Một số nét giới thiệu tổng quan về mạng máy tính

Một số nét giới thiệu tổng quan về mạng máy tính

Một cơ chế quản lý hàng đợi tích cực cải tiến VBLUE trên môi trường truyển video

The rapid development of video streaming applications over the internet poses a growing challenge. The requirements for bandwidth capacity and latency of transmission package often change constantly. One of the queue management mechanisms commonly used to increase the performance and prevent the degradation of video transmission quality is the active queue management mechanism (AQM). However, though the internet is a good effort network it does not have distinctions among transmission packets on the network leading to a significant percentage of video data packet discarded by the network router upon the occurrence of lacking bandwidth on the traffic lines due to congestion. The impact of the lost video package degrading the quality of watching at the receiver may vary from negligible to unacceptable levels. This paper proposes an innovative solution using selected VBLUE to discard the package which is built in the BLUE active queue management mechanism. The simulation results on NS-2 are given to show the efficiency of VBLUE for increasing the significant quality of video streaming.Sự phát triển nhanh chóng các ứng dụng truyền video trên Internet đặt ra những thách thức ngày càng lớn. Các yêu cầu về khả năng băng thông và độ trễ truyền dẫn gói tin thường biến đổi liên tục. Một trong các cơ chế quản lý hàng đợi thường được sử dụng để tăng hiệu năng mạng và ngăn cản sự suy giảm chất lượng truyền video là cơ chế quản lý hàng đợi tích cực (AQM). Tuy nhiên, do mạng Internet là mạng mặc dù được xây dựng với nỗ lực tối đa nhưng chưa thể đảm bảo về QoS (best-effort network) và không có sự phân biệt giữa các gói tin truyền trên mạng dẫn đến tỷ lệ đáng kể các gói dữ liệu video bị loại bỏ bởi các bộ định tuyến mạng khi xảy ra tình trạng thiếu băng thông trên các đường truyền do bị tắc nghẽn. Ảnh hưởng của việc mất gói tin video làm suy giảm chất lượng xem ở phía máy nhận có thể thay đổi từ không đáng kể đến mức không thể chấp nhận được. Bài báo này đề xuất một giải pháp cải tiến VBLUE sử dụng lựa chọn loại bỏ gói tin được tích hợp ngay trong cơ chế hàng đợi tích cực BLUE. Các kết quả mô phỏng trên NS-2 đã cho thấy hiệu quả của VBLUE làm tăng chất lượng phát luồng video một cách đáng kể.  

Research on Factors Affecting Credit Risk of Joint Stock Commercial Banks on Vietnam Stock Market

Design/methodology/approach: The article aims at identifying factors affecting credit risk of commercial banks in Vietnam. The study uses data collected from financial statements of 15 typical joint stock commercial banks out of a total of 27 joint stock commercial banks listed on the Vietnam stock exchange from 2012 to 2022 with panel data of 15 joint stock commercial banks for the period 2012 - 2022. The banks in the research data are the those with the largest total assets in the banking system. After collecting and processing data, research sample includes 165 observations and the study uses E-view software in quantitative analysis to build a regression model to determine the relationship and level of influence of Internal factors to credit risk of listed joint stock commercial banks.   Findings: Research results indicate that factors affecting credit risk of listed joint stock commercial banks include: Ratio of equity to total assets, capital structure of the bank, and operational performance of the banks.   Research, Practical & Social impications: These results confirm the importance of taking into account micro finance factors when making financing. Understanding the impact of these factors and relationships contributes to decision and risk management.   Originality/value: In order to limit credit risk it is necessary to focus on: Ensuring reasonable equity; Stricter control over loan capital; Optimal use of resources

Rheological properties of emulsion of crude oil and water

In the paper the rheological properties of crude oil of White Tiger oil-field (Vietnam) and its emulsion with sea-water, including measurement results and analytical approximation formulae for wide range of pressure, temperature and water concentration, are presented. As it is known, the crude oil of White Tiger oil-field is a high-paraffin and high-viscous oil. At the low temperature (T ≤ 40°C) it behaves as non-Newtonian fluid of Bingham-Shvedov group. Therefore, beside the effective viscosity, the effective dynamic shear stress is also measured and approximated. The rheological properties of crude oil and emulsion of crude oil and water are also measured and approximated for the case when the mixture contains 0.1% chemical reagent ES-3363

