Ultrasound examination of the head and neck

Structure of this thesis Part I deals with basic bio-physics and bio-effects of clinical ultrasound of the head and neck. Furthermore, the ultrasound anatomy of the head and neck is described and illustrated. In addition, the technique of ultrasound guided fine needle aspiration biopsy (UGFNAB) is outlined. In part H the significThe fallibility of palpation and current diagnostic tests to detect subclinical (occult) nodal disease in patients with upper aero-digestive tract cancer results in imperfect staging, improper treatment and delayed identification of recurrences in the neck. With continuous advances in imaging techniques (CT, MRI), the sensitivity for the detection of cervical lymph nodes is true enough increasing, while the specificity for detecting metastasis with these techniques remains low. An ideal diagnostic test should be suitable for screening, demonstrating and excluding cervical metastasis. In addition, the test should have no morbidity. The diagnostic work-up of patients with a head and neck mass is another important diagnostic problem. Although careful history taking and thorough ENT examination may be sufficiently characteristic to permit diagnosis, every clinical diagnosis will be associated with a certain degree of uncertainty. This uncertainty is mainly deterntined by the lintitations of clinical exantination in differentiating between solid and cystic lesions on one hand, and the establishment of exact anatontic properties on the other. In addition, there is a proportion of lesions which, despite thorough diagnostic work-up. remain elusive and are subjected to premature surgical exploration. CT may contribute to the pre-treatment work-up but is associated with several important drawbacks: high costs, lintited availability, radiation exposure and the need to use intravenous contrast. A simple, uniformly reliable, non-invasive and cost-effective test would be beneficial in these cases. The low accuracy of current diagnostic methods in the assessment of cervical nodal disease and the difficulties to evaluate head and neck masses actuated the present study, which started in 1984. By that time small-parts ultrasound transducers had been developed. These high-frequency transducers seemed better suited for examination of the superficial tissues in the head and neck region than earlier ultrasound equipment. In close cooperation between the departments of Radiology and Otorhinolaryngology and Head and Neck Surgery. a prospective study on the value of ultrasound examination of the head and neck was designed. The purpose of this study was to deterntine the values of palpation and ultrasound examination in the assessment of cervical metastatic disease in patients with upper aerodigestive tract cancer and in the evaluation of head and neck masses. An additional purpose of this study was to appraise the adjunctive value of cytologic exantination in the above mentioned clinical problem

Student teachers' practical knowledge, discipline strategies, and the teacher-class relationship

Social aspects of the learning environment, also called classroom climate, are important for students__ cognitive and affective learning outcomes. In this thesis the classroom climate is operationalised by means of two components: the teacher-class relationship and classroom discipline. The teacher-class relationship is described with the dimensions of control and affiliation, and classroom discipline is described with sensitive, directive and aggressive discipline strategies. Practical knowledge is thought to be extremely relevant in classroom situations that call for immediate teacher actions, such as disorderly situations, or students__ misconduct. A merit of this thesis is that it showed that in the context of education, it is worthwhile to perceive discipline strategies as consisting of three (sensitive, directive and aggressive) instead of two (sensitive and coercive) factors. This thesis also showed that there are clear and meaningful relations between discipline strategies and the teacher-class relationship. This connection appeared to be much stronger than the direct connection between student teachers__ practical knowledge and the teacher-class relationship. However, teachers__ practical knowledge was found to be related to the way the student teacher disciplines. Results of this thesis provide insight into which components of practical knowledge are related to student teachers__ discipline strategies. Classroom climate; classroom management; student teachers; interpersonal theory; discipline strategies; practical knowledge; teacher-class relationshipUBL - phd migration 201

A comparison of faecal analysis with backtracking to determine the diet composition and species preference of the black rhinoceros (Diceros bicornis minor)

The diet of black rhinoceros (Diceros bicornis minor) was studied using backtracking and faecal analysis in South Africa. Both methods yielded different results, with a large bias for dominant species. Results of backtracking showed that the rhinos browsed on 80 plant species. Grasses comprised 4.5% of the diet in the faecal analysis, but were not recorded during the backtracking. The backtracking method, along with a measure of forage availability, was used to identify two groups of plant species, those species taken in a higher proportion than available in the field and those taken in a lower proportion. Chemical analyses showed that these two species groups were similar in in vitro digestibility, macro-elements and fibre constituents. Mean bite size and species contribution to the diet were not correlated with any of the forage quality parameters, indicating that rhinos were not maximising nutrient intake or minimising fibre intake of these consumed plant species

An atomic force microscope operating at hypergravity for in situ measurement of cellular mechano-response

We present a novel atomic force microscope (AFM) system, operational in liquid at variable gravity, dedicated to image cell shape changes of cells in vitro under hypergravity conditions. The hypergravity AFM is realized by mounting a stand-alone AFM into a large-diameter centrifuge. The balance between mechanical forces, both intra- and extracellular, determines both cell shape and integrity. Gravity seems to be an insignificant force at the level of a single cell, in contrast to the effect of gravity on a complete (multicellular) organism, where for instance bones and muscles are highly unloaded under near weightless (microgravity) conditions. However, past space flights and ground based cell biological studies, under both hypogravity and hypergravity conditions have shown changes in cell behaviour (signal transduction), cell architecture (cytoskeleton) and proliferation. Thus the role of direct or indirect gravity effects at the level of cells has remained unclear. Here we aim to address the role of gravity on cell shape. We concentrate on the validation of the novel AFM for use under hypergravity conditions. We find indications that a single cell exposed to 2 to 3 × g reduces some 30–50% in average height, as monitored with AFM. Indeed, in situ measurements of the effects of changing gravitational load on cell shape are well feasible by means of AFM in liquid. The combination provides a promising technique to measure, online, the temporal characteristics of the cellular mechano-response during exposure to inertial forces