3,666 research outputs found
Genome-wide organization of eukaryotic pre-initiation complex is influenced by nonconsensus protein-DNA binding
Genome-wide binding preferences of the key components of eukaryotic
pre-initiation complex (PIC) have been recently measured with high resolution
in Saccharomyces cerevisiae by Rhee and Pugh (Nature (2012) 483:295-301). Yet
the rules determining the PIC binding specificity remain poorly understood. In
this study we show that nonconsensus protein-DNA binding significantly
influences PIC binding preferences. We estimate that such nonconsensus binding
contribute statistically at least 2-3 kcal/mol (on average) of additional
attractive free energy per protein, per core promoter region. The predicted
attractive effect is particularly strong at repeated poly(dA:dT) and
poly(dC:dG) tracts. Overall, the computed free energy landscape of nonconsensus
protein-DNA binding shows strong correlation with the measured genome-wide PIC
occupancy. Remarkably, statistical PIC binding preferences to both
TFIID-dominated and SAGA-dominated genes correlate with the nonconsensus free
energy landscape, yet these two groups of genes are distinguishable based on
the average free energy profiles. We suggest that the predicted nonconsensus
binding mechanism provides a genome-wide background for specific promoter
elements, such as transcription factor binding sites, TATA-like elements, and
specific binding of the PIC components to nucleosomes. We also show that
nonconsensus binding influences transcriptional frequency genome-wide
Machine learning for early detection of traffic congestion using public transport traffic data
The purpose of this project is to provide better knowledge of how the bus travel times is affected by congestion and other problems in the urban traffic environment. The main source of data for this study is second-level measurements coming from all buses in the Linköping region showing the location of each vehicle.The main goal of this thesis is to propose, implement, test and optimize a machine learning algorithm based on data collected from regional buses from Sweden so that it is able to perform predictions on the future state of the urban traffic.El objetivo principal de este proyecto es proponer, implementar, probar y optimizar un algoritmo de aprendizaje automático basado en datos recopilados de autobuses regionales de Suecia para que poder realizar predicciones sobre el estado futuro del tráfico urbano.L'objectiu principal d'aquest projecte Ă©s proposar, implementar, provar i optimitzar un algoritme de machine learning basat en dades recollides a partir d'autobusos regionals de Suècia de manera per poder realitzar prediccions sobre l'estat futur del trĂ nsit urbĂ
Public transit route planning through lightweight linked data interfaces
While some public transit data publishers only provide a data dump – which only few reusers can afford to integrate within their applications – others provide a use case limiting origin-destination route planning api. The Linked Connections framework instead introduces a hypermedia api, over which the extendable base route planning algorithm “Connections Scan Algorithm” can be implemented. We compare the cpu usage and query execution time of a traditional server-side route planner with the cpu time and query execution time of a Linked Connections interface by evaluating query mixes with increasing load. We found that, at the expense of a higher bandwidth consumption, more queries can be answered using the same hardware with the Linked Connections server interface than with an origin-destination api, thanks to an average cache hit rate of 78%. The findings from this research show a cost-efficient way of publishing transport data that can bring federated public transit route planning at the fingertips of anyone
Efficient Generation of Geographically Accurate Transit Maps
We present LOOM (Line-Ordering Optimized Maps), a fully automatic generator
of geographically accurate transit maps. The input to LOOM is data about the
lines of a given transit network, namely for each line, the sequence of
stations it serves and the geographical course the vehicles of this line take.
We parse this data from GTFS, the prevailing standard for public transit data.
LOOM proceeds in three stages: (1) construct a so-called line graph, where
edges correspond to segments of the network with the same set of lines
following the same course; (2) construct an ILP that yields a line ordering for
each edge which minimizes the total number of line crossings and line
separations; (3) based on the line graph and the ILP solution, draw the map. As
a naive ILP formulation is too demanding, we derive a new custom-tailored
formulation which requires significantly fewer constraints. Furthermore, we
present engineering techniques which use structural properties of the line
graph to further reduce the ILP size. For the subway network of New York, we
can reduce the number of constraints from 229,000 in the naive ILP formulation
to about 4,500 with our techniques, enabling solution times of less than a
second. Since our maps respect the geography of the transit network, they can
be used for tiles and overlays in typical map services. Previous research work
either did not take the geographical course of the lines into account, or was
concerned with schematic maps without optimizing line crossings or line
separations.Comment: 7 page
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