Search results for: Do Thanh Quan

Authors: Hai Hoang, Thanh Xuan Nguyen Thi, Guillaume Galliero

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Coarse-Grained (CG) molecular simulations have shown to be an efficient way to estimate thermophysical (static and dynamic) properties of fluids. Several strategies have been developed and reported in the literature for defining CG molecular models. Among them, those based on a top-down strategy (i.e. CG molecular models related to macroscopic observables), despite being heuristic, have increasingly gained attention. This is probably due to its simplicity in implementation and its ability to provide reasonable results for not only simple but also complex systems. Regarding simple Force-Fields associated with these CG molecular models, it has been found that the four parameters Mie chain model is one of the best compromises to describe thermophysical static properties (e.g. phase diagram, saturation pressure). However, parameterization procedures of these Mie-chain GC molecular models given in literature are generally insufficient to simultaneously provide static and dynamic (e.g. viscosity) properties. To deal with such situations, we have extended the corresponding states by using a quantity associated with the liquid viscosity. Results obtained from molecular simulations have shown that our approach is able to yield good estimates for both static and dynamic thermophysical properties for various real non-associating fluids. In addition, we will show that on simple (e.g. phase diagram, saturation pressure) and complex (e.g. thermodynamic response functions, thermodynamic energy potentials) static properties, results of our scheme generally provides improved results compared to existing approaches.

Keywords: coarse-grained model, mie potential, molecular simulations, thermophysical properties, phase equilibria

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Authors: Chen Jun-Hong, He Pu, Tao Wen-Quan

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Proton exchange membrane fuel cell (PEMFC) is the most promising future energy source owing to its low operating temperature, high energy efficiency, high power density, and environmental friendliness. In this paper, a comprehensive PEMFC system control-oriented model is developed in the Matlab/Simulink environment, which includes the hydrogen supply subsystem, air supply subsystem, and thermal management subsystem. Besides, Improved Artificial Bee Colony (IABC) is used in the parameter identification of PEMFC semi-empirical equations, making the maximum relative error between simulation data and the experimental data less than 0.4%. Operation temperature is essential for PEMFC, both high and low temperatures are disadvantageous. In the thermal management subsystem, water pump and fan are both controlled with the PID controller to maintain the appreciate operation temperature of PEMFC for the requirements of safe and efficient operation. To improve the control effect further, fuzzy control is introduced to optimize the PID controller of the pump, and the Radial Basis Function (RBF) neural network is introduced to optimize the PID controller of the fan. The results demonstrate that Fuzzy-PID and RBF-PID can achieve a better control effect with 22.66% decrease in Integral Absolute Error Criterion (IAE) of T_st (Temperature of PEMFC) and 77.56% decrease in IAE of T_in (Temperature of inlet cooling water) compared with traditional PID. In the end, a novel thermal management structure is proposed, which uses the cooling air passing through the main radiator to continue cooling the secondary radiator. In this thermal management structure, the parasitic power dissipation can be reduced by 69.94%, and the control effect can be improved with a 52.88% decrease in IAE of T_in under the same controller.

Keywords: PEMFC system, parameter identification, temperature control, Fuzzy-PID, RBF-PID, parasitic power

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Authors: Xi Quan Cheng, Yan Chao Xu, Xu Jiang, Lu Shao, Cher Hon Lau

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A hydrophilic thin-film-composite (TFC) nanofiltration (NF) membrane has been developed through the interfacial polymerization (IP) of amino-functional polyethylene glycol (PEG) and trimesoyl chloride. The selective layer is formed on a polyethersulfone (PES) support that is characterized using FTIR, XPS and SEM, and is dependent on monomer immersion duration, and the concentration of monomers and additives. The higher hydrophilicity alongside the larger pore size of the PEG-based selective layer is the key to a high water flux of 66.0 L m-2 h-1 at 5.0 bar. With mean pore radius of 0.42 nm and narrow pore size distribution, the MgSO4 rejections of the PEG based PA TFC NF membranes can reach up to 80.2 %. The hydrophilic PEG based membranes shows positive charged since the isoelectric points range from pH=8.9 to pH=9.1 and the rejection rates for different salts of the novel membranes are in the order of R(MgCl2)>R(MgSO4)>R(NaCl)>R(Na2SO4). The pore sizes and water permeability of these membranes are tailored by varying the molecular weight and molecular architecture of amino-functional PEG. Due to the unique structure of the selective layer of the PEG based membranes consisting of saturated aliphatic construction unit (CH2-CH2-O), the membranes demonstrate dual resistance to fouling and chlorine. The membranes maintain good salt rejections and high water flux of PEG based membranes after treatment by 2000 ppm NaClO for 24 hours. Interestingly, the PEG based membranes exhibit excellent fouling resistance with a water flux recovery of 90.2 % using BSA as a model molecule. More importantly, the hydrophilic PEG based NF membranes have been exploited to separate several water soluble antibiotics (such as tobramycin, an aminoglycoside antibiotic applied in the treatment of various types of bacterial infections), showing excellent performance in concentration or removal of antibioics.

Keywords: nanofiltration, antibiotic separation, hydrophilic membrane, high flux

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Authors: Nhac Thanh Huong

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New teaching methods have led to the changes in the teachers’ roles in an English class, in which teachers’ error correction is an integral part. Language error and corrective feedback have been the interest of many researchers in foreign language teaching. However, the techniques and the effectiveness of teachers’ feedback have been a question of much controversy. This present case study has been carried out with a view to finding out the patterns of teachers’ corrective feedback and their impact on students’ uptake in English speaking lessons of legal English major students at Hanoi Law University. In order to achieve those aims, the study makes use of classroom observations as the main method of data collection to seeks answers to the two following questions: 1. What patterns of corrective feedback occur in English speaking lessons for second- year legal English major students in Hanoi Law University?; 2. To what extent does that corrective feedback lead to students’ uptake? The study provided some important findings, among which was a close relationship between corrective feedback and uptake. In particular, recast was the most commonly used feedback type, yet it was the least effective in terms of students’ uptake and repair, while the most successful feedback, namely meta-linguistic feedback, clarification requests and elicitation, which led to students’ generated repair, was used at a much lower rate by teachers. Furthermore, it revealed that different types of errors needed different types of feedback. Also, the use of feedback depended on the students’ English proficiency level. In the light of findings, a number of pedagogical implications have been drawn in the hope of enhancing the effectiveness of teachers’ corrective feedback to students’ uptake in foreign language acquisition process.

