24 research outputs found

    Periodic Emission from the Gamma-ray Binary 1FGL J1018.6-5856

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    Gamma-ray binaries are stellar systems containing a neutron star or black hole with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable X-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.Comment: Contact authors: R.H.D. Corbet, M. Kerr, C.C. Cheun

    DEVELOPMENT of the MODEL of GALACTIC INTERSTELLAR EMISSION for STANDARD POINT-SOURCE ANALYSIS of FERMI LARGE AREA TELESCOPE DATA

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    Most of the celestial \u3b3 rays detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. Here, we describe the development of the Galactic Interstellar Emission Model (GIEM), which is the standard adopted by the LAT Collaboration and is publicly available. This model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse-Compton emission produced in the Galaxy. In the GIEM, we also include large-scale structures like Loop I and the Fermi bubbles. The measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20\ub0 and we observe an enhanced emission toward their base extending in the north and south Galactic directions and located within \u2dc4\ub0 of the Galactic Center

    Large-breast reconstruction using fat graft only after prosthetic reconstruction failure.

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    BACKGROUND: When prosthetic reconstruction fails, and in the case of absolute contraindications to flaps use, no common reconstructive option is available. METHODS: A large irradiated breast was reconstructed using only fat grafts (9 sessions) after prosthetic reconstruction failure (exposure of implant) due to absolute contraindications to general anesthesia and unavailability of large flaps. During the first four sessions small volumes were implanted in the extremely rigid and retracted tissues with regenerative purposes. Larger volumes were implanted during the last five sessions to improve volume and shape. RESULTS: A pleasant aesthetic result was achieved. Tissue regeneration with good vascular support was evident at ultrasonography and magnetic resonance. Histologic and ultrastructural examination of the new tissue showed normal adipose tissue with cell and vasculostromal maturation aspects. No degenerative or inflammatory aspects were present. CONCLUSION: Fat graft transplantation can be a reliable and safe option for breast reconstruction in selected patients

    Large-Breast Reconstruction Using Fat Graft Only after Prosthetic Reconstruction Failure

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    Background: When prosthetic reconstruction fails, and in the case of absolute contraindications to flaps use, no common reconstructive option is available. Methods: A large irradiated breast was reconstructed using only fat grafts (9 sessions) after prosthetic reconstruction failure (exposure of implant) due to absolute contraindications to general anesthesia and unavailability of large flaps. During the first four sessions small volumes were implanted in the extremely rigid and retracted tissues with regenerative purposes. Larger volumes were implanted during the last five sessions to improve volume and shape. Results: A pleasant aesthetic result was achieved. Tissue regeneration with good vascular support was evident at ultrasonography and magnetic resonance. Histologic and ultrastructural examination of the new tissue showed normal adipose tissue with cell and vasculostromal maturation aspects. No degenerative or inflammatory aspects were present. Conclusion: Fat graft transplantation can be a reliable and safe option for breast reconstruction in selected patients

    Combined evaluation of resting IGF1, N-terminal propeptide of type III procollagen and C-terminal cross-linked telopeptide of type I collagen levels might be useful for detecting inappropriate GH administration in female athletes

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    OBJECTIVE: To detect exogenous recombinant human GH (rhGH) abuse in female athletes. DESIGN: GH-dependent markers were assayed in serum of 100 female athletes (control group) and in a subgroup of nine female subjects treated with rhGH (0.09 IU/kg body weight, 6 days/week for 3 weeks). METHODS: Cut-off values (mean+2 s.d.) for IGF1, N-terminal propeptide of type III procollagen (PIIINP) and C-terminal telopeptide of type I collagen (ICTP) were calculated and arbitrary scores (1.5 or 2.0) were assigned to abnormal markers. By using the sum of individual marker scores, positive (> or =3) or negative ( or =3). Abnormal IGF1, PIIINP and ICTP levels were found in 61.4, 54.5 and 11.4% samples of the treated group. Overall, positive cases were present in 43.2% blood samples drawn in subjects treated with rhGH and in 26% of samples after rhGH withdrawal. The sensitivity of the detection approach was 66.6% at the end of 3-week rhGH treatment and 11.1% at the 15th day of rhGH withdrawal, while the specificity was 100%. CONCLUSION: Detection test for rhGH administration appears less sensitive in female (66.6%) than in male athletes (previous observation, 100% after 3 weeks of comparable rhGH dose), but shows a similar specificity (98.5-100%). Since athletes supposedly use very high doses and long-term administration of rhGH for doping purposes, it is foreseen that the here-in detection test would in future increase its strength

    Irreversible respiratory failure in an achondroplastic child: the importance of an early cervicomedullary decompression, and a review of the literature.

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    the important role of SEPs in detection of cervicomedullary compression in achondroplastic children and also stress the necessity of an early surgical treatment as the only condition for possible clinical improvement and/or full recovery

    NEW FERMI-LAT EVENT RECONSTRUCTION REVEALS MORE HIGH-ENERGY GAMMA RAYS FROM GAMMA-RAY BURSTS

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    Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy (~147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region

    Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares

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    We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO. All three flares are associated with very fast coronal mass ejections (CMEs) and strong solar energetic particle events. We present updated localizations of the >100 MeV photon emission, hard X-ray (HXR)and EUV images, and broadband spectra from 10 keV to 10 GeV, as well as microwave spectra. We also provide a comparison of the BTL flares detected by Fermi-LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop top with the accelerated electron spectra steepening at semirelativistic energies. The >100 MeV gamma-rays are best described by a pion-decay model resulting from the interaction of protons (and other ions) in a thick-target photospheric source. The protons are believed to have been accelerated (to energies >10 GeV) in the CME environment and precipitate down to the photosphere from the downstream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission

    Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares

    Get PDF
    We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO. All three flares are associated with very fast coronal mass ejections (CMEs) and strong solar energetic particle events. We present updated localizations of the >100 MeV photon emission, hard X-ray (HXR) and EUV images, and broadband spectra from 10 keV to 10 GeV, as well as microwave spectra. We also provide a comparison of the BTL flares detected by Fermi-LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop top with the accelerated electron spectra steepening at semirelativistic energies. The >100 MeV gamma-rays are best described by a pion-decay model resulting from the interaction of protons (and other ions) in a thick-target photospheric source. The protons are believed to have been accelerated (to energies >10 GeV) in the CME environment and precipitate down to the photosphere from the downstream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission
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