Instabilities in a nonstationary model of self-gravitating disks. II. Warp modes of vertical oscillations

Gravitational instabilities with respect to warp modes of vertical oscillations are examined for nonlinearly nonequilibrium disk models with isotropic and anisotropic velocity diagrams. Nonstationary analogs of the dispersion relations for vertical oscillations in these models are derived in a general form. A detailed study is made of the major large scale oscillatory modes, which correspond primarily to the most common type of warp in the form of an integral sign, as well as to dome-shaped, U-shaped, and precessional warps. Critical diagrams showing the initial virial relation as a function of the rotation parameter for the nonstationary model are constructed for each of these vertical oscillation modes. A comparative analysis is made of the growth rates of the instabilities for these modes in order to determine the dependence of the characteristic times for their appearance on the basic physical parameters of the two models.     

Number Counts,Confusion, Mapping Issues,and Sky Coverage Analysis for Radio Continuum Surveys through Emu Early Science,EMU-ASKAP,and WODAN Especially for Cosmology Science Goals

In this study, we discuss the challenges radio astronomers face while observing radio continuum sources. We consider issues related to rms noise, confusion, position accuracy, shot noise and how these issues affect observation results, data analysis and the science goals we are trying to achieve. We mainly focus on the Evolutionary Map of the Universe (EMU-ASKAP) sky survey, EMU Early science survey and Westerbork Observations of the Deep APERTIF Northern sky (WODAN). The study will also be useful for future surveys like with possible continuum surveys through MeerKAT (e.g., MIGHTEE) and SKA-1. The late time Integrated Sachs-Wolfe (ISW) effect detection is one of the major areas of research related to dark energy cosmology. We will particularly discuss how technical, data analysis and mapping issues, affect galaxy over/under density dependent science goals like the detection of the late time Integrated Sachs-Wolfe (ISW) effect through wide-field radio continuum surveys.

     

Effects of layered heterogeneity in subsurface geologic materials on solute transport under field conditions: A case study from northeastern Iowa, USA

