RESUMO
The abundances of water and highly to moderately volatile elements in planets are considered critical to mantle convection, surface evolution processes, and habitability. From the first flyby space probes to the more recent "Perseverance" and "Tianwen-1" missions, "follow the water," and, more broadly, "volatiles," has been one of the key themes of martian exploration. Ratios of volatiles relative to refractory elements (e.g., K/Th, Rb/Sr) are consistent with a higher volatile content for Mars than for Earth, despite the contrasting present-day surface conditions of those bodies. This study presents K isotope data from a spectrum of martian lithologies as an isotopic tracer for comparing the inventories of highly and moderately volatile elements and compounds of planetary bodies. Here, we show that meteorites from Mars have systematically heavier K isotopic compositions than the bulk silicate Earth, implying a greater loss of K from Mars than from Earth. The average "bulk silicate" δ41K values of Earth, Moon, Mars, and the asteroid 4-Vesta correlate with surface gravity, the Mn/Na "volatility" ratio, and most notably, bulk planet H2O abundance. These relationships indicate that planetary volatile abundances result from variable volatile loss during accretionary growth in which larger mass bodies preferentially retain volatile elements over lower mass objects. There is likely a threshold on the size requirements of rocky (exo)planets to retain enough H2O to enable habitability and plate tectonics, with mass exceeding that of Mars.
RESUMO
BACKGROUND: Carers play an important role in supporting client adjustment and relapse prevention following a first psychotic episode. The caring experience however is a stressful and demanding one, and carers require support to develop coping strategies and sustain themselves in their role. AIMS: To evaluate a psychoeducation programme provided within a public adult mental health service, designed for the families of clients experiencing first-episode psychosis. METHODS: A pre- and post-test questionnaire was administered to quantitatively measure the participants' changes in perceptions of their knowledge and understanding regarding mental illness and its treatment through attending the group. Qualitative items were included to ascertain other knowledge gained or benefits perceived and any critical feedback. RESULTS: The programme significantly improved carers' perceptions of their understanding of psychosis, recovery and relapse prevention. Additional feedback replicated previous findings that participants value support and feel less isolated through group attendance, gaining a sense of collective experience and the opportunity to share experiences and feel heard by peers. CONCLUSIONS: The evaluation demonstrates the efficacy of such a group and the importance of public mental health services in providing family interventions in first-episode psychosis care.