336,312 research outputs found
Probing spin entanglement by gate-voltage-controlled interference of current correlation in quantum spin Hall insulators
We propose an entanglement detector composed of two quantum spin Hall
insulators and a side gate deposited on one of the edge channels. For an ac
gate voltage, the differential noise contributed from the entangled electron
pairs exhibits the nontrivial step structures, from which the spin entanglement
concurrence can be easily obtained. The possible spin dephasing effects in the
quantum spin Hall insulators are also included.Comment: Physics Letters A in pres
Real-space renormalization group study of the Hubbard model on a non-bipartite lattice
We present the real-space block renormalization group equations for fermion
systems described by a Hubbard Hamiltonian on a triangular lattice with
hexagonal blocks. The conditions that keep the equations from proliferation of
the couplings are derived. Computational results are presented including the
occurrence of a first-order metal-insulator transition at the critical value of
Effect of carrot puree edible films on quality preservation of fresh-cut carrots
peer-reviewedFinancial support from the high level talent fund of Henan University of Technology Science and Technology (No. 2012BS024) is gratefully acknowledged.The effect of edible films based on carrot puree, chitosan, corn starch, gelatin, glycerol and cinnamaldehyde on fresh-cut carrots was studied during storage. Several parameters, such as firmness, colour, weight loss, total carotenoids, total phenols, polyphenol oxidase (PPO) activity and peroxidase (POD) activity in coated carrots were determined at regular intervals and then compared with the uncoated carrots throughout the storage period. Significant and expected changes were observed in all carrot samples that were compared. The coating treatment significantly (P < 0.05) delayed the senescence, reduced the deterioration of exterior quality and retained total carotenoids well compared with control (P < 0.05). In addition, significant inhibition of PPO activity (P < 0.05) and POD activity (P < 0.05) as well as reduced accumulation of polyphenols (P < 0.05) were observed for all coated samples. All of these favourable responses induced by coating treatment on minimally processed fresh-cut carrots showed beneficial physiological effects, which would give some useful references to the fresh-cut fruit and vegetable processing industry and satisfy people’s requirements allowing for extending product shelf life without negatively affecting the sensory quality or acceptability.Henan University of Technology Science and Technolog
Comment on "Absence of trapped surfaces and singularities in cylindrical collapse"
Recently, the gravitational collapse of an infinite cylindrical thin shell of
matter in an otherwise empty spacetime with two hypersurface orthogonal Killing
vectors was studied by Gon\c{c}alves [Phys. Rev. {\bf D65}, 084045 (2002).]. By
using three "alternative" criteria for trapped surfaces, the author claimed to
have shown that {\em they can never form either outside or on the shell,
regardingless of the matter content for the shell, except at asymptotical
future null infinite}.
Following Penrose's original idea, we first define trapped surfaces in
cylindrical spacetimes in terms of the expansions of null directions orthogonal
to the surfaces, and then show that the first criterion used by Gon\c{c}alves
is incorrect. We also show that his analysis of non-existence of trapped
surfaces in vacuum is incomplete. To confirm our claim, we present an example
that is a solution to the vacuum Einstein field equations and satisfies all the
regular conditions imposed by Gon\c{c}alves. After extending the solution to
the whole spacetime, we show explicitly that trapped surfaces exist in the
extended region.Comment: latex, 2 figures, the last version to appear in Phys. Rev.
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