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Search Results: 1 - 10 of 49717 matches for " Jun Shen "
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Modeling the glutamate–glutamine neurotransmitter cycle
Jun Shen
Frontiers in Neuroenergetics , 2013, DOI: 10.3389/fnene.2013.00001
Abstract: Glutamate is the principal excitatory neurotransmitter in brain. Although it is rapidly synthesized from glucose in neural tissues the biochemical processes for replenishing the neurotransmitter glutamate after glutamate release involve the glutamate–glutamine cycle. Numerous in vivo 13C magnetic resonance spectroscopy (MRS) experiments since 1994 by different laboratories have consistently concluded: (1) the glutamate–glutamine cycle is a major metabolic pathway with a flux rate substantially greater than those suggested by early studies of cell cultures and brain slices; (2) the glutamate–glutamine cycle is coupled to a large portion of the total energy demand of brain function. The dual roles of glutamate as the principal neurotransmitter in the CNS and as a key metabolite linking carbon and nitrogen metabolism make it possible to probe glutamate neurotransmitter cycling using MRS by measuring the labeling kinetics of glutamate and glutamine. At the same time, comparing to non-amino acid neurotransmitters, the added complexity makes it more challenging to quantitatively separate neurotransmission events from metabolism. Over the past few years our understanding of the neuronal-astroglial two-compartment metabolic model of the glutamate–glutamine cycle has been greatly advanced. In particular, the importance of isotopic dilution of glutamine in determining the glutamate–glutamine cycling rate using [1?13C] or [1,6-13C2] glucose has been demonstrated and reproduced by different laboratories. In this article, recent developments in the two-compartment modeling of the glutamate–glutamine cycle are reviewed. In particular, the effects of isotopic dilution of glutamine on various labeling strategies for determining the glutamate–glutamine cycling rate are analyzed. Experimental strategies for measuring the glutamate–glutamine cycling flux that are insensitive to isotopic dilution of glutamine are also suggested.
Pierre Bourdieu’s Standpoint on Media Culture and the Consumptive Liability of Contemporary Mass Media in China
Ai-jun SHEN
Cross-Cultural Communication , 2006, DOI: 10.3968/600
Abstract: Pierre Bourdieu was a famous contemporary thinker, sociologist and culture theory critic in France. His contribution not only embodies on providing a serial of social concepts, his comment and analysis on media culture, and the much broader way that he brought to culture study were also expensively valuable .What is more, it can also be used for reference in interpreting the changing process of the mass media culture in China. This thesis is composed of three parts. First, it aims to traces and analyses Bourdieu’s unique understanding and strategic point to media culture, and try to make it clear which part does contributions to the study of media culture ; Secondly, it goes on using the macro-thought way and several main concepts Bourdieu provided in studying media culture in China which is rounded by consumptive thoughts. During this process, we can see how the mass media changes and turns its meanings , and how it affects the receiver’s thoughts and the structure the society. In the last part, we aknowledged that Bourdieu`s theory indeed provided a unique visual angle for us in studying culture phenomenon. However, we should also notice that Bourdieu`s theory had his own shortages,and we should think it farther. Keywords: Bourdieu, consumptive, mass media Résumé Pierre Bourdieu est un penseur contemporain célèbre, sociologue et critique théorique culturel en France. Sa contribution consiste non seulement à offrir une série de concepts sociaux, mais son commentaire et analyse sur la culture de médias, et la voie élargie qu’il a frayé pour l’étude de la culture sont aussi précieux. En outre, il peut encore servir de référence pour interpréter le processus de changement de la culture de mass médias en Chine. Cet essai est composé de trois parties. D’abord, il vise à décrire et analyser la compréhension unique et la vue stragétique de Bourdieu sur la culture de médias. , et à éclaircir quelle partie contribue à l’étude de la culture de médias. Deuxièment, il continue à utiliser le mode de pensée macroscopique et plusieurs concepts principaux que Bourdieu a avancé dans l’étude de la culture de médias de la Chine qui est entourée par des pensées consomptives. Dans ce processus, on peut voir comment les mass médias changent leur sens et comment ils influent la pensée du récepteur et la structure sociale. Dans la dernière partie, on admet que la théorie de Bourdieu nous a en effet fourni un angle visuel unique pour l’étude du phénomène culturel. Cependant, on doit noter qu’il existe aussi des inconvénients dans sa théorie, donc on doit réfléchir plus loin. Mo
Properties of Orthogonal Gaussian-Hermite Moments and Their Applications
Wu Youfu,Shen Jun
EURASIP Journal on Advances in Signal Processing , 2005,
Abstract: Moments are widely used in pattern recognition, image processing, and computer vision and multiresolution analysis. In this paper, we first point out some properties of the orthogonal Gaussian-Hermite moments, and propose a new method to detect the moving objects by using the orthogonal Gaussian-Hermite moments. The experiment results are reported, which show the good performance of our method.
