Description: Aims It is unclear whether the cognitive dysfunctionassociated with heart failure (HF) is due to HF or comorbid conditions such as ischaemic heart disease (IHD). This study aimed to determine whether, compared with controls with and without IHD, adults with systolic HF show evidence of cognitive impairment and cerebral grey matter (GM) loss. Methods and results Cross-sectional study of 35 participants with HF, 56 with IHD, and 64 controls without either HF or IHD. Subjects were older than 45 years and free of overt cognitive impairment. We acquired magnetic resonance images and used SPM8 to determine regional differences in cerebral GM volume. Participants with HF had lower scores than controls without IHD on immediate memory, long delay recall and digit coding, whereas those with IHD had lower long delay recall scores than controls without IHD. Compared with controls without IHD, participants with HF showed evidence of GM loss in the left cingulate, the right inferior frontal gyrus, the left middle and superior frontal gyri, the right middle temporal lobe, the right and left anterior cingulate, the right middle frontal gyrus, the inferior and pre-central frontal gyri, the right caudate, and occipital-parietal regions involving the left precuneus. The loss of GM followed a similar, less extensive, pattern when we compared participants with HF and IHD. Conclusion Adults with HF have worse immediate and long-term memory and psychomotor speed than controls without IHD. Heart failure is associated with changes in brain regions that are important for demanding cognitive and emotional processing.

Description: Koegel Fontein, about 350 km north of Cape Town, is the only known early Cretaceous anorogenic igneous complex along the volcanic rifted margin of South Africa. The oldest rocks of the complex are minor granite and syenite intrusions at 144 Ma, which were followed by tholeiitic and alkaline basalt dykes, then by microsyenite and quartz porphyry dykes. The youngest and largest igneous unit is the 135 Ma Rietpoort Granite, with an exposed diameter of about 20 km. The country rocks are Mesoproterozoic gneisses of the Namaqua–Natal Province, which in many places were deformed and retrogressed by Pan-African tectonism. Whole-rock 18 O values from the Rietpoort Granite and smaller plutonic units (syenite, granite) are in the range 6–9 (outliers 4 and 17). Quartz 18 O values from all units are in a narrow range and indicate magma 18 O values between 6 and 8. In contrast to the syenites and granites, most mafic and silicic dyke units have 18 O 〈6, as low as –4·1. Quartz porphyry dykes that are compositionally similar to the Rietpoort Granite have a bimodal distribution of 18 O values in both whole-rock and quartz phenocrysts. The magma 18 O values estimated from the phenocryst data define a ‘normal group’ identical to the Rietpoort Granite (6–8) and a ‘low- 18 O group’ (0 to –2). The microsyenite and mafic dykes also yield negative 18 O values, but the strong hydrothermal alteration of these rocks and lack of fresh phenocrysts make a primary origin of the low 18 O values unlikely and untestable. Whole-rock D values of igneous units and basement rocks average –99, which corresponds to a palaeo-meteoric water with 18 O as low as –9. This is much lower than the expected value for meteoric water at the time of emplacement, given the low latitude (30–40°S). Quartz veins cutting the mafic dykes have 18 O values as low as –2, which attest to hydrothermal fluids having low 18 O values. Country rocks in the study area have a large range of 18 O (–3 to 10), with the majority below the mantle value of 6. The low 18 O values of the country rocks, although prevalent in the roof pendant of the Rietpoort Granite, do not appear to have originated from a meteoric–hydrothermal system established by the intrusions. We suggest instead that the Koegel Fontein complex was emplaced into a structurally controlled zone in the Namaqualand basement whose 18 O values had been lowered by interaction with meteoric fluid during reactivation along Pan-African shear zones. Initial emplacement of the magmas caused thermal dehydration of the country rocks and expulsion of low- 18 O fluids. This was followed by local partial melting of the altered crust with formation of low- 18 O crustal magmas. The O isotope data provide new constraints on the crustal vs mantle source of the Koegel Fontein magmas. The Rietpoort Granite and ‘normal 18 O’ quartz-porphyry dykes crystallized from magmas with 18 O values of 7–8, Nd of –5 to –7, and initial 87 Sr/ 86 Sr of 0·716–0·732, which fit a model for 30–50% meta-igneous crust similar to the local Namaqua gneisses, with a minor component of low- 18 O crust. The ‘low- 18 O’ quartz porphyry magma had an identical Nd isotope composition, but lower initial 87 Sr/ 86 Sr (0·709–0·725) and 18 O (0 to –2), which we attribute to melting or assimilation of hydrothermally altered basement rocks with Rb and 18 O depletion.

Description: 〈jats:title〉Abstract〈/jats:title〉 〈jats:p〉Thawing of ice-rich permafrost soils in sloped terrain can lead to activation of retrogressive thaw slumps (RTSs) which make organic matter available for decomposition that has been frozen for centuries to millennia. Recent studies show that the area affected by RTSs increased in the last two decades across the pan-Arctic. Combining a model of soil carbon dynamics with remotely sensed spatial details of thaw slump area and a soil carbon database, we show that RTSs in Siberia turned a previous quasi-neutral ecosystem into a strong source of carbon dioxide of 367 ± 213 gC m-1 a-1. On a global scale, recent CO〈jats:sub〉2〈/jats:sub〉 emissions from Siberian thaw slumps of 0.42 ± 0.22 Tg carbon per year are negligible so far. However, depending on the future evolution of permafrost thaw and hence thaw slump-affected area, such hillslope processes can transition permafrost landscapes to become a major source of additional CO〈jats:sub〉2〈/jats:sub〉 release into the atmosphere.〈/jats:p〉