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1. Ionization waves in the PK-4 direct current neon discharge

   https://doi.org/10.1088/1361-6595/abb955  

   Hartmann, Peter ; Rosenberg, Marlene ; Juhasz, Zoltan ; Matthews, Lorin S ; Sanford, Dustin L. ; Vermillion, Katrina ; Reyes, Jorge Carmona ; Hyde, Truell W ( November 2020 , Plasma Sources Science and Technology)

   null (Ed.)

   The PK-4 system is a micro-gravity dusty plasma experiment currently in operation on-board the International Space Station. The experiment utilizes a long DC discharge in neon or argon gases. We apply our 2D particle-in-cell with Monte Carlo collisions discharge simulation to compute local plasma parameters that serve as input data for future dust dynamics models. The simulation includes electrons, Ne+ ions, and Nem metastable atoms in neon gas and their collisions at solid surfaces including secondary electron emission and glass wall charging. On the time scale of the on-board optical imaging, the positive column appears stable and homogeneous. On the other hand, our simulations show that on microsecond time scales the positive column is highly inhomogeneous: ionization waves with phase velocities in the range between 500 m s−1 and 1200 m s−1 dominate the structure. In these waves, the electric field and charged particle densities can reach amplitudes up to 10 times of their average value. Our experiments on ground-based PK-4 replica systems fully support the numerical findings. In the experiment, the direction of the DC current can be alternated, which has been found to favor dust particle chain formation. We discuss possible mechanisms for how the highly oscillatory plasma environment contributes to the dust particle chain formation. 

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2. Effects of Bubble Injections on the Plasma Sheet Configuration

   https://doi.org/10.1029/2021JA029127  

   Sadeghzadeh, Sina ; Yang, Jian ; Wang, Chih‐Ping ; Mousavi, Ameneh ; Wang, Wenrui ; Sun, Weiqin ; Toffoletto, Frank ; Wolf, Richard ( June 2021 , Journal of Geophysical Research: Space Physics)

   The bimodal transport in the plasma sheet consists of sunward large‐scale, coherent, and slow motion of charged particles in the closed‐field‐line region as well as meso‐scale, localized, and transient fast flow bursts. It has been found that these earthward moving bursty bulk flows, also called “bubbles,” play a crucial role not only in the transporting mass and energy, but also in resolving the pressure‐balance crisis with their integrated effects. In this study, we examine how bubbles can affect the average configuration of the middle and inner plasma sheet using the Inertialized Rice Convection Model (RCM‐I). Bubbles are sporadically imposed aton the nightside plasma sheet, with optimized parameters that constrain their statistical properties. The consequence of the injection of these series of bubbles is evaluated by comparing against observed statistical results, including plasma moments and magnetic field configuration. Our findings confirm that bursty bulk flows are indispensable elements in the magnetotail plasma sheet.

    

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3. Biodiversity at the global scale: the synthesis continues

   https://doi.org/10.1002/ajb2.1694  

   Folk, Ryan A. ; Siniscalchi, Carolina M. ( June 2021 , American Journal of Botany)

   Traditionally, the generation and use of biodiversity data and their associated specimen objects have been primarily the purview of individuals and small research groups. While deposition of data and specimens in herbaria and other repositories has long been the norm, throughout most of their history, these resources have been accessible only to a small community of specialists. Through recent concerted efforts, primarily at the level of national and international governmental agencies over the last two decades, the pace of biodiversity data accumulation has accelerated, and a wider array of biodiversity scientists has gained access to this massive accumulation of resources, applying them to an ever‐widening compass of research pursuits. We review how these new resources and increasing access to them are affecting the landscape of biodiversity research in plants today, focusing on new applications across evolution, ecology, and other fields that have been enabled specifically by the availability of these data and the global scope that was previously beyond the reach of individual investigators. We give an overview of recent advances organized along three lines: broad‐scale analyses of distributional data and spatial information, phylogenetic research circumscribing large clades with comprehensive taxon sampling, and data sets derived from improved accessibility of biodiversity literature. We also review synergies between large data resources and more traditional data collection paradigms, describe shortfalls and how to overcome them, and reflect on the future of plant biodiversity analyses in light of increasing linkages between data types and scientists in our field.

