2,321 research outputs found

    Susceptibility of Alphitobius diaperinus (Panzer) (Coleoptera, Tenebrionidae) to cypermethrin, dichlorvos and triflumuron in southern Brazil.

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    Susceptibility of Alphitobius diaperinus (Panzer) (Coleoptera, Tenebrionidae) to cypermethrin, dichlorvos and triflumuron in southern Brazil. The lesser mealworm, Alphitobius diaperinus (Panzer), is an important insect pest in poultry houses in Brazil. Susceptibility of the lesser mealworm collected from eight poultry houses in Paraná state, southern Brazil, was evaluated for cypermethrin, dichlorvos and triflumuron. Adult A. diaperinus were tested in bioassays with cypermethrin and dichlorvos. Larvae were fed rabbit feed wetted with a triflumuron-water solution. Concentration-mortality regressions were estimated using Probit analysis and resistance ratios were calculated based on the susceptible population. Among the field populations evaluated, cypermethrin LC50 values for adults, ranged from 68.1 to 6,263 ng (AI)/cm2. LC50 values for adults challenged with dichlorvos ranged from 10.3 to 1,385 ng (AI)/cm2. One population from Pato Branco showed reduced susceptibility to triflumuron (LC50 = 272 ?g (AI)/ml of solution) when compared to the most susceptible population (LC50 = 109.8 ?g (AI)/ml). Application of cypermethrin and dichlorvos analogues should be managed with caution to minimize insecticide resistance problems. Suscetibilidade de Alphitobius diaperinus (Panzer) (Coleoptera, Tenebrionidae) a cipermetrina, diclorvós e triflumurom no sul do Brasil. O cascudinho, Alphitobius diaperinus (Panzer), é uma importante praga em aviários no Brasil. A suscetibilidade do cascudinho à cipermetrina, diclorvós e triflumurom foi avaliada em oito aviários do Estado do Paraná, Brasil. Adultos de A. diaperinus foram testados mediante bioensaios com cipermetrina e diclorvós. As larvas foram alimentadas com ração para coelhos impregnada com suspensões de triflumurom. As regressões de concentração-mortalidade foram estimadas usando análise de Probit e as razões de resistência calculadas com base na população suscetível. Entre as populações de campo avaliadas, os valores da CL50 para adultos tratados com cipermetrina variaram entre 68,1 to 6.263 ng (IA)/cm2. Os valores da CL50 para adultos tratados com diclorvós variaram de 10,3 to 1.385 ng (IA)/cm2. Uma população de Pato Branco apresentou reduzida suscetibilidade ao triflumurom (CL50 = 272 ?g (IA)/ml), quando comparada à população mais suscetível (CL50 = 109,8 ?g (IA)/ml de solução). Cipermetrina, diclorvós e análogos devem ser manejados e aplicados com cautela para minimizar os problemas de resistência a inseticidas

    Biogeochemical Activity of Siderophilic Cyanobacteria and Insights from their Genomes Implications for the Development of New Biosignatures

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    Verifying the links between genomie features in living organisms and their mineralization/demineralization activity will help to reveal traces of life on Earth and beyond. Among contemporary environments, iron-depositing hot springs (IDHS) may represent one of the most appropriate natural models for insights into ancient life since organisms may have originated on Earth and possibly Mars in association with hydrothennal activity and high [Fe(2+)]. Siderophilic or "iron-loving" cyanobacteria (CB) inhabiting IDHS may have genomic features and properties similar to those of ancient organisms because abundant Fe(2+) in IDHS has a strong potential to increase the magnitude of oxidative stress. That is why specific and/or additional proteins involved in Fe mineralization by siderophilic CB are expected. Inorganic polyphosphates (PPi) are known to increase the viability of prokaryotes Linder heavy metal concentrations and UV stress conditions. PPi have also been proposed as biosignatures. Ancient CB could have also been stressed by occasional migrations from the Fe(2+) rich Ocean to the basaltic land which was almost devoid of dissolved Fe(2+). Thus, the study of the adaptation reactions of siderophilic CB to fluctuation of dissolved Fe level may shed light on the paleophysiology of ancient oxygenic prokaryotes. Moreover, bioweathered Fe, Al, P, Cu, Ti and rare earth elements can be thought of as candidate organomarkers that document the effects of or ganic molecules in weathered rocks. However, the molecular mechanisms of the maintenance of Fe homeostasis in siderophilic CB, the role of PPi for this process and bioweathering activities are poorly understood. Here we present preliminary results describing a new mechanism of Fe mineralization in siderophilic CB, the effect of Fe on the generation of PPi bodies in siderophilic CB, their bioweathering activity and preliminary analysis of the diversity of proteins involved in the prevention of oxidative stress in phototrophs inhabiting IDHS

    Inferring Properties of Ancient Cyanobacteria from Biogeochemical Activity and Genomes of Siderophilic Cyanobacteria

