Stability of Electrostatic Electron Cyclotron Waves in a Multi-Ion Plasma

We have studied the stability of the electrostatic electron cyclotron wave in a plasma composed of hydrogen, oxygen and electrons. To conform to satellite observations in the low latitude boundary layer we model both the ionic components as drifting perpendicular to the magnetic field. Expressions for the frequency and the growth rate of the wave have been derived. We find that the plasma can support electron cyclotron waves with a frequency slightly greater than the electron cyclotron frequency ω _ce ; these waves can be driven unstable when the drift velocities of both the ions are greater than the phase velocity of the wave. We thus introduce another source of instability for these waves namely multiple ion beams drifting perpendicular to the magnetic field.     

Spatial distribution of dust deposition within a small drainage basin: Implications for loess deposits in the Negev Desert

Loessial colluvial sediments and aeolian aprons are common deposits in the Negev Desert Highlands. In an attempt to monitor the amounts and distributional pattern of loess, monthly dust measurements were carried out during 2004 to 2006 in 10 cm diameter traps located at 18 stations along four slopes, north‐facing, south‐facing, east‐facing and west‐facing in a second‐order drainage basin near Sede Boqer, Negev Desert Highlands, Israel. Annual total dust depositions ranged between 110 g and 178 g m^?2 with an average of 151·1 g m^?2. The average annual dust deposition in the catchment was 23·5% higher than the average amount recorded at the hilltops (122·4 g m^?2) and may be a consequence of sheltering opportunities in the hilly topography. When analysed according to season and aspect, significantly higher monthly amounts were received during the wet rainy season of December to March (17·0 g m^?2), in comparison with the rest of the year (8·1 g m^?2). As for the aspect, while no significant differences characterized north‐facing and south‐facing slopes, east‐facing slopes received significantly higher amounts (by 43·3%) than west‐facing slopes, pointing to preferential dust deposition at the leeward slope. Concurring with the classical model that anticipates higher dust deposition at the leeside slope, but in disagreement with some reports published in the literature, the findings of this study were also supported by a field survey that showed preferential loess accumulation at the eastern and north‐eastern aspects. These findings may shed light on distributional patterns of colluvial sediments and aeolian aprons in the Negev, on soil‐forming processes and on past cycles of dust deposition.     

Water Content Ratio: An Effective Substitute for Liquidity Index for Prediction of Shear Strength of Clays

Undrained shear strength of saturated clays is a very important property in geo-technical engineering practice. Since the collection of undisturbed samples and testing the same is difficult task and time consuming process, any attempt to obtain correlations between shear strength and consistency limits would be highly desirable. Several attempts have been made in the past to correlate shear strength with Liquidity index. The computation of Liquidity index involves the value of plastic limit determined by Casagrande thread rolling method; but the determination of the same is relatively a difficult task in geotechnical engineering practice especially so in less plastic soils. It has been shown that a good linear correlation exists between log of shear strength and water content ratio (ratio of water content to liquid limit). With the help of numerous experimental results, it could be established that water content ratio could replace the well-known parameter liquidity index to predict shear strength. This enables to eliminate the determination of the plastic limit. The relation between water content ratio and liquidity index depends on the liquid limit to plastic limit ratio, irrespective of the geological origin of the soil.     

Efficient management of e-wastes

Electricals and electronic equipments that have reached its utilization period are disposed by the consumer are considered as e-waste. The categories of e-waste range from household appliances to machines used in offices and consumer goods. The rise in problem is due to scarcity of proper place for disposing the e-wastes. Hence, the wastes are disposed in open landfills by the consumers which lead to direct reaction of the e-waste with the environment. The release of harmful toxins and chemicals by the e-wastes causes hazardous effects on living beings. Several processes are introduced in recycling and recovering the harmful metals present in the electronic equipments. The most important reasons for e-waste recycling are waste removal as well as recovery of valuable materials present in the waste. Developed countries such as USA and UK follow some strict rules and regulations about managing the increasing amount of e-wastes, whereas India still needs to have a rigid law for the e-waste management. Prior recycling and recovering the important metals from electronic wastes, it is crucial to ascertain the amount of the metal present in the e-waste. Plastics followed by metals are the main components found in electronic wastes. Hazardous metals such as copper, lead and cadmium are predominant in almost all kinds of e-wastes. Determination of the components present in the electronic wastes guides for the proper path to be followed for recovering the components from the wastes. The review deals with status of e-waste across the world and methods of recovery and management.     

