Objective:We conducted an expedited knowledge synthesis (EKS) to facilitate evidenceinformed decision making concerning youth suicide prevention, specifically school-based strategies and nonschool-based interventions designed to prevent repeat attempts.Methods: Systematic review of review methods were applied. Inclusion criteria were as follows: systematic review or meta-analysis; prevention in youth 0 to 24 years; peer-reviewed English literature. Review quality was determined with AMSTAR (a measurement tool to assess systematic reviews). Nominal group methods quantified consensus on recommendations derived from the findings. Results:No included review addressing school-based prevention (n = 7) reported decreased suicide death rates based on randomized controlled trials (RCTs) or controlled cohort studies (CCSs), but reduced suicide attempts, suicidal ideation, and proxy measures of suicide risk were reported (based on RCTs and CCSs). Included reviews addressing prevention of repeat suicide attempts (n = 14) found the following: emergency department transition programs may reduce suicide deaths, hospitalizations, and treatment nonadherence (based on RCTs and CCSs); training primary care providers in depression treatment may reduce repeated attempts (based on one RCT); antidepressants may increase short-term suicide risk in some patients (based on RCTs and meta-analyses); this increase is offset by overall population-based reductions in suicide associated with antidepressant treatment of youth depression (based on observational studies); and prevention with psychosocial interventions requires further evaluation. No review addressed sex or gender differences systematically, Aboriginal youth as a special population, harm, or cost-effectiveness. Consensus on 6 recommendations ranged from 73% to 100%.

SUMMARYThe morphology of the colonization of maize {Zea mays L.) by the vesicular arbuscular mycorrhizal fungus Glomus versiforme (Daniels and Trappe) Berch was determined quantitatively to establish the stage at which colonization was limited in response to increased P nutrition. Harvests were taken 14, 19, 24 and 29 d after planting maize in a calcined clay medium to whicb nutrient solution containing 0'16, 0-8 or 2-4 mM P was added daily. Tbe fraction of tbe root lengtb containing arbuscules (FAC) 19 d after planting was 04 witb 0'16 mM P, 0-3, witb 0'8 mM P and 0'17 witb 2^4 mM P. Corresponding sboot P concentrations were 1-5, 2-0 and 3 2 mg g '. Increased shoot P concentration reduced the number of appressoria per unit root lengtb, but tbis accounted for only a part of tbe reduction in FAC. Increased root length did not account for tbe effect of sboot P concentration on FAC. Tbe lengtb of arbuscular colonized root lengtb (total root lengtb x FAC) per appressorium was strongly reduced in response to increased sboot P concentration. It was concluded tbat tbe reduction m FAC was mediated primarily tbrough an inbibition of intra-radical development.

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Simulated rainfall events were applied during the summer fallow period to a Western Australian agricultural soil, a loamy sand, under continuous wheat and after the second pasture phase of a 2 pasture : 1 wheat (2P : 1W) rotation. The aims of this study were to determine the change in microbial activity, amount of net and gross nitrogen (N) mineralised, and inorganic N produced after dry soil was re-wet during summer rainfall. Three irrigation treatments were applied: (i) control soils received no water, (ii) the single wet treatment received 45 mm of water on day 0 and was allowed to dry, and (iii) the multiple wet treatment received 45 mm of water on day 0 plus further applications of 5 mm on days 3 and 8. The CO2 production and N mineralisation were measured in the surface 10 cm of soil for a period of 14 days after initial irrigation. Net N mineralisation was measured from in situ incubation of soil cores and gross N mineralisation by 15N isotopic dilution. The CO2 production was measured by infrared gas analysis of air samples taken from a closed headspace above the soil. A large flush in CO2 production and gross N mineralisation occurred immediately after rewetting the dry soil. This response was short-lived and rates of CO2 production and gross N mineralisation declined rapidly after 2 days. After irrigation on day 0, CO2 production was twice as large and gross N mineralisation was slightly larger in the 2P : 1W soil than continuous wheat. Gross N mineralisation and CO2 production were not significantly different in the multiple and single wet treatments after the re-wet on day 3, but an additional flush in activity occurred in the multiple wet treatment after the re-wet on day 8. The patterns of gross N mineralisation and CO2 production corresponded to changes in the soil water content, especially in the surface 2·5 cm of soil. Net and gross N mineralised and gross N immobilised over the 14-day period after the initial re-wet were greater in the multiple wet compared with the single wet treatments under both wheat and 2P : 1W. However, gross N mineralisation was approximately 4-fold greater than net N mineralisation under wheat and 15-fold greater under 2P : 1W. The majority of gross N mineralised after simulated summer rainfall was immobilised which resulted in an increase in inorganic N within the soil profile (0-50 cm) during opening winter rains.