ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / In NGN, the open interfaces and the IP protocol make the hazard of security aspect increased accordingly. Thereby, it is a very important premise for NGN network operation to afford a good secure media stream communication. In this paper, we will present a secure media stream communication for NGN. Then we will discuss the three parts of the media stream secure communication——media stream source authentication, secret key negotiation and distribution; media stream encryption/decryption in detail. It can effectively realize media stream end-to-end secure communication. Meanwhile, it also makes use of the expanding of former protocol during the secret key negotiation process.

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M.Ing. (Mechanical Engineering) / This dissertation presents and explains methods for the dynamic modeling of robot like mechanisms. These mechanisms can have multiple degree of freedom joints and contain closed-chains. A new kinematic notation is proposed. The algorithms, including those used for the inverse and direct dynamics, are all based on spatial notation and a general joint model, providing a quite general, integrated and complete method for solving the dynamics of simple closed-chain mechanisms.

In this work, the principal concern will be with the coupling reaction and it is anticipated that the other reactions referred to above will be considered further when products of the RX-R'Li reactions are discussed.

Student Number : 8801336R - M Dent research report - School of Oral Health (Dentistry) - Faculty of Health Sciences / The Johannesburg Hospital is a major referral centre for trauma in Johannesburg, and maxillofacial and oral surgery is one of the most utilized trauma and surgical departments at this Hospital. Mandibular fractures comprise the bulk of facial fractures treated; unit statistics on this type of fracture have been collected at intervals for thirty years. Data collection for the current report was undertaken to update statistics on mandibular fractures, and was undertaken over a six month period in 2004. This study assessed the epidemiology of mandibular fractures in 133 patients; concentrating on age, gender, race, mechanism and nature of injuries, site of fracture, treatment modalities and a cost analysis of surgical treatment. Black males in their 30’s made up the bulk of the study sample. A total of 203 fractures were noted, with a mean of 1.5 fractures per mandible; with angle fractures being the most commonly involved site (39%). Most patients sustained their injuries due to criminally motivated incidents. At least 75% of all fractures in this series were surgically treated. This report highlights some interesting trends that have changed over the last three decades, and attempts to offer some plausible explanations for this.

Thesis advisor: Amir H. HOveyda / Chapter 1: Ag-Catalyzed Enantioselective Vinylogous Mannich Reactions of Ketoimines Few catalytic methods have been reported for the enantioselective synthesis of N-substituted quaternary carbon stereogenic centers, typically the low reactivity of the electrophilic partner cannot be overcome. Herein, a silver-based catalyst is described which promotes highly site-, diastereo-, and enantioselective additions of siloxyfurans to ansidine-derived ketoimino esters. Mechanistic investigations, undertaken to elucidate the nature of the active silver-phosphine complex, supported the proposed origin for the anti-selective Mannich-type additions. Chapter 2: New Catalysts for the Enantioselective Cu-Catalyzed Additions of Allyl Groups to Phosphinoylaldimines The deficiencies in modern organic synthesis regarding the preparation of chiral molecules bearing amines, despite their incredible significance, are addressed. The development of a new method and catalyst for the preparation of enantiomerically enriched allyl-substituted alpha-chiral amines is described. Copper based catalysts bearing chiral C1-symmetric N-heterocyclic carbenes promote reactions between diphenylphosphinoyl aldimines and allyl boronic acid pinacol ester affording the homoallylic amines with high levels of efficiency and selectivity. Furthermore, the mechanistic rationale describing the selectivity patterns of the designed catalysts is analyzed. Chapter 3: NHC-Cu-Catalyzed Enantioselective Propargyl Group Additions to Phosphinoylaldimines The copper complex of a chiral N-heterocyclic carbene is found to be uniquely effective at promoting highly selective reactions of a commercially available allenylboron reagent and diphenylphosphinoyl aldimines. The enantiomerically enriched homopropargylic amines are exclusively afforded within an hour in the presence of as low as 0.25 mol % catalyst. The utility of the method is further demonstrated through the elaboration of the appended alkyne to difficult-to-access functionalities, highlighted by the synthesis of a key fragment for the preparation of the aza-epothilones, macrocyclic lactams which exhibit acute cytotoxicity. Chapter 4: Metal-Free Catalysts for Enantioselective Synthesis of Allenic Carbinols A metal-free catalyst, unique in structure and mechanism, is developed to address the remaining deficiencies in allyl addition chemistry, an area dominated by metal catalysis. The key organizational and enabling feature of the catalyst is a proton, a simple point charge which affects the facility of the C-C bond formation through electrostatic interactions. The unique alpha-selectivity delivered by the boron-based catalyst, a product of a catalytic cycle characterized by two gamma-selective allyl transfer processes, allows for the unprecedented synthesis of enantiopure allenyl-substituted tertiary alcohols. Moreover, the described transfomations can be performed in a matter of minutes with ˂0.5 mol % catalyst.

