3,692 research outputs found

    Multimetric Supergravities

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    Making use of integral forms and superfield techniques we propose supersymmetric extensions of the multimetric gravity Lagrangians in dimensions one, two, three and four. The supersymmetric interaction potential covariantly deforms the bosonic one, producing in particular suitable super-symmetric polynomials generated by the Berezinian. As an additional application of our formalism we construct supersymmetric multi-Maxwell theories in dimensions three and four.Comment: 37 pages, Latex2e, no figure

    The Fermi blazars' divide based on the diagnostic of the SEDs peak frequencies

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    We have studied the quasi-simultaneous Spectral Energy Distributions (SED) of 48 LBAS blazars, detected within the three months of the LAT Bright AGN Sample (LBAS) data taking period, combining Fermi and Swift data with radio NIR-Optical and hard-X/gamma-ray data. Using these quasi-simultaneous SEDs, sampling both the low and the high energy peak of the blazars broad band emission, we were able to apply a diagnostic tool based on the estimate of the peak frequencies of the synchrotron (S) and Inverse Compton (IC) components. Our analysis shows a Fermi blazars' divide based on the peak frequencies of the SED. The robust result is that the Synchrotron Self Compton (SSC) region divides in two the plane were we plot the peak frequency of the synchrotron SED vs the typical Lorentz factor of the electrons most contributing to the synchrotron emission and to the inverse Compton process. Objects within or below this region, radiating likely via the SSC process, are high-frequency-peaked BL Lac object (HBL), or low/intermediate-frequency peaked BL Lac object (LBL/IBL). All of the IBLs/LBLs within or below the SSC region are not Compton dominated. The objects lying above the SSC region, radiating likely via the External radiation Compton (ERC) process, are Flat Spectrum Radio Quasars and IBLs/LBLs. All of the IBLs/LBLs in the ERC region show a significant Compton dominance.Comment: Contribution to the Workshop SciNeGHe 2009/Gamma-ray Physics in the LHC era (Assisi - Italy, Oct. 7-9 2009

    Achilles Tendon mechanical behavior and ankle joint function at the walk-to-run transition

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    Walking at speeds higher than transition speed is associated with a decrease in the plantar-flexor muscle fibres' ability to produce force and, potentially, to an impaired behaviour of the muscle-tendon unit (MTU) elastic components. This study aimed to investigate the ankle joint functional indexes and the Achilles tendon mechanical behaviour (changes in AT force and power) to better elucidate the mechanical determinants of the walk-to-run transition. Kinematics, kinetic and ultrasound data of the gastrocnemius medialis (GM) were investigated during overground walking and running at speeds ranging from 5-9 km·h-1. AT and GM MTU force and power were calculated during the propulsive phase; the ankle joint function indexes (damper, strut, spring and motor) were obtained using a combination of kinetic and kinematic data. AT force was larger in running at speeds > 6.5 km/h. The contribution of AT to the total power provided by the GM MTU was significantly larger in running at speeds > 7.5 km/h. The spring and strut indexes of the ankle were significantly larger in running at speeds > 7.5 km/h. These data suggest that the walk-to-run transition could (at least partially) be explained by the need to preserve AT mechanical behaviour and the ankle spring function

    Metabolism as a Basis for Differential Atrazine Tolerance in Warm-Season Forage Grasses

