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1

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Ionospheric measurements of relative coronal brightness during the total solar eclipses of 11 August, 1999 and 9 July, 1945 (2000)

Davis, C. J. ; Lockwood, M. ; Bell, S. A. ; [et al.]

Springer

Annales geophysicae 18 (2000), S. 182-190

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ISSN: 0992-7689

Keywords: Ionosphere (solar radiation and cosmic ray effects) ; Radio science (ionospheric physics) ; Solar physics, astrophysics, and astronomy (corona and transition region)

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract Swept-frequency (1/10 MHz) ionosonde measurements were made at Helston, Cornwall (50°06′N, 5°18′W) during the total solar eclipse on August 11, 1999. Soundings were made every three minutes. We present a method for estimating the percentage of the ionising solar radiation which remains unobscured at any time during the eclipse by comparing the variation of the ionospheric E-layer with the behaviour of the layer during a control day. Application to the ionosonde date for 11 August, 1999, shows that the flux of solar ionising radiation fell to a minimum of 25±2% of the value before and after the eclipse. For comparison, the same technique was also applied to measurements made during the total solar eclipse of 9 July, 1945, at Sörmjöle (63°68′N, 20°20′E) and yielded a corresponding minimum of 16 ± 2%. Therefore the method can detect variations in the fraction of solar emissions that originate from the unobscured corona and chromosphere. We discuss the differences between these two eclipses in terms of the nature of the eclipse, short-term fluctuations, the sunspot cycle and the recently-discovered long-term change in the coronal magnetic field.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s00585-000-0182-z

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2

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Compiling path expressions into VLSI circuits (1986)

Anantharaman, T. S. ; Clarke, E. M. ; Foster, M. J. ; [et al.]

Springer

Distributed computing 1 (1986), S. 150-166

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ISSN: 1432-0452

Keywords: Silicon compilation ; Path expressions ; Process synchronization

Source: Springer Online Journal Archives 1860-2000

Topics: Computer Science

Notes: Abstract Path expressions were originally proposed by Campbell and Habermann [2] as a mechanism for process synchronization at the monitor level in software. Not surprisingly, they also provide a useful notation for specifying the behavior of asynchronous circuits. Motivated by these potential applications we investigate how to directly translate path expressions into hardware. Our implementation is complicated in the case of multiple path expressions by the need for synchronization on event names that are common to more than one path. Moreover, since events are inherently asynchronous in our model, all of our circuits must be self-timed. Nevertheless, the circuits produced by our construction have are proportional to N · log(N) where N is the total length of the multiple path expression under consideration. This bound holds regardless of the number of individual paths or the degree of synchronization between paths. Furthermore, if the structure of the path expression allows partitioning, the circuit can be laid out in a distributed fashion without additional area overhead.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01661169

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3

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Research on Automatic Verification of Finite-State Concurrent Systems (1987)

Clarke, E M ; Grumberg, O

Palo Alto, Calif. : Annual Reviews

Annual Review of Computer Science 2 (1987), S. 269-290

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ISSN: 8756-7016

Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff

Topics: Computer Science

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1146/annurev.cs.02.060187.001413

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4

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Program invariants as fixedpoints (1979)

Clarke, E. M.

Springer

Computing 21 (1979), S. 273-294

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ISSN: 1436-5057

Source: Springer Online Journal Archives 1860-2000

Topics: Computer Science

Description / Table of Contents: Zusammenfassung Es wird dargelegt, daß die Sätze für Widerspruchsfreiheit und Vollständigkeit für Systeme, die auf Floyd-Hoare-Axiomen basieren ([3], [5], [18]), tatsächlich Fixpunktsätze sind. Die Programminvarianten werden als Fixpunkt-Funktionale charakterisiert, die man auf natürliche Weise vom Programmtext herleiten kann. Es wird gezeigt, daß innerhalb des Rahmen dieser Fixpunkttheorie die Ergebnisse bezüglich Widerspruchsfreiheit und Vollständigkeit eine besonders einfache Interpretation besitzen. Die Vollständigkeit eines Floyd-Hoare-Axiomensystems ist äquivalent zur Existenz eines Fixpunktes für eine geeignetes Funktional. Die Widerspruchsfreiheit folgt aus der Maximalität dieses Fixpunktes. Die Funktionale für reguläre Prozedurdeklarationen ähneln Dijkstras Prädikat-Transformern. Für nichtreguläre Rekursionen braucht man eine Verallgemeinerung des Prädikat-Transformer-Konzepts, das hier relationaler Transformer genannt wird.

