The application of a sequential procedure with elimination as a method for the screening for metabolic diseases

A sequential classification procedure with early elimination, for the screening for metabolic diseases, is presented. Asymptotic properties of the procedure are derived in the Appendix and it is shown that the procedure is asymptotically distribution-free under certain assumptions, and asymptotically at least as efficient as a comparable fixed-sample procedure. With the use of data obtained from 36 mentally retarded patients, the procedure was evaluated by means of a bootstrap simulation. The procedure was then applied to this set of data, with satisfactory results and a considerable economy in observations.     

A multiple-tubes approach for accurate genotyping of very small DNA samples by using PCR: statistical considerations.

A multiple-tubes procedure is described for using PCR to determine the genotype of a very small DNA sample. The procedure involves dividing the sample among several tubes, then amplifying and typing the contents of each tube separately. The results are analyzed by a statistical procedure which determines whether a genotype can be conclusively assigned to the DNA sample. Simulation studies show that this procedure usually gives correct results even when the number of double-stranded fragments in the sample is as small as 30. The procedure remains effective even in the presence of small amounts of laboratory contamination. We find that the multiple-tubes procedure is superior to the standard one-tube procedure, either when the sample is small or when laboratory contamination is a potential problem; and we recommend its use in these situations. Because the procedure is statistical, it allows the degree of certainty in the result to be quantified and may be useful in other PCR applications as well.     

Efficacy of activated sludge in removing Cryptosporidium parvum oocysts from sewage.

Primary clarifier effluent (procedure B) and final effluent (procedure A) from a wastewater treatment plant were enriched with Cryptosporidium parvum oocysts obtained from the feces of naturally infected calves. Procedure B samples alone were subjected to a laboratory simulation of activated-sludge treatment. Coccidium-free neonatal CD-1 mice were then inoculated intragastrically with procedure A or procedure B samples. Seven days after inoculation, the intensity of oocyst infection in procedure B mice was 91% less than in procedure A mice (controls).     

Efficacy of activated sludge in removing Cryptosporidium parvum oocysts from sewage.

Primary clarifier effluent (procedure B) and final effluent (procedure A) from a wastewater treatment plant were enriched with Cryptosporidium parvum oocysts obtained from the feces of naturally infected calves. Procedure B samples alone were subjected to a laboratory simulation of activated-sludge treatment. Coccidium-free neonatal CD-1 mice were then inoculated intragastrically with procedure A or procedure B samples. Seven days after inoculation, the intensity of oocyst infection in procedure B mice was 91% less than in procedure A mice (controls).     

Measurement of delay discounting using trial-by-trial consequences

DELAY DISCOUNTING IN HUMANS WAS INVESTIGATED USING THREE DIFFERENT PROCEDURES: a frequently used discounting procedure with hypothetical rewards and delays; a procedure with hypothetical rewards and delays compressed down to much smaller values; and a contingent procedure in which each choice had a direct consequence. In the contingent procedure, on every trial, participants actually experienced the delay and obtained the reward amount associated with their choice. Each participant was exposed to all three procedures. Orderly temporal discounting patterns were obtained in all three procedures and described well by a hyperbolic model. Comparisons of the data revealed patterns unique to each procedure. The distributions of the discounting measures differed across the three procedures. In the contingent procedure, several subjects showed no discounting, e.g. complete self-control. Procedural factors in studies of impulsivity are discussed, and suggestions are offered for experiments in which the contingent-discounting procedure may prove useful.     

AFP蛋白芯片技术的检测流程优化

目的:通过优化现有的蛋白芯片检测过程,在保证检测准确性的同时缩短甲胎蛋白(Alpha Fetal protein,AFP)的检测时间,提高检测效率,为原发性肝癌的筛查提供经济、便捷、省时、有效的检测方法。方法:本研究在传统蛋白芯片检测流程(1-1.5小时)的基础上,通过优化检测流程将检测时间缩短至18分钟,并且通过和传统方法进行比较,评价该优化方法的检测效能。结果:与传统蛋白芯片检测方法相比,本优化方法的检测时间缩短至18分钟。重复检测同一样本,传统方法 AFP水平为16.50±1.172ng/m L,优化方法 AFP水平为18.33±1.029 ng/m L,结果无明显统计学差异(P=0.251)。结论:本研究成功地优化了AFP的蛋白芯片检测流程,在缩短检测时间的同时,保证了检测的准确率,是一种经济省时易操作的AFP检测方法。     

生物大分子结晶学中的刚体修正方法

刚体修正方法是修正生物大分子初结构的取向和位置的一个很有效的方法.本文简要地介绍了Fourier搜索法,CORELS刚体修正法及TRAREF刚体修正法三种方法,并给出了它们在不同的蛋白质结构测定中应用的结果.     

