Talking Helps: Evolving Communicating Agents for the Predator-Prey Pursuit Problem

We analyze a general model of multi-agent communication in which all agents communicate simultaneously to a message board. A genetic algorithm is used to evolve multi-agent languages for the predator agents in a version of the predator-prey pursuit problem. We show that the resulting behavior of the communicating multi-agent system is equivalent to that of a Mealy finite state machine whose states are determined by the agents’ usage of the evolved language. Simulations show that the evolution of a communication language improves the performance of the predators. Increasing the language size (and thus increasing the number of possible states in the Mealy machine) improves the performance even further. Furthermore, the evolved communicating predators perform significantly better than all previous work on similar preys. We introduce a method for incrementally increasing the language size which results in an effective coarse-to-fine search that significantly reduces the evolution time required to find a solution. We present some observations on the effects of language size, experimental setup, and prey difficulty on the evolved Mealy machines. In particular, we observe that the start state is often revisited, and incrementally increasing the language size results in smaller Mealy machines. Finally, a simple rule is derived that provides a pessimistic estimate on the minimum language size that should be used for any multi-agent problem

JB-300: An advanced medium size transport for 2005

In the fall of 1992, the TAC Team was presented with a Request for Proposal (PFP) for a mid-size (250-350 passenger) commercial transport. The aircraft was to be extremely competitive in the areas of passenger comfort, performance, and economic aspects. Through the use of supercritical airfoils, a technologically advanced Very High By-pass Ratio (VHBR) turbofan engine, a low overall drag configuration, a comparable interior layout, and mild use of composites, the JB-300 offers an economically viable choice to the airlines. The cents per passenger mile of the JB-300 is 1.76, which is considerably lower than current aircraft in the same range. Overall, the JB-300 is a technologically advanced aircraft, which will meet the demands of the 21st century

Experimental results for nulling the effective thermal expansion coefficient of fused silica fibres under a static stress

We have experimentally demonstrated that the effective thermal expansion coefficient of a fused silica fibre can be nulled by placing the fibre under a particular level of stress. Our technique involves heating the fibre and measuring how the fibre length changes with temperature as the stress on the fibre was systematically varied. This nulling of the effective thermal expansion coefficient should allow for the complete elimination of thermoelastic noise and is essential for allowing second generation gravitational wave detectors to reach their target sensitivity. To our knowledge this is the first time that the cancelation of the thermal expansion coefficient with stress has been experimentally observed

Death or survival from invasive pneumococcal disease in Scotland: associations with serogroups and multilocus sequence types

We describe associations between death from invasive pneumococcal disease (IPD) and particular serogroups and sequence types (STs) determined by multilocus sequence typing (MLST) using data from Scotland. All IPD episodes where blood or cerebrospinal fluid (CSF) culture isolates were referred to the Scottish Haemophilus, Legionella, Meningococcal and Pneumococcal Reference Laboratory (SHLMPRL) from January 1992 to February 2007 were matched to death certification records by the General Register Office for Scotland. This represented 5959 patients. The median number of IPD cases in Scotland each year was 292. Deaths, from any cause, within 30 days of pneumococcal culture from blood or CSF were considered to have IPD as a contributing factor. Eight hundred and thirty-three patients died within 30 days of culture of Streptococcus pneumoniae from blood or CSF [13.95%; 95% confidence interval (13.10, 14.80)]. The highest death rates were in patients over the age of 75. Serotyping data exist for all years but MLST data were only available from 2001 onward. The risk ratio of dying from infection due to particular serogroups or STs compared to dying from IPD due to all other serogroups or STs was calculated. Fisher's exact test with Bonferroni adjustment for multiple testing was used. Age adjustment was accomplished using the Cochran-Mantel-Haenszel test and 95% confidence intervals were reported. Serogroups 3, 11 and 16 have increased probability of causing fatal IPD in Scotland while serogroup 1 IPD has a reduced probability of causing death. None of the 20 most common STs were significantly associated with death within 30 days of pneumococcal culture, after age adjustment. We conclude that there is a stronger association between a fatal outcome and pneumococcal capsular serogroup than there is between a fatal outcome and ST

