Some results related to distribution functions of chi-square type random variables with random degrees of freedom

Tran Loc Hung,Tran Thien Thanh,Bui Quang Vu 대한수학회 2008 대한수학회보 Vol.45 No.3

The main aim of this paper is to present some results related to asymptotic behavior of distribution functions of random variables of chi-square type [수식] with degrees of freedom N, where N is a positive integer-valued random variable independent on all standard normally distributed random variables Xi. Two ways for computing the distribution functions of chi-square type random variables with random degrees of freedom are considered. Moreover, some tables concerning considered distribution functions are demonstrated in Appendix The main aim of this paper is to present some results related to asymptotic behavior of distribution functions of random variables of chi-square type [수식] with degrees of freedom N, where N is a positive integer-valued random variable independent on all standard normally distributed random variables Xi. Two ways for computing the distribution functions of chi-square type random variables with random degrees of freedom are considered. Moreover, some tables concerning considered distribution functions are demonstrated in Appendix

ON THE RATES OF CONVERGENCE IN WEAK LIMIT THEOREMS FOR NORMALIZED GEOMETRIC SUMS

Hung, Tran Loc,Kien, Phan Tri Korean Mathematical Society 2020 대한수학회보 Vol.57 No.5

The main purpose of this paper is to establish the rates of convergence in weak limit theorems for normalized geometric sums of independent identically distributed random variables via Zolotarev's probability metric.

SOME RESULTS ON ASYMPTOTIC BEHAVIORS OF RANDOM SUMS OF INDEPENDENT IDENTICALLY DISTRIBUTED RANDOM VARIABLES

Hung, Tran Loc,Thanh, Tran Thien Korean Mathematical Society 2010 대한수학회논문집 Vol.25 No.1

Let ${X_n,\;n\geq1}$ be a sequence of independent identically distributed (i.i.d.) random variables (r.vs.), defined on a probability space ($\Omega$,A,P), and let ${N_n,\;n\geq1}$ be a sequence of positive integer-valued r.vs., defined on the same probability space ($\Omega$,A,P). Furthermore, we assume that the r.vs. $N_n$, $n\geq1$ are independent of all r.vs. $X_n$, $n\geq1$. In present paper we are interested in asymptotic behaviors of the random sum $S_{N_n}=X_1+X_2+\cdots+X_{N_n}$, $S_0=0$, where the r.vs. $N_n$, $n\geq1$ obey some defined probability laws. Since the appearance of the Robbins's results in 1948 ([8]), the random sums $S_{N_n}$ have been investigated in the theory probability and stochastic processes for quite some time (see [1], [4], [2], [3], [5]). Recently, the random sum approach is used in some applied problems of stochastic processes, stochastic modeling, random walk, queue theory, theory of network or theory of estimation (see [10], [12]). The main aim of this paper is to establish some results related to the asymptotic behaviors of the random sum $S_{N_n}$, in cases when the $N_n$, $n\geq1$ are assumed to follow concrete probability laws as Poisson, Bernoulli, binomial or geometry.

SOME RESULTS RELATED TO DISTRIBUTION FUNCTIONS OF CHI-SQUARE TYPE RANDOM VARIABLES WITH RANDOM DEGREES OF FREEDOM

Hung, Tran Loc,Thanh, Tran Thien,Vu, Bui Quang Korean Mathematical Society 2008 대한수학회보 Vol.45 No.3

The main aim of this paper is to present some results related to asymptotic behavior of distribution functions of random variables of chi-square type $X^2_N={\Sigma}^N_{i=1}\;X^2_i$ with degrees of freedom N, where N is a positive integer-valued random variable independent on all standard normally distributed random variables $X_i$. Two ways for computing the distribution functions of chi-square type random variables with random degrees of freedom are considered. Moreover, some tables concerning considered distribution functions are demonstrated in Appendix.

