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ObjectivesThere is elevated unease regarding how repetitive head impacts, such as those associated with soccer heading, contribute to alterations in brain function. This study examined the extent heart rate variability (HRV) and cardiac baroreceptor sensitivity (BRS) metrics are altered immediately following an acute bout of soccer heading.MethodsSeven male elite soccer players (24.1 ± 1.5 years) completed 40 successful soccer headers in 20-min. The headers were performed under controlled circumstances using a soccer ball launcher located 25 meters away and using an initial ball velocity of 77.5 ± 3.7 km/h (heading condition). An accelerometer (xPatch) on the right mastoid process quantified linear/rotational head accelerations. Participants also completed sham (body contact) and control (non-contact) sessions. A three-lead ECG and finger photoplethysmography characterized short-term spontaneous HRV/cardiac BRS, before and after each condition. The SCAT3 indexed symptom scores pre-post exposures to all three conditions.ResultsDuring the heading condition, cumulative linear and rotational accelerations experienced were 1,574 ± 97.9 g and 313,761 ± 23,966 rad/s2, respectively. Heart rate trended toward an increase from pre- to post-heading (p = 0.063), however HRV metrics in the time-domain (ps > 0.260) and frequency-domain (ps > 0.327) as well as cardiac BRS (ps > 0.144) were not significantly changed following all three conditions. Following the heading condition, SCAT3 symptom severity increased (p = 0.030) with a trend for symptom score augmentation (p = 0.078) compared to control and sham.ConclusionWhereas, symptoms as measured by the SCAT3 were induced following an acute bout of controlled soccer heading, these preliminary findings indicate they were not accompanied by alterations to autonomic function. Ultimately, this demonstrates further research is needed to understand the physiological underpinnings of alterations in brain function occurring immediately after a bout of soccer heading and how these may, over time, contribute to long-term neurological impairments.

Dedicated long-term monitoring at appropriate spatial and temporal scales is necessary to understand biodiversity losses and develop effective conservation plans. Wildlife monitoring is often achieved by obtaining data at a combination of spatial scales, ranging from local to broad, to understand the status, trends, and drivers of individual species or whole communities and their dynamics. However, limited resources for monitoring necessitates tradeoffs in the scope and scale of data collection. Careful consideration of the spatial and temporal allocation of finite sampling effort is crucial for monitoring programs that span multiple spatial scales. Here we evaluate the ability of five monitoring designs-stratified random, weighted effort, indicator unit, rotating panel, and split panel-to recover parameter values that describe the status (occupancy), trends (change in occupancy), and drivers (spatially varying covariate and an autologistic term) of wildlife communities at two spatial scales. Using an amphibian monitoring program that spans a network of US national parks as a motivating example, we conducted a simulation study for a regional community occupancy sampling program to compare the monitoring designs across varying levels of sampling effort (ranging from 10% to 50%). We found that the stratified random design outperformed the other designs for most parameters of interest at both scales and was thus generally preferable in balancing the estimation of status, trends, and drivers across scales. However, we found that other designs had improved performance in specific situations. For example, the rotating panel design performed best at estimating spatial drivers at a regional level. Thus, our results highlight the nuanced scenarios in which various design strategies may be preferred and offer guidance as to how managers can balance common tradeoffs in large-scale and long-term monitoring programs in terms of the specific knowledge gained. Monitoring designs that improve accuracy in parameter estimates are needed to guide conservation policy and management decisions in the face of broad-scale environmental challenges, but the preferred design is sensitive to the specific objectives of a monitoring program.

Habitat fragmentation can alter species distributions and lead to reduced diversity at multiple scales. Yet, the literature describing fragmentation effects on biodiversity patterns is contradictory, possibly because most studies fail to integrate spatial scale into experimental designs and statistical analyses. Thus, it is difficult to extrapolate the effects of fragmentation to large-scaled systems in which conservation management is of immediate importance. To examine the influence of fragmentation on biodiversity across scales, we (1) estimated the effects of habitat area, connectivity, and quality at both local (i.e. community) and regional (i.e. metacommunity) scales; and (2) evaluated the direction, magnitude, and precision of these estimates at both spatial scales. We developed a multi-region community occupancy model to analyze 13 years (2005–2017) of amphibian monitoring data within the National Capital Region, a network of U.S. National Parks. Overall, we found a positive effect of park size and a negative effect of isolation on species richness at the park-level (i.e. metacommunity), and generally positive effects of wetland area, connectivity, and quality on species richness at the wetland-level (i.e. community), although parameter estimates varied among species. Covariate effects were less precise, but effect sizes were larger, at the local wetland-level as compared to the park-level scale. Our analysis reveals how scale can mediate interpretation of results from scientific studies, which might help explain conflicting narratives concerning the impacts of fragmentation in the literature. Our hierarchical framework can help managers and policymakers elucidate the relevant spatial scale(s) to target conservation efforts.

There is growing concern repetitive head contacts sustained by soccer players may lead to long-term health ramifications. Therefore, this preliminary investigation examined the impact an acute soccer heading bout has on dynamic cerebral autoregulation (dCA) metrics.In this preliminary investigation, 40 successful soccer headers were performed in 20 min by 7 male elite soccer players (24.1 ± 1.5 years). Soccer balls were launched at 77.5 ± 3.7 km/h from JUGS soccer machine, located 35 m away from participants. Linear and rotational head accelerations impacts were measured using an accelerometer (xPatch). The SCAT3 indexed concussion symptom score and severity before and after: soccer headers, sham (body contact only), and control conditions. Squat-stand maneuvers were performed at 0.05 Hz and 0.10 Hz to quantity dCA through measures of coherence, phase, and gain.Cumulative linear and rotational accelerations during soccer headers were 1574 ± 97.9 g and 313,761 ± 23,966 rads/sThese preliminary results indicate an acute bout of soccer heading resulted in alterations to dCA metrics. Therefore, future research with larger sample sizes is warranted to fully comprehend short- and long-term physiological changes related to soccer heading.

