10,526 research outputs found

    Entomopathogenic nematodes for biological control of codling moth

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    Entomopathogenic nematodes are often found naturally infecting codling moth larvae. The effect of an autumn treatment with S. feltiae on the fruit damage in the following summer was evaluated by treating 4 different apple orchards in October 2004 and 2005 at application rates of 3.75; 2 and 1.5 billion nematodes in 4000 l / ha. In three of the treated orchards, one treated with 3.75x109 nematodes/ha the other two treated with 2e9 nematode/ha, reduction in fruit damage was around 50%. In the most heavily infested orchard, which was treated with 1.5x109 nematode/ha only 33% reduction in fruit damage was achieved. Compared to previous studies, this was the first assessing the effect on the fruit damage in the summer following the treatment rather than assessing the mortality of sentinel larvae fixed to the treated tree trunks

    Emotions, Violence and Social Belonging: an Eliasian Analysis of Sports Spectatorship

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    This paper examines the development of different forms of spectator violence in terms of the socio-temporal structure of situational dynamics at Gaelic football matches in Ireland. The nature of violent encounters has shifted from a collective form based on local solidarity and a reciprocal code of honour, through a transitional collective form based on deferred emotional satisfaction and group pride, towards increasing individualization of spectator violence. This occurs due to the shifting objects of emotional involvement. As the functional specialization of the various roles in the game is partially accepted by spectators, the referee becomes the target of anger. Violence becomes more individualized as ‘mutually expected self-restraint’ proceeds within the context of relative state pacification beyond the field of play and the formation of a less volatile habitus. We use Elias’s figurational perspective on violence over the micro-interactional approach of Randall Collins, but support Collins’ emphasis on state legitimacy

    Gravitational anomalies: a recipe for Hawking radiation

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    We explore the method of Robinson and Wilczek for deriving the Hawking temperature of a black hole. In this method, the Hawking radiation restores general covariance in an effective theory of near-horizon physics which otherwise exhibits a gravitational anomaly at the quantum level. The method has been shown to work for broad classes of black holes in arbitrary spacetime dimensions. These include static black holes, accreting or evaporating black holes, charged black holes, rotating black holes, and even black rings. In the case of charged and rotating black holes, the expected super-radiant current is also reproduced.Comment: 7 pages; This essay received an "Honorable Mention" in the 2007 Essay Competition of the Gravity Research Foundation; (v2) Short comments and references added; (v3) Minor revisions and updated references to agree with published versio

    Impeded Growth of Magnetic Flux Bubbles in the Intermediate State Pattern of Type I Superconductors

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    Normal state bubble patterns in Type I superconducting Indium and Lead slabs are studied by the high resolution magneto-optical imaging technique. The size of bubbles is found to be almost independent of the long-range interaction between the normal state domains. Under bubble diameter and slab thickness proper scaling, the results gather onto a single master curve. On this basis, in the framework of the "current-loop" model [R.E. Goldstein, D.P. Jackson and A.T. Dorsey, Phys. Rev. Lett. 76, 3818 (1996)], we calculate the equilibrium diameter of an isolated bubble resulting from the competition between the Biot-and-Savart interaction of the Meissner current encircling the bubble and the superconductor-normal interface energy. A good quantitative agreement with the master curve is found over two decades of the magnetic Bond number. The isolation of each bubble in the superconducting matrix and the existence of a positive interface energy are shown to preclude any continuous size variation of the bubbles after their formation, contrary to the prediction of mean-field models.Comment: \'{e}quipe Nanostructures Quantique

    Comparing and characterizing some constructions of canonical bases from Coxeter systems

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    The Iwahori-Hecke algebra H\mathcal{H} of a Coxeter system (W,S)(W,S) has a "standard basis" indexed by the elements of WW and a "bar involution" given by a certain antilinear map. Together, these form an example of what Webster calls a pre-canonical structure, relative to which the well-known Kazhdan-Lusztig basis of H\mathcal{H} is a canonical basis. Lusztig and Vogan have defined a representation of a modified Iwahori-Hecke algebra on the free Z[v,v−1]\mathbb{Z}[v,v^{-1}]-module generated by the set of twisted involutions in WW, and shown that this module has a unique pre-canonical structure satisfying a certain compatibility condition, which admits its own canonical basis which can be viewed as a generalization of the Kazhdan-Lusztig basis. One can modify the parameters defining Lusztig and Vogan's module to obtain other pre-canonical structures, each of which admits a unique canonical basis indexed by twisted involutions. We classify all of the pre-canonical structures which arise in this fashion, and explain the relationships between their resulting canonical bases. While some of these canonical bases are related in a trivial fashion to Lusztig and Vogan's construction, others appear to have no simple relation to what has been previously studied. Along the way, we also clarify the differences between Webster's notion of a canonical basis and the related concepts of an IC basis and a PP-kernel.Comment: 32 pages; v2: additional discussion of relationship between canonical bases, IC bases, and P-kernels; v3: minor revisions; v4: a few corrections and updated references, final versio

    The supernova impostor PSN J09132750+7627410 and its progenitor

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    We report the results of our follow-up campaign of the supernova impostor PSN J09132750+7627410, based on optical data covering ∼250 d\sim250\,\rm{d}. From the beginning, the transient shows prominent narrow Balmer lines with P-Cygni profiles, with a blue-shifted absorption component becoming more prominent with time. Along the ∼3 months\sim3\,\rm{months} of the spectroscopic monitoring, broad components are never detected in the hydrogen lines, suggesting that these features are produced in slowly expanding material. The transient reaches an absolute magnitude Mr=−13.60±0.19 magM_r=-13.60\pm0.19\,\rm{mag} at maximum, a typical luminosity for supernova impostors. Amateur astronomers provided ∼4 years\sim4\,\rm{years} of archival observations of the host galaxy, NGC 2748. The detection of the quiescent progenitor star in archival images obtained with the Hubble Space Telescope suggests it to be an 18−2018-20\msun white-yellow supergiant.Comment: 7 pages, 4 figures, supplemental material available in the source file. Accepted for publication on Astrophysical Journal Letter

    Near-infrared light curves of type Ia supernovae

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    Aims. With our time-dependent model atmosphere code PHOENIX, our goal is to simulate light curves and spectra of hydrodynamical models of all types of supernovae. In this work, we simulate near-infrared light curves of SNe Ia and confirm the cause of the secondary maximum. Methods. We apply a simple energy solver to compute the evolution of an SN Ia envelope during the free expansion phase. Included in the solver are energy changes due to expansion, the energy deposition of {\gamma}-rays and interaction of radiation with the material. Results. We computed theoretical light curves of several SN Ia hydrodynamical models in the I, J, H, and K bands and compared them to the observed SN Ia light curves of SN 1999ee and SN 2002bo. By changing a line scattering parameter in time, we obtained quite reasonable fits to the observed near-infrared light curves. This is a strong hint that detailed NLTE effects in IR lines have to be modeled, which will be a future focus of our work. Conclusions. We found that IR line scattering is very important for the near-infrared SN Ia light curve modeling. In addition, the recombination of Fe III to Fe II and of Co III to Co II is responsible for the secondary maximum in the near-infrared bands. For future work the consideration of NLTE for all lines (including the IR subordinate lines) will be crucial.Comment: 5 pages, 12 figures, A&A in pres
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