IIASA Holdings of Materials on National Settlement Systems and Policies

This Working Paper is intended as the first snapshot of a growing list of literature and materials accumulated at Laxenburg relevant to the study of national urban settlement systems and urban growth policies in advanced countries

The reversibility of sea ice loss in a state-of-the-art climate model

Rapid Arctic sea ice retreat has fueled speculation about the possibility of threshold (or ‘tipping point’) behavior and irreversible loss of the sea ice cover. We test sea ice reversibility within a state-of-the-art atmosphere–ocean global climate model by increasing atmospheric carbon dioxide until the Arctic Ocean becomes ice-free throughout the year and subsequently decreasing it until the initial ice cover returns. Evidence for irreversibility in the form of hysteresis outside the envelope of natural variability is explored for the loss of summer and winter ice in both hemispheres. We find no evidence of irreversibility or multiple ice-cover states over the full range of simulated sea ice conditions between the modern climate and that with an annually ice-free Arctic Ocean. Summer sea ice area recovers as hemispheric temperature cools along a trajectory that is indistinguishable from the trajectory of summer sea ice loss, while the recovery of winter ice area appears to be slowed due to the long response times of the ocean near the modern winter ice edge. The results are discussed in the context of previous studies that assess the plausibility of sea ice tipping points by other methods. The findings serve as evidence against the existence of threshold behavior in the summer or winter ice cover in either hemisphere

Balancing Apples and Oranges: Methodologies for Facility Siting Decisions

Evaluating alternative sites for major constructed facilities requires comparing impacts of different levels and different types to establish desirable yet feasible balances. Currently employed and proposed, methodologies for evaluating the desirability of sets of impacts generated by large facilities are compared, and the theoretical assumptions implicit in each are discussed. In aggregate, the three sets of methodologies considered are Cost-Benefit Analysis and its various modifications, matrix or tableau methods of several sorts, and, preference theory (of which utility is a special case). Primary attention is given to the structure of objective functions defined over impacts

Safe nights out: Workers’ perspectives on tackling violence against women and girls

Existing research focused on workers within the night-timeeconomy (NTE) is limited. In this unique study, research was conducted with workers from a wide range of professions and occupations. The study garnered important insights into NTE workers’ understanding and experience of violence against women and girls (VAWG). Workers observed a strong relationship between alcohol consumption and VAWG and were knowledgeable about spiking, perceiving this practice to be growing. Strong protocols were in place to support women when spiking was alleged. The understanding of VAWG was, in contrast, broad but inconsistent. NTE workers provide myriad ways to support and protect women who are out at night. However, responses to potential incidents of VAWG are shaped by intuition, rather than being rooted in formal knowledge and institutional protocols. The decision to intervene is usually based on NTE workers’ levels of experience, confidence, and subjective perception of risk – described as ‘going with your gut’. There were, however, some good examples of where formal training had been provided and found to be useful. Specifically,there was evidence that many of the initiatives established as part of the Safer Streets project were making a difference. Respondents valued the training that they had received (such as zero-tolerance), and they recognised the important role that Street Pastors provide. Nevertheless, several training gaps were identified. Specifically, workers reported that they wanted to be better equipped to identify potential perpetrators of crime and would welcome advice on how to enhance personal and customer safety. NTE workers would also benefit from knowing more about the location and value of safe havens. The study showed that while many venues offer support to customers, there is some inconsistency in the way that safety measures are advertised and enacted

Efficient generation of single and entangled photons on a silicon photonic integrated chip

We present a protocol for generating on-demand, indistinguishable single photons on a silicon photonic integrated chip. The source is a time-multiplexed spontaneous parametric down-conversion element that allows optimization of single-photon versus multiphoton emission while realizing high output rate and indistinguishability. We minimize both the scaling of active elements and the scaling of active element loss with multiplexing. We then discuss detection strategies and data processing to further optimize the procedure. We simulate an improvement in single-photon-generation efficiency over previous time-multiplexing protocols, assuming existing fabrication capabilities. We then apply this system to generate heralded Bell states. The generation efficiency of both nonclassical states could be increased substantially with improved fabrication procedures.Comment: 7 pages, 4 figure

Using virtual worlds for role play simulation in child psychiatry: an evaluation study

Aims and method: To develop and evaluate a novel teaching session on clinical assessment using role play simulation. Teaching and research sessions occurred sequentially in computer laboratories. Ten medical students were divided into two online small-group teaching sessions. Students role-played as clinician avatars and the teacher played a suicidal adolescent avatar. Questionnaire and focus-group methodology evaluated participants’ attitudes to the learning experience. Quantitative data were analysed using SPSS, qualitative data through nominal-group and thematic analyses. Results: Participants reported improvements in psychiatric skills/knowledge, expressing less anxiety and more enjoyment than role-playing face to face. Simulator fidelity correlated positively with utility. Some participants expressed concern about added value over other learning methods and non-verbal communication. Clinical implications: The study shows that virtual worlds can successfully host role play simulation, valued by students as a useful learning method. The potential for distance learning would allow delivery irrespective of geographical distance and boundaries

Detection-Loophole-Free Test of Quantum Nonlocality, and Applications

We present a source of entangled photons that violates a Bell inequality free of the "fair-sampling" assumption, by over 7 standard deviations. This violation is the first experiment with photons to close the detection loophole, and we demonstrate enough "efficiency" overhead to eventually perform a fully loophole-free test of local realism. The entanglement quality is verified by maximally violating additional Bell tests, testing the upper limit of quantum correlations. Finally, we use the source to generate secure private quantum random numbers at rates over 4 orders of magnitude beyond previous experiments.Comment: Main text: 5 pages, 2 figures, 1 table. Supplementary Information: 7 pages, 2 figure