The fast intensification of agriculture affects many systems. In recent decades, traditional vineyards have been rapidly converted to trellis vineyards in Spain (the country with the largest vineyard surface worldwide) in an attempt to reduce harvesting costs and increase vine productivity. The implications of this modernization of vineyards on farmland biodiversity are still largely unknown. We studied 52 vineyards (26 traditional and 26 trellis) from June to September in south-western Spain, aiming to describe the effect of the modernization of goblet-shape traditional vineyards on vine structure and their management, as well as its effect on species' occurrence in vineyard plots. We applied hierarchical occurrence models to assess the occurrence probability of 10 bird species and two mammal species in traditional and trellis vineyard plots. Vineyard modernization involved taller vines (connected by metallic guide wires and poles by rows), greater distance between vine rows, bigger plot sizes, the systematic implementation of irrigation, and an application of fertilizers through the watering system (fertirrigation) in a third of studied vineyards. Other agrochemical treatments seemed to be equally used in both vineyard types. Due to the use of herbicides and frequent tilling, both types of vineyards showed low natural vegetation groundcover. Vineyard modernization had clear effects on fauna biodiversity in vineyard plots, with a higher occurrence in trellis vineyards of some species (rufous-tailed scrub-robin, European goldfinch, red-legged partridge, and house sparrow) and a higher occurrence of other species (European rabbit and European greenfinch) in traditional ones. Thus, vineyard modernization can drive a change in the community of birds and mammals that inhabit them. In addition, vineyard use by some species (particularly ground-dwelling ones) was strongly determined by the presence of arable land adjacent to the vineyard. These species may therefore use vineyards during summer because they provide water and/or better cover than harvested crops. Animals attracted to vineyards for water could be exposed to toxic doses of nitrates that are routinely applied through the watering system in a third of these. To maximize benefits for biodiversity, it would be advisable to manage modernization schemes in order to maintain landscape heterogeneity, with vineyards of both types combined with other agricultural systems, as well as higher proportions of natural vegetation surface cover., F.M. and B.A.'s time for writing this paper was within the AGROPERDIZ project (SBPLY/17/180501/000245), funded by the “Fondo Europeo de Desarrollo Regional” (Feder) and “Junta de Comunidades de Castilla-La Mancha” (JCCM) (recipient: F.M). X.C. was supported by a Ph.D. grant from the Basque Country Government (Grant number PRE_2018_2_0273).

Objective: The current investigation examined how a bout of soccer heading may impact brain function. Design: Semi-randomized crossover cohort. Setting: Controlled soccer heading. Participants: Seven male soccer players (24.1 ± 1.5 years). Intervention: 40 successful soccer headers were performed in 20 min (25 m, launch velocity ~80 km/h). X2 xPatch recorded linear and rotational head accelerations during each impact. A contact control “sham” condition – ball made body contact, but not by the head; and a no activity time “control” condition were also completed. Main Outcome Measures: Posterior and middle cerebral artery (PCA and MCA, respectively), cerebral blood velocity (CBV) was recorded during a visual task (neurovascular coupling: NVC) alongside SCAT3 symptoms scores pre/post a controlled bout of soccer heading. Results: Cumulative linear and rotational accelerations were 1,574 ± 97.9 g and 313,761 ± 23,966 rads/s2, respectively, during heading and changes in SCAT3 symptom number (pre: 2.6 ± 3.0; post: 6.7 ± 6.2, p = 0.13) and severity (pre: 3.7 ± 3.6, post: 9.4 ± 7.6, p = 0.11) were unchanged. In the PCA, no NVC differences were observed, including: relative CBV increase (28.0 ± 7.6%, p = 0.71) and total activation (188.7 ± 68.1 cm, p = 0.93). However, MCA-derived NVC metrics were blunted following heading, demonstrating decreased relative CBV increase (7.8 ± 3.1%, p = 0.03) and decreased total activation (26.7 ± 45.3 cm, p = 0.04). Conclusion: Although an acute bout of soccer heading did not result in an increase of concussion-like symptoms, there were alterations in NVC responses within the MCA during a visual task. This suggests an acute bout of repetitive soccer heading can alter CBV regulation within the region of the brain associated with the header impacts.

Background: An integrated curriculum is designed to be repetitive yet progressive and the concept has rapidly established itself within medical education. National organizations have recommended a shift to a spiral curriculum design, which uses both vertical and horizontal integration. This study examined differences between the recently implemented integrated spiral (class of 2019) and conventional block (classes of 2016–2018) MD curricula at the University of British Columbia (UBC) with respect to knowledge of concussion. Methods: Cross-sectional online survey (FluidSurveys: Fluidware, Ottawa, ON), distributed via email to UBC medical students during the 2015–2016 academic year. Questions focused on demographic data, knowledge of concussion definition, and management considerations. Differences in responses across the two groups were assessed using chi-square tests. Ordinal Likert-scale data were analyzed using Mann-Whitney U-Tests. Statistical significance was determined a priori at p

The definition of diabetes, its causes, complications, and basic treatments are outlined. Diabetes mellitus is characterized by increased concentrations of glucose in the blood. The basic defect is a relative or absolute lack of insulin, the pancreatic hormone promoting the transfer of glucose into tissues for storage as glycogen or fat. Type 1 diabetes is due to autoimmune destruction of insulin-producing cells and insulin therapy is essential. Type 2 diabetes is due to a relative lack of insulin, often with tissue insulin resistance. It is a slowly progressive condition so that, although diet and lifestyle changes are often effective initially, oral therapy and insulin may be required eventually. Diabetes is associated with long-term vascular complications affecting both small and large arteries.

Objective To determine the effects of repetitive subconcussive head trauma on neurovascular coupling (NVC) responses. Design Prospective cohort study collected between September 2013 and December 2016. Setting University laboratory. Participants One hundred seventy-nine elite, junior-level (age, 19.6 ± 1.5 years) contact sport (ice hockey, American football) athletes recruited for preseason testing. Fifty-two nonconcussed athletes returned for postseason testing. Fifteen noncontact sport athletes (age, 20.4 ± 2.2 years) also completed preseason and postseason testing. Exposure(s) Subconcussive sport-related head trauma. Main outcome measures Dynamics of NVC were estimated during cycles of 20 seconds eyes closed and 40 seconds eyes open to a visual stimulus (reading) by measuring cerebral blood flow (CBF) velocity in the posterior (PCA) and middle (MCA) cerebral arteries via transcranial Doppler ultrasound. Results Both athlete groups demonstrated no significant differences in PCA or MCA NVC dynamics between preseason and postseason, despite exposure to a median of 353.5 (range, 295.0-587.3) head impacts (>2g) over the course of the season for contact sport athletes. Conclusions Within the context of growing concern over detrimental effects of repetitive subconcussive trauma, the current results encouragingly suggest that the dynamics of NVC responses are not affected by 1 season of participation in junior-level ice hockey or American football. This is an important finding because it indicates an appropriate postseason CBF response to elevated metabolic demand with increases in neural activity.

