Structure learning of undirected graphical models for count data

Biological processes underlying the basic functions of a cell involve complex interactions between genes. From a technical point of view, these interactions can be represented through a graph where genes and their connections are, respectively, nodes and edges. The main objective of this paper is to develop a statistical framework for modelling the interactions between genes when the activity of genes is measured on a discrete scale. In detail, we define a new algorithm for learning the structure of undirected graphs, PC-LPGM, proving its theoretical consistence in the limit of infinite observations. The proposed algorithm shows promising results when applied to simulated data as well as to real data

Applying Social Media in the Hotel Sector: Satisfaction with the Facebook Pages of Hotels and Intention of Future Visit

CC BY-NC-ND 4.0This study is carried out with the main objective of analyzing the determining factors for the gratification of Facebook users when accessing a hotel’s Facebook page and verifying the relationship between satisfaction with the Facebook page and the intention to visit a hotel. This study surveyed 404 Facebook users in Vietnam. The methods of exploratory factor analysis, confirmatory factor analysis, and structural equation modeling are used to process the data. The results conclude that the factors affecting satisfaction with hotels’ Facebook pages are information, convenience, and social interaction; in addition, satisfaction with these Facebook pages has a positive effect on the intention to visit a hotel. This study contributes to hotels by helping them to understand the expectations of customers on their Facebook pages. From there, suggestions as to how to take measures to improve their presence on Facebook and enhance their competitiveness on the virtual platform are provided

Guided structure learning of DAGs for count data

In this paper, we tackle structure learning of Directed Acyclic Graphs (DAGs), with the idea of exploiting available prior knowledge of the domain at hand to guide the search of the best structure. In particular, we assume to know the topological ordering of variables in addition to the given data. We study a new algorithm for learning the structure of DAGs, proving its theoretical consistence in the limit of infinite observations. Furthermore, we experimentally compare the proposed algorithm to a number of popular competitors, in order to study its behavior in finite samples.Comment: arXiv admin note: text overlap with arXiv:1810.1085

Low doses of the quaternary ammonium salt Cetyltrimethylammonium bromide can be used as a pesticide to control grazers in microalgal cultures

© 2019 Elsevier B.V. Contamination of large-scale microalgal cultures by grazers can cause huge losses in biomass productivity. Here we propose the use of a quaternary ammonium salt cetyltrimethylammonium bromide (CTAB) to eradicate three types of commonly occurring grazers in microalgal cultures: the rotifer Brachionus, the ciliate Sterkiella and the flagellate Paraphysomonas. Low, premicellar doses (≤3 μM) of CTAB rapidly eradicated (within 1–2 d) all three tested grazers from microalgal cultures without significant losses (p < 0.05) in microalgal productivity. However, doses exceeding 5 μM also negatively affected microalgal growth. The optimal dose of CTAB that resulted in complete eradication of the grazers with minimum impact on microalgal productivity was 3 μM for Brachionus, 2 μM for Sterkiella and 3 μM for Paraphysomonas. Thus, being a readily available chemical, CTAB has the potential to be used as a fast-acting, low-cost control agent against a range of frequently occurring grazer types in large-scale microalgal cultures.status: publishe

Structure learning for zero-inflated counts, with an application to single-cell RNA sequencing data

The problem of estimating the structure of a graph from observed data is of growing interest in the context of high-throughput genomic data, and single-cell RNA sequencing in particular. These, however, are challenging applications, since the data consist of high-dimensional counts with high variance and over-abundance of zeros. Here, we present a general framework for learning the structure of a graph from single-cell RNA-seq data, based on the zero-inflated negative binomial distribution. We demonstrate with simulations that our approach is able to retrieve the structure of a graph in a variety of settings and we show the utility of the approach on real data

ARSENIC POLLUTION IN GROUNDWATER IN RED RIVER DELTA, VIETNAM : SITUATION AND HUMAN EXPOSURE

Joint Research on Environmental Science and Technology for the Eart

Sorting or supporting teachers? An exploration of the imbalanced role of classroom observation in the development and assessment of Vietnamese secondary schoolteachers

In 2018, Vietnam’s National Teacher Education Programme established a new framework for schoolteachers’ professional development. Classroom observation was the dominant method used for teacher monitoring, assessment and development. This paper explores the use and impact of current classroom observation policy and practice on novice teachers in Vietnamese secondary schools. Our study draws on qualitative data from 35 semi-structured interviews across four provinces. Our findings revealed ongoing policy-practice tensions, with the prioritisation and dominance of classroom observation as an assessment tool for sorting rather than supporting teachers. These tensions were indicative of a wider policy-practice disconnect enshrined in recent reform by the Ministry of Education and Training that advocated the adoption of lesson study as the preferred national approach in schools. However, the experiences of our participants reflected a very different picture in practice that reinforced traditional hierarchies of power associated with evaluative models of observation that are designed to standardise and rank teachers’ classroom performance rather than develop the quality of teaching. Instead of the more collaborative and collegial ethos typically associated with inquiry-based approaches like lesson study, observation was being used largely as a high-stakes assessment, resulting in increased levels of anxiety and stress among teachers

The role of classroom observation in the development and assessment of schoolteachers in Vietnam: a review of national policy and research

This paper focuses on the role of classroom observation in the development and assessment of schoolteachers in Vietnam through a narrative review of current policy and cognate research literature. The overall aim of this review was twofold. Firstly, to contribute to a growing bank of Vietnam-based studies to maximise the value of the insights from this scholarly work into recent policy reforms on teachers’ professional development in Vietnam. Secondly, to widen access and exposure to published work on the topic in Vietnamese that is not readily accessible to English-speaking scholars. This review revealed a long history and engrained culture of using observation as a teacher performance evaluation tool. In recent years, there have been policy reforms and research studies that have repositioned observation as a tool for teacher learning and development. However, the implementation of these reforms has been inconsistent across Vietnam, along with recent reform having encountered resistance from a culture of compliance in schools. This paper identifies some of the key issues that policy makers and educational leaders need to address in practice in order to ensure the effective and meaningful implementation of the reforms relating to the use of observation for learning and developmental purposes