4,019 research outputs found
Fully integrated InGaAs/InP single-photon detector module with gigahertz sine wave gating
InGaAs/InP single-photon avalanche diodes (SPADs) working in the regime of
GHz clock rates are crucial components for the high-speed quantum key
distribution (QKD). We have developed for the first time a compact, stable and
user-friendly tabletop InGaAs/InP single-photon detector system operating at a
1.25 GHz gate rate that fully integrates functions for controlling and
optimizing SPAD performance. We characterize the key parameters of the detector
system and test the long-term stability of the system for continuous operation
of 75 hours. The detector system can substantially enhance QKD performance and
our present work paves the way for practical high-speed QKD applications.Comment: 11 pages, 6 figures. Accepted for publication in Review of Scientific
Instrument
When Social Influence Meets Item Inference
Research issues and data mining techniques for product recommendation and
viral marketing have been widely studied. Existing works on seed selection in
social networks do not take into account the effect of product recommendations
in e-commerce stores. In this paper, we investigate the seed selection problem
for viral marketing that considers both effects of social influence and item
inference (for product recommendation). We develop a new model, Social Item
Graph (SIG), that captures both effects in form of hyperedges. Accordingly, we
formulate a seed selection problem, called Social Item Maximization Problem
(SIMP), and prove the hardness of SIMP. We design an efficient algorithm with
performance guarantee, called Hyperedge-Aware Greedy (HAG), for SIMP and
develop a new index structure, called SIG-index, to accelerate the computation
of diffusion process in HAG. Moreover, to construct realistic SIG models for
SIMP, we develop a statistical inference based framework to learn the weights
of hyperedges from data. Finally, we perform a comprehensive evaluation on our
proposals with various baselines. Experimental result validates our ideas and
demonstrates the effectiveness and efficiency of the proposed model and
algorithms over baselines.Comment: 12 page
MANAGING ULCERATIVE COLITIS BY INCREASING HYDROGEN PRODUCTION VIA ORAL ADMINISTRATION OF ACARBOSE
The objective of the study was to investigate ulcerative colitis management through oral administration of acarbose. Acarbose has gained importance as a drug used widely to treat Diabetes Mellitus Type 2,as it acts on the small intestine by competitively inhibiting enzymes that delay the release of glucose from complex carbohydrates, thereby specifically reducing postprandial glucose excursion. The main side-effect of treatment with Acarbose, flatulence, occurs when undigested carbohydrates are fermented by colonic bacteria, resulting in considerable amounts of hydrogen. We found that the enteric benefits of Acarbose are partly due to be their ability to neutralise oxidative stress via increased production of H2 in the gastrointestinal tract. Therefore, some symptoms of ulcerative colitis in human beings can be ameliorated by Acarbose
Unitarity of the Higher Dimensional Standard Model
We study the unitarity of the standard model (SM) in higher dimensions. We
show that the essential features of SM unitarity remain after compactification,
and place bounds on the highest Kaluza-Klein (KK) level N_KK and the Higgs mass
m_H in the effective four-dimensional (4d) low-energy theory. We demonstrate
these general observations by explicitly analyzing the effective 4d KK theory
of a compactified 5d SM on S^1/Z_2. The nontrivial energy cancellations in the
scattering of longitudinal KK gluons or KK weak bosons, a consequence of the
geometric Higgs mechanism, are verified. In the case of the electroweak gauge
bosons, the longitudinal KK states also include a small mixture from the KK
Higgs excitations. With the analyses before and after compactification, we
derive the strongest bounds on N_KK from gauge KK scattering. Applying these
bounds to higher-dimensional SUSY GUTs implies that only a small number of KK
states can be used to accelerate gauge coupling unification. As a consequence,
we show that the GUT scale in the 5d minimal SUSY GUT cannot be lower than
about 10^{14} GeV.Comment: Version in Phys. Lett. B (minor typos fixed, refs added
Scattering Matrix Theory For Nonlinear Transport
We report a scattering matrix theory for dynamic and nonlinear transport in
coherent mesoscopic conductors. In general this theory allows predictions of
low frequency linear dynamic conductance, as well as weakly nonlinear DC
conductance. It satisfies the conditions of gauge invariance and electric
current conservation, and can be put into a form suitable for numerical
computation. Using this theory we examine the third order weakly nonlinear DC
conductance of a tunneling diode
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