Current protocols examining cerebral autoregulation (CA) parameters require participants to refrain from exercise for 12–24 hr, however there is sparse objective evidence examining the recovery trajectory of these measures following exercise across the cardiac cycle (diastole, mean, and systole). Therefore, this study sought to determine the duration acute exercise impacts CA and the within‐day reproducibility of these measures. Nine participants performed squat–stand maneuvers at 0.05 and 0.10 Hz at baseline before three interventions: 45‐min moderate‐continuous exercise (at 50% heart‐rate reserve), 30‐min high‐intensity intervals (ten, 1‐min at 85% heart‐rate reserve), and a control day (30‐min quiet rest). Squat–stands were repeated at hours zero, one, two, four, six, and eight after each condition. Transcranial doppler ultrasound of the middle cerebral artery (MCA) and the posterior cerebral artery (PCA) was used to characterize CA parameters across the cardiac cycle. At baseline, the systolic CA parameters were different than mean and diastolic components (ps 0.079). In the PCA, phase values were affected only following high‐intensity intervals until hour four (ps > 0.055). Normalized gain in all cardiac cycle domains remained different following both exercise protocols (ps, Nine participants performed squat‐stand maneuvers at 0.05 and 0.10 Hz at baseline before three interventions: 45‐min moderate‐continuous exercise (at 50% heart‐rate reserve), 30‐min high‐intensity intervals (ten, one minute at 85% heart‐rate reserve), and a control day (30‐min quiet rest). Squat‐stands were repeated at hours zero, one, two, four, six, and eight after each condition. exercise was shown to affect dynamic CA into recovery up to 4 hr following exercise, with HIIT demonstrating greater affects than MICT (each phase of the cardiac cycle responded differently to exercise, with the systolic component showing impairments for up to 4 hr, compared to diastolic and mean which recovered after 2 hr in all measures).

The central nervous system preplans postural responses to successfully perform complex multi-joint movements. These responses have been termed anticipatory postural adjustments (APAs), and they constitute a general type of response to stabilize posture prior to movement initiation. APA sequences are elicited with shorter latency when a startling acoustic stimulus is applied, demonstrating their preplanned nature. Increasing task complexity using a simple reaction time (RT) paradigm has been shown to delay limb movement RT as a result of additional planning or sequencing requirements; however, the effect of task complexity on APA dynamics is unclear. The purpose of the present study was to investigate if task complexity modulates APA onset in a manner analogous to that observed in the primary effector. 13 participants completed 150 trials of simple (1-target) and complex (2- or 3-target) arm movements while standing on a force plate. Results indicated participants had significantly faster arm movement RTs in the simple versus the most complex condition. Similar to the primary effector, APA RTs were longer in the most complex (3-target) movement compared to both the 1-target and 2-target movements. Furthermore, APA excursion velocities were scaled to the complexity of the upcoming movement: the rate of APAs increased from simplest to most complex movements. These findings clearly demonstrate APAs are sensitive to task complexity, further elucidating their preplanned role in stabilizing posture which enables the successful completion of intended movements.

Ocular near point of convergence (NPC) has been shown to be sensitive to the effects of concussion and subconcussive impacts. To determine if NPC is also sensitive to a previous history of concussion, male contact-sport athletes either with (n=26) or without (n=16) a history of at least one previous concussion had their NPC assessed. The results showed that participants with a history of concussion displayed NPC values (9.4±1.6 cm) indistinguishable from those with no history of concussion (8.4±2.1 cm, t-test, p=0.09). This was the case regardless of whether 1, 2, or 3 or more concussions had occurred and despite the fact participants with concussion (mean time since last concussion: 1136 days) suffered from an increased number and severity of symptoms as assessed with the SCAT 3 (3.6±2.2 vs. 2.13±1.89 symptoms, 6.1±4.1 vs. 3.19±2.99 severity, t-test, p

Biodiversity loss is a major threat to the integrity of ecosystems and is projected to worsen, yet the path to successful conservation remains elusive. Decision support frameworks (DSFs) are increasingly applied by resource managers to navigate the complexity, uncertainty, and differing socio-ecological objectives inherent to conservation problems. Most published conservation research that uses DSFs focuses on analytical stages (e.g., identifying an optimal decision), making it difficult to assess and learn from previous examples in a conservation practice context. Here, we (1) evaluate the relationship between the application of decision science and the resulting conservation outcomes, and (2) identify and address existing barriers to the application of DSFs to conservation practice. To do this, we develop a framework for evaluating conservation initiatives using decision science that emphasizes setting attainable goals, building momentum, and obtaining partner buy-in. We apply this framework to a systematic review of amphibian conservation decision support projects, including a follow-up survey of the pertinent conservation practitioners, stakeholders, and scientists. We found that all projects identified optimal solutions to reach stated objectives, but positive conservation outcomes were limited when implementation challenges arose. Further, we identified multiple barriers (e.g., dynamic and hierarchical leadership, scale complexity, limited resource availability) that can inhibit the progression from decision identification to action implementation (i.e., ‘decision-implementation gap’), and to successful conservation outcomes. Based on these results, we provide potential actionable steps and avenues for future development of DSFs to facilitate the transition from decision to action and the realization of conservation successes.

