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We investigate the effects of magnetisation on the two-fluid plasma Richtmyer–Meshkov instability of a single-mode thermal interface using a computational approach. The initial magnetic field is normal to the mean interface location. Results are presented for a magnetic interaction parameter of 0.1 and plasma skin depths ranging from 0.1 to 10 perturbation wavelengths. These are compared to initially unmagnetised and neutral fluid cases. The electron flow is found to be constrained to lie along the magnetic field lines resulting in significant longitudinal flow features that interact strongly with the ion fluid. The presence of an initial magnetic field is shown to suppress the growth of the initial interface perturbation with effectiveness determined by plasma length scale. Suppression of the instability is attributed to the magnetic field's contribution to the Lorentz force. This acts to rotate the vorticity vector in each fluid about the local magnetic-field vector leading to cyclic inversion and transport of the out-of-plane vorticity that drives perturbation growth. The transport of vorticity along field lines increases with decreasing plasma length scales and the wave packets responsible for vorticity transport begin to coalesce. In general, the two-fluid plasma Richtmyer–Meshkov instability is found to be suppressed through the action of the imposed magnetic field with increasing effectiveness as plasma length scale is decreased. For the conditions investigated, a critical skin depth for instability suppression is estimated.
The transition from adolescent to adult mental health services (AMHS) is associated with disengagement, poor continuity of care and patient dissatisfaction. The aim of this retrospective and descriptive study was to describe the ‘care pathways’ in an independent mental health service when adolescents reach age 18 and to investigate the level of engagement of those who transitioned to independent AMHS.
This is a retrospective, naturalistic and descriptive study in design. All patients discharged from the St Patrick’s Adolescent Mental Health Service aged 17 years and 6 months and older, during a 3-year period between January 2014 and December 2016, were included. Electronic records were used to collect socio-demographic and clinical details and to determine engagement rates in adolescents who transferred to independent adult services.
A total of 180 patients aged over 17 years and 6 months were discharged from the adolescent service. Of these, 45.6% were discharged to their GP, 28.9% to public mental health services and 25.6% to independent mental health services. The majority who transitioned to independent AMHS went to a Young Adult Service, which had high engagement rates at 3 and 12 months post-transition.
In this independent mental health service, less than half of adolescents who reach the transition age are referred onto AMHS. Engagement rates were found to be high among those referred on to a specialised young adult service.
We computationally investigate the Richtmyer–Meshkov instability of a density interface with a single-mode perturbation in a two-fluid, ion–electron plasma with no initial magnetic field. Self-generated magnetic fields arise subsequently. We study the case where the density jump across the initial interface is due to a thermal discontinuity, and select plasma parameters for which two-fluid plasma effects are expected to be significant in order to elucidate how they alter the instability. The instability is driven via a Riemann problem generated precursor electron shock that impacts the density interface ahead of the ion shock. The resultant charge separation and motion generates electromagnetic fields that cause the electron shock to degenerate and periodically accelerate the electron and ion interfaces, driving Rayleigh–Taylor instability. This generates small-scale structures and substantially increases interfacial growth over the hydrodynamic case.
PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. The atmospheric conditions at Dome C deliver a high sensitivity, high photometric precision, wide-field, high spatial resolution, and high-cadence imaging capability to the PILOT telescope. These capabilities enable a unique scientific potential for PILOT, which is addressed in this series of papers. The current paper presents a series of projects dealing with the nearby Universe that have been identified as key science drivers for the PILOT facility. Several projects are proposed that examine stellar populations in nearby galaxies and stellar clusters in order to gain insight into the formation and evolution processes of galaxies and stars. A series of projects will investigate the molecular phase of the Galaxy and explore the ecology of star formation, and investigate the formation processes of stellar and planetary systems. Three projects in the field of exoplanet science are proposed: a search for free-floating low-mass planets and dwarfs, a program of follow-up observations of gravitational microlensing events, and a study of infrared light-curves for previously discovered exoplanets. Three projects are also proposed in the field of planetary and space science: optical and near-infrared studies aimed at characterising planetary atmospheres, a study of coronal mass ejections from the Sun, and a monitoring program searching for small-scale Low Earth Orbit satellite debris items.
PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. Conditions at Dome C are known to be exceptional for astronomy. The seeing (above ∼30 m height), coherence time, and isoplanatic angle are all twice as good as at typical mid-latitude sites, while the water-vapour column, and the atmosphere and telescope thermal emission are all an order of magnitude better. These conditions enable a unique scientific capability for PILOT, which is addressed in this series of papers. The current paper presents an overview of the optical and instrumentation suite for PILOT and its expected performance, a summary of the key science goals and observational approach for the facility, a discussion of the synergies between the science goals for PILOT and other telescopes, and a discussion of the future of Antarctic astronomy. Paper II and Paper III present details of the science projects divided, respectively, between the distant Universe (i.e. studies of first light, and the assembly and evolution of structure) and the nearby Universe (i.e. studies of Local Group galaxies, the Milky Way, and the Solar System).
The cold, dry, and stable air above the summits of the Antarctic plateau provides the best ground-based observing conditions from optical to sub-millimetre wavelengths to be found on the Earth. Pathfinder for an International Large Optical Telescope (PILOT) is a proposed 2 m telescope, to be built at Dome C in Antarctica, able to exploit these conditions for conducting astronomy at optical and infrared wavelengths. While PILOT is intended as a pathfinder towards the construction of future grand-design facilities, it will also be able to undertake a range of fundamental science investigations in its own right. This paper provides the performance specifications for PILOT, including its instrumentation. It then describes the kinds of projects that it could best conduct. These range from planetary science to the search for other solar systems, from star formation within the Galaxy to the star formation history of the Universe, and from gravitational lensing caused by exo-planets to that produced by the cosmic web of dark matter. PILOT would be particularly powerful for wide-field imaging at infrared wavelengths, achieving near diffraction-limited performance with simple tip–tilt wavefront correction. PILOT would also be capable of near diffraction-limited performance in the optical wavebands, as well be able to open new wavebands for regular ground-based observation, in the mid-IR from 17 to 40 μm and in the sub-millimetre at 200 μm.
The Burst Observer and Optical Transient Exploring System (BOOTES), is a global robotic
observatory network, which started in 1998 with Spanish leadership devoted to study
optical emissions from gamma ray bursts (GRBs) that occur in the Universe. We present shot
history and current status of BOOTES network. The Network philosophy, science and some
details of 117 GRBs followed-up are discussed.
Theoretical studies suggest that C/O and Mg/Si are the most important elemental ratios in determining the mineralogy of terrestrial planets. The C/O ratio controls the distribution of Si among carbide and oxide species, while Mg/Si gives information about the silicate mineralogy. We find mineralogical ratios quite different from those of the Sun, showing that there is a wide variety of planetary systems which are not similar to Solar System. Many of planetary host stars present a Mg/Si value lower than 1, so their planets will have a high Si content to form species such as MgSiO3. This type of composition can have important implications for planetary processes like plate tectonics, atmospheric composition or volcanism. Moreover, the information given by these ratios can guide us in the search of stars more probable to form terrestrial planets.
Although cognitive deficits in bipolar disorder have been associated with diminished functional outcome, this relationship has been studied primarily through cross-sectional designs, and has not been studied in patients early in the course of illness. The purpose of this study was to evaluate the impact of cognitive functioning on longitudinal 6-month functional and clinical outcome in recently diagnosed clinically stable patients with bipolar disorder.
A total of 53 recently diagnosed patients with DSM-IV bipolar disorder type I were assessed within 3 months of their first manic episode using a neuropsychological battery measuring verbal/pre-morbid intellectual functioning, learning/memory, spatial/non-verbal reasoning, attention/processing speed and executive function. Functional outcome was assessed at baseline and 6 months using the Multidimensional Scale of Independent Functioning (MSIF) and DSM-IV Global Assessment of Functioning Scale (GAF). Clinical outcome was assessed with symptom ratings and by monitoring onset of new mood episodes.
