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Abstract The authors deal with the problem of the design and manufacture of a high‐resolution FMCW radar for drone detection and classification. The difficulties of the problem are discrete clutter reduction and spurious phase noise mitigation. The discrete clutter is due to the reflected signals from land vehicles, birds etc., while the spurious phase noise is inherent in the radar signal due to the phase‐locked loop component and leakage between the transmitting and receiving paths. Both spurious phase noise and clutter will increase the system noise level and hence reduce the probability of detection of small targets such as drones and induce false alarms on the radar screen. In order to reduce discrete clutter, the authors propose a method to separate a drone from discrete clutter based on the design of the radar system parameters for a drone and its propeller detection, target's Doppler dispersion and moving characteristics. For spur mitigation, a method that focuses on the design of the isolation coefficient between transmitting and receiving paths to decrease the power of spurs below the minimum power requirement at the input of the analogue‐to‐digital converter is introduced. The results were applied by the authors to the development and manufacture of a radar with the given specifications for drone detection and classification. Different laboratory and field tests show that the spurs are mitigated and the drones are separated from discrete clutter with a range and accuracy better than the one recently published.

Physical layer secret key generation is a novel research direction that has attracted many researchers in recent years due to its low computational capacity and ability to obtain information-theoretic security. In this paper, we propose two methods based on the modulus and the real and imaginary parts of the channel impulse response (CIR) matrix to generate a secret key between two legitimate devices in massive Multiple-Input Multiple-Output (MIMO) wireless communication systems. For these methods, the legitimate devices first estimate the channel by using a probing signal to find their CIRs. Next, the CIR matrices are transformed into single-row vectors. The first method uses a simple quantization algorithm to convert the modulus of the complex components of the vector into the final key bit sequence. The second method uses the same quantization algorithm to transform the highest points of the real and imaginary parts into two sequences. The XOR operation between these two sequences generates the final key sequence. The key samples with different lengths generated from the system can be assessed by the most crucial performance metric of randomness according to the National Institute of Standards and Technology (NIST) version 800-22REV1A. The numerical results show that the first method has a higher pass rate and more randomness than the second method. Moreover, our proposed methods are superior to existing methods.

Monitoring oil drift by integrating multi-source satellite imagery has been a relatively underexplored practice due to the limited time-sampling of datasets. However, this limitation has been mitigated by the emergence of new satellite constellations equipped with both Synthetic Aperture Radar (SAR) and optical sensors. In this manuscript, we take advantage of multi-temporal and multi-source satellite imagery, incorporating SAR (Sentinel-1 and ICEYE-X) and optical data (Sentinel-2/3 and Landsat-8/9), to provide insights into the spatio-temporal variations of oil spills. We also analyze the impact of met–ocean conditions on oil drift, focusing on two specific scenarios: marine floating oil slicks off the coast of Qatar and oil spills resulting from a shipwreck off the coast of Mauritius. By overlaying oils detected from various sources, we observe their short-term and long-term evolution. Our analysis highlights the finding that changes in oil structure and size are influenced by strong surface winds, while surface currents predominantly affect the spread of oil spills. Moreover, to detect oil slicks across different datasets, we propose an innovative unsupervised algorithm that combines a Bayesian approach used to detect oil and look-alike objects with an oil contours approach distinguishing oil from look-alikes. This algorithm can be applied to both SAR and optical data, and the results demonstrate its ability to accurately identify oil slicks, even in the presence of oil look-alikes and under varying met–ocean conditions.

Nowadays, laser cutting technology stands as one of the most cutting-edge technologies. Not only do laser cutting machines play a crucial role in the mechanical engineering industry, but also in numerous other industries including electronic circuit manufacturing, garment manufacturing, and particularly in the handicraft industry. This study presents a methodology for the design and production of laser cutting machines in Vietnam. A laser cutting machine has been successfully constructed, featuring a straightforward configuration, user-friendly operation, and low cost. The machine has the ability to perform laser cutting on wooden materials, achieving a cutting depth ranging from 1 to 2 mm. The proposed laser cutting machine prototype can cut at a speed of 1000 mm/min, thus meeting the specified requirements.

