2,278 research outputs found

    A consistent interpretation of the Karmen anomaly

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    The Karmen anomaly can be interpreted as being due to a heavy neutrino of mass around 137 MeV produced in πe2\pi_{e 2} decays. This interpretation is consistent with the present limits on the couplings of such an object.Comment: 11pages, 4figures, Te

    Styrene-terminated polysulfone oligomers as matrix material for graphite reinforced composites: An initial study

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    Styrene terminated polysulfone oligomers are part of an oligomeric class of compounds with end groups capable of thermal polymerization. These materials can be used as matrices for graphite reinforced composites. The initial evaluation of styrene terminated polysulfone oligomer based composites are summarized in terms of fabrication methods, and mechanical and environmental properties. In addition, a description and evaluation is provided of the NASA/Industry Fellowship Program for Technology Transfer

    A revision of the genus Bougainvillia (Anthomedusae)

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    Os autores fizeram uma revisão do gênero Bougainvillia, incluindo todas as espécies descritas sob esse nome e todas aquelas realmente pertencentes a esse gênero, anteriormente descritas sob outros nomes. De cada espécie é dada uma lista de sinônimos a mais completa possível, assim como uma descrição detalhada. As espécies válidas são reunidas numa tabela sinótica com os dados que foi possível reunir para cada espécie. Estabelecida a sinonímia na base dos caracteres morfológicos, foi estudada a zoogeografia do gênero. Tudo indica ser B. ramosa a forma simples primitiva da qual derivaram as demais espécies. Desta forma, ou de outra próxima a ela, teria derivado um grupo de espécies de águas temperadas com certas características morfológicas comuns a todas, e, afora uma que é do Japão, habitantes do Atlântico ou mares adjacentes. Um segundo grupo de espécies teria evoluído em águas frias árticas ou boreais e antárticas, também com caracteres morfológicos em comum. Por fim, um terceiro grupo de espécies teria evoluído em águas tropicais tanto do Atlântico como do Pacífico, apresentando, igualmente, características morfológicas em comum. Considerando o número de espécies e sua distribuição, o gênero Bougainvilia aparece como um gênero inicialmente atlântico, havendo apenas duas espécies distribuídas exclusivamente no Pacífico ou Indo-Pacífico

    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

    Diagnosis and endovascular treatment of an internal mammary artery injury

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    Internal mammary artery (IMA) disruption after blunt chest trauma is rare. In some instances, it may occur after mild chest trauma with minor external physical findings. However, prompt diagnosis and treatment are necessary, as it can be associated with vascular and parenchymal injuries. We report a case of blunt chest trauma resulting in a sternal fracture associated with an IMA injury, active anterior mediastinal bleeding, bilateral lung contusions, and a left hemothorax. It was successfully treated by selective embolization to the left IMA branch and chest tube placement

    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

    Modified double lumen tube for a unique bronchial and carinal resection in a patient undergoing uniportal VATS for tumour: A case report

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    For bronchial sleeve and carinal resection and reconstruction during uniportal video-assisted thoracic surgery (VATS), ventilation technique remains a demanding challenge for the anesthesiologists. The ventilation techniques require maintaining adequate gas exchange while providing a good surgical exposure. The case we present was a 58-year-old female with carcinoma in the right upper lobe involving the right main bronchus and the lower trachea. Right upper sleeve lobectomy, carinal resection and reconstruction was performed under uniportal VATS. A modified double-lumen tube (DLT) was inserted to achieve one-lung ventilation, and high-frequency jet ventilation (HFJV) was passed through the DLT to provide oxygenation during the anastomosis without interfering with the surgical procedure. The whole procedure was uneventful. We suggest that the double lumen tube could be modified being a simple and safe option for one-lung ventilation in carinal resection and reconstruction under uniportal VATS
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