Lunar surface: Dust dynamics and regolith mechanics

The lunar surface is characterized by a collisionally evolved regolith resulting from meteoroid bombardment. This lunar soil consists of highly angular particles in a broad, approximately power law size distribution, with impact-generated glasses. The regolith becomes densified and difficult to excavate when subjected to lunar quakes or, eventually, manned and unmanned activity on the surface. Solar radiation and the solar wind produce a plasma sheath near the lunar surface. Lunar grains acquire charge in this environment and can exhibit unusual behavior, including levitation and transport across the surface because of electric fields in the plasma sheath. The fine component of the lunar regolith contributes to the operational and health hazards posed to planned lunar expeditions. In this paper we discuss the mechanical response of the regolith to anticipated exploration activities and review the plasma environment near the lunar surface and the observations, models, and dynamics of charged lunar dust

Morphologies of three-dimensional shear bands in granular media

We present numerical results on spontaneous symmetry breaking strain localization in axisymmetric triaxial shear tests of granular materials. We simulated shear band formation using three-dimensional Distinct Element Method with spherical particles. We demonstrate that the local shear intensity, the angular velocity of the grains, the coordination number, and the local void ratio are correlated and any of them can be used to identify shear bands, however the latter two are less sensitive. The calculated shear band morphologies are in good agreement with those found experimentally. We show that boundary conditions play an important role. We discuss the formation mechanism of shear bands in the light of our observations and compare the results with experiments. At large strains, with enforced symmetry, we found strain hardening.Comment: 6 pages 5 figures, low resolution figures

Dynamic Centrifuge Experiment on a Cantilever Retaining Wall

Seismic loads on a tall, cantilever retaining wall were studied using centrifuge modeling. An aluminum wall (55\u27 prototype) retaining dry, cohesionless backfill was subjected to two successive dynamic events. The backfill surface was horizontal and even with the top of the wall. The input motion was supplied via a servo-controlled, electro-hydraulic shake table. The input motion was roughly sinusoidal with peak horizontal accelerations of approximately 0.2g and 0.4g for the first and second dynamic events, respectively. The input motion frequency was 1 hz at prototype scale. Lateral earth pressures on the wall, wall displacement, and accelerations of the wall and backfill soil were measured. Pressure transducers were used to directly measure lateral earth pressures on the wall. The magnitudes of the lateral earth pressures were compared with values calculated using the Mononobe-Okabe method. Preliminary results indicate that calculated pressures are higher than the measured pressures

Critical packing in granular shear bands

In a realistic three-dimensional setup, we simulate the slow deformation of idealized granular media composed of spheres undergoing an axisymmetric triaxial shear test. We follow the self-organization of the spontaneous strain localization process leading to a shear band and demonstrate the existence of a critical packing density inside this failure zone. The asymptotic criticality arising from the dynamic equilibrium of dilation and compaction is found to be restricted to the shear band, while the density outside of it keeps the memory of the initial packing. The critical density of the shear band depends on friction (and grain geometry) and in the limit of infinite friction it defines a specific packing state, namely the \emph{dynamic random loose packing}

Order-of-magnitude speedup for steady states and traveling waves via Stokes preconditioning in Channelflow and Openpipeflow

Steady states and traveling waves play a fundamental role in understanding hydrodynamic problems. Even when unstable, these states provide the bifurcation-theoretic explanation for the origin of the observed states. In turbulent wall-bounded shear flows, these states have been hypothesized to be saddle points organizing the trajectories within a chaotic attractor. These states must be computed with Newton's method or one of its generalizations, since time-integration cannot converge to unstable equilibria. The bottleneck is the solution of linear systems involving the Jacobian of the Navier-Stokes or Boussinesq equations. Originally such computations were carried out by constructing and directly inverting the Jacobian, but this is unfeasible for the matrices arising from three-dimensional hydrodynamic configurations in large domains. A popular method is to seek states that are invariant under numerical time integration. Surprisingly, equilibria may also be found by seeking flows that are invariant under a single very large Backwards-Euler Forwards-Euler timestep. We show that this method, called Stokes preconditioning, is 10 to 50 times faster at computing steady states in plane Couette flow and traveling waves in pipe flow. Moreover, it can be carried out using Channelflow (by Gibson) and Openpipeflow (by Willis) without any changes to these popular spectral codes. We explain the convergence rate as a function of the integration period and Reynolds number by computing the full spectra of the operators corresponding to the Jacobians of both methods.Comment: in Computational Modelling of Bifurcations and Instabilities in Fluid Dynamics, ed. Alexander Gelfgat (Springer, 2018