The present paper investigates the impact of pairing correlation on the nuclear level density (NLD) and radiative strength function (RSF) of an odd-odd and rare-earth 166Ho nucleus. By employing the exact thermal pairing (EP) solution in conjunction with both the temperature-dependent independent-particle model (EP+IPM) for the NLD and the phonon damping model (EP+PDM) for the RSF, we achieve good agreement with the experimental NLD and RSF data, which have been recently extracted by using the Oslo method. Notably, without adding any extra parameters, our calculations successfully reproduce the pygmy dipole resonances (PDR) and a portion of the strength around the region of scissor resonance (SR) in the RSF. This suggests that the SR in this nucleus may be less pronounced than that obtained in the previous analysis within the phenomenological model. These features are the consequences of the EP and the couplings of the PDM phonon to all the particle-hole (ph), particle-particle (pp), and hole-hole (hh) configurations within the EP+PDM, thus insisting on the importance of the underlying physics involved in this model. Utilizing the obtained NLD and RSF, we predict the 165Ho(n,γ)166Ho and Maxwellian-averaged cross sections, which exhibit remarkable agreement with all the available experimental data from the Experimental Nuclear Reaction Data and Karlsruhe Astrophysical Database of Nucleosynthesis in Stars. These results reflect the imprint of the pairing correlation on those quantities.

This paper shows the observation and estimation of convective wind gusts by different satellite sensors at the C-band (Sentinel-1 SAR) and L-band (ALOS-1 SAR and SMAP radiometer) over Lake Victoria, the Gulf of Guinea, and the Gulf of Mexico. These areas are significantly impacted by deep convection associated with strong surface winds and heavy rainfall. In particular, the collocation of Sentinel-1 and SMAP images enables the observation of the movement of surface wind gusts corresponding to that of deep convective clouds. The convective wind intensity estimated from Sentinel-1 and SMAP data varies from 10 to 25 m/s. Additionally, we present an agreement in the observation of deep convective clouds, dynamics, and strong surface winds by different satellite sensors, including Meteosat geostationary (GEO), Aeolus Lidar, and Sentinel-1 SAR, respectively. We also evaluate the estimated convective wind gusts by comparison with the in situ measurements of the weather stations installed in the Gulf of Mexico, where deep convection occurs regularly. The result shows an agreement between the two wind sources estimated and measured. Likewise, the peaks of the measured wind gusts correspond to the occurrence of deep convective clouds observed by the GOES-16 GEO satellite.

Background: Unilateral biportal endoscopic (UBE) surgery for the treatment of lumbar disc herniation (LDH) has been growing rapidly for a relatively short period of time. This minimally invasive surgical technique has achieved favorable results in some developed countries. In the present study, we reported the preliminary outcomes of patients with LDH treated with UBE discectomy in a limited resources institution. Methods: Clinical and radiographic data of 46 patients of LDH treated between July 2022 and March 2023 using UBE discectomy techniques including ipsilateral interlaminar approach, contralateral sublaminar approach and paraspinal approach, were reviewed. Outcomes were analyzed in view of modified-Macnab criteria, Japanese Orthopedic Association score (JOA), Visual analog scale (VAS) with a mean follow-up of 3.1 months. Results: At the final follow-up, the mean VAS for low back pain was improved from 4.2 ± 1.1 to 1.4 ± 0.3 and VAS for leg pain was improved from 7.9 ± 1.2 to 2.6 ± 0.4. The mean JOA score improved from 13.8 ± 5.2 to 24.4 ± 4.3. Modified Macnab criteria were excellent in 30 patients (65.3 %), good in 14 (30.4 %), fair in 2 (4.3 %). A total of 57 levels of LDH were done. L4-L5 disc herniation was performed in 30 patients (52.6 %), L5-S1 in 20 (35.1 %), L2-L3 in 4 (7.0 %), and L3-L4 in 3 (5.3 %). Ipsilateral approach technique was performed at 48 patients (84.2 %), contralateral sublaminar approach in 7 (12.3 %), and paraspinal approach in 2 (3.5 %). Complications included 2 patients with dural tears (4.3 %), and 1 epidural hematoma (2.2 %). Conclusions: UBE discectomy techniques may be performed safely and effectively for the treatment of LDH in limited resources hospitals.

