Van Emden Research Articles

The first record of Atherigona from Lesotho (Diptera, Muscidae), with description of a new species

Eight species of Atherigona Rondani, 1856 are recorded from Lesotho for the first time: Atherigona angulata Deeming, 1971, Atherigona chrysohypene Muller, 2015, Atherigona kirkspriggsi Muller, 2015, Atherigona laevigata (Loew, 1852), Atherigona lineata ugandae van Emden, 1940, Atherigona londti Muller, 2015, Atherigona rubricornis Stein, 1913 and a new species Atherigona jordaensisp. nov. The new species is described and diagnoses for all known species from Lesotho are provided with a brief discussion on their distribution in the country.

Three new Coenosia Meigen species from Madagascar (Diptera: Muscidae)

Three new species, Coenosia circuita sp. n., Coenosia grunowiana sp. n. and Coenosia neaurifa sp. n. are described from Madagascar as new to science. The identification key to the species of the Afrotropical group “Coenosia” created in 1940 by Van Emden has been updated and considers now 14 species.

Response of elastic/viscoelastic layers on an elastic half-space in rolling contacts: Towards a new modeling approach for elastohydrodynamic lubrication

The 3D quasi-static contact problem of a rigid sphere rolling on an elastic half-space covered by a thin viscoelastic/elastic layer is studied as representative of soft layered contacts in engineering, physics, and biomedical applications, as well as for its potential merit to model Elasto-Hydrodynamically Lubricated (EHL) contacts in specific EHL film behavior suggested in earlier research. The viscoelastic layer behavior is modeled with a standard linear solid (SLS) model with a single relaxation time. Two approaches are used, the foundation (Winkler) reduced model assuming unidirectional stress–strain behavior normal to the surface only and the Papkovich–Neuber potential model which, based on the complete Navier–Cauchy equations, accounts for non-local support and bending effects. The models are validated against literature and compared. Whereas coated/layered contact problem studies mostly consider relatively thick coatings, and results focus on the pressure distribution and the contact area size, in this paper we consider layers with a thickness much smaller than the contact radius, i.e. of the order of a thickness of a conventional EHL film. The details of the layer deformation, pressure profiles and subsurface stresses are presented and interpreted in terms of the underlying physics, in particular the thin layer limit common also in thin fluid layers. It is shown that two dimensionless parameters, the ratio of the elastic modulus between the layer and the substrate and the ratio of the layer thickness to the corresponding Hertz contact width, dominate the systematic response for elastic layered contact problems. And four dimensionless parameters with two extras, the Deborah number based on the Hertz contact width and the ratio of the two elastic limits of the SLS viscoelastic material, are needed and analyzed for viscoelastic layered contacts. The results presented provide a good framework for the understanding and interpretation of the effects of viscoelastic layers on the deformation and pressure distribution of contact problems. Finally, the capability of actually modeling EHL film behavior via a viscoelastic layer suggested by van Emden et al. (2017) is discussed.

Commentaires sur des vers problématiquesdu manuscrit de Cambridge duRoland

AbstractThere are three extant editions of the Cambridge version ofThe Song of Roland. However, only the last one – that is, the van Emden edition – has a detailed examination of verses that pose subtle difficulties. Thus, although the manuscript’s text has been established, except for a few incorrect or uncertain readings, a more comprehensive examination of the text has just begun. This paper exhaustively contemplates the nuanced interpretations, unconvincing expansions of abbreviations, lexical and morphologic problems, and linguistic particularities of the copyist of this edition. It also considers modifications of the text, interpretation of problematic verses, and editorial methodology. The aspects listed above are not rigidly categorised because every case involves several points of view. The author of this paper has almost accomplished a fresh edition of the same manuscript,Édition électronique du Roland de Cambridge, which will soon be made available. The present paper offers supplementary information for the readers of this edition.

The histone chaperone FACT facilitates heterochromatin spreading by regulating histone turnover and H3K9 methylation states.

