Dileep Kumar | Koneru Lakshmaiah (original) (raw)
Papers by Dileep Kumar
Environmental Monitoring and Assessment, 2006
Peri-urban lands are often used for production of vegetables for better market accessibility and ... more Peri-urban lands are often used for production of vegetables for better market accessibility and higher prices. But most of these lands are contaminated with heavy metals through industrial effluents, sewage and sludge, and vehicular emission. Vegetables grown in such lands, therefore, are likely to be contaminated with heavy metals and unsafe for consumption. Samples of vegetables i.e., spinach (Spinacia oleracea L.) and okra (Abelmoschus esculentus L.); soil and irrigation water were collected from 5 peri-urban sites of New Delhi to monitor their heavy metal loads. While heavy metal load of the soils were below the maximum allowable limit prescribed by the World Health Organization (WHO), it was higher in irrigation water and vegetable samples. The spinach and okra samples showed Zn, Pb and Cd levels higher than the WHO limits. The levels of Cu, however, were at their safe limits. Metal contamination was higher in spinach than in okra. Spatial variability of metal contamination was also observed in the study. Bio-availability of metals present in soil showed a positive relationship with their total content and organic matter content of soil but no relationship was observed with soil pH. Washing of vegetables with clean water was a very effective and easy way of decontaminating the metal pollution as it reduced the contamination by 75 to 100%.
European Journal of Pharmacology, 2002
pH regulates various cellular functions. Previously, we have described that acidic pH produces de... more pH regulates various cellular functions. Previously, we have described that acidic pH produces depolarization and contraction in isolated aorta from spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats [Br. J. Pharmacol. 118 (1996) 485]. The aim of the present study was to investigate the involvement of Cl À channels in acidic pH-induced contraction. Changing the pH of the bathing solution from 7.4 to 6.5 induced a contraction in both SHR and WKY aorta, which was 127.50 F 13.32% and 79.27 F 0.94% of the 64.8 mM KCl-induced contraction, respectively. The acidic pH-induced contraction was partially inhibited by the voltage-dependent Ca 2 + channel (VDCC) blockers, verapamil (1 AM) and nifedipine (0.1 AM). The Cl À channel inhibitors, diisothiocyanatostilbene-2,2V-disulfonic acid (DIDS) (0.5 mM), 9-anthracene chloride (0.5 mM), indanyloxyacetic acid (30 AM) and niflumic acid (3 AM) also inhibited the acidic pH-induced contraction and the degree of attenuation was comparable to that of VDCC blockers. DIDS, 9-anthracene chloride and niflumic acid at concentrations used to inhibit the acidic pH-induced contraction also inhibited the 10 AM phenylephrine-induced contraction partially, without affecting the 64.8 mM KCl-induced contraction, whereas both the contractions were inhibited by indanyloxyacetic acid with equal efficacy. Indanyloxyacetic acid but not DIDS, 9-anthracene chloride or niflumic acid inhibited the 24.8 mM KCl-induced contraction. Simultaneous measurement of cytosolic Ca 2 + and tension showed that niflumic acid reversed the increase in intracellular Ca 2 + level and inhibited the contraction caused by acidic pH. Similarly, acidic pH depolarized the cultured vascular smooth muscle cells from SHR and the depolarization was completely reversible after the administration of niflumic acid. All these results suggest that the activation of Cl À channels is an important mechanism underlying the depolarization and contraction induced by acidic pH in SHR and WKY aortas. D
Controls of dimethyl sulphide in the Bay of Bengal during BOBMEX-Pilot cruise 1998
Journal of Earth System Science, 2000
The air-sea exchange is one of the main mechanisms maintaining the abundances of trace gases in t... more The air-sea exchange is one of the main mechanisms maintaining the abundances of trace gases in the atmosphere. Some of these, such as carbon dioxide and dimethyl sulphide (DMS), will have a bearing on the atmospheric heat budget. While the former facilitates the trapping of radiation (greenhouse effect) the latter works in the opposite direction through reflectance of radiation back into space by sulphate aerosols that form from oxidation of DMS in atmosphere. Here we report on the first measurements made on DMS in the Bay of Bengal and the factors regulating its abundance in seawater. Phytoplankton alone does not seem to control the extent of DMS concentrations. We find that changes in salinity could effectively regulate the extent of DMSP production by marine phytoplankton. In addition, we provide the first ever evidence to the occurrence of DMS precursor, DMSP, in marine aerosols collected in the boundary layer. This suggests that the marine aerosol transport of DMSP will supplement DMS gaseous evasion in maintaining the atmospheric non-sea salt sulphur budget.
Atmospheric Environment, 2006
This paper presents information on concentrations, size distributions, geographical distributions... more This paper presents information on concentrations, size distributions, geographical distributions and sources of water-soluble organic nitrogen (ON ws ) in aerosols over the East China Sea and western North Pacific to understand its impact on the atmospheric processes and the oceanic ecosystems in the autumn and spring in the East Asian region. Results revealed ON ws contributions to the total nitrogen in aerosols to be ~ 24% and ~ 10% over the East China Sea in the autumn and the spring, respectively. The particulate ON ws mainly existed in fine sized particles. Gas to particle conversion may be the major formation process for ON ws . Occurrence of particulate ON ws in both fine and coarse modes during the Kosa event suggests gaseous ON adsorption and/ or adhesion to the coarse mode mineral.
