Asymptotic nonnegative rank of matrices

The nonnegative rank of nonnegative matrices is an important quantity that appears in many fields, such as combinatorial optimization, communication complexity, and information theory. In this paper, we study the asymptotic growth of the nonnegative rank of a fixed nonnegative matrix under Kronecker product. This quantity is called the asymptotic nonnegative rank, which is already studied in information theory. By applying the theory of asymptotic spectra of V. Strassen (J. Reine Angew. Math. 1988), we introduce the asymptotic spectrum of nonnegative matrices and give a dual characterization of the asymptotic nonnegative rank. As the opposite of nonnegative rank, we introduce the notion of the subrank of a nonnegative matrix and show that it is exactly equal to the size of the maximum induced matching of the bipartite graph defined on the support of the matrix (therefore, independent of the value of entries). Finally, we show that two matrix parameters, namely rank and fractional cover number, belong to the asymptotic spectrum of nonnegative matrices

Joint exploration model based light field image coding: A comparative study

© 2017 IEEE. The recent light field imaging technology has been attracting a lot of interests due to its potential applications in a large number of areas including Virtual Reality, Augmented Reality (VR/AR), Teleconferencing, and E-learning. Light Field (LF) data is able to provide rich visual information such as scene rendering with changes in depth of field, viewpoint, and focal length. However, Light Field data usually associates to a critical problem - the massive data. Therefore, compressing LF data is one of the main challenges in LF research. In this context, we present in this paper a comparative study for compressing LF data with not only the widely used image/video coding standards, such as JPEG-2000, H.264/AVC, HEVC and Google/VP9 but also with the most recent image/video coding solution, the Joint Exploration Model. In addition, this paper also proposes a LF image coding flow, which can be used as a benchmark for future LF compression evaluation. Finally, the compression efficiency of these coding solutions is thoroughly compared throughout a rich set of test conditions

The empirical analysis of cigarette tax avoidance and illicit trade in Vietnam, 1998-2010.

Illicit trade carries the potential to magnify existing tobacco-related health care costs through increased availability of untaxed and inexpensive cigarettes. What is known with respect to the magnitude of illicit trade for Vietnam is produced primarily by the industry, and methodologies are typically opaque. Independent assessment of the illicit cigarette trade in Vietnam is vital to tobacco control policy. This paper measures the magnitude of illicit cigarette trade for Vietnam between 1998 and 2010 using two methods, discrepancies between legitimate domestic cigarette sales and domestic tobacco consumption estimated from surveys, and trade discrepancies as recorded by Vietnam and trade partners. The results indicate that Vietnam likely experienced net smuggling in during the period studied. With the inclusion of adjustments for survey respondent under-reporting, inward illicit trade likely occurred in three of the four years for which surveys were available. Discrepancies in trade records indicate that the value of smuggled cigarettes into Vietnam ranges from $100 million to$300 million between 2000 and 2010 and that these cigarettes primarily originate in Singapore, Hong Kong, Macao, Malaysia, and Australia. Notable differences in trends over time exist between the two methods, but by comparison, the industry estimates consistently place the magnitude of illicit trade at the upper bounds of what this study shows. The unavailability of annual, survey-based estimates of consumption may obscure the true, annual trend over time. Second, as surveys changed over time, estimates relying on them may be inconsistent with one another. Finally, these two methods measure different components of illicit trade, specifically consumption of illicit cigarettes regardless of origin and smuggling of cigarettes into a particular market. However, absent a gold standard, comparisons of different approaches to illicit trade measurement serve efforts to refine and improve measurement approaches and estimates

Geometric control of myogenic cell fate.

This work combines expertise in stem cell biology and bioengineering to define the system for geometric control of proliferation and differentiation of myogenic progenitor cells. We have created an artificial niche of myogenic progenitor cells, namely, modified extracellular matrix (ECM) substrates with spatially embedded growth or differentiation factors (GF, DF) that predictably direct muscle cell fate in a geometric pattern. Embedded GF and DF signal progenitor cells from specifically defined areas on the ECM successfully competed against culture media for myogenic cell fate determination at a clearly defined boundary. Differentiation of myoblasts into myotubes is induced in growth-promoting medium, myotube formation is delayed in differentiation-promoting medium, and myogenic cells, at different stages of proliferation and differentiation, can be induced to coexist adjacently in identical culture media. This method can be used to identify molecular interactions between cells in different stages of myogenic differentiation, which are likely to be important determinants of tissue repair. The designed ECM niches can be further developed into a vehicle for transplantation of myogenic progenitor cells maintaining their regenerative potential. Additionally, this work may also serve as a general model to engineer synthetic cellular niches to harness the regenerative potential of organ stem cells

A Community Hospital Antimicrobial Stewardship Program’s Assessment of Prolonged Infusion Piperacillin-tazobactam for Pseudomonas Aeruginosa Pneumonia

