Toxicity,biochemical and clastogenic response of chlorpyrifos and carbendazim in milkfish Chanos chanos

Carbendazim and Chlorpyrifos are some of the most widespread environmental contaminants of major concern to human and animal reproductive health. Acute toxicity test results for pesticides were evaluated by the Probit analysis method and 96 h LC₅₀ values for C. chanos exposed to chlorpyrifos was 3.73 and 11.5 μg l^?1 for carbendazim. Chlorpyrifos and carbendazim significantly decreased total protein, catalase, glutathione S-transferase and acetyl choline esterase and induced lipid peroxidation. Maximum effects of protein, catalase, lipid peroxidation, acetyl choline esterase and glutathione s-transferase were obtained in response to 23.68 μg l^?1 of chlorpyrifos and 43.68 μg l^?1 of carbendazim. Micronuclei assay results have shown increased abnormality with increasing doses of chlorpyrifos and carbendazim. Maximum increasing in micronuclei was observed in chlorpyrifos exposed C. chanos. This study showed that chlorpyrifos and carbendazim induced alterations in the activity of antioxidant enzymes and could induce clastogenicity.     

Petrogenesis of lunar meteorite EET 96008

Lunar meteorite EET 96008 is a fragmental breccia that predominantly consists of basaltic mineral clasts (0.5-2 mm), along with minor lithic fragments and breccia clasts. The matrix consists mainly of smaller mineral fragments (<0.5 mm), bound by glassy cement, the majority of which are pyroxene and plagioclase. The pyroxene possesses extensive exsolution lamellae. These lamellae, up to 1 μm in width, are atypical for mare-basalts. One of the distinguishing textures of EET 96008 is the presence of small pockets (∼400 × 500 μm) of mesostasis areas consisting of coarse (∼20 μm) intergrowths of ferroaugite, fayalite and Si-rich glass. Laths of ilmenite, armalcolite, apatite and whitlockite are also distributed in these areas. Ilmenite grains are abundant and dispersed throughout the thin sections. Chromite and ulvöspinel are present but in minor abundance. Troilite, generally rare in this rock, occurs as several grains in one pyroxene crystal. FeNi metal is conspicuously absent from this meteorite.The molar Fe/Mn ratio in olivines and pyroxenes and the age of the meteorite are evidence for a lunar origin. The mineralogy of EET 96008 shows close affinity to a mare-basalt source, albeit with possible minor highland/non-mare components. The bulk-rock, major-, trace- and rare-earth-element (REE) contents are similar to that of very low-titanium (VLT) basalts, which have experienced extreme fractional crystallization to the point of silicate liquid immiscibility. Mineralogical and textural features of this sample suggest that at least some of the breccia components were derived from a slow-cooled magma. The mineralogy and petrology of EET 96008 is strikingly similar to the lunar meteorite EET 87521, and we support the conclusion that EET 96008 and EET 87521 should be paired.Isochron ages of 3530 ± 270 Ma for apatite and 3519 ± 100 Ma for whitlockite of this rock are consistent with derivation from a mare-basalt precursor. These ages are within error of the low-Ti basalts, dated from the Apollo 12 and 15 sites. The whole-rock, platinum-group-element (PGE) contents of EET 96008 overlap with pristine low-Ti mare basalts, suggesting the presence of only a minimal extraterrestrial component.     

Aeromagnetic signatures of Precambrian shield and suture zones of Peninsular India

In many Precambrian provinces the understanding of the tectonic history is constrained by limited exposure and aeromagnetic data provide information below the surface cover of sediments,water,etc.and help build a tectonic model of the region.The advantage of using the aeromagnetic data is that the data set has uniform coverage and is independent of the accessibility of the region.In the present study,available reconnaissance scale aeromagnetic data over Peninsular India are analyzed to understand the magnetic signatures of the Precambrian shield and suture zones thereby throwing light on the tectonics of the region.Utilizing a combination of differential reduction to pole map,analytic signal,vertical and tilt derivative and upward continuation maps we are able to identify magnetic source distribution,tectonic elements,terrane boundaries,suture zones and metamorphic history of the region.The magnetic sources in the region are mainly related to charnockites,iron ore and alkaline intrusives.Our analysis suggests that the Chitradurga boundary shear and Sileru shear are terrane boundaries while we interpret the signatures of Palghat Cauvery and Achankovil shears to represent suture zones.Processes like metamorphism leave their signatures on the magnetic data:prograde granulites(charnockites)and retrograde eclogites are known to have high susceptibility.We fnd that charnockites intruded by alkali plutons have higher magnetization compared to the retrogressed charnockites.We interpret that the Dharwar craton to the north of isograd representing greenschist to amphibolite facies transition,has been subjected to metamorphism under low geothermal conditions.Some recent studies suggest a plate tectonic model of subductionecollisioneaccretion tectonics around the Palghat Cauvery shear zone(PCSZ).Our analysis is able to identify several west to east trending high amplitude magnetic anomalies with deep sources in the region from Palghat Cauvery shear to Achankovil shear.The magnetic high associated with PCSZ may represent the extruded high pressureeultra high temperature metamorphic belt(granulites at shallow levels and retrogressed eclogites at deeper levels)formed as a result of subduction process.The EW highs within the Madurai block can be related to the metamorphosed clastic sediments,BIF and mafc/ultramafc bodies resulting from the process of accretion.     

