The paper reports on measurements in the flow generated by a jet issuing from a circular outlet in a wall into a cross-stream along this wall. For the jet-to-crossflow velocity ratios R of 0.5, 1 and 2, the mean and fluctuating velocity components were measured with a three-sensor hot-wire probe. The hot-wire signals were evaluated to yield the three mean-velocity components, the turbulent kinetic energy, the three turbulent shear stresses and, in the case of R = 0.5, the terms in the turbulentkinetic-energy equation. The results give a quantitative picture of the complex three-dimensional mean flow and turbulence field, and the various phenomena as well as their dependence on the velocity ratio R are discussed in detail.

Spectral analysis and flow visualization are presented for various velocity ratios and Reynolds numbers of a jet issuing perpendicularly from a developing pipe flow into a crossflow. The results are complete with conditional averages of various turbulent quantities for one jet-to-cross-flow velocity ratio R of 0.5. A unique conditional-sampling technique separated the contributions from the turbulent jet flow, the irrotational jet flow, the turbulent crossflow and the irrotational crossflow by using two conditioning functions simultaneously. The intermittency factor profiles indicate that irrotational cross-flow intrudes into the pipe but does not contribute to the average turbulent quantities, while the jet-pipe irrotational flow contributes significantly to them in the region above the exit where the interaction between the boundary-layer eddies and those of the pipe starts to take place. Further downstream, the contributions of the oncoming boundary-layer eddies to the statistical averages reduce significantly. The downstream development depends mainly on the average relative eddy sizes of the interacting turbulent fields.

BackgroundThe main purpose of the study was to quantify the direct costs of oral cancer treatment to the healthcare system of Greece. Another aim was to identify factors that affect costs and potential cost reduction items. More specifically, we examined the relationship between stage of disease, modality of treatment and total direct costs.MethodsThe medical records and clinic files of the Oral and Maxillofacial Clinic of the Athens General Hospital "Genimatas" were abstracted to investigate clinical treatment characteristics, including length of hospitalization, modes of treatment, stage of disease etc. Records of 95 patients with oral squamous cell carcinoma (OSSC), with at least six months of follow-up, were examined. The clinical data was then used to calculate actual direct costs, based on 2001 market values.ResultsThe mean total direct costs for OSSC treatment estimated at euro 8,450 or approximately US$ 7,450. Costs depended on the stage of the disease, with significant increases in stages III and IV, as compared with stages I and II (p < 0.05). Multi-modality treatment applied mainly to patients in stages III and IV was the factor that affected the cost. Disease stage was also associated with the total duration of hospitalization (p < 0.05).ConclusionsThe clinical management of advanced oral cancer is strongly associated with higher costs. Although the ideal would be to prevent cancer, the combination of high-risk screening, early diagnosis and early treatment seems the most efficient way to reduce costs, and most importantly, prolong life.

Four high-frequency-response pressure transducers with 10 viscous units resolution each have been used to obtain simultaneously the fluctuating pressure gradients at the wall of a zero-pressure-gradient boundary layer and then to compute the vorticity flux away from the wall. Since the viscous force on an element of incompressible fluid is determined by the local vorticity gradients, understanding of their dynamical characteristics is essential in identifying the turbulent structure. Extremely high and low amplitudes of both vorticity gradients have been observed which contribute significantly to their statistics although they have low probability of appearance. The r.m.s. of the vorticity flux when scaled with inner wall variables depends very strongly on the Reynolds number, indicating a breakdown of this type of scaling. The application of a small threshold to the data indicated two preferential directions of the vorticity flux vector. An attempt has been made to identify these high- and low-amplitude signals with physical phenomena associated with bursting-sweep processes. Vortical structures carrying bipolar vorticity are the dominant wall structures which are associated with the violent events characterized by large fluctuations of vorticity flux.

The present study of the pressure fluctuations in the interaction region oif a two-dimensionals compression flow established that the frequency of the shock-wave unsteadiness is of the same order as the bursting frequency of the upstream boundary layer and that this frequency is independent of the downstream separated flow. The conditional-sampling technique developed herein is capable of separating phenomena due to shock-wave oscillations from those due to transport phenomena of turbulence. The results show that turbulence as inferred from wall-pressure fluctuations may be significantly amplified approaching the shock.