ON THE WEAK LIMIT THEOREMS FOR GEOMETRIC SUMMATIONS OF INDEPENDENT RANDOM VARIABLES TOGETHER WITH CONVERGENCE RATES TO ASYMMETRIC LAPLACE DISTRIBUTIONS

Hung, Tran Loc Korean Mathematical Society 2021 대한수학회보 Vol.58 No.6

The asymmetric Laplace distribution arises as a limiting distribution of geometric summations of independent and identically distributed random variables with finite second moments. The main purpose of this paper is to study the weak limit theorems for geometric summations of independent (not necessarily identically distributed) random variables together with convergence rates to asymmetric Laplace distributions. Using Trotter-operator method, the orders of approximations of the distributions of geometric summations by the asymmetric Laplace distributions are established in term of the "large-𝒪" and "small-o" approximation estimates. The obtained results are extensions of some known ones.

Trichoderma asperellum Chi42 Genes Encode Chitinase

Loc, Nguyen Hoang,Quang, Hoang Tan,Hung, Nguyen Bao,Huy, Nguyen Duc,Phuong, Truong Thi Bich,Ha, Tran Thi Thu The Korean Society of Mycology 2011 Mycobiology Vol.39 No.3

Four Trichoderma strains (CH2, SH16, PQ34, and TN42) were isolated from soil samples collected from Quang Tri and Thua Thien Hue provinces in Vietnam. The strains exhibited high chitinolytic secretion. Strain PQ34 formed the largest zone of chitinase-mediated clearance (> 4 cm in diameter) in agar containing 1% (w/v) colloidal chitin. Analysis of the internal transcribed spacer regions of these strains indicated that they were Trichoderma asperellum. The molecular weights of the chitinases were approximately 42 kDa. Chitinase genes (chi42) of T. asperellum strains TN42, CH2, SH16, and PQ34 were 98~99% homologous to the ech42 gene of T. harzianum CB-Pin-01 (accession No. DQ166036). The deduced amino acid sequences of both T. asperellum strains SH16 and TN42 shared 100% similarity.

Alumina-coated silicon-based nanowire arrays for high quality Li-ion battery anodes

Nguyen, Hung Tran,Zamfir, Mihai Robert,Duong, Loc Dinh,Lee, Young Hee,Bondavalli, Paolo,Pribat, Didier The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.47

<P>Amongst other requirements, a good anode for Li-ion battery applications must exhibit dimensional stability upon Li insertion, as well as chemical inertness with respect to the electrolyte. This latter characteristic is usually provided by the so-called solid electrolyte interphase (SEI), a passivating film that is formed at the end of the first lithiation step, originating from the partial reduction of the electrolyte and Li salt. However, silicon, which exhibits the highest known capacity for Li alloying, possesses none of the above attributes when used as an anode material. Actually, the large volume expansion of Si upon alloying with Li induces a mechanical instability of the SEI film, which therefore fails to provide its protective role. In this paper, we have studied the effect of thin alumina deposits on top of Si-based nanowires. A thin alumina deposit will act as a substitute for the SEI, preventing electrolyte decomposition. We observe that even if alumina films crack during lithiation–delithiation steps of the Si-based nanowires, they still provide some kind of protection, prolonging the lifetime of the anode. Using Al<SUB>2</SUB>O<SUB>3</SUB>-coated Si-based nanowires, we have been able to obtain a lifetime of 1280 cycles when the capacity of the anode was limited to 1200 mA h g<SUP>−1</SUP>. We also show that uncoated Si nanowires degrade more rapidly when cycled under identical conditions.</P> <P>Graphic Abstract</P><P>We have studied the effect of thin Al<SUB>2</SUB>O<SUB>3</SUB> coatings on Si-based nanowires for Li-ion battery anodes. We report a lifetime of 1280 cycles when the capacity is limited to 1200 mA h g<SUP>−1</SUP>. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm35125k'> </P>

Compliance of education journals in Vietnam with the minimum criteria to be indexed in the ASEAN Citation Index and Scopus

Trung Tran,Loc Thi My Nguyen,Thanh Thi Nghiem,Hien Thi Thu Le,Cuong Huu Nguyen,Thuy Phuong La,Trung Tien Nguyen,Hang Thi-Thu Nguyen 한국과학학술지편집인협의회 2019 Science Editing Vol.6 No.2