Thesis advisor: Lawrence T. Scott / Thermal cyclodehydrogenation is the key step in the total synthesis of fullerene C60 and represents an important family of carbon-carbon bond-forming reactions. My research focuses on understanding the mechanism of C-C bond formation in the high temperature cyclodehydrogenations of PAHs using appropriate test cases to form 5- or 6-membered rings. My goal was to understand more about molecular reactions under extreme conditions and thereby realize new synthetic pathways for new molecules. This dissertation describes the synthesis of several substrates and studies of their thermal cyclodehydrogenations. Chapter 1 presents the cyclodehydrogenations of [5]helicene and benzo[5]helicene to form 6-membered rings under flash vacuum pyrolysis (FVP) conditions. An observed rate difference established that an electrocyclic mechanism is favored in this case and disproved the radical cyclization and 1,2-hydrogen shift/carbene insertion mechanisms. Chapter 2 describes the cyclodehydrogenations of phenyl-substituted phenanthrenes to form 6-membered rings under FVP conditions. The radical mechanism is ruled out because of the rate difference. Chapter 3 shows the synthesis of 7-(9H-fluoren-9-ylidene)-7H-benzo[c]fluorene and its thermal cyclodehydrogenation to form 6-membered rings under FVP conditions. In chapter 4, the cyclodehydrogenations of phenyl-substituted anthracenes and phenanthrenes to form 5-membered rings under FVP conditions are presented. The unexpected dominance of phenyl loss suggests that radical mechanisms are occurring during the cyclodehydrogenations. Chapter 5 describes the cyclodehydrogenations of [4]helicene and benzo[4]helicene to form 5-membered rings under FVP conditions. The results point to a carbene cyclization mechanism, in competition with the radical mechanism. / Thesis (PhD) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

The Kyoto Protocol allows for the development of an international emissions-trading system. This led to the formulation of various mechanisms, namely Joint Implementation (JI), the Clean Development Mechanism (CDM) and Emissionstrading (ET). Given the potential emission-reduction targets in 2012 for developing countries, and in particular for South Africa, the objective of this study is identifying the current implementation of the CDM project cycle steps, as well as assessing the appropriateness of them. Constraints, bottlenecks and opportunities, are identified and suggestions for improvement are made, in order to improve the body of scientific knowledge. From the literature survey, and from discussions with experts in the field, it appears as if the benefits and issues identified, corroborate international findings. Benefits for countries hosting CDM projects include improved balance of payment, technology transfer and replacement of inefficient technology. Commonly occurring concerns, are that baseline setting, additionality and the entire CDM project cycle is complex. Resource and time constraints could jeopardize projects. Transaction costs have been prohibitive, further compounded by lack of initial upfront funding. Bureaucracy from the CDM executive board has frustrated attempts to implement projects. Lack of methodologies, as well as huge risk and cost in developing new methodologies have been obstacles for project developers, while clear guidelines on monitoring, governance and additionality have been conspicuously absent. Suggestions for improvement have been regular baseline revision and standard assessment procedures, application of the gold standard and an additionality tool. Issues that seem to be uniquely particular to South Africa are the slow adoption of large companies to accept the benefits of CDM, difficulty in convincing company executives to embark on CDM projects, as well as unwillingness to delegate authority to technical staff. Another notable pattern is a mismatch of opinion between scientists, academics and business. South Africa uniquely, produces 90% of its energy from fossil fuels, which could limit the adoption of CDM. Lack of institutional knowledge and experience is concerning, as well as ethics and little collaboration amongst stakeholders. Innovative suggestions for improvement have included a weighting for sustainable development indicators, benchmarks to simplify baselines, sink projects to be excluded owing to their risk, sellers clearing houses, industrial gases to be excluded, and programmatic CDM. Another important suggestion is that taxation of CDM credits should be abandoned, and the restrictive Public Finance Management Act to be improved. The proposed study has attempted to highlight some of these significant issues, with the view to improving the current knowledge and advance the possibility of alleviating some of these burdening issues.