Analysis of octyl- and nonylphenol and their ethoxylates in water and sediments by liquid chromatography/tandem mass spectrometry

The ubiquitous presence of alkylphenol ethoxylates in the environment as well as concern for endocrine disruption effects in biota caused by their degradation products (such as octyl- and nonylphenol) has raised interest in the environmental fate of these compounds. As part of an effort to model their behavior in a subestuary of the Chesapeake Bay, a quantitative method for the analysis of octyl- and nonylphenol, and their ethoxylates (1-5) in water and sediment was developed. Extraction procedures are based on solid-phase extraction techniques. Identification and quantitation of the analytes is done by liquid chromatography coupled to tandem mass spectrometry. Instrument detection limits for the compounds ranged from 0.1 to 9 pg injected on column, which allowed method detection limits of 0.04-3 ng/L in water and 0.2-13 ng/g of dry weight in sediment. The method was used to analyze water and sediment from the Back River, MD, where concentrations for the individual compounds ranged from <8 to 200 ng/L in water and <9 to 6700 ng/g of dry weight in sediment. Additionally, structural information obtained in the mass spectrometer is presented that supports previous observations that nonylphenol and its ethoxylates are composed mainly of isomers with a tertiary alpha-carbon.     

Cranes for Building Construction Projects

Cranes have come to symbolize building construction itself. They perform indispensable services in moving materials and components vertically and horizontally. Used since antiquity, their history is interrelated with the development of new power sources that replaced man and mule, first steam and later internal combustion, diesel, and electric engines. Mobile cranes can be rapidly deployed to lift heavy loads. New models with telescoping booms and all-terrain travel capability, compact urban machines, and even hybrids with tower cranes are beginning to replace the familiar lattice boom truck cranes. Mobile cranes have dominated the North American market, but a cultural change appears to be taking place toward tower cranes for building projects. Tower cranes, common in Europe for decades, are globally gaining in popularity with surging real estate developments. Ideal for dense urban environments and coming with a small footprint, they are available in a growing diversity of sizes and configurations. Sophisticated electronic controls and operator assistance devices are enhancing their safe and productive operation. While cranes occupy a central role on midrise and high-rise building projects, they operate in conjunction with other types of supporting equipment that are an essential part of the overall equipment array on today’s industrialized construction sites.     

Impact of Multimedia-Based Instruction on Learning and Retention

Studies measuring and evaluating the impact of the same multimedia-based education on learners in universities and high schools are a relatively new phenomenon. This study provides a summary of the results from research on the effects of multimedia-based safety education conducted by the M. E. Rinker Sr. School of Building Construction at the University of Florida. The findings are presented along with their related statistical test results. The findings indicate multimedia-based, self-paced learning offers very distinct advantages over traditional, instructor-led classroom learning. Overall, both the high-school and university student groups involved in the study exhibited superior retention rates when learning from the multimedia-based materials. Higher scoring students in the classroom showed little difference in either media, while students who tended to score at the low end of the grading scale uniformly scored higher on multimedia-based materials. The reduced variation in student performance based on test scores in the CD-ROM instruction indicates the positive effects of multimedia-based instruction.     

Schedule of Events

In this study, the effect of the user choice on social responses to computer-synthesized speech is investigated. Three previous findings about social responses to computer-synthesized speech (i.e., social identification, proximate source orientation, and similarity attraction) were tested using the choice paradigm. Social identification and proximate source orientation effects were found even when users had chosen a computer voice at their discretion. In addition, the primacy effect in the user choice prevailed: Participants were more likely to select whatever voice that they heard first between two options. The similarity attraction effect, however, was negated by the cognitive dissonance effect after user choices. The robustness of social responses, its implications for human–computer interaction, and the importance of the user choice in voice-interface designs are discussed.     

The effect of drying on black tea quality

Drying is an important part of tea manufacture, where enzyme reactions in earlier phases are terminated by heat and moisture loss, and new compounds are produced by the action of heat. This work is an attempt to quantify the temperatures required to produce the desired changes without damage through exposure to excess heat. Experiments were carried out giving already‐dried tea further heat exposure, drying tea from wet dhool in a thin layer, and drying a larger sample in a batch fluidized bed dryer. Temperatures in the range of 60–140 °C were used. Effects were monitored by commercial tasters, thin layer chromatography, reverse phase HPLC and size exclusion HPLC. Exposure to at least 80 °C was found to be necessary for quality development. For periods of less than 1 min, tea particle temperatures of up to 120 °C may be tolerated, but, in general, temperatures of 110 °C and above may be considered deleterious. Inlet air temperatures may be in excess of these values, but only while drying rates are high. The stewing phenomenon, cited by several authors, could not be found when drying times of less than 15 min were used. © 2001 Society of Chemical Industry     

