The Blade Against the Burden: The Iconography of the Sword in \u3ci\u3eThe Lord of the Rings\u3c/i\u3e

Invites us to consider the deeper social implications of carrying and using a sword in the medieval world of Middle-earth—how bearing a sword not only indicates leadership and service, but provides an opportunity for social mobility, in addition to its more obvious military meanings. Considers as examples Merry and Pippin swearing oaths to, respectively, Théoden and Denethor; Éowyn’s heroic deeds; and especially Aragorn’s use of Narsil/Andúril as a symbol of legitimacy and service to his people

Novel Nitric Oxide (NO)-Releasing Polymers and their Biomedical Applications.

Two common factors that can cause complications with indwelling biomedical devices are thrombus and infection. Nitric oxide (NO) is known to be a potent inhibitor of platelet activation and an antimicrobial agent. In this dissertation work, two novel approaches to achieving long-term NO release from polymers were studied and evaluated for their potential biomedical applications. First, S-nitroso-N-acetypenicillamine (SNAP)-doped Elast-eon E2As creates an inexpensive polymer that can locally deliver physiologically relevant levels of NO. SNAP was found to be stable in E2As during shelf-life stability and ethylene oxide sterilization studies. The SNAP/E2As polymer was coated on the inner walls of extracorporeal circulation (ECC) circuits and was found to preserve the platelet count at ~100% of baseline and reduce thrombus area after 4 h blood flow in a rabbit model. The SNAP/E2As polymer was also used to fabricate NO-releasing catheters that were implanted in sheep veins for 7 d. The SNAP/E2As catheters significantly reduced the amount of thrombus and bacterial adhesion. In the second approach, the NO release from diazeniumdiolated dibutylhexanediamine (DBHD/N2O2)-doped polymers was significantly improved using poly(lactic-co-glycolic acid) (PLGA) additives. Acid-capped PLGA additives were found to cause high initial bursts of NO, while ester-capped PLGA additives extended the NO release for up to 14 d. Poly(vinyl chloride)- and Elast-eon E2As were used as the base polymers for combined DBHD/N2O2 and PLGA coatings on the inner walls of ECC circuits. After 4 h of blood flow, the E2As-based NOrel circuits preserved platelets at a higher level than PVC-based NOrel circuits (97% and 80% of baseline, respectively). This demonstrates that the inherent hemocompatibility properties of the base polymer can also influence the efficiency of the NO release coatings. A DBHD/N2O2-doped SG-80A polymer material was also studied and used to fabricate patches that were applied to scald burn wounds infected with Acinetobacter baumannii. The NO released from these patches applied to the wounds is shown to significantly reduce the A. baumannii infection after 24 h. The results for both of types of NO-releasing polymers studied here demonstrated greatly enhanced hemocompatibility properties that can be applied to a wide variety of blood-contacting medical devices.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/109037/1/brisbel_1.pd

Classical analogy for the deflection of flux avalanches by a metallic layer

Sudden avalanches of magnetic flux bursting into a superconducting sample undergo deflections of their trajectories when encountering a conductive layer deposited on top of the superconductor. Remarkably, in some cases flux is totally excluded from the area covered by the conductive layer. We present a simple classical model that accounts for this behaviour and considers a magnetic monopole approaching a semi-infinite conductive plane. This model suggests that magnetic braking is an important mechanism responsible for avalanche deflection.Comment: 14 pages, 5 figure

