1,824 research outputs found

    AGB and SAGB stars: modelling dust production at solar metallicity

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    We present dust yields for asymptotic giant branch (AGB) and super--asymptotic giant branch (SAGB) stars of solar metallicity. Stars with initial mass 1.5 M⊙≤Mini≤3 M⊙1.5~M_{\odot} \leq M_{\rm ini} \leq 3~M_{\odot} reach the carbon star stage during the AGB phase and produce mainly solid carbon and SiC. The size and the amount of the carbon particles formed follows a positive trend with themass of the star; the carbon grains with the largest size (aC∼0.2μa_{\rm C} \sim 0.2\mum) are produced by AGB stars with Mini=2.5−3 M⊙M_{\rm ini} = 2.5-3~M_{\odot}, as these stars are those achieving the largest enrichment of carbon in the surface regions. The size of SiC grains, being sensitive to the surface silicon abundance, keeps around aSiC∼0.1μa_{\rm SiC} \sim 0.1\mum. The mass of carbonaceous dust formed is in the range 10−4−5×10−3 M⊙10^{-4} - 5\times 10^{-3}~M_{\odot}, whereas the amount of SiC produced is 2×10−4−10−3 M⊙2\times 10^{-4} - 10^{-3}~M_{\odot}. Massive AGB/SAGB stars with Mini>3 M⊙M_{\rm ini} > 3~M_{\odot} experience HBB, that inhibits formation of carbon stars. The most relevant dust species formed in these stars are silicates and alumina dust, with grain sizes in the range 0.1μm<aol<0.15μ0.1\mu m < a_{\rm ol} < 0.15\mum and aAl2O3∼0.07μa_{\rm Al_2O_3} \sim 0.07\mum, respectively. The mass of silicates produced spans the interval 3.4×10−3 M⊙≤Mdust≤1.1×10−2 M⊙3.4\times 10^{-3}~M_{\odot} \leq M_{\rm dust} \leq 1.1\times 10^{-2}~M_{\odot} and increases with the initial mass of the star.Comment: Accepted for publication in MNRA

    Therapeutic drug monitoring to improve outcome of anti-TNF drugs in pediatric inflammatory bowel disease

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    Introduction: Medical treatment of pediatric inflammatory bowel diseases (IBD) has been greatly changed by the introduction of a number of biologic agents that are able to target various players of the immune response. In particular, monoclonal antibodies against the pro-inflammatory cytokine TNF-alpha (TNF) such as infliximab, adalimumab, and golimumab are now in the clinics both in induction and maintenance therapy, and several efforts are currently ongoing to optimize the use of these drugs in children. Areas covered: This review focuses on therapeutic drug monitoring (TDM) of anti-TNF levels and antidrug antibodies (ADAs), in IBD children. A revision of the analytical assays used for assessing anti-TNF plasma levels is also provided. Expert opinion: Although there is a consensus across studies that higher anti-TNF trough levels are associated with a better clinical outcome, and that early anti-TNF serum measurements could be predictive of long-term response, it is still not clear what the best predictive time of sampling is and what the ideal target drug plasma concentration to achieve. Indeed, there are a number of published studies, particularly in pediatric cohorts, limited by the population size analyzed and more prospective large studies are needed to examine the value of these predictive markers

    Broadband X-ray spectral analysis of the Seyfert 1 galaxy GRS 1734-292

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    We discuss the broadband X-ray spectrum of GRS 1734-292 obtained from non-simultaneous XMM-Newton and NuSTAR observations, performed in 2009 and 2014, respectively. GRS1734-292 is a Seyfert 1 galaxy, located near the Galactic plane at z=0.0214z=0.0214. The NuSTAR spectrum (3−803-80 keV) is dominated by a primary power-law continuum with Γ=1.65±0.05\Gamma=1.65 \pm 0.05 and a high-energy cutoff Ec=53−8+11E_c=53^{+11}_{-8} keV, one of the lowest measured by NuSTAR in a Seyfert galaxy. Comptonization models show a temperature of the coronal plasma of kTe=11.9−0.9+1.2kT_e=11.9^{+1.2}_{-0.9} keV and an optical depth, assuming a slab geometry, τ=2.98−0.19+0.16\tau=2.98^{+0.16}_{-0.19} or a similar temperature and τ=6.7−0.4+0.3\tau=6.7^{+0.3}_{-0.4} assuming a spherical geometry. The 2009 XMM-Newton spectrum is well described by a flatter intrinsic continuum (Γ=1.47−0.03+0.07\Gamma=1.47^{+0.07}_{-0.03}) and one absorption line due to Fe\textsc{XXV} Kα\alpha produced by a warm absorber. Both data sets show a modest iron Kα\alpha emission line at 6.46.4 keV and the associated Compton reflection, due to reprocessing from neutral circumnuclear material

