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Search Results: 1 - 10 of 251727 matches for " C. Guo "
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Quantum memory for individual polarization photon
G. P. Guo,G. C. Guo
Physics , 2003, DOI: 10.1016/j.physleta.2003.09.048
Abstract: Here we present an experimentally feasible quantum memory for individual polarization photon with long-lived atomic ensembles excitations. Based a process similar to teleportation, the memory is reversible. And the storage information can be effortlessly read out and transferred back to photon. Although it successes with only a probability of 1/4, it is expected valuable in various quantum information processing, especially those cases where polarized photons are employed. The physical requirements are moderate and fit the presest technique.
Theoretic and Numerical Study of a New Chaotic System  [PDF]
C.X. Zhu, Y.H. Liu, Y. Guo
Intelligent Information Management (IIM) , 2010, DOI: 10.4236/iim.2010.22013
Abstract: This paper introduced a new three-dimensional continuous quadratic autonomous chaotic system, modified from the Lorenz system, in which each equation contains a single quadratic cross-product term, which is different from the Lorenz system and other existing systems. Basic properties of the new system are analyzed by means of Lyapunov exponent spectrum, Poincaré mapping, fractal dimension, power spectrum and chaotic behaviors. Furthermore, the forming mechanism of its compound structure obtained by merging together two simple attractors after performing one mirror operation has been investigated by detailed nu-merical as well as theoretical analysis. Analysis results show that this system has complex dynamics with some interesting characteristics.
Multiple-trait quantitative trait locus mapping with incomplete phenotypic data
Zhigang Guo, James C Nelson
BMC Genetics , 2008, DOI: 10.1186/1471-2156-9-82
Abstract: We present an expectation-maximization (EM) algorithm, derived for recombinant inbred and F2 genetic models but extensible to any mating design, that supports conventional hypothesis tests for QTL main effect, pleiotropy, and QTL-by-environment interaction in multiple-trait analyses with missing phenotypic data. We evaluate its performance by simulations and illustrate with a real-data example.The EM method affords improved QTL detection power and precision of QTL location and effect estimation in comparison with case deletion or imputation methods. It may be incorporated into any least-squares or likelihood-maximization QTL-mapping approach.Statistical methods for identifying and mapping genes controlling complex traits, commonly known as quantitative trait loci or QTL, have been developed to a high degree. The primary focus has been on methods for single traits ([1-8] and many others). It was proposed [9,10] that multi-trait QTL mapping methods that consider simultaneously several correlated phenotypic traits, or a single trait measured in several environments, offer increased detection power and precision of location and effect estimation over single-trait QTL mapping. This is because trait-by-trait QTL-searching neglects information contained in the data about the common influence of a QTL on more than one trait, in more than one environment, or [11] at more than one developmental stage. Multi-trait (MT) QTL mapping allows a formal test of pleiotropy of a QTL for multiple traits or QTL-by-environment interaction for a single trait measured across multiple environments. The enhancement by MT of QTL-detection power is greatest when the QTL induces covariation between the tested traits in the direction opposite to that from "background" sources [12,13]. These advantages have been exploited in animal [14-16] and plant [17] studies.With the promise of increased power from a multivariate approach comes an interesting problem: what to do when some of the multivariate d
Properties of non-coding DNA and identification of putative cis-regulatory elements in Theileria parva
Xiang Guo, Joana C Silva
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-582
Abstract: Intergenic regions and introns in Theileria are short, and their length distributions are considerably right-skewed. Intergenic regions flanked by genes in 5'-5' orientation tend to be longer and slightly more AT-rich than those flanked by two stop codons; intergenic regions flanked by genes in 3'-5' orientation have intermediate values of length and AT composition. Intron position is negatively correlated with intron length, and positively correlated with GC content. Using stringent criteria, we identified a set of high-quality orthologous non-coding sequences between T. parva and T. annulata, and determined the distribution of selective constraints across regions, which are shown to be higher close to translation start sites. A positive correlation between constraint and length in both intergenic regions and introns suggests a tight control over length expansion of non-coding regions. Genome-wide searches for functional elements revealed several conserved motifs in intergenic regions of Theileria genomes. Two such motifs are preferentially located within the first 60 base pairs upstream of transcription start sites in T. parva, are preferentially associated with specific protein functional categories, and have significant similarity to know regulatory motifs in other species. These results suggest that these two motifs are likely to represent transcription factor binding sites in Theileria.Theileria genomes are highly compact, with selection seemingly favoring short introns and intergenic regions. Three over-represented sequence motifs were independently identified in intergenic regions of both Theileria species, and the evidence suggests that at least two of them play a role in transcriptional control in T. parva. These are prime candidates for experimental validation of transcription factor binding sites in this single-celled eukaryotic parasite. Sequences similar to two of these Theileria motifs are conserved in Plasmodium hinting at the possibility of common r
Design of FIR Precoders and Equalizers for Broadband MIMO Wireless Channels with Power Constraints
Guo Yongfang,Levy Bernard C
EURASIP Journal on Wireless Communications and Networking , 2004,
Abstract: This paper examines the optimum design of FIR precoders or equalizers for multiple-input multiple-output (MIMO) frequency-selective wireless channels. For the case of a left-coprime FIR channel, which arises generically when the number of transmit antennas is larger than the number of receive antennas, the Bezout matrix identity can be employed to design an FIR MIMO precoder that equalizes exactly the channel at the transmitter. Similarly, for a right-coprime FIR channel, the Bezout identity yields an FIR zero-forcing MIMO equalizer. Unfortunately, Bezout precoders usually increase the transmit power, and Bezout equalizers tend to amplify the noise power. To overcome this problem, we describe in this paper a convex optimization technique for the optimal synthesis of MIMO FIR precoders subject to transmit power constraints, and of MIMO FIR equalizers with output noise power constraints. The synthesis problem reduces to the minimization of a quadratic objective function under convex quadratic inequality constraints, so it can be solved by employing Lagrangian duality. Instead of solving the primal problem, we solve the lower-dimensional dual problem for the Lagrange multipliers. When an FIR MIMO precoder has already been selected, we also describe a technique for adding a vector shaping sequence to the transmitted signal in order to reduce the transmit power. The selection of effective shaping sequences requires a search over a trellis of large dimensionality, which can be accomplished suboptimally by employing reduced-complexity search techniques.
