City University London

About: City University London is a education organization based out in London, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 5735 authors who have published 17285 publications receiving 453290 citations.

Illiquidity Contagion and Liquidity Crashes

Abstract: Liquidity providers often learn information about an asset from prices of other assets. We show that this generates a self-reinforcing positive relationship between price informativeness and liquidity. This relationship causes liquidity spillovers and is a source of fragility: a small drop in the liquidity of one asset can, through a feedback loop, result in a very large drop in market liquidity and price informativeness (a liquidity crash). This feedback loop provides a new explanation for comovements in liquidity and liquidity dry-ups. It also generates multiple equilibria.

Mental imagery and creativity: a meta-analytic review study.

Abstract: The reports of many creative individuals suggest the use of mental imagery in scientific and artistic production. A variety of protocols have tested the association between mental imagery and creativity, but the individual differences approach has been most frequently employed. This approach is assessed here through a range of meta-analytic tests. Database searches revealed 18 papers employing the individual differences approach that were subjected to a conservative set of selection criteria. Nine studies (1494 participants) were included in the final analyses. A marginal, but statistically significant, Fisher's Z-transformed correlation coefficient was revealed. Further analyses showed little difference between form and type of self-reported imagery and divergent thinking. Explanations for the failure to account for more than 3% of the variance in the data sets are discussed in the context of anecdotal reports, task validity, and design problems.

Miniature Multilevel Optical Memristive Switch Using Phase Change Material

Abstract: Optical memristive switches can be used as optical latching switches in which the switching state is changed only by applying an electrical Write/Erase pulse and maintained without an external power supply. We demonstrate an optical memristive switch based on a silicon multimode interferometer structure covered with nanoscale-sized Ge2Sb2Te5 (GST) material on top. The phase change of GST is triggered by resistive heating of the silicon layer beneath GST with an electrical pulse. Experimental results reveal that the optical transmissivity can be tuned in a controllable and repeatable manner. Partial crystallization of GST is obtained by controlling the width and amplitude of the electrical pulses. Crucially, we demonstrate that both Erase and Write operations, to and from any intermediate level, are possible with accurate control of the electrical pulses. Our work marks a significant step forward toward realizing photonic memristive switches without static power consumption, which are highly demanded in integrated photonics.

Supply-Chain Research Opportunities with the Poor as Suppliers or Distributors in Developing Countries

Abstract: Many social enterprises and some companies have developed supply chains with the poor as suppliers or distributors to alleviate poverty and to create revenues for themselves. Such supply chains have created new research opportunities because they raise issues fundamentally different from those examined in the existing operations management literature. We report this phenomenon of supply chains with the poor as suppliers or distributors in developing countries and identify operations management (OM) research opportunities. We also provide some stylized models to serve as potential seeds for modeling-based research in this area.

Evidence for a Conserved Quantity in Human Mobility

Abstract: Recent seminal works on human mobility have shown that individuals constantly exploit a small set of repeatedly visited locations1–3. A concurrent study has emphasized the explorative nature of human behaviour, showing that the number of visited places grows steadily over time4–7. How to reconcile these seemingly contradicting facts remains an open question. Here, we analyse high-resolution multi-year traces of ~40,000 individuals from 4 datasets and show that this tension vanishes when the long-term evolution of mobility patterns is considered. We reveal that mobility patterns evolve significantly yet smoothly, and that the number of familiar locations an individual visits at any point is a conserved quantity with a typical size of ~25. We use this finding to improve state-of-the-art modelling of human mobility4,8. Furthermore, shifting the attention from aggregated quantities to individual behaviour, we show that the size of an individual’s set of preferred locations correlates with their number of social interactions. This result suggests a connection between the conserved quantity we identify, which as we show cannot be understood purely on the basis of time constraints, and the ‘Dunbar number’9,10 describing a cognitive upper limit to an individual’s number of social relations. We anticipate that our work will spark further research linking the study of human mobility and the cognitive and behavioural sciences. Analysing high-resolution mobility traces from almost 40,000 individuals reveals that people typically revisit a set of 25 familiar locations day-to-day, but that this set evolves over time and is proportional to the size of their social sphere.