216 research outputs found

    Spin motive forces due to magnetic vortices and domain walls

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    We study spin motive forces, i.e, spin-dependent forces, and voltages induced by time-dependent magnetization textures, for moving magnetic vortices and domain walls. First, we consider the voltage generated by a one-dimensional field-driven domain wall. Next, we perform detailed calculations on field-driven vortex domain walls. We find that the results for the voltage as a function of magnetic field differ between the one-dimensional and vortex domain wall. For the experimentally relevant case of a vortex domain wall, the dependence of voltage on field around Walker breakdown depends qualitatively on the ratio of the so-called β\beta-parameter to the Gilbert damping constant, and thus provides a way to determine this ratio experimentally. We also consider vortices on a magnetic disk in the presence of an AC magnetic field. In this case, the phase difference between field and voltage on the edge is determined by the β\beta parameter, providing another experimental method to determine this quantity.Comment: 8 pages, 9 figures, submitted to PR

    Influence of the interelectrode distance on the production of nanoparticles by means of atmospheric pressure inert gas DC glow discharge

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    This work is aimed at investigating the influence of the inter-electrode spacing on the production rate and size of nanoparticles generated by evaporating a cathode on an atmospheric pressure dc glow discharge. Experiments are conducted in the configuration of two vertically aligned cylindrical electrodes in upward coaxial flow with copper as a consumable cathode and nitrogen as a carrier gas. A constant current of 0.5 A is delivered to the electrodes and the inter-electrode distance spanned from 0.5 to 10 mm. Continuous stable nanoparticle production is attained by optimal coaxial flow convection cooling of the cathode. Both the particle production rate and the primary particle size increase with the inter-electrode spacing up to nearly 5 mm and strongly decrease with an increasing inter-electrode distance beyond 5 mm. Production rates in the range of 1 mg h-1 of very small nanoparticles

    Online-growth measurements on the generation of metal nanoaerosol and their offline structural properties

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    93-98Aerosol, which is intentionally generated in the laboratory, is utilized to synthesize nanoparticles. As the size of suspended nanoparticles in nano regime, therefore, purposely generated aerosol is termed as nanoaerosol. The present study demonstrates the formation metal nanoparticles in gas-phase. For this purpose, the initial condition; is to create nanoaerosol that is, suspension of tiny metal particles in gas. By evaporating a metal source in the presence of gas, creates the condition of supersaturation and then by nucleation and condensation forms stable nuclei, which grow in size to form primary particles in gas. A high-temperature furnace is utilized to evaporate metal e.g. palladium with 10% silver (PdAg), in the high purity nitrogen, is known as a carrier gas. During the sparking process, growth of the PdAg nanoaerosol is monitored online by a scanning mobility particle sizer, as a function of different parameters. Size-distribution in produced nanoaerosol shifts towards larger mobility equivalent diameter value from 7.83 to 42.6 nm along-with the increase in number concentration, on increasing the evaporation temperature from 1200 to 1400 °C. To study the effect of sintering temperature on particle size, size-fractionation by a differential mobility analyzer and in-flight sintering of PdAg nanoaerosol have been carried out. On increasing the sintering temperature, the size of selected PdAg nanoparticles reduces. The geometric mean mobility equivalent diameters of fractionated PdAg nanoparticles of 17.9, 25.3 and 30.9 nm reduces to 15.2, 19.4 and 21.7 nm, respectively, due to the compaction. The value of geometric standard deviation is approximately 1.10, which reflects the monodisperse nature of PdAg nanoparticles in the generated nanoaerosol. An electrostatic precipitation technique is utilized to separate out PdAg nanoparticles from nanoaerosol onto suitable substrates. Formation of spherical and mono-crystalline PdAg nanoparticles is revealed by TEM studies

    Aerosol Route to Antibacterial Nanosilver Coating of Cotton Fabrics

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    The paper describes a gas phase process for the preparation of cotton fabrics coated with silver nanoparticles as antimicrobial agents. Silver nanoparticles are synthesized by means of atmospheric pressure electrical discharges (spark discharge and glow discharge) in pure inert gases, and the aerosols are passed through cotton fabric samples, where nanoparticles deposit. The particle size distribution of the aerosols is measured online during synthesis. Also, the cristallinity, size and morphology of the silver particles are analyzed. The mean size of the primary particles of silver varies from 4 nm to 18 nm, depending upon the type of discharge, the nature and flow rate of the gas. The bactericidal activity of the cotton samples doped with silver nanoparticles is assessed following the ISO 20743 method. All cotton samples show significant bactericidal property, although it degrades with increasing primary particle size and particle agglomeration. This purely physical aerosol route is a promising sustainable method for nanocoating of textiles

    Hidden order in bosonic gases confined in one dimensional optical lattices

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    We analyze the effective Hamiltonian arising from a suitable power series expansion of the overlap integrals of Wannier functions for confined bosonic atoms in a 1d optical lattice. For certain constraints between the coupling constants, we construct an explicit relation between such an effective bosonic Hamiltonian and the integrable spin-SS anisotropic Heisenberg model. Therefore the former results to be integrable by construction. The field theory is governed by an anisotropic non linear σ\sigma-model with singlet and triplet massive excitations; such a result holds also in the generic non-integrable cases. The criticality of the bosonic system is investigated. The schematic phase diagram is drawn. Our study is shedding light on the hidden symmetry of the Haldane type for one dimensional bosons.Comment: 5 pages; 1 eps figure. Revised version, to be published in New. J. Phy

