292 research outputs found
A Maximum Resonant Set of Polyomino Graphs
A polyomino graph is a connected finite subgraph of the infinite plane
grid such that each finite face is surrounded by a regular square of side
length one and each edge belongs to at least one square. In this paper, we show
that if is a maximum resonant set of , then has a unique perfect
matching. We further prove that the maximum forcing number of a polyomino graph
is equal to its Clar number. Based on this result, we have that the maximum
forcing number of a polyomino graph can be computed in polynomial time. We also
show that if is a maximal alternating set of , then has a unique
perfect matching.Comment: 13 pages, 6 figure
High photo-excited carrier multiplication by charged InAs dots in AlAs/GaAs/AlAs resonant tunneling diode
We present an approach for the highly sensitive photon detection based on the
quantum dots (QDs) operating at temperature of 77K. The detection structure is
based on an AlAs/GaAs/AlAs double barrier resonant tunneling diode combined
with a layer of self-assembled InAs QDs (QD-RTD). A photon rate of 115 photons
per second had induced 10nA photocurrent in this structure, corresponding to
the photo-excited carrier multiplication factor of 10^7. This high
multiplication factor is achieved by the quantum dot induced memory effect and
the resonant tunneling tuning effect of QD-RTD structure.Comment: 10 pages,5 figures. Submitted to Applied Physics Letter
The Influence of the Reputation of Finance Intermediaries on IPO Underpricing in China Growth Enterprize Markets (GEM)
Growth Enterprize Markets (GEM) in China was established in October 30, 2009. The paper analyses the underpricing effects and IPO stock’s first month, first quarter return in GEM of China, researches nearly 150 listed company in GEM. Its finds weak reputation effects of finance intermediaries on IPO underpricing and periods returns. This shows the failure of information generation function and failure of certificate function of finance intermediaries in new emerging market in China.Key Words: Growth enterprize market; Underpricing; Reputation of finance intermediaries; Information generation; Information certificatio
Results of Gravity Observations Using a Superconducting Gravimeter at the Tibetan Plateau
The tidal and nontidal gravity change characteristics in the Tibetan Plateau region were investigated using the continuous gravity measurements recorded with a superconducting gravimeter (SG) installed in Lhasa from December 8, 2009 to September 30, 2011. The results indicated that the precision of the tidal gravity observations with the SG in Lhasa was very high. The standard deviation of the harmonic analysis for the gravity tides was 0.498 nm s-2, and the uncertainties of amplitude factors in the four main tidal waves (i.e., O1, K1, M2 and S2) were better than 0.002%. In addition, the diurnal gravity tide observations clearly revealed a pattern of nearly diurnal resonance. As a result, it is affirmed that the station should act as a local tidal gravity reference in the Tibetan Plateau and its adjacent regions. The load effects of oceanic tides are so weak that the resulting perturbation in the gravimetric factors is less than 0.6%. However, the load effects of the local atmosphere on either the tidal or the nontidal gravity observations are significant, although no seasonal variations have been found. After removing the atmospheric effects, the standard deviation of the harmonic analysis for the gravity tides decreased obviously from 4.160 to 0.498 nm s-2. Having removed the load effects of oceanic tides and local atmosphere, it is found that the tidal gravity observations are significantly different from those expected theoretically, which may be related to active tectonic movement and extremely thick crust in the Tibetan Plateau region. In addition, the Earth¡¦s free oscillations excited by 2011 Tohoku-Oki Mw 9.0 Earthquake were successfully detected
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