Study of Cometary Dust Particle Fragmentation from <i>In situ</i> Measurements of Cometary Dust

Cometary nuclei, primitive remnants from the solar system’s birth, have compositions reflecting their time, and place, of formation. Cometary dust, a large fraction of cometary nuclei mass, is released by volatile vaporization as comets approach perihelion. Fragmentation of composite dust grains affects particle size distribution and gas-drag efficiency, affecting production rate calculations. Dust grains’ structures, implied by fragmentation process modelling, profoundly constrain comet formation theories. The causes, nature, and relative importance of fragmentation processes are investigated, supported by in situ cometary dust fragmentation observations. Results from spacecraft that have sampled cometary dust in situ, several providing evidence of fragmentation, are summarised, and two in situ datasets re-analyzed, to determine if fragmentation is ubiquitous, and if so, why it isn’t observed in every comet. Re-analysis of the International_Cometary_Explorer_(ICE) Plasma_Wave_Instrument dataset, which identified dust impacts at 21P/Giacobini-Zinner, shows evidence of grain fragmentation, clustering, and non-isotropic outflow, unidentified at the time. The Rosetta mission to 67P/Churyumov-Gerasimenko carried several dust detection and characterization instruments, including the Grain_Impact_Analyser_and Dust_Accumulator_(GIADA), data from which suggested a spacecraft-induced electrostatic deceleration and fragmentation mechanism for ultra-low-density (<1 kg m−3) aggregate grains. This work is critically reviewed, identifying several analytical deficiencies, dataset limitations, and problems with the eventual conclusions. The GIADA team analyzed Grain_Detection_System+Impact_Sensor (GDS+IS) data which fully characterized dust events. For this work GDS-only data, in which clusters were identified, was analyzed showing these data to be more reliable than initially believed, containing useful speed, and scattered light data for many of events. Re-analysis of GIADA data confirmed particles were fragmenting near the spacecraft forming detectable particle clusters, with different particle size, density, and velocity distributions to non-cluster particles. The grain fragmentation mechanism suggested isn’t proved or disproved, but associated mechanisms, including stress-induced particle break-up in the maneuvering spacecraft’s vicinity, were identified. Mean particle density, estimated using an alternative method, was between ρ− = 880 - 1180 kg m-

The “Futility of Thrift” and the Moral Economy of Nineteenth-Century Britain

This essay seeks to understand the “moral confusion” (to use David Graeber’s term in Debt) that surrounds thrift. It argues that thrift emerged as a moral imperative in the mid-nineteenth century as urban economies centered on mass consumption expanded, provoking fears of national degeneration in a working population enslaved by their own desires for immediate gratification from the panoply of food and fashion outlets. In response, a popular political economy emerged with tips on navigating the temptations of department stores and leisure complexes and avoiding the moral hazard of indebtedness by exercising restraint. These tropes imagined national regeneration, a stable economy, and a civilized society emerging from the saved capital generated by individual thrift, which could then be invested in solid, enduring businesses. At the same time, writers on the margins of conventional economics realized that a thriving urban economy, one able to provide employment for a growing population, was built on consumption: the survival of many small businesses depended on local people spending money in local shops, bars, and restaurants. This paper discusses these visions of the economy to explore the roots of an enduring tension in performative moral economy of thrift: while thrift was (and still is) associated with a morally responsible and sustainable capitalism, an everyday economy built on mass consumption depends on shopping and spending to keep capital moving. It argues that then (as now?), this contradiction was resolved through a moralized political economy that focused blame on the consumption habits of the urban poor rather than the structural inequalities resulting from the temporalities of capital investment

FD-U: Formación a docentes voluntarios de español como lengua de acogida a personas acogidas de Ucrania

española En febrero de 2022 estalló la guerra ruso-ucraniana y, desde su comienzo, más de 270 000 personas ucranianas se encuentran acogidas en España, con necesidades de vivienda, trabajo y aprendizaje del español. En este contexto, surgieron diferentes iniciativas para la enseñanza de español como lengua de acogida, como el Proyecto U, del que se da cuenta en este trabajo. Concretamente, este se centra en una formación específica para los docentes voluntarios, la FD-U, ya que, al comprobar el perfil de la mayoría de personas voluntarias del Proyecto U, se constató que, en general, no tenían ni formación previa, ni profesiones afines a la enseñanza de ELE. Por este motivo, se diseñaron webinarios que ofrecían contenidos básicos para la enseñanza de español, así como un instrumento de evaluación pre y post de la intervención. El objetivo principal de esta investigación era constatar la utilidad de los webinarios, así como la percepción de los docentes acerca de su propia preparación para dar clases de español en modalidad online a personas refugiadas. Como resultados más destacables podemos señalar que, aunque no tenían formación previa, se sentían con tranquilidad suficiente para afrontar las clases de español, si bien la formación fue percibida como de gran utilidad. English FD-U: Training of volunteer teachers of Spanish as a host language for Ukrainian refugees. In February 2022, the Russian-Ukrainian war broke out and, since its beginning, more than 270,000 Ukrainian people have fled to Spain, in need of housing, work and learning Spanish. In this context, different initiatives for teaching Spanish as a host language have arisen, such as Project U, which is described in this paper. Since most of the volunteer teachers in Project U had neither previous training nor work experience related to the teaching of Spanish as a foreign language, a specific training was designed, the FD-U, which consisted of webinars designed to provide basic content for the teaching of Spanish as a foreign language, as well as a pre-post evaluation instrument to evaluate this intervention. The main goal of this research was to ascertain the usefulness of the webinars, as well as teachers’ perceptions of their own readiness to teach Spanish online to refugees. The most notable results are that, although volunteers had no previous training, most of them felt ready enough to face Spanish classes, and they perceived the FPU as very usefu

