The aryans and the ancient system of caste

Over the last century or two, the dominant accounts of the caste system have looked for its roots in the ancient history of India. More precisely scholars have linked the origin of the caste system to the invasion of a Sanskrit speaking people, the Aryans, who are said to have imposed their language, religion and social structure on an indigenous population called the Dravidians. In this account, the latter were subjugated by the Aryans and made to have an inferior place in society as the lowest caste. Given the importance of the Aryan invasion theory in our understanding of the caste system this article looks into the literature on how this invasion and subjugation actually took place and what evidence is available for it. This analysis leads to the conclusion that hardly any or no evidence exists for the claim that the caste system originated as the result of an Aryan invasion. Subsequently, the article looks into the development of this account in the early nineteenth century European literature in order to see on what this account was based and to identify the background assumptions that make it appear plausible till today.Over the last century or two, the dominant accounts of the caste system have looked for its roots in the ancient history of India. More precisely scholars have linked the origin of the caste system to the invasion of a Sanskrit speaking people, the Aryans, who are said to have imposed their language, religion and social structure on an indigenous population called the Dravidians. In this account, the latter were subjugated by the Aryans and made to have an inferior place in society as the lowest caste. Given the importance of the Aryan invasion theory in our understanding of the caste system this article looks into the literature on how this invasion and subjugation actually took place and what evidence is available for it. This analysis leads to the conclusion that hardly any or no evidence exists for the claim that the caste system originated as the result of an Aryan invasion. Subsequently, the article looks into the development of this account in the early nineteenth century European literature in order to see on what this account was based and to identify the background assumptions that make it appear plausible till today

Stellar winds, dead zones, and coronal mass ejections

Axisymmetric stellar wind solutions are presented, obtained by numerically solving the ideal magnetohydrodynamic (MHD) equations. Stationary solutions are critically analysed using the knowledge of the flux functions. These flux functions enter in the general variational principle governing all axisymmetric stationary ideal MHD equilibria. The magnetized wind solutions for (differentially) rotating stars contain both a `wind' and a `dead' zone. We illustrate the influence of the magnetic field topology on the wind acceleration pattern, by varying the coronal field strength and the extent of the dead zone. This is evident from the resulting variations in the location and appearance of the critical curves where the wind speed equals the slow, Alfven, and fast speed. Larger dead zones cause effective, fairly isotropic acceleration to super-Alfvenic velocities as the polar, open field lines are forced to fan out rapidly with radial distance. A higher field strength moves the Alfven transition outwards. In the ecliptic, the wind outflow is clearly modulated by the extent of the dead zone. The combined effect of a fast stellar rotation and an equatorial `dead' zone in a bipolar field configuration can lead to efficient thermo-centrifugal equatorial winds. Such winds show both a strong poleward collimation and some equatorward streamline bending due to significant toroidal field pressure at mid-latitudes. We discuss how coronal mass ejections are then simulated on top of the transonic outflows.Comment: scheduled for Astrophys. J. 530 #2, Febr.20 2000 issue. 9 figures (as 6 jpeg and 8 eps files

Effect of dust on Kelvin-Helmholtz instabilities

Dust is present in a large variety of astrophysical fluids, from tori around supermassive black holes to molecular clouds, protoplanetary discs, and cometary outflows. In many such fluids, shearing flows are present, leading to the formation of Kelvin-Helmholtz instabilities (KHI) and changing the properties and structures of the fluid through processes such as mixing and clumping of dust. We investigate how dust changes the growth rates of the KHI in 2D and 3D and how the it redistributes and clumps dust. We investigate if similarities can be found between the structures in 3D KHI and those seen in observations of molecular clouds. We do this by performing numerical hydrodynamical dust+gas simulations with in addition to gas a number of dust fluids. Each dust fluid represents a portion of the particle size-distribution. We study how dust-to-gas mass density ratios between 0.01 and 1 alter the growth rate in the linear phase of the KHI. We do this for a wide range of perturbation wavelengths, and compare these values to the analytical gas-only growth rates. As the formation of high-density dust structures is of interest in many astrophysical environments, we scale our simulations with physical quantities similar to values in molecular clouds. Large differences in dynamics are seen for different grain sizes. We demonstrate that high dust-to-gas ratios significantly reduce the growth rate of the KHI, especially for short wavelengths. We compare the dynamics in 2D and 3D simulations, where the latter demonstrates additional full 3D instabilities during the non-linear phase, leading to increased dust densities. We compare the structures formed by the KHI in 3D simulations with those in molecular clouds and see how the column density distribution of the simulation shares similarities with log-normal distributions with power-law tails sometimes seen in observations of molecular clouds.Comment: 14 pages, 20 figure

Compositional Model Repositories via Dynamic Constraint Satisfaction with Order-of-Magnitude Preferences

