1,930 research outputs found
Semantic Variation in Online Communities of Practice
We introduce a framework for quantifying semantic variation of common words
in Communities of Practice and in sets of topic-related communities. We show
that while some meaning shifts are shared across related communities, others
are community-specific, and therefore independent from the discussed topic. We
propose such findings as evidence in favour of sociolinguistic theories of
socially-driven semantic variation. Results are evaluated using an independent
language modelling task. Furthermore, we investigate extralinguistic features
and show that factors such as prominence and dissemination of words are related
to semantic variation.Comment: 13 pages, Proceedings of the 12th International Conference on
Computational Semantics (IWCS 2017
Analysing Lexical Semantic Change with Contextualised Word Representations
This paper presents the first unsupervised approach to lexical semantic
change that makes use of contextualised word representations. We propose a
novel method that exploits the BERT neural language model to obtain
representations of word usages, clusters these representations into usage
types, and measures change along time with three proposed metrics. We create a
new evaluation dataset and show that the model representations and the detected
semantic shifts are positively correlated with human judgements. Our extensive
qualitative analysis demonstrates that our method captures a variety of
synchronic and diachronic linguistic phenomena. We expect our work to inspire
further research in this direction.Comment: To appear in Proceedings of the 58th Annual Meeting of the
Association for Computational Linguistics (ACL-2020
Photoelectrocatalytic performances of nanostructured/decorated TiO 2 electrodes: Effect of wavelength and cell configuration
The behaviour of TiO2 based electrodes was investigated during the photoelectrocatalytic water splitting process. TiO2 nanotubes and compact oxide structures were obtained by electrochemical oxidation of Ti foils. A subsequent hydrothermal process carried out at both the nanotubular and compact oxide structures allowed decorating the structure by TiO2 nanoparticles. The synthesized TiO2 samples worked as photoanodes both in a bulk three electrode cell and in a thin gap cell. The results from measurements of the photocurrent and from electrochemical impedance spectroscopy were used to highlight a combined effect of the wavelength of the incident light and the kind of cell configuration, on the global performance of the systems. The results indicate that the decoration process does not result only in a simple increase of the specific surface, but it also determines a different concentration of the bulk and superficial sites in the electrode. The different response of the sites at different wavelengths, along with the accessibility of the electrolyte to the porous structure are evocated to justify the experimental behaviour observed
Pathologische Veränderungen bei sporadischem Morbus Parkinson : induziert ein neurotropes Pathogen die Erkrankung?
Der Morbus Parkinson tritt in der Regel sporadisch auf und ist nach dem Morbus Alzheimer die häufigste degenerative Erkrankung des menschlichen Nervensystems. Sie ist bei nicht-menschlichen Wirbeltieren unbekannt und befällt außer dem Nervensystem keine anderen Organe. Wie bei vielen anderen Krankheiten auch erkennt der Kliniker nur die späten und bereits Symptome verursachenden Stadien des Morbus Parkinson. Spezielle Fehlfunktionen der Motorik, wie Hypokinese, Rigor, Ruhetremor weisen zwar auf die Erkrankung hin, können jedoch unter dem Bild eines »Parkinsonismus« auch bei anderen Krankheiten auftreten. Kennzeichnend dagegen ist ein eigenartiger pathologischer Prozess, der sich durch die Entwicklung von Einschlusskörpern in Nervenzellen auszeichnet. Der Prozess beschränkt sich auf wenige empfängliche Nervenzelltypen im zentralen, peripheren und enterischen Nervensystem. Die Einschlusskörper entwickeln sich nicht spontan und erscheinen auch nicht regelmäßig im Verlauf der Alterung des Nervensystems, selbst bei über Hundertjährigen nicht. Man hat also Grund, sie als pathologische Bildungen zu betrachten, auch wenn sie anfänglich in nur geringer Dichte im Nervengewebe auftreten. Die frühen symptomfreien Stadien der Krankheit lassen sich erst nach dem Tod der Patienten nachweisen. Wesentliche Kriterien für die Stellung einer postmortalen Diagnose sind die Einschlusskörper. Wie sie sich entwickeln und in den verschiedenen Stadien der Krankheit im Nervensystem ausbreiten, beschreiben Prof. Dr. Heiko Braak und Dr. Dr. Kelly Del Tredici
The Road to Success: Assessing the Fate of Linguistic Innovations in Online Communities
We investigate the birth and diffusion of lexical innovations in a large
dataset of online social communities. We build on sociolinguistic theories and
focus on the relation between the spread of a novel term and the social role of
the individuals who use it, uncovering characteristics of innovators and
adopters. Finally, we perform a prediction task that allows us to anticipate
whether an innovation will successfully spread within a community.Comment: 13 pages, Proceedings of the 27th International Conference on
Computational Linguistics (COLING 2018
Words are the Window to the Soul: Language-based User Representations for Fake News Detection
Cognitive and social traits of individuals are reflected in language use.
Moreover, individuals who are prone to spread fake news online often share
common traits. Building on these ideas, we introduce a model that creates
representations of individuals on social media based only on the language they
produce, and use them to detect fake news. We show that language-based user
representations are beneficial for this task. We also present an extended
analysis of the language of fake news spreaders, showing that its main features
are mostly domain independent and consistent across two English datasets.
Finally, we exploit the relation between language use and connections in the
social graph to assess the presence of the Echo Chamber effect in our data.Comment: 9 pages, accepted at COLING 202
Nannochloropsis oceanica cultivation in pilot-scale raceway ponds—from design to cultivation
Raceways ponds are the microalgal production systems most commonly used at industrial
scale. In this work, two di erent raceway configurations were tested under the same processing
conditions to compare their performance on the production of Nannochloropsis oceanica. Biomass
productivity, biochemical composition of the produced biomass, and power requirements to operate
those reactors were evaluated. Water depths of 0.20 and 0.13 m, and culture circulation velocities
of 0.30 and 0.15 m s1 were tested. A standard configuration, which had a full channel width
paddlewheel, proved to be the most energy e cient, consuming less than half of the energy required
by a modified configuration (had a half channel width paddlewheel). The later showed to have
slightly higher productivity, not enough to o set the large di erence in energetic consumption. Higher
flow velocity (0.30 m s1) led to a 1.7 g m2 d1 improvement of biomass productivity of the system,
but it increased the energy consumption twice as compared to the 0.15 m s1 flow velocity. The latter
velocity showed to be the most productive in lipids. A water depth of 0.20 m was the most suitable
option tested to cultivate microalgae, since it allowed a 54% energy saving. Therefore, a standard
raceway pond using a flow velocity of 0.3 m s1 with a 0.20 m water depth was the most e cient
system for microalgal cultivation. Conversely, a flow velocity of 0.15 m s1 was the most suitable to
produce lipids.Portugal 2020 Program (POCI-01-0247-FEDER-035234; LISBOA-01-0247-FEDER-035234; ALG-01-0247-FEDER-035234)info:eu-repo/semantics/publishedVersio
- …