199 research outputs found

    Deciphering the large-scale environment of radio galaxies in the local Universe: where do they born, grow and die?

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    The role played by the large-scale environment on the nuclear activity of radio galaxies (RGs), is still not completely understood. Accretion mode, jet power and galaxy evolution are connected with their large-scale environment from tens to hundreds of kpc. Here we present a detailed, statistical, analysis of the large-scale environment for two samples of RGs up to redshifts zsrcz_\mathrm{src}=0.15. The main advantages of our study, with respect to those already present in the literature, are due to the extremely homogeneous selection criteria of catalogs adopted to perform our investigation. This is also coupled with the use of several clustering algorithms. We performed a direct search of galaxy-rich environments around RGs using them as beacon. To perform this study we also developed a new method that does not appear to suffer by a strong zsrcz_\mathrm{src} dependence as other algorithms. We conclude that, despite their radio morphological (FR\,I vsvs FR\,II) and/or their optical (HERG vsvs LERG) classification, RGs in the local Universe tend to live in galaxy-rich large-scale environments having similar characteristics and richness. We highlight that the fraction of FR\,Is-LERG, inhabiting galaxy rich environments, appears larger than that of FR\,IIs-LERG. We also found that 5 out of 7 FR\,II-HERGs, with zsrc≀z_\mathrm{src}\leq0.11, lie in groups/clusters of galaxies. However, we recognize that, despite the high level of completeness of our catalogs, when restricting to the local Universe, the low number of HERGs (∌\sim10\% of the total FR\,IIs investigated) prevent us to make a strong statistical conclusion about this source class.Comment: 21 pages, 25 figures, accepted for publication on the Astrophysical Journal Supplement Series - pre-proof versio

    Effetti cardiorespiratori degli sprint ripetuti in giovani calciatori

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    Scopo: Nel calcio la performance dipende da attivitĂ  caratterizzate da sforzi di breve durata, talora ad alta intensitĂ , con ridotti tempi di recupero. Questo tipo di sforzo puĂČ avere maggiore potenzialitĂ  aritmogena rispetto a sforzi, anche massimali, iniziati e terminati in modo graduale. Gli sprint ripetuti permettono di valutare la performance e lo stato di allenamento in giovani calciatori. Scopo del nostro lavoro Ăš stato quello di valutare gli effetti degli sprint ripetuti sul sistema cardiorespiratorio in giovani calciatori delle rappresentative regionali siciliane della FIGC. Metodi: Sono stati esaminati 12 calciatori, di etĂ  media di 15±1 anni. Per valutare lo stato di fitness cardiorespiratoria sono stati determinati, al test da sforzo incrementale massimale al treadmill (SI), il VO2max in ml.Kg-1.min-1 (VO2maxSI) e la FCmax in bpm (FCmaxSI). Per valutare gli effetti cardiorespiratori degli sprint ripetuti, gli atleti hanno eseguito un test da sforzo al cicloergometro a freno meccanico (SR) che prevedeva 10 sprint massimali “all-out” di 6 sec, intervallati da 30 sec di recupero passivo. Nella serie dei 10 sprint, sono stati determinati il valore piĂč elevato di VO2 in ml.Kg-1.min-1 (VO2maxSR) e di FC in bpm (FCmaxSR). Risultati: Il valore medio di VO2maxSI (56,22±3,93 ml.Kg-1.min-1) indica che i soggetti esaminati hanno un buon livello di potenza aerobica, raggiunta ad una FCmaxSI di 190±8 bpm. I dati di VO2maxSR rilevati al test degli sprint ripetuti evidenziano un valore medio di 42,67±5,57 ml.Kg-1.min-1 (70% del VO2maxSI), raggiunto ad una FCmaxSR di 175±11 bpm (92% della FCmaxSI). Conclusioni: I dati del nostro studio indicano che nei soggetti esaminati gli sprint ripetuti determinano incrementi della frequenza cardiaca rapidi, elevati e persistenti nella fase di recupero. Questo dato deve essere preso in considerazione non solo per la valutazione della performance ma anche nella formulazione dell’idoneitĂ  a praticare la disciplina sportiva del calcio

    The 0.03-10Mo mass function of young open clusters

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    We report the present day mass functions (PDMFs) of 3 young open clusters over a mass range from 30 Jupiter masses to 10~\msunn. The PDMFs of the 3 clusters are remarkably similar, suggesting little impact of specific conditions (stellar density, metallicity, early dynamical evolution) on the mass distribution. Functional forms are provided to allow quantitative comparison with MFs derived in other environments.Comment: 6 pages, to appear in "IMF@50", Corbelli, Palla, Zinnecker ed

    Validity and reliability of an inertial sensor device for specific running patterns in soccer

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    Electronic performance tracking devices are largely employed in team sports to monitor performance and improve training. To date, global positioning system (GPS) based devices are those mainly used in soccer training. The aim of this study was to analyse the validity and reliability of the inertial sensor device (ISD) in monitoring distance and speed in a soccer-specific circuit and how their performance compare to a GPS system. 44 young male soccer players (age: 14.9 ± 1.1, range 9– 16, years, height: 1.65 ± 0.10 m, body mass: 56.3 ± 8.9 kg) playing in a non-professional soccer team in Italy, participated in the study. We assessed the players trough a soccer running sport-specific circuit. An ISD and a GPS were used to assess distance and speed. Data was compared to a video reference system, and the difference were quantified by means of the root mean square error (RMSE). Significant differences were found for both GPS and ISD devices for distance and speed. However, lower error for distance (dRMSE 2.23 ± 1.01 m and 5.75 ± 1.50 m, respectively) and speed (sRMSE 0.588 ± 0.152 m*s–1 and 1.30 ± 0.422 m*s–1, respectively) were attained by the ISD compared to the GPS. Overall, our results revealed a statistically significant difference between systems in data monitoring for either distance and speed. However, results of this study showed that a smaller error was obtained with the ISD than the GPS device. Despite caution is warranted within the interpreta-tion of these results, we observed a better practical applicability of the ISD due to its small size, lower cost and the possibility to use the device indoor

    Temporal variations in the evaporating atmosphere of the exoplanet HD 189733b

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    Atmospheric escape has been detected from the exoplanet HD 209458b through transit observations of the hydrogen Lyman-alpha line. Here we present spectrally resolved Lyman-alpha transit observations of the exoplanet HD 189733b at two different epochs. These HST/STIS observations show for the first time, that there are significant temporal variations in the physical conditions of an evaporating planetary atmosphere. While atmospheric hydrogen is not detected in the first epoch observations, it is observed at the second epoch, producing a transit absorption depth of 14.4+/-3.6% between velocities of -230 to -140 km/s. Contrary to HD 209458b, these high velocities cannot arise from radiation pressure alone and require an additional acceleration mechanism, such as interactions with stellar wind protons. The observed absorption can be explained by an atmospheric escape rate of neutral hydrogen atoms of about 10^9 g/s, a stellar wind with a velocity of 190 km/s and a temperature of ~10^5K. An X-ray flare from the active star seen with Swift/XRT 8 hours before the second-epoch observation supports the idea that the observed changes within the upper atmosphere of the planet can be caused by variations in the stellar wind properties, or by variations in the stellar energy input to the planetary escaping gas (or a mix of the two effects). These observations provide the first indication of interaction between the exoplanet's atmosphere and stellar variations.Comment: To be published in A&A Letters, June 28, 201
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