Internal loading of phosphorus in a sedimentation pond of a treatment wetland: effect of a phytoplankton crash

Sedimentation ponds are widely believed to act as a primary removal process for phosphorus (P) in nutrient treatment wetlands. High frequency in-situ P, ammonium (NH₄⁺) and dissolved oxygen measurements, alongside occasional water quality measurements, assessed changes in nutrient concentrations and productivity in the sedimentation pond of a treatment wetland between March and June. Diffusive equilibrium in thin films (DET) probes were used to measure in-situ nutrient and chemistry pore-water profiles. Diffusive fluxes across the sediment-water interface were calculated from the pore-water profiles, and dissolved oxygen was used to calculate rates of primary productivity and respiration. The sedimentation pond was a net sink for total P (TP), soluble reactive P (SRP) and NH₄⁺ in March, but became subject to a net internal loading of TP, SRP and NH₄⁺ in May, with SRP concentrations increasing by up to 41 μM (1300 μl^− 1). Reductions in chlorophyll a and dissolved oxygen concentrations also occurred at this time. The sediment changed from a small net sink of SRP in March (average diffusive flux: − 8.2 μmol m^− 2 day^− 1) to a net source of SRP in June (average diffusive flux: + 1324 μmol m^− 2 day^− 1). A diurnal pattern in water column P concentrations, with maxima in the early hours of the morning, and minima in the afternoon, occurred during May. The diurnal pattern and release of SRP from the sediment were attributed to microbial degradation of diatom biomass, causing reduction of the dissolved oxygen concentration and leading to redox-dependent release of P from the sediment. In June, 2.7 mol-P day^− 1 were removed by photosynthesis and 23 mol-P day^− 1 were supplied by respiration in the lake volume. SRP was also released through microbial respiration within the water column, including the decomposition of algal matter. It is imperative that consideration to internal recycling is given when maintaining sedimentation ponds, and before the installation of new ponds designed to treat nutrient waste.     

The Benefits and Costs of Residential Mobility Programmes for the Poor

By enabling low-income families to move from high- to low-poverty neighbourhoods, tenant-based rental subsidies for poor families have the potential to reduce the degree of economic segregation in the US. This paper provides a framework for identifying the benefits and costs of such housing mobility programmes, and reviews the available empirical evidence on the net effects of quasi- or formal randomised housing mobility experiments. The best available evidence suggests that families in public housing who receive rental subsidies to move from high- to lower-poverty areas may experience reductions in welfare receipt and improvements in health status. Such moves may also improve schooling outcomes for children and reduce their problem behaviours. The benefits to society from these changes are substantial when measured in dollar terms. Unfortunately, very little is currently known about the effects of housing-mobility efforts on non-participants.     

Preschoolers can attribute second-order beliefs.

The ability to attribute 2nd-order mental states was investigated in 87 children drawn from preschool, kindergarten, 1st-grade, and 2nd-grade classes. Ss received 4 stories, 2 standard and 2 new, designed to test their understanding of 2nd-order mental states. The standard stories were modified versions of J. Perner and H. Wimmer's (see record 1985-25133-001) 2nd-order task. The new stories were made significantly simpler by reducing the number of characters, episodes, and scenes and by including a deception context. The main findings were that performance on the new stories was significantly better than on the standard stories and that nearly half of the preschoolers and almost all of the kindergartners were able to attribute 2nd-order beliefs. These findings contrast with those of earlier research (e.g., G. J. Hogrefe et al; see PA, Vol 73:26831 and Perner and Wimmer). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reliability of self-reported HIV risk behaviors of drug users.

In AIDS research, relatively little attention has been paid to reliability of self-report of drug users. The authors examined the test-retest reliability of the Risk Behavior Assessment (NIDA, 1991) questionnaire. This structured-interview questionnaire was administered twice to 196 drug users in 5 cities over a 48-hr period. Findings indicated that respondents consistently self-report drug use, injection practices, and sexual behaviors; discrepancies do not appear to reflect systematic decreases or increases in self-report; unreliability is associated with poorly worded questions and respondent characteristics; and discrepant reports warrant attention in analysis and interpretation of data. Measurement error has implications for estimating risks, understanding relationships between behavior and HIV transmission, and interpreting change after interventions. Items with low reliability have been revised, and further reliability studies are examining whether revisions have led to improved reliability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive/attentional distraction in the control of conditioned nausea in pediatric cancer patients receiving chemotherapy.