Normalizing upper trapezius EMG amplitude: Comparison of ramp and constant force procedures

The present study compared three procedures for normalization of upper trapezius surface electromyographic (EMG) amplitudes: (a) a ramp procedure (providing data in per cent of maximal voluntary contraction, MVC); (b) a constant force procedure based on two reference contractions (two-force procedure) (%MVC) and (c) a procedure expressing muscle activation in per cent of a reference voluntary electrical activity (%RVE). The study also evaluated the repeatability of the ramp and the RVE procedures and estimated the force exertion (%MVC) corresponding to the RVE. To illustrate the ergonomic effect of different normalization procedures, trapezius EMG during two work tasks was compared after normalization by the two-force and the RVE procedures. Fifteen subjects participated in the whole study. We found that force estimates obtained by the ramp procedure equation could be translated to force estimates obtained by the two-force procedure by the equation: %MVC_2force = − 0.6 + 0.9*%MVC_ramp, although with a considerable imprecision due to large inter-individual differences. In the ramp procedure, the intra-individual test-retest coefficient of variation (CV) depended on the force level; it was 45% at 5% MVC and 10% at 30% MVC. The CV of the RVE was 15%. The reference contraction used in the RVE procedure corresponded from 13–79% MVC (median 33%MVC). The load reducing effect of an ergonomic intervention was less obvious with the RVE procedure than with the two-force procedure due to a larger inter-individual variation. The advantages and disadvantages of the different procedures are discussed.     

A two-step procedure for automatic and accurate segmentation of volumetric CLSM biofilm images

This paper presents a robust two-step segmentation procedure for the study of biofilm structure. Without user intervention, the procedure segments volumetric biofilm images generated by a confocal laser scanning microscopy (CLSM). This automated procedure implements an anisotropic diffusion filter as a preprocessing step and a 3D extension of the Otsu method for thresholding. Applying the anisotropic diffusion filter to even low-contrast CLSM images significantly improves the segmentation obtained with the 3D Otsu method. A comparison of the results for several CLSM data sets demonstrated that the accuracy of this procedure, unlike that of the objective threshold selection algorithm (OTS), is not affected by biofilm coverage levels and thus fills an important gap in developing a robust and objective segmenting procedure. The effectiveness of the present segmentation procedure is shown for CLSM images containing different bacterial strains. The image saturation handling capability of this procedure relaxes the constraints on user-selected gain and intensity settings of a CLSM. Therefore, this two-step procedure provides an automatic and accurate segmentation of biofilms that is independent of biofilm coverage levels and, in turn, lays a solid foundation for achieving objective analysis of biofilm structural parameters.     

术前参观对冠状动脉介入治疗患者焦虑的影响

目的:探讨术前参观对择期进行心脏介入术患者心理焦虑的影响。方法:将400例择期行心脏介入手术的患者分为参观组和对照组,对照组术前采用常规护理干预,参观组患者在此基础上进行术前参观,熟悉环境,了解手术过程。调查比较两组患者术前2日及术前1小时的焦虑值。结果:参观组与对照组术前2日焦虑值无明显差异,术前1小时参观组焦虑值明显低于对照组,差异具有统计学意义(P0.05)。结论:通过术前参观能够减轻患者的焦虑程度。     

An adaptive single-step FDR procedure with applications to DNA microarray analysis

The use of multiple hypothesis testing procedures has been receiving a lot of attention recently by statisticians in DNA microarray analysis. The traditional FWER controlling procedures are not very useful in this situation since the experiments are exploratory by nature and researchers are more interested in controlling the rate of false positives rather than controlling the probability of making a single erroneous decision. This has led to increased use of FDR (False Discovery Rate) controlling procedures. Genovese and Wasserman proposed a single-step FDR procedure that is an asymptotic approximation to the original Benjamini and Hochberg stepwise procedure. In this paper, we modify the Genovese-Wasserman procedure to force the FDR control closer to the level alpha in the independence setting. Assuming that the data comes from a mixture of two normals, we also propose to make this procedure adaptive by first estimating the parameters using the EM algorithm and then using these estimated parameters into the above modification of the Genovese-Wasserman procedure. We compare this procedure with the original Benjamini-Hochberg and the SAM thresholding procedures. The FDR control and other properties of this adaptive procedure are verified numerically.     

