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1. Dynamical evolution of multiple-population globular clusters

   https://doi.org/10.1093/mnras/stab223  

   Vesperini, Enrico; Hong, Jongsuk; Giersz, Mirek; Hypki, Arkadiusz (February 2021, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT We have carried out a set of Monte Carlo simulations to study a number of fundamental aspects of the dynamical evolution of multiple stellar populations in globular clusters with different initial masses, fractions of second generation (2G) stars, and structural properties. Our simulations explore and elucidate: (1) the role of early and long-term dynamical processes and stellar escape in the evolution of the fraction of 2G stars and the link between the evolution of the fraction of 2G stars and various dynamical parameters; (2) the link between the fraction of 2G stars inside the cluster and in the population of escaping stars during a cluster’s dynamical evolution; (3) the dynamics of the spatial mixing of the first-generation (1G) and 2G stars and the details of the structural properties of the two populations as they evolve toward mixing; (4) the implications of the initial differences between the spatial distribution of 1G and 2G stars for the evolution of the anisotropy in the velocity distribution and the expected radial profile of the 1G and 2G anisotropy for clusters at different stages of their dynamical history; and (5) the variation of the degree of energy equipartition of the 1G and the 2G populations as a function of the distance from the cluster’s centre and the cluster’s evolutionary phase. 

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2. Paleorelief and footwall rotation adjacent to the Wasatch Fault Zone recorded by the Eocene–Oligocene paleosurfaces, Snyderville Basin, Utah, U.S.A.

   Stearns, M.A.; Limb, E.; Bunds, M.P. (January 2022, Transactions American Geophysical Union)

   The Wasatch Fault Zone (WFZ) is a north–south striking, west-dipping extensional fault system that bounds the eastern margin of the Basin and Range Province. Fluid inclusion thermobarometry and paleosalinity horizons require 11 km of vertical offset across the WFZ and suggest 15–20o of eastward rotation of the WFZ footwall. A series of Eocene–Oligocene intrusive and volcanic rocks, the Wasatch Intrusive Belt (WIB), crop out in the Wasatch Mountains and Snyderville Basin in a now oblique upper-crustal section where the deepest rocks are adjacent to the WFZ and the Eocene paleosurfaces are located ~35 km east of the WFZ. Paleosurfaces include Keetley and Norwood volcanic deposits (part of the WIB) and Wasatch Fm. conglomerates sitting unconformably on Mesozoic and older rocks. It was unclear how the overall eastward rotation was recorded by the paleosurfaces, both locally and regionally, and how much paleorelief existed during the Eocene–Oligocene. These basal surfaces were digitized and analyzed in ArcGIS and Matlab to determine the magnitude and pattern of rotation recorded by the paleosurfaces and to create and refine a 3D model of exhumation within the Wasatch Mountains. The maximum rotation of an individual surface is 8o, and planar best fit of all surfaces is 2o. This mismatch between the fluid inclusion and geologic data suggests that distributed deformation, yet-to-be-identified structures, and/or paleorelief likely complicated the geologic record of footwall rotation. A three-dimensional pattern of exhumation suggests north–south variation in the magnitude of exhumation which decreases away from the latitude of the WIB. East–west variation in the rotation magnitude of the paleosurfaces could possibly owe to thermal buoyancy of the exhumed rocks near the WFZ. The pattern of exhumation, surface trace of the WFZ, pattern of modern relief, and emplacement history of the WIB are consistent with increased buoyancy in the central Wasatch Mountains and proximal to the WFZ due to the prolonged elevated geothermal gradient in the vicinity of the WIB. The WIB crops out in a high relief, topographically complex area, which combined with the footwall rotation, makes an exhumation map an invaluable tool for interpreting the thermal history of the magmatic rocks and contextualizing petrochronology data from the WIB. 

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3. Studying the Formation of Engineers: A Case Study of a Higher-education Learning Ecology

   Korte, Russell; LeBlanc, Saniya (July 2021, ASEE Annual Conference proceedings)

   null (Ed.)

