Unsupervised User Stance Detection on Twitter

We present a highly effective unsupervised framework for detecting the stance of prolific Twitter users with respect to controversial topics. In particular, we use dimensionality reduction to project users onto a low-dimensional space, followed by clustering, which allows us to find core users that are representative of the different stances. Our framework has three major advantages over pre-existing methods, which are based on supervised or semi-supervised classification. First, we do not require any prior labeling of users: instead, we create clusters, which are much easier to label manually afterwards, e.g., in a matter of seconds or minutes instead of hours. Second, there is no need for domain- or topic-level knowledge either to specify the relevant stances (labels) or to conduct the actual labeling. Third, our framework is robust in the face of data skewness, e.g., when some users or some stances have greater representation in the data. We experiment with different combinations of user similarity features, dataset sizes, dimensionality reduction methods, and clustering algorithms to ascertain the most effective and most computationally efficient combinations across three different datasets (in English and Turkish). We further verified our results on additional tweet sets covering six different controversial topics. Our best combination in terms of effectiveness and efficiency uses retweeted accounts as features, UMAP for dimensionality reduction, and Mean Shift for clustering, and yields a small number of high-quality user clusters, typically just 2--3, with more than 98\% purity. The resulting user clusters can be used to train downstream classifiers. Moreover, our framework is robust to variations in the hyper-parameter values and also with respect to random initialization

weSPOT: a cloud-based approach for personal and social inquiry

Scientific inquiry is at the core of the curricula of schools and universities across Europe. weSPOT is a new European initiative proposing a cloud-based approach for personal and social inquiry. weSPOT aims at enabling students to create their mashups out of cloud-based tools in order to perform scientific investigations. Students will also be able to share their inquiry accomplishments in social networks and receive feedback from the learning environment and their peers

ISIS2: Pixel Sensor with Local Charge Storage for ILC Vertex Detector

ISIS (In-situ Storage Imaging Sensor) is a novel CMOS sensor with multiple charge storage capability developed for the ILC vertex detector by the Linear Collider Flavour Identification (LCFI) collaboration. This paper reports test results for ISIS2, the second generation of ISIS sensors implemented in a 0.18 micron CMOS process. The local charge storage and charge transfer were unambiguously demonstrated.Comment: 11 pages, 16 figures, to be included in the Proceedings of International Linear Collider Workshop 201

weSPOT: A personal and social approach to inquiry-based learning

weSPOT is a new European initiative proposing a novel approach for personal and social inquiry-based learning in secondary and higher education. weSPOT aims at enabling students to create their mash-ups out of cloud based tools and services in order to perform scientific investigations. Students will also be able to share their inquiry accomplishments in social networks and receive feedback from the learning environment and their peers. This paper presents the research framework of the weSPOT project, as well as the initial inquiry-based learning scenarios that will be piloted by the project in real-life educational settings

Design and characterisation of the new CIS115 sensor for JANUS, the high resolution camera on JUICE

JUICE, the Jupiter Icy Moon Explorer, is a European Space Agency L-class mission destined for the Jovian system. Due for launch in 2022, it will begin a science phase after its transit to Jupiter that will include detailed investigations of three of the Galilean moons: Ganymede, Callisto and Europa. JUICE will carry payloads to characterise the Jovian environments, divided into in situ, geophysical and remote sensing packages. A key instrument in the remote sensing package is JANUS, an optical camera operating over a wavelength range of 350 nm to 1064 nm. JANUS will be used to study the external layers of Jupiter’s atmosphere, the ring system and the planetary bodies. To achieve the science goals, resolutions of better than 5 m per pixel are required for the highest resolution observations during the 200 km altitude orbit of Ganymede, whilst the system is operated with a signal to noise ratio of better than 100. Jupiter’s magnetic field is a dominant object in the solar system, trapping electrons and other charged particles leading to the radiation environment around Jupiter being very hostile, especially in the regions closest to Jupiter in the Ganymede orbit. The radiation tolerance of the focal plane detector in JANUS is therefore a major concern and radiation testing is vital to confirm its expected performance after irradiation will meet requirements set by the science goals. JANUS will be using a detector from e2v technologies plc, the CMOS Imaging Sensor 115 (CIS115), which is a device manufactured using 0.18 μm Imaging CMOS Process with a 2000 by 1504 pixel array each 7 μm square. The pixels have a 4T pinned photodiode pixel architecture, and the array is read out through four differential analogue outputs. This paper describes the preliminary characterisation of the CIS115, and results obtained with the CIS107 precursor sensor

weSPOT: A Cloud-based Approach for Personal and Social Inquiry

Scientific inquiry is at the core of the curricula of schools and universities across Europe. weSPOT is a new European initiative proposing a cloud-based approach for personal and social inquiry. weSPOT aims at enabling students to create their mashups out of cloud-based tools in order to perform scientific investigations. Students will also be able to share their inquiry accomplishments in social networks and receive feedback from the learning environment and their peers.published in: Sun SITE Central Europe, 2012, pp. 7-11, Ref: http://ceur-ws.org/Vol-945/The research leading to these results has received funding from the European Community’ s Seventh Framework Programme (FP7/2007-2013) under grant agreement N° 318499-weSPOT project

weSPOT: Inquiry based learning meets learning analytics

weSPOT, a project supported by the European Commission, addresses several challenges to building personal knowledge, specifically in the area of science. It focuses on inquiry-based learning, in which the learner takes the role of a self-motivated explorer, and provides support for building these skills. The main problem areas weSPOT tackles are the general lack of inquiry skills in students from ages 12 to 25, the dearth of technological support to bolster students’ curiosity, linking everyday world experiences to the classroom, streamlining e-learning with inquiry-based approaches, and measuring the impact of inquiry projects. weSPOT’s main objectives are: (a) defining a reference model for inquiry-based learning skills, (b) creating a diagnostic instrument for measuring inquiry skills, and (c) implementing a working environment that allows the easy linking of inquiry activities with school curricula and legacy systems

Searchable Encryption with Access Control

Outsourcing data to the cloud is becoming increasingly prevalent. To ensure data confidentiality, encrypting the data before outsourcing it is advised. While encryption protects the secrets in the data, it also prevents operations on the data. For example in a multi-user setting, data is often accessed via search, but encryption prevents search. Searchable encryption solves this dilemma. However, in a multi-user setting not all users may be allowed to access all data, requiring some means of access control. We address the question how searchable encryption and access control can be combined. Combining these technologies is required to achieve strong notions of confidentiality: if a ciphertext occurs as a search result, we learn something about the underlying document, even if access control does not let us access the document. This illustrates a need to link search and access control, so that search results presented to users only feature data the users are allowed to access. Our searchable encryption scheme with access control establishes that link