1,197 research outputs found

    Rotational dynamics of a soft filament: wrapping transition and propulsive forces

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    We analyze experimentally the shape of a long elastic filament rotating in a viscous liquid. We identify a continuous but sharp transition from a straight to an helical shape, resulting from the competition between viscous stresses and elastic forces. This induced helicity generates a propulsive force along the axis of rotation. In addition, we show that the shape transition is associated with an unstable branch in the force-torque relation. A linearized model of the fluid-structure interaction is proposed to account for all the features of the non-linear filament dynamics

    Bioorthogonal Catalysis Goes Chiral

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    Refers to: Zhi Du, Chun Liu, Hualong Song, Peter Scott, Zhenqi Liu, Jinsong Ren, Xiaogang Qu. Neutrophil-Membrane-Directed Bioorthogonal Synthesis of Inflammation-Targeting Chiral Drugs; Chem, Volume 6, Issue 8, 6 August 2020, Pages 2060-2072.Bioorthogonal nanofactories have emerged in the last decade to provide xenobiotic pathways that generate nonbiological substances in living environments. In this issue of Chem, Qu and co-workers incorporate asymmetric catalytic properties and chemotactic capabilities into novel nanodevices to achieve the stereo- and site-selective synthesis of the active enantiomer of ibuprofen at inflammation sites.Peer reviewe

    Coding Qualitative Data at Scale: Guidance for Large Coder Teams Based on 18 Studies

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    We outline a process for using large coder teams (10 + coders) to code large-scale qualitative data sets. The process reflects experience recruiting and managing large teams of novice and trainee coders for 18 projects in the last decade, each engaging a coding team of 12 (minimum) to 54 (maximum) coders. We identify four unique challenges to large coder teams that are not presently discussed in the methodological literature: (1) recruiting and training coders, (2) providing coder compensation and incentives, (3) maintaining data quality and ensuring coding reliability at scale, and (4) building team cohesion and morale. For each challenge, we provide associated guidance. We conclude with a discussion of advantages and disadvantages of large coder teams for qualitative research and provide notes of caution for anyone considering hiring and/or managing large coder teams for research (whether in academia, government and non-profit sectors, or industry)

    Adaptive Groundwater Governance and the Challenges of Policy Implementation in Idaho’s Eastern Snake Plain Aquifer Region

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    Globally, groundwater overdraft poses significant challenges to agricultural production. As a result, it is likely that new water management policies and governance arrangements will be needed to stop groundwater depletion and maintain agricultural viability. Drawing on interviews with state and non-state water managers and other water actors, this paper provides a study of a recent resource management agreement between surface water and groundwater irrigators in the Eastern Snake Plain Aquifer region of Idaho. Using adaptive governance as our descriptive framework, we examine how groundwater governance arrangements emerge and are applied to mitigate the impacts of groundwater overdraft. Our findings suggest that adaptive governance, while not a stated goal of the agreement, may enable flexible and sustainable social and ecological outcomes. Our findings also indicate that this new governance arrangement creates a vacuum in enforcement authority that may prove challenging as the management agreement is implemented. These findings extend our understanding of the conditions necessary for effective adaptive governance of groundwater resources, and highlight the challenge of creating capacity for local resource managers as governance shifts from more bureaucratic to adaptive and decentralised arrangements

    Histoire de D. Iean deuxiesme Roy de Castille

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    Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Sign.:a8, A-Z8, 2A-2D8Marca tip. en port

    Transboundary cultural resources: Sacred wildlife, Indigenous emotions, and conservation decision-making

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    For many Indigenous communities in North America, the grizzly bear is a symbol associated with tribal medicine, spirituality, history, and knowledge. Despite its cultural importance to Indigenous communities and also federal trust responsibilities, Indigenous Peoples are rarely consulted in conservation decision-making concerning grizzly bears, and the emotional outcomes of these decisions are poorly understood. In 2017 grizzly bears were removed from protection under the Endangered Species Act in the Greater Yellowstone Ecosystem. Drawing from emotional political ecology and emotional geography, we use the concepts of cultural resources and 'networked space' to investigates how conservation decisions about transboundary cultural resources affect the emotions of Indigenous Peoples inside and outside of policy-targeted areas such as Yellowstone. The bears are non-subsistence resources that also carry cultural meanings for people who live beyond their current range. We find that conservation decisions affecting transboundary cultural resources transcend time and space and can have strong emotional consequences for our research participants who live outside of the policy-targeted area. In connection with the psychological dimension of emotional political ecologies, we also find that our participant's emotional responses to the delisting were animated by the historical traumas imposed by living in a colonial state