Camellia sinensis var. madoensis is described and illustrated as a new variety of Camellia sinensis (section Thea, Theaceae) from Xuan Loc Commune, Song Cau District, Phu Yen Province. The new variety is easily distinguishable from C. sinensis var. sinensis by style free ½ to the base. The ITS sequence of this variety is also different from that of Camellia sinensis and its other varieties, while the matK gene sequences are nearly identical among Camellia taxa.

The purpose of this study was to determine new leadership styles in the context of the level of development of the Vietnamese economy in the last years and what is likely to happen in the next 10 years or more. Another aim was to create the combination of leadership best thinking that will enable Vietnamese leaders to adapt successfully in the implementation of the fourth industrial revolution (4IR) in Vietnam. The 4IR is fundamentally different because it involves the fusion of a range of new technologies that link the physical, digital and biological worlds, impacting all disciplines, economies, and industries. Transformational analysis in combination with documents review, in-depth interviews with Delphi technique in VUCA (Volatile, Uncertain, Complex and Ambiguous) environment with 64 top government leaders, researchers, and scholars. including hi-tech enterprises conducted to see the major characteristics and skills that a leader needs in the digitalization ages in the digitalization age. The study results were that there are five models of leadership in 4IR best practices: traditional leadership, transformational leadership, agile leadership, block-chain leadership, and human values and ethics. The principal conclusion was that the more resilience Vietnam is ready, the more successful Vietnam will achieve beyond the 4IR.

Abstract Proactive Fault tolerant (FT) approaches for infrastructure's cloud computing which have been increasingly developed in research scope with the support of machine learning need consistent monitoring and highly accurate predicting systems. However, it is difficult to implement the proactive fault tolerant approach of infrastructure's cloud computing because of complex architecture, dynamic services, and many interdependent factors existing in cloud environment. To overcome this problem, a proactive FT approach for cloud‐hosted application is proposed to achieve a high degree of automation, including physical machine (PM) fault analysis and self‐learning virtual machine (VM) migration. It is based on MAPE‐K (Monitor‐Analyze‐Plan‐Execute over a shared Knowledge) loop to take into account the knowledge inside controllers in run time. To evaluate PM fault analysis model, the web e‐Commerce is deployed by OpenStack Stein while the prototype of VM migration component is built by CloudSim for VM migration solution evaluation. The effectiveness of the approach is demonstrated in experiment results.

The study presents a design alternative, simulates the operation, and analyzes the new structure of the 6 DOF robot arm. The proposed robot model is based on reference shapes from AR3 robot arm, with modifications to details and structures to accommodate the actual and economic circumstances in Vietnam. Solidwork software was first utilized for the arm structure's design, strength testing, and optimization. The material is chosen with the goal of reducing production cost and ensuring the robot's operation properly. The study concludes by applying the topology optimization algorithm to a machine component to determine the optimal structure of the robot arm. To validating the design results, the prototype is manufacturers using CNC machine. The experimental results show the robot arm basic functions effectively. This research could be used as references for designing and manufacturing a 6 DOF robot arm with relative robot's structure.

