Introduction: Transcutaneous cardiac pacing (TCP) is recommended for the treatment of symptomatic bradycardia, a life-threatening condition. Although TCP is taught in ACLS (advanced cardiac life support) courses, it is a difficult skill to master for junior residents. The main objective of this study is to measure the impact of having access to a checklist on successful TCP implementation. Our hypothesis was that the availability of a CL would improve performance of junior residents in the management of symptomatic bradycardia by facilitating TCP. Methods: We conducted a prospective, randomized, single-site study. First-year residents entering postgraduate programs and taking a mandatory ACLS course were enrolled. Students had didactic sessions on the management of symptomatic bradycardia followed by hands-on teaching on a low-fidelity manikin (ALS® simulator, Laerdal) using a CL conceived for this project as a teaching tool. Study participants were then assessed with a simulation scenario requiring TCP. Participants were randomly assigned to groups with and without CL accessibility. Performances were graded on six critical tasks. The primary outcome was the successful use of TCP, defined as having completed all tasks. Participants then completed a post-test questionnaire. Sample size estimation was based on a previous project (Ranger et al., 2018). Accepting an alpha error of 0.05 and a power of 80%, 45 participants in each group would permit the detection of 26.5% in performance gain. Results: Of 250 residents completing the ACLS course in 2017, 85 voluntary participants were randomized to a control group (no CL available during testing, n = 42) or an experimental group (CL available during testing, n = 43). Six participants in the experimental group adequately used TCP compared to five participants in the control group (p = 0.81, chi-squared test). Out of the 43 participants who had access to the CL, only 2 (5%) used it. Reasons why the CL was infrequently used were stated as the following: 24 participants (56%) mentioned not realizing it was available, 8 (19%) considered it was of little to no utility and 5 (19%) forgot a CL existed. Conclusion: Availability of a checklist previously used during simulation teaching did not increase junior residents’ capacity to correctly apply TCP. Non-recognition of CL availability and decreased perceived need for it were the main reasons for marginal use. Our results suggest that there are many limiting factors to CL effectiveness.

Introduction: Individualizing risk for stroke following a transient ischemic attack (TIA) is a topic of intense research, as existing scores are context-dependent or have not been well validated. The Canadian TIA Score stratifies risk of subsequent stroke into low, moderate and high risk. Our objective was to prospectively validate the Canadian TIA Score in a new cohort of emergency department (ED) patients. Methods: We conducted a prospective cohort study in 14 Canadian EDs over 4 years. We enrolled consecutive adult patients with an ED visit for TIA or nondisabling stroke. Treating physicians recorded standardized clinical variables onto data collection forms. Given the ability of prompt emergency carotid endarterectomy (CEA) to prevent stroke (NNT = 3) in high risk patients, our primary outcome was the composite of subsequent stroke or CEA ≤7 days. We conducted telephone follow-up using the validated Questionnaire for Verifying Stroke Free Status at 7 and 90 days. Outcomes were adjudicated by panels of 3 local stroke experts, blinded to the index ED data collection form. Based on prior work, we estimated a sample size of 5,004 patients including 93 subsequent strokes, would yield 95% confidence bands of +/− 10% for sensitivity and likelihood ratio (LR). Our analyses assessed interval LRs (iLR) with 95% CIs. Results: We prospectively enrolled 7,569 patients with mean 68.4 +/−14.7 years and 52.4% female, of whom 107 (1.4%) had a subsequent stroke and 74 (1.0%) CEA ≤7 days (total outcomes = 181). We enrolled 81.2% of eligible patients; missed patients were similar to enrolled. The Canadian TIA Score stratified the stroke/CEA ≤7days risk as: Low (probability <0.2%, iLR 0.20 [95%CI 0.091-0.44]; Moderate (probability 1.3%, iLR 0.79 [0.68-0.92]; High (probability 2.6%, iLR 2.2 [1.9-2.6]. Sensitivity analysis for just stroke ≤7 days yielded similar results: Low iLR 0.17 [95%CI 0.056-0.52], Medium iLR 0.89 [0.75-1.1], High iLR 2.0 [1.6-2.4]. Conclusion: The Canadian TIA Score accurately identifies TIA patients risk for stroke/CEA ≤7 days. Patients classified as low risk can be safely discharged following a careful ED assessment with elective follow-up. Patients at moderate risk can undergo additional testing in the ED, have antithrombotic therapy optimized, and be offered early stroke specialist follow-up. Patients at high risk should in most cases be fully investigated and managed ideally in consultation with a stroke specialist during their index ED visit.

Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88) presented a critique of our recently published paper in Cell Reports entitled ‘Large-Scale Cognitive GWAS Meta-Analysis Reveals Tissue-Specific Neural Expression and Potential Nootropic Drug Targets’ (Lam et al., Cell Reports, Vol. 21, 2017, 2597–2613). Specifically, Hill offered several interrelated comments suggesting potential problems with our use of a new analytic method called Multi-Trait Analysis of GWAS (MTAG) (Turley et al., Nature Genetics, Vol. 50, 2018, 229–237). In this brief article, we respond to each of these concerns. Using empirical data, we conclude that our MTAG results do not suffer from ‘inflation in the FDR [false discovery rate]’, as suggested by Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88), and are not ‘more relevant to the genetic contributions to education than they are to the genetic contributions to intelligence’.

A significant portion of ruminant production in the tropics relies on the grazing of native grasses growing in acid, low-fertility soils. Under these conditions, animal production is generally limited by the low quality and availability of forage supply. The introduction of forage legumes into grazing systems is commonly accepted as a way to alleviate this problem. However, many of the tropical forage legumes adapted to acid soils and selected on the basis of good agronomic performance have limited feeding value. This could be associated with increased production of secondary metabolites such as condensed tannins (CT), which have the ability to bind and precipitate proteins, carbohydrates and other molecules (Mueller-Harvey and McAllan, 1992). High intake of CT by ruminants has been associated with depressed intake and reduced digestibilities of protein and cell wall of temperate (Barry and Duncan, 1984; Pritchard et al, 1988) and tropical (Carulla, 1994) forage legumes. However, more recent work showed that intake and digestibility of tropical legumes was not only influenced by CT concentration but also by cell wall content (Barahona et al, 1997). In the ongoing process of identifying legume germplasm for acid soils, the use of in vitro techniques has been of great benefit. Gas production methods have considerable appeal in this respect due to their ability to evaluate digestion kinetics and their potential to simulate digestion processes in the rumen. Pendong et al. (1996) using temperate forages, showed that the pressure transducer gas technique of Theodorou et al. (1994) could be used to assess digestible organic matter disappearance as well as fermentation kinetics. A similar assessment was undertaken in the current study in which the tannin contents and cell-wall characteristics of tanniniferous legumes from Colombia were determined and related using measurements made in laboratories in Colombia and the United Kingdom.

The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

Rapid weight gain in infancy and low levels of n-3 long chain polyunsaturated fatty acids (LCPUFA) at birth are associated with increased adiposity later in life. The association between placental LCPUFA delivery and weight gain in infancy is poorly understood. We sought to determine the relationships between maternal phenotype, placental fatty acid transporter expression and offspring growth patterns over the first 6 months. Placental tissue and cord blood were collected at term delivery from women with uncomplicated pregnancies. Offspring body composition measurements were recorded 1 day and 6 months after birth. Body mass index (BMI) z-scores were determined using World Health Organization 2006 reference data. Body phenotype patterns were compared among offspring who had an increase in BMI z-score and those who had a decrease. High skinfold thickness at birth and positive change in BMI z-scores during infancy were associated with low neonatal n-3 LCPUFA plasma levels (r=−0.46, P=0.046) and high saturated fatty acids levels (r=0.49, P=0.034). Growth of skinfolds over 6 months of age was associated with placental fatty acid transporter gene expression. Change in BMI z-score in the first 6 months of life correlated with arm muscle area growth, a measure of lean mass (r=0.62, P=0.003), but not with growth in skinfold thickness. Early infancy weight gain was associated with poor plasma LCPUFA status at birth, and fat deposition in infancy was related to changes in placental lipid handling. Thus, neonatal fatty acid profiles may influence the trajectory of infant growth and fat and lean mass deposition.

The small-scale variability of physical properties and structural characteristics of multiple pairs of fast-ice cores obtained during the austral summer of 1991-92 at two Antarctic sites, McMurdo Sound (MCM) and Pine Island Bay (PIB), are examined and discussed with respect to the growth and decay of the sea ice. The ice at the MCM site was thicker than that at the PIB site and was covered by a somewhat thinner snowpack. While mean salinity and temperature of the ice at the two sites were similar, small-scale variations in both salinity and temperature were greater at PIB than at MCM. The ice sheet at MCM was a two-layer medium consisting of congelation ice overlying platelet ice. The ice from the PIB site, however, was composed of mainly frazil ice and layers of congelation ice with occasional thin layers of snow-ice at the surface of the cores. Crystal sub-structure measurements, c-axis orientation and brine-layer spacing from the MCM cores revealed that the congelation ice had moderately aligned, horizontally oriented c axes, suggesting that east-west currents off the southwest tip of Hut Point Peninsula control crystal-growth orientation.d others: Variability of physical and structural characteristics of Antarctic fast ice

The depth, density, load and isotopic (δ18O) composition of the snow cover on pack-ice floes were measured in late austral summer 1992 in the eastern Ross, Amundsen and western Bellingshausen Seas. Snow-density values commonly exceeded 350 kg m-3 and some were as high as 500 kg m-3. The densification of the snow occurs quickly and is attributed to a windy environment. The high density and sometimes considerable depth of the snow on the floes accounts for loads of as much as 700 kg m-2 and resultant sea-water flooding of the underlying sea ice. Lower mean δ18O values in the Ross/Amundsen Seas snow cover suggest that the region might have a cooler climate than the Bellingshausen Sea region. Snow depths on floes in the Bellingshausen Sea region were lower than those in the Ross/Amundsen Seas region, because the Bellingshausen Sea floes were first-year ice. Possible annual units in the isotope profiles of snow, as much as 2m deep, indicate that floes in the Ross/Amundsen Seas region were 2-3 years old.

