The Platform Governance Archive v1: A longitudinal dataset to study the governance of communication and interactions by platforms and the historical evolution of platform policies (Data Paper)

Platform policies contain the spelled out rules about what is allowed and prohibited on a service. As such, they constitute both a normative framework as well as a means of public communication by platforms. Studying the evolution of the increasingly complex web of policies that platforms have developed can hence allow us to trace the emergence of a specific normative order, i.e. the ways in which platforms are governing user activities and public speech and communication dynamics, as well as identify how they have reacted to public controversies, political debates and legal regulation. A major difficulty for studies on the historical evolution of platform policies, however, is the availability of past policies which is often needed for a thorough analysis, as the policies change quite frequently and even their names and locations often differ from the current version. Although platforms have become increasingly transparent about how and when they are changing their rules and have begun to offer public archives of the different historical versions of their policies, these archives often do not contain all of the past versions of a policy and relying on them entails trusting the platforms to provide complete information. Thus it remains hard to systematically study how the rules and norms of platforms have changed over time. Our Platform Governance Archive (PGA) aims to address this need by providing a comprehensive and uniformly collected dataset of all of the historical versions of platform policies which does not rely on the platforms’ own public records. While we are working on extending the scope of the archive to include more platforms and policies, the current dataset described in this paper contains all of the historical versions of three types of policy documents (Terms of Service, Community Guidelines, Privacy Policies) by four major platforms (Facebook, YouTube, Twitter and Instagram) in the time period from the inception of each policy until the end of 2021. Our paper gives a comprehensive overview of the conceptual layout of the Platform Governance Archive and details the automated and manual processes of data collection and data cleaning, as well as our practical and theoretical challenges. Starting with how we define a relevant change to a platform policy, we lay out how we used the Internet Archive’s Wayback Machine to identify past versions of platform policies, collect them, and then automatically and manually check for changes. Specifically, we explain how we mapped the URLs of the selected policies and they have changed over time, putting together a puzzle of how they were renamed and relocated. We then detail the automated scraping process of these URLs from the Wayback Machine as well as the automated diff-checking which we employed. The last step of the data cleaning consisted in a manual revision of the automatically identified versions based on our definition of a relevant change, which was necessary because a significant amount of data noise remained. The paper furthermore describes how the platforms' ways of displaying their policies have changed over time by increasingly turning them into interactive pages and multi-page documents, as well as how we addressed the data collection challenges that arose from this. The paper furthermore provides an overview of the resulting v1 corpus the Platform Governance Archive which is a dataset consisting of 354 policy documents with a total of 6,036 pages. By detailing the structure of our data repository on Github, we offer a guide on how to access and work with the data. We furthermore describe the characteristics and details of each platform and policy type to account for the fact that each of them have undergone a specific historical development. Lastly, our paper also presents a structural analysis of some of the general trends and patterns which are visible in the dataset over a time period of up to almost two decades on the document level. Using a quantitative analysis, we analyse how the change frequency and the character count of each platform policy has developed over time. A comparative visualisation of these findings allows us to show how the extent of the policies has grown over time, to identify periods of high growth and frequent changes and to draw comparative conclusions about the four different platforms. The Platform Governance Archive aims to be a resource for researchers, journalists, policy-makers, platform operators, activists, and other stakeholders as well as the general public. By offering both a comprehensive dataset and an accessible interface, we aim to offer and continue to develop this resource to enable research and public debate on the historical evolution of platform policies in order to trace down changes, to identify characteristic periods of isomorphic policies, to measure influencing factors, and to understand how specific debates, events, and legislation have influenced and manifested in platform policies

Demonstrating Advantages of Neuromorphic Computation: A Pilot Study

Neuromorphic devices represent an attempt to mimic aspects of the brain's architecture and dynamics with the aim of replicating its hallmark functional capabilities in terms of computational power, robust learning and energy efficiency. We employ a single-chip prototype of the BrainScaleS 2 neuromorphic system to implement a proof-of-concept demonstration of reward-modulated spike-timing-dependent plasticity in a spiking network that learns to play the Pong video game by smooth pursuit. This system combines an electronic mixed-signal substrate for emulating neuron and synapse dynamics with an embedded digital processor for on-chip learning, which in this work also serves to simulate the virtual environment and learning agent. The analog emulation of neuronal membrane dynamics enables a 1000-fold acceleration with respect to biological real-time, with the entire chip operating on a power budget of 57mW. Compared to an equivalent simulation using state-of-the-art software, the on-chip emulation is at least one order of magnitude faster and three orders of magnitude more energy-efficient. We demonstrate how on-chip learning can mitigate the effects of fixed-pattern noise, which is unavoidable in analog substrates, while making use of temporal variability for action exploration. Learning compensates imperfections of the physical substrate, as manifested in neuronal parameter variability, by adapting synaptic weights to match respective excitability of individual neurons.Comment: Added measurements with noise in NEST simulation, add notice about journal publication. Frontiers in Neuromorphic Engineering (2019

The effects of interventional mitral valve repair using the MitraClip System on the results of pulmonary function testing, pulmonary pressure and diffusing capacity of the lung

