906 resultados para coherence rivalry


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The competing powers of Saudi Arabia and Iran continue to redress and reverse the strategic imbalance and direction of the Middle East’s regional politics. The 1979 Iranian Revolution catapulted these two states into an embittered rivalry. The fall of Saddam Hussein following the 2003 U.S. led invasion, the establishment of a Shi’ite Iraq and the 2011 Arab Uprisings have further inflamed tensions between Saudi Arabia and Iran. Iran and Saudi Arabia have not confronted each other militarily, but rather have divided the region into two armed camps on the basis of political and religious ideology in seeking regional allies and promulgating sectarianism as they continue to exploit the region’s weak states in a series of proxy wars ranging from conflicts in Iraq to Lebanon. The Saudi-Iranian strategic and geopolitical rivalry is further complicated by a religious and ideological rivalry, as tensions represent two opposing aspirations for Islamic leadership with two vastly differing political systems. The conflict is between Saudi Arabia, representing Sunni Islam via Wahhabism, and Iran, representing Shi’ite Islam through Khomeinism. The nature of the Saudi-Iranian rivalry has led many Middle East experts to identify their rivalry as a “New Middle East Cold War.” The Saudi-Iranian rivalry has important implications for regional stability and U.S. national security interests. Therefore, this thesis seeks to address the question: Is a cold war framework applicable when analyzing the Saudi Arabian and Iranian relationship?

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Our study examines asymmetric rivalry within and between strategic groups defined according to the size of their members. We hypothesize that, owing to several forms of group-level effects, including switching costs and efficiency, strategic groups comprising large firms expect to experience a large amount of retaliation from firms within their group and accommodation from the group comprising smaller firms. Small firms, on the other hand, expect to experience a small amount of retaliation from the group comprising large firms and no reaction from the other firms in their group. We estimate the effect of group-level strategic interactions on firm performance. Our analysis reveals that the rivalry behavior within and between groups is asymmetric, which supports the dominant-fringe relation between firms, as described in our hypothesis.

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Purpose: To evaluate postoperative spectral-domain optical coherence tomography findings after macular hole surgery. Methods: Retrospective, interventional, nonrandomized study. Overall, 164 eyes of 157 patients diagnosed with macular hole were operated on by vitrectomy and internal limiting membrane peeling. Preoperative and postoperative best-corrected visual acuity and spectral-domain optical coherence tomography images were obtained. Two groups were considered on the basis of the postoperative integrity of the back reflection line from the ellipsoid portion of the photoreceptor inner segment: group A (disruption of ellipsoid portion of the inner segment line, 60 eyes) and group B (restoration of ellipsoid portion of the inner segment line, 104 eyes). Results: Logarithm of the minimum angle of resolution best-corrected visual acuity improved significantly after the surgery of macular hole from a mean preoperative value of 0.79 ± 0.37 (range, 0.15–2.00) to a mean postoperative value of 0.35 ± 0.31 (range, 0.00–1.30) at the last follow-up visit (P < 0.01). Best-corrected visual acuity improved significantly in the 2 groups analyzed (all P < 0.01). A larger improvement was found in group B than in group A (P < 0.01). Conclusion: Ellipsoid portion of the inner segment line reconstruction seems to be a good prognostic factor for visual rehabilitation after macular hole surgery.

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Purpose: To characterize the relationship between fundus autofluorescence (FAF), Optical Coherence Tomography (OCT) and immunohistochemistry (IHC) over the course of chronic retinal degeneration in the P23H rat. Methods: Homozygous albino P23H rats, Sprague–Dawley (SD) rats as controls and pigmented Long Evans (LE) rats were used. A Spectralis HRA OCT system was used for scanning laser ophthalmoscopy (SLO) imaging OCT and angiography. To determine FAF, fluorescence was excited using diode laser at 488 nm. A fast retina map OCT was performed using the optic nerve as a landmark. IHC was performed to correlate with the findings of OCT and FAF changes. Results: During the course of retinal degeneration, the FAF pattern evolved from some spotting at 2 months old to a mosaic of hyperfluorescent dots in rats 6 months and older. Retinal thicknesses progressively diminished over the course of the disease. At later stages of degeneration, OCT documented changes in the retinal layers, however, IHC better identified the cell loss and remodeling changes. Angiography revealed attenuation of the retinal vascular plexus with time. Conclusion: We provide for the first time a detailed long-term analysis of the course of retinal degeneration in P23H rats using a combination of SLO and OCT imaging, angiography, FAF and IHC. Although, the application of noninvasive methods enables longitudinal studies and will decrease the number of animals needed for a study, IHC is still an essential tool to identify retinal changes at the cellular level.

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The comprehensive structure of cooperation at domestic level reflects on bilateral, regional and global level.

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The complexity of migration issues is clearly reflected by states diverging national migration policy interests that exists within one state. In line with the Swiss Report on International Cooperation on Migration of the Swiss Federal Council , this complexity requires close coordination and cooperation between the governmental institutions and all offices. Only through a close and coherent cooperation between all governmental actors involved in migration issues the migration-development nexus can be strength. The present paper will suggest how intergovernmental cooperation can lead to better policy coherence in migration by interlinking all actors involved.

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PURPOSE To evaluate image contrast and color setting on assessment of retinal structures and morphology in spectral-domain optical coherence tomography. METHODS Two hundred and forty-eight Spectralis spectral-domain optical coherence tomography B-scans of 62 patients were analyzed by 4 readers. B-scans were extracted in 4 settings: W + N = white background with black image at normal contrast 9; W + H = white background with black image at maximum contrast 16; B + N = black background with white image at normal contrast 12; B + H = black background with white image at maximum contrast 16. Readers analyzed the images to identify morphologic features. Interreader correlation was calculated. Differences between Fleiss-kappa correlation coefficients were examined using bootstrap method. Any setting with significantly higher correlation coefficient was deemed superior for evaluating specific features. RESULTS Correlation coefficients differed among settings. No single setting was superior for all respective spectral-domain optical coherence tomography parameters (P = 0.3773). Some variables showed no differences among settings. Hard exudates and subretinal fluid were best seen with B + H (κ = 0.46, P = 0.0237 and κ = 0.78, P = 0.002). Microaneurysms were best seen with W + N (κ = 0.56, P = 0.025). Vitreomacular interface, enhanced transmission signal, and epiretinal membrane were best identified using all color/contrast settings together (κ = 0.44, P = 0.042, κ = 0.57, P = 0.01, and κ = 0.62, P ≤ 0.0001). CONCLUSION Contrast and background affect the evaluation of retinal structures on spectral-domain optical coherence tomography images. No single setting was superior for all features, though certain changes were best seen with specific settings.

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Published also as thesis (PH. D.) Columbia University, 1917.

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Bibl.: p. 177-184.