To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Background: Insertion of an external ventricular drain (EVD) is performed to treat elevated intracranial pressure. EVD catheters are associated with complications such as EVD catheter infection (ECI), intracranial hemorrhage (ICH) and suboptimal catheter placement. As part of the Canadian Neurosurgery Research Collaborative, we sought to investigate the national rate of such complications and their risk factors. Methods: Prospective study of 273 patients from eight academic Canadian neurosurgery centres Results: Infection rate was 6% and predicted by smaller incisions and not peri-procedure antibiotics, tunneling distance, type of antiseptic used or catheter flushing (p>0.05). The mean duration of EVD was 17.7±3.7 in ECI and ventriculitis group which was significantly higher than in patients without ECI (9.4±8.1) (p=0.045). Although the risk of developing ICH was 9.3%, symptomatic ICH was rare. Pre-procedure pharmacological DVT prophylaxis predicted EVD-related ICH(OR 4.73). The rate of suboptimal catheter location was 31% and predicted by the number of passes (p=0.02), but not image guidance, level of training or catheter placement in an operating room setting (p>0.05). Conclusions: This study reports EVD complication rates and their associated risk factors observed within an academic, multicentre Canadian cohort. This information will help to identify strategies to increase the safety of this common neurosurgical procedure.
Background: There are few published reports on the safety and efficacy of stereoelectroencephalography (SEEG) in the presurgical evaluation of pediatric drug-resistant epilepsy. Our objective was to describe institutional experience with pediatric SEEG in terms of (1) insertional complications, (2) identification of the epileptogenic zone and (3) seizure outcome following SEEG-tailored resections. Methods: Retrospective review of 29 patients pediatric drug resistant epilepsy patients who underwent presurgical SEEG between 2005 – 2018. Results: 29 pediatric SEEG patients (15 male; 12.4 ± 4.6 years old) were included in this study with mean follow-up of 6.0 ± 4.1 years. SEEG-related complications occurred in 1/29 (3%)—neurogenic pulmonary edema. A total of 190 multi-contact electrodes (mean of 7.0 ± 2.5per patient) were implanted across 30 insertions which captured 437 electrographic seizures (mean 17.5 ± 27.6 per patient). The most common rationale for SEEG was normal MRI with surface EEG that failed to identify the EZ (16/29; 55%). SEEG-tailored resections were performed in 24/29 (83%). Engel I outcome was achieved following resections in 19/24 cases (79%) with 5.9 ± 4.0 years of post-operative follow-up. Conclusions: Stereoelectroencephalography in presurgical evaluation of pediatric drug-resistant epilepsy is a safe and effective way to identify the epileptogenic zone permitting SEEG-tailored resection.
In politically contested health debates, stakeholders on both sides present arguments and evidence to influence public opinion and the political agenda. The present study aimed to examine whether stakeholders in the Soft Drinks Industry Levy (SDIL) debate sought to establish or undermine the acceptability of this policy through the news media and how this compared with similar policy debates in relation to tobacco and alcohol industries.
Quantitative and qualitative content analysis of newspaper articles discussing sugar-sweetened beverage (SSB) taxation published in eleven UK newspapers between 1 April 2015 and 30 November 2016, identified through the Nexis database. Direct stakeholder citations were entered in NVivo to allow inductive thematic analysis and comparison with an established typology of industry stakeholder arguments used by the alcohol and tobacco industries.
Proponents and opponents of SSB tax/SDIL cited in UK newspapers.
Four hundred and ninety-one newspaper articles cited stakeholders’ (n 287) arguments in relation to SSB taxation (n 1761: 65 % supportive and 35 % opposing). Stakeholders’ positions broadly reflected their vested interests. Inconsistencies arose from: changes in ideological position; insufficient clarity on the nature of the problem to be solved; policy priorities; and consistency with academic rigour. Both opposing and supportive themes were comparable with the alcohol and tobacco industry typology.
