Non-radial oscillations in an axisymmetric MHD incompressible fluid

It is well known from Helioseismology that the Sun exhibits oscillations on a global scale, most of which are non-radial in nature. These oscillations help us to get a clear picture of the internal structure of the Sun as has been demonstrated by the theoretical and observational (such as GONG) studies. In this study we formulate the linearised equations of motion for non-radial oscillations by perturbing the MHD equilibrium solution for an axisymmetric incompressible fluid. The fluid motion and the magnetic field are expressed as scalarsU, V, P andT, respectively. In deriving the exact solution for the equilibrium state, we neglect the contribution due to meridional circulation. The perturbed quantitiesU *, V *, P *, T * are written in terms of orthogonal polynomials. A special case of the above formulation and its stability is discussed.     

Spatiotemporal variations in heat-related health risk in three Midwestern US cities between 1990 and 2010

Mortality from extreme heat is a leading cause of weather-related fatality, which is expected to increase in frequency with future climate scenarios. This study examines the spatiotemporal variations in heat-related health risk in three Midwestern cities in the USA between the years 1990 to 2010; cities include Chicago, Illinois, Indianapolis, IN and Dayton, OH. In order to examine these variations, we utilize the recently developed extreme heat vulnerability index (EHVI) that uses a principal components solution to vulnerability. The EHVI incorporates data from the US Decadal Census and remotely sensed variables to determine heat-related vulnerability at an intra-urban level (census block group). The results demonstrate significant spatiotemporal variations in heat health risk within the cities involved.     

Polychlorinated biphenyls (PCBs) in a benthic ecosystem in Gwangyang Bay, South Korea

Benthic ecosystem in Gwangyang Bay, a fast developing industrial area with steel production, port container handling, petroleum and other chemical processing in South Korea was studied. The average levels of polychlorinated biphenyls (ΣPCB) in the benthic components were: seawater 2.99 ± 0.13 (ng/L); sediment 294 ± 118 (ng/g TOC); [biota=ng/g lipid] starfish 92; prawn 131 ± 2; mussels 127 ± 22; crab 182 ± 114; clam 187; polychaeta 215; sea cucumber 497 ± 90; squill 603 ± 38; fish 396 ± 159. Levels in the inner bay samples were higher than the outer bay samples suggesting land based pollution. Good correlation (r(2)=0.79; p<0.05) existed between PCB concentration and lipid content indicating partitioning processes in action. PCB signature in the abiotic and biotic components shows enrichment of lower chlorinated congeners emitted by a unique source nearby, viz. steel manufacturing plant.     

Predicting and forecasting flow discharge at sites receiving significant lateral inflow

Two models, one linear and one non‐linear, were employed for the prediction of flow discharge hydrographs at sites receiving significant lateral inflow. The linear model is based on a rating curve and permits a quick estimation of flow at a downstream site. The non‐linear model is based on a multilayer feed‐forward back propagation (FFBP) artificial neural network (ANN) and uses flow‐stage data measured at the upstream and downstream stations. ANN predicted the real‐time storm hydrographs satisfactorily and better than did the linear model. The results of sensitivity analysis indicated that when the lateral inflow contribution to the channel reach was insignificant, ANN, using only the flow‐stage data at the upstream station, satisfactorily predicted the hydrograph at the downstream station. The prediction error of ANN increases exponentially with the difference between the peak discharge used in training and that used in testing. ANN was also employed for flood forecasting and was compared with the modified Muskingum model (MMM). For a 4‐h lead time, MMM forecasts the floods reliably but could not be applied to reaches for lead times greater than the wave travel time. Although ANN and MMM had comparable performances for an 8‐h lead time, ANN is capable of forecasting floods with lead times longer than the wave travel time. Copyright © 2007 John Wiley & Sons, Ltd.     

Nonlinear stability of the triangular libration points for the photo gravitational elliptic restricted problem of three bodies

In the present paper we have studied the stability of the triangular libration points for the doubly photogravitational elliptic restricted problem of three bodies under the presence of resonances as well as under their absence. Here we have found the conditions for stability.     

