117 research outputs found
Students’ Perceived Well-Being and Online Preference : Evidence from Two Universities in Vietnam during COVID-19
University education is still being impacted two years after the COVID-19 outbreak. We performed a rapid survey in February 2022 at two public universities in Vietnam to examine the effects of the pandemic on well-being and the factors that may associate with online class preference among university students as well as to investigate the need for support to improve resilience. A web-based survey included 1589 undergraduate students in total. Both quantitative and qualitative data analysis was carried out. Overall, approximately a quarter of respondents said that they perceived an influence on their health, 42.9% expressed stress, and more than 70% reported worrying about the future. In total, 61.9% of the respondents reported having satisfaction with online classes, while over half of them preferred a program of 50% online classes. Students who live in an urban area, are female, have had pre-COVID-19 campus life experience, have decreased income, and/or experience low online satisfaction and over-information may be in need of more support. The results show implications for universities to consider policies addressing well-being and post-pandemic online education. Providing support to university students to improve their resilience against the impact on their studying, campus life, health, and well-being should be prioritized during and post-pandemic
Model predictive direct power control of three-level T-type inverter-fed doubly-fed induction generator for wind energy system
The paper proposes a simplified direct power control strategy of a doubly-fed induction generator fed by a three-level T-type inverter based on finite control set model predictive control. A mathematical model based on grid voltage orientation was employed to determine the predictive values of the stator flux, rotor current, and capacitor voltages for all feasible rotor-side inverter output voltages. The active and reactive powers were calculated by using the grid voltage and the rotor current. A cost function was applied to track the active and reactive powers, maintain the balance of capacitor voltages, and reduce the common-mode voltage. The best switching control input was chosen by minimizing the cost function and implemented to the inverter. Different operating conditions of wind turbine systems were studied with Matlab/Simulink environment. The simulation results validate the improved performance of the proposed method compared with the classical control in terms of transient response and steady-state conditions
Endovascular intervention with intravascular ultrasound guidance of very early dissection complication in transplant renal artery: a case report and literature review
BackgroundTransplant renal artery dissection (TRAD) is a rare and serious event that can cause allograft dysfunction and eventually graft loss. Most cases are managed by operative repair. We report a case of TRAD in the early postoperative period, which was successfully managed with intravascular ultrasound-assisted endovascular intervention.Case presentationA 38-year-old man underwent HLA-compatible living kidney transplantation. The allograft had one renal artery and vein, which were anastomosed to the internal iliac artery and external iliac vein, respectively. Doppler ultrasonography performed a day after the operation showed an increase in systolic blood velocity, with no observed urine output and raising a suspicion of arterial anastomotic stenosis. Angiography showed a donor renal artery dissection distal to the moderately stenosed anastomosis site with calcified atherosclerotic plaque confirmed by IVUS. The transplant renal artery lesion was intervened with a stent. After the intervention, Doppler US revealed that the blood flow of the renal artery was adequate without an increase in the systolic blood velocity. Urine output gradually returned after 3 weeks, and serum creatinine level was normalized after 2 months.ConclusionsTransplant recipients commonly have atherosclerosis and hypertension, which are risk factors for arterial dissection. Our case showed that endovascular intervention can replace surgery to repair very early vascular complications such as dissection and help patients avoid high-risk operations. Early diagnosis and IVUS-assisted intervention with experienced interventionists can save allograft dysfunction
A hierarchical architecture for increasing efficiency of large photovoltaic plants under non-homogeneous solar irradiation
Under non-homogeneous solar irradiation, photovoltaic (PV) panels receive different solar irradiance, resulting in a decrease in efficiency of the PV generation system. There are a few technical options to fix this issue that goes under the name of mismatch. One of these is the reconfiguration of the PV generation system, namely changing the connections of the PV panels from the initial configuration to the optimal one. Such technique has been widely considered for small systems, due to the excessive number of required switches. In this paper, the authors propose a new method for increasing the efficiency of large PV systems under non-homogeneous solar irradiation using Series-Parallel (SP) topology. In the first part of the paper, the authors propose a method containing two key points: a switching matrix to change the connection of PV panels based on SP topology and the proof that the SP-based reconfiguration method can increase the efficiency of the photovoltaic system up to 50%. In the second part, the authors propose the extension of the method proposed in the first part to improve the efficiency of large solar generation systems by means of a two-levels architecture to minimize the cost of fabrication of the switching matrix
