MICROSCOPE Mission: Final Results of the Test of the Equivalence Principle.

The MICROSCOPE mission was designed to test the weak equivalence principle (WEP), stating the equality between the inertial and the gravitational masses, with a precision of 10^{-15} in terms of the Eötvös ratio η. Its experimental test consisted of comparing the accelerations undergone by two collocated test masses of different compositions as they orbited the Earth, by measuring the electrostatic forces required to keep them in equilibrium. This was done with ultrasensitive differential electrostatic accelerometers onboard a drag-free satellite. The mission lasted two and a half years, cumulating five months worth of science free-fall data, two-thirds with a pair of test masses of different compositions-titanium and platinum alloys-and the last third with a reference pair of test masses of the same composition-platinum. We summarize the data analysis, with an emphasis on the characterization of the systematic uncertainties due to thermal instabilities and on the correction of short-lived events which could mimic a WEP violation signal. We found no violation of the WEP, with the Eötvös parameter of the titanium and platinum pair constrained to η(Ti,Pt)=[-1.5±2.3(stat)±1.5(syst)]×10^{-15} at 1σ in statistical errors.

MICROSCOPE Mission: First Results of a Space Test of the Equivalence Principle.

According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10^{-15} precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives δ(Ti,Pt)=[-1±9(stat)±9(syst)]×10^{-15} (1σ statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations.

Intravenous Tranexamic Acid Decreases Blood Transfusions and Blood Loss for Patients with Surgically Treated Hip Fractures.

INTRODUCTION: Tranexamic acid can decrease blood loss related to surgery and trauma. The primary objective of this study is to examine if the use of a single dose of peri-operative TXA significantly decreases the rate of allogenic blood transfusions in the setting of operative care of hip fractures. Secondary objectives included examining if total blood loss was decreased by TXA in operative hip fractures as well as examining the safety of TXA by measuring the rates venous thromboembolism (VTE). METHODS: Retrospective chart review of 505 patients who were operatively treated for hip fractures at a single facility was performed. In a non-randomized fashion, 307 patients received TXA and 198 patients did not. Patients received 1 gram of TXA prior to incision. Blood transfusion was the primary end point. Blood loss was calculated using the hemoglobin balance method. Chart was reviewed for VTE events during hospitalization. RESULTS: 505 patients were analyzed. The use of single perioperative dose of TXA in the surgical management of hip fracture resulted in absolute risk reduction of transfusion of 7.7% and relative risk reduction of transfusion by 29%. This was statistically significant with P =.04. Patients who received TXA on average lost 235 ml less blood compared to those who did not receive TXA (P <.0001). No increase in VTE events were found in either group during hospitalization. CONCLUSION: This study supports the use of TXA is decrease blood loss and transfusion rates in patients with hip fractures. TXA can be used routinely to decrease complications in this usually fragile population.