Water Content of Earth's Continental Mantle Is Controlled by the Circulation of Fluids or Melts

A key mission of the ARES Directorate at JSC is to constrain models of the formation and geological history of terrestrial planets. Water is a crucial parameter to be measured with the aim to determine its amount and distribution in the interior of Earth, Mars, and the Moon. Most of that "water" is not liquid water per se, but rather hydrogen dissolved as a trace element in the minerals of the rocks at depth. Even so, the middle layer of differentiated planets, the mantle, occupies such a large volume and mass of each planet that when it is added at the planetary scale, oceans worth of water could be stored in its interior. The mantle is where magmas originate. Moreover, on Earth, the mantle is where the boundary between tectonic plates and the underlying asthenosphere is located. Even if mantle rocks in Earth typically contain less than 200 ppm H2O, such small quantities have tremendous influence on how easily they melt (i.e., the more water there is, the more magma is produced) and deform (the more water there is, the less viscous they are). These two properties alone emphasize that to understand the distribution of volcanism and the mechanism of plate tectonics, the water content of the mantle must be determined - Earth being a template to which all other terrestrial planets can be compared

Metasomatic Control of Water in Garnet and Pyroxene from Kaapvaal Craton Mantle Xenoliths

Fourier transform infrared spectrometry (FTIR) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) were used to determine water, rare earth (REE), lithophile (LILE), and high field strength (HFSE) element contents in garnet and pyroxene from mantle xenoliths, Kaapvaal craton, southern Africa. Water enters these nominally anhydrous minerals as protons bonded to structural oxygen in lattice defects. Pyroxene water contents (150-400 ppm in clinopyroxene; 40-250 ppm in orthopyroxene) correlate with their Al, Fe, Ca and Na and are homogeneous within a mineral grains and a xenolith. Garnets from Jagersfontein are chemically zoned for Cr, Ca, Ti and water contents. Garnets contain 0 to 20 ppm H2 Despite the fast diffusion rate of H in mantle m inerals, the observations above indicate that the water contents of mantle xenolith minerals were not disturbed during kimberlite entrainment and that the measured water data represent mantle values. Trace elements in all minerals show various degrees of light REE and LILE enrichments indicative of minimal to strong metasomatism. Water contents of peridotite minerals from the Kaapvaal lithosphere are not related to the degree of depletion of the peridotites. Instead, metasomatism exerts a clear control on the amount of water of mantle minerals. Xenoliths from each location record specific types of metasomatism with different outcomes for the water contents of mantle minerals. At pressures . 5.5 GPa, highly alkaline melts metasomatized Liqhobong and Kimberley peridotites, and increased the water contents of their olivine, pyroxenes and garnet. At higher pressures, the circulation of ultramafic melts reacting with peridotite resulted in co-variation of Ca, Ti and water at the edge of garnets at Jagersfontein, overall decreasing their water content, and lowered the water content of olivines at Finsch Mine. The calculated water content of these melts varies depending on whether the water content of the peridotite (2 wt% HO. 2O) or individual m inerals (<0.5-13 wt% H2O) are used, and also depend on the mineral-melt water partition coefficients. These metasomatic events are thought to have occurred during the Archean and Proterozoic, meaning that the water contents measured here have been preserved since that time and can be used to investigate viscocity and longevity of cratonic mantle roots

Effect of Sitting Posture on Development of Scoliosis in Duchenne Muscular Dystrophy Cases

Background: Scoliosis is a frequent association in boys with Duchenne Muscular Dystrophy when the ability to walk is lost around nine to 12 years of age. This study assessed the contribution of physical factors including lumbar posture to scoliosis in non-ambulatory youth with DMD in Nepal. Methods: Linear regression was used to assess effects of time since loss of ambulation, muscle strength, functional severity and lumbar angle as a binary variable on coronal Cobb angle; again logistic regression was used to assess effects of muscle strength and cross-legged sitting on the presence of a lordotic lumbar posture in 22 non-ambulant boys and young men. Results: The boys and young men had a mean (SD) age of 15.1 (4.0) years, had been non-ambulant for 48.6 (33.8) months and used a median of 3.5 (range 2 to 7) postures a day. The mean Cobb angle was 15.1 (range 0 to 70) degrees. Optimal accuracy in predicting scoliosis was obtained with a lumbar angle of -6° as measured by skin markers, and both a lumbar angle ≤-6° (P=0.112) and better functional ability (P=0.102) were associated with less scoliosis. Use of cross-legged sitting postures during the day was associated with a lumbar angle ≤-6° (OR 0.061; 95% CI 0.005 - 0.672; P=0.022). Conclusions: Use of cross-legged sitting posture was associated with increase in lumbar lordosis. Higher angle of lumbar lordosis and better functional ability are associated with lesser degree of scoliosis

