448 research outputs found

    Seasonal Occurrence of Aphids (Aulacorthum solani, K., Aphis glycines M.) and Effects of Some Insecticides on Aphids with Infurrow Treatment in Soybean

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    This study was conducted to investigate the seasonal occurrence of aphids and to evaluate efficacy of Carbofuran, Disulfoton and Ortran applied infurrow at the planting time in the field for the control of some aphids on soybean in 1976. Foxglove aphids (Aulacorthum solani) and soybean aphids (Aphis glycines) were dominant species in the soybean field and there were two peaks in the year. The occurrence patterns of aphids were different between visual counting on leaves and in yellow-pans. Carbofuran and Disulfoton showed a good effect for the control of aphids but Ortran was less effectiveOriginating text in Korean.Citation: Hwang, C. Y., Uhm, K. B., Choi, K. M. (1981). Seasonal Occurrence of Aphids (Aulacorthum solani, K., Aphis glycines M.) and Effects of Some Insecticides on Aphids with Infurrow Treatment in Soybean. Korean Journal of Plant Protection, 20(2), 112-116

    Transition from Townsend to glow discharge: subcritical, mixed or supercritical

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    The full parameter space of the transition from Townsend to glow discharge is investigated numerically in one space dimension in the classical model: with electrons and positive ions drifting in the local electric field, impact ionization by electrons (α\alpha process), secondary electron emission from the cathode (γ\gamma process) and space charge effects. We also perform a systematic analytical small current expansion about the Townsend limit up to third order in the total current that fits our numerical data very well. Depending on γ\gamma and system size pd, the transition from Townsend to glow discharge can show the textbook subcritical behavior, but for smaller values of pd, we also find supercritical or some intermediate ``mixed'' behavior. The analysis in particular lays the basis for understanding the complex spatio-temporal patterns in planar barrier discharge systems.Comment: 12 pages, 10 figures, submitted to Phys. Rev.

    Time-resolved spectral correlations of long-duration Gamma-Ray Bursts

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    For a sample of long GRBs with known redshift, we study the distribution of the evolutionary tracks on the rest-frame luminosity-peak energy Liso-Ep' diagram. We are interested in exploring the extension of the `Yonetoku' correlation to any phase of the prompt light curve, and in verifying how the high-signal prompt duration time, Tf, in the rest frame correlates with the residuals of such correlation (Firmani et al. 2006). For our purpose, we analyse separately two samples of time-resolved spectra corresponding to 32 GRBs with peak fluxes >1.8 phot cm^-2 s^-1 from the Swift-BAT detector, and 7 bright GRBs from the CGRO-BATSE detector previously processed by Kaneko et al. (2006). After constructing the Liso-Ep' diagram, we discuss the relevance of selection effects, finding that they could affect significantly the correlation. However, we find that these effects are much less significant in the Liso x Tf-Ep' diagram, where the intrinsic scatter reduces significantly. We apply further corrections for reducing the intrinsic scatter even more. For the sub-samples of GRBs (7 from Swift and 5 from CGRO) with measured jet break time, we analyse the effects of correcting Liso by jet collimation. We find that (i) the scatter around the correlation is reduced, and (ii) this scatter is dominated by the internal scatter of the individual evolutionary tracks. These results suggest that the time, integrated `Amati' and `Ghirlanda' correlations are consequences of the time resolved features, not of selection effects, and therefore call for a physical origin. We finally remark the relevance of looking inside the nature of the evolutionary tracks.Comment: 11 pages, 6 figures, 4 tables. Submitted to MNRAS (Sept 8th), after referee comment

    Differentiating criminal networks in the illegal wildlife trade: organized, corporate and disorganized crime

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    Historically, the poaching of wildlife was portrayed as a small-scale local activity in which only small numbers of wildlife would be smuggled illegally by collectors or opportunists. Nowadays, this image has changed: criminal networks are believed to be highly involved in wildlife trafficking, which has become a significant area of illicit activity. Even though wildlife trafficking has become accepted as a major area of crime and an important topic and criminologists have examined a variety of illegal wildlife markets, research that specifically focusses on the involvement of different criminal networks and their specific nature is lacking. The concept of a ‘criminal network’ or ‘serious organized crime’ is amorphous – getting used interchangeably and describes all crime that is structured rather than solely reflecting crime that fits within normative definitions of ‘organized’ crime. In reality, criminal networks are diverse. As such, we propose categories of criminal networks that are evidenced in the literature and within our own fieldwork: (1) organized crime groups (2) corporate crime groups and (3) disorganized criminal networks. Whereas there are instances when these groups act alone, this article will (also) discuss the overlap and interaction that occurs between our proposed categories and discuss the complicated nature of the involved criminal networks as well as predictions as to the future of these networks

    X-ray flares, neutrino cooled disks, and the dynamics of late accretion in GRB engines

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    We compute the average luminosity of X-ray flares as a function of time, for a sample of 10 long-duration gamma-ray burst afterglows. The mean luminosity, averaged over a timescale longer than the duration of the individual flares, declines as a power-law in time with index ~-1.5. We elaborate on the properties of the central engine that can produce such a decline. Assuming that the engine is an accreting compact object, and for a standard conversion factor between accretion rate and jet luminosity, the switch between a neutrino-cooled thin disk and a non-cooled thick disk takes place at the transition from the prompt to the flaring phase. We discuss the implications of this coincidence under different scenarios for the powering of the GRB outflow. We also show that the interaction of the outflow with the envelope of the progenitor star cannot produce flares out of a continuous relativistic flow, and conclude that it is the dynamics of the disk or the jet-launching mechanism that generates an intrinsically unsteady outflow on timescales much longer than the dynamical timescale of the system. This is consistent with the fact that X-ray flares are observed in short-duration GRBs as well as in long-duration ones.Comment: 5 pages, MNRAS in pres

    Jitter radiation images, spectra, and light curves from a relativistic spherical blastwave

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    We consider radiation emitted by the jitter mechanism in a Blandford-McKee self-similar blastwave. We assume the magnetic field configuration throughout the whole blastwave meets the condition for the emission of jitter radiation and we compute the ensuing images, light curves and spectra. The calculations are performed for both a uniform and a wind environment. We compare our jitter results to synchrotron results. We show that jitter radiation produces slightly different spectra than synchrotron, in particular between the self-absorption and the peak frequency, where the jitter spectrum is flat, while the synchrotron spectrum grows as \nu^{1/3}. The spectral difference is reflected in the early decay slope of the light curves. We conclude that jitter and synchrotron afterglows can be distinguished from each other with good quality observations. However, it is unlikely that the difference can explain the peculiar behavior of several recent observations, such as flat X-ray slopes and uncorrelated optical and X-ray behavior.Comment: 11 pages, 7 postscript figures. Accepted for publication in MNRA
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