    Domain growth and aging scaling in coarsening disordered systems

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    Using extensive Monte Carlo simulations we study aging properties of two disordered systems quenched below their critical point, namely the two-dimensional random-bond Ising model and the three-dimensional Edwards-Anderson Ising spin glass with a bimodal distribution of the coupling constants. We study the two-times autocorrelation and space-time correlation functions and show that in both systems a simple aging scenario prevails in terms of the scaling variable L(t)/L(s)L(t)/L(s), where LL is the time-dependent correlation length, whereas ss is the waiting time and tt is the observation time. The investigation of the space-time correlation function for the random-bond Ising model allows us to address some issues related to superuniversality.Comment: 8 pages, 9 figures, to appear in European Physical Journal

    Development of novel monoclonal antibodies against CD109 overexpressed in human pancreatic cancer.

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    Pancreatic cancer is one of the most aggressive and lethal types of cancer, and more effective therapeutic agents are urgently needed. Overexpressed cell surface antigens are ideal targets for therapy with monoclonal antibody (mAb)-based drugs, but none have been approved for the treatment of pancreatic cancer. Here, we report development of two novel mouse mAbs, KU42.33C and KU43.13A, against the human pancreatic cancer cell line BxPC-3. Using ELISA, flow cytometry, competitive assay and immunoprecipitation followed by mass spectrometry, we discovered that these two mAbs target two distinct epitopes on the external domain of CD109 that are overexpressed by varying amounts in human pancreatic cancer cell lines. Treatment with these two naked antibodies alone did not affect tumour cell growth or migration in vitro. Of the two mAbs, only KU42.33C was useful in determining the expression of CD109 in tumour cells by Western blot and immunohistochemistry. Interestingly, immunohistochemistry of human pancreatic carcinoma tissue arrays with mAb KU42.33C showed that 94% of the 65 human pancreatic adenocarcinoma cases were CD109 positive, with no expression in normal pancreatic tissues. Our results suggest that these two novel mAbs are excellent tools for determining the expression level of CD109 in the tumour specimens and sera of patients with a wide range of cancers, in particular pancreatic cancer, and for investigating its diagnostic, prognostic and predictive value. Further research is warranted and should aim to unravel the therapeutic potential of the humanised forms or conjugated versions of such antibodies in patients whose tumours overexpress CD109 antigen

    A nonlinear hydrodynamical approach to granular materials

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    We propose a nonlinear hydrodynamical model of granular materials. We show how this model describes the formation of a sand pile from a homogeneous distribution of material under gravity, and then discuss a simulation of a rotating sandpile which shows, in qualitative agreement with experiment, a static and dynamic angle of repose.Comment: 17 pages, 14 figures, RevTeX4; minor changes to wording and some additional discussion. Accepted by Phys. Rev.

    Use of axial tomography to follow temporal changes of benthic communities in an unstable sedimentary environment (Baie des Ha! Ha!, Saguenay Fjord)

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    In the upper layer of the sediment column, organic matter recycling is greatly influenced by bioturbation. However, there are many physical changes in the nature of the sediment that may disturb benthic communities and create a biogeochemical imbalance. Following a very heavy rainfall between 26 and 29 July 1996, an intense flash flood in the Saguenay Fjord caused discharges of 6 million cubic metres of sediments into Baie des Ha! Ha!. Unstable sediment deposits located at the top of the delta of the Rivie`re des Ha! Ha! were sporadically exported to the deep basin. After this physical disturbance, meiobenthic and macrobenthic organisms progressively re-colonised the sediment column. To determine the impacts of such sedimentary depositions on benthic fauna, two stations, one at the head and one at the mouth of the Baie des Ha! Ha!, have been monitored since 1996. During this survey, we developed a new method for the quantification of biogenic structures using computer axial tomography (CAT-Scan). Benthic fauna analysis showed that the two stations were characterised by different temporal changes in the benthic dynamics according to their geographic location. Using CAT-Scan analysis of sediment cores, we were able to characterise the stability of the sediment column for the two stations in 1999 and 2000. Scan results suggest that colonisation processes were closely linked with the stability of the sediment column. Erosion and redeposition of surficial sediments caused a succession in the formation of biogenic structures. These variations were characterised for the first time using CAT-Scan, which is a nondestructive, rapid, and precise method. Tomographic analysis showed the importance of the production and destruction rates of biogenic structures and the sedimentation rate for the preservation of burrows and potentially reactive components. This study finally demonstrated that each erosional event could be followed by a rapid formation of biogenic structures, allowing the re-oxidation of old deposits
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