The mean squared error of Geweke and Porter-Hudak's estimator of the memory parameter of a long-memory time series

We establish some asymptotic properties of a log-periodogram regression estimator for the memory parameter of a long-memory time series. We consider the estimator originally proposed by Geweke and Porter-Hudak (The estimation and application of long memory time series models. Journal of Time Ser. Anal. 4 (1983), 221–37). In particular, we do not omit any of the low frequency periodogram ordinates from the regression. We derive expressions for the estimator's asymptotic bias, variance and mean squared error as functions of the number of periodogram ordinates, m , used in the regression. Consistency of the estimator is obtained as long as m ←∞ and n ←∞ with ( m log m )/ n ← 0, where n is the sample size. Under these and the additional conditions assumed in this paper, the optimal m , minimizing the mean squared error, is of order O( n ^4/5). We also establish the asymptotic normality of the estimator. In a simulation study, we assess the accuracy of our asymptotic theory on mean squared error for finite sample sizes. One finding is that the choice m = n ^1/2, originally suggested by Geweke and Porter-Hudak (1983), can lead to performance which is markedly inferior to that of the optimal choice, even in reasonably small samples.     

Plug-in Selection of the Number of Frequencies in Regression Estimates of the Memory Parameter of a Long-memory Time Series

We consider the problem of selecting the number of frequencies, m , in a log-periodogram regression estimator of the memory parameter d of a Gaussian long-memory time series. It is known that under certain conditions the optimal m , minimizing the mean squared error of the corresponding estimator of d , is given by m ^(opt)= Cn ^4/5, where n is the sample size and C is a constant. In practice, C would be unknown since it depends on the properties of the spectral density near zero frequency. In this paper, we propose an estimator of C based again on a log-periodogram regression and derive its consistency. We also derive an asymptotically valid confidence interval for d when the number of frequencies used in the regression is deterministic and proportional to n ^4/5. In this case, squared bias cannot be neglected since it is of the same order as the variance. In a Monte Carlo study, we examine the performance of the plug-in estimator of d , in which m is obtained by using the estimator of C in the formula for m ^(opt) above. We also study the performance of a bias-corrected version of the plug-in estimator of d . Comparisons with the choice m = n ^1/2 frequencies, as originally suggested by Geweke and Porter-Hudak (The estimation and application of long memory time series models. Journal of Time Ser. Anal. 4 (1983), 221–37), are provided.     

Autobiographies of mental health clients: Psychologists' uses and recommendations.

More than 80% of practicing psychologists recommend self-help books to their psychotherapy clients, but only 33% recommend autobiographies written by mental health patients. In this study, 362 psychologists (38% response) provided clinical information and evaluative ratings on such published autobiographical accounts. The effect of reading autobiographies during treatment was typically considered "somewhat helpful." The titles and evaluative ratings of 40 leading autobiographies are provided as a resource for the practitioner; the most valued were An Unquiet Mind, Nobody Nowhere, Darkness Visible, Out of the Depths, and Girl Interrupted. The clinical advantages of recommending published autobiographies to clients are reviewed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CROSS-VALIDATORY CHOICE OF A SPECTRUM ESTIMATE AND ITS CONNECTIONS WITH AIC

Abstract. This paper concerns the use of a generalized version of the cross-validated log likelihood criterion (CVLL) for selecting a spectrum estimator from an arbitrary class of candidate estimators. It is shown that CVLL is asymptotically equivalent to the expected Kullback-Leibler information of the candidate estimator. The Akaike information criterion (AIC) is also asymptotically equivalent to Kullback-Leibler information, but the applicability of AIC is limited to parametric estimators. Thus CVLL can be viewed as a cross-validatory generalization of AIC. Monte Carlo results show that CVLL is able to provide an effective choice from a class of candidates which simultaneously includes autoregressive and classical smoothed periodogram estimators. To save computation time, CVLL can be evaluated only for the classical estimators while the computationally more efficient AIC is evaluated for the parametric estimators. The criterion values are all directly comparable in this case. As an additional computation-saving device, a non-cross-validatory version of CVLL for classical estimators is proposed and studied.