Electrical investigation of natural lawsonite and application to subduction contexts

Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Solid Earth 142(2), (2019):1430-1442, doi:10.1029/2018JB016899.We report an experimental investigation of the electrical properties of natural polycrystalline lawsonite from Reed Station, CA. Lawsonite represents a particularly efficient water reservoir in subduction contexts, as it can carry about 12 wt % water and is stable over a wide pressure range. Experiments were performed from 300 to about 1325 °C and under pressure from 1 to 10 GPa using a multi‐anvil apparatus. We observe that temperature increases lawsonite conductivity until fluids escape the cell after dehydration occurs. At a fixed temperature of 500 °C, conductivity measurements during compression indicate electrical transitions at about 4.0 and 9.7 GPa that are consistent with crystallographic transitions from orthorhombic C to P and from orthorhombic to monoclinic systems, respectively. Comparison with lawsonite structure studies indicates an insignificant temperature dependence of these crystallographic transitions. We suggest that lawsonite dehydration could contribute to (but not solely explain) high conductivity anomalies observed in the Cascades by releasing aqueous fluid at a depth (~50 km) consistent with the basalt‐eclogite transition. In subduction settings where the incoming plate is older and cooler (e.g., Japan), lawsonite remains stable to great depth. In these cooler settings, lawsonite could represent a vehicle for deep water transport and the subsequent triggering of melt that would appear electrically conductive, though it is difficult to uniquely identify the contributions from lawsonite on field electrical profiles in these more deep‐seated domains.A. P. acknowledges financial support from UCSD‐SIO startup funds, NSF‐EAR Petrology and Geochemistry (grant 1551200), and NSF‐COMPRES IV EOID subaward. The use of the COMPRES Cell Assembly Project was also supported by COMPRES under NSF Cooperative Agreement EAR 1661511. Q. W. acknowledges support from NSF EAR‐1620423. We thank Kurt Leinenweber for fruitful discussion, Jake Perez for technical help in the lab, and Sabine Faulhaber (UCSD Nano‐Engineering Department) for technical assistance with SEM images and EDS analyses. We also thank two reviewers for detailed comments that improved the manuscript. All the electrical data used for Figures 4 and 5 are available in the supporting information.2019-08-2

Pulmonary Function Studies of Healthy Non-smoking Male University Students of Kolkata, India — Revisited

Background: Pulmonary function tests (PFTs) need to be revisited in light of rapid economic growth and industrial development. Questions have been raised about the validity of existing population-specific norms for predicting PFTs, and therefore, the present study aimed to determine the applicability of existing norms for PFTs in young healthy non-smoking male university students of Kolkata. Methods: PFTs were carried out for 87 non-smoking male university students who were randomly sampled from the University of Calcutta, Kolkata, India. Results: The PFTs data obtained in this study did not show a significant variation with that obtained in a previous study. Significant (P < 0.001) differences in the forced expiratory volume in 1 s (FEV1%) and peak expiratory flow rate (PEFR) between the two studies may be attributed to differences in the age and body height, which exhibited significant correlations with the vital capacity (VC), forced vital capacity (FVC), FEV1, FEV1%, and PEFR. Regression equations have been computed to predict PFTs parameters from age and body height. Conclusion: Pulmonary function in the university students of Kolkata was found to have remained mostly unchanged in the last 24 years. The equations computed in this study are considered preferable owing to their substantially smaller standard error of estimate (SEE) than those proposed in the previous study

Factors determining paid and unpaid work in young adults: Evidence from a cohort study in Bihar, India

Early age at entry into the workforce makes it difficult for adolescents to obtain higher education and skills necessary for decent work and a better life. This study examines the factors determining engagement in paid and unpaid work and the age at entry into the workforce among young adults aged 23–27 years in Bihar, India, who were previously interviewed at the age of 15–19 years. The data were derived from the Understanding the Lives of Adolescents and Young Adults (UDAYA) in a sample of 2923 respondents. Young boys had significantly higher work participation than girls. Unmarried boys and girls started doing paid work earlier than married girls. A higher percentage of adolescents from the Scheduled Caste/Scheduled Tribes and Other Backward classes engaged in paid or unpaid work in young adulthood as compared to the General Caste. Children of educated mothers were more likely to delay their entry into the workforce. Adolescents who had attained 10–12 years (0.51, p \u3c 0.01) and 12+ years (0.54, p \u3c 0.01) of schooling until adulthood were less likely to have done paid work in young adulthood as compared to their uneducated counterparts. Young persons who received some vocational training (1.83, p \u3c 0.01) and who had heard of the scheme of employment (1.66, p \u3c 0.01) were more likely to be engaged in paid work. Higher levels of schooling and vocational training had delayed their entry into the workforce