Notes: Abstract We argue that soundness and relative completeness theorems for Floyd-Hoare Axiom Systems ([3], [5], [18]) are really fixedpoint theorems. We give a characterization of program invariants as fixedpoints of functionals which may be obtained in a natural manner from the text of a program. We show that within the framework of this fixedpoint theory, soundness and relative completeness results have a particularly simple interpretation. Completeness of a Floyd-Hoare Axiom System is equivalent to the existence of a fixedpoint for an appropriate functional, and soundness follows from the maximality of this fixedpoint. The functionals associated with regular procedure declarations are similar to thepredicate transformers of Dijkstra; for nonregular recursions it is necessary to use a generalization of the predicate transformer concept which we call arelational transformer.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02248730

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5

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Exploiting symmetry in temporal logic model checking (1996)

Clarke, E. M. ; Enders, R. ; Filkorn, T. ; [et al.]

Springer

Formal methods in system design 9 (1996), S. 77-104

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ISSN: 1572-8102

Keywords: model checking ; symmetry ; temporal-logic

Source: Springer Online Journal Archives 1860-2000

Topics: Computer Science

Notes: Abstract In practice, finite state concurrent systems often exhibit considerable symmetry. We investigate techniques for reducing the complexity of temporal logic model checking in the presence of symmetry. In particular, we show that symmetry can frequently be used to reduce the size of the state space that must be explored during model checking. In the past, symmetry has been exploited in computing the set of reachable states of a system when the transition relation is represented explicitly [14, 11, 19]. However, this research did not consider arbitrary temporal properties or the complications that arise when BDDs are used in such procedures. We have formalized what it means for a finite state system to be symmetric and described techniques for reducing such systems when the transition relation is given explicitly in terms of states or symbolically as a BDD. Moreover, we have identified an important class of temporal logic formulas that are preserved under this reduction. Our paper also investigates the complexity of various critical steps, like the computation of the orbit relation, which arise when symmetry is used in this type of verification. Finally, we have tested our ideas on a simple cache-coherency protocol based on the IEEE Futurebus + standard.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00625969

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6

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Editorial (1995)

Brayton, R. ; Clarke, E. M. ; Subrahmanyam, P. A.

Springer

Formal methods in system design 6 (1995), S. 5-5

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ISSN: 1572-8102

Source: Springer Online Journal Archives 1860-2000

Topics: Computer Science

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01384311

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7

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Immunocytochemical localization of ingested kidney bean (Phaseolus vulgaris) lectins in rat gut (1980)

King, T. P. ; Pusztai, A. ; Clarke, E. M. W.

Springer

Journal of molecular histology 12 (1980), S. 201-208

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ISSN: 1573-6865

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary The binding of ingested kidney bean (Phaseolus vulgaris) lectins to the luminal surface of the rat gut was investigated by an indirect immunofluorescence method in which the primary antiserum was monospecific for kidney bean globulin lectins. The major lectin-positive sites were found to be the non-crypt regions of villi in the proximal region of the small intestine; exactly the same regions displayed extensive disruption of microvilli. Lectins were not localized in the brush border regions of ileal villi and no microvillus abnormalities were detected in this region of the gut. The luminal surface of the caecum was strongly lectin-positive and here also microvillus disruption was evident. Low levels of lectins were detected on the luminal surface of the colon; no microvillus abnormalities were detected in this region.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01024550

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8

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Atriplex hortensis L. as a leafy vegetable, and as a leaf protein concentrate plant (1983)

Carlsson, Rolf ; Clarke, E. M. Wendy

Springer

Plant foods for human nutrition 33 (1983), S. 127-133

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ISSN: 1573-9104

Keywords: leafy vegetable ; forage ; leaf protein concentrate ; anti-nutritive secondary substances ; in vivo test

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract The quality ofAtriplex hortensis L. (Mountain Spinach) as a leafy vegetable, forage crop, and plant for production of leaf protein/nutrient concentrate was investigated. The plant can substitute or supplementSpinacia oleracea L. as a leafy vegetable, due to similar chemical composition and a higher leaf yield. The whole plant, as a meal, is similar toMedicago sativa L. in chemical composition. It could be suitable for cultivation in dry areas. By wet-fractionation of the plant a leaf protein concentrate can be obtained. The concentrate is well composed, and should lack anti-nutritive substances present in the whole plant.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01091298

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