3,909 research outputs found
Optimized stray-field-induced enhancement of the electron spin precession by buried Fe gates
The magnetic stray field from Fe gates is used to modify the spin precession
frequency of InGaAs/GaAs quantum-well electrons in an external magnetic field.
By using an etching process to position the gates directly in the plane of the
quantum well, the stray-field influence on the spin precession increases
significantly compared with results from previous studies with top-gated
structures. In line with numerical simulations, the stray-field-induced
precession frequency increases as the gap between the ferromagnetic gates is
reduced. The inhomogeneous stray field leads to additional spin dephasing.Comment: 4 pages, 2 figure
Weak formulation for singular diffusion equation with dynamic boundary condition
In this paper, we propose a weak formulation of the singular diffusion
equation subject to the dynamic boundary condition. The weak formulation is
based on a reformulation method by an evolution equation including the
subdifferential of a governing convex energy. Under suitable assumptions, the
principal results of this study are stated in forms of Main Theorems A and B,
which are respectively to verify: the adequacy of the weak formulation; the
common property between the weak solutions and those in regular problems of
standard PDEs.Comment: 23 page
Two Approaches to Dislocation Nucleation in the Supported Heteroepitaxial Equilibrium Islanding Phenomenon
We study the dislocation formation in 2D nanoscopic islands with two methods,
the Molecular Static method and the Phase Field Crystal method. It is found
that both methods indicate the same qualitative stages of the nucleation
process. The dislocations nucleate at the film-substrate contact point and the
energy decreases monotonously when the dislocations are farther away from the
island-wetting film contact points than the distance of the highest energy
barrier.Comment: 4 page
The Incidence of Arterial Stent Fractures with Exclusion of Coronary, Aortic, and Non-arterial Settings
Background: This study aimed to review the literature regarding fracture of arterial stents, especially its relation to location of placement, clinical relevance, and type of stents. Material and methods: We searched published articles in PubMed up to February 2008 by using the terms: stent fracture or stent breakage. Results: Thirty-one articles met our inclusion and exclusion criteria. Most of the studies reported fractures in stents placed in the superficial femoral artery or popliteal arteries. The cumulative incidence of stent fractures ranged from 2% to 65%, i.e. 0.6 to 60 per 1000 person-months. Stent fractures occur more frequently in the superficial femoral artery and are common when multiple stents are deployed and overlap. Stent fractures are associated with a higher risk of in-stent restenosis and re-occlusion. Conclusion: The incidence of stent fracture, its location of placement, and type of stent used were diverse across studies. Stent fracture may cause clinical deterioration especially in the femoropopliteal segment, and it should be detected before clinical manifestation appears. Further studies with larger study population involving new type of stents for a longer follow up period are warranted.Peer reviewe
Electronic in-plane symmetry breaking at field-tuned quantum criticality in CeRhIn5
Electronic nematics are exotic states of matter where electronic interactions
break a rotational symmetry of the underlying lattice, in analogy to the
directional alignment without translational order in nematic liquid crystals.
Intriguingly such phases appear in the copper- and iron-based superconductors,
and their role in establishing high-temperature superconductivity remains an
open question. Nematicity may take an active part, cooperating or competing
with superconductivity, or may appear accidentally in such systems. Here we
present experimental evidence for a phase of nematic character in the heavy
fermion superconductor CeRhIn5. We observe a field-induced breaking of the
electronic tetragonal symmetry of in the vicinity of an antiferromagnetic (AFM)
quantum phase transition at Hc~50T. This phase appears in out-of-plane fields
of H*~28T and is characterized by substantial in-plane resistivity anisotropy.
The anisotropy can be aligned by a small in-plane field component, with no
apparent connection to the underlying crystal structure. Furthermore no
anomalies are observed in the magnetic torque, suggesting the absence of
metamagnetic transitions in this field range. These observations are indicative
of an electronic nematic character of the high field state in CeRhIn5. The
appearance of nematic behavior in a phenotypical heavy fermion superconductor
highlights the interrelation of nematicity and unconventional
superconductivity, suggesting nematicity to be a commonality in such materials
Affinities and Beyond! Developing Ways of Seeing in Online Spaces
This article presents an insider view of an online community of adults involved in sharing digital photography through a host website, Flickr. It describes how reciprocal teaching and learning partnerships in a dynamic multimodal environment are achieved through the creation of a ‘Third Space’ or ‘Affinity Space’, where ‘Funds of Knowledge’ are shared and processed in such a way that new meanings and discourses are generated. It is argued that this process is evidence of valuable learning and of the deepening of global understandings within the local space of Flickr. The new understandings are at least partly identifiable on the Flickr space, through the co-constructed ‘folksonomy’ or ‘online taxonomy’ of ways of looking at the world. Further, the article provides evidence for broadening existing definitions of literacy, at a time when the visual mode increasingly works interactively with verbal cues and explanations
{Rearrangement of the antiferromagnetic ordering at high magnetic fields in SmFeAsO and SmFeAsOF single crystals
The low-temperature antiferromagnetic state of the Sm-ions in both
nonsuperconducting SmFeAsO and superconducting SmFeAsOF single
crystals was studied by magnetic torque, magnetization, and magnetoresistance
measurements in magnetic fields up to 60~T and temperatures down to 0.6~K. We
uncover in both compounds a distinct rearrangement of the antiferromagnetically
ordered Sm-moments near ~T. This is seen in both, static and pulsed
magnetic fields, as a sharp change in the sign of the magnetic torque, which is
sensitive to the magnetic anisotropy and hence to the magnetic moment in the
-plane, ({\it i.e.} the FeAs-layers), and as a jump in the magnetization
for magnetic fields perpendicular to the conducting planes. This rearrangement
of magnetic ordering in ~T is essentially temperature independent and
points towards a canted or a partially polarized magnetic state in high
magnetic fields. However, the observed value for the saturation moment above
this rearrangement, suggests that the complete suppression of the
antiferromagnetism related to the Sm-moments would require fields in excess of
60~T. Such a large field value is particularly remarkable when compared to the
relatively small N\'{e}el temperature ~K, suggesting very
anisotropic magnetic exchange couplings. At the transition, magnetoresistivity
measurements show a crossover from positive to negative field-dependence,
indicating that the charge carriers in the FeAs planes are sensitive to the
magnetic configuration of the rare-earth elements. This is indicates a finite
magnetic/electronic coupling between the SmO and the FeAs layers which are
likely to mediate the exchange interactions leading to the long range
antiferromagnetic order of the Sm ions.Comment: 10 pages, 7 figures, accepted in Phys. Rev.
Teaching Strategies: Teaching Beyond the Basics: Young Children Participate in a Cognitive Apprenticeship: Tunde Szecsi, Editor
Community members have a variety of funds of knowledge they could contribute as specialists in collaborative experiences with teachers. Yet, despite having such invaluable culture capital, speciali..
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