Design study of general aviation collision avoidance system

The selection and design of a time/frequency collision avoidance system for use in general aviation aircraft is discussed. The modifications to airline transport collision avoidance equipment which were made to produce the simpler general aviation system are described. The threat determination capabilities and operating principles of the general aviation system are illustrated

Is There a Doctor in the House? Medical Ethics and the Doctoral Honorific

The proliferation of professional doctorates has reinvigorated debate over the use of the doctoral honorific. Doctorate holders are often addressed as “doctor” in academic contexts, but idiomatic American English associates “doctor” with physicians—licensed clinicians with doctoral degrees in medicine. The possibility of patient confusion has historically justified proscription of the doctoral honorific by others, including nurses, but recently such proscriptions have been withdrawn. An examination of history, language, and ethical reasoning leads us to conclude that, in the context of patient interaction, clinicians should eschew the doctoral honorific entirely. We think it appropriate for professionals to rely on training-pathway titles as part of their professional duty to inform. In particular, we argue that licensed clinicians with doctoral degrees in medicine should embrace the title of “physician.

Do topical repellents divert mosquitoes within a community? Health equity implications of topical repellents as a mosquito bite prevention tool.

OBJECTIVES: Repellents do not kill mosquitoes--they simply reduce human-vector contact. Thus it is possible that individuals who do not use repellents but dwell close to repellent users experience more bites than otherwise. The objective of this study was to measure if diversion occurs from households that use repellents to those that do not use repellents. METHODS: The study was performed in three Tanzanian villages using 15%-DEET and placebo lotions. All households were given LLINs. Three coverage scenarios were investigated: complete coverage (all households were given 15%-DEET), incomplete coverage (80% of households were given 15%-DEET and 20% placebo) and no coverage (all households were given placebo). A crossover study design was used and coverage scenarios were rotated weekly over a period of ten weeks. The placebo lotion was randomly allocated to households in the incomplete coverage scenario. The level of compliance was reported to be close to 100%. Mosquito densities were measured through aspiration of resting mosquitoes. Data were analysed using negative binomial regression models. FINDINGS: Repellent-users had consistently fewer mosquitoes in their dwellings. In villages where everybody had been given 15%-DEET, resting mosquito densities were fewer than half that of households in the no coverage scenario (Incidence Rate Ratio [IRR]=0.39 (95% confidence interval [CI]: 0.25-0.60); p<0.001). Placebo-users living in a village where 80% of the households used 15%-DEET were likely to have over four-times more mosquitoes (IRR=4.17; 95% CI: 3.08-5.65; p<0.001) resting in their dwellings in comparison to households in a village where nobody uses repellent. CONCLUSIONS: There is evidence that high coverage of repellent use could significantly reduce man-vector contact but with incomplete coverage evidence suggests that mosquitoes are diverted from households that use repellent to those that do not. Therefore, if repellents are to be considered for vector control, strategies to maximise coverage are required

Effects of Landscape Composition and Configuration on Migrating Songbirds: Inference from an Individual-Based Model

The behavior of long-distance migrants during stopover is constrained by the need to quickly and safely replenish energetic reserves. Replenishing fuel stores at stopover sites requires adjusting to unfamiliar landscapes with little to no information about the distribution of resources. Despite their critical importance to the success of songbird migration, the effects of landscape composition and configuration on fuel deposition rates (FDR [g/d]), the currency of migration, has not been tested empirically. Our objectives were to understand the effects of heterogeneous landscapes on FDR of forest-dwelling songbirds during spring migration. The results of field experiments were used to parameterize a spatially explicit, individual-based model of forest songbird movement and resulting FDR. Further field experiments were used to validate the results from the individual-based model. In simulation experiments, we altered a Gulf South landscape in a factorial design to predict the effects of future patterns under different scenarios of land use change in which the abundance of high-quality hardwood habitat and the spatial aggregation of habitat varied. Simulated FDR decreased as the amount of hardwood in the landscape decreased from 41% to 22% to 12%. Further, migrants that arrived in higher-quality habitat types gained more mass. Counter to our expectations, FDR was higher with lower spatial aggregation of habitat. Differences in refueling rates may be most influenced by whether or not an individual experiences an initial searching cost after landing in poor-quality habitat. Therefore, quickly locating habitat with sufficient food resources at each stopover may be the most important factor determining a successful migration. Our findings provide empirical evidence for the argument that hardwood forest cover is a primary determinant of the quality of a stopover site in this region. This study represents the first effort to empirically quantify FDRs based on the configuration of landscapes

