The Paleoarchean Buffalo River komatiites: Progressive melting of a single large mantle plume beneath the growing Kaapvaal craton

Several Archean granitoid-greenstone terranes are exposed on the southeastern Kaapvaal craton in South Africa, but they received little scientific attention compared to the archetypal greenstone belt successions of the Barberton Mountain Land at the eastern craton margin. This study reports on a detailed field and geochemical survey of the Buffalo River Greenstone Belt at the southern Kaapvaal craton margin in KwaZulu-Natal, with focus on hitherto unstudied komatiites and basaltic rocks from this volcanic succession. Cross-cutting relationships and new U-Pb zircon age determinations for several granitoid units establish a minimum age of 3.26 Ga for komatiitic volcanism, possibly as old as ca. 3.5 Ga if a 3.47 Ga granodiorite sheet is interpreted as ‘intrusive’ into the greenstone succession. Geochemical data reveal three types of Paleoarchean komatiites at Buffalo River. Spinifex textured lava flows represent Al-depleted komatiites, with subchondritic Al2O3/TiO2 ratios and enrichment of LREE over HREE. The second type comprises Al-undepleted komatiites that have chondritic Al2O3/TiO2 and flat REE patterns. The third type identified comprises Al-enriched komatiites that display suprachondritic Al2O3/TiO2 ratios, with significant LREE depletion. The Al-depleted and Al-undepleted komatiites from Buffalo River are geochemically similar to komatiites from the 3.48 Ga Komati and 3.26 Ga Weltevreden formations of the Barberton Supergroup respectively, whereas the Al-enriched komatiites resemble the 3.33 Ga Commondale komatiites on the southeastern Kaapvaal craton. To explain the co-occurrence of three discrete komatiite types within a single volcanic succession at Buffalo River, we suggest that each major komatiite magmatic pulse originated from the same upwelling mantle source, from which melt was extracted at different pressure but similarly hot temperature conditions. 187Os/188Os data for the Al-depleted komatiites suggest an ultimate magma origin from a primitive mantle reservoir. The contrasting γOs values for Kaapvaal craton komatiites (zero to positive) and peridotitic mantle xenoliths (zero to negative) support a complementary nature of these lithologies as high-degree melts and depleted residues linked by vigorous mantle plume activity at around 3.5 Ga. Such a relationship can explain the contrasting Re/Os systematics of komatiites and lithospheric mantle peridotites, which creates the contrasting γOs over time. The highly siderophile element patterns of the Al-depleted komatiites from Buffalo River are similar to those of Barberton-type komatiites, for which an origin from the deepest upper mantle with high melt retention in an upwelling plume source was suggested. We confirm that this ca. 3.5 Ga mantle source had only 60–80 % of the platinum-group element budget of the modern ambient mantle, which points indirectly to a location at great depth in the aftermath of the meteoritic late accretion. Progressive melting of such an upwelling mantle source, to the point of majoritic garnet exhaustion, may explain the Al-undepleted and Al-enriched komatiites at Buffalo River. The presence of all three major komatiite types within a single volcanic succession may be linked to deep critical melting of a large mantle plume associated with growth of the Kaapvaal ‘continent’ at 3.5 Ga

Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column

We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O)

Integrated stratigraphy of the Waitakian-Otaian Stage boundary stratotype, Early Miocene, New Zealand