Determination of the magnetic penetration depth in a superconducting Pb film

Under the terms of the Creative Commons Attribution (CC BY) license to their work.By means of scanning Hall probe microscopy technique, we accurately map the magnetic field pattern produced by Meissner screening currents in a thin superconducting Pb stripe. The obtained field profile allows us to quantitatively estimate the Pearl length ¿ without the need of pre-calibrating the Hall sensor. This fact contrasts with the information acquired through the spatial field dependence of an individual flux quantum where the scanning height and the magnetic penetration depth combine in a single inseparable parameter. The derived London penetration depth λL coincides with the values previously reported for bulk Pb once the kinetic suppression of the order parameter is properly taken into account.This work was partially supported by the Fonds de la Recherche Scientique-FNRS, the Methusalem Funding of the Flemish Government, the Fund for Scientic Research-Flanders (FWO-Vlaanderen), and the ARC Grant 13/18-08 for Concerted Research Actions, financed by the Wallonia-Brussels Federation. J.B. acknowledges support from FRS-FNRS (Research Fellowship). J.V.d.V. acknowledges support from FWO-Vl. The work of A.V.S. was partially supported by “Crédit de demurrage,” U.Lg.Peer Reviewe

Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures

We present a detailed quantitative magneto-optical imaging study of several superconductor/ferromagnet hybrid structures, including Nb deposited on top of thermomagnetically patterned NdFeB, and permalloy/niobium with erasable and tailored magnetic landscapes imprinted in the permalloy layer. The magneto-optical imaging data is complemented with and compared to scanning Hall probe microscopy measurements. Comprehensive protocols have been developed for calibrating, testing, and converting Faraday rotation data to magnetic field maps. Applied to the acquired data, they reveal the comparatively weaker magnetic response of the superconductor from the background of larger fields and field gradients generated by the magnetic layer.Comment: 21 pages, including 2 pages of supplementary materia

In Vitro and in Vivo Study of Sustained Nitric Oxide Release Coating Using Diazeniumdiolate-doped Poly(vinyl chloride) Matrix with Poly(lactide-co-glycolide) Additive

Nitric oxide (NO) is an endogenous vasodilator as well as natural inhibitor of platelet adhesion and activation that can be released from a NO donor species, such as diazeniumdiolated dibutylhexanediamine (DBHD/N2O2) within a polymer coating. In this study, various Food and Drug Administration approved poly(lactic-co-glycolic acid) (PLGA) species were evaluated as additives to promote a prolonged NO release from DBHD/N2O2 within a plasticized poly(vinyl chloride) (PVC) matrix. When using an ester-capped PLGA additive with a slow hydrolysis time, the resulting coatings continuously release between 7 and 18 × 10−10 mol cm−2 min−1 NO for 14 days at 37 °C in PBS buffer. The corresponding pH changes within the polymer films were visualized using pH sensitive indicators and are shown to correlate with the extended NO release pattern. The optimal combined diazeniumdiolate/PLGA-doped NO release (NOrel) PVC coating was evaluated in vitro and its effect on the hemodynamics was also studied within a 4 h in vivo extracorporeal circulation (ECC) rabbit model of thrombogenicity. Four out of 7 control circuits clotted within 3 h, whereas all the NOrel coated circuits were patent after 4 h. Platelet counts on the NOrel ECC were preserved (79 ± 11% compared to 54 ± 6% controls). The NOrel coatings showed a significant decrease in the thrombus area as compared to the controls. Results suggest that by using ester-capped PLGAs as additives to a conventional plasticized PVC material containing lipophilic diazeniumdiolates, the NO release can be prolonged for up to 2 weeks by controlling the pH within the organic phase of the coating

Searching for dark matter sub-structure with HAWC

Numerical simulations show that the dark matter halos surrounding galaxies are expected to contain many over-densities or sub-halos. The most massive of these sub-halos can be optically observed in the form of dwarf galaxies. However, most lower mass sub-halos are predicted to exist as dark dwarf galaxies: sub-halos like dwarf galaxies with no luminous counterpart. It may be possible to detect these unseen sub-halos from gamma-ray signals originating from dark matter annihilation. The High Altitude Water Cherenkov Observatory (HAWC) is a very high energy (500 GeV to \u3e100 TeV) gamma ray detector with a wide field-of-view and near continuous duty cycle, making HAWC ideal for unbiased sky surveys. We perform a search for gamma ray signals from dark dwarfs in the Milky Way halo with HAWC. We perform a targeted search of HAWC gamma-ray sources which have no known association with lower-energy counterparts, based on an unbiased survey of the entire sky. With no sources found to strongly prefer dark matter models, we calculate the ability of HAWC to observe dark dwarfs. We also compute the HAWC sensitivity to potential future detections for a given model of dark matter substructure. Assuming thermal dark matter, we find the corresponding J-factor of a dark dwarf required to reach the HAWC detection criterion is 5.79× 1020 GeV2 cm−5 sr for one particular set of dark matter assumptions. HAWC is found to be able to competitively constrain dark matter annihilation from discovered halos with J-factors on the scale of 1019 GeV2 cm−5 sr or greater, with better constraints obtained on dark matter models with \u3e10 TeV masses and sources that transit overhead

