107 research outputs found

    AGILE Observations of the Gravitational Wave Event GW150914

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    We report the results of an extensive search in the AGILE data for a gamma-ray counterpart of the LIGO gravitational wave event GW150914. Currently in spinning mode, AGILE has the potential of covering with its gamma-ray instrument 80 % of the sky more than 100 times a day. It turns out that AGILE came within a minute from the event time of observing the accessible GW150914 localization region. Interestingly, the gamma-ray detector exposed about 65 % of this region during the 100 s time intervals centered at -100 s and +300 s from the event time. We determine a 2-sigma flux upper limit in the band 50 MeV - 10 GeV, UL=1.9×108ergcm2s1UL = 1.9 \times 10^{-8} \rm \, erg \, cm^{-2} \, s^{-1} obtained about 300 s after the event. The timing of this measurement is the fastest ever obtained for GW150914, and significantly constrains the electromagnetic emission of a possible high-energy counterpart. We also carried out a search for a gamma-ray precursor and delayed emission over timescales ranging from minutes to days: in particular, we obtained an optimal exposure during the interval -150 / -30 s. In all these observations, we do not detect a significant signal associated with GW150914. We do not reveal the weak transient source reported by Fermi-GBM 0.4 s after the event time. However, even though a gamma-ray counterpart of the GW150914 event was not detected, the prospects for future AGILE observations of gravitational wave sources are decidedly promising.Comment: 20 pages, 6 figures. Submitted to the Astrophysical Journal Letters on April 1, 201

    Large Anomalous Hall effect in a silicon-based magnetic semiconductor

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    Magnetic semiconductors are attracting high interest because of their potential use for spintronics, a new technology which merges electronics and manipulation of conduction electron spins. (GaMn)As and (GaMn)N have recently emerged as the most popular materials for this new technology. While Curie temperatures are rising towards room temperature, these materials can only be fabricated in thin film form, are heavily defective, and are not obviously compatible with Si. We show here that it is productive to consider transition metal monosilicides as potential alternatives. In particular, we report the discovery that the bulk metallic magnets derived from doping the narrow gap insulator FeSi with Co share the very high anomalous Hall conductance of (GaMn)As, while displaying Curie temperatures as high as 53 K. Our work opens up a new arena for spintronics, involving a bulk material based only on transition metals and Si, and which we have proven to display a variety of large magnetic field effects on easily measured electrical properties.Comment: 19 pages with 5 figure

    Production properties of K*(892) vector mesons and their spin alignment as measured in the NOMAD experiment

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    First measurements of K*(892) mesons production properties and their spin alignment in nu_mu charged current (CC) and neutral current (NC) interactions are presented. The analysis of the full data sample of the NOMAD experiment is performed in different kinematic regions. For K*+ and K*- mesons produced in nu_mu CC interactions and decaying into K0 pi+/- we have found the following yields per event: (2.6 +/- 0.2 (stat.) +/- 0.2 (syst.))% and (1.6 +/- 0.1 (stat.) +/- 0.1 (syst.))% respectively, while for the K*+ and K*- mesons produced in nu NC interactions the corresponding yields per event are: (2.5 +/- 0.3 (stat.) +/- 0.3 (syst.))% and (1.0 +/- 0.3 (stat.) +/- 0.2 (syst.))%. The results obtained for the rho00 parameter, 0.40 +/- 0.06 (stat) +/- 0.03 (syst) and 0.28 +/- 0.07 (stat) +/- 0.03 (syst) for K*+ and K*- produced in nu_mu CC interactions, are compared to theoretical predictions tuned on LEP measurements in e+e- annihilation at the Z0 pole. For K*+ mesons produced in nu NC interactions the measured rho00 parameter is 0.66 +/- 0.10 (stat) +/- 0.05 (syst).Comment: 20 p

    The organisation of physiotherapy for people with multiple sclerosis across Europe: a multicentre questionnaire survey

