The success in fabrication of Cr-doped fibers (CDFs) with fluorescence of Cr3+ by powder-in-tube (PIT) method equipped with drawing-tower process is demonstrated for the first time. The fluorescence intensity of CDFs by fabricated RIT method is weak because the concentration of Cr-ion in Cr:YAG rod is low. However, the fabrication with powder-in-tube (PIT) provides a better solution to improve the concentration of Cr-ion to enhance the fluorescence of CDFs. The Cr-doped powder was composed of CaO-Al2O3-BaCO3-MgO-Cr2O3 as the material of core and then it was poured into the silica tube with outer diameter of 20 mm and inner diameter of 7 mm (20/7) to yield the perform. The CDFs had a 17.5 £gm core and a 125 £gm cladding. The transmission loss was 0.74 dB/cm at 1550 nm. And the fluorescence intensity of Cr3+ between 800~1200 nm was 50 nW/nm. To reduce transmission loss further, we used multi-tubes to raise the ratio of cladding to core. According to the principle of conservation of mass, the core diameter of CDFs was 5 £gm. The transmission loss was improved more than 50% and it reached to 0.135 dB/cm at 1550 nm. Moreover, a single-mode characteristic of CDF was observed when the propagation wavelengths were longer than 1260 nm. The CDFs were successfully fabricated by using a fiber drawing-tower technique with PIT method. The demonstration of CDFs makes it possible as a new generation broadband fiber amplifier, a tunable NIR fiber laser for sensor applications, and a broadband source for high resolution OCT.

The diploma thesis deals with the field of tourism industry. After a general definition of a broader context and key terms, the basic theoretical approaches to assessing the potential of tourism and the division of its assumptions are evaluated and compared, as well as its typology is outlined. Subsequently, the investigated destination of Podzvičinsko is defined territorially, and the studied theoretical approaches are applied in its description and a detailed inventory of attractions. Further, structured interviews with experts were conducted. The next step was to compile a questionnaire and its distribution to the wider public in order to find out data about potential visitors. On the basis of the provided information, the participants were divided into respective target segments. Specific tourism products have been designed for these segments which maximally correspond to the segments profiles, their goals and possibilities. The findings identified during the structured interviews and in the questionnaires also defined negatively perceived aspects of the destination, and measures were proposed for their improvement.

A força de adesão entre resinas e ligas de metais básicos resulta do embricamento mecânico entre a superfície do metal e a resina e da interação química entre óxidos presentes na superfície dos metais e monômeros adesivos das resinas compostas. A literatura, entretanto, mostra que ainda persistem algumas dúvidas sobre a interação entre os diversos tipos de sistemas adesivos e metais básicos, por isso, essa pesquisa visa: verificar se a presença do Be na composição de ligas a base de Ni-Cr influencia a união metal básico/resina; comparar dois cimentos resinosos adesivos nessa função e verificar a influência da utilização de condicionadores (primers) adesivos metálicos para ligas nobres sobre essa união. Após 2500 termociclos, foram realizados testes de resistência à tração em 160 corpos-de-prova, que consistiam de dois discos de Ni-Cr-Be (Verabond – Aalba Dental Inc., Cordelia, CA-USA) com 6 mm de diâmetro e 2 mm de espessura cimentados entre si, e dois discos de Ni-Cr (Durabond - Odonto Comercial Importadora Ltda, São Paulo, SP), com as mesmas dimensões, cimentados entre si. Foram utilizadas diferentes marcas comerciais de sistemas adesivos: os cimentos resinosos adesivos, Panavia F (Kuraray Co. Ltd.), Bistite II DC (Tokuyama Corp.) e os agente de união (primers adesivos metálicos), Alloy Primer (Kuraray Co. Ltd. ), Metaltite (Tokuyama Corp.) e Cesead Opaque Primer (Kuraray Co. Ltd.). Discos cimentados sem primers serviram como grupo controle. Os resultados mostraram que houve diferença estatisticamente significante entre as duas ligas (Ni-Cr-Be –24,82 ± 7,6 MPa e Ni-Cr - 22,32 ± 7,9 MPa). Já para os cimentos houve superioridade adesiva do cimento Panavia F, que obteve média de resitência adesiva de 27,49 ± 4,8 MPa, sobre o cimento Bistite II, que obteve média de resistência adesiva de 19,63 ± 8,4 MPa. Os primers utilizados não apresentaram influência positiva sobre o Panavia F já que os grupos sem primer para esse cimento obtiveram média de 28,18 ± 5,6 MPa que é equivalente a média dos outros grupos com Panavia. Entretanto, para o cimento Bistite II DC os primers Alloy Primer e Metaltite obtiveram as menores médias, 12,7 ± 7,6 MPa e 15,71 ± 4,8 MPa respectivamente, enquanto sem primer, ou com o Cesead Opaque Primer, as médias foram significantemente superiores, 24.47 ± 6 MPa e 25.70 ± 6,8 Mpa respectivamente. Diante dos resultados conclui-se que os primers adesivos metálicos não potencializaram a adesão de cimentos resinosos adesivos sobre ligas de Ni-Cr. / The bond strength for resin and basic metals comes from the interaction between oxides in the metal surface and adhesive monomers in the composite resins composition. The literature shows that still are some questions about this interaction so this research intends to: verify if the presence of Be at Ni-Cr alloy plays some influence for this union, compare two resin luting cements at this function and study the influence the use of metal primers for noble metals in this mecanism of adhesion. After 2500 thermocycles, tensile bond strength tests were loaded at 160 specimens, which consisted of two metals discs with 6 mm in diameter and 2 mm thick from a Ni-Cr-Be alloy (Verabond – Aalba Dental Inc., Cordelia, CA-USA) bonded togheter and two metal discs from a Ni-Cr alloy (Durabond - Odonto Comercial Importadora Ltda, São Paulo, SP) bonded togheter. Diferent brand adhesive systems were used: the resin cements, Panavia F (Kuraray Co. Ltd.) and Bistite II DC (Tokuyama Corp.) and the metal primers, Alloy Primer (Kuraray Co. Ltd.), Metaltite (Tokuyama Corp.) and Cesead Opaque Primer (Kuraray Co. Ltd.). Nonprimed specimens served as control group. The results indicated that there is statiscal diferences beetwen the two alloys (Ni-Cr-Be –24,82 ± 7,6 MPa e Ni-Cr - 22,32 ± 7,9 MPa). Panavia F had founded greater bond strength (27,49 ± 4,8 MPa) than Bistite DC (19,63 ± 8,4 MPa). The metal primers did not show any positive influence for the Panavia bond strength when we considere that the no primer group had 28,18 ± 5,6 MPa bond strength media which were equivalente to the others Panavia´s groups. However for the Bistite cement, the bond strength for Alloy primer and Metaltite were the lower medias, 12,7 ± 7,6 MPa and 15,71 ± 4,8 MPa respectivally, while the no primer or the Cesead Opaque Primer groups showed superior medias 24,47 ± 6 MPa and 25,70 ± 6,8 MPa respectivally. The outcome of this research shows that the metal primers used did not incresead the bond strength between resin cements and Ni-Cr alloys.

