Mitochondria Exert a Negative Feedback on the Propagation of Intracellular Ca2+ Waves in Rat Cortical Astrocytes

We have used digital fluorescence imaging techniques to explore the interplay between mitochondrial Ca2+ uptake and physiological Ca2+ signaling in rat cortical astrocytes. A rise in cytosolic Ca2+ ([Ca2+]cyt), resulting from mobilization of ER Ca2+ stores was followed by a rise in mitochondrial Ca2+ ([Ca2+]m, monitored using rhod-2). Whereas [Ca2+]cyt recovered within ∼1 min, the time to recovery for [Ca2+]m was ∼30 min. Dissipating the mitochondrial membrane potential (Δψm, using the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxy-phenyl-hydrazone [FCCP] with oligomycin) prevented mitochondrial Ca2+ uptake and slowed the rate of decay of [Ca2+]cyt transients, suggesting that mitochondrial Ca2+ uptake plays a significant role in the clearance of physiological [Ca2+]cyt loads in astrocytes. Ca2+ signals in these cells initiated either by receptor-mediated ER Ca2+ release or mechanical stimulation often consisted of propagating waves (measured using fluo-3). In response to either stimulus, the wave traveled at a mean speed of 22.9 ± 11.2 μm/s (n = 262). This was followed by a wave of mitochondrial depolarization (measured using tetramethylrhodamine ethyl ester [TMRE]), consistent with Ca2+ uptake into mitochondria as the Ca2+ wave traveled across the cell. Collapse of Δψm to prevent mitochondrial Ca2+ uptake significantly increased the rate of propagation of the Ca2+ waves by 50%. Taken together, these data suggest that cytosolic Ca2+ buffering by mitochondria provides a potent mechanism to regulate the localized spread of astrocytic Ca2+ signals

The MeerKAT Galaxy Cluster Legacy Survey: I. Survey overview and highlights

Please abstract in the article.The South African Radio Astronomy Observatory (SARAO), the National Research Foundation (NRF), the National Radio Astronomy Observatory, US National Science Foundation, the South African Research Chairs Initiative of the DSI/NRF, the SARAO HCD programme, the South African Research Chairs Initiative of the Department of Science and Innovation.http://www.aanda.orghj2022Physic

Sharing and Sustainability Across Institutional and Self-instituted Forms

In recent years, instrumentalist agendas have had a profound impact, internationally, on the definition and delivery of education. Strengthened by the economic crisis, these agendas today threaten to dissolve the uniqueness of many academic institutions. Communities of practitioners which depend upon these organizations find themselves pushed into ever more precarious economic relations. Media attention has highlighted the idea of information as a public good and brought the ethics of information sharing to the nub of a debate over openness in society. Is the focus on permeability, on access and integration, an opportunity to advance the ideal of academic gift exchange or a threat to its distinctive forms? How can individuals and cooperating groups (often time-limited research partnerships) within educational institutions gain through sharing as a social act? What effect can individuals have in forming sustainable creative networks and what chances do such networks have for embedding a lasting culture of sharing (of cooperative and interdisciplinary practices) within institutions, both educational and social, both institutional and self-instituted? The paper addresses these questions, by reference to the project Electronic Literature as a Model of Creativity and Innovation in Practice (ELMCIP) and some of its linked organizations. ELMCIP is a collaboration between several European academic institutions which aims to 'develop a network based creative community', focused on practitioners and theorists in the field of Electronic Literature. It has recently joined several international organizations with the objective to share datasets on published digital literature across a number of platforms. What are the influencing factors in such ventures and how might this cooperation be informed by methods evolved by P2P and Open Access communities? How can sharing be engaged from a social dimension in order to encourage sustainability beyond the lifetime of projects such as ELMCIP

Trash Versionality for Post-Digital Culture

This article attempts an overview of phenomena, which exemplify informational and conceptual instances (or ‘versions’) characteristic of current ‘post-digital’ conditions. By counter-posing a variety of material, I aim to explore the role and position of different kinds of images (foremost social and visual) as they constitute post-digital relations. These are relations in which the primacy of computerized digital objects is moot. The versions presented in this text are the social, cultural and organizational confluences which find expression in differing data formats — originals and copies subject to fluctuating, moment-to-moment alteration. Together with the growth in communication and exchange, these versions imply a continual re-writing of the standards affecting social and network-based encounter. The processes renew shared conceptions and pictures, prompt self-reflection and pose the questions, “whose truth?” and, “whose value(s)?

