CHARACTERIZATION OF PATHOGENIC E. COLI ISOLATED IN SHEEP AT SLAUGHTERHOUSE

Fleeces, carcass surface, mucosal gut and faeces samples, collected from 95 slaughtered sheep and lambs from three abattoirs, were examined. The aim of this study was: 1) to evaluate the prevalence of the Verocytotoxic E. coli (VTEC); 2) to obtain virulence profile (stx1, stx2, hlyA and eae) by multiplex PCR; 3) to define the ovine-specific serogroup pathogenic power for the humans. An overall prevalence of 11.1% (adults 14%, lambs 7.8%) was found by direct PCR test. The VTEC occurrence was 18.9% in fleeces, 14.7% on carcasses and 10.5% in mucosal gut. According to the multiplex PCR the following results were obtained: 21% of the isolates belonged to VTEC pathogroup, within 92% were EHEC; 37.9% were identified as EPEC pathogroup. Forty one % of the strains were negative for all the genes. None of the isolates belonged to O157 and 0146 serogroups, while the 57% resulted O91

An Indication of Anisotropy in Arrival Directions of Ultra-high-energy Cosmic Rays through Comparison to the Flux Pattern of Extragalactic Gamma-Ray Sources

A new analysis of the data set from the Pierre Auger Observatory provides evidence for anisotropy in the arrival directions of ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative of excess arrivals from strong, nearby sources. The data consist of 5514 events above 20 EeV with zenith angles up to 80 degrees. recorded before 2017 April 30. Sky models have been created for two distinct populations of extragalactic gamma-ray emitters: active galactic nuclei from the second catalog of hard Fermi-LAT sources (2FHL) and starburst galaxies from a sample that was examined with Fermi-LAT. Flux-limited samples, which include all types of galaxies from the Swift-BAT and 2MASS surveys, have been investigated for comparison. The sky model of cosmic-ray density constructed using each catalog has two free parameters, the fraction of events correlating with astrophysical objects, and an angular scale characterizing the clustering of cosmic rays around extragalactic sources. A maximum-likelihood ratio test is used to evaluate the best values of these parameters and to quantify the strength of each model by contrast with isotropy. It is found that the starburst model fits the data better than the hypothesis of isotropy with a statistical significance of 4.0 sigma, the highest value of the test statistic being for energies above 39 EeV. The three alternative models are favored against isotropy with 2.7 sigma-3.2 sigma significance. The origin of the indicated deviation from isotropy is examined and prospects for more sensitive future studies are discussed

Inferences on mass composition and tests of hadronic interactions from 0.3 to 100 EeV using the water-Cherenkov detectors of the Pierre Auger Observatory

We present a new method for probing the hadronic interaction models at ultrahigh energy and extracting details about mass composition. This is done using the time profiles of the signals recorded with the water-Cherenkov detectors of the Pierre Auger Observatory. The profiles arise from a mix of the muon and electromagnetic components of air showers. Using the risetimes of the recorded signals, we define a new parameter, which we use to compare our observations with predictions from simulations. We find, first, inconsistencies between our data and predictions over a greater energy range and with substantially more events than in previous studies. Second, by calibrating the new parameter with fluorescence measurements from observations made at the Auger Observatory, we can infer the depth of shower maximum Xmax for a sample of over 81,000 events extending from 0.3 to over 100 EeV. Above 30 EeV, the sample is nearly 14 times larger than what is currently available from fluorescence measurements and extending the covered energy range by half a decade. The energy dependence of ?Xmaxcopyright is compared to simulations and interpreted in terms of the mean of the logarithmic mass. We find good agreement with previous work and extend the measurement of the mean depth of shower maximum to greater energies than before, reducing significantly the statistical uncertainty associated with the inferences about mass composition

CHARACTERIZATION OF PATHOGENIC E. COLI ISOLATED IN SHEEP AT SLAUGHTERHOUSE

Fleeces, carcass surface, mucosal gut and faeces samples, collected from 95 slaughtered sheep and lambs from three abattoirs, were examined. The aim of this study was: 1) to evaluate the prevalence of the Verocytotoxic E. coli (VTEC); 2) to obtain virulence profile (stx1, stx2, hlyA and eae) by multiplex PCR; 3) to define the ovine-specific serogroup pathogenic power for the humans. An overall prevalence of 11.1% (adults 14%, lambs 7.8%) was found by direct PCR test. The VTEC occurrence was 18.9% in fleeces, 14.7% on carcasses and 10.5% in mucosal gut. According to the multiplex PCR the following results were obtained: 21% of the isolates belonged to VTEC pathogroup, within 92% were EHEC; 37.9% were identified as EPEC pathogroup. Forty one % of the strains were negative for all the genes. None of the isolates belonged to O157 and 0146 serogroups, while the 57% resulted O91

Valutazione dei parametri di sicurezza alimentare in Tapes decussatus e Cerastoderma spp. provenienti dal banco naturale della laguna di Corru S\u2019Ittiri (OR)

