The convective-diffusive transport of sub-micron aerosols in an oscillatory laminar flow within a 2-D single bifurcation is studied, using order-of-magnitude analysis and numerical simulation using a commercial software (FEMLAB®). Based on the similarity between momentum and mass transfer equations, various transient mass transport regimes are classified and scaled according to Strouhal and beta numbers. Results show that the mass transfer rate is highest at the carinal ridge and there is a phase-shift in diffusive transport time if the beta number is greater than one. It is also shown that diffusive mass transfer becomes independent of the oscillating outer flow if the Strouhal number is greater than one. / Singapore-MIT Alliance (SMA)

Rock climbing participation is growing throughout the United States. Information on the participation patterns and preferences of groups of climbers can be used to help mangers make better informed decisions, allowing them to cater to the specific interests of climbing participants, ensure participant satisfaction and encourage continued patronage. This study explores variation in participant characteristics across segments of the climbing population. Because an individual's level of specialization will align him with other like-minded participants, an understanding of a participant's stages of involvement and level of specialization assists in understanding the social world's views and behaviors toward the resource and toward other participants. Information on participants' level of experience, level of commitment, and demographic dimensions can be used to better understand and manage climbers. This study aimed to identify differences among groups of climbers. The study measured across 484 participants. The participants were described by various dependent variables, which included demographic factors, level of specialization, motivations for climbing, types of conflicts and constraints experiences, and setting preferences. Measuring the climbers' participation patterns identified participant sub-world groups. The four groups of climbing participants, as identified by this study, were: infrequent climbers, frequent outdoor climbers, frequent indoor climbers, and avid climbers. While demographics are not significantly descriptive of climbing sub-world affiliations, this study found that there were differences among sub-world affiliates in terms of specialization level, motives, conflicts, constraints, and setting preferences.

Fertility rates in sub Saharan Africa (SSA) have been identified to be depicted by a  unique demographic scenario, that sets  the region  apart from other regions in the world. Demographers are particularly keen on comprehending the dynamics surrounding the demographic transition of the sub continent especially with respect to its shift from high fertility rates to low fertility rates.  The decline in fertility embodies the second phase of the demographic transition process. The discourse on fertility rates in the sub continent has been coined to be an anomaly based on its prevalence being an exception in the world. Discussion pertaining to fertility levels in the region in this paper was made  with the purpose of illuminating the factors that account for the region’s high fertility rates, as well as on  fertility discourse in the region, and the variation that characterize its prevalence amongst the countries in the sub continent. Information on the fertility rates revealed that social organization and cultural setting in the region play pivotal roles in forging high fertility rates in the region.

Rationale: Ng et al. (2008) demonstrated that sub-acute hippocampal atrophy occurred between 4.5 and 24 months following moderate-to-severe traumatic brain injury (TBI); it remains to be determined if atrophy occurred before 24 months. Objectives: (1) to determine if sub-acute hippocampal atrophy occurs by the first year of injury; (2) to determine associated clinical and demographic variables. Methods: Ten moderate-to-severe TBI patients underwent MRI at 5 and 12 months post-injury. Glasgow Coma Scale (GCS) and demographic variables were correlated with change. Results: Significant hippocampal volume decreases were observed for right (P< 0.002, Cohen’s d= 0.34) and left (P< 0.036, Cohen’s d= 0.22) sides. GCS was significantly correlated with right (r= -0.663, P< 0.037), but not left percent hippocampal volume change (r= -0.327, P< 0.356). No significant correlations were observed for demographic variables. Conclusion: Sub-acute hippocampal atrophy occurs between 5 and 12 months post-injury and is associated with injury severity.