Ice cores were obtained in January 1990 from the land-fast ice in McMurdo Sound for a study of variations in texture, fabric, sub-structure, composition and development. Two primary ice types were observed, congelation and platelet, with a minor amount of frazil ice. Congelation ice growth precedes platelet-ice accretion. Congelation-ice fabrics show frequent moderate to strong alignments, a phenomenon believed to be due to water-current control of selective ice-crystal growth. Platelet ice originates at the base of the congelation ice, initially as a porous latticework of tabular ice crystals which subsequently consolidate by congelation of the interstitial water. Interstitial congelation-ice fabrics generally have little or no alignment, indicating the reduced effect of currents within the platelet latticework prior to solidification. Platelet-crystal textures range from small, wavy-edged forms to large, blade-like forms. Platelet-crystal fabrics indicate that, in addition to being randomly oriented, the platelet latticeworks commonly include many crystals with their flat (0001) faces oriented both parallel and normal to the base of the overlying ice. Plate-width data suggest that the interstitial congelation ice-growth rates remain similar to those of the overlying congelation ice. This effective increase in growth rates probably happens because the latticework of accumulating platelets ahead of the freezing interface ensures that the water within the platelet layer is at the freezing point and less heat has to be removed from platelet-rich water than from platelet-free water for a given thickness of congelation ice to grow. The negative oceanic heat flux associated with platelet-ice formation in McMurdo Sound explains why McMurdo Sound fast ice is thicker than Ross Sea pack ice, and also why it reaches a greater thickness than Arctic fast ice grown in a similar polar marine climate. Plate widths in the McMurdo Sound congelation ice suggest, however, that it grows no faster than Arctic congelation ice.

Sixty-three ice cores were collected in the Bellingshausen and Amundsen Seas in August and September 1993 during a cruise of the R.V. Nathaniel B. Palmer. The structure and stable-isotopic composition (18O/16O) of the cores were investigated in order to understand the growth conditions and to identify the key growth processes, particularly the contribution of snow to sea-ice formation. The structure and isotopic composition of a set of 12 cores that was collected for the same purpose in the Bellingshausen Sea in March 1992 are reassessed. Frazil ice and congelation ice contribute 44% and 26%, respectively, to the composition of both the winter and summer ice-core sets, evidence that the relatively calm conditions that favour congelation-ice formation are neither as common nor as prolonged as the more turbulent conditions that favour frazil-ice growth and pancake-ice formation. Both frazil- and congelation-ice layers have an av erage thickness of 0.12 m in winter, evidence that congelation ice and pancake ice thicken primarily by dynamic processes. The thermodynamic development of the ice cover relies heavily on the formation of snow ice at the surface of floes after sea water has flooded the snow cover. Snow-ice layers have a mean thickness of 0.20 and 0.28 m in the winter and summer cores, respectively, and the contribution of snow ice to the winter (24%) and summer (16%) core sets exceeds most quantities that have been reported previously in other Antarctic pack-ice zones. The thickness and quantity of snow ice may be due to a combination of high snow-accumulation rates and snow loads, environmental conditions that favour a warm ice cover in which brine convection between the bottom and top of the ice introduces sea water to the snow/ice interface, and bottom melting losses being compensated by snow-ice formation. Layers of superimposed ice at the top of each of the summer cores make up 4.6% of the ice that was examined and they increase by a factor of 3 the quantity of snow entrained in the ice. The accumulation of superimposed ice is evidence that melting in the snow cover on Antarctic sea-ice floes ran reach an advanced stage and contribute a significant amount of snow to the total ice mass.

Because individuals develop dementia as a manifestation of neurodegenerative or neurovascular disorder, there is a need to develop reliable approaches to their identification. We are undertaking an observational study (Ontario Neurodegenerative Disease Research Initiative [ONDRI]) that includes genomics, neuroimaging, and assessments of cognition as well as language, speech, gait, retinal imaging, and eye tracking. Disorders studied include Alzheimer’s disease, amyotrophic lateral sclerosis, frontotemporal dementia, Parkinson’s disease, and vascular cognitive impairment. Data from ONDRI will be collected into the Brain-CODE database to facilitate correlative analysis. ONDRI will provide a repertoire of endophenotyped individuals that will be a unique, publicly available resource.