420 research outputs found
Improved algorithm for the direct dynamics variational multi-configurational Gaussian method.
The Direct Dynamics variational Multi-Configurational Gaussian (DD-vMCG) method provides a fully quantum mechanical solution to the time-dependent Schrödinger equation for the time evolution of nuclei with potential surfaces calculated on-the-fly using a quantum chemistry program. Initial studies have shown its potential for flexible and accurate simulations of non-adiabatic excited-state molecular dynamics. In this paper, we present developments to the DD-vMCG algorithm that improve both its accuracy and efficiency. First, a new, efficient parallel algorithm to control the DD-vMCG database of quantum chemistry points is presented along with improvements to the Shepard interpolation scheme. Second, the use of symmetry in describing the potential surfaces is introduced along with a new phase convention in the propagation diabatization. Benchmark calculations on the allene radical cation including all degrees of freedom then show that the new scheme is able to produce a consistent non-adiabatic coupling vector field. This new DD-vMCG version thus opens the route for effectively and accurately treating complex chemical systems using quantum dynamics simulations
Oscillations and running waves observed in sunspots. III. Multilayer study
We continue our study of waves and oscillations observed in sunspots using an improved method for enhancing the waves, giving the opportunity to identify them and determine their properties in far Hα wings. We found that the running penumbral waves are observable at least up to the formation height of the Hα ± 0.5 Å line, but not in the H Hα ± 0.75 Å or the FeI ± 0.12 Å. We found a time lag between the waves in the blue and the red wing of the Hα line corresponding to a phase shift of 180°, that indicates a pure Doppler shift of the line. There is a lag in the propagation of the waves seen at Hα center and at Hα wings. Also there is a lag in the variation of the umbral oscillations as they are observed from lower to higher atmospheric layers. The correlation between umbral oscillations at various atmospheric heights and running penumbral waves strongly indicates that the latter are excited by photospheric umbral oscillations and not the chromospheric ones. We found a new category of photospheric waves that originate at approximately 0.7 of the distance between the umbra and the penumbra boundary and propagate beyond the outer penumbra boundary with a velocity of the order of 3-4 km s^(-1). Further, we found 3 min penumbral oscillations apparent in the inner penumbra at lower chromospheric layers (far Hα wings)
Chromospheric Evershed flow
We studied the chromospheric Evershed flow from filtergrams obtained at nine wavelengths along the Hα profile. We computed line-of-sight velocities based on Becker's cloud model and we determined the components of the flow velocity vector as a function of distance from the center of the sunspot, assuming an axial symmetry of both the spot and the flow. We found that the flow velocity decreases with decreasing height and that the maximum of the velocity shifts towards the inner penumbral boundary. The flow related to some fibrils deviates significantly from the average Evershed flow. The profile of the magnitude of the flow velocity as a function of distance from the spot center, indicates that the velocity attains its maximum value in the downstream part of the flow channels (assumed to have the form of a loop). This behavior can be understood in terms of a critical flow that pass from subsonic to supersonic near the apex of the loop, attains its higher velocity at the downstream part of the loop and finally relaxes to subsonic through a tube shock. We computed the average flow vector from segmented line-of-sight velocity maps, excluding bright or dark fibrils alternatively. We found that the radial component of the velocity does not show a significant difference, but the magnitude of the vertical component of the velocity related to dark fibrils is higher than that related to bright fibrils.
