The Putative Cerean Exosphere

The ice-rich crust of dwarf planet 1 Ceres is the source of a tenuous water exosphere, and the behavior of thisputative exosphere is investigated with model calculations. Outgassing water molecules seasonally condensearound the winter pole in an optically thin layer

R (2004) A comparison of the effects of Snoezelen and reminiscence therapy on the agitated behaviour of patients with dementia

SUMMARY Background Behavioural disturbance, such as agitation, is a common feature of dementia, and causes significant problems and distress for carers. Snoezelen is increasingly used with people who have dementia, but there is limited evidence of its efficacy. Objective This crossover randomised controlled study aimed to evaluate the effect of Snoezelen on the mood and behaviour of patients with dementia, in comparison to the effect of an established and accepted intervention, reminiscence therapy. Methods Twenty patients with dementia and significant agitated behaviour, received three sessions each of Snoezelen and reminiscence. The effects were assessed using measures of observed agitated behaviour and heart rate over the course of the sessions, and mood and behaviour during the sessions. Results Both interventions had a positive effect. Snoezelen was no more beneficial than reminiscence in terms of effecting a significant reduction in agitated behaviour or heart rate. There was considerable variation in the way individuals responded to each intervention. Snoezelen may have a more positive effect than reminiscence, but due to the observed differences between the interventions being small, and the small number of subjects, this advantage was not demonstrated statistically. Conclusions Further research, with larger numbers of subjects, and an appropriate control is required to establish the benefits of Snoezelen for people at different stages of dementia, and to identify any benefits additional to those derived from increased staff attention

Carbon on Vesta and Ceres: Constraints from nuclear spectroscopy

International audienceThe NASA Dawn mission's Gamma Ray and Neutron Detector (GRaND) mapped the elemental composition of (4) Vesta and the dwarf planet Ceres, providing constraints on their formation and interior evolution. Data from Vesta and Ceres were acquired under similar conditions and at the same relative distance (about 0.8 body radii altitude). This enabled direct comparison of cosmogenic neutron and gamma ray signatures sensitive to the elemental composition of the bulk regolith to depths of a few decimeters. Analyses of GRaND data show that Vesta's basaltic regolith is contaminated by a few hundred µg/g hydrogen from the infall of carbonaceous chondrite impactors, which implies that the regolith contains less than 1 mg/g C. In contrast, Ceres' regolith contains between 1.8-and 3.2-wt.% hydrogen in the form of aqueous alteration products and water ice. Carbon was detected in the analysis of the gamma ray spectrum above 4 MeV, which includes contributions from C, O, and Fe. Analyses of neutron data indicate Ceres' ice-free regolith contains higher concentrations of C than found in C-rich meteorites (>3.5 wt.%). The ice-free regolith contains more H and less Fe than CI carbonaceous chondrites, Ceres' closest meteorite analogs. The addition of 10-to 15-wt.% C as carbonates and organics can explain the difference between Ceres and the meteorites. Carbonates, organics, and graphitized carbon are found on the surface of Ceres [2-4]. Graphitization by ionizing radiation may limit the lifetime of organics on the surface. Thus, organics may be more pervasive than indicated by infrared spectroscopy [5]. Ceres and the CI chondrites likely formed from a common reservoir within the solar nebula. Consequently, super chondritic abundances of H and C within Ceres' regolith are consistent with many lines of evidence that show Ceres underwent ice-rock fractionation. The presence of carbon in a water-rich environment makes Ceres a desirable target for studies of prebiotic chemistry

Variability in response to older people with dementia to both Snoezelen and reminiscence

Snoezelen and reminiscence are interventions commonly used by occupational therapists in dementia care. Snoezelen is reported to have a positive effect on patients' mood and their behaviour, in particular on agitated behaviour. A study was designed to assess the effects of Snoezelen on agitated behaviour in dementia. Reminiscence therapy was selected as a suitable comparison intervention, which would enable the benefits of Snoezelen other than those attributable to receiving one-to-one attention from staff to be evaluated. There was found to be considerable variation in the direction and magnitude of change in individual participants' agitated behaviour and heart rate during and after the sessions. This article considers the possible explanations for these individual differences and the practical implications of this research

A pilot study of the physiological and behavioural effects of snoezelen in dementia

