633 research outputs found

    Patent Law: Best Mode Disclosure—Genetic Engineers Get Their Trade Secret and Their Patent Too?

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    Amgen, Inc. v. Chugai Pharmaceutical Co., 927 F.2d 1200 (Fed. Cir.), cert. denied, 112 S. Ct. 169 (interim ed. 1991)

    On the topological complexity of aspherical spaces

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    The well-known theorem of Eilenberg and Ganea expresses the Lusternik - Schnirelmann category of an aspherical space as the cohomological dimension of its fundamental group. In this paper we study a similar problem of determining algebraically the topological complexity of the Eilenberg-MacLane spaces. One of our main results states that in the case when the fundamental group is hyperbolic in the sense of Gromov the topological complexity of an aspherical space K(π,1)K(\pi, 1) either equals or is by one larger than the cohomological dimension of π×π\pi\times \pi. We approach the problem by studying essential cohomology classes, i.e. classes which can be obtained from the powers of the canonical class via coefficient homomorphisms. We describe a spectral sequence which allows to specify a full set of obstructions for a cohomology class to be essential. In the case of a hyperbolic group we establish a vanishing property of this spectral sequence which leads to the main result.Comment: 25 pages, 2 figures. This version contains an additional section 10 with Theorem

    Role of plant sensory perception in plant-animal interactions

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    Plants actively gather information about their environments via a range of sensory modalities and respond in ways that profoundly influence their interactions with other organism

    Evidence of Local Adaptation in Plant Virus Effects on Host-Vector Interactions

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    Recent research suggests that plant viruses, and other pathogens, frequently alter host-plant phenotypes in ways that facilitate transmission by arthropod vectors. However, many viruses infect multiple hosts, raising questions about whether these pathogens are capable of inducing transmission-facilitating phenotypes in phylogenetically divergent host plants and the extent to which evolutionary history with a given host or plant community influences such effects. To explore these issues, we worked with two newly acquired field isolates of cucumber mosaic virus (CMV)—a widespread multi-host plant pathogen transmitted in a non-persistent manner by aphids—and explored effects on the phenotypes of different host plants and on their subsequent interactions with aphid vectors. An isolate collected from cultivated squash fields (KVPG2-CMV) induced in the native squash host (Cucurbita pepo) a suite of effects on host-vector interactions suggested by previous work to be conducive to transmission (including reduced host-plant quality for aphids, rapid aphid dispersal from infected to healthy plants, and enhanced aphid attraction to the elevated emission of a volatile blend similar to that of healthy plants). A second isolate (P1-CMV) collected from cultivated pepper (Capsicum annuum) induced more neutral effects in its native host (largely exhibiting non-significant trends in the direction of effects seen for KVPG2-CMV in squash). When we attempted cross-host inoculations of these two CMV isolates (KVPG2-CMV in pepper and P1-CMV in squash), P1-CMV was only sporadically able to infect the novel host; KVPG2-CMV infected the novel pepper host with somewhat reduced success compared with its native host and reached virus titers significantly lower than those observed for either strain in its native host. Furthermore, KVPG2-CMV induced changes in the phenotype of the novel host, and consequently in host-vector interactions, dramatically different than those observed in the native host and apparently maladaptive with respect to virus transmission (e.g., host plant quality for aphids was significantly improved in this instance, and aphid dispersal was reduced). Taken together, these findings provide evidence of adaption by CMV to local hosts (including reduced infectivity and replication in novel versus native hosts) and further suggest that such adaptation may extend to effects on host-plant traits mediating interactions with aphid vectors. Thus, these results are consistent with the hypothesis that virus effects on host-vector interactions can be adaptive, and they suggest that multi-host pathogens may exhibit adaptation with respect to these and other effects on host phenotypes, perhaps especially in homogeneous monoculture

    Olfactory Cues from Plants Infected by Powdery Mildew Guide Foraging by a Mycophagous Ladybird Beetle

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    Powdery mildews (Erysiphales) are economically important plant pathogens that attack many agricultural crops. Conventional management strategies involving fungicide application face challenges, including the evolution of resistance and concerns over impacts on non-target organisms, that call for investigation of more sustainable alternatives. Mycophagous ladybird beetles (Coleoptera: Coccinellidae) feed on powdery mildew and have considerable potential as biological control agents; however, the foraging ecology and behavior of these beetles is not well understood. Here we document the olfactory cues presented by squash plants (Cucurbita moschata) infected by powdery mildew (Podosphaera sp.) and the behavioral responses of twenty-spotted ladybird beetles (Psyllobora vigintimaculata) to these cues. Volatile analyses through gas chromatography revealed a number of volatile compounds characteristic of infected plants, including 3-octanol and its analogues 1-octen-3-ol and 3-octanone. These compounds are typical “moldy” odorants previously reported in volatiles collected from other fungi. In addition, infected plants exhibited elevated emissions of several compounds also observed in collections from healthy leaves, including linalool and benzyl alcohol, which are reported to have anti-fungal properties. In Y-tube choice assays, P. vigintimaculata beetles displayed a significant preference for the odors of infected plants compared to those of healthy plants. Moreover, beetles exhibited strong attraction to one individual compound, 1-octen-3-ol, which was the most abundant of the characteristic fungal compounds identified. These results enhance our understanding of the olfactory cues that guide foraging by mycophagous insects and may facilitate the development of integrated disease-management strategies informed by an understanding of underlying ecological mechanisms

    Visual literacy extended through graphic codes in illustrations

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    Picture books have an important place in the lives of all children. Huck (1987) believes that illustrations in picture books can enlarge children\u27s experiences, stretch their imaginations, and enhance their living. The illustrations of picture books can extend the text and sometimes can tell the story without the text. Kingman (1978) relates, that children do not always recognize the beauty of these books, but early impressions do exert influence on the development of permanent tastes for children growing up. People do not forget what they experience in their early years. When people are older, they learn to look and forget, but at a young age they still pour over the illustrations of picture books gathering treasures that they store in the pockets of their mind (p. 14)

    Distribution and prevalence of Wolbachia infections in native populations of the fire ant Solenopsis invicta (Hymenoptera : Formicidae)

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    Wolbachia are endosymbiotic bacteria that commonly infect arthropods. These bacteria induce a number of phenotypes in their hosts, including cytoplasmic incompatibility, thelytokous parthenogenesis, feminization, and male killing. We surveyed native South American populations of the fire ant Solenopsis invicta Buren for Wolbachia infections by using a diagnostic polymerase chain reaction assay. In addition, we determined the fidelity of vertical transmission of the bacteria from mother to offspring in this species by assaying daughters in 24 simple-family (monogyne) colonies. Infections were common in many parts of the extensive native range of S. invicta. However, the proportion of individuals infected varied greatly among samples, ranging from zero in several populations from the northerly parts of the range to >90% in more southerly populations. Possible explanations for this variation in the prevalence of Wolbachia infections are discussed. A survey of the two social forms of S. invicta from four geographic areas showed that the prevalence of Wolbachia infections consistently was higher in the monogyne form (single queen per colony) than the sympatric polygyne form (multiple queens per colony). One likely explanation for this trend is that the selective regimes acting on Wolbachia in the two forms differ because of the dissimilar reproductive strategies used by each form. Finally, overall transmission efficiency was found to be very high (>99%), making it unlikely that imperfect transmission prevents the spread of the microbe to near fixation in native populations
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