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Search Results: 1 - 10 of 37312 matches for " Van Kinh Nguyen "
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Full-Filling Subcarrier Power Allocation in OFDMA-Based Cognitive Radio Systems  [PDF]
Tuan Le Van, Hieu Dinh Chi, Kinh Nguyen Viet, Hieu Nguyen Thanh
Wireless Engineering and Technology (WET) , 2014, DOI: 10.4236/wet.2014.51002

When implementing an appropriate windowing, the interference from a Cognitive Radio (CR) system to licensed systems (primary users) will be significantly reduced. Consequently, power allocated to subcarriers can be increased, especially subcarriers having far spectral distance to primary user bands can be allocated full of its maximum possible power. In this paper, we propose a new class of sub-optimal subcarrier power allocation algorithm that significantly reduces complexity of OFDMA-based CR systems. Two sub-optimal proposals, called Pre-set Filling Range (PFR) and Maximum Filling Range (MFR) are studied. Investigations show that this new power allocating algorithm allows CR systems obtain high throughput while retaining low complexity.

Influenza A H5N1 and HIV co-infection: case report
Annette Fox, Peter Horby, Nguyen Ha, Le Nguyen Hoa, Nguyen Lam, Cameron Simmons, Jeremy Farrar, Nguyen Van Kinh, Heiman Wertheim
BMC Infectious Diseases , 2010, DOI: 10.1186/1471-2334-10-167
Abstract: A 30-year-old male was admitted on day 4 of influenza-like-illness with tachycardia, tachypnea, hypoxemia and bilateral pulmonary infiltrates. Influenza A/H5N1 and HIV tests were positive and the patient was treated with Oseltamivir and broad-spectrum antibiotics. Initially his condition improved coinciding with virus clearance by day 6. He clinically deteriorated as of day 10 with fever recrudescence and increasing neutrophil counts and died on day 16. His admission CD4 count was 100/μl and decreased until virus was cleared. CD8 T cells shifted to a CD27+CD28- phenotype. Plasma chemokine and cytokine levels were similar to those found previously in fatal H5N1.The course of H5N1 infection was not notably different from other cases. Virus was cleared despite profound CD4 T cell depletion and aberrant CD8 T cell activation but this may have increased susceptibility to a fatal secondary infection.Influenza A/H5N1 infection is characterized by high viral loads, overproduction of pro-inflammatory cytokines and chemokines, direct lung tissue destruction, pulmonary oedema and extensive inflammatory infiltration [1-3]. The prevailing view is that alveolar damage is the primary pathology leading to acute respiratory distress, multiple organ dysfunction syndrome and death [3]. Likewise, 2009 H1N1 infection can cause acute respiratory distress syndrome and death in previously healthy young adults very similar to the clinical syndrome seen in H5N1 [4].It remains unclear whether lung pathology in severe influenza is a direct consequence of high viral loads and/or of ensuing inflammatory responses. The involvement of innate versus adaptive immunity in inflammation or controlling viremia is also poorly defined. Further understanding of the pathological processes is necessary to develop interventions that prevent severe lung disease. The occurrence of H5N1 infection in a patient with HIV infection offered a unique opportunity to study the pathological and immunological process when
The effect of imposing a higher, uniform tobacco tax in Vietnam
Hoang Van Kinh, Hana Ross, David Levy, Nguyen Minh, Vu Ngoc
Health Research Policy and Systems , 2006, DOI: 10.1186/1478-4505-4-6
Abstract: While smoking prevalence has been decreasing in many of the more developed nations, rates have been high and increasing in many of the poorer nations. For example, smoking rates among Vietnamese males 15 year of age and older was 50% in 1997–98,[3] but rose to 56% in 2002.[4]The Government of Vietnam is aware of the impact of smoking on public health. It has launched a campaign against smoking by issuance of a Government Resolution on National Tobacco Control Policy[5] in 2000 with target of reducing the tobacco use prevalence rate to 20% for males and 2% for females in 2010. Vietnam was one of the first Asian nations to sign the World Health Organization's Framework Convention for Tobacco Control in 2003.Tobacco tax increase is among the measures suggested in the 2000 Resolution to achieve its goal of lower smoking prevalence. Other components of the tobacco control program include total ban on cigarette advertising, ban on distributing free cigarette samples, ban on vending machines selling cigarettes, and ban on smoking in all public places. Research evidence shows that imposing taxes on tobacco, as part of a comprehensive tobacco control program, is among the most effective methods of reducing tobacco use.[6,7] Higher taxes create incentives for some regular smokers to quit smoking, help prevent the young from initiating smoking, and reduces consumption among continuing smokers.The majority of evidence on the price responsiveness of tobacco demand is for high-income countries were data and the research capacity exists. Estimates of the price-elasticity for overall cigarette demand fall in a relatively wide range due to model specification, data issues and estimating methodology,[8,9] but the majority center in the relatively narrow range from -0.25[10] to -0.5.[11,12] Evidence does indicate that low income groups in the high income countries are more sensitive to cigarette prices compared to higher income groups.[13]Recent studies have begun to focus on tobacco
