977 research outputs found

    A study of Entanglement theory

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    This article is a 50-page study of entanglement theory. First, the basic of quantum mechanics and mathematical definition of entanglement is presented. Second, entanglement is described as a physical phenomenon that set Quantum Mechanics distinct from Classical Physics. Third, entanglement as a physical resource for quantum communication is discussed with applications, the distillation process, and quantification problem. Fourth, several methods to detect entanglement are addressed. Detecting entanglement is shown to have a closed connection with positive maps in operator theory

    Exploring quality teaching of information and communication technology in New South Wales and Yenbai high schools : a comparative study

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    This study compares ICT policy and curriculum and assessment practices between Australian and Vietnamese secondary schools, and investigates differences between these two school systems. Document analyses and case studies were used to examine the key differences in ICT curriculum and policy and assessment practices between Australian and Vietnamese secondary schools. The document analyses focused on the intended ICT policy and curriculum and assessment, as presented in official documents in both countries. Using a case study approach for in-depth examination, two secondary schools were selected (one from Yenbai province, Vietnam and one from Sydney, New South Wales, Australia). Two principals and three teachers were interviewed. Classroom teaching and assessment practices were observed, and principals and teachers‟ views were obtained through semi-structured interviews and extensive discussions. Findings from the two case studies were compared with the findings from the document analysis. This study explored and analysed differences in ICT teaching, learning, assessment, and achievement between Vietnamese and Australian secondary students. It was found that that Australian ICT school curricula and assessment differed markedly from the Vietnamese system. Student ICT achievement in these Australian and Vietnamese schools could not only be attributed to higher standards of intended ICT curricula and assessment, or teacher knowledge or classroom practices. These differences are better explained by economic and cultural factors, ICT policies and their degrees of implementation, and extra ICT curricula. In order to bridge the gap and implement adequate ICT curricula and policies, rigorous professional training in teaching and assessment is essential for both Australian and Vietnamese teachers. In order to improve Australian students‟ ICT achievement, achievement motivation must be addressed. Many challenging aspects were found in ICT policies and classrooms in the Vietnamese educational system that calls for immediate change and improvement. In order to implement reforms in Vietnamese education, the impact of cultural influence must be considered more seriously. In particular, this study highlights the need to integrate case study with large-scale study in international comparative studies

    An Algorithmic Weakening of the Erd?s-Hajnal Conjecture

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    We study the approximability of the Maximum Independent Set (MIS) problem in H-free graphs (that is, graphs which do not admit H as an induced subgraph). As one motivation we investigate the following conjecture: for every fixed graph H, there exists a constant ? > 0 such that MIS can be n^{1-?}-approximated in H-free graphs, where n denotes the number of vertices of the input graph. We first prove that a constructive version of the celebrated Erd?s-Hajnal conjecture implies ours. We then prove that the set of graphs H satisfying our conjecture is closed under the so-called graph substitution. This, together with the known polynomial-time algorithms for MIS in H-free graphs (e.g. P?-free and fork-free graphs), implies that our conjecture holds for many graphs H for which the Erd?s-Hajnal conjecture is still open. We then focus on improving the constant ? for some graph classes: we prove that the classical Local Search algorithm provides an OPT^{1-1/t}-approximation in K_{t, t}-free graphs (hence a ?{OPT}-approximation in C?-free graphs), and, while there is a simple ?n-approximation in triangle-free graphs, it cannot be improved to n^{1/4-?} for any ? > 0 unless NP ? BPP. More generally, we show that there is a constant c such that MIS in graphs of girth ? cannot be n^{c/(?)}-approximated. Up to a constant factor in the exponent, this matches the ratio of a known approximation algorithm by Monien and Speckenmeyer, and by Murphy. To the best of our knowledge, this is the first strong (i.e., ?(n^?) for some ? > 0) inapproximability result for Maximum Independent Set in a proper hereditary class

    FACTORS INFLUENCE ON CUSTOMER PURCHASE INTENTION VIA LIVETREAM: CASE OF VIETNAM

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     The main purpose of this study is to propose and empirically test a conceptual model that clarifies shopping behavior via livestream on Facebook platform of people in Hanoi. The data was collected from at least 240 random Facebook users. The analysis results show that Facebook users tend to buy goods via livestream when they feel that the product quality, design, and product policy are convincing enough for them. In addition, there are other factors that also influence purchasing decisions, such as technology quality, perceived value of style and attitude, reliability, product trust in the relationship between consumers and sellers such as livestream style, KOLs, sound & background… From there, theoretical and managerial contributions, as well as finding out limitations and future research directions are also discussed in the body of this paper  Keywords:  Shopping, Livestream, Livestream Products, Livestream People, Livestream Culture, Online Shopping

    Passive RF Tomography: Signal Processing and Experimental Validation

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    Radio frequency (RF) tomography is an imaging technique based upon a set of distributed transmitters and receivers surrounding the area under observation. This method requires prior knowledge of the transmitters\u27 and receivers\u27 locations. In some circumstances the transmitters may be uncooperative, while in other cases extrinsic emitters may be used as source of opportunity. In these scenarios, RF tomography should operate in a passive modality. A previous work postulated the principles and feasibility of passive RF tomography. This research further develops the underlying theory through concise and ad-hoc signal processing. Experimental verification and validation corroborate the effectiveness of passive RF tomography for object detection and imaging

    THE TRITERPENOID AND STEROID FROM THE FRUITING BODY OF Ganoderma applanatum (Pers.) Pat. IN VIETNAM

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    Five compounds, ergosterol (1), 5α,8α-epidioxy-22E-ergosta-6,22-dien-3β-ol (2); ergosta-7,22-dien-3β-ol (3); lanosta-7,9(11),24-triene-3,26-diol (4) and 3β-hydroxy-5α-lanosta-7,9,24(E)-trien-26-oic acid (5) were isolated from fruiting body of Ganoderma applanatum (Pers.) Pat.  (Ganodermataceae). The structures of the isolated compounds were established by spectroscopic methods (UV, IR, MS, 1H-NMR, 13C-NMR, DEPT, COSY, HSQC and HMBC). These compounds were isolated from the Vietnamese fungi for the first time. Moreover, the lanosta-7,9(11),24-triene-3,26-diol is the first compound was found in the fungi

    Negative positional externality of conspicuous and positional goods on society: An empirical analysis on income and clothing consumption for 9 EU countries.

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    Objectives The main objectives of this study were first, through secondary sources, to analyze the way positional externality exist and its negative impact of on society, focusing on conspicuous and positional goods. Second, it tries to find the empirical evidence for the effect of positional externality in income and clothing consumption. Third, the thesis discuss various ways to reduce positional externality. Summary The thesis first analyzes the literatures which shows the negative impact of conspicuous and positional goods on society. Then, using data from Life in Transition survey III, the thesis tests four hypotheses on the effect of positional externality on life satisfaction. Two hypotheses are related to income comparisons, while the others are related to clothing consumption. Finally, the author discusses some of the measures to reduce the effect of positional externality. Conclusions The main findings shows controlled for income of each individual, GDP per capita and average clothing consumption has negative correlation with life satisfaction of each individual. This result shows the existence of positional externality and support the argument that positional externality has a negative impact on society
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