Viet Nam has an increasing need for building materials, including refractory bricks. Little is known regarding the occupational hazards incurred in brick manufacturing. To determine the occupational health hazards posed by a refractory brick operation in Ha Noi, Viet Nam, a cross-sectional occupational risk survey was conducted, focusing on respirable dust hazards. It included an industrial hygiene walk-through and gravimetric dust analysis. Noise, heat, lack of head protection, and dust exposure were hazards identified at the brick-manufacturing site. Respiratory protection involved a three-layer cloth mask that had not been tested for efficacy. Silica dust exposure levels exceeded the Vietnamese permissible exposure level by almost fivefold based on gravimetric assessment and estimated silica content. This brick manufacturing site contains significant injury and respiratory illness hazards. Further investigations are necessary to begin to develop occupational safety measures at the site.

Workers in this plant demonstrate a consistent pattern of radiographic evidence of pneumoconiosis, which appears to be related to duration of work. Future studies should assess exposure control measures that are appropriate to countries undergoing rapid industrialization such as Vietnam.

To determine the number and distribution of exposures among workers exposed to silica dust in Vietnam, a cross-sectional study was conducted of the provincial Preventive Medicine Centers (PMCs) of 61 provinces, and data were collected from medical centers (MCs) of the Ministries of Construction, Industry, and Transportation. The PMC survey identified 112,956 exposed workers in 31 provinces. Ministry data identified 240,744 exposed workers. Quang Ninh province, with 50,000-70,000, had the highest concentration. These estimates provide a range of 40,000-350,000 exposed workers, supporting the development of a validated registry of silica-exposed workers, essential to the development of a program for silicosis prevention in Vietnam.

The natural hydrology has decisive influence on waterways in South-East Asia. Many rivers in the region take meandering courses in their low reaches.The natural bed topography with alternative bar of the meandering rivers was considered from the navigation point of view. The Ikeda and Nishimura's mathematical model(1986) was applied to define the lateral bed topography in three case studies for Irrawaddy river, Chao Phraya river and Mekong river. It was found that the water level available for navigation in dry season could not afford to full load of the operating vessels.The payload of operating vessels over the year before and after local dredging has been predicted.

In this thesis, we present the model of right-handed neutrinos at electroweak scale (EW⌫ R) and its extended version under two crucial tests by the electroweak precision measurements and the discovery of the 125 GeV SM-like Higgs boson. The key feature of the model is the existence of non-sterile electroweak scale right-handed neutrinos together with scalar triplets. We show that the EW⌫ R model with the new particle content satisfies well the constraint of the electroweak precision measurements through the contribution to the oblique parameters, S, T, U. Moreover, the 125 GeV SM-like Higgs discovery necessitates extending the minimal EW⌫ R model by adding one more complex scalar doublet and imposing a new symmetry. We present two very distinct scenarios in which the 125 GeV Higgs boson candidate of the model behaves like and unlike the SM one. In both cases, the signal strength of the 125 GeV candidate satisfies the experimental results of the LHC. The phenomenology of the heavy spin-zero states is also taken into account.-i