de inglés, así como formular una metodología y hacer recomendaciones. La investigadora Bilbao, C. (2017), destaca y reafirma lo postulado por otros autores respecto a la influencia de los factores motivacionales en el desarrollo de los currículos escolares y universitarios ya que tanto los docentes como los estudiantes de inglés están capacitados en el manejo de competencias. Está en línea con lo que se pretende reducir los impactos negativos de las emociones en el aprendizaje del inglés. En consecuencia, los docentes deben tomar conciencia del manejo de las emociones positivas para fortalecer la motivación en las clases de inglés. Deben promoverlos con didácticas y actividades diseñadas de acuerdo con los intereses y estilos de aprendizaje de los estudiantes para que los resultados de aprendizaje sean más efectivos. Esto nos permitirá transmitir recomendaciones para fortalecer el uso de las herramientas TIC para demostrar las ventajas que ofrecen a los estudiantes y docentes. Finalmente, serán conscientes de que los docentes pueden mejorar sus estrategias didácticas y pedagógicas. Palabras clave: Motivación, estrategias, aprendizaje, herramientas TIC, desmotivación.This exploratory study aims to identify communicative strategies of interest to the students of Fundación Intercultura in Bogota that stimulate learning in English. Based on their involvement and the relationships between them, emphasizing intrinsic, extrinsic, and distracting factors, the main elements were used to suggest a study that would analyze and reflect on how to raise interest in English classes, formulate a methodology, and make recommendations. The researcher Bilbao, C. (2017) highlights and reaffirms what has been postulated by other authors regarding the influence of motivational factors in the development of school and university curricula since both teachers and students of English are trained in managing competitions. She is in line with what is intended to reduce the negative impacts of emotions on learning English. Consequently, teachers must become aware of managing positive emotions to strengthen motivation in English classes. They must promote them with didactics and activities designed according to the interests and learning styles of the students so that the learning results are more effective. This allows us to transmit recommendations to strengthen the use of ICT tools to demonstrate the advantages they offer to students and teachers. Finally, they will be aware that teachers can improve their didactic and pedagogical strategies. Keywords: Motivation, demotivation, strategies, adult learning, ICT tools

A reproducing kernel Hilbert space log-rank test for the two-sample problem

Weighted log‐rank tests are arguably the most widely used tests by practitioners for the two‐sample problem in the context of right‐censored data. Many approaches have been considered to make them more robust against a broader family of alternatives, including taking linear combinations, or the maximum among a finite collection of them. In this article, we propose as test statistic the supremum of a collection of (potentially infinitely many) weighted log‐rank tests where the weight functions belong to the unit ball in a reproducing kernel Hilbert space (RKHS). By using some desirable properties of RKHSs we provide an exact and simple evaluation of the test statistic and establish connections with previous tests in the literature. Additionally, we show that for a special family of RKHSs, the proposed test is omnibus. We finalize by performing an empirical evaluation of the proposed methodology and show an application to a real data scenario

A reproducing kernel Hilbert space log-rank test for the two-sample problem

Weighted log‐rank tests are arguably the most widely used tests by practitioners for the two‐sample problem in the context of right‐censored data. Many approaches have been considered to make them more robust against a broader family of alternatives, including taking linear combinations, or the maximum among a finite collection of them. In this article, we propose as test statistic the supremum of a collection of (potentially infinitely many) weighted log‐rank tests where the weight functions belong to the unit ball in a reproducing kernel Hilbert space (RKHS). By using some desirable properties of RKHSs we provide an exact and simple evaluation of the test statistic and establish connections with previous tests in the literature. Additionally, we show that for a special family of RKHSs, the proposed test is omnibus. We finalize by performing an empirical evaluation of the proposed methodology and show an application to a real data scenario

Virulence of Spanish Phytophthora nicotianae isolates towards Capsicum annuum germplasm and pathogenicity towards Lycopersicum esculentum

The virulence of six northwestern Spanish Phytophthora nicotianae Breda de Haan isolates towards the pepper (Capsicum annuum) cultivars commonly used for the determination of P. capsici Leonian pathotype (SCM 334, PI201234 and Yolo Wonder), was similar to that of the latter oomycete but different to that of the German reference isolate P. nicotianae 411.87. When nine local C. annuum cultivars were inoculated with a P. nicotianae isolate of well known pathogenicity, the virulence recorded was significantly different to that recorded for P. capsici. Though the average level of resistance of the northwestern Spanish Capsicum germplasm to P. nicotianae was incomplete and weaker than that recorded for the SCM 334 and PI201234 cultivars, genotypes Co 12B and Co 3.25 showed high resistance to this oomycete. None of the six northwestern Spanish P. nicotianae isolates tested were pathogenic towards Lycopersicum esculentum cv. S. Pedro, unlike P. capsici, which produced clear collar and root rot in this host

Neutrino mixing and masses in a left-right model with mirror fermions

In the framework of a left-right model containing mirror fermions with gauge group SU(3)$_{C} \otimes SU(2)_{L} \otimes SU(2)_{R} \otimes U(1)_{Y^\prime}$, we estimate the neutrino masses, which are found to be consistent with their experimental bounds and hierarchy. We evaluate the decay rates of the Lepton Flavor Violation (LFV) processes $\mu \rightarrow e \gamma$, $\tau \rightarrow \mu \gamma$ and $\tau \rightarrow e\gamma$. We obtain upper limits for the flavor-changing branching ratios in agreement with their present experimental bounds. We also estimate the decay rates of heavy Majorana neutrinos in the channels $N \rightarrow W^{\pm} l^{\mp}$, $N \rightarrow Z \nu_{l}$ and $N \rightarrow H \nu_{l}$, which are roughly equal for large values of the heavy neutrino mass. Starting from the most general Majorana neutrino mass matrix, the smallness of active neutrino masses turns out from the interplay of the hierarchy of the involved scales and the double application of seesaw mechanism. An appropriate parameterization on the structure of the neutrino mass matrix imposing a symmetric mixing of electron neutrino with muon and tau neutrinos leads to Tri-bimaximal mixing matrix for light neutrinos.Comment: Accepted by European Physical Journal

Rutas metodológicas para la redimensión de la actuación de las bibliotecas públicas de La Habana

Objective. To present a research methodology oriented to re-dimensioning the performance of municipal public libraries in communities of The Havana, Cuba. Design/Methodology/Approach. The research process was characterized by a mixed methodology and a multiple triangulation approach. Results/Discussion. The ten phases, in which the research process was materialized, were presented through quantitative and qualitative methods and techniques. Conclusions. Multi-case study as an approach, mixed-qualitative research as a strategy and a multiple triangulation design conformed a relevant methodological strategy. Originality/Value. In Cuba, and particularly in Havana, municipal public libraries do not usually conduct qualitative or mixed researches concerning to its performance. For this reason, the exposition about the research experience in the scenario of Havana municipal public libraries in the period 2013-2016 was considered as pertinent and necessary

On the Influence of Shade in Improving Thermal Comfort in Courtyards

This study analyzes the thermal performance of courtyards in traditional buildings in the city center of Córdoba (South of Spain), one of them displaying a shading component, to determine the influence of this precise element. The courtyards have been monitored simultaneously during a summer period when temperatures during the day reached over 45 °C. The obtained data was contrasted, and we confirmed that the shading element provided an improvement of the thermal performance of the courtyard which doubled the thermal leap between outdoor and inside the courtyard temperatures when the shading element was installed, in comparison to the courtyard without shade. Therefore, the tempering effect of courtyards can be significantly improved by means of using these simple elements