1,042 research outputs found

    Temperature dependence of ultraviolet absorption cross-sections of alternative hydrochlorofluorocarbons

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    Ultraviolet absorption cross-section of six alternative hydrochlorofluorocarbons (HCFC-21 HCFC-22, HCFC-123, HCFC-124, HCFC-141b and HCFC-142b1) have been measured between 170 and 260 nm for temperature ranging from 210 to 295 K. These data are compared with other available determinations performed at room temperature and their temperature dependence is discussed. Photodissociation coefficients are estimated and their temperature dependence is discussed. Impact of the photodissociation on the total atmospheric destruction of these compounds is illustrated

    Ultraviolet absorption cross-sections of some carbonyl compounds and their temperature dependence

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    Ultraviolet absorption cross-section of phosgene (CCl2O), trichloroacetylchloride (CCl3-CClO) and trichloroacetaldehyde (CCl3-CHO) have been measured between 170 and 320 nm for temperature ranging from 210 to 295 K with classical double beam equipment. These data are compared with other available determinations performed at room temperature. Photodissociation coefficients are estimated and their temperature dependence is discussed. Impact of the photodissociation on the total atmospheric destruction of these compounds is illustrated

    Optimization of Apodized Pupil Lyot Coronagraph for ELTs

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    We study the optimization of the Apodized Pupil Lyot Coronagraph (APLC) in the context of exoplanet imaging with ground-based telescopes. The APLC combines an apodization in the pupil plane with a small Lyot mask in the focal plane of the instrument. It has been intensively studied in the literature from a theoretical point of view, and prototypes are currently being manufactured for several projects. This analysis is focused on the case of Extremely Large Telescopes, but is also relevant for other telescope designs. We define a criterion to optimize the APLC with respect to telescope characteristics like central obscuration, pupil shape, low order segment aberrations and reflectivity as function of the APLC apodizer function and mask diameter. Specifically, the method was applied to two possible designs of the future European-Extremely Large Telescope (E-ELT). Optimum configurations of the APLC were derived for different telescope characteristics. We show that the optimum configuration is a stronger function of central obscuration size than of other telescope parameters. We also show that APLC performance is quite insensitive to the central obscuration ratio when the APLC is operated in its optimum configuration, and demonstrate that APLC optimization based on throughput alone is not appropriate.Comment: 9 pages, 17 figures, accepted for publication in Astronomy & Astrophysic

    Plerixafor prescription modalities in autologous haematopoietic stem cell mobilization in Belgium

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    Objectives: The efficacy and safety of plerixafor, an antagonist of the CXCR4 receptor, in combination with G-CSF has been demonstrated in patients suffering from Iymphoma and multiple myeloma (MM) eligible for autologous haematopoietic stem cell collection. However, different reimbursement criteria have been applied in different countries to select patients eligible for treatment with plerixafor. The objective of this observational study was to describe the plerixafor prescription modalities in daily practice in Belgium. Methods: This open-label, prospective, observational study was conducted in 11 Belgian centres in 114 patients with lymphoma (Hodgkin's and non-Hodgkin's lymphoma) or MM who were treated with plerixafor according to the SmPC between April 2011 and October 2012. Patients included in another clinical trial with plerixafor were excluded from the study. Results: The use of plerixafor in patients with MM or lymphoma was effective, with a success rate (defined as a total yield > 2 x 10(6) CD34+ cells/kg) of 77%, and well tolerated (one SAE reported). Optimal collection (defined as a total yield >4 x 10(6) CD34+ cells/kg) was obtained for 43% of the study population (31% in lymphoma patients, compared to 61% in patients with MM). The use of plerixafor was in line with the SmPC and the Belgian reimbursement criteria for all patients. Conclusion: This study is showing that the use of plerixafor according to Belgian reimbursement criteria results in similar efficacy and safety as in other centres and countries worldwide

    Comparison of coronagraphs for high contrast imaging in the context of Extremely Large Telescopes

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    We compare coronagraph concepts and investigate their behavior and suitability for planet finder projects with Extremely Large Telescopes (ELTs, 30-42 meters class telescopes). For this task, we analyze the impact of major error sources that occur in a coronagraphic telescope (central obscuration, secondary support, low-order segment aberrations, segment reflectivity variations, pointing errors) for phase, amplitude and interferometric type coronagraphs. This analysis is performed at two different levels of the detection process: under residual phase left uncorrected by an eXtreme Adaptive Optics system (XAO) for a large range of Strehl ratio and after a general and simple model of speckle calibration, assuming common phase aberrations between the XAO and the coronagraph (static phase aberrations of the instrument) and non-common phase aberrations downstream of the coronagraph (differential aberrations provided by the calibration unit). We derive critical parameters that each concept will have to cope with by order of importance. We evidence three coronagraph categories as function of the accessible angular separation and proposed optimal one in each case. Most of the time amplitude concepts appear more favorable and specifically, the Apodized Pupil Lyot Coronagraph gathers the adequate characteristics to be a baseline design for ELTs.Comment: 12 pages, 6 figures, Accepted for publication in A&

    Intentional replantation for the management of maxillary sinusitis

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    Aim. To present a case that emphasizes the importance of the use of intentional replantation as a technique to successfully treat a periapical lesion and an odontogenic maxillary sinusitis through the alveolus at the same time. Summary. This case report presents a patient with odontogenic maxillary sinusitis secondary to periapical disease of a maxillary molar that had previously received root canal treatment. The molar was extracted, with drainage and rinsing of the maxillary sinus. The apices were resected extra-orally, and the retrograde cavity was prepared with ultrasound and retrograde filling using silver amalgam. The tooth was then replanted. After 2 years, the patient was asymptomatic, periapical radiography showed no evidence of root resorption and computed tomography scanning demonstrated the resolution of maxillary sinusitis

    Human Resources and the Resource Based View of the Firm

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    The resource-based view (RBV) of the firm has influenced the field of strategic human resource management (SHRM) in a number of ways. This paper explores the impact of the RBV on the theoretical and empirical development of SHRM. It explores how the fields of strategy and SHRM are beginning to converge around a number of issues, and proposes a number of implications of this convergence
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