SUMMARYHeterochromatin formation requires three distinct steps: nucleation, self-propagation (spreading) along the chromosome, and faithful maintenance after each replication cycle. Impeding any of those steps induces heterochromatin defects and improper gene expression. The essential histone chaperone FACT (facilitates chromatin transcription) has been implicated in heterochromatin silencing, but the mechanisms by which FACT engages in this process remain opaque. Here, we pinpoint its function to the heterochromatin spreading process in fission yeast. FACT impairment reduces nucleation-distal H3K9me3 and HP1/Swi6 accumulation at subtelomeres and derepresses genes in the vicinity of heterochromatin boundaries. FACT promotes spreading by repressing heterochromatic histone turnover, which is crucial for the H3K9me2 to me3 transition that enables spreading. FACT mutant spreading defects are suppressed by removal of the H3K9 methylation antagonist Epe1. Together, our study identifies FACT as a histone chaperone that promotes heterochromatin spreading and lends support to the model that regulated histone turnover controls the propagation of repressive methylation marks.

Problèmes méthodologiques de « The Cambridge version » duRolandéditée par Wolfgang G. van Emden

Abstract Van Emden executed numerous corrections in his edition of the Cambridge version ofThe Song of Roland(2005). However, these amendments are often insufficiently justified and cannot stand up to a rigorous and detailed examination from the standpoint of historical linguistics. In most cases, van Emden modified the text of the manuscript in order to « restore » metrically correct verses that, to his mind, should have been included according to the model followed by the Cambridge copyist. Van Emden accomplished his stated task by simultaneously rejecting and retaining modernized forms or words. Sometimes, he substituted an archaic form or word for a modernized term, even when the former had fallen into disuse long before the time the Cambridge manuscript was redacted. This paper does not merely list such contradictory or unsuccessful amendments. Instead, it shows that a common methodological problem is present in all the problematic corrections: van Emden was not entirely aware of the stage of textual evolution that he aimed to reinstate. By contrast, the author of the present paper began elaborating the methodology for his new edition of the Cambridge manuscript with precisely this question.

Effect of Afidopyropen against Myzus persicae (Hemiptera: Aphididae) and Its Predator, Adalia bipunctata (L.) in a Greenhouse

Effect of Afidopyropen against Myzus persicae (Hemiptera: Aphididae) and Its Predator, Adalia bipunctata (L.) in a Greenhouse

TASks for subtelomeres: when nucleosome loss and genome instability are favored.

Chromosome ends are protected from erosion and chromosomal fusions through telomeric repeats and the telomere-binding protein complex shelterin. Imperfect repetitive sequences, known as telomere-associated sequences (TAS), flank the telomeres, yet their function is not well understood. In this perspective, we discuss our recent findings demonstrating that the TAS, in Schizosaccharomyces pombe, are organized into a distinct chromatindomain that is marked by low nucleosome levels and ishighly recombinogenic (van Emden et al. in EMBO Rep 20:e47181. https://doi.org/10.15252/embr.201847181 , 2019). Low nucleosome abundance at the TAS is independent of the chromosomal position, but is an intrinsic property of the DNA sequence itself. Critical nucleosome levels are maintained through two heterochromatin complexes recruited by the shelterin subunit Ccq1, which together control gene repression and nucleosome stability. Furthermore, Ccq1 inhibits TAS-facilitated recombination between subtelomeres, yet independently of nucleosome stability. In conclusion, the TAS present a unique chromatin environment causing nucleosome loss and genome instability, which are both counteracted by Ccq1 through independent mechanisms. Given the antagonistic behavior, we hypothesize that Ccq1 co-evolved with the appearance of TAS to regulate nucleosome dynamics and recombination-based telomere maintenance in the absence of telomerase.

Biology, ecology, distribution and taxonomy of immature stages of Atherigona (s.s.) hyalinipennis van Emden (Diptera: Muscidae), a pest of the cereal crop tef (Eragrostis tef) and the fodder crop Rhodes grass (Chloris gayana)

The mature larva and puparium of Atherigona hyalinipennis van Emden are described, a parasite and further distributional data recorded and notes given on biology.

Aphids as Crop Pests. Edited by Helmut F. van Emden and Richard Harrington

Aphids as Crop Pests. Edited by Helmut F. van Emden and Richard Harrington

Taxonomy of Morellia Robineau-Desvoidy (Diptera: Muscidae): revision of the subgenera Morellia s. str. and Parapyrellia Townsend.

