174 research outputs found

    Fenomenološka analiza s lokalnim potencijalom raspršenja π +

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    π +-nucleus scattering cross section are calculated by solving a Schr¨odinger equation reduced from the Klein-Gordon equation. Local potentials are assumed, and phenomenological potential parameters are searched energy dependently for π + scattering from 12C, 40Ca, and 208Pb to reproduce not only differential elastic cross sections but also inelastic and total and reaction cross sections at 800 MeV/c pion laboratory momentum. The collective model is used to calculate the angular distributions of differential inelastic cross sections for pions leading to the lowest 2 + and 3− states of 12C. The deformation parameters and lengths are extracted and compared to the corresponding ones from other works. Local potentials well describe the scattering of pions from nuclei.Izračunali smo udarne presjeke za raspršenje π +-jezgra kao rješenja Schrödingerove jednadžbe koju smo izveli iz Klein-Gordononove jednadžbe. Primijenili smo lokalne potencijale, a parametre fenomenološkog potencijala smo odredili u ovisnosti o energiji za raspršenje π + na 12C, 40Ca i 208Pb, tražeći sklad ne samo s elastičnim diferencijalnim udarnim presjecima, već i s totalnim i reakcijskim udarnim presjecima za pione s laboratorijskim impulsom 800 MeV/c. Primijenili smo kolektivni model za računanje kutne ovisnosti neelastičnih diferencijalnih udarnih presjeka za najniža 2+ i 3− stanja 12C. Izveli smo parametre i duljine deformacije koje uspoređujemo s odgovarajućim vrijednostima drugih radova. Lokalni potencijali dobro opisuju raspršenje piona u jezgrama

    Herbivore-Induced Changes in Cotton Modulates Reproductive Behavior in the Moth Spodoptera littoralis

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    Plants produce chemical defense compounds to resist herbivore attack either by repelling the herbivores or attracting natural enemies of the herbivores. We have previously shown that volatile compounds from cotton released in response to herbivory by conspecifics reduce oviposition in cotton leafworm moth Spodoptera littoralis. It remained, however, unclear whether herbivore-induced changes also affect moth pre-mating and mating behaviors. In this study we examined the effect of herbivore-induced changes in cotton on reproductive behaviors i.e., female calling, male attraction and investment, and mating behavior in S. littoralis. We found a reduction in the number of females calling i.e., females releasing pheromone, in the presence of cotton plants damaged by larvae of S. littoralis compared to undamaged plants. Females also spent significantly less time calling and showed a delay in calling in the presence of damaged plants. Furthermore, males exhibited significantly delayed activation and reduced attraction toward female sex pheromone in the presence of damaged plants. We also found that mating success and the number of matings were significantly reduced in the presence of damaged plants whereas male investment i.e., spermatophore weight, was not affected. Thus, our study provides evidence that herbivory by conspecifics on host plants affect pre-mating and mating behaviors in an insect herbivore

    Study of the Optical Properties of Zno Nano-structure at Different Ti Content

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    Zinc oxide (ZnO) and TZO samples having different Ti content were synthesized from doping to composite by Citrate sol-gel method (dissolving and react with citric acid) characterized according to their optical properties. The UV - vis characterization exhibiting good optical properties. The results show there are one absorption edge at pure and low Ti doping but at higher Ti% another edge appeared and slightly shifted around 400 nm. The maximum absorption nearly at 350 nm, and the band gap energy of Ti-doped ZnO increase from 3.16 to 3.20 eV achieving a blue-shift. A red shift from 3.07 to 3.19 eV in the visible range which has a very important application, this improves the optical properties of ZnO and gives an indication how to tune its band gap (increase or decrease by doping or composition)

    ASSESSMENT OF GRAPE SEEDS AS A SOURCE OF ANTIOXIDANT COMPOUNDS

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    The grape seeds extracted with various organic solvents (methanol, ethanol, acetone and chloroform) either pure (100%) or mixed with 30, 50 and 50% water (except chloroform)  were evaluated for its content of antioxidant compounds; i.e. phenolics and flavonoids (by HPLC technique) and/or antioxidant activities (by DPPH test). The extraction yield was ranged between 6-10% depending on solvent type and significantly increased by mixing with water with various percentages. Total phenolics, total flavonoids and antioxidant activity of grape seed extracts were affected by type of solvent. The highest total phenolic compounds and total flavonoids was recorded in methanol 70% extract, while the lowest one was in water 100% extract

