846 research outputs found

    Site-selective silicon adatom desorption using femtosecond laser pulse pairs and scanning tunneling microscopy

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    We performed an experimental study of silicon adatom desorption from the Si~111!-737 surfaceusing femtosecond laser pulse pair excitation with 80 fs pulse duration, 800 nm center wavelength,300 mW average power, and a 100 MHz repetition rate. Using scanning tunneling microscopy, wedirectly recorded the desorption characteristics at each delay setting for each of the four adatombinding sites. The study revealed a preferential dependence between the delay time and the adatomsites within a 66.6–1000 fs delay range

    Experimental and observational studies on alcohol use and dietary intake: a systematic review

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153599/1/obr12950_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153599/2/obr12950.pd

    Integrated engineering environments for large complex products

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    An introduction is given to the Engineering Design Centre at the University of Newcastle upon Tyne, along with a brief explanation of the main focus towards large made-to-order products. Three key areas of research at the Centre, which have evolved as a result of collaboration with industrial partners from various sectors of industry, are identified as (1) decision support and optimisation, (2) design for lifecycle, and (3) design integration and co-ordination. A summary of the unique features of large made-to-order products is then presented, which includes the need for integration and co-ordination technologies. Thus, an overview of the existing integration and co-ordination technologies is presented followed by a brief explanation of research in these areas at the Engineering Design Centre. A more detailed description is then presented regarding the co-ordination aspect of research being conducted at the Engineering Design Centre, in collaboration with the CAD Centre at the University of Strathclyde. Concurrent Engineering is acknowledged as a strategy for improving the design process, however design coordination is viewed as a principal requirement for its successful implementation. That is, design co-ordination is proposed as being the key to a mechanism that is able to maximise and realise any potential opportunity of concurrency. Thus, an agentoriented approach to co-ordination is presented, which incorporates various types of agents responsible for managing their respective activities. The co-ordinated approach, which is implemented within the Design Co-ordination System, includes features such as resource management and monitoring, dynamic scheduling, activity direction, task enactment, and information management. An application of the Design Co-ordination System, in conjunction with a robust concept exploration tool, shows that the computational design analysis involved in evaluating many design concepts can be performed more efficiently through a co-ordinated approach

    Regeneration of Graft Livers and Limited Contribution of Extrahepatic Cells After Partial Liver Transplantation in Humans

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    Background Liver regeneration is still not fully understood. Partial liver transplantation (LT) can provide the opportunity to investigate the mechanisms of liver regeneration, including the contribution of extrahepatic cells to liver regeneration. Methods Of 61 patients transplanted with partial liver graft between August 1997 and October 2006, 56 patients were studied, including 49 adults and 7 children. Sequential computed tomography volumetric analysis was performed for volume measurement, while proliferating cell nuclear antigen (PCNA) labeling index was investigated for liver cell proliferation in nonprotocol liver biopsy specimens. In addition, 15 male recipients who had female liver grafts were investigated in order to detect Y chromosomes as extrahepatic cells in nonprotocol liver biopsy specimens. Results Graft volume per standard liver volume was markedly increased after adult-to-adult living-donor (LD) LT. In pediatric transplants, there was no volume increase over time. PCNA labeling index was vigorous in adult-to-adult LDLT in the early period after LDLT. No Y chromosome was evident in hepatocytes from female-donor male-recipient grafts during or after liver regeneration. However, in the cases of failing grafts of this type, many Y-chromosome-positive cells were observed in the graft liver. The character of those cells was CD34(−), CK9(−), hepatocyte-specific antigen(−), and CD68(+/−). Conclusion In adult-to-adult LDLT, vigorous liver regeneration occurs in the graft liver, demonstrated by not only volumetric but cell kinetic analysis. Involvement of extrahepatic cells in normal liver regeneration seems limited