The base of the type section of the Otaian Stage at Bluecliffs, South Canterbury, is recognised as the stratotype for the boundary between the Waitakian and Otaian Stages. Principal problems with the boundary are the restriction of existing bioevent proxies to shelf and upper slope environments and its uncertain age. These topics are addressed by a multidisplinary study of a 125 m section about the boundary, which examines its lithostratigraphy, depositional setting, biostratigraphy, correlation, and geochronology. The lower siltstone lithofacies (0-38.5 m) was deposited at upper bathyal depths (200-600 m) in a marginal basin which was partially sheltered from fully oceanic circulation by a submarine high and islands. The site was covered by cool-temperate water and was probably adjacent to the Subtropical Convergence. This unit is succeeded by the banded lithofacies (38.5-106 m) and the upper siltstone lithofacies (basal 19 m studied). Paleodepth probably declined up-sequence, but deposition at shelf depths is not definitely indicated. A cyclic pattern of abundance spikes in benthic and planktonic foraminifera commences 9 m above base and extends to 73 m in the banded lithofacies. Oxygen isotope excursions (up to 2.08%) in Euuvigerina miozea and Cibicides novozelandicus are greatest within the interval containing the abundance spikes. The stage boundary occurs in the banded lithofacies at the highest abundance spike (73 m). Although condensed intervals might affect the completeness of the section, they are not associated with sedimentary discontinuities, and we consider that the section is suitable as a biostratigraphic reference. Spores, pollens, dinoflagellates, calcareous nannofossils, foraminifera, bryozoans, and ostracods are preserved near the boundary, but molluscs principally occur higher, in the shallower upper siltstone lithofacies. Siliceous microfossils are rare. There is considerable scope for further biostratigraphic research. The primary event marking the boundary at 73 m is the appearance of the benthic foraminifer Ehrenbergina marwicki. This is a distinctive and widely distributed event but is restricted to shelf and upper bathyal environments. Supplementary events in planktonic foraminifera and calcareous nannofossils were researched. Highest occurrences of Globigerina brazieri and G. euapertura are recorded at 47 and 58 m. There is a marked decline in relative abundance of Paragloborotalia spp. at 62 m. Helicosphaera carteri becomes more abundant than H. euphratis between 56 and 87 m. These events are not exact proxies for the boundary but they may usefully indicate proximity to it. They occur in the interval of prominent spikes in foraminiferal abundance. The Waitakian-Otaian boundary is dated at 21.7 Ma by strontium isotopes. Stable primary remanence could not be determined in a pilot paleomagnetic study of Bluecliffs specimens. However, specimens trended towards reversed polarity, and remagnetisation great circle analysis will allow directions to be calculated in future collections

5-deazaflavin derivatives as inhibitors of p53 ubiquitination by HDM2

Based on previous reports of certain 5-deazaflavin derivatives being capable of activating the tumour suppressor p53 in cancer cells through inhibition of the p53-specific ubiquitin E3 ligase HDM2, we have conducted an structure–activity relationship (SAR) analysis through systematic modification of the 5-deazaflavin template. This analysis shows that HDM2-inhibitory activity depends on a combination of factors. The most active compounds (e.g., 15) contain a trifluoromethyl or chloro substituent at the deazaflavin C9 position and this activity depends to a large extent on the presence of at least one additional halogen or methyl substituent of the phenyl group at N10. Our SAR results, in combination with the HDM2 RING domain receptor recognition model we present, form the basis for the design of drug-like and potent activators of p53 for potential cancer therapy

Research data supporting the publication "Under Pressure: Offering Fundamental Insight into Structural Changes on Ball Milling Battery Materials"

Data depository includes the following: Powder X-ray diffraction (PXRD) of the ball-milled Li2MoO4 (at 40Hz and 50Hz, with varying ball size of 7 and 10 mm). PXRD of H-Nb2O5 ball-milled at 40 Hz and 50 Hz (7 mm ball) Electrochemical data of Li2MoO4 and Li2MnO3 (ball-milled samples). TEM of Li2MoO4 and the ball-milled equivalent. Li and Mo NMR of Li2MoO4 and the ball-milled equivalent

The HTA risk analysis chart: visualising the need for and potential value of managed entry agreements in health technology assessment

