5,183 research outputs found

    An insight into the role of trissolcus mitsukurii as biological control agent of halyomorpha halys in Northeastern Italy

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    11noSustainable strategies such as classical or augmentative biological control are currently being evaluated for the long-term management of the alien invasive pest Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). A three-year study carried out in northeastern Italy was performed to investigate the distribution and field performance of the H. halys egg parasitoid Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae), in comparison with other parasitoid species. In the study area, adventive populations of T. mitsukurii were present since 2016, representing the earliest detection of this species in Europe. Trissolcus mitsukurii was the most abundant parasitoid and showed a higher “parasitoid impact” (i.e., number of parasitized eggs over the total number of field-collected eggs) compared to the other species, i.e., Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae), Trissolcus basalis (Wollaston) and Trissolcus kozlovi Rjachovskij (Hymenoptera: Scelionidae). The hyperparasitoid Acroclisoides sinicus (Huang and Liao) (Hymenoptera: Pteromalidae) was also recorded. Phylogenetic analysis of T. mitsukurii population distinguished two clades, one covering samples from Italy, Japan and China, the other from South Korea. The present study provides promising results for the biological control of a pest that is having a dramatic impact on a wide range of crops worldwide.openopenScaccini D.; Falagiarda M.; Tortorici F.; Martinez-Sanudo I.; Tirello P.; Reyes-Dominguez Y.; Gallmetzer A.; Tavella L.; Zandigiacomo P.; Duso C.; Pozzebon A.Scaccini, D.; Falagiarda, M.; Tortorici, F.; Martinez-Sanudo, I.; Tirello, P.; Reyes-Dominguez, Y.; Gallmetzer, A.; Tavella, L.; Zandigiacomo, P.; Duso, C.; Pozzebon, A

    Chiral bosons and improper constraints

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    We argue that a consistent quantization of the Floreanini-Jackiw model, as a constrained system, should start by recognizing the improper nature of the constraints. Then each boundary conditon defines a problem which must be treated sparately. The model is settled on a compact domain which allows for a discrete formulation of the dynamics; thus, avoiding the mixing of local with collective coordinates. For periodic boundary conditions the model turns out to be a gauge theory whose gauge invariant sector contains only chiral excitations. For antiperiodoc boundary conditions, the mode is a second-class theory where the excitations are also chiral. In both cases, the equal-time algebra of the quantum energy-momentum densities is a Virasoro algebra. The Poincar\'e symmetry holds for the finite as well as for the infinite domain.Comment: 13 pages, Revtex file, IF.UFRGS Preprin

    8. EXPERIENCIAS EN EL TRATAMIENTO TÉRMICO DE ACEROS PARA ASEGURAMIENTO DE LA VALIDEZ DE LOS RESULTADOS EN DUREZA ROCKWELL C

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    Los laboratorios que siguen la norma ISO/IEC 17025 deben asegurar la validez de los resultados cuando ejecutan rutinariamente calibraciones y ensayos, en el caso de la dureza Rockwell, varios de los procedimientos de aseguramiento involucran el uso de materiales homogéneos, a excepción de los materiales de referencia certificados, los aceros en estado de suministro comercial presentan una no homogeneidad en la dureza bastante alta y después del tratamiento térmico comercial, esta persiste. En el presente trabajo se realiza el control de los parámetros de ciclos de tratamiento térmico para tres aceros (AISI 4140, AISI O1 y uno similar al AISI D2), con el fin de obtener una homogeneidad cercana a las estipuladas en la norma ASTM E18-19 para los rangos de dureza de la escala Rockwell C referentes a los bloques patrón. Para confirmar la homogeneidad de los tratamientos térmicos se realizaron mediciones de dureza HRC en un durómetro previamente verificado y análisis metalográficos, encontrando que la variación de temperaturas del tratamiento térmico influye en la homogeneidad de la dureza

    8. EXPERIENCIAS EN EL TRATAMIENTO TÉRMICO DE ACEROS PARA ASEGURAMIENTO DE LA VALIDEZ DE LOS RESULTADOS EN DUREZA ROCKWELL C

