1,323 research outputs found

    Blazar Flaring Patterns (B-FlaP): Classifying Blazar Candidates of Uncertain type in the third Fermi-LAT catalog by Artificial Neural Networks

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    The Fermi Large Area Telescope (LAT) is currently the most important facility for investigating the GeV γ\gamma-ray sky. With Fermi LAT more than three thousand γ\gamma-ray sources have been discovered so far. 1144 (40%\sim40\%) of the sources are active galaxies of the blazar class, and 573 (20%\sim20\%) are listed as Blazar Candidate of Uncertain type (BCU), or sources without a conclusive classification. We use the Empirical Cumulative Distribution Functions (ECDF) and the Artificial Neural Networks (ANN) for a fast method of screening and classification for BCUs based on data collected at γ\gamma-ray energies only, when rigorous multiwavelength analysis is not available. Based on our method, we classify 342 BCUs as BL Lacs and 154 as FSRQs, while 77 objects remain uncertain. Moreover, radio analysis and direct observations in ground-based optical observatories are used as counterparts to the statistical classifications to validate the method. This approach is of interest because of the increasing number of unclassified sources in Fermi catalogs and because blazars and in particular their subclass High Synchrotron Peak (HSP) objects are the main targets of atmospheric Cherenkov telescopes.Comment: 18 pages, 17 figures, accepted for publication on MNRA

    Optical counterparts of undetermined type γ\gamma-ray Active Galactic Nuclei with blazar-like Spectral Energy Distributions

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    During its first four years of scientific observations, the Fermi Large Area Telescope (Fermi-LAT) detected 3033 γ\gamma-ray sources above a 4σ\sigma significance level. Although most of the extra-Galactic sources are active galactic nuclei (AGN) of the blazar class, other families of AGNs are observed too, while a still high fraction of detections (30%\sim 30\%) remains with uncertain association or classification. According to the currently accepted interpretation, the AGN γ\gamma-ray emission arises from inverse Compton (IC) scattering of low energy photons by relativistic particles confined in a jet that, in the case of blazars, is oriented very close to our line of sight. Taking advantage of data from radio and X-ray wavelengths, which we expect to be produced together with γ\gamma-rays, providing a much better source localization potential, we focused our attention on a sample of γ\gamma-ray Blazar Candidates of Undetermined Type (BCUs), starting a campaign of optical spectroscopic observations. The main aims of our investigation include a census of the AGN families that contribute to γ\gamma-ray emission and a study of their redshift distribution, with the subsequent implications on the intrinsic source power. We furthermore analyze which γ\gamma-ray properties can better constrain the nature of the source, thus helping in the study of objects not yet associated with a reliable low frequency counterpart. In this communication we report on the instruments and techniques used to identify the optical counterparts of γ\gamma-ray sources, we give an overview on the status of our work, and we discuss the implications of a large scale study of γ\gamma-ray emitting AGNs.Comment: 9 pages, 2 figures, proceedings of the 10th Serbian Conference on Spectral Line Shapes in Astrophysics. JOAA, accepte

    C-NMT: A Collaborative Inference Framework for Neural Machine Translation

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    Collaborative Inference (CI) optimizes the latency and energy consumption of deep learning inference through the inter-operation of edge and cloud devices. Albeit beneficial for other tasks, CI has never been applied to the sequence-to-sequence mapping problem at the heart of Neural Machine Translation (NMT). In this work, we address the specific issues of collaborative NMT, such as estimating the latency required to generate the (unknown) output sequence, and show how existing CI methods can be adapted to these applications. Our experiments show that CI can reduce the latency of NMT by up to 44% compared to a non-collaborative approach

    Treatment of Vancouver B1 periprosthetic femoral fractures using Intrauma Iron Lady® locking plate: A retrospective study on 32 patients

