6,109 research outputs found

    LEIR lattice

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    The Low Energy Ion Ring (LEIR) is a low energy ion cooling and accumulation ring and serves to compress long ion pulses from Linac3 into high density bunches suitable for LHC ion operation. Issues of the LEIR lattice are to fulfil all constraints with a small number of quadrupoles and compensations of perturbations due to an electron cooler and gradients seen by the beam in the bending magnets during the ramp. Furthermore, experimental investigations via orbit response measurements will be reported

    Tuning Monte Carlo Generators: The Perugia Tunes

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    We present 9 new tunes of the pT-ordered shower and underlying-event model in PYTHIA 6.4. These "Perugia" tunes update and supersede the older "S0" family. The data sets used to constrain the models include hadronic Z0 decays at LEP, Tevatron minimum-bias data at 630, 1800, and 1960 GeV, Tevatron Drell-Yan data at 1800 and 1960 GeV, and SPS min-bias data at 200, 546, and 900 GeV. In addition to the central parameter set, called "Perugia 0", we introduce a set of 8 related "Perugia Variations" that attempt to systematically explore soft, hard, parton density, and colour structure variations in the theoretical parameters. Based on these variations, a best-guess prediction of the charged track multiplicity in inelastic, nondiffractive minimum-bias events at the LHC is made. Note that these tunes can only be used with PYTHIA 6, not with PYTHIA 8. Note: this report was updated in March 2011 with a new set of variations, collectively labeled "Perugia 2011", that are optimized for matching applications and which also take into account some lessons from the early LHC data. In order not to break the original text, these are described separately in Appendix B. Note 2: a subsequent "Perugia 2012" update is described in Appendix C.Comment: 46 page

    Blind quality assessment system for multimedia communications using tracing watermarking

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    Technical Note: Regularization performances with the error consistency method in the case of retrieved atmospheric profiles

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    International audienceThe retrieval of concentration vertical profiles of atmospheric constituents from spectroscopic measurements is often an ill-conditioned problem and regularization methods are frequently used to improve its stability. Recently a new method, that provides a good compromise between precision and vertical resolution, was proposed to determine analytically the value of the regularization parameter. This method is applied for the first time to real measurements with its implementation in the operational retrieval code of the satellite limb-emission measurements of the MIPAS instrument and its performances are quantitatively analyzed. The adopted regularization improves the stability of the retrieval providing smooth profiles without major degradation of the vertical resolution. In the analyzed measurements the retrieval procedure provides a vertical resolution that, in the troposphere and low stratosphere, is smaller than the vertical field of view of the instrument

    Epiluminescence microscopy: Criteria of cutaneous melanoma progression

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    Background: Cutaneous melanoma develops through a series of evolutionary steps (intraepidermal, radial, and vertical growth phases) that are traceable in specific histologic features. Epiluminescence microscopy (ELM) is an in vivo technique that enables the visualization of morphologic structures in pigmented lesions correlated with specific histologic architectural characteristics. Many ELM criteria associated with cutaneous melanoma have been described, but their correlation with tumor progression has not yet been established. Objective: In this preliminary study our purpose was to explore the possibility of recognizing ELM criteria that allow the in vivo detection of the various phases of melanoma progression as well as tumor depth. Methods: Seventy-two cutaneous melanomas (41 'thin' melanomas [TnM], 0.75 mm thickness) were investigated with ELM for the presence of nine standard ELM criteria; their significance was determined by calculating the chi-square test of independence. Results: A significant association is found between the presence of pigment network and TaM and between the presence of gray-blue areas, vascular pattern, and TkM. Moreover, pigment network plus radial streaming is the most significant association of ELM criteria in TnM, whereas gray-blue areas plus vascular pattern is the greatest in TkM. Conclusion: This study shows a good correlation between certain ELM criteria and the histologic architecture of cutaneous melanoma for a preoperative evaluation of the tumor thickness. Further investigation is needed for verifying on a larger number of cases our pilot estimates of sensitivity and specificity of ELM criteria in thin and thick melanomas

    Clinical and dermatoscopic criteria for the preoperative evaluation of cutaneous melanoma thickness

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    Background: Melanoma thickness measured according to the Breslow method is used to determine surgical margin and in patient selection for sentinel node biopsy. Previous studies did not confirm the reliability of melanoma palpability for clinical prediction of tumor thickness. Recently we reported the usefulness of epiluminescence microscopy (dermatoscopy) for in vivo detection of the phases of melanoma progression, as well as tumor depth. Objective: Our purpose was to determine whether the combination of clinical and dermatoscopic criteria could increase the accuracy in preoperative evaluation of melanoma thickness with respect to the clinical elevation and dermatoscopic assessments considered separately. Methods: In a blind retrospective study, 122 cutaneous melanomas were studied to evaluate the presence of several clinical and dermatoscopic criteria and their relation with the histologic thickness. An algorithm of combined criteria was constructed and statistically assessed. Results: Combinations of palpability, diameter of more than 15 mm, pigment network, gray-blue areas, and atypical vascular pattern allowed correct prediction of thickness in 89% of melanomas when categorized in two groups of less than 0.76 mm and more than 0.75 mm thickness, compared with 75% using palpability, and 80% using dermatoscopic criteria. Lower values were obtained in the further subdivision of melanomas into groups of 0.76 to 1.5 mm and more than 1.5 mm thickness. Conclusion: The combination of clinical and dermatoscopic criteria is a more precise guide for the preoperative evaluation of melanoma thickness than either is alone. However, further studies are needed to verify its applicability in establishing the surgical approach to cutaneous melanoma

    Reliability and inter-observer agreement of dermoscopic diagnosis of melanoma and melanocytic naevi

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    The aim of this study was to analyse the reliability and the inter- observer agreement of dermoscopy in the diagnosis of melanocytic skin lesions. Nine dermatologists, with a different training experience and who routinely used dermoscopy in different hospitals in Italy, evaluated clinical and dermoscopy photographs of 15 melanocytic lesions (four invasive melanomas, four histologically common naevi, and seven naevi with histological atypia). A further series of dermoscopic photographs of 40 melanocytic lesions was evaluated to quantify inter-observer concordance in recognizing dermoscopic criteria. Compared to the true (histological) diagnosis, clinical diagnosis (categories: melanoma, common naevus, atypical naevus) was correct in 40% of cases (range, 27-53%). The percentage raised to 55% (40-73%) by the use of dermoscopy, with an average improvement of 15.6%. Concerning melanoma, clinical diagnosis resulted in a sensitivity of 41.9%, specificity of 77.8%, positive predictive value (PPV) of 36.1%, negative predictive value (NPV) of 81.8%. By using dermoscopy, an improvement of diagnostic performance was found (sensitivity 75%, specificity 88.8%, VPP 71.0%, VPN 90.7%). The inter-observer agreement in melanoma diagnosis, by using dermoscopy, was similar to that obtained by clinical examination (k statistics = 0.54 and 0.52, respectively). Concerning dermoscopic criteria, the best agreement among observers was found for pseudopods, a dermoscopic parameter related to the radial growth phase of melanoma. We conclude that dermoscopy is an useful tool for a non-invasive diagnosis of melanocytic skin lesions, improving the diagnostic performance compared to clinical examination
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