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A thermally tough, low-melting, low-viscosity glass composition is described that has been used as a fusion mixture in sample preparations for X-ray fluorescence analysis.
The fusion mixture is cast into a glass disk which, after annealing, is used directly for the X-ray measurements. Problems arising from disk surface imperfections have, in the past, been minimized by either prolonged polishing of the glass surface, or grinding the disk and pressing the powder into a peltet. This practice has been eliminated through the incorporation of appropriate internal standard elements into the glass fusion mixture. This approach also minimizes interelement effects and errors due to instrumental drift.
A variety of corrosion products have been successfully analyzed by this method. Results will be given.
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
The quality of hoof horn is related to 3 factors: architecture of the Stratum corneum (number of tubules and inter-tubular space), cellular factors (type of keratinization, orientation of keratin fibres) and inter-cellular factors (amount and chemical composition of the inter-cellular substance (Pellman et al., 1993). Kempson and Logue (1993) related poor hoof horn quality at 1 month before calving to the occurrence of moderate to severe solar haemorrhage at 10 to 20 weeks after calving. The objective of this experiment was to develop the use of texture analysis as a method to measure the structural strength of hoof sole tissue and assess the influence of sample width and bruising on structural strength.
Mechanical properties of the hoof horn such as hardness, elastic modulus, bending stiffness and fracture toughness were influenced by the moisture content of the hoof horn (Collins et al., 1998; Baillie et al.; 2000). The moisture content of the hoof horn has been found to be affected by the micro-architecture and biochemical composition of the horn and by external factors such as humidity, chemicals and microbiological factors (Budras and Mulling, 1998). The aim of the experiment was to determine the influence of the moisture content and of storage methods, such as refrigerating in plastic bags and freezing, over the punch resistance and elastic modulus of the bovine hoof horn. Storage methods were studied for the determination of an experimental protocol in further research.
We present soft X-ray photomosaic images of two supernova remnants, Puppis A and IC 443, constructed from a series of exposures by the Einstein imaging instruments. The complex morphologies displayed in these images reflect the interaction between “middle-aged” supernova remnants and various components of the interstellar medium. Surface brightness variations across Puppis A suggest that inhomogeneities on scales from 0.2 to 30 pc are present in the interstellar medium, while the structure of IC 443 is apparently dominated by the interaction between the remnant and a giant molecular cloud.
We review results obtained with the Focal Plane Crystal Spectrometer (FPCS) on the Einstein Observatory. Clear evidence is found for departures from ionization equilibrium in the interior of Puppis A. This comes from the observed weakness of the forbidden lines relative to the resonance lines for the He - like triplets of O VII and Ne IX. However, it is shown that this departure from equilibrium does not alter our conclusion, based on previous FPCS results, that O and Ne are overabundant relative to Fe. The spectrum of N132D shows strong O VIII emission and very weak Fe emission, suggesting an even greater O/Fe abundance enhancement than in Puppis A. In the Cygnus Loop, the O to Ne abundance ratio is approximately solar; we have no information about Fe. The O VII triplet shows clear evidence for departures from ionization equilibrium in the Cygnus Loop. The spectrum of Tycho's SNR contains lines from ionization stages of Fe XVII through Fe XXIII and XXIV, indicating that a wide range of ionization conditions are present. Cas A and Kepler's SNR show relatively less emission from the higher ionization stages. For Tycho, we measured the strength of the strong Si XIII lines, and we find that a many-fold overabundance of Si relative to Fe is required regardless of the equilibrium state of the emitting plasma (confirming the Solid State Spectrometer results). On a separate topic, the completed analysis of X-ray Doppler shifts in Cas A suggests that the emitting material is concentrated in a ring that is inclined to the line of sight and is expanding at ~5000 km s−1.
A powerful young supernova remnant (SNR) similar to Cas A has recently been discovered in the irregular galaxy NGC 4449. We have obtained X-ray, optical and ultraviolet data which allow us to investigate possible models for this object and estimate its age. Several lines of argument indicate a massive star of order 25 M⊙ as the precursor to this remnant. If the x-ray emission is attributed to a reverse shock in the ejecta, the remnant should be ∼ 120 years old.
High resolution X-ray spectroscopy of the brightest knot of emission in the Puppis A supernova remnant shows that it is made up of ionizing plasma, far from equilibrium. Flux measurements in several X-ray lines enable us to determine the non-equilibrium conditions: electron temperature, ion populations, and time since the knot was heated by the supernova shock. Imaging and spectroscopic data from the Einstein Observatory together suggest that this knot is a cloud of density about 10 cm−3 which has recently been shocked to a temperature 7 × 106 K. Radio and optical data on the region appear consistent with this picture.
A recent theoretical literature highlights the role of endogenous firm entry as an internal amplification mechanism of business cycle fluctuations. The amplification mechanism works through the competition effect (CE) and the variety effect (VE). This paper tests the significance of this amplification mechanism, quantifies its importance, and disentangles the CE and VE. To this end, we estimate a medium-scale real business cycle model with firm entry for the U.S. economy. The CE and VE are estimated to be statistically significant. Together, they amplify the volatility of output by 8.5% relative to a model in which both effects are switched off. The CE accounts for most amplification, whereas the VE only plays a minor role.
