Code optimisation in a nested-sampling algorithm

The speed-up in program running time is investigated for problems of parameter estimation with Nested Sampling Monte Carlo methods. The example used in this study is to extract a polarization observable from event-by-event data from meson photoproduction reactions. Various implementations of the basic algorithm were compared, consisting of combinations of single threaded vs multi-threaded, and CPU vs GPU versions. These were implemented in OpenMP and OpenCL. For the application under study, and with the number of events as used in our work, we find that straightforward multi-threaded CPU OpenMP coding gives the best performance; for larger numbers of events, OpenCL on the CPU performs better. The study also shows that there is a “break-even” point of the number of events where the use of GPUs helps performance. GPUs are not found to be generally helpful for this problem, due to the data transfer times, which more than offset the improvement in computation time

Development of Bayesian analysis program for extraction of polarisation observables at CLAS

At the mass scale of a proton, the strong force is not well understood. Various quark models exist, but it is important to determine which quark model(s) are most accurate. Experimentally, finding resonances predicted by some models and not others would give valuable insight into this fundamental interaction. Several labs around the world use photoproduction experiments to find these missing resonances. The aim of this work is to develop a robust Bayesian data analysis program for extracting polarisation observables from pseudoscalar meson photoproduction experiments using CLAS at Jefferson Lab. This method, known as nested sampling, has been compared to traditional methods and has incorporated data parallelisation and GPU programming. It involves an event-by-event likelihood function, which has no associated loss of information from histogram binning, and results can be easily constrained to the physical region. One of the most important advantages of the nested sampling approach is that data from different experiments can be combined and analysed simultaneously. Results on both simulated and previously analysed experimental data for the K+Λ channel will be discussed

They are Small Worlds After All: Revised Properties of Kepler M Dwarf Stars and their Planets

We classified the reddest ($r-J>2.2$) stars observed by the NASA $Kepler$ mission into main sequence dwarf or evolved giant stars and determined the properties of 4216 M dwarfs based on a comparison of available photometry with that of nearby calibrator stars, as well as available proper motions and spectra. We revised the properties of candidate transiting planets using the stellar parameters, high-resolution imaging to identify companion stars, and, in the case of binaries, fitting light curves to identify the likely planet host. In 49 of 54 systems we validated the primary as the host star. We inferred the intrinsic distribution of M dwarf planets using the method of iterative Monte Carlo simulation. We compared several models of planet orbital geometry and clustering and found that one where planets are exponentially distributed and almost precisely coplanar best describes the distribution of multi-planet systems. We determined that $Kepler$ M dwarfs host an average of $2.2 \pm 0.3$ planets with radii of 1-4$R_{\oplus}$ and orbital periods of 1.5-180 d. The radius distribution peaks at $\sim 1.2R_{\oplus}$ and is essentially zero at $4R_{\oplus}$, although we identify three giant planet candidates other than the previously confirmed Kepler-45b. There is suggestive but not significant evidence that the radius distribution varies with orbital period. The distribution with logarithmic orbital period is flat except for a decline for orbits less than a few days. Twelve candidate planets, including two Jupiter-size objects, experience an irradiance below the threshold level for a runaway greenhouse on an Earth-like planet and are thus in a "habitable zone".Comment: MNRAS, in press. Tables 1, 3, and 4 are available in electronic form in the "anc" director

Dental Preparedness from Medical Department Viewpoint

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DNA-mediated gene transfer as an indicator of DNA damage and its repair by recipient cells

AbstractPreparations of plasmid containing the thymidine kinase gene (pHSV106) were treated with the alkylating agents methyl methanesulphonate or N-methyl-N-nitrosourea prior to transfection into thymidine kinase-deficient mouse L-cells using the DNA-calcium phosphate co-precipitation technique. Relative to transfection with unmodified plasmid, a reduced transformation efficiency was observed using alkylation-damaged plasmid, N-methyl-N-nitrosourea causing the greatest inhibition. Treatment of recipient cells with arabinosyl cytosine or dideoxythymidine during the expression period following transfection by the ‘damaged’ plasmid reduced transformation efficiency, suggesting that DNA repair 4–6 h post-transfection was required for gene expression

Inverse Simulation as a Tool for Fault Detection and Isolation in Planetary Rovers