Bringing joy back into higher education: the potential contribution of coaching

Purpose There are significant challenges facing academics and senior leaders in higher education (HE) institutions internationally. These challenges have led to increasing levels of metrification and managerialism, which has fostered work intensification, reduced professional autonomy, stress and burnout amongst faculty staff. Traditional approaches for supporting and developing staff, such as mentoring and training, do not provide the resources faculty staff need to meet the challenges they face. In contrast, experiences in various other educational and professional settings have demonstrated the effectiveness of workplace coaching in fostering well-being, adaptability, flexibility and sustainable performance. This review argues that workplace coaching could similarly support academics. Design/methodology/approach A critical literature review evaluates coaching interventions across educational and comparable sectors to identify positive well-being and performance-based outcomes. Findings While there is limited research into the efficacy of coaching interventions for faculty staff in HE, research in other educational, as well as comparable professional contexts, identifies significant sustainable improvements in well-being and performance for professional staff. Practical implications The evidence that identifies positive outcomes of coaching in professional workplace contexts is compelling. This critical review uses some of that evidence base to propose an agenda to implement coaching programmes that support faculty staff to improve their well-being and performance. Originality/value While there are published research studies on the positive outcomes of coaching in primary and secondary educational contexts, as well as for postgraduate research students, there is very limited knowledge, practice and research about coaching faculty staff in HE. This article addresses this by critically reviewing a broad range of literature to identify coaching and research initiatives for faculty staff in HE institutions

BEB-based models for ionisation cross sections of electron and positron impact with diatomic molecules

The ionising interactions of high-energy particles with molecules have applications in many areas. Despite this, some areas, including positron scattering, lack experimental data due to difficulties in performing experiments. Here, quick and simple methods for computing direct electron and positron impact ionisation cross sections are presented. These calculations, performed using the open-source software RAPID-CS, can provide a complete data set as a first approximation for when experimental, or more detailed computational work is not available. The cross-sectional data set includes the total, partial/fragment-specific, single-differential, average secondary electron energy and stopping power cross sections. The molecules N2, O2 and CO were chosen to study due to the availability of positron scattering data. An overall good agreement with experimental and other computational results is presented. Graphical abstract Direct electron (left) and positron right) impact partial ionisation cross sections for N2. Total cross section: red, N2+ partial cross section: blue, N+ partial cross section: green.electron: solid lines: BEB, experimental measurements by Lindsay and Mangan :Ürosses, Straub et al. : stars, Opel et al. : squares. Positron: solid lines: BEB0, Dashed lines: BEBA, Marler and Surko : red crosses, Bluhme et al. : star

Hidden from Family History: The Ethics of Remembering

This article draws on case studies or ‘microhistories’ from the author’s own research to explore the ethical responsibility of family historians to represent the experiences of those whose lives have been ‘hidden from history’, and in particular the lives of one’s female ancestors, as a way of correcting the omissions and erasures of official histories. It also discusses the ethical dilemmas posed by the discovery that one’s ancestors were involved in activities that are now regarded as morally suspect, such as profiting from the ownership of slaves. Finally, the article debates ethical arguments about respecting the rights of the dead to privacy

The social reproduction of (and through) food: Agrarian change in Uzbekistan

Food systems—and the interplay between food production, marketisation and access—are constituent elements of the social reproduction of life. Using a social reproduction framework, this paper problematises the ontological, epistemological and methodological premises of food system studies in agrarian change. Based on primary data collected during multiple rounds of fieldwork in rural Uzbekistan and adopting mixed methods, it offers a triple contribution. First, it assesses the inequalities of food security and dietary diversity among different classes of farmers and agrarian wage workers. Along these lines, it argues that individualised food security indicators do not unveil the systemic determinants that explain unequal patterns of social reproduction through nutrition during processes of agrarian marketisation. To move beyond individual‐based theorisations, it extends the investigation to state policies, market drivers and gender norms in relation to food knowledge, provision, affordability and availability. In so doing, it unpacks the contradictions that explain the uneven conditions of social reproduction of (and through) food. Finally, by investigating the modalities of access and availability of ultra‐processed food in rural areas, it reflects on the tensions between the capitalist global food system and its interaction with the logics of state‐led development to maintain the social reproduction of rural life

Technical variability of cornea parameters derived from anterior segment OCT fitted with Fringe Zernike polynomials

Background This study uses bootstrapping to evaluate the technical variability (in terms of model parameter variation) of Zernike corneal surface fit parameters based on Casia2 biometric data. Methods Using a dataset containing N = 6953 Casia2 biometric measurements from a cataractous population, a Fringe Zernike polynomial surface of radial degree 10 (36 components) was fitted to the height data. The fit error (height - reconstruction) was bootstrapped 100 times after normalisation. After reversal of normalisation, the bootstrapped fit errors were added to the reconstructed height, and characteristic surface parameters (flat/steep axis, radii, and asphericities in both axes) extracted. The median parameters refer to a robust surface representation for later estimates of elevation, whereas the SD of the 100 bootstraps refers to the variability of the surface fit.Results Bootstrapping gave median radius and asphericity values of 7.74/7.68 mm and -0.20/-0.24 for the corneal front surface in the flat/steep meridian and 6.52/6.37 mm and -0.22/-0.31 for the corneal back surface. The respective SD values for the 100 bootstraps were 0.0032/0.0028 mm and 0.0093/0.0082 for the front and 0.0126/0.0115 mm and 0.0366/0.0312 for the back surface. The uncertainties for the back surface are systematically larger as compared to the uncertainties of the front surface.Conclusion As measured with the Casia2 tomographer, the fit parameters for the corneal back surface exhibit a larger degree of variability compared with those for the front surface. Further studies are needed to show whether these uncertainties are representative for the situation where actual repeat measurements are possible