Linking catabolism to cyclodextrin extractability: determination of the microbial availability of PAHs in soil

When assessing the potential of a contaminated site for bioremediation, it is desirable to know how much of the contaminant(s) is available for microbial degradation, thus allowing the likelihood of successful bioremediation to be predicted. The aims of this study were to investigate the degradation of PAHs in two soils by a catabolic inoculum and indigenous soil microflora and link this to the cyclodextrin extractable fraction in the presence of transformer oil (0.05, 0.01, or 0.005%). This study showed very little difference between indigenous and inoculum-derived degradation for phenanthrene in laboratory-aged soil, and strong relationships were also observed between both of the microbial degradative conditions and the amount of phenanthrene extracted by cyclodextrin. Furthermore, the indigenous degradation of PAHs in a field-contaminated soil showed significant linear correlations with the cyclodextrin extractable fraction, with gradients approximating to 1. There are several novel facets to this study. First, in aged, contaminated soils, indigenous microflora gave an equally sensitive determination of degradative availability as that measured by the catabolic inoculum. Second, this is the first time intrinsic biodegradation of PAHs has been predicted by the cyclodextrin extraction in laboratory-spiked and field-contaminated soils. The cyclodextrin extraction technique represents a powerful tool for predicting the extent of intrinsic and augmented microbial degradation and will be useful in the assessment of contaminated land prior to bioremediation.     

Long-term fate of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in an agricultural soil

Laboratory studies are useful for understanding the behavior of persistent organic pollutants (POPs) in soil, although such investigations do not always relate directly to field conditions. Outdoor lysimeter studies may be used to overcome this problem. This work aimed to investigate the behavior of two polycyclic aromatic hydrocarbons (PAHs) (fluoranthene and benzo[a]pyrene) and two polychlorinated biphenyls (PCBs; congeners 28 and 52) in soil, using lysimeters established in 1990 atthe Agrosphere Institute (Forschungszentrum Julich GmbH, Germany). The two PAHs were in one lysimeter, and the PCBs were in a second lysimeter. Afurther aim of the study was to determine soil half-lives for each of the contaminants. The overall decline in PAH concentrations was considerably greater than forthe PCBs over the 152 month study. The PCBs exhibited greater chemical extractability than the PAHs and were demonstrated to have migrated through the soil column to a greater extent than the PAHs. Loss of PCBs from surface soil was not considered to have been congener specific for the two PCB congeners in this study. The two PAHs varied in their extents of total loss and movement through the soil column. Soil half-lives were determined as 10.9 y for [12C]PCB 28, 11.2 yr for [12C]PCB 52, 2.7 yr for benzoqpyrene, and 32 d (phase 1) to 38 yr (phase 2) for fluoranthene. These are shown to disagree with some previous estimates of POP half-lives in soil, suggesting that previous studies underestimated persistence by 10-fold or more.     

A Cost-Based Availability Allocation Algorithm

This paper develops a cost-based procedure for allocating the availability parameters (repair times and failure rates) to the various components that make up a system. The allocation is handled as a cost minimization problem, subject to the constraint of meeting a system availability requirement. The problem is solved using Lagrange multipliers and an example is stated and solved. This technique is applicable in the early stages of system design to determine the detailed component availability specifications (repair times and failure rates) that will allow a system requirement to be met. Furthermore, the technique is useful in the latter stages of system design when initial specifications have fallen short of the required goal, and modifications and improvements are required. The technique points out the problem components and defines the amount of improvement necessary.     