Crustal Configuration of the Northwest Himalaya Based on Modeling of Gravity Data

The gravity response and crustal shortening in the Himalayan belt are modeled in detail for the first time in the NW Himalaya. The Bouguer gravity anomaly along a ~450-km-long (projected) transect from the Sub-Himalaya in the south to the Karakoram fault in the north across the Indus-Tsangpo Suture Zone is modeled using spectral analysis, wavelet transform and forward modeling. The spectral analysis suggests three-layer interfaces in the lithosphere at 68-, 34- and 11-km depths corresponding to the Moho, the Conrad discontinuity and the Himalayan decollement thrust, respectively. The coherence, admittance and cross spectra suggest crustal shortening because of convergence compensated by lithospheric folding at 536- and 178-km wavelength at the Moho and the upper-crustal level. An average effective elastic thickness of around 31 km is calculated using the coherence method. The gravity data are modeled to demarcate intracrustal to subcrustal regional thrust/fault zones. The geometrical constraints of these faults are obtained in the space scale domain using the wavelet transform, showing good correlation with the major tectonic boundaries. The crustal configuration along the transect shows how the Moho depth increases from 45 to 80 km towards the north with the locus of flexure of the Indian crust beneath the Higher Himalayan zone. The combination of forward modeling and wavelet analysis gives insight into the subsurface extent and geometry of regional structures across the NW Himalaya.     

An estimate of the energy spectrum of gamma rays from the central region of the Galaxy and some implications

High resolution surveys of the galactic centre suggest the existence of an extended nonthermal source (Bulge) with an intensity much larger than the total background radiation in that direction. In this paper, we have first evaluated the physical conditions existing in this restricted region of space from an analysis of the radio spectrum and shown that if the distribution of matter, magnetic fieldB(r) and cosmic ray densityk(r) in the plane of the Galaxy is of gaussian type then at the centreB (0)=25–30 G andk(0)=25–35 times that in the near interstellar space. It is also found that most of the absorption in the Sagittarius A spectrum at low frequencies takes place in the Bulge and one requires a small additional absorption to take place in the line of sight corresponding to n _e ²10 cm^–6 pc at a temperature typically of clouds 100 K. The gamma ray spectra from the Bulge arising from interactions of cosmic rays with matter and radiation are then calculated in detail. A comparison made with the estimated background gamma ray spectra from the disk reveals that a detector with angular resolution 6° having a threshold of a few times 10^–6 photons cm^–2 s^–1 can detect this source; this bulge is not found to be a good X-ray source for detection. From a comparison of these calculations with the observed flux above 100 MeV, the following inferences have been deduced: (i) the lower limit to the magnetic field strength at the centre is 12 G, (ii) the observed gamma ray flux towards the Anti-centre can be well explained as due to interactions of cosmic rays with matter alone and a similar explanation towards the center reveals that cloud complexes could be more in the inner parts of the Galaxy than in the outer parts, and (iii) the observed flux values are found to be inconsistent with the existence of submillimeter radiation in the galactic scale.     

Estimation of wave directional spreading in shallow water

This paper describes wave directional spreading in shallow water. Waves were measured for a period of 2 months using the Datawell directional waverider buoy at 15 m water depth on the east coast of India in the Bay of Bengal. The study also showed that in shallow water wave directional spreading was narrowest at peak frequency and widened towards lower and higher frequencies. The wind direction was found to deviate from the wave direction during most of the time. The unidirectional spectrum was found to be satisfactorily represented by Scott spectra.     

