2,336 research outputs found

    A Compact MultiBand and Dual-Polarized Mobile Base-Station Antenna Using Optimal Array Structure

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    This paper introduces a multiband base-station antenna to provide multiple communications services. There is growing need for multiband base-station antennas for mobile communications to serve existing 2nd and 3rd generation systems and to provide emerging 4th generation communication service as well as WiFi. For example, cellular, PCS, and especially WCDMA service are currently widely used in Korea, and 4th generation service (WiBro and LTE), introduced in 2011, will have to operate in parallel with existing services. The proposed multiband base-station antenna can provide a single/dual/triple or more multiple services using dual-polarization (±45° linear polarizations) according to the requirements of the service provider. This antenna has a shared aperture, having several array antenna sets for multiple services (Band 1: cellular service in 0.824~0.894 GHz, Band 2: PCS, WCDMA, and WiFi in 1.920~2.170 GHz, Band 3: WiBro and WiMAX in 2.300~2.400 GHz, and Band 4: WiMAX in 5.150~5.850 GHz). This antenna can be helpful for reducing base-station operating expenses and to create a clean urban landscape by minimizing the number of base-station antennas, which are increasing rapidly

    Intra-abdominal angiosarcoma developing in a capsule of a foreign body: report of a case with associated hemorrhagic diathesis

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    BACKGROUNDS: Angiosarcoma occurs very rarely in the gastrointestinal tract and can present great diagnostic difficulty, especially when it is associated with intraabdominal abscess or granulation tissue. CASE PRESENTATION: We report a case where the angiosarcoma was diagnosed after the occurrence of disseminated angiosarcoma and concurrent hemoperitoneum. The tumor developed in the fibrous capsule of a foreign body, which was possibly related to the previous appendectomy twenty years ago, and became a widely disseminated malignant neoplasm in the abdomen. After the operation, the patient's course was dominated by a fatal consumptive coagulapathy. Pathologic examination of the multiple intra-abdominal lesions showed the histological and immunohistological characteristics of the angiosarcoma. CONCLUSION: Even though angiosarcoma in the gastrointestinal tract is extremely rare, when dealing with intraabdominal abscess or the gastrointestinal bleeding in patients who have undergone surgery or radiation therapy in the past, the possibility of angiosarcoma should be considered. To make the definite diagnosis of angiosarcoma and to avoid the misdiagnosis of foreign body granuloma, thorough histological examination and immunohistochemical staining may be prerequisite

    Effect of Magnolol on the Function of Osteoblastic MC3T3-E1 Cells

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    Objectives. In the present study, the ability of magnolol, a hydroxylated biphenyl compound isolated from Magnolia officinalis, to stimulate osteoblast function and inhibit the release of bone-resorbing mediators was investigated in osteoblastic MC3T3-E1 cells. Methods. Osteoblast function was measured by cell growth, alkaline phosphatase activity, collagen synthesis, and mineralization. Glutathione content was also measured in the cells. Bone-resorbing cytokines, receptor activator of nuclear factor-κB ligand (RANKL), TNF-α, and IL-6 were measured with an enzyme immunoassay system. Results. Magnolol caused a significant elevation of cell growth, alkaline phosphatase activity, collagen synthesis, mineralization, and glutathione content in the cells (P < 0.05). Skeletal turnover is orchestrated by a complex network of regulatory factors. Among cytokines, RANKL, TNF-α, and IL-6 were found to be key osteoclastogenetic molecules produced by osteoblasts. Magnolol significantly (P < 0.05) decreased the production of osteoclast differentiation inducing factors such as RANKL, TNF-α, and IL-6 in the presence of antimycin A, which inhibits mitochondrial electron transport and has been used as an ROS generator. Conclusion. Magnolol might be a candidate as an agent for the prevention of bone disorders such as osteoporosis

    Influence of Mg Deficiency on the Superconductivity in MgB2 Thin Films Grown by using HPCVD

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    The effects of Mg deficiency in MgB2 films grown by using hybrid physical-chemical vapor deposition were investigated after vacuum annealing at various temperatures. High-quality MgB2 films grown on c-cut Al2O3 substrates with different superconducting transition temperatures (Tc) of 40.2 and 41 K were used in this study. As the annealing temperature was increased from 200 to 800 C, the Mg contents in the MgB2 films systemically decreased, but the Tc's did not change, within 0.12 K, until the annealing temperature reached 700 C. For MgB2 films annealed at 800 C for 30 min, however, no superconductivity was observed, and the temperature dependence of the resistivity showed a semiconducting behavior. We also found that the residual resistivity ratio decreased with increasing annealing temperature.Comment: 7 pages including 4 figure

    Stratifying the early radiologic trajectory in dyspneic patients with COVID-19 pneumonia

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    OBJECTIVE: This study aimed to stratify the early pneumonia trajectory on chest radiographs and compare patient characteristics in dyspneic patients with coronavirus disease 2019 (COVID-19). MATERIALS AND METHODS: We retrospectively included 139 COVID-19 patients with dyspnea (87 men, 62.7+/-16.3 years) and serial chest radiographs from January to September 2020. Radiographic pneumonia extent was quantified as a percentage using a previously-developed deep learning algorithm. A group-based trajectory model was used to categorize the pneumonia trajectory after symptom onset during hospitalization. Clinical findings, and outcomes were compared, and Cox regression was performed for survival analysis. RESULTS: Radiographic pneumonia trajectories were categorized into four groups. Group 1 (n = 83, 59.7%) had negligible pneumonia, and group 2 (n = 29, 20.9%) had mild pneumonia. Group 3 (n = 13, 9.4%) and group 4 (n = 14, 10.1%) showed similar considerable pneumonia extents at baseline, but group 3 had decreasing pneumonia extent at 1-2 weeks, while group 4 had increasing pneumonia extent. Intensive care unit admission and mortality were significantly more frequent in groups 3 and 4 than in groups 1 and 2 (P \u3c .05). Groups 3 and 4 shared similar clinical and laboratory findings, but thrombocytopenia ( \u3c 150x103/muL) was exclusively observed in group 4 (P = .016). When compared to groups 1 and 2, group 4 (hazard ratio, 63.3; 95% confidence interval, 7.9-504.9) had a two-fold higher risk for mortality than group 3 (hazard ratio, 31.2; 95% confidence interval, 3.5-280.2), and this elevated risk was maintained after adjusting confounders. CONCLUSION: Monitoring the early radiologic trajectory beyond baseline further prognosticated at-risk COVID-19 patients, who potentially had thrombo-inflammatory responses

    Laparoscopic resection of a appendiceal mucocele

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    Laparoscopic resection of appendiceal mucoceles has recently been described, but the safety and efficacy are controversial. We present two cases of laparoscopic mucocelectomies involving 14 and 15 cm cystic masses originating from the appendix. The laparoscopic mucocelectomies were performed using four ports. From the beginning of the procedure, a laparoscopic bag was used to safely contain the mucocele, prevent rupture of the mucocele, and retract the mucocele. An endoscopic stapling device was used to transect the base of the cecum. Minimal handling was achieved by gravity and with the use of laparoscopic instruments. Laparoscopic appendectomies are widely performed for acute appendicitis, but laparoscopic resection is not routinely performed for an appendiceal mucocele because of the risk of perforation and subsequent pseudomyxoma peritonei. We report two cases of laparoscopic appendiceal mucocelectomies, which were performed safely with laparoscopic instruments and minimal manipulation
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