Migration as a phenomenon and process of population change

This paper relates migration with population growth and economic development. Migration affects both production and consumption; it should therefore be considered at the household-family level and analyzed within the utility maximization model. 1 determinant of internal migration is population pressure on land. Migration in the agricultural sector can provide resources to be reinvested in physical capital for agricultural technological change. Usually the agricultural family sends the maturing son to the city because of his better skills and education than other family members. Migrants are among the first to obtain newly created jobs or displace less qualified workers from existing jobs. Thus, migration initially causes disequilibrium, but since it supports technological improvement on the farms, it becomes an equilibriating mechanism. Migration rates are highest in villages where land is most unequally divided. Some of the main noneconomic determinants of migration include social conflicts, religious outbursts and movements, violence, wars, pestilence, epidemics, caste conflicts, political and ideological differences, and climatic unsuitability. Migration and fertility need to be analyzed at the family level rather than at the societal or micro level.     

Segmentation-based classification of hyperspectral imagery using projected and correlation clustering techniques

A partitional clustering-based segmentation is used to carry out supervised classification for hyperspectral images. The main contribution of this study lies in the use of projected and correlation partitional clustering techniques to perform image segmentation. These types of clustering techniques have the capability to concurrently perform clustering and feature/band reduction, and are also able to identify different sets of relevant features for different clusters. Using these clustering techniques segmentation map is obtained, which is combined with the pixel-level support vector machines (SVM) classification result, using majority voting. Experiments are conducted over two hyperspectral images. Combination of pixel-level classification result with the segmentation maps leads to significant improvement of accuracies in both the images. Additionally, it is also observed that, classified maps obtained using SVM combined with projected and correlation clustering techniques results in higher accuracies as compared to classified maps obtained from SVM combined with other partitional clustering techniques.     

Rb-Sr geochronology of the Kulu-Mandi Belt: Its implications for the Himalayan Tectogenesis

The Rb-Sr geochronology of the Kulu-Mandi Belt brings to light the significant fact that the Himalaya can not be regarded as outcome of a single Upper Cretaceous — Tertiary Himalayan Orogeny. Granitic rocks as old as 500 to 600 m.y. exist in the Lesser and Central Himalaya of this belt. They were formed during the Assyntian Orogenic cycle when a protoform of the Central Crystalline Axis was developed. Geosynclinal basic magmatism is more than 600 m.y. old. There is ample geological and geochronological evidence for the Hercynian Epeirogeny. The 10 to 75 m.y. Rb-Sr and K-Ar mineral dates indicate the effect of the Himalayan Orogeny. These results have far reaching implications for tectogenesis of the Himalaya all of which cannot be attributed to the Himalayan Orogeny, underthrusting of the Indian Peninsular Shield below Tethys and continental movements of the Upper Cretaceous — Tertiary times.

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Zusammenfassung Rb-Sr-Altersbestimmungen des Kulu-Mandi-Gürtels zeigen, daß der Himalaya nicht als Ergebnis einer Oberkreide/Tertiär-Orogenese angesehen werden kann. Granitische Gesteine, die etwa 500 bis 600 Millionen Jahre alt sind, gibt es im unteren und im zentralen Himalaya. Sie entstanden während der assyntischen Orogenese als eine Protoform der zentralen kristallinen Achse. Geosynklinaler basischer Magmatismus ist mehr als 600 Millionen Jahre alt. Es gibt genug geologische sowie geochronologische Beweise für eine hercynische Epirogenese. Alter von 10 bis 75 Millionen Jahren (Rb-Sr und K-Ar) deuten den Einfluß der Himalaya-Orogenese an. Diese Ergebnisse haben große Bedeutung für die Tektogenese des Himalaya. Die Unterschiebung (underthrusting) des indischen Subkontinentes (Indian Peninsular Shield) unter die Tethys wurde durch kontinentale Bewegungen der Oberkreide/Tertiär-Periode verursacht.

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Résumé La géochronologie Rb-Sr de la Kulu-Mandi Belt met en lumière ce fait significatif qu'on ne peut pas considérer l'Himalaya comme résultant d'une seule orogénie Crétacé supérieur — Tertiaire. Des roches granitiques de 500–600 M.a. existent dans l'Himalaya inférieur et central. Elles se sont formées pendant l'orogenèse assyntienne comme une »Protoforme« de l'Axe Crystallin Central. Le magmatisme géosynclinal basique date de plus de 600 M.a. Il y a suffisamment de preuves géologiques et géochronologiques pour une épeirogénie hercynienne. Des âges de 10 à 75 M.a. (Rb-Sr et K-Ar) indiquent l'influence de l'Orogénie himalayenne. Ces données ont une grande signification dans la tectogenèse de l'Himalaya. Le sous-charriage de la Péninsule indienne sous le Tethys a été causé par des mouvements continentaux d'âge Crétacé supérieur — Tertiaire.

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OBSERVATIONS ON ESTUARINE FLUID MUD ENTRAINMENT

I. INTRODUCTIONPrediction of mud bed erosion by forcing due to tidal currents usually requires a numerical solution of the advection--dispersion equation for sediment mass transport. Key role is of course played inthis by the bottom boundary conditions defining erosion and deposition fluxes. The issue of erosion isbriefly considered here. noting that it is customary to calculate the rate of erosion as a function of thebed shear stress in excess of the erosion shear strength of the bed (Me…     

Tectonic significance of the young mineral dates and the rates of cooling and uplift in the Himalaya

More than two-thirds of the published K-Ar, Rb-Sr and fission-track mineral dates from the Himalaya lie in the 5–75 m.y. range as a result of metamorphic overprint, uplift and cooling during the Late Cretaceous—Tertiary Himalayan orogeny. In contrast, the few but almost invariably old, Rb-Sr whole-rock ages reveal pre-Tertiary magmaticmetamorphic events.The pattern of distribution of these young dates vis-á-vis geological evidence reveals three phases, of the Himalayan orogeny, viz.: (1) folding and metamorphism (50–75 m.y.); (2) uplift (25–40 m.y.); and (3) major uplift, thrusting, formation of nappe structures, mylonitization and regional retrogression. The maximum concentration of dates in the 10–25 m.y. period marks this paroxysmal phase of the Himalayan orogeny.The Rb-Sr dates of co-existing muscovites and biotites have been used to compute the rates of cooling and uplift. Thus, slow cooling at the rate of about 4°C m.y.⁻¹ from 50 to 25 m.y. and rapid cooling at the rate of 19°-21°C m.y.⁻ from 25 m.y. to present have been inferred. The high rate of cooling over the past 25 m.y. is the result of major uplift at the rate of 0.7–0.8 mm yr⁻¹, which is in conformity with the current rate of uplift obtained from geodetic survey.