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    Interrelationships between life and the planetary system could have simultaneously left landmarks in genomes of microbes and physicochemical signatures in the lithosphere. Verifying the links between genomic features in living organisms and the mineralized signatures generated by these organisms will help to reveal traces of life on Earth and beyond. Among contemporary environments, iron-depositing hot springs (IDHS) may represent one of the most appropriate natural models [1] for insights into ancient life since organisms may have originated on Earth and probably Mars in association with hydrothermal activity [2,3]. IDHS also seem to be appropriate models for studying certain biogeochemical processes that could have taken place in the late Archean and,-or early Paleoproterozoic eras [4, 5]. It has been suggested that inorganic polyphosphate (PPi), in chains of tens to hundreds of phosphate residues linked by high-energy bonds, is environmentally ubiquitous and abundant [6]. Cyanobacteria (CB) react to increased heavy metal concentrations and UV by enhanced generation of PPi bodies (PPB) [7], which are believed to be signatures of life [8]. However, the role of PPi in oxygenic prokaryotes for the suppression of oxidative stress induced by high Fe is poorly studied. Here we present preliminary results of a new mechanism of Fe mineralization in oxygenic prokaryotes, the effect of Fe on the generation of PPi bodies in CB, as well as preliminary analysis of the diversity and phylogeny of proteins involved in the prevention of oxidative stress in phototrophs inhabiting IDHS

    Homotopy analysis of magnetohydrodynamic convection flow in manufacture of a viscoelastic fabric for space applications

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    Aerospace electro-conductive polymer materials are a new family of “smart” materials being deployed in many complex applications. The precision manufacturing of such processes to manipulate properties and enhance performance can exploit magnetohydrodynamic (MHD) control and simultaneous heat transfer (thermal processing). Motivated by these applications, we develop a model for laminar free convective flow of an incompressible and electrically-conducting viscoelastic fluid (Walters’ liquid B) over a continuously moving stretching surface embedded in a porous medium in the presence of strong radiative heat flux, as a simulation of magnetic smart fabric sheet processing. A heat generation/absorption term is included in the model. Darcy’s law is used to simulate porous media bulk drag effects. The stretching is assumed to be a linear function of the coordinate along the direction of stretching. Using similarity transformations, the governing partial differential equations are converted to nonlinear ordinary differential equations. The energy equation is further rendered into confluent hypergeometric form and then solved analytically for the prescribed surface temperature (PST) case and also for the Prescribed Boundary Surface Heat Flux (PHF) case, using Kummer’s function, subject to physically realistic boundary conditions. The momentum and energy equations are also solved using the semi-numerical homotopy analysis method (HAM), which contains the auxiliary parameter , permitting relatively easy adjustment and control of the convergence region of the series solution. This method provides an efficient approximate analytical solution with high accuracy, minimal calculation, and avoidance of physically unrealistic assumptions. HAM solutions are benchmarked with robust numerical shooting quadrature and found to correlate well. The influence of magnetic field on velocity and temperature profiles is studied via the Chandrasekhar number (Q). Furthermore detailed simulations are conducted for the influence of viscoelastic parameter (k1), Eckert number (E), radiation-conduction parameter (NR), Grashof number (Gr) and heat source/sink parameter () on the flow variables. The study finds applications in electro-conductive polymeric materials processing for aerospace fabric covers and other applications with demanding safety and protection requirements in smart materials synthesis

    A functional-cognitive framework for attitude research

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    In attitude research, behaviours are often used as proxies for attitudes and attitudinal processes. This practice is problematic because it conflates the behaviours that need to be explained (explanandum) with the mental constructs that are used to explain these behaviours (explanans). In the current chapter we propose a meta-theoretical framework that resolves this problem by distinguishing between two levels of analysis. According to the proposed framework, attitude research can be conceptualised as the scientific study of evaluation. Evaluation is defined not in terms of mental constructs but in terms of elements in the environment, more specifically, as the effect of stimuli on evaluative responses. From this perspective, attitude research provides answers to two questions: (1) Which elements in the environment moderate evaluation? (2) What mental processes and representations mediate evaluation? Research on the first question provides explanations of evaluative responses in terms of elements in the environment (functional level of analysis); research on the second question offers explanations of evaluation in terms of mental processes and representations (cognitive level of analysis). These two levels of analysis are mutually supportive, in that better explanations at one level lead to better explanations at the other level. However, their mutually supportive relation requires a clear distinction between the concepts of their explanans and explanandum, which are conflated if behaviours are treated as proxies for mental constructs. The value of this functional-cognitive framework is illustrated by applying it to four central questions of attitude research

    Plasmonic atoms and plasmonic molecules

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    The proposed paradigm of plasmonic atoms and plasmonic molecules allows one to describe and predict the strongly localized plasmonic oscillations in the clusters of nanoparticles and some other nanostructures in uniform way. Strongly localized plasmonic molecules near the contacting surfaces might become the fundamental elements (by analogy with Lego bricks) for a construction of fully integrated opto-electronic nanodevices of any complexity and scale of integration.Comment: 30 pages, 16 figure

    Series Solution for the Time-Fractional Coupled mKdV Equation Using the Homotopy Analysis Method

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    We present new analytical approximated solutions for the space-time fractional nonlinear partial differential coupled mKdV equation. A homotopy analysis method is considered to obtain an infinite series solution. The effectiveness of this method is demonstrated by finding exact solutions of the fractional equation proposed, for the special case when the limit of the integral order of the time derivative is considered. The comparison shows a precise agreement between these solutions

    Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

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    The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum
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