Memory, particularly verbal learning/memory, was robustly associated with 6-month functional outcome on the MSIF, even after partialling out the influence of mood symptoms and substance abuse co-morbidity. Depression ratings at 6 months, but not cognitive variables, were associated with 6-month GAF scores. Cognitive functioning was not associated with 6-month clinical outcome.
Memory was associated with 6-month longitudinal functional but not clinical outcome in recently diagnosed patients with bipolar disorder. These data further support the distinction between clinical and functional outcome, and emphasize the need for identification of, and development of treatments for, cognitive impairments early in the course of bipolar disorder.
Corrugated structures offer a potential solution for morphing wing skin applications due to their anisotropic behaviour that allows chordwise camber and length changes. Aerofoils with corrugated skins in the aft 1/3 of the chordwise section have been studied experimentally and computationally using various corrugation shapes and forms (sinusoidal, trapezoidal and triangular) at different Reynolds numbers. The study showed that the aerodynamic performance is highly dependent on corrugation amplitude, wavelength, gradient (combination of amplitude and wavelength) and Reynolds number. Evidence is given highlighting that penalties for having a non-smooth surface in the aft 1/3 of the chordwise section of an aerofoil can be eliminated for the lift curve slope and minimised for the zero lift drag coefficient.
The behaviour of an initially planar shock wave propagating into a linearly convergent wedge is investigated experimentally and numerically. In the experiment, a 25° internal wedge is mounted asymmetrically in a pressure-driven shock tube. Shock waves with incident Mach numbers in the ranges of 1.4–1.6 and 2.4–2.6 are generated in nitrogen and carbon dioxide. During each run, the full pressure history is recorded at fourteen locations along the wedge faces and schlieren images are produced. Numerical simulations performed based on the compressible Euler equations are validated against the experiment. The simulations are then used as an additional tool in the investigation.
The linearly convergent geometry strengthens the incoming shock repeatedly, as waves reflected from the wedge faces cross the interior of the wedge. This investigation shows that aspects of this structure persist through multiple reflections and influence the nature of the shock-wave focusing. The shock focusing resulting from the distributed reflected waves of the Mach 1.5 case is distinctly different from the stepwise focusing at the higher incoming shock Mach number. Further experiments using CO2 instead of N2 elucidate some relevant real-gas effects and suggest that the presence or absence of a weak leading shock on the distributed reflections is not a controlling factor for focusing.
The Microlensing Observations in Astrophysics (MOA) is a microlensing survey conducted at Mt. John Observatory in New Zealand. We searched transiting planet candidates from the MOA-I Galactic bulge data, which have been obtained with a 61cm B&C telescope from 2000 to 2005 for a microlensing search. Although this survey data were dedicated to microlensing, they are also quite useful for searching transiting objects because of the large number of stars monitored (~7 million) and the long span of the survey (~6 years). From our analysis, we found 58 transiting planet candidates. We are planning to follow up these candidates with high-precision spectroscopic and photometric observations for further selection, toward the detection of planets by radial velocity observations.
A review of morphing concepts with a strong focus on morphing skins is presented. Morphing technology on aircraft has found increased interest over the last decade because it is likely to enhance performance and efficiency over a wider range of flight conditions. For example, a radical change in configuration, i.e. wing geometry in flight may improve overall flight performance when cruise and dash are important considerations. Although many morphing aircraft concepts have been elaborated only a few deal with the problems relating to a smooth and continuous cover that simultaneously deforms and carries loads. It is found that anisotropic and variable stiffness structures offer potential for shape change and small area increase on aircraft wings. Concepts herein focus on those structures where primary loads are transmitted in the spanwise direction and a morphing function is achieved via chordwise flexibility. To meet desirable shape changes, stiffnesses can either be tailored or actively controlled to guarantee flexibility in the chordwise (or spanwise) direction with tailored actuation forces. Hence, corrugated structures, segmented structures, reinforced elastomers or flexible matrix composite tubes embedded in a low modulus membrane are all possible structures for morphing skins. For large wing area changes a particularly attractive solution could adopt deployable structures as no internal stresses are generated when their surface area is increased.
