12,217 research outputs found
Splitting of Surface Plasmon Frequencies of Metal Particles in a Nematic Liquid Crystal
We calculate the effective dielectric function for a suspension of small
metallic particles immersed in a nematic liquid crystal (NLC) host. For a
random suspension of such particles in the dilute limit, we calculate the
effective dielectric tensor exactly and show that the surface plasmon
(SP)resonance of such particles splits into two resonances, polarized parallel
and perpendicular to the NLC director. At higher concentrations, we calculate
this splitting using a generalized Maxwell-Garnett approximation, which can
also be applied to a small metal particle coated with NLC. To confirm the
accuracy of the MGA for NLC-coated spheres, we also use the Discrete Dipole
Approximation. The calculated splitting is comparable to that observed in
recent experiments on NLC-coated small metal particlesComment: 11 pages, 2 figures. To be published in Appl. Phys. Let
In-gap bound states and tunneling conductance of multiband superconductors through a normal/superconductor/superconductor junction
The tunneling conductance between a metal and a multiband s-wave
superconductor with a thin layer of single-band s-wave superconductor
sandwiched in between is examined in this paper. We show that an in-gap peak in
conductance curve is found as a result of the formation of in-gap bound state
between the single-band and multiband superconductor junctions if the phases of
the superconducting order parameters of the multiband superconductor are
frustrated. The implication of this result in determining the gap symmetry of
the iron-based superconductors is discussed.Comment: 5 pages, 5 figure
Influence of Dzyaloshinskii-Moriya interactions on magnetic structure of a spin-1/2 deformed kagome lattice antiferromagnet
Motivated by the recent neutron scattering experiment on Rb2Cu3SnF12 [Nat.
Phys. 6, 865 (2010)], we investigate the effect of Dzyaloshinskii-Moriya
interactions in a theoretical model for the magnetic structure of this
material. Considering the valence bond solid ground state, which has a 12-site
unit cell, we develop the bond operator mean-field theory. It is shown that the
Dzyaloshinskii-Moriya interactions significantly modify the triplon dispersions
around the Gamma point and cause a shift of the spin gap (the minimum triplon
gap) position from the K to Gamma point in the first Brilloin zone. The spin
gap is also evaluated in exact diagonalization studies on a 24-site cluster. We
discuss a magnetic transition induced by the Dzyaloshinskii-Moriya interactions
in the bond operator framework. Moreover, the magnetization process under
external magnetic fields is studied within the exact diagonalization and strong
coupling expansion approaches. We find that the results of all above approaches
are consistent with the experimental findings.Comment: 14 pages, 10 figures; typos corrected, and acknowledgements and
references adde
Real photons produced from photoproduction in collisions
We calculate the production of real photons originating from the
photoproduction in relativistic collisions. The
Weizscker-Williams approximation in the photoproduction is
considered. Numerical results agree with the experimental data from
Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC). We find
that the modification of the photoproduction is more prominent in large
transverse momentum region.Comment: 2 figure
Quit playing games with my heart: Understanding online dating scams
© Springer International Publishing Switzerland 2015. Online dating sites are experiencing a rise in popularity, with one in five relationships in the United States starting on one of these sites. Online dating sites provide a valuable platform not only for single people trying to meet a life partner, but also for cybercriminals, who see in people looking for love easy victims for scams. Such scams span from schemes similar to traditional advertisement of illicit services or goods (i.e., spam) to advanced schemes, in which the victim starts a long-distance relationship with the scammer and is eventually extorted money. In this paper we perform the first large-scale study of online dating scams. We analyze the scam accounts detected on a popular online dating site over a period of eleven months, and provide a taxonomy of the different types of scammers that are active in the online dating landscape. We show that different types of scammers target a different demographics on the site, and therefore set up accounts with different characteristics. Our results shed light on the threats associated to online dating scams, and can help researchers and practitioners in developing effective countermeasures to fight them
Complete BFT Embedding of Massive Theory with One- and Two-form Gauge Fields
We study the constraint structure of the topologically massive theory with
one- and two-form fields in the framework of Batalin-Fradkin-Tyutin embedding
procedure. Through this analysis we obtain a new type of Wess-Jumino action
with novel symmetry, which is originated from the topological coupling term, as
well as the St\"uckelberg action related to the explicit gauge breaking mass
terms from the original theory.Comment: 22 pages, no figures, references adde
Dynamic Labyrinthine Pattern in an Active Liquid Film
We report the generation of a dynamic labyrinthine pattern in an active
alcohol film. A dynamic labyrinthine pattern is formed along the contact line
of air/pentanol/aqueous three phases. The contact line shows a clear
time-dependent change with regard to both perimeter and area of a domain. An
autocorrelation analysis of time-development of the dynamics of the perimeter
and area revealed a strong geometric correlation between neighboring patterns.
The pattern showed autoregressive behavior. The behavior of the dynamic pattern
is strikingly different from those of stationary labyrinthine patterns. The
essential aspects of the observed dynamic pattern are reproduced by a
diffusion-controlled geometric model
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