Unsupervised segmentation of textured color images using Markov random field models
An unsupervised segmentation algorithm which uses Markov random fields for modeling color texture... more An unsupervised segmentation algorithm which uses Markov random fields for modeling color texture is presented. These models characterize a texture in terms of spatial interaction within each color plane and interaction among different color planes. These models are used for segmentation in conjunction with an agglomerative clustering procedure that at each step minimizes a global performance functional based on the
Current knowledge on the distribution of arsenic in groundwater in five states of India
Journal of Environmental Science and Health Part A-toxic/hazardous Substances & Environmental Engineering, 2007
Testing of groundwater used for drinking for arsenic has been undertaken more widely by state gov... more Testing of groundwater used for drinking for arsenic has been undertaken more widely by state governments in several states of India in recent years with the support of UNICEF. Available data for five states are collated in this paper and this provides the most up-to-date picture of areas known to be affected by arsenic in groundwater in the Indian portion of the Ganges-Brahmaputra river basin. In West Bengal, water from 132,262 government installed handpumps in 8 districts has been tested and overall 25.5% of samples were found to contain arsenic at concentrations greater than 50 μ gL−1 and 57.9% at concentrations greater than 10 μ gL−1. On the banks of the Brahmaputra in Assam, to date, samples from 5,729 government handpump sources in 22 districts have been tested for arsenic. Overall, samples from 6.3% of sources were found to contain arsenic at concentrations greater than 50 μ gL−1 and 26.1% at concentrations greater than 10 μ gL−1. In Bihar, on the River Ganges upstream of West Bengal, 66,623 sources from 11 districts have been tested and water samples from 10.8% of sources were found to contain arsenic at concentrations greater than 50 μ gL−1 and 28.9% at concentrations greater than 10 μ gL−1. Upstream of Bihar in Uttar Pradesh, home of the Taj Mahal, to date water samples from 20,126 government-installed handpump sources have been tested. As a result 2.4% of the samples tested were found to contain arsenic at concentrations greater than 50 μ gL−1 and 21.5% at concentrations greater than 10 μ gL−1. Finally in one district of Jharkhand, lying on the Ganges alluvial plain between Bihar and West Bengal, 9,007 sources have been tested and water samples from 3.7% of sources were found to contain arsenic at concentrations greater than 50 μ gL−1 and 7.5% at concentrations greater than 10 μ gL−1. State governments have adopted different sampling strategies and these are described in this paper. Testing is ongoing in several states and the complete picture is yet to emerge in some areas.
Amyloid plaque imaging agent [C-11]-6-OH-BTA-1: biodistribution and radiation dosimetry in baboon
Nuclear Medicine Communications, 2005
The amyloid neuritic plaque is considered to be a toxic collection of amyloid-ss protein found in... more The amyloid neuritic plaque is considered to be a toxic collection of amyloid-ss protein found in brain tissue in Alzheimer's disease. A neutral analogue of the amyloid-binding thioflavin-T (BTA), has been radiolabeled as [C-11]-6-OH-BTA-1. It crosses the blood brain barrier, and is a promising tracer for imaging plaques in vivo using positron emission tomography. We now report the biodistribution and dosimetry of [C-11]-6-OH-BTA-1 in baboons. Four 2-hour whole body studies were acquired in an ECAT ACCEL camera in two baboons after the bolus injection of [C-11]-6-OH-BTA-1. After 3.5 minute transmission scans performed per bed position prior to injection, emission scans were collected in 2-D mode over five bed positions. Regions of interest (ROI) were drawn around the brain, left and right lungs, heart, liver, gall bladder, left and right kidneys, spleen and urinary bladder. Since no fluid was removed from the baboons, total body radioactivity was calculated using the injected dose and a calibration factor determined from a cylinder phantom. The area under the curve (AUC) for each ROI was determined by trapezoidal integration of the first few points with subsequent points fit by a decreasing monoexponential. The AUC was then divided by counts in the total body, and resulting residence times were entered into the MIRDOSE3 program. The animals tolerated the procedure well. The ligand was eliminated via the hepatobiliary and renal systems. In the adult male and female reference the gallbladder received the highest estimated radiation dose and was the critical organ (3.9E-02 mGy/MBq and 4.3E-02 mGy/MBq respectively). In the United States, the absorbed dose to the gallbladder would limit [C-11]-6-OH-BTA-1 administered with the approval of a Radioactive Drug Research Committee (RDRC) to a single injection of 1295 MBq (35 mCi) in the adult male, and 1314 MBq (35 mCi) in the adult female.
Deep-sea Research Part Ii-topical Studies in Oceanography, 2001
Time-series observations at a nominally "xed location in the northern Arabian Sea (213N, 643E) du... more Time-series observations at a nominally "xed location in the northern Arabian Sea (213N, 643E) during the Northeast Monsoon (winter, February) of l997 showed the prevalence of cold sea-surface temperatures (SST) and deep mixed layers resulting from winter cooling and convection. The covariation of nitrate concentrations in the surface layers and concentrations of chlorophyll a and primary production in the euphotic zone with mixed-layer depth (MLD) and wind suggests that carbon "xation was controlled primarily by physical forcing. Cooler waters during winter 1997 relative to winter 1995 were associated with deeper MLDs, higher nitrate concentrations, elevated primary productivity, and higher chlorophyll a concentrations, leading to the inference that even a 13C decrease in SST could lead to signi"cantly higher primary productivity. Satellite data on sea surface temperature (advanced very high-resolution radiometer; AVHRR) and TOPEX/POSEl-DON altimeter data suggest that this interannual variation is of basin-wide spatial scale. After the termination of winter cooling and subsequent warming during the Spring Intermonsoon, the Arabian Sea has low primary production. During the latter period, micro-organisms, i.e. heterotrophic bacteria and microzooplankton)-proliferate, a feeding mode through the microbial loop that appears to be inherent to mesozooplankton for sustaining their biomass throughout the year in this region.
