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361.
Control of tillering in rice 总被引:146,自引:0,他引:146
Li X Qian Q Fu Z Wang Y Xiong G Zeng D Wang X Liu X Teng S Hiroshi F Yuan M Luo D Han B Li J 《Nature》2003,422(6932):618-621
Tillering in rice (Oryza sativa L.) is an important agronomic trait for grain production, and also a model system for the study of branching in monocotyledonous plants. Rice tiller is a specialized grain-bearing branch that is formed on the unelongated basal internode and grows independently of the mother stem (culm) by means of its own adventitious roots. Rice tillering occurs in a two-stage process: the formation of an axillary bud at each leaf axil and its subsequent outgrowth. Although the morphology and histology and some mutants of rice tillering have been well described, the molecular mechanism of rice tillering remains to be elucidated. Here we report the isolation and characterization of MONOCULM 1 (MOC1), a gene that is important in the control of rice tillering. The moc1 mutant plants have only a main culm without any tillers owing to a defect in the formation of tiller buds. MOC1 encodes a putative GRAS family nuclear protein that is expressed mainly in the axillary buds and functions to initiate axillary buds and to promote their outgrowth. 相似文献
362.
An improvement of the too cold tongue in the tropical Pacific with the development of an ocean-wave-atmosphere coupled numerical model 总被引:1,自引:0,他引:1
A common problem in the application of the coupled ocean-atmosphere general circulation models (CGCMs) without flux correction is that the simulated equatorial cold tongue in general tends to be too strong, narrow, and extending too far west. The causes are not well understood yet. One possible reason may be the simulated mixed layer depth (MLD) is too shallow in the tropical Pacific due to insufficient vertical mixing in the OGCM. It is believed that the wave-induced vertical mixing can greatly improve the simulation of the MLD and thermocline structure. In this study, the coupled ocean-atmosphere general circulation model (FGCM-0) incorporated with wave-induced mixing has been employed to simulate the tropical Pacific sea surface temperature (SST). Generally, the wave-induced mixing lowers the SST in the OGCM because the strengthened vertical mixing can bring more cold water upward. However, in the coupled model, the non-uniformity of the space distribution in SST drop generates a horizontal gradient of the sea surface air pressure, and thus yields surface wind field anomaly. The wind anomaly leads to both ocean surface circulation anomaly and downwelling anomaly, which can restrain the overly-westward extension of the cold tongue in the tropical Pacific. Compared with the model results from the original model (FGCM-0), the modeled SST is higher by more than 0.8℃, with a maximum of 1.2℃ in the western Pacific (160—180°E, 0—3°N). The eastern boundary of the isotherm of 26.0℃ also moves from 165°E to 180°E. The overly westward extension of the simulated equatorial cold tongue is suppressed with the incorporation of the wave-induced mixing in the coupled model. The simulated SST shows in general improved results with a maximum improvement of more than 1.0℃. The simulated SST improvement in the north tropical Pacific is much better than that of the south tropical Pacific. 相似文献
363.
An improvement of the too cold tongue in the tropical Pacific with the development of an ocean-wave-atmosphere coupled numerical model 总被引:1,自引:0,他引:1
A common problem in the application of the coupled ocean-atmosphere general circulation models (CGCMs) without flux correction is that the simulated equatorial cold tongue in general tends to be too strong, narrow, and extending too far west. The causes are not well understood yet. One possible reason may be the simulated mixed layer depth (MLD) is too shallow in the tropical Pacific due to insufficient vertical mixing in the OGCM. It is believed that the wave-induced vertical mixing can greatly improve the simulation of the MLD and thermocline structure. In this study, the coupled ocean-atmosphere general circulation model (FGCM-0) incorporated with wave-induced mixing has been employed to simulate the tropical Pacific sea surface temperature (SST). Generally, the wave-induced mixing lowers the SST in the OGCM because the strengthened vertical mixing can bring more cold water upward. However, in the coupled model, the non-uniformity of the space distribution in SST drop generates a horizontal gradient of the sea surface air pressure, and thus yields surface wind field anomaly. The wind anomaly leads to both ocean surface circulation anomaly and downwelling anomaly, which can restrain the overly-westward extension of the cold tongue in the tropical Pacific. Compared with the model results from the original model (FGCM-0), the modeled SST is higher by more than 0.8℃, with a maximum of 1.2℃in the western Pacific (160—180°E, 0—3°N) . The eastern boundary of the isotherm of 26. 0℃also moves from 165°E to 180°E. The overly westward extension of the simulated equatorial cold tongue is suppressed with the incorporation of the wave-induced mixing in the coupled model. The simulated SST shows in general improved results with a maximum improvement of more than 1.0℃. The simulated SST improvement in the north tropical Pacific is much better than that of the south tropical Pacific. 相似文献
364.
