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Search Results: 1 - 10 of 37640 matches for " Nguyen Thanh; Van Kinh "
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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.

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.
Contact with Biological Parents for Children in Residental Care: A Vietnam Study  [PDF]
Nguyen Ba Dat, Nguyen Van Luot, Nguyen Ha Thanh
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.611021
Abstract: Children living in residential care have a degree of separation from their parents and other family members. Based on attachment theory, this study was conducted to analyze the contact between these children and their biological parents, and the factors affecting this contact. The sample included 382 children (orphans, abandoned or helpless children, children whose parents are deprived of custody or are unable to raise a child) living in residential centers located in North, Central and South of Vietnam. Data were obtained by semi-structured interviews. The results showed that, on average, children contact their parents and family members once a month. In addition, variables such as family image in children’s mind and joyfulness when meeting parents are the best predictors of contact between children and parents, family members. The contact between children and parents is arguably considered as a form of consolidation and maintenance of emotional relationship.
Mean Threshold and ARNN Algorithms for Identification of Eye Commands in an EEG-Controlled Wheelchair  [PDF]
Nguyen Thanh Hai, Nguyen Van Trung, Vo Van Toi
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B059

This paper represented Autoregressive Neural Network (ARNN) and meant threshold methods for recognizing eye movements for control of an electrical wheelchair using EEG technology. The eye movements such as eyes open, eyes blinks, glancing left and glancing right related to a few areas of human brain were investigated. A Hamming low pass filter was applied to remove noise and artifacts of the eye signals and to extract the frequency range of the measured signals. An autoregressive model was employed to produce coefficients containing features of the EEG eye signals. The coefficients obtained were inserted the input layer of a neural network model to classify the eye activities. In addition, a mean threshold algorithm was employed for classifying eye movements. Two methods were compared to find the better one for applying in the wheelchair control to follow users to reach the desired direction. Experimental results of controlling the wheelchair in the indoor environment illustrated the effectiveness of the proposed approaches.

The Optimal Stopping Time for Selling an Asset When It Is Uncertain Whether the Price Process Is Increasing or Decreasing When the Horizon Is Infinite  [PDF]
Nguyen Khac Minh, Nguyen Thanh Trung, Pham Van Khanh
American Journal of Operations Research (AJOR) , 2018, DOI: 10.4236/ajor.2018.82007
Abstract: Assume that we want to shell an asset with unknown drift but known that the drift is a two value random variable, and the initial distribution can be estimated. As time goes by, this distribution is updated and base on the probability of the drift takes the small one gives us the stopping rule. Research results show that the optimal strategy to sell the asset is if the initial probability that the drift receives a small value greater than a certain threshold then liquidates the asset immediately, otherwise the asset holder will wait until the probability of the drift receives a small value passing a certain threshold, it is the optimal time to liquidate the asset.
Loss to Followup in HIV-Infected Patients from Asia-Pacific Region: Results from TAHOD
Jialun Zhou,Junko Tanuma,Romanee Chaiwarith,Christopher K. C. Lee,Matthew G. Law,Nagalingeswaran Kumarasamy,Praphan Phanuphak,Yi-Ming A. Chen,Sasisopin Kiertiburanakul,Fujie Zhang,Saphonn Vonthanak,Rossana Ditangco,Sanjay Pujari,Jun Yong Choi,Tuti Parwati Merati,Evy Yunihastuti,Patrick C. K. Li,Adeeba Kamarulzaman,Van Kinh Nguyen,Thi Thanh Thuy Pham,Poh Lian Lim
AIDS Research and Treatment , 2012, DOI: 10.1155/2012/375217
Abstract: This study examined characteristics of HIV-infected patients in the TREAT Asia HIV Observational Database who were lost to follow-up (LTFU) from treatment and care. Time from last clinic visit to 31 March 2009 was analysed to determine the interval that best classified LTFU. Patients defined as LTFU were then categorised into permanently LTFU (never returned) and temporary LTFU (re-entered later), and these groups compared. A total of 3626 patients were included (71% male). No clinic visits for 180 days was the best-performing LTFU definition (sensitivity 90.6%, specificity 92.3%). During 7697 person-years of follow-up, 1648 episodes of LFTU were recorded (21.4 per 100-person-years). Patients LFTU were younger ( ), had HIV viral load ≥500?copies/mL or missing ( ), had shorter history of HIV infection ( ), and received no, single- or double-antiretroviral therapy, or a triple-drug regimen containing a protease inhibitor ( ). 48% of patients LTFU never returned. These patients were more likely to have low or missing haemoglobin ( ), missing recent HIV viral load ( ), negative hepatitis C test ( ), and previous temporary LTFU episodes ( ). Our analyses suggest that patients not seen at a clinic for 180 days are at high risk of permanent LTFU, and should be aggressively traced. 1. Introduction Loss to followup (LTFU) in patients receiving antiretroviral therapy can cause serious consequences such as discontinuation of treatment and increased risk of death [1–3]. At a program level, LTFU can make it difficult to evaluate outcomes of treatment and care [4, 5]. In resource-limited settings, where treatment has become rapidly available following the rollout of antiretroviral therapy, LTFU presents even more challenging obstacles that require special consideration and approaches [6, 7]. One of the key questions in patient followup is how to define a patient as LTFU. This has varied in studies conducted in different settings [8–10]. Defining LTFU using a very early threshold, for example, a patient with no clinic visit in the last three months, may result in many patients being considered as LTFU who would return to clinic naturally at a later date. Defining LTFU with a long threshold, for example, one year, may mean delaying too long before any effort is made to track patients potentially at risk of LTFU. The majority of research into LTFU in HIV-infected patients receiving antiretroviral treatment in resource-limited settings has been conducted in the sub-Saharan Africa region [3, 10–13]. A few studies have been conducted among Asian, mostly female, patients
Investigation the Dimensional Ratio Effect on the Resonant Properties of Piezoelectric Ceramic Disk  [PDF]
Vo Thanh Tung, Nguyen Trong Tinh, Truong Van Chuong, Nguyen Thi Mai H??ng, Dang Anh Tuan, Le Van Truyen
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.412202

