1,089 research outputs found

    Unmanned and uncontrolled: The commingling theory and the legality of unmanned aircraft system operations

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    In 2002 Australia became the first nation to promulgate certification standards for the commercial use of drones or unmanned aircraft systems (UAS). Since that time the Australian Civil Aviation Safety Authority (CASA) has played a key role both domestically and internationally through the International Civil Aviation Organization (ICAO) in assisting to develop technical guidance materials that will enable contracting states to develop UAS regulations. An arduous component of this task is the fact that all existing aircraft are capable of being unmanned. Moreover, given the unbounded nature of aircraft operations, UAS regulations necessarily require international harmonisation. But the objective of developing universal UAS standards is still far from being finalised while the accelerating pace of UAS technological development continues to challenge traditional regulatory regimes and legal systems throughout the world. This paper considers the broader legal issues associated with civilian UAS operations and their integration into unsegregated civilian airspace. The Australian UAS regulatory experience is examined with some unique constitutional limitations identified in relation to the application of the so-called ‘commingling theory’. It is contended that such limitations may render void existing UAS regulation in certain situations – many of which are related to the operation of small UAS and may have significant privacy implications. In particular this paper finds that the regulations purporting to control the operation of systems that are not capable of commingling with aircraft operating within navigable airspace are ultra vires and hence of no legal effect. In concluding this paper strongly asserts that if the commercial benefits attendant to UAS operations is to be fully realised then their risks to society must be controlled through domestic legislation that is harmonised and consistent with internationally agreed guidelines

    Transition State Theory For Laser-Driven Reactions

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    Recent developments in transition state theory brought about by dynamical systems theory are extended to time-dependent systems such as laser-driven reactions. Using time-dependent normal form theory, the authors construct a reaction coordinate with regular dynamics inside the transition region. The conservation of the associated action enables one to extract time-dependent invariant manifolds that act as separatrices between reactive and nonreactive trajectories and thus make it possible to predict the ultimate fate of a trajectory. They illustrate the power of our approach on a driven Henon-Heiles system, which serves as a simple example of a reactive system with several open channels. The present generalization of transition state theory to driven systems will allow one to study processes such as the control of chemical reactions through laser pulses

    Transition state theory for laser-driven reactions

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    Recent developments in Transition State Theory brought about by dynamical systems theory are extended to time-dependent systems such as laser-driven reactions. Using time-dependent normal form theory, we construct a reaction coordinate with regular dynamics inside the transition region. The conservation of the associated action enables one to extract time-dependent invariant manifolds that act as separatrices between reactive and non-reactive trajectories and thus make it possible to predict the ultimate fate of a trajectory. We illustrate the power of our approach on a driven H´enon-Heiles system, which serves as a simple example of a reactive system with several open channels. The present generalization of Transition State Theory to driven systems will allow one to study processes such as the control of chemical reactions through laser pulses

    Gastric emptying of low- and high-caloric liquid meals measured using ultrasonography in healthy volunteers

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    Purpose Delayed gastric emptying is present in patients with functional dyspepsia (FD), diabetes mellitus, and neurological diseases. Diet may affect gastric emptying symptoms in patients with FD. We sought to determine the extent to which gastric emptying and symptoms of dyspepsia are influenced by caloric content in healthy subjects using ultrasonography. Materials and Methods 32 healthy volunteers were given 2 meals with different caloric content in random order. Gastric emptying was determined using ultrasonography to measure antral area when fasting, and postprandially at intervals of 0, 10, 20, and 30 min. Dyspeptic symptoms including discomfort, nausea, and fullness were graded. Results The antral area following a high-caloric meal compared to a low-caloric meal was significantly increased at 0, 10, 20, and 30 min (P=0.0203,<0.0001<0.0001,<0.0001, respectively), as was the median fullness (P<0.0048, 0.0001, 0.0009, 0.0001, respectively) measured at the same time points. There was a weak correlation (r2=0.1, P<0.0001) between the antral area and subjective fullness. No differences between gastric emptying in males and females were found. Conclusion The caloric content of a meal influences gastric emptying. Using ultrasonography to measure the antral area helps us to assess gastric emptying and therefore to assess patients with functional dyspepsia.publishedVersio

