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https://www.readbyqxmd.com/read/29352175/magnetic-vortices-as-efficient-nano-heaters-in-magnetic-nanoparticle-hyperthermia
#1
N A Usov, M S Nesmeyanov, V P Tarasov
Magnetic vortices existing in soft magnetic nanoparticles with sizes larger than the single-domain diameter can be efficient nano-heaters in biomedical applications. Using micromagnetic numerical simulation we prove that in the optimal range of particle diameters the magnetization reversal of the vortices in spherical iron and magnetite nanoparticles is possible for moderate amplitudes of external alternating magnetic field, H0 < 100 Oe. In contrast to the case of superparamagnetic nanoparticles, for the vortex configuration the hysteresis loop area increases as a function of frequency...
January 19, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29352144/pressure-assisted-enhancement-in-superconducting-properties-of-fe-substituted-nbse2-single-crystal
#2
Manikandan Krishnan, Rukshana Pervin, Kalai Selvan Ganesan, Kannan Murugesan, Govindaraj Lingannan, Akshay Kumar Verma, Parasharam M Shirage, Arumugam Sonachalam
The impact of hydrostatic pressure (P) up to 1 GPa on T c , J c and the nature of the pinning mechanism in FexNbSe2 single crystals have been investigated within the framework of the collective theory. We found that the pressure can induce a transition from the regime where pinning is controlled by spatial variation in the critical transition temperature (δT c ) to the regime controlled by spatial variation in the mean free path (δℓ). Furthermore, T c and low field J c are slightly induced, although the J c drops more rapidly at high fields than at ambient P...
January 19, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29347810/plasma-q-plate-for-generation-and-manipulation-of-intense-optical-vortices
#3
Kenan Qu, Qing Jia, Nathaniel J Fisch
An optical vortex is a light wave with a twisting wavefront around its propagation axis and null intensity in the beam center. Its unique spatial structure of field lends itself to a broad range of applications, including optical communication, quantum information, superresolution microscopy, and multidimensional manipulation of particles. However, accessible intensity of optical vortices have been limited to material ionization threshold. This limitation might be removed by using the plasma medium. Here we propose the design of suitably magnetized plasmas which, functioning as a q-plate, leads to a direct conversion from a high-intensity Gaussian beam into a twisted beam...
November 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347763/rayleigh-taylor-instability-and-vortex-rings-in-coupled-gross-pitaevskii-equations
#4
Hidetsugu Sakaguchi, Hiroomi Chono
The Rayleigh-Taylor instability is a gravitational instability in two fluids where the heavier fluid is set over the lighter fluid. The instability occurs both in classical fluids and quantum fluids. We numerically study the Rayleigh-Taylor instability using coupled Gross-Pitaevskii equations for two-component Bose-Einstein condensates. We carry out numerical simulations that the heavier component is set in a torus initially which is surrounded by the lighter component. When the torus falls, the Rayleigh-Taylor instability develops and a sagging pattern appears...
November 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347682/front-propagation-in-a-regular-vortex-lattice-dependence-on-the-vortex-structure
#5
E Beauvier, S Bodea, A Pocheau
We investigate the dependence on the vortex structure of the propagation of fronts in stirred flows. For this, we consider a regular set of vortices whose structure is changed by varying both their boundary conditions and their aspect ratios. These configurations are investigated experimentally in autocatalytic solutions stirred by electroconvective flows and numerically from kinematic simulations based on the determination of the dominant Fourier mode of the vortex stream function in each of them. For free lateral boundary conditions, i...
November 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347532/dual-lattice-functional-renormalization-group-for-the-berezinskii-kosterlitz-thouless-transition-irrelevance-of-amplitude-and-out-of-plane-fluctuations
#6
Jan Krieg, Peter Kopietz
We develop a functional renormalization group (FRG) approach for the two-dimensional XY model by combining the lattice FRG proposed by Machado and Dupuis [Phys. Rev. E 82, 041128 (2010)PLEEE81539-375510.1103/PhysRevE.82.041128] with a duality transformation that explicitly introduces vortices via an integer-valued field. We show that the hierarchy of FRG flow equations for the infinite set of relevant and marginal couplings of the model can be reduced to the well-known Kosterlitz-Thouless renormalization group equations for the renormalized temperature and the vortex fugacity...
October 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347458/emergent-dynamic-structures-and-statistical-law-in-spherical-lattice-gas-automata
#7
Zhenwei Yao
Various lattice gas automata have been proposed in the past decades to simulate physics and address a host of problems on collective dynamics arising in diverse fields. In this work, we employ the lattice gas model defined on the sphere to investigate the curvature-driven dynamic structures and analyze the statistical behaviors in equilibrium. Under the simple propagation and collision rules, we show that the uniform collective movement of the particles on the sphere is geometrically frustrated, leading to several nonequilibrium dynamic structures not found in the planar lattice, such as the emergent bubble and vortex structures...
