OreSat: A Student Team-Based Approach to an Inexpensive, Open, and Modular (1-3U) CubeSat Bus

Most educational CubeSat projects have the same dilemma: not enough money to buy capable COTS hardware, and not enough internal experience (even with teams of students) to build reliable, and inexpensive systems in-house. We present a middle road to the “COTS vs DIY” conundrum: the OreSat bus. OreSat is a fully open source 1U – 3U CubeSat system meant to be built, modified, and flown by student teams. It’s specifically designed to be put together by resource-constrained student teams with “gaps” in their interdisciplinary breadth, as most teams have. OreSat has everything you would expect from a CubeSat system: a 1 – 3U structure, multi-band deployable antenna, solar array, battery pack, on-board computer, radio system, star tracker, reaction wheels, magnetorquers, and SDR GPS receiver. OreSat is built around a high density card-cage system with roughly a 40% higher packing density than the commonly used PC/104-plus stack. Each system is a “card” based on inexpensive 2 and 4 layer PCBs that interface to a common backplane that is capable of carrying CAN, Ethernet, RF, and power. As each CubeSat is unique, the backplane is made bespoke for each mission with 30% of backplane connections available for customization. Student teams can take the existing OreSat systems and build them as is, or modify them for their missions. The OreSat bus is scheduled for first flight in late 2021 (OreSat0, a 1U technology demonstrator), and will be fully deployed in late 2022 as the 2U “OreSat” mission, accepted into the 2017 NASA CubeSat Launch Initiative (CSLI)

A Bayesian reanalysis of the Standard versus Accelerated Initiation of Renal-Replacement Therapy in Acute Kidney Injury (STARRT-AKI) trial

Background Timing of initiation of kidney-replacement therapy (KRT) in critically ill patients remains controversial. The Standard versus Accelerated Initiation of Renal-Replacement Therapy in Acute Kidney Injury (STARRT-AKI) trial compared two strategies of KRT initiation (accelerated versus standard) in critically ill patients with acute kidney injury and found neutral results for 90-day all-cause mortality. Probabilistic exploration of the trial endpoints may enable greater understanding of the trial findings. We aimed to perform a reanalysis using a Bayesian framework. Methods We performed a secondary analysis of all 2927 patients randomized in multi-national STARRT-AKI trial, performed at 168 centers in 15 countries. The primary endpoint, 90-day all-cause mortality, was evaluated using hierarchical Bayesian logistic regression. A spectrum of priors includes optimistic, neutral, and pessimistic priors, along with priors informed from earlier clinical trials. Secondary endpoints (KRT-free days and hospital-free days) were assessed using zero–one inflated beta regression. Results The posterior probability of benefit comparing an accelerated versus a standard KRT initiation strategy for the primary endpoint suggested no important difference, regardless of the prior used (absolute difference of 0.13% [95% credible interval [CrI] − 3.30%; 3.40%], − 0.39% [95% CrI − 3.46%; 3.00%], and 0.64% [95% CrI − 2.53%; 3.88%] for neutral, optimistic, and pessimistic priors, respectively). There was a very low probability that the effect size was equal or larger than a consensus-defined minimal clinically important difference. Patients allocated to the accelerated strategy had a lower number of KRT-free days (median absolute difference of − 3.55 days [95% CrI − 6.38; − 0.48]), with a probability that the accelerated strategy was associated with more KRT-free days of 0.008. Hospital-free days were similar between strategies, with the accelerated strategy having a median absolute difference of 0.48 more hospital-free days (95% CrI − 1.87; 2.72) compared with the standard strategy and the probability that the accelerated strategy had more hospital-free days was 0.66. Conclusions In a Bayesian reanalysis of the STARRT-AKI trial, we found very low probability that an accelerated strategy has clinically important benefits compared with the standard strategy. Patients receiving the accelerated strategy probably have fewer days alive and KRT-free. These findings do not support the adoption of an accelerated strategy of KRT initiation

Regional Practice Variation and Outcomes in the Standard Versus Accelerated Initiation of Renal Replacement Therapy in Acute Kidney Injury (STARRT-AKI) Trial: A Post Hoc Secondary Analysis.

ObjectivesAmong patients with severe acute kidney injury (AKI) admitted to the ICU in high-income countries, regional practice variations for fluid balance (FB) management, timing, and choice of renal replacement therapy (RRT) modality may be significant.DesignSecondary post hoc analysis of the STandard vs. Accelerated initiation of Renal Replacement Therapy in Acute Kidney Injury (STARRT-AKI) trial (ClinicalTrials.gov number NCT02568722).SettingOne hundred-fifty-three ICUs in 13 countries.PatientsAltogether 2693 critically ill patients with AKI, of whom 994 were North American, 1143 European, and 556 from Australia and New Zealand (ANZ).InterventionsNone.Measurements and main resultsTotal mean FB to a maximum of 14 days was +7199 mL in North America, +5641 mL in Europe, and +2211 mL in ANZ (p p p p p p p p = 0.007).ConclusionsAmong STARRT-AKI trial centers, significant regional practice variation exists regarding FB, timing of initiation of RRT, and initial use of continuous RRT. After adjustment, such practice variation was associated with lower ICU and hospital stay and 90-day mortality among ANZ patients compared with other regions