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Velocity Interferometer System for Any Reflector (VISAR) [Barker and Hollenbach, J. Appl. Phys. 43, 4669 (1972)] is a well-known diagnostic that is employed on many shock physics and pulsed-power experiments. With the VISAR diagnostic, the velocity on the surface of any metal flyer can be found. For most experiments employing VISAR, either a kinetic pressure [Grady, Mech. Mater. 29, 181 (1998)] or a magnetic pressure [Lemke et al., Intl J. Impact Eng. 38, 480 (2011)] drives the motion of the flyer. Moreover, reliable prediction of the time-dependent pressure is often a critical component to understanding the physics of these experiments. Although VISAR can provide a precise measurement of a flyer’s surface velocity, the real challenge of this diagnostic implementation is using this velocity to unfold the time-dependent pressure. The purpose of this paper is to elucidate a new method for quickly and reliably unfolding VISAR data.
The highest efficiency CuIn1-xGaxSe2 (CIGS) based solar cells have been produced from films with x∼0.3 which gives a value of Eg around 1.1-1.2eV. Increasing the Ga content of the CIGS absorber provides an increase in Voc, allows tuning of the band gap that can enhance performance under actual operating conditions, and potentially makes it possible to use CIGS films in multi-junction devices. However, champion cells have not yet been produced for values of x significantly greater than 0.3. This work focuses on how increased Ga content in CIGS films affects the recombination behavior of grain boundaries. Cathodoluminescence spectral imaging (CLSI) measurements on fully processed devices allow us to compare device properties with recombination behavior and optical properties of grain boundaries in films with different Ga content. Our data suggests that grain boundaries in high efficiency films with x∼0.3 exhibit a significant red shift in the CL spectra whereas grain boundaries in films with higher Ga content typically show either a small shift or none at all. This shift indicates band bending near the boundaries which could enhance charge separation and subsequent collection of carriers generated near grain boundaries. This is investigated statistically to identify trends in different regions of the films.
Properties of radiatively cooled supersonic plasma jets formed by ablation of thin Al
foils driven by 1.4 MA, 250 ns current pulse are presented. The jets are highly collimated
with half-opening angles of ~2°. Measurements of the flow velocity (~60
km/s) and plasma temperature (~15 eV) in the jet with Thomson scattering diagnostic
give internal Mach number of M ~ 3, suggesting additional collimation of the jet by
toroidal magnetic fields.
The formation of supersonic, radiatively cooled plasma jets with applications to
laboratory astrophysics has been an active area of research on the MAGPIE generator. One
of the ways of producing astrophysically-relevant jets in the laboratory is by using the
ablation of plasma from a radial foil Z-pinch. In this configuration a ~1.4 MA, 250
ns current pulse is introduced into an aluminium disk with a thickness of 15
μm. The ablated plasma from the foil converges on the axis, producing a
steady and collimated jet with a typical axial velocity of ~100 km/s. The setup
allows for the addition of argon above the foil for jet-ambient interaction studies. The
interaction is characterised by the formation of several shock features, which are
presented and discussed from experimental data and numerical simulations.
Over the past 3 years, we have conducted a survey of 100 square degrees of the southern Galactic plane with the Mopra radiotelescope (HOPS). The survey includes observations of multiple spectral lines in the 12 mm band, with the most important being the water maser transition at 22.2 GHz and the non-metastable inversion transitions of ammonia. We report on initial results from HOPS, including the detection of 540 water masers, about two-thirds of which appear to be new detections. We also find widespread emission in the NH3 (1,1) line, as well as detec tions in the NH3 (2,2), (3,3), (6,6) and (9,9) lines.
Collimated outflows (jets) are ubiquitous in the universe, appearing around sources as diverse as protostars and extragalactic supermassive black holes. Jets are thought to be magnetically collimated, and launched from a magnetized accretion disk surrounding a compact gravitating object. We have developed the first laboratory experiment to address time-dependent, episodic phenomena relevant to the poorly understood jet acceleration and collimation region (Ciardi et al., 2009). The experiments were performed on the MAGPIE pulsed power facility (1.5 MA, 250 ns) at Imperial College. The experimental results show the periodic ejections of magnetic bubbles naturally evolving into a heterogeneous jet propagating inside a channel made of self-collimated magnetic cavities. The results provide a unique view of the possible transition from a relatively steady-state jet launching to the observed highly structured outflows.
To deliver quality care at the end of life, understanding the impact of various changes and life transitions that occur in older age is essential. This review seeks to uncover potential sources of distress in an elder's physical, psychological, social, and spiritual well-being to shed light on the unique challenges and needs facing this age group.
Papers relating to older adults (aged 65 years and older or a mean age of 65 years and older) with advanced/terminal cancer receiving palliative, hospice, or end-of-life care published after 1998 were reviewed.
Older adults with advanced cancer have unique needs related to changes in their physical, psychological, social, and spirituals well-being. Changes in each of these domains offer not only the risk of causing distress but also the potential for growth and development during the final stages of advanced cancer.
Significance of results:
Being aware of the various changes that occur with aging will help health care professionals tailor interventions to promote dignity-conserving care and greatly reduce the potential for suffering at the end of life.
This paper is an interim report of our inferences about the hydrostatic structure of the Sun, following the first report of the GONG team in Science (Gough et al., 1996). That work confirms that the spherically averaged structure of the Sun is more or less in agreement with current standard solar models. However, there remain some significant deviations which we regard as important clues to the existence of dynamical phenomena which are not taken into account in standard solar modelling.
A model of a drying swath has been developed and used with 20-year long meteorological data sets from 32 sites in north-west Europe to provide an objective assessment of the influence of weather on field hay drying. The model considered the swath in terms of its bulk properties but incorporated the effects on swath drying of soil evaporation and stubble transpiration: delays in swath drying caused by interception of rain or dew were calculated explicitly.
A cutting season from May to September was assumed, and results given in terms of the number of daily cuts reaching various moisture contents in less than 10 days, and especially those reaching 25% (dry-weight basis) within 5 days so that dry-matter losses were relatively small, and immediate long-term storage was possible. Rainfall amounts on the faster-drying swaths were usually less than 1 mm. A large inter-annual variability in hay-drying prospects was demonstrated, even at sites with fairly good climates for drying on average. The most favourable conditions for field drying were shown to occur substantially earlier in the cutting season at maritime sites than at those with a more continental climate. Conditioning of the swath allowed more cuts to dry to a prescribed moisture content, but with the penalty of larger average rainfall on the swath, and consequent loss of quality.
A study of 20 manic patients, with patient and matched control comparisons, showed a two fold increase in life events during the 4 month period before admission to hospital. Life events, independent of affective illness and having significant objective negative impact (i.e. traumatic) were significantly more common. These findings are considered in relation to social relationships, family history of affective illness and the use of psychotropic medication.
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