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ALTITUDINAL VARIATION OF ANTIOXIDATIVE SYSTEM IN LEAVES OF RHODIOLA QUADRIFIDA AND R. GELIDA
四裂红景天与长鳞红景天叶片中抗氧化系统随海拔梯度的变化

WANG Xiao-Feng,REN Hong-Xu,SUN Guo-jun,
汪晓峰
,任红旭,孙国钧

植物生态学报 , 2005,
Abstract: Alpine environments are characterized by rapid changes in climate, and leaves of alpine plants are routinely exposed to high light intensities at low temperatures. The fact that there seems to be no impairment of photosynthesis by high light and low temperatures under field conditions indicates a very well regulated system of carbohydrate turnover together with a functional system of antioxidants. To study the mechanisms of adaptation of alpine plants, we investigated the antioxidative defense capacity in leaves of two alpine plants, Rhodiola quadrifida and R. gelida. Field investigations were carried out on the slopes of Tianshan Mountain near the Tianshan Glacier NO. 1. Along this slope, R. quadrifida was found between 3 500 and 3 805 m and R. gelida was found between 3 805 and 4 010 m. The two species coexisted at 3 805 m. Plant specimens used in this experiment were collected at 50 m intervals from 3 610 to 3 900 m. Our results showed that the malondialdehyde (MDA) content in leaves of R. gelida was significantly greater than that in R. quadrifida, suggesting that R. gelida might suffer more serious oxidative stress compared to R. quadrifida. The fact that R. gelida can survive and maintain normal metabolism at high elevations suggests that it might be an adaptive mechanisms to endure serious oxidative stress in this harsh environment. The increase in the activities of antioxidative enzymes, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) as well as the contents of reduced glutathione (GSH) and ascorbic acid (AsA), in the leaves of R. gelida suggested a combined and balanced enhancement of antioxidants to improve stress resistance in alpine plant leaves. Among all the antioxidative enzymes examined, peroxidase (POD) was quite distinct from others. Activity of POD was below the limits of detection in leaves of R. quadrifida collected from elevations lower than 3 805 m, but enhanced activity was observed in leaves of R. gelida as altitude increased implying that POD might play an important role in plant adaptation to alpine environments. Given the inverse relationship between growth rate and peroxidase activity demonstrated in many plant developmental systems, in-depth studies on the role of peroxidases in adaptation of R. gelida to high altitudes are warranted.
The Wheeler Propagator  [PDF]
C. G. Bollini,M. C. Rocca
Physics , 1998,
Abstract: We study the half advanced and half retarded Wheeler Green function and its relation to Feynman propagators. First for massless equation. Then, for Klein-Gordon equations with arbitrary mass parameters; real, imaginary or complex. In all cases the Wheeler propagator lacks an on-shell free propagation. The Wheeler function has support inside the light-cone (whatever the mass). The associated vacuum is symmetric with respect to annihilation and creation operators. We show with some examples that perturbative unitarity holds, whatever the mass (real or complex). Some possible applications are discussed.
Study of the Wheeler Propagator  [PDF]
C. G. Bollini,M. C. Rocca
Physics , 2010,
Abstract: We study the half advanced and half retarded Wheeler Green function and its relation to Feynman propagators. First for massless equation. Then, for Klein-Gordon equations with arbitrary mass parameters; real, imaginary or complex. In all cases the Wheeler propagator lacks an on-shell free propagation. The Wheeler function has support inside the light-cone (whatever the mass). The associated vacuum is symmetric with respect to annihilation and creation operators.
