Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric ...chemistry, and air–surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM ∕ GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM ∕ GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg oxidation. Hence, the performance of the Hg oxidation mechanisms under study differs in the extent to which they can reproduce the various observed parameters. This variation implies possibility of more complex chemistry and multiple Hg oxidation pathways occurring concurrently in various parts of the atmosphere.
Objective
Access to adequate mental health (MH) services is necessary for nearly half of Canadian youth (18–24 years) who enroll in post-secondary education given the relatively high risk of MH ...problems. Our objectives were to determine the status of MH services available to students in post-secondary institutions in Canada and to determine the extent to which these services are based on the principles of a high-quality youth MH (YMH) service.
Method
Information on MH services was collected from websites of a representative sample (N = 67) of post-secondary institutions across all provinces. Data were analysed descriptively according to four categories (universities with a Faculty of Medicine (FoM) n = 18, other large universities n = 15, small universities n = 16, and colleges n = 18).
Results
Most institutions provided 24-h crisis line support (84%) and indicated the availability of free counselling or psychotherapy (n = 62 of 67, 92.5%), while only a minority indicated provision of an initial clinical assessment (25%) and provision of multiple sessions of therapy (37%). Wait time for first contact was impressively low (<72 h) in the minority of institutions (40%) which provided this information. Access to either a prescribing physician or psychiatrist was infrequent, though several mentioned an unexplained model of “stepped care” and outside referrals. While relevant information was not uniformly easy to access, larger institutions both with and without a FoM appear to be better poised to provide MH services. None of the institutions appeared to follow all the principles of service delivery recommended for a high-quality YMH, with only two showing early identification activities.
Conclusions
MH services in post-secondary institutions may need a transformation similar to YMH services, including a clear pathway to care, an initial clinical assessment, early identification of MHA disorders, and better utilization of institutional resources through greater collaboration and matching of timely interventions to the presenting problems.
The project MarParCloud (Marine biological production, organic
aerosol Particles and marine Clouds: a process
chain) aims to improve our understanding of the genesis, modification and
impact of ...marine organic matter (OM) from its biological production, to
its export to marine aerosol particles and, finally, to its ability to
act as ice-nucleating particles (INPs) and cloud condensation nuclei (CCN). A
field campaign at the Cape Verde Atmospheric Observatory (CVAO) in the
tropics in September–October 2017 formed the core of this project that was
jointly performed with the project MARSU (MARine atmospheric
Science Unravelled). A suite of chemical,
physical, biological and meteorological techniques was applied, and
comprehensive measurements of bulk water, the sea surface microlayer (SML),
cloud water and ambient aerosol particles collected at a ground-based and a
mountain station took place. Key variables comprised the chemical characterization of the atmospherically
relevant OM components in the ocean and the atmosphere as well as
measurements of INPs and CCN. Moreover, bacterial cell counts, mercury
species and trace gases were analyzed. To interpret the results, the
measurements were accompanied by various auxiliary parameters such as air
mass back-trajectory analysis, vertical atmospheric profile analysis, cloud
observations and pigment measurements in seawater. Additional modeling
studies supported the experimental analysis. During the campaign, the CVAO exhibited marine air masses with low and
partly moderate dust influences. The marine boundary layer was well mixed as
indicated by an almost uniform particle number size distribution within the
boundary layer. Lipid biomarkers were present in the aerosol particles in
typical concentrations of marine background conditions. Accumulation- and
coarse-mode particles served as CCN and were efficiently transferred to the
cloud water. The ascent of ocean-derived compounds, such as sea salt and
sugar-like compounds, to the cloud level, as derived from chemical analysis
and atmospheric transfer modeling results, denotes an influence of marine
emissions on cloud formation. Organic nitrogen compounds (free amino acids)
were enriched by several orders of magnitude in submicron aerosol particles
and in cloud water compared to seawater. However, INP measurements also indicated
a significant contribution of other non-marine sources to the local INP
concentration, as (biologically active) INPs were mainly present in
supermicron aerosol particles that are not suggested to undergo strong
enrichment during ocean–atmosphere transfer. In addition, the number of CCN
at the supersaturation of 0.30 % was about 2.5 times higher during dust
periods compared to marine periods. Lipids, sugar-like compounds, UV-absorbing (UV: ultraviolet) humic-like substances and low-molecular-weight neutral components
were important organic compounds in the seawater, and highly surface-active
lipids were enriched within the SML. The selective enrichment of specific
organic compounds in the SML needs to be studied in further detail and
implemented in an OM source function for emission modeling to better
understand transfer patterns, the mechanisms of marine OM transformation in the
atmosphere and the role of additional sources. In summary, when looking at particulate mass, we see oceanic compounds
transferred to the atmospheric aerosol and to the cloud level, while from a
perspective of particle number concentrations, sea spray aerosol (i.e.,
primary marine aerosol) contributions to both CCN and INPs are rather
limited.
Nasal intermittent positive pressure ventilation (NIPPV) has been shown to be superior to nasal continuous positive airway pressure (CPAP) postextubation in preterm neonates. However, studies have ...not permitted high CPAP pressures or rescue with other modes. We hypothesized that if CPAP pressures >8 cmH2O and rescue with other modes were permitted, CPAP would be noninferior to NIPPV.
We conducted a pragmatic, comparative-effectiveness, noninferiority study utilizing network-based real-world data from 22 Canadian NICUs. Centers self-selected CPAP or NIPPV as their standard postextubation mode for preterm neonates <29 weeks' gestation. The primary outcome was failure of the initial mode ≤72 hours. Secondary outcomes included failure ≤7 days, and reintubation ≤72 hours and ≤7 days. Groups were compared using a noninferiority adjusted risk-difference (aRD) margin of 0.05, and margin of no difference.
A total of 843 infants extubated to CPAP and 974 extubated to NIPPV were included. CPAP was not noninferior (and inferior) to NIPPV for failure of the initial mode ≤72 hours (33.0% vs 26.3%; aRD 0.07 0.03 to 0.12, Pnoninferiority(NI) = .86), and ≤7 days (40.7% vs 35.8%; aRD 0.09 0.05 to 0.13, PNI = 0.97). However, CPAP was noninferior (and equivalent) to NIPPV for reintubation ≤72 hours (13.2% vs 16.1%; aRD 0.01 -0.05 to 0.02, PNI < .01), and noninferior (and superior) for reintubation ≤7 days (16.4% vs 22.8%; aRD -0.04 -0.07 to -0.001, PNI < .01).
CPAP was not noninferior to NIPPV for failure ≤72 hours postextubation; however, it was noninferior to NIPPV for reintubation ≤72 hours and ≤7 days. This suggests CPAP may be a reasonable initial postextubation mode if alternate rescue strategies are available.
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