   The development of professional engineers for the workforce is one of the aims of engineering education, which benefits from the complementary efforts of engineering students, faculty, and employers. Typically, current research on engineering competencies needed for practice in the workplace is focused on the experiences and perspectives of practicing engineers. This study aimed to build on this work by including the perspectives and beliefs of engineering faculty about preparing engineering students, as well as the perspectives and beliefs of engineering students about preparing for the workplace. The overall question of the research was, “What and how do engineering students learn about working in the energy sector?” Additional questions asked practicing engineers, “What is important to learn about your work and how did you learn what was important when you started in this industry? For engineering faculty, we asked, “What is important for students to learn as they prepare for work as professionals in the energy industry?” We anticipated that the findings of triangulating these three samples would help us better understand the nature of the preparation of engineering students for work by exploring the connections and disconnections between engineering education in school and engineering practice in the workplace. The aim was to map out the complex ecosystem of professional learning in the context of engineering education and practice. The core concept framing this study is the development of competence for engineering practice—including the education of students in the context of higher education and the practical learning of newly hired engineers on the job. Initial findings of the work-in-progress describe the nature of instruction and learning in higher education, learning in the workplace, along with comparisons and contrasts between the two. As of this point, we have initially mapped the learning ecosystem in the workplace based on in-depth, qualitative interviews with 12 newly hired engineers in the target energy company. In addition, we are analyzing interviews with two managers in the company and three other experienced leaders in the energy industry (this sample is currently in process and will include interviews with more participants). Currently, we are analyzing and mapping the learning and experiences of students in their studies of energy engineering and the instructional goals of engineering faculty teaching and mentoring these students. The map of the higher education ecosystem will connect with the workplace ecosystem to portray a more longitudinal map of the learning and development of professional competence of engineering students preparing for their career in the energy sector. The findings of the analysis of the workplace emphasized the importance of the social and relational systems in the workplace, while very preliminary indications from the educational context (students and faculty) indicate initial awareness of the social context of energy practice and policy. There are also indications of the nature of important cultural differences between higher education and industry. We continue to collect data and work on the analysis of data with the aim of mapping out the larger learning and experience ecosystem that leading to professional competence. 

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4. Informal roads as social-ecological-technological systems (SETS): sustainability challenges and impact on landscape transformations

   https://doi.org/10.31489/2021BMG4/144-154  

   Kuklina, Vera; Petrov, Andrey; Bilichenko, Irina; Bogdanov, Viktor; Kobylkin, Dmitriy; Krasnoshtanova, Natalia (October 2021, Karaġandy universitetìnìn habaršysy Biologiâ medicina geografiâ seriâsy)

   Following the call to mobilize studies of social-ecological systems and sociotechnical systems, the paper presents the case for studying integrated social-ecological-technological systems (SETS), and dynamic systems that include social, natural and technological (engineering) elements. Using the case study of informal roads in the Baikal region, authors of the article argue that re-focusing on SETS creates additional synergies and convergence options to improve the understanding of coupled systems and infrastructure in particular. Historically, transportation infrastructure has contributed to changes in natural and social systems of Northern Eurasia: Transsiberian and Baikal-Amur railroads and East Siberia – Pacific Ocean and Power of Siberia pipelines have been the main drivers of social-ecological transitions. At the local scale, informal roads serve as one of the most illustrative and characteristic examples of SETS. The examination of development and transformation of the informal roads allows exploring the interactions between socioeconomic processes, ecological dynamics and technological advances. The variety of informal roads reflects the importance of specific social, natural or technological factors in the SETS transformation largely unconditioned by policy and regulations thus providing a unique opportunity to better understand sustainability challenges facing infrastructure-based SETS. Relying on interviews and in-situ observations conducted in 2019 in the Baikal region, the following factors affecting sustainability of informal road SETS were identified: social (identification of actors involved in location, construction, maintenance, use and abandonment of informal roads), technological (road cover, width, frequency and nature of use by different kinds of vehicles), environmental (geomorphology and landscape sensitivity and vulnerability). The sustainability challenges of SETS development and transformations are found in changing mobility practices, social structure and economies of local communities, increased occurrences of forest fires and development of erosion and permafrost degradation in local environment and push for development of new technologies of transportation and communication. 

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5. The origin and micromechanics of the preferential orientation of crystals in mush

   Carrara, AC; Bergantz, G (July 2023, Gochemical Society)

   none (Ed.)

   An obstacle to developing a general mechanical framework for magma mush is the emergence and complexity of a crystal fabric. To illuminate the conditions that produce a crystal fabric we performed time-dependent numerical simulations using a Computational-Fluid-Dynamics and Discrete-Element-Method (CFD-DEM) model in three dimensions. The specific focus was on the role of shear strain in the creation of a preferential orientation of crystals in mush. CFD-DEM method allows for the simultaneous coupling and frictional interactions of melt and crystals undergoing shear strain. The crystal shapes are represented using spheroids (either oblate or prolate). Simulations consist in imposing a compression stress (pressure) and a simple shear to a dense suspension of crystals in a viscous liquid, and monitoring the evolution of the orientation and strength of the shape fabrics. We ran a series of simulations by varying the size and aspect ratio of the particles. We considered samples in which all the solids have the same volume and shape, and cases including size and aspect ratio distributions. Results show that the strength of the shape fabric and the angle between the crystal preferential orientation and the compression plane both increase with the shear strain up to steady state values, which are primarily controlled by the aspect ratio of the particles. The stronger the aspect ratio, the greater the magnitude of the preferential orientation and the lower its angle relative to the compression plane. When introducing a distribution in the size of the crystals, we observed a decrease in the strength of the shape fabric and an increase in the angle between the preferential orientation of the crystals and the compression plane compared with samples composed of crystals having the same shape and size. Similarly, the distribution in the aspect ratio further decreases the strength of the shape fabric and increases the angle between the preferential orientation of the solids and the compression plane. Finally, we employed an alternative approach to quantify the amount of foliation and lineation and show that the samples always display a stronger foliation than lineation, although the shear strain increases both the foliation and the lineation. 

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