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    Introduction: Periprosthetic femoral fractures (PFF) actually represent a serious public health problem. They are reported to occur in 0,1-4.5% of all patients undergoing total hip replacement (THR). PFF are commonly distinguished using the Vancouver classification. This study principal aim is to evaluate results obtained using the Intrauma Iron Lady® Conical Coupling locking plate for the treatment of Vancouver type B1 periprosthetic femoral fractures. Materials and Methods: We enrolled 32 patients affected by Vancouver B1 PFF and treated with the same device. Metal cerclages were additionally used in 12 (38%) patients. A clinical and radiographical post-operative follow-up was then planned at 1, 3 and 6 months after surgery; than the follow-up was annually fixed. Results: Mean age at the moment of trauma was 76,7 years. All involved femoral stem were uncemented and the they were all radiographically and intraoperativelly judged to be stable. Mean post-operative follow-up period was 5,8 years. 29 patients (91%) presented healed fracture at 6 months follow-up. 9% patients developed a superficial surgical site infection. Discussion and Conclusions: Literature highlights that Vancouver B1 PFF should be treated with open reduction and internal fixation (ORIF) using polyaxial locking plates. However, no single technique has gained universal acceptance to be superior that the other. The current reported healing rate ranges from 40 to 100%. Using the Intrauma Iron Lady® Conical Coupling locking plate, we obtained a healing rate of 91%; this data is consistent with recent literature. Moreover, the role of cerclages in addition to femoral plating is actually controversial because they potentially damage the soft callus vascularization. Our results showed no difference in term of healing rate between patients with and without cerclages, according with some of most recent articles. A prospective study with a higher number of patients should be carried out in order to better evaluate the role of cerclages on healing rate but also the complications frequency after PFF surgical treatment

    Multiplexed dispersive readout of superconducting phase qubits

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    We introduce a frequency-multiplexed readout scheme for superconducting phase qubits. Using a quantum circuit with four phase qubits, we couple each qubit to a separate lumped-element superconducting readout resonator, with the readout resonators connected in parallel to a single measurement line. The readout resonators and control electronics are designed so that all four qubits can be read out simultaneously using frequency multiplexing on the one measurement line. This technology provides a highly efficient and compact means for reading out multiple qubits, a significant advantage for scaling up to larger numbers of qubits.Comment: 4 pages, 4 figure

    Identification of non-canonical Wnt receptors required for Wnt-3a-induced early differentiation of human neural stem cells

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    Wnt proteins preferentially activate either β-catenin-dependent or β-cateninindependent signals, but the activity of a particular Wnt also depends on cellular context and receptor availability. We previously reported that Wnt-3a induces neural differentiation of human embryonic stem cell-derived neural stem cells (NSCs) in a β-catenin-independent manner by activating a signal involving JNK and the AP-1 family member ATF-2. Here, we report the results of a gene silencing approach to identify the Wnt receptors that mediate this response to Wnt-3a. Silencing of ROR2 increased neuronal differentiation, as measured by expression of the genes DCX, NEUROD1 and NGN1, suggesting ROR2 signals normally prevent differentiation. Silencing of the other Wnt receptors singly did not affect Wnt-3ainduced neuronal differentiation. However, pair-wise silencing of ROR1 and FZD4 or FZD5 and of LRP6 and FZD4 or FZD5 inhibited neuronal differentiation, as detected by reductions in the expression of neuronal genes and immunocytochemical detection of DCX and NEUROD1 and DCX. Ectopic expression of these receptors in HEK 293 cells increased ATF2-dependent transcription. In addition, ROR1 co-immunoprecipitated with FZD4 and LRP6 in transfected HEK 293 cells and colocalized with FZD4 and with LRP6 at the cell surface of transfected L cells. Wnt-3a did not appear to affect these interactions but did alter the interactions between LRP6 and FZD4/5. Together, these observations highlight roles for ROR1, LRP6, FZD4 and FZD5 in neural stem cell differentiation and provide support for a model in which dynamic interactions among these receptors mediate Wnt-3a activation of ATF2 signaling
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