December 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347323/evolution-of-inverse-cascades-and-formation-of-precondensate-in-gross-pitaevskii-turbulence-in-two-dimensions
#8
Natalia Vladimirova
Here we study how coherence appears in a system driven by noise at small scales. In the wave turbulence modeled by the Gross-Pitaevskii or the nonlinear Schrödinger equation, we observe states with correlation scales smaller than the system size but much larger than the excitation scale. We call a such state precondensate to distinguish it from condensate defined as a systemwide coherent state. Both condensate and precondensate are characterized by large-scale phase coherence and a narrow distribution of amplitudes...
December 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347269/length-of-excitable-knots
#9
Fabian Maucher, Paul Sutcliffe
In this paper, we present extensive numerical simulations of an excitable medium to study the long-term dynamics of knotted vortex strings for all torus knots up to crossing number 11. We demonstrate that FitzHugh-Nagumo evolution preserves the knot topology for all the examples presented, thereby providing a field theory approach to the study of knots. Furthermore, the evolution yields a well-defined minimal length for each knot that is comparable to the ropelength of ideal knots. We highlight the role of the medium boundary in stabilizing the length of the knot and discuss the implications beyond torus knots...
July 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347084/identifying-the-linear-phase-of-the-relativistic-kelvin-helmholtz-instability-and-measuring-its-growth-rate-via-radiation
#10
R Pausch, M Bussmann, A Huebl, U Schramm, K Steiniger, R Widera, A Debus
For the relativistic Kelvin-Helmholtz instability (KHI), which occurs at shear interfaces between two plasma streams, we report results on the polarized radiation over all observation directions and frequencies emitted by the plasma electrons from ab initio kinetic simulations. We find the polarization of the radiation to provide a clear signature for distinguishing the linear phase of the KHI from its other phases. During the linear phase, we predict the growth rate of the KHI radiation power to match the growth rate of the KHI to a high degree...
July 2017: Physical Review. E
https://www.readbyqxmd.com/read/29345950/confined-electroconvective-vortices-at-structured-ion-exchange-membranes
#11
Joeri de Valença, Morten Jõgi, R Martijn Wagterveld, Elif Karatay, Jeffery A Wood, Rob G H Lammertink
In this paper, we investigate electroconvective ion transport at cation exchange membranes with different geometry square-wave structures (line undulations) experimentally and numerically. Electroconvective micro-vortices are induced by strong concentration polarization once a threshold potential difference is applied. The applied potential required to start and sustain electroconvection is strongly affected by the geometry of the membrane. A reduction in the resistance of approximately 50% can be obtained when the structure size is similar to the mixing layer thickness, resulting in confined vortices with less lateral motion compared to the case of flat membranes...
January 18, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29345472/current-driven-motion-of-domain-boundaries-between-skyrmion-lattice-and-helical-magnetic-structure
#12
Kiyou Shibata, Toshiaki Tanigaki, Tetsuya Akashi, Hiroyuki Shinada, Ken Harada, Kodai Niitsu, Daisuke Shindo, Naoya Kanazawa, Yoshinori Tokura, Taka-Hisa Arima
To utilize magnetic skyrmions, nano-scale vortex-like magnetic structure, experimental elucidation of their dynamics against current application in various circumstances such as in confined structure and mixture of different magnetic phases is indispensable. Here, we investigate the current-induced dynamics of the coexistence state of magnetic skyrmions and helical magnetic structure in a thin plate of B20-type helimagnet FeGe in terms of in-situ realspace observation using Lorentz transmission electron microscopy (TEM)...
January 18, 2018: Nano Letters
https://www.readbyqxmd.com/read/29344479/mechanisms-of-optic-nerve-invasion-in-primary-choroidal-melanoma
#13
Eszter Szalai, Jill R Wells, Hans E Grossniklaus
Aim: The aim of this study was to assess morphological risk factors associated with optic nerve invasion of choroidal melanoma and to identify possible mechanisms of optic nerve invasion. Methods: Medical charts and histology slides of patients with primary choroidal melanoma who were treated by enucleation/exenteration and whose pathology showed optic nerve invasion were reviewed. Results: Twenty-one patients (mean age: 65.67 ± 14.72 years) with primary uveal melanoma arising from the choroid were included in this analysis...