Strong ocean surface mean and gust winds associated with deep convection can cause significant damages. It is hard to estimate surface convective wind gusts since they may occur suddenly and become intense quickly. This problem is even more challenging for tropical and subtropical regions over which convection is particularly intense while one has little in situ and remote sensing data. This article presents the collocation of several low-earth orbit (LEO) acquired data sources to observe and estimate ocean surface convective winds. The LEO devices include Sentinel-1 synthetic aperture radar (SAR), ASCAT-A/B/C scatterometers, Windsat, and SMAP radiometers. This combination enables the short- and long-term observations of ocean wind pattern variabilities, for instance, a mesoscale squall line and a submesoscale wind cell. Sentinel-1 data can offer convective wind gust estimates at a high spatial resolution, whereas the other sources (SMAP, Windsat, and ASCAT-A/B/C) only estimate wind gusts at a scale larger than 0.25° grid. Also, thanks to the LEO data collocation, one can observe the displacement direction of surface wind patterns and their intensity variabilities (15–25 m/s). Surface wind patterns move according to the horizontal displacement of deep convective clouds aloft observed by the Meteosat geostationary satellite. Likewise, the wind intensity variability and deep cloud brightness temperature evolve accordingly. Using simultaneous rainfall and wind speed measurements from Windsat, this study showed that the high-intensity radar backscattering from C-band Sentinel-1 SAR data is mainly induced by convective winds rather than precipitation.

Bats are a major reservoir of zoonotic viruses, including coronaviruses. Since the emergence of SARS-CoV in 2002/2003 in Asia, important efforts have been made to describe the diversity of Coronaviridae circulating in bats worldwide, leading to the discovery of the precursors of epidemic and pandemic sarbecoviruses in horseshoe bats. We investigated the viral communities infecting horseshoe bats living in Northern Vietnam, and report here the first identification of sarbecoviruses in Rhinolophus thomasi and Rhinolophus siamensis bats. Phylogenetic characterization of seven strains of Vietnamese sarbecoviruses identified at least three clusters of viruses. Recombination and cross-species transmission between bats seemed to constitute major drivers of virus evolution. Vietnamese sarbecoviruses were mainly enteric, therefore constituting a risk of spillover for guano collectors or people visiting caves. To evaluate the zoonotic potential of these viruses, we analyzed in silico and in vitro the ability of their RBDs to bind to mammalian ACE2s and concluded that these viruses are likely restricted to their bat hosts. The workflow applied here to characterize the spillover potential of novel sarbecoviruses is of major interest for each time a new virus is discovered, in order to concentrate surveillance efforts on high-risk interfaces.

The smart environmental management system proposed in this work offers a new approach to environmental monitoring by utilizing data from IoT stations and MODIS satellite imagery. The system is designed to be deployed in vast regions, such as the Mekong Delta, with low building and operating costs, making it a cost-effective solution for environmental monitoring. The system leverages telemetry data collected by IoT stations in combination with MODIS MOD09GA, MOD11A1, and MCD19A2 daily image products to develop computational models that calculate the values land surface temperature (LST), 2.5 and 10 (µm) particulate matter mass concentrations (PM2.5 and PM10) in areas without IoT stations. The MOD09GA product provides land surface spectral reflectance from visible to shortwave infrared wavelengths to determine land cover types. The MOD11A1 product provides thermal infrared emission from the land surface to compute LST. The MCD19A2 product provides aerosol optical depth values to detect the presence of atmospheric aerosols, e.g., PM2.5 and PM10. The collected data, including remote sensing images and telemetry sensor data, are preprocessed to eliminate redundancy and stored in cloud storage services for further processing. This allows for automatic retrieval and computation of the data by the smart data processing engine, which is designed to process various data types including images and videos from cameras and drones. The calculated values are then made available through a graphic user interface (GUI) that can be accessed through both desktop and mobile devices. The GUI provides real-time visualization of the monitoring values, as well as alerts to administrators based on predetermined rules and values of the data. This allows administrators to easily monitor the system, configure the system by setting alerting rules or calibrating the ground stations, and take appropriate action in response to alerts. Experimental results from the implementation of the system in Dong Thap Province in the Mekong Delta show that the linear regression models for PM2.5 and PM10 estimations from MCD19A2 AOD values have correlation coefficients of 0.81 and 0.68, and RMSEs of 4.11 and 5.74 µg/m3, respectively. Computed LST values from MOD09GA and MOD11A1 reflectance and emission data have a correlation coefficient of 0.82 with ground measurements of air temperature. These errors are comparable to other models reported in similar regions in the literature, demonstrating the effectiveness and accuracy of the proposed system.