Keywords: corrective feedback, error, uptake, speaking English lesson

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Authors: Van-Thanh Ho, Hyoungsoon Lee, Jaiyoung Ryu

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Efficient pressure distribution within soft robotic systems, specifically to the pneumatic artificial muscle (PAM) regions, is essential to minimize energy consumption. This optimization involves adjusting reservoir pressure, pipe diameter, and branching network layout to reduce flow speed and pressure drop while enhancing flow efficiency. The outcome of this optimization is a lightweight power source and reduced mechanical impedance, enabling extended wear and movement. To achieve this, a branching network system was created by combining pipe components and intricate cross-sectional area variations, employing the principle of minimal work based on a complete virtual human exosuit. The results indicate that modifying the cross-sectional area of the branching network, gradually decreasing it, reduces velocity and enhances momentum compensation, preventing flow disturbances at separation regions. These optimized designs achieve uniform velocity distribution (uniformity index > 94%) prior to entering the connection pipe, with a pressure drop of less than 5%. The design must also consider the length-to-diameter ratio for fluid dynamic performance and production cost. This approach can be utilized to create a comprehensive PAM system, integrating well-designed tube networks and complex pneumatic models.

Keywords: pneumatic artificial muscles, pipe networks, pressure drop, compressible turbulent flow, uniformity flow, murray's law

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Authors: Xuan Linh Nguyen, Tien Yin Chou, Yao Min Fang, Feng Cheng Lin, Thanh Van Hoang, Yin Min Huang

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In Vietnam, land use planning is the most important and powerful tool of the government for sustainable land use and land management. Nevertheless, many of land use planning locations are facing protests from surrounding households due to environmental impacts. In addition, locations are planned completely based on the subjective decisions of planners who are unsupported by tools or scientific methods. Hence, this research aims to assist the decision-makers in evaluating the rationality of planning locations by developing a Spatial Decision Support System (SDSS) using approaches of Geographic Information System (GIS)-based technology, Analytic Hierarchy Process (AHP) multi-criteria-based technique and Fuzzy set theory. An ArcGIS Desktop add-ins named SDSS-LUPA was developed to support users analyzing data and presenting results in friendly format. The Fuzzy-AHP method has been utilized as analytic model for this SDSS. There are 18 planned locations in Hung Ha district (Thai Binh province, Vietnam) as a case study. The experimental results indicated that the assessment threshold higher than 0.65 while the 18 planned locations were irrational because of close to residential areas or close to water sources. Some potential sites were also proposed to the authorities for consideration of land use planning changes.

Keywords: analytic hierarchy process, fuzzy set theory, land use planning, spatial decision support system

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Authors: Ngo Thi Thanh Mai, Nguyen Thu Ha, Frances Crawford

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The demand for developing international social work field education is on the rise. Global foreign universities have considered international collaboration and cross-cultural perspective as an essential part of their social work training curriculum. International placement program at Faculty of Social Work (FSW), Hanoi National University of Education (HNUE) has met the need of international social work students, as well as the institutions involved in achieving social work professional social work knowledge in the Vietnamese context. This program has also lead to a long-term collaboration between HNUE and several global institutions in developing social work education, research and practice skill. This paper focuses on the benefits and challenges of students who involved in the global placement programme at Faculty of Social Work (FSW), Hanoi National University of Education (HNUE) and content of international field education provided to the international students based on the experience of the authors. Study results indicated that the participants have opportunity them to explore a new culture and social work system abroad especially in the Vietnamese context. However, there are still difficulties that international students have to face during different phases of the exchange process such as language and communication barriers, cultural value differences, insufficient support and supervision during placement. Basing on these results, the authors intend to propose some recommendations to enhance the programme activities such as pre-departure orientation, support and supervision during placement, cultural exchange and follow-up activities.

Keywords: social work education, social work, international placement, field placement, Vietnam

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Authors: Huong Nguyen Thi Thanh, Van Mai Thi Khanh

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For around the world, payments for environmental services have been implemented since the late 1970s in Europe and North America; then, it was spread to Latin America, Asia, Africa, and finally Oceania in 2008. In Vietnam, payments for environmental services are an interesting issue recently with the forest as the main focus and therefore known as the program on payment for forest environmental services (PFES). PFES was piloted in Lam Dong and Son La in 2008 and has been widely applied in many provinces after 2010. PFES is in the orientation for the socialization of national forest protection in Vietnam and has made great strides in the last decade. By using the primary data and secondary data simultaneously, the paper clarifies two cases of implementing PFES in the Vietnam North Central area with the different mechanisms of payment. In the first case at Phu Loc district (Thua Thien Hue province), PFES is an indirect method by a water supply company via the Forest Protection and Development Fund. In the second one at Phong Nha – Ke Bang National Park (Quang Binh Province), tourism companies are the direct payers to forest owners. The paper describes the PFES implementation process at each site, clarifies the payment mechanism, and models the relationship between stakeholders in PFES implementation. Based on the current status of PFES sites, the paper compares and analyzes the advantages and disadvantages of the two payment methods. Finally, the paper proposes recommendations to improve the existing shortcomings in each payment mechanism.

Keywords: advantages and disadvantages, forest environmental services, forest protection, payment mechanism

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Authors: Trung Le Thanh

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Bored piles are always the optimal solution for high-rise building foundations. They have many advantages, such as large diameter, large pile length and construction in all different geological conditions. However, due to construction characteristics, the load-bearing capacity of bored piles is not optimal because wall friction is reduced due to poor contact between the pile and the surrounding soil. Therefore, grouting technology along the pile body helps improve the load-bearing capacity of bored piles significantly through increasing the skin resistance of the pile and surrounding soil. The improvement of pile skin resistance depends on the parameters of grouting technology, especially grouting volume, mortar viscosity, mortar strength,... and different geological conditions. Studies show that the technology of grouting piles on sandy soil is more effective than on clay. This article presents an experimental model to determine the load-bearing capacity of bored piles with a diameter of 400 mm and a length of 3 m on sand with different slurry volume in Tan Uyen city, Binh Duong province. On that basis, analyze the correlation between the increase in load-bearing capacity of bored piles without and with shaft grouting pile. Research results show that the wall resistance of shaft grouted piles increases 2-3 times compared to piles without grouting, and the pile's load-bearing capacity increases significantly. The article's research provides scientific value for consulting work on the design of bored piles when grouted along the pile body.