Public health advocates were particularly prominent in the UK newspaper debate surrounding the SDIL. Advocates in future policy debates might benefit from seeking a similar level of prominence and avoiding inconsistencies by being clearer about the policy objective and mechanisms.
Introduction: Simulation is becoming widely adopted across medical disciplines and by different medical professionals. For medical students, emergency medicine simulation has been shown to increase knowledge, confidence and satisfaction. At the University of Ottawa Skills and Simulation Centre, third-year medical students participate in simulated scenarios common to Emergency Medicine (EM) as part of their mandatory EM clerkship rotation. This study aims to evaluate simulation as part of the EM clerkship rotation by assessing changes in student confidence following a simulation session. Methods: In groups of seven, third year medical students at the University of Ottawa completed simulation sessions of the following: Status Asthmaticus, Status Epilepticus, Urosepsis and Breaking Bad News. Student confidence with each topic was assessed before and after simulation with a written survey. Confidence scores pre- and post-simulation were compared with the Wilcoxon signed rank test. Results: Forty-eight third years medical students in their core EM clerkship rotation, between September 2017 and August 2018 participated in this study. Medical student confidence with diagnosis of status asthmaticus (N = 44, p = 0.0449) and status epilepticus (N = 45, p = 0.0011) increased significantly following simulation, whereas confidence with diagnosis of urosepsis was unchanged (N = 45, p = 0.0871). Treatment confidence increased significantly for status asthmaticus (N = 47, p = 0.0009), status epilepticus (N = 48, p = 0.0005) and urosepsis (N = 48, p < 0.0001). Confidence for breaking bad news was not significantly changed after simulation (N = 47, p = 0.0689). Conclusion: Simulation training in our EM clerkship rotation significantly increased the confidence of medical students for certain common EM presentations, but not for all. Further work will aim to understand why some simulation scenarios did not improve confidence, and look to improve existing scenarios.
We identified a pseudo-outbreak of Mycobacterium avium in an outpatient bronchoscopy clinic following an increase in clinic procedure volume. We terminated the pseudo-outbreak by increasing the frequency of automated endoscope reprocessors (AER) filter changes from quarterly to monthly. Filter changing schedules should depend on use rather than fixed time intervals.
The Arizona Department of Health Services identified unusually high levels of influenza activity and severe complications during the 2015–2016 influenza season leading to concerns about potential increased disease severity compared with prior seasons. We estimated state-level burden and severity to compare across three seasons using multiple data sources for community-level illness, hospitalisation and death. Severity ratios were calculated as the number of hospitalisations or deaths per community case. Community influenza-like illness rates, hospitalisation rates and mortality rates in 2015–2016 were higher than the previous two seasons. However, ratios of severe disease to community illness were similar. Arizona experienced overall increased disease burden in 2015–2016, but not increased severity compared with prior seasons. Timely estimates of state-specific burden and severity are potentially feasible and may provide important information during seemingly unusual influenza seasons or pandemic situations.
