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Die Schriften zur Kultur- und Mediensemiotik | Online sind ein Open Access Journal des Virtuellen Zentrums für kultursemiotische Forschung / Virtual Centre for Cultural Semiotics (www.kultursemiotik.com). Ausgabe 7 beleuchtet unterschiedliche Potenziale der Semiotik in der Lehrer*innenbildung, die aus theoretischer Perspektive aufgezeigt oder anhand von Konzepten aus der Praxis mit theoretischer/empirischer Fundierung untersucht werden. Beides findet aus fachlicher, überfachlicher, inter- oder transdisziplinärer Perspektive statt.
Die Arbeit besteht aus drei empirischen Studien, die als übergeordnete Forschungsfragen untersuchen sollten, welche signifikanten Prädiktoren das subjektive Wohlbefinden bei Studierenden beeinflussen können und zum anderen klären sollte, ob das subjektive Wohlbefinden in einem Zusammenhang mit der Studienabbruchsintention steht. Jede Studie baute auf den Hauptprädiktoren Persönlichkeit, Selbstkonzept und soziale Integration auf und hatte zugleich noch einen spezifischen Aspekt, der sich von Studie zu Studie änderte. In der ersten Studie wurde als zusätzliche Variable der Identitätsstatus betrachtet. An dieser Erhebung nahmen Studierende ab dem zweiten Semester teil und sie wurde im Querschnitt durchgeführt. Die zentralen Ergebnisse waren hinsichtlich des subjektiven Wohlbefindens die Bedeutung von Neurotizismus, Extraversion, dem Selbstkonzept der allgemeinen Problemlösung und die deutlich unterschiedlichen Ergebnisse zwischen Frauen und Männern. So hatte bei den Studentinnen vor allem Neurotizismus einen Einfluss und bei Männern hingegen die Extraversion. Hinsichtlich der Studienabbruchsintention zeigte sich ein vollständiger Mediatoreffekt zwischen der sozialen Eingebundenheit und der Studienabbruchsintention mit dem subjektiven Wohlbefinden als Mediator. Im Pfadmodell zeigte sich allerdings kein signifikanter Zusammenhang zwischen dem subjektiven Wohlbefinden und der Studienabbruchsintention. In der zweiten Studie lag der Fokus auf Studierenden im ersten Semester in einer Längsschnittuntersuchung und spezifizierte sich auf Aspekte der Motivation, die allerdings keine Zusammenhänge zeigten. Auch hier gab es einen vollständigen Mediatoreffekt des subjektiven Wohlbefindens hinsichtlich des Regressionspfades zwischen sozialer Integration und Studienabbruchsintention. Die dritte Studie legte den Schwerpunkt auf die Bedeutung der Grundbedürfnisse nach Deci & Ryan (2000) und die Emotionsregulationsstrategien Neubewertung und Unterdrückung. Die Teilnehmenden waren Studierende ab dem zweiten Semester, die im Längsschnitt befragt wurden. Beim ersten Messzeitpunkt während des Semesters waren das Autonomieerleben, Neurotizismus und das Selbstkonzept der allgemeinen Problemlösung signifikante Prädiktoren des subjektiven Wohlbefindens, beim zweiten Messzeitpunkt war der einzige, signifikante Prädiktor im Pfadmodell die Persönlichkeitsdimension Verträglichkeit. Zwischen dem subjektiven Wohlbefinden und der Studienabbruchsintention zeigte sich ein signifikanter Zusammenhang.
Innovate with Crowds. Co-Creation and Idea Evaluation in Internal and External Crowdsourcing.
(2020)
Crowdsourcing seems to be a promising approach for organizations to overcome challenges widely discussed in innovation and organizational research. However, the extent to which an organization can leverage the benefits from crowdsourcing is contingent on which type of crowd is addressed and how crowds are used. Based on unique data from crowdsourcing contests, the dissertation provides insights how to innovate with internal and external crowds in order to utilize their potential for co-creation and idea evaluation.
Southeast Asia is one of the most dynamic regions in the world. This volume offers a timely approach to Southeast Asian Studies, covering recent transitions in the realms of urbanism, rural development, politics, and media. While most of the contributions deal with the era of post-independence, some tackle the colonial period and the resulting developments. The volume also includes insights from Southern India.
As a tribute to the interdisciplinary project of Southeast Asian Studies, this book brings together authors from disciplines as diverse as area studies, sociology, history, geography, and journalism.
