735 research outputs found
Seismic inference of 57 stars using full-length Kepler data sets
We present stellar properties (mass, age, radius, distances) of 57 stars from
a seismic inference using full-length data sets from Kepler. These stars
comprise active stars, planet-hosts, solar-analogs, and binary systems. We
validate the distances derived from the astrometric Gaia-Tycho solution.
Ensemble analysis of the stellar properties reveals a trend of mixing-length
parameter with the surface gravity and effective temperature. We derive a
linear relationship with the seismic quantity to
estimate the stellar age. Finally, we define the stellar regimes where the
Kjeldsen et al (2008) empirical surface correction for 1D model frequencies is
valid.Comment: 4-page proceedings from Seismology of the Sun and the Distant Stars
2016, TASC/KASC, Azores, Portugal, corrected references in v
A Key Station Identification Method for Urban Rail Transit: A Case Study of Beijing Subway
Congestion occurs and propagates in the stations of urban rail transit, which results in the impendent need to comprehensively evaluate the station performance. Based on complex network theory, a key station identification method is considered. This approach considers both the topology and dynamic operation states of urban rail transit network, such as degree, passenger demand, system capacity and capacity utilization. A case of Beijing urban rail transit is applied to verify the validation of the proposed method. It shows that the method can be helpful to daily passenger flow control and capacity enhancement during peak hours.</p
A Bayesian Network Modeling for Departure Time Choice: A Case Study of Beijing Subway
Departure time choice is critical for subway passengers to avoid congestion during morning peak hours. In this study, we propose a Bayesian network (BN) model to capture departure time choice based on data learning. Factors such as travel time saving, crowding, subway fare, and departure time change are considered in this model. K2 algorithm is then employed to learn the BN structure, and maximum likelihood estimation (MLE) is adopted to estimate model parameters, according to the data obtained by a stated preference (SP) survey. A real-world case study of Beijing subway is illustrated, which proves that the proposed model has higher prediction accuracy than typical discrete choice models. Another key finding indicates that subway fare discount higher than 20% will motivate some passengers to depart 15 to 20 minutes earlier and release the pressure of crowding during morning peak hours
Poplar Allene Oxide Synthase 1 Gene Promoter Drives Rapid and Localized Expression by Wounding
Promoters play critical roles in controlling the transcription of genes and are important as tools to drive heterologous expression for biotechnological applications. In addition to core transcription factor-binding motifs that assist in the binding of RNA polymerases, there are specific nucleotide sequences in a promoter region to allow regulation of gene expression. The allene oxide synthase (AOS) gene family are cytochrome P450s that are responsive to a variety of environmental stress, making them good candidates for the discovery of inducible promoters. Populus AOS homologs separate phylogenetically into two clades. Based on the 19 promoter motifs with significant abundance differences between the two clades, Clade I AOS genes are likely more responsive to hormones, salt, and pathogen, whereas clade II homologs are likely inducible by water stress. In this study, an upstream promoter from a Clade I poplar AOS encoding gene (AOS1) was cloned and used to drive the expression of a Ăź-glucuronidase (GUS) gene in Arabidopsis. AOS is an essential enzyme in the lipoxygenase pathway that is responsible for the production of many nonvolatile oxylipins in plants, including the jasmonates, which are regulatory phytohormones coordinating a variety of biological and stress response functions. Consistent with AOS transcript expression patterns, we found that the poplar AOS1 promoter drives rapid and localized expression by wounding. The study provides insight on the responsive elements in the poplar AOS promoters, but more importantly identifies a strong wound-inducible and localized promoter for future applications.
Key Message: Populus AOSs separate phylogenetically into two clades, which show significant abundance differences in 19 promoter motifs. * AOS1 is predominantly expressed in growing vascular tissue in Populus * Populus AOS1 promoter drives rapid and localized expression by wounding in Arabidopsis
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