With manned expeditions to planetary bodies beyond our own and the Moon currently intractable, the onus falls upon robotic systems to explore and analyse extraterrestrial environments such as Mars. These systems typically take the form of wheeled rovers, designed to navigate the difficult terrain of other worlds. Rovers have been used in this role since Lunokhod 1 landed on the Moon in 1970. While early rovers were remote controlled, communication latency with bodies beyond the Moon and the desire to improve mission effectiveness have resulted in increasing autonomy in planetary rovers. With an increase in autonomy, however, comes an increase in complexity. This can have a negative impact on the reliability of the rover system. With a fault-free system an unlikely prospect and human assistance millions of miles away, the rover must have a robust fault detection, isolation and recovery (FDIR) system. The need for comprehensive FDIR is demonstrated by the recent Chinese lunar rover, Yutu (or “Jade Rabbit”). Yutu was rendered immobile 42 days after landing and remained so for the duration of its operational life: 31 months. While its lifespan far exceeded its expected value, Yutu's inability to move severely impaired its ability to perform its mission. This clearly highlights the need for robust FDIR. A common approach to FDIR is through the generation and analysis of residuals. Output residuals may be obtained by comparing the outputs of the system with predictions of those outputs, obtained from a mathematical model of the system which is supplied with the system inputs. Output residuals allow simple detection and isolation of faults at the output of the system. Faults in earlier stages of the system, however, propagate through the system dynamics and can disperse amongst several of the outputs. This problem is exemplified by faults at the input, which can potentially excite every system state and thus manifest in every output residual. Methods exist for decoupling and analysing output residuals such that input faults may be isolated, however, these methods are complex and require comprehensive development and testing. A conceptually simpler approach is presented in this paper. Inverse simulation (InvSim) is a numerical method by which the inputs of a system are obtained for a desired output. It does so by using a Newton-Raphson algorithm to solve a non-linear model of the system for the input. When supplied with the outputs of a fault-afflicted system, InvSim produces the input required to drive a fault-free system to this output. The fault therefore manifests itself in this generated input signal. The InvSim-generated input may then be compared to the true system input to generate input residuals. Just as a fault at an output manifests itself in the residual for that output alone, a fault at an input similarly manifests itself only in the residual for that input. InvSim may also be used to generate residuals at other locations in the system, by considering distinct subsystems with their own inputs and outputs. This ability is tested comprehensively in this paper. Faults are applied to a simulated rover at a variety of locations within the system structure and residuals generated using both InvSim and conventional forward simulation. Residuals generated using InvSim are shown to facilitate detection and isolation of faults in several locations using simple analyses. By contrast, forward simulation requires the use of complex analytical methods such as structured residuals or adaptive thresholds

Historia prawa historii prawa w Anglii i Walii

This article explores the development of the study of legal history as a subject in the law schools of England and Wales. It outlines changes in university education more generally, and in legal scholarship in particular and how those changes impact the particular subject under study. Drawing on empirical studies and personal reflections relating to past experience it concludes by speculating on potential different outcomes, both positive and negative, which may emerge when the universities of England and Wales emerge from the uncertainty of the COVID-19 pandemic, during which the piece was written.W artykule przedstawiany jest rozwój nauki historii prawa jako przedmiotu nauczanego na angielskich i walijskich wydziałach prawa. Wskazuje się w nim ogólnie na przemiany edukacji uniwersyteckiej, a w szczególności na zmiany zachodzące w zakresie nauki prawa, a także na to, jak te zmiany wpływają na poszczególne przedmioty studiów. Opierając się na badaniach empirycznych oraz osobistych przemyśleniach związanych z własnymi doświadczeniami, artykuł kończy się przedstawieniem przypuszczeń dotyczących możliwych konsekwencji, tak pozytywnych jak i negatywnych, które mogą ujawnić się, gdy uniwersytety w Anglii i Walii wydobędą się z niepewności okresu pandemii COVID-19, w trakcie której artykuł został napisany

The Role of Negative Outcome Expectations in Career Exploration and Decision-Making

This study had two objectives. First, responding to calls for improved measurement of outcome expectations in the domain of career exploration and decision-making (Fouad & Guillen, 2006), a measure of outcome expectations was developed that incorporates Bandura’s (1997) conceptualization of both positive and negative outcomes, as well as classes of physical, social, and self-evaluative effects. Second, the replicability of the scale’s factor structure and evidence of its validity were examined. Social cognitive career theory (SCCT; Lent & Brown, 2013) was used to explore the theoretical relationships between positive and negative outcome expectations, and other domain-specific variables, including (a) self-efficacy, (b) learning experiences, (c) social support, and (d) career exploration goals. In addition to exploring direct relationships proposed by the SCCT career self-management model, negative outcome expectations were also explored for their theorized moderation of the relations of self-efficacy to goals and positive outcome expectations to goals. Data were collected via an online survey in two separate samples of college students who were in the process of making initial career decisions. Exploratory and confirmatory factor analyses of the new outcome expectations measure indicated a 22-item, four-factor scale with distinct positive and negative factors. Subsequent measure and hypothesis testing analyses offered support for the convergent and discriminant validity of the scale in the samples, found that exploratory intentions was linked with both self-efficacy and positive outcome expectations, and indicated a potential moderator role for negative outcome expectations in these relationships

The Angular Diameter and Fundamental Parameters of Sirius A

The Sydney University Stellar Interferometer (SUSI) has been used to make a new determination of the angular diameter of Sirius A. The observations were made at an effective wavelength of 694.1 nm and the new value for the limb-darkened angular diameter is 6.048 +/- 0.040mas (+/-0.66%). This new result is compared with previous measurements and is found to be in excellent agreement with a conventionally calibrated measurement made with the European Southern Observatory's Very Large Telescope Interferometer (VLTI) at 2.176 microns (but not with a second globally calibrated VLTI measurement). A weighted mean of the SUSI and first VLTI results gives the limb-darkened angular diameter of Sirius A as 6.041 +/- 0.017mas (+/-0.28%). Combination with the Hipparcos parallax gives the radius equal to 1.713 +/- 0.009R_sun. The bolometric flux has been determined from published photometry and spectrophotometry and, combined with the angular diameter, yields the emergent flux at the stellar surface equal to (5.32+/- 0.14)x10^8 Wm^-2 and the effective temperature equal to 9845 +/- 64 K. The luminosity is 24.7 +/- 0.7 L_sun.Comment: Accepted for publication in PAS