1,059 research outputs found

    Relaxed MHD states of a multiple region plasma

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    We calculate the stability of a multiple relaxation region MHD (MRXMHD) plasma, or stepped-Beltrami plasma, using both variational and tearing mode treatments. The configuration studied is a periodic cylinder. In the variational treatment, the problem reduces to an eigenvalue problem for the interface displacements. For the tearing mode treatment, analytic expressions for the tearing mode stability parameter Δ′\Delta', being the jump in the logarithm in the helical flux across the resonant surface, are found. The stability of these treatments is compared for m=1m=1 displacements of an illustrative RFP-like configuration, comprising two distinct plasma regions. For pressure-less configurations, we find the marginal stability conclusions of each treatment to be identical, confirming analytic results in the literature. The tearing mode treatment also resolves ideal MHD unstable solutions for which Δ′→∞\Delta' \to \infty: these correspond to displacement of a resonant interface. Wall stabilisation scans resolve the internal and external ideal kink. Scans with increasing pressure are also performed: these indicate that both variational and tearing mode treatments have the same stability trends with β\beta, and show pressure stabilisation in configurations with increasing edge pressure. Combined, our results suggest that MRXMHD configurations which are stable to ideal perturbations plus tearing modes are automatically in a stable state. Such configurations, and their stability properties, are of emerging importance in the quest to find mathematically rigorous solutions of ideal MHD force balance in 3D geometry.Comment: 11 pages, 3 figures, 22nd IAEA Fusion Energy Conference, Geneva, Switzerland. Submitted to Nuclear Fusio

    On the Choice of Shear Correction Factor in Sandwich Structures

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    The first-order shear deformation theory (FSDT) is a relatively simple tool that has been found to yield accurate results in the non-local problems of sandwich structures, such as buckling and free vibration. However, a key factor in practical application of the theory is determination of the transverse shear correction factor (K), which appears as a coefficient in the expression for the transverse shear stress resultant. The physical basis for this factor is that it is supposed to compensate for the FSDT assumption that the shear strain is uniform through the depth of the cross section. In the present paper, the philosophies and results of K determination for homogeneous rectangular cross sections are first reviewed, followed by a review and discussion for the case of sandwich structures. The analysis presented in the paper results in the conclusion that K should be taken equal to unity, as a first approximation, for both two-skin as well as for multi-skin sandwich structures.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    An investigation into the depth and time dependent behavior of UV cured 3D ink jet printed objects

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    An ultra-violet (UV) curable ink jet 3D printed material was characterized by an inverse finite element modeling (IFEM) technique employing a nonlinear viscoelastic–viscoplastic (NVEVP) material constitutive model; this methodology was compared directly with nanoindentation tests. The printed UV cured ink jet material properties were found to be z-depth dependent owing to the sequential layer-by-layer deposition approach. With further post-UV curing, the z-depth dependence was weakened but properties at all depths were influenced by the duration of UV exposure, indicating that none of the materials within the samples had reached full cure during the 3D printing process. Effects due to the proximity of an indentation to the 3D printed material material-sample fixing interface, and the different mounting material, in a test sample were examined by direct 3D finite element simulation and shown to be insignificant for experiments performed at a distance greater than 20 lm from the interface

    Neutrophils use selective autophagy receptor Sqstm1/p62 to target Staphylococcus aureus for degradation in vivo in zebrafish

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    Macroautophagy/autophagy functions to degrade cellular components and intracellular pathogens. Autophagy receptors, including SQSTM1/p62, target intracellular pathogens. Staphylococcus aureus is a significant pathogen of humans, especially in immunocompromise. S. aureus may use neutrophils as a proliferative niche, but their intracellular fate following phagocytosis has not been analyzed in vivo. In vitro, SQSTM1 can colocalize with intracellular Staphylococcus aureus, but whether SQSTM1 is beneficial or detrimental in host defense against S. aureus in vivo is unknown. Here we determine the fate and location of S. aureus within neutrophils throughout zebrafish infection. We show Lc3 and Sqstm1 recruitment to phagocytosed S. aureus is altered depending on the bacterial location within the neutrophil and that Lc3 marking of bacterial phagosomes within neutrophils may precede bacterial degradation. Finally, we show Sqstm1 is important for controlling cytosolic bacteria, demonstrating for the first time a key role of Sqstm1 in autophagic control of S. aureus in neutrophils

    Endocrine therapy for hormone receptor-positive metastatic breast cancer: American Society of Clinical Oncology Guideline