    ANTIMICROBIAL ACTIVITY OF ETHANOLIC EXTRACTS OF CLOVE AND THYME

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    This study was carried out to evaluate the antimicrobial activity of clove (Syzygium aromaticum) and thyme (Thymus vulgaris) ethanolic extracts. Different concentrations of ethanolic extracts were prepared and antimicrobial activity was determined against some bacterial, yeast and mold strains. The antimicrobial activity of examined extracts at different concentrations was determined against different cell population of tested strains and expressed as diameter of inhibition zone. Results showed that all clove and thyme ethanolic extracts were markedly inhibited the growth of all tested strains, however, the inhibition effect was differed with regard to the concentration of ethanolic extract as well as the type of tested microorganism. Generally, clove ethanolic extract had stronger antimicrobial activity rather than that of thyme ethanolic extract. Subsequently, clove and thyme are an extremely strong antimicrobial agent with usefull potential applications in food processing as a natural safe unsted of synthetic antimicrobial agents

    Functional integration of "undead" neurons in the olfactory system.

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    Programmed cell death (PCD) is widespread during neurodevelopment, eliminating the surpluses of neuronal production. Using the Drosophila olfactory system, we examined the potential of cells fated to die to contribute to circuit evolution. Inhibition of PCD is sufficient to generate new cells that express neural markers and exhibit odor-evoked activity. These "undead" neurons express a subset of olfactory receptors that is enriched for relatively recent receptor duplicates and includes some normally found in different chemosensory organs and life stages. Moreover, undead neuron axons integrate into the olfactory circuitry in the brain, forming novel receptor/glomerular couplings. Comparison of homologous olfactory lineages across drosophilids reveals natural examples of fate change from death to a functional neuron. Last, we provide evidence that PCD contributes to evolutionary differences in carbon dioxide-sensing circuit formation in Drosophila and mosquitoes. These results reveal the remarkable potential of alterations in PCD patterning to evolve new neural pathways

    Mate discrimination among subspecies through a conserved olfactory pathway.

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    Communication mechanisms underlying the sexual isolation of species are poorly understood. Using four subspecies of Drosophila mojavensis as a model, we identify two behaviorally active, male-specific pheromones. One functions as a conserved male antiaphrodisiac in all subspecies and acts via gustation. The second induces female receptivity via olfaction exclusively in the two subspecies that produce it. Genetic analysis of the cognate receptor for the olfactory pheromone indicates an important role for this sensory pathway in promoting sexual isolation of subspecies, in combination with auditory signals. Unexpectedly, the peripheral sensory pathway detecting this pheromone is conserved molecularly, physiologically, and anatomically across subspecies. These observations imply that subspecies-specific behaviors arise from differential interpretation of the same peripheral cue, reminiscent of sexually conserved detection but dimorphic interpretation of male pheromones in Drosophila melanogaster. Our results reveal that, during incipient speciation, pheromone production, detection, and interpretation do not necessarily evolve in a coordinated manner

    Evaluation of the DREAM Technique for a High-Throughput Deorphanization of Chemosensory Receptors in Drosophila

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    In the vinegar fly Drosophila melanogaster, the majority of olfactory receptors mediating the detection of volatile chemicals found in their natural habitat have been functionally characterized (deorphanized) in vivo. In this process, receptors have been assigned ligands leading to either excitation or inhibition in the olfactory sensory neuron where they are expressed. In other, non-drosophilid insect species, scientists have not yet been able to compile datasets about ligand–receptor interactions anywhere near as extensive as in the model organism D. melanogaster, as genetic tools necessary for receptor deorphanization are still missing. Recently, it was discovered that exposure to artificially high concentrations of odorants leads to reliable alterations in mRNA levels of interacting odorant receptors in mammals. Analyzing receptor expression after odorant exposure can, therefore, help to identify ligand–receptor interactions in vivo without the need for other genetic tools. Transfer of the same methodology from mice to a small number of receptors in D. melanogaster resulted in a similar trend, indicating that odorant exposure induced alterations in mRNA levels are generally applicable for deorphanization of interacting chemosensory receptors. Here, we evaluated the potential of the DREAM (Deorphanization of receptors based on expression alterations in mRNA levels) technique for high-throughput deorphanization of chemosensory receptors in insect species using D. melanogaster as a model. We confirmed that in some cases the exposure of a chemosensory receptor to high concentration of its best ligand leads to measureable alterations in mRNA levels. However, unlike in mammals, we found several cases where either confirmed ligands did not induce alterations in mRNA levels of the corresponding chemosensory receptors, or where gene transcript-levels were altered even though there is no evidence for a ligand–receptor interaction. Hence, there are severe limitations to the suitability of the DREAM technique for deorphanization as a general tool to characterize olfactory receptors in insects
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