The subgenera Morellia Robineau-Desvoidy, 1830 and Parapyrellia Townsend, 1915 of Morellia (Diptera, Muscidae) are revised. Forty-two species of the subgenus Morellia (out of 50) and seven of the subgenus Parapyrellia (all species) are redescribed and illustrated, and 48 species are keyed (41 spp. of Morellia and 7 spp. of Parapyrellia). Morellia (M.) cashmirana van Emden, 1965, originally described as a subspecies of M. (M.) hortorum (Fallén, 1817), is raised to species rank, stat. nov. Four species are transferred from the subgenus Morellia to the subgenus Parapyrellia (subgen. comb. nov.): M. dendropanacis Pamplona & Couri, 1995; M. lopesae Pamplona, 1986; M. roppai Pamplona, 1986 and M. semimarginata (Stein, 1918).

Species of Coenosia Meigen (Diptera, Muscidae) described by Fritz van Emden from the British Museum Ruwenzori Expedition of 1934-1935.

All the species of Coenosia Meigen (Diptera, Muscidae) described by Fritz van Emden from the British Museum (Natural History) Ruwenzori Expedition of 1934-1935 (Emden 1940), supplemented by species from the Entomological Expedition to Abyssinia of 1926-1927 (Emden 1941), were studied, a total of 51 species. All types are deposited in the Natural History Museum, London, UK. For each species, a diagnosis is given and photographs of the 10 holotypes and of their labels are presented. Dissections and illustrations of the male terminalia were made when paratypes or identified specimens were available; all terminalia are described for the first time. One new synonym is proposed: C. kilembana (Emden, 1940) as a junior synonym of C. rebmanni Speiser, 1924; and three subspecies had their status revised and were elevated to species rank: C. brunneigena Emden, 1940, previously a subspecies of C. heterocnemis Emden, 1940; and C. albisquama (Emden, 1940) and C. argentescens (Emden, 1940), both previously subspecies of C. niveifrons (Stein, 1913).

<strong><em>Eutarsopolipus</em> <em>obrieni</em> n. sp. (Acari: Podapolipidae), ectoparasite of <em>Platynus</em> <em>darlingtoni</em> (Coleoptera: Carabidae) in Jamaica, a second species in the <em>brettae</em> group of <em>Eutarsopolipus</em></strong>

Eutarsopolipus obrieni sp. nov. (Acari: Podapolipidae), subelytral parasite of Platynus darlingtoni van Emden (Coleoptera: Carabidae), collected in Jamaica, is described. Relationships in the groups of Eutarsopolipus with adult females without stigmata, the pterostichi, brettae, stammeri and lukoschusi groups, are presented and a key to the 12 species in this cluster of Eutarsopolipus is included.

FLP answer set semantics without circular justifications for general logic programs

The answer set semantics presented by Faber et al. [27] has been widely used to define so called FLP answer sets for different types of logic programs. However, it was recently observed that when being extended from normal to more general classes of logic programs, this approach may produce answer sets with circular justifications that are caused by self-supporting loops. The main reason for this behavior is that the FLP answer set semantics is not fully constructive by a bottom up construction of answer sets. In this paper, we overcome this problem by enhancing the FLP answer set semantics with a level mapping formalism such that every answer set I can be built by fixpoint iteration of a one-step provability operator (more precisely, an extended van Emden–Kowalski operator for the FLP reduct fΠI). This is inspired by the fact that under the standard answer set semantics, each answer set I of a normal logic program Π is obtainable by fixpoint iteration of the standard van Emden–Kowalski one-step provability operator for the Gelfond–Lifschitz reduct ΠI, which induces a level mapping. The enhanced FLP answer sets, which we call well-justified FLP answer sets, are thanks to the level mapping free of circular justifications. As a general framework, the well-justified FLP answer set semantics applies to logic programs with first-order formulas, logic programs with aggregates, description logic programs, hex-programs etc., provided that the rule satisfaction is properly extended to such general logic programs. We study in depth the computational complexity of FLP and well-justified FLP answer sets for general classes of logic programs. Our results show that the level mapping does not increase the worst-case complexity of FLP answer sets. Furthermore, we describe an implementation of the well-justified FLP answer set semantics, and report about an experimental evaluation, which indicates a potential for performance improvements by the level mapping in practice.

