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51.
The scientific world is, as I have often repeated, a shadow world, shadowing a world familiar to our consciousness. Just how much do we expect it to shadow? We do not expect it to shadow all that is in our mind, emotions, memory, etc. In the main we expect it to shadow impressions which can be traced to external sense organs. But time makes a dual entry and thus forms an intermediate link between the internal and the external. This is shadowed partially by the scientific world of primary physics (which excludes time's arrow), but fully when we enlarge the scheme to include entropy. Therefore by the momentous departure in the nineteenth century the scientific world is not confined to a static extension around which the mind may spin a romance of activity and evolution; it shadows that dynamic quality of the familiar world which cannot be parted from it without disaster to its significance.—Arthur Eddington,The Nature of the Physical World. 相似文献
52.
L. R. Abramo L. Brenig E. Gunzig Alberto Saa 《International Journal of Theoretical Physics》2003,42(6):1145-1152
We investigate the dynamics of Einstein equations in the vicinity of the two recently described types of singularity of anisotropic and homogeneous cosmological models described by the action
with general F() and V(). The dynamical nature of each singularity is elucidated, and we show that both are, in general, dynamically unavoidable, reinforcing the unstable character of previous isotropic and homogeneous cosmological results obtained for the conformal coupling case. 相似文献
53.
Boron-nitrilotriacetate,N(CH2COO)3B: Synthesis and Crystal-Structure Determinations at 293K and 110K
The title compound is insoluble in aprotic solvents and decomposes in protic ones. Its crystal structure consists of discrete molecules with non-crystallographic C30-symmetry and a transannular dative B? N bond (1.620(3) (Å). The molecules pack tightly (density 1.804 g cm?2) interacting via O…C contacts between carbonyl groups (2.92–3.05 Å)). The atoms show small vibrational motion which may be interpreted in terms of a rigid body model. Distances and angles obtained at 293 and 110 were corrected for effects of rigid body motion and do not show significant differences. 相似文献
54.
Zecchin KG Alberici LC Riccio MF Eberlin MN Vercesi AE Graner E Catharino RR 《Rapid communications in mass spectrometry : RCM》2011,25(3):449-452
Fatty acid synthase (FASN) is the metabolic enzyme responsible for the endogenous synthesis of the saturated long-chain fatty acid palmitate. In contrast to most normal cells, FASN is overexpressed in a variety of human cancers including cutaneous melanoma, in which its levels of expression are associated with a poor prognosis and depth of invasion. Recently, we have demonstrated the mitochondrial involvement in FASN inhibition-induced apoptosis in melanoma cells. Herein we compare, via electrospray ionization mass spectrometry (ESI-MS), free fatty acids (FFA) composition of mitochondria isolated from control (EtOH-treated cells) and Orlistat-treated B16-F10 mouse melanoma cells. Principal component analysis (PCA) was applied to the ESI-MS data and found to separate the two groups of samples. Mitochondria from control cells showed predominance of six ions, that is, those of m/z 157 (Pelargonic, 9:0), 255 (Palmitic, 16:0), 281 (Oleic, 18:1), 311 (Arachidic, 20:0), 327 (Docosahexaenoic, 22:6) and 339 (Behenic, 22:0). In contrast, FASN inhibition with Orlistat changes significantly mitochondrial FFA composition by reducing synthesis of palmitic acid, and its elongation and unsaturation products, such as arachidic and behenic acids, and oleic acid, respectively. ESI-MS of mitochondria isolated from Orlistat-treated cells presented therefore three major ions of m/z 157 (Pelargonic, 9:0), 193 (unknown) and 199 (Lauric, 12:0). These findings demonstrate therefore that FASN inhibition by Orlistat induces significant changes in the FFA composition of mitochondria. 相似文献