14 research outputs found
Universalities in One-electron Properties of Limit Quasi-periodic Lattices
We investigate one-electron properties of one-dimensional self-similar
structures called limit quasi-periodic lattices. The trace map of such a
lattice is nonconservative in contrast to the quasi-periodic case, and we can
determine the structure of its attractor. It allows us to obtain the three new
features of the present system: 1) The multi-fractal characters of the energy
spectra are {\it universal}. 2) The supports of the -spectra extend
over the whole unit interval, . 3) There exist marginal critical
states.Comment: 4 pages, 2figure
Design Process in the Stage of Changes: Architects Learning New Role
Many researchers spent time analyzing design process, some of them were focused even on architectural design. Many of them presented possible views how to understand (architectural) design. They try to fi nd universal description of what design might be and how and what principles it uses. Concern in their approach is given on Ñconceptualì stage of the design process, or simply all design process is referred as conceptual, with some features of Ñproductì design. That is an aspect, which we, as practitioners, see from a slightly different point of view. It relates to what we consider to be architecture. In our point of view architecture is completed building
Impact of the phosphatidylinositide 3-kinase signaling pathway on the cardioprotection induced by intermittent hypoxia.
BACKGROUND: Exposure to intermittent hypoxia (IH) may enhance cardiac function and protects heart against ischemia-reperfusion (I/R) injury. To elucidate the underlying mechanisms, we developed a cardioprotective IH model that was characterized at hemodynamic, biochemical and molecular levels.
METHODS: Mice were exposed to 4 daily IH cycles (each composed of 2-min at 6-8% O2 followed by 3-min reoxygenation for 5 times) for 14 days, with normoxic mice as controls. Mice were then anesthetized and subdivided in various subgroups for analysis of contractility (pressure-volume loop), morphology, biochemistry or resistance to I/R (30-min occlusion of the left anterior descending coronary artery (LAD) followed by reperfusion and measurement of the area at risk and infarct size). In some mice, the phosphatidylinositide 3-kinase (PI3K) inhibitor wortmannin was administered (24 µg/kg ip) 15 min before LAD.
RESULTS: We found that IH did not induce myocardial hypertrophy; rather both contractility and cardiac function improved with greater number of capillaries per unit volume and greater expression of VEGF-R2, but not of VEGF. Besides increasing the phosphorylation of protein kinase B (Akt) and the endothelial isoform of NO synthase with respect to control, IH reduced the infarct size and post-LAD proteins carbonylation, index of oxidative damage. Administration of wortmannin reduced the level of Akt phosphorylation and worsened the infarct size.
CONCLUSION: We conclude that the PI3K/Akt pathway is crucial for IH-induced cardioprotection and may represent a viable target to reduce myocardial I/R injury