Leibniz described imaginary roots, negatives, and infinitesimals as useful fictions. But did he view such 'impossible' numbers mathematical entities? Alice Bob take on the labyrinth of current scholarship.

car body acceleration is an important factor affecting track safety and ride comfort, which are two primary aspects of railway systems. though track level is an important source of wagon body acceleration, no quantitative relation between them is available and the aim of this paper is to propose a method to address this issue. to do so, car body acceleration is determined using a 10 dof simulat...

CA1 place cells discharge in prospective and retrospective modes, possibly reflecting memory retrieval and encoding, respectively. In this issue of Neuron, Bieri et al. (2014) report that slow and fast gamma oscillations associate with prospective and retrospective discharge, indicating that gamma oscillations organize information-processing modes.

in this paper effects of fractured sleepers on rail track vibration under moving wheelset have been investigated. two parallel rails of the track have been modeled as euler-bernoulli beams on elastic points as rail pads. also sleepers have been modeled as visco-elastic euler-bernoulli beams. it is assumed that, some sleepers under the rail track have been fractured and modeled by two beams. the...

Car body acceleration is an important factor affecting track safety and ride comfort, which are two primary aspects of railway systems. Though track level is an important source of wagon body acceleration, no quantitative relation between them is available and the aim of this paper is to propose a method to address this issue. To do so, car body acceleration is determined using a 10 DOF simulat...