1,578 research outputs found

    Gauge-invariant perturbations at second order in two-field inflation

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    We study the second-order gauge-invariant adiabatic and isocurvature perturbations in terms of the scalar fields present during inflation, along with the related fully non-linear space gradient of these quantities. We discuss the relation with other perturbation quantities defined in the literature. We also construct the exact cubic action of the second-order perturbations (beyond any slow-roll or super-horizon approximations and including tensor perturbations), both in the uniform energy density gauge and the flat gauge in order to settle various gauge-related issues. We thus provide the tool to calculate the exact non-Gaussianity beyond slow-roll and at any scale.Comment: 28 pages, no figures. v2: Added a summary subsection 4.3 with further discussion of the results. Generalized all super-horizon results of section 4 and appendix A to exact ones. Other minor textual changes and references added. Conclusions unchanged. Matches published versio

    The curvature perturbation at second order

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    We give an explicit relation, up to second-order terms, between scalar-field fluctuations defined on spatially-flat slices and the curvature perturbation on uniform-density slices. This expression is a necessary ingredient for calculating observable quantities at second-order and beyond in multiple-field inflation. We show that traditional cosmological perturbation theory and the `separate universe' approach yield equivalent expressions for superhorizon wavenumbers, and in particular that all nonlocal terms can be eliminated from the perturbation-theory expressions

    Free Abelian 2-Form Gauge Theory: BRST Approach

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    We discuss various symmetry properties of the Lagrangian density of a four (3 + 1)-dimensional (4D) free Abelian 2-form gauge theory within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism. The present free Abelian gauge theory is endowed with a Curci-Ferrari type condition which happens to be a key signature of the 4D non-Abelian 1-form gauge theory. In fact, it is due to the above condition that the nilpotent BRST and anti-BRST symmetries of the theory are found to be absolutely anticommuting in nature. For our present 2-form gauge theory, we discuss the BRST, anti-BRST, ghost and discrete symmetry properties of the Lagrangian densities and derive the corresponding conserved charges. The algebraic structure, obeyed by the above conserved charges, is deduced and the constraint analysis is performed with the help of the physicality criteria where the conserved and nilpotent (anti-)BRST charges play completely independent roles. These physicality conditions lead to the derivation of the above Curci-Ferrari type restriction, within the framework of BRST formalism, from the constraint analysis.Comment: LaTeX file, 21 pages, journal referenc

    Molecular Characterization of Antibiotic Resistance in Poultry Gut Origin Enterococci and Horizontal Gene Transfer of Antibiotic Resistance to Staphylococcus aureus

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    Enterococci, the normal inhabitant of gastrointestinal tract of humans and animals, have emerged as significant antibiotic resistant nosocomial pathogens. The current study was designed to determine the antibiotic resistance profile and genes harbored by isolated strains of Enterococci along with study of antibiotic resistance transfer potential from resistant Enterococci to susceptible pathogenic Staphylococcus aureus in vitro. The PCR based prevalence of Enterococcus faecalis and Enterococcus faecium from 118 broiler cloacal swabs was 60.46 and 30.23%, respectively, indicating that E. faecalis is the predominant species in broilers followed by E. faecium. Enterococci (n=86) were examined for the phenotypic resistance against eleven antibiotics which showed higher level of resistance to lincomycin (96.51%), erythromycin (90.69%), tetracycline (86.04%) and streptomycin (75.58%), intermediate level of resistance to ciprofloxacin (54.65%) and doxycycline (48.83%), and low resistance level to penicillin (26.74%), chloramphenicol (26.74%), amoxicillin (17.44%), augmentin (11.62%) and vancomycin (10.46%). Over 80% Enterococcal isolates were found multidrug resistant (MDR). On the basis of PCR analysis, erm (B) and tet (M) genes were identified in all phenotypically erythromycin and tetracycline resistant strains while van (B) was identified in only 4/9 (44.4%) of vancomycin resistant enterococci (VRE) with no detection of van (A) gene in any VRE. One strain E. faecalis (FME-41) was able to transfer the erythromycin resistance to pathogenic Staphylococcus aureus (M-11) in broth mating assay.  MDR Enterococci pose therapeutic threat to human community and control on the spread of such MDR Enterococci from poultry to human food chain is crucial

    The Effect of Salicylic Acid on the Growth and Microtuberization of Potato (Solanum tuberosum L.) cv. Arizona Propagated in Vitro

