Pulsed-field magnetization of drilled bulk high-temperature superconductors: flux front propagation in the volume and on the surface

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during a pulsed-field magnetization. As the magnetic pulse penetrates the cylindrical sample, the magnetic flux density is measured simultaneously in 16 holes by means of microcoils that are placed across the median plane, i.e. at an equal distance from the top and bottom surfaces, and close to the surface of the sample. We discuss the time evolution of the magnetic flux density in the holes during a pulse and measure the time taken by the external magnetic flux to reach each hole. Our data show that the flux front moves faster in the median plane than on the surface when penetrating the sample edge; it then proceeds faster along the surface than in the bulk as it penetrates the sample further. Once the pulse is over, the trapped flux density inside the central hole is found to be about twice as large in the median plane than on the surface. This ratio is confirmed by modelling

Bulk high-Tc superconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux ?

Drilling holes in a bulk high-Tc superconductor enhances the oxygen annealing and the heat exchange with the cooling liquid. However, drilling holes also reduces the amount of magnetic flux that can be trapped in the sample. In this paper, we use the Bean model to study the magnetization and the current line distribution in drilled samples, as a function of the hole positions. A single hole perturbs the critical current flow over an extended region that is bounded by a discontinuity line, where the direction of the current density changes abruptly. We demonstrate that the trapped magnetic flux is maximized if the center of each hole is positioned on one of the discontinuity lines produced by the neighbouring holes. For a cylindrical sample, we construct a polar triangular hole pattern that exploits this principle; in such a lattice, the trapped field is ~20% higher than in a squared lattice, for which the holes do not lie on discontinuity lines. This result indicates that one can simultaneously enhance the oxygen annealing, the heat transfer, and maximize the trapped field

Apatites in Gale Crater

ChemCam is an active remote sensing instrument suite that has operated successfully on MSL since landing Aug. 6th, 2012. It uses laser pulses to remove dust and to analyze rocks up to 7 m away. Laser-induced breakdown spectroscopy (LIBS) obtains emission spectra of materials ablated from the samples in electronically excited states. The intensities of the emission lines scale with the abundances of the related element. ChemCam is sensitive to most major rock-forming elements as well as to a set of minor and trace elements such as F, Cl, Li, P, Sr, Ba, and Rb. The measured chemical composition can then be used to infer the mineralogical composition of the ablated material. Here, we report a summary of inferred apatite detections along the MSL traverse at Gale Crater. We present the geologic settings of these findings and derive some interpretations about the formation conditions of apatite in time and space

Modification of the trapped field in bulk high-temperature superconductors as a result of the drilling of a pattern of artificial columnar holes

The trapped magnetic field is examined in bulk high-temperature superconductors that are artificially drilled along their c-axis. The influence of the hole pattern on the magnetization is studied and compared by means of numerical models and Hall probe mapping techniques. To this aim, we consider two bulk YBCO samples with a rectangular cross-section that are drilled each by six holes arranged either on a rectangular lattice (sample I) or on a centered rectangular lattice (sample II). For the numerical analysis, three different models are considered for calculating the trapped flux: (i), a two-dimensional (2D) Bean model neglecting demagnetizing effects and flux creep, (ii), a 2D finite-element model neglecting demagnetizing effects but incorporating magnetic relaxation in the form of an E-J power law, and, (iii), a 3D finite element analysis that takes into account both the finite height of the sample and flux creep effects. For the experimental analysis, the trapped magnetic flux density is measured above the sample surface by Hall probe mapping performed before and after the drilling process. The maximum trapped flux density in the drilled samples is found to be smaller than that in the plain samples. The smallest magnetization drop is found for sample II, with the centered rectangular lattice. This result is confirmed by the numerical models. In each sample, the relative drops that are calculated independently with the three different models are in good agreement. As observed experimentally, the magnetization drop calculated in the sample II is the smallest one and its relative value is comparable to the measured one. By contrast, the measured magnetization drop in sample (1) is much larger than that predicted by the simulations, most likely because of a change of the microstructure during the drilling process.Comment: Proceedings of EUCAS 09 conferenc

