The dynamics of tracers in crowded matrix is of interest in various areas of physics, such as the diffusion of proteins in living cells. By using two-dimensional (2D) Langevin dynamics simulations, we investigate the diffusive properties of a tracer of a diameter in crowded environments caused by randomly distributed crowders of a diameter. Results show that the emergence of subdiffusion of a tracer at intermediate time scales depends on the size ratio of the tracer to crowders δ. If δ falls between a lower critical size ratio and a upper one, the anomalous diffusion occurs purely due to the molecular crowding. Further analysis indicates that the physical origin of subdiffusion is the "cage effect". Moreover, the subdiffusion exponent α decreases with the increasing medium viscosity and the degree of crowding, and gets a minimum αmin=0.75 at δ=1. At long time scales, normal diffusion of a tracer is recovered. For δ≤1, the relative mobility of tracers is independent of the degree of crowding. Meanwhile, it is sensitive to the degree of crowding for δ>1. Our results are helpful in deepening the understanding of the diffusive properties of biomacromolecules that lie within crowded intracellular environments, such as proteins, DNA and ribosomes. 相似文献
Wine derives its economic value to a large extent from geographical origin, which has a significant impact on the quality of the wine. According to the food legislation, wines can be without geographical origin (table wine) and wines with origin. Wines with origin must have characteristics which are essential due to its region of production and must be produced, processed and prepared, exclusively within that region. 相似文献
Incorporating further information into the ordered weighted averaging (OWA) operator weights is investigated in this paper. We first prove that for a constant orness the minimax disparity model [13] has unique optimal solution while the modified minimax disparity model [16] has alternative optimal OWA weights. Multiple optimal solutions in modified minimax disparity model provide us opportunity to define a parametric aggregation OWA which gives flexibility to decision makers in the process of aggregation and selecting the best alternative. Finally, the usefulness of the proposed parametric aggregation method is illustrated with an application in metasearch engine. 相似文献
Naturally occurring radionuclides (NORN) such as 40K, 226Ra and 232Th from 44 surface sediment samples collected from four desert regions of Chinese were determined to investigate the regional
characteristics of the source areas of Asian dust. The radionuclides for 41 surface sediment samples collected from seven
sites of the Keum River area in Korea were also determined to compare the regional characteristics with the Chinese desert
area. The specific activities (SA) and the specific activity ratios (SAR) of the radionuclides were investigated for distinguishing
the source region of Asian dust. The SA of 226Ra and 232Th as well as the SAR of 226Ra/40K and 232Th/40K were found to be useful to characterize source area and tracing Asian dust. 相似文献
The slant from horizontal size disparity is geometrically predictable. The apparent slant, however, is usually not equivalent
to the prediction as numerous visual factors affect it. The aim of this study is to examine whether the vertical angular subtense
of a stimulus with horizontal size disparity alters the magnitude of perceived slant for a given horizontal angular subtense.
The results indicate that a smaller angular subtense of display produces a smaller magnitude of slant perception. 相似文献
Abstract We show that with symmetric agents, noncooperation is the only stable coalition structure in a fishery with more than two countries. In the case of asymmetric fishing nations, partial or full cooperation may be stable even if the number of countries exceeds two. These are important results for recent fisheries economics papers that have not allowed for coalition formation. As an example how of one can use the model, we study the problem of new entrants into Regional Fisheries Management Organizations (RFMOs). We show that depending on the economic structure of the fishery, new entrants may make cooperation more difficult or easier. 相似文献
Anesthesia for diagnostic procedures, e.g., MRI measurements, has increasingly used sevoflurane and nitrous oxide in recent years. Sevoflurane and nitrous oxide are known cerebrovasodilatators, however, which potentially interferes with MRI examination of cerebral hemodynamics. To compare the effects of relevant equianesthetic concentrations (0.4 MAC) of both drugs on regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) we used contrast-enhanced magnetic resonance imaging (MRI) perfusion measurement, which has the advantage of providing regional anatomic resolution.
Sevoflurane increased rCBF more than did nitrous oxide in all regions except in parietal and frontal gray matter. Nitrous oxide, by contrast, increased rCBV in most of the gray matter regions more than did sevoflurane. In summary we show that, in contrast to nitrous oxide, sevoflurane supratentorially reversed the anterior-posterior gradient in rCBF and typically redistributed rCBF to infratentorial gray matter. In contrast, nitrous oxide increased rCBV more than did sevoflurane. Both inhalational anesthetics had a drug-specific influence on cerebral hemodynamics, which is of importance when interpreting MRI studies of cerebral hemodynamics in anesthetized patients. 相似文献