Background: The study analyzes changes in lung function, pulmonary pressure and diffusing capacity of the lung in patients with mitral valve regurgitation (MR) treated by MitraClip implantation. Methods: A total of 43 patients (19 women and 24 men with an average age of 78.0 +/- 6.6 years) who were able to perform pulmonary function testing including diffusing capacity of the lung for carbon monoxide (DLCO), vital capacity (VC), total lung capacity (TLC), residual volume (RV) and forced expiratory volume in 1 s (FEV1) before and 6 weeks after MitraClip implantation participated in this study. Furthermore, clinical and echocardiographic parameters including systolic pulmonary artery pressure (sPAP), left ventricular ejection fraction (LVEF) and left atrial diameter (LAD) measurements were recorded in all patients. Results: The procedure was performed successfully in all 43 patients leading to a reduction of MR in 97.7% of cases. One patient died on day 4 after the intervention most likely due to pulmonary artery embolism. Six weeks after the implantation 79.1% of patients showed a MR of at most mild to moderate. Furthermore, we could demonstrate a significant reduction of systolic pulmonary artery pressure during follow-up (from 48.8 +/- 11.4 mmHg to 42.9 +/- 9.0 mmHg (t(41) = - 2.6, p = 0.01). However, no changes in LVEF were detected. Comparing pre and post implant lung function tests, no significant alterations were seen for VC, TLC, DLCO and FEV1. Though, in a subgroup of patients with moderate to severe preexisting deterioration of DLCO at the baseline (max. 50%) the MitraClip procedure resulted in a significant improvement in DLCO (37.8% +/- 9.0 to 41.6% +/- 10.0, p < 0.001). Conclusions: Treatment of MR with the MitraClip system successfully reduces MR severity in the vast majority of patients. Consecutively, a reduction in pulmonary pressure could be observed, however no changes in LVEF were obvious. Lung function tests remained unaltered during follow-up. However, in a subgroup of patients with severe preexisting deterioration of DLCO the MitraClip procedure resulted in a significant improvement in DLCO

Acute transverse myelitis and psoriasiform dermatitis associated with Sjoegren’s syndrome: a case report

BACKGROUND: Clinical complications of Sjoegren’s syndrome include myelitis and skin manifestations. There is scarce observational data and a lack of randomised controlled studies regarding the treatment of Sjoegren’s syndrome in the presence of such complications. CASE PRESENTATION: Here we report the case of a 41-year-old Caucasian female patient with biopsy-proven Sjoegren’s syndrome who initially presented with generalized exanthema and subsequently developed acute extensive transverse myelitis. In view of the rapid deterioration we opted for an intensive treatment using a combination of corticosteroid pulse therapy, plasmapheresis and cyclophosphamide, which we later changed to rituximab. Under that treatment the skin manifestations resolved entirely whereas transverse myelitis showed incomplete remission. CONCLUSION: Severe neurological and dermatological complications may occur in Sjoegren’s syndrome. This suggests a close yet currently unclear pathogenetic relationship. Intensive immunosuppressant treatment resulted in significant improvement of both symptom clusters. Skin manifestations may precede other severe complications in Sjoegren’s syndrome and therefore require particular attention

A large aperture reflective wave-plate for high-intensity short-pulse laser experiments

We report on a reflective wave-plate system utilizing phase-shifting mirrors (PSM) for a continuous variation of elliptical polarization without changing the beam position and direction. The scalability of multilayer optics to large apertures and the suitability for high-intensity broad-bandwidth laser beams make reflective wave-plates an ideal tool for experiments on relativistic laser-plasma interaction. Our measurements confirm the preservation of the pulse duration and spectrum when a 30-fs Ti:Sapphire laser beam passes the system

Distinguishing between wet and dry atmospheres of TRAPPIST-1 e and f

The nearby TRAPPIST-1 planetary system is an exciting target for characterizing the atmospheres of terrestrial planets. The planets e, f and g lie in the circumstellar habitable zone and could sustain liquid water on their surfaces. During the extended pre-main sequence phase of TRAPPIST-1, however, the planets may have experienced extreme water loss, leading to a desiccated mantle. The presence or absence of an ocean is challenging to determine with current and next generation telescopes. Therefore, we investigate whether indirect evidence of an ocean and/or a biosphere can be inferred from observations of the planetary atmosphere. We introduce a newly developed photochemical model for planetary atmospheres, coupled to a radiative-convective model and validate it against modern Earth, Venus and Mars. The coupled model is applied to the TRAPPIST-1 planets e and f, assuming different surface conditions and varying amounts of CO$_2$ in the atmosphere. As input for the model we use a constructed spectrum of TRAPPIST-1, based on near-simultaneous data from X-ray to optical wavelengths. We compute cloud-free transmission spectra of the planetary atmospheres and determine the detectability of molecular features using the Extremely Large Telescope (ELT) and the James Webb Space Telescope (JWST). We find that under certain conditions, the existence or non-existence of a biosphere and/or an ocean can be inferred by combining 30 transit observations with ELT and JWST within the K-band. A non-detection of CO could suggest the existence of an ocean, whereas significant CH$_4$ hints at the presence of a biosphere.Comment: 37 pages, 18 figures, accepted for publication in Ap

Anterior gradient 2 and 3 – two prototype androgen‐responsive genes transcriptionally upregulated by androgens and by oestrogens in prostate cancer cells

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96748/1/febs12118.pd