Beta diversity reconsidered

A simple analytical procedure to test for differences in beta diversity among sets of plots has been recently presented. Here, we describe an improved randomization procedure that replaces the one previously proposed. This procedure consists of shuffling within-group dissimilarities among groups and disregarding between-group dissimilarities. By repeating this operation many times, a distribution of the test statistics under the null hypothesis of no differences in the mean plot-to-plot dissimilarities within groups is obtained. This procedure ensures that the correct null model is selected. To describe this new procedure, we used plant and water beetle (Coleoptera) data collected from 45 permanent ponds. Beta diversity was compared between plant and water beetle (Coleoptera) assemblages.     

Inverse analysis of constitutive models: biological soft tissues

The paper describes a procedure for estimating the material parameters of biological soft tissue by fitting model prediction to experimental load-deformation data. This procedure minimizes the error between data and theoretical model prediction through systematically adjusting the parameters in the latter. The procedure uses commercially available software and is not specific to any particular model; nevertheless, for illustration purposes, we employ a six parameter fibril-reinforced poroelastic cartilage model. We are able to estimate any and all of these parameters by the procedure. Convergence of the parameters and convergence of the arbitrary initial stress relaxation to the data was demonstrated in all cases. Though we illustrate the optimization procedure here for unconfined compression only, it can be adapted easily to other experimental configurations such as confined compression, indentation and tensile test. Furthermore, the procedure can be applied in other areas of biomechanics where material parameters need to be extracted from experimental data.     

DNA probe attachment on plastic surfaces and microfluidic hybridization array channel devices with sample oscillation

DNA probe immobilization on plastic surfaces and device assembly are both critical to the fabrication of microfluidic hybridization array channel (MHAC) devices. Three oligonucleotide (oligo) probe immobilization procedures were investigated for attaching oligo probes on four different types of plastic surfaces (polystyrene, polycarbonate, poly(methylmethacrylate), and polypropylene). These procedures are the Surmodics procedure, the cetyltrimethylammonium bromide (CTAB) procedure, and the Reacti-Bind procedure. To determine the optimal plastic substrate and attachment chemistry for array fabrication, we investigated plastic hydrophobicity, intrinsic fluorescence, and oligo attachment efficiency. The Reacti-Bind procedure is least effective for attaching oligo probes in the microarray format. The CTAB procedure performs well enough to use in array fabrication, and the concentration of CTAB has a significant effect on oligo immobilization efficiency. We also found that use of amine-modified oligo probes resulted in better immobilization efficiency than use of unmodified oligos with the CTAB procedure. The oligo probe immobilization on plastic surfaces by the Surmodics procedure is the most effective with regard to probe spot quality and hybridization sensitivity. A DNA hybridization assay on such a device results in a limit of detection of 12pM. Utilizing a CO(2) IR laser machining and adhesive layer approach, we have developed an improved procedure for realizing a DNA microarray inside a microfluidic channel. This device fabrication procedure allows for more feasible spot placement in the channel and reduced sample adsorption by adhesive tapes used in the fabrication procedure. We also demonstrated improved hybridization kinetics and increased detection sensitivity in MHAC devices by implementing sample oscillation inside the channel. A limit of detection of 5pM has been achieved in MHAC devices with sample oscillation.     

Development of sequential multiple comparison procedure for dose response test

We propose a multiple comparison procedure to identify the minimum effective dose level by sequentially comparing each dose level with the zero dose level in the dose finding test. If we can find the minimum effective dose level at an early stage in the sequential test, it is possible to terminate the procedure in the dose finding test after a few group observations up to the dose level. Thus, the procedure is viable from an economical point of view when high costs are involved in obtaining the observations. In the procedure, we present an integral formula to determine the critical values for satisfying a predefined type I familywise error rate. Furthermore, we show how to determine the required sample size in order to guarantee the power of the test in the procedure. In practice, we compare the power of the test and the required sample size for various configurations of the population means in simulation studies and adopt our sequential procedure to the dose response test in a case study.     