ObjectivesTo determine the effect of heading a soccer ball on serum neurofilament light (NF-L) protein, plasma tau protein and symptom metrics including total number of symptoms reported and symptom severity scores on the Standardized Concussion Assessment Tool— 3rd edition (SCAT3).MethodsEleven male collegiate soccer players were recruited to take part in three experimental conditions including heading, sham and control conditions. Participants were required to perform 40 headers in 20 min in the heading condition, and control 40 soccer balls directed at them with their hands, chest or thigh in the sham condition. No ball contact was made during the control condition. Blood sampling and SCAT3 symptom assessments were completed prior to and 1 hour following conditions. A subset of participants returned 3 weeks following the heading condition for blood sampling.ResultsNF-L was elevated at 1 hour (p=0.004) and 1 month (p=0.04) following the heading condition, and at 1 hour (p=0.02) following the control condition. Tau levels remained unchanged following all conditions. The total number of symptoms (TS) and symptom severity (SS) scores from the SCAT3 were both elevated following the heading condition (p=0.01 and p=0.03, respectively). Both TS and SS decreased following sham (p=0.04 and p=0.04) and control conditions (p=0.04 and p=0.04).ConclusionAn acute bout of soccer heading is associated with increased NF-L concentrations at 1 hour and 1 month following the session and can lead to symptoms commonly reported following sport-related concussion.

Made available in DSpace on 2019-10-06T15:43:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 A common challenge for studying wildlife populations occurs when different survey methods provide inconsistent or incomplete inference on the trend, dynamics, or viability of a population. A potential solution to the challenge of conflicting or piecemeal data relies on the integration of multiple data types into a unified modeling framework, such as integrated population models (IPMs). IPMs are a powerful approach for species that inhabit spatially and seasonally complex environments. We provide guidance on exploiting the capabilities of IPMs to address inferential discrepancies that stem from spatiotemporal data mismatches. We illustrate this issue with analysis of a migratory species, the American Woodcock (Scolopax minor), in which individual monitoring programs suggest differing population trends. To address this discrepancy, we synthesized several long-term data sets (1963–2015) within an IPM to estimate continental-scale population trends, and link dynamic drivers across the full annual cycle and complete extent of the woodcock's geographic range in eastern North America. Our analysis reveals the limiting portions of the life cycle by identifying time periods and regions where vital rates are lowest and most variable, as well as which demographic parameters constitute the main drivers of population change. We conclude by providing recommendations for resolving conflicting population estimates within an integrated modeling approach, and discuss how strategies (e.g., data thinning, expert opinion elicitation) from other disciplines could be incorporated into ecological analyses when attempting to combine multiple, incongruent data types. Department of Integrative Biology Michigan State University, 288 Farm Lane RM 203 National Audubon Society, 225 Varick Street, 7th Floor Ecology Evolutionary Biology and Behavior Program Michigan State University Department of Biological Sciences Kent State University, 249 Cunningham Hall Institute of Biosciences São Paulo State University (Unesp) Department of Fisheries Wildlife & Conservation Biology University of Minnesota, 2003 Upper Buford Circle, Suite 135 Institute of Biosciences São Paulo State University (Unesp)

Cerebral pressure-flow dynamics are typically reported between mean arterial pressure and mean cerebral blood velocity. However, by reporting only mean responses, potential differential regulatory properties associated with systole and diastole may have been overlooked.Twenty young adults (16 male, age: 26.7 ± 6.6 years, BMI: 24.9 ± 3.0 kg/mThere were main effects for both cardiac cycle and frequency for phase and gain metrics (p0.001). The systolic phase (mean ± SD) was elevated at 0.05 (1.07 ± 0.51 radians) and 0.10 Hz (0.70 ± 0.46 radians) compared to the diastolic phase (0.05 Hz: 0.59 ± 0.14 radians; 0.10 Hz: 0.33 ± 0.11 radians). Conversely, the systolic normalized gain was reduced (0.05 Hz: 0.49 ± 0.12%/%; 0.10 Hz: 0.66 ± 0.20%/%) compared to the diastolic normalized gain (0.05 Hz: 1.46 ± 0.43%/%; 0.10 Hz: 1.97 ± 0.48%/%).These findings indicate there are differential systolic and diastolic aspects of the cerebral pressure-flow relationship. The oscillations associated with systole are extensively buffered within the cerebrovasculature, whereas diastolic oscillations are relatively unaltered. This indicates that the brain is adapted to protect itself against large increases in systolic blood pressure, likely as a mechanism to prevent cerebral haemorrhages.

To determine whether acute sports-related concussion (SRC) exerts differential effects on cerebral autoregulatory properties during systole versus diastole.One hundred and thirty-six contact-sport athletes tested preseason; 14 sustained a concussion and completed follow-up testing at 72 hours, 2 weeks, and 1 month post-injury. Five minutes of repetitive squat-stand maneuvers induced blood pressure (BP) oscillations at both 0.05 and 0.10 Hz. Beat-by-beat peak-systolic and end-diastolic BP (sysBP/ diasBP) and middle cerebral artery blood velocity (sysMCAv/diasMCAv) were recorded using finger photoplethysmography and transcranial Doppler ultrasound, respectively. Relationships between sysBP-sysMCAv and diasBP-diasMCAv were quantified using transfer function analysis to estimate coherence (correlation), gain (response magnitude), and phase (response latency).Significant main effects of the cardiac cycle were observed across all outcome metrics. A significant main effect of SRC was observed for 0.10 Hz phase: systolic and diastolic phases were reduced at 72 h (21.8 ± 5.2%) and 2 weeks (22.7 ± 7.1%) compared to preseason but recovered by 1 month. Concussion significantly impaired diastolic, but not systolic, gain: 0.10 Hz diastolic gain was increased (27.2 ± 7.7%) at 2 weeks, recovering by 1 month.Impairments in autoregulatory capacity, observed for a transient period following SRC that persist beyond symptom resolution and clinical recovery, appear to be differentially affected across the cardiac cycle. Similar patterns of impairment were observed for systolic and diastolic phases (response latency); however, normalized gain (response magnitude) impairments were identified only in diastole. These findings may explain the increased cerebral vulnerability as well as exercise-induced symptom exacerbation observed post-SRC.

