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1.
OR methods and tools are being increasingly applied within the health services domain to support objective decision-making for the effective and efficient provision of resources. Healthcare modelling, however, is beset with many challenges and this paper examines a number of issues that define the primary challenges faced by the modeller in this field. It is fair to say that their resolution determines the likely success or failure of healthcare modelling in general. Working with a number of participating health service organizations, a proposed framework towards successful implementation has evolved and is presented in this paper 相似文献
2.
Overall isothermal melt-crystallization and subsequent melting behavior of metallocene-catalyzed syndiotactic polypropylene resins of various molecular weights were investigated using differential scanning calorimetry (DSC) technique. Two sets of molecular weight range were synthesized with two different metallocene catalyst systems. The kinetics of the overall isothermal melt-crystallization process was analyzed based on various macrokinetic models, i.e. the Avrami, Malkin and Urbanovici-Segal models. The effective activation energy describing the overall isothermal crystallization process over the crystallization temperature range studied was estimated based on an Arrhenius approximation of the obtained Avrami crystallization rate constants. The equilibrium melting temperature for each of these resins was estimated based on the linear and non-linear Hoffman-Weeks extrapolative methods. 相似文献
3.
Santi Tungprapa Tanarinthorn Puangparn Monchawan Weerasombut Ittipol Jangchud Porntiva Fakum Somsak Semongkhol Chidchanok Meechaisue Pitt Supaphol 《Cellulose (London, England)》2007,14(6):563-575
This paper reports an investigation of the effects of solvent system, solution concentration, and applied electrostatic field
strength (EFS) on the morphological appearance and/or size of as-spun cellulose acetate (CA) products. The single-solvent
systems were acetone, chloroform, N,N
-dimethylformamide (DMF), dichloromethane (DCM), methanol (MeOH), formic acid, and pyridine. The mixed-solvent systems were
acetone–DMAc, chloroform–MeOH, and DCM–MeOH. Chloroform, DMF, DCM, MeOH, formic acid, and pyridine were able to dissolve CA,
forming clear solutions (at 5% w/v), but electrospinning of these solutions produced mainly discrete beads. In contrast, electrospinning of the solution of
CA in acetone produced short and beaded fibers. At the same solution concentration of 5% (w/v) electrospinning of the CA solutions was improved by addition of MeOH to either chloroform or DCM. For all the solvent systems
investigated smooth fibers were obtained from 16% (w/v) CA solutions in 1:1, 2:1, and 3:1 (v/v) acetone–DMAc, 14–20% (w/v) CA solutions in 2:1 (v/v) acetone–DMAc, and 8–12% (w/v) CA solutions in 4:1 (v/v) DCM–MeOH. For the as-spun fibers from CA solutions in acetone–DMAc the average diameter ranged between 0.14 and 0.37 μm
whereas for the fibers from solutions in DCM–MeOH it ranged between 0.48 and 1.58 μm. After submersion in distilled water
for 24 h the as-spun CA fibers swelled appreciably (i.e. from 620 to 1110%) but the physical integrity of the fibrous structure
remained intact. 相似文献
4.
A. M. Pitt S. M. Cramer A. B. Czernicki K. Kalghatgi Cs. Horvath B. A. Solomon 《Applied biochemistry and biotechnology》1983,8(1):55-68
Anisotropic polysulfone membranes were prepared with carboxypeptidase G1 embedded in the polymer structure. The enzymatically active flat and hollow-fiber membranes were obtained by precipitating the polymer from solution in an organic mixture in which an aqueous solution of the enzyme had been dispersed. The process has been found to be particularly suitable for the immobilization of enzymes in anisotropic hollow fibers that exhibited no detectable enzyme leakage upon perfusion. The pH profiles measured with the enzyme in free solution and in the embedded form were similar. Kinetic parameters of multitubular enzyme reactors were investigated by measuring the rate of hydrolysis of glutamate from folic acid or methotrexate at different flow rates and substrate concentrations. The relatively slow mass transfer in such reactors was found to affect strongly the observed kinetics. The results of in vitro experiments with 5000 fiber reactors suggest that hollow fiber cartridges prepared with such membranes have clinical potential for the extracorporeal removal of methotrexate from blood. 相似文献
5.
Bogert D Burnstein R Fisk R Fuess S Morfin J Ohska Stutte L Walker JK Bofill J Busza W Eldridge T Friedman JI Goodman MC Kendall HW Kostoulas IG Lyons T Magahiz R Mattison T Mukherjee A Osborne L Pitt R Rosenson L Sandacz A Tartaglia M Taylor FE Verdier R Whitaker S Yeh GP Abolins M Brock R Cohen A Ernwein J Owen D Slate J Weerts H 《Physical review letters》1985,55(6):574-577
6.
Treatment of N-(2-mercaptoethyl)-1,8-naphthalimide (HL) with stoichiometric amounts of AsCl(3) and base affords AsL(2)Cl and AsL(3) complexes stabilized in part by secondary As...O bonding interactions. 相似文献
7.
A. Heiss J. Tardieu De Maleissye V. Viossat K. A. Sahetchian I. G. Pitt 《国际化学动力学杂志》1991,23(7):607-622
The reaction pathways of n-butoxy and s-butoxy radicals have been investigated by TLC and HPLC analysis of end products, particularly peroxides and carbonyl compounds. The butoxy radicals were produced by the pyrolysis of very low concentrations of the corresponding dibutylperoxide in an atmosphere of oxygen and nitrogen, at atmospheric pressure. The decomposition reaction (3) s-BuO → C2H5 + CH3CHO and the reaction (2) s-BuO + O2 → HO2 + CH3COC2H5 have been studied, and the ratio k3/k2 has been determined in the temperature range 363–503 K by kinetic modeling of the formation of the observed acetaldehyde and methylethylketone. The rate constant k3 obtained was: A good agreement was observed between experimental data and RRKM theory. The implications of the results for atmospheric chemistry and combustion are discussed. At room temperature, the reaction with O2, yielding HO2 radicals and methylethylketone is, by far, the main channel for s-BuO radicals. In the field of low temperature combustion, the decomposition of s-BuO radicals producing C2H5 and CH3CHO is the main pathway; the route s-BuO + O2 decreases tremendously in importance as the temperature is raised above 393 K. 相似文献
8.
Strongin B Bofill J Friedman JI Fuess S Goodman MC Kendall HW Kistiakowsky V Lyons T Osborne LS Pitt R Schneekloth U Taylor FE Bogert D Koizumi G Stutte L Abolins M Brock R Cobau W Hatcher R Owen D Perkins G Tartaglia M Weerts H Belusevic R Walker JK White A Womersley J 《Physical review D: Particles and fields》1991,43(9):2778-2786
9.
10.
Michael K. Pitt Sheheryar Malik Arnaud Doucet 《Annals of the Institute of Statistical Mathematics》2014,66(3):527-552
Discrete-time stochastic volatility (SV) models have generated a considerable literature in financial econometrics. However, carrying out inference for these models is a difficult task and often relies on carefully customized Markov chain Monte Carlo techniques. Our contribution here is twofold. First, we propose a new SV model, namely SV–GARCH, which bridges the gap between SV and GARCH models: it has the attractive feature of inheriting unconditional properties similar to the standard GARCH model but being conditionally heavier tailed. Second, we propose a likelihood-based inference technique for a large class of SV models relying on the recently introduced continuous particle filter. The approach is robust and simple to implement. The technique is applied to daily returns data for S&P 500 and Dow Jones stock price indices for various spans. 相似文献