On Under-determination in Cosmology

I discuss how modern cosmology illustrates under-determination of theoretical hypotheses by data, in ways that are different from most philosophical discussions. I emphasize cosmology's concern with what data could in principle be collected by a single observer (Section 2); and I give a broadly sceptical discussion of cosmology's appeal to the cosmological principle as a way of breaking the under-determination (Section 3). I confine most of the discussion to the history of the observable universe from about one second after the Big Bang, as described by the mainstream cosmological model: in effect, what cosmologists in the early 1970s dubbed the `standard model', as elaborated since then. But in the closing Section 4, I broach some questions about times earlier than one second

Medien – Wissen – Bildung: Kulturen und Ethiken des Teilens

Dass das Teilen in der Gesellschaft der Gegenwart einmal eine so große Rolle spielen würde, hätte bis vor kurzem wohl kaum jemand vorausgesagt. Eine globale Protestbewegung brachte ein tiefes Bedürfnis zum Ausdruck, alternative Wege einzuschlagen, die auf anderen Werten beruhten als jene, die allem Anschein nach zur Finanzkrise geführt hatten. Gleichzeitig sind hoch entwickelte Informations- und Kommunikationstechnologien, die das Teilen erleichtern, nicht nur beinahe überall verfügbar; sie stehen auch im Zentrum des Interesses zahlreicher Menschen, die viel Zeit und Einsatz aufbringen, um mit diesen Technologien zu experimentieren und sie in die Abläufe ihres Alltagslebens eingliedern. Eine ganze Generation von medienkompetenten, radikal globalisierten Menschen wächst mit der täglichen und persönlichen Erfahrung auf, dass das Teilen von (digitalen) Gütern ein unverzichtbares Element im Aufbau gemeinschaftlicher Beziehungen verschiedenster Art ist. Heute stehen diese Erfahrungen im krassen Widerspruch zu anderen gesellschaftlichen Erfahrungen, bei denen Wettbewerb und individuelles Besitzstreben vorherrschen. Dieser Band will einen Beitrag zur kollektiven Arbeit leisten, das Teilen in der Gesellschaft neu zu denken

Medien – Wissen – Bildung: Kulturen und Ethiken des Teilens

Dass das Teilen in der Gesellschaft der Gegenwart einmal eine so große Rolle spielen würde, hätte bis vor kurzem wohl kaum jemand vorausgesagt. Eine globale Protestbewegung brachte ein tiefes Bedürfnis zum Ausdruck, alternative Wege einzuschlagen, die auf anderen Werten beruhten als jene, die allem Anschein nach zur Finanzkrise geführt hatten. Gleichzeitig sind hoch entwickelte Informations- und Kommunikationstechnologien, die das Teilen erleichtern, nicht nur beinahe überall verfügbar; sie stehen auch im Zentrum des Interesses zahlreicher Menschen, die viel Zeit und Einsatz aufbringen, um mit diesen Technologien zu experimentieren und sie in die Abläufe ihres Alltagslebens eingliedern. Eine ganze Generation von medienkompetenten, radikal globalisierten Menschen wächst mit der täglichen und persönlichen Erfahrung auf, dass das Teilen von (digitalen) Gütern ein unverzichtbares Element im Aufbau gemeinschaftlicher Beziehungen verschiedenster Art ist. Heute stehen diese Erfahrungen im krassen Widerspruch zu anderen gesellschaftlichen Erfahrungen, bei denen Wettbewerb und individuelles Besitzstreben vorherrschen. Dieser Band will einen Beitrag zur kollektiven Arbeit leisten, das Teilen in der Gesellschaft neu zu denken

The MeerKAT Galaxy Cluster Legacy Survey. I. Survey Overview and Highlights

International audienceMeerKAT's large number (64) of 13.5 m diameter antennas, spanning 8 km with a densely packed 1 km core, create a powerful instrument for wide-area surveys, with high sensitivity over a wide range of angular scales. The MeerKAT Galaxy Cluster Legacy Survey (MGCLS) is a programme of long-track MeerKAT L-band (900−1670 MHz) observations of 115 galaxy clusters, observed for ∼6−10 h each in full polarisation. The first legacy product data release (DR1), made available with this paper, includes the MeerKAT visibilities, basic image cubes at ∼8″ resolution, and enhanced spectral and polarisation image cubes at ∼8″ and 15″ resolutions. Typical sensitivities for the full-resolution MGCLS image products range from ∼3−5 μJy beam−1. The basic cubes are full-field and span 2° × 2°. The enhanced products consist of the inner 1.2° × 1.2° field of view, corrected for the primary beam. The survey is fully sensitive to structures up to ∼10' scales, and the wide bandwidth allows spectral and Faraday rotation mapping. Relatively narrow frequency channels (209 kHz) are also used to provide H I mapping in windows of 0 200. We find no dependence of the star-formation rate on distance from the cluster centre, and we observe a small excess of the radio-to-100 μm flux ratio towards the centre of Abell 209 that may reflect a ram pressure enhancement in the denser environment. We detect diffuse cluster radio emission in 62 of the surveyed systems and present a catalogue of the 99 diffuse cluster emission structures, of which 56 are new. These include mini-halos, halos, relics, and other diffuse structures for which no suitable characterisation currently exists. We highlight some of the radio galaxies that challenge current paradigms, such as trident-shaped structures, jets that remain well collimated far beyond their bending radius, and filamentary features linked to radio galaxies that likely illuminate magnetic flux tubes in the intracluster medium. We also present early results from the H I analysis of four clusters, which show a wide variety of H I mass distributions that reflect both sensitivity and intrinsic cluster effects, and the serendipitous discovery of a group in the foreground of Abell 3365. Data are available at https://doi.org/10.48479/7epd-w356