Rationale: Ng et al. (2008) demonstrated that sub-acute hippocampal atrophy occurred between 4.5 and 24 months following moderate-to-severe traumatic brain injury (TBI); it remains to be determined if atrophy occurred before 24 months. Objectives: (1) to determine if sub-acute hippocampal atrophy occurs by the first year of injury; (2) to determine associated clinical and demographic variables. Methods: Ten moderate-to-severe TBI patients underwent MRI at 5 and 12 months post-injury. Glasgow Coma Scale (GCS) and demographic variables were correlated with change. Results: Significant hippocampal volume decreases were observed for right (P< 0.002, Cohen’s d= 0.34) and left (P< 0.036, Cohen’s d= 0.22) sides. GCS was significantly correlated with right (r= -0.663, P< 0.037), but not left percent hippocampal volume change (r= -0.327, P< 0.356). No significant correlations were observed for demographic variables. Conclusion: Sub-acute hippocampal atrophy occurs between 5 and 12 months post-injury and is associated with injury severity.

Globalization of the world economy has made knowledge a critical element of effectiveness in the world economy. Current economic and trade conditions change rapidly and require constant improvement to ensure economic development. These conditions stimulate innovation and improvements in technology, designs, and other tangible and intangible assets. Most Sub-Saharan African countries have not exploited the benefits that intellectual property rights offer to its users, despite considerable improvements to existing knowledge and options for protecting knowledge. Strong intellectual property laws are important for effective incentives to invent continuously. It is important to provide some form of compensation and guarantee that their innovation is credited to them. This is achieved through the establishment of intellectual property rights. Intellectual property rights have far-reaching effects on several sectors of the economy, such as trade, manufacturing, and other industries. Intellectual property rights policies are therefore, important for economic development.

The laws of classical mechanics show that mechanical properties are independent of sample sizes. However, based on extensive theoretical work and experimentation, it is believed that reducing the size of materials to the submicron scale can result in different mechanical properties than those found in bulk quantities. This size effect was explained by the strain gradient. Atomic simulations have shown that yield stress depends on size even in the absence of the strain gradient. All of the experiments done on material creep behaviour, reported in the literature, have been conducted in the presence of strain gradient. This thesis focuses on the fabrication methods of freestanding indium pillar samples created by two unique methods; focused ion beam (FIB) and the micro-fabrication approach. The low melting point indium metal limits the application of FIB to form the sub-micron pillars. As a result, two different micro-lithography techniques, ultra-violet radiation and electron-beam lithography, were developed to fabricate these nano-pillars. In order to monitor the creep mechanism, which was dominant in this testing, the samples were then divided into two groups: polycrystalline and single-crystal pillars, each in different sizes. These pillars will later be compressed by a nano-indenter using a flat punch. Compressive stress, strain, and stiffness of the pillars will be measured to verify if the indium mechanical behavior deviates from the bulk in the absence of strong strain gradient.

The laws of classical mechanics show that mechanical properties are independent of sample sizes. However, based on extensive theoretical work and experimentation, it is believed that reducing the size of materials to the submicron scale can result in different mechanical properties than those found in bulk quantities. This size effect was explained by the strain gradient. Atomic simulations have shown that yield stress depends on size even in the absence of the strain gradient. All of the experiments done on material creep behaviour, reported in the literature, have been conducted in the presence of strain gradient. This thesis focuses on the fabrication methods of freestanding indium pillar samples created by two unique methods; focused ion beam (FIB) and the micro-fabrication approach. The low melting point indium metal limits the application of FIB to form the sub-micron pillars. As a result, two different micro-lithography techniques, ultra-violet radiation and electron-beam lithography, were developed to fabricate these nano-pillars. In order to monitor the creep mechanism, which was dominant in this testing, the samples were then divided into two groups: polycrystalline and single-crystal pillars, each in different sizes. These pillars will later be compressed by a nano-indenter using a flat punch. Compressive stress, strain, and stiffness of the pillars will be measured to verify if the indium mechanical behavior deviates from the bulk in the absence of strong strain gradient.