The Culex vishnui subgroups, particularly Culex tritaeniorhynchus, are considered the primary vectors of the Japanese encephalitis virus (JEV) in Asia. Recent molecular phylogenetic analyses of JEV isolates from Asian countries have shown that JEVs with diverse genetic variants are present in Asia. Furthermore, some JEV strains have been found to have crossed the East China Sea and been introduced into Japan. In this study, the possibility of overseas migration of the JE vector mosquito, Cx. tritaeniorhynchus was examined from the genetic, physical, and meteorological perspectives. Molecular phylogenetic analysis was performed based on both whole coding sequences and on the barcoding region of the mitochondrial cytochrome c oxidase subunit I (COI) gene of Cx. vishnui subgroups collected from Asian countries. Culex tritaeniorhymchus was classified into two genetically independent taxa by COI sequences: the Japanese type (Ct-J), which inhabits Japan except for the Amami Islands of southern Japan, and the continental type (Ct-C), which inhabits the Asian region except for Japan. It was confirmed that approximately 10% of Cx. tritaeniorhynchus trapped during the summer in western Kyushu were Ct-C, and that they could fly for up to 38 h continuously. The meteorological analysis also confirmed that the atmospheric flow occurring over the continent coincided with the date of Ct-C capture. This is the first report showing the existence of two taxa in Cx. tritaeniorhynchus. Their physical and physiological characteristics suggest the possibility of long-distance migration from overseas regions to Japan across the East China Sea. Future efforts are expected to provide evidence to support the occurrence of long-distance migration of Cx. tritaeniorhynchus with JEV.

How do universities encourage academics to buy into a shared vision while often setting punitive targets in teaching and research? This article explores possible antecedents of a university's shared vision and its relationships with academics' research and teaching performance in the era of managerialism. This cross-country study of two large universities in the UK and Vietnam draws on data from multiple sources to uncover the key components of a university's shared vision. A survey strategy was adopted. Data were collected from different sources, using a stratified random sampling technique from academics of different schools at those universities. A total of 431 survey responses from academics at these universities were included for analysis, employing structure equation modelling. It provides fresh insights into whether having a shared vision can benefit academics' research and teaching performance. The findings of this study show that while achieving a high degree of shared vision may enhance research performance, it may do little to improve teaching performance. The study provides empirical evidence indicating that a shared vision emerges as strongly rooted within individual employees rather than managers, challenging the common belief that a shared vision emanates primarily from the top down. This article advances social exchange theory (SET) by showing the interdependence of workplace antecedents, personal attributes, interpersonal connections, and performance. It introduces a framework for the relationship between universities' shared vision with its possible antecedents and with academics' teaching performance and research performance. The article also discusses useful implications for higher education leaders, based on the findings of the study.

The combination of low earth orbit (LEO) and GEO stationary (GEO) satellites brings significant advantages to observe, monitor, and understand convective systems and the associated vertical and horizontal dynamics. Two LEO, C-band Sentinel-1 synthetic aperture radar and L-band soil moisture active passive (SMAP) radiometer, are used to observe surface wind patterns, while the other LEO (Aeolus lidar instrument) offers the measurements of intense convective downdrafts. Meteosat GEO is used to detect deep convective clouds. Four case study examples of LEO and GEO combination illustrate here the matching in location and observation time between deep convective clouds, intense downdrafts, and strong surface wind gusts. In particular, the two-dimensional deep convective cloud patterns and surface wind patterns have the same direction displacement. The observations of surface wind patterns by two different LEO (Sentinel-1 and SMAP) indicate that the high-intensity radar backscattering on Sentinel-1 images should be induced by convective wind gusts rather than hydrometeors or convective precipitation at the sea surface as suggested in previous references. Finally, the convective wind gusts estimated from Sentinel-1 and SMAP data correspond to those obtained by the high-frequency radars, small-scale numerical models, and in-situ measurements.

