The impact of uncertainty in satellite data on the assessment of flood inundation models

The performance of flood inundation models is often assessed using satellite observed data; however these data have inherent uncertainty. In this study we assess the impact of this uncertainty when calibrating a flood inundation model (LISFLOOD-FP) for a flood event in December 2006 on the River Dee, North Wales, UK. The flood extent is delineated from an ERS-2 SAR image of the event using an active contour model (snake), and water levels at the flood margin calculated through intersection of the shoreline vector with LiDAR topographic data. Gauged water levels are used to create a reference water surface slope for comparison with the satellite-derived water levels. Residuals between the satellite observed data points and those from the reference line are spatially clustered into groups of similar values. We show that model calibration achieved using pattern matching of observed and predicted flood extent is negatively influenced by this spatial dependency in the data. By contrast, model calibration using water elevations produces realistic calibrated optimum friction parameters even when spatial dependency is present. To test the impact of removing spatial dependency a new method of evaluating flood inundation model performance is developed by using multiple random subsamples of the water surface elevation data points. By testing for spatial dependency using Moran’s I, multiple subsamples of water elevations that have no significant spatial dependency are selected. The model is then calibrated against these data and the results averaged. This gives a near identical result to calibration using spatially dependent data, but has the advantage of being a statistically robust assessment of model performance in which we can have more confidence. Moreover, by using the variations found in the subsamples of the observed data it is possible to assess the effects of observational uncertainty on the assessment of flooding risk

An evidence-based approach to measuring affective domain development

Background: Educational taxonomies are utilised within nursing programmes to design curriculum, develop learning objectives, and measure attainments including the assessment of values, behaviours, and attitudes. Current measurement of the affective domain is limited, relying on quantitative tools, often immediately before and after learning activities. Purpose: This paper examines the reliability of a qualitative framework to assess the long-term impact of learning activities known to stimulate affective domain development. Method: Epstein's (1977) qualitative framework was applied to the self-reported responses of twelve international nurses (20–24 months post nurse registration) who had engaged in learning activities during their preregistration programme that were considered to be enrichment (international placement, interprofessional learning, simulation and blended learning). Results: Epstein's framework was used to measure the degree of affective domain development from the self reported responses of the students. The degree of modification in affective domain development was assessed as identification level (assuming a different attitude or behaviour) for four nurses and internalisation stage for eight nurses (embracing new values and attitudes). Conclusion: Epstein's framework is a reliable tool that can capture the short and long-term modification in affective domain development of nurses after they have experienced transformational learning activities. Key elements that move a nurse from identification to internalisation level are the motivating reason for undertaking the activity and reflection on the learning

Relative safety: risk and unprotected anal intercourse among gay men diagnosed with HIV

Duration: January 1998 - January 1999 This study investigated the experiences of gay men with diagnosed HIV in order to better understand the range of social, psychological and cultural meanings attached to HIV risk. We examined how men engaged in unprotected anal intercourse (UAI) and how they felt about it. We looked at the meanings they attached to UAI, the risks (if any) they perceived, and how engaging in UAI affected their lives. The study generated data from two sources. First, information on sexual risk behaviour was provided by the second annual Gay Men's Sex Survey in 1998. We compared the demographics and sexual behaviour of men diagnosed with HIV, those who had never tested and those who had tested negative in order to gain a comparative picture of sexual risk behaviour. This data demonstrated that, on a population level, substantial differences in sexual behaviour occurred between men who had never tested for HIV and those that had. Men who had never tested were substantially less likely to engage in sexual activities implicated in HIV exposure (UAI and sero-discordant UAI) compared to those who had tested. Among those who had tested, men with diagnosed HIV were no more likely to engage in UAI than those tested negative. However, among men that engaged in UAI, men who had tested positive did so substantially more often. The study also included 64 in-depth, semi-structured interviews with gay men who had diagnosed HIV. All had engaged in UAI in the previous year: some with partners who they knew were also HIV infected; others with partners whom they knew to be uninfected; and some with partners whose HIV status they did not know. Most interviewees had done UAI with a range of partners from all three categories. We found that UAI was an act that resists easy classification, imbued with multiple meanings, it's perceived safety and desirability dependent upon the circumstances in which it occurs and the partners involved. Moreover, the concepts of safety and risk that health promoters employ in relation to UAI were not necessarily shared by the positive men we interviewed. Important for our purposes was that gay men with diagnosed HIV engaging in UAI, felt they were risking something entirely different to their uninfected partners. For them, risk was experienced in a mediated and diffuse manner on three levels: risks to personal health, risks to psychological well-being and risks to social standing. The final report was called Relative safety: risk and unprotected anal intercourse among gay men diagnosed with HIV