Several systems have been proposed for the overall assessment of animal welfare at the farm level for the purpose of advising farmers or assisting public decision-making. They are generally based on several measures compounded into a single evaluation, using different rules to assemble the information. Here we discuss the different methods used to aggregate welfare measures and their applicability to certification schemes involving welfare. Data obtained on a farm can be (i) analysed by an expert who draws an overall conclusion; (ii) compared with minimal requirements set for each measure; (iii) converted into ranks, which are then summed; or (iv) converted into values or scores compounded in a weighted sum (e.g. TGI35L) or using ad hoc rules. Existing methods used at present (at least when used exclusively) may be insufficiently sensitive or not routinely applicable, or may not reflect the multidimensional nature of welfare and the relative importance of various welfare measures. It is concluded that different methods may be used at different stages of the construction of an overall assessment of animal welfare, depending on the constraints imposed on the aggregation process.
The light curves for three eclipsing binaries in the Magellanic Clouds have been obtained using CCD uVJIC photometry. One target in the LMC, MACHO*05:36:48.7−69:17:00, is an eccentric system, e = 0.20, with a period of 3.853534 ± 0.000005 d. Initial solutions indicate a primary component in the range Teff,1 = 20,000−35,000K and the secondary Teff,2 1000−2000K cooler than the primary, with inclinations ranging i = 84.2° − 86.0°. Two targets in the SMC, MOA J005018.4-723855 and MOA J005623.5−722123, have periods of 1.8399±0.0004 and 2.3199 ± 0.0003 days respectively. Both have circular orbits with the former being a semi-detached system.
An overview of silicon carbide (SiC) power device technology is given with an emphasis on processing issues and commercial applications. Schottky Barrier Diodes (SBDs) were the first to be made commercially available in 2001, with power switch and RF amplifiers soon to follow. This paper discusses the performance of current available rectifiers and published power switch development and identifies key issues in processing and device structures which have influenced past and will impact future SiC product development.
A 2,3-dibutoxy-1,4-phenylenevinylene comonomer was incorporated into a distyrylbenzene derivative 11. Novel 1,2-disubstituted-3,6-dibromobenzene comonomers 15 and 18 were prepared by directed metallation. Copolymerization of 11with a 9,9-dioctylfluorene-2,7-diboronate ester 1 yielded a green fluorescent polymer while copolymerization of 15 and 18 with the 9,9-dihexylfluorene-2,7-diboronate 22 afforded promising blue fluorescent polymers 23 and 24 respectively.
A review of the MOA (Microlensing Observations in Astrophysics) project is presented. MOA is a collaboration of approximately 30 astronomers from New Zealand and Japan established with the aim of finding and detecting microlensing events towards the Magellanic Clouds and the Galactic bulge, which may be indicative of either dark matter or of planetary companions. The observing program commenced in 1995, using very wide band blue and red filters and a nine-chip mosaic CCD camera.
As a by-product of these observations a large database of CCD photometry for 1.4 million stars towards both LMC and SMC has been established. In one preliminary analysis 576 bright variable stars were confirmed, nearly half of them being Cepheids. Another analysis has identified large numbers of blue variables, and 205 eclipsing binaries are included in this sample. In addition 351 red variables (AGB stars) have been found. Light curves have been obtained for all these stars. The observations are carried out on a 61-cm f/6.25 telescope at Mt John University Observatory where a new larger CCD camera was installed in 1998 July. From this latitude (44° S) the Magellanic Clouds can be monitored throughout the year.