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Cheung Wing-chuen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 80-82). / Abstracts in English and Chinese. / Chapter 1 --- Introduction to CR manifolds --- p.6 / Chapter 1.1 --- Non-equivalence of real analytic hypersurfaces in C2 --- p.6 / Chapter 1.2 --- CR manifold and Levi form --- p.9 / Chapter 1.3 --- The real hyperquadrics --- p.16 / Chapter 2 --- Normal Forms --- p.22 / Chapter 2.1 --- Formal theory of normal forms --- p.22 / Chapter 2.2 --- Geometric theory of normal forms --- p.33 / Chapter 3 --- Connections and Curvatures --- p.45 / Chapter 3.1 --- Solution of the equivalence problem --- p.45 / Chapter 3.2 --- Geometric interpretation of the solution --- p.59 / Chapter 4 --- Chains --- p.65 / Chapter 4.1 --- Identification of the two definitions of chains --- p.65 / Chapter 4.2 --- Chain-preserving maps --- p.73 / Chapter 4.3 --- Some pathological behaviour of chains --- p.76 / Bibliography --- p.80

Lo, Chi Yu. / On t.p. "n" is a superscript. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 92). / Abstracts in Chinese and English. / Chapter 0 --- Introduction --- p.5 / Chapter 1 --- "CR structures and the group SU(p, q)" --- p.7 / Chapter 1.1 --- Almost complex structure and CR manifolds --- p.7 / Chapter 1.2 --- Automorphism Groups of Ball and Polydisc --- p.17 / Chapter 1.3 --- "The group SU(p,q) and its Maurer Cartan form" --- p.24 / Chapter 2 --- Cartan´ةs construction on nondegenerate CR manifold --- p.33 / Chapter 2.1 --- A digression on the Frobenius Theorem and projective structure --- p.33 / Chapter 2.2 --- Cartan bundle and canonical forms --- p.45 / Chapter 2.3 --- Calculations of real hypersurface in C2 --- p.60 / Chapter 3 --- Geometric consequences and chain --- p.66 / Chapter 3.1 --- CR equivalence problem --- p.66 / Chapter 3.2 --- CR manifolds of dimension 3 --- p.71 / Chapter 3.3 --- Definition of chains --- p.78 / Chapter 3.4 --- Chains on a special kind of Reinhardt hyper surf ace in C2 --- p.87 / Bibliography --- p.92

