4,699 research outputs found

    Cytological Analysis of the Effect of Gametocidal Chromosome 2C on ChineseSpring- E. elongatum 7E Disomic Addition

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    AbstractElytrigia Desv is an important parent plant in wheat breeding because of its good characters. In this study, according to the complete or incomplete gametocidal effect, ChineseSpring- Ae.cylindrical-2C disomic addition were used to cross with ChineseSpring- E. elongatum (E. elongatum, 2n=14EE) 7E disomic addition. The chromosome aberration were induced and the translocation of wheat- E. elongatum 7E were created. By observing the F1 and BF1 meiosis of pollen mother cell, it showed that the number of univalents, rod bivalents, multivalents were more than theoretical value. In meiosis metaphase I of CE-7Eā€œĆ—CS-2Cā€, the configuration of chromosome pairing was 3.88I +16.18II+0.51III+0.23IVĀ° Even in anaphase I, II, there were a lot of abnormal phenomena, such as lagging chromosomes and fragments. By using C-banding, the materials with translocation were identified. After checked 102 plants of F2, we obtained 7 translocation plants, including 1 inter-wheat-genome translocation. The translocation frequency was 6.86%

    End to End Optimization of a Mars Hybrid Transportation Architecture

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    NASAs Mars Study Capability Team (MSCT) is developing a reusable Mars hybrid transportation architecture in which both chemical and solar electric propulsion systems are used in a single vehicle design to send crew and cargo to Mars. This paper presents a new integrated framework that combines Earth departure/arrival, heliocentric trajectory, Mars orbit reorientation, and vehicle sizing into a single environment and solves the entire mission from beginning to end in an effort to find a globally optimized solution for the hybrid architecture

    The kHz QPOs as a probe of the X-ray color-color diagram and accretion-disk structure for the atoll source 4U 1728-34

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    We have taken the kHz QPOs as a tool to probe the correlation between the tracks of X-ray color-color diagram (CCD) and magnetosphere-disk positions for the atoll source 4U 1728-34, based on the assumptions that the upper kHz QPO is ascribed to the Keplerian orbital motion and the neutron star (NS) magnetosphere is defined by the dipole magnetic field. We find that from the island to the banana state, the inner accretion disk gradually approaches the NS surface with the radius decreasing from r ~33.0km to ~15.9 km, corresponding to the magnetic field from B(r) ~4.8*10^6 G to ~4.3*10^7 G. In addition, we note the characteristics of some particular radii of magnetosphere-disk -r are: firstly, the whole atoll shape of the CCD links the disk radius range of ~15.9 - 33.0 km, which is just located inside the corotation radius of 4U 1728-34 -r_co ( ~34.4 km), implying that the CCD shape is involved in the NS spin-up state. Secondly, the island and banana states of CCD correspond to the two particular boundaries: (I)-near the corotation radius at r ~27.2 - 33.0 km, where the source lies in the island state; (II)-near the NS surface at r ~15.9 - 22.3 km, where the source lies in both the island and banana states. Thirdly, the vertex of the atoll shape in CCD, where the radiation transition from the hard to soft photons occurs, is found to be near the NS surface at r ~16.4 km. The above results suggest that both the magnetic field and accretion environment are related to the CCD structure of atoll track, where the corotation radius and NS hard surface play the significant roles in the radiation distribution of atoll source.Comment: 6 pages, 3 figures, 1 table, accepted by Astronomy & Astrophysic

    Integrated Optimization of Mars Hybrid Solar-Electric/Chemical Propulsion Trajectories

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    NASAs Human Exploration and Operation Mission Directorate is developing a reusable hybrid transportation architecture in which both chemical and solar-electric propulsion systems are used to deliver crew and cargo to the Martian sphere of influence. By combining chemical and solar-electric propulsions into a single spacecraft and applying each where it is the most effective, the hybrid architecture enables a series of Mars trajectories that are more fuel efficient than an all chemical propulsion architecture without significant increase to trip time. Solving the complex problem of low-thrust trajectory optimization coupled with the vehicle sizing requires development of an integrated trajectory analysis frame- work. Previous studies have utilized a more segmented optimization framework due to the limitation of the tools available. A new integrated optimization framework was recently developed to address the deficiencies of the previous methods that enables higher fidelity analysis to be performed and increases the efficiency of large design space explorations

    GPSP: Graph Partition and Space Projection based Approach for Heterogeneous Network Embedding

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    In this paper, we propose GPSP, a novel Graph Partition and Space Projection based approach, to learn the representation of a heterogeneous network that consists of multiple types of nodes and links. Concretely, we first partition the heterogeneous network into homogeneous and bipartite subnetworks. Then, the projective relations hidden in bipartite subnetworks are extracted by learning the projective embedding vectors. Finally, we concatenate the projective vectors from bipartite subnetworks with the ones learned from homogeneous subnetworks to form the final representation of the heterogeneous network. Extensive experiments are conducted on a real-life dataset. The results demonstrate that GPSP outperforms the state-of-the-art baselines in two key network mining tasks: node classification and clustering.Comment: WWW 2018 Poste

    Migrating Knowledge between Physical Scenarios based on Artificial Neural Networks

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    Deep learning is known to be data-hungry, which hinders its application in many areas of science when datasets are small. Here, we propose to use transfer learning methods to migrate knowledge between different physical scenarios and significantly improve the prediction accuracy of artificial neural networks trained on a small dataset. This method can help reduce the demand for expensive data by making use of additional inexpensive data. First, we demonstrate that in predicting the transmission from multilayer photonic film, the relative error rate is reduced by 46.8% (26.5%) when the source data comes from 10-layer (8-layer) films and the target data comes from 8-layer (10-layer) films. Second, we show that the relative error rate is decreased by 22% when knowledge is transferred between two very different physical scenarios: transmission from multilayer films and scattering from multilayer nanoparticles. Finally, we propose a multi-task learning method to improve the performance of different physical scenarios simultaneously in which each task only has a small dataset

