Concept Drift and Adaptation for Emotion Detection in Twitter

The classification task in dynamical environments is challenging. A reason for this is the change of their statistical properties over time. This characteristic is called concept drift and is one of the major topics in data mining. The objective of this thesis is to analyze, how accurate different systems are classifying in dynamical environments over a period of time. For this purpose, two different approaches are evaluated. One approach removes the features with the highest change in influence. The other is an ensemble based model which let experts vote between the outcomes. Although the models were not able to increase the accuracy after a long period of time, the results show that both models are able to achieve a higher accuracy than the baseline in particular cases. This outcome underlines that emotion detection in Twitter can be improved. New models or improvements to existing ones could be able to handle concept drift to achieve a higher accuracy

Group Effort: Study Group Matching Service

Poster Presentation, Judge\u27s Winner (2016)https://digitalcommons.wpi.edu/gps-posters/1528/thumbnail.jp

Ordinos: A Verifiable Tally-Hiding E-Voting System

Modern electronic voting systems (e-voting systems) are designed to provide not only vote privacy but also (end-to-end) verifiability. Several verifiable e-voting systems have been proposed in the literature, with Helios being one of the most prominent ones. Almost all such systems, however, reveal not just the voting result but also the full tally, consisting of the exact number of votes per candidate or even all single votes. There are several situations where this is undesirable. For example, in elections with only a few voters (e.g., boardroom or jury votings), revealing the complete tally leads to a low privacy level, possibly deterring voters from voting for their actual preference. In other cases, revealing the complete tally might unnecessarily embarrass some candidates. Often, the voting result merely consists of a single winner or a ranking of candidates, so revealing only this information but not the complete tally is sufficient. This property is called tally-hiding and it offers completely new options for e-voting. In this paper, we propose the first provably secure end-to-end verifiable tally-hiding e-voting system, called Ordinos. We instantiated our system with suitable cryptographic primitives, including an MPC protocol for greater-than tests, implemented the system, and evaluated its performance, demonstrating its practicality. Moreover, our work provides a deeper understanding of tally-hiding in general, in particular in how far tally-hiding affects the levels of privacy and verifiability of e-voting systems

Extending the Tally-Hiding Ordinos System: Implementations for Borda, Hare-Niemeyer, Condorcet, and Instant-Runoff Voting

Modern electronic voting systems (e-voting systems) are designed to achieve a variety of security properties, such as verifiability, accountability, and vote privacy. Some of these systems aim at so-called tally-hiding: they compute the election result, according to some result function, like the winner of the election, without revealing any other information to any party. In particular, if desired, they neither reveal the full tally consisting of all (aggregated or even individual) votes nor parts of it, except for the election result, according to the result function. Tally-hiding systems offer many attractive features, such as strong privacy guarantees both for voters and for candidates, and protection against Italian attacks. The Ordinos system is a recent provably secure framework for accountable tally-hiding e-voting that extends Helios and can be instantiated for various election methods and election result functions. So far, practical instantiations and implementations for only rather simple result functions (e.g., computing the $k$ best candidates) and single/multi-vote elections have been developed for Ordinos. In this paper, we propose and implement several new Ordinos instantiations in order to support Borda voting, the Hare-Niemeyer method for proportional representation, multiple Condorcet methods, and Instant-Runoff Voting. Our instantiations, which are based on suitable secure multi-party computation (MPC) components, offer the first tally-hiding implementations for these voting methods. To evaluate the practicality of our MPC components and the resulting e-voting systems, we provide extensive benchmarks for all our implementations

Kryvos: Publicly Tally-Hiding Verifiable E-Voting

Elections are an important corner stone of democratic processes. In addition to publishing the final result (e.g., the overall winner), elections typically publish the full tally consisting of all (aggregated) individual votes. This causes several issues, including loss of privacy for both voters and election candidates as well as so-called Italian attacks that allow for easily coercing voters. Several e-voting systems have been proposed to address these issues by hiding (parts of) the tally. This property is called tally-hiding. Existing tally-hiding e-voting systems in the literature aim at hiding (part of) the tally from everyone, including voting authorities, while at the same time offering verifiability, an important and standard feature of modern e-voting systems which allows voters and external observers to check that the published election result indeed corresponds to how voters actually voted. In contrast, real elections often follow a different common practice for hiding the tally: the voting authorities internally compute (and learn) the full tally but publish only the final result (e.g., the winner). This practice, which we coin publicly tally-hiding, indeed solves the aforementioned issues for the public, but currently has to sacrifice verifiability due to a lack of practical systems. In this paper, we close this gap. We formalize the common notion of publicly tally-hiding and propose the first provably secure verifiable e-voting system, called Kryvos, which directly targets publicly tally-hiding elections. We instantiate our system for a wide range of both simple and complex voting methods and various result functions. We provide an extensive evaluation which shows that Kryvos is practical and able to handle a large number of candidates, complex voting methods and result functions. Altogether, Kryvos shows that the concept of publicly tally-hiding offers a new trade-off between privacy and efficiency that is different from all previous tally-hiding systems and which allows for a radically new protocol design resulting in a practical e-voting system

Non-interactive zero-knowledge proofs of knowledge based on Fiat-Shamir transformation

