A Study on the Impact of Locality in the Decoding of Binary Cyclic Codes

In this paper, we study the impact of locality on the decoding of binary cyclic codes under two approaches, namely ordered statistics decoding (OSD) and trellis decoding. Given a binary cyclic code having locality or availability, we suitably modify the OSD to obtain gains in terms of the Signal-To-Noise ratio, for a given reliability and essentially the same level of decoder complexity. With regard to trellis decoding, we show that careful introduction of locality results in the creation of cyclic subcodes having lower maximum state complexity. We also present a simple upper-bounding technique on the state complexity profile, based on the zeros of the code. Finally, it is shown how the decoding speed can be significantly increased in the presence of locality, in the moderate-to-high SNR regime, by making use of a quick-look decoder that often returns the ML codeword.Comment: Extended version of a paper submitted to ISIT 201

On Binary Matroid Minors and Applications to Data Storage over Small Fields

Locally repairable codes for distributed storage systems have gained a lot of interest recently, and various constructions can be found in the literature. However, most of the constructions result in either large field sizes and hence too high computational complexity for practical implementation, or in low rates translating into waste of the available storage space. In this paper we address this issue by developing theory towards code existence and design over a given field. This is done via exploiting recently established connections between linear locally repairable codes and matroids, and using matroid-theoretic characterisations of linearity over small fields. In particular, nonexistence can be shown by finding certain forbidden uniform minors within the lattice of cyclic flats. It is shown that the lattice of cyclic flats of binary matroids have additional structure that significantly restricts the possible locality properties of $\mathbb{F}_{2}$-linear storage codes. Moreover, a collection of criteria for detecting uniform minors from the lattice of cyclic flats of a given matroid is given, which is interesting in its own right.Comment: 14 pages, 2 figure

Bioactivity of Alstonia boonei De Wild leaf alkaloid on the growth and development of Maruca vitrata Fab.

The bioactivity of Alstonia boonei De Wild leaf alkaloid was tested under laboratory bioassay against the legume pod borer, Maruca vitrata Fabricius. The alkaloid was incorporated into standard M. vitrata artificial diet at five doses [0.00 % (Control), 0.02 %, 0.05 %, 0.10 % and 0.20 %], and fed to the newly emerged first instar M. vitrata larvae in plastic wells under laboratory conditions. Significant differences (P < 0.05) were recorded in the larval survival, wet and dry weights of the larvae at ten days after infestation (DAI). Mean larval survival ranged from 34.78 to 65.00 percent in the treatments with the alkaloid compared with 91.67 percent in the control. At 15 DAI, all the survivors in the control had pupated normally compared with the 4.34 to 35.00 percent pupation (with various levels of deformity) in the treatments with the alkaloid. The mean percentage adult emergence was also significantly different in the control (83.33 %) compared with the other treatments (range 0.00 to 10.00 %). These results indicate a high level of bioactivity of A. boonei leaf alkaloid against M. vitrata. It is concluded that the alkaloid has a great potential in the search for bioactive compounds for the management of the insect

Functional response and life history parameters of Apanteles taragamae, a larval parasitoid of Maruca vitrata

Open Access JournalThe legume pod borer Maruca vitrata Fabricius (Lepidoptera: Crambidae) is a serious pest of cowpea in West-Africa. The parasitoid Apanteles taragamae Viereck (Hymenoptera: Braconidae) that originates from Taiwan is a potential candidate for biological control of M. vitrata. We investigated under laboratory conditions the functional response of the parasitoid by offering each experienced female 10, 20, 30 and 40 larvae of M. vitrata. We studied the influence of different host larval ages on the development, longevity, sex ratio, lifetime fecundity and parasitization rate of the wasp. In a comparative study, we also investigated the life history of A. taragamae and M. vitrata at different temperatures in the range of 20–30°C. The parasitoid successfully parasitized two- and three-day-old host larvae (first and second instars). Younger larvae (one-day-old) were parasitized to a lesser extent, and only males developed in them. Older larvae were not parasitized, partly because of defensive host behaviour. The success of parasitization was positively correlated with the density of two-day-old M. vitrata larvae. Parasitoid developmental time and longevity decreased with increasing temperature. The intrinsic rate of population increase (rm) exhibited an optimum curve with a maximum at 24–28°C. For the host M. vitrata, rm was maximal at temperatures of 26–30°C. The data are discussed in the context of the potential of A. taragamae for biological control of M. vitrata

Efficacité comparée des insecticides de natures différentes dans la gestion des insectes ravageurs du niébé au Centre du Bénin

