Encrusting agglutinated foraminifera on indurated sediment at a hydrothermal venting area on the Juan de Fuca Ridge, northeast Pacific Ocean

Indurated sediment from the apron and basal areas of hydrothermal mounds in Middle Valley, on the Juan de Fuca Ridge, northeastern Pacific Ocean, is the site of attachment for a variety of encrusting agglutinated foraminifera. Hydrothermal venting in Middle Valley has created a unique environment which is characterized by elevated temperatures of substrate and bottom water, low pH values, and consolidated substrate. Foraminifera avoid areas in direct contact with the extremely high temperatures of hydrothermal vent fluids, but encrust the surrounding indurated sediment. Species diversity is low and population density varies on a small scale. One new genus, Ropostrum, with its type species R. amuleturn, is described from this locality. The substrate bears other micro-organisms of unknown affinity which are illustrated here. A comparison with other deep-sea consolidated substrates shows that encrusting agglutinated foraminifera prefer Fe-and Mn-rich surfaces

Benthic foraminiferal distribution at Middle Valley, Juan de Fuca Ridge, a northeast Pacific hydrothermal venting site

Fourteen benthic foraminiferal bearing surface samples collected from the Area of Active Venting (AAV) in Middle Valley at a depth of 2430 m at the northern end of Juan de Fuca Ridge, northeast Pacific Ocean, yielded 156 identifiable taxa. Sample sites were selected near active or recently active vents, where temperatures up to 274 °C have been measured. The sea floor beyond hydrothermal mounds is characterized by unaltered soft hemipelagic mud and is dominated by a calcareous foraminiferal assemblage which includes numerous allochthonous species derived from the shelf via turbidite flows into the valley. Within the AAV, agglutinated foraminifera dominate with proximity to hydrothermal vent activity. Species of the family Hormosinidae, subfamily Reophacinae, dominate in the hydrothermal habitat because of their success at colonization. Attached agglutinated foraminifera densely colonize the indurated sediment in close proximity to vent sites. However, like the macrofauna observed near hydrothermal vents, foraminifera do not venture into the extreme habitats where temperatures are greater than 20 °C. Where clam beds are found in association with active hydrogen sulphide venting, benthic foraminifera occur rarely. These beds occur in loose pyritic mud that is toxic to all but species (e.g. the clam Calyptogena) that co-exist symbiotically with sulphur-oxidizing bacteria. The sparse distribution of calcareous benthic foraminifera in the vent areas is caused by enhanced carbonate dissolution at pH values of 5.2. Low foraminiferal abundance and species diversity at the immediate site of active venting is attributed to rapid changes in phys

Control condition design and implementation features in controlled trials: a meta-analysis of trials evaluating psychotherapy for depression

Abstract: Control conditions are the primary methodology used to reduce threats to internal validity in randomized controlled trials (RCTs). This meta-analysis examined the effects of control arm design and implementation on outcomes in RCTs examining psychological treatments for depression. A search of MEDLINE, PsycINFO, and EMBASE identified all RCTs evaluating psychological treatments for depression published through June 2009. Data were analyzed using mixed-effects models. One hundred twenty-five trials were identified yielding 188 comparisons. Outcomes varied significantly depending control condition design (p < 0.0001). Significantly smaller effect sizes were seen when control arms used manualization (p = 0.006), therapist training (p = 0.002), therapist supervision (p = 0.009), and treatment fidelity monitoring (p = 0.003). There were no significant effects for differences in therapist experience, level of expertise in the treatment delivered, or nesting vs. crossing therapists in treatment arms. These findings demonstrate the substantial effect that decisions regarding control arm definition and implementation can have on RCT outcomes