Background: External ventricular drain (EVD) insertion is a common neurosurgical procedure performed in patients with life-threatening conditions, but can be associated with complications. The objectives of this study are to evaluate data on national practice patterns and complications rates in order to optimize clinical care Methods: The Canadian Neurosurgery Research Collaborative conducted a prospective multi-centre registry of patients undergoing EVD insertions at Canadian residency programs Results: In this interim analysis, 4 sites had recruited 46 patients (mean age: 53.9 years, male:female 2:1). Most EVD insertions occurred outside of the operating theatre, using free-hand technique, and performed by junior neurosurgery residents (R1-R3). The catheter tip was in the ipsilateral frontal horn or body of the lateral ventricle in 76% of cases. Suboptimally placed catheters did not have higher rates of short-term occlusion. EVD-related hemorrhage occurred in 6.5% (3/45) with only 1 symptomatic patient. EVD-related infection occurred in 13% (6/46) at a mean of 6 days and was associated with longer duration of CSF drainage (P=0.039; OR: 1.13) Conclusions: Interim results indicate rates of EVD-related complications may be higher than previously thought. This study will continue to recruit patients to confirm these findings and determine specific risk factors associated with them
There is substantial evidence of an inverse association between birth weight and later blood pressure (BP) in populations from high-income countries, but whether this applies in low-income countries, where causes of low birth weight are different, is not certain. Objective: We conducted a review of the evidence on the relationship between birth weight and BP among African children and adolescents. Medline, EMBASE, Global Health and Web of Science databases were searched for publications to October 2016. Papers reporting the relationship between birth weight and BP among African children and adolescents were assessed. Bibliographies were searched for further relevant publications. Selected papers were summarized following the preferred reporting items for systematic review and meta-analysis (PRISMA) guidelines. In total, 16 papers from 13 studies conducted in nine African countries (Nigeria, Republic of Seychelles, Gambia, Democratic Republic of Congo, Cameroon, South Africa, Algeria, Zimbabwe and Angola) were reviewed. Eight studies were cohorts, while five were cross-sectional. The relationship between birth weight and later BP varied with age of the participants. Studies in neonates showed a consistently positive association, while predominantly inverse associations were seen among children, and studies in adolescents were inconsistent. Based on the limited number of studies identified, the relationship between birth weight and later BP may vary with age in African children and adolescents. Not all studies adequately controlled for confounding, notably gender or age. Whether the inverse relationship between birth weight and BP in later life observed in Western settings is also seen in Africa remains unclear.
Background: Neurosurgical residents face a unique combination of challenges, including long duty hours, technically challenging cases, and uncertain employment prospects. We sought to assess the demographics, interests, career goals, self-rated happiness, and overall well-being of Canadian neurosurgery residents. Methods: A cross-sectional survey was developed and sent through the Canadian Neurosurgery Research Collaborative to every resident enrolled in a Canadian neurosurgery program as of April 1, 2016. Results: We analyzed 76 completed surveys of 146 eligible residents (52% response rate). The median age was 29 years, with 76% of respondents being males. The most popular subspecialties of interest for fellowship were spine, oncology, and open vascular neurosurgery. The most frequent self-reported number of worked hours per week was the 80- to 89-hour range. The majority of respondents reported a high level of happiness as well as stress. Sense of accomplishment and fatigue were reported as average to high and overall quality of life was low for 19%, average for 49%, and high for 32%. Satisfaction with work-life balance was average for 44% of respondents and was the only tested domain in which significant dissatisfaction was identified (18%). Overall, respondents were highly satisfied with their choice of specialty, choice of program, surgical exposure, and work environment; however, intimidation was reported in 36% of respondents and depression by 17%. Conclusions: Despite a challenging residency and high workload, the majority of Canadian neurosurgery residents are happy and satisfied with their choice of specialty and program. However, work-life balance, employability, resident intimidation, and depression were identified as areas of active concern.
Moving mesh methods provide an efficient way of solving partial differential equations for which large, localised variations in the solution necessitate locally dense spatial meshes. In one-dimension, meshes are typically specified using the arclength mesh density function. This choice is well-justified for piecewise polynomial interpolants, but it is only justified for spectral methods when model solutions include localised steep gradients. In this paper, one-dimensional mesh density functions are presented which are based on a spatially localised measure of the bandwidth of the approximated model solution. In considering bandwidth, these mesh density functions are well-justified for spectral methods, but are not strictly tied to the error properties of any particular spatial interpolant, and are hence widely applicable. The bandwidth mesh density functions are illustrated in two ways. First, by applying them to Chebyshev polynomial approximation of two test functions, and second, through use in periodic spectral and finite-difference moving mesh methods applied to a number of model problems in acoustics. These problems include a heterogeneous advection equation, the viscous Burgers’ equation, and the Korteweg-de Vries equation. Simulation results demonstrate solution convergence rates that are up to an order of magnitude faster using the bandwidth mesh density functions than uniform meshes, and around three times faster than those using the arclength mesh density function.