Two studies were conducted to investigate the use of cognitive/attentional distraction (via commercially available video games) to control conditioned nausea in pediatric cancer patients receiving chemotherapy. The first study compared the nausea severity in children who played video games during chemotherapy-related procedures with that of control-group children who did not play video games. The second study used a combined ABAB withdrawal and repeated measures analysis of variance design that incorporated baseline and intervention assessments within a single session. In both studies, video game-playing resulted in significantly less nausea. The introduction and withdrawal of the opportunity to play video games produced significant changes (reduction and exacerbation, respectively) in nausea. Although video games also reduced self-reported anxiety, the effects were weaker than those for nausea. Pulse rate and systolic/diastolic blood pressure were not consistently affected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age related differences in learning to use a text-editing system

The increased use of computer technology in most occupations means that many middle-aged and older workers who lack computer experience will need to acquire skills to interact with this technology. This study examined age-group differences in learning to use a text-editing system. One hundred and thirty-five females ranging in age from 25 to 70 participated in the study. They received training under one of three training conditions: instructor-based, online or manual-based. Age differences were assessed by comparing performance on criterion tasks. Results indicated significant differences among the groups in learning success, younger learners being the most successful. There were no significant age by training interactions. The findings indicate a need to develop more effective training strategies to teach older learners to use computer technologies. They also indicate the need for changes in system design because computer applications are difficult for novice users to learn.     

Category-specific semantic deficits: The role of familiarity and property type reexamined.

Category-specific deficits for living things have been explained variously as an artifact due to differences in the familiarity of concepts in different categories (E. Funnell & J. Sheridan, 1992) or as the result of an underlying impairment to sensory knowledge (E. K. Warrington & T. Shallice, 1984). Efforts to test these hypotheses empirically have been hindered by the shortcomings of currently available stimulus materials. A new set of stimuli are described that the authors developed to overcome the limitations of existing sets. The set consists of color photographs, matched across categories for familiarity and visual complexity. This set was used to test the semantic knowledge of a classic patient, J.B.R. (E. K. Warrington & T. Shallice, 1984). The results suggest that J.B.R.'s deficit for living things cannot be explained in terms of familiarity effects and that the most severely affected categories are those whose identification is most dependent on sensory information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit Spatial Contextual Learning in Healthy Aging.

Three experiments investigated the aging of implicit spatial and spatiotemporal context learning in 2 tasks. In contextual cuing, people learn to use repeated spatial configurations to facilitate search for a target, whereas in higher order serial learning, they learn to use subtle sequence regularities to respond more quickly and accurately to a series of events. Results reveal a dissociation; overall contextual cuing is spared in healthy aging, whereas higher order sequence learning is impaired in the same individuals. This finding suggests that these 2 forms of implicit learning rely on different neural substrates that age differently; the results are also consistent with recent evidence that fronto-striatal circuits are particularly susceptible to decline in health aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Counseling victims of sexual harassment.

Describes therapeutic experiences with 10 sexual harassment victims in individual therapy and 7 sexual harassment victims in group therapy and compares them with data from sexual employment surveys and with other crime populations. Findings reveal that victims progressed through stages of feelings including confusion/self-blame, fear/anxiety, depression/anger, and disillusionment. The stress of sexual harassment was also affected by a history of prior victimization and by the victim's involvement in a formal complaint process related to the harassment. The group setting was found to be more effective than individual treatment for coping with the specific effects of sexual harassment, and Ss in group therapy used the group to understand their experience, sort through legal and employment decisions, learn new coping skills, and develop support for each other. Victims of sexual harassment differed from victims of crime: The primary effects of the harassment were on economic and career well-being; the secondary effects were on private relationships and physical well-being. The reverse is true for victims of crime. Therapeutic complications arising from the therapist's involvement in court proceedings and organizational remedies are also described. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)