Objectif: Le niébé est une importante plante alimentaire dont la production et la valorisation sont d’une grande priorité pour l’amélioration de la sécurité alimentaire de la population. L’objectif de cette étude est de comparer en milieu paysan, l'efficacité du champignon entomopathogène Beauveria bassiana (isolat Bb 115), du mélange Neem (Topbio) - virus MaviMNPV et de l’insecticide chimique Decis (deltaméthrine) dans la gestion des insectes ravageurs du niébé.Méthodologie et résultats: L'essai a été conduit dans trois villages de la zone cotonnière du centre du Bénin (commune de Glazoué). C’est en effet, une zone de grande production du niébé. L’essai a été conduit suivant un dispositif de bloc aléatoire complet avec quatre traitements et trois répétitions par village de la zone. Les traitements comprennent 1) témoin (niébé non traité), 2) mélange Topbio - MaviMNPV, 3) B. bassiana et 4) Decis. L’application du champignon B. bassiana a été faite à la dose de 75 g m.a. (matière active)/ha. Le Décis et le TopBio à 1L /ha. Quant à la suspension virale, la dose de 2.109 OB/ha a été utilisée. Les effets des différents pesticides utilisés sur les densités de populations de M. vitrata, Megalurothrips sjostedti, Clavigralla tomentosicollis, que sur leur dégâts sur les organes reproductifs (boutons floraux, fleurs, gousses) ont été évalués. Des organes fructifères ont été prélevés hebdomadairement pour évaluer le nombre de larves mortes ou vivantes et aussi leurs dégâts sur les boutons floraux, fleurs et gousses. Les rendements en grains ont été également évalués. Bien qu’il y ait une grande variation dans les effets occasionnés par les biopesticides testés, ils ont considérablement réduit la densité de population de Maruca vitrata et des autres espèces d'insectes, Megalurothrips sjostedti et Clavigralla tomentosicollis ainsi que le niveau de dommages sur les organes fructifères. Comparativement au témoin, le rendement global en grains a été amélioré dans le niébé traité. Ainsi, à Glazoué, dans la zone centrale, des rendements meilleurs de 933,03±8,7Kg/ha ont été obtenus avec le champignon B. bassiana.Conclusion et applications des résultats: Ces résultats révèlent clairement que les biopesticides utilisés dans notre étude peuvent réduire significativement les densités des ravageurs ciblés. Cette étude suggère la possibilité de l'utilisation de biopesticides comme des alternatives aux insecticides chimiques dans la lutte contre les ravageurs du niébé.Mots clés : Niébé, insectes ravageurs, insecticide chimique, insecticide biologique, lutte intégré

Pesticide resistance in Plutella xylostella (Lepidoptera: Plutellidae) populations from Togo and Benin

Published online: 17 August 2016The diamondback moth, Plutella xylostella (L.) is the major insect pest of cabbage crops in Togo and Benin. For control, farmers very often resort to spraying chemical insecticides at high dosages with frequent applications. Bioassays were carried out on three populations of P. xylostella, two from Togo (Kara and Dapaong) and one from Benin (Cotonou), to assess their level of susceptibility to currently used insecticides. A reference strain of P. xylostella from Matuu in Kenya was used as a control. In the laboratory, three insecticide representatives of different chemical families (deltamethrin, chlorpyrifos ethyl and spinosad) were assayed against third instar larvae of P. xylostella. Results revealed that P. xylostella populations from Dapaong, Kara and Cotonou were more resistant to deltamethrin (13 to 59-fold at LC50 level, 149 to 1772-fold at LC90 level) and chlorpyrifos ethyl (5 to 15-fold at LC50 level, 9 to 885-fold at LC90 level) than the reference strain. Spinosad was more toxic to P. xylostella populations than the other insecticides with LC50 and LC90 values less than 1 μg/ml and 15 μg/ml, respectively. However, the population from Cotonou appeared significantly more resistant to spinosad compared to the reference strain. These results are discussed in the light of developing an integrated pest management strategy for reducing the selection pressure of spinosad

An assessment of learning gains from educational animated videos versus traditional extension presentations among farmers in Benin*

Article purchasedThis study compared the efficacy of linguistically and dialectically localized animated educational videos (LAV) against traditional learning extension (TLE) presentations for learning gains of knowledge around agricultural- and healthcare-related topics within a rural population in Benin. While both approaches demonstrated learning gains, LAV resulted in significantly higher test scores and more detailed knowledge retention. A key contribution of this research, moreover, involves the use of mobile phone technologies to further disseminate educational information. That is, a majority of participants expressed both a preference for the LAV teaching approach and a heightened interest in digitally sharing the information from the educational animations with others. Because the animations are, by design, readily accessible to mobile phones via Africa’s explosively expanding digital infrastructure, this heightened interest in sharing the animated videos also transforms each study participant into a potential a learning node and point of dissemination for the educational video’s material as well

Vulnérabilité des cossettes issues de quelques cultivars d’igname à l’attaque de Dinoderus porcellus Lesne (Coleoptera: Bostrichidae) en conditions de laboratoire

Dinoderus porcellus Lesne a été récemment identifié comme un véritable ravageur des stocks de cossettes d’igname en Afrique de l’Ouest. En conséquence, plusieurs méthodes de lutte ont été testées ou envisagées contre ce ravageur et comprennent, entre autres, l’utilisation des cultivars d’ignames résistants à l’insecte. Dans la présente étude, le comportement de quatre lots de cossettes issues des quatre cultivars d’igname suivants : Otoukpanan, Singor, Kprakpra et Portchahabim face à D. porcellus a été observé et comparé. Cette série d’études a porté sur : (1) la préférence de D. porcellus pour l’un ou l’autre des quatre cultivars; (2) la vitesse de développement et le taux d’émergence de D. porcellus sur ces différents cultivars d’igname, et (3) leur susceptibilité à travers les dégâts et l’effectif de la progéniture de D. porcellus enregistrés sur chacun d’eux. Nos résultats ont montré : que D. porcellus a une préférence marquée pour les cossettes de Otoukpanan suivi de Singor, Portchahabim et enfin Kprakpra ; qu’il s’est développé plus rapidement sur Otoukpanan suivi de Singor, Portchahabim et Kprakpra ; et qu’il a causé le plus de dégâts sur Otoukpanan sur lequel sa progéniture a été également la plus abondante. Portchahabim et Singor ont été les cultivars les moins attaqués du lot ; de plus, aucune progéniture n’a été enregistrée sur Portchahabim. Ainsi donc, les cultivars Singor et Portchahabim ont été les moins vulnérables aux attaques de D. porcellus et devraient être privilégiés dans la préparation des cossettes.Mots clés: Dioscorea sp., insectes des denrées stockées, préférence, résistance variétale, Bénin