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Oxygen is declining globally in subsurface seawater. Fjords are particularly susceptible to hypoxia, because entrance sills restrict water circulation. We studied the oxygen dynamics of the Kitimat Fjord System on the west coast of Canada, using 3 yr of data from moored sensors and water column profiles. Subsurface oxygen within the fjord system is principally controlled by the connection to Hecate Strait on the outer shelf. Variations in oxygen concentration in Hecate Strait are reflected in the water that is drawn into the fjord system year‐round at mid‐depth (50–150 m). Deep water is renewed annually, beginning in May/June. Remineralization results in a seasonal decline in oxygen at depth. In the absence of deep‐water renewal, the bottom water in the system could become hypoxic in 1–2 yr. Mixing over a shallow inner sill (100 m) replenishes the oxygen in the deep water of Gardner Canal year‐round. The decadal trends in oxygen concentration show an increase from the 1950s to a maximum in the late 1970s, followed by a decline through 2016. The decline over the period 1977–2016 is 0.018 mL L−1 yr−1 (~ 0.83 μmol L−1 yr−1), which is consistent with the decline observed over the upper continental shelf over the same period. [ABSTRACT FROM AUTHOR]

BACKGROUND: Automated oxygen titration to maintain a stable SpO2 has been developed for spontaneously breathing patients but has not been evaluated during CPAP and noninvasive ventilation (NIV). METHODS: We performed a randomized controlled crossover, double-blind study on 10 healthy subjects with induced hypoxemia during 3 situations: spontaneous breathing with oxygen support, CPAP (5 cm H2O), and NIV (7/3 cm H2O). We conducted in random order 3 dynamic hypoxic challenges of 5 min (FIO2 0.08 6 0.02, 0.116 0.02, and 0.14 6 0.02). For each condition, we compared automated oxygen titration and manual oxygen titration by experienced respiratory therapists (RTs), with the aim to maintain the SpO2 at 94 6 2%. In addition, we included 2 subjects hospitalized for exacerbation of COPD under NIV and a subject managed after bariatric surgery with CPAP and automated oxygen titration. RESULTS: The percentage of time in the SpO2 target was higher with automated compared with manual oxygen titration for all conditions, on average 59.6 6 22.8% compared to 44.3 6 23.9% (P 5 .004). Hyperoxemia (SpO2 > 96%) was less frequent with automated titration for each mode of oxygen administration (24.0 6 24.4% vs 39.1 6 25.3%, P < .001). During the manual titration periods, the RT made several changes to oxygen flow (5.1 6 3.3 interventions that lasted 122 6 70 s/period) compared to none during the automated titration to maintain oxygenation in the targeted SpO2. Time in the SpO2 target was higher with stable hospitalized subjects in comparison with healthy subjects under dynamic-induced hypoxemia. CONCLUSIONS: In this proof-of-concept study, automated oxygen titration was used during CPAP and NIV. The performances to maintain the SpO2 target were significantly better compared to manual oxygen titration in the setting of this study protocol. This technology may allow decreasing the number of manual interventions for oxygen titration during CPAP and NIV. [ABSTRACT FROM AUTHOR]

Around 50% of humankind relies on groundwater as a source of drinking water. Here we investigate the age, geochemistry, and microbiology of 138 groundwater samples from 95 monitoring wells (<250 m depth) located in 14 aquifers in Canada. The geochemistry and microbiology show consistent trends suggesting large-scale aerobic and anaerobic hydrogen, methane, nitrogen, and sulfur cycling carried out by diverse microbial communities. Older groundwaters, especially in aquifers with organic carbon-rich strata, contain on average more cells (up to 1.4 × 107 mL−1) than younger groundwaters, challenging current estimates of subsurface cell abundances. We observe substantial concentrations of dissolved oxygen (0.52 ± 0.12 mg L−1 [mean ± SE]; n = 57) in older groundwaters that seem to support aerobic metabolisms in subsurface ecosystems at an unprecedented scale. Metagenomics, oxygen isotope analyses and mixing models indicate that dark oxygen is produced in situ via microbial dismutation. We show that ancient groundwaters sustain productive communities and highlight an overlooked oxygen source in present and past subsurface ecosystems of Earth. Microbes in ancient groundwaters can be very diverse and productive. Some microbes seem to produce oxygen in the dark, which others use to consume the greenhouse gas methane. Their metabolisms are relevant for groundwater health and global change. [ABSTRACT FROM AUTHOR]

Elevated water temperatures and low dissolved oxygen (hypoxia) are pervasive stressors in aquatic systems that can be exacerbated by climate change and anthropogenic activities, and there is growing interest in their interactive effects. To explore this interaction, we quantified the effects of acute and long-term hypoxia exposure on the critical thermal maximum (CT max ) of Redside Dace (Clinostomus elongatus), a small-bodied freshwater minnow with sparse populations in the Great Lakes Basin of Canada and designated as Endangered under Canada's Species at Risk Act. Fish were held at 18°C and acclimated to four levels of dissolved oxygen (>90%, 60%, 40%, and 20% air saturation). CT max was measured after 2 and 10 weeks of acclimation and after 3.5 weeks of reoxygenation, and agitation behavior was quantified during CT max trials. Aquatic surface respiration behavior was also quantified at 14 weeks of acclimation to oxygen treatments. Acute hypoxia exposure decreased CT max in fish acclimated to normoxia (>90% air saturation), but acclimation to hypoxia reduced this effect. There was no effect of acclimation oxygen level on CT max when measured in normoxia, and there was no effect of exposure time to hypoxia on CT max . Residual effects of hypoxia acclimation on CT max were not seen after reoxygenation. Agitation behavior varied greatly among individuals and was not affected by oxygen conditions. Fish performed aquatic surface respiration with low frequency, but performed it earlier when acclimated to higher levels of oxygen. Overall, this work sheds light on the vulnerability of fish experiencing acute hypoxia and heat waves concurrently., (© 2024 The Author(s). Journal of Experimental Zoology Part A: Ecological and Integrative Physiology published by Wiley Periodicals LLC.)

We recently read an interesting study which demonstrated that self-inflating resuscitation bag (SIRB) lacking expiratory valve has unreliable performance in oxygen delivery during spontaneous breathing mimicked by mechanical lung simulator. It was postulated that the absence of an expiratory valve and the resulting air entrainment via the exhaust port accounts for the poor oxygen delivery performance. The current disposable SIRB in-use in our institutions (Med-Rescuer Disposable BVM Resuscitator 4000, BLS Systems Limited, ON, Canada) has a duckbill valve but no expiratory valve. Safety concerns regarding its oxygen delivery performance during spontaneous breathing were raised, as this SIRB was commonly used to preoxygenate critically ill patient with potentially transmissible respiratory infection (e.g. COVID-19) before tracheal intubation. We therefore performed an experiment on this SIRB using one of us as a healthy volunteer. Our small experiment demonstrated that air entrainment could occur via the exhaust port and affect oxygen delivery performance. Our experiment also demonstrated that attaching a positive end-expiratory pressure (PEEP) valve to the exhaust port improves the oxygen delivery performance. The findings of this experiment were sent to the relevant department of our institutions for safety consideration. [ABSTRACT FROM AUTHOR]

We use life cycle assessment to model the environmental impacts of medical oxygen supply to hospitals. Although medical oxygen accounts for only 1% of global liquid oxygen production, it serves life-saving purposes in the healthcare sector, which is increasingly grappling with its environmental burdens. Considering six indicators in the TRACI impact assessment method, we estimate the total environmental impacts of bulk liquid oxygen – by far the dominant supply pathway in North America – as follows: global warming potential of 0.49 kg CO 2 eq., fossil fuel depletion of 0.90 MJ surplus, carcinogenic toxicity of 6.2 × 10−8 CTUh, non-carcinogenic toxicity of 2.1 × 10−7 CTUh, respiratory effects of 2.8 × 10−4 PM 2.5 eq., and ecotoxicity of 15 CTUe, per oxygen bed day, assuming a flow rate of 2 L/min. These impacts are primarily driven by electricity used to produce liquid oxygen via cryogenic distillation. Alternatively, liquid oxygen can be converted to gaseous form and shipped to hospitals in cylinder format – with substantially increased environmental impacts from the additional container and transportation. Medical oxygen can also be produced in gaseous form via pressure swing adsorption technology, either in an on-site plant or in a portable oxygen concentrator at the patient bedside. These alternatives may modestly reduce environmental impacts compared to liquid oxygen production, though the lower purity oxygen produced is less prevalent in clinical practice. We highlight several key variables affecting the environmental impacts of each medical oxygen supply pathway, including the location of production facilities (and corresponding electricity grids), losses in the supply-chain, and clinical practice (such as the choice of oxygen purity and flow rate). Limitations of our study include a lack of primary empirical data collection and a cradle-to-gate scope that omits other aspects of oxygen therapy such as hospital energy and water use (allocated to the procedure), wastes generated, and the production of medical equipment and consumables used. Ultimately, the results of our study suggest that medical oxygen production accounts for less than 1% of the total carbon footprint of healthcare in Canada. [ABSTRACT FROM AUTHOR]