The predominant knowledge-based approach to automated model construction, compositional modelling, employs a set of models of particular functional components. Its inference mechanism takes a scenario describing the constituent interacting components of a system and translates it into a useful mathematical model. This paper presents a novel compositional modelling approach aimed at building model repositories. It furthers the field in two respects. Firstly, it expands the application domain of compositional modelling to systems that can not be easily described in terms of interacting functional components, such as ecological systems. Secondly, it enables the incorporation of user preferences into the model selection process. These features are achieved by casting the compositional modelling problem as an activity-based dynamic preference constraint satisfaction problem, where the dynamic constraints describe the restrictions imposed over the composition of partial models and the preferences correspond to those of the user of the automated modeller. In addition, the preference levels are represented through the use of symbolic values that differ in orders of magnitude

Non-linear dynamics of Kelvin-Helmholtz unstable magnetized jets: three-dimensional effects

A numerical study of the Kelvin-Helmholtz instability in compressible magnetohydrodynamics is presented. The three-dimensional simulations consider shear flow in a cylindrical jet configuration, embedded in a uniform magnetic field directed along the jet axis. The growth of linear perturbations at specified poloidal and axial mode numbers demonstrate intricate non-linear coupling effects. The physical mechanims leading to induced secondary Kelvin-Helmholtz instabilities at higher mode numbers are identified. The initially weak magnetic field becomes locally dominant in the non-linear dynamics before and during saturation. Thereby, it controls the jet deformation and eventual breakup. The results are obtained using the Versatile Advection Code [G. Toth, Astrophys. Lett. Comm. 34, 245 (1996)], a software package designed to solve general systems of conservation laws. An independent calculation of the same Kelvin-Helmholtz unstable jet configuration using a three-dimensional pseudo-spectral code gives important insights into the coupling and excitation events of the various linear mode numbers.Comment: 10 (+7) pages, 6 figures, accepted for Phys. Plasmas 6, to appear 199

Orientalism and the puzzle of the Aryan invasion theory

The origin of the Aryan invasion theory (AIT) is generally located in the discovery of the Indo-European and Dravidian language families. However, these discoveries cannot account for the emergence of the AIT, because the postulation of the invasion preceded the linguistic research. In its search for an alternative account of the cognitive conditions under which this theory could come into being, this article illustrates a particular way of studying the intellectual history of Orientalism. The Orientalist discourse on India is approached as a body of reflections on the western cultural experience of India. This perspective brings us to the thesis that the pre-conditions for the emergence of the AIT lay in the postulation of two entities in the Orientalist discourse on India: the ‘Hindu religion’ and its ‘caste system’. Both these notions and the AIT appeared cogent and coherent to European minds, because they mirrored internal developments within European culture and its intellectual debates, which had given shape to Europe’s experience of India

Numerical simulations of stellar winds: polytropic models

We discuss steady-state transonic outflows obtained by direct numerical solution of the hydrodynamic and magnetohydrodynamic equations. We make use of the Versatile Advection Code, a software package for solving systems of (hyperbolic) partial differential equations. We proceed stepwise from a spherically symmetric, isothermal, unmagnetized, non-rotating Parker wind to arrive at axisymmetric, polytropic, magnetized, rotating models. These represent 2D generalisations of the analytical 1D Weber-Davis wind solution, which we obtain in the process. Axisymmetric wind solutions containing both a `wind' and a `dead' zone are presented. Since we are solving for steady-state solutions, we efficiently exploit fully implicit time stepping. The method allows us to model thermally and/or magneto-centrifugally driven stellar outflows. We particularly emphasize the boundary conditions imposed at the stellar surface. For these axisymmetric, steady-state solutions, we can use the knowledge of the flux functions to verify the physical correctness of the numerical solutions.Comment: 11 pages, 6 figures, accepted for Astron. Astrophys. 342, to appear 199

The Brahmin, the Aryan, and the powers of the priestly class : puzzles in the study of Indian religion

The classical account of the Brahmin priestly class and its role in Indian religion has seen remarkable continuity during the past two centuries. Its core claims appear to remain unaffected, despite the major shifts that occurred in the theorizing of Indian culture and in the study of religion. In this article, we first examine the issue of the power and status of the Brahmin and show how it generates explanatory puzzles today. We then turn to 18th- and 19th-century sources to identify the cognitive conditions which sustained the classical account of the Brahmin priest and allowed for its transmission. Three clusters of concepts were crucial here: Christian-theological ideas concerning heathen priesthood and idolatry; racial notions of biological and cultural superiority and inferiority; and anthropological speculations about ‘primitive man’ and his ‘magical thinking’. While all three clusters were rejected by 20th- and 21st-century scholarship, the related claims about Brahmanical ritual power continue to be presented as facts. What accounts for this peculiar combination of continuities and discontinuities in the study of (ancient) Indian religion? We turn to some insights from the philosophy of science to sketch a route toward answering this question