A Note on the Ant Gnamptogenys Hartmani Wheeler  [cached]
Psyche , 1961, DOI: 10.1155/1961/76084
Abstract:
Correcion to the Synonymy of the Ant Camponotus Formosensis Wheeler  [cached]
W. L. Brown
Psyche , 1952, DOI: 10.1155/1952/45613
Abstract:
Reconsideration of the Regge-Wheeler equation  [PDF]
Guihua Tian,Shikun Wang,Zhao Zheng
Physics , 2005,
Abstract: Reconsideration of the Regge-Wheeler equation is processed by using the Painlev\'{e} coordinate and "good" timelier to define the initial time. We find that: the Regge-Wheeler equation could has positive imaginary frequency. Because the Regge-Wheeler equation is the odd (angular) perturbation to the Schwarzschild black hole, the conclusion is that the Schwarzschild black hole is unstable with respect to the rotating perturbation.
Delay Equations of the Wheeler-Feynman Type  [PDF]
D. -A. Deckert,D. Dürr,N. Vona
Mathematics , 2012,
Abstract: We present an approximate model of Wheeler-Feynman electrodynamics for which uniqueness of solutions is proved. It is simple enough to be instructive but close enough to Wheeler-Feynman electrodynamics such that we can discuss its natural type of initial data, constants of motion and stable orbits with regard to Wheeler-Feynman electrodynamics.
Alpine tourism  [cached]
Andrea Macchiavelli
Revue de Géographie Alpine , 2009, DOI: 10.4000/rga.843
Abstract: The spectacular increase in tourism in the Alps in recent decades has been founded mainly on the boom in skiing, resulting in both strong real estate development and an increasing array of infrastructures and ski runs. Today the ski market seems to have virtually reached saturation point and the winter sports sector needs to diversify its offer through innovation. After a review of the main factors of change in mountain tourism, the paper presents a grid for interpreting the life cycle of alpine destinations, identifying the phases that characterize their evolution. The conditions that may favour innovation in alpine tourism are then identified, as well as the contradictions that frequently accompany them. In most cases, innovation is the result of a process that begins within the alpine community, frequently encouraged and supported by national and international institutions and with whose help structural difficulties are successfully overcome. La forte croissance qu’ont connue les pays alpins dans les dernières décennies a surtout été fondée sur l’offre des activités du ski, avec comme conséquence, un massif développement immobilier et la multiplication d’infrastructures et de pistes. Aujourd’hui, le marché du ski semble arriver à saturation, la Convention alpine a mis un frein à la poursuite du développement des domaines skiables et on observe donc avec intérêt la diversification de l’offre soutenue par l’innovation. Après avoir rappelé les facteurs de changement en cours les plus significatifs dans le tourisme montagnard, l’article présente une grille interprétative de l’évolution des destinations touristiques alpines, identifiant les phases qui ont caractérisé son développement. Ensuite, l’article propose une réflexion sur certaines conditions qui peuvent favoriser l’innovation dans le tourisme alpin, ainsi que sur les contradictions qui accompagnent souvent ces conditions. Dans la plupart des cas l’innovation est le résultat d’un processus qui a été lancé et qui s’est développé au sein de la communauté alpine, souvent favorisé et soutenu par des institutions nationales et internationales, et grace auquel les difficultés structurelles qui ont déjà été abordées précédemment ont pu être surmontées avec succès.
Solving the Wheeler-DeWitt of Small Universe  [PDF]
Shintaro Sawayama
Physics , 2009,
Abstract: We can solve the Wheeler-DeWitt equation of the small universe enough to metric becomes diagonal and take a Gaussian normal coordinate. Our previous works are concerning to this paper. In this paper, we only write how to solve the Wheeler-DeWitt equation of such universe. Our motivation is simple, that is to solve the Wheeler-DeWitt equation. Even if the Wheeler-DeWitt equation is solved, quantum gravity does not complete yet. However, this work may be one of the first step to quantum gravity.
A note on the Burrows-Wheeler transformation  [PDF]
Maxime Crochemore,Jacques Désarménien,Dominique Perrin
Computer Science , 2005,
Abstract: We relate the Burrows-Wheeler transformation with a result in combinatorics on words known as the Gessel-Reutenauer transformation.
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