CONNECTING MATHEMATICS AND PRACTICE: A CASE STUDY OF TEACHING EXPONENTIAL FUNCTIONS

There is a need for teaching exponential functions to show the necessity for a better match between the knowledge of exponential functions in high schools with the practical application of it in fields. In this research, a teaching process was built in association with teaching situations to show students the relationship between mathematics and real life. The research sample included 76 students in high schools in Vietnam. Additionally, two problems of compound interest and population growth were integrated and were the main research instruments. Data were collected, including student work, and they were analyzed qualitatively. The results showed that students had improved their problem-solving skills and saw the relationship between mathematics and practice. Furthermore, there were some recommendations suggested for textbook authors and teachers. Article visualizations

Average symbol error rate analysis of reconfigurable intelligent surfaces based free-space optical link over Weibull distribution channels

Optical wireless communication (OWC) enables wireless connectivity using ultraviolet bands, infrared or visible. With its advantages features as high bandwidth, low cost, and operation in an unregulated spectrum. Free-space optical (FSO) communication systems are near terrestrial as a communication link between transceivers, the link is line-of-sight and successfully transmitted optical signals. Nevertheless, the optical signals transmissions over the FSO channels bring challenges to the system. To overcome the challenges posed by the FSO channels, the most common technique is to use relay stations, the most recent is the reconfigurable intelligent surfaces (RISs) technique. This study introduces a Weibull distribution model for a free-space optical communication link with RISs assisted, the parameter used to evaluate the performance of the system is the average symbol error rate (ASER). The RISs effect is examined by considering the influence of the transmitter beam waist radius, shape parameter, aperture radius, scale parameter, and signal-to-noise ratio on the ASER

Classification of cow’s behaviors based on 3-DoF accelerations from cow’s movements

Cow’s behavior classification helps people to monitor cow activities, thus the health and physiological periods of cows can be well tracked. To classify the behavior of cows, the data from the 3-axis acceleration sensor mounted on their neck is often used. Data acquisition and preprocessing of sensor data is required in this device. We acquire data from the 3-axis acceleration sensor mounted on the cows’neck and send to the microcontrollter. At the microcontroller, a proposed decision tree is applied in real-time manner to classify four important activities of the cows (standing, lying, feeding, and walking). Finally, the results can be sent to the server through the wireless transmission module. The test results confirm the reliability of the proposed device

Validity of two physical activity questionnaires (IPAQ and PAQA) for Vietnamese adolescents in rural and urban areas

<p>Abstract</p> <p>Background</p> <p>Although physical activity is recognised to be an important determinant of health and nutritional status, few instruments have been developed to assess physical activity in developing countries. The aim of this study was to compare the validity of the short form of the International Physical Activity Questionnaire (IPAQ) and a locally adapted version of the Physical Activity Questionnaire for Adolescents (PAQA) for use in school going adolescents in rural and urban areas in Vietnam.</p> <p>Methods</p> <p>Sixteen year old adolescents from rural areas (n = 137) and urban areas (n = 90) completed the questionnaires in 2006. Test-retest reliability was assessed by comparing registrations after 2 weeks. Criterion validity was assessed by comparison with 7 days continuous accelerometer logging. Validity of the two methods was assessed using Spearman correlation coefficient, intra class correlation coefficients (ICC) and Kappa statistics.</p> <p>Results</p> <p>Reliability of both questionnaires was poor for both the IPAQ (ICC = 0.37) and the PAQA (ICC = 0.40). Criterion validity of both questionnaires was acceptable and similar for the IPAQ (ρ = 0.21) and the PAQA (ρ = 0.27) but a significantly lower validity was observed in rural areas. Both forms poorly estimated time spent on light, moderate and vigorous physical activity. Agreement of both questionnaires to classify individuals was also low but the IPAQ performed better than the PAQA.</p> <p>Conclusion</p> <p>Both questionnaires have a similar and overall poor validity to be used as a population instrument in Vietnam. Low reliability and classification properties in rural areas call for further research for specific use in such settings.</p

Research Notes : Exotic soybean observational yield performance trial in Kien Gian province --Mekong Delta --Vietnam --dry season 1981-1982

In the light of mutual technical assistance, six soybean varieties, namely \u27Bon minori\u27 (2 lines), \u27Enrei\u27 (2 lines), \u27Akiyoshi\u27 and \u27Hyuuga\u27, were forwarded by registered mail from Japan to Vietnam in May, 1981. Due to its long postal course, soybean seed was only received in November 1981. A month later, seeds were planted on December 10, 1981, at the provincial seed farm of Kien Giang province and then harvested on February 26, 1982