Keywords: bored pile, shaft grouting, bearing capacity, pile shaft resistance

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Authors: Srinivasa Reddy Mallampati, Chi-Hyeon Lee, Nguyen Thanh Truc, Byeong-Kyu Lee

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Organic polymeric materials (plastics) are widely used in our daily life and various industrial fields. The separation of waste plastics is important for its feedstock and mechanical recycling. One of the major problems in incineration for thermal recycling or heat melting for material recycling is the polyvinyl chloride (PVC) contained in waste plastics. This is due to the production of hydrogen chloride, chlorine gas, dioxins, and furans originated from PVC. Therefore, the separation of PVC from waste plastics is necessary before recycling. The separation of heavy polymers (PVC 1.42, PMMA 1.12, PC 1.22 and PET 1.27 g/cm3 ) from light ones (PE and PP 0.99 g/cm3) can be achieved on the basis of their density. However it is difficult to separate PVC from other heavy polymers basis of density. There are no simple and inexpensive techniques to separate PVC from others. If hydrophobic the PVC surface is selectively changed into hydrophilic, where other polymers still have hydrophobic surface, flotation process can separate PVC from others. In the present study, the selective surface hydrophilization of polyvinyl chloride (PVC) by microwave treatment after alkaline/acid washing and with activated carbon was studied as the pre-treatment of its separation by the following froth flotation. In presence of activated carbon as absorbent, the microwave treatment could selectively increase the hydrophilicity of the PVC surface (i.e. PVC contact angle decreased about 19o) among other plastics mixture. At this stage, 100% PVC separation from other plastics could be achieved by the combination of the pre- microwave treatment with activated carbon and the following froth floatation. The hydrophilization of PVC by surface analysis would be due to the hydrophilic groups produced by microwave treatment with activated carbon. The effect of optimum condition and detailed mechanism onto separation efficiency in the froth floatation was also investigated.

Keywords: Hydrophilic, PVC, contact angle, additive, microwave, froth floatation, waste plastics

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Authors: Dong Tran, Thanh Dac Van, Ly Le

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Hemagglutinin (HA) and Neuraminidase (NA) play an important role in host immune evasion across influenza virus evolution process. The correlation between HA and NA evolution in respect to epitopic evolution and drug interaction has yet to be investigated. In this study, combining of sequence to structure evolution and statistical analysis on epitopic/binding site specificity, we identified potential therapeutic features of HA and NA that show specific antibody binding site of HA and specific binding distribution within NA active site of current inhibitors. Our approach introduces the use of sequence variation and molecular interaction to provide an effective strategy in establishing experimental based distributed representations of protein-protein/ligand complexes. The most important advantage of our method is that it does not require complete dataset of complexes but rather directly inferring feature interaction from sequence variation and molecular interaction. Using correlated sequence analysis, we additionally identified co-evolved mutations associated with maintaining HA/NA structural and functional variability toward immunity and therapeutic treatment. Our investigation on the HA binding specificity revealed unique conserved stalk domain interacts with unique loop domain of universal antibodies (CR9114, CT149, CR8043, CR8020, F16v3, CR6261, F10). On the other hand, NA inhibitors (Oseltamivir, Zaninamivir, Laninamivir) showed specific conserved residue contribution and similar to that of NA substrate (sialic acid) which can be exploited for drug design. Our study provides an important insight into rational design and identification of novel therapeutics targeting universally recognized feature of influenza HA/NA.

Keywords: influenza virus, hemagglutinin (HA), neuraminidase (NA), sequence evolution

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Authors: Van-Thanh Ho, Jaiyoung Ryu

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In soft robotics, the optimization of fluid dynamics through pneumatic methods plays a pivotal role in enhancing operational efficiency and reducing energy loss. This is particularly crucial when replacing conventional techniques such as cable-driven electromechanical systems. The pneumatic model employed in this study represents a sophisticated framework designed to efficiently channel pressure from a high-pressure reservoir to various muscle locations on the robot's body. This intricate network involves a branching system of tubes. The study introduces a comprehensive pneumatic model, encompassing the components of a reservoir, tubes, and Pneumatically Actuated Muscles (PAM). The development of this model is rooted in the principles of shock tube theory. Notably, the study leverages experimental data to enhance the understanding of the interplay between the PAM structure and the surrounding fluid. This improved interactive approach involves the use of morphing motion, guided by a contraction function. The study's findings demonstrate a high degree of accuracy in predicting pressure distribution within the PAM. The model's predictive capabilities ensure that the error in comparison to experimental data remains below a threshold of 10%. Additionally, the research employs a machine learning model, specifically a surrogate model based on the Kriging method, to assess and quantify uncertainty factors related to the initial reservoir pressure and tube diameter. This comprehensive approach enhances our understanding of pneumatic soft robotics and its potential for improved operational efficiency.

Keywords: pneumatic artificial muscles, pressure drop, morhing motion, branched network, surrogate model

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Authors: Nguyen Tien Thanh, Günter Meon

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Precipitation plays a key role in water cycle, defining the local climatic conditions and in ecosystem. It is also an important input parameter for water resources management and hydrologic models. With spatial continuous data, a certainty of discharge predictions or other environmental factors is unquestionably better than without. This is, however, not always willingly available to acquire for a small basin, especially for coastal region in Vietnam due to a low network of meteorological stations (30 stations) on long coast of 3260 km2. Furthermore, available gridded precipitation datasets are not fine enough when applying to hydrologic models. Under conditions of global warming, an application of spatial interpolation methods is a crucial for the climate change impact studies to obtain the spatial continuous data. In recent research projects, although some methods can perform better than others do, no methods draw the best results for all cases. The objective of this paper therefore, is to investigate different spatial interpolation methods for daily precipitation over a small basin (approximately 400 km2) located in coastal region, Southern Vietnam and find out the most efficient interpolation method on this catchment. The five different interpolation methods consisting of cressman, ordinary kriging, regression kriging, dual kriging and inverse distance weighting have been applied to identify the best method for the area of study on the spatio-temporal scale (daily, 10 km x 10 km). A 30-year precipitation database was created and merged into available gridded datasets. Finally, observed changes in constructed precipitation were performed. The results demonstrate that the method of ordinary kriging interpolation is an effective approach to analyze the daily precipitation. The mixed trends of increasing and decreasing monthly, seasonal and annual precipitation have documented at significant levels.

Keywords: interpolation, precipitation, trend, vietnam

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Authors: Pham Minh Duc, Tran Thi Thanh Hien, David A. Bengtson

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Laboratory feeding trial: the study was conducted to find out the optimal dietary vitamin C, or ascorbic acid (AA) levels in terms of the growth performance of snakehead. The growth trial included six treatments with five replications. Each treatment contained 0, 125, 250, 500, 1000 and 2000 mg AA equivalent kg⁻¹ diet which included six iso-nitrogenous (45% protein), iso-lipid (9% lipid) and isocaloric (4.2 Kcal.g¹). Eighty snakehead fingerlings (6.24 ± 0.17 g.fish¹) were assigned randomly in 0.5 m³ composite tanks. Fish were fed twice daily on demand for 8 weeks. The result showed that growth rates increased, protein efficiency ratio increased and the feed conversion ratio decreased in treatments with AA supplementation compared with control treatment. The survival rate of fish tends to increase with increase AA level. The number of RBCs, lysozyme in treatments with AA supplementation tended to rise significantly proportional to the concentration of AA. The number of WBCs of snakehead in treatments with AA supplementation was higher 2.1-3.6 times. In general, supplementation of AA in the diets for snakehead improved growth rate, feed efficiency and immune response. Hapa on-farm trial: based on the results of the laboratory feeding trial, the effects of AA on snakehead in hapas to simulate farm conditions, was tested using the following treatments: commercial feed; commercial feed plus hand mixed AA at 500; 750 and 1000 mg AA.kg⁻¹; SBM diet without AA; SBM diet plus 500; 750 and 1000 mg AA.kg⁻¹. The experiment was conducted in two experimental ponds (only SBM diet without AA placed in one pond and the rest in the other pond) with four replicate hapa each. Stocking density was 150 fish.m² and culture period was 5 months until market size was attained. The growth performance of snakehead and economic aspects were examined in this research.

