boundary crossings
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Author(s):  
Saskia Huc-Hepher

AbstractBased on the author’s experience of curating a collection of migrant community web objects within the UK Web Archive, this paper combines conceptual interrogation with empirical analysis. The central premise is that the incorporation of multilingual, diasporic micro-archives serves to queer the anglophone UK Web Archive, or “patriarchive”, by dismantling steadfast binaries and implicit postcolonial hegemonies. The article challenges Jacques Derrida’s contention that the mal d’archive is the result of the archive’s ‘troubling’ duality, and posits, on the contrary, that such boundary-crossings are the very incarnation of a positive, transgressive form of xenofeminism (XF). From the dualism at the origin of the archive itself, to that comprised in the concept of genre/gender, and from the spatiotemporal in-betweenness of the archived diasporic (web)site to the translanguaging present therein, the article demonstrates how the diasporic micro-archive is the embodiment of a non-binary, trans-inclusive XF ideology. Taking French migrant women’s blogs preserved in the London French Special Collection as a primary source and examining their transformation over time, the paper explores how blog repurposing can be apprehended as a technomaterialist XF act and how the blogs’ increasing multimodal translanguaging bears witness to a form of culturo-linguistic transitioning that transcends binary hybridity.


2021 ◽  
Author(s):  
Ronan Modolo ◽  
Claire Baskevitch ◽  
Francois Leblanc ◽  
Adam Masters

<p>The JUICE (JUpiter ICy moon Explorer) mission, selected by the European Space Agency in May 2012 to be the first large mission within the Cosmic Vision Program 2015–2025, will provide the most comprehensive exploration to date of the Jovian system in all its complexity, with particular emphasis on Ganymede as a planetary body and potential habitat (JUICE Red Book, 2014). The Galilean satellites are known to have thin atmospheres, technically exospheres (McGrath et al., 2004), produced by ion-induced sputtering and sublimation of the surface materials. These moons and tenuous atmosphere are embedded in the flowing plasma of the jovian. The interaction between the neutral environments of the Galilean satellites and the jovian plasma changes the plasma momentum, the temperature and generates strong electrical currents. In order to prepare the scientific return of the mission and the optimization of operation modes of plasma instruments, a modeling effort has been carried out at LATMOS (PhD R. Allioux, IRAP, 2012; L. Leclercq, LATMOS, 2015; O. Apurva, LATMOS, 2017). A 3D parallel multi-species hybrid model (Latmos Hybrid Simulation, LatHyS) has been developed to model and characterize the plasma environment of Ganymede (Leclercq et al, 2016; Modolo et al, 2016) and a 3D parallel multi-species exospheric model (Exospheric Global Model, EGM) to pattern the dynamic of the neutral envelopes of Ganymede (Turc et al, 2014; Leblanc et al, 2017). The presentation will examine the global structure of the interaction with the jovian plasma, to describe the formation of Alfvén wings, and to emphasize the phenomena related to the multi-species nature of the plasma. The simulation model supports the preparation of the JUICE mission and its Ganymede phase by characterizing boundary crossings.</p>


2021 ◽  
Author(s):  
Hannah Ruedisser ◽  
Andreas Windisch ◽  
Ute V. Amerstorfer ◽  
David Píša ◽  
Jan Soucek

<p>Planetary magnetospheres create multiple sharp boundaries, such as the bow shock, where the solar wind plasma is decelerated and compressed, or the magnetopause, a transition between solar wind field and planetary field.<br />We attempt to use convolutional neural networks (CNNs) to identify magnetospheric boundaries, i.e.  planetary and interplanetary shocks crossings and magnetopause crossings in spacecraft in situ data. The boundaries are identified by a discontinuity in a magnetic field, plasma density, and in the spectrum of high-frequency waves. These measurements are available on many planetary missions. Data from Earth's missions Cluster and THEMIS are used for CNN training. We ultimately strive for successful classification of boundaries (shock, magnetopause, inbound, outbound) and the correct handling of multiple crossings.</p>


2021 ◽  
Author(s):  
Sophia Zomerdijk-Russell ◽  
Adam Masters ◽  
Daniel Heyner

<p>Mercury’s magnetosphere is a unique and dynamic system, primarily due to the proximity of the planet to the Sun and its small size. Interactions between solar wind and embedded Interplanetary Magnetic Field (IMF) and the dayside Hermean magnetosphere drive an electric current on the system’s magnetopause boundary. So far, electromagnetic induction due to magnetopause motion in response to changing external pressure has been used to constrain Mercury’s iron core size. Here we assess the impact a changing IMF direction has on the Hermean magnetopause currents, and the resulting inducing magnetic field. Observations made by MESSENGER during subsolar magnetopause boundary crossings in the first ‘hot season’, are used to demonstrate the importance of the IMF direction to Mercury’s magnetopause currents. Our 16 boundary crossings show that introduction of external IMFs change the magnetopause current direction by 10° to 100°, compared to the case where only the internal planetary field is considered. Analytical modelling was used to fill in the bigger picture and suggests for an east-west reversal of the IMF, typical of the heliospheric current sheet sweeping over Mercury’s magnetosphere, the inducing field at Mercury’s surface caused by the resulting magnetopause current dynamics is on the order of 10% of the global planetary field. These results suggest that IMF variability alone has an appreciable effect on Mercury’s magnetopause current and generates a significant inducing magnetic field around the planet. The arrival of the BepiColombo mission will allow this response to be further explored as a method of probing Mercury’s interior.</p>