Modelling the progression of pandemic influenza A (H1N1) in Vietnam and the opportunities for reassortment with other influenza viruses
Maciej F Boni, Bui Manh, Pham Thai, Jeremy Farrar, Tran Hien, Nguyen Hien, Nguyen Van Kinh, Peter Horby
BMC Medicine , 2009, DOI: 10.1186/1741-7015-7-43
Abstract: We developed an age- and spatially-structured mathematical model in order to estimate the potential impact of pandemic H1N1 in Vietnam and the opportunities for reassortment with animal influenza viruses. The model tracks human infection among domestic animal owners and non-owners and also estimates the numbers of animals may be exposed to infected humans.In the absence of effective interventions, the model predicts that the introduction of pandemic H1N1 will result in an epidemic that spreads to half of Vietnam's provinces within 57 days (interquartile range (IQR): 45-86.5) and peaks 81 days after introduction (IQR: 62.5-121 days). For the current published range of the 2009 H1N1 influenza's basic reproductive number (1.2-3.1), we estimate a median of 410,000 cases among swine owners (IQR: 220,000-670,000) with 460,000 exposed swine (IQR: 260,000-740,000), 350,000 cases among chicken owners (IQR: 170,000-630,000) with 3.7 million exposed chickens (IQR: 1.9 M-6.4 M), and 51,000 cases among duck owners (IQR: 24,000 - 96,000), with 1.2 million exposed ducks (IQR: 0.6 M-2.1 M). The median number of overall human infections in Vietnam for this range of the basic reproductive number is 6.4 million (IQR: 4.4 M-8.0 M).It is likely that, in the absence of effective interventions, the introduction of a novel H1N1 into a densely populated country such as Vietnam will result in a widespread epidemic. A large epidemic in a country with intense human-animal interaction and continued co-circulation of other seasonal and avian viruses would provide substantial opportunities for H1N1 to acquire new genes.In early 2009 a novel influenza A (H1N1) variant emerged which spread globally causing the first influenza pandemic in over 40 years. The dynamics and impact of this pandemic are difficult to predict, especially since the world has changed significantly in 40 years - the global population has almost doubled, more people live in cities, people travel more frequently and over longer
Stimulating the development of national Streptococcus suis guidelines in Viet Nam through a strategic research partnership
Horby,Peter; Wertheim,Heiman; Ha,Nguyen Hong; Trung,Nguyen Vu; Trinh,Dao Tuyet; Taylor,Walter; Ha,Nguyen Minh; Lien,Trinh Thi Minh; Farrar,Jeremy; Kinh,Nguyen Van;
Bulletin of the World Health Organization , 2010, DOI: 10.1590/S0042-96862010000600015
Abstract: problem: streptococcus suis is a common cause of adult bacterial meningitis in viet nam, and possibly other parts of asia, yet this disabling infection has been largely neglected. prevention, diagnosis and treatment are relatively straightforward and affordable but, in early 2007, no national diagnostic, case management or prevention guidelines existed in viet nam. approach: enhanced detection of s. suis infections was established in 2007 as part of a collaborative research programme between the national hospital for tropical diseases, a key national hospital with very close links to the ministry of health, and a research group affiliated with oxford university based in viet nam. the results were reported directly to policy-makers at the ministry of health. local setting: viet nam is a low-income country with a health-care system that has seen considerable improvements and increased autonomy. however, parts of the system remain fairly centralized the ministry of health. relevant changes: following the improved detection and reporting of s. suis cases, the ministry of health issued guidance to all hospitals in viet nam on the clinical and laboratory diagnosis, treatment and prevention of s. suis. a public health laboratory diagnostic service was established at the national institute of hygiene and epidemiology and training courses were conducted for clinicians and microbiologists. ministry of health guidance on surveillance and control of communicable diseases was updated to include a section on s. suis. lessons learnt: research collaborations can efficiently inform and influence national responses if they are well positioned to reach policy-makers.