Low-temperature mechanical dissipation of thermally evaporated indium film for use in interferometric gravitational wave detectors

Indium bonding is under consideration for use in the construction of cryogenic mirror suspensions in future gravitational wave detectors. This paper presents measurements of the mechanical loss of a thermally evaporated indium film over a broad range of frequencies and temperatures. It provides an estimate of the resulting thermal noise at 20 K for a typical test mass geometry for a cryogenic interferometric gravitational wave detector from an indium layer between suspension elements

Complex Challenges and New Opportunities: Building the Framework for Boundary Review. An Assessment of PPS’s Organizational Readiness and Options for Citizen Engagement

On February 25, 2013, the PPS Board unanimously approved Resolution 4718, which directs staff “to develop and recommend a process for a comprehensive review of school boundaries district-wide and policies related to student assignment and transfer to better align with the Racial Educational Equity Policy and promote strong capture rates and academic programs at every grade level.” To deal with the student assignment and transfer policy issues, Superintendent Carole Smith charged the “Superintendent’s Advisory Committee on Enrollment and Transfer” (SACET) with recommending changes to student assignment and transfer policies to bring them into alignment with the district’s racial educational equity policy. As for the Districtwide Boundary Review component, in December 2013, Portland Public Schools entered into an Intergovernmental Agreement with the Center for Public Service (CPS) at Portland State University (PSU) to assist the District with eventually achieving two important tasks: Devise and implement a process to engage a wide range of current and future PPS parents, students and staff, community organizations; and other key stakeholders to conduct a comprehensive District-wide Boundary Review and recommend new PPS school boundaries for adoption by the Portland School Board; Create a flexible and dynamic “Boundary Review Framework” on which the current and future boundary-setting processes will be based. CPS proposed a three-phase approach for the “PPS District-Wide Boundary Framework” project, which would include recommendations at the end of each Phase as to recommended next steps. As initially outlined from the vantage point of October 2013, the proposed approach would be as follows: Phase I (3 months): Initial Assessment and Framework Recommendations Phase II (7-8 months): Stakeholder and Community Engagement Phase III (4 months): Final Recommendations, Community Deliberations, and Decision Making This report concludes Phase I and includes the Findings and Recommendations from our Initial Assessment

Evaluating the impact of minimum unit pricing (MUP) on alcohol sales after 3 years of implementation in Scotland: A controlled interrupted time-series study

Background and aims: On 1 May 2018, Scotland introduced minimum unit pricing (MUP), a strength-based floor price below which alcohol cannot be sold, throughout all alcoholic beverages. The legislation necessitates an evaluation of its impact across a range of outcomes that will inform whether MUP will continue beyond its sixth year. We measured the impact of MUP on per-adult alcohol sales (as a proxy for consumption) after 3 years of implementation. Design, setting and participants: Controlled interrupted time-series regression was used to assess the impact of MUP on alcohol sales in Scotland after 3 years of implementation, with England and Wales (EW) being the control group. In adjusted analyses, we included household disposable income, on-trade alcohol sales (in off-trade analyses) and substitution between drink categories (in drink category analyses) as covariates. Measurements: Weekly data were assessed on the volume of pure alcohol sold in Scotland and EW between January 2013 and May 2021, expressed as litres of pure alcohol per adult. The impact of MUP on total (on- and off-trade combined), off-trade and on-trade alcohol sales was assessed separately. Results: The introduction of MUP in Scotland was associated with a 3.0% (95% confidence interval = 1.8−4.2%) net reduction in total alcohol sales per adult after adjustment for the best available geographical control, disposable income and substitution. This reflects a 1.1% fall in Scotland in contrast to a 2.4% increase in EW. The reduction in total alcohol sales in Scotland was driven by reduced sales of beer, spirits, cider and perry. The reduction in total sales was due to reductions in sales of alcohol through the off-trade. There was no evidence of any change in on-trade alcohol sales. Conclusion: Minimum unit pricing has been effective in reducing population-level alcohol sales in Scotland in the 3 years since implementation