Keywords: fish health, growth rate, snakehead, Vitamin C

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Authors: Muhammad Afzal, Shahbaz Mushtaq, Duc-Anh-An-Vo, Kathryn Reardon Smith, Thanh Ma

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Climate change has become one of the most challenging environmental issues in the 21st century. Climate change-induced natural disasters, especially floods, are the major factors of livelihood vulnerability, impacting millions of individuals worldwide. Evaluating and mitigating the effects of floods requires an in-depth understanding of the relationship between vulnerability and livelihood capital assets. Using an integrated approach, sustainable livelihood framework, and system thinking approach, the study developed a conceptual model of a generalized livelihood system in District Rajanpur, Pakistan. The model visualizes the livelihood vulnerability system as a whole and identifies the key feedback loops likely to influence the livelihood vulnerability. The study suggests that such conceptual models provide effective communication and understanding tools to stakeholders and decision-makers to anticipate the problem and design appropriate policies. It can also serve as an evaluation technique for rural livelihood policy and identify key systematic interventions. The key finding of the study reveals that household income, health, and education are the major factors behind the livelihood vulnerability of the rural poor of District Rajanpur. The Pakistani government tried to reduce the livelihood vulnerability of the region through different income, health, and education programs, but still, many changes are required to make these programs more effective especially during the flood times. The government provided only cash to vulnerable and marginalized families through income support programs, but this study suggests that along with the cash, the government must provide seed storage facilities and access to crop insurance to the farmers. Similarly, the government should establish basic health units in villages and frequent visits of medical mobile vans should be arranged with advanced medical lab facilities during and after the flood.

Keywords: livelihood vulnerability, rural communities, flood, sustainable livelihood framework, system dynamics, Pakistan

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Authors: Thi Thanh Nga Pham, Damien Philippon, Alexis Drogoul, Thi Thu Thuy Nguyen, Tien Cong Nguyen

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Mekong River Delta region of Vietnam is recognized as one of the most vulnerable to climate change due to flooding and seawater rise and therefore an increased burden of climate change-related diseases. Changes in temperature and precipitation are likely to alter the incidence and distribution of vector-borne diseases such as dengue fever. In this region, the peak of the dengue epidemic period is around July to September during the rainy season. It is believed that climate is an important factor for dengue transmission. This study aims to enhance the capacity of dengue prediction by the relationship of dengue incidences with climate and environmental variables for Mekong River Delta of Vietnam during 2005-2015. Mathematical models for vector-host infectious disease, including larva, mosquito, and human being were used to calculate the impacts of climate to the dengue transmission with incorporating geospatial data for model input. Monthly dengue incidence data were collected at provincial level. Precipitation data were extracted from satellite observations of GSMaP (Global Satellite Mapping of Precipitation), land surface temperature and land cover data were from MODIS. The value of seasonal reproduction number was estimated to evaluate the potential, severity and persistence of dengue infection, while the final infected number was derived to check the outbreak of dengue. The result shows that the dengue infection depends on the seasonal variation of climate variables with the peak during the rainy season and predicted dengue incidence follows well with this dynamic for the whole studied region. However, the highest outbreak of 2007 dengue was not captured by the model reflecting nonlinear dependences of transmission on climate. Other possible effects will be discussed to address the limitation of the model. This suggested the need of considering of both climate variables and another variability across temporal and spatial scales.

Keywords: infectious disease, dengue, geospatial data, climate

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Authors: Thanh N. Do

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This paper addresses the modeling of two critical behaviors of concrete material in reinforced concrete components: (1) the increase in strength and ductility due to confining stresses from surrounding transverse steel reinforcements, and (2) the progressive deterioration in strength and stiffness due to high strain and/or cyclic loading. To improve the state-of-the-art, the author presents a new 3D constitutive model of concrete material based on plasticity and continuum damage mechanics theory to simulate both the confinement effect and the strength deterioration in reinforced concrete components. The model defines a yield function of the stress invariants and a compressive damage threshold based on the level of confining stresses to automatically capture the increase in strength and ductility when subjected to high compressive stresses. The model introduces two damage variables to describe the strength and stiffness deterioration under tensile and compressive stress states. The damage formulation characterizes well the degrading behavior of concrete material, including the nonsymmetric strength softening in tension and compression, as well as the progressive strength and stiffness degradation under primary and follower load cycles. The proposed damage model is implemented in a general purpose finite element analysis program allowing an extensive set of numerical simulations to assess its ability to capture the confinement effect and the degradation of the load-carrying capacity and stiffness of structural elements. It is validated against a collection of experimental data of the hysteretic behavior of reinforced concrete columns and shear walls under different load histories. These correlation studies demonstrate the ability of the model to describe vastly different hysteretic behaviors with a relatively consistent set of parameters. The model shows excellent consistency in response determination with very good accuracy. Its numerical robustness and computational efficiency are also very good and will be further assessed with large-scale simulations of structural systems.

Keywords: concrete, damage-plasticity, shear wall, confinement

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Authors: Pattanapon Kayansamruaj, Ha Thanh Dong, Nopadon Pirarat, Channarong Rodkhum

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Streptococcus iniae (SI) is a devastating pathogenic bacteria causing heavy mortality in farmed fish. The application of commercialized bacterin vaccine has been reported failures as the outbreaks of the new serotype of SI were emerged in farms after vaccination and subsequently caused severe losses. In the present study, we attempted to develop effective DNA vaccines against SI infection using Nile tilapia (Oreochromis niloticus) as an animal model. Two monovalent DNA vaccines were constructed by the insertion of coding sequences of cell wall-associated virulence factors-encoding genes, comprised of eno (α-enolase) and mtsB (hydrophobic membrane protein), into cytomegalovirus expression vector (pCI-neo). In the animal trial, 30-g Nile tilapia were injected intramuscularly with 15 µg of each vaccine (mock vaccine group was injected by naked pCI-neo) and maintained for 35 days prior challenging with pathogenic SI at the dosage of 107 CFU/fish. At 13 days post-challenge, the relative percent survival of pEno, pMtsB and mock vaccine were 57%, 45% and 27%, respectively. The expression levels of immune responses-associated genes, namely, IL1β, TNF-α, TGF-β, COX2, IL-6, IL-12 and IL-13, were investigated from the spleen of experimental animal at 7 days post-vaccination (PV) and 7 days post-challenge (PC) using quantitative RT-PCR technique. Generally, at 7 days PV, the pEno vaccinated group exhibited highest level of up-regulation (1.7 to 2.9 folds) of every gene, but TGF-β, comparing to pMtsB and mock vaccine groups. However, at 7 days PC, pEno group showed significant up-regulation (1.4 to 8.5 folds) of immune-related genes as similar as mock vaccine group, while pMtsB group had lowest level of up-regulation (0.7 to 3.3 folds). Summarily, this study indicated that the pEno and pMtsB vaccines could elicit the immune responses of the fish and the magnitude of gene expression at 7 days PV was also consistent with the protection level conferred by the vaccine.