November 2017: Ocular Oncology and Pathology
https://www.readbyqxmd.com/read/29343632/correction-to-dynamics-of-phytoplankton-blooms-in-turbulent-vortex-cells
#14
Christian Lindemann, Andre Visser, Patrizio Mariani
No abstract text is available yet for this article.
January 2018: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/29341756/generic-theory-for-majorana-zero-modes-in-2d-superconductors
#15
Cheung Chan, Lin Zhang, Ting Fung Jeffrey Poon, Ying-Ping He, Yan-Qi Wang, Xiong-Jun Liu
It is well known that non-Abelian Majorana zero modes (MZM) are located at vortex cores in a p_{x}+
July 28, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29339740/understanding-turbulent-free-surface-vortex-flows-using-a-taylor-couette-flow-analogy
#16
Sean Mulligan, Giovanni De Cesare, John Casserly, Richard Sherlock
Free-surface vortices have long been studied to develop an understanding of similar rotating flow phenomena observed in nature and technology. However, a complete description of its turbulent three-dimensional flow field still remains elusive. In contrast, the related Taylor-Couette flow system has been well explicated which classically exhibits successive instability phases manifested in so-called Taylor vortices. In this study, observations made on the turbulent free-surface vortex revealed distinguishable, time-dependent "Taylor-like" vortices in the secondary flow field similar to the Taylor-Couette flow system...
January 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29337318/homes-for-plants-and-microbes-a-phenotyping-approach-with-quantitative-control-of-signaling-between-organisms-and-their-individual-environments
#17
Oskar Siemianowski, Kara R Lind, Xinchun Tian, Matt Cain, Songzhe Xu, Baskar Ganapathysubramanian, Ludovico Cademartiri
We describe a simple, scalable, modular, and frugal approach to create model ecosystems as millifluidic networks of interconnected habitats (hosting microbes or plants), which offers (i) quantitative and dynamic control over the exchange of chemicals between habitats, and (ii) independent control over their environment. Oscillatory laminar flows produce regions of vortex mixing around obstacles. When these overlap, rapid mass transport by dispersion occurs, which is quantitatively describable as diffusion, but is directional and tunable in rate over 3 orders of magnitude...
January 16, 2018: Lab on a Chip
https://www.readbyqxmd.com/read/29335710/continuous-flow-trapping-and-localized-enrichment-of-micro-and-nano-particles-using-induced-charge-electrokinetics
#18
Cunlu Zhao, Chun Yang
In this work, we report an effective microfluidic technique for continuous-flow trapping and localized enrichment of micro- and nano-particles by using induced-charge electrokinetic (ICEK) phenomena. The proposed technique utilizes a simple microfluidic device that consists of a straight microchannel and a conducting strip attached to the bottom wall of the microchannel. Upon application of the electric field along the microchannel, the conducting strip becomes polarized to introduce two types of ICEK phenomena, the ICEK flow vortex and particle dielectrophoresis, and they are identified by a theoretical model formulated in this study to be jointly responsible for the trapping of particles over the edge of the conducting strip...
January 16, 2018: Soft Matter
https://www.readbyqxmd.com/read/29335470/stratospheric-ozone-loss-over-the-eurasian-continent-induced-by-the-polar-vortex-shift
#19
Jiankai Zhang, Wenshou Tian, Fei Xie, Martyn P Chipperfield, Wuhu Feng, Seok-Woo Son, N Luke Abraham, Alexander T Archibald, Slimane Bekki, Neal Butchart, Makoto Deushi, Sandip Dhomse, Yuanyuan Han, Patrick Jöckel, Douglas Kinnison, Ole Kirner, Martine Michou, Olaf Morgenstern, Fiona M O'Connor, Giovanni Pitari, David A Plummer, Laura E Revell, Eugene Rozanov, Daniele Visioni, Wuke Wang, Guang Zeng
The Montreal Protocol has succeeded in limiting major ozone-depleting substance emissions, and consequently stratospheric ozone concentrations are expected to recover this century. However, there is a large uncertainty in the rate of regional ozone recovery in the Northern Hemisphere. Here we identify a Eurasia-North America dipole mode in the total column ozone over the Northern Hemisphere, showing negative and positive total column ozone anomaly centres over Eurasia and North America, respectively. The positive trend of this mode explains an enhanced total column ozone decline over the Eurasian continent in the past three decades, which is closely related to the polar vortex shift towards Eurasia...
January 15, 2018: Nature Communications
https://www.readbyqxmd.com/read/29335455/publisher-correction-trapping-and-manipulation-of-nanoparticles-using-multifocal-optical-vortex-metalens
#20
Yanbao Ma, Guanghao Rui, Bing Gu, Yiping Cui
A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.
January 15, 2018: Scientific Reports
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