| 1. |
- Duong, Quang Trung, et al.
(författare)
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Pairwise Error Probability of Distributed Space--Time Coding Employing Alamouti Scheme in Wireless Relays Networks
- 2009
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Ingår i: Wireless personal communications. - : Springer. - 0929-6212 .- 1572-834X. ; 51:2, s. 231-244
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we analyze the pairwise error probability (PEP) of distributed space-time codes, in which the source and the relay generate Alamouti space--time code in a distributed fashion. We restrict our attention to the space-time code construction for Protocol III in [1]. In particular, we derive two closed-form approximations for PEP when the relay is either close to the destination or source and an upper bound for any position of the relay. Using the alternative definition of $Q$-function, we can express these PEPs in terms of finite integral whose integrand is composed of trigonometric functions. We further show that with only one relay assisted source-destination link, system still achieves diversity order of two, assuming single-antenna terminals. We also perform Monte-Carlo simulations to verify the analysis.
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| 2. |
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| 3. |
- Thanh, Nguyen Xuan, et al.
(författare)
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Does poverty lead to non-fatal unintentional injuries in rural Vietnam?
- 2005
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Ingår i: International Journal of Injury Control and Safety Promotion. - : Informa UK Limited. - 1745-7300 .- 1745-7319. ; 12:1, s. 31-37
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify associations between poverty at the household level and unintentional injury morbidity. A cohort consisting of 24,874 person-time episodes, representing 24,776 people living in 5,801 households (classified into rich, middle income and poor by local authorities in 1999) was followed during 2000, in order to identify and assess non-fatal unintentional injuries. Incidence rate ratios were calculated using a Poisson regression model. The results showed that poverty was a risk factor for unintentional injuries generally. When looking at different types of injury, poverty was a risk for home, work and "other" injuries, protective for school injuries, while the risk of traffic injuries was not affected. The results also showed that communes in mountainous areas were at higher risk for home, work and other injuries. Overall, poverty was associated with unintentional injury morbidity. However, the relationship varied by sex, age and type of injury. Specifically, poverty increased the risk for children and elderly people being injured at home, and for adults (15-59 years) being affected by work injuries.
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| 4. |
- Thanh, Nguyen Xuan, et al.
(författare)
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Does "the injury poverty trap" exist? A longitudinal study in Bavi, Vietnam.
- 2006
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Ingår i: Health Policy. - : Elsevier BV. - 0168-8510 .- 1872-6054. ; 78:2-3, s. 249-257
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Tidskriftsartikel (refereegranskat)abstract
- In this study we concentrate on injuries and affected households' capacities to earn incomes. A longitudinal study was performed in Bavi district, Vietnam, with the specific objectives to investigate: (1) the affects of injuries on incomes by comparing income changes in injured and non-injured individuals; (2) the affect of injuries on social mobility by estimating households' relative risk of dropping into poverty for households with and without injuries and estimating the relative risk of escaping from poverty for households without and with injuries. The propensity score matching method using a logit model was used for data analysis. The results show that on average, the loss per household is estimated at VND 1,084,000 (USD 72) for poor and VND 2,598,000 (USD 173) for non-poor, equivalent to 11 (9) and 15 (13) working months of an average person in the poor and non-poor group, respectively, during 1999 (2001). The relative risk of dropping into poverty for non-poor households with and without injuries equal to 1.21 (p=0.08) and the relative risk of escaping from poverty between poor households without and with injuries equal to 0.96 (p=0.39). In conclusion, it has been argued that the introduction of user fees created a poverty trap and thus their removal may be a solution. However, user fees are only a part of the burden on households. Loss of income during the illness period is likely to be a problem of the same magnitude. A successful solution must thus follow two tracks: prepayment of health care and some insurance based compensation of income losses during the illness period. Both reforms, if they are persistent, must be done within the resource limits of the local society. If the risk of catastrophic illness is more evenly spread across the society, it would increase the general welfare even if no more resources are provided.
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| 5. |
- Duong, Quang Trung, et al.
(författare)
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On the Performance of Two-Way Amplify-and-Forward Relay Networks
- 2009
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Ingår i: IEICE transactions on communications. - : IEICE. - 0916-8516 .- 1745-1345. ; E92-B:12, s. 3957-3959
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Tidskriftsartikel (refereegranskat)abstract
- The performance of two-way amplify-and-forward (AF) relay networks is presented. In particular, we derive exact closed-form expressions for symbol error rate (SER), average sum-rate, and outage probability of two-way AF relay systems in independent but not identically distributed (i.n.i.d.) Rayleigh fading channels. Our analysis is validated by a comparison against the results of Monte-Carlo simulations.
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| 7. |
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| 8. |
- Minh, Hoang Van, 1971-
(författare)
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Epidemiology of cardiovascular disease in rural Vietnam
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the context of transitional Vietnam, although cardiovascular disease (CVD) has been shown to cause a large burden of mortality and morbidity in hospitals, little is known about the magnitude of its burden, risk factor levels and its relationship with socio-demographic status in the overall population. This thesis provides a preliminary insight into population-based knowledge of the CVD epidemiology in rural Vietnam and contributes to the development of methodologies for monitoring it. The ultimate goal of the work is to facilitate the formulation of evidence-based health interventions for reducing the burden of the CVD epidemic in Vietnam and elsewhere. This work was located in Bavi district, a rural community in the north of Vietnam. Studies on cause-specific mortality and risk factors were conducted within the framework of an ongoing Demographic Surveillance System (DSS) (called FilaBavi). The cause-specific mortality study used a verbal autopsy (VA) approach to identify causes of death in FilaBavi during 1999-2003. The risk factor study, conducted in 2002, employed the WHO STEPwise approach to surveillance of non-communicable disease (NCD) risk factors (WHO STEPS). Findings indicated that Bavi district, as an example of rural Vietnam, was already experiencing high rates of CVD mortality and associated risk factors. Mortality results indicated a substantial proportion of deaths due to CVD, which was the leading cause of death (20% and 25.7% of total mortality in 1999 and 2000, respectively and 32% of adult deaths during 1999-2003), exceeding infectious diseases. Hypertension was found to be a serious problem in terms both of its magnitude (14% of the population) and widespread unawareness (82% of the hypertensives). Smoking prevalence was very high among men (58% current daily smokers) and might be expected to cause a considerable number of future deaths without urgent action. CVD mortality and some risk factors seemed to be rising among disadvantaged groups (women, less educated people and the poor). The combination of DSS and WHO STEPS methodologies was shown to have potential for addressing basic epidemiological questions as to how NCD and CVD mortality and associated risk factors are distributed in populations. Given this evidence, actions to prevent CVD in Bavi and similar settings are clearly urgent. Interventions should be comprehensive and integrated, including both primary and secondary approaches, as well as policy-level involvement. Further studies, continuing on similar lines, plus qualitative approaches and deeper cross-site comparisons, are also needed to give further insights into CVD epidemiology in this type of setting.
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| 9. |
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| 10. |
- Nguyen, Hoang, 1965-, et al.
(författare)
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A continuous wavelet-Galerkin method for the linear wave equation
- 2007
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Ingår i: SIAM Journal on Scientific Computing. - 1064-8275 .- 1095-7197.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We consider the continuous space-time Galerkin method for the linear second-order wave equation proposed by French and Peterson in 1996. A bottleneck for this approach is how to solve the discrete problems effectively. In this paper, we tackle this bottleneck by essentially employing wavelet bases in space. We show how to decouple the corresponding linear system and we prove that the resulting subsystems can be uniformly preconditioned by simple diagonal preconditioners, leading to efficient iterative solutions.
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