Hui, Chun Yin. / On t.p. "n" is a superscript. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 80-83). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.5 / Chapter 2 --- Basic properties of real hypersurfaces in CN --- p.9 / Chapter 2.1 --- Hypersurfaces in CN and some nondegeneracy conditions --- p.9 / Chapter 2.2 --- CR functions and their holomorphic extensions --- p.15 / Chapter 2.3 --- Normal coordinates for real analytic hypersurfaces --- p.18 / Chapter 3 --- The algebraic results for reflection principle --- p.22 / Chapter 4 --- Reflection principle for real analytic hypersurfaces in higher complex dimensions --- p.30 / Chapter 4.1 --- Reflection principle for Levi nondegenerate hypersurfaces --- p.31 / Chapter 4.2 --- Essentially finite real analytic hypersurfaces and not totally degenerate CR mappings --- p.38 / Chapter 4.3 --- Reflection principle for essentially finite hypersurfaces --- p.44 / Chapter 4.4 --- Reflection principle for CR mappings and bounded domains --- p.54 / Chapter 4.5 --- Futher results on the reflection principle --- p.64 / Chapter 5 --- An extension result of CR functions by a general Schwarz reflection principle --- p.66 / Chapter 5.1 --- A general Schwarz reflection principle --- p.66 / Chapter 5.2 --- "Holomorphic extension of CR functions on a real analytic, generic CR submanifold in CN" --- p.69 / Bibliography --- p.80

The success in fabrication of Cr-doped fibers (CDFs) with fluorescence of Cr3+ by powder-in-tube (PIT) method equipped with drawing-tower process is demonstrated. However, the fabrication by using powder-in-tube (PIT) with redrawing technique provides a better solution to improve the concentration of Cr-ion to enhance the fluorescence of CDFs. The Cr-doped powder was composed of CaO-Al2O3-BaCO3-MgO-Cr2O3 as the material of core. The CDFs had a 7 £gm core and a 125 £gm cladding. The transmission loss was 0.27 dB/cm at 1550 nm and a core non-circularity of less than 3% for the CDFs are achieved. The fluorescence intensity of Cr3+ between 800~1200 nm was 6 nW/nm. The optical fiber fabrication processes, whether the preform is made by MCVD(Modified Chemical Vapor Deposition), RIT(Rod-in-Tube) or PIT, the inter-diffusion between core and cladding materials is an inevitable issue at such high fiber drawing temperature. Since SiO2 is amajor component in the cladding, SiO2 will certainly diffuse into the core region and become one of the new constituents in the core. The Cr-doped powder was composed of SiO2- Al2O3-MgO-K2O-TiO2-Cr2O3 as the material of core. The CDFs had a 10 £gm core and a 125 £gm cladding. The fluorescence intensity of Cr4+ between 900~1300 nm was 200 pW/nm. The CDFs were successfully fabricated by using podwer-in-tube with redrawing technique. The demonstration of CDFs makes it possible as a new generation broadband fiber amplifier and a broadband source for high resolution OCT.

Abstract The breakthrough technology in dry fiber fabrication has opened the possibility for using fiber bandwidths all the way from 1.3 to 1.6 £gm. The fiber amplifier that is in common use can not fully cover the whole, which its range is from 1.3 to 1.6 £gm. Recently, the Cr4+-doped fiber has shown a broadband emission from 1.3 to 1.6 £gm. Therefore, it is eminently suitable for super-wideband optical source. In this study, we first propose and fabricate a Cr4+-doped fiber by employing a commercial drawing-tower method, which has good core diameter uniformity, the growth speed is up to 200 m/min, and the core diameter is less than 10 £gm. The central wavelength of the ASE spectrum is at 1310 nm, and a 3-dB bandwidth is 300 nm. The divergent angle of the Cr-doped fiber is 17 o ¡Ñ 15 o and it¡¦s also similar to a single mode fiber of 16 o ¡Ñ 16 o. Low-loss fusion splice can readily be done with the standard single mode fiber, and is beneficial when integrated with the broadband WDM couplers. Therefore, it is good for commercial production and application to light wave systems.

Title: Symmetries of the CR sub-Laplacian Author: Zuzana Vlasáková Department: Charles University Institute of Mathematics Supervisor: Prof. RNDr. Vladimír Souček, DrSc. Author's e-mail address: zuzana.kasarova@email.cz Supervisor's e-mail address: soucek@karlin.mff.cuni.cz Abstract: The aim of this work is to characterize the vector space of symme- try operators of the CR sub-Laplacian. To do this, we define a CR structure on some distinguished submanifold of Cn+1 (it is in fact the big cell in the CR sphere) and write down the CR sub-Laplacian on it. We also define the symmetries of the CR sub-Laplacian in general and using the ambient con- struction, which we introduce in the sequel, we construct all of them. Keywords: CR geometry, CR sub-Laplacian, symmetries of differential op- erator. 1