Failure to Replicate a Genetic Association May Provide Important Clues About Genetic Architecture

Replication has become the gold standard for assessing statistical results from genome-wide association studies. Unfortunately this replication requirement may cause real genetic effects to be missed. A real result can fail to replicate for numerous reasons including inadequate sample size or variability in phenotype definitions across independent samples. In genome-wide association studies the allele frequencies of polymorphisms may differ due to sampling error or population differences. We hypothesize that some statistically significant independent genetic effects may fail to replicate in an independent dataset when allele frequencies differ and the functional polymorphism interacts with one or more other functional polymorphisms. To test this hypothesis, we designed a simulation study in which case-control status was determined by two interacting polymorphisms with heritabilities ranging from 0.025 to 0.4 with replication sample sizes ranging from 400 to 1600 individuals. We show that the power to replicate the statistically significant independent main effect of one polymorphism can drop dramatically with a change of allele frequency of less than 0.1 at a second interacting polymorphism. We also show that differences in allele frequency can result in a reversal of allelic effects where a protective allele becomes a risk factor in replication studies. These results suggest that failure to replicate an independent genetic effect may provide important clues about the complexity of the underlying genetic architecture. We recommend that polymorphisms that fail to replicate be checked for interactions with other polymorphisms, particularly when samples are collected from groups with distinct ethnic backgrounds or different geographic regions

SuperGaN: Synthesis of NbTiN/GaN/NbTiN Tunnel Junctions

Nb-based circuits have broad applications in quantum-limited photon detectors, low-noise parametric amplifiers, superconducting digital logic circuits, and low-loss circuits for quantum computing. The current state-of-the-art approach for superconductor-insulator-superconductor (SIS) junction material is the Gurvitch trilayer process based on magnetron sputtering of Nb electrodes with Al-Oxide or AlN tunnel barriers grown on an Al overlayer. However, a current limitation of elemental Nb-based circuits is the low-loss operation of THz circuits operating above the 670 GHz gap frequency of Nb and operation at higher temperatures for projects with a strict power budget, such as space-based applications. NbTiN is an alternative higher energy gap material and we have previously reported on the first NbTiN/AlN/NbTiN superconducting-insulating-superconducting (SIS) junctions with an epitaxially grown AlN tunnel barrier. One drawback of a directly grown tunnel barrier compared to thermal oxidation or plasma nitridation is control of the barrier thickness and uniformity across a substrate, leading to variations in current density (Jc). Semiconductor barriers with smaller barrier heights enable thicker tunnel barriers for a given Jc. GaN is an alternative semiconductor material with a closed-packed Wurtzite crystal structure similar to AlN and it can be epitaxially grown as a tunnel barrier using the Reactive Bias Target Ion Beam Deposition (RBTIBD) technique. This work presents the preliminary results of the first reported high-quality NbTiN/GaN/NbTiN heterojunctions with underdamped SIS I(V) characteristics.Comment: Presented at the 16th EUROPEAN CONFERENCE ON APPLIED SUPERCONDUCTIVIT

Urban data cultures in post-socialist countries: challenges for evidence-based policy towards housing sustainability

This draft report summarises the initial results from the research project "Urban Data Cultures: Understanding Creation and Management of Housing-Related Information in Post-Communist Republics". This project seeks to better understand the how geographically-varied ‘data cultures’ (i.e. variegated representations, values, norms, epistemologies, practices, infrastructures, standards, power structures, etc, through which data is produced and used) inform the monitoring of progress towards the UN’s Sustainable Development Goals (SDGs), particularly as they relate to urban housing. For this pilot module, the countries of Georgia, Ukraine, Albania and Kyrgyzstan have been selected as research settings. Our main methods were: in-depth interviews with officials engaged in housing policy and management at the central, regional and local levels (n=24); notes from informal conversations, workshops and visits to state departments; and an analysis of background policy reports, journalism and academic literature related to the case study countries. On the basis of this material, we explore how management styles of housing data are observably impacted in our field settings by three key dynamics: marketization/decentralization; knowledge and expertise; and the evolution of data sharing infrastructures. We then proceed to outline a five-dimensional model of 'data cultures', comprising: 'relationships between data and decision-making'; 'relationships between the data of particular public organizations and civil society'; 'systematicity of data collection'; 'attitudes towards data sharing'; and 'specialization of data-related functions'. In conclusion, we outline some preliminary recommendations