9,878 research outputs found

    LANDSAT-4 multispectral scanner (MSS) subsystem radiometric characterization

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    The multispectral band scanner (mass) and its spectral characteristics are described and methods are given for relating video digital levels on computer compatible tapes to radiance into the sensor. Topics covered include prelaunch calibration procedures and postlaunch radiometric processng. Examples of current data resident on the MSS image processing system are included. The MSS on LANDSAT 4 is compared with the scanners on earlier LANDSAT satellites

    The gravitational path integral and trace of the diffeomorphisms

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    I give a resolution of the conformal mode divergence in the Euclidean gravitational path-integral by isolating the trace of the diffeomorphisms and its contribution to the Faddeev-Popov measure.Comment: 20 pgs

    Entropic Origin of the Growth of Relaxation Times in Simple Glassy Liquids

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    Transitions between ``glassy'' local minima of a model free-energy functional for a dense hard-sphere system are studied numerically using a ``microcanonical'' Monte Carlo method that enables us to obtain the transition probability as a function of the free energy and the Monte Carlo ``time''. The growth of the height of the effective free energy barrier with density is found to be consistent with a Vogel-Fulcher law. The dependence of the transition probability on time indicates that this growth is primarily due to entropic effects arising from the difficulty of finding low-free-energy saddle points connecting glassy minima.Comment: Four pages, plus three postscript figure

    Stability of the Breached Pair State for a Two-species Fermionic System in the Presence of Feshbach Resonance

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    We investigate the phenomenon of fermionic pairing with mismatched Fermi surfaces in a two-species system in the presence of Feshbach resonance, where the resonantly-paired fermions combine to form bosonic molecules. We observe that the Feshbach parameters control the critical temperature of the gapped BCS superfluid state, and also determine the range over which a gapless breached pair state may exist. Demanding the positivity of the superfluid density, it is shown that although a breached pair state with two Fermi surfaces is always unstable, its single Fermi-surface counterpart can be stable if the chemical potentials of the two pairing species have opposite signs. This condition is satisfied only over a narrow region in the BEC side, characterized by an upper and a lower limit for the magnetic field. We estimate these limits for a mixture of two hyperfine states of 6^6Li using recent experimental data.Comment: 14 pages,5 figure

    The resummed thrust distribution in DIS

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    We present preliminary results on the resummation of leading and next-to-leading logarithms for the thrust distribution in deep inelastic scattering. Our predictions, expanded to O(alpha_s^2), are compared to corresponding results from the Monte Carlo programs DISASTER++ and DISENT.Comment: 5 pages; talk presented by V. Antonelli at the UK Phenomenology Workshop on Collider Physics, September 1999, St. John's College, Durha

    Comparative investigation of the coupled-tetrahedra quantum spin systems Cu2Te2O5X2, X=Cl, Br and Cu4Te5O12Cl4

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    We present a comparative study of the coupled-tetrahedra quantum spin systems Cu2Te2O5X2, X=Cl, Br (Cu-2252(X)) and the newly synthesized Cu4Te5O12Cl4 (Cu-45124(Cl)) based on ab initio Density Functional Theory calculations. The magnetic behavior of Cu-45124(Cl) with a phase transition to an ordered state at a lower critical temperature Tc_c=13.6K than in Cu-2252(Cl) (Tc_c=18K) can be well understood in terms of the modified interaction paths. We identify the relevant structural changes between the two systems and discuss the hypothetical behavior of the not yet synthesized Cu-45124(Br) with an ab initio relaxed structure using Car-Parrinello Molecular Dynamics.Comment: 2 pages, 1 figure; submitted to Proceedings of M2S-HTSC VIII, Dresden 200

    Identification of Risk Factors in Globally Outsourced Software Projects using Logistic Regression and ANN

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    Abstract Global supply chains are often critically dependent upon globally outsourced Information Technology (IT) and Business Process Outsourcing (BPO) projects. Effective risk assessment and mitigation of these projects is therefore of great importance for such supply chains. Traditional risk management techniques used so far in IT and BPO projects have depended almost entirely on the Expected Utility Theory that computes risk exposure as the product of risk probability and risk impact. Although this method is considered the gold standard in risk assessment, it has severe limitations due to the fact that accurate computation of risk probability and impact is difficult. In this and earlier papers, we have advocated the use of risk factors in conjunction with other existing methods for risk assessment. Risk factors are conditions that affect project performance. In this paper, we use Logistic Regression and Artificial Neural Network (ANN) based methods on a set of globally outsourced projects to predict project performance and to rank the relative importance of project risk factors. Although in this paper these techniques have been tested in outsourced IT projects, these can also be used in identifying and determining project risk factors in other industries. Keywords Outsourced projects, Risk Management, Risk Factors, Logistic Regression, Artificial Neural Network

    Extended Self-similarity in Kinetic Surface Roughening

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    We show from numerical simulations that a limited mobility solid-on-solid model of kinetically rough surface growth exhibits extended self-similarity analogous to that found in fluid turbulence. The range over which scale-independent power-law behavior is observed is significantly enhanced if two correlation functions of different order, such as those representing two different moments of the difference in height between two points, are plotted against each other. This behavior, found in both one and two dimensions, suggests that the `relative' exponents may be more fundamental than the `absolute' ones.Comment: 4 pages, 4 postscript figures included (some changes made according to referees' comments. accepted for publication in PRE Rapid Communication

    Spatiotemporal rheochaos in nematic hydrodynamics

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    Motivated by the observation of rheochaos in sheared wormlike micelles [Bandyopadhyay et al., Phys. Rev. Lett, 84 2022, (2000); Europhys. Lett. 56, 447 (2001); Pramana 53, 223 (1999)] we study the coupled nonlinear partial differential equations for the hydrodynamic velocity and order parameter fields in a sheared nematogenic fluid. In a suitable parameter range, we find irregular, dynamic shear-banding and establish by decisive numerical tests that the chaos we observe in the model is spatiotemporal in nature.Comment: Slight changes in text, references and Fig. 5 inset; 6 eps figures (figs 2,3,4 at lower resolution to reduce file size; full files available on request); accepted for publication in Phys Rev Let
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