Measuring the Flow of Time: The Works of James A. Ford, 1935-1941: James A. Ford and the Growth of Americanist Archaeology

Measuring the Flow of Time: The Works of James A. Ford, 1935-1941. Michael J. O'Brien and R. Lee Lyman. Tuscaloosa: University of Alabama Press, 1999. 582 pp.
James A. Ford and the Growth of Americanist Archaeology. Michael J. O'Brien and R. Lee Lyman. Columbia: University of Missouri Press, 1998.377 pp.     

A Deterministic Method for Deriving Site-Specific Human Health Assessment Criteria for Contaminants in Soil

A method for deriving Site-Specific Assessment Criteria (SSAC) for use when considering risk to human health from chronic exposure to heavy metals (except lead), metalloids, and organic substances in soil, with application to the United Kingdom (UK), is described. The SSAC represents the soil concentration above which an unacceptable risk to human health may be indicated.

The method considers the UK standard land uses (residential with and without plant uptake, allotment gardens, and commercial/industrial) by applying the default exposure factors and algorithms provided. Non-standard land uses can be also considered. Site-specific determinations of contaminant bioaccessibility or of plant-to-soil concentration factors may be used if available.

The method adopts the risk-based source-pathway-receptor pollutant linkage framework and a deterministic methodology. Exposure pathways considered are direct ingestion of soil and dust, consumption of home grown or allotment vegetables, ingestion of soil attached to such vegetables, inhalation of soil vapors outdoors and inhalation of soil vapors indoors. A test for the significance of the dermal pathway is also included.

It is not intended that the method be used to generate or replace UK Soil Guideline Values, because this can only be done by the appropriate authoritative bodies within the UK (Department of the Environment, Food and Rural Affairs and the Environment Agency).     

胰蛋白酶活性的定量测定方法

对甲苯磺酰基精氨酸甲酯(TAME)是胰蛋白酶的专一性底物. TAME经胰蛋白酶水解释放出的对甲苯磺酰基精氨酸与活性测定混合物中的NaOH反应, 导致溶液pH值的下降. 以酚红为指示剂, 通过测定555nm处光吸收值的降低可以监测pH的变化. 在0.001～0.3μg的范围内, 胰蛋白酶含量与555nm处光吸收值的降低呈线性关系.     

A Physical Method for Deriving the Electrostatic Interaction between Rod-Like Polyions at All Mutual Angles

The screened Coulomb interaction between polyelectrolyte cylinders immersed in an ionic bath is examined. The electrostatic force and torque acting between a pair of unlike rods is formulated for all separations in which the electrostatic potential on some dividing surface between rods can be written as a linear superposition of isolated cylinder potentials. (The surface potential on the rods themselves may be much higher than that permitted by a superposition approximation.) The mutual energy in the case of skewed rods is found to be exponential in separation and proportional to 1/sin θ where θ is the twist angle of one rod relative to the other. Rods with similar charge repel each other with a torque acting to make the rods perpendicular while rods of opposite charge attract with the parallel arrangement preferred.     

A Bayesian Method for Deriving Species-Sensitivity Distributions: Selecting the Best-Fit Tolerance Distributions of Taxonomic Groups

We present a Bayesian method for deriving species-sensitivity distributions (SSDs). We employed four Bayesian statistical models to consider differences in tolerance to toxic substances among different taxonomic groups. We first used a Malkov chain Monte Carlo simulation based on these models to estimate the SSD parameters. We then computed deviance information criterion values of the models and compared them in order to select the model with the best predictive ability. We applied this approach to seven substances (zinc, lead, hexavalent chromium, cadmium, nickel, short-chain chloride paraffin, and chloroform) as case examples, and then compared the derived SSDs from the selected models and a model that assumed no tolerance differences among taxonomic groups. We discuss the advantages and limitations of our approach on the basis of our results.     

