36,224 research outputs found

    On the unlikelihood of specific long range forces in immunologic and enzymatic reactions

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    In the past few years, a great many experiments have been performed by Rothen (24, 25) which he has interpreted as suggesting that antigen and antibody, and enzyme and substrate proteins, can react specifically, although separated by distances of hundreds of angstroms. This hypothesis seems to conflict with evidence accumulated from many other investigations indicating that short range interactions, involving distances usually associated with electrostatic and van der Waals’ forces, and hydrogen bonds, of the order of 5 A, operate in these reactions. We have therefore engaged in a critical analysis of the experimental techniques used by Rothen to determine whether some interpretation other than that invoking the existence of specific long range forces could be found to explain his experimental results

    Comments on Ringwood's paper 'Petrogenesis of Apollo 11 basalts and implications for lunar origin'

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    Apollo 11 basalt petrogenesis and theories of lunar evolution comparing lunar and earth environment

    Magnification of starting torques of dc motors by maximum power point trackers in photovoltaic systems

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    Direct current (dc) motors are used in terrestrial photovoltaic (PV) systems such as in water-pumping systems for irrigation and water supply. Direct current motors may also be used for space applications. Simple and low weight systems including dc motors may be of special interest in space where the motors are directly coupled to the solar cell array (with no storage). The system will operate only during times when sufficient insolation is available. An important performance characteristic of electric motors is the starting to rated torque ratio. Different types of dc motors have different starting torque ratios. These ratios are dictated by the size of solar cell array, and the developed motor torque may not be sufficient to overcome the load starting torque. By including a maximum power point tracker (MPPT) in the PV system, the starting to rated torque ratio will increase, the amount of which depends on the motor type. The starting torque ratio is calculated for the permanent magnet, series and shunt excited dc motors when powered by solar cell arrays for two cases: with and without MPPT's. Defining a motor torque magnification by the ratio of the motor torque with an MPPT to the motor torque without an MPPT, a magnification of 3 was obtained for the permanent magnet motor and a magnification of 7 for both the series and shunt motors. The effect of the variation of solar insolation on the motor starting torque was covered. All motor types are less sensitive to insolation variation in systems including MPPT's as compared to systems with MPPT's. The analysis of this paper will assist the PV system designed to determine whether or not to include an MPPT in the system for a specific motor type

    Loop algebras, gauge invariants and a new completely integrable system

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    One fruitful motivating principle of much research on the family of integrable systems known as ``Toda lattices'' has been the heuristic assumption that the periodic Toda lattice in an affine Lie algebra is directly analogous to the nonperiodic Toda lattice in a finite-dimensional Lie algebra. This paper shows that the analogy is not perfect. A discrepancy arises because the natural generalization of the structure theory of finite-dimensional simple Lie algebras is not the structure theory of loop algebras but the structure theory of affine Kac-Moody algebras. In this paper we use this natural generalization to construct the natural analog of the nonperiodic Toda lattice. Surprisingly, the result is not the periodic Toda lattice but a new completely integrable system on the periodic Toda lattice phase space. This integrable system is prescribed purely in terms of Lie-theoretic data. The commuting functions are precisely the gauge-invariant functions one obtains by viewing elements of the loop algebra as connections on a bundle over S1S^1

    Nonpecuniary Class Action Settlements

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    Miller and Singer offer a theoretical and empirical analysis of nonpecuniary class action settlements, including coupons, securities and fluid recoveries

    Starting characteristics of direct current motors powered by solar cells

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    Direct current motors are used in photovoltaic systems. Important characteristics of electric motors are the starting to rated current and torque ratios. These ratios are dictated by the size of the solar cell array and are different for the various dc motor types. Discussed here is the calculation of the starting to rated current ratio and starting to rated torque ratio of the permanent magnet, and series and shunt excited motors when powered by solar cells for two cases: with and without a maximum-power-point-tracker (MPPT) included in the system. Comparing these two cases, one gets a torque magnification of about 3 for the permanent magnet motor and about 7 for other motor types. The calculation of the torques may assist the PV system designer to determine whether or not to include an MPPT in the system
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