Objectives: Noninvasive ventilation is widely used to avoid tracheal intubation in critically ill children. The objective of this study was to assess whether noninvasive ventilation failure was associated with severe tracheal intubation-associated events and severe oxygen desaturation during tracheal intubation.Design: Prospective multicenter cohort study of consecutive intubated patients using the National Emergency Airway Registry for Children registry.Setting: Thirteen PICUs (in 12 institutions) in the United States and Canada.Patients: All patients undergoing tracheal intubation in participating sites were included. Noninvasive ventilation failure group included children with any use of high-flow nasal cannula, continuous positive airway pressure, or bilevel noninvasive ventilation in the 6 hours prior to tracheal intubation. Primary tracheal intubation group included children without exposure to noninvasive ventilation within 6 hours before tracheal intubation.Interventions: None.Measurements and Main Results: Severe tracheal intubation-associated events (cardiac arrest, esophageal intubation with delayed recognition, emesis with aspiration, hypotension requiring intervention, laryngospasm, pneumothorax, pneumomediastinum) and severe oxygen desaturation (< 70%) were recorded prospectively. The study included 956 tracheal intubation encounters; 424 tracheal intubations (44%) occurred after noninvasive ventilation failure, with a median of 13 hours (interquartile range, 4-38 hr) of noninvasive ventilation. Noninvasive ventilation failure group included more infants (47% vs 33%; p < 0.001) and patients with a respiratory diagnosis (56% vs 30%; p < 0.001). Noninvasive ventilation failure was not associated with severe tracheal intubation-associated events (5% vs 5% without noninvasive ventilation; p = 0.96) but was associated with severe desaturation (15% vs 9% without noninvasive ventilation; p = 0.005). After controlling for baseline differences, noninvasive ventilation failure was not independently associated with severe tracheal intubation-associated events (p = 0.35) or severe desaturation (p = 0.08). In the noninvasive ventilation failure group, higher FIO2 before tracheal intubation (≥ 70%) was associated with severe tracheal intubation-associated events.Conclusions: Critically ill children are frequently exposed to noninvasive ventilation before intubation. Noninvasive ventilation failure was not independently associated with severe tracheal intubation-associated events or severe oxygen desaturation compared to primary tracheal intubation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Oxygen titration is recommended to avoid hyperoxemia and hypoxemia. Automated titration, as well as the SpO2 target, may have an impact on oxygen utilization, with potential logistical effects in emergency and military transportation. We sought to assess the oxygen flow required for different SpO2 targets in spontaneously breathing subjects, and to evaluate individualized automated oxygen titration to maintain stable oxygenation in subjects with COPD and healthy subjects with induced hypoxemia. METHODS: In the first part of the study, oxygen flow was evaluated in hospitalized subjects for different SpO2 targets from 90% to 98%. Oxygen requirements to reach these targets were determined using a device that automatically adjusts oxygen flow every second on the basis of the SpO2 target. In the second part of the study, the same automated oxygen titration method was used to correct hypoxemia in subjects with COPD and in healthy subjects with induced hypoxemia while the subjects wore a gas mask. Oxygen flow, SpO2, and heart rate were continuously recorded. RESULTS: Thirty-six spontaneously breathing hospitalized subjects were included in the first part of the study. Oxygen flow was reduced more than 6-fold when the SpO2 target was decreased from 98% to 90%. The second part of the study included 15 healthy and 9 subjects with stable COPD. In healthy subjects, heterogeneous oxygen flows were required to correct induced hypoxemia (0.2-2.5 L/min). In subjects with COPD, oxygen flow varied from 0 L/min (in 9 of 18 tested conditions) to 2.9 L/min. CONCLUSIONS: Significant reductions in the amount of oxygen delivered could be obtained with optimized SpO2 targets. Oxygen delivery through a gas mask to correct hypoxemia is feasible, and automated oxygen titration may help individualize oxygen administration and reduce oxygen utilization. [ABSTRACT FROM AUTHOR]

Introduction Air travel may expose patients with sickle cell disease (SCD) to an increased risk of disease-related complications. Several factors are felt to contribute including prolonged hypoxia, dehydration, temperature changes, and stress. The Canadian Paediatric Society (CPS) position statement, published in 2007, recommends that SCD patients use supplemental oxygen on flights. While the National Heart, Lung and Blood Institute (NHLBI) recommend that SCD patients dress warmly, stay hydrated, and move about the cabin. Other guidelines do not make specific recommendations. Methods A cross-sectional online survey was circulated through the Canadian Hemoglobinopathy Association (CanHaem) and American Society of Pediatric Hematology and Oncology (ASPHO) listservs to North American health care practitioners (HCPs). Participants were asked to share their air travel recommendations for patients with SCD. Similarly, a patient survey regarding experiences with air travel was circulated through the Sickle Cell Disease Association of Canada (SCDAC) and the Sickle Cell Foundation of Alberta (SCFOA) listservs and discussion boards. Results Although air travel is perceived to be a risk factor for sickling complications, only 18% of HCPs recommend supplemental oxygen. Most HCPs advise patients to increase hydration, carry analgesics, and wear warm clothes to prevent sickling complications. The patient survey was limited by a low response rate. Conclusion The majority of HCPs are not routinely recommending prophylactic oxygen to patients with SCD during air travel. [ABSTRACT FROM AUTHOR]

Rationale: Cardiopulmonary exercise testing (CPET) is the gold standard to evaluate exertional breathlessness, a common and disabling symptom. However, the interpretation of breathlessness responses to CPET is limited by a scarcity of normative data. Objectives: We aimed to develop normative reference equations for breathlessness intensity (Borg 0-10 category ratio) response in men and women aged ⩾40 years during CPET, in relation to power output (watts), oxygen uptake, and minute ventilation. Methods: Analysis of ostensibly healthy people aged ⩾40 years undergoing symptom-limited incremental cycle CPET (10 W/min) in the CanCOLD (Canadian Cohort Obstructive Lung Disease) study. Participants had smoking histories <5 pack-years and normal lung function and exercise capacity. The probability of each Borg 0-10 category ratio breathlessness intensity rating by power output, oxygen uptake, and minute ventilation (as an absolute or a relative value [percentage of predicted maximum]) was predicted using ordinal multinomial logistic regression. Model performance was evaluated by fit, calibration, and discrimination (C statistic) and externally validated in an independent sample ( n  = 86) of healthy Canadian adults. Results: We included 156 participants (43% women) from CanCOLD; the mean age was 65 (range, 42-91) years, and the mean body mass index was 26.3 (standard deviation, 3.8) kg/m 2 . Reference equations were developed for women and men separately, accounting for age and/or body mass. Model performance was high across all equations, including in the validation sample (C statistic for men = 0.81-0.92, C statistic for women = 0.81-0.96). Conclusions: Normative reference equations are provided to compare exertional breathlessness intensity ratings among individuals or groups and to identify and quantify abnormal breathlessness responses (scores greater than the upper limit of normal) during CPET.

Background: Respiratory distress is the leading cause of neonatal morbidity and mortality worldwide, and prenatal exposure to air pollution is associated with adverse long-term respiratory outcomes; however, the impact of prenatal air pollution exposure on neonatal respiratory distress has not been well studied., Objectives: We examined associations between prenatal exposures to fine particular matter ( PM 2.5 ) and nitrogen dioxide ( NO 2 ) with respiratory distress and related neonatal outcomes., Methods: We used data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a prospective pregnancy cohort ( n = 2,001 ) recruited in the first trimester from 10 Canadian cities. Prenatal exposures to PM 2.5 ( n = 1,321 ) and NO 2 ( n = 1,064 ) were estimated using land-use regression and satellite-derived models coupled with ground-level monitoring and linked to participants based on residential location at birth. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for associations between air pollution and physician-diagnosed respiratory distress in term neonates in hierarchical logistic regression models adjusting for detailed maternal and infant covariates., Results: Approximately 7 % of newborns experienced respiratory distress. Neonates received clinical interventions including oxygen therapy (6%), assisted ventilation (2%), and systemic antibiotics (3%). Two percent received multiple interventions and 4% were admitted to the neonatal intensive care unit (NICU). Median PM 2.5 and NO 2 concentrations during pregnancy were 8.81   μ g / m 3 and 18.02  ppb , respectively. Prenatal exposures to air pollution were not associated with physician-diagnosed respiratory distress, oxygen therapy, or NICU admissions. However, PM 2.5 exposures were strongly associated with assisted ventilation (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.17 ; 95% CI: 1.02, 1.35), multiple clinical interventions (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.16 ; 95% CI: 1.07, 1.26), and systemic antibiotics, (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.12 ; 95% CI: 1.04, 1.21). These associations were consistent across exposure periods-that is, during prepregnancy, individual trimesters, and total pregnancy-and robust to model specification. NO 2 exposure was associated with administration of systemic antibiotics (OR per 1-ppb increase in NO 2 = 1.03 ; 95% CI: 1.00, 1.06)., Discussion: Prenatal exposures to PM 2.5 increased the risk of severe respiratory distress among term newborns. These findings support the development and prioritization of public health and prenatal care strategies to increase awareness and minimize prenatal exposures to air pollution. https://doi.org/10.1289/EHP12880.

Objective: To assess the effectiveness and adverse effects of acute cluster headache medications in a large international sample, including recommended treatments such as oxygen, commonly used medications such as opioids, and emerging medications such as intranasal ketamine. Particular focus is paid to a large subset of respondents 65 years of age or older. Background: Large international surveys of cluster headache are rare, as are examinations of treatments and side effects in older cluster headache patients. This article presents data from the Cluster Headache Questionnaire, with respondents from over 50 countries and with the vast majority from the United States, the United Kingdom, and Canada. Methods: This internet‐based survey included questions on cluster headache diagnostic criteria, which were used as part of the inclusion/exclusion criteria for the study, as well as effectiveness of medications, physical and medical complications, psychological and emotional complications, mood scores, and difficulty obtaining medications. The diagnostic questions were also used to create a separate group of respondents with probable cluster headache. Limitations to the methods include the use of nonvalidated questions, the lack of a formal clinical diagnosis of cluster headache, and the grouping of some medications (eg, all triptans as opposed to sumatriptan subcutaneous alone). Results: A total of 3251 subjects participated in the questionnaire, and 2193 respondents met criteria for this study (1604 cluster headache and 589 probable cluster headache). Of the respondents with cluster headache, 68.8% (1104/1604) were male and 78.0% (1245/1596) had episodic cluster headache. Over half of respondents reported complete or very effective treatment for triptans (54%, 639/1139) and oxygen (54%, 582/1082). Between 14 and 25% of respondents reported complete or very effective treatment for ergot derivatives (dihydroergotamine 25%, 42/170; cafergot/ergotamine 17%, 50/303), caffeine and energy drinks (17%, 7/41), and intranasal ketamine (14%, 5/37). Less than 10% reported complete or very effective treatment for opioids (6%, 30/541), intranasal capsaicin (5%, 7/151), and intranasal lidocaine (2%, 5/241). Adverse events were especially low for oxygen (no or minimal physical and medical complications 99%, 1077/1093; no or minimal psychological and emotional complications 97%, 1065/1093), intranasal lidocaine (no or minimal physical and medical complications 97%, 248/257; no or minimal psychological and emotional complications 98%, 251/257), intranasal ketamine (no or minimal physical and medical complications 95%, 38/40; no or minimal psychological and emotional complications 98%, 39/40), intranasal capsaicin (no or minimal physical and medical complications 91%, 145/159; no or minimal psychological and emotional complications 94%, 150/159), and caffeine and energy drinks (no or minimal physical and medical complications 89%, 39/44; no or minimal psychological and emotional complications 91%, 40/44). This is in comparison to ergotamine/cafergot (no or minimal physical and medical complications 83%, 273/327; no or minimal psychological and emotional complications 89%, 290/327), dihydroergotamine (no or minimal physical and medical complications 81%, 143/176; no or minimal psychological and emotional complications 91%, 160/176), opioids (no or minimal physical and medical complications 76%, 416/549; no or minimal psychological and emotional complications 77%, 423/549), or triptans (no or minimal physical and medical complications 73%, 883/1218; no or minimal psychological and emotional complications 85%, 1032/1218). A total of 139 of 1604 cluster headache respondents (8.7%) were age 65 and older and reported similar effectiveness and adverse events to the general population. The 589 respondents with probable cluster headache reported similar medication effectiveness to respondents with a full diagnosis of cluster headache. Conclusions: Oxygen is reported by survey respondents to be a highly effective treatment with few complications in cluster headache in a large international sample, including those 65 years or over. Triptans are also very effective with some side effects, and newer medications deserve additional study. Patients with probable cluster headache may respond similarly to acute medications as patients with a full diagnosis of cluster headache. [ABSTRACT FROM AUTHOR]

