Generalizing Normality: Different Estimation Methods for Skewed Information

Normality is the most commonly used mathematical supposition in data modeling. Nonetheless, even based on the law of large numbers (LLN), normality is a strong presumption, given that the presence of asymmetry and multi-modality in real-world problems is expected. Thus, a flexible modification in the normal distribution proposed by Elal-Olivero adds a skewness parameter called Alpha-skew-normal (ASN) distribution, which enables bimodality and fat-tail, if needed, although it is sometimes not trivial to estimate this third parameter (regardless of the location and scale). This work analyzed seven different statistical inferential methods towards the ASN distribution on synthetic data and historical data of water flux from 21 rivers (channels) in the Atacama region. Moreover, the contributions of this paper are related to the estimations of probability surrounding rivers’ flux levels in the surroundings of Copiapó city, which is the most economically important city of the third Chilean region and is known to be located in one of the driest areas on Earth (excluding the North and the South Poles). The results show the competitiveness of the MPS and RADE methods with respect to the MLE method, as well as their excellent performance.

MALDI-TOF MS and 16S RNA Identification of Culturable Gastric Microbiota: Variability Associated with the Presence of Helicobacter pylori

Helicobacter pylori is the main bacteria associated with gastroduodenal diseases. Recent studies have reported that gastric microbiota might be modified by the H. pylori colonization, favoring gastric lesions′ development. In Chile, the region of La Araucanía concentrates a high risk of gastric cancer associated with Helicobacter pylori colonization, rurality, poverty, and Mapuche ethnicity. Hence, we aimed to identify the culturable gastric microbiota and characterize its variability at different stages of epithelial injury, based on its H. pylori colonization in dyspeptic patients from this Chilean region. Microaerophilic bacteria strains were isolated from antrum biopsies of 155 dyspeptic patients′ biopsies and identified using MALDI-TOF MS or 16sRNA gene sequencing for non-pylori species identification, and UreC gene amplification for H. pylori confirmation. We found 48 species from 18 families, mainly belonging to Neisseriaceae (21.3%), Streptococcaceae (20.0%), Actynomicetaceae (9.0%), Enterobacteriaceae, and Lactobacillaceae (4.5%); however, Streptococcaceae and Actinomycetaceae families showed a significant reduction in samples infected with H. pylori, along with a considerably lower diversity of species. Our results revealed a microbiota modification due to H. pylori colonization associated with the gastric epithelial state, suggesting a potential microbiota role for developing and progressing gastric diseases.

Celia Leyton, su pintura indigenista, retrato del patrimonio cultural del pueblo mapuche

This research explores key aspects of the life and work of the Chilean artist Celia Leyton Vidal (Santiago de Chile, 1895-1975). Celia Leyton’s research and painting work was mainly developed in La Araucanía, the southern Chilean region where she spent most of her adult life. As a prominent middle school teacher, art researcher and painter, Leyton made a significant contribution to the academic art domain, and was devoted to the promotion and dissemination of the Mapuche culture and values. Her prolific field work includes annotations, sketches, descriptions and analysis of her research experiences, all of which led to the creation of numerous paintings and documents, including catalogues and an autobiography. Fearing it was endangered in modern times, the artist devotedly dedicated her entire life and work to disseminate Mapuche culture, virtues and worldview. A first biographic review provided a general understanding about the painter’s life, her academic background, gender-related struggles, as well as the influential references that contributed to shape her social and ethical profile, and her visual representations and symbolism. Finally, we discuss a formal and symbolic analysis of a self-portrait, considered as one of her most important art works, and which reveals the true value of her artistic and cultural project

Tourism statistics

Tourism statistics are key sources of information for economic planners, tourism researchers, and operators. Still, several cases of data inadequacy and inaccuracy are reported in literature. The aim of this article is to propose a methodology useful to improve tourism statistics: a modified version of the Coarsened Exact Matching. The methodological steps herein proposed provide tourism statisticians and authorities with a tool to improve the reliability of available sample surveys. Data from a Chilean region are used to illustrate the method. This study contributes to the realm of tourism statistics literature in that it offers a new methodological approach to the creation of accurate and adequate tourism data.

A statistical study of <i>Weinmannia</i> pollen trajectories across the Andes

Recent airborne pollen records data from Northern Patagonia (San Carlos de Bariloche, Argentina, Lat. 41.1435° S, Long. 71.375° W, 800 m elevation) suggest that pollen transport takes place from the west to the east slope of the Andes. However, the atmospheric characteristics responsible of this transport have not yet been studied. The aim of this paper is to assess potential source areas and to describe the involved atmospheric mechanisms of the trans-Andean pollen transport. Methodology relies on the analysis of backward trajectories of air masses calculated with the HYSPLIT 4.9 regional model for particular days where airborne pollen of Weinmannia trichosperma Cav. was detected east of the Andes. This pollen type was selected because it is found regularly at localities in eastern Patagonia beyond its present-day distribution. Weinmannia's substantial presence during early Holocene times would also benefit from better knowledge of its transport mechanisms. Correspondence between atmospheric trajectories and the position of sources was checked using GIS maps. Mode T, Principal Component Analysis (PCA) with Varimax rotation was used to identify the main spatial structure of geopotential height anomalies producing the calculated trajectories. Eighty-eight cases showed that the calculated directions of trajectories trended from the Northwest to Southwest passing over the Chilean region of W. trichosperma distribution. PCs results showed two patterns of negative anomalies over southern Patagonia. The prevailing circulation pattern which drives airborne transport is the presence of a trough located south of 37 to 40° S with its axis over western Patagonia. The synoptic situations for two cases highly correlated with principal component scores were described.