Journal of Earth System Science, 2003
The 26th January 2001 Bhuj earthquake occurred in the Kachchh Rift Basin which has a long history... more The 26th January 2001 Bhuj earthquake occurred in the Kachchh Rift Basin which has a long history of major earthquakes. Great Triangulation Survey points (GTS) were first installed in the area in 1856–60 and some of these were measured using Global Positioning System (GPS) in the months of February and July 2001. Despite uncertainties associated with repairs and possible reconstruction of points in the past century, the re-measurements reveal pre-seismic, co-seismic and post-seismic deformation related to Bhuj earthquake. More than 25 Μ-strain contraction north of the epicenter appears to have occurred in the past 140 years corresponding to a linear convergence rate of approximately 10 mm/yr across the Rann of Kachchh. Motion of a single point at Jamnagar 150 km south of the epicenter in the 4 years prior to the earthquake, and GTS-GPS displacements in Kathiawar suggests that pre-seismic strain south of the epicenter was small and differs insignificantly from that measured elsewhere in India. Of the 20 points measured within 150 km of the epicenter, 12 were made at existing GTS points which revealed epicentral displacements of up to 1 m, and strain changes exceeding 30 Μ-strain. Observed displacements are consistent with reverse co-seismic slip. Re-measurements in July 2001 of one GTS point (Hathria) and eight new points established in February reveal post-seismic deformation consistent with continued slip on the Bhuj rupture zone.
Journal of Pharmacology and Experimental Therapeutics, 2002
Acidic pH induced a contraction (APIC) in isolated aortas from spontaneously hypertensive (SHR) a... more Acidic pH induced a contraction (APIC) in isolated aortas from spontaneously hypertensive (SHR) and Wistar Kyoto rats, but failed to produce any response in age-matched Wistar rat aorta. This study was conducted to test the hypothesis that tyrosine phosphorylation of proteins is a molecular mechanism underlying the APIC. Tyrosine kinase inhibitors, genistein and tyrphostin 23 inhibited the APIC in a concentration-dependent manner. APIC was inhibited by phosphatidylinositol 3-kinase (PI3-kinase) inhibitors, LY-294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one hydrochloride] and wortmannin. Consistent with the results from tension measurement experiments, Western blot analysis showed that acidic pH induced an appreciable increment of tyrosine phosphorylation of 85-kDa protein (p85) in SHR aorta, which was completely inhibited by tyrphostin 23, whereas in Wistar rat aorta, the protein tyrosine phosphorylation was not observed. Further investigations using immunoprecipitation followed by Western blotting confirmed an increase in the tyrosine phosphorylation of p85. Analysis by SDS-polyacrylamide gel electrophoresis followed by silver staining of the gel revealed that amounts of multiple proteins with molecular sizes of 120, 130, 210, and 225 kDa were increased at acidic pH, which were immunoprecipitated with anti-phosphotyrosine antibody. Western blotting using a specific anti-PI3-kinase antibody identified the p85 as the regulatory subunit of PI3-kinase, whereas 120-, 130-, and 225-kDa proteins were identified by mass spectrometry as pro-␣2 (I) collagen, collagen ␣1 (I) chain, and fibernectin I, respectively. As assayed by Western blotting using anti-myosin light chain (MLC) antibody, acidic pH induced a stimulation of MLC phosphorylation, and the stimulated MLC phosphorylation was abolished by tyrphostin 23 and LY-294002. These results suggest that acidic pH induces an increase in tyrosine phosphorylation of PI3-kinase, resulting in the MLC phosphorylation-dependent contraction of SHR aorta.
Deep-sea Research Part Ii-topical Studies in Oceanography, 1996
The magnitudes of silica and 226Ra inputs to water (through particle regeneration, in situ, and f... more The magnitudes of silica and 226Ra inputs to water (through particle regeneration, in situ, and from sediments) and the validity of observed Si and 226Ra as tracers of water masses and advective processes were examined in the Indian Ocean using the GEOSECS data. The regenerated quantities of these two parameters were calculated as the difference between the observed and the expected concentrations; the latter were estimated from a three end-member mixing model employing potential temperature and salinity as conservative tracers. Here we present results on the quantitative spreading of the Antarctic Bottom Water (AABW); the Modified North Atlantic Deep Water (MNADW, also known as the Circumpolar Water) and the North Indian Deep Water (NIDW)--both these were represented together as High Salinity Deep Waters (HSDW); the Antarctic Intermediate Water (AAIW); the North Indian Intermediate Water (NIIW) and the Central Indian Water (CIW). Our results concur with recent results in the literature. Briefly, the northward flow of the AABW is uneven; the MNADW core layer is found to be closer to the Antarctic that spreads to the north, and AAIW is largely restricted to the Indian Ocean south of 105. Our results also reveal that: roughly 10% more AABW enters the Bay of Bengal than the Arabian Sea; there is greater possibility for deep waters to enter the Central Indian Basin from the Bay of Bengal; CIW occupies a larger part of the Bay of Bengal than of the Arabian Sea; and 10% of the NIIW reaches 305 in the western Indian Ocean.