Virtual machines migration is an essential feature of virtualisation technology which brings many advantages in cloud computing management process such as proactive fault tolerance, load balancing, and power management. There have been many virtual migration algorithms that have been developed but it is hard to find one that best suits all applications as well as ensures the desire of all stakeholders. The optimal virtual machines migration of cloud computing is usually NP‐hard or NP‐complete. In addition, determining when virtual machines migrate is a challenge because of the difficulty of fault detection in cloud computing. In this study, the authors propose a virtual machines migration game approach for multi‐tier application in infrastructure‐as‐a‐service cloud computing where they first proposed fault detection model based on Takagi–Sugeno fuzzy system with metric's physical machines and then optimal or near optimal migration solution is approximated based on Nash equilibrium. The results of experiment demonstrate the efficiency of their proposal. The proposed virtual machines migration algorithm has been benchmarked in order to highlight their strength and feasibility.

Modern badminton training machines, which circumvents the requirement of two opposing players for conducting a match, are either expensive or has complex operation. This research involved the prototyping of a shuttlecock robot that enables a badminton player to practice independently. First, a three-dimensional model of the badminton robot was designed. Subsequently, the dynamics of the mechanism were evaluated. Next, the hardware was designed using MATLAB. Finally, the trajectory of the badminton shuttlecock was determined using a series of experimental tests. The as-developed product was reliable and stable, enabling badminton players to practice independently. Moreover, the designed robot can be manufactured at a lower cost than similar machines developed in other studies.

Antibiotic has frequently been used in the shrimp-farming process in Vietnam. This leads to the status that antibiotic-resistant bacteria and products do not receive in the market. Bacteria had the resistant ability to pathogenic bacteria in water, and they have an important role in sustainable aquaculture. This study aimed to isolate and select good bacterial strains against Vibrio parahaemolyticus, pathogenic bacteria, on shrimp from 8 samples of shrimp pond water at 3 villages Ngu Lac, Phuoc An and Long Toan of Duyen Hai district, Tra Vinh province on NB agar medium. As a result, fifty-nine bacterial isolates were isolated and 10/59 isolates (16.95%) were identified as resistant to Vibrio parahaemolyticus by the well diffusion method. In 10 isolates, there were 7 isolates had good resistance to select for PCR technique and sequencing. The result indicated that these seven strains, including DH1m, DH2f, DH4d, DH8i, DH8m, DH8n, belonged to Bacilli and DH1n strain belonged to Streptomyces sp.

The epidemiology of typhoid fever in Lao People`s Democratic Republic is poorly defined. Estimating the burden of typhoid fever in endemic countries is complex due to the cost and limitations of population-based surveillance; serological approaches may be a more cost-effective alternative. ELISAs were performed on 937 serum samples (317 children and 620 adults) from across Lao PDR to measure IgG antibody titers against Vi polysaccharide and the experimental protein antigens, CdtB and HlyE. We measured the significance of the differences between antibody titers in adults and children and fitted models to assess the relationship between age and antibody titers. The median IgG titres of both anti-HylE and CdtB were significantly higher in children compared to adults (anti-HylE; 351.7 ELISA Units (EU) vs 198.1 EU, respectively; p