Accuracy threshold for concatenated error detection in one dimension

Estimates of the quantum accuracy threshold often tacitly assume that it is possible to interact arbitrary pairs of qubits in a quantum computer with a failure rate that is independent of the distance between them. None of the many physical systems that are candidates for quantum computing possess this property. Here we study the performance of a concatenated error-detection code in a system that permits only nearest-neighbor interactions in one dimension. We make use of a new message-passing scheme that maximizes the number of errors that can be reliably corrected by the code. Our numerical results indicate that arbitrarily accurate universal quantum computation is possible if the probability of failure of each elementary physical operation is below approximately 10^{-5}. This threshold is three orders of magnitude lower than the highest known.Comment: 7 pages, 4 figures, now with error bar

An Auger electron spectroscopy study of surface-preparation contaminants

There are many cleaning techniques that are presently being employed for surface preparation of materials that are subsequently exposed to ultrahigh vacuum (UHV). Unfortunately, there are virtually no comparative measurements which establish the residual contaminant level of each method. In this report, eleven different cleaning methods, ranging from only detergent cleaning to electrochemical polishing, were applied to identical samples of 347 stainless steel. Two surface conditions, a standard machined surface and a mechanically polished surface, were studied. Auger electron spectroscopy (AES) within a UHV environment was then used to detect the types of contaminants and the magnitudes found on the sample surfaces. It was found that the electrochemical polishing gave the least contaminated surface of all metals studied and that mechanically polished surfaces were significantly cleaner than the as-machined surfaces for any given cleaning method. Furthermore, it was also found that the residual contaminations left by methanol, ethanol, isopropyl alcohol, acetone, and freon finishing rinses are almost the same

Herwig++ 2.0 Release Note

A new release of the Monte Carlo program Herwig++ (version 2.0) is now available. This is the first version of the program which can be used for hadron-hadron physics and includes the full simulation of both initial- and final-state QCD radiation.Comment: Source code and additional information available at http://hepforge.cedar.ac.uk/herwig

Residents' annoyance responses to aircraft noise events

In a study conducted in the vicinity of Salt Lake City International Airport, community residents reported their annoyance with individual aircraft flyovers during rating sessions conducted in their homes. Annoyance ratings were obtained at different times of the day. Aircraft noise levels were measured, and other characteristics of the aircraft were noted by trained observers. Metrics commonly used for assessing aircraft noise were compared, but none performed significantly better than A-weighted sound pressure level. A significant difference was found between the ratings of commercial jet aircraft and general aviation propeller aircraft, with the latter being judged less annoying. After the effects of noise level were accounted for, no significant differences were found between the ratings of landings and takeoffs. Aircraft noise annoyance reactions are stronger in lowered ambient noise conditions. This is consistent with the theory that reduced nighttime and evening ambient levels could create different reactions at different times of day. After controlling for ambient noise in a multiple regression analysis, no significant differences were found between the ratings of single events obtained during the three time periods: morning, afternoon, and evenings

Asymmetric quantum error correction via code conversion

In many physical systems it is expected that environmental decoherence will exhibit an asymmetry between dephasing and relaxation that may result in qubits experiencing discrete phase errors more frequently than discrete bit errors. In the presence of such an error asymmetry, an appropriately asymmetric quantum code - that is, a code that can correct more phase errors than bit errors - will be more efficient than a traditional, symmetric quantum code. Here we construct fault tolerant circuits to convert between an asymmetric subsystem code and a symmetric subsystem code. We show that, for a moderate error asymmetry, the failure rate of a logical circuit can be reduced by using a combined symmetric asymmetric system and that doing so does not preclude universality.Comment: 5 pages, 8 figures, presentation revised, figures and references adde