Journal of Geophysical Research, 1996
Intensive observations in the northeast Indian Ocean (Bay of Bengal) during the presouthwest and ... more Intensive observations in the northeast Indian Ocean (Bay of Bengal) during the presouthwest and northeast monsoon seasons of 1991 reveal that freshwater discharge from rivers of the Indian subcontinent exerts the dominant control over total carbon dioxide (TCO2) and pCO 2 distributions in surface waters. Low pCO 2 levels occur within the low-salinity zones, with a large area in the northxvestem bay acting as a sink for atmosl:heric CO 2. Only a part of the observed pCO 2 variation can be accounted for by the effect of salinity, and biological production suppoaed by external nutrient inputs in conjunction with strong thermohaline stratification may be more important in lowering surface water pCO 2 by > 100 patm relative to that in the atmosphere. The pCO 2 distribution is seasonally variable and appears to be controlled by the spreading of fresher waters by the prevailing surface circulation.
Journal of Earth System Science, 2000
Usingin situ data collected during 1992–1997, under the Indian programme of Joint Global Ocean Fl... more Usingin situ data collected during 1992–1997, under the Indian programme of Joint Global Ocean Flux Study (JGOFS), we show that the biological productivity of the Arabian Sea is tightly coupled to the physical forcing mediated through nutrient availability. The Arabian Sea becomes productive in summer not only along the coastal regions of Somalia, Arabia and southern parts of the west coast of India due to coastal upwelling but also in the open waters of the central region. The open waters in the north are fertilized by a combination of divergence driven by cyclonic wind stress curl to the north of the Findlater Jet and lateral advection of nutrient-rich upwelled waters from Arabia. Productivity in the southern part of the central Arabian Sea, on the other hand, is driven by advection from the Somalia upwelling. Surface cooling and convection resulting from reduced solar radiation and increased evaporation make the northern region productive in winter. During both spring and fall inter-monsoons, this sea remains warm and stratified with low production as surface waters are oligotrophic. Inter-annual variability in physical forcing during winter resulted in one-and-a-half times higher production in 1997 than in 1995.
Selecting Neighbors in Random Field Models for Color Images
We derive a criterion for the selection of random field models for color images. Models are defin... more We derive a criterion for the selection of random field models for color images. Models are defined in terms of sets of neighbors that characterize interactions within and between bands of a color image. A Bayesian approach is used to select from a set of models the model which maximizes the posterior probability of the model given the image data.
Marine Chemistry, 1990
Abstract We report here the non-conservative behaviour of DOC in the northwestern Indian Ocean by... more Abstract We report here the non-conservative behaviour of DOC in the northwestern Indian Ocean by studying this parameter together with other carbon and nitrogen components. This contrasts with earlier reports of conservative behaviour. Concentrations of DOC, 3–4 times ...
Markov Random Field Models for Unsupervised Segmentation of Textured Color Images
IEEE Transactions on Pattern Analysis and Machine Intelligence, 1995
Abstract-We present an unsupervised segmentation algorithm which uses Markov random field models ... more Abstract-We present an unsupervised segmentation algorithm which uses Markov random field models for color textures. These models characterize a texture in terms of spatial interaction within each color plane and interaction between different color planes. The models are used by ...
Respiration rates in subsurface waters of the northern Indian Ocean: evidence for low decomposition rates of organic matter within the water column in the Bay of Bengal
Deep-sea Research Part Ii-topical Studies in Oceanography, 1996
Depth profiles of activity of the respiratory electron transport system (ETS) have been generated... more Depth profiles of activity of the respiratory electron transport system (ETS) have been generated at several locations in the northern Indian Ocean. The results reveal much lower ETS activities in subsurface waters of the Bay of Bengal than those measured in the Arabian Sea. ...
Results Using Random Field Models for the Segmentation of Color Images of Natural Scenes
We present results using a Markov random field color texture model for the unsupervised segmentat... more We present results using a Markov random field color texture model for the unsupervised segmentation of images of outdoor scenes. The color random field model describes textured regions in terms of spatial interaction within color bands and between different color bands. The model is used by a segmentation algorithm based on agglomerative hierarchical clustering. At the heart of the clustering is a step wise optimal merging process that at each iteration maximizes a global performance functional. The test for stopping the clustering is based on changes in the likelihood of the image. We provide experimental results that demonstrate the performance of the segmentation algorithm on color images of natural scenes. Most of the processing during segmentation is local making the algorithm amenable to high performance parallel implementation
Journal of Earth System Science, 2000
Bacterial abundance and production, numbers, sizes and concentrations of transparent exopolymer p... more Bacterial abundance and production, numbers, sizes and concentrations of transparent exopolymer particles (TEP) and total organic carbon (TOC) were measured during the 1996 summer monsoon to understand the relationship between TEP, the most labile particulate organic carbon, and bacteria. While high regional variability in the vertical distribution of TOC was discernible, TEP concentrations were high in surface waters at 18–20°N along 64°E with concentrations well over 25 mg alginic acid equivalents I−1 due to upwelling induced productivity. Their concentrations decreased with depth and were lower between 200 and 500 m. Bacterial concentrations were up to 1.99 × 108 I–1 in the surface waters and decreased by an order of magnitude or more at depths below 500 m. A better relationship has been found between bacterial abundance and concentrations of TEP than between bacteria and TOC, indicating that bacterial metabolism is fueled by availability of TEP in the Arabian Sea. Assuming a carbon assimilation of 33%, bacterial carbon demand (BCD) is estimated to be 1.017 to 4.035 g C m–2 d–1 in the surface waters. The observed TEP concentrations appear to be sufficient in meeting the surface and subsurface BCD in the northern Arabian Sea.
