Search results for "fields"

Minimal unit vector fields

2002

We compute the first variation of the functional that assigns each unit vector field the volume of its image in the unit tangent bundle. It is shown that critical points are exactly those vector fields that determine a minimal immersion. We also find a necessary and sufficient condition that a vector field, defined in an open manifold, must fulfill to be minimal, and obtain a simpler equivalent condition when the vector field is Killing. The condition is fulfilled, in particular, by the characteristic vector field of a Sasakian manifold and by Hopf vector fields on spheres.

Correlation between spin structure oscillations and domain wall velocities

2013

Magnetic sensing and logic devices based on the motion of magnetic domain walls rely on the precise and deterministic control of the position and the velocity of individual magnetic domain walls in curved nanowires. Varying domain wall velocities have been predicted to result from intrinsic effects such as oscillating domain wall spin structure transformations and extrinsic pinning due to imperfections. Here we use direct dynamic imaging of the nanoscale spin structure that allows us for the first time to directly check these predictions. We find a new regime of oscillating domain wall motion even below the Walker breakdown correlated with periodic spin structure changes. We show that the e…

Slow Magnetic Relaxation in a Co (II)–Y (III) Single‐Ion Magnet with Positive Axial Zero‐Field Splitting

2013

This work was supported by the MINECO (Spain) (Project CTQ2011-24478), the Junta de Andalucía (FQM-195 and Project of excellence P08-FQM-03705), and the University of Granada. E.R. and E.Cr. thank MINECO grant No. CTQ2011-23862-C02-01 and Generalitat de Catalunya grant No. 2009SGR-1459, for financial support. We would like to thank Prof. Liviu Chibotaru for providing us the SINGLE_ANISO program and Dr. Andrew Ozarowski for the EPR simulation software. E.K.B. thanks the EPSRC and Leverhulme Trust for financial support. The NHMFL is funded by the NSF, DoE, and the state of Florida. J.C. acknowledges financial support by the Spanish Ministerio de Ciencia e Innovación through projects CTQ2010-1…

Untangling knowledge fields and knowledge dynamics within the decision-making process

2020

PurposeThe purpose of this paper is to analyse the influences of different types of knowledge and their inherent dynamics on the effectiveness of the decision-making (DM) process. Knowledge dynamics (KD) is envisioned through the lens of the knowledge fields theory while effective DM process is objectivised via organisational appreciation and reward, higher business performance, sustainable partnerships and managerial satisfaction with previous achievements.Design/methodology/approachA questionnaire-based survey was conducted with 275 middle managers from companies operating in the business consulting field. The conceptual and structural model was tested using the partial least squares stru…

A wavelet operator in solving electromagnetic fields equations in time domain

2010

Ferromagnetic dinuclear mixed-valence Mn(II)/Mn(III) complexes: building blocks for the higher nuclearity complexes. structure, magnetic properties, …

2013

A series of six mixed-valence Mn(II)/Mn(III) dinuclear complexes were synthesized and characterized by X-ray diffraction. The reactivity of the complexes was surveyed, and structures of three additional trinuclear mixed-valence Mn(III)/Mn(II)/Mn(III) species were resolved. The magnetic properties of the complexes were studied in detail both experimentally and theoretically. All dinuclear complexes show ferromagnetic intramolecular interactions, which were justified on the basis of the electronic structures of the Mn(II) and Mn(III) ions. The large Mn(II)-O-Mn(III) bond angle and small distortion of the Mn(II) cation from the ideal square pyramidal geometry were shown to enhance the ferromag…

Accelerating wide-angle converging waves in the near field

2014

We show that a wide-angle converging wave may be transformed into a shape-preserving accelerating beam having a beam-width near the diffraction limit. For that purpose, we followed a strategy that is particularly conceived for the acceleration of nonparaxial laser beams, in contrast to the well-known method by Siviloglou et al (2007 Phys. Rev. Lett. 99 213901). The concept of optical near-field shaping is applied to the design of non-flat ultra-narrow diffractive optical elements. The engineered curvilinear caustic can be set up by the beam emerging from a dynamic assembly of elementary gratings, the latter enabling to modify the effective refractive index of the metamaterial as it is arran…

Generic unfoldings with the same bifurcation diagram which are not (C0, C0)— equivalent

1997

Computing generators of the tame kernel of a global function field

2006

Abstract The group K 2 of a curve C over a finite field is equal to the tame kernel of the corresponding function field. We describe two algorithms for computing generators of the tame kernel of a global function field. The first algorithm uses the transfer map and the fact that the l -torsion can easily be described if the ground field contains the l th roots of unity. The second method is inspired by an algorithm of Belabas and Gangl for computing generators of K 2 of the ring of integers in a number field. We finally give the generators of the tame kernel for some elliptic function fields.

Tevatron Run II combination of the effective leptonic electroweak mixing angle

2018

The Ministry of Science and Innovation and the Consolider-Ingenio 2010 Program and the European Union community Marie Curie Fellowship Contract No. 302103.