In this paper, the challenging problem of robust mean-signal estimation of a single-step microparticle bioaffinity assay is investigated. For this purpose, a density estimation-based robust algorithm (DER) was developed. The DER algorithm was comparatively evaluated with four other parameter estimation methods (mean value, median filtering, least square estimation, Welsch robust m-estimator). Two important questions were raised and investigated: 1) Which of the five methods can robustly estimate the mean bioaffinity signal? and 2) How many microparticles need to be measured in order to obtain an accurate estimate of the mean signal value? To answer the questions, bootstrap and coefficient of variation (CV) analyses were performed. In the CV analysis, the DER algorithm gave the best results: The CV ranged from 0.8% to 4.9% when the number of microparticles used for the mean signal estimation varied from 800 to 30. In the bootstrap analysis of the standard error, the DER algorithm had the smallest variance. As a conclusion, it can be underlined that: 1) of all methods tested, the DER algorithm gave the most consistent and reproducible results according to the bootstrap and CV analysis; 2) using the DER algorithm accurate estimates could be calculated based on 80-100 particles, corresponding to a typical assay measurement time of 1 min; and 3) the investigated bioaffinity signals contained a large number of outliers (observations that severely deviate from the majority of data) and therefore robust techniques were necessary for the mean signal estimation tasks. 相似文献
Abstract. A hidden Markov regime is a Markov process that governs the time or space dependent distributions of an observed stochastic process. We propose a recursive algorithm for parameter estimation in a switching autoregressive process governed by a hidden Markov chain. A common approach to the recursive estimation problem is to base the estimation on suboptimal modifications of Kalman filtering techniques. The main idea in this paper is to use the maximum likelihood method and from this develop a recursive EM algorithm. 相似文献
Assessed the role of noradrenaline (NA) on the acquisition of an aversively motivated discrimination task and its reversal. A conditioned taste aversion procedure was used. NA depletions were achieved through 2 pharmacological means: systemic N-2 chloroethyl-N-ethyl-2-bromo-benzylamine (DSP4) and destruction of the dorsal noradrenergic bundle (DNAB) with 6-hydroxydopamine (6-OHDA). Both procedures caused marked reductions of NA in the frontal cortex and hippocampus. In neither of the studies (Exp 1, DSP4 and Exp 2, DNAB) were there any significant changes between controls and NA-depleted rats in either the rate of acquisition of the original discrimination (Phase 1) or the subsequent reversal (Phase 2). This occurred irrespective of which of the 2 stimuli (a taste cue or a tongue-tactile cue) initially was used as the conditioned stimulus/stimuli (CS) (the stimulus first followed by contingent administration of lithium chloride and later, by saline injections). Thus NA does not appear to be critically involved in the acquisition and reversal of a taste/tactile discrimination task. The significance of forebrain NA for other discrimination tasks is discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
The effect of varying lanthanum composition upon the formation of the nonsuperconducting La1.67Sr0.33Cu2O5– and the stoichiometry variation tolerance of the ternary system La2–xSrxCuO4 (with x=0 and 0.15) were investigated using a variety of techniques. Results indicate that total conversion to La2CuO4 from freeze-dried precursors with an LaCu = 2.001 ratio is achieved after sintering (1253 K, 12 h) and annealing in oxygen (773 K, 6 h). Small variations in the stoichiometry of solids La2–xSrxCuO4 with x=0 and 0.15 were detected. Lanthanum-deficient composition in the ternary system induces the formation of the non-superconducting phase whose stoichiometry is better represented by La1.60Sr0.40Cu2O5–. The temperature-programmed reduction profiles of the cuprates can be associated with the formation of more or less stable intermediates. 相似文献
Highly crystalline, monophasic LaFeO3 and LaCoO3 perovskites, prepared by the explosion method, are shown to be heterogeneous at surface level. The outmost atomic layers of these perovskites contain high concentrations of carbonate-type species. Their specific activities for methane combustion are in fact identical to La2O2CO3 and air-exposed La2O3. These results compared with pertinent data from the literature hint that surface heterogeneity may be often present in mixed oxides catalysts. 相似文献
Summary: Propylene was copolymerized with 10‐undecen‐1‐ol using dimethylsilanylbis(2‐methyl‐4‐phenyl‐1‐indenyl)zirconium dichloride as catalyst and MAO and TIBA as cocatalysts. Comonomer incorporations from 0.1 to 0.9 mol‐% (0.5 to 3.6 wt.‐%) were obtained. These hydroxyl functionalized copolymers were applied as compatibilizers to PP/PA6 blend with a composition of 70/30. For comparison, hydroxyl functionalized polyethylene prepared with metallocene catalyst and commercial MAH grafted ethylene butyl acrylate (E/BA/MAH) and poly(propylene) (PP‐g‐MAH) were also used as compatibilizers. Effects of the compatibilizers on morphology and mechanical and thermal properties of the blends were studied. Enhanced adhesion between the blend components was observed in morphology and dynamic mechanical studies. Although improvement in toughness was not as pronounced as expected, there were indications that the hydroxyl functionalized propylene copolymers prepared with metallocene catalysts could serve as a new type of compatibilizer in polymer blends.
SEM micrograph (5 000×) of an PP/PA6/PP‐co‐OH4 blend. 相似文献
Particulate air pollution has been associated with lung and cardiovascular disease, for which lung inflammation may be a driving
mechanism. The pro-inflammatory cytokine, tumor necrosis factor (TNF) has been suggested to have a key-role in particle-induced
inflammation. 相似文献
A bench-scale experimental setup has been used to study the conditions necessary for smouldering ignition in four types of loose-fill wood fibre thermal insulation, and to study the development of the smouldering process. The products varied with regard to wood species, grain size and fire retardant chemical additives. The test material was placed in an insulated open top container and heated from below. Temperatures within the sample and mass loss were measured during the tests. Both the fibre size and the level of added fire retardant seem to influence the smouldering ignition. Two different types of smouldering were identified in this study. Materials undergoing smouldering Type 1 obtained maximum temperatures in the range 380°C to 440°C and a total mass loss of 40 wt% to 50 wt%. Materials undergoing smouldering Type 2 obtained maximum temperatures in the range 660°C to 700°C and a total mass loss of 80 wt% to 90 wt%. This implies that Type 2 smouldering involves secondary char oxidation, which represents a risk for transition to flaming combustion and thereby a considerable fire hazard. This has been an exploratory project and the results must therefore be considered as indicative. The findings may, however, have implications for fire safety in the practical use of loose-fill wood fibre insulation in buildings, and further experimental studies should be performed with this in mind to obtain more knowledge about the topic. 相似文献