Direct measurement of the meridional circulation in the stratosphere during the IGY

Summary In this study the horizontal component of the meridional circulation at the 100, 50 and 30 mb levels in the stratosphere is computed for the IGY period July 1957 through June 1958. Radiosonde data from approximately 240 stations, well distributed over the northern hemisphere, are used in the analysis of the north-south component of the wind. Values of the mean meridional circulation for the four seasons are presented at every 5° latitude from the equator to 80°N.In the annual average at 100 mb an apparent three cell pattern is obseered, consisting of a region of strong poleward motion north of 55°N, equatorward motion from 15° to 55°N and weak poleward motion from 0° to 15°N. In the annual averages at 50 and 30 mb poleward motions appear only at high latitudes and diminsih in strength with height. Equatorward motions dominate at 30 mb. A maximum value of the mean meridional circulation of +60 cm sec^–1 is found at 100 mb at 70°N.

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Zusammenfassung In dieser Untersuchung ist für die 100-, 50- und 30 mb-Niveaus die horizontale Komponente der meridionalen Zirkulation in der Stratosphäre im internationalen geophysikalischen Jahr (Juli 1957 bis Juni 1958) berechnet worden. Es werden dabei Radiosonden-Daten von etwa 240 Stationen, die über die nördliche Hemisphäre gut verteilt sind, für die Analyse der Nord-Süd-Windkomponente verwendet. Für jeden fünften Breitengrad vom Äquator bis 80°N werden Werte der durchschnittlichen Meridionalkomponente der Zirkulation für die vier Jahreszeiten mitgeteilt.Im Jahresdurchschnitt zeigt sich im 100 mb-Niveau eine Verteilung der Meridionalkomponente, die anscheinend einem aus drei Zellen bestehenden Zirkulationssystem entspricht, wobei nördlich von 55°N eine starke polwärts gerichtete Bewegung, zwischen 15° und 55°N eine Strömung gegen den Äquator und zwischen 0° und 15°N wieder eine schwache polwärts gerichtete Strömung besteht. In den Jahresdurchschnittswerten aus den Niveaus der 50- und 30 mb-Flächen sind polwärts gerichtete Strömungskomponenten nur in hohen geographischen Breiten festzustellen, die mit zunehmender Höhe an Stärke abnehmen. Im Niveau von 30 mb herrscht eine zum Äquator hin gerichtete Meridionalkomponente der Strömung vor. Ein Maximalwert der durchschnittlichen meridionalen Zirkulation von +60 cm sec^–1 wurde in der 100 mb-Höhenlage bei 70°N festgestellt.

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Résumé Dans cette étude, la composante horizontale de la circulation méridionale dans la stratosphère aux niveaux de 100, 50 et 30mb est calculée pour la période de Juillet 1957au Juin 1958 pour l'Année Géophysique Internationale. Les données de radiosondage d'environ 240 stations bien réparties sur l'hémisphère du nord sont employées dans l'analyse de la composante nord-sud du vent. Les valeurs de la circulation moyenne méridionale des quatre saisons sont présententées pour tous les 5° de latitude de l'équateur jusqu'à 80°N.En moyenne d'un an, on peut apparemment observer, à 100mb, une distribution en trois cellules consistant d'une région de mouvement fort vers le pôle au nord de 55°N, d'un mouvement vers l'équateur de 15° à 55°N et d'un mouvement faible vers le pôle de 0° à 15° N. A 50 et 30 mb en moyenne d'un an des mouvements vers le pôle apparaissent seulement dans les hautes altitudes et ils diminuent en force suivant la hauteur. Dans le niveau de 30 mb, c'est un mouvement vers l'équateur qui domine. Use valeur maxima de la circulation méridionale moyenne de +60 cm·sec^–1 a été constatée à 100 mb à 70°N.

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With 6 Figures

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The research reported in this paper has been made possible through the support of the Atomic Energy Commission and of the Geophysics Research Directorate of the U.S. Air Force under contracts No. At (30-2) 2241 and 19(604)-5223.     

Lateglacial and Holocene palaeoenvironments at Sierra La Madera,northwestern Mexico: Sharp signals of Younger Dryas and North American monsoon

During the last glacial termination, the climate system experienced intense global variations whose causes and impacts are not fully defined, particularly for low latitudes. The northwestern Mexico Sky Islands present a climate-sensitive ideal setting to record palaeoecological and palaeoclimatic changes due to their physiographic complexity and location in the ecotone between temperate and tropical ecosystems. High-resolution pollen analysis and a detailed sedimentological study were conducted at the Ciénega Tonibabi tropical thorn scrub site. The 15 540–0 cal a bp nearly continuous record shows that the North Atlantic Ocean did have a cold and humid climatic influence during the glacial stages of the end of the Pleistocene, including a sharp pulse during the Younger Dryas. However, a shift to the Pacific Ocean influence occurred during the Holocene, which led to the development of the El Niño conditions prevailing today. Colder and warmer phases follow one another with higher or lower winter precipitation, including a sharp Bølling–Allerød and development and intensification of the North American monsoon. They are reflected in hydrological changes as well as in the advances, retreats and intermingling of coniferous forests and tropical thorn scrub.