Sport-related concussion is known to affect a variety of brain functions. However, the impact of this brain injury on cerebral autoregulation is poorly understood. Thus, the goal of the current study was to determine the acute and cumulative effects of sport-related concussion on indices of dynamic cerebral autoregulation. Towards this end, 179 elite, junior-level (age 19.6 ± 1.5 years) contact sport (ice hockey, American football) athletes recruited for pre-season testing, 42 with zero prior concussions and 31 with three or more previous concussions. Eighteen athletes sustained a concussion during that competitive season, and completed follow-up testing at 72-hours, 2-weeks, and 1-month post-injury. Beat-by-beat arterial blood pressure (BP) and middle cerebral artery blood velocity (MCAv) were recorded using finger photoplethysmography and transcranial Doppler ultrasound, respectively. Five minutes of repetitive squat-stand manoeuvres induced BP oscillations at 0.05 Hz and 0.10 Hz (20-s and 10-s cycles, respectively). The BP-MCAv relationship was quantified using transfer function analysis to estimate Coherence (correlation), Gain (amplitude ratio), and Phase (timing offset). At a group level, repeated-measures ANOVA indicated 0.10 Hz Phase was significantly reduced following an acute concussion, compared to preseason, by 23% (-0.136 ± 0.033 rads) at 72 hours and by 18% (-0.105 ± 0.029 rads) at 2-weeks post-injury, indicating impaired autoregulatory functioning; recovery to preseason values occurred by 1-month. Athletes were cleared to return to competition after a median of 14 days (range 7-35), implying physiologic dysfunction persisted beyond clinical recovery in many cases. When comparing dynamic pressure buffering between athletes with zero prior concussions and those with three or more, no differences were observed. Sustaining an acute sport-related concussion induces transient impairments in the capabilities of the cerebrovascular pressure-buffering system that may persist beyond two weeks, and may be due to a period of autonomic dysregulation. Athletes with a history of three or more concussions did not exhibit impairments relative to those with zero prior concussions, suggesting recovery of function over time. Findings from this study support the potential need to consider physiological recovery in deciding when patients should return-to-play following a concussion.

Objective: To determine whether acute sports-related concussion (SRC) exerts differential effects on cerebral autoregulatory properties during systole versus diastole.

Objective: Cerebral pressure-flow dynamics are typically reported between mean arterial pressure and mean cerebral blood velocity. However, by reporting only mean responses, potential differential regulatory properties associated with systole and diastole may have been overlooked.

Although balance control has been studied extensively following acute concussion, little is known regarding repetitive sub-concussive head impacts or chronic exposure to multiple concussive events. Quiet stance postural control was characterized in contact sport athletes at pre-season (n = 135) and post-season (n = 48) to evaluate the effects of subconcussive trauma to the head. To determine the impact of acute concussion on postural control, athletes diagnosed with a concussion during the season (n = 12) were tested at 72-h, 2-weeks, and 1-month post-injury. Because only 4 of the concussed athletes completed baseline testing, control athletes (n = 12) matched for sport, age, body mass index (BMI), and previous concussion history served as a comparison group. Finally, the effects of previous concussion history on quiet stance postural control were determined by comparing pre-season data in contact sport athletes with either zero (Hx0, n = 50) or three or more (Hx3+, n = 25) previous concussions. A force plate was used to compare changes in centre-of-pressure root-mean-square displacement (RMSdisp) and mean-velocity (COPvel) in the anterior/posterior (AP) and medial/lateral (ML) directions. One-minute trials were performed with feet hip-width apart, hands-on-hips, and A) eyes-open and B) eyes-closed. Biomechanical head-impact exposure (impacts over 10 g) was indexed over the season using mastoid-fixed impact sensors. In acutely injured athletes, repeated-measures ANOVA revealed a significant effect of time for RMSdisp AP with increased displacement at 2 weeks compared to 72 h (p = 0.008, 95% CI: −0.180, −0.310 cm). No other COP variables were affected by acute concussion. Moreover, there was no effect of concussion history or repeated sub-concussive impacts on any quiet stance metric. Additionally, head-impact exposure metrics were not correlated with COP metrics. Taken together, the data suggests alterations in COP sway during quiet stance persist in the acute 2-week period after injury. These findings were not present with either a history of multiple concussions or exposure to sub-concussive head impacts indicating acute concussion does not have appear to have long term effects for these measures.

Many bridge designers currently rely on the design specifications provided by AASHTO to evaluate liquefaction hazards for foundations and embankments. These guide specifications recommend a pseudo-probabilistic approach (i.e., an approach in which probabilistic estimates of seismic loading are incorporated into a deterministic liquefaction hazard analysis) for most conventional projects. A more consistent approach for the assessment of liquefaction hazards would involve a performance-based or uniform hazard evaluation of liquefaction potential. However, a performance-based liquefaction analysis is complex and difficult to implement in practice. This paper describes a simplified procedure for uniform hazard liquefaction analysis that uses the standard penetration test to closely approximate the results of a performance-based liquefaction analysis at a desired uniform hazard level. The simplified procedure is compatible with current AASHTO load and resistance factor bridge design specifications and is intended for use on bridges and other transportation-related structures. The procedure is summarized and shown to produce more consistent results for liquefaction hazards across different seismic environments than the existing AASHTO pseudo-probabilistic procedure. An example application of the simplified procedure is presented and discussed, and limitations for the procedure's proper use are provided.

Background The concept of neurovascular coupling has been postulated since the late 1800s and has been demonstrated most commonly in humans using visual stimuli (e.g. reading, checkerboards). These traditional paradigms evoke only a moderate cerebral blood flow response due to the relative simplicity of the visual stimuli. New method Forty subjects completed three visual paradigms each challenging the visual processing areas to a different extent: reading text, complicated visual searching (new method: Where ’ s Waldo ) and viewing coloured dots. Posterior and middle cerebral artery (PCA, MCA) velocities were recorded using transcranial Doppler ultrasound during each visual paradigm. Results Prior to the presentation of the visual stimuli there were no differences in mean arterial pressure, or PCA or MCA velocities for the three paradigms. All three paradigms led to an elevation in PCA and MCA velocities after a delay (∼1.1 s). Whereas velocity elevation was consistent across the three paradigms in the MCA, it was markedly larger during the Where ’ s Waldo task in the PCA. Thus, although the onset of the neurovascular coupling response was similar across the three visual paradigms, its overall magnitude was stimulus-dependent. Comparison with existing methods Given that PCA velocity can be affected by blood pressure or carbon dioxide alterations, traditional neurovascular coupling paradigms (e.g. reading, checkerboards) appear to have a lower signal-to-noise ratio than that observed in complicated visual search tasks such as Where ’ s Waldo. Conclusions We recommend complicated visual search paradigms such as Where ’ s Waldo be considered for future transcranial Doppler-based neurovascular coupling studies.