Background: There is an increasing interest in 'transfer under pressure' (TUP) decompression in commercial diving, bridging traditional surface-oriented diving and saturation diving. In TUP diving the diver is surfaced in a closed bell and transferred isobarically to a pressure chamber for final decompression to surface pressure., Methods: Tables for air diving and air and oxygen decompression have been compared for total decompression time (TDT), oxygen breathing time as well as high and low gradient factors (GF high and low). These have been considered surrogate outcome measures of estimated decompression sickness probability (P DCS )., Results: Six decompression tables from DadCoDat (DCD, The Netherlands), Defence and Civil Institute of Environmental Medicine (DCIEM, Canada), Comex MT92 tables (France) and the United States Navy (USN) have been compared. In general, USN and DCD procedures advised longer TDT and oxygen breathing time and had a lower GF high compared to MT92 and DCIEM tables. GF low was significantly higher in USN procedures compared to DCD and one of the MT92 tables due to a shallower first stop in many USN profiles compared to the two others. Allowance and restrictions for repetitive diving varied extensively between the six procedures. While USN procedures have been risk-assessed by probabilistic models, no detailed documentation is available for any of the tables regarding validation in experimental and operational diving., Conclusions: Absence of experimental testing of the candidate tables precludes firm conclusions regarding differences in P DCS . All candidate tables are recognised internationally as well as within their national jurisdictions, and final decisions on procedure preference may depend on factors other than estimated P DCS . USN and DCD procedures would be expected to have lower P DCS than MT92 and DCIEM procedures, but the magnitude of these differences is not known., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Background: Gypsum Hill Spring, located in Nunavut in the Canadian High Arctic, is a rare example of a cold saline spring arising through thick permafrost. It perennially discharges cold (~ 7 °C), hypersaline (7-8% salinity), anoxic (~ 0.04 ppm O 2 ), and highly reducing (~ - 430 mV) brines rich in sulfate (2.2 g.L -1 ) and sulfide (9.5 ppm), making Gypsum Hill an analog to putative sulfate-rich briny habitats on extraterrestrial bodies such as Mars., Results: Genome-resolved metagenomics and metatranscriptomics were utilized to describe an active microbial community containing novel metagenome-assembled genomes and dominated by sulfur-cycling Desulfobacterota and Gammaproteobacteria. Sulfate reduction was dominated by hydrogen-oxidizing chemolithoautotrophic Desulfovibrionaceae sp. and was identified in phyla not typically associated with sulfate reduction in novel lineages of Spirochaetota and Bacteroidota. Highly abundant and active sulfur-reducing Desulfuromusa sp. highly transcribed non-coding RNAs associated with transcriptional regulation, showing potential evidence of putative metabolic flexibility in response to substrate availability. Despite low oxygen availability, sulfide oxidation was primarily attributed to aerobic chemolithoautotrophic Halothiobacillaceae. Low abundance and transcription of photoautotrophs indicated sulfur-based chemolithoautotrophy drives primary productivity even during periods of constant illumination., Conclusions: We identified a rare surficial chemolithoautotrophic, sulfur-cycling microbial community active in a unique anoxic, cold, hypersaline Arctic spring. We detected Mars-relevant metabolisms including hydrogenotrophic sulfate reduction, sulfur reduction, and sulfide oxidation, which indicate the potential for microbial life in analogous S-rich brines on past and present Mars. Video Abstract., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Background: Long-term oxygen therapy (LTOT) is the only component of the management of chronic obstructive pulmonary disease (COPD) that improves survival in patients with severe daytime hypoxemia. LTOT is usually provided by a stationary oxygen concentrator and is recommended to be used for at least 15-18 h a day. Several studies have demonstrated a deterioration in arterial blood gas pressures and oxygen saturation during sleep in patients with COPD, even in those not qualifying for LTOT. The suggestion has been made that the natural progression of COPD to its end stages of chronic pulmonary hypertension, severe hypoxemia, right heart failure, and death is dependent upon the severity of desaturation occurring during sleep. The primary objective of the International Nocturnal Oxygen (INOX) trial is to determine, in patients with COPD not qualifying for LTOT but who present significant nocturnal arterial oxygen desaturation, whether nocturnal oxygen provided for a period of 3 years decreases mortality or delay the prescription of LTOT.Methods: The INOX trial is a 3-year, multi-center, placebo-controlled, randomized trial of nocturnal oxygen therapy added to usual care. Eligible patients are those with a diagnosis of COPD supported by a history of past smoking and obstructive disease who fulfill our definition of significant nocturnal oxygen desaturation (i.e., ≥ 30% of the recording time with transcutaneous arterial oxygen saturation < 90% on either of two consecutive recordings). Patients allocated in the control group receive room air delivered by a concentrator modified to deliver 21% oxygen. The comparison is double blind. The primary outcome is a composite of mortality from all cause or requirement for LTOT. Secondary outcomes include quality of life and utility measures, costs from a societal perspective and compliance with oxygen therapy. The follow-up period is intended to last at least 3 years.Discussion: The benefits of LTOT have been demonstrated whereas those of nocturnal oxygen therapy alone have not. The INOX trial will likely determine whether supplemental oxygen during sleep is effective in reducing mortality, delaying the need for LTOT and improving health-related quality of life in patients with COPD who desaturate overnight.Trial Registration: Current Controlled Trials ISRCTN50085100 ; ClinicalTrials.gov NCT01044628 (date of registration: January 6, 2010). [ABSTRACT FROM AUTHOR]

In the coming decades, warming and deoxygenation of marine waters are anticipated to result in shifts in the distribution and abundance of fishes, with consequences for the diversity and composition of fish communities. Here, we combine fisheries-independent trawl survey data spanning the west coast of the USA and Canada with high-resolution regional ocean models to make projections of how 34 groundfish species will be impacted by changes in temperature and oxygen in British Columbia (BC) and Washington. In this region, species that are projected to decrease in occurrence are roughly balanced by those that are projected to increase, resulting in considerable compositional turnover. Many, but not all, species are projected to shift to deeper depths as conditions warm, but low oxygen will limit how deep they can go. Thus, biodiversity will likely decrease in the shallowest waters (less than 100 m), where warming will be greatest, increase at mid-depths (100-600 m) as shallow species shift deeper, and decrease at depths where oxygen is limited (greater than 600 m). These results highlight the critical importance of accounting for the joint role of temperature, oxygen and depth when projecting the impacts of climate change on marine biodiversity. This article is part of the theme issue 'Detecting and attributing the causes of biodiversity change: needs, gaps and solutions'.

Purpose: The objective of this study was to describe the clinical course and outcomes in children with technology dependence (TD) hospitalized with SARS-CoV-2 infection., Methods: Seventeen pediatric hospitals (15 Canadian and one each in Iran and Costa Rica) included children up to 17 years of age admitted February 1, 2020, through May 31, 2021, with detection of SARS-CoV-2. For those with TD, data were collected on demographics, clinical course and outcome., Results: Of 691 children entered in the database, 42 (6%) had TD of which 22 had feeding tube dependence only, 9 were on supplemental oxygen only, 3 had feeding tube dependence and were on supplemental oxygen, 2 had a tracheostomy but were not ventilated, 4 were on non-invasive ventilation, and 2 were on mechanical ventilation prior to admission. Three of 42 had incidental SARS-CoV-2 infection. Two with end-stage underlying conditions were transitioned to comfort care and died. Sixteen (43%) of the remaining 37 cases required increased respiratory support from baseline due to COVID-19 while 21 (57%) did not. All survivors were discharged home., Conclusion: Children with TD appear to have an increased risk of COVID-19 hospitalization. However, in the absence of end-stage chronic conditions, all survived to discharge., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

The Athabasca Oil Sands contain one of the world's largest oil reserves consisting of approximately 168 billion barrels of currently recoverable bitumen. With 20% recoverable through open pit mining methods, this extraction process produces a considerable amount of fluid fine tailings (FFT) waste material, which must be deposited on site in tailings ponds. These ponds allow the waste sand, clay and residual bitumen to settle out of the water column, allowing for the water to be recycled for use again in the extraction process. It is vital to gain a better understanding of the processes contributing to the development of physicochemical gradients (pH, Eh, Oxygen etc…) that form in these tailings ponds over time, with the goal of remediation and subsequent construction of end-pit lake systems once oil extraction has ceased. To differentiate between the impacts of biotic and abiotic processes in fresh (newly processed material) and mature FFT (∼38 year old tailings) over a 52-week study, a specific experimental design was utilized in accordance with novel microsensor profiling techniques. The sulfide diffusive fluxes within mature biotic systems measured 37.6 μmol m −2 day −1 at the onset of the experiment, decreasing over time, as FeS mineralization progressed. In addition, DO fluxes also showed strong correlation to the physical affects of consolidation, and overall biological consumption of O 2 at the FFT-water interface. This holistic study comparing different tailings pond materials provides insight regarding biotransformation and physicochemical controls effecting sediment oxygen demand associated with reclaimed wetlands and end pit lake development. [ABSTRACT FROM AUTHOR]