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    Salicylic acid was employed in this study at levels (0, 50, 100, 150, 200 mg/L) in culture media for shoot development from the culture of single nodal segments, the results showed that the level (100 mg/L) was the best significantly in shoot number, leaf number, leaf area, root length and number, the significant effect of (100 mg/L) was also in total soluble protein (16.78 mg/gm) in shoots, whereas the levels (100,150, 200 mg/l) were the best significantly in chlorophyll content of the shoot leaves, the level (100 mg/L) was also affected significantly in the means of microtuber weight and number(1.094), (7.125) and total soluble protein (5.146 µg /gm) whereas the levels (100 and 150 mg/L) of salicylic acid in starch percentage (12.97, 12.99 %) were better significantly than control treatment (2.55 %). Keywords: Salicylic acid, Potato. Microtuberization, InVitr

    Phytochemical Constituents of Leaves Essential oils of Achillea fragrantissima (Asteraceae) from Iraq

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    Essential oils of Achillea fragrantissima extract were prepared and analyzed by gas chromatography–mass spectrometry (GC-MS). A total of 57 phytochemical constituents of chemical compounds were identified in leaves of A. fragrantissima. The major constituents of the essential oil were camphor (34.50%), 1, 8-cineole (14.60%), artemisia ketone (10.25%), and 3-thujanone (7.82%). In addition, 43 components were present at <1%. From the 57 identified compounds, four of them was sesquiterpenes (7.01%), whereas 35 compounds were monoterpenes (61.40%)

    Curvaton and the inhomogeneous end of inflation

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    We study the primordial density perturbations and non-Gaussianities generated from the combined effects of an inhomogeneous end of inflation and curvaton decay in hybrid inflation. This dual role is played by a single isocurvature field which is massless during inflation but acquire a mass at the end of inflation via the waterfall phase transition. We calculate the resulting primordial non-Gaussianity characterized by the non-linearity parameter, fNLf_{NL}, recovering the usual end-of-inflation result when the field decays promptly and the usual curvaton result if the field decays sufficiently late.Comment: 13 pages, 5 figure

    Calculation of Electric Field Distribution at High Voltage Cable Terminations

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    High Voltage cables are used for transmission and distribution of electrical power. Such cables are subjected to extensive high voltage testing for performance evaluation and quality control purposes. During such testing, the cable ends have to be prepared carefully to make a proper end termination. Usually deionized water terminations are used for testing XLPE cables. Alternatively conductive paint is used to prepare such a termination. This paper presents an analytical method of calculating the voltage distribution across such a resistive termination when subjected to AC voltage stress. The proposed method is used to determine the effect of different design parameters on voltage and stress distribution on such cable ends. The method is simple and can be used to understand the importance of stress control at a cable termination which constitutes a critical part of such cables.    Keywords: AC voltage distribution, cable terminations, resistive terminations, stress control, XLPE high  voltage cable

    Effect of Background Evolution on the Curvaton Non-Gaussianity

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    We investigate how the background evolution affects the curvature perturbations generated by the curvaton, assuming a curvaton potential that may deviate slightly from the quadratic one, and parameterizing the background fluid density as \rho\propto a^{-\alpha}, where a is the scale factor, and \alpha depends on the background fluid. It turns out that the more there is deviation from the quadratic case, the more pronounced is the dependence of the curvature perturbation on \alpha. We also show that the background can have a significant effect on the nonlinearity parameters f_NL and g_NL. As an example, if at the onset of the curvaton oscillation there is a dimension 6 contribution to the potential at 5 % level and the energy fraction of the curvaton to the total one at the time of its decay is at 1 %, we find variations \Delta f_NL \sim \mathcal{O}(10) and \Delta g_NL \sim \mathcal{O}(10^4) between matter and radiation dominated backgrounds. Moreover, we demonstrate that there is a relation between f_NL and g_NL that can be used to probe the form of the curvaton potential and the equation of state of the background fluid.Comment: 14 pages, 8 figure

    Anatomical Studies of Medicinal Plant Fumaria densiflora in Iraq

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    The anatomical characters of the leaf, stem and fruits of Fumaria densiflora of Papaveraceae family were studied by scanning electron and light microscopy. The results showed that the wall cells of adaxial and abaxial epidermis was thick with straight- sinuate anticlinal cell walls. Both surface have stomatal types of anomocytic, anisocytic and hemiparacytic. Leaf mesophyll consists of 1- 2 layers of palisade cells under the superior epidermis thickness rang 121.44 um and 3 or 6 layers of spongy tissue under the palisade layer. Cross sections of stems are pentagonal- shaped in outline and having five prominent angles.Fumaria fruits are tetragonal in shaped (fruit ribs are four). The external area included 2-4 layers of chlorenchyma cells as well as several layers of hypodermal collenchyma cells were recognized below the epidermis. Laticifer tubes could be seen in the sclerenchymatous sheath of the vascular bundles, the fruit wall, placenta and internal parenchyma layers. Keywords: Papaveraceae, Fumaria densiflora, leaves, stem, fruits
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