Objective Examine differences between the recently implemented integrated spiral (year 1) and conventional block (years 2-4) MD curriculum at University of British Columbia (UBC) with respect to knowledge of concussion diagnosis and management. Design Cross-sectional survey Setting UBC undergraduate MD program Participants An online survey was distributed to all 1152 students currently enrolled in UBC medical school. To date, 123 surveys have been returned (10.7% response rate) with 58 first year students (integrated spiral curriculum) and 65 students in years 2-4 (conventional block curriculum). Females made up 60% of responses. Interventions Online survey, hosted by FluidSurveys (Fluidware, Ottawa, ON), distributed through email. Outcome measures Questions focused on demographic data, knowledge of concussion definitions, and management considerations. Main results Majority of responses revealed both curriculums have promoted a strong understanding of concussion definition and related symptoms (84% correct response rate). Only 8.1% of participants believed that functional imaging (MRI or CT) is a mandatory assessment tool for concussions. Differences between the conventional and integrated curriculums included: understanding concussions can occur without direct impact to the head (91.4% integrated vs. 69.2% conventional: χ2(1)=43.325, p Conclusions The findings from this study reveal a number of positive signs regarding the evolution of medical education in terms of concussion diagnosis and management. The integrated curriculum is taking further steps in advancing concussion knowledge in medical education. Competing interests None.

Objective To determine the influence of a history of 3+ previous concussions on quiet stance. Design Retrospective cohort. Setting Laboratory. Participants Eighty-seven male (age range 17–22) contact-sport athletes (football and hockey) entered the study. Participants were recruited from the same sport teams and tested during the pre-season. Exclusion criteria: concussion in the prior 6 months, or history of 1 or 2 concussions. Forty-four met the inclusion criteria: thirty-one had no previous concussions, and thirteen had a history of 3+ concussions. Interventions Participants held quiet upright stance on a force plate (NDI True Impulse) with feet hip-width apart and hands on hips with eyes-open (1 min), and closed (1 min). Independent variables included condition (2) and concussion history (2). Outcome measures Root-mean-square displacement (RMSd), and mean velocity of centre-of-pressure (COP) in the anterior/posterior (AP) and medial/lateral (ML) directions. Main results Mixed ANOVA indicated a significant condition effect in ML-RMSd (p=0.015, 95% CI: 0.032–0.277) between eyes-open and eyes-closed conditions. ML mean velocity also displayed a significant condition effect (p=0.025, 95% CI: 0.025–0.358). In contrast to the effect of visual input, there was no main effect of concussion history on these metrics. Conclusions A history of 3+ concussions does not appear to result in long-term deficits controlling in quiet stance. Those ML variables were sensitive to condition and indicate that frontal plane COP movements may be more sensitive than those in the sagittal plane. These findings are important as a history of concussion does not appear to alter quiet stance balance control mechanisms. Competing interests None.

Objective To examine how sub-concussive head trauma throughout a contact-sport season affects quiet stance centre of pressure (COP) sway Design Prospective cohort Setting Laboratory Participants: Twenty-four elite male football players (age range 18–22) were recruited for the study Intervention Quiet stance data was collected at the start and at the end of the competitive season. One-minute trials were performed with eyes-open and eyes-closed on a force plate (NDI True Impulse) with feet hip-width apart and hands-on-hips. Biomechanical head-impact exposure was indexed using the xPatch (X2 Biosystems) Outcome measures COP measures: Anterior/posterior (AP) and medial/lateral (ML) root-mean-square displacement (RMSd) and mean velocity. Biomechanical head-impact data: For hits above 20g, peak linear acceleration (PLA), and peak rotational acceleration (PRAwere estimated across the competitive season. Independent variables included time (2) and condition (2) Results RM-ANOVA reveal an effect of condition (eyes-open vs eyes-closed) in AP-RMSd (p=0.035, 95% CI: 0.006, 0.159), ML-RMSd (p Conclusions In contrast to the prolonged COP alterations observed following acute concussions, there were no discernable effects of sub-concussive trauma on COP sway during quiet stance in the same population. This is an important finding as it reveals that participation in contract-sport does not impair quiet stance balance Competing interests None.

Objective To examine the effects of concussion history on an index of cerebral autoregulation in a healthy athlete population. Design Retrospective Cohort. Setting Laboratory. Participants 136 male contact sport athletes (19.1±1.4 years, 66 football, 70 hockey) were recruited; 39 presented with 0 previous concussions, 16 with 3+ previous concussions; exclusion criteria included history of concussion within 6 months. Intervention Participants completed baseline testing prior to the athletic season. Squat-stand manoeuvres at 0.05 and 0.10 Hz were used to enhance blood pressure (BP) variation. BP and cerebral blood velocity (CBV) in the middle cerebral artery were indexed non-invasively via finger photoplethysmography and transcranial Doppler ultrasound, respectively. Independent variables included sport (2) and concussion history (2). Outcomes Transfer function analysis point estimates at 0.05 and 0.10 Hz characterised the coherence (correlation), phase (synchronisation), and gain (amplitude buffer) between BP and CBV waveforms during the squat-stand manoeuvres. Results These findings suggest that, despite reductions in 0.10 Hz phase lead being reported acutely after concussion, multiple concussions do not appear to induce long-term impairments in dynamic cerebral autoregulation metrics. This is an important revelation as it indicates that the cerebrovasculature is able to adequately recover following the acutely diminished buffering capacity associated with a concussive injury Conclusions These findings suggest that, despite reductions in 0.10 Hz phase lead being reported acutely after concussion, multiple concussions do not appear to induce long-term impairments in dynamic cerebral autoregulation metrics. This is an important revelation as it indicates that the cerebrovasculature is able to adequately recover following the acutely diminished buffering capacity associated with a concussive injury Competing interests None.