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: No standardized method of resident operative-case logging exists. Our study sought to develop a standardized form used by residents to log operative-cases. Methods: Members of the Canadian Neurosurgery Research Collaborative (CNRC), a national resident-led research organization have created a standardized document based on the current Royal College objectives for operative procedures (section 5). Modifications to structure and content will be guided via consensus from Canadian neurosurgery program-directors. Results: Program directors in each CNRC collaborative institution will be asked to modify the standardized form. The CNRC currently involves thirteen of the fourteen Canadian neurosurgery residency programs. Additional consensus, if necessary, can be reached at the Royal College meeting for program directors of neurosurgery March 20th 2017. Conclusions: A standardized operative-case log represents the first step in a prospective study towards compiling operative volume of all Canadian neurosurgical residents over one academic year. Such data will be essential to guide informed decisions with regard to Royal College requirements as Canadian neurosurgical programs transition to a competency based framework.
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
Hulless oats are of interest as an alternative to corn and wheat in organic poultry diets because they offer potential to enhance agrobiodiversity and produce locally grown feeds both within and outside of corn-growing regions. Hulless oats are easily certified GM-free and have demonstrated nutritional value for poultry. A feeding study was carried out to examine: (i) the effects of substituting corn, wheat or a fraction of each with hulless oats in organic layer diets, and (ii) the importance of oat variety in feed performance. Productivity and economic implications in the context of current organic markets were explored. Experimental diets included an oat-free control, Oat + corn, Oat + wheat and Oat + corn + wheat, each of which was formulated with three hulless oat varieties, AC Gwen, Paul and Streaker. All but the control diet included oats at 200 g kg−1. Three hundred Hy-Line Brown hens were individually caged and allocated to diets in groups of 10 in a completely randomized design with three replicates per diet. Experimental diets were fed between 24 and 32 weeks of age during which time hen health, egg production and egg quality indicators were monitored. Results indicated that hulless oats had no negative effects on hen health and productivity. On the basis of current organic feed ingredient prices and an estimated cost of USD 533 mt−1 for production of oats in the study region, oat containing diets were more expensive than the oat-free control. In an evaluation of revenue based on current market prices for organic eggs, the additional cost was completely offset by larger egg sizes of hens on oat containing diets. There were no major differences associated with oat variety.
The GRASP mission (Gamma-ray Astronomy with Spectroscopy and Positioning) is currently under study as an ESA space astronomy mission to be launched in the mid 90's. GRASP is designed as a high quality spectral imager (E/ΔE ≈ 500 at 1 Mev) with positioning to the arc minute level within a large field of view (≈7°) which operates over a wide spectral range (30 Kev-100 Mev) with a 3σ sensitivity of typically 10 mcrab or better over the entire operational range within an observational period of ≈105 seconds. In this paper, we will mainly discuss the capability of the instrument with respect to the study of both point source and diffuse source measurements of the galactic center region.
Background: The goals of evidence-based neurosurgery are to improve surgical outcomes, reduce complications, and provide an objective basis for altering practice. The need for higher quality studies, typically prospective and multicentre, has been growing especially in light of the evolving complexity of neurosurgical interventions and heterogeneity of patient populations. In the United Kingdom (UK), trainee-led research collaboratives have been established to tackle this problem. Therefore, we sought to evaluate the potential role for a resident-led research collaborative in neurosurgery in Canada based on the UK experience. Methods: A literature review of trainee-led collaboratives was conducted utilizing PubMed and Medline. Identified articles were reviewed for study quality and clinical relevance to explore the potential benefits of collaboratives. Results: In the UK, 27 collaboratives have been established in various specialties by trainees. Some published high quality trials with implications on their clinical fields. Evidence suggests that such endeavors improves trainees’ research skills and may help cultivate a research culture tailored towards clinical trials. Conclusions: Given the growing evidence for research collaboratives in the UK, we propose launching the Canadian Neurosurgery Research Collaborative (CNRC) which currently represents 12 out of 14 neurosurgery programs in Canada, and planning its first multicenter prospective study.
Background: The Canadian Neurosurgery Research Collaborative (CNRC) is a trainee-led multi-centre collaboration made up of representatives from 12 of 14 neurosurgical centres with residency programs. To demonstrate the potential of this collaborative network, we gathered administrative operative data from each centre in order to provide a snapshot of the operative landscape in Canadian neurosurgery. Methods: Residents from each training program provided adult neurosurgical operative data for the 2014 calendar year, including the number of surgeries in the subcategories cranial, spinal, and peripheral nerve. Because some residency programs have surgeries distributed among more than one hospital, we calculated mean case load per residency program and per hospital. Results: Interim results from 6 neurosurgery residency programs are presented (with data from other programs forthcoming). Overall, there were on average 2,352 operative cases per residency program (n=6) and 1,176 operative cases per adult hospital (n=12). Among 5 programs with more detailed operative data, the mean numbers of cranial, spinal, peripheral nerve, and miscellaneous surgeries per residency program were 757 (47%), 487 (30%), 47 (3%), and 319 (20%) respectively. Conclusions: We show as a proof-of-concept that a trainee-led nation-wide research collaborative can generate meaningful data in a Canadian context.