Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract: Recently, the observed equation of state for dark energy appears to favor values below $-1$. The tendency implies that the nature of dark energy may be quite different from that of the cosmological constant. In view of the adjustment on the equation of state keeps decreasing, the introduction of the phantom energy seems inevitable. By employing observational constraints from supernovae and from the acoustic scale in which the accuracy of the data has become extraordinary, we apply a phenomenological scenario to be acquainted with the evolution of our universe. The demonstration on the constrained unfolding of the phantom energy shows the model has high consistency with the current observation.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2024-05-10 Cooperative journals: 《Research in Astronomy and Astrophysics》
Abstract: For the ASO-S/HXI payload, the accuracy of the flare reconstruction is reliant on important factors such as the alignment of the dual grating and the precise measurement of observation orientation. To guarantee optimal functionality of the instrument throughout its life cycle, the Solar Aspect System (SAS) is imperative to ensure that measurements are accurate and reliable. This is achieved by capturing the target motion and utilizing a physical model-based inversion algorithm. However, the SAS optical system's inversion model is a typical ill-posed inverse problem due to its optical parameters, which results in small target sampling errors triggering unacceptable shifts in the solution. To enhance inversion accuracy and make it more robust against observation errors, we suggest dividing the inversion operation into two stages based on the SAS spot motion model. First, the as-rigid-as-possible (ARAP) transformation algorithm calculates the relative rotations and an intermediate variable between the substrates. Second, we solve an inversion linear equation for the relative translation of the substrates, the offset of the optical axes, and the observation orientation. To address the ill-posed challenge, the Tikhonov method grounded on the discrepancy criterion and the maximum a posteriori (MAP) method founded on the Bayesian framework are utilized. The simulation results exhibit that the ARAP method achieves a solution with a rotational error of roughly ±35 (1/2-quantile); both regularization techniques are successful in enhancing the stability of the solution, the variance of error in the MAP method is even smaller—it achieves a translational error of approximately ±18 μm (1/2-quantile) in comparison to the Tikhonov method's error of around ±24 μm (1/2-quantile). Furthermore, the SAS practical application data indicates the method's usability in this study. Lastly, this paper discusses the intrinsic interconnections between the regularization methods.
Subjects: Biology >> Neurobiology Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2020-03-23
Abstract: In clinical practice, a patient is declared dead after 30 minutes of unsuccessful resuscitation post-cardiac arrest, as the brain is considered irreversibly damaged within minutes after cardiac arrest. A recent report showed that cellular function of the brain can be restored hours post-mortem in pigs. However, whether consciousness can be regained ex vivo is unknown. Herein, we developed normothermic machine perfusion (NMP) technology for ex vivo brain resuscitation after circulatory death. We found that perfusion of the brain alone was able to preserve circulation, cytoarchitecture, metabolic activity and brainstem function, but failed to regain consciousness. With supports of a functioning liver, global electrocorticographic activity and consciousness were restored. Brain function could be maintained for at least 22 hours. The technology was able to resuscitate consciousness of the brain suffering 50-min normothermic ischemia. These findings demonstrate that liver-assisting brain NMP can restore and maintain consciousness ex vivo after a prolonged interval post-mortem. " " " " " " " "
Peer Review Status:Awaiting Review