139 research outputs found
Status Poles and Status Zoning to Model Residential Land Prices: Status-Quality Trade off Theory (Short Paper)
This study describes an approach for augmenting urban residential preference and hedonic house price models by incorporating Status-Quality Trade Off theory (SQTO). SQTO seeks explain the dynamic of urban structure using a multipolar, in which the location and strength of poles is driven by notions of residential status and dwelling quality. This paper presents in outline an approach for identifying status poles and for quantifying their effect on land and residential property prices. The results show how the incorporation of SQTO results in an enhanced understanding of variations in land / property process with increased spatial nuance. A number of future research areas are identified related to the status pole weights and the development of status pole index
Assimilation of SMAP products for improving streamflow simulations over tropical climate region — is spatial information more important than temporal information?
Streamflow is one of the key variables in the hydrological cycle. Simulation and forecasting of streamflow are challenging tasks for hydrologists, especially in sparsely gauged areas. Coarse spatial resolution remote sensing soil moisture products (equal to or larger than 9 km) are often assimilated into hydrological models to improve streamflow simulation in large catchments. This study uses the Ensemble Kalman Filter (EnKF) technique to assimilate SMAP soil moisture products at the coarse spatial resolution of 9 km (SMAP 9 km), and downscaled SMAP soil moisture product at the higher spatial resolution of 1 km (SMAP 1 km), into the Soil and Water Assessment Tool (SWAT) to investigate the usefulness of different spatial and temporal resolutions of remotely sensed soil moisture products in streamflow simulation and forecasting. The experiment was set up for eight catchments across the tropical climate of Vietnam, with varying catchment areas from 267 to 6430 km2 during the period 2017–2019. We comprehensively evaluated the EnKF-based SWAT model in simulating streamflow at low, average, and high flow. Our results indicated that high-spatial resolution of downscaled SMAP 1 km is more beneficial in the data assimilation framework in aiding the accuracy of streamflow simulation, as compared to that of SMAP 9 km, especially for the small catchments. Our analysis on the impact of observation resolution also indicates that the improvement in the streamflow simulation with data assimilation is more significant at catchments where downscaled SMAP 1 km has fewer missing observations. This study is helpful for adding more understanding of performances of soil moisture data assimilation based hydrological modelling over the tropical climate region, and exhibits the potential use of remote sensing data assimilation in hydrology
Assessment of Antioxidant and Antibacterial Activities of Lactobacillus farciminis HN11 as a Probiotic Candidate
Background and Objective: Lactobacillus farciminis is an obligate homofermentative bacterial species in fermented foods. Although other species such as Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei and Lactobacillus rhamnosus in Lactobacillus genus have been well characterized, probiotic characteristics of Lactobacillus farciminis still need to investigate. Thus, the objective of this study was to investigate probiotic characteristics and antibacterial activity of Lactobacillus farciminis HN11 isolated from Solanum macrocarpon sauces in Hue city, Vietnam.
Material and Methods: Lactobacillus farciminis HN11 was cultured in Rogosa and Sharpe media and antibacterial activity of the free-cell suspension was assessed against Escherichia coli, Vibrio parahaemolyticus K5, Vibrio parahaemolyticus KS-02, Vibrio owensii KS-05, Vibrio alginolyticus KS-08, Vibrio alginolyticus A1-1 and Staphylococcus aureus using agar well diffusion method. Various probiotic characteristics of the isolate including antibacterial and antioxidant activities, autoaggregation and coaggregation were assessed. Furthermore, hemolytic and amino-acid dercarboxylase activities were assessed for biosafety assessment. The strain abilities to resist sodium chloride and bile salts were assessed as well.
Results and Conclusion: Lactobacillus farciminis HN11 exhibited significant resistance to NaCl and bile salts. The strain expressed high coaggregation abilities for Escherichia coli, significant autoaggregation abilities and antibacterial activities against Vibrio spp. and Escherichia coli. Antioxidant assessment showed that Lactobacillus farciminis HN11 contained high antioxidant activities. This strain was negative for hemolytic and amino-acid dercarboxylase activities. Moreover, ampicillin and chloramphenicol inhibited growth of Lactobacillus farciminis HN11. This study assessed characteristics of Lactobacillus farciminis HN11 and showed its great potentials as a probiotic in fermented foods, enhancing antioxidant and decreasing harmful foodborne bacteria. Although, encapsulation of the strain within acid resistance materials is suggested to better protect it against high-acid contents of the stomach.
Conflict of interest: The authors declare no conflict of interest
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
Fractional flow reserve in assessment of intermediate non-culprit lesions in acute myocardial infarction
Context: Percutaneous coronary intervention (PCI) of intermediate non-culprit arteries can reduce death or heart attack risk in patients with acute myocardial infarction and multivessel coronary artery disease.
Aims: To compare the effectiveness of fractional flow reserve (FFR)-guided PCI with angiography-guided PCI for intermediate non-culprit lesions in patients with acute myocardial infarction and multivessel coronary artery disease.
Methods: In this cohort study, acute myocardial infarction patients with multivessel coronary artery disease who had successful percutaneous coronary intervention of the culprit artery were divided into group of patients receiving FFR-guided PCI (FFR≤0.80, n = 31) and group of patients receiving angiography-guided PCI (diameter stenosis of 50-90%, n = 62) for lesions in non-culprit arteries. These two groups were followed for at least 1 year for major adverse cardiovascular events.