Background: The study aim was to determine and compare the length of hospitalization, mortality, clinical stability, and time to clinical stability of a standard infusion (SI) and prolonged infusion (PI) piperacillin-tazobactam (TZP) in Pseudomonas aeruginosa ( PA) pneumonia patients. Methods: This retrospective study evaluated length of hospitalization, mortality, clinical stability, and time to clinical stability with either SI-TZP or PI-TZP therapy in hospitalized patients diagnosed with PA pneumonia between January 01, 2008 and June 30, 2014. Patients were included in the study if they received ≥2 days of TZP, were diagnosed with PA pneumonia, and had TZP therapy initiated within 3 days of the documented PA infection. Results: A similar proportion of patients achieved clinical stability between the PI (n=14, 70%) and SI (n=22, 67%) groups, (p=0.8). There was no statistically significant difference in the average time to clinical stability between the PI (mean=5.3±3.6) and SI (mean=5.8±6.8) groups, (p=0.77). The total length of stay in the PI group (mean=15.9±9.8) was shorter than in the SI group (mean=23.9±33) but did not achieve statistical significance, p=0.2. The 14-day all-cause mortality was similar between the two groups, PI (n=1, 5%) and SI (n=2, 6%). Conclusion: The use of PI TZP was equally effective as standard therapy. Further research is warranted to confirm these findings on the clinical benefits of prolonged infusion therapy

Thói quen phát triển chuyên môn của giáo viên ở các trường phổ thông Việt Nam

Nguồn lực và chất lượng giáo viên là một trong những mối quan tâm thiết yếu để phát triển giáo dục bền vững. Thông qua phân tích bộ dữ liệu “Khảo sát thói quen phát triển chuyên môn giáo viên các trường phổ thông ở Việt Nam năm 2019” với 464 quan sát về thói quen học tập của giáo viên phổ thông từ các trường công lập và tư thục trên cả nước, chúng tôi thực hiện nghiên cứu phân tích thói quen phát triển chuyên môn của giáo viên. Nghiên cứu này là một phần kết quả của dự án nghiên cứu về năng lực chuyên môn giáo viên phổ thông Việt Nam giai đoạn 2020 – 2025 của Trung tâm nghiên cứu và Phát triển Giáo dục EdLab Asia. Bằng cách phân tích dữ liệu về số giờ tham gia hoạt động phát triển chuyên môn của giáo viên ở từng loại hình trường, nghiên cứu chỉ ra sự khác biệt về thói quen học tập của giáo viên các cấp phổ thông theo từng loại hình nhà trường. Nghiên cứu cũng chỉ ra rằng hoạt động phát triển chuyên môn giáo viên của trường tư thục tốt hơn trường công lập. Kết quả của nghiên cứu là gợi ý cho các nhà hoạch định chính sách, các nhà quản lý giáo dục tại các cơ sở giáo dục phổ thông, không kể công-tư tham chiếu và điều chỉnh các kế hoạch, chương trình phát triển chuyên môn giáo viên

Transformation of glycosyltransferase dnrs and auxiliary DNRQ genes into the Streptomyces peucetius MH9.2 for the enhance of doxorubicin production

Doxorubicin antibiotic produced by Streptomyces peucetius is a very crucial antibiotic with a large spectrum used as an anticancer drug and in clinical treatment. Production of doxorubicin from wild type strain by microbiological fermentation process is nomally very low yield and limited. The enhancement of doxorubicin production (DXR) by the genetically engineering of the auxiliary genes involved in the pathway of doxorubicin biosynthesis from Streptomyces peucetius has being focused by many research groups. The gene cluster responsible for biosynthesis of doxorubicin had been isolated, sequenced and characterized. Among them, the dnrQ and dnrS genes belong to the gene cluster encoded for the glycosyltransferase and helper enzymes, which are responsible for attachment of sugar moiety to -rhodomycinon intermediate and regulation of doxorubicin production, respectively. In this research, the dnrQ and dnrS genes were isolated and cloned in the p25.1 vector containing the strong promoter (ermE*) to generate the p25.1QS as a recombinant vector. The obtained plasmid was transferred into the host strain Streptomyces peucetius MH9.2 by the protoplast transformation method to generate the S. peucetius MH9.2SQ strain. Doxorubicin production from the recombinant S. peucetius MH9.2SQ and the parent strain were extracted and purified by using chlorofrom and methanol solvents. The products were confirmed by HPLC, LC-mass analysis and antibacterial bioassay. The results showed that the over production of doxorubicin was accumulated by the recombinant strain from the fermentation broth. In the S. peucetius MH9.2SQ, the doxorubicin productivity was 3.1 to 3.6 folds higher than in the parent strain. This recombinant strain could be a potential candidate for further research in enhancement and larger biomass scale of DXR production

Factors affecting the decision to choose a university of high school students: A study in An Giang Province, Vietnam

It is important to provide high school students with the necessary information for them to consult and make a decision to choose a university. The study aims to identify and evaluate the influence of factors in the decision to choose a university for high school students. The questionnaire survey method was used to collect data from 393 students from eight high schools in An Giang Province, Vietnam. Exploratory factor analysis and linear regression were used to analyze the data. The research results show that students are quite satisfied and quite certain with their decision to choose a university, while there are six important factors affecting the decision to choose a university. Influential factors with decreasing order of magnitude are: i) Factors consulted by teachers, family, friends, and relatives; ii) Factors of future job opportunities; iii) Factors of media activities; iv) Factors of learning conditions; v) Factors of university reputation; vi) Factors belong to the students themselves. The findings of the study show that there is no statistically significant difference between the group of males and females, between grades 10, 11, and 12. Besides, there is a statistically significant difference between students in high schools. The findings of this study have theoretical and practical implications for university admissions in Vietnam. Proposals made to university administrators were discussed. From the research results, we want to help students find the right university, and support universities to improve the efficiency of admissions