158 research outputs found
Battle of Sharing Economy: The Contingent Effects of Ride-Sharing on Taxi Industry
With the rapid growth of sharing economy, there has been a bitter controversy on the disruptive nature of sharing economy to threaten traditional industry. This study examines the impact of ride-sharing services, which is one of the most successful business models in sharing economy, on taxi industry. Using comprehensive data on Uber and taxi transactions in New York City from April to September 2014, we find that ride-sharing is negatively associated with the demand for taxis. Interestingly, this effect is contingent upon market- and customer-segments. The negative effect of Uber on taxis is mostly driven in Manhattan and high-income areas, where most taxis are concentrated. Furthermore, our analyses reveal that ride-sharing services take more demand of taxi customers who pay by cash and who are price-sensitive, by providing relative advantages of ride-sharing platforms. In addition, taxi customers in groups appear to more switch to ride-sharing services. Relevant implications for both research and practice are discussed
Stability and Generalization Capabilities of Message Passing Graph Neural Networks
Message passing neural networks (MPNN) have seen a steep rise in popularity
since their introduction as generalizations of convolutional neural networks to
graph structured data, and are now considered state-of-the-art tools for
solving a large variety of graph-focused problems. We study the generalization
capabilities of MPNNs in graph classification. We assume that graphs of
different classes are sampled from different random graph models. Based on this
data distribution, we derive a non-asymptotic bound on the generalization gap
between the empirical and statistical loss, that decreases to zero as the
graphs become larger. This is proven by showing that a MPNN, applied on a
graph, approximates the MPNN applied on the geometric model that the graph
discretizes.Comment: 44 pages, typos corrected, preprin
End of the World Perspective to BCFT
In this work, we study the end-of-the-world (EOW) branes anchored to the
boundaries of BCFT dual to the BTZ black hole. First, we explore the
thermodynamics of the boundary system consisting of the conformal boundary and
two EOW branes. This thermodynamics is extended by the tension appearing as the
effective cosmological constant of JT black holes on the EOW branes. The
tension contribution is identified with the shadow entropy equivalent to the
boundary entropy of the BCFT. The thermodynamics of the JT black holes
and the bulk of BCFT can be combined into a novel grafted thermodynamics
based on the first law. Second, we focus on the observer's view of the EOW
branes by lowering the temperature. We show that the EOW branes generate a
scale called ``reefs" inside the horizon. This scale also appears in the
grafted thermodynamics. At high temperatures, observers on the EOW branes see
their respective event horizons. The reef starts to grow relatively to the
horizon size at the temperature, . As the temperature cools down the
reef area fills the entire interior of the JT black holes at the temperature
. Then, the observers recognize their horizons disappear and see the
large density of the energy flux. At this temperature, the two JT regions
become causally connected. This connected spacetime has two asymptotic
boundaries with a conformal matter. Also, we comment on the grafted
thermodynamics to higher dimensions in Appendix B.Comment: 29 pages, 9 figure
Cross talk by extensive domain wall motion in arrays of ferroelectric nanocapacitors
We report on extensive domain wall motion in ferroelectric nanocapacitor
arrays investigated by piezoresponse force microscopy. Under a much longer or
higher bias voltage pulse, compared to typical switching pulse conditions,
domain walls start to propagate into the neighbouring capacitors initiating a
significant cross-talk. The propagation paths and the propagated area into the
neighbouring capacitors were always the same under repeated runs. The
experimental and the simulated results show that the observed cross-talk is
related to the capacitor parameters combined with local defects. The results
can be helpful to test the reliability of nanoscale ferroelectric memory
devices
- …