A video analysis of head injuries satisfying the criteria for a head injury assessment in professional Rugby Union: a prospective cohort study

Objectives Concussion is the most common match injury in professional Rugby Union, accounting for 25% of match injuries. The primary prevention of head injuries requires that the injury mechanism be known so that interventions can be targeted to specifically overall incidence by focusing on characteristics with the greatest propensity to cause a head injury. Methods 611 head injury assessment (HIA) events in professional Rugby Union over a 3-year period were analysed, with specific reference to match events, position, time and nature of head contact. Results 464 (76%) of HIA events occur during tackles, with the tackler experiencing a significantly greater propensity for an HIA than the ball carrier (1.40 HIAs/1000 tackles for the tackler vs 0.54 HIAs/1000 tackles for the ball carrier, incidence rate ratio (IRR) 2.59). Propensity was significantly greater for backline players than forwards (IRR 1.54, 95%CI 1.28 to 1.84), but did not increase over the course of the match. Head to head contact accounted for the most tackler HIAs, with the greatest propensity. Conclusions By virtue of its high propensity and frequency, the tackle should be the focus for interventions that may include law change and technique education. A specific investigation of the characteristics of the tackle is warranted to refine the approach to preventative strategies

Avoiding acyclovir neurotoxicity in patients with chronic renal failure undergoing haemodialysis

Acute neurotoxicity following the administration of the recommended oral dose of acyclovir (800 mg twice daily) to dialysis-dependent patients is increasingly recognised. This suggests that the recommended dose is too high. Little is known of the pharmacokinetics of oral acyclovir in dialysis patients. We studied 7 patients with oliguric end stage renal failure receiving haemodialysis. Following haemodialysis, each patient received a single 800-mg tablet of acyclovir. Plasma acyclovir levels were monitored over the next 48 h as well as before and after the next routine dialysis. Peak plasma levels were achieved at 3 h (12.54 ± 1.76 μM, range 8.5 - 17.5 μM) with the half-life calculated to be 20.2 ± 4.6 h. Mean plasma levels of 6.29 ± 0.94 μM were within the quoted range to inhibit herpes tester virus (4-8 μM) at 18 h. Haemodialysis (4-5 h) eliminated 51 ± 11.5% of the acyclovir which remained at 48 h. Computer modelling of various dose modifications suggests that a loading dose of 400 mg and a maintenance dose of 200 mg twice daily is sufficient to maintain a mean plasma acyclovir level of 6.4 ± 0.8 μM A further loading dose (400 mg) after dialysis would raise the residual acyclovir concentration by 6.1 ± 1.0 μM. Such a dose modification should prevent neurotoxicity, whilst the rapid elimination of acyclovir by a single haemodialysis treatment provides both a diagnostic and therapeutic tool when toxicity is suspected.Peer reviewe

N,N'-diisopropylthiourea and N,N'-dicyclohexyl-thiourea zinc(II) complexes as precursors for the synthesis of ZnS nanoparticles

The single X-ray crystal structures of zinc (II) complexes of N,N'-diisopropylthiourea and N,N' dicyclohexylthiourea weredetermined.These complexes, similar to other alkylthioureas, were found to be effective as precursors for the preparation of hexadecylamine-capped ZnS nanoparticles. The complexes are air-stable, easy to prepare and inexpensive. They pyrolyse cleanly to give high-quality ZnS nanoparticles, which show quantum confinement effects in their absorption spectra and close to band-edge emission. Their broad diffraction patterns are typicalof nanosized particles while their transmission electronmicroscopy images showed agglomerates of needle-like platelet nanoparticles

N,N'-diisopropylthiourea and N,N'-dicyclohexyl-thiourea zinc(II) complexes as precursors for the synthesis of ZnS nanoparticles

The single X-ray crystal structures of zinc (II) complexes of N,N'-diisopropylthiourea and N,N' dicyclohexylthiourea weredetermined.These complexes, similar to other alkylthioureas, were found to be effective as precursors for the preparation of hexadecylamine-capped ZnS nanoparticles. The complexes are air-stable, easy to prepare and inexpensive. They pyrolyse cleanly to give high-quality ZnS nanoparticles, which show quantum confinement effects in their absorption spectra and close to band-edge emission. Their broad diffraction patterns are typicalof nanosized particles while their transmission electronmicroscopy images showed agglomerates of needle-like platelet nanoparticles

N,N’-diisopropylthiourea and N,N’-dicyclohexyl-thiourea zinc(II) complexes as precursors for the synthesis of ZnS nanoparticles

The single X-ray crystal structures of zinc (II) complexes of N,N’-diisopropylthiourea and N,N’ dicyclohexylthiourea weredetermined.These complexes, similar to other alkylthioureas, were found to be effective as precursors for the preparation of hexadecylamine-capped ZnS nanoparticles. The complexes are air-stable, easy to prepare and inexpensive. They pyrolyse cleanly to give high-quality ZnS nanoparticles, which show quantum confinement effects in their absorption spectra and close to band-edge emission. Their broad diffraction patterns are typicalof nanosized particles while their transmission electronmicroscopy images showed agglomerates of needle-like platelet nanoparticles

Why are Algebra word problems difficult? Using tutorial log files and the power law of learning to select the best fitting cognitive model

Abstract. Some researchers have argued that algebra word problems are difficult for students because they have difficulty in comprehending English. Others have argued that because algebra is a generalization of arithmetic, and generalization is hard, it’s the use of variables, per se, that cause difficulty for students. Heffernan and Koedinger [9] [10] presented evidence against both of these hypotheses. In this paper we present how to use tutorial log files from an intelligent tutoring system to try to contribute to answering such questions. We take advantage of the Power Law of Learning, which predicts that error rates should fit a power function, to try to find the best fitting mathematical model that predicts whether a student will get a question correct. We decompose the question of “Why are Algebra Word Problems Difficult? ” into two pieces. First, is there evidence for the existence of this articulation skill that Heffernan and Koedinger argued for? Secondly, is there evidence for the existence of the skill of “composed articulation ” as the best way to model the “composition effect” that Heffernan and Koedinger discovered?