2,290 research outputs found

    Autoclavable addition polyimides for 371 C composite applications

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    Studies were conducted to improve the thermo-oxidative stability (TOS) of PMR type polyimides by the substitution of para-aminostyrene (PAS) for the nadic ester endcap in second generation PMR polyimides (PMR-2). The nadic endcap which provides the PMR polyimides with their relative ease of fabrication, both by limiting the molecular weight of the prepolymer and by undergoing the final addition cure without volatiles, is also the weak link with regard to TOS. A polyimide formulated with PAS endcaps, called V-CAP, utilizes a two step reaction sequence similar to that of the PMR polyimides and can be easily autoclave molded into low void composite materials. Resin studies included two formulations of both PMR-2 and V-CAP, corresponding to n=9 and n=14 prepolymer stoichiometry. Unidirectional reinforced T40R graphite fiber laminates were fabricated from each of the resins was post-cured in either air at 385 C or nitrogen at 400 C. Composite specimens were aged in air at 371 C and mechanical properties were measured at 371 C before and after exposure

    Mediastinitis and sternal prosthesis infection successfully treated by minimally invasive omental flap transposition

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    Purulent mediastinitis is a possible serious complication after mediastinal surgery. We report the case of a localized sternal plasmocytoma treated by sternectomy and prosthetic repair, who needed a second surgery for a fistulizing mediastinitis. Five months earlier, in another Hospital, the patient underwent sternal resection and reconstruction with a “sandwich” prosthesis (Methyl-methacrylate and Marlex mesh). Suppurative mediastinitis occurred and septic shock resolution was observed after the spontaneous opening of a mediastinal cutaneous fistula. After referring to our Unit the patient underwent extensive local and systemic preparation and nutritional support; the infected prosthesis was then removed and the gap filled by a laparoscopically-prepared omental flap. Adequate preoperative management, removal of any infected material and minimally invasive omental flap transposition allowed the successful treatment of this life-threatening condition

    Production of Electron Neutrinos at Nuclear Power Reactors and the Prospects for Neutrino Physics

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    High flux of electron neutrinos(\nue) is produced at nuclear power reactors through the decays of nuclei activated by neutron capture. Realistic simulation studies on the neutron transport and capture at the reactor core were performed. The production of \chr51 and \fe55 give rise to mono-energetic \nue's at Q-values of 753 keV and 231 keV and fluxes of 8.3×1048.3 \times 10^{-4} and 3.0×1043.0 \times 10^{-4} \nue/fission, respectively. Using data from a germanium detector at the Kuo-Sheng Power Plant, we derived direct limits on the \nue magnetic moment and the radiative lifetime of \mu_{\nu} < 1.3 \times 10^{-8} ~ \mub and τν/mν>0.11s/eV\rm{\tau_{\nu} / m_{\nu} > 0.11 s / eV} at 90% confidence level (CL), respectively. Indirect bounds on τν/mν3\rm{\tau_{\nu} / m_{\nu}^3} were also inferred. The \nue-flux can be enhanced by loading selected isotopes to the reactor core, and the potential applications and achievable statistical accuracies were examined. These include accurate cross-section measurements, studies of mixing angle θ13\theta_{13} and monitoring of plutonium production.Comment: 5 pages, 3 figures, 7 table

    Dynamic titanium prosthesis based on 3D-printed replica for chest wall resection and reconstruction

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    3D-printing technologies can assist the surgical planning and prosthesis engineering for the management of extended chest wall resection. Different types of prosthesis have been utilized over time, but some concerns remain about their impact on the respiratory function. Here we present a new kind of 3D-printed titanium prosthesis designed to be either strong and flexible. The prosthesis was created on a 1:1 3D-printed anatomic replica of the chest, used to delineate surgical margins and to define the reconstructive requirements

