117 research outputs found

    The snail-killing flies of Alaska (Diptera: Sciomyzidae)

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    Information is given on the geographic distribution, habitat preferences, larval foods, and immature stages for 57 species of 9 genera of Sciomyzidae known to occur in Alaska. An illustrated key to adults is included. Alaska as a habitat for sciomyzid flies is discussed, and information on feeding habits of the larvae is summarized

    Sharpenings of Li's criterion for the Riemann Hypothesis

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    Exact and asymptotic formulae are displayed for the coefficients λn\lambda_n used in Li's criterion for the Riemann Hypothesis. For nn \to \infty we obtain that if (and only if) the Hypothesis is true, λnn(Alogn+B)\lambda_n \sim n(A \log n +B) (with A>0A>0 and BB explicitly given, also for the case of more general zeta or LL-functions); whereas in the opposite case, λn\lambda_n has a non-tempered oscillatory form.Comment: 10 pages, Math. Phys. Anal. Geom (2006, at press). V2: minor text corrections and updated reference

    Self-assembly of phosphate fluorosurfactants in carbon dioxide

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    Anionic phosphodiester surfactants, possessing either two fluorinated chains (F/F) or one hydrocarbon chain and one fluorinated chain (H/F), were synthesized and evaluated for solubility and self-assembly in liquid and supercritical carbon dioxide. Several surfactants, of both F/F and EUF types and having varied counterions, were found to be capable of solubilizing water-in-CO2 (W/C), via the formation of microemulsions, expanding upon the family of phosphate fluorosurfactants already found to stabilize W/C microemulsions. Small-angle neutron scattering was used to directly characterize the microemulsion particles at varied temperatures, pressures, and water loadings, revealing behavior consistent with previous results on W/C microemulsions

    Neuroscience, Ethics, and National Security: The State of the Art

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    Military involvement and research in neuroscience generates unique ethical, legal, and social issues that require careful elucidation and consideration in order to align the potentially conflicting needs of national defense, public interest, and scientific progress

    Predatory capacity of a shorefly, Ochthera chalybescens, on malaria vectors

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    <p>Abstract</p> <p>Background</p> <p>Since <it>Ochthera chalybescens </it>had been reported to prey on African malaria vectors, the predatory capacity of adults of this species on <it>Anopheles gambiae </it>sensu stricto was explored.</p> <p>Method</p> <p>Predatory capacity of this fly on <it>A. gambiae </it>s.s. was tested at all developmental stages, including the adult stage in the laboratory setting. Effects of water depth on its predatory capacity were also examined.</p> <p>Results</p> <p>This study revealed that <it>O. chalybescens </it>preyed on mosquitoes at all life stages except eggs. It was able to prey on an average of 9.8 to 18.8 mosquito larvae in 24 hrs. Mosquito larva size and water depth did not affect predatory capacity. However, the predacious fly preyed on significantly more 2<sup>nd</sup>-instar larvae than on pupae when larvae and pupae were both available.</p> <p>Conclusion</p> <p><it>Ochthera chalybescens </it>is, by all indications, an important predator of African malaria vectors.</p

    A first genome assembly of the barley fungal pathogen Pyrenophora teres f. teres

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    Background: Pyrenophora teres f. teres is a necrotrophic fungal pathogen and the cause of one of barley’s most important diseases, net form of net blotch. Here we report the first genome assembly for this species based solely on short Solexa sequencing reads of isolate 0-1. The assembly was validated by comparison to BAC sequences, ESTs, orthologous genes and by PCR, and complemented by cytogenetic karyotyping and the first genome-wide genetic map for P. teres f. teres. Results: The total assembly was 41.95 Mbp and contains 11,799 gene models of 50 amino acids or more. Comparison against two sequenced BACs showed that complex regions with a high GC content assembled effectively. Electrophoretic karyotyping showed distinct chromosomal polymorphisms between isolates 0-1 and 15A, and cytological karyotyping confirmed the presence of at least nine chromosomes. The genetic map spans 2477.7 cM and is composed of 243 markers in 25 linkage groups, and incorporates SSR markers developed from the assembly. Among predicted genes, non-ribosomal peptide synthetases and efflux pumps in particular appear to have undergone a P. teres f. teres-specific expansion of non-orthologous gene families. Conclusions: This study demonstrates that paired-end Solexa sequencing can successfully capture coding regions of a filamentous fungal genome. The assembly contains a plethora of predicted genes that have been implicated in a necrotrophic lifestyle and pathogenicity and presents a significant resource for examining the bases for P. teres f. teres pathogenicity

    On the zeros of the Ramanujan τ-Dirichlet series in the critical strip

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    Abstract. We describe computations which show that each of the first 12069 zeros of the Ramanujan τ-Dirichlet series of the form σ + it in the region 0 &lt;t&lt;6397 is simple and lies on the line σ = 6. The failures of Gram’s law in this region are also noted. The first 5018 zeros and 2228 successive zeros beginning with the 20001st zero are also calculated. The distribution of the normalized spacing of the zeros is examined and it appears to be that of the eigenvalues of random matrices. These comptuations are done with a Berry-Keating formula for the τ-Dirichlet series and evaluated using Mathematica TM. 1

    Morphology Of Final Instar Ochrotrichia Xena (Trichoptera : Hydroptilidae)

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    Volume: 110Start Page: 231End Page: 23
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