Objective To examine how acute sport-related concussion influences centre of pressure (COP) sway during quiet stance Design Prospective cohort Setting Laboratory Participants Eighty-seven male contact-sport (football and hockey) athletes entered the study. Seven subjects (age range 17–22) were concussed and completed follow-up testing 72-hours, two-weeks, and one-month following the injury. Intervention One-minute eyes-open and eyes-closed quiet stance trials were performed on a force plate (NDI True Impluse) with feet hip-width apart. Force plate data and SCAT3 were collected at each time point. Outcome measures Root-mean-square COP displacement (RMSd) and mean COP velocity were quantified in the anterior/posterior (AP) and medial/lateral (ML) directions. Independent variables included condition (2) and time (4) Main results RM-ANOVA indicated a main effect of time for all outcomes: AP-RMSd (p=0.006), AP mean velocity (p=0.012), ML-RMSd (p=0.001), ML mean velocity (p=0.001). Pairwise comparisons indicated reductions at 2-weeks in AP-RMSd (0.05, 95% CI: −0.672, 0.000), and AP mean velocity (p=0.039, 95% CI: −1.275, −0.036). ML-RMSd was reduced 1 month post-concussion (p=0.021, 95% CI: −0.365, −0.034). Change scores from baseline to 72-hours were correclated between: AP-RMSd and Balance Error Scoring System (r=0.878, p=0.009), AP mean velocity and Standardised Assessment of Concussion (SAC) (r=−0.822, p=0.023), and ML mean velocity and SAC (r=−0.836, p=0.019). Conclusions Measures of COP sway during quiet stance revealed alterations in displacement and velocity that persisted up to one-month following a sports-related concussion. These COP alterations exceeded the duration of clinical recovery (median return-to-play: 14 days) indicating that clinical recovery does not equal physiological recovery. Competing interests None.

Objective To examine the effect of multiple previous concussions on heart rate variability (HRV) in contact-sport athletes. Design Retrospective Cohort. Setting Laboratory. Participants 136 male elite contact-sport (hockey and football) athletes were recruited for this study. Forty-one had no previous concussion history (Hx-), while nineteen had a history of three or more concussions (Hx+). All testing was preformed prior to the start of the competitive season Interventions HRV was assessed during 5-minutes of quiet stance, and while actively squatting at 0.10 Hz via a 3-lead electrocardiogram, using Kubios software. Independent variables included condition (rest vs active) and group (Hx+ vs Hx-) Outcome measures Time-Domain: square root of mean squared differences of successive R-R intervals (RMSSD), percentage of successive R-R intervals that differ by more than 50 milliseconds (pNN50). Frequency-Domain: total power. Main results Mixed ANOVA revealed repeated squat-stand manoeuvres challenged the autonomic system, increasing total power by 2477 milliseconds2 (95% CI: 1153–3801, p Conclusions A history of multiple sport-related concussions impairs the ability of the autonomic system to respond to an everyday stressor applied to the cardiovascular system (squatting and standing). This is an important finding, as it reveals that cumulative concussions may impart long-term impairments in the ability to accurately regulate the autonomic system. Competing interests None.

Objective To determine how a history of 3+ concussions alters elevations in cerebral blood velocity (CBV) in the posterior cerebral artery (PCA) during visual tasks. Design Retrospective Cohort. Setting Laboratory. Participants 136 male contact-sport athletes (19.1±1.4 years, 66 football, 70 hockey) were recruited; 39 presented with 0 previous concussions, 16 with 3+ previous concussions; exclusion criteria included history of concussion within 6 months. Intervention Transcranial Doppler ultrasound indexed PCA-CBV during a series of visual tasks. Participants closed their eyes (20-seconds) and, when prompted, opened their eyes to complete a visual task (40-seconds). Testing occurred prior to the start of their athletic season. The visual trial raw traces were averaged together to enhance the signal-to-noise ratio of outcome measurements. The independent variable tested was concussion history. Outcomes Eyes-closed CBV (cm/s), peak elevation in CBV after eyes-open (cm/s), relative change in CBV (%), and total activation during the first 30 seconds of the task (indexed via area under the curve-AUC) Main results Independent samples T-Tests indicated there were no effects of concussion history on any outcome: Eyes-closed CBV (p=0.950), peak CBV (p=0.903), % CBV elevation (p=0.593), and AUC (p=0.718). Conclusions A history of multiple concussions does not alter the cerebrovasculature’s ability to maintain nutrient delivery required for visual challenges in cortical areas supplied by the PCA. This is an important finding; despite the long-term neurocognitive deficits associated with a history of concussions, the transcranial Doppler assessment of neurovascular coupling appears intact for this population of younger adult contact-sport athletes. Competing interests None.

Objective To determinethe extentto which an acute sport-related concussion disrupts elevations in cerebral blood velocity (CBV) in the posterior cerebral artery (PCA) during visual tasks. Design Prospective Cohort. Setting Laboratory. Participants 136 male contact-sport athletes (19.1±1.4 years) recruited, subset of 14 participants (19±1.4 years) sustained concussions. Intervention Transcranial Doppler ultrasound was used to index CBV in the PCA during a series of visual tasks. Participants closed their eyes (20 seconds), and when prompted, opened their eyes and completed a visual task (40 seconds). Testing was completed prior to the start of their athletic season (T0), and again (if concussed) at 72-hours (T1), 2-weeks (T2), and 1-month (T3) post-injury. The raw traces from each trial were averaged to enhance the signal-to-noise ratio of the outcome measurements. Independent variable tested was time (4 points). Outcome measures Eyes-closed CBV (cm/s), peak elevation in CBV (cm/s), relative change in CBV (%) and total activation during the first 30 seconds of the task (indexed via area under the curve-AUC) Main results RM-ANOVA indicated there were no time effects forany of the outcome metrics: Eyes-closed CBV (p=0.473), peak CBV (p=0.541),% CBV elevation (p=0.603) and AUC (p=0.972). Conclusions These negative findings are important, as they indicate the PCA is able to maintain nutrient delivery required for visual challenges. Thus, neurovascular coupling is maintained despite the reported impairments in indices of cerebral autoregulation in the same population. Competing interests None.

