480 research outputs found

    Characterisation of archaeological waterlogged wood by pyrolytic and mass spectrometric techniques

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    1) Department of Chemistry and Industrial Chemistry, University of Pisa, via Risorgimento 35. 56126 Pisa, Italy ; 2) IRNAS-CSIC, Seville, Spain; E-mail address: [email protected] combination of two techniques based on analytical pyrolysis and mass spectrometry, including direct exposure-MS (DE-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), was used to study the chemical composition of waterlogged archaeological wood. In particular, the two techniques were used to chemically characterise samples of archaeological wood from the excavation of the Site of the Ancient Ships of Pisa San Rossore in Pisa (Italy). The data were compared to those of native sound wood of the same species. The results highlight that DE-MS is a valuable technique for the characterisation of archaeological wood. DE-MS allows us to use a minimal sample size and to perform the analysis in a few minutes, thus avoiding the long wet-chemical procedures that are commonly used to characterise wood. The results also confirm the importance of Py-GC/MS as a tool for shedding light on the chemical modifications of wood in archaeological objects. The analyses demonstrated that waterlogged wood from the site of Pisa San Rossore have undergone an extensive loss of polysaccharides together with partial demethylation of lignin units, both guaiacyl and syringyl monomers. In fact, catechols and methoxy catechols were identified among the pyrolysis products of the waterlogged wood samples.The authors wish to thank Dott.ssa G. Giachi (Restoration Laboratories of the Archaeological Superintendence of Tuscany, Florence, Italy) for providing archaeological wood samples and for her valuable support and collaboration. Funding was provided by the Archaeological Superintendence of Tuscany and by the Italian MIUR (PRIN Cofin05).Peer reviewe

    An 18-34-GHz dynamic frequency divider based on 0.2-μm AlGaAs/GaAs/AlGaAs quantum-well transistors

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    The design and performance of a dynamic frequency divider was presented. This digital IC demonstrates the ability of the authors' AlGaAs/GaAs/AlGaAs quantum-well FETs with gate lengths of 0.2 μm. Stable operation was achieved in the frequency range from 18 GHz up to 34 GHz with a power consumption of 250 mW. To the authors' knowledge, this is the best result ever reported for HEMT circuits, and is similar to the frequency limit achieved by use of AlGaAs/GaAs HBTs

    Synchronous bursts on scale-free neuronal networks with attractive and repulsive coupling

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    This paper investigates the dependence of synchronization transitions of bursting oscillations on the information transmission delay over scale-free neuronal networks with attractive and repulsive coupling. It is shown that for both types of coupling, the delay always plays a subtle role in either promoting or impairing synchronization. In particular, depending on the inherent oscillation period of individual neurons, regions of irregular and regular propagating excitatory fronts appear intermittently as the delay increases. These delay-induced synchronization transitions are manifested as well-expressed minima in the measure for spatiotemporal synchrony. For attractive coupling, the minima appear at every integer multiple of the average oscillation period, while for the repulsive coupling, they appear at every odd multiple of the half of the average oscillation period. The obtained results are robust to the variations of the dynamics of individual neurons, the system size, and the neuronal firing type. Hence, they can be used to characterize attractively or repulsively coupled scale-free neuronal networks with delays.Comment: 15 pages, 9 figures; accepted for publication in PLoS ONE [related work available at http://arxiv.org/abs/0907.4961 and http://www.matjazperc.com/

    16 x 16 bit parallel multiplier based on 6 K gate array with 0.3 μm AlGaAs/GaAs quantum well transistors

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    The design and performance of a 16x16 bit parallel multiplier based on a 6 K gate array will be presented. This LSI semicustom IC demonstrates the high potential of the authors' AlGaAs/GaAs quantum well FETs with a gate length of 0.3 μm. The best multiplication time measured was 7.2 ns