Keywords: gene expression, DNA vaccine, Nile tilapia, Streptococcus iniae

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Authors: Thomas Monahan, Nicolas Gorius, Thanh Nguyen

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Exoplanet atmospheric parameters retrieval is a complex, computationally intensive, inverse modeling problem in which an exoplanet’s atmospheric composition is extracted from an observed spectrum. Traditional Bayesian sampling methods require extensive time and computation, involving algorithms that compare large numbers of known atmospheric models to the input spectral data. Runtimes are directly proportional to the number of parameters under consideration. These increased power and runtime requirements are difficult to accommodate in space missions where model size, speed, and power consumption are of particular importance. The use of traditional Bayesian sampling methods, therefore, compromise model complexity or sampling accuracy. The Atmospheric Retrievals conditional Generative Adversarial Network (ARcGAN) is a deep convolutional generative adversarial network that improves on the previous model’s speed and accuracy. We demonstrate the efficacy of artificial intelligence to quickly and reliably predict atmospheric parameters and present it as a viable alternative to slow and computationally heavy Bayesian methods. In addition to its broad applicability across instruments and planetary types, ARcGAN has been designed to function on low power application-specific integrated circuits. The application of edge computing to atmospheric retrievals allows for real or near-real-time quantification of atmospheric constituents at the instrument level. Additionally, edge computing provides both high-performance and power-efficient computing for AI applications, both of which are critical for space missions. With the edge computing chip implementation, ArcGAN serves as a strong basis for the development of a similar machine-learning algorithm to reduce the downlinked data volume from the Compact Ultraviolet to Visible Imaging Spectrometer (CUVIS) onboard the DAVINCI mission to Venus.

Keywords: deep learning, generative adversarial network, edge computing, atmospheric parameters retrieval

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Authors: Nguyen-Thanh Son

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Flood is among the most frequent and costliest natural hazards. The flood disasters especially affect the poor people in rural areas, who are heavily dependent on agriculture and have lower incomes. Cambodia is identified as one of the most climate-vulnerable countries in the world, ranked 13th out of 181 countries most affected by the impacts of climate change. Flood monitoring is thus a strategic priority at national and regional levels because policymakers need reliable spatial and temporal information on flood-prone areas to form successful monitoring programs to reduce possible impacts on the country’s economy and people’s likelihood. This study aims to develop methods for flood mapping and assessment from MODIS data in Cambodia. We processed the data for the period from 2000 to 2017, following three main steps: (1) data pre-processing to construct smooth time-series vegetation and water surface indices, (2) delineation of flood-prone areas, and (3) accuracy assessment. The results of flood mapping were verified with the ground reference data, indicating the overall accuracy of 88.7% and a Kappa coefficient of 0.77, respectively. These results were reaffirmed by close agreement between the flood-mapping area and ground reference data, with the correlation coefficient of determination (R²) of 0.94. The seasonally flooded areas observed for 2010, 2015, and 2016 were remarkably smaller than other years, mainly attributed to the El Niño weather phenomenon exacerbated by impacts of climate change. Eventually, although several sources potentially lowered the mapping accuracy of flood-prone areas, including image cloud contamination, mixed-pixel issues, and low-resolution bias between the mapping results and ground reference data, our methods indicated the satisfactory results for delineating spatiotemporal evolutions of floods. The results in the form of quantitative information on spatiotemporal flood distributions could be beneficial to policymakers in evaluating their management strategies for mitigating the negative effects of floods on agriculture and people’s likelihood in the country.

Keywords: MODIS, flood, mapping, Cambodia

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Authors: Ayman Mutahar Alrassas, Shaoran Ren, Renyuan Ren, Hung Vo Thanh, Mohammed Hail Hakimi, Zhenliang Guan

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The significant effect of CO₂ on global climate and the environment has gained more concern worldwide. Enhance oil recovery (EOR) associated with sequestration of CO₂ particularly into the depleted oil reservoir is considered the viable approach under financial limitations since it improves the oil recovery from the existing oil reservoir and boosts the relation between global-scale of CO₂ capture and geological sequestration. Consequently, practical measurements are required to attain large-scale CO₂ emission reduction. This paper presents an integrated modeling workflow to construct an accurate 3D reservoir geological model to estimate the storage capacity of CO₂ under geological uncertainty in an unconventional oil reservoir of the Paleogene Shahejie Formation (Es1) in the block Nv32, Shenvsi oilfield, China. In this regard, geophysical data, including well logs of twenty-two well locations and seismic data, were combined with geological and engineering data and used to construct a 3D reservoir geological modeling. The geological modeling focused on four tight reservoir units of the Shahejie Formation (Es1-x1, Es1-x2, Es1-x3, and Es1-x4). The validated 3D reservoir models were subsequently used to calculate the theoretical CO₂ storage capacity in the block Nv32, Shenvsi oilfield. Well logs were utilized to predict petrophysical properties such as porosity and permeability, and lithofacies and indicate that the Es1 reservoir units are mainly sandstone, shale, and limestone with a proportion of 38.09%, 32.42%, and 29.49, respectively. Well log-based petrophysical results also show that the Es1 reservoir units generally exhibit 2–36% porosity, 0.017 mD to 974.8 mD permeability, and moderate to good net to gross ratios. These estimated values of porosity, permeability, lithofacies, and net to gross were up-scaled and distributed laterally using Sequential Gaussian Simulation (SGS) and Simulation Sequential Indicator (SIS) methods to generate 3D reservoir geological models. The reservoir geological models show there are lateral heterogeneities of the reservoir properties and lithofacies, and the best reservoir rocks exist in the Es1-x4, Es1-x3, and Es1-x2 units, respectively. In addition, the reservoir volumetric of the Es1 units in block Nv32 was also estimated based on the petrophysical property models and fund to be between 0.554368

Keywords: CO₂ storage capacity, 3D geological model, geological uncertainty, unconventional oil reservoir, block Nv32

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Authors: Hong Nguyen Thi Hai, Ryota Konda, Dat Kieu Tuan, Cao Tran Thanh, Khang Phung Van, Hau Tran Tin, Harry Wu