In this work, the vibration characteristics of a piezoelectric ceramic disk with different dimensional ratio are studied by simulation method. Computational finite element modeling combined with the computational programs has allowed for the prediction of the effect, the change of diameter-to-thickness ratio on the resonant characteristics, the vibration modes as well as comparing the physic properties of piezoceramics. Three types of piezoelectric materials were chosen, piezoelectric materials (PZT) and Pb-free piezoelectric materials Ba(Zr0.2Ti0.8)O3-50(Ba0.7Ca0.3)TiO3(BZT-50BCT), BaTiO3 for research.

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
On the Interpretation of the 'Extra' Variables in the Hurwitz Transformation
Le Van Hoang,Nguyen Thanh Son
Physics , 2005,
Abstract: The Hurwits transformation is generalized by introducing three new variables called 'extra'. Interpretation of these extra variables allows us to establish relation between isotropic harmonic oscillator and five-dimensional hydrogen-like atom in 'electromagnetic' fields of various configurations. For the Schrodinger equations, the scheme of separation of extra variables is suggested.
The Factors Impact on Employee Satisfaction in Work at Vietnamese Garment Enterprises  [PDF]
Hoang Thanh Tung, Nguyen Thi Van Anh, Pham Thi Thuy Anh
Open Journal of Business and Management (OJBM) , 2019, DOI: 10.4236/ojbm.2019.72045
Abstract: This research is to identify and assess the factors that impact an employee’s satisfaction in work. The company selected for this research is a leading garment company of the Vietnamese textile and garment industry. With the survey and analyzing the opinion of 318 workers, the research results indicated six groups of elements (variables) in work which have impacted on the staff’s satisfaction: wages and welfare, working conditions, relations with superiors, relations with colleagues, training and promotion opportunities, nature of work. These six-factor groups were measured by 27 observed variables. The analysis and evaluation of factors affect the satisfaction of employees in order to contribute practically to the setting up and implementation of effective measures to enhance job satisfaction for employees, create motivate labor and bring the higher labor productivity.
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