Research on flipped classroom instruction has substantially advanced in the past ten years. Flipped classroom refers to an instructional approach in which students study educational videos at home and do homework assignments in class. Since an increasing number of teachers wants to adopt the flipped classroom approach in their practice, further research—particularly in the context of secondary education—is clearly required. The two presented studies in this thesis aimed at examining the effectiveness of flipped classroom instruction in secondary education by conducting a meta-analytic synthesis of prior studies and an intervention study with a methodologically new approach. Specifically, the studies investigated whether and under which conditions the flipped classroom approach has a positive impact on student achievement and which learners benefit most from a flipped or video-based classroom.
In the first study, meta-analytic methods were used to examine whether the flipped classroom approach, after controlling for sampling error, positively effects student achievement in secondary education. Effect sizes were calculated for the research designs pre-test-post-test (Time), post-test only (PostOnly) and pre-test-post-test with control group (Treatment). Moreover, the impact of four moderator variables as boundary conditions of flipped classroom effectiveness was estimated: disciplinary field, length of the intervention, use of a quiz and use of a learning management system. The meta-analytical findings for the effect size Treatment confirmed the effectiveness of flipped classroom on student achievement in comparison to traditional instruction (Cohen’s d = 0.42). Moderator analyses on the effect size Time showed stronger effects for subjects in the STEM area (science, technology, engineering, mathematics) than for foreign languages and humanities. The effect sizes were also higher for shorter intervention studies than for longer ones and if quiz at home had been left out. Moderator analyses on the effect sizes PostOnly and Treatment made clear that the effect sizes for intervention studies without a learning management system were higher than with a learning management system.
The second study aimed to compare flipped classroom with other forms of video-based instruction and determine which types of students benefit most from video-based instruction. Thirty-eight school classes with 848 ninth-grade students took part in a quasi-experimental pre-post-test intervention study over the course of four weeks. Two independent variables were completely crossed resulting in four experimental conditions: video (at home vs. in class) and instructional method (student-centred vs. teacher-centred). Multilevel analyses revealed that all four experimental conditions were equally effective in promoting students’ learning gains. At-risk, average and excellent students profited least from video-based instruction. Confident and independent students had the highest learning gains from pre- to post-test. The study constitutes a first step towards a comprehensive evaluation of flipped classroom by using a better-controlled research design and may contribute to a more objective discussion about the positive effects of flipped classroom.
Cryptography is the scientific study of techniques for securing information and communication against adversaries. It is about designing and analyzing encryption schemes and protocols that protect data from unauthorized reading. However, in our modern information-driven society with highly complex and interconnected information systems, encryption alone is no longer enough as it makes the data unintelligible, preventing any meaningful computation without decryption. On the one hand, data owners want to maintain control over their sensitive data. On the other hand, there is a high business incentive for collaborating with an untrusted external party.
Modern cryptography encompasses different techniques, such as secure multiparty computation, homomorphic encryption or order-preserving encryption, that enable cloud users to encrypt their data before outsourcing it to the cloud while still being able to process and search on the outsourced and encrypted data without decrypting it. In this thesis, we rely on these cryptographic techniques for computing on encrypted data to propose efficient multiparty protocols for order-preserving encryption, decision tree evaluation and kth-ranked element computation.
We start with Order-preserving encryption (OPE) which allows encrypting data, while still enabling efficient range queries on the encrypted data. However, OPE is symmetric limiting, the use case to one client and one server. Imagine a scenario where a Data Owner (DO) outsources encrypted data to the Cloud Service Provider (CSP) and a Data Analyst (DA) wants to execute private range queries on this data. Then either the DO must reveal its encryption key or the DA must reveal the private queries. We overcome this limitation by allowing the equivalent of a public-key OPE.
Decision trees are common and very popular classifiers because they are explainable. The problem of evaluating a private decision tree on private data consists of a server holding a private decision tree and a client holding a private attribute vector. The goal is to classify the client’s input using the server’s model such that the client learns only the result of the classification, and the server learns nothing. In a first approach, we represent the tree as an array and execute only d interactive comparisons (instead of 2 d as in existing solutions), where d denotes the depth of the tree. In a second approach, we delegate the complete tree evaluation to the server using somewhat or fully homomorphic encryption where the ciphertexts are encrypted under the client’s public key.
A generalization of a decision tree is a random forest that consists of many decision trees. A classification with a random forest evaluates each decision tree in the forest and outputs the classification label which occurs most often. Hence, the classification labels are ranked by their number of occurrences and the final result is the best ranked one. The best ranked element is a special case of the kth-ranked element. In this thesis, we consider the secure computation of the kth-ranked element in a distributed setting with applications in benchmarking and auctions. We propose different approaches for privately computing the kth-ranked element in a star network, using either garbled circuits or threshold homomorphic encryption.