    Stage-related outcome for thymic epithelial tumours

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    Background: Thymic epithelial tumours (TETs) are characterized by a wide variety of biological behaviors. Radical resection and stage are strong prognostic factors. Aim of this study is to review our Single Center Experience. Methods: One hundred and seventy-seven patients observed in the period from January 2000 to December 2016 were included in the study. Data regarding clinicopathologic features, treatment, and survival were collected. Stage-related clinical standpoints and therapeutic options were also evaluated. Results: Non-surgical treatment was primarily performed in 15 (8.47%), unresectable disease was intraoperatively found in 12 cases (7.4%). The analysis of 150 patients undergoing curative surgery revealed 70 stage I TET (46.66%), 49 stage II (32.66%), 19 stage III (12.66%), 6 stage IVa (4%) and 6 stage IVb (4%) at the first hospital admission. Histology identified 12 A thymoma (8%), 38 AB (25.33%), 24 B1 (16%), 50 B2 (33.33%), 19 B3 (12.66%) and 7 carcinomas (4.66%). The mean follow up time was 84.14 months (sd = 61.68 months). Disease relapse occurred in 13 patients (8.78%) at a mean period of 78.85 months (sd = 60.87 months) after surgery. Exitus due to thymoma happened in 6 cases (4.05%) after a mean survival of 56.02 months (sd = 25.17 months). The 5-year overall survival rate was 0.94 (95%CI 0.88-0.97) and the 5-year disease-free survival rate was 0.90 (95%CI 0.83-0.94). The 5-year overall survival rates were 96.1% (95% CI, 89.9-98.5%) for the early stages and 87.4% (95% CI, 65.6-95.8%) for the advanced stages (p = 0.670). The 5-year disease-free survival rates resulted being 98.8% (95% CI, 92.3-99.8%) for the early stages and 59.8% (95% CI, 37.8-76.2%) for the advanced stages (p &lt; 0.001). Conclusions: Advanced stage TETs are characterized by higher mortality and recurrence rates. Although technically demanding, surgery, as part of multimodality therapy, could prolong survival. Iterative surgical treatment of recurrences is a viable option for selected patients. Trial registration: The study was approved by the Institutional Review Board of Perugia and Terni University Hospitals [Code T1003] and was retrospectively registered

    The Category of Node-and-Choice Forms, with Subcategories for Choice-Sequence Forms and Choice-Set Forms

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    The literature specifies extensive-form games in many styles, and eventually I hope to formally translate games across those styles. Toward that end, this paper defines NCF\mathbf{NCF}, the category of node-and-choice forms. The category's objects are extensive forms in essentially any style, and the category's isomorphisms are made to accord with the literature's small handful of ad hoc style equivalences. Further, this paper develops two full subcategories: CsqF\mathbf{CsqF} for forms whose nodes are choice-sequences, and CsetF\mathbf{CsetF} for forms whose nodes are choice-sets. I show that NCF\mathbf{NCF} is "isomorphically enclosed" in CsqF\mathbf{CsqF} in the sense that each NCF\mathbf{NCF} form is isomorphic to a CsqF\mathbf{CsqF} form. Similarly, I show that CsqFa~\mathbf{CsqF_{\tilde a}} is isomorphically enclosed in CsetF\mathbf{CsetF} in the sense that each CsqF\mathbf{CsqF} form with no-absentmindedness is isomorphic to a CsetF\mathbf{CsetF} form. The converses are found to be almost immediate, and the resulting equivalences unify and simplify two ad hoc style equivalences in Kline and Luckraz 2016 and Streufert 2019. Aside from the larger agenda, this paper already makes three practical contributions. Style equivalences are made easier to derive by [1] a natural concept of isomorphic invariance and [2] the composability of isomorphic enclosures. In addition, [3] some new consequences of equivalence are systematically deduced.Comment: 43 pages, 9 figure

    Deep venous thrombosis and abortion: an unusual clinical manifestation of severe form of pectus excavatum

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    Pectus excavatum is a chest wall malformation with a strong psychological and aesthetic impact. Rarely, pectus excavatum patients can show respiratory or cardiac symptoms occurring mainly during physical exertion. We report a case of a 34-year-old pregnant woman with a severe degree of pectus excavatum who developed serious cardiovascular disease resulting in spontaneous twin abortion at the twenty-first week of gestation. Cardiovascular disease was resolved after open surgical correction of pectus excavatum. This case shows how a tardive diagnosis and a delayed surgical approach for pectus excavatum can lead to severe consequences

    Renaissance of the ~1 TeV Fixed-Target Program

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    This document describes the physics potential of a new fixed-target program based on a ~1 TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.Comment: 31 pages, 11 figure

    New Constraints on Dispersive Form Factor Parameterizations from the Timelike Region

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    We generalize a recent model-independent form factor parameterization derived from rigorous dispersion relations to include constraints from data in the timelike region. These constraints dictate the convergence properties of the parameterization and appear as sum rules on the parameters. We further develop a new parameterization that takes into account finiteness and asymptotic conditions on the form factor, and use it to fit to the elastic \pi electromagnetic form factor. We find that the existing world sample of timelike data gives only loose bounds on the form factor in the spacelike region, but explain how the acquisition of additional timelike data or fits to other form factors are expected to give much better results. The same parameterization is seen to fit spacelike data extremely well.Comment: 24 pages, latex (revtex), 3 eps figure
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