Introduction: Members of the Canadian Armed Forces (CAF) are required to meet the minimum standards of the Fitness for Operational Requirements of CAF Employment (FORCE) job-based simulation test (JBST) and must possess the capacity to perform other common essential tasks. One of those tasks is to perform basic fire management tasks during fire emergencies to mitigate damage and reduce the risk of injuries and/or death until professional firefighters arrive at the scene. To date however, the physiological demands of common firefighting tasks have mostly been performed on professional firefighters, thus rendering the transferability of the demands to the general military population unclear. This pilot study aimed to quantify, for the first time, the physiological demands of basic fire management tasks in the military, to determine if they are reflected in the FORCE JBST minimum standard. We hypothesized that the physiological demands of basic fire management tasks within the CAF are below the physiological demands of the FORCE JBST minimum standard, and as such, be lower than the demands of professional firefighting., Materials and Methods: To achieve this, 21 CAF members (8 females; 13 males; mean [SD] age: 33 [10] years; height: 174.5 [10.5] cm; weight: 85.4 [22.1] kg, estimated maximal oxygen uptake [$\dot V$O2peak]: 44.4 (7.4) mL kg-1 min-1) participated in a realistic, but physically demanding, JBST developed by CAF professional firefighting subject matter experts. The actions included lifting, carrying, and manipulating a 13-kg powder fire extinguisher and connecting, coupling, and dragging a 38-mm fire hose over 30 m. The rate of oxygen uptake ($\dot V$O2), heart rate, and percentage of heart rate reserve were measured continuously during two task simulation trials, which were interspersed by a recovery period. Rating of perceived exertion (6-no exertion; 20-maximal exertion) was measured upon completion of both task simulations. Peak $\dot V$O2 ($\dot V$O2peak) was estimated based on the results of the FORCE JBST., Results: The mean (SD) duration of both task simulation trials was 3:39 (0:19) min:s, whereas the rest period in between both trials was 62 (19) minutes. The mean O2 was 21.1 (4.7) mL kg-1 min-1 across trials, which represented 52.1 (12.2) %$\dot V$O2peak and ∼81% of the FORCE JBST. This was paralleled by a mean heart rate of 136 (18) beats min-1, mean percentage of heart rate reserve of 61.2 (10.8), and mean rating of perceived exertion of 11 ± 2. Other physical components of the JBST consisted of lifting, carrying, and manipulating a 13-kg load for ∼59 seconds, which represents 65% of the load of the FORCE JBST. The external resistance of the fire hose drag portion increased up to 316 N, translating to a total of 6205 N over 30 m, which represents 96% of the drag force measured during the FORCE JBST., Conclusions: Our findings demonstrate that the physiological demands of basic fire management tasks in the CAF are of moderate intensity, which are reflected in the CAF physical fitness standard. As such, CAF members who achieve the minimum standard on the FORCE JBST are deemed capable of physically performing basic fire management tasks during fire emergencies., (© The Association of Military Surgeons of the United States 2021. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Identifying the relationship between maximum consumption of oxygen and body fat percentage is important due to increased cardiovascular risk factors., Objective: This study aimed to verify the association between body fat percentage determined by three predictive equations using anthropometric measures (Lohman, Boileau, and Slaughter) and maximum oxygen uptake (VO2max). We also aimed to estimate the capacity of these equations for explaining VO2max variations in adolescents according to sex., Design and Setting: This was a cross-sectional study conducted in high schools in São José, Southern Brazil., Methods: This study included 879 adolescents (14-19 years) from Southern Brazil. Aerobic fitness was assessed using the modified Canadian Aerobic Fitness Test. The independent variable was body fat percentage predicted by the Lohman, Boileau, and Slaughter equations. Analyses adjusted for sociodemographic variables, physical activity level, and sexual maturation were performed with P value < 0.05., Results: All anthropometric prediction equations used to estimate body fat percentage explained VO2max variations in adolescents. In male adolescents, both regression models based on the Boileau et al.12 and Lohman10 equations revealed higher explanatory power for VO2max (20%) compared with that based on the Slaughter et al.13 equation (19%). In female adolescents, the model based on the anthropometric equation of Slaughter et al.13 showed the greatest explanatory power for VO2max (18%)., Conclusion: The inverse relationship between VO2max and body fat intensifies the need for effective intervention programs that prioritize maintenance of appropriate body fat and aerobic fitness levels because inadequate levels of both factors result in negative health consequences.

Background: Hospitals expanded critical care capacity during the COVID-19 pandemic by treating COVID-19 patients with high-flow nasal cannula oxygen therapy (HFNC) in non-traditional settings, including general internal medicine (GIM) wards. The impact of this practice on intensive care unit (ICU) capacity is unknown., Objective: To describe how our hospital operationalized the use of HFNC on GIM wards, assess its impact on ICU capacity, and examine the characteristics and outcomes of treated patients., Design: Retrospective cohort study of all patients treated with HFNC on GIM wards at a Canadian tertiary care hospital., Participants: All patients admitted with COVID-19 and treated with HFNC on GIM wards from December 28, 2020, to June 13, 2021, were included., Main Measures: We combined administrative data on critical care occupancy daily with chart-abstracted data for included patients to establish the total number of patients receiving ICU-level care at our hospital per day. We also collected data on demographics, medical comorbidities, illness severity, COVID-19 treatments, HFNC care processes, and patient outcomes., Key Results: We treated 124 patients with HFNC on the GIM wards (median age 66 years; 48% female). Patients were treated with HFNC for a median of 5 days (IQR 3 to 8); collectively, they received HFNC for a total of 740 hospital days, 71% of which were on GIM wards. At peak ICU capacity strain (144%), delivering HFNC on GIM wards added 20% to overall ICU capacity by managing up to 14 patients per day. Patients required a median maximal fraction of inspired oxygen of 80% (IQR 60 to 95). There were 18 deaths (15%) and 85 patients (69%) required critical care admission; of those, 40 (47%) required mechanical ventilation., Conclusions: With appropriate training and resources, treatment of COVID-19 patients with HFNC on GIM wards appears to be a feasible strategy to increase critical care capacity., (© 2022. The Author(s), under exclusive licence to Society of General Internal Medicine.)

Alzheimer's disease (AD) is associated with abnormal resting-state network (RSN) architecture of the default mode network (DMN), the dorsal attention network (DAN), the executive control network (CON), the salience network (SAL), and the sensory-motor network (SMN). However, little is known about the disrupted intra- and inter-network architecture in mild cognitive impairment (MCI). Here, we employed a priori defined regions of interest to investigate the intra- and inter-network functional connectivity profiles of these RSNs in longitudinal participants, including normal controls (n = 23), participants with early MCI (n = 26), and participants with late MCI (n = 19). We found longitudinal alterations of functional connectivity within the DMN, where they were correlated with variation in cognitive ability. The SAL as well as the interaction between the DMN and the SAL were disrupted in MCI. Furthermore, our results demonstrate that longitudinal alterations of functional connectivity are more profound in earlier stages as opposed to later stages of the disease. The increased severity of cognitive impairment is associated with increasingly altered RSN connectivity patterns, suggesting that disruptions in functional connectivity may contribute to cognitive dysfunction and may represent a potential biomarker of impaired cognitive ability in MCI. Earlier prevention and treatment may help to delay disease progression to AD. [ABSTRACT FROM AUTHOR]

The Grand River is a 7th-order 300-km river draining the largest watershed (6800 km²) in southern Ontario, Canada. The watershed has experienced large landuse changes during a period >100 y, resulting in increasing agricultural and urban nutrient inputs to the river. As a result, the Grand River is highly degraded from its source to mouth. We studied longitudinal and temporal changes in aquatic community metabolism (photosynthesis and respiration) and O2 gas exchange over 3 seasons using O2 and d18O-O2. Diel changes in O2 saturation were >50 percentage points along the river. In some parts, the diel O2 change was >10 mg/L. Strong daily variation in d18O-O2, up to 22‰, was observed at all 23 sampling sites in the river. Despite consistently high nutrient levels and high productivity from headwaters to mouth, wastewater treatment plant (WWTP) effluents strongly affected O2 saturation in all seasons. Modifications to river flow or nutrient inputs that affect the O2 gas-exchange coefficient or O2 demand could exacerbate current nighttime hypoxia problems. Strong diel variability in O2 may not directly indicate changes in metabolic rates because changes in gas-exchange coefficients alone are enough to mask changes in metabolic rates. Photosynthetic rates immediately downstream of WWTPs did not increase because nutrients were already high because of agricultural nutrient loading upstream of WWTPs. As a result, WWTP nutrients were exported downstream rather than used immediately below the WWTPs and the zone of impact from WWTP nutrients extended farther downstream than would otherwise be expected. O2 is the measure used by ecosystem managers, but metabolism and gas exchange must be managed to achieve the desired O2 outcomes. [ABSTRACT FROM AUTHOR]

