Measurement of digital particle image velocimetry precision using electro-optically created particle-image displacements

The displacement (velocity) precision achieved with digital particle image velocimetry (PIV) was measured. The purpose of this work was to determine the precision and sensitivity of digital PIV using real rather than theoretical images at 1 and 2 mm spatial resolution. The displacement measurement precision was determined by measuring the RMS noise from 60 identical displacement distributions. This work is unique in that it uses electro-optical image shifting to create a repeatable image displacement distribution of random particle fields. The displacement variance between images is caused by the shot-to-shot variation in: (1) the particle-image fields, (2) the camera noise and (3) the variance in the correlation peak detection. In addition to magnification variations, the particle-number density, imaging-lens f-stop and image-plane position errors were varied to determine the best configuration. The results indicate that both the ensemble-mean and the RMS fluctuations of the image displacements are affected by these parameters and comparisons with results found in the literature are presented. The extents of these variations are quantified. This variance does not, of course, include errors due to random gradients and out-of-plane pairing losses, which exist in real turbulent flows.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49061/2/e20705.pd

Particle-image velocimetry measurement errors when imaging through a transparent engine cylinder

When making particle-image velocimetry measurements through the quartz cylinder of a reciprocating engine, the particle images are aberrated. This work quantifies the practical field-of-view and the errors in the velocity measurements caused by those aberrations. Electro-optical image shifting was used to create a repeatable particle-image displacement distribution for 60 images. Ensemble averaging of these images is used to quantify the rms errors due to the shot-to-shot variation in (1) the particle-image fields, (2) the camera noise, (3) the variance in the correlation-peak detection and (4) the particle-image aberrations. These results demonstrate that the field-of-view is restricted to the centre 66 mm of the 86 mm inside-diameter cylinder due to decreased accuracy, decreased image-to-image precision and decreased displacement-peak detectability of the image-displacement correlation. The correlation-peak detectability was degraded by both particle-image aberrations and decreased transmission of the scattered light.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49062/2/e20709.pd

Outcome after resection of Adrenocortical Carcinoma liver metastases: a retrospective study

Background: Metastatic Adrenocortical Carcinoma (ACC) is a rare malignancy with a poor 5-year-survival rate (<15%). A surgical approach is recommended in selected patients if complete resection of distant metastasis can be achieved. To date there are only limited data on the outcome after surgical resection of hepatic metastases of ACC. Methods: A retrospective analysis of the German Adrenocortical Carcinoma Registry was conducted. Patients with liver metastases of ACC but without extrahepatic metastases or incomplete tumour resection were included. Results: Seventy-seven patients fulfilled these criteria. Forty-three patients underwent resection of liver metastases of ACC. Complete tumour resection (R0) could be achieved in 30 (69.8%). Median overall survival after liver resection was 76.1 months in comparison to 10.1 months in the 34 remaining patients with unresected liver metastases (p < 0.001). However, disease free survival after liver resection was only 9.1 months. Neither resection status (R0/R1) nor extent of liver resection were significant predictive factors for overall survival. Patients with a time interval to the first metastasis/recurrence (TTFR) of greater than 12 months or solitary liver metastases showed significantly prolonged survival. Conclusions: Liver resection in the case of ACC liver metastases can achieve long term survival with a median overall survival of more than 5 years, but disease free survival is short despite metastasectomy. Time to recurrence and single versus multiple metastases are predictive factors for the outcome

What Is the Optimal Duration of Adjuvant Mitotane Therapy in Adrenocortical Carcinoma? An Unanswered Question

A relevant issue on the treatment of adrenocortical carcinoma (ACC) concerns the optimal duration of adjuvant mitotane treatment. We tried to address this question, assessing whether a correlation exists between the duration of adjuvant mitotane treatment and recurrence-free survival (RFS) of patients with ACC. We conducted a multicenter retrospective analysis on 154 ACC patients treated for ≥12 months with adjuvant mitotane after radical surgery and who were free of disease at the mitotane stop. During a median follow-up of 38 months, 19 patients (12.3%) experienced recurrence. We calculated the RFS after mitotane (RFSAM), from the landmark time-point of mitotane discontinuation, to overcome immortal time bias. We found a wide variability in the duration of adjuvant mitotane treatment among different centers and also among patients cared for at the same center, reflecting heterogeneous practice. We did not find any survival advantage in patients treated for longer than 24 months. Moreover, the relationship between treatment duration and the frequency of ACC recurrence was not linear after stratifying our patients in tertiles of length of adjuvant treatment. In conclusion, the present findings do not support the concept that extending adjuvant mitotane treatment over two years is beneficial for ACC patients with low to moderate risk of recurrence

Measurements and Modeling of Reynolds Stress and Turbulence Production in a Swirl-Supported, Direct-Injection Diesel Engine