    

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4. Meso-Scale Electrodynamic Coupling of the Earth Magnetosphere-Ionosphere System

   https://doi.org/10.1007/s11214-022-00940-0  

   Yu, Yiqun ; Cao, Jinbin ; Pu, Zuyin ; Jordanova, Vania K. ; Ridley, Aaron ( December 2022 , Space Science Reviews)

   Within the fully integrated magnetosphere-ionosphere system, many electrodynamic processes interact with each other. We review recent advances in understanding three major meso-scale coupling processes within the system: the transient field-aligned currents (FACs), mid-latitude plasma convection, and auroral particle precipitation. (1) Transient FACs arise due to disturbances from either dayside or nightside magnetosphere. As the interplanetary shocks suddenly compress the dayside magnetosphere, short-lived FACs are induced at high latitudes with their polarity successively changing. Magnetotail dynamics, such as substorm injections, can also disturb the current structures, leading to the formation of substorm current wedges and ring current disruption. (2) The mid-latitude plasma convection is closely associated with electric fields in the system. Recent studies have unraveled some important features and mechanisms of subauroral fast flows. (3) Charged particles, while drifting around the Earth, often experience precipitating loss down to the upper atmosphere, enhancing the auroral conductivity. Recent studies have been devoted to developing more self-consistent geospace circulation models by including a better representation of the auroral conductance. It is expected that including these new advances in geospace circulation models could promisingly strengthen their forecasting capability in space weather applications. The remaining challenges especially in the global modeling of the circulation system are also discussed.

    

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5. SlicerMorph: An open and extensible platform to retrieve, visualize and analyse 3D morphology

   https://doi.org/10.1111/2041-210X.13669  

   Rolfe, Sara ; Pieper, Steve ; Porto, Arthur ; Diamond, Kelly ; Winchester, Julie ; Shan, Shan ; Kirveslahti, Henry ; Boyer, Doug ; Summers, Adam ; Maga, A. Murat ( July 2021 , Methods in Ecology and Evolution)

   Large‐scale digitization projects such as#ScanAllFishesandoVertare generating high‐resolution microCT scans of vertebrates by the thousands. Data from these projects are shared with the community using aggregate 3D specimen repositories like MorphoSource through various open licenses. We anticipate an explosion of quantitative research in organismal biology with the convergence of available data and the methodologies to analyse them.

   Though the data are available, the road from a series of images to analysis is fraught with challenges for most biologists. It involves tedious tasks of data format conversions, preserving spatial scale of the data accurately, 3D visualization and segmentations, and acquiring measurements and annotations. When scientists use commercial software with proprietary formats, a roadblock for data exchange, collaboration and reproducibility is erected that hurts the efforts of the scientific community to broaden participation in research.

   We developed SlicerMorph as an extension of 3D Slicer, a biomedical visualization and analysis ecosystem with extensive visualization and segmentation capabilities built on proven python‐scriptable open‐source libraries such as Visualization Toolkit and Insight Toolkit. In addition to the core functionalities of Slicer, SlicerMorph provides users with modules to conveniently retrieve open‐access 3D models or import users own 3D volumes, to annotate 3D curve and patch‐based landmarks, generate landmark templates, conduct geometric morphometric analyses of 3D organismal form using both landmark‐driven and landmark‐free approaches, and create 3D animations from their results. We highlight how these individual modules can be tied together to establish complete workflow(s) from image sequence to morphospace. Our software development efforts were supplemented with short courses and workshops that cover the fundamentals of 3D imaging and morphometric analyses as it applies to study of organismal form and shape in evolutionary biology.

   Our goal is to establish a community of organismal biologists centred around Slicer and SlicerMorph to facilitate easy exchange of data and results and collaborations using 3D specimens. Our proposition to our colleagues is that using a common open platform supported by a large user and developer community ensures the longevity and sustainability of the tools beyond the initial development effort.

    

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