    The Kuramoto model in complex networks

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    181 pages, 48 figures. In Press, Accepted Manuscript, Physics Reports 2015 Acknowledgments We are indebted with B. Sonnenschein, E. R. dos Santos, P. Schultz, C. Grabow, M. Ha and C. Choi for insightful and helpful discussions. T.P. acknowledges FAPESP (No. 2012/22160-7 and No. 2015/02486-3) and IRTG 1740. P.J. thanks founding from the China Scholarship Council (CSC). F.A.R. acknowledges CNPq (Grant No. 305940/2010-4) and FAPESP (Grants No. 2011/50761-2 and No. 2013/26416-9) for financial support. J.K. would like to acknowledge IRTG 1740 (DFG and FAPESP).Peer reviewedPreprin

    Weichteilerkrankungen der Schulter und Subakromialsyndrome

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    Elbow arthroscopy in children and adolescents: analysis of outcome and complications

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    Abstract Background Chondral or osteochondral lesions, post-traumatic contracture and loose bodies of the elbow are often associated with chronic pain, stiffness, repetitive swelling and joint blockages. Therefore, arthroscopy of the elbow is often used in the elderly for the treatment of osteochondral defects or arthrolysis. There are only a few reports and studies about arthroscopic therapy of the elbow in children and adolescents. This study assesses the clinical outcome of arthroscopic therapy in this age group. Methods In a retrospective study, children and adolescents who underwent an elbow arthroscopy in the period from 2010 to 2014 were included. The children were evaluated using the validated outcome measures Mayo Elbow Performance Score (MEPS), range of motion, pain on visual analog scale (VAS), Oxford Elbow Score (OES), quick dash and postoperative satisfaction. Furthermore, all complications were analyzed. Results In total, 27 patients were included. The mean (range) age was 14 (11–17) years, with a follow-up of 45 months. Fourteen (52%) were female and thirteen children (48%) were male. Twenty children had an arthroscopy due to osteochondritis dissecans and seven children for post-traumatic pain and stiffness. The mean (standard deviation) MEPS improved from 65 (15) to 96 (8; p = .005). The OES and quick dash were 93 and 5.4. The mean extension improved from − 15° (± 13.8) to 3° (± 10.2; p < .001). The mean flexion improved from 131° (± 13.4) to 137° (± 9.5; p = .003). Average pain on VAS was postoperative .2 (± .5), and 81.5% of all children had excellent or good results. There were no complications such as damage of nerves or blood vessels observed. Conclusion Elbow arthroscopy is an appropriate and safe treatment option in children and adolescents with good and excellent postoperative results

    Complex Functional Posttraumatic Shoulder Reconstruction Using Shoulder Arthroplasty and a Pedicled Innervated Latissimus Dorsi Flap—A Case Report and Literature Review

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    Background The shoulder joint is one of the most freely movable joints in the human body and has therefore high importance for upper limb functionality. Several techniques have been developed to replace the glenohumeral joint including humeral hemiarthroplasty, anatomical total shoulder arthroplasty, and reverse total shoulder arthroplasty, depending on the underlying pathology. For the soft tissue reconstruction, the innervated latissimus dorsi musculocutaneous flap is a reliable solution flap in shoulder and arm reconstruction. Case presentation We present the case of a 16‐year‐old male patient with a complete destruction of the shoulder joint and soft tissues after ballistic trauma. We performed the reconstruction of the shoulder joint using a humeral hemiarthroplasty with a mesh fixation to the remaining glenoid. The soft tissue coverage and the restoration of the deltoid muscle function were insured with a pedicled innervated latissimus dorsi musculocutaneous flap. One year postoperatively, the patient showed a good function of the shoulder joint with an excellent aesthetical result and no pain. Conclusion The pedicled latissimus dorsi musculocutaneous flap can safely restore the shoulder function, while the humeral hemiarthroplasty with mesh fixation can be a reliable solution for the reconstruction of a completely destructed shoulder joint
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