Mobilisation, alteration, and redistribution of monosulfidic sediments in inland river systems.

The accumulation of monosulfidic sediments in inland waterways is emerging as a major environmental issue. Mobilisation and suspension of monosulfidic sediments can result in deoxygenation, acidification of the water column and mobilisation of trace metals. The controls on monosulfidic sediment mobilisation and the critical thresholds for its scour and entrainment have not been established. This study examines the effect of a minor flood event (average return interval of 5 years) on sulfidic sediment scour in the Wakool River in southern NSW, Australia. Five profiles were sampled within a small (~300 m) reach before and after a minor flood event to determine the degree of sediment scour and transport. The results indicate substantial scour of both monosulfidic sediments and underlying bed sediments (approximately 2100 m(3)). Changes in the sediment geochemistry suggest large concentrations of monosulfidic sediments had been suspended in the water column, partially-oxidised and redeposited. This is supported by (210)Pb results from one of the profiles. These results suggest that these monosulfidic sediments can move as bed load during minor flood events.

Monosulfidic black ooze accumulations in sediments of the Geographe Bay area, Western Australia.

Mobilisation of sedimentary monosulfidic black ooze (MBO) may result in rapid deoxygenation and acidification of surface waters, and release of potentially toxic metals. This study examines the extent and nature of MBO accumulation in the Geographe Bay area, Western Australia. MBO accumulations were found to be widespread in benthic sediments of the Geographe Bay area with acid-volatile sulfide (AVS) contents as high as 320 µmol g(-1). The MBO materials often had unusually high dissolved sulfide (S(-II)) concentrations in their pore-waters (up to 610 mg L(-1)) and elevated elemental sulfur (S(0)) contents (up to 51 µmol g(-1)). Dissolved S(-II) is able to accumulate due to limited iron availability and S(0) is largely its partial oxidation product. The availability of organic carbon and Fe limited MBO accumulation at many sites. A comparison of AVS and simultaneously extracted metal (SEM) concentrations has shown that metals are likely to be bound in sulfide complexes.

Iron-monosulfide oxidation in natural sediments: resolving microbially mediated S transformations using XANES, electron microscopy, and selective extractions.

Iron-monosulfide oxidation and associated S transformations in a natural sediment were examined by combining selective extractions, electron microscopy and S K-edge X-ray absorption near-edge structure (XANES) spectroscopy, The sediment examined in this study was collected from a waterway receiving acid-sulfate soil drainage. It contained a high acid-volatile sulfide content (1031 micromol g(-1)), reflecting an abundance of iron-monosulfide. The iron-monosulfide speciation in the initial sediment sample was dominated by nanocrystalline mackinawite (tetragonal FeS). At near-neutral pH and an 02 partial pressure of approximately 0.2 atm, the mackinawite was found to oxidize rapidly, with a half-time of 29 +/- 2 min. This oxidation rate did not differ significantly (P < 0.05) between abiotic versus biotic conditions, demonstrating that oxidation of nanocrystalline mackinawite was not microbially mediated. The extraction results suggested that elemental S (S8(0)) was a key intermediate S oxidation product Transmission electron microscopy showed the S8(0) to be amorphous nanoglobules, 100-200 nm in diameter. The quantitative importance of S8(0) was confirmed by linear combination XANES spectroscopy, after accounting for the inherent effect of the nanoscale S8(0) particle-size on the corresponding XANES spectrum. Both the selective extraction and XANES data showed that oxidation of S8(0) to SO4(2-) was mediated by microbial activity. In addition to directly revealing important S transformations, the XANES results support the accuracy of the selective extraction scheme employed here.

Blood lactate concentrations in anesthetized dogs with intracranial disease.

BACKGROUND: The importance of blood lactate concentrations in dogs with intracranial disease has not been established, despite frequently observed hyperlactatemia in dogs undergoing general anesthesia for advanced imaging, surgery, or both. HYPOTHESIS: Blood lactate concentrations are elevated in anesthetized dogs with intracranial disease, compared with dogs with intervertebral disc disease (IVDD). ANIMALS: Eighty-five hospitalized dogs undergoing advanced imaging, surgery, or both for primary neurologic disease; 30 with intracranial disease; 55 with IVDD. METHODS: Retrospective study. Age, breed, neurologic diagnosis, time from anesthesia induction to measurement of blood lactate, blood lactate concentration under anesthesia, and concurrently measured heart rate, mean arterial pressure, PCV, arterial hemoglobin oxygen saturation, and arterial partial pressure of oxygen were included in a multivariable linear regression analysis. RESULTS: Dogs with meningioma (adjusted mean lactate 2.99 mmol/L, 95% CL 2.21-4.05, P < 0.0001) and hydrocephalus (adjusted mean lactate 1.5 mmol/L, 95% CL 0.99-2.27, P= 0.003) had higher blood lactate concentrations compared with dogs with IVDD (adjusted mean lactate 0.79 mmol/L, 95% CL 0.6-1.04). Only dogs with meningioma had clinically important hyperlactatemia (>2.5 mmol/L). CONCLUSIONS: Prospective studies are warranted to determine the degree and clinical importance of high blood lactate concentrations in dogs with intracranial disease.

