547 research outputs found
Clasts in the CM2 carbonaceous chondrite Lonewolf Nunataks 94101: evidence for aqueous alteration prior to complex mixing
Clasts in the CM2 carbonaceous chondrite Lonewolf Nunataks (LON) 94101 have been characterized using scanning and transmission electron microscopy and electron microprobe analysis to determine their degrees of aqueous alteration, and the timing of alteration relative to incorporation of clasts into the host. The provenance of the clasts, and the mechanism by which they were incorporated and mixed with their host material are also considered. Results show that at least five distinct types of clasts occur in LON 94101, of which four have been aqueously altered to various degrees and one is largely anhydrous. The fact that they have had different alteration histories implies that the main part of aqueous activity occurred prior to the mixing and assimilation of the clasts with their host. Further, the presence of such a variety of clasts suggests complex mixing in a dynamic environment involving material from various sources. Two of the clasts, one containing approximately 46 vol% carbonate and the other featuring crystals of pyrrhotite up to approximately 1 mm in size, are examples of unusual lithologies and indicate concentration of chemical elements in discrete areas of the parent body(ies), possibly by flow of aqueous solutions
Metamorphism on Ordinary Chondrite Parent Bodies: The Role of Fluids.
第3回極域科学シンポジウム/第35回南極隕石シンポジウム 11月30日(金) 国立国語研究所 2階講
Vertical flow in the Southern Ocean estimated from individual moorings
In this study, we demonstrate that oceanic vertical velocities can be estimated from individual mooring measurements, even for non-stationary flow. This result is obtained under three assumptions: i. weak diffusion (Péclet number ≫1), ii. weak friction (Reynolds number ≫1), and iii. small inertial terms (Rossby number ≪1). The theoretical framework is applied to a set of 4 moorings located in the Southern Ocean. For this site, the diagnosed vertical velocities are highly variable in time, their standard deviation being one-to-two orders of magnitude greater than their mean. We demonstrate that the time-averaged vertical velocities are largely induced by geostrophic flow, and can be estimated from the time-averaged density and horizontal velocities. This suggests that local time-mean vertical velocities are primarily forced by the time-mean ocean dynamics, rather than by e.g. transient eddies or internal waves. We also show that, in the context of these four moorings, the time-mean vertical flow is consistent with stratified Taylor column dynamics in the presence of a topographic obstacle
Stacking Defects in Synthetic and Meteoritic Hibonites: Implications for High-Temperature Processes in the Solar Nebula
Hibonite (CaAl12O19) is a primary, highly refractory phase occurring in many Ca-Al-rich inclusions (CAIs) from different chondrite groups, except CI chondrites. Hibonite is predicted to be one of the earliest minerals to condense during cooling of the solar nebula at higher temperatures than any other major CAI mineral. Therefore, hibonite has great potential to reveal the processes and conditions of the very early, high-temperature stages of the solar nebular evolution. Previous microstructural studies of hibonite in CAIs and their Wark-Lovering (WL) rims showed the presence of numerous stacking defects in hibonite. These defects are interpreted as the modification of the stacking sequences of spinel and Ca-containing blocks within the ideal hexagonal hibonite structure, as shown by experimental studies of reaction-sintered ceramic CaO-Al2O3 compounds. We performed preliminary experiments in the CaO-Al2O3-MgO system to understand the formation processes and conditions of defect-structured hibonite found in meteorites
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Interventions to promote patients and families' involvement in adult intensive care settings: a protocol for a mixed-method systematic review.
BACKGROUND: There has been an identified need for greater patient and family member involvement in healthcare. This is particularly relevant in an intensive care unit (ICU), as the family provides a key communicative and practical link between patient and clinician. Family members have been deemed a positive beneficial influence on ICU care and recovery processes, yet they themselves are often emotionally affected after discharge. There has been no standardised evidenced-based approach which explores research on family member involvement and the range and quality of contributions remain unclear. This project will undertake a systematic review to assess the evidence base for interventions designed to promote patient and family member involvement in adult intensive care settings and develop a comprehensive typology of interventions for use by clinicians, patients and carers. METHODS: The following databases will be searched without date restriction: MEDLINE, EMBASE and CINAHL, as well as the Cochrane Central Register of Controlled Trials, Joanna Briggs and Cochrane Libraries. Manual searches of recent back issues of leading ICU and patient experience journals will also be undertaken, as will the reference lists of included studies. Unpublished literature will be sought through grey literature databases, including GreyLit and OpenGrey. All evaluation studies that consider intervention activities to promote patient and family member involvement in adult ICUs will be included; all research designs will be eligible. We will seek to include studies that report on a mixture of relevant outcomes for patients and family members. Abstracts and papers will be independently screened by at least two members of the team to determine their inclusion. Included papers will be assessed for methodological rigour using a standard rating approach, which assesses 'quality of study' and 'quality of information'. Quality assessment will be completed by at least two members of the team. Data on interventions, evaluation methods and outcomes will be collated using a predetermined extraction table. These are likely to be heterogeneous in nature, which will mean that the review will follow a narrative approach to synthesis. DISCUSSION: The review will provide valuable and rigorous insight into the range and quality of interventions available to promote patient and family member involvement in ICU. This is the first step towards addressing the absence of a synthesis of research for this context, and will, in addition, develop a typology of available interventions that will help service users and clinicians make informed decisions about the approaches to patient and family member involvement which they might want to adopt. SYSTEMATIC REVIEW REGISTRATION: PROSPERO (CRD42018086325)
An unusual clast in lunar meteorite MacAlpine Hills 88105: a unique lunar sample or projectile debris?