Background Recent changes to the regulatory landscape of pharmaceuticals may sometimes require reimbursement authorities to issue guidance on technologies that have a less mature evidence base. Decision makers need to be aware of risks associated with such health technology assessment (HTA) decisions and the potential to manage this risk through managed entry agreements (MEAs). Objective This work develops methods for quantifying risk associated with specific MEAs and for clearly communicating this to decision makers. Methods We develop the ‘HTA risk analysis chart’, in which we present the payer strategy and uncertainty burden (P-SUB) as a measure of overall risk. The P-SUB consists of the payer uncertainty burden (PUB), the risk stemming from decision uncertainty as to which is the truly optimal technology from the relevant set of technologies, and the payer strategy burden (PSB), the additional risk of approving a technology that is not expected to be optimal. We demonstrate the approach using three recent technology appraisals from the UK National Institute for Health and Clinical Excellence (NICE), each of which considered a price-based MEA. Results The HTA risk analysis chart was calculated using results from standard probabilistic sensitivity analyses. In all three HTAs, the new interventions were associated with substantial risk as measured by the P-SUB. For one of these technologies, the P-SUB was reduced to zero with the proposed price reduction, making this intervention cost effective with near complete certainty. For the other two, the risk reduced substantially with a much reduced PSB and a slightly increased PUB. Conclusions The HTA risk analysis chart shows the risk that the healthcare payer incurs under unresolved decision uncertainty and when considering recommending a technology that is not expected to be optimal given current evidence. This allows the simultaneous consideration of financial and data-collection MEA schemes in an easily understood format. The use of HTA risk analysis charts will help to ensure that MEAs are considered within a standard utility-maximising health economic decision-making framework

Evidence-based consensus guidelines for the management of catatonia: Recommendations from the British Association for Psychopharmacology

The British Association for Psychopharmacology developed an evidence-based consensus guideline on the management of catatonia. A group of international experts from a wide range of disciplines was assembled. Evidence was gathered from existing systematic reviews and the primary literature. Recommendations were made on the basis of this evidence and were graded in terms of their strength. The guideline initially covers the diagnosis, aetiology, clinical features and descriptive epidemiology of catatonia. Clinical assessments, including history, physical examination and investigations are then considered. Treatment with benzodiazepines, electroconvulsive therapy and other pharmacological and neuromodulatory therapies is covered. Special regard is given to periodic catatonia, malignant catatonia, neuroleptic malignant syndrome and antipsychotic-induced catatonia. There is attention to the needs of particular groups, namely children and adolescents, older adults, women in the perinatal period, people with autism spectrum disorder and those with certain medical conditions. Clinical trials were uncommon, and the recommendations in this guideline are mainly informed by small observational studies, case series and case reports, which highlights the need for randomised controlled trials and prospective cohort studies in this area

Deep hydrous mantle reservoir provides evidence for crustal recycling before 3.3 billion years ago

Water strongly influences the physical properties of the mantle and enhances its ability to melt or convect. Its presence can also be used to trace recycling of surface reservoirs down to the deep mantle1, which makes knowledge of the water content in the Earth's interior and its evolution crucial for understanding global geodynamics. Komatiites (MgO-rich ultramafic magmas) result from a high degree of mantle melting at high pressures2 and thus are excellent probes of the chemical composition and water contents of the deep mantle. An excess of water over elements that show similar geochemical behaviour during mantle melting (for example, cerium) was recently found in melt inclusions in the most magnesium-rich olivine in 2.7-billion-year-old komatiites from Canada3 and Zimbabwe4. These data were taken as evidence for a deep hydrated mantle reservoir, probably the transition zone, in the Neoarchaean era (2.8 to 2.5 billion years ago). Here we confirm the mantle source of this water by measuring deuterium-to-hydrogen ratios in these melt inclusions and present similar data for 3.3-billion-year-old komatiites from the Barberton greenstone belt. From the hydrogen isotope ratios, we show that the mantle sources of these melts contained excess water, which implies that a deep hydrous mantle reservoir has been present in the Earth's interior since at least the Palaeoarchaean era (3.6 to 3.2 billion years ago). The reconstructed initial hydrogen isotope composition of komatiites is more depleted in deuterium than surface reservoirs or typical mantle but resembles that of oceanic crust that was initially altered by seawater and then dehydrated during subduction. Together with an excess of chlorine and depletion of lead in the mantle sources of komatiites, these results indicate that seawater-altered lithosphere recycling into the deep mantle, arguably by subduction, started before 3.3 billion years ago