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Melaleuca cajuputi is a moderately fast-growing species and considered as a multi-purpose tree as it provides fuelwood, piles and frame poles in construction, leaf essential oil and honey. It occurs in Australia, Papua New Guinea, and South-East Asia. M. cajuputi plantation can be harvested on 6-7 year rotations for wood products. Its timber can also be used for pulp and paper, fiber and particle board, producing quality charcoal and potentially sawn timber. However, most reported M. cajuputi breeding programs have been focused on oil production rather than wood production. In this study, breeding program of M. cajuputi aimed to improve wood production was examined by estimating genetic parameters for growth (tree height, diameter at breast height (DBH), and volume), stem form, stiffness (modulus of elasticity (MOE)), bark thickness and bark ratio in a half-sib family progeny trial including 80 families in the Mekong Delta of Vietnam. MOE is one of the key wood properties of interest to the wood industry. Non-destructive wood stiffness was measured indirectly by acoustic velocity using FAKOPP Microsecond Timer and especially unaffected by bark mass. Narrow-sense heritability for the seven traits ranged from 0.13 to 0.27 at age 7 years. MOE and stem form had positive genetic correlations with growth while the negative correlation between bark ratio and growth was also favorable. Breeding for simultaneous improvement of multiple traits, faster growth with higher MOE and reduction of bark ratio should be possible in M. cajuputi. Index selection based on volume and MOE showed genetic gains of 31 % in volume, 6 % in MOE and 13 % in stem form. In addition, heritability and age-age genetic correlations for growth traits increased with time and optimal early selection age for growth of M. cajuputi based on DBH alone was 4 years. Selected thinning resulted in an increase of heritability due to considerable reduction of phenotypic variation but little effect on genetic variation.

Keywords: acoustic velocity, age-age correlation, bark thickness, heritability, Melaleuca cajuputi, stiffness, thinning effect

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Authors: Yik Sin Chan, Bee Ling Chuah, Wei Quan Chan, Ri Jin Cheng, Yan Hang Oon, Kong Soo Khoo, Nam Weng Sit

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Traditionally, medicinal plants have been used to treat different kinds of ailments including infectious diseases. They serve as a good source of lead compounds for the development of new and safer anti-infective agents. This study aimed to investigate the antimicrobial potential of the leaves of three medicinal plants, namely Catunaregam spinosa (Rubiaceae; Mountain pomegranate), Houttuynia cordata (Saururaceae; "fishy-smell herb") and Rhapis excelsa (Arecaceae; “broadleaf lady palm”). The leaves extracts were obtained by sequential extraction using hexane, chloroform, ethyl acetate, ethanol, methanol and water. The antibacterial and antifungal activities were assessed using a colorimetric broth microdilution method against a panel of human pathogenic bacteria (Gram-positive: Bacillus cereus and Staphylococcus aureus; Gram-negative: Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) and fungi (yeasts: Candida albicans, Candida parapsilosis and Cryptococcus neoformans; Moulds: Aspergillus fumigatus and Trichophyton mentagrophytes) respectively; while antiviral activity was evaluated against the Chikungunya virus on monkey kidney epithelial (Vero) cells by neutral red uptake assay. All the plant extracts showed bacteriostatic activity, however, only 72% of the extracts (13/18) were found to have bactericidal activity. The lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were given by the hexane extract of C. spinosa against S. aureus with the values of 0.16 and 0.31 mg/mL respectively. All the extracts also possessed fungistatic activity. Only the hexane, chloroform and ethyl acetate extracts of H. cordata exerted inhibitory activity against A. fumigatus, giving the lowest fungal susceptibility index of 16.7%. In contrast, only 61% of the extracts (11/18) showed fungicidal activity. The ethanol extract of R. excelsa exhibited the strongest fungicidal activity against C. albicans, C. parapsilosis and T. mentagrophytes with minimum fungicidal concentration (MFC) values of 0.04–0.08 mg/mL, in addition to its methanol extract against T. mentagrophytes (MFC=0.02 mg/mL). For anti-Chikungunya virus activity, only chloroform and ethyl acetate extracts of R. excelsa showed significant antiviral activity with 50% effective concentrations (EC50) of 29.9 and 78.1 g/mL respectively. Extracts of R. excelsa warrant further investigations into their active principles responsible for antifungal and antiviral properties.

Keywords: bactericidal, Chikungunya virus, extraction, fungicidal

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Authors: Asrarul H. Jeelani

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Arsenic contamination of groundwater and its’ health implications in lower Gangetic plain of Indian states started reporting in the 1980s. The same period was declared as the first water decade (1981-1990) to achieve ‘water for all.’ To fulfill the aim, the Indian government, with the support of international agencies installed millions of hand-pumps through water resources development programs. The hand-pumps improve the accessibility if the groundwater, but over-extraction of it increases the chances of mixing of trivalent arsenic which is more toxic than pentavalent arsenic of dug well water in Gangetic plain and has different physical manifestations. Now after three decades, Bihar (middle Gangetic plain) is also facing arsenic contamination of groundwater and its’ health implications. Objective: This interdisciplinary research attempts to understand the health and social implications of arsenicosis among different castes in Haldi Chhapra village and to find the association of ramifications with water resources development. Methodology: The Study used concurrent quantitative dominant mix method (QUAN+qual). The researcher had employed household survey, social mapping, interviews, and participatory interactions. However, the researcher used secondary data for retrospective analysis of hand-pumps and implications of arsenicosis. Findings: The study found 88.5% (115) household have hand-pumps as a source of water however 13.8% uses purified supplied water bottle and 3.6% uses combinations of hand-pump, bottled water and dug well water for drinking purposes. Among the population, 3.65% of individuals have arsenicosis, and 2.72% of children between the age group of 5 to 15 years are affected. The caste variable has also emerged through quantitative as well as geophysical locations analysis as 5.44% of arsenicosis manifested individual belong to scheduled caste (SC), 3.89% to extremely backward caste (EBC), 2.57% to backward caste (BC) and 3% to other. Among three clusters of arsenic poisoned locations, two belong to SC and EBC. The village as arsenic affected is being discriminated, whereas the affected individual is also facing discrimination, isolation, stigma, and problem in getting married. The forceful intervention to install hand-pumps in the first water decades and later restructuring of the dug well destroyed a conventional method of dug well cleaning. Conclusion: The common manifestation of arsenicosis has increased by 1.3% within six years of span in the village. This raised the need for setting up a proper surveillance system in the village. It is imperative to consider the social structure for arsenic mitigation program as this research reveals caste as a significant factor. The health and social implications found in the study; retrospectively analyzed as the collateral impact of water resource development programs in the village.

