Energy Consumption and Economic Growth: Evidence from Vietnam

The importance of non-renewable, renewable and sustainable energy sources and energy consumption in the economic development strategy of a country is undeniable. The purpose of the paper is to investigate the impacts of energy consumption on the economic growth of Vietnam during the 1980-2014 period. By applying the Autoregressive Distributed Lag (ARDL) model of Pesaran et al. (2001),

Effectiveness of cervical pessary compared to cervical cerclage with or without vaginal progesterone for the prevention of preterm birth in women with twin pregnancies and a short cervix : Study protocol for a two-by-two factorial randomised clinical trial

Peer reviewedPublisher PD

A physical model study on toe protection for sea dikes and revetments in Vietnam

Along 3,260-km coastline of Vietnam, there is a system of about 2,700-km sea dike. This system has an important role for the development of Vietnam. It protects densely concentrated population and industrial areas. However, in the storm season, there is usually some collapse in the sea dike system due to the strong impacts of wind wave and high sea water level. One of the reasons, which cause the dikes collapse, is that the toe protection loses its stability. The present research deals with the study of toe protection for sea dikes and revetments in Vietnam. In the present research, two dimension physical model tests were carried out to study the toe protection for sea dikes and revetments in Vietnam using typical data of water depth, wave climate and slope of revetments, etc. Experiments were carried out in a regular wave flume of the Laboratory of Fluid Mechanics Delft University of Technology. Wave-induced kinetic energy, which causes the movement of stones at the toe, was determined from the obtained velocities at different locations in front of the slope. Moreover, the study proposed a new concept on relative turbulent energy intensity to compare fluctuation between points and an assumption on an equivalent wave based on wave-induced kinetic energy equivalence to determine the stone size for bottom protection. The results of the experiments proved that the seabed (sand) would be totally eroded and lowered by strong wave-induced kinetic energy at nodes positions, the net flows and movement of nodes due to water level changes during a storm. The seabed is still eroded even if it was lowered. As a result, the toe protection loses its stability and the slope slides afterwards. Moreover, the study concluded that the equivalent wave height is equal to Hmax = (1+KR) H, where H is incoming wave height and KR is the reflection coefficient. Finally, an equation, which was also based on wave-induced kinetic energy equivalence, has been provided giving a good reliability to use for determining the stone size for bottom protection. For the safety of the sea dikes, the study recommended that, for the Vietnamese specification, there should be a requirement on slope (revetment) stability calculation in case there is a scour hole in front of the slope. A mattress made of available material like bamboo can be applied to keep the scour hole away from the toe. For preliminary design, the stones, which keep the mattress stable, can be determined by modified Shields curve with Hmax. Finally, the study recommended that the approach for determining the stone size based on the equivalent wave should be developed and applied in scale model research. A crest height of 7m +SWL complies with an allowable downtime of approximately 0.2%. The downtime costs are of considerable more influence than estimated by the port authority. Also the consequences of a breakwater collapse result in a 65% heavier element weight. The discounted total costs over the lifetime of the breakwater are 219 $million for the probabilistic design and 468$ million for the deterministic design. The collapse costs and downtime costs have a significant influence on the total costs over the lifetime and therefore on the economic optimal geometry of the breakwater. A more robust design than deterministically derived can reduce the total cost over the lifetime by almost 50%.Civil Engineering and Geoscience

Influence of velocity effects on the shape of N 2 (and air) broadened H 2O lines revisited with classical molecular dynamics simulations

The modeling of the shape of H 2O lines perturbed by N 2 (and air) using the Keilson-Storer (KS) kernel for collision-induced velocity changes is revisited with classical molecular dynamics simulations (CMDS). The latter have been performed for a large number of molecules starting from intermolecular-potential surfaces. Contrary to the assumption made in a previous study [H. Tran, D. Bermejo, J.-L. Domenech, P. Joubert, R. R. Gamache, and J.-M. Hartmann, J. Quant. Spectrosc. Radiat. Transf. 108, 126 (2007)]10.1016/j.jqsrt.2007.03.009, the results of these CMDS show that the velocity-orientation and -modulus changes statistically occur at the same time scale. This validates the use of a single memory parameter in the Keilson-Storer kernel to describe both the velocity-orientation and -modulus changes. The CMDS results also show that velocity- and rotational state-changing collisions are statistically partially correlated. A partially correlated speed-dependent Keilson-Storer model has thus been used to describe the line-shape. For this, the velocity changes KS kernel parameters have been directly determined from CMDS, while the speed-dependent broadening and shifting coefficients have been calculated with a semi-classical approach. Comparisons between calculated spectra and measurements of several lines of H 2O broadened by N 2 (and air) in the ν 3 and 2ν 1 ν 2 ν 3 bands for a wide range of pressure show very satisfactory agreement. The evolution of non-Voigt effects from Doppler to collisional regimes is also presented and discussed. © 2012 American Institute of Physics.Support of this research by the National Science Foundation (NSF) through Grant No. ATM-0803135; financial support from MICINN through Grant Nos. FIS2009-08069 and Consolider CSD00038.Peer Reviewe