Comparative studies on water governance: a systematic review

Governance is key to tackle water challenges and transform water management under the increasing pressures of competing water uses and climate change. Diverse water governance regimes have evolved in different countries and regions to regulate the development and management of water resources and the provision of water services. Scholars and policy analysts have been comparing these water governance regimes to analyze elements and processes, to assess performance, or to draw lessons. While the number of such studies has increased over the past decades, no comprehensive synthesis exists. This paper aims to present such a synthesis through conducting a systematic review of the emerging field of comparative water governance studies, and critically reflecting on how water governance is defined, conceptualized and assessed in different contexts. Based on the insights that this review brings about, we identify four areas for future research: 1) improving the balance between small-N, medium-N and large-N studies that are applied for comparative studies on water governance, 2) conducting longitudinal comparisons of water governance in order to identify temporal governance trends and patterns 3) expanding the geographical coverage of the comparisons to include underrepresented countries and regions, focusing more broadly on the Global South 4) addressing the issues of justice, equity and power, which are becoming increasingly important in tackling the water governance challenges that are exacerbated by the impacts of climate change, industrialization and urbanization

Where ecosystems, people and health meet: academic traditons and emerging fields for research and practice

Human-driven environmental change has brought attention to the importance of ecosystems in sustaining human health and well-being. There are various schools of thought and fields of inquiry and action that seek to understand health in relation to linked social and ecological phenomena. We describe 18 such fields and outline common elements and incongruities among them. They converge around the application of systems thinking and crossing disciplinary boundaries, while differences are found in methodologies, research foci and problem framing. Although fields encourage sustainable and equitable pathways for health promotion, depoliticized and ahistorical approaches continue to be standard practice. Future research calls for a deeper commitment to examining ourselves as political actors, making space for conversations around power dynamics, and (re)centering participants in research methodologies.As mudanças ambientais antrópicas despertaram a atenção para a importância dos ecossistemas como fundamentais para sustentar a saúde e o bem-estar humanos. Várias escolas de pensamento e campos de atuação em pesquisa e ação buscam compreender a saúde e os fenômenos sociais e ecológicos associados. Apresentamos 18 desses campos de atuação destacando seus elementos comuns e divergências. Eles convergem em torno do cruzamento de fronteiras disciplinares e na aplicação do pensamento sistêmico, enquanto as principais diferenças são encontradas nas metodologias, nos enfoques de pesquisa e no enquadramento dos problemas. Embora os campos busquem promover a saúde pelos caminhos sustentáveis e equitativos, as abordagens despolitizadas e a-históricas continuam sendo parte da prática padrão. Pesquisas futuras requerem um compromisso maior na avaliação das nossas próprias condutas como atores políticos e na promoção de novos espaços de discussões sobre a dinâmica de poder, a fim de (re)centralizar os participantes nas metodologias de pesquisa

Avalanches of popping bubbles in collapsing foams

We report acoustic experiments on foam systems. We have recorded the sound emitted by crackling cells during the collapsing of foams. The sound pattern is then analyzed using classical methods of statistical physics. Fundamental processes at the surface of the collapsing foam are found. In particular, size is not a relevant parameter for exploding bubbles.Comment: 8 pages, 4 figures, submitted for publicatio