Utility of remotely sensed data for identification of soil conservation practices

Discussed are a variety of remotely sensed data sources that may have utility in the identification of conservation practices and related linear features. Test sites were evaluated in Alabama, Kansas, Mississippi, and Oklahoma using one or more of a variety of remotely sensed data sources, including color infrared photography (CIR), LANDSAT Thematic Mapper (TM) data, and aircraft-acquired Thermal Infrared Multispectral Scanner (TIMS) data. Both visual examination and computer-implemented enhancement procedures were used to identify conservation practices and other linear features. For the Kansas, Mississippi, and Oklahoma test sites, photo interpretations of CIR identified up to 24 of the 109 conservation practices from a matrix derived from the SCS National Handbook of Conservation Practices. The conservation practice matrix was modified to predict the possibility of identifying the 109 practices at various photographic scales based on the observed results as well as photo interpreter experience. Some practices were successfully identified in TM data through visual identification, but a number of existing practices were of such size and shape that the resolution of the TM could not detect them accurately. A series of computer-automated decorrelation and filtering procedures served to enhance the conservation practices in TM data with only fair success. However, features such as field boundaries, roads, water bodies, and the Urban/Ag interface were easily differentiated. Similar enhancement techniques applied to 5 and 10 meter TIMS data proved much more useful in delineating terraces, grass waterways, and drainage ditches as well as the features mentioned above, due partly to improved resolution and partly to thermally influenced moisture conditions. Spatially oriented data such as those derived from remotely sensed data offer some promise in the inventory and monitoring of conservation practices as well as in supplying parameter data for a variety of computer-implemented agricultural models

Applications of TIMS data in agricultural areas and related atmospheric considerations

While much of traditional remote sensing in agricultural research was limited to the visible and reflective infrared, advances in thermal infrared remote sensing technology are adding a dimension to digital image analysis of agricultural areas. The Thermal Infrared Multispectral Scanner (TIMS) an airborne sensor having six bands over the nominal 8.2 to 12.2 m range, offers the ability to calculate land surface emissivities unlike most previous singular broadband sensors. Preliminary findings on the utility of the TIMS for several agricultural applications and related atmospheric considerations are discussed

3-d resistive MHD simulations of magnetic reconnection and the tearing mode instability in current sheets

Magnetic reconnection plays a critical role in many astrophysical processes where high energy emission is observed, e.g. particle acceleration, relativistic accretion powered outflows, pulsar winds and probably in dissipation of Poynting flux in GRBs. The magnetic field acts as a reservoir of energy and can dissipate its energy to thermal and kinetic energy via the tearing mode instability. We have performed 3d nonlinear MHD simulations of the tearing mode instability in a current sheet. Results from a temporal stability analysis in both the linear regime and weakly nonlinear (Rutherford) regime are compared to the numerical simulations. We observe magnetic island formation, island merging and oscillation once the instability has saturated. The growth in the linear regime is exponential in agreement with linear theory. In the second, Rutherford regime the island width grows linearly with time. We find that thermal energy produced in the current sheet strongly dominates the kinetic energy. Finally preliminary analysis indicates a P(k) 4.8 power law for the power spectral density which suggests that the tearing mode vortices play a role in setting up an energy cascade.Comment: 4 pages, 8 figures, accepted for publication in the International Journal of Modern Physics D, proceedings of HEPRO meeting, held in Dublin, in September 200

Trois bicentenaires : Hume, Condillac, Smith. Adam Smith entre le marginalisme et le marxisme

It is not easy to understand why, and how, orthodox economists who do not believe either in the labor-theory or in the cost-theory of value, continue to favor Adam Smith's Wealth of Nations, but forget such economists as Condillac, whose value theory is nearer to theirs and whose bicentenary we also commemorate.Adam Smith, it is submitted, is still interesting but for reasons far enough from orthodox economic theory. Smith is in fact, according to some recent interpretations, more of a welfare economist, concerned with moral values, than a partial analysis economist: his theory of value derives from ethical considerations following Hume and keeps its normative flavor throughout instead of being solely a tentative explanation of prices. Some apparently contradictory assertions about value could thus be reconciled in a unifying theory, as explained by such authors as Lindgren (1973) or Rieseman (1976).If it is possible to reconcile many apparently contradictory views in Adam Smith's works, thanks to a more holistic approach, it is suggested that a similar approach could be applied to a more controversial economist, Karl Marx, whose career may be compared to that of Smith in many respects