Evolution of the basalts from three back-arc basins of southwest Pacific

Petrography, petrochemistry, and mineral chemistry of basalts from the Woodlark, Manus, and Lau basins from the southwest Pacific, have been studied to understand their magmatic evolution. Basalt from the western Woodlark Basin (Dobu Seamount) indicates mixing of a near-primitive magma with fractionated basaltic melt in shallow magma chambers. Basalts from Manus Basin and Central Lau Spreading Center (Lau Basin) are typical N-MORBs, and they exhibit olivine fractionation under high oxidizing conditions while basalts from Mangatolu Triple Junction (Lau Basin) are enriched in Al₂O₃, K₂O, and Zr indicative of a contribution from a subducting plate.     

Isolating type-specific phenologies through spectral unmixing of satellite time series

Vegetation phenology is commonly studied using time series of multi-spectral vegetation indices derived from satellite imagery. Differences in reflectance among land-cover and/or plant functional types are obscured by sub-pixel mixing, and so phenological analyses have typically sought to maximize the compositional purity of input satellite data by increasing spatial resolution. We present an alternative method to mitigate this ‘mixed-pixel problem’ and extract the phenological behavior of individual land-cover types inferentially, by inverting the linear mixture model traditionally used for sub-pixel land-cover mapping. Parameterized using genetic algorithms, the method takes advantage of the discriminating capacity of calibrated surface reflectance measurements in red, near infrared, and short-wave infrared wavelengths, as well as the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index. In simulation, the unmixing procedure reproduced the reflectances and phenological signals of grass, crop, and deciduous forests with high fidelity (RMSE?相似文献   

Assessing adaptive capacity to tropical cyclones in the East coast of India: a pilot study of public response to cyclone warning information

Ability to respond positively to climate hazards (also called adaptive capacity) first requires a perception of the risk due to that hazard and then formulation, evaluation and implementation of response by the exposed units with the view to reducing impacts. From a policy perspective, facilitating the process of perception of risk (and sometimes formulation, evaluation and implementation of response) often requires some kind of generation and communication of information for use by the exposed units. For example, the cyclone early warning system is a policy intervention which aims to generate and communicate information to the people about a possible cyclone occurrence, so as to facilitate timely and appropriate response such as evacuating the risk prone areas and/or taking refuge in a cyclone shelter by the people in danger. Anecdotal evidence suggests that many a time the cyclone warning message is not able to generate the desired response from the target audience. An understanding of the factors underlying the process of perception, formulation, evaluation and response by the exposed units to manage cyclone risk is required to close the gap between the desired response and the actual response by the exposed units to the warning information. In this paper we attempt to identify such factors in the Indian context. We conducted an exploratory study on the East coast of India to identify the factors that affect the perceptual and evaluative processes underlying the ‘warning-response’ process i.e. evacuation behavior of the exposed units once they have received the cyclone warning. The findings highlight some important factors that could be addressed to improve the warning-response process and hence enhance the ability of people to respond to cyclone risk.     

Chromium isotopes identify the extraterrestrial component in impactites from Dhala impact structure,India

The Dhala structure in north-central India is a confirmed complex impact structure of Paleoproterozoic age. The presence of an extraterrestrial component in impactites from the Dhala structure was recognized by geochemical analyses of highly siderophile elements and Os isotopic compositions; however, the impactor type has remained unidentified. This study uses Cr isotope systematics to identify the type of projectile involved in the formation of the Dhala structure. Unlike the composition of siderophile elements (e.g., Ni, Cr, Co, and platinum group elements) and their inter-element ratios that may get compromised due to the extreme energy generated during an impact, Cr isotopes retain the distinct composition of the impactor. The distinct ε⁵⁴Cr value of −0.31 ± 0.09 for a Dhala impact melt breccia sample (D6-57) indicates inheritance from an impactor originating within the non-carbonaceous reservoir, that is, the inner Solar System. Based on the Ni/Cr ratio, Os abundance, and Cr isotopic composition of the samples, the impactor is constrained to be of ureilite type. Binary mixing calculations also indicate contamination of the target rock by 0.1–0.3 wt% of material from a ureilite-like impactor. Together with the previously identified impactors that formed El'gygytgyn, Zhamanshin, and Lonar impact structures, the Cr isotopic compositions of the Dhala impactites argue for a much more diverse source of the objects that collided with the Earth over its geological history than has been supposed previously.