Environmental Monitoring and Assessment, 2006
Peri-urban lands are often used for production of vegetables for better market accessibility and ... more Peri-urban lands are often used for production of vegetables for better market accessibility and higher prices. But most of these lands are contaminated with heavy metals through industrial effluents, sewage and sludge, and vehicular emission. Vegetables grown in such lands, therefore, are likely to be contaminated with heavy metals and unsafe for consumption. Samples of vegetables i.e., spinach (Spinacia oleracea L.) and okra (Abelmoschus esculentus L.); soil and irrigation water were collected from 5 peri-urban sites of New Delhi to monitor their heavy metal loads. While heavy metal load of the soils were below the maximum allowable limit prescribed by the World Health Organization (WHO), it was higher in irrigation water and vegetable samples. The spinach and okra samples showed Zn, Pb and Cd levels higher than the WHO limits. The levels of Cu, however, were at their safe limits. Metal contamination was higher in spinach than in okra. Spatial variability of metal contamination was also observed in the study. Bio-availability of metals present in soil showed a positive relationship with their total content and organic matter content of soil but no relationship was observed with soil pH. Washing of vegetables with clean water was a very effective and easy way of decontaminating the metal pollution as it reduced the contamination by 75 to 100%.
European Journal of Pharmacology, 2002
pH regulates various cellular functions. Previously, we have described that acidic pH produces de... more pH regulates various cellular functions. Previously, we have described that acidic pH produces depolarization and contraction in isolated aorta from spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats [Br. J. Pharmacol. 118 (1996) 485]. The aim of the present study was to investigate the involvement of Cl À channels in acidic pH-induced contraction. Changing the pH of the bathing solution from 7.4 to 6.5 induced a contraction in both SHR and WKY aorta, which was 127.50 F 13.32% and 79.27 F 0.94% of the 64.8 mM KCl-induced contraction, respectively. The acidic pH-induced contraction was partially inhibited by the voltage-dependent Ca 2 + channel (VDCC) blockers, verapamil (1 AM) and nifedipine (0.1 AM). The Cl À channel inhibitors, diisothiocyanatostilbene-2,2V-disulfonic acid (DIDS) (0.5 mM), 9-anthracene chloride (0.5 mM), indanyloxyacetic acid (30 AM) and niflumic acid (3 AM) also inhibited the acidic pH-induced contraction and the degree of attenuation was comparable to that of VDCC blockers. DIDS, 9-anthracene chloride and niflumic acid at concentrations used to inhibit the acidic pH-induced contraction also inhibited the 10 AM phenylephrine-induced contraction partially, without affecting the 64.8 mM KCl-induced contraction, whereas both the contractions were inhibited by indanyloxyacetic acid with equal efficacy. Indanyloxyacetic acid but not DIDS, 9-anthracene chloride or niflumic acid inhibited the 24.8 mM KCl-induced contraction. Simultaneous measurement of cytosolic Ca 2 + and tension showed that niflumic acid reversed the increase in intracellular Ca 2 + level and inhibited the contraction caused by acidic pH. Similarly, acidic pH depolarized the cultured vascular smooth muscle cells from SHR and the depolarization was completely reversible after the administration of niflumic acid. All these results suggest that the activation of Cl À channels is an important mechanism underlying the depolarization and contraction induced by acidic pH in SHR and WKY aortas. D
Controls of dimethyl sulphide in the Bay of Bengal during BOBMEX-Pilot cruise 1998
Journal of Earth System Science, 2000
The air-sea exchange is one of the main mechanisms maintaining the abundances of trace gases in t... more The air-sea exchange is one of the main mechanisms maintaining the abundances of trace gases in the atmosphere. Some of these, such as carbon dioxide and dimethyl sulphide (DMS), will have a bearing on the atmospheric heat budget. While the former facilitates the trapping of radiation (greenhouse effect) the latter works in the opposite direction through reflectance of radiation back into space by sulphate aerosols that form from oxidation of DMS in atmosphere. Here we report on the first measurements made on DMS in the Bay of Bengal and the factors regulating its abundance in seawater. Phytoplankton alone does not seem to control the extent of DMS concentrations. We find that changes in salinity could effectively regulate the extent of DMSP production by marine phytoplankton. In addition, we provide the first ever evidence to the occurrence of DMS precursor, DMSP, in marine aerosols collected in the boundary layer. This suggests that the marine aerosol transport of DMSP will supplement DMS gaseous evasion in maintaining the atmospheric non-sea salt sulphur budget.
Atmospheric Environment, 2006
This paper presents information on concentrations, size distributions, geographical distributions... more This paper presents information on concentrations, size distributions, geographical distributions and sources of water-soluble organic nitrogen (ON ws ) in aerosols over the East China Sea and western North Pacific to understand its impact on the atmospheric processes and the oceanic ecosystems in the autumn and spring in the East Asian region. Results revealed ON ws contributions to the total nitrogen in aerosols to be ~ 24% and ~ 10% over the East China Sea in the autumn and the spring, respectively. The particulate ON ws mainly existed in fine sized particles. Gas to particle conversion may be the major formation process for ON ws . Occurrence of particulate ON ws in both fine and coarse modes during the Kosa event suggests gaseous ON adsorption and/ or adhesion to the coarse mode mineral.
