Dong P.V.,Institute of Physics |
Long H.N.,Institute of Physics |
Hung H.T.,Hanoi University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012
We show that there is an infinite number of U(1) symmetries like Peccei-Quinn symmetry in the 3-3-1 model with minimal scalar sector-two scalar triplets. Moreover, all of them are completely broken due to the model's scalars by themselves (notice that these scalars as known to have been often used to break the gauge symmetry and to generate the masses for the model's particles). There is not any residual Peccei-Quinn symmetry. Because of the minimal scalar content, there are some quarks that are massless at tree level, but they can get consistent mass contributions at one loop due to this fact. Interestingly, axions as associated with the mentioned U(1)s breaking (including Majoron due to lepton-charge breaking) are all gauged away because they are also the Goldstone bosons responsible for the gauge symmetry breaking as usual. © 2012 American Physical Society.
Kim K.J.,MItsubishi Electric |
Duong T.Q.,Blekinge Institute of Technology |
Tran X.-N.,Hanoi University
IEEE Transactions on Signal Processing | Year: 2012
In this paper, we analyze the performance of cooperative spectrum sharing single-carrier (SC) relay systems. Taking into account the peak interference power at the primary user (PU) and the maximum transmit power at the secondary user (SU) network, two separate power allocation constraints are formed. For a two-hop decode-and-forward (DF) relaying protocol and two power allocation constraints, two relay selection schemes, namely, a full-channel state information (CSI)-based best relay selection (BRS) and a partial CSI-based best relay selection (PBRS), are proposed. The distributions of the end-to-end signal-to-noise ratios (e2e-SNRs) for the four cases are derived first, and then their outage probabilities and asymptotic outage probabilities are derived in closed-form. The derived asymptotic outage probabilities are utilized to see different diversity gains. Monte Carlo simulations have verified the derived diversity gains for the four different cases. We also present upper bounds on the ergodic capacities for two particular cases. © 2012 IEEE.
Luu D.-T.,CNRS Biochemistry and Plant Molecular Physiology Laboratory |
Luu D.-T.,Hanoi University |
Maurel C.,CNRS Biochemistry and Plant Molecular Physiology Laboratory
Traffic | Year: 2013
Aquaporins (AQPs) are channel proteins that facilitate the transport of water and small solutes across biological membranes. In plants, AQPs exhibit a high multiplicity of isoforms in relation to a high diversity of sub-cellular localizations, at the plasma membrane (PM) and in various intracellular compartments. Some members also exhibit a dual localization in distinct cell compartments, whereas others show polarized or domain-specific expression at the PM or tonoplast, respectively. A diversity of mechanisms controlling the routing of newly synthesized AQPs towards their destination membranes and involving diacidic motifs, phosphorylation or tetramer assembly is being uncovered. Recent approaches using single particle tracking, fluorescence correlation spectroscopy and fluorescence recovery after photobleaching have, in combination with pharmacological interference, stressed the peculiarities of AQP sub-cellular dynamics in environmentally challenging conditions. A role for clathrin and sterol-rich domains in cell surface dynamics and endocytosis of PM AQPs was uncovered. These recent advances provide deep insights into the cellular mechanisms of water transport regulation in plants. They also point to AQPs as an emerging model for studying the sub-cellular dynamics of plant membrane proteins. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Ngo L.T.,Hanoi University
IEEE International Conference on Fuzzy Systems | Year: 2013
The advances of nVIDIAs computing technology allow to deploy of general purpose high performance applications of Graphic Processing Units (GPU) by parallelizing algorithms. Based on the grid-based representation of T2FS, the paper deals with an approach to computational process of general type-2 fuzzy logic systems based on Grid T2FS for GPU platforms. Experiments are implemented in various applications to show that the representation are suitable to speed-up general type-2 fuzzy logic systems on GPU platform. © 2013 IEEE.
