Multidimensional Coherent Spectroscopy of a Semiconductor Microcavity

Rephasing and non-rephasing two-dimensional coherent spectra map the anti-crossing associated with normal-mode splitting in a semiconductor microcavity. For a 12-meV detuning range near zero detuning, it is observed that there are two diagonal features related to the intra-action of exciton-polariton branches and two off-diagonal features related to coherent interaction between the polaritons. At negative detuning, the lineshape properties of the diagonal intra-action features are distinguishable and can be associated with cavity-like and exciton-like modes. A biexcitonic companion feature is observed, shifted from the exciton feature by the biexciton binding energy. Closer to zero detuning, all features are enhanced and the diagonal intra-action features become nearly equal in amplitude and linewidth. At positive detuning the exciton- and cavity-like characteristics return to the diagonal intra-action features. Off-diagonal interaction features exhibit asymmetry in their amplitudes throughout the detuning range. The amplitudes are strongly modulated (and invert) at small positive detuning, as the lower polariton branch crosses the bound biexciton energy determined from negative detuning spectra.Comment: 13 pages, 4 figure

Geospatial analysis and living urban geometry

This essay outlines how to incorporate morphological rules within the exigencies of our technological age. We propose using the current evolution of GIS (Geographical Information Systems) technologies beyond their original representational domain, towards predictive and dynamic spatial models that help in constructing the new discipline of "urban seeding". We condemn the high-rise tower block as an unsuitable typology for a living city, and propose to re-establish human-scale urban fabric that resembles the traditional city. Pedestrian presence, density, and movement all reveal that open space between modernist buildings is not urban at all, but neither is the open space found in today's sprawling suburbs. True urban space contains and encourages pedestrian interactions, and has to be designed and built according to specific rules. The opposition between traditional self-organized versus modernist planned cities challenges the very core of the urban planning discipline. Planning has to be re-framed from being a tool creating a fixed future to become a visionary adaptive tool of dynamic states in evolution

Agent-based model on resilience-oriented rapid responses of road networks under seismic hazard

This paper explores a new pathway towards seismic resilience of Road Networks (RNs) under earthquake hazards, by leveraging post-shock rapid responses as the key to minimize the functionality losses of RNs, especially in the immediate aftermath of earthquakes. Accordingly, an agent-based modelling (ABM) framework is developed to enable the nuanced examination on resilience of earthquake-damaged RNs, when different system repair approaches are considered. In this framework, those different approaches are predicated on the damage level of individual bridges and on the system recovery timeline, i.e. the response to rehabilitation need is considered as a function of the time elapsed from the event. Each approach is represented by a different agent, whose behaviour is shaped by a set of pre-defined behavioural attributes, while the interplay among those agents is also accounted for, during the entirety of post-shock recovery campaigns. To demonstrate its applicability, the ABM framework is applied to a real-world RN across Luchon, France. As shown by the case-study, post-shock rapid responses are found to be a viable strategy to increase the recovery rate of RNs’ functionality in the immediate-, and mid-term aftermath of damaging earthquakes, and ultimately, to improve the seismic resilience thereof

Fostering Production of Pharmaceutical Products in Developing Countries

The ways in which pharmaceutical products are currently developed, manufactured, and distributed fail to meet the needs of developing countries. The recent emergence of new infectious diseases, the associated surge of healthcare nationalism, and the prevalence of substandard and falsified drugs have strengthened substantially the net benefits of augmenting the capacity of developing countries to produce such products locally. Most previous efforts to do so have foundered. The chance of success in the future would be maximized by the adoption of five strategies : (a) clarifying the zones of discretion created by the relevant treaties to ensure that local firms have the freedom to operate; (b) the use of “production triangles” (collaborations among developing-country governments, local firms, and developed-country pharmaceutical firms) to reduce regulatory impediments and to ensure that there exist adequate markets for locally produced products; (c) developing the human capital base in developing countries through initiatives such as an international apprenticeship system; (d) strengthening the legal and administrative apparatus for preventing the dissemination in developing countries of substandard and falsified drugs; and (e) reliance on regional economic communities to create economies of scale and to ensure that medicines are made available to all residents of all developing countries, while also stimulating competition among local firms. These strategies would both save many lives and strengthen the economic and social development of developing and least-developed countries

Five sepharose-bound ligands for the chromatographic purification of Clostridium collagenase and clostripain

Social media data have provoked a mixed response from researchers. While there is great enthusiasm for this new source of social data – Twitter data in particular – concerns are also expressed about their biases and unknown provenance and, consequently, their credibility for social research. This article seeks a middle path, arguing that we must develop better understanding of the construction and circulation of social media data to evaluate their appropriate uses and the claims that might be made from them. Building on sociotechnical approaches, we propose a high-level abstraction of the ‘pipeline’ through which social media data are constructed and circulated. In turn, we explore how this shapes the populations and samples that are present in social media data and the methods that generate data about them. We conclude with some broad principles for supporting methodologically informed social media research in the future

Analyzing and predicting the spatial penetration of Airbnb in U.S. cities

In the hospitality industry, the room and apartment sharing platform of Airbnb has been accused of unfair competition. Detractors have pointed out the chronic lack of proper legislation. Unfortunately, there is little quantitative evidence about Airbnb's spatial penetration upon which to base such a legislation. In this study, we analyze Airbnb's spatial distribution in eight U.S. urban areas, in relation to both geographic, socio-demographic, and economic information. We find that, despite being very different in terms of population composition, size, and wealth, all eight cities exhibit the same pattern: that is, areas of high Airbnb presence are those occupied by the \newpart{``talented and creative''} classes, and those that are close to city centers. This result is consistent so much so that the accuracy of predicting Airbnb's spatial penetration is as high as 0.725