Notes about morphological features of the Western Hemisphere subtribe Ardistomina, and revision of genus Semiardistomis Kult (Coleoptera, Carabidae, Scaritinae, Clivinini)

Comparisons of structural features (principally mouthparts, elytral-abdominal locking mechanism, and female genitalia) of the ardistomine genera (Aspidoglossa Putzeys, Ardistomis Putzeys, and Semiardistomis Kult) with those features of members of the subtribe Clivinina (Clivina Latreille, Oxydrepanus Putzeys, Schizogenius Putzeys,Ancus Putzeys, Nyctosyles Putzeys, and Obadius Burmeister) confirm the taxonomic validity of the subtribe Ardistomina. Based on morphological features, the ardistomine genera are postulated to be related as follows: [Aspidoglossa [Ardistomis + Semiardistomis]]. Knowledge of this subtribe is further extended by taxonomic treatment of the genus Semiardistomis Kult. Of the 30 valid names of Semiardistomis previously recognized, four were proposed as variety names, and are listed as junior synonyms: Ardistomis labialis picipes Bates, 1881, Ardistomis labialis nanus Bates, 1881, and Ardistomis labialis dilatatus Bates, 1881; and Ardistomis pallipes caerulea Putzeys, 1846. Eight names, treated as specific epithets, are junior synonyms, as follows: Ardistomis (Semiardistomis) balthasari Kult, 1950 = Semiardistomis glabratus (Putzeys, 1866); Ardistomis (Semiardistomis) emdeni Kult, 1950 = Semiardistomis deletus (Putzeys, 1846); Ardistomis aenea Putzeys, 1866, Ardistomis (Semiardistomis) brittoni Kult, 1950, and Ardistomis (Semiardistomis) marani Kult, 1950 = Semiardistomis flavipes (Dejean, 1831); Ardistomis tuspanensis Putzeys, 1846 = Semiardistomis labialis (Chaudoir, 1837); Ardistomis (Semiardistomis) vlastae Kult, 1950 = Semiardistomis subglabra (van Emden, 1949); and Ardistomis striga Putzeys, 1866 = Semiardistomis pallipes (Dejean, 1831). Two new species described are Semiardistomis exspectatus sp. n. (type locality PERU, Madre de Dios, Rio Manu, 11°56'47"S, 071°17'00"W), and Semiardistomis major sp. n. (type locality PERU, Loreto, Rio Samiria, 05°12'S, 75°20'W). The 20 species of Semiardistomis are arranged intwo species–groups here proposed: the puncticollis group, including 12 species; and labialis group, including eight species. The species recognized are keyed, described or redescribed, and notes are provided about their Geographical distribution, habitat and activity. Distribution maps show known geographical ranges, from which are inferred patterns of speciation from a center of radiation in northern South America of both lineages.

‘Exciting statistics’: the rapid development and promising future of hierarchical models for population ecology

