Fermi LAT observations of cosmic-ray electrons from 7 GeV to 1 TeV

We present the results of our analysis of cosmic-ray electrons using about 8 million electron candidates detected in the first 12 months on-orbit by the Fermi Large Area Telescope. This work extends our previously-published cosmic-ray electron spectrum down to 7 GeV, giving a spectral range of approximately 2.5 decades up to 1 TeV. We describe in detail the analysis and its validation using beam-test and on-orbit data. In addition, we describe the spectrum measured via a subset of events selected for the best energy resolution as a cross-check on the measurement using the full event sample. Our electron spectrum can be described with a power law $\propto {\rm E}^{-3.08 \pm 0.05}$ with no prominent spectral features within systematic uncertainties. Within the limits of our uncertainties, we can accommodate a slight spectral hardening at around 100 GeV and a slight softening above 500 GeV.Comment: 20 pages, 23 figures, 2 tables, published in Physical Review D 82, 092004 (2010) - contact authors: C. Sgro', A. Moisee

Grassroots Agency: Participation and Conflict in Buenos Aires Shantytowns seen through the Pilot Plan for Villa 7 (1971–1975)

open access articleIn 1971, after more than a decade of national and municipal policies aimed at the top-down removal of shantytowns, the Buenos Aires City Council approved the Plan Piloto para la Relocalización de Villa 7 (Pilot Plan for the Relocation of Shantytown 7; 1971–1975, referred to as the Pilot Plan hereinafter). This particular plan, which resulted in the construction of the housing complex, Barrio Justo Suárez, endures in the collective memory of Argentines as a landmark project regarding grassroots participation in state housing initiatives addressed at shantytowns. Emerging from a context of a housing shortage for the growing urban poor and intense popular mobilizations during the transition to democracy, the authors of the Pilot Plan sought to empower shantytown residents in novel ways by: 1) maintaining the shantytown’s location as opposed to eradication schemes that relocated the residents elsewhere, 2) formally employing some of the residents for the stage of construction, as opposed to “self-help” housing projects in which the residents contributed with unpaid labor, and 3) including them in the urban and architectural design of the of the new housing. This paper will examine the context in which the Pilot Plan was conceived of as a way of re-assessing the roles of the state, the user, and housing-related professionals, often seen as antagonistic. The paper argues that residents’ fair participation and state intervention in housing schemes are not necessarily incompatible, and can function in specific social and political contexts through multiactor proposals backed by a political will that prioritizes grassroots agency

The On-orbit Calibrations for the Fermi Large Area Telescope

The Large Area Telescope (LAT) on--board the Fermi Gamma ray Space Telescope began its on--orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here we describe on orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009.Comment: 60 pages, 34 figures, submitted to Astroparticle Physic

Trattamenti con oli essenziali per il controllo di nematodi fitoparassiti

L’esigenza di una maggiore tutela dell’ambiente e della salute umana impone in misura crescente l’esigenza di una parziale o totale sostituzione degli agrofarmaci di sintesi con prodotti più sostenibili nella lotta contro patogeni e parassiti delle colture agrarie, tra cui anche i nematodi. Gli oli essenziali (OE) ed i loro componenti attivi possono costituire una fonte di nuovi prodotti nematocidi ad elevata sostenibilità, in quanto uniscono ad una buona efficacia nematocida un ridotto impatto sull’ambiente e l’uomo grazie alla loro elevata volatilit

Effects of phytoplasma presence on the chemical composition of essential oils from Grindelia robusta Nutt., Echinacea purpurea Moench., and Monarda fistulosa L.

Plants are well recognized to change the secondary metabolites pattern of biosynthetic pathways in response to virus, bacteria, phytoplasma or fungi infections, and/or attacks by phytophagous insects. Most of these secondary metabolites are represented by volatile semiochemicals used as chemical defence in the sense of repellency. Such changes in the phytochemical profile greatly affect the quality and the commercial value of plants used for medicinal and cosmetic purposes. As a continuation of our studies aimed to verify the effect of phytoplasma infections on the volatile chemicals production, we report the differences detected between healthy and infected plants of Grindelia robusta Nutt. (Asteraceae), Echinacea purpurea Moench. (Asteraceae), and Monarda fistulosa L. (Lamiaceae), all species of great importance in the medicinal practice and grown at the Herb Garden of Casola Valsenio (Ravenna, Emilia Romagna region, northern Italy). Before flowering, only a few yellow symptoms were present on the leaves; however in some cases, the plants showed reduction of leaf size and stunting; whereas, at blooming, severe virescence and phyllody symptoms were observed. Samples from symptomatic plants were collected and tested for phytoplasma presence. Nested PCR/RFLP analyses on 16Sr DNA gene confirmed that in all the symptomatic samples examined phytoplasmas identified belonged to ribosomal subgroup 16SrI-B (Aster yellows: AY, \u2018Candidatus Phytoplasma asteris\u2019) in the case of G. robusta and E. purpurea, and to ribosomal soubgroup 16SrXII-A stolbur, for M. fistulosa. These two phytoplasmas are associated with a number of economically important diseases worldwide and recent reports indicated the presence of stolbur phytoplasmas in hyssop (Hyssopus officinalis) and in Parietaria spp., and of AY in woolly foxglove (Digitalis lanata). Essential oils were obtained from aerial parts of healthy and phytoplasma-infected plants by hydrodistillation followed by GC/MS analysis using a reported procedure. In all cases, significant differences in the chemical composition of essential oils were observed. In G. robusta infected plants, a higher percentage of limonene, borneol (both almost > 50%), and borneol acetate (15% in healthy plants and 21.3% in infected ones) were detected. Essential oil of E. purpurea revealed differences for limonene (2.2% in healthy plants and 4.4% in infected ones), cis-verbenol (1.8% and 5.6% respectively), verbenone (2.7% and 11.4%), and to a lesser extent carvone (0.8% to 2.5%). Infection by phytoplasmas belonging to ribosomal soubgroup 16SrXII-A stolbur in M. fistulosa led to an increase of monoterpene hydrocarbons such as \uf061-thujene, \uf061-pinene, \uf0443-carene, and myrcene and to a decrease in aromatic monoterpene like p-cymene and thymol. Phytoplasmas have an appreciable influence in the content of secondary metabolites and these three species increase the concentration of the above cited monotherpens as chemical response to the presence of these pathogens