1,550 research outputs found

    Progress in the development of a S RETGEM-based detector for an early forest fire warning system

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    In this paper we present a prototype of a Strip Resistive Thick GEM photosensitive gaseous detector filled with Ne and ethylferrocene vapours at a total pressure of 1 atm for an early forest fire detection system. Tests show that it is one hundred times more sensitive than the best commercial ultraviolet flame detectors and therefore, it is able to reliably detect a flame of 1.5x1.5x1.5 m3 at a distance of about 1km. An additional and unique feature of this detector is its imaging capability, which in combination with other techniques, may significantly reduce false fire alarms when operating in an automatic mode. Preliminary results conducted with air filled photosensitive gaseous detectors are also presented. The approach main advantages include both the simplicity of manufacturing and affordability of construction materials such as plastics and glues specifically reducing detector production cost. The sensitivity of these air filled detectors at certain conditions may be as high as those filled with Ne and EF. Long term test results of such sealed detectors indicate a significant progress in this direction. We believe that our detectors utilized in addition to other flame and smoke sensors will exceptionally increase the sensitivity of forest fire detection systems. Our future efforts will be focused on attempts to commercialize such detectors utilizing our aforementioned findings.Comment: Presented at the International Conference on Micropattern gaseous detectors, Crete, Greece, June 200

    Abstracting strings for model checking of C programs

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    Data type abstraction plays a crucial role in software verification. In this paper, we introduce a domain for abstracting strings in the C programming language, where strings are managed as null-terminated arrays of characters. The new domain M-String is parametrized on an index (bound) domain and a character domain. By means of these different constituent domains, M-Strings captures shape information on the array structure as well as value information on the characters occurring in the string. By tuning these two parameters, M-String can be easily tailored for specific verification tasks, balancing precision against complexity. The concrete and the abstract semantics of basic operations on strings are carefully formalized, and soundness proofs are fully detailed. Moreover, for a selection of functions contained in the standard C library, we provide the semantics for character access and update, enabling an automatic lifting of arbitrary string-manipulating code into our new domain. An implementation of abstract operations is provided within a tool that automatically lifts existing programs into the M-String domain along with an explicit-state model checker. The accuracy of the proposed domain is experimentally evaluated on real-case test programs, showing that M-String can efficiently detect real-world bugs as well as to prove that program does not contain them after they are fixed

    Twinning Automata and Regular Expressions for String Static Analysis

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    In this paper we formalize TARSIS, a new abstract domain based on the abstract interpretation theory that approximates string values through finite state automata. The main novelty of TARSIS is that it works over an alphabet of strings instead of single characters. On the one hand, such an approach requires a more complex and refined definition of the widening operator, and the abstract semantics of string operators. On the other hand, it is in position to obtain strictly more precise results than state-of-the-art approaches. We implemented a prototype of TARSIS, and we applied it to some case studies taken from some of the most popular Java libraries manipulating string values. The experimental results confirm that TARSIS is in position to obtain strictly more precise results than existing analyses

    Static analysis for dummies: Experiencing LiSA

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    Semantics-based static analysis requires a significant theoretical background before being able to design and implement a new analysis. Unfortunately, the development of even a toy static analyzer from scratch requires to implement an infrastructure (parser, control flow graphs representation, fixpoint algorithms, etc.) that is too demanding for bachelor and master students in computer science. This approach difficulty can condition the acquisition of skills on software verification which are of major importance for the design of secure systems. In this paper, we show how LiSA (Library for Static Analysis) can play a role in that respect. LiSA implements the basic infrastructure that allows a non-expert user to develop even simple analyses (e.g., dataflow and numerical non-relational domains) focusing only on the design of the appropriate representation of the property of interest and of the sound approximation of the program statements

    Critical assessment of Streptomyces spp. able to control toxigenic fusaria in cereals : a literature and patent review