Many biologists might indeed find statistics dull or even terrifying (van Emden, 2008), but ecologists and wildlife biologists should be downright ecstatic with recent developments in statistical modeling. One of the most exciting advances in recent decades is the development of hierarchical models. Hierarchical or multi-level models are becoming increasingly common in population analysis, and with good reason. Indeed, Kery & Schaub (2011) devote much of their final chapter to the ‘Power and Beauty of Hierarchical Models’, and among the many virtues they list for hierarchical models are simpler fitting of complex models, clarity of thinking about these models and a ‘step-up’ approach to model building (Kery & Schaub, 2011). Simpler and clearer model construction is an important advantage of hierarchical models, and although this may be reason enough to choose a hierarchical approach to modeling ecological data, the benefits do not stop with the fitting of the model to data. The property of shrinkage is a particularly important advantage of hierarchical models in ecology (Gelman et al., 2004; Gelman & Hill, 2006; Ntzoufras, 2011; Cam, 2012; Schaub & Kery, 2012). Shrinkage (or ‘borrowing strength’) refers to the assumption of random effects to be realizations of a process governed by a statistical distribution (Gelman et al., 2004; Cam, 2012; Schaub & Kery, 2012). This stochastic assumption means that realizations of the process (such as daily risk of mortality at sites, in the present case) that are poorly estimated because of small sample size, short study duration, etc., but that fall far from the population mean will be pulled toward the mean; those realizations that are strongly supported by data contribute more information about the distribution from which the stochastic realizations are drawn, and are pulled less strongly toward the mean (Gelman et al., 2004; Gelman & Hill, 2006). Including random effects in models therefore allows the estimation of parameters for realizations with small sample sizes, guards against spurious conclusions, and increases the precision of parameter estimates for all realizations of the process of interest (Gelman & Hill, 2006; Cam, 2012; Schaub & Kery, 2012). Another important benefit of hierarchical models is reduction in bias. Where unmeasured (or unmeasurable) variables affect a parameter of interest, estimates of that parameter can be biased; applying a random effect allows for such unobserved heterogeneity and reduces the bias associated with unmeasured covariates (Gelman & Hill, 2006; Cam, 2012). The many advantages of hierarchical models for animal conservation apply not only to shared frailty models (Heisey et al., 2010; Griffin et al., 2011; Halstead et al., 2012), but also to modeling individual frailties in survival and reproduction (Cam et al., 2002; Wintrebert et al., 2005), accounting for heterogeneity in individual capture probabilities (Dorazio & Royle, 2003), discerning patterns among demographic parameters (Link & Barker, 2005) and combining inference for mark-recapture models (Rivot & Prevost, 2002; Calvert et al., 2009; Papadatou et al., 2010, 2012) among many, many other applications. Although all commentators correctly acknowledge that algebraically identical hierarchical models can be analyzed under a frequentist or Bayesian approach, the latter offers the ecologist several important advantages. Modern software allows the simple implementation of complex models that would be difficult to analyze in a likelihood framework (Royle & Dorazio, 2008; Kery & Schaub, 2011; Schaub & Kery, 2012). This frees ecologists to focus on developing interesting, relevant models for their systems rather than writing complex likelihood functions (Kery, 2010; Kery & Schaub, 2011; Schaub & Kery, 2012). The consistent treatment of fixed effects, random effects, and missing data is another advantage of the Bayesian paradigm (Link & Barker, 2010; Heisey, 2012). Calculation of derived parameters and out-of-sample predictions, and propagating error associated with these quantities, is simple and does not rely upon asymptotic approximations (Kery, 2010; Link & Barker, 2010); such derived parameters and predictions are commonly of interest in population models. Updating prior bs_bs_banner