This study aimed at elucidating the present situation of scholarly journals published in Vietnam according to the minimum criteria to be indexed in the ASEAN Citation Index (ACI) and Scopus, with the goal of suggesting development strategies for scholarly journals in Vietnam. From the 387 journals accredited by the Vietnamese State Council for Professorship, 13 education journals were arbitrarily selected, and their compliance with the five minimum criteria for the ACI (peer review, timeliness, abstracts in English, references in Roman script, and a website in English) and the six minimum criteria for Scopus (peer review, timeline, abstracts in English, references in Roman characters, Electronic International Standard Serial Number [ISSN], and publication ethics) were assessed. Two of the 13 journals were eligible to be indexed in the ACI, while none fulfilled the minimum criteria to be indexed in Scopus. An urgent task for the editors of those journals is to establish an informative journal homepage in English that provides basic information on the journal. Then, an Electronic ISSN can be obtained from the ISSN International Center. Furthermore, the following steps are suggested for journal promotion: establishment of appropriate editorial policies and publication ethics procedures, improvement of research integrity, enhancement of the journals’ reputation in the international scientific community, and improvement of the online publishing system by adopting a journal manuscript management system. To achieve those goals, financial support from the Vietnamese government will be invaluable.

Research Articles : Trichoderma asperellum Chi42 Genes Encode Chitinase

( Nguyen Hoang Loc ),( Hoang Tan Quang ),( Nguyen Bao Hung ),( Nguyen Duc Huy ),( Truong Thi Bich Phuong ),( Tran Thi Thu Ha ) 한국균학회 2011 韓國菌學會誌 Vol.39 No.3

Four Trichoderma strains (CH2, SH16, PQ34, and TN42) were isolated from soil samples collected from Quang Tri and Thua Thien Hue provinces in Vietnam. The strains exhibited high chitinolytic secretion. Strain PQ34 formed the largest zone of chitinase-mediated clearance (> 4 cm in diameter) in agar containing 1% (w/v) colloidal chitin. Analysis of the internal transcribed spacer regions of these strains indicated that they were Trichoderma asperellum. The molecular weights of the chitinases were approximately 42 kDa. Chitinase genes (chi42) of T. asperellum strains TN42, CH2, SH16, and PQ34 were 98~99% homologous to the ech42 gene of T. harzianum CB-Pin-01 (accession No. DQ166036). The deduced amino acid sequences of both T. asperellum strains SH16 and TN42 shared 100% similarity.

Numerical Analysis of Dielectrophoresis-Based Microfluidic Chip with a Facing-Electrode Design for Cell Separation

Nguyen Thu Hang,Nguyen Mai Chi,Nguyen Hoang Trung,Thi Y Van Tran,Vu Ngoc Trung,Thu Hang Bui,Duc Trinh Chu,Bui Tung Thanh,Jen Chun-Ping,Quang Loc Do 한국농업기계학회 2024 바이오시스템공학 Vol.49 No.1

Purpose Circulating tumor cell separation and analysis have played a critical role in cancer diagnosis, prognosis, and treatment. In this work, we aim to design and investigate a novel biochip that integrates dielectrophoresis, microfl uidic technology to separate circulating tumor cells from blood cells. To create a dielectrophoresis-induced non-uniform electric fi eld, a facing-electrode design was proposed and utilized, in which a slanted electrode array and a simple rectangular ground electrode are placed parallel on the top and bottom parts of the microfl uidic channel, respectively. This design can reduce the particle position dependence in the microchannel and the complexity of the microfabrication process. Methods The separation process, effi ciency, and optimization of the proposed device were numerically investigated using the fi nite element method. Parametric research was conducted to comprehensively examine the impact of various operating and design factors on the cell movement and trajectories in the microfl uidic device. Results The results indicated the potential of the proposed biochip to ensure cancer cell separation from blood cells with high effi ciency, high purity in a label-free, non-invasive, easy integration, and low-cost manner. Under the optimal conditions, the separation effi ciency reached 92%, 88%, and 96% for human colon cancer cells (HT-29), red blood cells, and white blood cells, respectively. Conclusions In this study, a novel DEP-based microfl uidic chip was proposed to separate HT-29 tumor cells from blood cells and numerically investigated to verify the performance of the biochip design. Our fi ndings could provide a foundation for further theoretical and practical investigations. The proposed system can separate cancer cells from red blood cells and white blood cells as well as off ers numerous advantages, such as compact size, low voltage, high effi ciency, non-invasiveness, and label-free nature. The tumor cell enrichment platform has the potential for application in cancer detection, analysis, and assessment.