    Imaging-guided chest biopsies: techniques and clinical results

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    Background This article aims to comprehensively describe indications, contraindications, technical aspects, diagnostic accuracy and complications of percutaneous lung biopsy. Methods Imaging-guided biopsy currently represents one of the predominant methods for obtaining tissue specimens in patients with lung nodules; in many cases treatment protocols are based on histological information; thus, biopsy is frequently performed, when technically feasible, or in case other techniques (such as bronchoscopy with lavage) are inconclusive. Results Although a coaxial system is suitable in any case, two categories of needles can be used: fine-needle aspiration biopsy (FNAB) and core-needle biopsy (CNB), with the latter demonstrated to have a slightly higher overall sensitivity, specificity and accuracy. Conclusion Percutaneous lung biopsy is a safe procedure even though a few complications are possible: pneumothorax, pulmonary haemorrhage and haemoptysis are common complications, while air embolism and seeding are rare, but potentially fatal complications

    Thymoma calcification: Is it clinically meaningful?

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    Among anterior mediastinal lesions, thymoma is the most common. Thymomas are tumors of thymic epithelial cell origin that are distinguished by inconsistent histological and biologic behavior. Chest imaging studies typically show a round or lobulated tumor in the anterior mediastinum. Calcifications in thymomas are classically punctuate or amorphous, positioned within the lesion. Chest computed tomography (CT) features suggesting higher risk thymoma consist of tumor heterogeneity, vascular involvement, lobulation, pulmonary nodules, lymphadenopathy, and pleural manifestations. Imaging findings have an imperfect ability to predict stage and prognosis for thymoma patients. Our objective is to highlight the clinical implications of thymoma calcifications on the diagnosis, clinical manifestation and prognosis. A pubmed and google search was performed using the following words: thymoma calcification, calcified thymus, mediastinal calcification, anterior mediastinal calcification, and calcified thymoma. After reviewing 370 articles, 32 eligible articles describing thymoma calcifications were found and included in this review. Although the presence of thymus calcifications was more common in patients with invasive thymomas, they were present in significant portion of non-invasive thymomas. The presence of calcifications was not a significant factor in differentiating between benign and malignant thymoma. As a result, the type, location, size or other characteristics of thymus gland calcifications were not relevant features in clinical and radiologic diagnosis of thymoma. The histopathological diagnosis is still the only possible way to confirm the neoplastic nature of thymoma. All types of thymomas should be evaluated and managed independently of the presence of calcifications

    Pulmonary Alveolar Microlithiasis: CT and pathologic findings in 10 patients

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    Background and Aim. To evaluate CT findings of pulmonary alveolar microlithiasis and correlate the CT with the pathologic findings. Methods. The study included 10 patients with pathologically proven microlithiasis. Two independent observers evaluated the presence, extent and distribution of the CT findings. CT findings were compared with those at autopsy in two patients and with transbronchial biopsy in eight patients. Results. All patients had a myriad of calcified nodules measuring approximately 1 mm in diameter. Close apposition of the nodules resulted in areas of ground-glass attenuation and consolidation, which were the predominant abnormality on CT in all 10 patients, involving 41% ± 16.3 (mean ± SD) and 30% ± 4.8 of the lung parenchyma, respectively. Calcifications were also seen along interlobular septa, bronchovascular bundles and pleura. Other findings included interlobular septal thickening, thickening of bronchovascular bundles, nodules, and subpleural cysts. There was a solid agreement between the observers for the presence (kappa value; 0.77) and extent (Spearman rank correlation; r= 0.81 to 1.0 p<0.01) of abnormalities. Autopsy specimens demonstrated microliths in alveolar airspaces and along interlobular septa, bronchovascular bundles and pleura. Subpleural small cysts were shown to represent dilated alveolar ducts. Conclusion. Pulmonary microlithiasis is characterised by the presence of numerous small, calcified nodules, calcifications along interlobular septa, bronchovascular bundles and pleura, ground-glass opacities, consolidation, and subpleural cysts. The cysts represent dilated alveolar ducts
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