Comparison of the antibacterial activity against Escherichia coli of silver nanoparticle produced by chemical synthesis with biosynthesis

The synthesis of silver nanoparticles (Ag NPs) has been carried out using different methods, mainly by biological and chemical methods; however, comparing antibacterial activity of Ag NPs synthesized by these methods has not been conducted before. In this study, silver nanoparticles (Ag NPs) were synthesized by methods using reducing agent NaBH4/carboxymethyl cellulose (CMC) and fungal strain Trichoderma asperellum (T.asperellum). The formation of silver nanoparticles was observed visually by color change and identified by Ultraviolet-visible (UV – vis) spectroscopy. The transmission electron microscopy (TEM) image illustrated almost nanoparticles with spherical shape and average diameter of 4.1 ± 0.2 nm and 2.1 ± 0.2 nm of samples produced from chemical reduction and biosynthesis respectively. Both samples after 180 days storing have been separated lightly, but the agglomeration and absorbance peak shifting were not observed which proved the high stability of synthesized Ag NPs. Antimicrobial activity against human bacterial pathogen Escherichia coli (E. coli) showed that the inhibition zone produced by “biosynthesis” and “chemical reduction” Ag NPs were 3.17 cm and 2.42 cm respectively. With nanoparticles size smaller than 2 mm, antibacterial activity of “biosynthesis” Ag NPs against E. coli was 31 % higher than “chemical reduction” Ag NPs, although the concentration of Ag NPs produced by biosynthesis was about 10-fold less

KHẢ NĂNG LƯU TRỮ CACBON CỦA THẢM CỎ BIỂN TẠI ĐẦM LĂNG CÔ, TỈNH THỪA THIÊN HUẾ

Seagrass beds play an essential role in mitigating climate change by absorbing CO2 from the atmosphere and converting carbon into biomass through photosynthesis. We used remote sensing and GIS technology with field survey data to establish the distribution and above-ground dry biomass maps of seagrass beds in 2021. A Landsat 8 OLI satellite image was used in the interpretation process. An above-ground dry biomass map was established by building the regression function between the above-ground dry biomass and the reflectance spectrum of the image bands. The overall accuracy and the Kappa coefficient of the classification process were 95.5% and 0.94. At Lang Co Lagoon, the seagrass bed area in 2021 was about 36.18 ha, distributed primarily in the area between Lang Co Town and the north of the lagoon; and scattered in the north of the lagoon, Hoi Can, Hoi Dua, and Hoi Mit. In addition, the total carbon stock of seagrasses in Lang Co Lagoon was estimated at 5.54 tons, equivalent to 20.32 tons of CO2, in which the contribution of Halodule uninervis accounted for 61% of the total carbon stock.Thảm cỏ biển đóng vai trò quan trọng trong việc giảm thiểu biến đổi khí hậu thông qua việc hấp thụ CO2 từ khí quyển và chuyển cacbon thành sinh khối nhờ quá trình quang hợp. Chúng tôi đã sử dụng công nghệ viễn thám và GIS, kết hợp với dữ liệu khảo sát thực địa, để thành lập bản đồ phân bố và sinh khối khô trên mặt đất của hệ sinh thái thảm cỏ biển tại Đầm Lăng Cô vào năm 2021. Một ảnh vệ tinh Landsat 8 OLI đã được sử dụng trong quá trình giải đoán. Một bản đồ sinh khối khô trên mặt đất được thành lập thông qua việc xây dựng hàm hồi quy giữa sinh khối khô trên mặt đất và phổ phản xạ của các kênh ảnh Landsat. Độ chính xác tổng thể và hệ số Kappa là 95,5% và 0,94. Tại Đầm Lăng Cô, diện tích thảm cỏ biển năm 2021 chiếm khoảng 36,18 ha, phân bố chủ yếu ở các khu vực giao giữa Thị trấn Lăng Cô và phía Bắc của đầm; rải rác tại phía Bắc của đầm, Hói Cạn, Hói Dừa và Hói Mít. Ngoài ra, tổng trữ lượng cacbon của cỏ biển ở Đầm Lăng Cô là 5,54 tấn cacbon, tương đương với 20,32 tấn CO2; trong đó, sự đóng góp của loài Halodule uninervis chiếm 61% tổng trữ lượng cacbon