The harmonic mean renormalises random diffusion across a spatial multigrid

Most methods for modelling dynamics posit just two time scales: a fast and a slow scale. But many applications, such as the diffusion in a random media considered here, possess a wide variety of space-time scales. Consider the microscale diffusion on a one dimensional lattice with arbitrary diffusion coefficients between adjacent lattice points. I develop a slow manifold approach to model the diffusion, with some rigorous support, on a lattice that is coarser by a factor of four: the coarser scale effective diffusion coefficients are the harmonic mean of fine scale coefficients. Then iterating the analytic mapping of random diffusion from the finer grid to the coarser grid generates a hierarchy of models on a spatial multigrid across a wide range of space-time scales, all with rigorous support. The one step harmonic mean renormalises to harmonic means for the effective diffusion coefficients across the entire hierarchy. References Todd Arbogast and Kirsten J. Boyd. Subgrid upscaling and mixed multiscale finite elements. SIAM J. Numer. Anal., 44:1150--1171, 2006. doi:10.1137/050631811. Achi Brandt. General highly accurate algebraic coarsening. Elect. Trans. Num. Anal., 10:1--20, 2000. http://www.emis.ams.org/journals/ETNA/vol.10.2000/pp1-20.dir/pp1-20.html. Achi Brandt. Multiscale scientific computation: review 2001. In T. F. Chan T. J. Barth and R. Haimes, editors, Multiscale and Multiresolution Methods: Theory and Applications, pages 1--96. Springer--Verlag, Heidelberg, 2001. Achi Brandt. Methods of systematic upscaling. Technical report, Department of Computer Science and Applied Mathematics, The Weizmann Institute of Science, March 2006. http://wisdomarchive.wisdom.weizmann.ac.il:81/archive/00000398/. William L. Briggs, Van Emden Henson, and Steve F. McCormick. A multigrid tutorial, second edition. SIAM, 2nd edition, 2001. J. Carr. Applications of centre manifold theory, volume 35 of Applied Math. Sci. Springer--Verlag, 1981. J. Dolbow, M. A. Khaleel, and J. Mitchell. Multiscale mathematics initiative: A roadmap. Report from the 3rd DoE workshop on multiscale mathematics. Technical report, Department of Energy, USA, http://www.sc.doe.gov/ascr/mics/amr, December 2004. Weinan E, Bjorn Engquist, Xiantao Li, Weiqing Ren, and Eric Vanden-Eijnden. The heterogeneous multiscale method: A review. Technical report, http://www.math.princeton.edu/multiscale/review.pdf, 2004. B. Engquist and P. E. Souganidis. Asymptotic and numerical homogenization. Acta Numerica, 17:147--190, 2008. Martin J. Gander and Andrew M. Stuart. Space-time continuous analysis of waveform relaxation for the heat equation. SIAM Journal on Scientific Computing, 19(6):2014--2031, 1998. Y. A. Kuznetsov. Elements of applied bifurcation theory, volume 112 of Applied Mathematical Sciences. Springer--Verlag, 1995. Tony MacKenzie and A. J. Roberts. Holistic discretisation ensures fidelity to dynamics in two spatial dimensions. Technical report, http://arxiv.org/abs/0904.0855v1, 2009. G. A. Pavliotis and A. M. Stuart. Multiscale methods: averaging and homogenization, volume 53 of Texts in Applied Mathematics. Springer, 2008. A. J. Roberts. Simple and fast multigrid solution of Poisson's equation using diagonally oriented grids. ANZIAM J., 43(E):E1--E36, July 2001. http://anziamj.austms.org.au/ojs/index.php/ANZIAMJ/article/view/465. A. J. Roberts. Low-dimensional modelling of dynamical systems applied to some dissipative fluid mechanics. In Rowena Ball and Nail Akhmediev, editors, Nonlinear dynamics from lasers to butterflies, volume 1 of Lecture Notes in Complex Systems, chapter 7, pages 257--313. World Scientific, 2003. A. J. Roberts. Choose interelement coupling to preserve self-adjoint dynamics in multiscale modelling and computation. Technical report, http://arxiv.org/abs/0811.0688, 2008. A. J. Roberts. Normal form transforms separate slow and fast modes in stochastic dynamical systems. Physica A, 387:12--38, 2008. A. J. Roberts. Model dynamics across multiple length and time scales on a spatial multigrid. Multiscale Modeling and Simulation, 7(4):1525--1548, 2009. G. Samaey, I. G. Kevrekidis, and D. Roose. The gap-tooth scheme for homogenization problems. SIAM Multiscale Modeling and Simulation, 4:278--306, 2005. doi:10.1137/030602046. G. Samaey, A. J. Roberts, and I. G. Kevrekidis. Equation-free computation: an overview of patch dynamics, chapter 8, pages 216--246. Oxford University Press, 2010.

Use of Expanding Foam for Confining Thrips in Cages on Cowpea, Vigna unguiculata (L.) Walp, Flowers

