Efficiency bounds for estimating linear functionals of nonparametric regression models with endogenous regressors

The main objective of this paper is to derive the efficiency bounds for estimating certain linear functionals of an unknown structural function when the latter is not itself a conditional expectation.

An Exploratory Study of COVID-19 Misinformation on Twitter

During the COVID-19 pandemic, social media has become a home ground for misinformation. To tackle this infodemic, scientific oversight, as well as a better understanding by practitioners in crisis management, is needed. We have conducted an exploratory study into the propagation, authors and content of misinformation on Twitter around the topic of COVID-19 in order to gain early insights. We have collected all tweets mentioned in the verdicts of fact-checked claims related to COVID-19 by over 92 professional fact-checking organisations between January and mid-July 2020 and share this corpus with the community. This resulted in 1 500 tweets relating to 1 274 false and 276 partially false claims, respectively. Exploratory analysis of author accounts revealed that the verified twitter handle(including Organisation/celebrity) are also involved in either creating (new tweets) or spreading (retweet) the misinformation. Additionally, we found that false claims propagate faster than partially false claims. Compare to a background corpus of COVID-19 tweets, tweets with misinformation are more often concerned with discrediting other information on social media. Authors use less tentative language and appear to be more driven by concerns of potential harm to others. Our results enable us to suggest gaps in the current scientific coverage of the topic as well as propose actions for authorities and social media users to counter misinformation.Comment: 20 pages, nine figures, four tables. Submitted for peer review, revision

Polarized fermions in the unitarity limit

We consider a polarized Fermi gas in the unitarity limit. Results are calculated analytically up to next-to-leading order in an expansion about d=4 spatial dimensions. We find a first order transition from superfluid to normal phase. The critical chemical potential asymmetry for this phase transition is delta_mu_c= 2/(mu epsilon)*(1-0.467\epsilon), where epsilon=4-d is the expansion parameter and 'mu' is the average chemical potential of the two fermion species. Stability of the superfluid phase in the presence of supercurrents is also studied.Comment: 5 pages, 5 figures, LaTeX2e; minor changes, note added at the end, to be published in PR

Solution of different multi-criteria decision making engineering problems by PROMETHEE II and VIKOR

In our day to day life we come across situations in which we have a number of choices available in front of us and it is difficult to choose among them on the basis of a single criterion. Different alternatives have different attributes related to them so it is important for the decision maker to weigh all the alternatives and come up with a common index on the basis of which he can compare his alternatives. Here in this thesis, to encounter with such problems, multi criteria decision making methods have been used to come up with the best alternative. Two methods namely PROMETHEE II (preference ranking organization method for enrichment evaluation) and VIKOR (višekriterijumsko kompromisno rangiranje) have been used to solve different engineering problems ranging from selection of machining parameters to choosing a supplier for an industry. PROMETHEE II uses the outranking method for the ranking of alternatives and VIKOR is a compromise solution method. Problems have been solved by both the methods and the results have been compared with each other