Sigma-Protokolle sind sehr effiziente Beweise von Wissen. Leider weisen sie nur die Special Honest Verifier Zero-Knowledge Eigenschaft auf, welche schwächer als die Zero-Knowledge Eigenschaft ist. Das liegt daran, dass bei Honest Verifier Zero-Knowledge nur für ehrliche Verifizierer ein Simulator existieren muss, während bei Zero-Knowledge auch für bösartige Verifizierer, das sind Verifizierer, die sich möglicherweise nicht an das Protokoll halten, eine erfolgreiche Simulationen verlangt werden. Eine Möglichkeit, Sigma-Protokolle in Zero-Knowledge Protokolle umzuwandeln, besteht in der Fiat-Shamir Transformation. Dabei entsteht nicht nur ein Zero-Knowledge Beweis von Wissen, sondern auch ein nicht-interaktives Beweissystem. Die Idee der Fiat-Shamir Transformation besteht darin, dass der Beweiser die Challenge mittels einer Hashfunktion aus dem gemeinsamen Eingabewort und dem Commitment berechnet. Trotz der aktiven Verwendung der Fiat-Shamir Transformation in der Praxis wurde erst 2012 in Arbeiten von Bernhard, Pereira und Warinschi sowie Faust, Kohlweiss, Marson, und Venturi der Versuch eines Beweises der Korrektheit erbracht. Der Beweis der ersten Arbeit wird in dieser Masterarbeit ausformuliert

Interspecific patterns for egg and clutch sizes of African Bufonidae (Amphibia: Anura)

Little is known about reproductive trade-offs in African amphibians, but such data, particularly in the form of quantitative measurements, are a key for investigating life history evolution. Here we compile and analyze known data on African bufonids from published material and new data from preserved museum specimens, to investigate interspecific patterns of egg and clutch sizes variation. Our data is a composite of mixed sources, including ova data from dissected females and laid clutches from observations in the field. Our study shows that, as body size increases, clutch size increases but egg size decreases, and when correcting for body size, egg size is inversely correlated with clutch size. These parameter interactions however, are different for different reproductive modes. In free-swimming larval developing species, the same trends are recovered, but for lecithotrophic viviparous species no significant correlations could be recovered for clutch size and body size nor for the trade-off between clutch size and egg size, and egg size is positively related to body size. The egg size of Nimbaphrynoides occidentalis (Angel, 1943) is a clear outlier, which may be due to its matrotrophic viviparous reproduction. In addition, we observed no statistical difference between ova data collected from dissections and laid clutch data from field observations, which suggests that such a mixed dataset has utility in comparative analyses

Terrestrial reproduction as an adaptation to steep terrain in African toads

How evolutionary novelties evolve is a major question in evolutionary biology. It is widely accepted that changes in environmental conditions shift the position of selective optima, and advancements in phylogenetic comparative approaches allow the rigorous testing of such correlated transitions. A longstanding question in vertebrate biology has been the evolution of terrestrial life histories in amphibians and here, by investigating African bufonids, we test whether terrestrial modes of reproduction have evolved as adaptations to particular abiotic habitat parameters. We reconstruct and date the most complete species-level molecular phylogeny and estimate ancestral states for reproductive modes. By correlating continuous habitat measurements from remote sensing data and locality records with life-history transitions, we discover that terrestrial modes of reproduction, including viviparity evolved multiple times in this group, most often directly from fully aquatic modes. Terrestrial modes of reproduction are strongly correlated with steep terrain and low availability of accumulated water sources. Evolutionary transitions to terrestrial modes of reproduction occurred synchronously with or after transitions in habitat, and we, therefore, interpret terrestrial breeding as an adaptation to these abiotic conditions, rather than an exaptation that facilitated the colonization of montane habitats.Swiss National Science Fund (grant no. 31003A-133067 awarded to S.P.L. and P2BSP3_158846 to H.C.L.); Freiwillige Akademische Gesellschaft Basel; National Geographic Expedition Grant (CRE Grant #8532-08); Swiss Academy of Science (SCNAT); German Science Foundation (MU2914/2-1); Percy Sladen Memorial Fund (to D.J.G.)

Data from: Terrestrial reproduction as an adaptation to steep terrain in African toads

How evolutionary novelties evolve is a major question in evolutionary biology. It is widely accepted that changes in environmental conditions shift the position of selective optima, and advancements in phylogenetic comparative approaches allow the rigorous testing of such correlated transitions. A longstanding question in vertebrate biology has been the evolution of terrestrial life histories in amphibians and here, by investigating African bufonids, we test whether terrestrial modes of reproduction have evolved as adaptations to particular abiotic habitat parameters. We reconstruct and date the most complete species-level molecular phylogeny and estimate ancestral states for reproductive modes. By correlating continuous habitat measurements from remote sensing data and locality records with life-history transitions, we discover that terrestrial modes of reproduction, including viviparity evolved multiple times in this group, most often directly from fully aquatic modes. Terrestrial modes of reproduction are strongly correlated with steep terrain and low availability of accumulated water sources. Evolutionary transitions to terrestrial modes of reproduction occurred synchronously with or after transitions in habitat, and we, therefore, interpret terrestrial breeding as an adaptation to these abiotic conditions, rather than an exaptation that facilitated the colonization of montane habitats

Literature sources of locality records from Terrestrial reproduction as an adaptation to steep terrain in African toads

Publications used for extracting additional, non-digitized locality records of African Bufonida