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    Atrazine metabolism was studied in four warmseason forage grasses to determine if metabolism was the basis for differential atrazine tolerance among the grasses. Big bluestem and switchgrass are atrazine tolerant while indiangrass and sideoats grama are atrazine susceptible in the seedling stage. Metabolism of atrazine in big bluestem and switchgrass occurred primarily by glutathione conjugation. The major metabolic product isolated from indiangrass and sideoats grama was the N-deethylated metabolite of atrazine. Glutathione conjugation by big bluestem and switchgrass occurred at a faster rate than N-dealkylation of atrazine in indiangrass and sideoats grama. Differential tolerance to atrazine among the grasses studied was probably due to the metabolic route by which they detoxify atrazine and the rate of metabolism for that specific route. Intraspecific differences in atrazine tolerance in indiangrass were due to the amount of metabolite produced in relationship to the amount of parent atrazine remaining in the shoot tissue. The more tolerant indiangrass lines had a higher metabolite to parent atrazine ratio than susceptible lines. This study confirmed differences in seedling atrazine tolerance of four indiangrass lines observed in previous greenhouse studies. Nomenclature: Atrazine, 6- chloro -N- ethyl - N\u27 -(1- methylethyl) -1,3,5 -triazine- 2,4-diamine; big bluestem, Andropogon gerardii Vitman; switchgrass, Panicum virgatum L.; indiangrass, Sorghastrum nutans (L.) Nash; sideoats grama, Bouteloua curtipendula (Michx.) Torr

    Circular quiver gauge theories, isomonodromic deformations and WN fermions on the torus

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    We study the relation between class S theories on punctured tori and isomonodromic deformations of flat SL(N) connections on the two-dimensional torus with punctures. Turning on the self-dual Ω -background corresponds to a deautonomization of the Seiberg–Witten integrable system which implies a specific time dependence in its Hamiltonians. We show that the corresponding τ-function is proportional to the dual gauge theory partition function, the proportionality factor being a nontrivial function of the solution of the deautonomized Seiberg–Witten integrable system. This is obtained by mapping the isomonodromic deformation problem to WN free fermion correlators on the torus

    The accuracy of sentinel lymph-node biopsy in breast cancer after previous excisional biopsy

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    Scopo: La biopsia del linfonodo sentinella (BLS) nel carcinoma della mammella con linfonodi ascellari clinicamente negativi \ue8 considerato la migliore scelta per stadiare il cavo ascellare. Inizialmente una precedente biopsia escissionale del carcinoma era considerata una controindicazione. Esaminiamo il tasso di successo della BLS e la incidenza della recidiva a livello ascellare in pazienti con carcinoma della mammella precedentemente sottoposti a biopsia escissionale del tumore. Pazienti e metodi: 858 pazienti con carcinoma della mammella sono stati sottoposti a BLS e i pazienti con linfonodi sentinella metastatici a svuotamento del cavo ascellare; 82 pazienti erano stati sottoposti precedentemente a biopsia escissionale del tumore. Risultati: Il linfonodo sentinella \ue8 stato identificato nel 100% dei casi, \ue8 risultato indenne nel 74,4% e metastatico nel 23,1%. La dissezione del cavo ascellare \ue8 stata effettuata in tutti i casi con linfonodi sentinella metastatici e nel 74% dei casi non si sono ritrovati altri linfonodi ascellari metastatici. Il follow-up mediano \ue8 stato di 63,5 mesi e non si sono osservate recidive ascellari. Conclusioni: L\u2019accuratezza del BLS in pazienti con carcinoma della mammella sottoposte precedentemente a biopsia escissionale \ue8 uguale a quella dei pazienti non sottoposti a biopsia.Aim: Sentinel node biopsy (SLNB) is considered to be the standard of care for staging the axilla in clinically node-negative women with breast cancer. A previous breast excisional biopsy has been considered a contraindication to the use of SLNB.We examined the success rate of SLN localization and then the evaluation of the incidence of axillary relapse in patients with breast cancer undergoing excisional biopsy. Patients and Methods: 858 patients with breast carcinoma underwent a SLNB and only positive sentinel nodes were submitted to axillary dissection; 82 patients had undergone an excisional biopsy before. Results: The sentinel node was identified in 100% of cases, it was negative in 74.4% and positive in 23.1%. Complete axillary dissection was performed in all positive cases, and in 74% of cases no other positive nodes were found. The follow-up median was 63.5 months and no axillary recurrence was observed. Conclusions: SLNB accuracy in breast cancer patients who have previously undergone excisional biopsy is comparable with that in patients undergoing no excisional biopsy, so that it may be considered a standard procedure