Unsupervised segmentation of textured color images using Markov random field models
An unsupervised segmentation algorithm which uses Markov random fields for modeling color texture... more An unsupervised segmentation algorithm which uses Markov random fields for modeling color texture is presented. These models characterize a texture in terms of spatial interaction within each color plane and interaction among different color planes. These models are used for segmentation in conjunction with an agglomerative clustering procedure that at each step minimizes a global performance functional based on the
Current knowledge on the distribution of arsenic in groundwater in five states of India
Journal of Environmental Science and Health Part A-toxic/hazardous Substances & Environmental Engineering, 2007
Testing of groundwater used for drinking for arsenic has been undertaken more widely by state gov... more Testing of groundwater used for drinking for arsenic has been undertaken more widely by state governments in several states of India in recent years with the support of UNICEF. Available data for five states are collated in this paper and this provides the most up-to-date picture of areas known to be affected by arsenic in groundwater in the Indian portion of the Ganges-Brahmaputra river basin. In West Bengal, water from 132,262 government installed handpumps in 8 districts has been tested and overall 25.5% of samples were found to contain arsenic at concentrations greater than 50 μ gL−1 and 57.9% at concentrations greater than 10 μ gL−1. On the banks of the Brahmaputra in Assam, to date, samples from 5,729 government handpump sources in 22 districts have been tested for arsenic. Overall, samples from 6.3% of sources were found to contain arsenic at concentrations greater than 50 μ gL−1 and 26.1% at concentrations greater than 10 μ gL−1. In Bihar, on the River Ganges upstream of West Bengal, 66,623 sources from 11 districts have been tested and water samples from 10.8% of sources were found to contain arsenic at concentrations greater than 50 μ gL−1 and 28.9% at concentrations greater than 10 μ gL−1. Upstream of Bihar in Uttar Pradesh, home of the Taj Mahal, to date water samples from 20,126 government-installed handpump sources have been tested. As a result 2.4% of the samples tested were found to contain arsenic at concentrations greater than 50 μ gL−1 and 21.5% at concentrations greater than 10 μ gL−1. Finally in one district of Jharkhand, lying on the Ganges alluvial plain between Bihar and West Bengal, 9,007 sources have been tested and water samples from 3.7% of sources were found to contain arsenic at concentrations greater than 50 μ gL−1 and 7.5% at concentrations greater than 10 μ gL−1. State governments have adopted different sampling strategies and these are described in this paper. Testing is ongoing in several states and the complete picture is yet to emerge in some areas.
Amyloid plaque imaging agent [C-11]-6-OH-BTA-1: biodistribution and radiation dosimetry in baboon
Nuclear Medicine Communications, 2005
The amyloid neuritic plaque is considered to be a toxic collection of amyloid-ss protein found in... more The amyloid neuritic plaque is considered to be a toxic collection of amyloid-ss protein found in brain tissue in Alzheimer's disease. A neutral analogue of the amyloid-binding thioflavin-T (BTA), has been radiolabeled as [C-11]-6-OH-BTA-1. It crosses the blood brain barrier, and is a promising tracer for imaging plaques in vivo using positron emission tomography. We now report the biodistribution and dosimetry of [C-11]-6-OH-BTA-1 in baboons. Four 2-hour whole body studies were acquired in an ECAT ACCEL camera in two baboons after the bolus injection of [C-11]-6-OH-BTA-1. After 3.5 minute transmission scans performed per bed position prior to injection, emission scans were collected in 2-D mode over five bed positions. Regions of interest (ROI) were drawn around the brain, left and right lungs, heart, liver, gall bladder, left and right kidneys, spleen and urinary bladder. Since no fluid was removed from the baboons, total body radioactivity was calculated using the injected dose and a calibration factor determined from a cylinder phantom. The area under the curve (AUC) for each ROI was determined by trapezoidal integration of the first few points with subsequent points fit by a decreasing monoexponential. The AUC was then divided by counts in the total body, and resulting residence times were entered into the MIRDOSE3 program. The animals tolerated the procedure well. The ligand was eliminated via the hepatobiliary and renal systems. In the adult male and female reference the gallbladder received the highest estimated radiation dose and was the critical organ (3.9E-02 mGy/MBq and 4.3E-02 mGy/MBq respectively). In the United States, the absorbed dose to the gallbladder would limit [C-11]-6-OH-BTA-1 administered with the approval of a Radioactive Drug Research Committee (RDRC) to a single injection of 1295 MBq (35 mCi) in the adult male, and 1314 MBq (35 mCi) in the adult female.
Deep-sea Research Part Ii-topical Studies in Oceanography, 2001
Time-series observations at a nominally "xed location in the northern Arabian Sea (213N, 643E) du... more Time-series observations at a nominally "xed location in the northern Arabian Sea (213N, 643E) during the Northeast Monsoon (winter, February) of l997 showed the prevalence of cold sea-surface temperatures (SST) and deep mixed layers resulting from winter cooling and convection. The covariation of nitrate concentrations in the surface layers and concentrations of chlorophyll a and primary production in the euphotic zone with mixed-layer depth (MLD) and wind suggests that carbon "xation was controlled primarily by physical forcing. Cooler waters during winter 1997 relative to winter 1995 were associated with deeper MLDs, higher nitrate concentrations, elevated primary productivity, and higher chlorophyll a concentrations, leading to the inference that even a 13C decrease in SST could lead to signi"cantly higher primary productivity. Satellite data on sea surface temperature (advanced very high-resolution radiometer; AVHRR) and TOPEX/POSEl-DON altimeter data suggest that this interannual variation is of basin-wide spatial scale. After the termination of winter cooling and subsequent warming during the Spring Intermonsoon, the Arabian Sea has low primary production. During the latter period, micro-organisms, i.e. heterotrophic bacteria and microzooplankton)-proliferate, a feeding mode through the microbial loop that appears to be inherent to mesozooplankton for sustaining their biomass throughout the year in this region.