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Background: COVID-19 disease is accompanied by a dysregulated immune response and hypercoagulability. The Anti-Coronavirus Therapies (ACT) inpatient trial aimed to evaluate anti-inflammatory therapy with colchicine and antithrombotic therapy with the combination of rivaroxaban and aspirin for prevention of disease progression in patients hospitalised with COVID-19., Methods: The ACT inpatient, open-label, 2 × 2 factorial, randomised, controlled trial was done at 62 clinical centres in 11 countries. Patients aged at least 18 years with symptomatic, laboratory confirmed COVID-19 who were within 72 h of hospitalisation or worsening clinically if already hospitalised were randomly assigned (1:1) to receive colchicine 1·2 mg followed by 0·6 mg 2 h later and then 0·6 mg twice daily for 28 days versus usual care; and in a second (1:1) randomisation, to the combination of rivaroxaban 2·5 mg twice daily plus aspirin 100 mg once daily for 28 days versus usual care. Investigators and patients were not masked to treatment allocation. The primary outcome, assessed at 45 days in the intention-to-treat population, for the colchicine randomisation was the composite of the need for high-flow oxygen, mechanical ventilation, or death; and for the rivaroxaban plus aspirin randomisation was the composite of major thrombosis (myocardial infarction, stroke, acute limb ischaemia, or pulmonary embolism), the need for high-flow oxygen, mechanical ventilation, or death. The trial is registered at www., Clinicaltrials: gov, NCT04324463 and is ongoing., Findings: Between Oct 2, 2020, and Feb 10, 2022, at 62 sites in 11 countries, 2749 patients were randomly assigned to colchicine or control and the combination of rivaroxaban and aspirin or to the control. 2611 patients were included in the analysis of colchicine (n=1304) versus control (n=1307); 2119 patients were included in the analysis of rivaroxaban and aspirin (n=1063) versus control (n=1056). Follow-up was more than 98% complete. Overall, 368 (28·2%) of 1304 patients allocated to colchicine and 356 (27·2%) of 1307 allocated to control had a primary outcome (hazard ratio [HR] 1·04, 95% CI 0·90-1·21, p=0·58); and 281 (26·4%) of 1063 patients allocated to the combination of rivaroxaban and aspirin and 300 (28·4%) of 1056 allocated to control had a primary outcome (HR 0·92, 95% CI 0·78-1·09, p=0·32). Results were consistent in subgroups defined by vaccination status, disease severity at baseline, and timing of randomisation in relation to onset of symptoms. There was no increase in the number of patients who had at least one serious adverse event for colchicine versus control groups (87 [6·7%] of 1304 vs 90 [6·9%] of 1307) or with rivaroxaban and aspirin versus control groups (85 [8·0%] vs 91 [8·6%]). Among patients assigned to colchicine, 8 (0·61%) had adverse events that led to discontinuation of study drug, mostly gastrointestinal in nature. 17 (1·6%) patients assigned to the combination of rivaroxaban and aspirin had bleeding compared with seven (0·66%) of those allocated to control (p=0·042); the number of serious bleeding events was two (0·19%) versus six (0·57%), respectively (p=0·18). No patients assigned to rivaroxaban and aspirin had serious adverse events that led to discontinuation of study drug., Interpretation: Among patients hospitalised with COVID-19, neither colchicine nor the combination of rivaroxaban and aspirin prevent disease progression or death., Funding: Canadian Institutes for Health Research, Bayer, Population Health Research Institute, Hamilton Health Sciences Research Institute, Thistledown Foundation., Translations: For the Portuguese, Russian and Spanish translations of the abstract see Supplementary Materials section., Competing Interests: Declaration of interests JWE reports grant or in-kind support from AstraZeneca, Bayer, Boehringer-Ingelheim, Bristol Myers Squibb, GlaxoSmithKline, Pfizer, Janssen, Sanofi-Aventis and honoraria from Astra-Zeneca, Bayer, Boehringer-Ingelheim, Bristol-Myer-Squibb, Daiichi-Sankyo, Eli-Lilly, Glaxo-Smith-Kline, Merck, Pfizer, Janssen, Sanofi-Aventis, Servier. SSJ reports grant support from Boston Scientific, honoraria from Medtronic, Penumbra. EPB-C reports grant support from Bayer, Roche, BMS-Pfizer. RPW reports grant support from Bayer, Roche, BMS-Pfizer, grant and honorarium from Boehringer-Ingelheim, and consultancy fees from Atricure and Phasebio. MLD reports grant support from the Population Health Research Institute (PHRI) to manage the ACT study in Argentina. RD reports grant support from PHRI to manage the ACT study in Argentina. AA reports institutional grant support from Bayer and EMS, and lecture fees from Bayer and Sanofi-Aventis. SW reports grant support from NIH, honoraria from Pfizer, and safety monitoring committee of an AIDS Clinical Trial Group. RDL reports institutional grant support from Bristol Myers Squibb, Glaxo Smith Kline, Medtronic, Pfizer, and Sanofi, consulting fees from Bristol Myers Squibb, GlaxoSmithKline, Medtronic, Pfizer, Sanofi, Bayer, Boehringer Ingelheim, Daiichi Sankyo, Merck, and Portola, honoraria from Pfizer and meeting travel support from IQVIA. OB reports grant support from Astra Zeneca, Bayer, Amgen, Novartis, Servier, Pfizer. SSA reports grants from CIHR and PHAC, honoraria and consulting fees from Bayer and Janssen Pharma, meeting support from Heart and Stroke Canada, is committee member at the American Heart Association, the Canadian Cardiovascular Society, and Heart and Stroke Canada. JB reports consulting fees from Bayer. SC reports ACT study funding from Bayer, owns Bayer stock, is a board member of Canadian Arrhythmia Network, is an institutional advisory board member at the Institute of Circulatory and Respiratory Health, Canadian Institutes for Health Research. MEF reports institutional grants from Amgen, Astra Zeneca, Novartis, and Novo Nordisk and consulting fees from Otitopic. ML reports participation in vaccine advisory boards for Medicago, Pfizer, and Sanofi and is on the data safety and monitoring board for CanSino Biologics. SY reports institutional grant support from Bayer and honoraria, and travel costs for lectures from Bayer. SR, LX, LH, SIB, AY, SKS, WMT, MH, WH, AA, OD, CF, and PL-J have no disclosures to report., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This paper describes the results of an investigation for the degree of equivalence of realizations of the triple points of argon and oxygen between the 'National Institute of Standards -Egypt (NIS)' and 'Institut Nationale de Métrologie - France (LNE-Cnam).' The investigation was carried out through measurements of the argon and oxygen triple points (83.8058 K and 54.3584 K, respectively), as defining fixed points on the ITS-90 that are used in the calibration of capsule standard platinum resistance thermometers. The main objective of this work was to compare the realizations of both of the fixed-point cells and to establish the degree of equivalence between the two laboratories. As defined by the MRA, the degree of equivalence between two measurements (each consisting of a measured value $$m_{i}$$ and its uncertainty $$u_{i})$$ is expressed by the difference between the measured values, $$m_{1} - m_{2}$$ , and the expanded pair uncertainty of this difference $$U_\mathrm{p}$$ . Two cells, containing argon and oxygen, which had been fabricated and filled at LNE-Cnam, were used as artifacts exchanged between the two laboratories. The comparison measurements revealed temperature differences of 0.28 mK and 0.39 mK with expanded pair uncertainties of 0.66 mK and 0.74 mK for the argon and oxygen points, respectively. A detailed description of the equipment used in the two laboratories and an analysis of the comparison results will be presented in this paper. [ABSTRACT FROM AUTHOR]

Background: Pediatric mechanical ventilation practice guidelines are not well established; therefore, the European Society for Paediatric and Neonatal Intensive Care (ESPNIC) developed consensus recommendations on pediatric mechanical ventilation management in 2017. However, the guideline's applicability in different health care settings is unknown. This study aimed to determine the consensus on pediatric mechanical ventilation practices from Canadian respiratory therapists' (RTs) perspectives and consensually validate aspects of the ESPNIC guideline., Methods: A 3-round modified electronic Delphi survey was conducted; contents were guided by ESPNIC. Participants were RTs with at least 5 years of experience working in standalone pediatric ICUs or units with dedicated pediatric intensive care beds across Canada. Round 1 collected open-text feedback, and subsequent rounds gathered feedback using a 6-point Likert scale. Consensus was defined as ≥ 75% agreement; if consensus was unmet, statements were revised for re-ranking in the subsequent round., Results: Fifty-two RTs from 14 different pediatric facilities participated in at least one of the 3 rounds. Rounds 1, 2, and 3 had a response rate of 80%, 93%, and 96%, respectively. A total of 59 practice statements achieved consensus by the end of round 3, categorized into 10 sections: (1) noninvasive ventilation and high-flow oxygen therapy, (2) tidal volume and inspiratory pressures, (3) breathing frequency and inspiratory times, (4) PEEP and F IO 2 , (5) advanced modes of ventilation, (6) weaning, (7) physiological targets, (8) monitoring, (9) general, and (10) equipment adjuncts. Cumulative text feedback guided the formation of the clinical remarks to supplement these practice statements., Conclusions: This was the first study to survey RTs for their perspectives on the general practice of pediatric mechanical ventilation management in Canada, generally aligning with the ESPNIC guideline. These practice statements considered information from health organizations and institutes, supplemented with clinical remarks. Future studies are necessary to verify and understand these practices' effectiveness., Competing Interests: Ms Quach discloses relationships with the Canadian Lung Association and the Lung Health Foundation. The authors remaining authors have disclosed no conflicts of interest., (Copyright © 2022 by Daedalus Enterprises.)