Abstract Background Dementia poses a serious threat to the wellbeing of the elderly. In the context of the rapidly ageing population of Vietnam however, little is known about the prevalence of symptoms and other related factors. This study aims to detect the prevalence of cognitive symptoms of dementia in the elderly in Vietnam as well as other associated factors. Methods A cross-sectional study was conducted over a period of six communes at the Northern, Central and Southern region of Vietnam. Prevalence of cognitive symptoms of dementia was the outcome of interest and assessed by Mini Mental State Evaluation (MMSE) questionnaire and was standardized according to the age structure of Vietnam. A total of 3308 adults aged 60 and above were included. Association between having cognitive symptoms of dementia and other factors was assessed with logistic regression. Findings Cognitive symptoms of dementia were perceived in 46.4% of the sample group. The symptoms were more common among participants who were older, female, had a lower educational level, were not physically active or have previously had stroke. Conclusions Prevalence of cognitive symptoms of dementia in adults aged 60 and above was relatively high in Vietnam. Other modifiable associated factors including physical inactivity and social connectedness should also be considered in designing intervention program to prevent dementia in the future.

Globally, cities are growing rapidly in size and density and this has caused profound impacts on urban forest ecosystems. Urbanization requiring deforestation reduces ecosystem services that benefit both city dwellers and biodiversity. Understanding spatial and temporal patterns of vegetation changes associated with urbanization is thus a vital component of future sustainable urban development. We used Landsat time series data for three decades from 1988 to 2018 to characterize changes in vegetation cover and habitat connectivity in the Perth Metropolitan Area, in a rapidly urbanising Australian biodiversity hotspot, as a case study to understand the impacts of urbanization on urban forests. Moreover, as golf courses are a major component in urban areas, we assessed the role of golf courses in maintaining vegetation cover and creating habitat connectivity. To do this we employed (1) land use classification with post-classification change detection, and (2) Morphological Spatial Pattern Analysis (MSPA). Over 17,000 ha of vegetation were cleared and the area of vegetation contributing to biodiversity connectivity was reduced significantly over the three decades. The spatial patterns of vegetation loss and gain were different in each of the three decades (1988-2018) reflecting the implementation of urban planning. Furthermore, MSPA analysis showed that the reduction in vegetation cover led to habitat fragmentation with a significant decrease in the core and bridge classes and an increase in isolated patches in the urban landscape. Golf courses played a useful role in maintaining vegetation cover and contributing to connectivity in a regional biodiversity hotspot. Our findings suggest that for future urban expansion, urban planning needs to more carefully consider the impacts of deforestation on connectivity in the landscape. Moreover, there is a need to take into consideration opportunities for off-reserve conservation in smaller habitat fragments such as in golf courses in sustainable urban management.

The aim of this study is to identify key factors that influence the willingness-to-pay (WTP) of Internet users in Vietnam for fee-based online contents. The study collects 309 suitable questionnaires filled by internet users over 18 years old and living in Vietnam, who frequently use online contents and have ideally made payment for online contents. The analysis results indicate that the willingness-to-pay for the fee-based online contents of Vietnamese users are influenced by their attitudes toward paying and ethical self-efficacy for online piracy. The study also identifies the antecedents of attitude, which include the perceived benefits of usefulness and enjoyment, the perceived sacrifice of the fee, social influences from other people, and especially the free mentality. The study then suggests managerial implications to online content providers in enhancing WTP for the fee-based online contents in Vietnam.

We studied sandfly (Diptera: Psychodidae) populations in six provinces of Vietnam. This work explores the diversity of sandfly species according to the province, as well as environment, and updated information on public health since leishmaniasis cases were reported in two provinces. Sandflies were collected using 428 CDC light traps from May 30 to October 13, 2016 and identified based on the morphology of the cibarium, pharynx and/or male genitalia or female spermathecae. A total of 2585 sandflies belonging to five genera and 13 identified species were collected. The main species were: the Sergentomyia barraudi group (12.53%), Se. sylvatica (9.63%) and Phlebotomus stantoni (3.95%). In all, 294 Sergentomyia specimens classified as Se. sp2 and Se. sp3 and a heterogeneous group, herein called Se. und_sp., showed unknown morphological characteristics requiring further studies. We provide detailed comments about morphological description and taxonomical identification in order to help standardization of sandfly classification in Southeast Asia. We observed differentiation according to the provinces in terms of density and species richness, with Lang Son having the highest density and Ninh Binh having the highest species richness. The majority of specimens were collected in rock caves and outdoors, suggesting mainly cavernicolous and exophilic characters of sandfly species in Northern Vietnam. However, specimens were also collected in intra- and peri-domiciliary sites. It is worth noting that Ph. stantoni was the main species found in dog sheds and indoors, and in particular in a leishmaniasis patient’s house.