A Quantitative Assessment Method for Ascaris Eggs on Hands

The importance of hands in the transmission of soil transmitted helminths, especially Ascaris and Trichuris infections, is under-researched. This is partly because of the absence of a reliable method to quantify the number of eggs on hands. Therefore, the aim of this study was to develop a method to assess the number of Ascaris eggs on hands and determine the egg recovery rate of the method. Under laboratory conditions, hands were seeded with a known number of Ascaris eggs, air dried and washed in a plastic bag retaining the washing water, in order to determine recovery rates of eggs for four different detergents (cationic [benzethonium chloride 0.1% and cetylpyridinium chloride CPC 0.1%], anionic [7X 1% - quadrafos, glycol ether, and dioctyl sulfoccinate sodium salt] and non-ionic [Tween80 0.1% -polyethylene glycol sorbitan monooleate]) and two egg detection methods (McMaster technique and FLOTAC). A modified concentration McMaster technique showed the highest egg recovery rate from bags. Two of the four diluted detergents (benzethonium chloride 0.1% and 7X 1%) also showed a higher egg recovery rate and were then compared with de-ionized water for recovery of helminth eggs from hands. The highest recovery rate (95.6%) was achieved with a hand rinse performed with 7X 1%. Washing hands with de-ionized water resulted in an egg recovery rate of 82.7%. This washing method performed with a low concentration of detergent offers potential for quantitative investigation of contamination of hands with Ascaris eggs and of their role in human infection. Follow-up studies are needed that validate the hand washing method under field conditions, e.g. including people of different age, lower levels of contamination and various levels of hand cleanliness.     

A Novel Generalized Ridge Regression Method for Quantitative Genetics

As the molecular marker density grows, there is a strong need in both genome-wide association studies and genomic selection to fit models with a large number of parameters. Here we present a computationally efficient generalized ridge regression (RR) algorithm for situations in which the number of parameters largely exceeds the number of observations. The computationally demanding parts of the method depend mainly on the number of observations and not the number of parameters. The algorithm was implemented in the R package bigRR based on the previously developed package hglm. Using such an approach, a heteroscedastic effects model (HEM) was also developed, implemented, and tested. The efficiency for different data sizes were evaluated via simulation. The method was tested for a bacteria-hypersensitive trait in a publicly available Arabidopsis data set including 84 inbred lines and 216,130 SNPs. The computation of all the SNP effects required <10 sec using a single 2.7-GHz core. The advantage in run time makes permutation test feasible for such a whole-genome model, so that a genome-wide significance threshold can be obtained. HEM was found to be more robust than ordinary RR (a.k.a. SNP-best linear unbiased prediction) in terms of QTL mapping, because SNP-specific shrinkage was applied instead of a common shrinkage. The proposed algorithm was also assessed for genomic evaluation and was shown to give better predictions than ordinary RR.     

A New Quantitative Method for Analysing Unreplicated Factorial Designs

The paper proposes a new method for the analysis of unreplicated factorial designs. The new method does not use an estimate of the error variance and has the potential to identify up to m – 1 active contrasts, where m is the number of contrasts in the study. It can be shown that the proposed test statistic, called MaxU_r, is a function of the generalized likelihood ratio test statistic under normality, which was also used by Al‐Shiha and Yang (1999). Our strategy to identify active contrasts using MaxU_r, however, is different from the multistage procedure proposed by Al‐Shiha and Yang (1999). Additionally, our simulation study seems to show that the new method is superior to Al‐Shiha and Yang's (1999) method. In order to test the performance of the new method, we did an extensive simulation study based on 10,000 samples to compare the new method with 12 other methods from the literature. To reasonably compare these methods, some of the 12 existing methods had to be slightly modified, such that the probability of falsely rejecting the global null hypothesis of no active factors was 0.05 for all methods. Two types of evaluation standard were used, the empirical power and the loss of decision. The results show that the new method performs very well, especially for large number of active contrasts (say more than 3 out of 15). A second purpose of the simulation study was to compare the performance of two well‐known estimates for the variance. One is the PSE introduced by Lenth (1989), the other the ASE introduced by Dong (1993). The simulation study confirmed the approximations of Kunert (1997) which indicate that Dong's (1993) estimate should perform better for small numbers of active factors. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)