Journal of Earth System Science, 2003
The 26th January 2001 Bhuj earthquake occurred in the Kachchh Rift Basin which has a long history... more The 26th January 2001 Bhuj earthquake occurred in the Kachchh Rift Basin which has a long history of major earthquakes. Great Triangulation Survey points (GTS) were first installed in the area in 1856–60 and some of these were measured using Global Positioning System (GPS) in the months of February and July 2001. Despite uncertainties associated with repairs and possible reconstruction of points in the past century, the re-measurements reveal pre-seismic, co-seismic and post-seismic deformation related to Bhuj earthquake. More than 25 Μ-strain contraction north of the epicenter appears to have occurred in the past 140 years corresponding to a linear convergence rate of approximately 10 mm/yr across the Rann of Kachchh. Motion of a single point at Jamnagar 150 km south of the epicenter in the 4 years prior to the earthquake, and GTS-GPS displacements in Kathiawar suggests that pre-seismic strain south of the epicenter was small and differs insignificantly from that measured elsewhere in India. Of the 20 points measured within 150 km of the epicenter, 12 were made at existing GTS points which revealed epicentral displacements of up to 1 m, and strain changes exceeding 30 Μ-strain. Observed displacements are consistent with reverse co-seismic slip. Re-measurements in July 2001 of one GTS point (Hathria) and eight new points established in February reveal post-seismic deformation consistent with continued slip on the Bhuj rupture zone.
Journal of Pharmacology and Experimental Therapeutics, 2002
Acidic pH induced a contraction (APIC) in isolated aortas from spontaneously hypertensive (SHR) a... more Acidic pH induced a contraction (APIC) in isolated aortas from spontaneously hypertensive (SHR) and Wistar Kyoto rats, but failed to produce any response in age-matched Wistar rat aorta. This study was conducted to test the hypothesis that tyrosine phosphorylation of proteins is a molecular mechanism underlying the APIC. Tyrosine kinase inhibitors, genistein and tyrphostin 23 inhibited the APIC in a concentration-dependent manner. APIC was inhibited by phosphatidylinositol 3-kinase (PI3-kinase) inhibitors, LY-294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one hydrochloride] and wortmannin. Consistent with the results from tension measurement experiments, Western blot analysis showed that acidic pH induced an appreciable increment of tyrosine phosphorylation of 85-kDa protein (p85) in SHR aorta, which was completely inhibited by tyrphostin 23, whereas in Wistar rat aorta, the protein tyrosine phosphorylation was not observed. Further investigations using immunoprecipitation followed by Western blotting confirmed an increase in the tyrosine phosphorylation of p85. Analysis by SDS-polyacrylamide gel electrophoresis followed by silver staining of the gel revealed that amounts of multiple proteins with molecular sizes of 120, 130, 210, and 225 kDa were increased at acidic pH, which were immunoprecipitated with anti-phosphotyrosine antibody. Western blotting using a specific anti-PI3-kinase antibody identified the p85 as the regulatory subunit of PI3-kinase, whereas 120-, 130-, and 225-kDa proteins were identified by mass spectrometry as pro-␣2 (I) collagen, collagen ␣1 (I) chain, and fibernectin I, respectively. As assayed by Western blotting using anti-myosin light chain (MLC) antibody, acidic pH induced a stimulation of MLC phosphorylation, and the stimulated MLC phosphorylation was abolished by tyrphostin 23 and LY-294002. These results suggest that acidic pH induces an increase in tyrosine phosphorylation of PI3-kinase, resulting in the MLC phosphorylation-dependent contraction of SHR aorta.
Deep-sea Research Part Ii-topical Studies in Oceanography, 1996
The magnitudes of silica and 226Ra inputs to water (through particle regeneration, in situ, and f... more The magnitudes of silica and 226Ra inputs to water (through particle regeneration, in situ, and from sediments) and the validity of observed Si and 226Ra as tracers of water masses and advective processes were examined in the Indian Ocean using the GEOSECS data. The regenerated quantities of these two parameters were calculated as the difference between the observed and the expected concentrations; the latter were estimated from a three end-member mixing model employing potential temperature and salinity as conservative tracers. Here we present results on the quantitative spreading of the Antarctic Bottom Water (AABW); the Modified North Atlantic Deep Water (MNADW, also known as the Circumpolar Water) and the North Indian Deep Water (NIDW)--both these were represented together as High Salinity Deep Waters (HSDW); the Antarctic Intermediate Water (AAIW); the North Indian Intermediate Water (NIIW) and the Central Indian Water (CIW). Our results concur with recent results in the literature. Briefly, the northward flow of the AABW is uneven; the MNADW core layer is found to be closer to the Antarctic that spreads to the north, and AAIW is largely restricted to the Indian Ocean south of 105. Our results also reveal that: roughly 10% more AABW enters the Bay of Bengal than the Arabian Sea; there is greater possibility for deep waters to enter the Central Indian Basin from the Bay of Bengal; CIW occupies a larger part of the Bay of Bengal than of the Arabian Sea; and 10% of the NIIW reaches 305 in the western Indian Ocean.
