Guided waves-based damage identification in plates through an inverse Bayesian process.

The use of guided waves to identify damage has become a popular method due to its robustness and fast execution, as well as the advantage of being able to inspect large areas and detect minor structural defects. When a travelling wave on a plate interacts with a defect, it generates a scattered field that will depend on the defects geometry. By analysing the scattered field, one can thus characterize the type and size of the plate damage. A Bayesian framework based on a guided waves interaction model for damage identification of infinite plate for the first time is presented here. A semi-analytical approach based on the lowest order plate theories is adopted to obtain the scattering features for damage geometries with circular symmetry, resulting in an efficient inversion procedure. Subsequently, ultrasound experiments are performed on a large aluminium plate with a circular indentation to generate wave reflection and transmission coefficients. With the aid of signal processing techniques, the effectiveness and efficiency of the proposed approach are verified. A full finite element model is used to test the damage identification scheme. Finally, the scattering coefficients are reconstructed, reliably matching the experimental results. The framework supports digital twin technology of structural health monitoring.

Fracture of tracheostomy tubes--report of 3 cases.

Fracture of the tubes appears to be caused by their prolonged use and defective fusion at the junction of cannula and phalange. We report here three cases of fractured polyvinyl chloride tracheostomy tube, an unusual complication of tracheostomy, presenting as foreign body in the trachea.

Juvenile nasopharyngeal angiofibroma.

A total of 27 cases of nasopharyngeal angiofibroma were treated in this series. All were males and age ranged between 9 and 24 years. Predominant symptoms were epistaxis and nasal obstruction. Nasopharyngeal mass was present in all cases. Cheek extensions were observed in 6. Surgery was done in 25 cases. Transpalatal excision was done in all cases. Cheek extensions were removed through separate sublabial incisions. Additional lateral rhinotomy was required in one case. Death occurred in one case during surgery due to excessive haemorrhage. Out of 25 cases, 21 were followed up for periods ranging from 2-5 years. Complete cure was observed in 16 cases. Recurrence occurred in 5 cases, who were operated upon again. Out of 5 recurrence operated cases, 2 cases showed a second recurrence.

In vitro and in vivo evaluation of change of local pH on bacteria in C.S.O.M.

An in vitro study has shown a high bactericidal activity of 2 per cent acetic acid. An in vitro study in 400 cases of C.S.O.M. has shown that conservative treatment of C.S.O.M. by pH change with 2 per cent acetic acid is better than antibiotic ear drops alone. However, combined therapy (pH change plus antibiotic ear drops) is definitely superior to single treatment by either of the two methods. Two per cent acetic acid is well tolerated by the middle ear mucosa except in 1 per cent cases, where its use had to be discontinued because of irritation. The use of 2 per cent acetic acid is highly recommended, particularly for poor nations, because of its negligible cost as compared to antibiotic ear drops.

Propranolol in the control of schizophrenic symptoms.

All schizophrenic symptoms remitted completely in six out of 14 adults who had not responded to phenothiazine drugs and who were then given propranolol. Another patient improved markedly and four improved moderately. Two had minimal or transient improvement, and one left hospital unchanged after a short, severe, toxic reaction. The six with complete remissions all began to improve within a few days of starting propranolol and the florid symptoms remitted completely after three to 26 days. They were stabilized on a daily dose of 500-3,500 mg of propranolol and at the time of writing had remained well for up to six months. Two patients who stopped propranolol after their symptoms remitted relapsed severely within a few days. Toxic effects (ataxia, visual hallucinations, and confusional states) were related to the rate of increase rather than to the absolute dose of propranolol. After the procedure was modified unwanted effects were usually mild or absent.