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    Background Understanding the organisational set-up of physiotherapy services across different countries is increasingly important as clinicians around the world use evidence to improve their practice. This also has to be taken into consideration when multi-centre international clinical trials are conducted. This survey aimed to systematically describe organisational aspects of physiotherapy services for people with multiple sclerosis (MS) across Europe. Methods Representatives from 72 rehabilitation facilities within 23 European countries completed an online web-based questionnaire survey between 2013 and 2014. Countries were categorised according to four European regions (defined by United Nations Statistics). Similarities and differences between regions were examined. Results Most participating centres specialized in rehabilitation (82 %) and neurology (60 %), with only 38 % specialising in MS. Of these, the Western based Specialist MS centres were predominately based on outpatient services (median MS inpatient ratio 0.14), whilst the Eastern based European services were mostly inpatient in nature (median MS inpatient ratio 0.5). In almost all participating countries, medical doctors - specialists in neurology (60 %) and in rehabilitation (64 %) - were responsible for referral to/prescription of physiotherapy. The most frequent reason for referral to/prescription of physiotherapy was the worsening of symptoms (78 % of centres). Physiotherapists were the most common members of the rehabilitation team; comprising 49 % of the team in Eastern countries compared to approximately 30 % in the rest of Europe. Teamwork was commonly adopted; 86 % of centres based in Western countries utilised the interdisciplinary model, whilst the multidisciplinary model was utilised in Eastern based countries (p = 0.046). Conclusion This survey is the first to provide data about organisational aspects of physiotherapy for people with MS across Europe. Overall, care in key organisational aspects of service provision is broadly similar across regions, although some variations, for example the models of teamwork utilised, are apparent. Organisational framework specifics should be considered anytime a multi-centre study is conducted and results from such studies are applied.PubMedWoSScopu

    High energy variability of 3C 273 during the AGILE multiwavelength campaign of December 2007-January 2008

