10,804 research outputs found
Effects of cosmic rays on single event upsets
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
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
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
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
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
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
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
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
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 gauge fields is constructed
by employing 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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