Modeling the martian atmosphere with the LMD global climate model

Introduction: For several years we have been developing a 3D Global Climate Model (GCM) for Mars derived from the models used on Earth for weather forecasting or climate changes studies [1]. The purpose of such a project is ambitious: we wish to build a 'Mars simulator' based only on physical equations, with no tailor-made forcing, but able to reproduce all the available observations of the Martian climate (temperatures, winds, but also clouds, dust, ices, chemical species, etc...). The GCM is constantly evolving, thanks to a contnuous collaboration between several teams based in France (LMD, SA), the UK (The Open University, University of Oxford) and Spain (Instituto de Astrofisica de Andalucia), and with the support of ESA and CNES. We are currently working on an improved version of the model. Several new parametrisation are included in the heart of the model (radiative transfer, surface and subsurface processes, dynamics) and the applications of the GCM are in contnuous development (Water, dust, CO2, radon cycles, photochemistry, thermosphere, ionosphere, etc...

Erratum to: Benchmarks for ethically credible partnerships between industry and academic health centers: beyond disclosure of financial conflicts of interest.

Relationships between industry and university-based researchers have been commonplace for decades and have received notable attention concerning the conflicts of interest these relationships may harbor. While new efforts are being made to update conflict of interest policies and make industry relationships with academia more transparent, the development of broader institutional partnerships between industry and academic health centers challenges the efficacy of current policy to effectively manage these innovative partnerships. In this paper, we argue that existing strategies to reduce conflicts of interest are not sufficient to address the emerging models of industry-academic partnerships because they focus too narrowly on financial matters and are not comprehensive enough to mitigate all ethical risk. Moreover, conflict-of-interest strategies are not designed to promote best practices nor the scientific and social benefits of academic-industry collaboration. We propose a framework of principles and benchmarks for "ethically credible partnerships" between industry and academic health centers and describe how this framework may provide a practical and comprehensive approach for designing and evaluating such partnerships

Mineralogy of Vera Rubin Ridge in Gale Crater from the Mars Science Laboratory CheMin instrument

Gale crater was selected as the landing site for the Mars Science Laboratory Curiosity rover because of orbital evidence for a variety of secondary minerals in the lower slopes of Aeolis Mons (aka Mount Sharp) that indicate changes in aqueous conditions over time. Distinct units demonstrate orbital spectral signatures of hematite, phyllosilicate (smectite), and sulfate minerals, which suggest that ancient aqueous environments in Gale crater varied in oxidation potential, pH, and water activity. Vera Rubin ridge (VRR) is the first of these units identified from orbit to have been studied by Curiosity. Orbital near-infrared data from VRR show a strong band at 860 nm indicative of hematite. Before Curiosity arrived at VRR, the hypotheses to explain the formation of hematite included (1) precipitation at a redox interface where aqueous Fe2+ was oxidized to Fe3+, and (2) acidic alteration of olivine in oxic fluids. Studying the composition and sedimentology of the rocks on VRR allow us to test and refine these hypotheses and flesh out the depositional and diagenetic history of the ridge. Here, we focus on the mineralogical results of four rock powders drilled from and immediately below VRR as determined by CheMin

Pharmacotherapy and Pregnancy: Highlights from the Third International Conference for Individualized Pharmacotherapy in Pregnancy

To address provider struggles to provide evidence-based, rational drug therapy to pregnant women, this third Conference was convened to highlight the current progress and research in the field. Speakers from academic centers, industry, and governmental institutions spoke about: the Food and Drug Administration’s role in pregnancy pharmacology and the new labeling initiative; drug registries in pregnancy; the pharmacist’s role in medication use in pregnancy; therapeutic areas such as preterm labor, gestational diabetes, nausea and vomiting in pregnancy, and hypertension; breast-feeding and medications; ethical challenges for consent in pregnancy drug studies; the potential for cord blood banks; and concerns about the fetus when studying drugs in pregnancy. The Conference highlighted several areas of collaboration within the current Obstetrics Pharmacology Research Units Network and hoped to educate providers, researchers, and agencies with the common goal to improve the ability to safely and effectively use individualized pharmacotherapy in pregnancy