2,314 research outputs found

    Management of the Rice Tungro Virus Vector \u3ci\u3eNephotettix virescens\u3c/i\u3e (Homoptera: Cicadellidae) with Controlled-Release Formulations of Carbofuran

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    Field trials were conducted in lowland flooded rice in the Philippines to evaluate a number of carbofuran controlled-release formulations in comparison with commercial formulations. The test formulations were based on a biodegradable matrix of pine kraft lignin and were used as granules of different sizes and also in the form of small strips. The release rates were assessed under field conditions by bioassaying rice plants in the field, using adult rice green leafhopper, Nephotettix virescens Distant. The lignin formulations with a high level of active ingredient (15–45% by weight) gave as good or better control than the commercial 3% granules in tests based on three application techniques: broadcast into the floodwater, soil incorporation, and root zone injection. The improvements in control levels of green leafhoppers were most marked with soil incorporation and root zone application. The best lignin-based formulation reduced levels of tungro virus infection from 23% for a conventional flowable carbofuran formulation to 1.0% at an application rate of 0.5 kg (AI)/ha. At the same rate, the grain yield was increased from 3.56 t/ha to 5.5 t/ha, using the controlled-released formulation

    The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. II.The optically thin phase and the structure of the ejecta in recurrent novae

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    We continue our study of the physical properties of the recurrent nova T Pyx, focussing on the structure of the ejecta in the nebular stage of expansion during the 2011 outburst. The nova was observed contemporaneously with the Nordic Optical Telescope (NOT), at high resolution spectroscopic resolution (R ~ 65000) on 2011 Oct. 11 and 2012 Apr. 8 (without absolute flux calibration), and with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope, at high resolution (R ~ 30000) on 2011 Oct. 10 and 2012 Mar. 28 (absolute fluxes). We use standard plasma diagnostics (e.g. [O III] and [N II] line ratios and the Hβ\beta line fluxes) to constrain electron densities and temperatures. Using Monte Carlo modeling of the ejecta, we derive the structure and filling factor from comparisons to the optical and ultraviolet line profiles. The ejecta can be modeled using an axisymmetric conical -- bipolar -- geometry with a low inclination of the axis to the line of sight, i=15+/-5 degrees, compatible with published results from high angular resolution optical spectro-interferometry. The structure is similar to that observed in the other short orbital period recurrent novae during their nebular stages. We show that the electron density scales as t3t^{-3} as expected from a ballistically ejected constant mass shell; there is no need to invoke a continuing mass outflow following the eruption. The derived mass for the ejecta with filling factor f ~ 3%, M_ej ~ 2E-6$M_sun is similar to that obtained for other recurrent nova ejecta but inconsistent with the previously reported extended optically thick epoch of the explosion. We suggest that the system underwent a common envelope phase following the explosion that produced the recombination event. Implications for the dynamics of the recurrent novae are discussed. (truncated)Comment: accepted for publication in A&A (10 Nov. 2012), 10 pgs, 16 fig

    The spectroscopic evolution of the γ\gamma-ray emitting classical nova Nova Mon 2012. I. Implications for the ONe subclass of classical novae

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    Nova Mon 2012 was the first classical nova to be detected as a high energy γ\gamma-ray transient, by Fermi-LAT, before its optical discovery. We study a time sequence of high resolution optical echelle spectra (Nordic Optical Telescope) and contemporaneous NOT, STIS UV, and CHIRON echelle spectra (Nov 20/21/22). We use [O III] and Hβ\beta line fluxs to constrain the properties of the ejecta. We derive the structure from the optical and UV line profiles and compare our measured line fluxes for with predictions using Cloudy with abundances from other ONe novae. Mon 2012 is confirmed as an ONe nova. We find E(B-V)=0.85±\pm0.05 and hydrogen column density 5×1021\approx 5\times 10^{21} cm2^{-2}. The corrected continuum luminosity is nearly the same in the entire observed energy range as V1974 Cyg, V382 Mon, and Nova LMC 2000 at the same epoch after outburst. The distance, about 3.6 kpc, is quite similar to V1974 Cyg. The line profiles can be modeled using an axisymmetric bipolar geometry for the ejecta with various inclinations of the axis to the line of sight, 60 \le i \le 80 degrees, an opening angle of \approx70deg,innerradius70 deg, inner radius \Delta R/R(t)\approx 0.4forpermittedlinesandlessfilledforforbiddenlines.Thefillingfactor for permitted lines and less filled for forbidden lines. The filling factor f\approx 0.1-0.3implyingM(ejecta) implying M(ejecta) \leq 6\times 10^{-5}MM_\odot.TheONenovaeappeartocompriseasinglephysicalclasswithbipolarhighmassejecta,similarlyenhancedabundances,andacommonspectroscopicevolutionwithinanarrowrangeofluminosities.Thedetected. The ONe novae appear to comprise a single physical class with bipolar high mass ejecta, similarly enhanced abundances, and a common spectroscopic evolution within a narrow range of luminosities. The detected \gamma$-ray emission may be a generic phenomenon, common to all ONe novae, possibly to all classical novae, and connected with acceleration and emission processes within the ejecta (abstract severely truncated).Comment: Submitted to A&A 9/1/2013; Accepted 27/2/2013 (in press

