157 research outputs found

    The impact of inlet boundary layer thickness on the unsteady aerodynamics of S-duct intakes

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    The need to reduce aero-engine emissions and direct operating costsis driving the civil aerospace sectortowards considering more integrated propulsion systems. Many of the proposed novel aircraft architectures employ convoluted intakes for either the aero-engine or propulsion system. These intakes are characterized by unsteady distortion that can hinder the performance and operability of the propulsion system. This work assessesthe impact of the inlet boundary layer on the unsteady aerodynamics of an S-duct intake using time-resolved particle image velocimetry at the aerodynamic interface plane.An increase in the boundary layer thickness at the intake inlet increasesthe flow unsteadiness on the swirl angle by up to 40% relativeto the baseline case. The azimuthal orientation of the inlet boundary layer modifies the intensity and topology of the most frequent swirl distortion pattern. For a relatively thick inlet boundary layer, the reduction of the dominant frequencies associated withthe unsteady swirl angle is postulated to be beneficial for the engine stability. Overall, this works gives guidelines for the integration between the intake and the engine across the range of potential inlet operating conditions

    In vivo Raman spectroscopy for bladder cancer detection using a superficial Raman probe compared to a nonsuperficial Raman probe

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    Raman spectroscopy is promising as a noninvasive tool for cancer diagnosis. A superficial Raman probe might improve the classification of bladder cancer, because information is gained solely from the diseased tissue and irrelevant information from deeper layers is omitted. We compared Raman measurements of a superficial to a nonsuperficial probe, in bladder cancer diagnosis. Two-hundred sixteen Raman measurements and biopsies were taken in vivo from at least one suspicious and one unsuspicious bladder location in 104 patients. A Raman classification model was constructed based on histopathology, using a principal-component fed linear-discriminant-analysis and leave-one-person-out cross-validation. The diagnostic ability measured in area under the receiver operating characteristics curve was 0.95 and 0.80, the sensitivity was 90% and 85% and the specificity was 87% and 88% for the superficial and the nonsuperficial probe, respectively. We found inflammation to be a confounder and additionally we found a gradual transition from benign to low-grade to high-grade urothelial carcinoma. Raman spectroscopy provides additional information to histopathology and the diagnostic value using a superficial probe. </p

    Active surveillance in renal transplant patients with prostate cancer: a multicentre analysis

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    Introduction: Due to medical improvements leading to increased life expectancy after renal transplantation and widened eligibility criteria allowing older patients to be transplanted, incidence of (low-risk) prostate cancer (PCa) is increasing among renal transplant recipients (RTR). It remains to be established whether active surveillance (AS) for PCa represents a safe treatment option in this setting. Therefore, we aim to compare AS discontinuation and oncological outcomes of AS for PCa of RTR vs. non-transplant patients. Methods: Multicentre study including RTR diagnosed with PCa between 2008 and 2018 in whom AS was initiated. A subgroup of non-RTR from the St. Antonius hospital AS cohort was used as a control group. Comparison of RTR vs. non-RTR was performed by 2:1 propensity score matched survival analysis. Outcome measures included tumour progression-free survival, treatment-free survival, metastasis rates, biochemical recurrence rates and overall survival. Patients were matched based on age, year of diagnosis, PSA, biopsy ISUP grade group, relative number of positive biopsy cores and clinical stage. Results: A total of 628 patients under AS were evaluated, including 17 RTRs and 611 non-RTRs. A total of 13 RTR cases were matched with 24 non-RTR cases. Median overall follow-up for the RTR and non-RTR matched cases was, respectively, 5.1 (IQR 3.2–8.7) years and 5.7 (IQR 4.8–8.1) years. There were no events of metastasis and biochemical recurrence among matched cases. The matched-pair analysis results in a 1-year and 5-year survival of the RTR and non-RTR patients were, respectively, 100 vs. 92%, and 39 vs. 76% for tumour progression, 100 vs. 91% and 59 vs. 76% for treatment-free survival and, respectively, 100 vs. 100% and 88 vs. 100% for overall survival. No significant differences in tumour progression-free survival (p = 0.07) and treatment-free survival were observed (p = 0.3). However, there was a significant difference in overall survival comparing both groups (p = 0.046). Conclusions: AS may be carefully considered in RTR with low-risk PCa. In our preliminary analysis, no major differences were present in AS outcomes between RTR and non-RTR. Overall mortality was significantly higher in the RTR subgroup

    ACTH-Bestimmungen im Plasma aus dem Bulbus cranialis venae jugularis

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    Der Anstieg der Corticosteroninkretion in das Nebennierenvenenblut frisch hypophysektomierter Ratten diente zur Bestimmung von ACTH-Spiegeln in 1 ml nativen, menschlichen Plasma. Normale ACTH-Plasmaspiegel sind sowohl bei Punktion der Vena cubitalis als auch des Bulbus cranialis venae jugularis durch diese Methode nicht oder nur ungenau zu erfassen. Bei Patienten mit pathologisch erhöhten ACTH-Spiegeln in der Vena cubitalis sind die ACTH-Spiegel im Bulbus cranialis venae jugularis signifikant höher. Es ließ sich eine Beziehung zwischen ACTH-Spiegel in der Peripherie (Vena cubitalis), Differenz der ACTH-Spiegel zwischen Bulbus cranialis venae jugularis und Vena cubitalis und biologischer Halbwertszeit von endogenem ACTH aufstellen. Nach den Ergebnissen der Bestimmung von ACTH-Spiegeln bei Nebennierengesunden läßt sich folgern, daß die biologische Halbwertszeit von endogenem ACTH größer als 4 min sein muß. Bei Patienten mit erhöhten ACTH-Spiegeln ließ sich die biologische Halbwertszeit von endogenem ACTH größenordnungsmäßig mit ca. 40 min berechnen. Bei diesen Patienten betrug die mittlere tägliche ACTH-Inkretion ca. 100 E.ACTH-contents of 1 ml specimens of human plasma were assayed by measurement of increases of corticosterone output in the adrenal vein of acutely hypophysectomized rats. This procedure is not sensitive enough to measure normal ACTH-levels acurately, neither when blood was drawn from the bulbus cranialis venae jugularis, nor from the vena cubitalis. In patients having pathologically elevated ACTH-levels, the ACTH-content of plasma is significantly higher in the bulbus cranialis venae jugularis than in peripheral venous blood. An equation is presented formulating the relation of peripheral ACTH-levels, differences of ACTH-levels between bulbus cranialis venae jugularis and vena cubitalis, and of the biological halflife of endogenous ACTH. On the basis of the results of the determinations of socalled normal ACTH-levels it can be concluded, that the biological halflife of endogenous ACTH is longer than 4 min. From the data of patients with elevated ACTH-levels a halflife of approximately 40 min and a mean ACTH-secretion of approx. 100 units per day could be calculated
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