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    Mycotoxins produced by Fusarium species on cereals represent a major concern for food safetyworldwide. Fusariumtoxinsthatarecurrentlyunderregulationfortheircontentinfoodinclude trichothecenes, fumonisins, and zearalenone. Biological control of Fusarium spp. has been widely explored with the aim of limiting disease occurrence, but few e\ufb00orts have focused so far on limiting toxin accumulation in grains. The bacterial genus Streptomyces is responsible for the production of numerous drug molecules and represents a huge resource for the discovery of new molecules. Streptomycesspp. arealsoe\ufb03cientplantcolonizersandabletoemploydi\ufb00erentmechanismsofcontrol against toxigenic fungi on cereals. This review describes the outcomes of research using Streptomyces strains and/or their derived molecules to limit toxin production and/or contamination of Fusarium species in cereals. Both the scienti\ufb01c and patent literature were analyzed, starting from the year 2000, and we highlight promising results as well as the current pitfalls and limitations of this approach

    The PER model of abstract non-interference

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    Abstract. In this paper, we study the relationship between two models of secure information flow: the PER model (which uses equivalence relations) and the abstract non-interference model (which uses upper closure operators). We embed the lattice of equivalence relations into the lattice of closures, re-interpreting abstract non-interference over the lattice of equivalence relations. For narrow abstract non-interference, we show non-interference it is strictly less general. The relational presentation of abstract non-interference leads to a simplified construction of the most concrete harmless attacker. Moreover, the PER model of abstract noninterference allows us to derive unconstrained attacker models, which do not necessarily either observe all public information or ignore all private information. Finally, we show how abstract domain completeness can be used for enforcing the PER model of abstract non-interference

    The effects of tricyclazole treatment on aquatic macroinvertebrates in the field and in laboratory

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    The effects of tricyclazole treatments on benthic macroinvertebrates in the field and in laboratory were studied. In field conditions, low density of benthic populations was observed, both in treated and untreated plots, which was attributed to the short period of submersion of the rice field and high water temperature, fungicide treatments had no significant effect. Both laboratory acute toxicity test and a test using a mesocosm suggested a low toxicity of tricyclazole on invertebrates. A reduction of the macroinvertebrate density was observed only when tricyclazole concentration was applied at concentrations 100 times the ones tested in the field, acute toxicity test gave an LC50 after 48 h of 26 mg*L\u20131, in agreement with data obtained for other species

    Selection of an Endophytic Streptomyces sp. Strain DEF09 From Wheat Roots as a Biocontrol Agent Against Fusarium graminearum

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    Selection of biological control agents (BCA) profits from an integrated study of the tripartite interactions occurring among the BCA, the plant and the pathogen. The environment plays a crucial role in the efficacy of BCA, therefore, the selection process shall utmost mimic naturally occurring conditions. To identify effective biocontrol strains against Fusarium graminearum, the major cause of Fusarium head blight (FHB) in wheat and deoxynivalenol (DON) accumulation in grains, a workflow consisting of in vitro and in vivo assays was set up. Twenty-one Streptomyces strains, 16 of which were endophytes of different plants, were analyzed. In vitro and in vivo tests characterized their plant growth promoting (PGP) traits. Biocontrol activity against F. graminearum was firstly assessed with a dual culture assay. An in vivo germination blotter assay measured Fusarium foot rot and root rot symptoms (FFR-FRR) reduction as well as growth parameters of the plant treated with the Streptomyces strains. A selected subset of Streptomyces spp. strains was then assessed in a growth chamber measuring FFR symptoms and growth parameters of the wheat plant. The approach led to the identification of an effective Streptomyces sp. strain, DEF09, able to inhibit FHB on wheat in controlled conditions by blocking the spread of the pathogen at the infection site. The results were further confirmed in field conditions on both bread and durum wheat, where DEF09 decreased disease severity up to 60%. This work confirms that FRR and FFR pathosystems can be used to identify BCA effective against FHB
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