Biotechnological potential within the genus Burkholderia.

Many species within the genus Burkholderia possess significant biotechnological potential in bioremediation and biological control. Here we provide a description of the Burkholderia strains being investigated for their ability to degrade major xenobiotic pollutants and update information on their taxonomy, metabolic capacity and genomes.

Schematic drawings of facial expressions for emotion recognition and interpretation by preschool-aged children.

Schematic drawings of facial expressions were evaluated as a possible assessment tool for research on emotion recognition and interpretation involving young children. A subset of Ekman and Friesen's (1976) Pictures of Facial Affect was used as the standard for comparison. Preschool children (N = 138) were shown drawing and photographs in two context conditions for six emotions (anger, disgust, fear, happiness, sadness, and surprise). The overall correlation between accuracy for the photographs and drawings was .677. A significant difference was found for the stimulus condition (photographs vs. drawings) but not for the administration condition (label-based vs. context-based). Children were significantly more accurate in interpreting drawings than photographs and tended to be more accurate in identifying facial expressions in the label-based administration condition for both photographs and drawings than in the context-based administration condition.

Facial interpretation and component consistency.

The issue of consistency, without regard to accuracy, of the facial component of focus (upper/eyebrows, middle/eyes, lower/nose and mouth) when interpreting facial expressions of emotion was examined. Eighty girls (average age, 7 years) chose, from an array of schematic faces, which face best represented various emotional scenarios (anger, disgust, fear, happiness, sadness, and surprise). The findings indicate that these children were remarkably consistent in facial area of focus. Across six trials for each emotion, children focused on the mouth (lower component) for happiness, sadness, surprise, and disgust, and on the eyebrows (the upper component) for anger and fear.

Interpretation of facial expressions of emotion: the influence of eyebrows.

The contribution of the eyebrow component (eyebrow density and eyebrow position) in interpretation of facial displays of emotions was explored. In Study 1, college students (N = 60) and children (N = 60), ages 6-9 years, listened to vignettes consisting of one or two sentences and selected the facial expression that best matched the vignette. A main effect for eyebrow density as well as interactions for Density x Age and Density x Emotion were found. Also, a main effect for eyebrow position and interactions for Position x Age, Position x Emotion, and Position x Age x Emotion were significant. Study 2 was conducted to better understand whether findings regarding eyebrow position were a function of mistaking the intended emotion portrayed in the vignettes. Using a within-subject design, responses from 60 children, age 6-9 years, were compared for trials when the emotion was designated and when emotion was not designated. A main effect for designation of emotion was not found; however, an interaction effect for Designation x Emotion was significant.

Production of facial expressions of emotion in preschool children.

138 preschool children created faces with manipulable facial components to represent expressed emotions. Proportions selecting appropriate components varied with emotions so the task was perhaps more cognitively demanding than Ekman and Friesen's facial recognition task.

Predictors of behavior problems in three-year-old sons of alcoholics: early evidence for the onset of risk.

We investigated risk factors in a population-based sample of alcoholic (father) and comparison families with 3-year-old sons. Alcoholic and comparison parents did not differ in socioeconomic status (SES), education, years married, family size, or cognitive functioning. Antisocial behavior and depression were significantly greater in alcoholic parents. High risk children were more impulsive than comparison children, but there were no differences in developmental age, IQ, or behavior problems. A higher percentage of high-risk children were rated in the extreme clinical range for behavior problems than were comparison children. For alcoholic families, mothers' ratings of their children's total behavior problems, externalizing behavior problems, and internalizing behavior problems were predicted by mothers' lifetime alcohol problems, current depression, and family SES. Father variables failed to predict children's behavior problems. Maternal variables were stronger predictors of their 3-year-old sons' problem behaviors than were paternal variables.

Laparoscopic-guided biopsy for diagnosis of hepatic candidiasis.

Histopathological evaluation of infected tissue is critical in the diagnosis of hepatic candidiasis since cultures are unreliable. Percutaneous techniques are inaccurate because lesions often are small and multifocal, and open biopsy is not always well-tolerated in acutely ill patients. The authors investigated the feasibility of laparoscopically guided biopsy in patients suspected of having hepatic candidiasis. Preliminary results suggest that laparoscopically guided biopsy is highly accurate and less invasive than open biopsy.

Cognition and affect in evaluations of stereotyped group members.

The contribution of cognition and affect to evaluations of stereotyped group members was examined. Subjects were American male undergraduates who evaluated a male homosexual or a male heterosexual applicant to a program in elementary education or fine arts. Cognitive measures used to predict evaluations were the discrepancies between stereotype components for the social category and stereotype components for the occupation; affective measures were four dimensions of mood-affect. Results indicated that negative affect predicted evaluations of homosexuals but not heterosexuals. Homosexuals were evaluated less favorably than heterosexuals for both occupations, despite the fact that homosexuals were perceived as less discrepant from occupational members than heterosexuals.