10,804 research outputs found

    Effects of cosmic rays on single event upsets

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    Assistance was provided to the Brookhaven Single Event Upset (SEU) Test Facility. Computer codes were developed for fragmentation and secondary radiation affecting Very Large Scale Integration (VLSI) in space. A computer controlled CV (HP4192) test was developed for Terman analysis. Also developed were high speed parametric tests which are independent of operator judgment and a charge pumping technique for measurement of D(sub it) (E). The X-ray secondary effects, and parametric degradation as a function of dose rate were simulated. The SPICE simulation of static RAMs with various resistor filters was tested

    Initial states and infrared physics in locally de Sitter spacetime

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    The long wavelength physics in a de Sitter region depends on the initial quantum state. While such long wavelength physics is under control for massive fields near the Hartle-Hawking vacuum state, such initial states make unnatural assumptions about initial data outside the region of causal contact of a local observer. We argue that a reasonable approximation to a maximum entropy state, one that makes minimal assumptions outside an observer's horizon volume, is one where a cutoff is placed on a surface bounded by timelike geodesics, just outside the horizon. For sufficiently early times, such a cutoff induces secular logarithmic divergences with the expansion of the region. For massive fields, these effects sum to finite corrections at sufficiently late times. The difference between the cutoff correlators and Hartle-Hawking correlators provides a measure of the theoretical uncertainty due to lack of knowledge of the initial state in causally disconnected regions. These differences are negligible for primordial inflation, but can become significant during epochs with very long-lived de Sitter regions, such as we may be entering now.Comment: 19 pages, 4 figures, references adde

    The Performance of Alfalfa Synthetics in the First and Advanced Generations

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    During alfalfa breeding investigations conducted at the Nebraska Agricultural Experiment Station, numerous superior clones were selected and tested as clones, and in polycross progeny tests. Information was needed on the performance of synthetic varieties in the first and advanced generations, on the optimum number of clones to include in a synthetic variety, and on parent-progeny relationships. Clones with high general combining ability for forage yield as measured by polycross progeny tests, and in certain instances specific combining ability based on single-cross tests, were intercrossed in various ways to produce synthetic varieties. A group of synthetics varying in number of parents from 2 to 6 clones, having in some instances certain clones as common parents, was tested initially in the first generation of synthesis (referred to as Syn-1 from here on), later in the Syn-1 versus the Syn-2, and in some instances in the Syn-1, Syn-2, and Syn-3, and ultimately in the Syn-1,-2,-3, and -4 generations. The purposes of this bulletin are to report (1) comparative results obtained in yield trials involving the Syn-1,-2,-3, and -4 generations of 5 two-clone and 14 multiple-clone synthetics at Lincoln, Nebraska, and Ithaca, New York, and (2) parent-progeny relationships

    Modifying the Einstein Equations off the Constraint Hypersuface

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    A new technique is presented for modifying the Einstein evolution equations off the constraint hypersurface. With this approach the evolution equations for the constraints can be specified freely. The equations of motion for the gravitational field variables are modified by the addition of terms that are linear and nonlocal in the constraints. These terms are obtained from solutions of the linearized Einstein constraints.Comment: 4 pages, 1 figure, uses REVTe

    Extracting Spooky-activation-at-a-distance from Considerations of Entanglement

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    Following an early claim by Nelson & McEvoy \cite{Nelson:McEvoy:2007} suggesting that word associations can display `spooky action at a distance behaviour', a serious investigation of the potentially quantum nature of such associations is currently underway. This paper presents a simple quantum model of a word association system. It is shown that a quantum model of word entanglement can recover aspects of both the Spreading Activation equation and the Spooky-activation-at-a-distance equation, both of which are used to model the activation level of words in human memory.Comment: 13 pages, 2 figures; To appear in Proceedings of the Third Quantum Interaction Symposium, Lecture Notes in Artificial Intelligence, vol 5494, Springer, 200

    AdS/CFT and the Information Paradox

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    The information paradox in the quantum evolution of black holes is studied within the framework of the AdS/CFT correspondence. The unitarity of the CFT strongly suggests that all information about an initial state that forms a black hole is returned in the Hawking radiation. The CFT dynamics implies an information retention time of order the black hole lifetime. This fact determines many qualitative properties of the non-local effects that must show up in a semi-classical effective theory in the bulk. We argue that no violations of causality are apparent to local observers, but the semi-classical theory in the bulk duplicates degrees of freedom inside and outside the event horizon. Non-local quantum effects are required to eliminate this redundancy. This leads to a breakdown of the usual classical-quantum correspondence principle in Lorentzian black hole spacetimes.Comment: 16 pages, harvmac, reference added, minor correction

    A soil-landscape model for Mahurangi Forest, Northland, New Zealand

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    Exotic plantation forestry is an important land use of both economic and environmental significance in Northland and elsewhere in New Zealand. It is therefore of considerable importance that forestlands be managed sustainably by employing approaches such as site-specific management. The establishment of site-specific forest management practices requires information regarding the distribution of key soil properties (Turvey and Poutsma, 1980). Quantitative modelling to predict key soil properties from landscape features may be an effective approach to mapping forestlands. A study investigating the efficacy of such an approach is being conducted within Mahurangi Forest, Northland, New Zealand. As a pilot to the study, a detailed qualitative soil-landscape model was developed in order to gain a greater understanding of the soil-landscape relationships and soil pattern of the area. The qualitative soil-landscape model developed in the pilot study is presented here

    A soil-landscape model for southern Mahurangi Forest, Northland

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    Exotic plantation forestry has a productive area of about 75 000 ha in Northland (L. Cannon, personal communication). Forestry is thus an important land use of both economic and environmental significance in Northland as well as elsewhere in New Zealand. Therefore, it is of considerable importance that forestlands be managed sustainably by employing approaches such as site-specific management. The establishment of site-specific forest management practices requires information regarding the distribution of key soil properties (Turvey and Poutsma, 1980). Quantitative modelling to predict key soil properties of sustainable forestry from observable landscape features may be a cost-effective approach to mapping forestlands. We are investigating the efficacy of such an approach within Mahurangi Forest, Northland

    Taub--NUT Dyons in Heterotic String Theory

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    Starting with the Taub--NUT solution to Einstein's equations, together with a constant dilaton, a dyonic Taub--NUT solution of low energy heterotic string theory with non--trivial dilaton, axion and U(1)U(1) gauge fields is constructed by employing O(1,1)O(1,1) transformations. The electromagnetic dual of this solution is constructed, using SL(2,\rline) transformations. By an appropriate change to scaled variables, the extremal limit of the dual solution is shown to correspond to the low energy limit of an exact conformal field theory presented previously.Comment: 16 pages (plain TEX), (Revised version has curvature singularities correctly identified), IASSNS-HEP-94/50, McGill/94-2
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