Pollution from sewage discharge is one of the most critical environmental problems worldwide, e.g., in Brazil, where basic sanitation is still scarce. As pollution can affect biomes, especially estuaries where intensive ecological and human activities occur, has caused widespread concern. This work aimed to study the water quality of the Jundiaí/Potengi Estuary (JPE) in an area close to the discharge of treated and untreated wastewater for 18 months. Physicochemical and microbiological parameters were measured and integrated using the Water Quality Index of the Canadian Council of Ministers of the Environment. Ecotoxicological tests were performed with Brazilian endemic organisms to assess the impact of water pollution on biota. A generalized linear regression model was applied to understand the effects of water quality on ecotoxicological responses. Concentrations of metals, dissolved oxygen, total ammonia nitrogen, nitrate, and thermotolerant coliforms did not comply with Brazilian environmental regulations. A significant increase in the mortality rate of Mysidopsis juniae and Nitocra sp. and a significant decrease in the reproductive rate of Nitocra sp. indicated the most affected areas related to the discharge of treated and untreated wastewater. Only 10% of the samples from sites without direct wastewater impact showed a toxic response in at least one organism. Both water quality and sampling sites were statistical predictors of ecotoxicological response, describing not only the pollutant load but also the type of effluent. This study demonstrated the degradation of the environmental quality of the JPE, particularly due to the discharge of sanitary wastewater, and highlights the importance of protection and remediation measures to preserve this protected area., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Water quality plays an important role in estuarine habitats and affects aquatic organisms. The focus of this study was to understand the temporal-spatial variation of water quality and reveal the natural and anthropogenic drivers by using multiple analysis approaches. Herein, during 2012-2018, six water quality constituents (pH, electrical conductivity (EC), dissolved oxygen (DO), ammonia nitrogen (NH 3 N), total nitrogen (TN), and total phosphorus (TP) were examined for eight sites in the Yangtze Estuary, and the hydro-sediment data, i.e., discharge (Q) and sediment transport rate (STR), was collected from the upstream hydrological station Datong. The cluster analysis (CA), principal component analysis (PCA)/factor analysis (FA), Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI), and the Mann-Kendall (MK) test were applied. The eight sampling sites were geographically grouped into cluster I, cluster II, and cluster III based on the characteristics of water quality changes, which are under the influence of the upstream runoff, the anthropogenic activities, and seawater. The results are as follows: (1) NH 3 N, TN, and DO were key constituents representing the water quality of cluster I and cluster III, and those were EC, TN, and DO for cluster II; (2) The monthly-average Q and STR of Datong were negatively correlated to water quality constituents with seasonal variation except for pH; (3) The impact of anthropogenic activities on water quality was especially reflected in cluster III which is close to the Huangpu River Estuary; upstream runoff was the natural driver of water quality changes for cluster I while that was seawater for cluster II. Seawater acts a key role in affecting the water quality of cluster II situated at the North Branch. Revealing the key drivers of water quality change in the Yangtze Estuary provides a reference for water quality management., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Long-term oxygen therapy in COPD is usually supervised through home-care respiratory programs. Such programs often involve an intensive education intervention at the initiation of long-term oxygen therapy, followed by an extended follow-up period that aims toward home oxygen adherence. The objective of this study was to estimate the cost-effectiveness ratio of such a maintenance program., Methods: A simulation model was developed that compared 2 strategies after the intensive education intervention: (1) enrollment and (2) no enrollment in a maintenance program. The study population consisted of a hypothetical cohort of 200 patients (100 patients per group; mean age, 74 years; 45% men; mean FEV 1 of 43% predicted value; and mean resting P aO 2 w hile breathing air, 50 mm Hg). Effectiveness assumptions of the program were derived from a current literature review. The primary outcome was the ratio of the incremental cost of the program per quality-adjusted life-years gained. Only direct costs were considered; a health-care system perspective was adopted. Costs are reported in 2020 Canadian dollars (Can $)., Results: Over a 5-year period, an extended home-visit program may prevent 9 deaths and provide an additional 39 years of life and 24 quality-adjusted life-years. Compared with usual care (ie, no enrollment in the maintenance program), the incremental cost-effectiveness ratio was Can $17,197 per quality-adjusted life-years gained. Sensitivity analyses demonstrated the robustness of the model. Only a reduction in adherence of 25% per year would increase the incremental cost-effectiveness ratio per quality-adjusted life-years beyond the threshold of Can $50,000 that is usually considered as acceptable from a health-care system perspective., Conclusions: An extended home-visit program to maintain or improve adherence to long-term oxygen therapy in patients with COPD would most likely be cost-effective., Competing Interests: The authors have disclosed no conflicts of interest., (Copyright © 2022 by Daedalus Enterprises.)

BACKGROUND: The purpose of this study was to compare the ability of 3 portable oxygen concentrators (POCs) to maintain SpO2 ≥ 90% during exercise in patients with chronic lung disease. METHODS: Twenty-one subjects with chronic lung disease (18 with COPD, 3 with pulmonary fibrosis) and documented room air exertional SpO2 ≤ 85% performed four 6-min walk tests: a control walk using the subject’s current oxygen system and prescribed exertional flow rate, and 1 walk with each of the 3 POCs (Eclipse 3, EverGo, and iGo) at their maximum pulse-dose setting. RESULTS: SpO2 was significantly higher pre-walk and post-walk with the Eclipse 3, compared to the other POCs (all P < .01). The subjects also walked farther and maintained a mean SpO2 ≥ 90% with the Eclipse 3 (both P < .01), which delivers the largest oxygen bolus. The subjects indicated that they preferred the EverGo’s physical characteristics, but that the Eclipse 3 responded best to their breathing. The iGo was rated less favorably than Eclipse 3 or EverGo. CONCLUSIONS: The Eclipse 3 was best at meeting the subjects’ clinical needs. POC users should be appropriately tested during all activities of daily living, to ensure adequate oxygenation. The healthcare provider should provide information and help to direct the subject toward the most clinically appropriate oxygen system, while being mindful of the patient’s preferences and lifestyle. (Clinicaltrials.gov NCT01653730). [ABSTRACT FROM AUTHOR]

The first thorough examination of oxygen concentrations in Canadian waters of the Pacific Ocean reveals several patterns in space and time. Sub-surface concentrations of oxygen tend to be lower in shelf waters than in deep-sea waters on the same isopycnal and lower in southern waters of the continental shelf than farther north. The lowest near-bottom concentration was 0.7 ml L−1(31 μmol kg−1) in mid-shelf waters in summer off southwest Vancouver Island in the Juan de Fuca Eddy region. Oxygen concentration there declined at a rate of 0.019 ml L−1 y−1(0.83 μmol kg−1 y−1) from 1979 to 2011. This decline is attributed mainly to changes in oxygen concentrations on the same density surfaces, rather than to changes in the depth of constant-density surfaces. A numerical simulation of ocean currents and nutrient concentrations in and surrounding the Juan de Fuca Eddy in summer reveals persistent upwelling into the centre of this eddy and slow bottom currents within the eddy. Upwelled water at bottom of the Juan de Fuca Eddy has water properties associated with the California Undercurrent on the 26.6 sigma-t surface at 200 m depth, where oxygen concentration is typically 2.0 ml L−1(87 μmol kg−1) and declined at a rate of 0.025 ml L−1 y−1(1.1 μmol kg−1 y−1) from 1981 to 2011, mainly as a result of changes on constant-density surfaces rather than to uplifting isopycnals. We propose that upwelling advects deep, oxygen-poor water onto the continental shelf bottom, and the slow bottom currents allow time for oxidation of organic material in bottom waters to further reduce the oxygen concentration. RÉSUMÉ [Traduit par la rédaction] Le premier examen approfondi des concentrations d'oxygène dans les eaux canadiennes de l'océan Pacifique révèle plusieurs configurations dans le temps et dans l'espace. Les concentrations d'oxygène sous la surface ont tendance à être plus faibles dans les eaux de la plate-forme continentale que dans les eaux de l'océan profond sur la même isopycne et plus faibles dans les eaux du sud de la plate-forme que plus loin au nord. La concentration la plus faible près du fond était de 0.7 ml L−1(31 μmol kg−1) dans les eaux du milieu de la plate-forme en été au large du sud-ouest de l’île de Vancouver dans la région du remous de Juan de Fuca. Les concentrations en oxygène à cet endroit ont diminué au rythme de 0.019 ml L−1 a−1(0.83 μmol kg−1 a−1) entre 1979 et 2011. Cette diminution est principalement attribuée aux changements dans les concentrations d'oxygène sur les surfaces d’égale densité plutôt qu'aux changements dans la profondeur des surfaces de densité constante. Une simulation numérique des courants océaniques et des concentrations de nutrients dans le remous de Juan de Fuca et dans les régions avoisinantes en été révèle des remontées d'eau froide persistantes vers le centre de ce remous et des courants de fond lents à l'intérieur du remous. L'eau qui a remonté au fond du remous de Juan de Fuca a des propriétés liées au sous-courant de Californie sur la surface sigma–t 26.6 à une profondeur de 200 m, où la concentration en oxygène est normalement de 2.0 ml L−1(87 μmol kg−1), et a diminué au taux de 0.025 ml L−1 a−1(1.1 μmol kg−1 a−1) de 1981 à 2011, principalement à cause des changements sur les surfaces de densité constante plutôt que du soulèvement des isopycnes. Nous pausons l'hypothèse que les remontées d'eau advectent des eaux profondes pauvres en oxygène au bas de la plate-forme continentale et que les lents courants de fond donnent le temps à l'oxydation de la matière organique dans les eaux de fond, ce qui réduit davantage la concentration de l'oxygène. [ABSTRACT FROM AUTHOR]

Background: Severe COVID-19 appears to disproportionately affect people who are immunocompromised, although Canadian data in this context are limited. We sought to determine factors associated with severe COVID-19 outcomes among recipients of organ transplants across Canada., Methods: We performed a multicentre, prospective cohort study of all recipients of solid organ transplants from 9 transplant programs in Canada who received a diagnosis of COVID-19 from March 2020 to November 2021. Data were analyzed to determine risk factors for oxygen requirement and other metrics of disease severity. We compared outcomes by organ transplant type and examined changes in outcomes over time. We performed a multivariable analysis to determine variables associated with need for supplemental oxygen., Results: A total of 509 patients with solid organ transplants had confirmed COVID-19 during the study period. Risk factors associated with needing ( n = 190), compared with not needing ( n = 319), supplemental oxygen included age (median 62.6 yr, interquartile range [IQR] 52.5-69.5 yr v. median 55.5 yr, IQR 47.5-66.5; p < 0.001) and number of comorbidities (median 3, IQR 2-3 v. median 2, IQR 1-3; p < 0.001), as well as parameters associated with immunosuppression. Recipients of lung transplants ( n = 48) were more likely to have severe disease with a high mortality rate ( n = 15, 31.3%) compared with recipients of other organ transplants, including kidney ( n = 48, 14.8%), heart ( n = 1, 4.4%), liver ( n = 9, 11.4%) and kidney-pancreas ( n = 3, 12.0%) transplants ( p = 0.02). Protective factors against needing supplemental oxygen included having had a liver transplant and receiving azathioprine. Having had 2 doses of SARS-CoV-2 vaccine did not have an appreciable influence on oxygen requirement. Multivariable analysis showed that older age (odds ratio [OR] 1.04, 95% confidence interval [CI] 1.02-1.07) and number of comorbidities (OR 1.63, 95% CI 1.30-2.04), among other factors, were associated with the need for supplemental oxygen. Over time, disease severity did not decline significantly., Interpretation: Despite therapeutic advances and vaccination of recipients of solid organ transplants, evidence of increased severity of COVID-19, in particular among those with lung transplants, supports ongoing public health measures to protect these at-risk people, and early use of COVID-19 therapies for recipients of solid organ transplants., Competing Interests: Competing interests: Geneviève Huard reports payment from Gilead and AbbVie, and participation on a data safety monitoring board with Paladin. Ruth Sapir-Pichhadze reports grants from the Canadian Institutes of Health Research, Fonds de recherche du Québec, Genome Canada and Kidney Foundation of Canada, as well as speaker fees from the Korean Society of Nephrology. Atul Humar reports fees from Roche, Astellas and Merck. Deepali Kumar reports grants from Roche, GSK, Takeda, Qiagen, Amplyx and Atara Biotherapeutics, as well as fees from Roche, GSK, Takeda, Exevir, Astellas and Meducom. Deepali Kumar is the 2022–2023 president of the American Society of Transplantation. No other competing interests were declared., (© 2022 CMA Impact Inc. or its licensors.)