Vegetation of the coastal dunes and wetland of Schinias National Park (NE Attica, Sterea Ellas, Greece)
The vegetation developing on the coastal sand dunes and wetland of Schinias National Park, a Natura 2000 Site, was studied following the Braun-Blanquet method. Vegetation units were delimited using cluster analysis and by applying the fidelity measure; the phi-coefficient was used for the definition of diagnostic species. The vegetation types distinguished (twenty associations, two sub-associations and thirteen communities not assigned formal rank), which belong to 18 alliances, 16 orders and 12 classes, are discussed and presented in phytosociological tables. Among them Mathiolo tricuspidatae-Anthemidetum tomentosae, Pistacio lentisci-Pinetum halepensis pinetosum pineae, Puccinellio festuciformis-Aeluropetum litoralis cressetosum creticae and Tamaricetum tetrandrae are described for the first time. The vegetation types recognized in the study area are linked to twelve EUNIS habitat types, nine of which are related to 13 Annex I habitat types (Directive 92/43/EEC), and one to a habitat type of national interest (72A0). One Annex I habitat type occurring in the study area has scattered presence in the Natura 2000 network in Greece (1420), two are infrequent (2190, 2260), two are rare (2230, 2270) and three are priority habitat types (1150, 2250, 2270)
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A counselling psychology perspective on in-patient settings: considering the relationship of care and depression
Objectives: The way services users understand and relate to the care provided to them is a very important element of their recovery. Qualitative and quantitative studies have focused on psychiatric hospitalisation, from both service user and staff perspectives, mainly from the nursing discipline. However, less is known about the experience of being cared for by others during psychiatric hospitalisation. This study aims to explore the experience of care through a psychologically informed understanding of this experience, so as to elicit themes that have relevance to depression and caring as a result of the care-receiving experience. This study’s unique contribution is that it focuses on the more fundamentally humane phenomenon of “being looked after”. Therefore the objective of this study is to explore the experience of depressed service users being cared for by others (i.e. mental health care professionals) within in-patient psychiatric settings, in order to throw light on the important link between care and depression and so understand the involvement of the care component of hospitalisation on the depressive experience. It is hoped this will contribute to the provision of appropriate services for these individuals. Method: Semi-structured interviews were carried out with eight in-patients who had been diagnosed with, and were undergoing treatment for, depression. Verbatim transcripts of the interviews were then analysed using Interpretative Phenomenological Analysis (IPA).
Results: The analysis produced three master themes: ‘containment’; ‘attached’; ‘arrested temporality’. A description of these master themes and the related subordinate themes is presented.
Conclusion: The results of the analysis are considered in light of existing theory and their clinical implications. The clinical implications of the findings, such as the need to maintain connections with family, foster supportive relationships within the ward environment, understand attachment patterns to the mental health system and temporal idleness within units highlight the need to prioritise the service-user perspective in clinical settings and future research
Deep Halpha imagery of the Eridanus shells
A deep \ha image of interlocking filamentary arcs of nebulosity has been
obtained with a wide-field ( 30\degree diameter) narrow-band filter
camera combined with a CCD as a detector. The resultant mosaic of images,
extending to a galactic latitude of 65, has been corrected for field
distortions and had galactic coordinates superimposed on it to permit accurate
correlations with the most recent H{\sc i} (21 cm), X-ray (0.75 kev) and FIR
(IRAS 100 m) maps.
Furthermore, an upper limit of 0.13 arcsec/yr to the expansion proper motion
of the primary 25\degree long nebulous arc has been obtained by comparing a
recent \ha image obtained with the San Pedro Martir telescope of its
filamentary edge with that on a POSS E plate obtained in 1951.
It is concluded that these filamentary arcs are the superimposed images of
separate shells (driven by supernova explosions and/or stellar winds) rather
than the edges of a single `superbubble' stretching from Barnard's Arc (and the
Orion Nebula) to these high galactic latitudes. The proper motion measurement
argues against the primary \ha emitting arc being associated with the giant
radio loop (Loop 2) except in extraordinary circumstances.Comment: 9 pages, 5 figures, accepted for MNRAS publicatio
An Updated Catalog of 4680 Northern Eclipsing Binaries with Algol-Type light curve morphology in the Catalina Sky Surveys
We present an updated catalog of 4680 northern eclipsing binaries (EBs) with
Algol-type light curve morphology (i.e., with well-defined beginning and end of
primary and secondary eclipses), using data from the Catalina Sky Surveys. Our
work includes revised period determinations, phenomenological parameters of the
light curves, and system morphology classification based on machine learning
techniques. While most of the new periods are in excellent agreement with those
provided in the original Catalina catalogs, improved values are now available
for ~10% of the stars. A total of 3456 EBs were classified as detached and 449
as semi-detached, while 145 cannot be classified unambiguously into either
subtype. The majority of the SD systems seems to be comprised of short-period
Algols. By applying color criteria, we searched for K- and M-type dwarfs in
these data, and present a subsample of 609 EB candidates for further
investigation. We report 119 EBs (2.5% of the total sample) that show maximum
quadrature light variations over long timescales, with periods bracketing the
range 4.5-18 yrs and fractional luminosity variance of 0.04-0.13. We discuss
possible causes for this, making use of models of variable starspot activity in
our interpretation of the results
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