4,560 research outputs found
Impact of edge-removal on the centrality betweenness of the best spreaders
The control of epidemic spreading is essential to avoid potential fatal
consequences and also, to lessen unforeseen socio-economic impact. The need for
effective control is exemplified during the severe acute respiratory syndrome
(SARS) in 2003, which has inflicted near to a thousand deaths as well as
bankruptcies of airlines and related businesses. In this article, we examine
the efficacy of control strategies on the propagation of infectious diseases
based on removing connections within real world airline network with the
associated economic and social costs taken into account through defining
appropriate quantitative measures. We uncover the surprising results that
removing less busy connections can be far more effective in hindering the
spread of the disease than removing the more popular connections. Since
disconnecting the less popular routes tend to incur less socio-economic cost,
our finding suggests the possibility of trading minimal reduction in
connectivity of an important hub with efficiencies in epidemic control. In
particular, we demonstrate the performance of various local epidemic control
strategies, and show how our approach can predict their cost effectiveness
through the spreading control characteristics.Comment: 11 pages, 4 figure
Isotropic-medium three-dimensional cloaks for acoustic and electromagnetic waves
We propose a generalization of the two-dimensional eikonal-limit cloak
derived from a conformal transformation to three dimensions. The proposed cloak
is a spherical shell composed of only isotropic media; it operates in the
transmission mode and requires no mirror or ground plane. Unlike the well-known
omnidirectional spherical cloaks, it may reduce visibility of an arbitrary
object only for a very limited range of observation angles. In the
short-wavelength limit, this cloaking structure restores not only the
trajectories of incident rays, but also their phase, which is a necessary
ingredient to complete invisibility. Both scalar-wave (acoustic) and transverse
vector-wave (electromagnetic) versions are presented.Comment: 17 pages, 12 figure
Exterior optical cloaking and illusions by using active sources: a boundary element perspective
Recently, it was demonstrated that active sources can be used to cloak any
objects that lie outside the cloaking devices [Phys. Rev. Lett. \textbf{103},
073901 (2009)]. Here, we propose that active sources can create illusion
effects, so that an object outside the cloaking device can be made to look like
another object. invisibility is a special case in which the concealed object is
transformed to a volume of air. From a boundary element perspective, we show
that active sources can create a nearly "silent" domain which can conceal any
objects inside and at the same time make the whole system look like an illusion
of our choice outside a virtual boundary. The boundary element method gives the
fields and field gradients (which can be related to monopoles and dipoles) on
continuous curves which define the boundary of the active devices. Both the
cloaking and illusion effects are confirmed by numerical simulations
A Functional Taxonomy of Music Generation Systems
Digital advances have transformed the face of automatic music generation
since its beginnings at the dawn of computing. Despite the many breakthroughs,
issues such as the musical tasks targeted by different machines and the degree
to which they succeed remain open questions. We present a functional taxonomy
for music generation systems with reference to existing systems. The taxonomy
organizes systems according to the purposes for which they were designed. It
also reveals the inter-relatedness amongst the systems. This design-centered
approach contrasts with predominant methods-based surveys and facilitates the
identification of grand challenges to set the stage for new breakthroughs.Comment: survey, music generation, taxonomy, functional survey, survey,
automatic composition, algorithmic compositio
A comprehensive study for the plasmonic thin-film solar cell with periodic structure
A comprehensive study of the plasmonic thin-film solar cell with the periodic strip structure is presented in this paper. The finite-difference frequency-domain method is employed to discretize the inhomogeneous wave function for modeling the solar cell. In particular, the hybrid absorbing boundary condition and the one-sided difference scheme are adopted. The parameter extraction methods for the zeroth-order reflectance and the absorbed power density are also discussed, which is important for testing and optimizing the solar cell design. For the numerical results, the physics of the absorption peaks of the amorphous silicon thin-film solar cell are explained by electromagnetic theory; these peaks correspond to the waveguide mode, Floquet mode, surface plasmon resonance, and the constructively interference between adjacent metal strips. The work is therefore important for the theoretical study and optimized design of the plasmonic thin-film solar cell. © 2010 Optical Society of America.published_or_final_versio
T-cell receptor gene expression in tumour-infiltrating lymphocytes and peripheral blood lymphocytes of patients with nasopharyngeal carcinoma.
The T-cell receptor (TCR) repertoire expression of tumour-infiltrating lymphocytes (TILs) from 19 nasopharyngeal carcinoma (NPC) biopsies was compared with those of lymphocytes from 18 control nasopharyngeal biopsies. mRNA was extracted from these lymphocytes and the cDNA transcribed. A panel of 18 V alpha- and 21 V beta-specific primers was used to detect the TCR gene use from cDNA. The use of V alpha and V beta genes was restricted in TILs compared with lymphocytes from biopsies. The frequencies of V alpha 2, V alpha 3, V alpha 9, V alpha 10, V alpha 11, V alpha 13, V alpha 14, V alpha 15, V beta 11, V beta 15 and V beta 20 were decreased and the frequencies of V alpha 10 [Pc = 0.04; relative risk (RR) = 0.05], V alpha 11 (Pc = 0.02; RR = 0.07), V alpha 13 (Pc = 0.002; RR = 0), V alpha 14 (Pc = 0.04; RR = 0.05), V beta 14 (Pc = 0.001; RR = 0.03) and V beta 20 (Pc = 0.001; RR = 0.03) remained significantly reduced after correction for the number of families typed. The frequency of V alpha 17 was higher in NPC biopsies than in NPC PBLs (P = 0.05), and the frequency of V beta 15 was lower in NPC biopsies than in NPC PBLs (P = 0.02). The frequencies of V alpha 17 and V alpha 18 in HLA-B46+ patients were significantly lower (P = 0.009; P = 0.044) than in B46+ controls. The results suggest that the restriction of TCR gene use in NPC patients may be important in NPC pathogenesis
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