Biogeochemistry of Himalayan rivers as an agent of climate change

Uplift of the Himalaya, intensification of the Asian monsoon and increased erosion from the Himalayan orogen are all intimately coupled and reflected in the transport of weathering products to the ocean by the large rivers, namely the Indus, Ganga, Brahmaputra, Mekong, Chang Jiang and Irrawady1-6. In recent years, several studies have focused on the coupling between continental weathering rates and changes in atmospheric CO2 budget. Because the atmospheric CO2 reservoir is relatively small and CO2 gets converted to bicarbonate anion (HCO3-) and is balanced by dissolved cations from the silicate/carbonate rocks; it is likely that this reservoir is sensitive to changes induced by chemical weathering rates. In such a scenario, increased chemical weathering and associated CO2 consumption rates in the Himalayan rivers could alter the atmospheric CO2 levels and hence the global climate. Both oceanic and terrestrial evidence points to a marked, progressive period of intense cooling of global climate over the geologic past. Existing-models of the global CO2 cycle do not include detailed consideration of such tectonically-driven enhanced chemical weathering. The purpose of this paper is to evaluate the present-day CO2 consumption rates by chemical weathering processes in the Himalaya, based on newer data6, and their implications to long-term climate change

Distribution of rare earth elements in the Yamuna and the chambal rivers, India

We report here the first measurements of dissolved rare earth elements (REE) in the headwaters of the Yamuna river draining through the southern slopes of Himalaya. Due to intense weathering of the surface rocks of different lithologies and influence of tributaries, Yamuna river waters have variable dissolved REE contents (87 < ΣREE < 1374 ng L-1, mean = 288.6 ng L-1) and exhibit negative Eu anomaly (0.49 < Eu/Eu < 0.73, mean = 0.63). While most of the samples do not show discernable Ce anomalies; a negative Ce anomaly, however, found in a few of them, which can be explained by the colloidal pool preferentially enriched in Ce. A comparison among the river waters and bed sediments suggests that dissolved composition of REE is strongly fractionated and is enriched in MREE (Nd-Gd) with respect to sediments; presumably due to preferential dissolution of phosphate minerals such as apatite during weathering processes. Along with the Yamuna river, bed sediments from the Chambal river (a Peninsular river) have also been analyzed for REE composition. Bed sediments in the Yamuna and the Chambal river basins are characterized by ΣREE concentrations in the range of 78 to 291 µg g-1 (mean = 165 µg g-1) and 96 to 157 µg g-1 (mean = 134 µg g-1), respectively. A characteristic feature observed in the REE-normalized patterns of bed sediments is a strong HREE enrichment and a relatively positive Eu anomaly with respect to the granites in the Yamuna river catchment. In contrast, the bed sediment samples of the Chambal river show significant LREE enrichment and Eu enrichment with respect to the Deccan basalts in its catchment. The feldspars and their secondary products, which are enriched in Eu, might be the cause of the Eu anomaly. In river sediments of both these basins, the enrichment factors (EF), with respect to PAAS are ≤2 suggesting that REE composition is mainly derived from weathering processes

Systematic review: combination therapies for treatment-naïve chronic hepatitis B

Background: There is a renewed interest in use of combination therapies in treatment-naïve chronic hepatitis B (CHB) because of limitations of monotherapies. Aim: To discuss the current status of combination therapies in treatment-naive CHB. Methods PubMed search was done using 'combination', 'sequential' and 'chronic hepatitis B' as the search terms. Results: The two most popular combination therapies include 'combination of nucleos(t)ide analogues' and 'combination of interferons and nucleos(t)ide analogues'. Combination therapies using two nucleos(t)ide analogues do not lead to higher long-term efficacy. However, addition of a nucleos(t)ide analogue with a good resistance profile to a nucleos(t)ide analogue with a lower genetic barrier to resistance decreases the risk of emergent resistance to the latter. Greater sustained virological, biochemical and seroconversion rates are observed with addition of lamivudine to conventional interferon, but pegylated-interferon monotherapy is equally effective as combination with lamivudine. Again, resistance to lamivudine is lower with its combination with interferons. Conclusions: The answer to the question whether hepatitis B can be treated better with combination or monotherapy remains largely unknown. Additional trials are warranted of combination therapies of peginterferon and potent nucleos(t)ide analogues or therapies with the combined use of nucleos(t)ide analogues or immunomodulators

Long-term record of aerosol optical properties and chemical composition from a high-altitude site (Manora Peak) in Central Himalaya

A long-term study, conducted from February 2005 to July 2008, involving chemical composition and optical properties of ambient aerosols from a high-altitude site (Manora Peak: 29.4°N, 79.5°E, ~1950ma.s.l.) in the central Himalaya is reported here. The total suspended particulate (TSP) mass concentration varied from 13 to 272 µgm.3 over a span of 42 months. Aerosol optical depth (AOD) and TSP increase significantly during the summer (April-June) due to increase in the concentration of mineral dust associated with the long-range transport from desert regions (from the middle-East and Thar Desert in western India). The seasonal variability in the carbonaceous species (EC, OC) is also significantly pronounced, with lower concentrations during the summer and monsoon (July-August) and relatively high during the post-monsoon (September-November) and winter (December-March). On average, total carbonaceous aerosols (TCA) and water-soluble inorganic species (WSIS) contribute nearly 25 and 10% of the TSP mass, respectively. The WSOC/OC ratios range from 0.36 to 0.83 (average: 0.55±0.15), compared to lower ratios in the Indo-Gangetic Plain (range: 0.35-0.40), and provide evidence for the enhanced contribution from secondary organic aerosols. The mass fraction of absorbing EC ranged from less than a percent (during the summer) to as high as 7.6% (during the winter) and absorption coefficient (babs, at 678 nm) varied between 0.9 to 33.9Mm-1 (1Mm-1=10-6 m-1). A significant linear relationship between babs and EC (µgCm-3) yields a slope of 12.2 (±2.3) m2 g-1, which is used as a measure of the mass absorption efficiency (σabs) of EC

Health problems in geriatric population of age group ≥70 years in rural Kerala, India: a cross sectional study

Background: The proportion of elderly population is increasing considerably world over. The health and socio-economic issues of this section is to be considered separately and in depth insights about them is needed for formulating elderly friendly health policy. This study intends toidentify the important health concerns of elderly population above the age group of 70 years in a rural area in North Kerala, India.Methods: It is a community based cross-sectional descriptive study involving all individuals above the age group of 70 years in a randomly selected panchayath ward from rural North Kerala. The data regarding demography, socioeconomic aspects, medical history, access to health care and treatment of chronic illnesses were collected through interview of study participants by a trained health care volunteer using a pre-validated questionnaire.Results: A total of 93 individuals above the age group of 70 years were included in the study out of which 63% were females and 37% males. In the study population 55.9% of the elderly were widowed and 87.1 % were staying along with their children. Almost 75% of the elderly received social welfare pension from government agencies and 14.3% received service pensions. 67.74% of the study population were hypertensive and 35.56% were diabetic. Other health issues included arthritis, coronary artery disease, chronic kidney disease, genito urinary symptoms and cerebrovascular accident.Conclusion:  The study provide valuable insights into the health and social issues of elderly in Kerala and points to the importance of formulating an elderly friendly health policy in the state

A Generalized Semi-Analytic Model for Magnetar-Driven Supernovae

Several types of energetic supernovae, such as superluminous supernovae (SLSNe) and broad-line Ic supernovae (Ic-BL SNe), could be powered by the spin-down of a rapidly rotating magnetar. Currently, most models used to infer the parameters for potential magnetar-driven supernovae make several unsuitable assumptions that likely bias the estimated parameters. In this work, we present a new model for magnetar-driven supernovae that relaxes several of these assumptions and an inference workflow that enables accurate estimation of parameters from lightcurves of magnetar-driven supernovae. In particular, in this model, we include the dynamical evolution of the ejecta, coupling it to the energy injected by the magnetar itself while also allowing for non-dipole spin down. We show that the model can reproduce SLSN and Ic-BL SN light curves consistent with the parameter space from computationally expensive numerical models. We also show the results of parameter inference on four well-known example supernovae, demonstrating the model's effectiveness at capturing the considerable diversity in magnetar-driven supernova lightcurves. The model fits each light curve well and recovers parameters broadly consistent with previous works. This model will allow us to explore the full diversity of magnetar-driven supernovae under one theoretical framework, more accurately characterize these supernovae from only photometric data, and make more accurate predictions of future multiwavelength emission to test the magnetar-driven scenario better.Comment: 16 pages, 12 pages including appendices. Submitted to MNRAS. Comments welcome. Model available in public code Redback: https://github.com/nikhil-sarin/redbac

Chemical characteristics of aerosols in MABL of bay of Bengal and Arabian sea during spring inter-monsoon: a comparative study