Targeting effect of folate on cancer cell through curcumin carrier nano-system

Folate receptor (FR) is well known for its overexpression on surface of various cancer cell lines, which is identical to normal tissue. Folic-based targeting drug delivery systems, therefore, are one of the most effective targeting carriers that effectively bind to FR up-regulated cancer cells. Curcumin was used both for labeling and chemotherapy. The materials were characterized and structurally confirmed by FT-IR spectra, fluorescent images and FE-SEM images. Bioassays were conducted on HeLa and HT29 cancer cell lines after 4 and 12 hours. Results show that folic acid significantly enhanced both targeting efficiency and internalization of curcumin to FR-expressing cancer cells

KẾT QUẢ NGHIÊN CỨU VỀ ĐỘNG LỰC TRẦM TÍCH LƠ LỬNG TRONG MÙA KHÔ TẠI VÙNG BIỂN VEN BỜ CỬA SÔNG HẬU

During the dry season (April 2014 and March 2015), the program of cooperation in science and technology between Vietnam and the United States and the independent project VAST-DLT.06/15-16 have conducted two surveys aiming to investigate deposition and sptial and temporal distribution of suspended sediment concentration under the domination by hydrodynamic processes such as wave, current, river flow. In addition, we also investigated the effect of tidal current in relationship with concentration of suspended sediment. Three 12-hour continuous monitoring stations of suspended sediment factors, water level and current are located on the topset at a depth of 8 m, the foreset at a depth of 15 m and the bottomset at a depth of 25 m, with a distance between the two stations about 3 km. In which, the concentrations of suspended sediment (SSCs) in the range of particle sizes from 1.25 μm to 250 μm and particle diameter are measured by LISST-25x (Suspended Sediment Sensor), water level, velocity and current direction are measured by the ADCP. Results of data analysis show that the distributions of particle diameter of suspended sediment over time on the topset, the foreset and the bottomset are different and do not change much under tidal phases. Meanwhile, the concentrations of suspended sediment (SSCs) correlate with velocity and fluctuate under tidal phases. Suspended sediment is deposited at tidal transition and reactivates when current velocities increase in flood and ebb tide phases. The survey data show that the increase of current velocity during flood tide phase causes re-suspension of bottom sediments and increases the concentration of suspended sediment. At flood tide phase corresponding to strong velocity, suspended sediment moves faster and vice versa at ebb tide phase, smaller current velocity makes the movement speed of suspended sediment slow.Trong mùa khô (tháng 4 năm 2014 và tháng 3 năm 2015), chương trình hợp tác khoa học và công nghệ giữa Việt Nam và Hoa Kỳ, và đề tài độc lập mã số VAST-ĐLT.06/15-16 đã thực hiện 2 chuyến khảo sát nhằm mục đích điều tra sự lắng đọng và phân bố theo không gian, thời gian của hàm lượng trầm tích lơ lửng dưới sự chi phối chủ yếu bởi các quá trình thủy động lực như sóng, dòng chảy, lưu lượng nước sông. Ngoài ra, chúng tôi còn khảo sát ảnh hưởng của dòng triều trong mối tương quan với hàm lượng trầm tích lơ lửng. Ba trạm đo liên tục trong 12 giờ các yếu tố trầm tích lơ lửng, mực nước và dòng chảy được đặt trên thềm châu thổ (topset) ở độ sâu 8 m, sườn châu thổ (foreset) ở độ sâu 15 m và chân châu thổ (bottomset) ở độ sâu 25 m, các trạm được đặt cách nhau 3 km. Trong đó, nồng độ trầm tích lơ lửng (SSCs) trong giới hạn kích thước hạt từ 1,25 µm đến 250 µm và đường kính hạt được đo bằng máy LISST-25X (Suspended Sediment Sensor), mực nước, vận tốc và hướng dòng chảy được đo bằng máy ADCP. Kết quả phân tích số liệu cho thấy phân bố đường kính hạt của trầm tích lơ lửng theo thời gian trên thềm châu thổ, sườn châu thổ, chân châu thổ là khác nhau và chúng không biến động nhiều theo pha triều. Trong khi đó, hàm lượng trầm tích lơ lửng (SSCs) tương quan với vận tốc dòng chảy và dao động theo pha triều. Trầm tích lơ lửng lắng đọng vào lúc thuỷ triều chuyển trạng thái (từ triều rút sang triều dâng hoặc ngược lại) và được tái hoạt động trở lại khi tốc độ dòng chảy tăng trong pha triều lên và pha triều xuống. Các số liệu khảo sát cho thấy rằng sự tăng của tốc độ dòng chảy trong pha triều lên đã gây ra sự tái lơ lửng của trầm tích đáy và làm tăng hàm lượng trầm tích lơ lửng. Tại các pha triều lên ứng với vận tốc dòng chảy lớn, trầm tích lơ lửng được dịch chuyển nhanh hơn và ngược lại tại pha triều xuống, tốc độ dòng chảy thấp hơn đã làm tốc độ dịch chuyển của trầm tích chậm lại