Long-term survival in multiple myeloma is associated with a distinct immunological profile, which includes proliferative cytotoxic T-cell clones and a favourable Treg/Th17 balance

Despite improved outcomes in multiple myeloma (MM), a cure remains elusive. However, even before the current therapeutic era, 5% of patients survived >10 years and we propose that immune factors contribute to this longer survival. We identified patient

Multiple myeloma causes clonal T-cell immunosenescence: Identification of potential novel targets for promoting tumour immunity and implications for checkpoint blockade

© 2016 Macmillan Publishers Limited. Tumour-induced dysfunction of cytotoxic T cells in patients with multiple myeloma (MM) may contribute to immune escape and be responsible for the lack of therapeutic efficacy of immune checkpoint blockade. We therefore investigated dysfunctional clonal T cells in MM and demonstrated immunosenescence but not exhaustion as a predominant feature. T-cell clones were detected in 75% of MM patients and their prognostic significance was revalidated in a new post-immunomodulatory drug cohort. The cells exhibited a senescent secretory effector phenotype: KLRG-1+/CD57+/CD160+/CD28-. Normal-for-age telomere lengths indicate that senescence is telomere independent and potentially reversible. p38-mitogen-activated protein kinase, p16 and p21 signalling pathways known to induce senescence were not elevated. Telomerase activity was found to be elevated and this may explain how normal telomere lengths are maintained in senescent cells. T-cell receptor signalling checkpoints were normal but elevated SMAD levels associated with T-cell inactivation were detected and may provide a potential target for the reversal of clonal T-cell dysfunction in MM. Low programmed death 1 and cytotoxic T-lymphocyte-associated antigen 4 expression detected on T-cell clones infers that these cells are not exhausted but suggests that there would be a suboptimal response to immune checkpoint blockade in MM. Our data suggest that other immunostimulatory strategies are required in MM

Smelting conditions and smelting products: Experimental insights into the development of iron bloomery furnaces

The material record for bloomery furnaces in Iron Age and Roman Britain is fragmentary and, because of this paucity of evidence, the reconstruction of the ceramic structures used in iron production is difficult. Experiments have nevertheless been carried out to explore the working parameters and efficiency of iron smelting in bowl furnaces (small structures with little structure above ground level, interior measuring about 30 cm in height) (Craddock, 1995; Girbal, 2013) and shaft furnaces (height c.1m) (Smith, 2013; Crew, 2013; Doonan and Dungworth, 2013; Tylecote and Merkel, 1985; Tylecote and Wynne, 1958). These experiments aimed to clarify which furnace is more efficient for iron smelting and therefore what method was most likely used in Iron Age and Roman Britain. It is theorised that iron smelting furnaces developed from bowl structures to shaft structures over time, as smelters sought furnaces which could reach higher temperatures and create more reducing atmospheres (Dungworth 2013; Tylecote and Merkel, 1985; Tylecote and Wynne, 1958). These experiments suggest that the shaft furnace was used as it could meet these requirements. This study looks at the working conditions of a shaft furnace at an intermediary height - between that of a bowl furnace and of a shaft furnace - in order to understand its working parameters and to consequently better understand the progression from a bowl to a 1m high shaft structure

Vertical zonation of testate amoebae in the Elatia Mires, northern Greece : palaeoecological evidence for a wetland response to recent climate change or autogenic processes?

The Elatia Mires of northern Greece are unique ecosystems of high conservation value. The mires are climatically marginal and may be sensitive to changing hydroclimate, while northern Greece has experienced a significant increase in aridity since the late twentieth century. To investigate the impact of recent climatic change on the hydrology of the mires, the palaeoecological record was investigated from three near-surface monoliths extracted from two sites. Testate amoebae were analysed as sensitive indicators of hydrology. Results were interpreted using transfer function models to provide quantitative reconstructions of changing water table depth and pH. AMS radiocarbon dates and 210Pb suggest the peats were deposited within the last c. 50 years, but do not allow a secure chronology to be established. Results from all three profiles show a distinct shift towards a more xerophilic community particularly noted by increases in Euglypha species. Transfer function results infer a distinct lowering of water tables in this period. A hydrological response to recent climate change is a tenable hypothesis to explain this change; however other possible explanations include selective test decay, vertical zonation of living amoebae, ombrotrophication and local hydrological change. It is suggested that a peatland response to climatic change is the most probable hypothesis, showing the sensitivity of marginal peatlands to recent climatic change