The chemical composition of aerosols in the Marine Atmospheric Boundary Layer (MABL) of Bay of Bengal (BoB) and Arabian Sea (AS) has been studied during the spring and inter-monsoon (March-May 2006) based on the analysis of water soluble constituents (Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO3- and SO42-), crustal elements (Al, Fe, and Ca) and carbonaceous species (EC, OC). The total suspended particulates (TSP) ranged from 5.2 to 46.6 μg m-3 and 8.2 to 46.9 μg m-3 during the sampling transects in the BoB and AS respectively. The water-soluble species, on average, accounted for 44% and 33% of TSP over BoB and AS respectively, with dominant contribution of SO42- over both the oceanic regions. However, distinct differences with respect to elevated abundances of NH4+ in the MABL of BoB and that of Na+ and Ca2+ in AS are clearly evident. The non-sea-salt component of SO42- ranging from 82 to 98% over BoB and 35 to 98% over AS; together with nss-Ca2+/nss-SO42- equivalent ratios 0.12 to 0.5 and 0.2 to 1.16, respectively, provide evidence for the predominance of anthropogenic constituents and chemical transformation processes occurring within MABL. The concentrations of OC and EC average around 1.9 and 0.4 μg m-3 in BoB and exhibit a decreasing trend from north to south; however, abundance of these carbonaceous species are not significantly pronounced over AS. The abundance of Al, used as a proxy for mineral aerosols, varied from 0.2 to 1.9 μg m-3 over BoB and AS, with a distinctly different spatial pattern - decreasing north to south in BoB in contrast to an increasing pattern in the Arabian Sea

A methodology for solving single-model, stochastic assembly line balancing problem

Cataloged from PDF version of article.In this paper, a methodology is developed to solve the single-model, stochastic assembly line balancing problem for the objective of minimizing the total labor cost and the expected incompletion cost arising from tasks not completed within the prescribed cycle time. The methodology is based on determining an initial DP based solution and its improvement using a branch-and-bound procedure which uses an approximate solution instead of a lower bound for fathoming nodes. Detailed experimentation shows the superiority of this method over the most promising one from the literature. # 1999 Elsevier Science Ltd. All rights reserved

Mixing in the surface waters of the western Bay of Bengal using 228Ra and 226Ra

228Ra and 226Ra have been measured in the surface waters of the western Bay of Bengal during five cruises conducted between 1988 and 1999. The ranges and mean (given in brackets) concentrations for 228Ra and 226Ra are 6.8-42.1 (17.8 ± 7.9) dpm/100 kg and 6.0-16.7 (9.2 ± 2.2) dpm/ 100 kg, respectively. (228Ra/226Ra) Activity Ratio (henceforth denoted as [228/226]) ranges from 0.8 to 3.4 with a mean of 1.9 ± 0.5. Both 228Ra and 226Ra show inverse correlation with salinity, the former much stronger. A surface 2-D diffusion-advection model is used with a new approach. A simple bivariate function, C(x,y) = C0e-Ax·e-By where C0, A and B are constants, is fitted to the whole 228Ra and 226Ra data C(x,y). Substituting C(x,y) in the two-dimensional steady-state diffusion equation of Ra, the estimated values of the constants A and B can be related to eddy diffusivities and advection velocities in the zonal (x) and meridional (y) directions. From this relationship, the horizontal eddy diffusivities in the zonal and meridional directions are inferred to be 1.3 × 107 and 2.1 × 108 cm2s-1, respectively in the absence of advection terms. Similarly, neglecting the influence of diffusion, one can estimate the advection velocities, wx and wy in the zonal and meridional directions, as 0.2 and 1.1 cm s-1, respectively. The model-fit values C(x,y) of 228Ra concentrations are in good agreement with the measured values except in regions showing exceptionally high and low values. Incorporating both the advection rates and eddy diffusivities into the equation, it is found that increasing advection velocities depending on the direction can decrease or increase the eddy diffusivities and that such changes are more effective in the meridional direction compared to zonal direction in the region of study. On the whole, 228Ra appears a good tracer to derive rates of mixing between low salinity waters in the north and their high salinity southern counterparts of the western Bay of Bengal. The eddy diffusivities, Kx and Ky (without advection) derived for the Bay of Bengal are higher by about an order of magnitude than the ones similarly obtained for the Arabian Sea. This is not unexpected due to the turbulent conditions prevailing in the Bay of Bengal for most of the year