Instabilities and turbulence in highly ionized plasmas in a magnetic field Semiannual status report, 1 Sep. 1970 - 28 Feb. 1971

Instabilities and turbulence in highly ionized plasmas in magnetic field related to problems of thrustors for manned space flight and plasma generated energ

The Birds of the Highlands of South-West Saudi Arabia and adjacent parts of the Tihama: July 2010

The objective of the survey was to compare habitats and bird life in the Asir region, particularly Jebal Souda and the Raydah escarpment protected area of the Saudi Wildlife Commission, and adjacent regions of the tihama, with those observed in July 1987 (Jennings, et al., 1988). The two surveys were approximately the same length and equal amounts of time were spent in the highlands and on the tihama. A number of walked censuses were carried out during 2010 on Jebal Souda, using the same methodology as walked censuses in 1987, and the results are compared. Broadly speaking the comparison of censuses revealed that in 2010 there were less birds and reduced diversity on the Jebal Souda plateau, compared to 1987. However in the Raydah reserve the estimates of breeding bird populations compiled in the mid 1990s was little changed as far as could be assessed in 2010. The highland region of south-west Saudi Arabia, especially Jebal Souda, has been much developed since the 1987 survey and is now an important internal recreation and resort area. This has lead to a reduction in the region’s importance for terraced agriculture. These changes may be a contributing factor to changes in bird numbers on the plateau. Subsidiary tasks that arose during the 2010 survey were to help locate satellite tagged Bald Ibises Geronticus eremita from Syria which were transiting Saudi Arabia at the time. Secondly to search for the Asir subspecies of the Eurasian Magpie Pica pica asirensis, which is endemic to the south-west Saudi Arabia highlands, and is reported to be in decline. A separate team searching for the Bald Ibis located some individuals and one was found dead. Few Magpies were located and it seems clear that this very scarce bird has declined further in numbers in recent years. A number of interesting records of birds were obtained, especially on the tihama, where two new birds for Saudi Arabia were observed, Black-headed Heron Ardea melanocephala and Painted Snipe Rostratula benghalensis and one species, Glossy Ibis Plegadis falcinellus was found breeding for the first time in the Arabian Peninsula. Some recommendations for the protection and management of the Raydah reserve are presented. A systematic list of all birds seen is provided

Effects of canyon topography on strong ground motion

The two-dimensional scattering and diffraction of SH waves of arbitrary angle of incidence from irregular, canyon-shaped topography is formulated in terms of an integral equation. Taking advantage of the simple boundary conditions of SH-wave problems, the method of images is applied to reduce the integral equation to one with a finite integral, which can readily be solved numerically by available methods. The method is first applied to the analytically solved case of a cylindrical canyon to verify its accuracy, and then to two idealized cross sections based upon Pacoima Canyon to investigate the effects of topography in a more realistic case. The results of the harmonic analysis include wave amplification patterns and transfer functions for different wavelengths and for different angles of incidence. The study also includes analysis of transient motions. With the N76°W component of the Pacoima Dam accelerogram specified to occur at one point in the cross section, the effects of different angles of incidence upon the required input motion and upon the motion at several other points in the cross section were examined by calculating accelerograms and response spectra. The effects of canyon-shaped topography are seen most prominently in the amplification patterns and transfer functions for harmonic response, wherein shielding and focusing can cause variations up to a factor of six for wavelengths comparable to, or shorter than, the canyon width. In the case of transient motions, the accelerograms at different points show significant differences, but not as large as seen in the harmonic analysis. The response spectra show the smallest differences; significant effects are confined to the higher frequencies

