Hybrid quantum annealing via molecular dynamics

A novel quantum–classical hybrid scheme is proposed to efficiently solve large-scale combinatorial optimization problems. The key concept is to introduce a Hamiltonian dynamics of the classical flux variables associated with the quantum spins of the transverse-field Ising model. Molecular dynamics of the classical fluxes can be used as a powerful preconditioner to sort out the frozen and ambivalent spins for quantum annealers. The performance and accuracy of our smooth hybridization in comparison to the standard classical algorithms (the tabu search and the simulated annealing) are demonstrated by employing the MAX-CUT and Ising spin-glass problems.

Intraseasonal Variability of Air–Sea Fluxes over the Bay of Bengal during the Southwest Monsoon

In the Bay of Bengal (BoB), surface heat fluxes play a key role in monsoon dynamics and prediction. The accurate representation of large-scale surface fluxes is dependent on the quality of gridded reanalysis products. Meteorological and surface flux variables from five reanalysis products are compared and evaluated against in situ data from the Research Moored Array for African–Asian–Australian Monsoon Analysis and Prediction (RAMA) in the BoB. The reanalysis products: ERA-Interim (ERA-I), TropFlux, MERRA-2, JRA-55, and CFSR are assessed for their characterization of air–sea fluxes during the southwest monsoon season [June–September (JJAS)]. ERA-I captured radiative fluxes best while TropFlux captured turbulent and net heat fluxes Qnet best, and both products outperformed JRA-55, MERRA-2, and CFSR, showing highest correlations and smallest biases when compared to the in situ data. In all five products, the largest errors were in shortwave radiation QSW and latent heat flux QLH, with nonnegligible biases up to approximately 75 W m−2. The QSW and QLH are the largest drivers of the observed Qnet variability, thus highlighting the importance of the results from the buoy comparison. There are also spatially coherent differences in the mean basinwide fields of surface flux variables from the reanalysis products, indicating that the biases at the buoy position are not localized. Biases of this magnitude have severe implications on reanalysis products’ ability to capture the variability of monsoon processes. Hence, the representation of intraseasonal variability was investigated through the boreal summer intraseasonal oscillation, and we found that TropFlux and ERA-I perform best at capturing intraseasonal climate variability during the southwest monsoon season.

An approximation algorithm for the treatment of sound points in the CABARET scheme

Описана новая вычислительная технология расчета потоковых переменных на новом временном слое в разностных схемах типа Кабаре для численного решения квазилинейных гиперболических уравнений в частных производных. Новая технология позволяет единообразно рассматривать все случаи возникновения звуковых точек и не нарушает свойства временной обратимости разностных схем при отсутствии нелинейной коррекции потоков. A new numerical approach to the calculation of flux variables on a new time layer in the CABARET (Compact Accurately Boundary Adjusting-REsolution Technique) scheme for the numerical solution of quasilinear hyperbolic differential equations is described. This approach allows one to uniformly treat all cases of sound points and does not violate the time reversibility properties of difference schemes in the absence of nonlinear correction of fluxes.

GROUPS OF GENERALIZED FLUX TRANSFORMATIONS IN THE SPACE OF GENERALIZED CONNECTIONS

We present a group of transformations in the space of generalized connections that contains the set of transformations generated by the flux variables of loop quantum gravity. This group is labeled by certain SU(2)-valued functions on the bundle of directions in the spatial manifold. A further generalization is obtained by considering functions that depend on germs of analytic curves, rather than just on directions.

A Comparison between Direct and Calculated Oxygen Saturation in Intensive Care

We investigated the discrepancy between calculated and spectrophotometrically determined oxygen saturation, and the corresponding effect of this difference on calculated oxygen uptake in 46 arterial-venous sample pairs from 28 critically ill patients. The range of discrepancy between the two methods showed limits of agreement (mean ±2SD) of -2.26 to +0.70% for arterial samples, and - 5.52 to + 4.96% for the corresponding venous samples. The effect of this variation on oxygen uptake showed limits of agreement of -43.2 to 36.0 ml/min when the discrepancy between oxygen uptake, calculated using the direct measure of saturation, was compared to that using the derived value. Multiple regression analysis showed that Pco2, temperature and 2,3 diphosphoglycerate were significantly related to saturation discrepancy with an R-squared value of 0.64 (P< 0.0001) for a subgroup of 25 venous samples. The precision of the Po2 electrode was also found to be a major contributory component to the discrepancies, particularly at venous Po2 values. Thus the use of calculated oxygen saturation may result in clinically significant inaccuracies in the assessment of some oxygen flux variables.