UWB Radio-over-Fiber System Using Direct Modulated VCSEL

The demand for efficient and cost-effective transmission and distribution of RF signal is increasing with the rapid development of wireless communication. This thesis studies the effect of using cost-effective vertical cavity surface emitting laser (VCSEL) to distribute ultra wide band (UWB) RF signal. Properties of multimode and single mode VCSEL are studied and simulated using commercial optical design suite. One of the biggest drawbacks of Orthogonal Frequency Division Multiplexing (OFDM) used by UWB is high peak to average power ratio (PAPR). Signal pre-distortion method is proposed to mitigate nonlinear effect from VCSEL optical system. Software connector is implemented to interconnect the Optical and Wireless design suite. Integrated VCSEL optical link and UWB simulation is carried out for the performance of the radio-on-fiber (RoF) system. The RoF system with optimized single mode VCSEL and proposed pre-distortion method is found to be capable of distributing UWB RF signal

The protective effect of rural life on mite sensitization disappears among urban migrants in the South of Vietnam.

BACKGROUND: Rapid urbanization combined with rural migration to urban areas in southern Vietnam could be risk factors for allergen sensitization, contributing to chronic respiratory diseases (CRD). We aimed to evaluate the prevalence of mite sensitization and its relation to house dust characteristics among rural and urban native and migrating populations with CRD. METHODS: Rural (n&nbsp;=&nbsp;19) and urban (n&nbsp;=&nbsp;46) dwellings were defined on the basis of a home typology. Controls were western Belgian houses (n&nbsp;=&nbsp;14). Besides the house characteristics, both endotoxin and mite allergens were measured in the settled dusts. The sensitization to mite allergens was defined by positive skin prick test (SPT) and concentration of specific IgE (sIgE)≥ 0.7 U/mL. The prevalence of mite sensitization was evaluated among 610 patients with CRD and compared according to both their home types and places of birth and&nbsp;residences. RESULTS: The concentration of endotoxin (but not mite allergen) was higher in rural compared to urban dusts (440 (95%CI: 314-566) versus 170 (95%CI: 115-226) EU/mg; p&nbsp;&lt;&nbsp;0.0001). The prevalence of positive sIgE to Der p1 and Der p2 was significantly lower in rural (9% and 5%) compared to urban (15% and 9%) population, consistent with the positive SPT to mite (14% and 21%, respectively). Among the urban migrants, the risk of mite sensitization (SPT) was higher compared to the rural natives (OR: 1.79 (1.02-3.15), p&nbsp;&lt;&nbsp;0.05) and not different to the urban ones (OR: 1.35 (0.82-2.23) p NS). CONCLUSION: In Vietnam, associated with higher endotoxin (but not allergen) dust concentrations, the risk of mite sensitization was lower in rural compared to the native urban population, but this protective effect could disappear among rural to urban&nbsp;migrants.</p

The influence of HIV infection on clinical presentation, response to treatment, and outcome in adults with Tuberculous meningitis.

BACKGROUND: Tuberculous meningitis occurs more commonly in human immunodeficiency virus (HIV)-infected individuals than in HIV-uninfected individuals, but whether HIV infection alters the presentation and outcome of tuberculous meningitis is unknown. METHODS: We performed a prospective comparison of the presenting clinical features and response to treatment in 528 adults treated consecutively for tuberculous meningitis (96 were infected with HIV and 432 were uninfected with HIV) in 2 tertiary-care referral hospitals in Ho Chi Minh City, Vietnam. Logistic regression was used to model variables associated independently with HIV infection, 9-month survival, and the likelihood of having a relapse or an adverse drug event. Kaplan-Meier estimates were used to compare survival rates and times to fever clearance, coma clearance, relapse, and adverse events. RESULTS: HIV infection did not alter the neurological presentation of tuberculous meningitis, although additional extrapulmonary tuberculosis was more likely to occur in HIV-infected patients. The 9-month survival rate was significantly decreased in HIV-infected patients (relative risk of death from any cause, 2.91 [95% confidence interval, 2.14-3.96]; P &lt; .001), although the times to fever clearance and coma clearance and the number or timing of relapses or adverse drug events were not significantly different between the groups. CONCLUSIONS: HIV infection does not alter the neurological features of tuberculous meningitis but significantly reduces the survival rate

Evaluation of the Luminex xTAG Respiratory Viral Panel FAST v2 assay for detection of multiple respiratory viral pathogens in nasal and throat swabs in Vietnam

