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排序方式: 共有409条查询结果,搜索用时 15 毫秒
1.
Bing Yong HSIE 《数学学报(英文版)》2006,22(2):507-514
This paper gives a p-adic analogue of the Mackey theory, which relates representations of a group of type G - H × t A to systems of imprimitivity. 相似文献
2.
Smooth Solutions to Optimal Investment Models with Stochastic Volatilities and Portfolio Constraints
Pham 《Applied Mathematics and Optimization》2002,46(1):55-78
Abstract. This paper deals with an extension of Merton's optimal investment problem to a multidimensional model with stochastic volatility
and portfolio constraints. The classical dynamic programming approach leads to a characterization of the value function as
a viscosity solution of the highly nonlinear associated Bellman equation. A logarithmic transformation expresses the value
function in terms of the solution to a semilinear parabolic equation with quadratic growth on the derivative term. Using a
stochastic control representation and some approximations, we prove the existence of a smooth solution to this semilinear
equation. An optimal portfolio is shown to exist, and is expressed in terms of the classical solution to this semilinear equation.
This reduction is useful for studying numerical schemes for both the value function and the optimal portfolio. We illustrate
our results with several examples of stochastic volatility models popular in the financial literature. 相似文献
3.
4.
Activation of myosin II by phosphorylation of the 20 kDa regulatory light chains (LC20) has been implicated in numerous contractile and motile events, e.g., smooth muscle contraction, cytokinesis, and cell migration. The ability to analyze LC20 phosphorylation in minute samples is critical to determine the importance of LC20 phosphorylation in diverse physiological processes. We have developed a method for the separation and quantification of unphosphorylated, monophosphorylated, and diphosphorylated LC20 with a detection limit of 1 pg (50 amol). LC20 is initially isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transblotted to a polyvinlyidene difluoride (PVDF) membrane. The region of the membrane containing the LC20 band (identified by electrophoresis of purified LC20 in a neighboring lane) is cut out and fluorescently labeled with Alexa Fluor 488 C5 maleimide. The labeled LC20 is eluted from the membrane with detergent and subjected to capillary isoelectric focusing (CIEF) to separate unphosphorylated, mono-, and diphosphorylated LC20, which are detected and quantified by laser-induced fluorescence (LIF). A linear relationship between log(peak area) and log(LC20 amount) is observed over the range of 50 amol-150 fmol. Quantification of LC20 phosphorylation by CIEF with LIF detection was compared with three commonly used methods with much lower levels of sensitivity: urea/glycerol-PAGE with Western blotting, phosphorylation by [gamma-32P]ATP with Cerenkov counting, and phosphorylation by [gamma-32P]ATP followed by SDS-PAGE, autoradiography, and scanning densitometry. All four methods gave very similar quantitative results, the major difference being that the new method exhibits 3000-fold enhanced sensitivity. This method is therefore applicable to quantitative analysis of phosphorylation of minute quantities of LC20. 相似文献
5.
Onk-StrictlyConvexandk-VerySmoothBanachSpacesZhangZihou(张子厚)(HuainanTelecisionUniversity,Huainan,Anhui,232001)Abstract:Inthis... 相似文献
6.
Kehayias JJ 《Analytical and bioanalytical chemistry》2004,379(2):188-191
Body composition has become the main outcome of many nutritional intervention studies including osteoporosis, malnutrition, obesity, AIDS, and aging. Traditional indirect body composition methods developed with healthy young adults do not apply to the elderly or diseased. Fast neutron activation (for N and P) and neutron inelastic scattering (for C and O) are used to assess in vivo elements characteristic of specific body compartments. Non-bone phosphorus for muscle is measured by the 31P(n,)28Al reaction, and nitrogen for protein via the 14N(n,2n)13N fast neutron reaction. Inelastic neutron scattering is used to measure total body carbon and oxygen. Body fat is derived from carbon after correcting for contributions from protein, bone, and glycogen. Carbon-to-oxygen ratio (C/O) is used to measure the distribution of fat and lean tissue in the body and to monitor small changes of lean mass. A sealed, D–T neutron generator is used for the production of fast neutrons. Carbon and oxygen mass and their ratio are measured in vivo at a radiation exposure of less than 0.06 mSv. Gamma-ray spectra are collected using large BGO detectors and analyzed for the 4.43 MeV state of carbon and 6.13 MeV state of oxygen, simultaneously with the irradiation. P and N analysis by delayed fast neutron activation is performed by transferring the patient to a shielded room equipped with an array of NaI(Tl) detectors. A combination of measurements makes possible the assessment of the quality of fat-free mass. The neutron generator system is used to evaluate the efficacy of new treatments, to study mechanisms of lean tissue depletion with aging, and to investigate methods for preserving function and quality of life in the elderly. It is also used as a reference method for the validation of portable instruments of nutritional assessment. 相似文献
7.