Tang T.D.,Hanoi University
CAD Computer Aided Design | Year: 2014
Five-axis CNC machine tools are more and more popular in machining area, because of their ability to machine parts with complex geometries efficiently as well as achieve higher dimensional accuracy. Since two additional rotational axes are introduced in five-axis machines, there are difficult geometric problems that need to be solved in order to take full advantages of five-axis machining, and the most complex problems are collision detection and avoidance. Due to its widespread importance, a lot of researches have been carried out to solve the collision detection and avoidance problems. These include the surface properties analysis based method, convex hull based method, C-space based method, accessibility based method, bounding volume and space partition method, distance calculation (vector) based method, rolling ball method, radial projection method, graphic-assisted method, and sweep plane approach. This paper aims at providing a state of the art review on algorithms for collision detection and avoidance in five-axis NC machining. In addition, a comparison of algorithms for collision detection and avoidance is considered. © 2014 Elsevier Ltd. All rights reserved.
Dong P.V.,Vietnam Academy of Science and Technology |
Tham T.D.,Vietnam Academy of Science and Technology |
Hung H.T.,Hanoi University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
We show that the SU(3)CâŠ - SU(3) LâŠ - U(1)X (3-3-1) model of strong and electroweak interactions can naturally accommodate an extra U(1)N symmetry behaving as a gauge symmetry. The resulting theory based on SU(3) CâŠ - SU(3)LâŠ - U(1) XâŠ - U(1)N (3-3-1-1) gauge symmetry realizes B-L=-(2/√3)T8+N as a charge of SU(3)Lâ Š - U(1)N. Consequently, a residual symmetry, W parity, resulting from broken B-L, similarly to R-parity in supersymmetry, is always conserved and may be unbroken. There is a specific fermion content recently studied in which all new particles that have wrong lepton numbers are odd under W parity, while the standard model particles are even. Therefore, the lightest wrong-lepton particle (LWP) responsible for dark matter is naturally stabilized. We explicitly show that the non-Hermitian neutral gauge boson (X0) as the LWP cannot be dark matter. However, the LWP as a new neutral fermion (NR) can be dark matter if its mass is in the range 1.9 TeV≤mNR≤2.5 TeV, provided that the new neutral gauge boson (Z′) mass satisfies 2.2 TeV≤mZ′≤2.5 TeV. Moreover, the scalar dark matter candidate (H′â‰η3) that has traditionally been studied is only stabilized by W parity. All the unwanted interactions and vacuums that are often encountered in the 3-3-1 model are naturally suppressed. And, the standing issues on tree-level flavor changing neutral currents and CPT violation also disappear. © 2013 American Physical Society.
Van Hieu N.,Hanoi University
Sensors and Actuators, B: Chemical | Year: 2010
A truly simple procedure was presented for highly reproducible synthesis of very large-scale SnO2 nanowires (NWs) on silicon and alumina substrates. The growth involves thermally evaporating SnO powder in a tube furnace with temperature, pressure, and O2 gas-flow controlled to 960 °C, 0.5-5 Torr, and 0.4-0.6 sccm, respectively. The scanning- and transmission-electron-microscopic studies show that the diameter and length of the nanowires vary from 50 to 150 nm and 1 to 10 μm, respectively. As-synthesized SnO2 NWs on alumina substrates were used to fabricate gas sensor by screen-printing method. A good ohmic contact of the screen-printed NWs sensor was obtained. Randomly selected gas-sensor devices were tested with various gases such as C2H5OH, CH3COCH3, C3H8, CO, and H2 for studying gas-sensing properties. The results reveal that as-fabricated sensors exhibit relatively reproducible and good response to ethanol gas. Typically, the response to 100 ppm ethanol in air is around 11.8, and response and recovery times are around 4 and 30 s, respectively. © 2009 Elsevier B.V. All rights reserved.