Design of FIR Precoders and Equalizers for Broadband MIMO Wireless Channels with Power Constraints
Guo Yongfang,Levy Bernard C.
EURASIP Journal on Wireless Communications and Networking , 2004,
Abstract: This paper examines the optimum design of FIR precoders or equalizers for multiple-input multiple-output (MIMO) frequency-selective wireless channels. For the case of a left-coprime FIR channel, which arises generically when the number n T of transmit antennas is larger than the number n R of receive antennas, the Bezout matrix identity can be employed to design an FIR MIMO precoder that equalizes exactly the channel at the transmitter. Similarly, for a right-coprime FIR channel, the Bezout identity yields an FIR zero-forcing MIMO equalizer. Unfortunately, Bezout precoders usually increase the transmit power, and Bezout equalizers tend to amplify the noise power. To overcome this problem, we describe in this paper a convex optimization technique for the optimal synthesis of MIMO FIR precoders subject to transmit power constraints, and of MIMO FIR equalizers with output noise power constraints. The synthesis problem reduces to the minimization of a quadratic objective function under convex quadratic inequality constraints, so it can be solved by employing Lagrangian duality. Instead of solving the primal problem, we solve the lower-dimensional dual problem for the Lagrange multipliers. When an FIR MIMO precoder has already been selected, we also describe a technique for adding a vector shaping sequence to the transmitted signal in order to reduce the transmit power. The selection of effective shaping sequences requires a search over a trellis of large dimensionality, which can be accomplished suboptimally by employing reduced-complexity search techniques.
A Quality Control Mechanism Linking Meiotic Success to Release of Ascospores
Haiyan Guo, Megan C. King
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0082758
Abstract: Eukaryotic organisms employ a variety of mechanisms during meiosis to assess and ensure the quality of their gametes. Defects or delays in successful meiotic recombination activate conserved mechanisms to delay the meiotic divisions, but many multicellular eukaryotes also induce cell death programs to eliminate gametes deemed to have failed during meiosis. It is generally thought that yeasts lack such mechanisms. Here, we show that in the fission yeast Schizosaccharomyces pombe, defects in meiotic recombination lead to the activation of a checkpoint that is linked to ascus wall endolysis – the process by which spores are released in response to nutritional cues for subsequent germination. Defects in meiotic recombination are sensed as unrepaired DNA damage through the canonical ATM and ATR DNA damage response kinases, and this information is communicated to the machinery that stimulates ascus wall breakdown. Viability of spores that undergo endolysis spontaneously is significantly higher than that seen upon chemical endolysis, demonstrating that this checkpoint contributes to a selective mechanism for the germination of high quality progeny. These results provide the first evidence for the existence of a checkpoint linking germination to meiosis and suggest that analysis solely based on artificial, enzymatic endolysis bypasses an important quality control mechanism in this organism and potentially other ascomycota, which are models widely used to study meiosis.
Phase separation in a polarized Fermi gas with spin-orbit coupling
W. Yi,G. -C. Guo
Physics , 2011, DOI: 10.1103/PhysRevA.84.031608
Abstract: We study the phase separation of a spin polarized Fermi gas with spin-orbit coupling near a wide Feshbach resonance. As a result of the competition between spin-orbit coupling and population imbalance, the phase diagram for a uniform gas develops a rich structure of phase separation involving gapless superfluid states which are topologically non-trivial. We find that these novel gapless phases can be stabilized by intermediate spin-orbit coupling strengths. We then demonstrate the phase separation induced by an external trapping potential and discuss the optimal parameter region for the experimental observation of the gapless superfluid phases.
Existence and Stability of Standing Pulses in Neural Networks: II Stability
Yixin Guo,Carson C. Chow
Quantitative Biology , 2004,
Abstract: We analyze the stability of standing pulse solutions of a neural network integro-differential equation. The network consists of a coarse-grained layer of neurons synaptically connected by lateral inhibition with a non-saturating nonlinear gain function. When two standing single-pulse solutions coexist, the small pulse is unstable, and the large pulse is stable. The large single-pulse is bistable with the ``all-off'' state. This bistable localized activity may have strong implications for the mechanism underlying working memory. We show that dimple pulses have similar stability properties to large pulses but double pulses are unstable.
Existence and Stability of Standing Pulses in Neural Networks : I Existence
Yixin Guo,Carson C. Chow
Quantitative Biology , 2004, DOI: 10.1137/040609483
Abstract: We consider the existence of standing pulse solutions of a neural network integro-differential equation. These pulses are bistable with the zero state and may be an analogue for short term memory in the brain. The network consists of a single-layer of neurons synaptically connected by lateral inhibition. Our work extends the classic Amari result by considering a non-saturating gain function. We consider a specific connectivity function where the existence conditions for single-pulses can be reduced to the solution of an algebraic system. In addition to the two localized pulse solutions found by Amari, we find that three or more pulses can coexist. We also show the existence of nonconvex ``dimpled'' pulses and double pulses. We map out the pulse shapes and maximum firing rates for different connection weights and gain functions.
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