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    PURPOSE: To develop recommendations about endocrine therapy for women with hormone receptor (HR) -positive metastatic breast cancer (MBC). METHODS: The American Society of Clinical Oncology convened an Expert Panel to conduct a systematic review of evidence from 2008 through 2015 to create recommendations informed by that evidence. Outcomes of interest included sequencing of hormonal agents, hormonal agents compared with chemotherapy, targeted biologic therapy, and treatment of premenopausal women. This guideline puts forth recommendations for endocrine therapy as treatment for women with HR-positive MBC. RECOMMENDATIONS: Sequential hormone therapy is the preferential treatment for most women with HR-positive MBC. Except in cases of immediately life-threatening disease, hormone therapy, alone or in combination, should be used as initial treatment. Patients whose tumors express any level of hormone receptors should be offered hormone therapy. Treatment recommendations should be based on type of adjuvant treatment, disease-free interval, and organ function. Tumor markers should not be the sole criteria for determining tumor progression; use of additional biomarkers remains experimental. Assessment of menopausal status is critical; ovarian suppression or ablation should be included in premenopausal women. For postmenopausal women, aromatase inhibitors (AIs) are the preferred first-line endocrine therapy, with or without the cyclin-dependent kinase inhibitor palbociclib. As second-line therapy, fulvestrant should be administered at 500 mg with a loading schedule and may be administered with palbociclib. The mammalian target of rapamycin inhibitor everolimus may be administered with exemestane to postmenopausal women with MBC whose disease progresses while receiving nonsteroidal AIs. Among patients with HR-positive, human epidermal growth factor receptor 2-positive MBC, human epidermal growth factor receptor 2-targeted therapy plus an AI can be effective for those who are not chemotherapy candidates

    Multipolar Reactive DPD: A Novel Tool for Spatially Resolved Systems Biology

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    This article reports about a novel extension of dissipative particle dynamics (DPD) that allows the study of the collective dynamics of complex chemical and structural systems in a spatially resolved manner with a combinatorially complex variety of different system constituents. We show that introducing multipolar interactions between particles leads to extended membrane structures emerging in a self-organized manner and exhibiting both the necessary mechanical stability for transport and fluidity so as to provide a two-dimensional self-organizing dynamic reaction environment for kinetic studies in the context of cell biology. We further show that the emergent dynamics of extended membrane bound objects is in accordance with scaling laws imposed by physics.Comment: submitted to CMSB 0

    A mechanical property evaluation of graded density Al-Si10-Mg lattice structures manufactured by selective laser melting

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    Metal components with applications across a range of industrial sectors can be manufactured by selective laser melting (SLM). A particular strength of SLM is its ability to manufacture components incorporating periodic lattice structures not realisable by conventional manufacturing processes. This enables the production of advanced, functionally graded, components. However, for these designs to be successful, the relationships between lattice geometry and performance must be established. We do so here by examining the mechanical behaviour of uniform and graded density SLM Al-Si10-Mg lattices under quasistatic loading. As-built lattices underwent brittle collapse and non-ideal deformation behaviour. The application of a microstructure-altering thermal treatment drastically improved their behaviour and their capability for energy absorption. Heat-treated graded lattices exhibited progressive layer collapse and incremental strengthening. Graded and uniform structures absorbed almost the same amount of energy prior to densification, 6.3±0.26.3±0.2 MJ/m3 and 5.7±0.25.7±0.2 MJ/m3, respectively, but densification occurred at around 7% lower strain for the graded structures. Several characteristic properties of SLM aluminium lattices, including their effective elastic modulus and Gibson-Ashby coefficients, C1 and α, were determined; these can form the basis of new design methodologies for superior components in the future

    Solid foundations? Towards a historical sociology of prison building programmes in England and Wales, 1959–2015

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    Between 1959 and 2015 the UK government embarked upon five major phases of prison building in England and Wales. Drawing upon detailed archival research, this article offers a historical sociology of prison building programmes. It traces the evolution of prison building as a public policy concern and documents how this key site of penal policymaking was interpreted, and contested, by policy actors who were themselves embedded within deep institutional structures of power and meaning. It argues that prison building has moved from the margins to the mainstream of penal policy, shaped by strongly-held convictions about the liberal-democratic state, the competition for control of finite resources and the complex ?geography of administration? that underpins the British machinery of government

    Current status of turbulent dynamo theory: From large-scale to small-scale dynamos

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    Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic Prandtl numbers. It is argued that all the different cases show similarities at intermediate length scales. On the other hand, in the presence of helicity of the turbulence, power develops on large scales, which is not present in non-helical small-scale turbulent dynamos. At small length scales, differences occur in connection with the dissipation cutoff scales associated with the respective value of the magnetic Prandtl number. These differences are found to be independent of whether or not there is large-scale dynamo action. However, large-scale dynamos in homogeneous systems are shown to suffer from resistive slow-down even at intermediate length scales. The results from simulations are connected to mean field theory and its applications. Recent work on helicity fluxes to alleviate large-scale dynamo quenching, shear dynamos, nonlocal effects and magnetic structures from strong density stratification are highlighted. Several insights which arise from analytic considerations of small-scale dynamos are discussed.Comment: 36 pages, 11 figures, Spa. Sci. Rev., submitted to the special issue "Magnetism in the Universe" (ed. A. Balogh
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