Lunar meteorite MacAlpine Hills (MAC) 88105 is a well-studied feldspathic regolith breccia dominated by rock and mineral fragments from the lunar highlands. Thin section MAC 88105,159 contains a small rock fragment, 400 × 350 μm in size, which is compositionally anomalous compared with other MAC 88105 lithic components. The clast is composed of olivine and plagioclase with minor pyroxene and interstitial devitrified glass component. It is magnesian, akin to samples in the lunar High Mg-Suite, and also alkali-rich, akin to samples in the lunar High Alkali Suite. It could represent a small fragment of late-stage interstitial melt from an Mg-Suite parent lithology. However, olivine and pyroxene in the clast have Fe/Mn ratios and minor element concentrations that are different from known types of lunar lithologies. As Fe/Mn ratios are notably indicative of planetary origin, the clast could either (1) have a unique lunar magmatic source, or (2) have a nonlunar origin (i.e., consist of achondritic meteorite debris that survived delivery to the lunar surface). Both hypotheses are considered and discussed
Modification of turbulent dissipation rates by a deep Southern Ocean eddy
The impact of a mesoscale eddy on the magnitude and spatial distribution of diapycnal ocean mixing is investigated using a set of hydrographic and microstructure measurements collected in the Southern Ocean. These data sampled a baroclinic, mid-depth eddy formed during the disintegration of a deep boundary current. Turbulent dissipation is suppressed within the eddy, but is elevated by up to an order of magnitude along the upper and lower eddy boundaries. A ray-tracing approximation is employed asa heuristic device to elucidate how the internal wave field evolves in the ambient velocity and stratification conditions accompanying the eddy. These calculations are consistent with the observations, suggesting reflection of internal wave energy from the eddy center and enhanced breaking through critical layer processes along the eddy boundaries. These results have important implications for understanding where and how internal wave energy is dissipated in the presence of energetic deep geostrophic flows
The effectiveness and cost-effectiveness of acupressure for the control and management of chemotherapy-related acute and delayed nausea: Assessment of Nausea in Chemotherapy Research (ANCHoR), a randomised controlled trial
Chemotherapy-induced nausea and vomiting remain difficult symptoms to manage in clinical practice. As standard antiemetic drugs do not fully eliminate these symptoms, it is important to explore the adjuvant role of non-pharmacological and complementary therapies in antiemetic management approaches. Acupressure is one such treatment showing highly suggestive evidence so far of a positive effect, meriting further investigation
Observed eddy-internal wave interactions in the Southern Ocean
The physical mechanisms that remove energy from the Southern Ocean’s vigorous mesoscale eddy field are not well understood. One proposed mechanism is direct energy transfer to the internal wave field in the ocean interior, via eddy-induced straining and shearing of preexisting internal waves. The magnitude, vertical structure, and temporal variability of the rate of energy transfer between eddies and internal waves is quantified from a 14-month deployment of a mooring cluster in the Scotia Sea. Velocity and buoyancy observations are decomposed into wave and eddy components, and the energy transfer is estimated using the Reynolds-averaged energy equation. We find that eddies gain energy from the internal wave field at a rate of −2.2 ± 0.6 mW m−2, integrated from the bottom to 566 m below the surface. This result can be decomposed into a positive (eddy to wave) component, equal to 0.2 ± 0.1 mW m−2, driven by horizontal straining of internal waves, and a negative (wave to eddy) component, equal to −2.5 ± 0.6 mW m−2, driven by vertical shearing of the wave spectrum. Temporal variability of the transfer rate is much greater than the mean value. Close to topography, large energy transfers are associated with low-frequency buoyancy fluxes, the underpinning physics of which do not conform to linear wave dynamics and are thereby in need of further research. Our work suggests that eddy–internal wave interactions may play a significant role in the energy balance of the Southern Ocean mesoscale eddy and internal wave fields
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