This study was conducted to evaluate the physical/mechanical characteristics of typical selected mining tasks and the energy expenditure required for their performance. The study comprised two phases designed to monitor and record the typical activities that miners perform and to measure the metabolic energy expenditure and thermal responses during the performance of these activities under a non-heat stress environmental condition (ambient air temperature of 25.8°C and 61% relative humidity with a wet bulb globe temperature (WBGT) of 22.0°C). Six common mining jobs were evaluated in 36 miners: (1) production drilling (jumbo drill) (n = 3), (2) production ore transportation (load-haul dump vehicle) (n = 4), (3) manual bolting (n = 9), (4) manual shotcrete (wet/dry) (n = 3), (5) general services (n = 8) and, (6) conventional mining (long-hole drill) (n = 9). The time/motion analysis involved the on-site monitoring, video recording, and mechanical characterization of the different jobs. During the second trial, continuous measurement of oxygen consumption was performed with a portable metabolic system. Core (ingestible capsule) and skin temperatures (dermal patches) were recorded continuously using a wireless integrated physiological monitoring system. We found that general services and manual bolting demonstrated the highest mean energy expenditure (331 ± 98 and 290 ± 95 W, respectively) as well as the highest peak work rates (513 and 529 W, respectively). In contrast, the lowest mean rate of energy expenditure was measured in conventional mining (221 ± 44 W) and manual shotcrete (187 ± 77 W) with a corresponding peak rate of 295 and 276 W, respectively. The low rate of energy expenditure recorded for manual shotcrete was paralleled by the lowest work to rest ratio (1.8:1). While we found that production drilling had a moderate rate of energy expenditure (271 ± 11 W), it was associated with the highest work to rest ratio (6.7:1) Despite the large inter-variability in energy expenditure and work intervals among jobs, only small differences in average core temperature (average ranged between 37.20 ± 0.22 to 37.42 ± 0.18°C) were measured. We found a high level of variability in the duration and intensity of tasks performed within each mining job. This was paralleled by a large variation in the work to rest allocation and mean energy expenditure over the course of the work shift. [ABSTRACT FROM PUBLISHER]

SUMMARY Issues related to equipment scale-up and process simulation are described for a thermochemical cycle driven by nuclear heat from Canada's proposed Generation IV reactor (Super-Critical Water-Cooled Reactor; SCWR), which is a CANDU derivative using supercritical water cooling. The copper-chlorine (Cu-Cl) cycle has been identified by Atomic Energy of Canada Limited as the most promising cycle for thermochemical hydrogen production with SCWR. Water is decomposed into hydrogen and oxygen through intermediate Cu-Cl compounds. This article outlines the challenges and design issues of hydrogen production with a Cu-Cl cycle coupled to Canada's nuclear reactors. The processes are simulated using the Aspen Plus process simulation code, allowing the cycle efficiency and possible efficiency improvements to be examined. The results are useful to assist the development of a lab-scale cycle demonstration, which is currently being undertaken at the University of Ontario Institute of Technology in collaboration with numerous partners. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Geochemical and isotopic monitoring allows determination of CO2 presence in the subsurface through the sampling of produced fluids and gases at production and/or monitoring wells. This is demonstrated by data from 22 months of monitoring at the Pembina Cardium CO2 Monitoring Pilot in central Alberta, Canada. Eight wells centered around two CO2 injectors were sampled monthly between February 2005 and February 2007. Stable isotope analyses of the samples revealed that changes in the δ13CCO2 values in produced gas as well as changes in the δ18O values of the produced fluids indicate CO2 presence and identify trapping mechanisms at select production wells. Using equilibrium isotope exchange relationships and CO2 solubility calculations, fluid and gas saturations in the pore space in excess of that occupied by oil were calculated. We demonstrate that stable isotope measurements on produced fluids and gases at the Pembina Cardium CO2 storage site can be used to determine both qualitatively and quantitatively the presence of CO2 around the observation well, given that the injected CO2 is isotopically distinct. [Copyright &y& Elsevier]

Abstract: This study investigates differences in the δ13Ccol, δ15N, δ13Csc, δ18Osc, Sr/Ca, and Ba/Ca values of juvenile and adult woolly mammoths (Mammuthus primigenius) from Old Crow, Yukon, Canada. The data indicate that nursing in woolly mammoths lasted at least three years, and was associated with minimal decreases in δ13Ccol (~0.2‰), large decreases in δ13Csc (~1.5‰), and large increases in δ15N (~2‰) and δ18Osc (~2‰) values. Sr/Ca and Ba/Ca ratios suggest that woolly mammoth juveniles began consuming plant foods between 2 and 3 “African Elephant Years” of age, much later than the initiation of weaning in modern elephants. We hypothesize that delayed weaning was an adaptation to increased predation risk and decreased food quality/quantity during the extended hours of darkness that occur in winter at high latitudes. Prolonged nursing and delayed weaning may have made mammoths particularly vulnerable to climatic stressors or human hunting. [ABSTRACT FROM AUTHOR]

Alberta oil-sands petroleum coke is an abundant byproduct of the upgrading of bitumen. The current study aims to improve the current understanding of sulfur added to the surface of petroleum coke through reaction with sulfur dioxide (SO2) and how this is affected by a large excess of oxygen (O2). Particular focus is given to the distribution and speciation of sulfur within the coke particles, as well as its thermal stability. Petroleum coke was activated in SO2with and without O2in a packed bed reactor at 600−800 °C. The activated cokes were characterized with electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Cross-sectional analysis with EPMA of activated coke particles revealed that sulfur-rich coke particles (i.e., SIAC) could be produced with and without O2. Under low SO2(3%), high O2(18%) conditions, however, O2competitively reacted with coke at 600 °C, and SO2only reacted to form a sulfur-rich layer after O2had been depleted. Analysis with XPS suggested that the sulfur-rich layer of the coke particles was made up of thiophene from the coke plus carbon−sulfur surface complexes, mainly heterocyclic sulfide and disulfide, while the presence of aliphatic sulfide, thiolactone, and thiol could not be ruled out. TGA and DSC analyses confirmed that sulfur added to activated coke via reaction with SO2was not elemental in nature. In both N2and air, sulfur added via high-temperature reaction with SO2is more thermally stable than that of a commercial SIAC sulfurized at lower temperatures. This may have beneficial implications if these SO2activated cokes were to be used to capture mercury, since they could be thermally regenerated with minimal loss of active sulfur surface sites while the captured mercury is collected, avoiding the costly and potentially problematic landfill disposal of Hg-containing activated carbon. [ABSTRACT FROM AUTHOR]

Abstract: Quahog parasite unknown (QPX) is a protistan microorganism associated with mass mortalities of hard clams (Mercenaria mercenaria) along the northeastern coasts of the United States and maritime Canada. Because several studies indicate modulatory effects of prevailing environmental parameters on disease outbreaks, this study tested the effect of major environmental parameters (temperature, salinity and oxygen concentration; individually or combined) on QPX survival in artificial seawater and parasite growth in culture media in vitro. Three QPX isolates from two different geographic locations were compared. Results indicated that in vitro growth of QPX was optimal in standard culture medium at 34ppt between 20°C and 23°C. Additionally, significant differences in temperature optima were observed for geographically distinct QPX isolates (p <0.001) confirming previous studies suggesting the existence of different QPX strains (or ecotypes). When tested in seawater, QPX exhibited opposite trends with higher survival at 15°C and 15ppt. Results also demonstrated limited survival and growth of QPX under anoxic conditions. Additionally, results showed that the parasite is able to survive extreme temperatures (−12°C to 32°C) suggesting that QPX could overcome short periods of extreme conditions in the field. These results contribute to a better understanding of interactions between QPX and its environment, but potential impacts of environmental conditions on QPX disease development need further work as it also involves clam response to these factors. [Copyright &y& Elsevier]

Assemblages of subfossil Chaoboridae mandibles from 80 thermally-stratified shield lakes in southern central Canada were examined to explore the influence of subfossil Chaoborus on subfossil Chironomidae-based paleolimnological inference models of deepwater oxygen, as volume-weighted hypolimnetic oxygen (VWHO). Inclusion of subfossil Chaoborus in subfossil Chironomidae-based VWHO models only improved model performance modestly, however it produced substantively better inferences of hypolimnetic oxygen in anoxic lakes, because Chaoborus had a much stronger positive relationship with low VWHO compared to chironomid taxa indicative of anoxic conditions, such as Chironomus. A Chaoborus mandible:Chironomidae head capsule ratio (chaob:chir) may be a useful index in paleolimnological studies, as chaob:chir in a surface sediment training set was significantly related to VWHO, and displayed little co-variation with other limnological variables such as trophic status (e.g. TP, TN) or lake depth (e.g. Zmax). Chaob:chir values in a stratigraphic analysis tracked chironomid-inferred VWHO, however the use of chaob:chir in regional ‘top–bottom’ paleolimnological studies must be used with caution. [ABSTRACT FROM AUTHOR]

