38 resultados para Traditional borehole drilling

em CentAUR: Central Archive University of Reading - UK


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Although ways of thinking about the past have changed, in Britain the reporting of excavations has followed a series of shared conventions for nearly 100 years. This article considers two of them. It investigates the relationship between accounts of stratigraphic evidence and the publication of the associated artefacts and ecofacts and suggests that it results from the combination of two separate intellectual traditions in the late nineteenth century. It also identifies certain widely shared proportions between the separate components of excavation monographs published over a long period of time. Their existence has never been acknowledged. The excavation report has become a well-established literary genre and authors who are familiar with such texts unconsciously reproduce the same structures in their writing.

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Background: Inadvertent drilling on the ossicular chain is one of the causes of sensorineural hearing loss (HL) that may follow tympanomastoid surgery. A high-frequency HL is most frequently observed. It is speculated that the HL is a result of vibration of the ossicular chain resembling acoustic noise trauma. It is generally considered that using a large cutting burr is more likely to cause damage than a small diamond burr. Aim: The aim was to investigate the equivalent noise level and its frequency characteristics generated by drilling onto the short process of the incus in fresh human temporal bones. Methods and Materials: Five fresh cadaveric temporal bones were used. Stapes displacement was measured using laser Doppler vibrometry during short drilling episodes. Diamond. and cutting burrs of different diameters were used. The effect of the drilling on stapes footplate displacement was compared with that generated by an acoustic signal. The equivalent noise level (dB sound pressure level equivalent [SPL eq]) was thus calculated. Results: The equivalent noise levels generated ranged from 93 to 125 dB SPL eq. For a 1-mm cutting burr, the highest equivalent noise level was 108 dB SPL eq, whereas a 2.3-mm cutting burr produced a maximal level of 125 dB SPL eq. Diamond burrs generated less noise than their cutting counterparts, with a 2.3-mm diamond burr producing a highest equivalent noise level of 102, dB SPL eq. The energy of the noise increased at the higher end of the frequency spectrum, with a 2.3-mm cutting burr producing a noise level of 105 dB SPL eq at 1 kHz and 125 dB SPL eq at 8 kHz. In contrast, the same sized diamond burr produced 96 dB SPL eq at 1 kHz and 99 dB at 8 kHz. Conclusion:This study suggests that drilling on the ossicular chain can produce vibratory force that is analogous with noise levels known to produce acoustic trauma. For the same type of burr, the larger the diameter, the greater the vibratory force, and for the same size of burr, the cutting burr creates more vibratory force than the diamond burr. The cutting burr produces greater high-frequency than lower-frequency vibratory energy.

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E-Learning is an emerging tool that uses advanced technology to provide training and development in higher education and within industry. Its rapid growth has been facilitated by the Internet and the massive opportunities in global education. The aim of this study is to consider how effective and efficient e-learning is when integrated with traditional learning in a blended learning environment. The study will provide a comparison between purist ELearning and Blended learning environment. The paper will also provide directions for the blended learning environment which can be used by all the three main stakeholder student, tutors and institution to make strategic decision about the learning and teaching initiatives. The paper concludes that blended learning approaches offer the most flexible and scalable route to E-Learning.