Versatile Multilayer Metamaterial Nanoparticles with Tailored Optical Constants for Force and Torque Transduction

The ability to apply force and torque directly to micro- and nanoscale particles in optical traps has a wide range of applications. While full control of both force and torque in three dimensions has been realized using top-down fabrication of rod-shaped particles composed of birefringent crystalline materials, widespread usage of such particles is limited as the optical constants of the predominant birefringent materials (quartz SiO2 and rutile TiO2) preclude coverage of the full application space of optical trapping. Here, we show that multilayer metamaterial nanoparticles provide access to a wide range of optical constants that can be specifically tuned for each application. Selecting the material pair Nb2O5/SiO2 from the library of amorphous dielectrics as our metamaterial, we show that its refractive index and birefringence can be designed by adapting the ratio of layer thicknesses. Using a robust top-down fabrication process, we show that uniformly sized, free-floating Nb2O5/SiO2 particles with high birefringence at moderate refractive index are obtained at high yield. Using an optical torque wrench, we show that these particles function as joint force and torque transducers while maintaining excellent stability in aqueous solutions and can be controllably optimized for particular physical characteristics such as maximal torque transfer or rapid response time. We expect that such customizable birefringent metamaterial nanoparticles whose properties surpass those of conventional crystalline particles will provide a means to unleash the full potential of optical trapping applications. </p

Child Melioidosis Deaths Caused by Burkholderia pseudomallei–Contaminated Borehole Water, Vietnam, 2019

Within 8 months, 3 children from 1 family in northern Vietnam died from melioidosis. Burkholderia pseudomallei of the same sequence type, 541, was isolated from clinical samples, borehole water, and garden and rice field soil. Boreholes should be properly constructed and maintained to avoid B. pseudomallei contamination

Versatile Multilayer Metamaterial Nanoparticles with Tailored Optical Constants for Force and Torque Transduction

The ability to apply force and torque directly to micro- and nanoscale particles in optical traps has a wide range of applications. While full control of both force and torque in three dimensions has been realized using top-down fabrication of rod-shaped particles composed of birefringent crystalline materials, widespread usage of such particles is limited as the optical constants of the predominant birefringent materials (quartz SiO2 and rutile TiO2) preclude coverage of the full application space of optical trapping. Here, we show that multilayer metamaterial nanoparticles provide access to a wide range of optical constants that can be specifically tuned for each application. Selecting the material pair Nb2O5/SiO2 from the library of amorphous dielectrics as our metamaterial, we show that its refractive index and birefringence can be designed by adapting the ratio of layer thicknesses. Using a robust top-down fabrication process, we show that uniformly sized, free-floating Nb2O5/SiO2 particles with high birefringence at moderate refractive index are obtained at high yield. Using an optical torque wrench, we show that these particles function as joint force and torque transducers while maintaining excellent stability in aqueous solutions and can be controllably optimized for particular physical characteristics such as maximal torque transfer or rapid response time. We expect that such customizable birefringent metamaterial nanoparticles whose properties surpass those of conventional crystalline particles will provide a means to unleash the full potential of optical trapping applications. ImPhys/OpticsBN/Nynke Dekker La

Quantifying the Precision of Single-Molecule Torque and Twist Measurements Using Allan Variance

Single-molecule manipulation techniques have provided unprecedented insights into the structure, function, interactions, and mechanical properties of biological macromolecules. Recently, the single-molecule toolbox has been expanded by techniques that enable measurements of rotation and torque, such as the optical torque wrench (OTW) and several different implementations of magnetic (torque) tweezers. Although systematic analyses of the position and force precision of single-molecule techniques have attracted considerable attention, their angle and torque precision have been treated in much less detail. Here, we propose Allan deviation as a tool to systematically quantitate angle and torque precision in single-molecule measurements. We apply the Allan variance method to experimental data from our implementations of (electro)magnetic torque tweezers and an OTW and find that both approaches can achieve a torque precision better than 1 pN · nm. The OTW, capable of measuring torque on (sub)millisecond timescales, provides the best torque precision for measurement times ≲10 s, after which drift becomes a limiting factor. For longer measurement times, magnetic torque tweezers with their superior stability provide the best torque precision. Use of the Allan deviation enables critical assessments of the torque precision as a function of measurement time across different measurement modalities and provides a tool to optimize measurement protocols for a given instrument and application.Accepted Author ManuscriptBN/Nynke Dekker La