5,506 research outputs found
Electron Beam Supercollimation in Graphene Superlattices
Although electrons and photons are intrinsically different, importing useful
concepts in optics to electronics performing similar functions has been
actively pursued over the last two decades. In particular, collimation of an
electron beam is a long-standing goal. We show that ballistic propagation of an
electron beam with virtual no spatial spreading or diffraction, without a
waveguide or external magnetic field, can be achieved in graphene under an
appropriate class of experimentally feasible one-dimensional external periodic
potentials. The novel chiral quasi-one-dimensional metallic state that the
charge carriers are in originates from a collapse of the intrinsic helical
nature of the charge carriers in graphene owing to the superlattice potential.
Beyond providing a new way to constructing chiral one-dimensional states in two
dimensions, our findings should be useful in graphene-based electronic devices
(e.g., for information processing) utilizing some of the highly developed
concepts in optics.Comment: 7 pages, 4 figures (including supporting online material), published
online in Nano Letter
New Generation of Massless Dirac Fermions in Graphene under External Periodic Potentials
We show that new massless Dirac fermions are generated when a slowly varying
periodic potential is applied to graphene. These quasiparticles, generated near
the supercell Brillouin zone boundaries with anisotropic group velocity, are
different from the original massless Dirac fermions. The quasiparticle
wavevector (measured from the new Dirac point), the generalized pseudospin
vector, and the group velocity are not collinear. We further show that with an
appropriate periodic potential of triangular symmetry, there exists an energy
window over which the only available states are these quasiparticles, thus,
providing a good system to probe experimentally the new massless Dirac
fermions. The required parameters of external potentials are within the realm
of laboratory conditions.Comment: 4 pages, 4 figure
Selenoprotein W promotes cell cycle recovery from G2 arrest through the activation of CDC25B
AbstractSelenoprotein W (SelW) contains a highly reactive selenocysteine (Sec; U) in the CXXU motif corresponding to the CXXC motif in thioredoxin (Trx) and thus it appears to be involved in regulating the cellular redox state. Recent reports on the interaction between SelW and 14-3-3 suggest that SelW may be redox dependently involved in the cell cycle. However, the precise function of SelW has not yet been elucidated. Here, we show that SelW is involved in the G2–M transition, especially in the recovery from G2 arrest after deoxyribonucleic acid (DNA) damage. Knockdown of SelW significantly accumulated phosphorylated cyclin‐dependent kinase (Cdk1), which eventually led to a delay in recovery from G2 arrest. We also found that inactive Cdk1 is caused by the sustained inactivation of CDC25B, which removes the inhibitory phosphate from Cdk1. Our observation from this study reveals that SelW activated CDC25B by promoting the dissociation of 14-3-3 from CDC25B through the reduction of the intramolecular disulfide bond during recovery. We suggest that SelW plays an important role in the recovery from G2 arrest by determining the dissociation of 14-3-3 from CDC25B in a redox-dependent manner
Photo Quality Assessment based on a Focusing Map to Consider Shallow Depth of Field
Proliferation and advances in digital cameras encourage people to take many photos. However, the number of photos that
people can access is increasing exponentially. Good quality photo selection is becoming burdensome. In this paper, we propose
a novel method to evaluate photo quality considering DoF (Depth of Field) based on a focusing map. The focusing map is a
form of saliency map classified into four levels based on the spatial distribution of Canny edges. We implemented it in a CUDA
environment to improve the speed of focusing map generation. In order to evaluate our method, we tested our feature on the
four classified 206 photos; then, we compare our method to a photo set manually classified by a user. The proposed measure
efficiently assesses the photos with DoF. Especially, the expert group who used DSLR camera agreed that our photo assessment
measure is useful
Coderivations of Ranked Bigroupoids
The notion of (co)derivations of ranked bigroupoids is discussed by Alshehri et al. (in press), and their generalized version is studied by Jun et al. (under review press). In particular, Jun et al. (under review press) studied coderivations of ranked bigroupoids. In this paper, the generalization of coderivations of ranked bigroupoids is discussed. The notion of generalized coderivations in ranked bigroupoids is introduced, and new generalized coderivations of ranked bigroupoids are obtained by combining a generalized self-coderivation with a rankomorphism. From the notion of (X,∗,&)-derivation, the existence of a rankomorphism of ranked bigroupoids is established
Hypervector Spaces Based on Intersectional Soft Sets
The notion of int-soft subfields, int-soft algebras over int-soft subfields, and int-soft hypervector spaces are introduced, and their properties and characterizations are considered. In connection with linear transformations, int-soft hypervector spaces are discussed
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