Here we present a study of the radio frequency eclipses of the black widow pulsar J1810+1744 at low frequencies, where we are most sensitive to small deviations in the effects of material along the line of sight. Utilising the simultaneous dual beamforming and interferometric (imaging) mode of LOFAR High Band Antenna, pulsar flux variations throughout the orbit are compared for the two observing techniques to test for the presence of scattering and absorption at eclipse orbital phases. Dispersion measure and scattering variations are used as a sensitive probe into outermost edges of the eclipsing material surrounding the companion star. We find the eclipsing medium to be variable on timescales shorter than the 3.6 hr orbital period, and propose cyclotron-synchrotron absorption as the most likely primary eclipse mechanism.
Background: The Canadian Neurosurgery Research Collaborative (CNRC) was founded in November 2015 as a resident-led national network for multicentre research. We present an annual report of our activities. Methods: CNRC meetings and publications were reviewed and summarized. The status of ongoing and future studies was collected from project leaders. Results: In its first year, the CNRC produced two papers accepted for publication in the Canadian Journal of Neurological Sciences: A CNRC launch letter and a study of operative volume at Canadian neurosurgery residency programs. Three manuscripts are in preparation: 1) a study of the demographics of Canadian neurosurgery residents, 2) an assessment of mobile devices usage patterns and 3) a validation study of the most utilized neurosurgery mobile apps. In addition, protocols for two multi-centre studies are currently undergoing national Research Ethics Board review: A retrospective study of the incidence and predictors of cerebellar mutism and a prospective registry of external ventricular drain procedures and complications. The network is now a registered not-for-profit organization endorsed by the Canadian Neurosurgical Society. Conclusions: The CNRC is a feasibile, relevant and productive resident-led national research network. As the CNRC matures, we look forward to expanding the scope and impact of its projects.
Background: Communicating with senior neurosurgical colleagues during residency necessitates a reliable and versatile smartphone. Smartphones and their apps are commonplace. They enhance communication with colleagues, provide the ability to access patient information and results, and allow access to medical reference applications. Patient data safety and compliance with the Personal Health Information Protection Act (PHIPA, 2004) in Canada remain a public concern that can significantly impact the way in which mobile smartphones are utilized by resident physicians Methods: Through the Canadian Neurosurgery Research Collaborative (CNRC), an online survey characterizing smartphone ownership and utilization of apps among Canadian neurosurgery residents and fellows was completed in April 2016. Results: Our study had a 47% response rate (80 surveys completed out of 171 eligible residents and fellows). Smartphone ownership was almost universal with a high rate of app utilization for learning and facilitating the care of patients. Utilization of smartphones to communicate and transfer urgent imaging with senior colleagues was common. Conclusions: Smartphone and app utilization is an essential part of neurosurgery resident workflow. In this study we characterize the smartphone and app usage within a specialized cohort of residents and suggest potential solutions to facilitate greater PHIPA adherence
Contamination of feedstuffs and ingredients with heavy metals poses a major problem for animal health and the transmission of toxic substances within the human food chain, as these elements can be accumulated into meat, egg and milk products. This paper reports on the levels of the three metals, arsenic, cadmium and lead, that exceed EU permitted levels, within premixes and complete feeds (total of 3417 samples) destined for a variety of animal species and taken from different countries during the period 2009–2016. For this period, 20% of all samples were contaminated at levels above the EU limit. In complete feed, ruminants were at the highest risk of exposure with 47% of samples being contaminated. Lead posed the major risk for minerals and cadmium posed the highest risk for premixes during the sampling period. When compared by country, contamination levels varied widely, with the highest contamination determined for Canada with 50% of samples being above the EU limit. To mitigate problems with heavy metals in animal feeds, due diligence in terms of sampling and testing is a necessary tool to evaluate level of risk. Research has shown that trace minerals can be sources of these heavy metals so the industry should be more diligent regarding their provider's quality guarantees. In addition, feeds identified with contamination should not be fed to animals to ensure that these heavy metal toxins are not passed into edible food products, thus providing safety in the food chain.