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    55We report the results of a 3-week multi-wavelength campaign targeting the flat spectrum radio quasar 3C 273 carried out with the AGILE gamma-ray mission, covering the 30 MeV-50 GeV and 18-60 keV, the REM observatory (covering the near-IR and optical), Swift (nearUV/Optical, 0.2-10 keV and 15-50 keV), INTEGRAL (3-200 keV) and Rossi XTE (2-12 keV). This is the first observational campaign including gamma-ray data, after the last EGRET observations, more than 8 years ago. Aims. This campaign has been organized by the AGILE team with the aim of observing, studying and modelling the broad band energy spectrum of the source, and its variability on a week timescale, testing the emission models describing the spectral energy distribution of this source. Methods. Our study was carried out using simultaneous light curves of the source flux from all the involved instruments, in the different energy ranges, to search for correlated variability. Then a time-resolved spectral energy distribution was used for a detailed physical modelling of the emission mechanisms. Results. The source was detected in gamma-rays only in the second week of our campaign, with a flux comparable to the level detected by EGRET in June 1991. We found an indication of a possible anti-correlation between the emission at gamma-rays and at soft and hard X-rays, supported by the complete set of instruments. Instead, optical data do not show short term variability, as expected for this source. Only in two preceding EGRET observations (in 1993 and 1997) 3C 273 showed intra-observation variability in gamma-rays. In the 1997 observation, flux variation in gamma-rays was associated with a synchrotron flare. The energy-density spectrum with almost simultaneous data partially covers the regions of synchrotron emission, the big blue bump, and the inverse-Compton. We adopted a leptonic model to explain the hard X/gamma-ray emissions, although from our analysis hadronic models cannot be ruled out. In the adopted model, the soft X-ray emission is consistent with combined synchrotron-self Compton and external Compton mechanisms, while hard X and gamma-ray emissions are compatible with external Compton from thermal photons of the disk. Under this model, the time evolution of the spectral energy distribution is well interpreted and modelled in terms of an acceleration episode of the electron population, leading to a shift in the inverse Compton peak towards higher energies.openPacciani Luigi; Donnarumma I; Vittorini V; D'Ammando F; Fiocchi MT; Impiombato Domenico; Stratta G; Verrecchia F; Bulgarelli A; Chen Rongchang; Giuliani Andrea; Longo Francesco; Pucella Gianluca; Vercellone S; Tavani Marco; Argan A; Barbiellini Amidei Guido; Boffelli Fabrizio; Caraveo Patrizia; Cattaneo Paolo Walter; Cocco Veronica; Costa E; Del Monte Ettore; Di Cocco G; Evangelista Yuri; Feroci Marco; Froysland Tom Vidar; Fuschino F; Galli M; Gianotti F; Labanti C; Lapshov I; Lazzarotto F; Lipari Paolo; Marisaldi M; Mereghetti S; Morselli Aldo; Pellizzoni A; Perotti F; Picozza Piergiorgio; Prest Michela; Rapisarda Massimo; Soffitta P; Trifoglio M; Tosti Gino; Trois A; Vallazza Erik Silvio; Zanello Dino; Antonelli Lucio Angelo; Colafrancesco Sergio; Cutini Sara; Gasparrini Dario; Giommi P; Pittori Carlotta; Salotti LPacciani, Luigi; Donnarumma, I; Vittorini, V; D'Ammando, F; Fiocchi, Mt; Impiombato, Domenico; Stratta, G; Verrecchia, F; Bulgarelli, A; Chen, Rongchang; Giuliani, Andrea; Longo, Francesco; Pucella, Gianluca; Vercellone, S; Tavani, Marco; Argan, A; Barbiellini Amidei, Guido; Boffelli, Fabrizio; Caraveo, Patrizia; Cattaneo Paolo, Walter; Cocco, Veronica; Costa, E; Del Monte, Ettore; Di Cocco, G; Evangelista, Yuri; Feroci, Marco; Froysland Tom, Vidar; Fuschino, F; Galli, M; Gianotti, F; Labanti, C; Lapshov, I; Lazzarotto, F; Lipari, Paolo; Marisaldi, M; Mereghetti, S; Morselli, Aldo; Pellizzoni, A; Perotti, F; Picozza, Piergiorgio; Prest, Michela; Rapisarda, Massimo; Soffitta, P; Trifoglio, M; Tosti, Gino; Trois, A; Vallazza Erik, Silvio; Zanello, Dino; Antonelli Lucio, Angelo; Colafrancesco, Sergio; Cutini, Sara; Gasparrini, Dario; Giommi, P; Pittori, Carlotta; Salotti, L

    AGILE detection of delayed gamma-ray emission from GRB 080514B

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    GRB 080514B is the first gamma ray burst (GRB), since the time of EGRET, for which individual photons of energy above several tens of MeV have been detected with a pair-conversion tracker telescope. This burst was discovered with the Italian AGILE gamma-ray satellite. The GRB was localized by a cooperation between AGILE and the interplanetary network (IPN). The gamma-ray imager ( GRID) estimate of the position, obtained before the SuperAGILE-IPN localization, is found to be consistent with the burst position. The hard X-ray emission observed by SuperAGILE lasted about 7 s, while there is evidence that the emission above 30 MeV extends for a longer duration ( at least 13 s). Similar behavior has been seen from a few other GRBs observed with EGRET. However, during the brightest phases, the latter measurements were affected by instrumental dead time effects, resulting in only lower limits to the burst intensity. Thanks to the small dead time of the AGILE/GRID we could assess that in the case of GRB 080514B the gamma-ray to X-ray flux ratio changes significantly between the prompt and extended emission phase

    Overweight at age two years in a multi-ethnic cohort (ABCD study): the role of prenatal factors, birth outcomes and postnatal factors

