Calibration of GRACE Accelerometers Using Two Types of Reference Accelerations

Two approaches for the calibration of GRACE (Gravity Recovery And Climate Experiment) accelerometers are revisited. In the first approach, surface forces acting on the satellite are considered to derive the reference acceleration. In the second approach, the total acceleration consisting of a gravitational and a non-gravitational contribution is first determined from the reduced-dynamic orbits. The approximation of discrete satellite positions by a polynomial function allows the total acceleration to be obtained by a twofold derivative w.r.t. time. Calibration parameters (scale factor and bias) and statistical values are estimated for periods with a low and high solar activity. The quality of these two approaches shows dependencies on solar activity and consequent variations in the magnitude of the non-gravitational reference acceleration. Besides, the quality of the presented results is affected by the orientation of the orbital plane w.r.t. the Sun. The second approach is vitiated by a periodic disturbing signal on cross-track axis. This signal has been pointed out in earlier studies (Calabia et al., Aerosp Sci Technol 45, 2015; Calabia and Jin, Aerosp Sci Technol 49, 2016). We apply a moving window median filter to recover the underlying non-gravitational signal for accelerometer calibration. The calibration is accomplished by a direct comparison of reference accelerations and observed accelerometer measurements without introducing any a priori values or constraints. The focus of this work is more sensor oriented than gravity field recovery (GFR) related. Nevertheless, the results can be used as initial values for precise orbit determination (POD) or for pre-processing of accelerometer measurements in a multi step gravity field recovery approach (Klinger and Mayer-Gürr, Adv Space Res 58(9), 2016). The final paper is available at https://doi.org/10.1007/1345_2018_46

IP Models to orchestrate innovation ecosystems: IMEC, a public research institute in nano-electronics

Companies increasingly organize innovation activities within innovation ecosystems. This study illustrates the central role of the IP-model that an orchestrator develops for the innovation ecosystem partners. The governance of IP is instrumental for the success of innovation ecosystems as it determines the value appropriation potential for the ecosystem partners and positively influences the success of innovation ecosystems. The insights are based on a case study of IMEC, a public research institute in nano-electronics. IMEC has an IP-based orchestration model for innovation ecosystems through multi-party research collaborations between public and private firms. (Keywords: Innovation Management, Intellectual Property, Innovation Networks, Innovation Ecosystems, Open Innovation

Intestinal transplantation: from the laboratory to the clinics

Intestinal transplantation (ITx) is a valuable treatment for patients suffering from irreversible short bowel syndrome and debilitating complications of total parenteral nutrition. However, the results of ITx remain inferior to other solid organ transplants due to the profound immunogenicity of the organ and the subsequent demand for high levels of immunosuppression with its associated side effects. Since 2000, 10 consecutive cadaveric intestinal transplantations have been performed in our center. All were treated with the same Leuven Tolerogenic Protocol - an experimentally proven, multifactorial immunomodulatory regimen - which includes the administration of donor specific whole blood, low-dose steroids, low-dose tacrolimus, and limitation of peritransplant intestinal ischemia reperfusion injury. The first patient transplanted in this series was the first successful ITx performed in the Benelux. The 5-year patient and graft survival rate is 90% (follow-up: 11 months – 11 years and 10 months), which compares favorably with the average 50% patient survival rate reported by the Intestinal Transplant Registry. Only one patient (10%) developed an early acute rejection, reversible with immediate steroid treatment. Three patients (30%) faced a later episode of acute rejection (at 4 months, 18 months and 46 months). Wider application of ITx depends upon the development of these immunosuppressive protocols which prohibit intestinal rejection while reducing the need for immunosuppression.status: publishe