[Complications due to the waiting period for dental treatment under general anaesthesia]

Item does not contain fulltextThe capacity for dental treatment under general anaesthesia is limited. Clearly, the demand for treatment exceeds the supply. A written questionnaire completed by all 403 patients who were treated in 2003 in a centre for special dentistry under general anaesthesia, or their parents or carers, revealed that the median time between referral and the first consultation was 8 weeks.The median time between the first consultation and treatment was also 8 weeks. The waiting period for children was longer than that for adults, with that for 4- and 5-year-olds the longest of all. During the waiting period, 43% of the patients developed complications, such as oral pain and problems with eating and sleeping. Children developed complications more often than adults. With every week of waiting, the likelihood of children developing complications increased by 6.7%

Mass spectrometric detection of short-living radicals produced by a plasma needle

A plasma needle is a radio-frequency (rf) micro-discharge operated in a mixt. of helium and air at atm. pressure. This source is designed for medical treatment of living tissues. Therapeutic effects of plasma treatment depend on generation of short-living active radicals: reactive oxygen and nitrogen species (ROS/RNS). In this work we det. the concn. of several ROS and RNS (at. oxygen, nitrogen and hydroxyl radical) by means of threshold ionization mass spectrometry. It is shown that mol. oxygen and nitrogen are substantially dissocd. in the plasma. At. nitrogen and oxygen are the most abundant radicals: the densities are on av. few times 10-4. Hydroxyl radicals are less abundant (10-5 fraction of the total gas d.). As expected, the densities of active species increase with increasing plasma power. Spatial (axial) distributions have been detd.; the radical d. reaches a max. at 2.5 mm away from the rf powered electrode, and it decreases at distances larger than 3.5 mm. The amt. of active radical species is reasonably high, which explains the effectiveness of plasma in bacterial inactivation and tissue treatment. [on SciFinder (R)

Mass spectrometric detection of short-living radicals produced by a plasma needle

A plasma needle is a radio-frequency (rf) micro-discharge operated in a mixt. of helium and air at atm. pressure. This source is designed for medical treatment of living tissues. Therapeutic effects of plasma treatment depend on generation of short-living active radicals: reactive oxygen and nitrogen species (ROS/RNS). In this work we det. the concn. of several ROS and RNS (at. oxygen, nitrogen and hydroxyl radical) by means of threshold ionization mass spectrometry. It is shown that mol. oxygen and nitrogen are substantially dissocd. in the plasma. At. nitrogen and oxygen are the most abundant radicals: the densities are on av. few times 10-4. Hydroxyl radicals are less abundant (10-5 fraction of the total gas d.). As expected, the densities of active species increase with increasing plasma power. Spatial (axial) distributions have been detd.; the radical d. reaches a max. at 2.5 mm away from the rf powered electrode, and it decreases at distances larger than 3.5 mm. The amt. of active radical species is reasonably high, which explains the effectiveness of plasma in bacterial inactivation and tissue treatment. [on SciFinder (R)

A plasma needle generates nitric oxide

Generation of nitric oxide (NO) by a plasma needle is studied by means of mass spectrometry. The plasma needle is an atm. glow generated by a radio-frequency excitation in a mixt. of helium and air. This source is used for the treatment of living tissues, and nitric oxide may be one of the most important active agents in plasma therapy. Efficient NO generation is of particular importance in the treatment of cardiovascular diseases. Mass spectrometric measurements have been performed under various plasma conditions; gas compn. in the plasma and conversion of feed gases (nitrogen and oxygen) into other species has been studied. Up to 30% of the N2 and O2 input is consumed in the discharge, and NO has been identified as the main conversion product. [on SciFinder (R)

A plasma needle generates nitric oxide

Generation of nitric oxide (NO) by a plasma needle is studied by means of mass spectrometry. The plasma needle is an atm. glow generated by a radio-frequency excitation in a mixt. of helium and air. This source is used for the treatment of living tissues, and nitric oxide may be one of the most important active agents in plasma therapy. Efficient NO generation is of particular importance in the treatment of cardiovascular diseases. Mass spectrometric measurements have been performed under various plasma conditions; gas compn. in the plasma and conversion of feed gases (nitrogen and oxygen) into other species has been studied. Up to 30% of the N2 and O2 input is consumed in the discharge, and NO has been identified as the main conversion product. [on SciFinder (R)

Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry

Fractional no. d. measurements for a radiofrequency plasma needle operating at atm. pressure were obtained using a mol. beam mass spectrometer (MBMS) system designed for diagnostics of atm. plasmas. The MBMS system comprises three differentially pumped stages and a mass/energy analyzer and includes an automated beam-to-background measurement facility as a software-controlled chopper mechanism. The automation of the beam modulation allows the neutral components in the plasma to be rapidly and accurately measured using the mass spectrometer by threshold ionization techniques. Data are reported for plasma generated by a needle plasma source operated using a He/air mixt. In particular, data for the conversion of atm. O and N into nitric oxide are discussed with ref. to its significance for medical applications such as disinfecting wounds and dental cavities and for microsurgery. [on SciFinder (R)

“There is a worksheet to be followed”: A case study of a science teacher's use of learning support texts for practical work

Drawing on the notion of the 'didactical transposition' of curriculum texts, this paper takes a critical look at why one science teacher still persists with a traditional teacher-centred approach towards practical work. It flows from a multi-case study on the instructional decision-making of Grade 9 Natural Science teachers currently implementing the new outcomes-based Curriculum 2005 in South Africa. Data were collected through classroom observations, pre-lesson and post-lesson interviews, video-stimulated recall sessions as well as content analysis of various artefacts. The paper describes how and explains why the respondent uses the Learner Support Material (LSM) in a rather mechanical manner to shape practical work for his learners