Keywords: arsenicosis, caste, collateral impact, water resources

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Authors: Binh Thanh Ta, Elizabeth Sturgiss

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Central to patient-centered care is the idea of treating a patient as a person and understanding their perspectives regarding their health conditions and care preferences. Surprisingly, little is known about how GPs can understand their patients’ perspectives. This paper addresses the challenge of understanding patient perspectives in behavior change consultations by adopting Conversation Analysis (CA), which is an empirical research approach that allows both researchers and the audience to examine patients’ perspectives as displayed in GP-patient interaction. To understand people’s perspectives, CA researchers do not rely on what they say but instead on how they demonstrate their endogenous orientations to social norms when they interact with each other. Underlying CA is the notion that social interaction is orderly by all means. (It is important to note that social orders should not be treated as exogenous sets of rules that predetermine human behaviors. Rather social orders are constructed and oriented by social members through their interactional practices. Also, note that these interactional practices are the resources shared by all social members). As CA offers tools to uncover the orderliness of interactional practices, it not only allows us to understand the perspective of a particular patient in a particular medical encounter but, more importantly, enables us to recognise the shared interactional practice for signifying a particular perspective. Drawing on the 10 video-recorded consultations on behavior change in primary care, we have discovered the orderliness of patient laughter when reporting health behaviors, which signifies their orientation to the problematic nature of the reported behaviors. Among 24 cases where patients reported their health behaviors, we found 19 cases in which they laughed while speaking. In the five cases where patients did not laugh, we found that they explicitly framed their behavior as unproblematic. This finding echoes the CA body research on laughter, which suggests that laughter produced by first speakers (as opposed to laughing in response to what has been said earlier) normally indicates some sort of problems oriented to the self (e.g. self-tease, self-depreciation, etc.). This finding points to the significance of understanding when and why patients laugh; such understanding would assist GPs to recognise whether patients treat their behavior as problematic or not, thereby producing responses sensitive to patient perspectives.

Keywords: patient centered care, laughter, conversation analysis, primary care, behaviour change consultations

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Authors: Iris Xiaohong Quan

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The global digital health market reached 175 billion U.S. dollars in 2019, and is expected to grow at about 25% CAGR to over 650 billion USD by 2025. Different terms such as digital health, e-health, mHealth, telehealth have been used in the field, which can sometimes cause confusion. The term digital health was originally introduced to refer specifically to the use of interactive media, tools, platforms, applications, and solutions that are connected to the Internet to address health concerns of providers as well as consumers. While mHealth emphasizes the use of mobile phones in healthcare, telehealth means using technology to remotely deliver clinical health services to patients. According to FDA, “the broad scope of digital health includes categories such as mobile health (mHealth), health information technology (IT), wearable devices, telehealth and telemedicine, and personalized medicine.” Some researchers believe that digital health is nothing else but the cultural transformation healthcare has been going through in the 21st century because of digital health technologies that provide data to both patients and medical professionals. As digital health is burgeoning, but research in the area is still inadequate, our paper aims to clear the definition confusion and provide an overall picture of digital health companies. We further investigate how business models are designed and differentiated in the emerging digital health sector. Both quantitative and qualitative methods are adopted in the research. For the quantitative analysis, our research data came from two databases Crunchbase and CBInsights, which are well-recognized information sources for researchers, entrepreneurs, managers, and investors. We searched a few keywords in the Crunchbase database based on companies’ self-description: digital health, e-health, and telehealth. A search of “digital health” returned 941 unique results, “e-health” returned 167 companies, while “telehealth” 427. We also searched the CBInsights database for similar information. After merging and removing duplicate ones and cleaning up the database, we came up with a list of 1464 companies as digital health companies. A qualitative method will be used to complement the quantitative analysis. We will do an in-depth case analysis of three successful unicorn digital health companies to understand how business models evolve and discuss the challenges faced in this sector. Our research returned some interesting findings. For instance, we found that 86% of the digital health startups were founded in the recent decade since 2010. 75% of the digital health companies have less than 50 employees, and almost 50% with less than 10 employees. This shows that digital health companies are relatively young and small in scale. On the business model analysis, while traditional healthcare businesses emphasize the so-called “3P”—patient, physicians, and payer, digital health companies extend to “5p” by adding patents, which is the result of technology requirements (such as the development of artificial intelligence models), and platform, which is an effective value creation approach to bring the stakeholders together. Our case analysis will detail the 5p framework and contribute to the extant knowledge on business models in the healthcare industry.

Keywords: digital health, business models, entrepreneurship opportunities, healthcare

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Authors: Saem Lee, Thanh Nguyen, Hio-Jung Shin, Thomas Koellner

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Land-use management has an influence on the provision of ecosystem service in dynamic, agricultural landscapes. Agricultural land use is important for maintaining the productivity and sustainability of agricultural ecosystems. However, in Korea, intensive farming activities in this highland agricultural zone, the upper stream of Soyang has led to contaminated soil caused by over-use pesticides and fertilizers. This has led to decrease in water and soil quality, which has consequences for ecosystem services and human wellbeing. Conventional farming has still high percentage in this area and there is no special measure to prevent low water quality caused by farming activities. Therefore, the adoption of environmentally friendly farming has been considered one of the alternatives that lead to improved water quality and increase in biomass production. Concurrently, farm households with environmentally friendly farming have occupied still low rates. Therefore, our research involved a farm household survey spanning conventional farming, the farm in transition and organic farming in Soyang watershed. Another purpose of our research was to compare economic advantage of the farmers adopting environmentally friendly farming and non-adaptors and to investigate the different factors by logistic regression analysis with socio-economic and benefit-cost ratio variables. The results found that farmers with environmentally friendly farming tended to be younger than conventional farming and farmer in transition. They are similar in terms of gender which was predominately male. Farmers with environmentally friendly farming were more educated and had less farming experience than conventional farming and farmer in transition. Based on the benefit-cost analysis, total costs that farm in transition farmers spent for one year are about two times as much as the sum of costs in environmentally friendly farming. The benefit of organic farmers was assessed with 2,800 KRW per household per year. In logistic regression, the factors having statistical significance are subsidy and district, residence period and benefit-cost ratio. And district and residence period have the negative impact on the practice of environmentally friendly farming techniques. The results of our research make a valuable contribution to provide important information to describe Korean policy-making for agricultural and water management and to consider potential approaches to policy that would substantiate ways beneficial for sustainable resource management.

