6,596 research outputs found

    Investigating Supergiant Fast X-ray Transients with LOFT

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    Supergiant Fast X-ray Transients (SFXT) are a class of High-Mass X-ray Binaries whose optical counterparts are O or B supergiant stars, and whose X-ray outbursts are ~ 4 orders of magnitude brighter than the quiescent state. LOFT, the Large Observatory For X-ray Timing, with its coded mask Wide Field Monitor (WFM) and its 10 m^2 class collimated X-ray Large Area Detector (LAD), will be able to dramatically deepen the knowledge of this class of sources. It will provide simultaneous high S/N broad-band and time-resolved spectroscopy in several intensity states, and long term monitoring that will yield new determinations of orbital periods, as well as spin periods. We show the results of an extensive set of simulations performed using previous observational results of these sources obtained with Swift and XMM-Newton. The WFM will detect all SFXT flares within its field of view down to a 15-20 mCrab in 5ks. Our simulations describe the outbursts at several intensities (F_(2-10keV)=5.9x10^-9 to 5.5x10^-10 erg cm^-2 s^-1), the intermediate and most common state (10^-11 erg cm^-2 s^-1), and the low state (1.2x10^-12 to 5x10^-13 erg cm^-2 s^-1). We also considered large variations of N_H and the presence of emission lines, as observed by Swift and XMM-Newton.Comment: Proceedings of the 5th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2012), Heidelberg. 4 pages, 3 figures, 1 tabl

    Benign nocturnal alternating hemiplegia of childhood: a new case with unusual findings

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    It has been described a neuro developmental disorder labelled “Benign nocturnal alternating hemiplegia of childhood” (BNAHC) characterized by recurrent attacks of nocturnal hemiplegia without progression to neurological or intellectual impairment. We report a female patient who at 11 months revealed a motionless left arm, unusual crying without impairment of consciousness and obvious precipitating factors. The attacks occur during sleep in the early morning with lack of ictal and interictal electroencephalographic abnormalities, progressive neurological deficit, and cognitive impairment. Unlike previous reports of BNAHC our patient come from a family with a history of both migraine, hemiplegic migraine, and sleep disorders. Our study remarks on the typical features described in previous studies and stresses the uncommon aspects that could help to identify the disorder which is likely to have been underestimated. Despite some clinical similarities between BNAHC and familiar hemiplegic migraine and alternating hemiplegia of childhood, the genetic analyses of our patient did not reveal genetic mutations found in both disorders

    Augmented reality for dental implantology: a pilot clinical report of two cases

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    Background: Despite the limited number of articles dedicated to its use, augmented reality (AR) is an emerging technology that has shown to have increasing applications in multiple different medical sectors. These include, but are not limited to, the Maxillo-facial and Dentistry disciplines of medicine. In these medical specialties, the focus of AR technology is to achieve a more visible surgical field during an operation. Currently, this goal is brought about by an accurate display of either static or dynamic diagnostic images via the use of a visor or specific glasses. The objective of this study is to evaluate the feasibility of using a virtual display for dynamic navigation via AR. The secondary outcome is to evaluate if the use of this technology could affect the accuracy of dynamic navigation. Case presentation: Two patients, both needing implant rehabilitation in the upper premolar area, were treated with flapless surgery. Prior to the procedure itself, the position of the implant was virtually planned and placed for each of the patients using their previous scans. This placement preparation contributed to a dynamic navigation system that was displayed on AR glasses. This, in turn, allowed for the use of a computer-aided/image-guided procedure to occur. Dedicated software for surface superimposition was then used to match the planned position of the implant and the real one obtained from the postoperative scan. Accuracies, using this procedure were evaluated by way of measuring the deviation between real and planned positions of the implants. For both surgeries it was possible to proceed using the AR technology as planned. The deviations for the first implant were 0.53\u2009mm at the entry point and 0.50\u2009mm at the apical point and for the second implant were 0.46\u2009mm at the entry point and 0.48\u2009mm at the apical point. The angular deviations were respectively 3.05\ub0 and 2.19\ub0. Conclusions: From the results of this pilot study, it seems that AR can be useful in dental implantology for displaying dynamic navigation systems. While this technology did not seem to noticeably affect the accuracy of the procedure, specific software applications should further optimize the results

    On the B and J/Psi Cross Section Measurements at Ua1 and CDF

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    We analise the implications of the measurement of BB and J/ψJ/\psi inclusive \pt\ distributions performed in ppˉp\bar p collisions by the UA1 and CDF experiments.Comment: 16 pages + 8 topdrawer figs included at the end, Latex, IFUP-TH 2/9

    Generalized Gluon Currents and Applications in QCD

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    We consider the process containing two quark lines and an arbitrary number of gluons in a spinor helicity framework. A current with two off-shell gluons appears in the amplitude. We first study this modified gluon current using recursion relations. The recursion relation for the modified gluon current is solved for the case of like-helicity gluons. We apply the modified gluon current to compute the amplitude for qqˉ→qqˉgg⋯gq \bar q \rightarrow q \bar q gg \cdots g in the like-helicity gluon case.Comment: 80 pages, 2 figures (appended in pictex), CLNS 91/112

    Inflaton Potential Reconstruction and Generalized Equations of State

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    We extend a previous analysis concerning cosmological fluids with generalized equations of state in order to study inflationary scenarios. In the framework of the slow-roll approximation we find the expressions for the perturbation parameters ϔ\epsilon, η\eta and the density perturbation spectra in terms of the adiabatic index \ga as a function of the universe scale factor. This connection allows to find straightforwardly \ga corresponding, for example, to the simplest {\it chaotic} model and to the Harrison-Zeldovich potential and shows its capability to be applied to more complicate situations. Finally, we use this description to develop a new approach to the early universe dynamics, based on a 1/N1/N expansion, where NN is the e-fold number. To this aim, we introduce a set of suitable dimensionless variables and show that at the zero-th order in 1/N1/N, an improved slow-roll approximation is obtained.Comment: 15 pages, plain Latex, to appear in Mod. Phys. Lett.

    Religious tourism and seduction: the case of Sacred Mount of Varallo

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    Since 2003 the Sacred Mount of Varallo is included in the World Heritage List of UNESCO because it represents a successful integration of architecture and fine art into a landscape of great beauty for spiritual reasons. As the other Sacred Mounts of Piemonte and Lombardia (Italy), it represents a place in witch all visitors (tourist or pilgrims) couldn\u2019t resist the attraction of and environment full of spiritual and natural seduction. According to these characteristics, the paper aims to define who visits the Sacred Mount of Varallo and which experiences he/she is looking for. In this way we try to understand how a classical religious tourism destination could seduce the third millennium tourist. The research methodology is based both on official statistical data, and on a questionnaire delivered to visitors
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