    A rocket-borne Langmuir probe response to continuous and pulsed sweep modes

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    Nightime ionospheric electron density and temperature are measured using a rocket-borne Langmuir probe (LP) launched on board a SONDA III rocket from the Brazilian equatorial rocket launching station in Alcantara-MA, at 23:51 hrs (LT) on May 31, 1992. A sweep voltage varying between -IV and +2.5V is applied to the spherical LP sensor alternately in continuous and pulsed modes. In the continuous mode the effect of contamination of the sensor surface on the current collected by the sensor is clearly seen in the current-voltage characteristics and thereby on the electron temperature estimated, while this effect is practically absent in the pulsed mode operation. An electron temperature profile estimated from the LP data is compared with the IRI90 model profile.Material digitalizado en SEDICI gracias a la colaboración de la Facultad de Ciencias Astronómicas y Geofísicas (UNLP).Asociación Argentina de Geofísicos y Geodesta

    Management of the Rice Tungro Virus Vector \u3ci\u3eNephotettix virescens\u3c/i\u3e (Homoptera: Cicadellidae) with Controlled-Release Formulations of Carbofuran

    Get PDF
    Field trials were conducted in lowland flooded rice in the Philippines to evaluate a number of carbofuran controlled-release formulations in comparison with commercial formulations. The test formulations were based on a biodegradable matrix of pine kraft lignin and were used as granules of different sizes and also in the form of small strips. The release rates were assessed under field conditions by bioassaying rice plants in the field, using adult rice green leafhopper, Nephotettix virescens Distant. The lignin formulations with a high level of active ingredient (15–45% by weight) gave as good or better control than the commercial 3% granules in tests based on three application techniques: broadcast into the floodwater, soil incorporation, and root zone injection. The improvements in control levels of green leafhoppers were most marked with soil incorporation and root zone application. The best lignin-based formulation reduced levels of tungro virus infection from 23% for a conventional flowable carbofuran formulation to 1.0% at an application rate of 0.5 kg (AI)/ha. At the same rate, the grain yield was increased from 3.56 t/ha to 5.5 t/ha, using the controlled-released formulation

    Weekly chemotherapy in advanced prostatic cancer.

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    This randomised phase II study was performed in order to evaluate the effectiveness of a weekly chemotherapy regimen in advanced prostatic carcinoma patients (stage D2) refractory to hormonal therapy. Seventy-two cases were studied: they were randomised in a 2:1 ratio to receive either epirubicin (30 mg m-2 weekly) or doxorubicin (25 mg m-2 weekly); 48 patients received epirubicin and 24 received doxorubicin. After 12 courses of chemotherapy, the 45 evaluable patients in the epirubicin arm showed a response rate of 37.7% and the 21 evaluable patients in the doxorubicin arm showed a response rate of 33.3% (P = 0.51). Pain intensity, bone and prostatic tumour markers rapidly and significantly decreased in responders. An improvement in physical symptoms, functional conditions and in emotional well-being was observed in the majority of the treated patients. The histological analysis of bone metastases, performed before and after 12 courses of chemotherapy showed a significant reduction in neoplastic invasion and in new bone formation in responders. Cardiac performance worsened in five out of 45 patients and in ten out of 21 during the first 12 courses of epirubicin or doxorubicin respectively (P = 0.014). The median survival was 12.5 months in the epirubicin arm and 8.0 months in the doxorubicin arm (P = 0.042). Our data indicate that in advanced prostatic carcinoma, a weekly epirubicin regimen may give rapid palliative results, similar to that of doxorubicin, but with less side-effects

    Limits on the Dipole Moments of the τ\tau-Lepton via the Process $e^{+}e^{-}\to \tau^+ \tau^- \gamma in a Left-Right Symmetric Model

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    Limits on the anomalous magnetic moment and the electric dipole moment of the τ\tau lepton are calculated through the reaction e+eτ+τγe^{+}e^{-}\to \tau^+ \tau^- \gamma at the Z1Z_1-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. Due to the stringent limit of the model mixing angle ϕ\phi, the effect of this angle on the dipole moments is quite small.Comment: 15 pages, 3 figure

    Rural-urban migration in d-dimensional lattices

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    The rural-urban migration phenomenon is analyzed by using an agent-based computational model. Agents are placed on lattices which dimensions varying from d=2 up to d=7. The localization of the agents in the lattice define their social neighborhood (rural or urban) not being related to their spatial distribution. The effect of the dimension of lattice is studied by analyzing the variation of the main parameters that characterizes the migratory process. The dynamics displays strong effects even for around one million of sites, in higher dimensions (d=6, 7).Comment: 9 pages, 7 figures, to be published in International Journal of Modern Physics C 1
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