    Get PDF
    Los laboratorios que siguen la norma ISO/IEC 17025 deben asegurar la validez de los resultados cuando ejecutan rutinariamente calibraciones y ensayos, en el caso de la dureza Rockwell, varios de los procedimientos de aseguramiento involucran el uso de materiales homogéneos, a excepción de los materiales de referencia certificados, los aceros en estado de suministro comercial presentan una no homogeneidad en la dureza bastante alta y después del tratamiento térmico comercial, esta persiste. En el presente trabajo se realiza el control de los parámetros de ciclos de tratamiento térmico para tres aceros (AISI 4140, AISI O1 y uno similar al AISI D2), con el fin de obtener una homogeneidad cercana a las estipuladas en la norma ASTM E18-19 para los rangos de dureza de la escala Rockwell C referentes a los bloques patrón. Para confirmar la homogeneidad de los tratamientos térmicos se realizaron mediciones de dureza HRC en un durómetro previamente verificado y análisis metalográficos, encontrando que la variación de temperaturas del tratamiento térmico influye en la homogeneidad de la dureza

    Observation of Pulsed Gamma-rays Above 25 GeV from the Crab Pulsar with MAGIC

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    One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring the high-end region of a pulsar's spectrum would shed light on this question. By developing a new electronic trigger, we lowered the threshold of the Major Atmospheric gamma-ray Imaging Cherenkov (MAGIC) telescope to 25 GeV. In this configuration, we detected pulsed gamma-rays from the Crab pulsar that were greater than 25 GeV, revealing a relatively high cutoff energy in the phase-averaged spectrum. This indicates that the emission occurs far out in the magnetosphere, hence excluding the polar-cap scenario as a possible explanation of our measurement. The high cutoff energy also challenges the slot-gap scenario.Comment: Slight modification of the analysis: Fitting a more general function to the combined data set of COMPTEL, EGRET and MAGIC. Final result and conclusion is unchange

    Constraints on the steady and pulsed very high energy gamma-ray emission from observations of PSR B1951+32/CTB 80 with the MAGIC Telescope

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    We report on very high energy gamma-observations with the MAGIC Telescope of the pulsar PSR B1951+32 and its associated nebula, CTB 80. Our data constrain the cutoff energy of the pulsar to be less than 32 GeV, assuming the pulsed gamma-ray emission to be exponentially cut off. The upper limit on the flux of pulsed gamma-ray emission above 75 GeV is 4.3*10^-11 photons cm^-2 sec^-1, and the upper limit on the flux of steady emission above 140 GeV is 1.5*10^-11 photons cm^-2 sec^-1. We discuss our results in the framework of recent model predictions and other studies.Comment: 7 pages, 7 figures, replaced with published versio

    First bounds on the very high energy gamma-ray emission from Arp 220

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    Using the Major Atmospheric Gamma Imaging Cherenkov Telescope (MAGIC), we have observed the nearest ultra-luminous infrared galaxy Arp 220 for about 15 hours. No significant signal was detected within the dedicated amount of observation time. The first upper limits to the very high energy γ\gamma-ray flux of Arp 220 are herein reported and compared with theoretical expectations.Comment: Accepted for publication in Ap

    miR-146a rs2431697 identifies myeloproliferative neoplasm patients with higher secondary myelofibrosis progression risk

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    Myelofibrosis (MF) occurs as part of the natural history of polycythemia vera (PV) and essential thrombocythemia (ET), and remarkably shortens survival. Although JAK2V617F and CALR allele burden are the main transformation risk factors, inflammation plays a critical role by driving clonal expansion toward end-stage disease. NF-κB is a key mediator of inflammation-induced carcinogenesis. Here, we explored the involvement of miR-146a, a brake in NF-κB signaling, in MPN susceptibility and progression. rs2910164 and rs2431697, that affect miR-146a expression, were analyzed in 967 MPN (320 PV/333 ET/314 MF) patients and 600 controls. We found that rs2431697 TT genotype was associated with MF, particularly with post-PV/ET MF (HR = 1.5; p < 0.05). Among 232 PV/ET patients (follow-up time=8.5 years), 18 (7.8%) progressed to MF, being MF-free-survival shorter for rs2431697 TT than CC + CT patients (p = 0.01). Multivariate analysis identified TT genotype as independent predictor of MF progression. In addition, TT (vs. CC + CT) patients showed increased plasma inflammatory cytokines. Finally, miR-146a−/− mice showed significantly higher Stat3 activity with aging, parallel to the development of the MF-like phenotype. In conclusion, we demonstrated that rs2431697 TT genotype is an early predictor of MF progression independent of the JAK2V617F allele burden. Low levels of miR-146a contribute to the MF phenotype by increasing Stat3 signaling
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