Bullous Henoch–Schonlein purpura with involvement of face

Henoch–Schonlein purpura (HSP) with facial involvement with bullous rashes are extremely rare. A 12-year-old boy presented with abdominal pain and features of arthritis. He also had multiple purpuric rashes over his lower limbs. Gradually, he developed bullous rashes which were seen on his legs and hands and progressed to involve the face. He was confirmed to be suffering from HSP from clinical presentation and skin biopsy. The child responded well to oral steroids. Bullous lesions may be seen in HSP. However, there is neither prognostic significance of this nor does it alter the management. Other causes of bullous lesions should be ruled out. As facial involvement is associated with renal and gastrointestinal involvement, these children should be monitored for sequelae

Breccia-cored columnar rosettes in a rubbly pahoehoe lava flow, Elephanta Island, Deccan Traps, and a model for their origin

Rubbly pahoehoe lava flows are abundant in many continental flood basalts including the Deccan Traps. However, structures with radial joint columns surrounding cores of flow-top breccia (FTB), reported from some Deccan rubbly pahoehoe flows, are yet unknown from other basaltic provinces. A previous study of these Deccan “breccia-cored columnar rosettes” ruled out explanations such as volcanic vents and lava tubes, and showed that the radial joint columns had grown outwards from cold FTB inclusions incorporated into the hot molten interiors. How the highly vesicular (thus low-density) FTB blocks might have sunk into the flow interiors has remained a puzzle. Here we describe a new example of a Deccan rubbly pahoehoe flow with FTB-cored rosettes, from Elephanta Island in the Mumbai harbor. Noting that (1) thick rubbly pahoehoe flows probably form by rapid inflation (involving many lava injections into a largely molten advancing flow), and (2) such flows are transitional to ‘a’ā flows (which continuously shed their top clinker in front of them as they advance), we propose a model for the FTB-cored rosettes. We suggest that the Deccan flows under study were shedding some of their FTB in front of them as they advanced and, with high-eruption rate lava injection and inflation, frontal breakouts would incorporate this FTB rubble, with thickening of the flow carrying the rubble into the flow interior. This implies that, far from sinking into the molten interior, the FTB blocks may have been rising, until lava supply and inflation stopped, the flow began solidifying, and joint columns developed outward from each cold FTB inclusion as already inferred, forming the FTB-cored rosettes. Those rubbly pahoehoe flows which began recycling most of their FTB became the ‘a’ā flows of the Deccan

Heat transfer from a hot moving steel plate by using Cu-Al layered double hydroxide nanofluid based air atomized spray

<p>The current research is focused on the cooling of a hot moving steel plate by using air atomized spray cooling technique. A new type of coolant, Cu-Al LDH nanofluid, has been prepared and used for heat flux removal. Preparation method of nanofluid and its characteristics has been reported. The cooling effectiveness is reported in terms of cooling rate by varying the concentration of nanofluid in five levels. The results indicate that the cooling rate increases at very low concentration of LDH with respect to base fluid. However, beyond a certain concentration a decreasing trend of cooling rate has been observed.</p> <p><b>Abbreviations:</b> CHF: Critical heat flux; HTC: Heat transfer coefficients; LDH:Layered double hydroxide; TEM: Transmission electron microscopy.</p

Developing groundwater potentiality models by coupling ensemble machine learning algorithms and statistical techniques for sustainable groundwater management

The present study intends to construct a logistic regression based hybrid EML model by considering nine standalone and ensemble machine learning (EML) algorithms as parameters for groundwater potentiality mapping (GPM) in the Teesta River basin of Bangladesh, including random forest (RF), M5P, artificial neural network (ANN), random subspace (RS), dagging, bagging, random tree, support vector machine (SVM), and REPTree. The GPM were then validated using the receiver operating characteristics (ROC) curve. To investigate the effect of the parameters for GPM, we used classification and regression tree (CART) and RF based sensitivity analysis. The very high (831-1200km2) and high groundwater potential areas (521-680km2), were predicted using nine EML algorithms and one hybrid model. The REPTree (AUC-0.893) model outperformed other nine models based on ROC's area under curve (AUC). Furthermore, the LR algorithm-based hybrid EML model outperformed the REPTree model in terms of precision (AUC: 0.933)