Human immunodeficiency virus (HIV) infection patterns and risk behaviours in different population groups and provinces in Viet Nam
Tuan,Nguyen Anh; Fylkesnes,Knut; Thang,Bui Duc; Hien,Nguyen Tran; Long,Nguyen Thanh; Van Kinh,Nguyen; Thang,Pham Hong; Manh,Pham Duc; O'Farrell,Nigel;
Bulletin of the World Health Organization , 2007, DOI: 10.1590/S0042-96862007000100010
Abstract: objective: to study patterns and determinants of hiv prevalence and risk-behaviour characteristics in different population groups in four border provinces of viet nam. methods: we surveyed four population groups during april-june 2002. we used stratified random-cluster sampling and collected data concomitantly on hiv status and risk behaviours. the groups included were female sex workers (n = 2023), injecting drug users (n = 1391), unmarried males aged 15-24 years (n = 1885) and different categories of mobile groups (n = 1923). findings: we found marked geographical contrasts in hiv prevalence, particularly among female sex workers (range 0-24%). the hiv prevalence among injecting drug users varied at high levels in all provinces (range 4-36%), whereas lower prevalences were found among both unmarried young men (range 0-1.3%) and mobile groups (range 0-2.5%). all groups reported sex with female sex workers. less than 40% of the female sex workers had used condoms consistently. the strongest determinants of hiv infection among female sex workers were inconsistent condom use (adjusted odds ratio [or], 5.3; 95% confidence interval [ci], 2.4-11.8), history of injecting drug use and mobility, and, among injecting drug users, sharing of injection equipment (adjusted or, 7.3; 95% ci, 2.3-24.0) and sex with non-regular partners (adjusted or 3.4; 95% ci 1.4-8.5). conclusion: the finding of marked geographical variation in hiv prevalence underscores the value of understanding local contexts in the prevention of hiv infection. although lacking support from data from all provinces, there would appear to be a potential for sex work to drive a self-sustaining heterosexual epidemic. that the close links to serious injecting drug use epidemics can have an accelerating effect in increasing the spread of hiv merits further study.
WHO Antiretroviral Therapy Guidelines 2010 and Impact of Tenofovir on Chronic Kidney Disease in Vietnamese HIV-Infected Patients
Daisuke Mizushima, Junko Tanuma, Fumihide Kanaya, Takeshi Nishijima, Hiroyuki Gatanaga, Nguyen Tien Lam, Nguyen Thi Hoai Dung, Nguyen Van Kinh, Yoshimi Kikuchi, Shinichi Oka
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079885
Abstract: Objective The 2010 WHO antiretroviral therapy (ART) guidelines have resulted in increased tenofovir use. Little is known about tenofovir-induced chronic kidney disease (CKD) in HIV-infected Vietnamese with mean body weight of 55 kg. We evaluated the prevalence and risk factors of CKD in this country. Design Cross-sectional study was performed. Methods Clinical data on HIV-infected Vietnamese cohort were collected twice a year. To evaluate the prevalence of CKD, serum creatinine was measured in 771 patients in October 2011 and April 2012. CKD was defined as creatinine clearance less than 60 ml/min at both time points. Multivariate logistic regression was used to determine the factors associated with CKD Results Tenofovir use increased in Vietnam from 11.9% in April 2011 to 40.3% in April 2012. CKD was diagnosed in 7.3%, of which 7% was considered moderate and 0.3% was severe. Multivariate analysis of October-2011 data identified age per year-increase (OR: 1.229, 95%CI, 1.170-1.291), body weight per 1 kg-decrement (1.286, 1.193-1.386), and tenofovir use (2.715, 1.028-7.168) as risk factors for CKD. Conclusions Older age, low body weight and tenofovir use were independent risk factors for CKD in Vietnam. Further longitudinal study is required to evaluate the impact of TDF on renal function in Vietnam and other countries with small-body weight patients.
Acute Measles Encephalitis in Partially Vaccinated Adults
Annette Fox, Than Manh Hung, Heiman Wertheim, Le Nguyen Minh Hoa, Angela Vincent, Bethan Lang, Patrick Waters, Nguyen Hong Ha, Nguyen Vu Trung, Jeremy Farrar, Nguyen Van Kinh, Peter Horby
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071671
Abstract: Background The pathogenesis of acute measles encephalitis (AME) is poorly understood. Treatment with immune-modulators is based on theories that post-infectious autoimmune responses cause demyelination. The clinical course and immunological parameters of AME were examined during an outbreak in Vietnam. Methods and Findings Fifteen measles IgM-positive patients with confusion or Glasgow Coma Scale (GCS) score below 13, and thirteen with uncomplicated measles were enrolled from 2008–2010. Standardized clinical exams were performed and blood collected for lymphocyte and measles- and auto-antibody analysis. The median age of AME patients was 21 years, similar to controls. Eleven reported receiving measles vaccination when aged one year. Confusion developed a median of 4 days after rash. Six patients had GCS <8 and four required mechanical ventilation. CSF showed pleocytosis (64%) and proteinorrhachia (71%) but measles virus RNA was not detected. MRI revealed bilateral lesions in the cerebellum and brain stem in some patients. Most received dexamethasone +/? IVIG within 4 days of admission but symptoms persisted for ≥3 weeks in five. The concentration of voltage gated calcium channel-complex-reactive antibodies was 900 pM in one patient, and declined to 609 pM ~ 3 months later. Measles-reactive IgG antibody avidity was high in AME patients born after vaccine coverage exceeded 50% (~ 25 years earlier). AME patients had low CD4 (218/μl, p = 0.029) and CD8 (200/μl, p = 0.012) T-cell counts compared to controls. Conclusion Young adults presenting with AME in Vietnam reported a history of one prior measles immunization, and those aged <25 years had high measles-reactive IgG avidity indicative of prior vaccination. This suggests that one-dose measles immunization is not sufficient to prevent AME in young adults and reinforces the importance of maintaining high coverage with a two-dose measles immunization schedule. Treatment with corticosteroids and IVIG is common practice, and should be assessed in randomized clinical trials.