Main memory forensics and its special form, virtual machine introspection (VMI), are powerful tools for digital forensics and can be used to improve the security of computer-based systems. However, their use in production systems is often not possible. This work identifies the causes and offers practical solutions to apply these techniques in cloud computing and on mobile devices to improve digital forensics and incident analysis.
Four key challenges must be tackled. The first challenge is that many existing solutions are not reproducible, for example, because the corresponding software components are not available, obsolete or incompatible. The use of these tools is also often complex and can lead to a crash of the system to be monitored in case of incorrect use. To solve this problem, this thesis describes the design and implementation of Libvmtrace, which is a framework for the introspection of Linux-based virtual machines. The focus of the developed design is to implement frequently used methods in encapsulated modules so that they are easy for developers to use, optimize and test.
The second challenge is that many production systems do not provide an interface for main memory forensics and virtual machine introspection. To address this problem, this thesis describes possible solutions for how such an interface can be implemented on mobile devices and in cloud environments designed to protect main memory from unprivileged access. We discuss how cold boot attacks, the ARM TrustZone and the hypervisor of cloud servers can be used to acquire data from storage.
The third challenge is how to reconstruct information from main memory efficiently. This thesis describes how these questions can be solved by employing two practical examples. The first example involves extracting the keys of encrypted TLS connections from the main memory of applications to decrypt network traffic without affecting the performance of the monitored application. The TLSKex and DroidKex architecture describe two approaches to localize the keys efficiently with the help of semantic knowledge in the main memory of applications. The second example discusses how to monitor and document SSH sessions of potential attackers from outside of a virtual machine. It is important that the monitoring routines are not noticed by an attacker. To achieve this, we evaluate how to optimize the performance of the monitoring mechanism.
The fourth challenge is how to deal with the performance degradation caused by introspection in productive systems. This thesis discusses how this can be achieved using the example of a SIEM system. To reduce the performance overhead, we describe how to configure the monitoring routine to collect only the information needed to detect incidents. Also, we describe two approaches that permit the monitoring routine to be dynamically adjusted at runtime to extract more information if necessary so that incidents can be better analyzed.
This study explores the integration of data journalism within three European legacy news organisations through the lens of organisational structure and professional culture. Interviews with data journalists and editors suggest that professional routines resonate with established data journalism epistemologies, values, and norms that appear to be constitutional for an inter-organisational data journalism subculture. At the same time, organisational structure either integrates the journalistic subculture by increasing levels of complexity, formalisation, and centralisation or rejects it by not accommodating it structurally or culturally. The three data teams work along epistemologies of computer-assisted reporting, investigative journalism, and data journalism but differentiate themselves through nuanced understandings of data journalism practice, driven by individual journalists. After a structureless episode, one team sets itself apart as it diverges from data-driven routines and orients itself towards technological and interdisciplinary interactive journalism. The findings show an interdependence of individual efforts, varying conceptualisations of data journalism practice, and interplay between organisational structure and professional culture.
Datenjournalismus: Eine Dekonstruktion aus feldtheoretischer und techniksoziologischer Perspektive
(2020)
Das Ziel der vorliegenden Arbeit ist es, mittels dreier Publikationen Forschungslücken punktuell zu schließen, mit der Absicht, zu einer vertieften Beschreibung des Datenjournalismus und zur Theoriebildung beizutragen. Das Konterkarieren mit einschlägigen Studien und die Einordung der Befunde der Publikationen mithilfe Bourdieus (1976) Habitus-Feld-Theorie sowie der Akteur-Netzwerk Theorie (Latour, 2005) als Detailperspektive zielen darauf ab, Erklärungs- und Beschreibungsansätze zu liefern, um mögliche Implikationen für das journalistische Feld darzustellen.
Diese Beobachtungen möchte ich zum Ausgangspunkt nehmen, die im Tristan-Roman verhandelten Zeichenkomplexe unter dem Gesichtspunkt einer Semiose des Mehrdeutigen näher zu beleuchten. Zunächst rücke ich dafür die epistemologische Figur der "Spur" in den Fokus, um dann in einem zweiten Schritt deren semiotische Funktionalisierung anhand exemplarischer Szenen der Manipulation, des Erkennens und Verkennens herauszuarbeiten. Die auf diese Weise nachgezeichnete innertextuelle Semiose soll anschließend didaktisch für detektivische Zugänge zu mittelalterlicher Literatur produktiv gemacht werden, wobei ein besonderer Akzent auf dem medialen Transfer und dem Einsatz digitalisierter Handschriften aus dem Mittelalter liegen wird.