Nel presente lavoro vengono riportati i risultati di un\u2019indagine, condotta nel 2010, allo scopo di valutare la presenza di alcuni contaminanti batterici e virali di interesse per la sicurezza e la salute dei consumatori in molluschi bivalvi raccolti presso il banco naturale della laguna di Corru S\u2019Ittiri. Si trattava di molluschi appar-tenenti all\u2019ordine Veneroidae, in particolare di vongole veraci (Tapes decussatus) e cuori (Cerastoderma spp.). I risultati hanno evidenziato che i molluschi possono essere contaminati da E. coli VTEC e suggeriscono la presenza del rischio di inquinamento di origine agro-zootecnica nella zona considerata, che funge anche da bacino di raccolta di acque di bonifica. Il riscontro nei molluschi di NoV appartenenti ai genotipi GI e GII, che sono stati coinvolti in episodi di infezione umana, assume un importante significato sanitario, in relazione alla capacit\ue0 di tali virus di resistere nell\u2019ambiente, in presenza di condizioni favorevoli, per periodi pi\uf9 o meno lunghi. Infatti, nella laguna oggetto dell\u2019indagine, si potrebbero verificare eventi che determinano l\u2019aumento del rischio di contaminazione virale, tra i quali piogge abbondanti (nella zona gli sbalzi stagionali sono notevoli), che possono provocare la tracimazione di liquami non ancora depurati, o inefficienze nei sistemi di depurazione, che aumentano la dispersione virale nell\u2019ambiente

Search for Ultra-High Energy Photons with the Pierre Auger Observatory

One of key scientific objectives of the Pierre Auger Observatory is the search for ultra-high energy photons. Such photons could originate either in the interactions of energetic cosmic-ray nuclei with the cosmic microwave background (so-called cosmogenic photons) or in the exotic scenarios, e.g. those assuming a production and decay of some hypothetical super-massive particles. The latter category of models would imply relatively large fluxes of photons with ultra-high energies at Earth, while the former, involving interactions of cosmic-ray nuclei with the microwave background - just the contrary: very small fractions. The investigations on the data collected so far in the Pierre Auger Observatory led to placing very stringent limits to ultra-high energy photon fluxes: below the predictions of the most of the exotic models and nearing the predicted fluxes of the cosmogenic photons. In this paper the status of these investigations and perspectives for further studies are summarized

Observation of inclined EeV air showers with the radio detector of the Pierre Auger Observatory

With the Auger Engineering Radio Array (AERA) of the Pierre Auger Observatory, we have observed the radio emission from 561 extensive air showers with zenith angles between 60 and 84. In contrast to air showers with more vertical incidence, these inclined air showers illuminate large ground areas of several km2 with radio signals detectable in the 30 to 80 MHz band. A comparison of the measured radio-signal amplitudes with Monte Carlo simulations of a subset of 50 events for which we reconstruct the energy using the Auger surface detector shows agreement within the uncertainties of the current analysis. As expected for forward-beamed radio emission undergoing no significant absorption or scattering in the atmosphere, the area illuminated by radio signals grows with the zenith angle of the air shower. Inclined air showers with EeV energies are thus measurable with sparse radio-antenna arrays with grid sizes of a km or more. This is particularly attractive as radio detection provides direct access to the energy in the electromagnetic cascade of an air shower, which in case of inclined air showers is not accessible by arrays of particle detectors on the ground

A 3-Year Sample of Almost 1,600 Elves Recorded Above South America by the Pierre Auger Cosmic-Ray Observatory

Elves are a class of transient luminous events, with a radial extent typically greater than 250 km, that occur in the lower ionosphere above strong electrical storms. We report the observation of 1,598 elves, from 2014 to 2016, recorded with unprecedented time resolution (100 ns) using the fluorescence detector (FD) of the Pierre Auger Cosmic-Ray Observatory. The Auger Observatory is located in the Mendoza province of Argentina with a viewing footprint for elve observations of 3.106 km2, reaching areas above the Pacific and Atlantic Oceans, as well as the Córdoba region, which is known for severe convective thunderstorms. Primarily designed for ultrahigh energy cosmic-ray observations, the Auger FD turns out to be very sensitive to the ultraviolet emission in elves. The detector features modified Schmidt optics with large apertures resulting in a field of view that spans the horizon, and year-round operation on dark nights with low moonlight background, when the local weather is favorable. The measured light profiles of 18% of the elve events have more than one peak, compatible with intracloud activity. Within the 3-year sample, 72% of the elves correlate with the far-field radiation measurements of the World Wide Lightning Location Network. The Auger Observatory plans to continue operations until at least 2025, including elve observations and analysis. To the best of our knowledge, this observatory is the only facility on Earth that measures elves with year-round operation and full horizon coverage. ©2020. The Authors

Data-driven estimation of the invisible energy of cosmic ray showers with the Pierre Auger Observatory

The determination of the primary energy of extensive air showers using the fluorescence detection technique requires an estimation of the energy carried away by particles that do not deposit all their energy in the atmosphere. This estimation is typically made using Monte Carlo simulations and thus depends on the assumed primary particle mass and on model predictions for neutrino and muon production. In this work we present a new method to obtain the invisible energy from events detected by the Pierre Auger Observatory. The method uses measurements of the muon number at ground level, and it allows us to reduce significantly the systematic uncertainties related to the mass composition and the high energy hadronic interaction models, and consequently to improve the estimation of the energy scale of the Observatory.Comment: Published version, 18 pages, 10 figures, 4 table