Measured and numerically predicted components of the mean rate-of-strain tensor _Sij_ and the Reynolds stress _u_ru___ are examined and compared to elucidate the source and scrutinize the modeling of late-cycle turbulence production in swirl-supported, direct-injection diesel engines. The experiments are performed with combustion in the engine inhibited, to eliminate the complicating influence of heat release on turbulence generation and to reduce the problem to one more closely approximating constant-density turbulence. Both the measurements and the calculations indicate that the primary influence of the mean flow swirl on turbulence production is confined to two separate periods: (1) shortly after the end of injection and (2) in the late-cycle period, when large positive levels of _u_r,u___ are observed. Formation of the positive Reynolds stress coincides with the development of a negative radial gradient in mean angular momentum, indicating an unstable mean flow field. At this time, the measured velocity fluctuations show a large increase, approximately doubling in magnitude compared to fluctuations measured without fuel injection. Predicted velocity fluctuations, obtained via k-_ turbulence modeling, show a similar late-cycle increase, although the magnitude of the increase is not quantitatively captured. To evaluate its applicability during the period in which the unstable, negative radial gradient in angular momentum is present, the isotropic eddy viscosity hypothesis is examined. The Reynolds stress estimated from the measured _Sr__ using the eddy viscosity hypothesis is found to mimic the measured stress with reasonable accuracy, and the measured and calculated r-_ plane turbulence production terms are shown to have excellent qualitative and quantitative agreement. The quantitative agreement, however, appears largely providential, as the measured and predicted values of _Sr__ differ by a factor of 2. This discrepancy is compensated for by the underpredicted turbulent kinetic energy and seemingly high values of the dissipation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86744/1/Sick29.pd

Mitotane Monotherapy in Patients With Advanced Adrenocortical Carcinoma

Context Although mitotane is the only approved drug for the treatment of adrenocortical carcinoma (ACC), data on monotherapy in advanced disease are still scarce. Objective To assess the efficacy of mitotane in advanced ACC in a contemporary setting and to identify predictive factors. Design and Setting Multicenter cohort study of three German referral centers. Patients One hundred twenty-seven patients with advanced ACC treated with mitotane monotherapy. Outcome Measures Response Evaluation Criteria in Solid Tumors evaluation, progression-free survival (PFS) and overall survival (OS) by Kaplan-Meier method, and predictive factors by Cox regression. Results Twenty-six patients (20.5%) experienced objective response, including three with complete remission. Overall, median PFS was 4.1 months (range 1.0 to 73) and median OS 18.5 months (range 1.3 to 220). Multivariate analysis indicated two main predictive factors: low tumor burden (180 days). Patients who achieved mitotane levels >14 mg/L had significantly longer OS (HR 0.42; P = 0.003). Conclusions At 20.5% the objective response rate was slightly lower than previously reported. However, >20% of patients experienced long-term disease control at >1 year. In general, patients with late diagnosis of advanced disease and low tumor burden might especially benefit from mitotane monotherapy, whereas patients with early advanced disease and high tumor burden are probably better candidates for combined therapy of mitotane and cytotoxic drugs

Efficacy and safety of radiation therapy in advanced adrenocortical carcinoma

BACKGROUND: International guidelines emphasise the role of radiotherapy (RT) for the management of advanced adrenocortical carcinoma (ACC). However, the evidence for this recommendation is very low. METHODS: We retrospectively analysed all patients who received RT for advanced ACC in five European centres since 2000. PRIMARY ENDPOINT: time to progression of the treated lesion (tTTP). Secondary endpoints: best objective response, progression-free survival (PFS), overall survival (OS), adverse events, and the establishment of predictive factors by Cox analyses. RESULTS: In total, 132 tumoural lesions of 80 patients were treated with conventional RT (cRT) of 50-60 Gy (n = 20) or 20-49 Gy (n = 69), stereotactic body RT of 35-50 Gy (SBRT) (n = 36), or brachytherapy of 12-25 Gy (BT) (n = 7). Best objective lesional response was complete (n = 6), partial (n = 52), stable disease (n = 60), progressive disease (n = 14). Median tTTP was 7.6 months (1.0-148.6). In comparison to cRT20-49Gy, tTTP was significantly longer for cRT50-60Gy (multivariate adjusted HR 0.10; 95% CI 0.03-0.33; p < 0.001) and SBRT (HR 0.31; 95% CI 0.12-0.80; p = 0.016), but not for BT (HR 0.66; 95% CI 0.22-1.99; p = 0.46). Toxicity was generally mild and moderate with three grade 3 events. No convincing predictive factors could be established. CONCLUSIONS: This largest published study on RT in advanced ACC provides clear evidence that RT is effective in ACC

Treatment of Refractory Adrenocortical Carcinoma with Thalidomide: Analysis of 27 Patients from the European Network for the Study of Adrenal Tumours Registry

OBJECTIVE Adrenocortical carcinoma (ACC) is a rare malignancy with a dismal prognosis. In advanced stages, tumour control by mitotane and cytotoxic chemotherapy is often temporary and salvage treatments are warranted. METHODS Retrospective cohort study of participants in the prospective European Networks for the Study of Adrenal Tumours (ENSAT) registry. Main outcome measures were best response during treatment, progression-free survival (PFS), both measured according to RECIST 1.1 by two blinded radiologists, and overall survival (OS). RESULTS Twenty-seven patients (13 males; median age 44.1 years) progressing after mitotane and a median of 4 further systemic treatments were included. Thalidomide was administered as tolerated with a starting dose of 50 mg and target dose of 200 mg /d. The median interval between treatment initiation and first imaging was 10.5 (4.4-17.5) weeks. The best response to treatment was stable disease (SD, n=2) and progressive disease (n=25), with a median PFS of 11.2 weeks and a median OS of 36.4 weeks. The first patient with SD discontinued treatment due to mild epistaxis and diarrhea after 22.3 weeks. The second patient had SD at the second treatment evaluation after 25.2 weeks and continued thalidomide but then had clinical progression and deceased after 54.3 weeks. In general, thalidomide induced only mild or moderate adverse effects (mainly fatigue and gastrointestinal complaints). CONCLUSION Thalidomide was overall well tolerated but resulted in disease control in only 2/27 (7.4%) patients. In the absence of predictive response markers, thalidomide should only be considered in exceptional cases as a salvage therapy in ACC