WANG Ting GUO Xia FANG Yuan SHEN GuangDi 《科学通报(英文版)》2007,52(7):1001-1005
An ultraviolet (UV) laser lift-off (LLO) technique was presented to form a roughened surface morphol-ogy on GaN membrane grown by metalorganic chemical vapor deposition (MOCVD). The etched sur-face showed cone-like structures on a free-standing GaN membrane. Based on the scanning electron microscopy (SEM) and atom force microscopy (AFM) measurements, the etching mechanism was proposed, which was related to the different decomposition depth caused by the dislocations in the GaN membrane. The etching efficiency and morphology of GaN by the LLO technique and the photo-electrochemical (PEC) wet etching technique was compared and analyzed. This roughed cone-like surface morphology by LLO can enhance the external efficiency of vertical structure n-side-up GaN-based light-emitting diodes (LEDs) simultaneously while being released of the performance con-strains impeded by sapphire. 相似文献
365.
YUAN Yuan ZHANG Huanguo 《武汉大学学报:自然科学英文版》2007,12(6):992-996
Permutation codes over finite chain rings are introduced; by using the character of the finite chain rings and the knowledge of representation of group, some conditions for existence or non-existence of self-dual permutation codes over finite chain rings are obtained. Specially, when the group is a direct product of a 2-group and a T-group, and the group action is transitive, the sufficient and necessary condition of the existence of permutation codes is given. 相似文献
366.
Functional link between ataxia-telangiectasia and Nijmegen breakage syndrome gene products 总被引:50,自引:0,他引:50
Zhao S Weng YC Yuan SS Lin YT Hsu HC Lin SC Gerbino E Song MH Zdzienicka MZ Gatti RA Shay JW Ziv Y Shiloh Y Lee EY 《Nature》2000,405(6785):473-477
Ataxia-telangiectasia (A-T) and Nijmegen breakage syndrome (NBS) are recessive genetic disorders with susceptibility to cancer and similar cellular phenotypes. The protein product of the gene responsible for A-T, designated ATM, is a member of a family of kinases characterized by a carboxy-terminal phosphatidylinositol 3-kinase-like domain. The NBS1 protein is specifically mutated in patients with Nijmegen breakage syndrome and forms a complex with the DNA repair proteins Rad50 and Mrel1. Here we show that phosphorylation of NBS1, induced by ionizing radiation, requires catalytically active ATM. Complexes containing ATM and NBS1 exist in vivo in both untreated cells and cells treated with ionizing radiation. We have identified two residues of NBS1, Ser 278 and Ser 343 that are phosphorylated in vitro by ATM and whose modification in vivo is essential for the cellular response to DNA damage. This response includes S-phase checkpoint activation, formation of the NBS1/Mrel1/Rad50 nuclear foci and rescue of hypersensitivity to ionizing radiation. Together, these results demonstrate a biochemical link between cell-cycle checkpoints activated by DNA damage and DNA repair in two genetic diseases with overlapping phenotypes. 相似文献
367.
LUO Yuan 《系统科学与复杂性》1998,(2)
1.Introduction.Weallknowthattheneuralnetworkmodelandtheciphersystemarebothimportantinthefieldofinformationprocessing.Thispaperwilltellyouhowtoestablishakindofrelationshipbetweenthem.ThetraditionalHopfieldNeuralNetworkisadynamicsystemwithNconnectedneurons,andthestateofeachneuroniseither lor--1.Letyi(t)bethestateoftheithneuronattimet.Thenthestateofthewholenetworkcanbedenotedasavectorv(t)=(yi(t),yi(t),''IVN(t)).Atthenexttime,thestateoftheithneuroniscomputedbywheresgn(u)~--1whenu<0andsgn(u)~1… 相似文献
368.
This paper develops a novel event-triggered optimal control approach based on state observer and neural network(NN) for nonlinear continuous-time systems. Firstly, the authors propose an online algorithm with critic and actor NNs to solve the optimal control problem and provide an event-triggered method to reduce communication and computation burdens. Moreover, the authors design weight estimation for critic and actor NNs based on gradient descent method and achieve uniformly ultimate boundednes... 相似文献
369.
As we have borrowed the wisdom from biological neural network, the characteristic of interference- proof in information transferring process has been carefully studied. Our study includes the response of electrical-interference-proof circuit in electromagnetic environment, by means of bionics redesign. In this way, new principles, new technics and new ways are adopted to solve the unavoidable situations in traditional electro- magnet protection design. Based on the Boolean model, the complex bionic topological networks were firstly built and the charactoristics of degeneracy were analyzed, then the bidirectional actions between degeneracy in networks and the robustness of functions were proved in order to fill up the gap to deal with the need of interference-proof. Based on the creation of the neuron networks and the electrical synapses ' charac- teristic of plasticity, the impact of the distribution in the weight of synapse on the character of network self- recovery was studied afterwards so that the corresponding mechanism could be defined. 相似文献
370.
Keane TM Goodstadt L Danecek P White MA Wong K Yalcin B Heger A Agam A Slater G Goodson M Furlotte NA Eskin E Nellåker C Whitley H Cleak J Janowitz D Hernandez-Pliego P Edwards A Belgard TG Oliver PL McIntyre RE Bhomra A Nicod J Gan X Yuan W van der Weyden L Steward CA Bala S Stalker J Mott R Durbin R Jackson IJ Czechanski A Guerra-Assunção JA Donahue LR Reinholdt LG Payseur BA Ponting CP Birney E Flint J Adams DJ 《Nature》2011,477(7364):289-294