11,445 research outputs found

    Correlated Spectral and Temporal Variability in the High-Energy Emission from Blazars

    Get PDF
    Blazar flare data show energy-dependent lags and correlated variability between optical/X-ray and GeV-TeV energies, and follow characteristic trajectories when plotted in the spectral-index/flux plane. This behavior is qualitatively explained if nonthermal electrons are injected over a finite time interval in the comoving plasma frame and cool by radiative processes. Numerical results are presented which show the importance of the effects of synchrotron self-Compton cooling and plasmoid deceleration. The use of INTEGRAL to advance our understanding of these systems is discussed.Comment: 8 pages, 5 figures, uses epsf.sty, rotate.sty Invited paper in "The Extreme Universe," 3rd INTEGRAL Workshop, 14-18 September 1998, Taorimina, Ital

    Testing Gaussian random hypothesis with the cosmic microwave background temperature anisotropies in the three-year WMAP data

    Full text link
    We test the hypothesis that the temperature of the cosmic microwave background is consistent with a Gaussian random field defined on the celestial sphere, using de-biased internal linear combination (DILC) map produced from the 3-year WMAP data. We test the phases for spherical harmonic modes with l <= 10 (which should be the cleanest) for their uniformity, randomness, and correlation with those of the foreground templates. The phases themselves are consistent with a uniform distribution, but not for l <= 5, and the differences between phases are not consistent with uniformity. For l=3 and l=6, the phases of the CMB maps cross-correlate with the foregrounds, suggestion the presence of residual contamination in the DLC map even on these large scales. We also use a one-dimensional Fourier representation to assemble a_lm into the \Delta T_l(\phi) for each l mode, and test the positions of the resulting maxima and minima for consistency with uniformity randomness on the unit circle. The results show significant departures at the 0.5% level, with the one-dimensional peaks being concentrated around \phi=180 degs. This strongly significant alignment with the Galactic meridian, together with the cross-correlation of DILC phases with the foreground maps, strongly suggests that even the lowest spherical harmonic modes in the map are significantly contaminated with foreground radiation.Comment: submitted to ApJL, one paragraph is added in Section 3 and some more in the Referenc

    Attempts to Enrich the Parasite Fauna of the European Corn Borer in Minnesota

    Get PDF
    Four parasitic insect species were tested in laboratory experimentation for adaptability to the European corn borer (ECB). Apanreles sesamiae, Apanteles flavipes and Chelonus knabi did not adapt to the ECB, Lixophaga diatraeae was able to survive on ECB. Three other species. Macrocentrus grandii, Eriborus terebrans and Lydella rhompsoni, all known parasites of ECB, were obtained and reared in the laboratory on ECB for propagation, release and ecological studies. Methodology for experimentation and propagation of parasites was described

    Auto and cross correlation of phases of the whole-sky CMB and foreground maps from the 1-year WMAP data

    Full text link
    The issue of non-Gaussianity is not only related to distinguishing the theories of the origin of primordial fluctuations, but also crucial for the determination of cosmological parameters in the framework of inflation paradigm. We present an advenced method for testing non-Gaussianity on the whole-sky CMB anisotropies. This method is based on the Kuiper's statistic to probe the two-dimensional uniformity on a periodic mapping square associating phases: return mapping of phases of the derived CMB (similar to auto correlation) and cross correlations between phases of the derived CMB and foregrounds. Since phases reflect morphology, detection of cross correlation of phases signifies the contamination of foreground signals in the derived CMB map. The advantage of this method is that one can cross check the auto and cross correlation of phases of the derived CMB and foregrounds, and mark off those multipoles in which the non-Gaussianity results from the foreground contaminations. We apply this statistic on the derived signals from the 1-year WMAP data. The auto-correlations of phases from the ILC map shows the significance above 95% CL against the random phase hypothesis on 17 spherical harmonic multipoles, among which some have pronounced cross correlations with the foreground maps. We conclude that most of the non-Gaussianity found in the derived CMB maps are from foreground contaminations, except, among others, l=6. With this method we are better equipped to approach the issue of non-Gaussianity of primordial origin for the upcoming PLANCK mission.Comment: 2 figures added: new representation of reconstructed (from 1D Fourier composition) DT distribution for each multipole number el

