Optimizing dual energy cone beam CT protocols for preclinical imaging and radiation research

Objective: The aim of this work was to investigate whether quantitative dual-energy CT (DECT) imaging is feasible for small animal irradiators with an integrated cone-beam CT (CBCT) system. Methods: The optimal imaging protocols were determined by analyzing different energy combinations and dose levels. The influence of beam hardening effects and the performance of a beam hardening correction (BHC) were investigated. In addition, two systems from different manufacturers were compared in terms of errors in the extracted effective atomic numbers (Z(eff)) and relative electron densities (rho(e)) for phantom inserts with known elemental compositions and relative electron densities. Results: The optimal energy combination was determined to be 50 and 90kVp. For this combination, Z(eff) and r rho(e) can be extracted with a mean error of 0.11 and 0.010, respectively, at a dose level of 60cGy. Conclusion: Quantitative DECT imaging is feasible for small animal irradiators with an integrated CBCT system. To obtain the best results, optimizing the imaging protocols is required. Well-separated X-ray spectra and a sufficient dose level should be used to minimize the error and noise for Z(eff) and rho(e). When no BHC is applied in the image reconstruction, the size of the calibration phantom should match the size of the imaged object to limit the influence of beam hardening effects. No significant differences in Z(eff) and rho(e) errors are observed between the two systems from different manufacturers. Advances in knowledge: This is the first study that investigates quantitative DECT imaging for small animal irradiators with an integrated CBCT system

Testing advanced driver assistance systems for fault management with the VEHIL test facility

This paper presents a methodological approach for validation of advanced driver assistance systems (ADASs), especially concerning fault management. Tools in this methodology are the unique VEhicle-Hardware-In-the-Loop (VEHIL) test facility and the associated simulation tool PRESCAN. With VEHIL the development process and more specifically the validation phase of intelligent vehicles can be carried out safer, cheaper, more manageable, and more reliable. In VEHIL a complete vehicle is tested in the simulation loop, such that the safety and reliability of an ADAS can be tested to great accuracy and reliability

VEHIL: a test facility for validation of fault management systems for advanced driver assistance systems

We present a methodological approach for the validation of fault management systems for Advanced Driver Assistance Systems (ADAS). For the validation process the unique VEHIL facility, developed by TNO Automotive and currently situated in Helmond, The Netherlands, is applied. The VEHIL facility provides the opportunity to make the entire development process of intelligent vehicles safer, cheaper, and more manageable, and to make simulation more reliable. The main feature of VEHIL is that a complete intelligent vehicle, including its sensors and actuators, can be tested in a Hardware-In-the-Loop simulation environment. In this way VEHIL can be applied in the design phase for fast and easy optimization of the sensor configuration. Moreover, due to its ability for providing very accurately controllable testing conditions, VEHIL can also be used for the validation of the performance of intelligent vehicle control and fault management systems. In this paper, we particularly focus on the use of VEHIL for the validation of fault management systems for Advanced Driver Assistance Systems

VEHIL : test facility for fault management testing of advanced driver assistance systems

This paper presents the latest developments of the VEHIL facility, which aims to make the development process of intelligent vehicles safer, cheaper and more manageable. The main feature of VEHIL is that a complete intelligent vehicle can be tested in a hardware-in-the-loop simulation environment. The use of VEHIL will be illustrated by preliminary test results of a Pre-Crash System. Furthermore, a methodological approach will be presented for the validation of fault management systems for Advanced Driver Assistance Systems by fault injection in VEHIL

Inhibition of Trophoblast-Induced Spiral Artery Remodeling Reduces Placental Perfusion in Rat Pregnancy.

Rats harboring the human angiotensinogen and human renin genes develop preeclamptic features in pregnancy. The preeclamptic rats exhibit a deeper trophoblast invasion associated with a reduced resistance index by uterine Doppler. Doxycycline inhibits matrix metalloproteinase activity. We tested the hypothesis that matrix metalloproteinase inhibition reduces trophoblast invasion with subsequent changes in placental perfusion. Preeclamptic and pregnant control Sprague-Dawley rats were treated with doxycycline (30 mg/kg of body weight orally) from gestational day 12 until day 18. Placental perfusion was assessed using a micromarker contrast agent. The animals were euthanized on day 18 of pregnancy; biometric data were acquired, and trophoblast invasion was analyzed. Doxycycline resulted in intrauterine growth retardation and lighter placentas in both groups. Maternal body weight was not affected. As shown earlier, preeclamptic rats exhibited a deeper endovascular trophoblast invasion. However, doxycycline treatment reduced trophoblast invasion in the preeclamptic rats. The physiological spiral artery remodeling, as assessed by the deposition of fibrinoid and α-actin in the spiral artery contour, was significantly reduced by doxycycline. The vascularity index, as assessed by perfusion measurement of the placenta, was reduced after doxycycline treatment in preeclamptic rats. Thus, matrix metalloproteinase inhibition with doxycycline leads to reduced trophoblast invasion and associated reduced placental perfusion. These studies are the first to show that reducing trophoblast-induced vascular remodeling decreases subsequent placental perfusion. Our model allows the study of dysregulated trophoblast invasion and vascular remodeling in vivo to gain important insights into preeclampsia-related mechanisms

Structure of the specific combining ability between two species of Eucalyptus. II. A clustering approach and a multiplicative model

International audienceThe Eucalyptus breeding program of URPPI (a partnership between CIRAD-Fore t, Centre National de la Recherche Forestie re du Congo, and Unite dÕAforestation Industrielle du Congo) consists of a re- ciprocal recurrent selection scheme developed in the Congo between the two species Eucalyptus urophylla and Eucalyptus grandis. Two approaches are proposed in order to model and predict the speciÞc combining ability (SCA) between these species. The clustering ap- proach uses a simultaneous clustering procedure of the two species based on SCA and reveals heterotic groups coherent with the geographical origins of E. urophylla genotypes. The second approach uses a multiplicative model to partition the SCA into three multiplicative terms explaining 95% of the interactio

Structure of the specific combining ability between two species of Eucalyptus. I. RAPD data

International audienceWithin the context of the reciprocal recurrent selection scheme developed in 1989 by CIRAD-Fore t on Eucalyptus, RAPD essays were performed to assess the genetic diversity in the two species E. urophylla and E. grandis. The molecular markers were split into two parts: the speciÞc markers (present with di¤erent fre- quencies in the two species) and the common markers (present with similar frequencies in the two species). The study analyses the structure of genetic diversity within and between the two species of Eucalyptus. Dif- ferent genetic distances are worked out for use in pre- diction equations of the individual tree trunk volume of hybrids at 38 months. Each distance is expressed as the sum of the general genetic distance and the speciÞc genetic distance. The general genetic distance based on the double presence plus the double absence of bands seems to be an interesting co-variate to use in a factor regression model. Through this model the distance calculated between species explains the general com- bining ability (GCA) and the speciÞc combining ability (SCA) of the phenotypic character with a global coe¦c- ient of determination of 81.6