In the Cedar River watershed of northeastern Iowa, USA, water quality in 17 out of 20 private wells indicates that groundwater is contaminated with nitrate from agricultural leachates. In nine of the wells, nitrate concentration exceeds the US Environmental Protection Agency recommended maximum contaminant level (MCL) of 45umg/L (as NO3 ^m) for drinking purposes. Solute-transport investigations determined that the surficial loam sediments, the Quaternary sand and gravel deposits, and the glacial till deposits form layered heterogeneity in the subsurface. The resulting conductivity contrast causes a capillary barrier, thereby altering the mechanisms of vertical tracer movement. Storm-water tracing with potassium bromide, corn fertilizer, and fluorescein dye indicates that macropore flow occurs only within the upper 0.9um of loamy sediments. An average breakthrough concentration of 204umg/L bromide at 0.3um depth on day 3 after the storm event supports the hypothesis of macropore flow in the surficial soils. Fluorescein dye was recovered at a depth of 0.3um with a peak concentration of 650u7g/L at approximately 5udays after the storm event. The loamy sediment layer is underlain by the Iowan Pebble Band, a pebbly layer admixed with sand, developed in post-glacial time. In the field experiments, preferential flow of the tracers was predominantly vertical within the loamy sediments but rapidly changed to a horizontal matrix flow upon entering the materials of higher saturated hydraulic conductivity in the Pebble Band. The Pebble Band is underlain by low-conductivity deposits of pre-Illinoian till. Even though the upper oxidized portion of the glacial till is reported to have macropores, the Pebble Band prevented deeper infiltration of storm water by maintaining a strong component of horizontal hydraulic gradient. Chemical data indicate that the Pebble Band is a hydraulic-conductivity boundary that abruptly changes the unsaturated-flow mechanism from macropore flow to matrix flow. Résumé Dans le bassin de la rivière du Cèdre, au nord-est de l'Iowa (États-Unis), la qualité de l'eau de 17 puits particuliers sur 20 montre que l'eau souterraine est contaminée par des nitrates provenant de lessivages agricoles. Dans 9 de ces puits, la concentration en nitrates dépasse la concentration maximale recommandée par l'Agence américaine de protection de l'environnement (EPA), fixée à 45umguNO3/L pour l'eau potable. Des études sur le transport de solutés ont montré que les sédiments détritiques (loamy) superficiels, les dépôts quaternaires de sables et de graviers et les dépôts morainiques constituent une formation hétérogène litée sous la surface. Le contraste de conductivité résultant constitue une barrière capillaire qui modifie les mécanismes réglant le mouvement vertical du traceur. Le traçage de l'eau d'une averse par du bromure de potassium, un engrais du maïs et de la fluorescéine indique que l'écoulement dans les macropores se produit uniquement dans les premiers 90ucm des sédiments détritiques (loamy). Une concentration moyenne de la restitution de 204umg/L de bromure à 30ucm de profondeur le troisième jour après l'averse va dans le sens de l'hypothèse d'un écoulement dans les macropores des sols superficiels. La restitution de la fluorescéine s'est produite à 30ucm de profondeur par un pic à une concentration de 650u7g/L environ 5ujours après l'averse. La couche de sédiments détritiques est recouverte par la couche de galets de l'Iowa, un niveau postglaciaire de galets mêlés à du sable. Au cours des expériences de terrain, un écoulement préférentiel des traceurs a été verticalement prédominant dans les sédiments détritiques (loamy), mais s'est rapidement changé en un écoulement matriciel horizontal en entrant dans les matériaux à plus forte conductivité hydraulique saturée dans la couche de galets de l'Iowa. Cette couche de galets est recouverte (underlain) par des dépôts à faible conductivité de la moraine pré-illinoyenne. Même si la partie supérieure oxydée de la moraine paraît posséder des macropores, la couche à galets empêche l'infiltration de l'eau de l'averse en introduisant une forte composante dans le gradient hydraulique horizontal. Les données chimiques montrent que la couche à galets se présente comme une limite de conductivité hydraulique qui change brutalement le mécanisme d'écoulement non saturé d'un écoulement en macropore en un écoulement matriciel. Resumen Se ha detectado una contaminación por lixiviados de nitrato de origen agrícola en 17 de los 20 pozos particulares muestreados en la cuenca del río Cedar, al Nordeste de Iowa (EEUU). En nueve de los pozos, el contenido en nitrato es superior a la concentración máxima admitida para agua potable (45umg/L), de acuerdo con los criterios de la Agencia Medioambiental de los Estados Unidos (USEPA). Mediante investigaciones de transporte de solutos, se ha podido caracterizar la heterogeneidad del subsuelo debido al contraste de conductividad hidráulica entre las tres capas identificadas: sedimentos margosos superficiales, depósitos Cuaternarios de arena y grava, y depósitos de till glacial. El contraste de materiales origina una barrera capilar que altera los mecanismos del desplazamiento vertical de trazador. Se ha utilizado bromuro de potasio, fertilizante de maíz y fluoresceína como trazadores del agua de tormenta. De esta forma se ha observado que el flujo a través de macroporos es significativo únicamente en la capa superior margosa de 0.9um. Prueba de ello es que se registró una concentración promedio de 204umg/L de bromuro, a una profundidad de 0.3um, tres días después del episodio de lluvia. Se midió asimismo un pico de fluoresceína de 650u7g/L, también a 0.3um, al cabo de cinco días. Bajo las margas se encuentra el nivel de cantos rodados de Iowa (Iowan Pebble Band), desarrollado en un período post-glacial, que consiste en cantos rodados mezclados con arena. Gracias a los experimentos de campo se pudo comprobar que hay un flujo vertical preferente de trazador en el estrato superior margoso, el cual se convierte de inmediato en horizontal (en la matriz) al encontrar el nivel de cantos rodados, cuya conductividad hidráulica saturada es mayor. Por debajo de los cantos hay depósitos de tillita pre-Illinoiense de baja conductividad. Aunque se han identificado macroporos en la parte superior oxidada de los depósitos glaciales, la existencia de un marcado gradiente horizontal en el nivel de cantos rodados actúa impidiendo la infiltración del agua de tormenta. Los datos químicos indican que el nivel de cantos rodados se comporta como un contorno de conductividad hidráulica que altera abruptamente el mecanismo de flujo no saturado, inicialmente a través de los macroporos del suelo, para convertirlo en flujo en medio poroso.     

