42,098 research outputs found
Effects of Transit Signal Priority on Traffic Safety: Interrupted Time Series Analysis of Portland, Oregon, Implementations
Transit signal priority (TSP) has been implemented to transit systems in many
cities of the United States. In evaluating TSP systems, more attention has been
given to its operational effects than to its safety effects. Existing studies
assessing safety effects of TSP reported mixed results, indicating that the
safety effects of TSP vary in different contexts. In this study, TSP
implementations in Portland, Oregon, were assessed using interrupted time
series analysis (ITSA) on month-to-month changes in number of crashes from
January 1995 to December 2010. Single-group and controlled ITSA were conducted
for all crashes, property-damage-only crashes, fatal and injury crashes,
pedestrian-involved crashes, and bike-involved crashes. Evaluation of the
post-intervention period (2003 to 2010) showed a reduction in all crashes on
street sections with TSP (-4.5 percent), comparing with the counterfactual
estimations based on the control group data. The reduction in
property-damage-only crashes (-10.0 percent) contributed the most to the
overall reduction. Fatal and injury crashes leveled out after TSP
implementation but did not change significantly comparing with the control
group. Pedestrian and bike-involved crashes were found to increase in the
post-intervention period with TSP, comparing with the control group. Potential
reasons to these TSP effects on traffic safety were discussed.Comment: Published in Accident Analysis & Preventio
Layout Decomposition for Quadruple Patterning Lithography and Beyond
For next-generation technology nodes, multiple patterning lithography (MPL)
has emerged as a key solution, e.g., triple patterning lithography (TPL) for
14/11nm, and quadruple patterning lithography (QPL) for sub-10nm. In this
paper, we propose a generic and robust layout decomposition framework for QPL,
which can be further extended to handle any general K-patterning lithography
(K4). Our framework is based on the semidefinite programming (SDP)
formulation with novel coloring encoding. Meanwhile, we propose fast yet
effective coloring assignment and achieve significant speedup. To our best
knowledge, this is the first work on the general multiple patterning
lithography layout decomposition.Comment: DAC'201
Dynamic allosteric control of noncovalent DNA catalysis reactions
Allosteric modulation of catalysis kinetics is prevalent in proteins and has been rationally designed for ribozymes. Here, we present an allosteric DNA molecule that, in its active configuration, catalyzes a noncovalent DNA reaction. The catalytic activity is designed to be modulated by the relative concentrations of two DNA regulator molecules, one an inhibitor and the other an activator. Dynamic control of the catalysis rate is experimentally demonstrated via three cycles of up and down regulation by a factor of over 10. Unlike previous works, both the allosteric receptor and catalytic core are designed, rather than evolved. This allows flexibility in the sequence design and modularity in synthetic network construction
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