    European Corn Borer Parasitoids; Distribution in Southern Minnesota

    Get PDF
    During the 1940\u27s and 1950\u27s seven exotic parasitoids of the European corn borer (ECB) Ostrinia nubilalis (Hubner), were released in Minnesota. This study was done to determine which introduced parasitoids became established and their distribution in Minnesota. The experiment was conducted during the summer of 1977 and fall of 1977, 78, 79- and 80 in conjunction with the annual ECB population surveys in southern Minnesota by the State Department of Agriculture, Division of Plant Industry. Three introduced parasitoids, Macrocentrus grandii Goidanich, Eriborus Terebrans (Gravenhorst), and Sympiesis viridula (Thomson) and two native parasitoids, lshnus inquisitorius artricollaris (Walsh) and Aplomya caesar (Aldrich) were recovered. M. grandii was confined to the eastern portion, while E. terebrans was recovered from throughout southern Minnesota. S. viridula was found in only three counties, perhaps because of its biology it may have eluded recovery, resulting in underestimated distribution. The two native species, I. inquisitorius atricollaris and A. caesar, occur only occasionally in Minnesota

    Dynamical coupled-channel model of kaon-hyperon interactions

    Full text link
    The pi N --> KY and KY --> KY reactions are studied using a dynamical coupled-channel model of meson-baryon interactions at energies where the baryon resonances are strongly excited. The channels included are: pi N, K \Lambda, and K\Sigma. The resonances considered are: N^* [S_{11}(1650), P_{11}(1710), P_{13}(1720),D_{13}(1700)]; \Delta^* [S_{31}(1900), P_{31}(1910), P_{33}(1920)]; \Lambda ^* [S_{01}(1670), P_{01}(1810)] \Sigma^* [P_{11}(1660), D_{13}(1670)]; and K^*(892). The basic non-resonant \pi N --> KY and KY --> KY transition potentials are derived from effective Lagrangians using a unitary transformation method. The dynamical coupled-channel equations are simplified by parametrizing the pi N -->pi N amplitudes in terms of empirical pi N partial-wave amplitudes and a phenomenological off-shell function. Two models have been constructed. Model A is built by fixing all coupling constants and resonance parameters using SU(3) symmetry, the Particle Data Group values, and results from a constituent quark model. Model B is obtained by allowing most of the parameters to vary around the values of model A in fitting the data. Good fits to the available data for pi^- p to K^0 \Lambda, K^0 \Sigma^0 have been achieved. The investigated kinematics region in the center-of-mass frame goes from threshold to 2.5 GeV. The constructed models can be imbedded into associated dynamical coupled-channel studies of kaon photo- and electro-production reactions.Comment: 35 pages, 11 Figure

    Spin injection from perpendicular magnetized ferromagnetic δ\delta-MnGa into (Al,Ga)As heterostructures

    Full text link
    Electrical spin injection from ferromagnetic δ\delta-MnGa into an (Al,Ga)As p-i-n light emitting diode (LED) is demonstrated. The δ\delta-MnGa layers show strong perpendicular magnetocrystalline anisotropy, enabling detection of spin injection at remanence without an applied magnetic field. The bias and temperature dependence of the spin injection are found to be qualitatively similar to Fe-based spin LED devices. A Hanle effect is observed and demonstrates complete depolarization of spins in the semiconductor in a transverse magnetic field.Comment: 4 pages, 3 figure

    On the Antenna Beam Shape Reconstruction Using Planet Transit

    Full text link
    The calibration of the in-flight antenna beam shape and possible beamdegradation is one of the most crucial tasks for the upcoming Planck mission. We examine several effects which could significantly influence the in-flight main beam calibration using planet transit: the problems of the variability of the Jupiter's flux, the antenna temperature and passing of the planets through the main beam. We estimate these effects on the antenna beam shape calibration and calculate the limits on the main beam and far sidelobe measurements, using observations of Jupiter and Saturn. We also discuss possible effects of degradation of the mirror surfaces and specify corresponding parameters which can help us to determine these effects.Comment: 10 pages, 8 figure

    Shifts of the nuclear resonance in the vortex lattice in YBa2_2Cu3_3O7_7

    Full text link
    The NMR and NQR spectra of 63^{63}Cu in the CuO2_2 plane of YBa2_2Cu3_3O7_7 in the superconducting state are discussed in terms of the phenomenological theory of Ginzburg-Landau type extended to lower temperatures. We show that the observed spectra, Kumagai {\em et al.}, PRB {\bf 63}, 144502 (2001), can be explained by a standard theory of the Bernoulli potential with the charge transfer between CuO2_2 planes and CuO chains assumed.Comment: 11 pages 7 figure
    corecore