    Theoretical and Phenomenological Constraints on Form Factors for Radiative and Semi-Leptonic B-Meson Decays

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    We study transition form factors for radiative and rare semi-leptonic B-meson decays into light pseudoscalar or vector mesons, combining theoretical constraints and phenomenological information from Lattice QCD, light-cone sum rules, and dispersive bounds. We pay particular attention to form factor parameterisations which are based on the so-called series expansion, and study the related systematic uncertainties on a quantitative level. In this context, we also provide the NLO corrections to the correlation function between two flavour-changing tensor currents, which enters the unitarity constraints for the coefficients in the series expansion.Comment: 52 pages; v2: normalization error in (29ff.) corrected, conclusion about relevance of unitarity bounds modified; form factor fits unaffected; references added; v3: discussion on truncation of series expansion added, matches version to be published in JHEP; v4: corrected typos in Tables 5 and

    Precision flavour physics with BKννˉB\to K\nu\bar\nu and BKl+lB\to Kl^+l^-

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    We discuss how the combined analysis of BKννˉB\to K\nu\bar\nu and BKl+lB\to Kl^+l^- can provide us with new physics tests practically free of form factor uncertainties. Residual theory errors are at the level of several percent. This study underlines the excellent motivation for measuring these modes at a Super Flavour Factory, or, in the case of BKl+lB\to Kl^+l^-, also at a hadron collider.Comment: 6 pages, 1 figure, invited talk at the 3rd Workshop on Heavy Flavour Physics, Capri, Italy, 5-7 July 201

    Size Distributions of Arctic Waterbodies Reveal Consistent Relations in Their Statistical Moments in Space and Time

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    Arctic lowlands are characterized by large numbers of small waterbodies, which are known to affect surface energy budgets and the global carbon cycle. Statistical analysis of their size distributions has been hindered by the shortage of observations at sufficiently high spatial resolutions. This situation has now changed with the high-resolution (&lt;5 m) circum-Arctic Permafrost Region Pond and Lake (PeRL) database recently becoming available. We have used this database to make the first consistent, high-resolution estimation of Arctic waterbody size distributions, with surface areas ranging from 0.0001 km2 (100 m2) to 1 km2. We found that the size distributions varied greatly across the thirty study regions investigated and that there was no single universal size distribution function (including power-law distribution functions) appropriate across all of the study regions. We did, however, find close relationships between the statistical moments (mean, variance, and skewness) of the waterbody size distributions from different study regions. Specifically, we found that the spatial variance increased linearly with mean waterbody size (R2 = 0.97, p &lt; 2.2e-16) and that the skewness decreased approximately hyperbolically. We have demonstrated that these relationships (1) hold across the 30 Arctic study regions covering a variety of (bio)climatic and permafrost zones, (2) hold over time in two of these study regions for which multi-decadal satellite imagery is available, and (3) can be reproduced by simulating rising water levels in a high-resolution digital elevation model. The consistent spatial and temporal relationships between the statistical moments of the waterbody size distributions underscore the dominance of topographic controls in lowland permafrost areas. These results provide motivation for further analyses of the factors involved in waterbody development and spatial distribution and for investigations into the possibility of using statistical moments to predict future hydrologic dynamics in the Arctic

    Repetitive Peripheral Magnetic Stimulation (rPMS) in Subjects With Migraine-Setup Presentation and Effects on Skeletal Musculature