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    <p>Abstract</p> <p>Background</p> <p>Childhood overweight/obesity is a major public health problem worldwide which disproportionally affects specific ethnic groups. Little is known about whether such differences already exist at an early age and which factors contribute to these ethnic differences. Therefore, the present study assessed possible ethnic differences in overweight at age 2 years, and the potential explanatory role of prenatal factors, birth outcomes and postnatal factors.</p> <p>Methods</p> <p>Data were derived from a multi-ethnic cohort in the Netherlands (the ABCD study). Weight and height data of 3,156 singleton infants at age 2 years were used. Five ethnic populations were distinguished: Dutch native (n = 1,718), African descent (n = 238), Turkish (n = 162), Moroccan (n = 245) and other non-Dutch (n = 793). Overweight status was defined by the International Obesity Task Force guidelines. The explanatory role of prenatal factors, birth outcomes and postnatal factors in ethnic disparities in overweight (including obesity) was assessed by logistic regression analysis.</p> <p>Results</p> <p>Compared to the native Dutch (7.1%), prevalence of overweight was higher in the Turkish (19.8%) and Moroccan (16.7%) group, whereas the prevalence was not increased in the African descent (9.2%) and other non-Dutch (8.8%) group. Although maternal pre-pregnancy body mass index partly explained the ethnic differences, the odds ratio (OR) of being overweight remained higher in the Turkish (OR: 2.66; 95%CI: 1.56-4.53) and Moroccan (OR: 2.11; 95%CI: 1.31-3.38) groups after adjusting for prenatal factors. The remaining differences were largely accounted for by weight gain during the first 6 months of life (postnatal factor). Maternal height, birth weight and gender were independent predictors for overweight at age 2 years, but did not explain the ethnic differences.</p> <p>Conclusion</p> <p>Turkish and Moroccan children in the Netherlands have 2- to 3-fold higher odds for being overweight at age 2 years, which is largely attributed to maternal pre-pregnancy BMI and weight gain during the first 6 months of life. Further study on the underlying factors of this early weight gain is required to tackle ethnic differences in overweight among these children.</p

    Gamma-ray burst detection with the AGILE mini-calorimeter

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    The mini-calorimeter (MCAL) instrument on-board the AGILE satellite is a non-imaging gamma-ray scintillation detector sensitive in the 300 keV-100 MeV energy range with a total on-axis geometrical area of 1400 cm(2). Gamma-ray bursts (GRBs) are one of the main scientific targets of the AGILE mission and the MCAL design as an independent self-triggering detector makes it a valuable all-sky monitor for GRBs. Furthermore MCAL is one of the very few operative instruments with microsecond timing capabilities in the MeV range

    Deletion of the Huntingtin Polyglutamine Stretch Enhances Neuronal Autophagy and Longevity in Mice

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    Expansion of a stretch of polyglutamine in huntingtin (htt), the protein product of the IT15 gene, causes Huntington's disease (HD). Previous investigations into the role of the polyglutamine stretch (polyQ) in htt function have suggested that its length may modulate a normal htt function involved in regulating energy homeostasis. Here we show that expression of full-length htt lacking its polyglutamine stretch (ΔQ-htt) in a knockin mouse model for HD (Hdh140Q/ΔQ), reduces significantly neuropil mutant htt aggregates, ameliorates motor/behavioral deficits, and extends lifespan in comparison to the HD model mice (Hdh140Q/+). The rescue of HD model phenotypes is accompanied by the normalization of lipofuscin levels in the brain and an increase in the steady-state levels of the mammalian autophagy marker microtubule-associate protein 1 light chain 3-II (LC3-II). We also find that ΔQ-htt expression in vitro increases autophagosome synthesis and stimulates the Atg5-dependent clearance of truncated N-terminal htt aggregates. ΔQ-htt's effect on autophagy most likely represents a gain-of-function, as overexpression of full-length wild-type htt in vitro does not increase autophagosome synthesis. Moreover, HdhΔQ/ΔQ mice live significantly longer than wild-type mice, suggesting that autophagy upregulation may be beneficial both in diseases caused by toxic intracellular aggregate-prone proteins and also as a lifespan extender in normal mammals
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