Two decades of studies on learning management system in higher education: A bibliometric analysis with Scopus database 2000-2020

Over the past twenty years, using learning management systems in higher education has attracted increasing interest from researchers around the globe. In this context, the current study aimed to explore the volume, growth trajectory, and geographic distribution of learning management systems in higher education literature, along with identifying impactful authors, sources, and publications, and highlight emerging research issues. The authors conducted bibliometric analysis on 1334 documents, related to the use of learning management systems in the context of higher education, extracted from Scopus database. The findings show a rapidly growing knowledge base on learning management systems in higher education, especially intensely in the years 2015-2020 and primarily from research in developed societies. This flourishing is consistent with the development trend of international education and the strong development of technology. In addition, the core literature was identified based on the volume of publications and citations. The results also reveal the emerging intellectual structure of the field and provide points of reference for scholars studying the discipline. This paper offers a knowledge map for future research assessments of learning management systems in higher education

Targeting effect of folate on cancer cell through curcumin carrier nano-system

Folate receptor (FR) is well known for its overexpression on surface of various cancer cell lines, which is identical to normal tissue. Folic-based targeting drug delivery systems, therefore, are one of the most effective targeting carriers that effectively bind to FR up-regulated cancer cells. Curcumin was used both for labeling and chemotherapy. The materials were characterized and structurally confirmed by FT-IR spectra, fluorescent images and FE-SEM images. Bioassays were conducted on HeLa and HT29 cancer cell lines after 4 and 12 hours. Results show that folic acid significantly enhanced both targeting efficiency and internalization of curcumin to FR-expressing cancer cells

A Bibliometric Analysis of the Global Research Trend in Child Maltreatment

Child maltreatment remains a major health threat globally that requires the understanding of socioeconomic and cultural contexts to craft effective interventions. However, little is known about research agendas globally and the development of knowledge-producing networks in this field of study. This study aims to explore the bibliometric overview on child maltreatment publications to understand their growth from 1916 to 2018. Data from the Web of Science Core Collection were collected in May 2018. Only research articles and reviews written in the English language were included, with no restrictions by publication date. We analyzed publication years, number of papers, journals, authors, keywords and countries, and presented the countries collaboration and co-occurrence keywords analysis. From 1916 to 2018, 47, 090 papers (53.0% in 2010–2018) were published in 9442 journals. Child Abuse & Neglect (2576 papers; 5.5%); Children and Youth Services Review (1130 papers; 2.4%) and Pediatrics (793 papers, 1.7%) published the most papers. The most common research areas were Psychology (16, 049 papers, 34.1%), Family Studies (8225 papers, 17.5%), and Social Work (7367 papers, 15.6%). Among 192 countries with research publications, the most prolific countries were the United States (26, 367 papers), England (4676 papers), Canada (3282 papers) and Australia (2664 papers). We identified 17 authors who had more than 60 scientific items. The most cited papers (with at least 600 citations) were published in 29 journals, headed by the Journal of the American Medical Association (JAMA) (7 papers) and the Lancet (5 papers). This overview of global research in child maltreatment indicated an increasing trend in this topic, with the world’s leading centers located in the Western countries led by the United States. We called for interdisciplinary research approaches to evaluating and intervening on child maltreatment, with a focus on low-middle income countries (LMICs) settings and specific contexts

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke