On the development of a magnetoresistive sensor for blade tip timing and blade tip clearance measurement systems.

A simultaneous blade tip timing (BTT) and blade tip clearance (BTC) measurement system enables the determination of turbomachinery blade vibrations and ensures the monitoring of the existing running gaps between the blade tip and the casing. This contactless instrumentation presents several advantages compared to the well-known telemetry system with strain gauges, at the cost of a more complex data processing procedure. The probes used can be optical, capacitive, eddy current as well as microwaves, everyone with its dedicated electronics and many existing different signal processing algorithms. Every company working in this field has developed its own processing method and sensor technology. Hence, repeating the same test with different instrumentations, the answer is often different. Moreover, rarely it is possible to achieve reliability for in-service measurements. Developments are focused on innovative instrumentations and a common standard. This paper focuses on the results achieved using a novel magnetoresistive sensor for simultaneous tip timing and tip clearance measurements. The sensor measurement principle is described. The sensitivity to gap variation is investigated. In terms of measurement of vibrations, experimental investigations were performed at the Air Force Institute of Technology (ITWL, Warsaw, Poland) in a real aeroengine and in the von Karman Institute (VKI) R2 compressor rig. The advantages and limitations of the magnetoresistive probe for turbomachinery testing are highlighted.

Lung cancer surgery in elderly patients.

AIMS AND BACKGROUND: Bronchogenic carcinoma is the major cancer-related cause of death in patients aged 70 years and over, and its incidence is rising. The aim of our study was to compare the incidence and the prognostic effect of the parameters characterizing resected patients with non-small-cell lung cancer (NSCLC) when stratified by age. Of 283 NSCLC patients candidates to a long-term follow-up program and who underwent pulmonary resection in our Unit, 34 (12%) were older than 70 years. METHODS: All patients had been preoperatively selected to exclude those with severe or multiple organ system disease and staged in accordance with the UICC classification. RESULTS: When univariate and multivariate analyses were performed within the elderly group, exclusively epidermoid carcinoma and multiple tumor nodules emerged as independent poor prognostic factors (hazard risk, 5.77 and 7.33, respectively). In comparing the older and younger groups, a higher incidence of previous primary neoplastic disease (P = 0.001), epidermoid carcinoma (P < 0.05) and multiple tumor nodules (P < 0.001) was observed in the elderly. Postoperative death was similar (3% vs 4.8%) in the two age groups, as was survival expectancy when stratified by stage. However, univariate analysis showed that epidermoid carcinoma (P = 0.001) and pneumonectomy (P = 0.00001) had a worse outcome in the older early stage subset than in the younger group. When multivariate analysis was performed in all early stage patients, only lymph node involvement and multiple tumor nodules were independently related to survival (hazard risk, 1.82 and 3.76, respectively) and had a poor prognosis. In more advanced disease, elderly and younger patients had a similar outcome. CONCLUSIONS: Our results confirm that a patient's advanced age is not a risk factor in deciding on pulmonary resection, at least for stage I and II NSCLC, and suggest that in all patients, irrespective of age, stage and histologic cell type, the presence of multiple tumor nodules is the only true prognostic factor with a very low survival rate.

Results of surgical treatment of stage IIIA non-small cell lung cancer.

From 1975 to 1993, 665 patients with non-small cell lung carcinoma (NSCLC) were studied in our Unit. Of the 55 stage IIIA patients submitted to resection, 50 were followed-up in order to evaluate the effectiveness of surgery and to identify which variables had a prognostic impact on survival. The expectancy of survival at 3,5 and 10 years was 31.7, 19.5 and 13.7%, respectively. When the analysis was limited to N2 patients, 3,5- and 10-year survival rates were 20.9, 14 and 7%, respectively. Regarding the "TN" factor, the T3N0 subset presented the highest expected survival (24.8 and 18.6% at 5 and 10 years). With regard to the "T3" factor and type of surgery, peripheral tumors submitted to en bloc resection of the chest wall showed the best 5-year survival rate (42.9%), whereas extrapleural resections--even for tumors confined to the parietal pleura--showed a 5-year survival rate of 14.3%. A slightly higher risk of death was observed in tumors originating in the superior sulcus (SST). No patients with mediastinal pleura and pericardium involvement survived more than 34 months. With univariate analysis, "N2" was the variable most significantly associated with a negative prognosis when related to T3 (T3N2 vs T3N0 0.025 < P < 0.05) or non-epidermoid tumor (no survivors at 3 years; N2 epidermoid vs N2 non-epidermoid tumor P < 0.05). Applying multivariate analysis, epidermoid cell type, even if exclusively for N2 tumors, was an independent prognostic factor, showing a favorable impact on survival expectancy (27.8% at 90 months).

The role of surgery in stage IIIa non-small cell lung cancer. Surgery in IIIa NSCLC.

The authors have reviewed the records of 50 consecutive patients resected for stage IIIa non-small cell lung cancer and included in a long-term follow-up study at the 1st Department of Surgery, University of Rome "La Sapienza". Overall survival was 60-20-16.6-16.6% at 1-5-7-10 years with an incidence of recurrence and/or metastasis respectively of 56-80-85.6-85.6%. These percentages were not influenced by the histological type. Tumours with the best prognosis were those classified as T1N2 and T3N0 (7-year survival rate: 33.3 and 29.4% respectively). Tumours with the worst prognosis were those classified as T3N2 with the highest incidence of relapse after 6 months (T3N0 vs T3N2 0.01 < p < 0.025) and no survival after 3 years (T3N0 vs T3N2 0.005 < p < 0.01). Regarding T3 tumours, infiltration of mediastinal pleura or pericardium was a negative prognostic factor implying no survival at 30 months. Involvement of chest wall or parietal pleura showed better survival overall although not statistically significant (10-year survival rate: 37.4 vs 24% respectively).

Temporal correlation of some endocrine circadian rhythms in elderly subjects.

The aim of this chronobiological study was to investigate temporal correlations in the circadian patterns of 6 hormones, namely somatotrophic hormone (STH), prolactin (PRL), cortisol (F), aldosterone (ALD), insulin (IRI) and C-peptide (CP), assayed in systemic blood serum drawn at 07:00, 10:00, 13:00, 16:00, 19:00 and 22:00 h from an antecubital vein in 19 young subjects (aged 20-29 yr, comprising 10 males and 9 females; and 20 elderly subjects (aged 70-81 yr, comprising 10 males and 10 females). All subjects were sampled on a normal dietary sodium intake (120-140 mEq/24h) while following a social routine of diurnal activity (07:00-23:00) and nocturnal rest (23:00-07:00). Time-qualified data were analyzed by lead-lag correlation and by cosinor analysis. According to the lead-lag correlation findings, it would appear that the correlation which exists between several time-qualified series in young subjects is no longer present in elderly subjects. The circadian rhythms which were found to have lost their temporal correlations with advancing age were those between STH and IRI, STH and ALD, PRL and IRI, PRL and CP, and ALD and CP. It should be noted that the correlation between hormonal rhythms breaks down mainly on account of a peculiar age-related change in the magnitude of the circadian fluctuation. This chronological decline in amplitude led to the conclusion that the senescence of endocrine rhythmic functions is a biological phenomenon characterized by altered circadian variability.