4 research outputs found
Seeing Theory: A Visual Introduction to Probability and Statistics
No full textAs mathematics instructors and students know, lucid visualizations are essential to helping learners understand complex mathematical concepts. Seeing Theory is an online, interactive textbook that utilizes colorful, interactive visualizations and animations to explain concepts like compound probability and Bayesian Inference. This resource was envisioned by Daniel Kunin (currently a master's student in mathematics and computer science at Stanford University), who created Seeing Theory along with designer Jingru Guo, software engineer Tyler Dae Devlin, and statistics student Daniel Xiang. Seeing Theory contains six chapters, each of which contains three interactive visualizations. Each visualization contains two panels: a short explanation of each concept appears on the left, while a graph or chart appears on the right. In addition, the left panel often contains an interactive element. For instance, in the basic probability module, users are invited to flip a coin, roll a die, and draw a card. As they do so, the graph on the right reflects the outcome of these actions, revealing the principles of basic probability
Free entry in infrastructure
No full textWith a policy of free entry, individuals, firms, or community groups who wish to supply power, water, and sanitation services can do so with minimal legal restrictions. Free entry is the opposite of"exclusivity"or"legal monopoly". Free entry is allowed in most industries, but governments usually allow only one provider of power, water, and sanitation in any given area. This is supposed to prevent wasteful duplication and ensure a supply of essential services to poor and marginal areas. But monopoly water and power utilities often operate at high cost, lack funds to invest, and provide low-quality, unreliable service. Worse, poor and marginal areas are often unserved. When the monopoly model doesn't work, it is time to look at alternatives. The authors provide examples of alternative solutions in developing countries: *In Karachi, Pakistan, the Orangi Pilot Project provides sanitation in an unplanned settlement. Roughly 800,000 working class people lived in an area where sanitary conditions were medievaland a long-hoped-for sewerage system never came. Starting in 1980, a charitable group developed a low-cost approach to piped sanitation, explained the technology to the community, and catalyzed community action. Householders and neighborhoods funded the construction of household pourflush latrines and sewerage lines. * In Paraguay, 300 to 400 private individuals and aguateros supply good quality piped water to areas unserved by the public water company. Unlike the public company, the aguateros allow payment of connection fees on installment, making it easier for low-income consumers to connect. * In Yemen, small-scale electricity providers innovatively meet the rural and village demand for electricity that the public utility does not meet. These entrants seldom duplicate investments, although some government intervention to ensure interconnection could improve efficiency. Limitations on entry may sometimes be justified for environmental reasons or to promote private sector investment, but those cases are rare. Legalizing alternative providers will allow them to expand and meet new needs. Limits on their entry may be needed sometimes, but limits should be the exception, not the rule, the authors argue. Generally, free entry should be allowed in power, water, and sanitation.Health Economics&Finance,Decentralization,Water and Industry,Economic Theory&Research,Environmental Economics&Policies,Town Water Supply and Sanitation,Environmental Economics&Policies,Health Economics&Finance,Water and Industry,Economic Theory&Research
Extraction and analysis of signatures from the Gene Expression Omnibus by the crowd
No full textGene expression data are accumulating exponentially in public repositories. Reanalysis and integration of themed collections from these studies may provide new insights, but requires further human curation. Here we report a crowdsourcing project to annotate and reanalyse a large number of gene expression profiles from Gene Expression Omnibus (GEO). Through a massive open online course on Coursera, over 70 participants from over 25 countries identify and annotate 2,460 single-gene perturbation signatures, 839 disease versus normal signatures, and 906 drug perturbation signatures. All these signatures are unique and are manually validated for quality. Global analysis of these signatures confirms known associations and identifies novel associations between genes, diseases and drugs. The manually curated signatures are used as a training set to develop classifiers for extracting similar signatures from the entire GEO repository. We develop a web portal to serve these signatures for query, download and visualization
Reproducibility of fluorescent expression from engineered biological constructs in E. coli
No full textWe present results of the first large-scale interlaboratory study carried out in synthetic biology, as part of the 2014 and 2015 International Genetically Engineered Machine (iGEM) competitions. Participants at 88 institutions around the world measured fluorescence from three engineered constitutive constructs in E. coli. Few participants were able to measure absolute fluorescence, so data was analyzed in terms of ratios. Precision was strongly related to fluorescent strength, ranging from 1.54-fold standard deviation for the ratio between strong promoters to 5.75-fold for the ratio between the strongest and weakest promoter, and while host strain did not affect expression ratios, choice of instrument did. This result shows that high quantitative precision and reproducibility of results is possible, while at the same time indicating areas needing improved laboratory practices.Peer reviewe