    PathLocdb: a comprehensive database for the subcellular localization of metabolic pathways and its application to multiple localization analysis

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    <p>Abstract</p> <p>Background</p> <p>In eukaryotes, the cell is divided into several compartments enclosed by unitary membranes. Such compartmentalization is critical for cells to restrict different pathways to be carried out in different subcellular regions. The summary and classification of subcellular localizations of metabolic pathways are the first steps towards understanding their roles in spatial differentiation and the specialization of metabolic pathways in different organisms.</p> <p>Results</p> <p>Integrating the subcellular localization of enzymes and their pathways from UniProt Knowledgebase and KEGG pathway databases, we present the first database for subcellular localization of 43014 pathways from 80676 UniProt entries and their pathway annotations from UniProt and KEGG pathway databases. To extract pathway localization across organisms, we defined 889 superpathways as clusters of basic pathways with the same pathway annotations from different organisms. Over eighty-eight percent of superpathways in the Swiss-Prot dataset occur in cytoplasm and mitochondria. And over seventy percent of UniProt superpathways have multiple localization annotations. We summarized four common reasons for the multiple localization of superpathways. Based on this database, we also discovered 88 potential transport systems between different steps of multiply localized pathways and 45 duplicated genes from 17 pathways, occurring in parallel in several locations in humans.</p> <p>Conclusions</p> <p>PathLocdb is a free web-accessible database that enables biochemical researchers to quickly access summarized subcellular localization of pathways from UniProt and KEGG pathway databases. As the first effort to systematically integrate pathway localization, this database is very useful in discovering the variation of localization of pathways between organisms and also cross-talk between different organelles within a pathway. The Pathlocdb database is available at http://pathloc.cbi.pku.edu.cn.</p

    High similarity of phylogenetic profiles of rate-limiting enzymes with inhibitory relation in Human, Mouse, Rat, budding Yeast and E. coli

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    Background: The phylogenetic profile is widely used to characterize functional linkage and conservation between proteins without amino acid sequence similarity. To survey the conservative regulatory properties of rate-limiting enzymes (RLEs) in metabolic inhibitory network across different species, we define the enzyme inhibiting pair as: where the first enzyme in a pair is the inhibitor provider and the second is the target of the inhibitor. Phylogenetic profiles of enzymes in the inhibiting pairs are further generated to measure the functional linkage of these enzymes during evolutionary history. Results: We find that the RLEs generate, on average, over half of all in vivo inhibitors in each surveyed model organism. And these inhibitors inhibit on average over 85% targets in metabolic inhibitory network and cover the majority of targets of cross-pathway inhibiting relations. Furthermore, we demonstrate that the phylogenetic profiles of the enzymes in inhibiting pairs in which at least one enzyme is rate-limiting often show higher similarities than those in common inhibiting enzyme pairs. In addition, RLEs, compared to common metabolic enzymes, often tend to produce ADP instead of AMP in conservative inhibitory networks. Conclusions: Combined with the conservative roles of RLEs in their efficiency in sensing metabolic signals and transmitting regulatory signals to the rest of the metabolic system, the RLEs may be important molecules in balancing energy homeostasis via maintaining the ratio of ATP to ADP in living cells. Furthermore, our results indicate that similarities of phylogenetic profiles of enzymes in the inhibiting enzyme pairs are not only correlated with enzyme topological importance, but also related with roles of the enzymes in metabolic inhibitory network. Ā© 2011 licensee BioMed Central Ltd

    Human liver rate-limiting enzymes influence metabolic flux via branch points and inhibitors

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    Background: Rate-limiting enzymes, because of their relatively low velocity, are believed to influence metabolic flux in pathways. To investigate their regulatory role in metabolic networks, we look at the global organization and interactions between rate-limiting enzymes and compounds such as branch point metabolites and enzyme inhibitors in human liver. Results: Based on 96 rate-limiting enzymes and 132 branch point compounds from human liver, we found that rate-limiting enzymes surrounded 76.5% of branch points. In a compound conversion network from human liver, the 128 branch points involved showed a dramatically higher average degree, betweenness centrality and closeness centrality as a whole. Nearly half of the in vivo inhibitors were products of rate-limiting enzymes, and covered 75.34% of the inhibited targets in metabolic inhibitory networks. Conclusion: From global topological organization, rate-limiting enzymes as a whole surround most of the branch points; so they can influence the flux through branch points. Since nearly half of the in vivo enzyme inhibitors are produced by rate-limiting enzymes in human liver, these enzymes can initiate inhibitory regulation and then influence metabolic flux through their natural products. Ā© 2009 Zhao and Qu; licensee BioMed Central Ltd

    The Effectiveness of Scarcity Messages in Group-Buying Social Commerce: The Comparison of Korea and China

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    This study attempts to extend the customer valueā€“customer satisfactionā€“customer loyalty framework by introducing key constructs of scarcity messages as a major environmental stimulus and the urge to buy impulsively as its response in the context of group-buying social commerce, across countries including Korea and China. More specifically, this study proposes that scarcity messages influence customersā€™ value perception (i.e., utilitarian value and hedonic value. Moreover, the study suggests that scarcity messages and customer values arouse the urge to buy impulsively. In the Korean sample, the results show that scarcity messages increase both utilitarian and hedonic values as well as the urge to buy impulsively, which in turn enhances customersā€™ satisfaction and further loyalty. In the Chinese sample, relationships related to utilitarian value are insignificant. That is, scarcity messages only influence hedonic value which increases the urge to buy impulsively. Besides, customer satisfaction depends on utilitarian and hedonic values
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