Comparison of Two Procedures for Detection of Salmonella in Food, Feed, and Pharmaceutical Products

A survey of food, feed, and pharmaceutical products was undertaken to compare an accelerated Salmonella detection procedure by enrichment serology (ES) to the traditional procedure outlined in the Bacteriological Analytical Manual (BAM). Excellent agreement between the two methods was obtained in the results of 689 test samples involving 35 different products. In addition to being more rapid and simpler to perform, the ES procedure was just as accurate and sensitive as the BAM procedure.     

Accelerated Procedure for Salmonella Detection in Dried Foods and Feeds Involving Only Broth Cultures and Serological Reactions

A procedure has been developed in which Salmonella can be detected in dried foods and feeds within 50 hr. This includes preenrichment (18 hr), selective enrichment (24 hr), elective enrichment (6 to 8 hr), and serological testing (2 hr). The procedure is as sensitive as the more time-consuming, traditional (plating, biochemical, and serological) procedure which may require at least 4 to 5 days. The new procedure is rapid and accurate in comparison to traditional procedures. Moreover, it is simple and inexpensive to perform. As described, the procedure does not necessitate the isolation of pure cultures, but this step is performed easily if desired.     

Stepwise Variable Selection in Classification Problems

Two variable selection procedures are evaluated for classification problems: a forward stepwise discrimination procedure, and a stepwise procedure preceded by a preliminary screening of variables on the basis of individual t statistics. Expected probability of correct classification is used as the measure of performance. A comparison is made of the procedures using samples from multi-variate normal populations and from several nonnormal populations. The study demonstrated some situations where the use of all variables is preferable to the use of a stepwise discriminant procedure stopping after a few steps, though usually the latter procedure was superior in performance. However where the stepwise procedure performed better than using all variables, the modified stepwise procedure performed still better. The use of modified stepwise procedures in which not all the covariances of the problem need be estimated seems promising.     

Displacement imprinted polymer receptor analysis (DIPRA) for chlorophenolic contaminants in drinking water and packaging materials

The preparation of a molecularly imprinted polymer (MIP) for pentachlorophenol is described together with two alternative reporter derivatives for use in a displacement imprinted polymer receptor analysis (DIPRA) format procedure. In this procedure, alternative reporter molecules were rebound to the synthetic receptor sites and their displacement by the target analyte was employed as the basis of a simple procedure for the measurement of chlorophenols in water and packaging material samples. Water samples were extracted using the standard procedure (EPA 528) and a detection limit of 0.5 microg l(-1) was achieved using the DIPRA detection method, with good agreement between the displacement technique and GC-ECD analysis. A variety of packaging materials, extracted using a buffered detergent solution were also analysed using the DIPRA procedure and showed good agreement with GC results. In addition, investigation of the cross-reactivity of a range of pesticides and materials commonly encountered in environmental analysis indicated the procedure gave good discrimination between pesticides bearing a chlorophenolic moiety and other materials. The procedure is considered highly suitable for use as a rapid field-test method or for incorporation into a test kit device.     

A simultaneous procedure facilitates acquisition under an optimal interstimulus interval in artificial neural networks and rats

In a computer simulation, a neural network first received a simultaneous procedure, where the interstimulus interval (ISI) was 0 time-steps (ts). Output activations were near zero under this procedure. The network then received a forward-delay procedure where the ISI was 8 ts. Output activations increased to the near-maximum level faster than those of a control network that first received an explicitly unpaired procedure. Comparable results were obtained with rats that first received trials where a retractable lever was presented for 3s concurrently with access to water. Low-lever pressing was observed under this procedure. The rats then received trials where the lever was followed 15s after by water. Lever pressing appeared faster than a control group that received the 15-s ISI after an explicitly unpaired procedure. The model used in the simulation explains these results as connection-weight increments that promote little output activations in a simultaneous procedure, but facilitate acquisition in an optimal ISI.