Objective To examine how head-impact exposures affect the elevation in cerebral blood velocity (CBV) in the posterior cerebral artery (PCA) during visual tasks. Design Prospective Cohort. Setting Laboratory. Participants To date: 40 male contact-sport athletes (19.4±1.2 years) and 3 cross-country athletes (20.0±1.0 years) have completed testing (non-contact controls). Intervention Transcranial Doppler ultrasound indexed PCA CBV during visual tasks. Participants closed their eyes (20-seconds), and when prompted, opened them and completed a visual task (40-seconds). Testing occurred prior-to and upon-completion-of the competitive athletic season. Raw traces from each trial were averaged to enhance the signal-to-noise ratio of outcome measurements. Independent variable tested was time (2). Outcome Eyes-closed CBV (cm/s), peak elevation in CBV (cm/s), relative change in CBV (%) and total activation during the first 30 seconds of the task (indexed via area under the curve-AUC). Head-impact exposure was characterised in a subset of contact-sport athletes (n=29) using the xPatch (X2 Biosystems). Main results RM-ANOVA indicated the contact-sport season had no effects on any outcome metrics: Eyes-closed CBV (p=0.181), peak CBV (p=0.117),% CBV elevation (p=0.252) and AUC (p=0.366), despite experiencing cumulative peak linear accelerations of 8147.2±6215.5 g, and cumulative peak rotational accelerations of 34.5×106 ± 59.0×106 rad/?s2. Conclusions The results from this study suggest neurovascular coupling metrics are maintained throughout a contact-sport season. This indicates nutrient delivery is maintained for neurocognitive challenges despite possible impairments in cerebrovasculature’s ability to buffer blood pressure challenges associated elevations in rotational accelerations experienced during a contact-sport season. Competing interests None.

Objective Examine how the frequency-dependent relationship between blood pressure (BP) and cerebral blood velocity (CBV) is affected by acute sport-related concussion. Design Prospective Cohort. Setting Laboratory. Participants: 136 male contact-sport athletes (19.1±1.4 years) recruited, subset of 14 sustained concussions (19±1.4 years). Intervention Participants completed baseline (T0) and post-injury testing at 72-hours (T1), 2-weeks (T2), and 1-month (T3). BP was monitored via finger photoplethysmography, and transcranial Doppler ultrasound indexed CBV in the middle cerebral artery. Squat-stand manoeuvers were performed at 0.05 and 0.10Hz to enhance BP variation. RM-ANOVA independent variables included time (4) and frequency (2). Outcome measures Transfer function analysis point estimates quantified coherence (correlation), phase (synchronisation) and gain (amplitude buffer) metrics between BP and CBV waveforms. Results Significant frequency-time interactions for phase (p=0.007) and gain (p=0.049). Simple effects analysis revealed time effects for phase at 0.10 Hz, indicating reductions at T1 (95% CI: 0.033 – 0.24 rads, p=0.008) and T2 (95% CI: 0.014–0.196 rads, p=0.02) compared to T0. On average, return-to-play occurred at T2 (median 14 days). Phase reductions at T1 were correlated with Standardised Assessment of Concussion performance (r=0.659, p=0.02). Conclusions These results reveal transient post-concussion impairments in the capacity of the cerebrovasculature to buffer BP oscillations, which exceeded clinical recovery duration. Phase reductions at 0.10Hz suggest the presence of a cerebrovascular autonomic dysregulation, which could leave the brain less protected to BP surges. This key finding may help explain why the brain is more vulnerable to additional trauma during the post-injury recovery period. Competing interests None.

Simplified empirical liquefaction triggering models are commonly used throughout the world to assess the liquefaction initiation hazard. Significant differences between two popular liquefaction triggering models have precipitated a substantial amount of confusion in modern engineering practice. Past research to study these differences has generally focused on deterministic or scenario-based applications of the liquefaction models without directly accounting for uncertainties from the models or seismic loading. This paper investigates how accounting for these uncertainties through a performance-based liquefaction triggering assessment affects the differences between these two probabilistic liquefaction models. A comparative parametric study is performed in which a wide range of soil parameters, seismicity levels, and return periods is considered in assessing the disparity between the two models. This disparity is shown to vary significantly with variations in the parameters that were evaluated. Add...

Twelve-hour hormonal and metabolic profiles were performed in a 68-year-old woman with a benign adrenal phaeochromocytoma (a) prior to adrenergic blockade, (b) after the establishment of pharmacological alpha-blockade with phenoxybenzamine, (c) after combined alpha and beta-blockade with phenoxybenzamine and propranolol, and (d) after successful surgery and withdrawal of medication. Pretreatment, (a) vs (d), significant elevations (12-h mean +/- SD) were observed in the concentrations of noradrenaline (44.9 +/- 14.4 vs 2.3 +/- 0.7 nmol/l, P less than 0.01), glucose (6.9 +/- 1.9 vs 5.0 +/- 1.0 mmol/l, P less than 0.05), glycerol (0.22 +/- 0.02 vs 0.07 +/- 0.01 mmol/l, P less than 0.01), non-esterified fatty acids (0.71 +/- 0.28 vs 0.34 +/- 0.08 mmol/l, P less than 0.01), and total ketone bodies (0.08 +/- 0.03 vs 0.03 +/- 0.02 mmol/l, P less than 0.01). Alpha-blockade, (b) vs (a), was associated with an increase in noradrenaline levels (P less than 0.01) but not with any significant alterations in intermediary metabolite concentrations. Following the establishment of combined alpha and beta-blockade, (c) vs (b), plasma noradrenaline returned to its pretreatment level while the concentrations of glycerol, fatty acids and ketone bodies were normalized. A completely physiological 12-h blood glucose profile, however, was observed only post-operatively. No significant differences were observed in mean plasma insulin levels between the four studies. These results indicate impaired regulation of multiple aspects of carbohydrate, lipid and ketone body metabolism in our patient.(ABSTRACT TRUNCATED AT 250 WORDS)