    Direct observation of incommensurate magnetism in Hubbard chains

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    The interplay between magnetism and doping is at the origin of exotic strongly correlated electronic phases and can lead to novel forms of magnetic ordering. One example is the emergence of incommensurate spin-density waves with a wave vector that does not match the reciprocal lattice. In one dimension this effect is a hallmark of Luttinger liquid theory, which also describes the low energy physics of the Hubbard model. Here we use a quantum simulator based on ultracold fermions in an optical lattice to directly observe such incommensurate spin correlations in doped and spin-imbalanced Hubbard chains using fully spin and density resolved quantum gas microscopy. Doping is found to induce a linear change of the spin-density wave vector in excellent agreement with Luttinger theory predictions. For non-zero polarization we observe a decrease of the wave vector with magnetization as expected from the Heisenberg model in a magnetic field. We trace the microscopic origin of these incommensurate correlations to holes, doublons and excess spins which act as delocalized domain walls for the antiferromagnetic order. Finally, when inducing interchain coupling we observe fundamentally different spin correlations around doublons indicating the formation of a magnetic polaron

    The M\u3csub\u3er\u3c/sub\u3e-value of chloroplast coupling factor 1

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    The Mr of spinach chloroplast coupling factor 1 has been determined by sedimentation equilibrium and by light scattering to be 400 000 ± 24 600 and 407 000 ± 20 000, respectively. These values differ substantially from that obtained previously (325 000) and are consistent with an α3β3γδε{lunate} subunit stoichiometry. © 1983

    The health economic impact of disease management programs for COPD: A systematic literature review and meta-analysis

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    __Abstract__ Background: There is insufficient evidence of the cost-effectiveness of Chronic Obstructive Pulmonary Disease (COPD) Disease Management (COPD-DM) programs. The aim of this review is to evaluate the economic impact of COPD-DM programs and investigate the relation between the impact on healthcare costs and health outcomes. We also investigated the impact of patient-, intervention, and study-characteristics.Methods: We conducted a systematic literature review to identify cost-effectiveness studies of COPD-DM. Where feasible, results were pooled using random-effects meta-analysis and explorative subgroup analyses were performed.Results: Sixteen papers describing 11 studies were included (7 randomized control trials (RCT), 2 pre-post, 2 case-control). Meta-analysis showed that COPD-DM led to hospitalization savings of €1060 (95% CI: €2040 to €80) per patient per year and savings in total healthcare uti

    European Society of Coloproctology: guidelines for the management of diverticular disease of the colon

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    The guideline was developed during several working phases including three voting rounds and one consensus meeting. The two project leads (JKS and EA) appointed by the ESCP guideline committee together with one member of the guideline committee (WB) agreed on the methodology, decided on six themes for working groups (WGs) and drafted a list of research questions. Senior WG members, mostly colorectal surgeons within the ESCP, were invited based on publication records and geographical aspects. Other specialties were included in the WGs where relevant. In addition, one trainee or PhD fellow was invited in each WG. All six WGs revised the research questions if necessary, did a literature search, created evidence tables where feasible, and drafted supporting text to each research question and statement. The text and statement proposals from each WG were arranged as one document by the first and last authors before online voting by all authors in two rounds. For the second voting ESCP national representatives were also invited. More than 90% agreement was considered a consensus. The final phrasing of the statements with < 90% agreement was discussed in a consensus meeting at the ESCP annual meeting in Vienna in September 2019. Thereafter, the first and the last author drafted the final text of the guideline and circulated it for final approval and for a third and final online voting of rephrased statements

    Major differences in clinical presentation, diagnosis and management of men and women with autosomal inherited bleeding disorders

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    Background: In recent years, more awareness is raised about sex-specific dilemmas in inherited bleeding disorders. However, no large studies have been performed to assess differences in diagnosis, bleeding phenotype and management of men and women with bleeding disorders. Therefore, we investigated sex differences in a large cohort of well-defined patients with autosomal inherited bleeding disorders (von Willebrand disease (VWD), rare bleeding disorders (RBDs) and congenital platelet defects (CPDs)).Methods: We included patients from three nationwide cross-sectional studies on VWD, RBDs and CPDs in the Netherlands, respectively the WiN, RBiN and TiN study. In all studies a bleeding score (BS) was obtained, and patients filled in an extensive questionnaire on the management and burden of their disorder.Findings: We included 1092 patients (834 VWD; 196 RBD; 62 CPD), of whom 665 (60.9%) were women. Women were more often referred because of a bleeding diathesis than men (47.9% vs 36.6%, p = 0.002). Age of first bleeding was similar between men and women, respectively 8.9 +/- 13.6 (mean +/- sd) years and 10.6 +/- 11.3 years (p = 0.075). However, the diagnostic delay, which was defined as time from first bleeding to diagnosis, was longer in women (11.6 +/- 16.4 years) than men (7.7 +/- 16.6 years, p = 0.002). Similar results were found when patients referred for bleeding were analyzed separately. Of women aging 12 years or older, 469 (77.1%) had received treatment because of sex-specific bleeding.Interpretation: Women with autosomal inherited bleeding disorders are more often referred for bleeding, have a longer diagnostic delay, and often require treatment because of sex-specific bleeding. (C) 2021 The Authors. Published by Elsevier Ltd.Clinical epidemiolog
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