Nguyen H.H.,Hanoi University
Journal of Plastic, Reconstructive and Aesthetic Surgery | Year: 2012
Background: Total scalp avulsion is a rare and devastating event. Microsurgical replantation is the sole method to achieve an ideal cosmetic outcome. In the literature, most studies have reviewed limited sample sizes. Most authors report better outcomes when a greater number of microvascular anastomoses are used. This strategy remains controversial, as some authors have suggested that one artery may be sufficient. Methods: From 2005 to 2008, seven patients who sustained scalp avulsion underwent microsurgical replantation. All of the vascular anastomoses were made with a branch of the superficial temporal artery. We did not use vein grafts. The ischaemia time was 4-16 h. Results: In six cases, a single artery and one to two veins were anastomosed; in another case, two arteries and three veins were anastomosed. Six of the seven scalp replantations were successful and achieved normal hair regrowth. In five of the six successful cases, we performed a single-artery anastomosis. Conclusion: Scalp avulsion is rare around the world but occurs relatively frequently in our country due to the lack of safe and secure working conditions in agriculture and industry. In cases where multiple arterial anastomoses are not possible, the present findings suggest that one branch of the superficial temporal artery may be sufficient to reperfuse the replanted scalp and achieve excellent aesthetic results. © 2012 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.
McNaughton D.,Flinders University |
Duong T.T.H.,Hanoi University
PLoS Neglected Tropical Diseases | Year: 2014
Background:The Wolbachia strategy aims to manipulate mosquito populations to make them incapable of transmitting dengue viruses between people. To test its efficacy, this strategy requires field trials. Public consultation and engagement are recognized as critical to the future success of these programs, but questions remain regarding how to proceed. This paper reports on a case study where social research was used to design a community engagement framework for a new dengue control method, at a potential release site in central Vietnam.Methodology/Principal Findings:The approach described here, draws on an anthropological methodology and uses both qualitative and quantitative methods to design an engagement framework tailored to the concerns, expectations, and socio-political setting of a potential trial release site for Wolbachia-infected Aedes aegypti mosquitoes. The process, research activities, key findings and how these were responded to are described. Safety of the method to humans and the environment was the most common and significant concern, followed by efficacy and impact on local lives. Residents expected to be fully informed and engaged about the science, the project, its safety, the release and who would be responsible should something go wrong. They desired a level of engagement that included regular updates and authorization from government and at least one member of every household at the release site.Conclusions/Significance:Results demonstrate that social research can provide important and reliable insights into public concerns and expectations at a potential release site, as well as guidance on how these might be addressed. Findings support the argument that using research to develop more targeted, engagement frameworks can lead to more sensitive, thorough, culturally comprehensible and therefore ethical consultation processes. This approach has now been used successfully to seek public input and eventually support for releases Wolbachia-infected mosquitoes, in two different international settings - Australia and Vietnam. © 2014 McNaughton, Duong.
Nga T.T.,Hanoi University
BMC pharmacology & toxicology | Year: 2014
The irrational overuse of antibiotics should be minimized as it drives the development of antibiotic resistance, but changing these practices is challenging. A better understanding is needed of practices and economic incentives for antibiotic dispensing in order to design effective interventions to reduce inappropriate antibiotic use. Here we report on both quantitative and qualitative aspects of antibiotic sales in private pharmacies in northern Vietnam. A cross-sectional study was conducted in which all drug sales were observed and recorded for three consecutive days at thirty private pharmacies, 15 urban and 15 rural, in the Hanoi region in 2010. The proportion of antibiotics to total drug sales was assessed and the revenue was calculated for rural and urban settings. Pharmacists and drug sellers were interviewed by a semi-structured questionnaire and in-depth interviews to understand the incentive structure of antibiotic dispensing. In total 2953 drug sale transactions (2083 urban and 870 rural) were observed. Antibiotics contributed 24% and 18% to the total revenue of pharmacies in urban and rural, respectively. Most antibiotics were sold without a prescription: 88% in urban and 91% in rural pharmacies. The most frequent reported reason for buying antibiotics was cough in the urban setting (32%) and fever in the rural area (22%). Consumers commonly requested antibiotics without having a prescription: 50% in urban and 28% in rural area. The qualitative data revealed that drug sellers and customer's knowledge of antibiotics and antibiotic resistance were low, particularly in rural area. Over the counter sales of antibiotic without a prescription remains a major problem in Vietnam. Suggested areas of improvement are enforcement of regulations and pricing policies and educational programs to increase the knowledge of drug sellers as well as to increase community awareness to reduce demand-side pressure for drug sellers to dispense antibiotics inappropriately.