L’entrepreneur dans la pensée économique : l’originalité méconnue de Turgot

Cette note remonte jusqu’à Léon Say en 1877 pour déceler une erreur répétée par Schumpeter et des auteurs contemporains qui négligent d’attribuer à A.-R.-J. Turgot la priorité dans la distinction entre capitalistes et entrepreneurs. Quelque cinquante ans avant Jean-Baptiste Say, Turgot avait explicité cette distinction, logiquement et historiquement, en se fondant sur l’absentéisme graduel de la classe des propriétaires dans la montée du capitalisme. La distinction se trouve à l’article LXX des Réflexions.This note pretends that because of an error going back at least to Léon Say (1877) and repeated by Schumpeter and contemporary authors, the priority of the 1766 "Reflexions..." of A.R.J. Turgot on the distinction between the capitalist and the entrepreneur is neglected. Some fifty years before Jean-Baptiste Say, Turgot made clear that distinction, which came logically and historically for him from the gradual absenteeism of the class of proprietors during the rise of capitalism. The distinction is found in Reflexion LXX

Théorie du bien-être et politique économique

After facing disappearance during the thirties, under the well known attack by Lionel Robbins and other economists, theoretical welfare economics seems to be more and more in use in spite of still shaky foundations. The concept of surplus, the measurement of preferences and the economic welfare function are apparently among the most promising approaches. Welfarists like Tinbergen and Bergson are not so far now from known anti-welfarists like Robbins and Myrdal. However, the issue of the debate between Pigou and Robbins has to be reconsidered before we can use welfare theory. New methodological arguments are presented that try to separate the shaft from the weed in the thesis of Pigou and Robbins. Some errors are found that have remained alive up to now. After a new light is shed on the controversy, it is fairly easy reconcile Pigou, Robbins, Bergson, Myrdal and Tinbergen. It is fortunate that we can reach such a consensus because the theory of economic policy badly needs renewed foundations to be able to cope with changing values, new patterns of distribution and other long range problems. A fresh start with the questions raised by welfare economics should ease the way towards these goals

Retour à Adam Smith (1723-1790) après deux siècles?

Après un survol des appréciations courantes de l’analyse économique de Smith, on souligne l’intérêt actuel marqué pour la totalité du système incluant d’autres niveaux comme l’histoire, la sociologie et l’éthique. Le plus intéressant de Smith pour les années à venir semble résider bien plus dans ses positions éthiques que dans son analyse économique. En fait, le principal problème pendant actuellement est celui d’une éthique acceptable de la répartition, qui ne semble résider ni dans les théories déontologiques, ni dans l’utilitarisme, mais quelque part entre les deux, comme nous convainc facilement un rapide coup d’oeil sur les positions récentes allant de Hare à Sen en passant par Rawls. La priorité accordée par Smith à d’autres motifs de deux sortes et à deux niveaux au lieu de l’utilité nous donne enfin une vision alternative à l’utilitarisme grâce à des prémisses qui appartiennent maintenant à trois niveaux de généralité et d’universalité. À cause de son naturalisme, cependant, Smith ne nous offre pas de suggestions précises pour expliciter ce système et nous permettre enfin une méthode pour souder n’importe quel système philosophique et pas seulement l’utilitarisme à la théorie économique.After a review of current assessments of Smithian economics, the author stresses the interest of the entire system at historical, sociological and ethical levels. The renewed interest in Smith comes from his ethical positions rather than from his skills as an economic analyst. The solution to the vexing problem of ever finding an acceptable ethics in distribution theory seems to be found somewhere between utilitarian and deontological theories. But neither of these two theories alone succeeds in doing so, as one is easily convinced from a short survey of the existing literature ranging from Hare to Rawls and then to Sen. The priority given by Smith to motives of two kinds at two levels different from utility permits one to have an alternative view to utilitarianism for kinds of ethical premises which belong to three levels of generalization and universalization. His naturalism does not permit one to go very far in that direction however, and much work has still to be done to bridge economics to philosophical systems other than, and distinct from, utilitarianism