Studies on insect biology often require insects to be confined on a plant surface with cages. E. A. Hartley (1923) discussed the use of glass lantern globes for caging insects on plants shortly after the beginning of the 20th century. He devised improvements in cage production that included such things as use of perforated celluloid that provided better air circulation and use of melted paraffin to reduce insect escape. A substantial improvement in cage production was the development of clip cages that enabled small insects to be caged on a small portion of the plant, i.e., branches and foliage (MacGillivary and Anderson, 1957; Guthrie and Bishop, 1960; and Mowry, 1993). These cages, however, are not without their problems. Although clip cages may work well with aphids and whiteflies, they may be unsuccessful in preventing escape of smaller insects like thrips. Further, standard clip cages are not suitable for confining certain plant structures like flowers. Salguero et al (1991) used perforated plastic bags to cage thrips on tomato blooms. Bags were secured with paraffin strips. Although this method successfully confined thrips to small blooms, the process is time consuming and difficult. Thrips are considered a major insect pest of cowpea, Vigna unguiculata (L.) Walp, worldwide with different species attacking either the blooms or foliage of cowpea (Singh and van Emden, 1 979; Jackai and Daoust, 1986). Chalfant (1976) reported Frankliniella tritici (Fitch) to be the most abundant species on cowpea. F. tritici attack cowpea flowers and can cause damage to reproductive portions of blooms resulting in premature senescence (Jackai and Daoust, 1986). The impact of thrips, especially F. tritici, on cowpea is not well defined. Although several studies have correlated F. tritici management with improved cowpea yield (Chalfant and Johnson, 1972; Sweeden et al, 1994) other studies suggest that yield increase may actually be caused by other factors such as insecticides directly inducing plant responses (Hundley, 2004). In order to define the impact of F. tritici on cowpea, known numbers of thrips will need to be confined on cowpea flowers. The objective of this manuscript is to describe a caging system that successfully confines thrips on cowpea flowers. Thrips cages (Fig. 1) were constructed by taking a square of No-Thrip Insect Screen (Green-Tek, Edgerton, WI) measuring approximately 13 cm X 13 cm and rolling it into a tube 3.5 cm in diameter. Duct tape (Duck® Brand, Henkel Consumer Adhesives, Inc., Avon, OH) strips approximately 2.5 cm wide were used to seal inner and outer seams of the rolled mesh. A 29.5 ml plastic cup (Solo Cup Co., Highland Park, IL) was placed bottom-side inward in one end of the tube. Another 2.5 cm wide strip of duct tape was used to secure the cup to the tube and tape was burnished around the juncture to ensure a seal. The end opposing the cup was also taped shut and burnished. The bottom of the cup was then removed with a carpet knife. A hole was punched in the center of the cup lid approximately 0.5 cm in diameter and a slit was created from the hole to the edge of the lid to allow placement over the peduncle of the cowpea

Qualified Logic Programming with Bivalued Predicates

Research on the field of uncertainty in logic programming has evolved during the last 25 years. In a recent paper [M. Rodríguez-Artalejo and C.A. Romero-Díaz. Quantitative logic programming revisited. In J. Garrigue and M. Hermenegildo, editors, Functional and Logic Programming (FLOPS'08) , volume 4989 of LNCS , pages 272–288. Springer Verlag, 2008] we have revised a classical approach by van Emden's to Quantitative Logic Programming [M.H. van Emden. Quantitative deduction and its fixpoint theory. Journal of Logic Programming , 3(1):37–53, 1986], generalizing it to a generic scheme QLP( D ) for so-called Qualified Logic Programming over a parametrically given domain D , whose elements play the role of generalized truth values and can be used to qualify logical assertions. In this paper we present an extension of QLP( D ) yielding a more expressive scheme BQLP( D ), which supports a simple kind of negation based on bivalued predicates and allows threshold constraints in clause bodies in order to impose lower bounds to the qualifications computed by program clauses. The new scheme has a rigorous declarative semantics and a sound and strongly complete goal resolution procedure which can be efficiently implemented using constraint logic programming technology.

Abstract interpretation of resolution-based semantics

We extend the abstract interpretation point of view on context-free grammars by Cousot and Cousot to resolution-based logic programs and proof systems. Starting from a transition-based small-step operational semantics of Prolog programs (akin to the Warren Machine), we consider maximal finite derivations for the transition system from most general goals. This semantics is abstracted by instantiation to terms and furthermore to ground terms, following the so-called c- and s-semantics approach. Orthogonally, these sets of derivations can be abstracted to SLD-trees, call patterns and models, as well as interpreters providing effective implementations (such as Prolog). These semantics can be presented in bottom–up fixpoint form. This abstract interpretation-based construction leads to classical bottom–up semantics (such as the s-semantics of computed answers, the c-semantics of correct answers of Keith Clark, and the minimal-model semantics of logical consequences of Maarten van Emden and Robert Kowalski). The approach is general and can be applied to infinite and top–down semantics in a straightforward way.