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We report a rare presentation of ancient schwannoma of the oesophagus, management of which required tracheal resection.
A 40-year-old woman was referred to our hospital with a six-year history of progressively worsening stridor. She had undergone laser excision of a tracheal tumour thrice in the past. Fibre-optic bronchoscopy showed a tumour arising from the posterior wall of the trachea. Computed tomography scanning showed evidence of extension along the retrotracheal plane. The patient required tracheal resection and anastomosis due to significant involvement of the posterior tracheal wall. The mass was seen to be arising from the oesophagus, and was able to be enucleated from the oesophageal wall. Histopathology was typical of an ancient schwannoma.
This case emphasises the need to consider oesophageal schwannomas in the differential diagnosis of posterior tracheal tumours; it also highlights the need for careful pre-operative assessment in the management of these tumours in order to avoid complications.
MEMS based microcantilevers have been employed as sensors in both liquid and ambient conditions. One scheme for detection is based upon monitoring the change in microcantilever resonant frequency as a function of the adsorbed analyte concentration. However, the sensitivity is limited by the accuracy of the frequency measurements, which is a function of the Q-factor of the vibrating element and the measurement bandwidth. In this paper, we present a feedback scheme for self-locking amplification of the small-amplitude thermal oscillations of the microcantilever. Using this approach, we demonstrate an improvement in the Q-factor by two to three orders of magnitude as compared to that of the undriven microcantilever. Use of this technique eliminates the need for lock-in detection and results in improved response times for sensor applications. Experiments using the proposed feedback amplification technique show improved sensitivity for the detection of biological molecules in liquids, and for adsorbed vapors under ambient conditions.
To investigate the dynamics of nasopharyngeal colonization with Streptococcus pneumoniae,
and to determine the prevalent serogroups/types (SGT) and their antimicrobial susceptibility,
we studied 100 infants attending our well-baby clinic. Nasopharyngeal swab specimens were
obtained at 6, 10, 14, 18 and 22 weeks and at 9 and 18 months of age and submitted for
culture, serotyping and antimicrobial susceptibility testing of S. pneumoniae. Colonization with
pneumococcus was seen on at least one occasion in 81 infants. The median age of acquisition
was 11 weeks and the median duration of carriage was 1·3 months. The common SGTs
identified were 6, 19, 14 and 15. SGT 1, which was a common invasive isolate in children in
our hospital during this period, was not isolated from these children. Sequential colonization
by 2, 3 or 4 SGTs was observed in 18, 5 and 2 children, respectively. Resistance to penicillin,
chloramphenicol, cotrimoxazole and erythromycin was observed in 0, 13 (6%) 11 (5%) and
5 (3%) isolates, respectively. There was a significant difference in susceptibility to
cotrimoxazole between colonizing and invasive isolates (5% vs. 40%, P<0·0001).
Increased rate of material removal and a high degree of surface finish during the polishing of diamond is desirable not only in the technology of gem diamond processing, but also for the tribological, optical, electronic and thermal management applications of chemical vapor deposited (CVD) diamond films. Conventional mechanical abrasion techniques, though with comparatively larger material removal rates, have limitations to the surface finish attainable due to the inherent nature of the material removal process - predominantly micro-chipping. Chemical etching of diamond, on the other hand is understood to involve atom by atom material removal preferentially from defect sites, but with lower overall material removal rates. It has been realized that a combination of these two processes, leading to chemi-mechanical polishing, may therefore provide better overall results, in terms of material removal and surface finish.
In recent work on chemi-mechanical polishing of diamond, KNO3 - an oxidizing agent shown to be a dislocation etchant for diamond by Tolansky and Patel in the 1950s - has been employed. Dislocation etchants usually lead to the formation of block patterns on diamond surfaces under the usual etching conditions because of the normal and tangential etch rates (Vn and Vt) of comparable magnitude. KNO3 therefore would impose a limitation on the degree of surface finish attainable when used for chemi-mechanical polishing. However, if a chemical etchant and conditions for which Vn ≪ Vt could be established for diamond surfaces, better chemical polishing effects may be achieved. Experimental investigations in this direction have provided encouraging results and some aspects of the new results are presented.
Diamond nucleation and growth by CFD were investigated to examine the possibility of engineering diamond growth shapes for practical applications. The results obtained include the following:
a) Evidence supporting certain factors influencing nucleation - useful in controlling nucleation sites and nucleation density.
b) Evidence for a double spiral growth mechanism operating on (111) faces under specific conditions - indicates the possibility of a new mechanism operating for diamond growth from the vapour phase, and the possibility of larger growth rates.
c) Evidence for the enhanced growth in <100= crystallographic direction on a cubooctahedral crystal and its control by varying the process parameters – thus showing the possibility of obtaining diamond needles and tips as engineered growth shapes, for specific applications.
A retrospective analysis of thirty patients with external laryngeal trauma was performed to assess the type and extent of injuries commonly seen as well as the outcome following treatment. Outcome was assessed both in terms of voice and airway. Major laryngeal injuries (19 cases) outnumbered minor injuries (11 cases). A good correlation exists between the symptoms of haemoptysis and stridor at presentation and severity of the injury (p = 0.002). Early surgical intervention is associated with better outcome (p = 0.01). However there is no statistically significant difference in outcome between major and minor injuries (p = 0.3) indicating that other factors are operative in determining outcome. Based on our findings a management strategy for patients with external laryngeal trauma is outlined.
A case of malignant pleomorphic adenoma of the left parotid gland which metastasized to the kidney and multiple subcutaneous sites is presented. The patient presented as an acute emergency due to spontaneous rupture of the kidney containing metastasis. All the distant metastatic lesions were confined to the right side of the body.
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