    Schwannoma Of The Craniocervical Junction: Surgical Approach Of Two Cases

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    We report two cases of craniocervical junction schwannomas with a special focus on the surgical approach. The patients underwent a far-lateral approach in the sitting position that facilitated the lesion removal. This report is meant to improve the understanding of this surgical technique as well as improve awareness of its usefulness for similar cases.6103:00:00639641Baldwin, H., Christopher, G., The far lateral/combined supra- and infratentorial approach (1994) J Neurosurg, 81, pp. 60-68Oliveira, E., Rhoton A.L., Jr., Peace, D., Microsurgical anatomy of the region of the foramen magnum (1985) Surg Neurol, 24, pp. 293-352Salas, E., Sekhar, L.N., Ziyal, I.M., Caputy, A.J., Wright, D.C., Variations of the extreme-lateral craniocervical approach: Anatomical study and clinical analysis of 69 patients (1999) J Neurosurg, 90 (SPINE 2), pp. 206-219Martins, R.S., Suzuki, S.H., Sanematsu P., Jr., Plese, J.P.P., Acoustic neuroma in children without association with neurofibromatosis: Report of two cases (1999) Arq Neuropsiquiatr, 57, pp. 96-100Neto, P.M.A., Stamm, A.C., Braga, F.M., Mandibular trigeminal schwannoma: Case report (2001) Arq Neuropsiquiatr, 59, pp. 959-963Siqueira, M.G., Jennings, E., Moraes, O.J.S., Naso-ethmoid schwannoma with intracranial extension: Case report (2001) Arq Neuropsiquitr, 59, pp. 421-423Andrade, G.C., Neto, P.M.A., Braga, F.M., Thalamic intracerebral schwannoma: Case report (2002) Arq Neuropsiquiatr, 60, pp. 308-313Rhoton A.L., Jr., The far-lateral approach and its transcondylar, supracondylar, and paracondylar extensions (2000) Neurosurgery, 47, pp. 195-210Spetzler, R.F., Grahm, T.W., The far-lateral approach to file inferior clivus and the upper cervical region technical note (1990) BNI Quarterly, 6, pp. 35-38Samii, M., Klekamp, J., Carvalho, G., Surgical results for meningiomas of the craniocervical junction (1996) Neurosurgery, 39, pp. 1086-1095Al-Mefty, O., Borba, L.A.B., Aoki, N., Angtuaco, E., Pait, T.G., The transcondylar approach to extradural nonneoplastic lesions of the craniovertebral junction (1996) J Neurosurg, 84, pp. 1-6Bertalanffy, H., Seeger, W., The dorsolateral, suboccipital, transcondilar approach to the lower clivus and anterior portion of the craniocervical junction (1991) Neurosurgery, 29, pp. 815-82

    Optically bright Active Galactic Nuclei in the ROSAT-Faint Source Catalogue

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    To build a large, optically bright, X-ray selected AGN sample we have correlated the ROSAT-FSC catalogue of X-ray sources with the USNO catalogue limited to objects brighter than O=16.5 and then with the APS database. Each of the 3,212 coincidences was classified using the slitless Hamburg spectra. 493 objects were found to be extended and 2,719 starlike. Using both the extended objects and the galaxies known from published catalogues we built up a sample of 185 galaxies with O_APS < 17.0 mag, which are high-probability counterparts of RASS-FSC X-ray sources. 130 galaxies have a redshift from the literature and for another 34 we obtained new spectra. The fraction of Seyfert galaxies in this sample is 20 %. To select a corresponding sample of 144 high-probability counterparts among the starlike sources we searched for very blue objects in an APS-based color-magnitude diagram. Forty-one were already known AGN and for another 91 objects we obtained new spectra, yielding 42 new AGN, increasing their number in the sample to 83. This confirms that surveys of bright QSOs are still significantly incomplete. On the other hand we find that, at a flux limit of 0.02 count /-1 and at this magnitude, only 40 % of all QSOs are detected by ROSAT.Comment: 17 pages, 16 figures, accepted by A&
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