Online mechanism design for electric vehicle charging

The rapid increase in the popularity of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) is expected to place a considerable strain on the existing electricity grids, due to the high charging rates these vehicles require. In many places, the limited capacity of the local electricity distribution network will be exceeded if many such vehicles are plugged in and left to charge their batteries simultaneously. Thus, it will become increasingly important to schedule the charging of these vehicles, taking into account the vehicle owners’ preferences, and the local constraints on the network. In this paper, we address this setting using online mechanism design and develop a mechanism that incentivises agents (representing vehicle owners) to truthfully reveal their preferences, as well as when the vehicle is available for charging. Existing related online mechanisms assume that agent preferences can be described by a single parameter. However, this is not appropriate for our setting since agents are interested in acquiring multiple units of electricity and can have different preferences for these units, depending on factors such as their expected travel distance. To this end, we extend the state of the art in online mechanism design to multi-valued domains, where agents have non-increasing marginal valuations for each subsequent unit of electricity. Interestingly, we show that, in these domains, the mechanism occasionally requires leaving electricity unallocated to ensure truthfulness. We formally prove that the proposed mechanism is dominant-strategy incentive compatible, and furthermore, we empirically evaluate our mechanism using data from a real-world trial of electric vehicles in the UK. We show that our approach outperforms any fixed price mechanism in terms of allocation efficiency, while performing only slightly worse than a standard scheduling heuristic, which assumes non-strategic agents

Cooperating Agents for 3D Scientific Data Interpretation

Many organizations collect vast quantities of three-dimensional (3-D) scientific data in volumetric form for a range of purposes, including resource exploration, market forecasting, and process modelling. Traditionally, these data have been interpreted by human experts with only minimal software assistance. However, such manual interpretation is a painstakingly slow and tedious process. Moreover, since interpretation involves subjective judgements and each interpreter has different scientific knowledge and experience, formulation of an effective interpretation often requires the cooperation of numerous such experts. Hence, there is a pressing need for a software system in which individual interpretations can be generated automatically and then refined through the use of cooperative reasoning and information sharing. To this end, a prototype system, SurfaceMapper, has been developed in which a community of cooperating software agents automatically locate and display interpretations in a volume of 3-D scientific data. The challenges and experiences in designing and building such a system are discussed. Particular emphasis is given to the agents' interactions and an empirical evaluation of the effectiveness of different cooperation strategies is presented

Aerosol light absorption in the North Atlantic: trends and seasonal characteristics during the period 1989 to 2003

Aerosol light attenuation on quartz fibre filters has been measured since February 1989 at the Mace Head Atmospheric Research station near Carna, Co. Galway, Ireland, using an Aethalometer. <P style='line-height: 20px;'> The frequency of occurrence of the hourly averaged aerosol absorption data is found to be bimodally distributed. The two modes result from clean marine air and anthropogenically polluted continental air both being advected to the station dependent on the prevailing wind direction. The hourly averages of the marine portion of the aerosol light absorption are found to follow closely a lognormal distribution with a geometric mean of 0.310&nbsp;Mm^-1. The&nbsp;hourly averages of continental sector aerosol absorption are neither normally nor lognormally distributed and have an arithmetic mean of 6.36&nbsp;Mm^-1, indicating the presence of anthropogenic sources for BC east of the Mace Head station. <P style='line-height: 20px;'> The time series of the monthly averaged attenuation coefficient &sigma;_att of both marine and continental sector aerosol shows an increase from 1989 to 1997 and a levelling off thereafter. <P style='line-height: 20px;'> The monthly maximum of marine sector &sigma;_att is found in May. Trend and seasonal characteristics of the clean marine aerosol attenuation coefficients observed at Mace Head appear to be driven by meteorological factors, as indicated by rainfall data and by trends in&nbsp;the North Atlantic Oscillation (NAO) indices. The observed increasing trends of the continental sector &sigma;_att from 1989 up to 1997 are possibly related to changes in BC emissions over Ireland, calculated from UNSTAT (2002) fuel consumption data

Nucleon-nucleus optical potential in the particle-hole approach

Feshbach's projection formalism in the particle-hole model space leads to a microscopic description of scattering in terms of the many-body self-energy. To investigate the feasibility of this approach, an optical potential for O-16 is constructed starting from two previous calculations of the self-energy for this nucleus. The results reproduce the background phase shifts for positive parity waves and the resonances beyond the mean field. The latter can be computed microscopically for energies of astrophysical interest using Green's function theory.Comment: 8 pages, 6 figures. Submitted to Phys. Rev.