    Rooting and carbohydrate availability in Vitis 140 Ruggeri stem cuttings

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    Rooting in Vitis 140 Ruggeri rootstock appears to be correlated to the availability of soluble carbohydrates in the cuttings. This relationship was verified using stem cuttings collected from December to April by comparing those propagated after cold storage (C) with those collected directly in the field (F). The basal end of some of the cuttings of both groups (C and F) were dipped into deionized water before propagation (CW and FW). The mobilization of soluble carbohydrates paralleled with the pattern of the rooting process. In the cold stored material, rooting took place earlier than in the field material. The mobilization of soluble carbohydrates occurred at two stages: during the storage period at 2 °C (50% if compared with the cuttings collected in the field) and during the first 20 d of rooting. On day 20, the carbohydrate content was reduced by 80%. Rooting and carbohydrate availability appear to be associated

    Produção de matéria seca, extração e utilização de nitrogênio em aveia adubada com uréia em mistura com zeólita.

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    A perda de nitrogênio (N) por volatilização de amônia é um dos principais fatores responsáveis pela baixa eficiência da uréia aplicada sobre a superfície do solo. A redução das perdas por volatilização pode ser obtida com o de zeólitas como aditivo à uréia. Zeólitas são minerais alumino-silicatos cristalinos hidratados de metais alcalinos ou alcalinos-terrosos, estruturados em redes cristalinas tridimensionais rígidas, formadas por tetraedros de AlO4 e SiO4 e de ocorrência natural. O objetivo deste trabalho foi avaliar o efeito da mistura de zeólita à uréia na adubação nitrogenada da aveia sobre a produção de matéria seca, extração e utilização de nitrogênio. O delineamento experimental adotado foi em blocos ao acaso em esquema fatorial 2X2X2X4, com 3 repetições. Os tratamentos foram 2 tipos de zeólita estilbita (natural = 470 g kg-1 e concentrada = 650 g kg-1), 2 granulometrias (<1mm e <0,3mm), 2 níveis de nitrogênio (100 e 200 mg kg-1 ); e 4 relações de zeólita (testemunha, 25, 50 e 100% m/m da dose de N). Os tratamentos foram aplicados na adubação da aveia conduzida em vasos e em casa-de-vegetação. Os melhores resultados de produção de matéria seca foram obtidos a dose de 200 mg kg-1 de N em mistura com 59,8% de zeólita concentrada (650 g kg-1 de estilbita). A melhor eficiência de uso foi alcançada com o uso das doses mais baixas de nitrogênio da uréia

    On the Angular Resolution of the AGILE gamma-ray imaging detector

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    We present a study of the Angular Resolution of the AGILE gamma-ray imaging detector (GRID) that is operational in space since April 2007. The AGILE instrument is made of an array of 12 planes each equipped with a Tungsten converter and Silicon micros trip detectors and is sensitive in the energy range 50 MeV - 10 GeV. Among the space instruments devoted to gamma-ray astrophysics, AGILE uniquely exploits an analog readout system with dedicated electronics coupled with Silicon detectors. We show the results of Monte Carlo simulations carried out to reproduce the gamma-ray detection by the GRID, and we compare them to in-flight data. We use the Crab (pulsar + Nebula) system for discussion of real data performance, since its E^{-2} energy spectrum is representative of the majority of gamma-ray sources. For Crab-like spectrum sources, the GRID angular resolution (FWHM of ~4deg at 100 MeV; ~0.8deg at 1 GeV; ~0.9deg integrating the full energy band from 100 MeV to tens of GeV) is stable across a large field of view, being characterized by a flat response up to 30deg off-axis. A comparison of the angular resolution obtained by the two operational gamma-ray instruments, AGILE-GRID and Fermi-LAT, is interesting in view of future gamma-ray missions, that are currently under study. The two instruments exploit different detector configurations affecting the angular resolution: the former being optimized in the readout and track reconstruction especially in the low-energy band, the latter in terms of converter thickness and power consumption. We show that, despite these differences, the angular resolution of both instruments is very similar between 100 MeV and a few GeV.Comment: 19 pages, 8 figures, accepted for publication in Ap
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