A.E. Bolzan 《Journal of Electroanalytical Chemistry》1995,380(1-2)
The voltammetric behaviour of smooth palladium electrodes in 1 M NaOH is studied in the potential range related to the thermodynamic stability of water. The electrosorption of H atoms on bulk Pd appears as a reversible reaction coupled to a diffusion process which occurs within bulk Pd. The voltammetric electrodesorption of H from bulk Pd is a process under mixed control, i.e. the diffusion from the bulk and the surface oxidation of H atoms. Fast pseudocapacitive reactions are detected in the range 0.2–0.4 V associated with the adsorption of H atoms at the submonolayer level. The initial stages of Pd oxide layer formation, at ca. 0.68 V, involves two reversible stages. The Pd oxide monolayer formation is achieved at 1.25 V/RHE and is followed by the formation of a third reversible system. This system is enhanced by an excursion in the potential range of the oxygen evolution reaction. This reversible system is probably a redox system involving Pd(II)/Pd(IV) species. The voltammetric electroreduction of the Pd oxide film shows rather irreversible behaviour. Inhibition effects on the reversible adsorption of H atoms due to residual oxide species were observed as well as inhibition on loading the Pd electrode with hydrogen to form the (α + β)-PdH phase. Rotating ring-disc experiments demonstrate that Pd electrodissolution in basic solutions is much smaller than in acid solutions. However, soluble palladium species are detected, especially during the formation of the fast redox systems, in the potential range related to Pd oxide layer growth. 相似文献
8.
An europium-sensitized time-resolved luminescence (TRL) method was developed to determine oxytetracycline (OTC) in cultivated catfish muscle. Extraction of OTC from fish muscle was performed with pH 4.0 ethylenediaminetetraacetic acid (EDTA)-McIlvaine buffer and clean up with hydrophilic-lipophilic balanced copolymer solid phase extraction (SPE) cartridges. The eluate was used without further concentration for TRL measurement in pH 9.0 micellar tris(hydroxylmethyl)aminomethane (TRIS) buffer. Cetyltrimethylammonium chloride (CTACl) was used as surfactant and EDTA as a co-ligand. The excitation and emission wavelengths were set at 388 and 615 nm, respectively. The linear dynamic range was 0-1000 ng g−1 (R2=0.9995). The recovery was 92-112% in the fortification range of 50-200 ng g−1 and the limits of detection (LOD) ranged from 3 to 7 ng g−1. Incurred catfish samples were used to demonstrate the performance of the method around 100 ng g−1, the European Union maximum residue level. 相似文献
9.
10.
Training with blood flow restriction could lead to an effect on skin temperature. Additionally, this effect could be higher in people with lower physical fitness level due to their lower capacity of heat loss. The aim of this preliminary study was therefore to evaluate the effects of training experience on the acute and chronic thermal skin responses after performing exercise with and without blood flow restriction. The study included ten men, of these, five were trained. All subjects performed tests and re-tests for maximum strength (1 repetition maximum) through unilateral leg extensions (right thigh at 45 ± 6.7 kg and left thigh at 45.5 ± 8.1 kg, p > 0.05). The protocol consisted of four sets to concentric failure, with one-minute rest intervals between sets at an intensity corresponding to 40% of 1 RM. There were 7-day intervals between experimental sessions (150 mmHg versus unrestricted flow restriction). The thermal images were made before the protocol (pre), immediately after the end of the series (post), and 24 h afterward (post 24 h). When comparing temperature variation (Δ exercise and Δ 24 h) between groups, it was observed that the trained participants showed a greater drop in temperature 24 h after exercise with 150 mmHg restriction (confidence interval: 95% of Δ 24 h [−0.2 to −0.9 °C]) compared to untrained subjects (p = 0.006 and ES > 1.5, confidence interval: 95% Δ 24 h [−0.1 to 0.6 °C].) In conclusion, this preliminary study showed that training experience interferes with the chronic cutaneous thermal temperature of the anterior thigh when strength training associated with blood flow restriction 150 mmHg was performed. 相似文献