Northern ectotherms must seek refuge from winter conditions for a large portion of their annual activity cycle. The objective of this study was to quantify physical properties of overwintering sites selected by wood turtles (Glyptemys insculpta (LaConte, 1830)) at the species’ northern range limit. We mapped all structural features (e.g., root balls and log jams), water depth, and sediment types along a 1.5 km stretch of river that was available to turtles outfitted with radio transmitters (N = 8) during winter. Temperature selection was assessed by comparing thermal profiles from data loggers on turtles and temperature stations within the river and other riparian habitats (e.g., ephemeral pools and oxbows). Dissolved oxygen (DO) was measured at each temperature station and turtle location. Wood turtles overwintered in the river, which was colder (~0 °C), had more stable temperatures, and provided higher DO (12.64 ppm) compared with adjacent habitats. Some turtles selected structured refuges for overwintering. Winter movements were not related to temperature or DO, but may be related to maintaining a certain distance from shore and water depth to protect against accidental relocations during winter. We discuss hibernacula as potential factors limiting the northern distribution of wood turtles, a species at risk in Canada. Les ectothermes nordiques doivent trouver un refuge contre les conditions hivernales durant une partie importante de leur cycle annuel d’activités. L’objectif de notre étude est de mesurer les propriétés physiques des sites d’hivernage choisis par les tortues des bois (Glyptemys insculpta (LeConte, 1830)) à la limite boréale de la répartition de l’espèce. Nous avons cartographié tous les éléments structuraux (par ex., boules de racines et embâcles), la profondeur de l’eau et les types de sédiments sur une section de 1,5 km de rivière disponible à des tortues (N = 8) porteuses de radiotransmetteurs pendant l’hiver. La sélection de la température a été évaluée en comparant les profils de températures sur les enregistreuses fixées aux tortues et ceux des stations d’enregistrement dans la rivière et dans les autres habitats de la rive (par ex., les étangs temporaires et les bras morts). Nous avons mesuré l’oxygène dissous (DO) à chaque station d’enregistrement thermique et à chaque emplacement habité par une tortue. Les tortues des bois passent l’hiver dans la rivière qui présente des températures plus froides (~0 °C), mais plus stables et des concentrations de DO plus grandes (12,64 ppm) que les habitats adjacents. Quelques tortues ont choisi des refuges dans des structures pour passer l’hiver. Les déplacements en hiver ne sont pas reliés à la température, ni à la concentration de DO, mais s’expliquent peut-être par le besoin de maintenir une certaine distance de la berge et une certaine profondeur d’eau afin d’éviter les déplacements accidentels pendant l’hiver. Nous discutons des hibernacles comme facteurs potentiels qui peuvent limiter la répartition vers le nord de la tortue des bois, une espèce à risque au Canada. [ABSTRACT FROM AUTHOR]

Denitrification and oxygen dynamics were investigated in the sea ice of Franklin Bay (70°N), Canada. These investigations were complemented with measurements of denitrification rates in sea ice from different parts of the Arctic (69°N–85°N). Potential for bacterial denitrification activity (5–194 μmol N m−2 day−1) and anammox activity (3–5 μmol N m−2 day−1) in melt water from both first-year and multi-year sea ice was found. These values correspond to 27 and 7%, respectively, of the benthic denitrification and anammox activities in Arctic sediments. Although we report only potential denitrification and anammox rates, we present several indications that active denitrification in sea ice may occur in Franklin Bay (and elsewhere): (1) despite sea ice-algal primary production in the lower sea ice layers, heterotrophic activity resulted in net oxygen consumption in the sea ice of 1–3 μmol l−1 sea ice per day at in situ light conditions, suggesting that O2 depletion may occur prior to the spring bloom. (2) The ample organic carbon (DOC) and NO3 − present in sea ice may support an active denitrification population. (3) Measurements of O2 conditions in melted sea ice cores showed very low bulk concentrations, and in some cases anoxic conditions prevailed. (4) Laboratory studies using planar optodes for measuring the high-resolution two-dimensional O2 distributions in sea ice confirmed the very dynamic and heterogeneous O2 distribution in sea ice, displaying a mosaic of microsites of high and low O2 concentrations. Brine enclosures and channels were strongly O2 depleted in actively melting sea ice, and anoxic conditions in parts of the brine system would favour anaerobic processes. [ABSTRACT FROM AUTHOR]

A 13-item survey of dentists' views about approaches to pain and anxiety management was distributed in Atlantic Canada. Respondents indicated that about 50% had training in conscious-sedation techniques and 20% had learned to administer intravenous (IV) sedation. Sixty-nine percent of those responding had used oral sedatives to help manage fearful patients. Forty-six percent had referred anxious adult patients to specialists or other dentists, and 78% had made similar referrals for anxious children. Seventeen percent reported using conscious sedation, but they typically treated more than 20 anxious patients per year. Most (80%) believed that nitrous oxide and oxygen (N2O/O2) conscious sedation should be included in the treatments that a licensed practitioner can provide, and they were evenly divided in their opinion about the need for a separate licence for its use. However, only half of respondents believed that IV sedation should be included among a general practitioner's treatment options, and over 70% said that this treatment should be subject to a separate licence. The implications of these findings for curriculum are discussed. [ABSTRACT FROM AUTHOR]

A growing awareness of the difference between the supply and demand for fish products is fueling rapid growth of an aquaculture industry in Canada, including a freshwater sector, based mainly on the cage farming of rainbow trout. Cage farms can release relatively large loads of organic matter and nutrients to the environment. In consequence, federal and provincial resource management agencies need to develop regulatory instruments that will foster the growth of the industry while ensuring minimal water quality impacts. Such instruments should be science based, but there are currently key gaps in our understanding of the water quality implications of the operations of freshwater cage aquaculture. Here I review the state of science of the water quality implications of cage aquaculture and identify 11 knowledge gaps that currently hamper the development of sound, science-based cage culture management instruments. Perhaps the most important finding of the review is the recognition that, while aquaculture has produced significant increases in lakewater total phosphorus (TP) levels in some situations, classic phosphorus mass balance models may substantially overestimate the contributions of cage farms to TP concentrations in some lakes. Research on this, and perhaps the other knowledge gaps identified in this review, should aid the development of sound management instruments for freshwater cage aquaculture in Canada and elsewhere. [ABSTRACT FROM AUTHOR]

The Musselwhite Mine in Canada processes a free milling gold ore at 5.5-5.8g/t Au and 4.2% pyrrhotite. A laboratory investigation was conducted to improve cyanidation. The pyrrhotite was determined to be 50% monoclinic and 50% hexagonal. A leach using 8ppm dissolved oxygen yielded only 82.3% gold extraction with a 0.29kg/t NaCN consumed. The addition of lead nitrate, directly to the leach, showed 94.2% gold extraction with only 0.16kg/t NaCN consumption. A gold extraction of 95.0% was obtained by adding oxygen with lead nitrate. The laboratory results were found to be similar to current plant practice. Plant data indicated that the enhancement of leaching kinetics has resulted in a 0.61% increase of gold recovery, from 95.20% in 1999 to 95.81% in 2000. Benefits of the oxygen system were more pronounced in the hot summer months when higher slurry temperatures depleted dissolved oxygen content and pyrrhotite is more reactive. Other modifications include the installation of cone spargers. The results of July 2000 versus those of July 1999 displayed a 2.0% improvement in recovery with the use of oxygen (i.e. a reduction of 0.08g/t Au in the leach residue). In 2000, the improvement of gold recovery represented an additional gross revenue of $CDN0.5 Million (€ 0.304 Million). Cyanide consumption decreased slightly by approximately 8%. [ABSTRACT FROM AUTHOR]

1. Subfossil chironomid head capsules were sampled from surficial sediments from 86 boreal shield lakes in south-central Ontario, Canada. Lake characteristics ranged from shallow to very deep (> 80 m), ultraoligotrophic to mesotrophic, and with end-of-summer hypolimnetic oxygen conditions ranging from near-saturation to anoxic. 2. Subfossil chironomid assemblages, comprising 44 taxa from 59 lakes, were analysed using multivariate ordination techniques such as redundancy analysis (RDA) and canonical correspondence analysis (CCA). Forward selection in RDA and CCA both showed that measures of oxygen, such as end-of-summer volume-weighted hypolimnetic oxygen concentration (VWHO) and bottom oxygen concentration (botO2), were the strongest explanatory variables for the chironomid data. Maximum depth and major ion chemistry were also important explanatory variables. 3. Oxygen inference models were developed using partial-least-squares regression (PLS), weighted-averaging partial-least-squares regression (WA-PLS), and weighted averaging regression (WA). Models were developed using both the full 44 taxa assemblage (which included littoral taxa) and using only 15 profundal-type taxa. 4. Cross-validated models (jackknifing) using full-assemblage or profundal-only taxa had similar statistical power (similar root mean squared error of prediction, RMSEP). The best models had moderate predictive power, with an r2jack as high as 0.56, and an RMSEP as low as 2.15 mg L–1 for [VWHO], and an r2jack of 0.49 and an RMSEP of 0.24 for log([botO2] + 1). 5. Reconstruction of [VWHO] and [botO2] using a previously published chironomid profile that showed strong lake response to land-clearance and logging suggests that oxygen inference models are reliable and accurate, reflecting the qualitative changes occurring in subfossil assemblages. However, the profundal-only models may be misleading in... [ABSTRACT FROM AUTHOR]

Despite the growing importance of oxygen-delivery devices worldwide, there are only a few reports of physiological data on various oxygen masks in children. The possibility of carbon dioxide (CO 2 ) rebreathing has been a prevalent concern with the use of oxygen-delivery devices. OxyMask Kid TM (Southmedic Inc. Canada; hereafter OxyMask) is expected to reduce CO 2 rebreathing even at low oxygen flow rates because of its structural features. Biological data using OxyMask in children have not been well investigated. Measured respiratory parameters of OxyMask with those of a simple oxygen mask in healthy children were compared. Ten subjects were enrolled, with a median age of 5.4 years. All subjects used both OxyMask and a simple oxygen mask. The fraction of inspiratory oxygen (F I O 2 ), partial pressure of inspiratory CO 2 (P I CO 2 ), and partial pressure of end-tidal CO 2 were measured using a sidestream gas-sampling monitor in all subjects. The oxygen flow rate was set at 1, 3, 5, and 10 L/min. F I O 2 levels were higher with OxyMask than those with the simple oxygen mask at 3 L/min of oxygen. P I CO 2 levels were significantly lower with OxyMask than those with the simple oxygen mask (1.5 mmHg vs. 3.7 mmHg at 1 L/min, P = 0.005; 1.0 mmHg vs. 2.7 mmHg at 3 L/min, P = 0.005, respectively), whereas P I CO 2 levels were higher at low oxygen flow rates with both masks.Conclusion: Our results showed that higher F I O 2 and less CO 2 rebreathing were achieved with OxyMask than those with a simple oxygen mask at low flow rates of oxygen in healthy children. What is Known: • OxyMask is expected to reduce carbon dioxide rebreathing even at low oxygen flow rates because of its structural features. • Efficacy has been demonstrated in experimental models and adult data, but clinical data on the use of the OxyMask in children are limited. What is New: • Higher fraction of inspiratory oxygen and lesser carbon dioxide rebreathing were achieved with OxyMask than with a simple oxygen mask at low flow rates of oxygen in healthy children., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Estimates the temperatures from quartz-Al[sub2]SiO[sub5] pairs from oxygen isotope fractionation of the Mica Greek area, British Columbia. Information on oxygen isotope thermometry; Application of the fast grain boundary diffusion model; Discussion on quartz-kyanite nodules.