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Research on animal-assisted interventions (AAIs) has increased massively in the last few years. But it is still not clear how AAIs work and how important the animal is in such interventions. The aim of this systematic review was to compile the existing state of knowledge about the working mechanisms of AAIs. We searched 12 major electronic databases for previous AAI studies with active control groups. Of 2001 records identified, we included 172 studies in the systematic review. We extracted previously published hypotheses about working mechanisms and factors that have been implicitly considered specific or non-specific in AAI research by categorizing control conditions using content analysis. We analyzed the categories using descriptive statistics. We found that 84% of the included studies mentioned a hypothesis of working mechanisms, but 16% did not define specific hypotheses. By analyzing their control conditions, we found that in most controlled studies, the animal or the interaction with the animal was implicitly considered as a specific factor for the effects of the AAI. Non-specific factors such as therapeutic aspects, social interactions, or novelty have also been controlled for. We conclude that AAI research still cannot answer the question of how and why AAIs work. To address this important research gap, we suggest using component studies with innovative control conditions and results from placebo research to address both the specific and non-specific, contextual factors of AAIs to disentangle its mechanisms. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=158103, identifier: CRD42020158103.

Suicide is the third leading cause of death among adolescents. Many suicidal youths treated in emergency departments do not receive follow-up treatment as advocated by the National Strategy for Suicide Prevention. Two strategies for improving rates of follow-up treatment were compared.In a randomized controlled trial, suicidal youths at two emergency departments (N=181; ages ten to 18) were individually assigned between April 2003 and August 2005 to one of two conditions: an enhanced mental health intervention involving a family-based cognitive-behavioral therapy session designed to increase motivation for follow-up treatment and safety, supplemented by care linkage telephone contacts after emergency department discharge, or usual emergency department care enhanced by provider education. Assessments were conducted at baseline and approximately two months after discharge from the emergency department or hospital. The primary outcome measure was rates of outpatient mental health treatment after discharge.Intervention patients were significantly more likely than usual care patients to attend outpatient treatment (92% versus 76%; p=.004). The intervention group also had significantly higher rates of psychotherapy (76% versus 49%; p=.001), combined psychotherapy and medication (58% versus 37%; p=.003), and psychotherapy visits (mean 5.3 versus 3.1; p=.003). Neither the emergency department intervention nor community outpatient treatment (in exploratory analyses) was significantly associated with improved clinical or functioning outcomes.Results support efficacy of the enhanced emergency department intervention for improving linkage to outpatient mental health treatment but underscore the need for improved community outpatient treatment to prevent suicide, suicide attempts, and poor clinical and functioning outcomes for suicidal youths treated in emergency departments.

International audience

Iron is an essential nutrient involved in a variety of biological processes in the ocean, including photosynthesis, respiration and nitrogen fixation. Atmospheric deposition of aerosols is recognized as the main source of iron for the surface ocean. In high nutrient, low chlorophyll areas, it is now clearly established that iron limits phytoplankton productivity but its biogeochemical role in low nutrient, low chlorophyll environments has been poorly studied. We investigated this question in the unexplored southeast Pacific, arguably the most oligotrophic area of the global ocean. Situated far from any continental aerosol source, the atmospheric iron flux to this province is amongst the lowest of the world ocean. Here we report that, despite low dissolved iron concentrations (~0.1 nmol l−1) measured across the whole gyre (3 stations situated in the center, the western and the eastern edge), photosynthesis and primary productivity are only limited by iron availability at the border of the gyre, but not in the center. The seasonal stability of the gyre has apparently allowed for the development of populations acclimated to these extreme oligotrophic conditions. Moreover, despite clear evidence of nitrogen limitation in the central gyre, we were unable to measure nitrogen fixation in our experiments, even after iron and/or phosphate additions, and cyanobacterial nifH gene abundances were extremely low compared to the North Pacific Gyre. The South Pacific gyre is therefore unique with respect to the physiological status of its phytoplankton populations.

International audience; Prochlorococcus, Synechococcus, picophytoeukaryotes and bacterioplankton abundances and contributions to the total particulate organic carbon concentration (POC), derived from the total particle beam attenuation coefficient (cp), were determined across the eastern South Pacific between the Marquesas Islands and the coast of Chile. All flow cytometrically derived abundances decreased towards the hyper-oligotrophic centre of the gyre and were highest at the coast, except for Prochlorococcus, which is not detected under eutrophic conditions. Temperature and nutrient availability appeared important in modulating picophytoplankton abundance, according to the prevailing trophic conditions. Although the non-vegetal particles tended to dominate the cp signal everywhere along the transect (50 to 83%), this dominance seemed to weaken from oligo- to eutrophic conditions, the contributions by vegetal and non-vegetal particles being about equal under mature upwelling conditions. Spatial variability in the vegetal compartment was more important than the non-vegetal one in shaping the water column particulate attenuation coefficient. Spatial variability in picophytoplankton biomass could be traced by changes in both Tchla and cp. Finally, picophytoeukaryotes contributed with ~38% on average to the total integrated phytoplankton carbon biomass or vegetal attenuation signal along the transect, as determined by direct size measurements on cells sorted by flow cytometry and optical theory. The role of picophytoeukaryotes in carbon and energy flow would therefore be very important, even under hyper-oligotrophic conditions.

International audience; Probably because it is a readily available ocean color product, almost all models of primary productivity use chlorophyll as their index of phytoplankton biomass. As other variables become more readily available, both from remote sensing and in situ autonomous platforms, we should ask if other indices of biomass might be preferable. Herein, we compare the accuracy of different proxies of phytoplankton biomass for estimating the maximum photosynthetic rate (Pmax) and the initial slope of the production versus irradiance (P vs. E) curve (a). The proxies compared are: the total chlorophyll a concentration (Tchla, the sum of chlorophyll a and divinyl chlorophyll), the phytoplankton absorption coefficient, the phytoplankton photosynthetic absorption coefficient, the active fluorescence in situ, the particulate scattering coefficient at 650 nm (bp (650)), and the particulate backscattering coefficient at 650 nm (bbp (650)). All of the data (about 170 P vs. E curves) were collected in the South Pacific Ocean. We find that when only the phytoplanktonic biomass proxies are available, bp (650) and Tchla are respectively the best estimators of Pmax and alpha. When additional variables are available, such as the depth of sampling, the irradiance at depth, or the temperature, Tchla becomes the best estimator of both Pmax and a. From a remote sensing perspective, error propagation analysis shows that, given the current algorithms errors for estimating bbp(650), Tchla remains the best estimator of Pmax.