Menstruation-Related Symptoms and Associated Factors among Female University Students in Vietnam
Menstruation and menstrual-related symptoms, stress, and lifestyle factors can significantly affect the health and academic lives of university students. This study aimed to explore menstruation-related symptoms and associated factors among female university students in Vietnam. This study used a cross-sectional design. Data from 349 students were analyzed for menstrual and menstrual-related symptoms using the Menstrual Distress Questionnaire (MDQ). We found that 92.0% and 98.9% of the students had menstrual-related symptoms in the pre- and intra-menstrual phases, respectively. The most common symptoms in each phase were backache (71.1%) in the pre-menstrual phase and fatigue (90.3%) in the intra-menstrual phase. Menstruation-related symptoms were associated with stress. These results contribute significantly to our understanding of menstrual health among Vietnamese university students. These findings imply the need to strengthen support systems for university students, especially by providing proper information about menstruation and managing stress
Impact of pasteurisation and storage conditions on the physicochemical properties of acerola jelly
Acerola, a fruit rich in bioactive compounds such as polyphenols and vitamin C, is highly susceptible to degradation under temperature influences. This study aimed to evaluate the impact of pasteurisation and storage conditions on the stability of these compounds in acerola jelly. Analytical findings revealed that thermal treatment at 80°C for 5 minutes effectively eradicated total aerobic bacteria and mould yeast content. Furthermore, this treatment preserved the vitamin C and phenolic content, as well as the sensory quality of the jelly, better than other samples. The study also discovered that during storage, the degradation of vitamin C and polyphenols in acerola jelly adhered to the first-order model and the Arrhenius model. In contrast, attributes such as total soluble solids (TSS), pH, and titratable acidity (TA) remained constant during pasteurisation and storage. Kinetic parameters, including D-value, k-value, z-value, and activation energy (Ea), indicated high stability of the product when stored at a low temperature of 4-6oC. These findings suggest that acerola jelly has considerable potential for commercial production
Association between ACE I/D genetic polymorphism and the severity of coronary artery disease in Vietnamese patients with acute myocardial infarction
BackgroundThe severity of coronary artery disease is a prognostic factor for major adverse cardiovascular events in patients diagnosed with acute myocardial infarction. ACE I/D polymorphism is one of the genetic factors that may affect the severity of coronary artery disease. This study aimed to investigate the association between ACE I/D genotypes and the severity of coronary artery disease in patients with acute myocardial infarction.Materials and methodsA single-center, prospective, observational study was conducted at the Department of Cardiology and Department of Interventional Cardiology, Cho Ray Hospital, Ho Chi Minh City, Vietnam from January 2020 to June 2021. All participants diagnosed with acute myocardial infarction underwent contrast-enhanced coronary angiography. The severity of coronary artery disease was determined by Gensini score. ACE I/D genotypes were identified in all subjects by using the polymerase chain reaction method.ResultsA total of 522 patients diagnosed with first acute myocardial infarction were recruited. The patients' median Gensini score was 34.3. The II, ID, and DD genotype rates of ACE I/D polymorphism were 48.9%, 36.4%, and 14.7%, respectively. After adjusting for confounding factors, multivariable linear regression analysis showed that the ACE DD genotype was independently associated with a higher Gensini score compared with the II or ID genotypes.ConclusionThe DD genotype of the ACE I/D polymorphism was associated with the severity of coronary artery disease in Vietnamese patients diagnosed with first acute myocardial infarction
ARtVista: Gateway To Empower Anyone Into Artist
Drawing is an art that enables people to express their imagination and
emotions. However, individuals usually face challenges in drawing, especially
when translating conceptual ideas into visually coherent representations and
bridging the gap between mental visualization and practical execution. In
response, we propose ARtVista - a novel system integrating AR and generative AI
technologies. ARtVista not only recommends reference images aligned with users'
abstract ideas and generates sketches for users to draw but also goes beyond,
crafting vibrant paintings in various painting styles. ARtVista also offers
users an alternative approach to create striking paintings by simulating the
paint-by-number concept on reference images, empowering users to create
visually stunning artwork devoid of the necessity for advanced drawing skills.
We perform a pilot study and reveal positive feedback on its usability,
emphasizing its effectiveness in visualizing user ideas and aiding the painting
process to achieve stunning pictures without requiring advanced drawing skills.
The source code will be available at https://github.com/htrvu/ARtVista.Comment: CHI 202
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