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    Purpose: Repetitive peripheral magnetic stimulation (rPMS) has been successfully applied recently in migraineurs to alleviate migraine symptoms. Symptom relief has been achieved by stimulating myofascial trigger points (mTrPs) of the trapezius muscles, which are considered part of the trigemino-cervical complex (TCC). However, effects on musculature have not been assessed in detail, and the specificity of effects to muscles considered part of the TCC yet has to be elucidated. Against this background, this study presents the setup of rPMS in migraine and evaluates effects on skeletal musculature. Materials and Methods: Thirty-seven adults (mean age: 25.0 ± 4.1 years, 36 females) suffering from migraine and presenting mTrPs according to physical examination underwent rPMS either to mTrPs in the trapezius muscles (considered part of the TCC; n = 19) or deltoid muscles (considered not part of the TCC; n = 18) during six sessions over the course of 2 weeks. Standardized questionnaires were filled in to assess any adverse events and experience with rPMS as well as satisfaction and benefits from stimulation. Algometry was performed to evaluate changes in pressure pain thresholds (PPTs). Results: All stimulation sessions were successfully performed without adverse events, with 84.2% of subjects of the trapezius group and 94.4% of subjects of the deltoid group describing rPMS as comfortable (p = 0.736). Muscular pain or tension improved in 73.7% of subjects of the trapezius group and in 61.1% of subjects of the deltoid group (p = 0.077). PPTs of the trapezius muscles clearly increased from the first to the last stimulation sessions—regardless of the stimulated muscle (rPMS to the trapezius or deltoid muscles). However, depending on the examined muscles the increase of PPTs differed significantly (subjects with stimulation of trapezius muscles: p = 0.021; subjects with stimulation of deltoid muscles: p = 0.080). Conclusion: rPMS is a comfortable method in migraineurs that can improve local muscular pain or tension. Furthermore, it is able to increase directly and indirectly the PPTs of the trapezius muscles (considered part of the TCC) when applied over mTrPs, supporting the role of the TCC in migraineurs

    PeRL:A circum-Arctic Permafrost Region Pond and Lake database

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    Ponds and lakes are abundant in Arctic permafrost lowlands. They play an important role in Arctic wetland ecosystems by regulating carbon, water, and energy fluxes and providing freshwater habitats. However, ponds, i.e., waterbodies with surface areas smaller than 1. 0 × 104ĝ€m2, have not been inventoried on global and regional scales. The Permafrost Region Pond and Lake (PeRL) database presents the results of a circum-Arctic effort to map ponds and lakes from modern (2002-2013) high-resolution aerial and satellite imagery with a resolution of 5ĝ€m or better. The database also includes historical imagery from 1948 to 1965 with a resolution of 6ĝ€m or better. PeRL includes 69 maps covering a wide range of environmental conditions from tundra to boreal regions and from continuous to discontinuous permafrost zones. Waterbody maps are linked to regional permafrost landscape maps which provide information on permafrost extent, ground ice volume, geology, and lithology. This paper describes waterbody classification and accuracy, and presents statistics of waterbody distribution for each site. Maps of permafrost landscapes in Alaska, Canada, and Russia are used to extrapolate waterbody statistics from the site level to regional landscape units. PeRL presents pond and lake estimates for a total area of 1. 4 × 106ĝ€km2 across the Arctic, about 17ĝ€% of the Arctic lowland ( &lt; ĝ€300ĝ€mĝ€a.s.l.) land surface area. PeRL waterbodies with sizes of 1. 0 × 106ĝ€m2 down to 1. 0 × 102ĝ€m2 contributed up to 21ĝ€% to the total water fraction. Waterbody density ranged from 1. 0 × 10 to 9. 4 × 101ĝ€kmĝ'2. Ponds are the dominant waterbody type by number in all landscapes representing 45-99ĝ€% of the total waterbody number. The implementation of PeRL size distributions in land surface models will greatly improve the investigation and projection of surface inundation and carbon fluxes in permafrost lowlands. Waterbody maps, study area boundaries, and maps of regional permafrost landscapes including detailed metadata are available at https://doi.pangaea.de/10.1594/PANGAEA.868349
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