Constitutional metaphors: Facebook’s “supreme court” and the legitimation of platform governance

Who governs—and who should govern—online communication? Social media companies, international organizations, users, or the state? And by what means? A range of rhetorical devices have been used to simplify the complexities associated with the governance of online platforms. This includes “constitutional metaphors”: metaphorical allusions to traditional political concepts such as statehood, democracy, and constitutionalism. Here, we empirically trace the ascent of a powerful constitutional metaphor currently employed in the news media discourse on platform governance: characterizations of Facebook’s Oversight Board (OB) as a “supreme court.” We investigate the metaphor’s descriptive suitability and question its normative and political ramifications. We argue that uncritical characterizations of the OB as Facebook’s “supreme court” obscure its true scope and purpose. In addition, we argue that appropriating the socio-cultural symbolism and hence political legitimacy of a supreme court and mapping it onto a different type of actor poses a threat to responsible platform governance.Peer Reviewe

Myosin II filament dynamics in actin networks revealed with interferometric scattering microscopy

The plasma membrane and the underlying cytoskeletal cortex constitute active platforms for a variety of cellular processes. Recent work has shown that the remodeling acto-myosin network modifies local membrane organization, but the molecular details are only partly understood due to difficulties with experimentally accessing the relevant time and length scales. Here, we use interferometric scattering (iSCAT) microscopy to investigate a minimal acto-myosin network linked to a supported lipid bilayer membrane. Using the magnitude of the interferometric contrast, which is proportional to molecular mass, and fast acquisition rates, we detect, and image individual membrane attached actin filaments diffusing within the acto-myosin network and follow individual myosin II filament dynamics. We quantify myosin II filament dwell times and processivity as functions of ATP concentration, providing experimental evidence for the predicted ensemble behavior of myosin head domains. Our results show how decreasing ATP concentrations lead to both increasing dwell times of individual myosin II filaments and a global change from a remodeling to a contractile state of the acto-myosin network

Freedom of expression in the digital public sphere:Strategies for bridging information and accountability gaps in algorithmic content moderation

A substantial portion of contemporary public discourse and social interaction is conducted over online social media platforms, such as Facebook, YouTube, Reddit, and TikTok. Accordingly, these platforms form a core component of the digital public sphere which, although subject to private ownership, constitute a digital infrastructural resource that is open to members of the public. As private entities, platforms can set their own rules for participation, in the form of terms of service, community standards, and other guidelines. The content moderation systems deployed by such platforms to ensure that content posted on the platform complies with these terms, conditions, and standards have the potential to influence and shape public discourse by mediating what members of the public are able to see, hear, and say online. Over time, these rules may have a norm-setting effect, shaping the conduct and expectations of users about what acceptable discourse looks like. Thus, the design and implementation of content moderation systems have a powerful impact on the freedom of expression of users and their access to dialogic interaction on the platform. With great power comes great responsibility: the increasing trend towards the adoption of algorithmic content moderation systems that have a questionable track record as regards their ability to safeguard freedom of expression gives rise to urgent concerns on the need to ensure that content moderation is regulated in a manner that safeguards and fosters robust public discourse in the online sphere

Schüler*innen werten selbstständig ein Experiment zur Bestimmung der Zellsaftkonzentration (Osmose) aus: Binnendifferenzierung im naturwissenschaftlichen Unterricht durch den Einsatz gestufter Lernhilfen

In dem Forschungsprojekt „Bielefelder Binnendifferenzierung in den MINT-Fächern“ (BiBi-MINT) am Oberstufen-Kolleg Bielefeld zur Verzahnung von Mathematikunterricht und Naturwissenschaftsunterricht mit gleichzeitigem Fokus auf die Binnendifferenzierung sind unter anderem gestufte Lernhilfen zur Auswertung eines Experimentes zur Bestimmung der Zellsaftkonzentration entwickelt, angewendet und evaluiert worden. Sie sind dazu geeignet, Schüler*innen eigenverantwortlich die Auswertung und Interpretation des Experimentes durchführen zu lassen. Das Untersuchungsprinzip des Experimentes ist das Bestimmen der Masse von Gemüsestreifen vor und nach dem Einlegen in verschieden konzentrierten NaCl-Lösungen. Die Lernhilfen beinhalten dabei sowohl eine wiederholende Hinführung zur Bestimmung der relativen Massendifferenz als auch eine mathematische Auswertung und Bestimmung der Zellsaftkonzentration. Zur Interpretation werden Inhalte der biologischen Unterrichtsreihe zur Osmose vermittelt bzw. wiederholend bearbeitet

Schüler*innen lernen selbstständig das Modellieren mit Exponentialfunktionen: Binnendifferenzierung im Mathematikunterricht durch digitale gestufte Lernhilfen

In dem Forschungsprojekt „Bielefelder Binnendifferenzierung in den MINT-Fächern“ (BiBi-MINT) am Oberstufen-Kolleg Bielefeld zur Verzahnung von Mathematikunterricht und Naturwissenschaftsunterricht mit gleichzeitiger Binnendifferenzierung sind im Anwendungskontext „Corona“ digitale gestufte Lernhilfen zur Erstellung und Prognose von Exponentialfunktionen entwickelt und evaluiert worden. Sie sind dazu geeignet, dass Schüler*innen eigenverantwortlich das Modellieren mit Exponentialfunktionen erlernen. In diesem Beitrag wird anhand der konkreten Unterrichtseinheit in das Konzept der gestuften Lernhilfen eingeführt, und es werden die Materialien zum Nacherfinden als Online-Supplements zur Verfügung gestellt. Neben der Verwendung im Schulunterricht kann dieses Unterrichtsbeispiel exemplarisch in der Lehrer*innenbildung eingesetzt werden

AI-based Evaluation of cardiac real-time MRI with congenital heart disease

Cardiac MRI scans are an important tool used by cardiologists. It can be utilized for diagnoses and assessment of vital parameters like the stroke volume or blood flow. The significant reduction in acquisition time that is achievable nowadays allows the recording of realtime 3D videos of the human heart. Such high frame rates yield very large amounts of data. To evaluate this data highly efficiently and with as little manual intervention as possible, it must be processed and interpreted automatically. We introduce the key challenges in such automated evaluations of realtime cardiac MRI. As patients are able breath freely during the examination, the effect of respiration on parameters such as blood flow and stroke volume can be investigated. However, this leads to the challenge of respiratory synchronization. Also, as the 3D representation of the heart is acquired slice by slice, the cardiac cycles in those slices must be synchronized. Another challenge is the physiological segmentation of the images. Especially for pathological hearts (e.g. univentricular hearts) this is a great challenge as high accuracy and automation are demanded. Furthermore, we present our workflow to tackle those challenges and show and discuss first results. One result is a breath- and cardiac cycle synchronized segmented univentricular heart in 4D (3D+time)