This paper aims to investigate the motivations and barriers of Vietnamese students towards the distance education. Quantitative strategy was exploited to conduct this research. The sample of 250 students who following the distance education programs in Ho Chi Minh City was selected. The results show that four motivation factors and six barrier factors were found. The motivations include: perceived benefits, amotivation, no pressure, and follow regulations. The barriers are: lack of time and family supports for study; lack of academic skills; lack of communications with the college/ school; Lack of Financial resources; technological problems and low Social interaction. In addition, research also proved that Perceived benefits and no pressure have positive impact on Intention of distance learning while lacking of academic skills has negative influence on the intention of distance learning.

High revenues from rubber latex exports have led to a rapid expansion of commercial rubber cultivation and, as a consequence, the conversion of different land use types (e.g., natural forests) into rubber plantations, which may lead to a decrease in soil health. In this study in Quang Tri Province, Vietnam, we determined: (1) the variation of soil health parameters along a chronosequence of rubber tree stands and natural forests and (2) the relationships and potential feedback between vegetation types, vegetation structures and soil health. Our results revealed that: (1) soil health was higher in natural forests than in rubber plantations with a higher values in higher biomass forests; (2) soil health was lower in younger rubber plantations; (3) soil health depends on vegetation structure (with significantly positive relationships found between soil health and canopy cover, litter biomass, dry litter cover and ground vegetation cover). This study highlights the need for more rigorous land management practices and land use conversion policies in order to ensure the long-term conservation of soil health in rubber plantations.

(1) Dengue is the most spread mosquito-borne viral disease in the world, and vector control is the only available means to suppress its prevalence, since no effective treatment or vaccine has been developed. A biological control program using copepods that feed on mosquito larvae has been practiced in Vietnam and some other countries, but the application of copepods was not always successful. (2) To understand why the utility of copepods varies, we evaluated the predation efficiency of a copepod species (Mesocyclops aspericornis) on a vector species (Aedes aegypti) by laboratory experiments under different temperatures, nutrition and prey-density conditions. (3) We found that copepod predation reduced intraspecific competition among Aedes larvae and then shortened the survivor’s aquatic life and increased their pupal weight. In addition, the predatory efficiency of copepods was reduced at high temperatures. Furthermore, performance of copepod offspring fell when the density of mosquito larvae was high, probably because mosquito larvae had adverse effects on copepod growth through competition for food resources. (4) These results suggest that the increase in mosquitoes will not be suppressed solely by the application of copepods if the density of mosquito larvae is high or ambient temperature is high. We need to consider additional control methods in order to maintain the efficiency of copepods to suppress mosquito increase.

Introduction: Tension hydrothorax is an uncommon emergent condition in which hemodynamic instability and respiratory compromise may occur. Emergency physicians may diagnose tension hydrothorax by point-of-care ultrasound. Case Series: We discuss the key sonographic features assisting in identification. Four patients with history of malignancy who were found to have tension hydrothorax exhibited the following common ultrasound findings: massive, left-sided pleural effusion; complete, compressive atelectasis; and shift of cardiac structures into the right hemithorax, resulting in right-sided probe placement to obtain cardiac views. Conclusion: This is the first instance to our knowledge of point-of-care ultrasound findings in tension hydrothorax to be described in the literature.