Keywords: organic farming, logistic regression, profitability, agricultural land-use

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Authors: Iris Xiaohong Quan, Sharon Qi, Kelly Tianqin Shi

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This study focuses on the critical role of insurance policies in a world grappling with increasing mental health challenges, as they significantly influence the dynamics of healthcare businesses and entrepreneurial ventures. The paper utilizes the mental health sector as a case to examine the impact of insurance policies on healthcare service providers, entrepreneurs, and individuals seeking mental health support. This paper addressed the following research questions: To what extent do changes in insurance reimbursement policies affect the accessibility and affordability of mental health services for patients, and how does this impact the overall demand for such services? What are the barriers and opportunities that mental health entrepreneurs face and what strategies and adaptations do mental health businesses employ when navigating the evolving landscape of insurance reimbursement policies? How do changes in insurance reimbursement policies, specifically related to mental health services, influence the financial viability and sustainability of mental health clinics and private practices? Employing a self-designed survey aimed at autism spectrum disorder (ASD) treatment companies, alongside two in-depth case studies and an analysis of pertinent insurance policies and documents, this research aims to elucidate the multifaceted influence of insurance policies on the mental health industry. The findings from this study reveal how insurance policies shape the landscape of mental health businesses and their operations. A total of 821 autism treatment organizations or offices were contacted by telephone between November 1, 2019, and January 31, 2020. About half of the offices (53.33%) were established in the past five years, and 80% were established in the past 15 years. There is a significant increase in the establishment of ABA service centers in the recent two decades as a result of autism insurance reform, the increasing social awareness of ASD, and the redefinition of autism. In addition, almost half of the ABA service providers we surveyed had a patient size ranging from 20 to 50 in the year when the residence state passed the legislation for autism insurance coverage. On average, an ABA service provider works with 5.3 insurance companies. This research find that insurance is the main source of revenue for most ABA service providers. However, our survey reveals that clients’ out of pocket payment has been the second main revenue sources. Despite the changes of regulations and insurance policies in all states, clients still have to pay a fraction of, if not all, the ABA treatment service fees out of pocket. This research shows that some ABA service providers seek federal and government funds and grants to support their services and businesses. Our further analysis with the in-depth case studies and other secondary data also indicate the rise of entrepreneurial startups in the mental health industry. Overall, this research sheds light on both the challenges and opportunities presented by insurance policies in the mental health sector, offering insights into the new industry landscape.

Keywords: entrepreneurship, healthcare policy, insurance policy, mental health industry

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Authors: Angela T. H. Kwan, Wenjun Liang, Jack Wellington, Mohammad Mofatteh, Thanh N. Nguyen, Pingzhong Fu, Juanmei Chen, Zile Yan, Weijuan Wu, Yongting Zhou, Shuiquan Yang, Sijie Zhou, Yimin Chen

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Background: Endovascular Therapy (EVT)—in the form of mechanical thrombectomy—following intravenous thrombolysis is the standard gold treatment for patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO). It is well established that an ASPECTS ≥ 7 is associated with an increased likelihood of positive post-EVT outcomes, as compared to an ASPECTS < 7. There is also prognostic utility in coupling posterior circulation ASPECTS (pc-ASPECTS) with magnetic resonance imaging for evaluating the post-EVT functional outcome. However, the value of pc-ASPECTS applied to CT must be explored further to determine its usefulness in predicting functional outcomes following EVT. Objective: In this study, we aimed to determine whether pc-ASPECTS on CT can predict post-EVT functional outcomes among patients with AIS due to LVO. Methods: A total of 247 consecutive patients aged 18 and over receiving EVT for LVO-related AIS were recruited into a prospective database. The data were retrospectively analyzed between March 2019 to February 2022 from two comprehensive tertiary care stroke centers: Foshan Sanshui District People’s Hospital and First People's Hospital of Foshan in China. Patient parameters included EVT within 24hrs of symptom onset, premorbid modified Rankin Scale (mRS) ≤ 2, presence of distal and terminal cerebral blood vessel occlusion, and subsequent 24–72-hour post-stroke onset CT scan. Univariate comparisons were performed using the Fisher exact test or χ2 test for categorical variables and the Mann–Whitney U test for continuous variables. A p-value of ≤ 0.05 was statistically significant. Results: A total of 247 patients met the inclusion criteria; however, 3 were excluded due to the absence of post-CTs and 8 for pre-EVT ASPECTS < 7. Overall, 236 individuals were examined: 196 anterior circulation ischemic strokes and 40 posterior strokes of basilar artery occlusion. We found that both baseline post- and pc-ASPECTS ≥ 7 serve as strong positive markers of favorable outcomes at 90 days post-EVT. Moreover, lower rates of inpatient mortality/hospice discharge, 90-day mortality, and 90-day poor outcome were observed. Moreover, patients in the post-ASPECTS ≥ 7 anterior circulation group had shorter door-to-recanalization time (DRT), puncture-to-recanalization time (PRT), and last known normal-to-puncture-time (LKNPT). Conclusion: Patients of anterior and posterior circulation ischemic strokes with baseline post- and pc-ASPECTS ≥ 7 may benefit from EVT.

Keywords: endovascular therapy, thrombectomy, large vessel occlusion, cerebral ischemic stroke, ASPECTS

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Authors: Quan Wen, Tianxiao Chang, Shaolu Shi, Yushi Wang, Guangyu Wang

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As a kind of working environment of the fuze, the spin rate decaying law of projectile in exterior trajectory is of great value in the design of the rotation count fixed distance fuze. In addition, it is significant in the field of devices for simulation tests of fuze exterior ballistic environment, flight stability, and dispersion accuracy of gun projectile and opening and scattering design of submunition and illuminating cartridges. Besides, the self-destroying mechanism of the fuze in small-caliber projectile often works by utilizing the attenuation of centrifugal force. In the theory of projectile aerodynamics and fuze design, there are many formulas describing the change law of projectile angular velocity in external ballistic such as Roggla formula, exponential function formula, and power function formula. However, these formulas are mostly semi-empirical due to the poor test conditions and insufficient test data at that time. These formulas are difficult to meet the design requirements of modern fuze because they are not accurate enough and have a narrow range of applications now. In order to provide more accurate ballistic environment parameters for the design of a hemispherical head projectile fuze, the projectile’s spin rate decaying law in exterior trajectory under the effect of air resistance was studied. In the analysis, the projectile shape was simplified as hemisphere head, cylindrical part, rotating band part, and anti-truncated conical tail. The main assumptions are as follows: a) The shape and mass are symmetrical about the longitudinal axis, b) There is a smooth transition between the ball hea, c) The air flow on the outer surface is set as a flat plate flow with the same area as the expanded outer surface of the projectile, and the boundary layer is turbulent, d) The polar damping moment attributed to the wrench hole and rifling mark on the projectile is not considered, e) The groove of the rifle on the rotating band is uniform, smooth and regular. The impacts of the four parts on aerodynamic moment of the projectile rotation were obtained by aerodynamic theory. The surface friction stress of the projectile, the polar damping moment formed by the head of the projectile, the surface friction moment formed by the cylindrical part, the rotating band, and the anti-truncated conical tail were obtained by mathematical derivation. After that, the mathematical model of angular spin rate attenuation was established. In the whole trajectory with the maximum range angle (38°), the absolute error of the polar damping torque coefficient obtained by simulation and the coefficient calculated by the mathematical model established in this paper is not more than 7%. Therefore, the credibility of the mathematical model was verified. The mathematical model can be described as a first-order nonlinear differential equation, which has no analytical solution. The solution can be only gained as a numerical solution by connecting the model with projectile mass motion equations in exterior ballistics.

Keywords: ammunition engineering, fuze technology, spin rate, numerical simulation

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