Journal of Geophysical Research, 1996
Intensive observations in the northeast Indian Ocean (Bay of Bengal) during the presouthwest and ... more Intensive observations in the northeast Indian Ocean (Bay of Bengal) during the presouthwest and northeast monsoon seasons of 1991 reveal that freshwater discharge from rivers of the Indian subcontinent exerts the dominant control over total carbon dioxide (TCO2) and pCO 2 distributions in surface waters. Low pCO 2 levels occur within the low-salinity zones, with a large area in the northxvestem bay acting as a sink for atmosl:heric CO 2. Only a part of the observed pCO 2 variation can be accounted for by the effect of salinity, and biological production suppoaed by external nutrient inputs in conjunction with strong thermohaline stratification may be more important in lowering surface water pCO 2 by > 100 patm relative to that in the atmosphere. The pCO 2 distribution is seasonally variable and appears to be controlled by the spreading of fresher waters by the prevailing surface circulation.
Journal of Earth System Science, 2000
Usingin situ data collected during 1992–1997, under the Indian programme of Joint Global Ocean Fl... more Usingin situ data collected during 1992–1997, under the Indian programme of Joint Global Ocean Flux Study (JGOFS), we show that the biological productivity of the Arabian Sea is tightly coupled to the physical forcing mediated through nutrient availability. The Arabian Sea becomes productive in summer not only along the coastal regions of Somalia, Arabia and southern parts of the west coast of India due to coastal upwelling but also in the open waters of the central region. The open waters in the north are fertilized by a combination of divergence driven by cyclonic wind stress curl to the north of the Findlater Jet and lateral advection of nutrient-rich upwelled waters from Arabia. Productivity in the southern part of the central Arabian Sea, on the other hand, is driven by advection from the Somalia upwelling. Surface cooling and convection resulting from reduced solar radiation and increased evaporation make the northern region productive in winter. During both spring and fall inter-monsoons, this sea remains warm and stratified with low production as surface waters are oligotrophic. Inter-annual variability in physical forcing during winter resulted in one-and-a-half times higher production in 1997 than in 1995.
Selecting Neighbors in Random Field Models for Color Images
We derive a criterion for the selection of random field models for color images. Models are defin... more We derive a criterion for the selection of random field models for color images. Models are defined in terms of sets of neighbors that characterize interactions within and between bands of a color image. A Bayesian approach is used to select from a set of models the model which maximizes the posterior probability of the model given the image data.
Marine Chemistry, 1990
Abstract We report here the non-conservative behaviour of DOC in the northwestern Indian Ocean by... more Abstract We report here the non-conservative behaviour of DOC in the northwestern Indian Ocean by studying this parameter together with other carbon and nitrogen components. This contrasts with earlier reports of conservative behaviour. Concentrations of DOC, 3–4 times ...
Markov Random Field Models for Unsupervised Segmentation of Textured Color Images
IEEE Transactions on Pattern Analysis and Machine Intelligence, 1995
Abstract-We present an unsupervised segmentation algorithm which uses Markov random field models ... more Abstract-We present an unsupervised segmentation algorithm which uses Markov random field models for color textures. These models characterize a texture in terms of spatial interaction within each color plane and interaction between different color planes. The models are used by ...
Respiration rates in subsurface waters of the northern Indian Ocean: evidence for low decomposition rates of organic matter within the water column in the Bay of Bengal
Deep-sea Research Part Ii-topical Studies in Oceanography, 1996
Depth profiles of activity of the respiratory electron transport system (ETS) have been generated... more Depth profiles of activity of the respiratory electron transport system (ETS) have been generated at several locations in the northern Indian Ocean. The results reveal much lower ETS activities in subsurface waters of the Bay of Bengal than those measured in the Arabian Sea. ...
Results Using Random Field Models for the Segmentation of Color Images of Natural Scenes
We present results using a Markov random field color texture model for the unsupervised segmentat... more We present results using a Markov random field color texture model for the unsupervised segmentation of images of outdoor scenes. The color random field model describes textured regions in terms of spatial interaction within color bands and between different color bands. The model is used by a segmentation algorithm based on agglomerative hierarchical clustering. At the heart of the clustering is a step wise optimal merging process that at each iteration maximizes a global performance functional. The test for stopping the clustering is based on changes in the likelihood of the image. We provide experimental results that demonstrate the performance of the segmentation algorithm on color images of natural scenes. Most of the processing during segmentation is local making the algorithm amenable to high performance parallel implementation
Journal of Earth System Science, 2000
Bacterial abundance and production, numbers, sizes and concentrations of transparent exopolymer p... more Bacterial abundance and production, numbers, sizes and concentrations of transparent exopolymer particles (TEP) and total organic carbon (TOC) were measured during the 1996 summer monsoon to understand the relationship between TEP, the most labile particulate organic carbon, and bacteria. While high regional variability in the vertical distribution of TOC was discernible, TEP concentrations were high in surface waters at 18–20°N along 64°E with concentrations well over 25 mg alginic acid equivalents I−1 due to upwelling induced productivity. Their concentrations decreased with depth and were lower between 200 and 500 m. Bacterial concentrations were up to 1.99 × 108 I–1 in the surface waters and decreased by an order of magnitude or more at depths below 500 m. A better relationship has been found between bacterial abundance and concentrations of TEP than between bacteria and TOC, indicating that bacterial metabolism is fueled by availability of TEP in the Arabian Sea. Assuming a carbon assimilation of 33%, bacterial carbon demand (BCD) is estimated to be 1.017 to 4.035 g C m–2 d–1 in the surface waters. The observed TEP concentrations appear to be sufficient in meeting the surface and subsurface BCD in the northern Arabian Sea.