Possible fuel cycle scenarios for a helium-cooled, sub-critical, fast reactor with a fusion neutron source for the transmutation of spent nuclear fuel have been analyzed. The transmutation rate was set by the 3000MWth fission power output. The primary objective was to achieve greater than 90% burn of the transuranic (TRU) fuel obtained from spent nuclear fuel. A secondary objective was to examine the possibility of achieving this deep burn without reprocessing after initial fabrication of the TRU into coated particle TRISO fuel. Four sets of 5-batch fuel cycle scenarios, differing in the constraints imposed on the beginning of cycle (BOC) k-eff and the end of cycle (EOC) neutron source strength (characterized by the fusion neutron source power level), were evaluated. In scenario A, BOC k-eff was required to be 0.95 and EOC Pfus less than 200 MWth was required. In scenario B, the restriction was removed to allow less reactive BOC fuel loadings, while the 200 MW upper limit on EOC Pfus was retained. It was found that the primary objective of greater than 90% TRU burn-up could be achieved by repeatedly reprocessing the TRISO TRU fuel particles to remove fission products and add fresh TRU makeup at the end of each 5-batch burn cycle, without needing to increase the fusion neutron source power above 100 MWth when the BOC k-eff is restricted to 0.95. The secondary objective of obviating processing could only be accomplished when the restriction was removed and recycling was employed or when both EOC Pfus and BOC k-eff restrictions were removed in a single-pass deep burn fuel cycle. In scenario C, with both the BOC k-eff limit and the fusion power limit unrestricted, greater than 90% TRU burn-up was achieved without reprocessing the TRISO TRU fuel particles, which could then be buried intact in a high-level waste repository, but a neutron source rate of 3370 MWth was required. In scenario D, with only the BOC k-eff limit unrestricted, greater than 90% TRU burn-up was achieved without reprocessing by the continuous recycle of TRISO particles through the reactor.

Recovery of unattached offshore facilities or missing equipments is a challenging activity. Generally speaking, this activity involves a comprehensive procedure which includes: target characterization, searching, detection, verification, locating, reacquisition and salvage. Among them, target searching and detection are the most critical components of the whole procedure. The purpose of this investigation was dedicated in discussing the efficiency by the application of side-scan sonar, magnetometer and sub-bottom profiler simultaneously in searching, detecting, identifying and locating underwater stationary targets. Procedures of this research include: 1. Discussing the capabilities of instruments and verification cruises on target. 2. Discussing the salvage activity we conducted off Kaohsiung harbor on a depleted anchor. 3. Estimating the practicability of the methodology. According to the characteristics of these apparatus, the water depth, collected by echo sounder, is capable of expressing the relief of the seabed. Seabed sonographs, recorded by side-scan sonar, show that it is feasible to detect, verify and locate targets on the seabed. Sub-bottom profiler provides the sub-surface sedimentary information which can be used to detect buried targets. Magnetometer can detect environmental magnetic intensities, which can locate and determine the size of ferrous targets. Two depleted anchors were recorded off Kaohsiung harbor on the navigation chart. A recovery plan was then arranged which included 4 phases: collection of anchor characteristics, initial field survey and target detection, target verification and locating, target recovery. The underwater searching equipment employed in this activity include: side-scan sonar, sub-bottom profiler, magnetometer, echo sounder, underwater positioning system (include GPS), remotely operated vehicle (ROV) and professional divers. The offshore working platform used in this activity was R/V Ocean Research#3. Results of the initial search phase by side-scan sonar indicated there was only one potential target in the searching area. Follow up verification cruises confirmed acoustically that the target was an anchor with a piece of chain clogged on a block. The results of this investigation included the information such as the dimensions and the location of the anchor. Furthermore, the reason which caused the anchor being abandoned on the seafloor was derived. For underwater ferrous targets, such as anchor and chain cable, all of the aforementioned apparatus, have good potential for their detection and verification. It can be concluded that, applying these apparatus simultaneously can more effectively conduct searching, detecting, identifying and locating underwater stationary targets than by the application of a single instrument such as side-scan sonar system. Optical verifications of this target by ROV were attempted, nevertheless, were not success due to the difficulties in maneuvering OR#3 into proper position. An attempt to recovery this target by divers was arranged. But due to bad weather and rough sea state, the divers were not even allowed to dive. However, according to the experiences collected, a target reacquisition and recovery facility was built to fulfill the necessity of guiding divers to the target and lift it.