Streptococcus suis, an Important Cause of Adult Bacterial Meningitis in Northern Vietnam
Heiman F. L. Wertheim, Huyen Nguyen Nguyen, Walter Taylor, Trinh Thi Minh Lien, Hoa Thi Ngo, Thai Quoc Nguyen, Bich Ngoc Thi Nguyen, Ha Hong Nguyen, Ha Minh Nguyen, Cap Trung Nguyen, Trinh Tuyet Dao, Trung Vu Nguyen, Annette Fox, Jeremy Farrar, Constance Schultsz, Hien Duc Nguyen, Kinh Van Nguyen, Peter Horby
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005973
Abstract: Background Streptococcus suis can cause severe systemic infection in adults exposed to infected pigs or after consumption of undercooked pig products. S. suis is often misdiagnosed, due to lack of awareness and improper testing. Here we report the first fifty cases diagnosed with S. suis infection in northern Viet Nam. Methodology/Principal Findings In 2007, diagnostics for S. suis were set up at a national hospital in Hanoi. That year there were 43 S. suis positive cerebrospinal fluid samples, of which S. suis could be cultured in 32 cases and 11 cases were only positive by PCR. Seven patients were blood culture positive for S. suis but CSF culture and PCR negative; making a total of 50 patients with laboratory confirmed S. suis infection in 2007. The number of S. suis cases peaked during the warmer months. Conclusions/Significance S. suis was commonly diagnosed as a cause of bacterial meningitis in adults in northern Viet Nam. In countries where there is intense and widespread exposure of humans to pigs, S. suis can be an important human pathogen.
Klebsiella pneumoniae Oropharyngeal Carriage in Rural and Urban Vietnam and the Effect of Alcohol Consumption
Trinh Tuyet Dao, Dror Liebenthal, Toan Khanh Tran, Bich Ngoc Thi Vu, Diep Ngoc Thi Nguyen, Huong Kieu Thi Tran, Chuc Kim Thi Nguyen, Huong Lan Thi Vu, Annette Fox, Peter Horby, Kinh Van Nguyen, Heiman F. L. Wertheim
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091999
Abstract: Introduction Community acquired K. pneumoniae pneumonia is still common in Asia and is reportedly associated with alcohol use. Oropharyngeal carriage of K. pneumoniae could potentially play a role in the pathogenesis of K. pneumoniae pneumonia. However, little is known regarding K. pneumoniae oropharyngeal carriage rates and risk factors. This population-based cross-sectional study explores the association of a variety of demographic and socioeconomic factors, as well as alcohol consumption with oropharyngeal carriage of K. pneumoniae in Vietnam. Methods and Findings 1029 subjects were selected randomly from age, sex, and urban and rural strata. An additional 613 adult men from a rural environment were recruited and analyzed separately to determine the effects of alcohol consumption. Demographic, socioeconomic, and oropharyngeal carriage data was acquired for each subject. The overall carriage rate of K. pneumoniae was 14.1% (145/1029, 95% CI 12.0%–16.2%). By stepwise logistic regression, K. pneumoniae carriage was found to be independently associated with age (OR 1.03, 95% CI 1.02–1.04), smoking (OR 1.9, 95% CI 1.3–2.9), rural living location (OR 1.6, 95% CI 1.1–2.4), and level of weekly alcohol consumption (OR 1.7, 95% CI 1.04–2.8). Conclusion Moderate to heavy weekly alcohol consumption, old age, smoking, and living in a rural location are all found to be associated with an increased risk of K. pneumoniae carriage in Vietnamese communities. Whether K. pneumoniae carriage is a risk factor for pneumonia needs to be elucidated.
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