The bispectrum of sampled data. II. Monte-Carlo simulations ofdetection and estimation of the sampling jitter

For pt.I see IEEE Trans. Acoust. Speech, Signal Process., vol.41, no.1, p.296-312 (1993). The effect of jitter in sampling on the spectrum and bispectrum of the sampled data has been considered previously. Methods of detecting the presence of jitter in a uniform sampling process and of estimating its variance based on a test statistic calculated from the bispectrum estimates have been proposed. The present authors demonstrate, by means of Monte-Carlo simulations, how these results can be applied in an actual case. For this purpose, samples taken from a stationary band-limited process in sampling times given by a random jitter process are generated by computer. The authors then apply the jitter detection and estimation methods that have been developed in previous work and study how their performance depends on signal duration and on jitter variance. They examine the actual simulation results concerning detection probability, estimation bias, and estimation variance in comparison with the theoretical results. This comparison indicates that the bispectrum is a domain where jitter detection and estimation with high performance can be achieved, provided that a signal with sufficiently long duration and high skewness is available     

Le trouble obsessionnel-compulsif et l'insight: Une revue critique de la littérature.

It is assumed that an individual suffers from obsessive-compulsive disorder (OCD) with poor insight when he or she does not recognize for most of the time that his or her obsessions/compulsions are unreasonable (American Psychiatric Association, 2000). In this critical review of research concerning insight in obsessions, overvalued ideas and delusions, we propose several factors that should be considered when evaluating insight. The instruments frequently used to evaluate insight in OCD patients are critically discussed. Often they assess insight principally in medical terms (e.g., the capacity to recognize that one's behaviour is the result of a mental disorder) without considering the cognitive dimensions. Other instruments designed specifically for OCD assess insight on the basis of the anticipated consequences of not executing one ritual but these instruments do not distinguish this from obsessional doubts. Measures of insight for OCD may need to consider that OCD has several independent components and conviction may vary according to level initial doubt as well to type of consequence. A multidimensional model that evaluates three cognitive dimensions of insight in OCD patients is presented (the Inference Based Approach). This cognitive model establishes a clear distinction between the obsessional doubts, the anticipated consequences and the degree of conviction in the need to perform the ritual. Further recommendations are presented to evaluate insight in OCD patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Robust parameter estimation of a deterministic signal in impulsivenoise

This paper presents a robust class of estimators for the parameters of a deterministic signal in impulsive noise. The proposed technique has the structure of the maximum likelihood estimator (MLE) but has an extra degree of freedom: the choice of a nonlinear function (which is different from the score function suggested by the MLE) that can be adjusted to improve robustness. The effect of this nonlinear function is studied analytically via an asymptotic performance analysis. We investigate the covariance of the estimates and the loss of efficiency induced by nonoptimal choices of the nonlinear function, giving special attention to the case of α-stable noise. Finally, we apply the theoretical results to the problem of estimating the parameters of a sinusoidal signal in impulsive noise     

What contributed to the major decline in per capita cigarette consumption during California's comprehensive tobacco control programme?

Objectives

California experienced a notable decline in per capita cigarette consumption during its comprehensive tobacco control programme. This study examines what proportion of the decline occurred from: (1) fewer ever smokers in the population, (2) more ever smokers quitting, and (3) current smokers smoking less.

Design, subjects

Per capita cigarette consumption computed from cigarette sales and from adult respondents to the large, cross‐sectional, population‐based California Tobacco Surveys of 1990 (n  =  24 296), 1996 (n  =  18 616) and 2002 (n  =  20 525) were examined for similar trends.

Main outcome measure

Changes (period 1: 1990–1996; period 2: 1996–2002) in per capita cigarette consumption from self‐reported survey data were partitioned for the entire population and for demographic subgroups into the three components mentioned above.

Results

In periods 1 and 2, most of the decline in per capita cigarette consumption for the population as a whole was from current smokers smoking less followed by a reduction in ever smokers. The decline from smokers smoking less was particularly evident among young adults (18–29 years) in period 1. While the portion of the decline due to quitting in the entire population in period 1 was negligible, in period 2 it accounted for 22% of the total per capita decline. The decline from quitting in period 2 was mostly observed among women.

Conclusions

Rather than near‐term benefits from smokers quitting, population health benefits from reduced per capita cigarette consumption will likely occur over the longer term from fewer people becoming ever smokers, and more less‐addicted smokers eventually quitting successfully.