Measuring the diffusion of palliative care in long-term care facilities – a death census

ABSTRACT: BACKGROUND: The dissemination of palliative care for patients presenting complex chronic diseases at various stages has become an important matter of public health. A death census in Swiss long-term care facilities (LTC) was set up with the aim of monitoring the frequency of selected indicators of palliative care. METHODS: The survey covered 150 LTC facilities (105 nursing homes and 45 home health services), each of which was asked to complete a questionnaire for every non-accidental death over a period of six months. The frequency of 4 selected indicators of palliative care (resort to a specialized palliative care service, the administration of opiates, use of any pain measurement scale or other symptom measurement scale) was monitored in respect of the stages of care and analysed based on gender, age, medical condition and place of residence. RESULTS: Overall, 1200 deaths were reported, 29.1% of which were related to cancer. The frequencies of each indicator varied according to the type of LTC, mostly regarding the administration of opiate. It appeared that the access to palliative care remained associated with cancer, terminal care and partly with age, whereas gender and the presence of mental disorders had no effect on the indicators. In addition, the use of drugs was much more frequent than the other indicators. CONCLUSION: The profile of patients with access to palliative care must become more diversified. Among other recommendations, equal access to opiates in nursing homes and in home health services, palliative care at an earlier stage and the systematic use of symptom management scales when resorting to opiates have to become of prime concern

Compassionate communities: design and preliminary results of the experience of Vic (Barcelona, Spain) caring city

yesBackground: A program of Compassionate City or Community (CC) has been designed and developed in the City of Vic (43,964 habitants, Barcelona, Spain), based on The Compassionate City Charter and other public health literature and experiments, with the joint leadership of the City Council and the Chair of Palliative Care at the University of Vic, and as an expansion of a comprehensive and integrated system of palliative care. Methods: The program started with an assessment of needs of the city as identified by 48 social organizations with a foundational workshop and a semi-structured survey. After this assessment, the mission, vision, values and aims were agreed. The main aims consisted in promoting changes in social and cultural attitudes toward the end of life (EoL) and providing integrated care for people with advanced chronic conditions and social needs such as loneliness, poverty, low access to services at home, or conflict. The selected slogan was “Living with meaning, dignity, and support the end of life”. Results: The program for the first year has included 19 activities (cultural, training, informative, and mixed) and followed by 1,260 attendants, and the training activities were followed by 147 people. Local and regional sponsors are funding the initiative. After a year, a quantitative and qualitative evaluation was performed, showing high participation and satisfaction of the attendants and organizations. In the second year, the care for particular vulnerable people defined as targets (EoL and social factors described before) will start with volunteers with more organizations to join the project. Conclusions: The key identified factors for the initial success are: the strong joint leadership between social department of the Council and the University; clear aims and targets; high participation rates; the limited size of the geographical context; which allowed high participation and recognition; and the commitment to evaluate results

Plan de formación y docencia en un centro integral de cáncer: estrategia e implementación

Introducción: El Institut Català d'Oncologia (ICO) puso en marcha la Unidad de Formación y Docencia (UFiD), en el año 2006, con el objetivo de potenciar el desarrollo profesional, la difusión del conocimiento y la calidad de la atención oncológica. En el presente artículo se describe el proceso de puesta en marcha de la UFiD, los resultados del estudio de las necesidades formativas realizada por los profesionales y colectivos de la institución, las acciones formativas organizadas, y en el área de docencia, los resultados de la reorganización de las trayectorias docentes de los diferentes servicios, así como el apoyo de nuevas iniciativas. Materiales y métodos: Durante el periodo 2008-2009, se implantaron acciones formativas y docentes en concordancia con los resultados del estudio de necesidades y con las líneas estratégicas de la institución. Se realizaron un total de 71 actividades formativas, con 898 participantes de todas las categorías profesionales, con una tasa de satisfacción de los participantes de 7,8 sobre 10. En el apartado de docencia, durante el mismo periodo se realizaron 3 másteres, 3 posgrados, 59 cursos de actualización con metodología semipresencial y 19 cursos con metodología online, todos ellos con acreditación académica. La satisfacción media fue de 8 sobre 10. Resultados y conclusiones: La actividad llevada a cabo por la UFiD ha permitido, por una parte, articular la formación continuada en base al estudio de las necesidades de los profesionales, lo que ha contribuido a promover el desarrollo profesional y la calidad asistencial de éstos, y por otra parte, dar soporte a las actividades docentes ya existentes y promover nuevas iniciativas para favorecer la difusión de conocimientos en el área oncológica, lo que ha posicionado al ICO como un centro absolutamente comprometido con la formación oncológica