Recent interest in the use of Snoezelen as an intervention for agitated behaviour in patients with dementia remains supported by limited evidence of efficacy. This pilot study aimed to develop an approach for assessing the effects of Snoezelen on agitated behaviour in patients with dementia and its comparability with an existing control intervention. Ten patients with dementia were randomised to receive a 4-week course of either Snoezelen or reminiscence therapy. The therapeutic effects were assessed using the Agitation Behaviour Mapping Instrument (ABMI) and the Cohen-Mansfield Agitation Inventory (CMAI) and by heart rate recording. Differences in dementia severity between the two groups hindered direct comparison of outcomes. Both interventions were well tolerated and the majority of both Snoezelen and reminiscence sessions were rated positively. The ABMI ratings suggested that Snoezelen might have reduced agitated behaviour during and immediately after the session but that this effect was short-lived. The CMAI scores indicated reduced agitated behaviour during the intervention period. Heart rate data showed both decreases and increases during the sessions for different participants. With minor modifications, the measures used will be appropriate for a full-scale comparative trial. Both interventions may have helpful short-term effects and while for some patients the sessions are primarily relaxing, for others they may have a more stimulating effect

High spatial resolution measurements of Ceres’ elemental composition

International audienceDuring Dawn's primary mission at Ceres, the Gamma Ray and Neutron Detector (GRaND) acquired global elemental mapping data from a circular, polar orbit, 385 km from the surface. GRaND is sensitive to the composition of the bulk regolith to depths of a few decimeters within surface regions similar in scale to the spacecraft's orbital altitude. The data indicate that Ceres experienced ice-rock fractionation, concentrating water ice and aqueous alteration products within the crust and regolith [1]. In the final phase of the mission, the spacecraft was placed into elliptical orbits around Ceres with periapsis at 35 km altitude in order to acquire elemental data with high spatial resolution and sensitivity. The orbits sampled a narrow band of longitudes around Occator crater, with periapsis gradually drifting from the northern to the southern hemisphere, crossing Urvara crater. With 50-km spatial resolution at periapsis, the GRaND data offer a new view of Ceres at scales compatible with geology, mineralogy, topography and gravity data sets, yielding fresh insights into crustal processes and interior evolution. GRaND measurements reveal compositional variations within the young, 92-km diameter Occator crater and its ejecta blanket, providing geochemical constraints on crater formation and cryovolcanism, and enabling characterization of materials recently ejected from Ceres' crust. Preliminary analyses of neutron spectra suggest that the crater interior contains relatively high concentrations of hydrogen and/or neutron absorbers, such as chlorine. Lobate deposits within the floor of the crater may contain water ice [2], and the faculae contain hydrogen-rich materials, such as ammonium chloride [3], which could be widespread within the crater's subsurface. Increased signal-to-background ratios at low altitudes enable more accurate determination of concentrations and bounds for a wider range of elements. Target elements include H, C, Si, Cl, K, and Fe. Measurements of ejecta from Occator and the older Yalode and Urvara impact basins provide new information on crustal composition and heterogeneity

Compositional variability on the surface of 1 Ceres revealed through GRaND measurements of high-energy gamma rays

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The Putative Cerean Exosphere

The ice-rich crust of dwarf planet 1 Ceres is the source of a tenuous water exosphere, and the behavior of this putative exosphere is investigated with model calculations. Outgassing water molecules seasonally condense around the winter pole in an optically thin layer. This seasonal cap reaches an estimated mass of at least 2 x 10(3) kg, and the aphelion summer pole may even retain water throughout summer. If this reservoir is suddenly released by a solar energetic particle event, it would form a denser transient water exosphere. Our model calculations also explore species other than H2O. Light exospheric species escape rapidly from Ceres due to its low gravity, and hence their exospheres dissipate soon after their respective source has faded. For example, the theoretical turn-over time in a water exosphere is only 7 hr. A significant fraction of CO2 and SO2 molecules can get trapped and stored in perennially shadowed regions at the current spin axis orientation, but not at the higher spin axis tilt, leaving H2O as the only common volatile expected to accumulate in polar cold traps over long timescales. The D/H fractionation during migration to the cold traps is only about 10%.National Aeronautics and Space Administration [NNX15AI38G, 80NSSC17K0545]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Ceres: Astrobiological Target and Possible Ocean World

International audienceCeres, the most water-rich body in the inner solar system after Earth, has recently been recognized to have astrobiological importance. Chemical and physical measurements obtained by the Dawn mission enabled the quantification of key parameters, which helped to constrain the habitability of the inner solar system's only dwarf planet. The surface chemistry and internal structure of Ceres testify to a protracted history of reactions between liquid water, rock, and likely organic compounds. We review the clues on chemical composition, temperature, and prospects for long-term occurrence of liquid and chemical gradients. Comparisons with giant planet satellites indicate similarities both from a chemical evolution standpoint and in the physical mechanisms driving Ceres' internal evolution