Dead-end pores are usually present in natural porous media especially in consolidated sandstone and limestone rocks. However, the presence of the dead-end pores is usually ignored. Then, the influences of the dead end pores to the flow system are also neglected. In this paper, pressure changes for the periods of transient and steady state of the dead-end pores are studied using lattice gas automata model. A simulation result is compared with the past works. They show that the model is viable to perform simulation of deadend pore pressure. Some parameters such as pressure distribution and size of neck and body of the dead-end pores are varied to examine their effects. We found that the parameters affect the rate of pressure change during transient period. In addition, the parameters also affect the pressure fluctuation during steady state period. The dead-end pores have function either as source or sink in the transient period depend on initial and injection pressures. During steady state period, the dead-end pores behave both as source and sink since the pressure in the pores fluctuates around an equilibrium pressure between the pressure of dead-end pore and that of main channel at the neck position of dead-end pore. and Takzvané mŕtve póry (neprietočné póry) sa často nachádzajú v prírodných pórovitých prostrediach, predovšetkým v skonsolidovaných pieskovcoch a vo vápencoch. Obvykle sa ich existencii nevenuje pozornosť. Pozornosť sa nevenuje ani ich vplyvu na prúdenie v tomto systéme. V tomto príspevku sú študované zmeny tlaku v mŕtvych póroch počas neustáleného a ustáleného prúdenia s použitím ''lattice gas automata'' modelu. Výsledky simulácie sme porovnali s predchádzajúcimi prácami. Výsledky naznačujú, že tento model je vhodný na simuláciu zmien tlakov v mŕtvych póroch. Vplyv niektorých parametrov, ako je rozdelenie tlakov a tvary ''krčkov'' (spojovacích pórov) ako aj mŕtvych pórov boli menené tak, aby sme mohli pozorovať ich vplyv na prúdenie. Zistili sme, že tieto parametre ovplyvňujú rýchlosť zmien tlakov počas neustáleného prúdenia. Navyše sme zistili, že tieto parametre ovplyvňujú fluktuáciu tlakov počas ustáleného prúdenia. Mŕtve póry môžu počas neustáleného prúdenia fungovať ako zdroje alebo odbery, v závislosti od počiatočného, alebo ''plniaceho'' tlaku. Počas ústáleného prúdenia sa mŕtve póry správajú ako zdroje alebo aj odbery, pretože tlak v póroch fluktuuje okolo rovnovážneho tlaku medzi tlakom v mŕtvych póroch a hlavným kanálom v závislosti od vlastností ''krčku'' mŕtveho póru.
Net CO2 exchange (Rn), stomatal conductance (gj, intemal CO2 concentration (Q), and water-use efficiency (WUE) of aging leaves were measured at the beginning of the dry season in 18 species in a tropical deciduous forest in Guanacaste, Costa Rica. In selected trees, gas exchange of old leaves was also compared with that of young leaves, and stomatal responses to irradiation and dark were measured. Based on comparisons with published data, and gj declined more rapidly with leaf age in deciduous than in evergreen species. Whereas both senescence and drought were implicated as causes of these dechneš in the deciduous species, the relative importance of factors responsible for the smaller decreases in physiological activity of old leaves of the evergreen species was less obvious. In the latter trees, and WUE of aging leaves, although not always as high as in young leaves, were high enough to refiite the suggestion that old leaves are solely a liability to tropical deciduous forest trees. On the other hand, stomatal closure in the dark was incomplete, potentially allowing water loss at night and during droughts.
Four-d-old seedlings were exposed to ultraviolet-B, UV-B (20 pinol ht^), and UV-B supplemented with red, R {X 612 nin, 5 pmol nr^) or far-red, FR (X 712 nin, 4.5 pmol nr^) radiation for 30 min during the middle of tlie light phase. Three d of UV-B treatment caused reduction in shoot elongation and expansion of cotyledonaiy leaves. The reduction was largely reversed by supplementary R and FR radiations. Supplementation of FR accelerated senescence process. Similar changes were also noted in the contents of photosynthetic piginents, while the level of anthocyanin was enhanced by all treatments. Flavonoid accumulation was enhanced by UV-B, whereas R and FR radiations suppressed its synthesis to various degrees. The chlorophyll (Chl) fluorescence ratio Fy/F,„ and half-rise time of maximum fluorescence were greatly reduced by UV-B and with FR supplementation. R reversed this UV-B inhibition to a great extent. Likewise, tlie P-S dechne was higher under control and +UV-B+R than under +UV-B and +UV-B+FR treatments, At the protein level both the subunits of ribulose 1,5-bisphosphate carboxylase alone were regulated by phytochrome. All these experiments indicated a possible role of phytochrome in regulating the UV-B induced changes in plant morphology and chloroplast proteins.