Background Acute respiratory infections (ARI) are among the leading causes of hospitalization in children ≤5 years old. Rapid diagnostics of viral pathogens is essential to avoid unnecessary antibiotic treatment, thereby slowing down antibiotic-resistance. We evaluated the diagnostic performance of the Luminex xTAG Respiratory Viral Panel FAST v2 against viral specific PCR as reference assays for ARI in Vietnam. Methods Four hundred and forty two nose and throat swabs were collected in viral transport medium, and were tested with Luminex xTAG Respiratory Viral Panel FAST v2. Multiplex RT-PCR and single RT-PCR were used as references. Results Overall, sensitivity of the Luminex against reference assays was 91.8%, 95% CI 88.1-94.7 (270/294), whilst 112/6336 (1.8%, 95% CI, 1.4-2.1) of pathogens were detected by the Luminex, but not by reference assays. Frequency of pathogens detected by Luminex and reference assays was 379 and 292, respectively. The diagnostic yield was 66.7% (295/442, 95%CI 62.1-71.1%) for the Luminex assay and 54.1% (239/442, 95% CI, 49.3-58.8%) for reference assays. The Luminex kit had higher yields for all viruses except influenza B virus, respiratory syncytial virus, and human bocavirus. High agreements between both methods [mean (range): 0.91 (0.83-1.00)] were found for 10/15 viral agents. Conclusions The Luminex assay is a high throughput multiplex platform for rapid detection of common viral pathogens causing ARI. Although the current high cost may prevent Luminex assays from being widely used, especially in limited resource settings where ARI are felt most, its introduction in clinical diagnostics may help reduce unnecessary use of antibiotic prescription.</p

Evaluation of the Luminex xTAG Respiratory Viral Panel FAST v2 assay for detection of multiple respiratory viral pathogens in nasal and throat swabs in Vietnam [version 1; referees: 2 approved]

Background: Acute respiratory infections (ARI) are among the leading causes of hospitalization in children ≤5 years old. Rapid diagnostics of viral pathogens is essential to avoid unnecessary antibiotic treatment, thereby slowing down antibiotic-resistance. We evaluated the diagnostic performance of the Luminex xTAG Respiratory Viral Panel FAST v2 against viral specific PCR as reference assays for ARI in Vietnam. Methods: Four hundred and forty two nose and throat swabs were collected in viral transport medium, and were tested with Luminex xTAG Respiratory Viral Panel FAST v2. Multiplex RT-PCR and single RT-PCR were used as references. Results: Overall, viral pathogens were detected in a total count of 270/294 (91.8%, 95% CI 88.1-94.7) by the Luminex among reference assays, whilst 112/6336 (1.8%, 95% CI, 1.4-2.1) of pathogens were detected by the Luminex, but not by reference assays. Frequency of pathogens detected by Luminex and reference assays was 379 and 292, respectively. The diagnostic yield was 66.7% (295/442, 95%CI 62.1-71.1%) for the Luminex assay and 54.1% (239/442, 95% CI, 49.3-58.8%) for reference assays. The Luminex kit had higher yields for all viruses except influenza B virus, respiratory syncytial virus, and human bocavirus. High agreements between both methods [mean (range): 0.91 (0.83-1.00)] were found for 10/15 viral agents. Conclusions: The Luminex assay is a high throughput multiplex platform for rapid detection of common viral pathogens causing ARI. Although the current high cost may prevent Luminex assays from being widely used, especially in limited resource settings where ARI are felt most, its introduction in clinical diagnostics may help reduce unnecessary use of antibiotic prescription

Antioxidant and cytotoxic activity of lichens collected from Bidoup Nui Ba National Park, Vietnam

[[abstract]]Lichens were some of the earliest colonizers of terrestrial habitats on Earth. They represent a unique symbiont between fungi (mycobionts) and algae and/or cyanobacteria (photobionts). Lichens have been used as a cure for diabetes, coughs, pulmonary tuberculosis, wound healing, and dermatological diseases. The aim of this study is to investigate the in vitro antioxidant and cytotoxic activities of methanol lichen extracts. Fourteen lichen species from Bidoup Nui Ba National Park were identified according to their morphology and anatomical and chemical characteristics. The antioxidant activity of the methanol lichen extracts was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assay. The results showed that, of the lichens tested, L5 had the highest free radical activity with 50% inhibitory concentration (IC50) of 59.9 ± 4.65 mg mL−1. The methanol extract of L5 also showed the highest total flavonoid and polyphenol contents. In a cytotoxic assay, it was observed that the methanol extract of U38.1 exhibited high cytotoxic effect against MCF-7 cells, with IC50 of 34.27 ± 1.25 mg mL−1. The tested lichen extracts were also found to have slight cytotoxic effect on fibroblasts at screening concentration of 100 µg mL−1. All of the extracts were found to possess different cytotoxic activities against MO-91 cells, with IC50 values ranging from 10.50 ± 1.56 to over 50 mg mL−1. All of the extracts except U38.1 induced normal peripheral blood mononuclear cell (PBMC) proliferation, especially after 48 h of treatment at 25 µg/mL.[[notice]]補正完