Percutaneous coronary intervention in the elderly: changes in case-mix and periprocedural outcomes in 31758 patients treated between 2000 and 2007

&lt;p&gt;Background: The elderly account for an increasing proportion of the population and have a high prevalence of coronary heart disease. Percutaneous coronary intervention (PCI) is the most common method of revascularization in the elderly. We examined whether the risk of periprocedural complications after PCI was higher among elderly (age ≥75 years) patients and whether it has changed over time.&lt;/p&gt; &lt;p&gt;Methods and Results: The Scottish Coronary Revascularization Register was used to undertake a retrospective cohort study on all 31 758 patients undergoing nonemergency PCI in Scotland between April 2000 and March 2007, inclusive. There was an increase in the number and percentage of PCIs undertaken in elderly patients, from 196 (8.7%) in 2000 to 752 (13.9%) in 2007. Compared with younger patients, the elderly were more likely to have multivessel disease, multiple comorbidity, and a history of myocardial infarction or coronary artery bypass grafting (χ2 tests, all P&#60;0.001). The elderly had a higher risk of major adverse cardiovascular events within 30 days of PCI (4.5% versus 2.7%, χ2 test P&#60;0.001). Over the 7 years, there was a significant increase in the proportion of elderly patients who had multiple comorbidity (χ2 test for trend, P&#60;0.001). Despite this, the underlying risk of complications did not change significantly over time either among the elderly (χ2 test for trend, P=0.142) or overall (χ2 test for trend, P=0.083).&lt;/p&gt; &lt;p&gt;Conclusions: Elderly patients have a higher risk of periprocedural complications and account for an increasing proportion of PCIs. Despite this, the risk of complications after PCI has not increased over time.&lt;/p&gt

Deep Optical Counterpart Searches of Gamma-Ray Burst Localizations

We report the results of a 5 year CCD imaging program of small gamma-ray burst (GRB) error boxes from the First Interplanetary Network and an optical transient field. The fields include GBS 0010 - 16, GBS 0552-08, GBS 1028 + 46, GBS 1205 + 23, GBS 1412 + 79, OTS 1809 + 31, GBS 2006 - 22, and GBS 2252 - 03. A total of 274 hours of open shutter time was used to obtain multiple UBVI-filtered frames covering an area approximately twice that of the 99% confidence localizations. For 2070 objects in these fileds above the survey detection limit of V ~ 22, 79,000 calibrated photometric measurements were made. The objectives of the survey were to search for objects of unusual colours, variability, or proper motions. The final cesus of objects in these fields is consistent with the expected numbers of normal stars, galaxies, and proper motion objects based on statistics on large-scale surveys. While no obvous GRB optical counterparts were found, several potentially interesting objects were discovered, along with marginal evidence for a QSO excess at the rate one per high Galactic latitude localization. The results and implications are discussed in detial along with suggestions for future work

The identification and psychological treatment of panic disorder in adolescents: a survey of CAMHS clinicians

Background Panic disorder is experienced by around 1% of adolescents, and has a significant impact on social and academic functioning. Preliminary evidence supports the effectiveness of panic disorder specific treatment in adolescents with panic disorder, however panic disorder may be overlooked in adolescents due to overlapping symptoms with other anxiety disorders and other difficulties being more noticeable to others. The aim of this study was to establish what training National Health Service (NHS) Child and Adolescent Mental Health Services (CAMHS) clinicians have received in psychological therapies and panic disorder and how they identify and treat panic disorder in adolescents. Method CAMHS clinicians from a range of professions (n = 427), who were delivering psychological treatments to children and adolescents with anxiety disorders, participated. They completed a cross-sectional, online survey, including a vignette describing an adolescent with panic disorder, and were asked to identify the main diagnosis or presenting problem. Results Less than half the clinicians (48.6%) identified panic disorder or panic symptoms as the main presenting problem from the vignette. The majority of clinicians suggested CBT would be their treatment approach. However, few identified an evidence-based treatment protocol for working with young people with panic disorder. Almost half the sample had received no training in cognitive behaviour therapy (CBT) and around a fifth had received no training in delivering psychological treatments. Conclusions Only half of CAMHS clinicians identified panic disorder from a vignette and although CBT treatments are widely offered, only a minority of adolescents with panic disorder are receiving treatments developed for, and evaluated with young people with panic disorder. There is a vital need for clinician training, the use of tools that aid identification and the implementation of evidence-based treatments within CAMHS