In most stochastic decision problems one has the opportunity to collect information that would partially or totally eliminate the inherent uncertainty. One wishes to compare the cost and value of such information in terms of the decision maker's preferences to determine an optimal information gathering plan. The calculation of the value of information generally involves oneor more stochastic recourse problems as well as one or more expected value distribution problems. The difficulty and costs of obtaining solutions to these problems has led to a focus on the development of upper and lower bounds on the various subproblems that yield bounds on the value of information. In this paper we discuss published and new bounds for static problems with linear and concave preference functions for partial and perfect information. We also provide numerical examples utilizing simple production and investment problems that illustrate the calculations involved in the computation of the various bounds and provide a setting for a comparison of the bounds that yields some tentative guidelines for their use. The bounds compared are the Jensen's Inequality bound,the Conditional Jensen's Inequality bound and the Generalized Jensen and Edmundson-Madansky bounds. 相似文献
Our study focuses on the incorporation of β-CD into the HA structure, its effects on the phase of HA and the biological responses to proteins and blood cells. Hydroxyapatite (HA) containing levels of β-cyclodextrin (β-CD) of upto 0.9 wt% has been produced by co-precipitation method. The complexes were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TG) and differential scanning analysis (DSC) methods. The size of the complexes as analyzed using DLS (dynamic light scattering) was between 150 nm and 350 nm. The results show that an increase in concentration of β-CD in the prepared samples that leads to an increase in hydrophobicity seems to promote an affinity for albumin adsorption. The PAGE results were substantiated by Lowry measurements and the results reveal that the H2 (containing 0.7 wt% β-CD) sample shows around 40% increase in albumin adsorption when compared to the H1 (containing 0.5 wt% β-CD) sample. The preferential adsorption of albumin has not been demonstrated in vivo. The ability to design particles that can preferentially interact with particular protein can obtain desired targeting effects. So the results indicate that HA/β-CD complexes have immense potential in targeted delivery of drugs. The in vivo potential of the developed samples was further confirmed in vitro by the results of cell aggregation and haemolytic activity. 相似文献
Reverse thermal gels have numerous biomedical implications, as they undergo physical gelation upon temperature increases and can incorporate biomolecules to promote tissue repair. Such a material is developed for the sustained release of bevacizumab (Avastin), a drug used to treat age‐related macular degeneration. The polymer, poly(ethylene glycol)‐poly(serinol hexamethylene urethane) (ESHU), forms a physical gel when heated to 37 °C and shows good cytocompatibility with ocular cells. ESHU is capable of sustaining bevacizumab release over 17 weeks in vitro, and the release kinetics can be altered by changing the drug dose and the ESHU concentration. These results suggest that ESHU is biologically safe, and suitable for ocular drug delivery.
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