The occultation of MKE 31 by Neptune on September 12, 1983

The predicted occultation of the star No. 31 (Mink et al., 1981) by Neptune on September 12, 1983 was observed photoelectrically. Four secondary occultations were recorded before the immersion event.     

Morphological characteristics and emplacement mechanism of the seamounts in the Central Indian Ocean Basin

The morphotectonic features of the Central Indian Ocean Basin (CIOB) provide information regarding the development of the basin. Multibeam mapping of the CIOB reveals presence of abundant isolated seamounts and seamount chains sub-parallel to each other and major fracture zones along 73° E, 79° E and 75°45′ E. Morphological analyses were carried out for 200 seamounts that occur either as isolated edifies or along eight sub-parallel chains. The identified eight parallel seamount chains that trend almost north–south and reflecting the absolute motion of the Indian plate, probably originated from the ancient propagative fractures. Inspite of the differences in their height, the seamounts of these eight chains are morphologically correlatable. In the study area the seamounts are clustered north and south of 12° S latitude. Interestingly, in the area north of 12° S (area II: 9°–12° S) the seamounts are distinctly smaller (≤ 400 m height) whereas, the area south of 12° S (area I: 12°–15° S) has a mixed population of seamounts. The normalized abundance of the CIOB seamount is 976 seamounts/10⁶ km² but on a finer scale this value varies from 500 to 1600 seamounts/10⁶ km², which is less than the seamount concentrations of the Pacific and Atlantic oceans (9000 to 16,000 seamounts/10⁶ km²). Three categories of seamounts are present in the CIOB e.g. (1) single-peaked (2) multi-peaked and (3) composite. The study indicate that single-peaked seamounts are dominant (89%) while multi-peaked is less (8%) and composite ones are rare (3%) in the CIOB.The progressive northward movement of the Indian continent caused collision between India and Asia at around 62 Ma ago. A majority of the near-axis originated seamounts in the CIOB seemed to have formed as a consequence of the temporally widespread (Cretaceous  65 Ma to late Eocene < 49 Ma) collision between India and Eurasia. The regional stress patterns in the Indian plate vary N to NE in the continent and N to NW in Indian Ocean areas. The combined effect of the regional stress patterns maintained the orientation of the seamount chains and the local stress regime helped in the upwelling of magma and formation of seamounts. The low heat flow, morphological features and geochemical signature indicate that the morphotectonic structures formed contemporaneously with the oceanic crust.     

Evaluation of mixing schemes in the HYbrid Coordinate Ocean Model (HYCOM) in the tropical Indian Ocean

Ocean Dynamics - The performance of three different mixing schemes implemented in the HYbrid Coordinate Ocean Model (HYCOM), namely, K-Profile Parameterization (KPP), Goddard Institute of Space...     

Optimizing urban stormwater control strategies and assessing aquifer recharge through drywells in an urban watershed

Hydrogeology Journal - A coupled simulation-optimization model (SOM) is developed in this work that links the US Environmental Protection Agency’s Storm Water Management Model (SWMM) with a...     

Occurrence of High Level Magma Intrusives and Associated Mineralization near Gani Inlier,Kurnool Sub-Basin,Cuddapah Basin,India

An ensemble of spatially associated high level magma intrusives comprising dykes, laccolith and vent have been identified near Gani inlier in the Kurnool sub-basin. Geological setting, morphology of igneous intrusives and their relationships with the sediment cover have been documented. Diabase in laccolith, dykes and vesicular basalt in vents are prominent rocks and have been subjected to extensive deuteric alterations viz. saussurtisation and uralitisation. It is envisioned that the basic magma was intruded as dykes in strike-slip fault domain, outpoured through the vents as vesicular basalts at the intersection zones of cross faults. The vertical ascending melt was deflected as a sheet due to fault control at a sub-surface level of ～700m along the lithological discontinuities in country rock sediments. The sheet to laccolith transition has resulted in the uplift of older Tadpatri Formation as an inlier amidst the Neoproterozoic Kurnool sediment cover. The localization of iron ore and copper mineralization adjacent to intrusives is attributed to late stage melt-fluid activity associated with the igneous activity. Based on field relationships it is suggested that the high level magmatic activity had occurred after the Kurnool sedimentation in this part of the Kurnool sub-basin.