Res Publica ◽  
2021 ◽  
Author(s):  
Olle Torpman

AbstractMuch has been written about climate change from an ethical view in general, but less has been written about it from a libertarian point of view in particular. In this paper, I apply the libertarian moral theory to the problem of climate change. I focus on libertarianism’s implications for our individual emissions. I argue that (i) even if our individual emissions cause no harm to others, these emissions cross other people’s boundaries, (ii) although the boundary-crossings that are due to our ‘subsistence emissions’ are implicitly consented to by others, there is no such consent to our ‘non-subsistence emissions’, and (iii) there is no independent justification for these emissions. Although offsetting would provide such a justification, most emitters do not offset their non-subsistence emissions. Therefore, these emissions violate people’s rights, which means that they are impermissible according to libertarianism’s non-aggression principle.


2021 ◽  
Vol 9 (1) ◽  
pp. 365-379
Author(s):  
Barbara Kensington-Miller ◽  
Andrea Webb ◽  
Ann Gansemer-Topf ◽  
Heather Lewis ◽  
Julie Luu ◽  
...  

This study examines the lived experiences of seven internationally diverse scholars from Canada, the United States, New Zealand, and Australia to answer the question: how do we make meaning of our collective boundary crossing experiences across disciplines and positions within SoTL? Our positions range from graduate student, faculty, and academic developers, to department chair and centre director. We conducted a phenomenological study, based on narratives of experience, and drew on Wenger-Trayner and Wenger-Trayner’s (2015) theoretical framework that explores the features of a landscape of practice. Guided by this framework, we analyze our boundary crossings and brokering across the “diverse, political and flat” features of the SoTL landscape. Our collective findings highlight the critical role brokers play in facilitating boundary crossings. Brokering is precarious, bringing people together, building trusting relationships, and developing legitimacy while negotiating deadlocks, bureaucracy, authorities, and a multitude of challenges. Brokers, we found, require strength and resilience to mobilise, influence, and drive change in the landscape to transform existing practices or create new ones. We suggest that our analytical process can be used as a tool of analysis for future research about how brokers influence the SoTL landscape of practice and how brokering enhances SoTL development, support, and leadership.


2021 ◽  
Vol 9 (1) ◽  
pp. 365-379
Author(s):  
Barbara Kensington-Miller ◽  
Andrea Webb ◽  
Ann Gansemer-Topf ◽  
Heather Lewis ◽  
Julie Luu ◽  
...  

This study examines the lived experiences of seven internationally diverse scholars from Canada, the United States, New Zealand, and Australia to answer the question: how do we make meaning of our collective boundary crossing experiences across disciplines and positions within SoTL? Our positions range from graduate student, faculty, and academic developers, to department chair and centre director. We conducted a phenomenological study, based on narratives of experience, and drew on Wenger-Trayner and Wenger-Trayner’s (2015) theoretical framework that explores the features of a landscape of practice. Guided by this framework, we analyze our boundary crossings and brokering across the “diverse, political and flat” features of the SoTL landscape. Our collective findings highlight the critical role brokers play in facilitating boundary crossings. Brokering is precarious, bringing people together, building trusting relationships, and developing legitimacy while negotiating deadlocks, bureaucracy, authorities, and a multitude of challenges. Brokers, we found, require strength and resilience to mobilise, influence, and drive change in the landscape to transform existing practices or create new ones. We suggest that our analytical process can be used as a tool of analysis for future research about how brokers influence the SoTL landscape of practice and how brokering enhances SoTL development, support, and leadership.


2021 ◽  
Author(s):  
Vladimir Krasnoselskikh ◽  
Andrea Larosa ◽  
Thierry Dudok de Wit ◽  
Oleksiy Agapitov ◽  
Clara Froment ◽  
...  

<p>Switchback boundaries separate two plasmas moving with different velocities, that may have different temperatures and densities and typically manifest sharp magnetic field deflections through the boundary. They may be analyzed similarly to MHD discontinuities. The first step of their characterization consists of analysis in terms of MHD discontinuities. Such an analysis was performed by Larosa et al., (2021) who has found that 32% of them may be attributed to rotational discontinuities, 17% to tangential, about 42% to the group of discontinuities that are difficult to unambiguously define whether they are tangential or rotational, and 9% that do not belong to any of these two groups. We describe and apply hereafter for two events another approach for the characterization of the boundaries based on classification of the general type discontinuity in MHD approximation. It is based on the problem of the decay of the general type of discontinuity. It is well known [Kulikovsky and Lyubimov, 1962, Gogosov, 1959} that general type MHD discontinuity decays on 7 separate discontinuities belonging to different types of MHD waves, namely, entropic wave, two slow mode waves, two Alfvenic waves, and two fast mode waves. Entropic wave is standing in the reference frame of the discontinuity; other wave modes are supposed to run in the opposite directions from the initial discontinuity with their characteristic velocities. Making use of plasma parameters from two sides of the boundary one can evaluate the fraction of each wave mode present in the discontinuity. We apply this method to two boundary crossings. This repartition of the discontinuity allows characterizing the deviation from Alfvenicity quantitatively.</p><p>References</p><p>Larosa, A., et al., A&A, 2021, (accepted)</p><p>Kulikovsky, Lyubimov, Magnetohydrodynamics, (1962)</p><p>Gogosov, V.V., Decay of the MHD discontinuity, (1959)</p>


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