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Understanding the relationship between tree species diversity and above-ground carbon (AGC) storage in tropical forests is essential for a sustainable flow of ecosystem goods and services. Although tropical forests of Vietnam are of particular interest due to their high biodiversity and carbon density, few studies have evaluated the relative importance of species composition, tree species diversity and forest structure on AGC storage by forest vegetation type. In this study, we tested for the influence of taxonomic diversity, forest structure and species composition on AGC storage in evergreen broad-leaved and deciduous forests of Southeast Vietnam. Data was collected within 137 rectangular plots (25 m × 20 m), randomly selected across a deciduous forest (DF) and four evergreen broad-leaved forest (EB) categories, with different stand­ing volumes levels: very poor (EBG), poor (EBP), medium (EBM) and rich (EBR). In total, we identified 3687 individuals from 110 tree species belonging to 46 families in 6.85 hectares of sampled area. AGC stor­age significantly differed among forest categories, ranging from 14.81 Mg ha−1 in EBG to 146.74 Mg ha−1 in EBR. There was higher AGC in the medium diameter class (20-40 cm), except for EBR where there was higher AGC within individuals of 40-60 cm in diameter. Taxonomic diversity was weakly correlated with AGC while stand structure (stem density and maximum diameter) were strongly correlated. Our results suggest that maintaining the abundance distributions of remnant tree species, particularly that of large trees, is one important method to enhance AGC storage in the tropical ecosytems of southern Vietnam.

Objective: To describe several clinical and subclinical characteristics of patients with first diagnosed prostate cancer at 108 Military Central Hospital. Subject and method: A retrospective study was performed on 312 patients with first diagnosed prostate cancer in Department of Urology, 108 Military Central Hospital, from January 1st, 2016, to December 31st, 2020. Main research criteria: age, symptoms of urinary disorders, total PSA, signs of bone metastases, and Gleason score. Result: Mean age was 73.9-year-old, frequent clinical symptoms were urinary hesitancy 51% and acute urinary retention 32.4%; mean prostate volume was 61.1ml; the rate of carcinoma was 99.6%; most of cases had high PSA (³ 20ng/ml) and very high (³ 100ng/ml); 63.7% of cases had signs of bone metastases at the time of diagnosis. Conclusion: Prostate cancer is mainly late diagnosed; the rate of adenocarcinoma accounted for 99.6%.

Tree species inventories, particularly of poorly known dry forests, are necessary to protect and restore them in degraded landscapes. The present research has been conducted to compare taxonomic diversity and community composition in four dry forests (DF) categories with different standing volume levels: very low (DFV), low (DFP), medium (DFM) and high (DFR). This quantitative assessment of taxonomic diversity, forest structure and species composition were obtained from 103 sample plots (0.1 ha each). The regeneration potential of trees was assessed in 515 subplots (4 m × 4 m) located within the 103 plots. A total of 1,072 trees representing 87 species belonging to 37 families were recorded in 10.3 ha of total sampled area. The ranges of diversity indices observed in the four forest types were: Margalef's (5.44–8.43), Shannon-Wiener (1.80–2.29), Simpson diversity (0.76–0.87) and evenness (0.32–0.35). The regeneration potential of rare and threatened species Dalbergia oliveri, Hopea recopei, Dalbergia bariensis, Sindora siamensis, Parashorea stellata was observed to be poor. Conversely, Cratoxylon formosum, Shorea obtusa, Dipterocarpus tuberculatus, Dipterocarpus obtusifolius, Terminalia alata, Shorea siamensis and Xylia xylocarpa were the most dominant species at the seedling and sapling stage, showing a strong potential for regeneration. Overall, this study provides useful information on tree species diversity and composition for tropical dry forests which can be used as baseline data to develop incoming plans for forest management and conservation in Vietnam's Central Highlands Region.

The assessment of carbon stocks is one of the key measurements to support climate change mitigation policies. The research applied Landsat 8 satellite imagery combined with field-measurements using four machine learning methods (random forest - RF, artificial neural networks - NNET, support vector machines – SVM, and linear regression - LM) to estimate aboveground carbon in evergreen broadleaf forest in Binh Phuoc province. The field sample plots were randomly divided into training (96 plots) and testing (24 plots) data. The results showed that RF yielded the greatest precision with an R2 value above 0,9 and RMSE below 6 ton/ha on the training data, with an R2 value of 0,41 and RMSE of 11,04 ton/ha on the testing data. The estimate of forest carbon stock increased distinctly from the mean value of 59,80 ton/ha in the very poor forest to 87,78 ton/ha in the rich forest. The results found in the present study demonstrated that Landsat 8 imagery in conjunction with RF has the appropriate to estimate aboveground carbon stock in evergreen broadleaf forest-leaved in Binh Phuoc province. Keywords: Random forest, aboveground carbon, REDD+, forest carbon estimation.

This article analyses the cause of the freezing phenomenon on the tip and body of the end part of the injector (EPI) assembly in a LPG injection system. Based on the physical properties of LPG, fuel injection conditions, environmental conditions, material parameters, shape and size of the EPI of the LPG injector assembly, and thermodynamic process taking place in the EPI tube, we established a calculation model to determine the pressure course of LPG in the tube. Results of the pressure courses measured in the experiment and calculation model have proven to be similar. The calculation model showed that it was not possible to manufacture an EPI using changes in material, shape and size to completely eliminate freezing. However, adjusting input parameters for EPI size and shape enabled us to determine the optimal geometry of the EPI and showed the need for a heating element device to deal with freezing on the tip and body of the EPI. An experiment on the EPI with a heating element device demonstrated the effectiveness of this solution.