Sequential product on standard effect algebra ${\cal E} (H)$
Shen Jun,Wu Junde
Physics , 2009, DOI: 10.1088/1751-8113/42/34/345203
Abstract: A quantum effect is an operator $A$ on a complex Hilbert space $H$ that satisfies $0\leq A\leq I$, ${\cal E} (H)$ is the set of all quantum effects on $H$. In 2001, Professor Gudder and Nagy studied the sequential product $A\circ B=A^{{1/2}}BA^{{1/2}}$ of $A, B\in {\cal E}(H)$. In 2005, Professor Gudder asked: Is $A\circ B=A^{{1/2}}BA^{{1/2}}$ the only sequential product on ${\cal E} (H)$? Recently, Liu and Wu presented an example to show that the answer is negative. In this paper, firstly, we characterize some algebraic properties of the abstract sequential product on ${\cal E} (H)$; secondly, we present a general method for constructing sequential products on ${\cal E} (H)$; finally, we study some properties of the sequential products constructed by the method
Generalized quantum operations and almost sharp quantum effects
Shen Jun,Wu Junde
Physics , 2009, DOI: 10.1016/S0034-4877(10)80006-0
Abstract: In this paper, we study generalized quantum operations and almost sharp quantum effects, our results generalize and improve some important conclusions in [2] and [3].
Spectral representation of infimum of bounded quantum observables
Shen Jun,Wu Junde
Physics , 2009, DOI: 10.1063/1.3253609
Abstract: In 2006, Gudder introduced a logic order on bounded quantum observable set $S(H)$. In 2007, Pulmannova and Vincekova proved that for each subset $\cal D$ of $S(H)$, the infimum of $\cal D$ exists with respect to this logic order. In this paper, we present the spectral representation for the infimum of $\cal D$.
Not each sequential effect algebra is sharply dominating
Shen Jun,Wu Junde
Mathematics , 2008,
Abstract: Let $E$ be an effect algebra and $E_S$ be the set of all sharp elements of $E$. $E$ is said to be sharply dominating if for each $a\in E$ there exists a smallest element $\widehat{a}\in E_s$ such that $a\leq \widehat{a}$. In 2002, Professors Gudder and Greechie proved that each $\sigma$-sequential effect algebra is sharply dominating. In 2005, Professor Gudder presented 25 open problems in International Journal of Theoretical Physics, Vol. 44, 2199-2205, the 3th problem asked: Is each sequential effect algebra sharply dominating? Now, we construct an example to answer the problem negatively.
The n-th root of sequential effect algebras
Shen Jun,Wu Junde
Mathematics , 2009,
Abstract: Sequential effect algebra is an important model for studying quantum measurement theory. In 2005, Professor Gudder presented 25 open problems to motivate its study. The 20th problem asked: In a sequential effect algebra, if the square root of some element exists, is it unique ? We can strengthen the problem as following: For each given positive integer $n>1$, is there a sequential effect algebra such that the n-th root of its some element $c$ is not unique and the n-th root of $c$ is not the k-th root of $c$ ($k
Remarks on the sequential effect algebras
Shen Jun,Wu Junde
Mathematics , 2009, DOI: 10.1016/S0034-4877(09)90015-5
Abstract: In this paper, first, we answer affirmatively an open problem which was presented in 2005 by professor Gudder on the sub-sequential effect algebras. That is, we prove that if $(E,0,1, \oplus, \circ)$ is a sequential effect algebra and $A$ is a commutative subset of $E$, then the sub-sequential effect algebra $\bar{A}$ generated by $A$ is also commutative. Next, we also study the following uniqueness problem: If $na=nb=c$ for some positive integer $n\geq 2$, then under what conditions $a=b$ hold? We prove that if $c$ is a sharp element of $E$ and $a|b$, then $a=b$. We give also two examples to show that neither of the above two conditions can be discarded.
The average value inequality in sequential effect algebras
Shen Jun,Wu Junde
Mathematics , 2009,
Abstract: A sequential effect algebra $(E,0,1, \oplus, \circ)$ is an effect algebra on which a sequential product $\circ$ with certain physics properties is defined, in particular, sequential effect algebra is an important model for studying quantum measurement theory. In 2005, Gudder asked the following problem: If $a, b\in (E,0,1,\oplus, \circ)$ and $a\bot b$ and $a\circ b\bot a\circ b$, is it the case that $2(a\circ b)\leq a^2\oplus b^2$ ? In this paper, we construct an example to answer the problem negatively.
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