The following trial was conducted to investigate the effects of Se source (inorganic sodium selenite (SS) versus organic use Sel-Plex® (SP; Alltech Inc, Nicholasville, KY, USA)) on the performance, feathering and meat quality of 900, one-day-old male broilers over a 42 day growing period. Pens (n = 20) were randomly assigned to either: Diet A (no Se; negative control), Diet B as for diet A plus 0.3 mg/kg SS (positive control), Diet C as for diet A plus 0.2 mg/kg SP, Diet D as for diet A plus 0.3 mg/kg SP and Diet E as for diet A plus 0.4 mg/kg SP. From day 1 to 28, significant (P < 0.05) treatment effects were seen for feed intake and FCR, with values for the negative control being higher than for the diets containing Se. The best FCR was recorded for the diet containing 0.4 mg/kg SP. Breast meat yield for birds fed the negative control were lower than those fed selenite or SP supplemented diets (P < 0.05). Feather measurements on d 14, 28 and 42 of age showed that, although scores became poorer with age (4.9 at 14 d, 4.6 at 28 d and 3.6 at 42 d), they were unaffected (P > 0.05) by dietary Se inclusion. Numeric trends in favour of SP were seen in cooking losses in meat chilled for 24 hours and seven days. Cooking losses in meat frozen for seven days were significantly influenced by Se inclusion, whereby values for birds fed 0.3 and 0.4 mg/kg SP were significantly lower than values for birds fed inorganic selenite (P < 0.05). Tissue Se concentrations were highest for the SP diets. Meat oxidation from the birds fed SP was lower than for the birds fed no Se or SS. The results demonstrated that SP may be more advantageous in improving certain variables of performance and meat quality compared to inorganic sources of Se.
Background Currently, the literature lacks reliable data regarding operative case volumes at Canadian neurosurgery residency programs. Our objective was to provide a snapshot of the operative landscape in Canadian neurosurgical training using the trainee-led Canadian Neurosurgery Research Collaborative. Methods: Anonymized administrative operative data were gathered from each neurosurgery residency program from January 1, 2014, to December 31, 2014. Procedures were broadly classified into cranial, spine, peripheral nerve, and miscellaneous procedures. A number of prespecified subspecialty procedures were recorded. We defined the resident case index as the ratio of the total number of operations to the total number of neurosurgery residents in that program. Resident number included both Canadian medical and international medical graduates, and included residents on the neurosurgery service, off-service, or on leave for research or other personal reasons. Results: Overall, there was an average of 1845 operative cases per neurosurgery residency program. The mean numbers of cranial, spine, peripheral nerve, and miscellaneous procedures were 725, 466, 48, and 193, respectively. The nationwide mean resident case indices for cranial, spine, peripheral nerve, and total procedures were 90, 58, 5, and 196, respectively. There was some variation in the resident case indices for specific subspecialty procedures, with some training programs not performing carotid endarterectomy or endoscopic transsphenoidal procedures. Conclusions: This study presents the breadth of neurosurgical training within Canadian neurosurgery residency programs. These results may help inform the implementation of neurosurgery training as the Royal College of Physicians and Surgeons residency training transitions to a competence-by-design curriculum.
We empirically test separation of ownership and control (SOC) and the interaction of SOC with farmer effort on farm success using data from the U.S. Department of Agriculture's Agricultural Resource Management Survey. We use a two-stage least-squares approach with instrumental variables that proxy for participation constraints in binding incentive contracts. We find that the interaction has a significantly positive effect on success for grain farms and an insignificant effect for livestock farms. The results are consistent with hypotheses by Allen and Lueck (1998), but our model predicts that farms with SOC are likely to be more successful than farms without SOC despite exogenous uncertainty and agency costs.