Background Vietnam possesses a vast diversity of rice landraces due to its geographical situation, latitudinal range, and a variety of ecosystems. This genetic diversity constitutes a highly valuable resource at a time when the highest rice production areas in the low-lying Mekong and Red River Deltas are enduring increasing threats from climate changes, particularly in rainfall and temperature patterns. Results We analysed 672 Vietnamese rice genomes, 616 newly sequenced, that encompass the range of rice varieties grown in the diverse ecosystems found throughout Vietnam. We described four Japonica and five Indica subpopulations within Vietnam likely adapted to the region of origin. We compared the population structure and genetic diversity of these Vietnamese rice genomes to the 3000 genomes of Asian cultivated rice. The named Indica-5 (I5) subpopulation was expanded in Vietnam and contained lowland Indica accessions, which had very low shared ancestry with accessions from any other subpopulation and were previously overlooked as admixtures. We scored phenotypic measurements for nineteen traits and identified 453 unique genotype-phenotype significant associations comprising twenty-one QTLs (quantitative trait loci). The strongest associations were observed for grain size traits, while weaker associations were observed for a range of characteristics, including panicle length, heading date and leaf width. Conclusions We showed how the rice diversity within Vietnam relates to the wider Asian rice diversity by using a number of approaches to provide a clear picture of the novel diversity present within Vietnam, mainly around the Indica-5 subpopulation. Our results highlight differences in genome composition and trait associations among traditional Vietnamese rice accessions, which are likely the product of adaption to multiple environmental conditions and regional preferences in a very diverse country. Our results highlighted traits and their associated genomic regions that are a potential source of novel loci and alleles to breed a new generation of low input sustainable and climate resilient rice.

There are tens of typical volcano-related relics such as craters and waterfalls in the Pleiku volcanic plateau, Gia Lai province however, Gia Lai’s tourism has underdeveloped. Thus it is vital finding the specific tourist products to promote the provincial nonsmoking industry. Quantifying conservative values of typical volcanic landscapes in the form of money would provide useful information for decision-makers to plan and develop rural tourism. This study was applied to the contingent valuation method to estimate the conservative values of twenty volcanic landscapes in the Pleiku plateau. The results indicated that Bien Ho volcanic landscape got the highest traditional value with above 38.60 billion VND. Subsequently, the conservative value of Chu Dang Ya was 27.28 billion VND. The value of the Phu Cuong waterfall was also estimated quite highly. Furthermore, our new finding is that there was a close relationship between the results coming from the conservative valuation and the results coming from evaluation, classification of geoheritages based on UNESCO’s criteria adapting in Vietnam. The study figured out that there was a close relationship between the conservative valuation and information accessibility on twenty landscapes by interviewees before.

This article presents a new kind of finline in double-layer dielectric substrate and its beamforming circuit of Butler matrix in the millimeter-wave band. The finline is constructed by inserting a slotline between two dielectric substrate layers. In this configuration, it is bounded within a closed structure composed of a double-layer dielectric substrate and two rows of via-hole arrangement, contributing to low dispersion and low radiation loss of the finline characteristics. The proposed finline design aims to provide a low-complexity and low-loss transmission line which is applied to the Butler matrix design. A 4×4 Butler matrix for 4 switchable beams is realized by using the finline in the double-layer dielectric substrate. In addition, a waveguide-to-finline transition is developed as a feeding circuit for the Butler matrix. Characteristics of the proposed transition and the Butler matrix were analyzed by electromagnetic analysis of the finite element method and demonstrated by experiments at 79 GHz. The proposed Butler matrix obtains a wideband characteristic and an acceptable insertion loss of 2.42 dB. The array factor which is calculated from the measured amplitude and phase outputs 4 switchable beams with the beam directions of +14°, -46.5°, +46.5° and -14°, respectively. The proposed beamforming circuit using finline in double-layer dielectric substrate would be attractive for millimeter-wave applications due to its performance and low cost.

After using the conventional scientific research methods, observing the steps of document synthesis, interviewing, and checking the reliability of the questionnaire through Cronbach's Alpha, the paper has come up with five quantitative assessment criteria and eight qualitative assessment questions of the content and forms of extracurricular sports activities for students at secondary schools in Tay Ninh province. This research has contributed to renewing the content and forms of extracurricular sports activities for students at secondary school. Article visualizations

The paper aims to provide a comprehensive, scientific and thorough description of the content and methods of how extra-curricular sports activities are conducted for lower secondary school students in Tay Ninh province. To investigate the dependable data, the research employed a range of trustworthy approaches including document synthesizing, interviewing the students and PE teachers in some lower secondary schools, and evaluating the gathered data. The results indicate that the most popular sports among the PE teachers and students are football, badminton, and volleyball which are mostly organized in group, class, and club practice, without an instructor. About the practice durations, it generally ranges from thirty minutes to two hours, equating to two or three sessions at school. Moreover, these activities usually take place in school, and it is mainly held in the afternoon or after theoretical learning. Article visualizations

Objective: To evaluate the treatment of renal pelvis stone by retrograde ureteroscopy using holmium laser at 103 Military Hospital. Subject and method: A prospective longitudinal clinical description was performed from April 2018 to April 2020 on 57 patients (33 male and 24 female patients). Result: The success rate was 100%, the rate of fragments migrated into the renal calices was 10.5%, conversion rate to open surgery was 0%, stone free rate was 93%, intra-operative complication rate was 0%, post-operative complication rate was 1.8%. Conclusion: Endoscopic retrograde using holmium laser is a safe and effective treatment method for renal pelvis stone.