Search results for: Retief Broodryk

Authors: Pieter van den Berg, Retief Broodryk, Bert Moolman

Abstract:

Firstly, this study aimed to identify which performance indicators (PIs) discriminate between winning and losing university-level Rugby Union (RU) teams and, secondly, to compare the significant PIs in RU and Rugby Union Sevens (RS) at university level. Understanding the importance of PIs and their effect on match outcomes could assist coaching staff to prioritise specific game aspects during training to increase performance. Twenty randomly selected round-robin matches of the 2018 Varsity Cup (n=20), and Varsity Sports sevens (n=20) tournaments were analysed. A linear mixed model was used to determine statistical significant differences set at p≤0.05 while effect size was reported according to Cohen's d value. Results revealed that various PIs discriminated between winning and losing RU teams and that specific PIs could be observed as significant in both RU and RS. Therefore, specific identified tactical aspects of RU and RS should be prioritised to optimise performance

Keywords: match success, notational analysis, performance analysis, rugby, video analysis

Procedia PDF Downloads 72

Authors: P. A. Broodryk, A. F. Van Der Merwe, H. W. J. P. Neomagus

Abstract:

The production of the clear liquid fertilizer ammonium polyphosphate (APP) is best achieved by the pyrolysis of urea phosphate, as it produces a product that is free from any of the impurities present in the raw phosphoric acid it was made from. This is a multiphase, multi-step reaction that produces carbon dioxide and ammonia as gasses and ammonium polyphosphate as liquid products. The polyphosphate chain length affects the solubility and thus the applicability of the product as liquid fertiliser, thus proper control of the reaction conditions is thus required for the use of this reaction in the production of fertilisers. This study investigates the reaction kinetics of the aforementioned reaction, describing a mathematical model for the kinetics of the reaction along with the accompanying rate constants. The reaction is initially exothermic, producing only carbon dioxide as a gas product and ammonium diphosphate, at higher temperatures the reaction becomes endothermic, producing ammonia gas as an additional by-product and longer chain polyphosphates, which when condensed too far becomes highly water insoluble. The aim of this study was to (i) characterise the pyrolysis reaction of urea phosphate by determining the mechanisms and the associated kinetic constants, and (ii) to determine the optimum conditions for ammonium diphosphate production. A qualitative investigation was also done to find the rate of hydrolysis of APP as this provides an estimate of the shelf life of an APP clear liquid fertiliser solution.

Keywords: ammonium polyphosphate, kinetics, pyrolysis, urea phosphate

Procedia PDF Downloads 157

Authors: Adele Broodryk, Cindy Pienaar, Martinique Sparks, Ben Coetzee

Abstract:

Background: Cold water immersion (CWI) is a popular recovery modality utilised. However, discrepancies exist regarding the results over a 48 hour recovery period. Aim: To evaluate the effects of CWI and passive recovery (PAR) on a range of haematological and physical parameters over a 48-hour using a cross-sectional, pre-post-test design. Subjects and Methods: Both the and physical parameters were evaluated at baseline, after a 15-min fitness session, and at 0, 24 and 48 hours post-recovery in 23 male university rugby players. The CWI group sat in a cold water pool (8°C) for 20 min whereas the PAR group remained seated. Results: At 0 hours post-CWI, three (blood lactate (BLa-), Sodium (Na+) and haemoglobin) returned to baseline values, however Vertical Jump Test (VJT) height results decreased whereas after PAR it improved. From 0 to 24 and/or 48 h, four (Partial Oxygen (PO2) VJT-height, plasma glucose, and Na+) significantly increased (p ≤ 0.05) in either and/or both groups. Significant intergroup differences (p ≤ 0.05) were noticed in the physical tests. Conclusions: PAR is superior as an acute modality (0 hours) due to CWI cooling the body down. However, CWI demonstrates advantageous over a 24-hour period in a wide range of haematological variables.

Keywords: cryotherapy, recuperation, haematological, rugby

Procedia PDF Downloads 264

Authors: Jeanne-Mari Retief

Abstract:

As of November 2016, three African states have withdrawn from the International Criminal Court (ICC) and more are expected to follow. The alleged abuse of universal jurisdiction and targeting of African states by the ICC motivated the withdrawals. These historical exits raise many questions, especially in regard to the adequate investigation and prosecution of international crimes in a continent with a history of impunity. Even though African courts exist and one more is proposed, many issues remain i.e. adequate access to the courts, the extent of the courts’ jurisdiction, and proposed methods of effectively dealing with international crimes in Africa. This paper seeks to address the practical effects of the withdrawal from the ICC and the problems posed through utilizing regional courts. It will specifically look at the practical challenges existing courts face, the lack of access to the latter, issues concerning the proposed African Court for Justice and Human Rights, and the shocking promotion of impunity in Africa. These all have severe implications for African citizens and victims of the most heinous crimes. The mantra of African solutions to African problems places an important duty on states to ensure the actual provision of these solutions, which can only be achieved through a critical analysis of the questions above.

Keywords: ACJHR, Africa, impunity, justice, Malabo protocol

Procedia PDF Downloads 222