Comparative study of body composition of different fish species from brackish water pond

Seven species of fish (Catla catla, Cirrhinus mrigala, Cyprinus carpio, Hypophthalmicthys molitrix, Labeo rohita, Mori-Rahu Hybrid and Thalla-Rahu Hybrid) were collected from a brackish water pond near Muzaffargarh, Pakistan for the comparison of body composition. All the seven species were found relatively well adapted to the saline environment though some of them showed significant differences in body composition. Results obtained did not show any adverse effect of salinity on these fish species. The mean values of body constituents, except for protein content (dry and wet body weight) differed significantly (P<0.05) among various fish species. Minimum amount of water content and maximum amount of lipids, organic content and condition factor were observed in Cyprinus carpio indicating that Cyprinus carpio show overall better growth in brackish water as compared to other species. Cyprinus carpio may be recommended for culturing in such water bodies and farmers may be encouraged to farm this species on mass scale.     

Comparative study of body composition of four fish species in relation to pond depth

Fish specimen of Labeo rohita, Cirrhinus mrigala, Hypophthalmicthys molitrix and Catla catla were sampled from three ponds of different depths (152 cm, 122 cm and 76 cm) to compare the body composition of these species in relation to pond depth. There was significant (P < 0.001) effect of pond depth on water, ash, organic, fat and protein contents (all % wet and dry body weight). It was observed that pond depth has significant effect (P < 0.01) on condition factor in pond B (122 cm depth) and no effect in pond A and C. Maximum mean values of body composition were observed in Labeo rohita in all the three ponds. Present study demonstrates that fish cultured in ponds of different depths have different values of protein which can help guide the farmers to select best pond depths to produce protein rich fish.     

Impact assessment due to rural electrification in hill tract of Bangladesh for sustainable development

Environmental impact assessment (EIA) of any project is essential for understanding the sustainability of the project. For sustainable development of hill tracts, electricity is inseparable. Like other parts of Bangladesh hill tracts districts felt increasing demand of electricity. In this paper an attempt has been taken to present the existing environmental condition and analysis the future environmental condition after implementation of project. Electrification will extend the length of the active day. Electrification will improve security (people’s perception of safety and security) at the region. The elements of the project identified as components for analysis are chosen based on DOE’s guideline. The study showed that 87% people say that they feel safer at night since being electrified. Impacts are classified on the basis of EPA’s scaling and DOE, university’s teachers, NGOs expert’s opinions. Value more than 10 is classified significantly affected element of the project. In this paper advantages and disadvantages of the Electrification Project has been presented.     

Studies on the transfer of mineral nutrients from feed, water, soil and plants to buffaloes under arid environments

Studies were conducted at a Livestock Farm in an arid region of Pakistan, to determine the uptake of mineral nutrients from the food of buffaloes. Samples of feed, water, forage, soil as well as blood, milk, urine, and faeces of the animals were collected and analysed for K⁺, Ca²⁺, and Fe²⁺ during summer and winter. The results showed that the concentrations of K⁺ and Ca²⁺ in plants were low, whereas that of Fe²⁺ was high. In animals, K⁺ was not found in the milk in significant amounts, rather it was excreted in the urine. The calcium taken in by the animals was used for the synthesis of milk, as a result of which low Ca²⁺ concentrations were detected in urine. Mineral nutrient concentrations (K⁺ and Ca²⁺) in forage plants and water were lower than the optimum requirement of the animals, as a result of which blood plasma contained lower amounts of minerals (K⁺ and Fe²⁺) than that of the normal animals or critical limits. From the findings of the present study, it can be concluded that the buffaloes raised at the livestock farm had a severe deficiency of mineral nutrients, particularly K⁺ in lactating and Fe²⁺ in both lactating and non-lactating animals. Feed supplements, that can overcome these deficiencies, should be used for the optimum growth, milk production and resistance to diseases.     

Polar wandering path for India during the Precambrian

Summary The recent radiometric dating on some Precambrian formations of India and the available paleomagnetic data have enhanced the possibility of deducing the Polar wander path for India during the remote past. The data indicate that India was in the northern hemisphere during the Precambrian times. This inference has also been substantiated by the paleoclimatic evidences.     

Stability of remanent magnetization of some dykes from Mysore State,India

Summary The magnetic properties of some dykes from Mysore State, India, have been studied in detail. The rocks were found to have aQ _n ratio varying from 1.5 to 11.6, a remanent coercive force varying from 100 to 250 Oersteds, Curie temperature varying from 250 to 480°C and were found to have lamellae of ilmenite oriented in (111) plane of magnetite. The stable natural remanent magnetization of the rock seems to be of TRM origin with titanomagnetite and low grade titanomaghemite being the main carrier of remanent magnetization.N.G.R.I. Contribution No. 70-215.