Energy balance of cosmic rays

Energy dissipation channels of cosmic rays in galaxy and metagalax

Amobee at IEST 2018: Transfer Learning from Language Models

This paper describes the system developed at Amobee for the WASSA 2018 implicit emotions shared task (IEST). The goal of this task was to predict the emotion expressed by missing words in tweets without an explicit mention of those words. We developed an ensemble system consisting of language models together with LSTM-based networks containing a CNN attention mechanism. Our approach represents a novel use of language models (specifically trained on a large Twitter dataset) to predict and classify emotions. Our system reached 1st place with a macro $\text{F}_1$ score of 0.7145.Comment: 7 pages, accepted to the 9th WASSA Workshop, part of the EMNLP 2018 Conference; added links to open-source materia

Nancy ´77: año del desengaño

Nancy ´77: año del desengañ

Caracas, Tercer Festival Internacional de Teatro

Caracas, Tercer Festival Internacional de Teatr

Essays on exchange-traded funds

This thesis investigates the consequences of exchange-traded fund industry growth. In particular, I study the ETF arbitrage mechanism, the impact of ETF trading on international diversification and on price efficiency of distressed stocks. In the first chapter, I show that, although low on average, ETF premiums/ discounts can be as high as 16% when considering international country-level ETFs. I propose a risk-based limits to arbitrage explanation of such deviations. I show that while currency and equity illiquidity risks are important in explaining ETF premiums there is still a large portion of premium that remains unexplained. I argue that ETF premiums represent a reward arbitrageurs demand for being exposed to financial frictions risk and show that the absolute value of ETF deviations is a good proxy for multiple dimensions of financial frictions such as funding illiquidity, credit risk and information uncertainty. I show that it can be used as an aggregate financial friction proxy at the country-level and that it is priced in the cross-section of stock returns internationally. In the second chapter, I show that investment decisions of ETF market participants when trading country ETFs are driven by shocks to U.S. fundamentals, rather than local risks. Investors react only to negative news about local economies. When U.S. economic uncertainty increases, investors switch to Cash ETFs. I demonstrate that ETF arbitrage mechanism is one of the key channels through which U.S. shocks propagate to local economies leading to increased return correlation with the U.S. market, limiting the benefits from international diversification. I find that countries with stronger ETF price discovery and lower limits to arbitrage have a higher comovement with the U.S. market. In the third chapter, I examine the effect of exchange traded funds on the underlying stocks conditional on the credit quality of securities in the basket. I show that U.S. industry ETFs help to alleviate the short-selling constraint present for distressed securities at the individual stock level by providing the alternative trading route to gain the negative exposure via cheap short-selling of ETFs. As a result, ETF basket membership has a positive effect on distressed stocks price efficiency. In addition, I show that distressed stocks that are members of ETF basket do not show signs of distress anomaly unlike the non-member securities

Metropolitan revenue sources: the Nairobi case

The paper discusses briefly the reasons for budgetary plight which faces most large cities and particularly those in the developing countries. The case of Nairobi, a primary city subject to many of the forces discussed above, is then examined in some detail and a forecast given of its fiscal outlook by 1985. The almost inevitable gap between revenues and expenditures is, in the case of Nairobi, seriously deepened by the recent abolition of the Graduated Personal Tax, a major revenue source of the city. Various methods of coping with the fiscal crisis are then discussed anda substitute tax measure suggested, designed not only to replace the lost GPT revenues but to improve the efficiency of the city's revenue structure. The suggested measure proposes the imposition of a municipal surcharge on the national income tax liability of Nairobi residents. Albeit tentatively, the paper examines the various economic and administrative aspects of the surcharge

Amobee at SemEval-2018 Task 1: GRU Neural Network with a CNN Attention Mechanism for Sentiment Classification

This paper describes the participation of Amobee in the shared sentiment analysis task at SemEval 2018. We participated in all the English sub-tasks and the Spanish valence tasks. Our system consists of three parts: training task-specific word embeddings, training a model consisting of gated-recurrent-units (GRU) with a convolution neural network (CNN) attention mechanism and training stacking-based ensembles for each of the sub-tasks. Our algorithm reached 3rd and 1st places in the valence ordinal classification sub-tasks in English and Spanish, respectively.Comment: 8 pages, accepted to the 12th International Workshop on Semantic Evaluation 201

Biofilm Formation as a Pathogenicity Factor of Medically Important Fungi

To cause disease, the infectious agent makes use of both invasiveness factors—the pathogen virulence factors—and the ability to resist and evade the host immune system. The success of the infection process is the result of a complex equation involving pathogen interaction with the host, wherein the expression of several virulence factors (and not just one or the other) will favor the establishment of the pathogen in the host. Fungal pathogens are frequently associated with biofilm formation