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Showing papers by "Paul Morris published in 1998"


Journal ArticleDOI
TL;DR: Hyphal germlings were shown to respond chemotropically to daidzein and genistein, suggesting that hyphal tips from zoospores that have encysted adjacent to the root may use specific host isoflavones to locate their host.
Abstract: We have investigated the role of the isoflavones daidzein and genistein on the chemotropic behavior of germinating cysts of Phytophthora sojae. Hyphal germlings were shown to respond chemotropically to daidzein and genistein, suggesting that hyphal tips from zoospores that have encysted adjacent to the root may use specific host isoflavones to locate their host. Observations of the contact response of hyphal germlings were made on several different substrates in the presence and absence of isoflavones. Hyphal tips of germlings detected and penetrated pores in membranes and produced multiple appressoria on smooth, impenetrable surfaces. Hyphae that successfully penetrated the synthetic membrane were observed to grow away from the membrane surface. The presence of isoflavones in the medium surrounding the hyphal germlings did not appear to alter any of those habits. Daidzein and genistein did not inhibit germination or initial hyphal growth at concentrations up to 20 μm.

138 citations


Proceedings Article
02 Jun 1998
TL;DR: Every consistent temporal plan can be reformulated as an equivalent dispatch-able network, and an algorithm is presented that constructs such a network and is shown to have a minimum number of edges among all such networks.
Abstract: The Simple Temporal Network formalism permits signiicant exibility in specifying the occurrence time of events in temporal plans. However, to retain this exibility during execution , there is a need to propagate the actual execution times of past events so that the occurrence windows of future events are adjusted appropriately. Unfortunately, this may run afoul of tight real-time control requirements that dictate extreme eeciency. The performance may be improved by restricting the propagation. However, a fast, locally propagating, execution controller may incorrectly execute a consistent plan. To resolve this dilemma, we identify a class of dis-patchable networks that are guaranteed to execute correctly under local propagation. We show that every consistent temporal plan can be reformulated as an equivalent dispatch-able network, and we present an algorithm that constructs such a network. Moreover, the constructed network is shown to have a minimum number of edges among all such networks. This algorithm will be own on an autonomous spacecraft as part of the Deep Space 1 Remote Agent experiment.

130 citations


Proceedings Article
01 Jul 1998
TL;DR: A new algorithm is presented that uses linear space and has time complexity equivalent to Johnson's algorithm for all-pairs shortest-path problems and can be made minimal in the maximum number of edges incoming or outgoing at any node.
Abstract: Temporal plans permit significant flexibility in specifying the occurrence time of events. Plan execution can make good use of that flexibility. However, the advantage of execution flexibility is counterbalanced by the cost during execution of propagating the time of occurrence of events throughout the flexible plan. To minimize execution latency, this propagation needs to be very efficient. Previous work showed that every temporal plan can be reformulated as a dispatchable plan, Le., one for which propagation to immediate neighbors is sufficient. A simple algorithm was given that finds a dispatchable plan with a minimum number of edges in cubic time and quadratic space. In this paper, we focus on the efficiency of the reformulation process, and improve on that result. A new algorithm is presented that uses linear space and has time complexity equivalent to Johnson's algorithm for all-pairs shortest-path problems. Experimental evidence confirms the practical effectiveness of the new algorithm. For example, on a large commercial application, the performance is improved by at least two orders of magnitude. We further show that the dispatchable plan, already minimal in the total number of edges, can also be made minimal in the maximum number of edges incoming or outgoing at any node.

77 citations


Proceedings ArticleDOI
01 May 1998
TL;DR: Several issues arising at the interface between planning and execution are discussed including exe cution latency plan dispatchability and the dis tinction between controllable and uncontrollable events.
Abstract: Deep Space One will be the rst spacecraft to be controlled by an autonomous agent poten tially capable of carrying out a complete mission with minimal commanding from Earth The New Millennium Remote Agent NMRA includes a planner scheduler that produces plans and an executive that carries them out In this paper we discuss several issues arising at the interface between planning and execution including exe cution latency plan dispatchability and the dis tinction between controllable and uncontrollable events Temporal information in the plan is rep resented within the general framework of Simple Temporal Constraint networks as introduced by Dechter Meiri and Pearl However the execu tion requirements have a substantial impact on the topology of the links and the propagation through the network

44 citations


Proceedings ArticleDOI
06 Apr 1998
TL;DR: This paper has two functions: to describe the results of this workshops on problems with industrial uptake from research and development projects in Requirements Engineering and to provide a framework to support planning for future RE activities and initiatives.
Abstract: In September 1996 the Joint Research Centre of the European Commission held a workshop in Brussels on problems with industrial uptake from research and development projects in Requirements Engineering. Although there have, in this domain, been a number of research projects industrial uptake has rarely lived up to expectations. The workshop set out to investigate possible explanations for this and what potential mechanisms there may be for promoting industrial uptake of current and future Requirement Engineering projects. This paper has two functions: to describe the results of this workshops and to provide a framework to support planning for future RE activities and initiatives.

38 citations


Journal ArticleDOI
TL;DR: The Joint Research Centre of the European Commission organised and held a workshop in Brussels to investigate possible explanations for and what potential mechanisms there may be for promoting industrial uptake of current and future requirement engineering R&D projects.
Abstract: Although there have been a number of research projects in requirements engineering, industrial uptake from these projects has rarely lived up to expectations. To investigate possible explanations for this and what potential mechanisms there may be for promoting industrial uptake of current and future requirement engineering R&D projects, the Joint Research Centre of the European Commission organised and held a workshop in Brussels. This paper describes the results of this workshop and outlines follow-up support activities.

33 citations


Journal ArticleDOI
TL;DR: The effect of added calcium on the developmental fate of encysted zoospores was studied in four strains of Phytophthora sojae, finding that Cysts from all strains were capable of producing both secondar and thirdar cells.
Abstract: The effect of added calcium on the developmental fate of encysted zoospores was studied in four strains of Phytophthora sojae. Cysts from all strains were capable of producing both secondar...

27 citations


Journal ArticleDOI
TL;DR: In this paper, the authors hypothesized that caffeine consumption would lead to an underestimation of the offender's aggression, less aggressive feelings toward the offender, and decreased willingness to shoot at the offender.
Abstract: Based on theories of emotions and attributional processes (Schachter, 1964; Zillman, 1978, 1983), this study hypothesized that caffeine consumption would lead to an underestimation of the offender's aggression, less aggressive feelings toward the offender, and decreased willingness to shoot at the offender. To test these hypotheses, 52 police officers in Holland ingested 150 mg of either caffeine or vitamin C and then faced a videotaped Fire Arms Training System simulated scenario. In order to investigate police officers' shooting behavior, the researcher observed the police officers' behavior by scoring the videotapes. Three different types of behavior emerged: "not shooting," "shooting in time," and "shooting too late" (shooting at the offender after he had made his stabbing movement). The officer's impression of the offender was measured with a questionnaire, as was the officer's tendency to shoot. The findings support the hypotheses. The offender made a less aggressive impression on the officers who had consumed caffeine; caffeine consumption resulted in officers' decreased aggressive feelings toward the aggressive offender; and police officers were less likely to shoot at the offender as a result of caffeine consumption.

4 citations