Results: There was no statistically significant difference in major cardiovascular events between FFR-guided percutaneous coronary intervention group and angiography-guided percutaneous coronary intervention group. However, FFR-guided percutaneous coronary intervention group had a lower mortality rate compared to the angiography-guided percutaneous coronary intervention group (3.2% vs. 4.8%). Additionally, there were no reported cases of myocardial infarction in angiography-guided PCI group, while angiography-guided PCI group had a rate of 1.6%.
Conclusions: This study found that it remains uncertain whether FFR-guided PCI is superior than angiography-guided PCI for intermediate non-culprit lesions in patients with acute myocardial infarction and multivessel coronary artery disease
On the Out of Distribution Robustness of Foundation Models in Medical Image Segmentation
Constructing a robust model that can effectively generalize to test samples
under distribution shifts remains a significant challenge in the field of
medical imaging. The foundational models for vision and language, pre-trained
on extensive sets of natural image and text data, have emerged as a promising
approach. It showcases impressive learning abilities across different tasks
with the need for only a limited amount of annotated samples. While numerous
techniques have focused on developing better fine-tuning strategies to adapt
these models for specific domains, we instead examine their robustness to
domain shifts in the medical image segmentation task. To this end, we compare
the generalization performance to unseen domains of various pre-trained models
after being fine-tuned on the same in-distribution dataset and show that
foundation-based models enjoy better robustness than other architectures. From
here, we further developed a new Bayesian uncertainty estimation for frozen
models and used them as an indicator to characterize the model's performance on
out-of-distribution (OOD) data, proving particularly beneficial for real-world
applications. Our experiments not only reveal the limitations of current
indicators like accuracy on the line or agreement on the line commonly used in
natural image applications but also emphasize the promise of the introduced
Bayesian uncertainty. Specifically, lower uncertainty predictions usually tend
to higher out-of-distribution (OOD) performance.Comment: Advances in Neural Information Processing Systems (NeurIPS) 2023,
Workshop on robustness of zero/few-shot learning in foundation model
THIẾT LẬP CHỈ SỐ CHẤT LƯỢNG NƯỚC DỰA VÀO PHÂN TÍCH THỐNG KÊ: ÁP DỤNG CHO SÔNG HƯƠNG, TỈNH THỪA THIÊN HUẾ
Huong River’s water quality was preliminarily assessed by comparing the parameters monitored with the Vietnam Technical Regulation on Surface Water Quality. The river water quality was then assessed based on Water Quality Index (WQI). Principal Component Analysis (PCA) was applied to the river water quality data during 2017–2020 to determine the weighting (wi) of the ith water quality parameter for WQI calculation. The WQI was calculated both from wi and subindex (qi). The parameters selected (n = 11) for WQI calculation consisted of pH, EC (electric conductivity), DO, TSS, BOD5, COD, N-NH4+, N-NO3–, P-PO43–, Fe (total dissolved iron), and TC (total coliform). The parameters were monitored at 8–10 sites in 4–5 sessions (February, May, August, and November). The results show that 95% of WQI at 90–100 corresponds to water quality level ‘good’ and ‘excellent’; only 5% of WQI values at 49–77 (mainly in November 2020) corresponds to the level from ‘bad’ to ‘good’. In the flood-rainy season, the increase in concentrations of TSS and Fe and the decrease in DO concentration lead to a reduction in WQI. The river water quality was not significantly differed by space/monitoring sites (p > 0,05) with median WQIs of 97–100 but varied over time: the years 2017 and 2019 had median WQIs (99), higher than that in the years 2018 and 2020 (97) with p < 0,01.Chất lượng nước (CLN) sông Hương được đánh giá sơ bộ qua so sánh các thông số quan trắc với quy định kỹ thuật Việt Nam về CLN mặt. Tiếp theo, CLN sông được đánh giá qua Chỉ số chất lượng nước (WQI). Phương pháp phân tích thành phần chính (PCA) được áp dụng cho dữ liệu CLN sông giai đoạn 2017–2020 để xác định trọng số (wi) của thông số CLN i trong tính toán WQI. Chỉ số chất lượng nước được tính từ cả trọng số và chỉ số phụ (qi). Các thông số được lựa chọn để tính WQI gồm (n = 11): pH, EC (độ dẫn điện), DO, TSS, BOD5, COD, N-NH4+, N-NO3–, P-PO43–, Fe (tổng sắt tan) và TC (tổng coliform). Các thông số đó được quan trắc ở 8–10 vị trí trong 4–5 đợt (tháng 2, 5, 8 và 11). Kết quả cho thấy, 95% các giá trị WQI nằm trong khoảng 90–100, ứng với CLN loại ‘tốt’ và ‘rất tốt’; chỉ 5% các giá trị WQI nằm trong khoảng 49–77 (chủ yếu vào tháng 11/2020), ứng với CLN loại ‘xấu’ đến ‘tốt’. Vào mùa mưa lũ, nồng độ TSS và Fe tăng lên, nồng độ DO giảm, dẫn đến làm giảm WQI. Chất lượng nước sông không khác nhau có ý nghĩa thống kê theo không gian/vị trí quan trắc (p > 0,05) với WQI trung vị 97–100 nhưng khác nhau theo thời gian: năm 2017 và 2019 có WQI trung vị (99) lớn hơn năm 2018 và 2020 (WQI trung vị 97) với p < 0,01
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