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AbstractUsing a global sample of high‐frequency data, I investigate how liquidity shocks affect intraday price movements. I find a negative association between liquidity shocks and price impact. This finding remains robust after considering the exogeneity of liquidity shocks, using alternative windows to measure liquidity shocks, and controlling for volume shocks and volatility shocks. Additional tests show that the documented relation stems from idiosyncratic shocks and sell‐order shocks. Moreover, I find that liquidity shocks are likely driven by uninformed traders. My evidence suggests that the market requires 30 min to accomplish price adjustments when meeting liquidity shocks.

We show that some natural output conventions for error-free computation in chemical reaction networks (CRN) lead to a common level of computational expressivity. Our main results are that the standard definition of error-free CRNs have equivalent computational power to 1) asymmetric and 2) democratic CRNs. The former have only "yes" voters, with the interpretation that the CRN's output is yes if any voters are present and no otherwise. The latter define output by majority vote among "yes" and "no" voters. Both results are proven via a generalized framework that simultaneously captures several definitions, directly inspired by a recent Petri net result of Esparza, Ganty, Leroux, and Majumder [CONCUR 2015]. These results support the thesis that the computational expressivity of error-free CRNs is intrinsic, not sensitive to arbitrary definitional choices. ; The first author is a postdoctoral fellow of the Research Foundation – Flanders (FWO). The second author was supported by NSF grant 1619343, and the third author by NSF grant 1618895.

The possibility of oscillating chemical reactions is discussed, and it is shown that in systems where only first order reactions occur oscillations around equilibrium states or stationary states are not possible. For systems described by non-linear differential equations, on the other hand, it is known that oscillations around stationary states can occur, since the equations of Volterra can be interpreted as describing a set of chemical reactions. The necessary and sufficient conditions for the occurrence of oscillations in a chemical system is derived as inequalities among the rate constants, using the criterion of Sturm. It is pointed out that none of the chemical reactions alleged to show oscillatory behaviour have been thoroughly investigated experimentally.

A mathematical model for reactive-transport processes in porous media is presented. The modeled system includes diffusion, electromigration and electroosmosis as the most relevant transport mechanism and water electrolysis at the electrodes, aqueous species complexation, precipitation and dissolution as the chemical reactions taken place during the treatment time. The model is based on the local chemical equilibrium for most of the reversible chemical reactions occurring in the process. As a novel enhancement of previous models, the local chemical equilibrium reactive-transport model is combined with the solution of the transient equations for the kinetics of those chemical reactions that have representative rates in the same order than the transport mechanisms. The model is validated by comparison of simulation and experimental results for an acid- enhanced electrokinetic treatment of a real Pb-contaminated calcareous soil. The kinetics of the main pH buffering process, the calcite dissolution, was defined by a simplified empirical kinetic law. Results show that the evaluation of kinetic rate entails a significant improvement of the model prediction capability. ; This work has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045. Part of this work was supported financially by the European Commission within the project LIFE12 ENV/IT/442 SEKRET "Sediment electrokinetic remediation technology for heavy metal pollution removal". Paz-Garcia acknowledges the financial support from the "Proyecto Puente - Plan Propio de Investigación y Transferencia de la Universidad de Málaga", code: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the financial support from the University of Malaga through a postdoctoral contract.