Evaluating Energy Differences on a Quantum Computer with Robust Phase Estimation.

We adapt the robust phase estimation algorithm to the evaluation of energy differences between two eigenstates using a quantum computer. This approach does not require controlled unitaries between auxiliary and system registers or even a single auxiliary qubit. As a proof of concept, we calculate the energies of the ground state and low-lying electronic excitations of a hydrogen molecule in a minimal basis on a cloud quantum computer. The denominative robustness of our approach is then quantified in terms of a high tolerance to coherent errors in the state preparation and measurement. Conceptually, we note that all quantum phase estimation algorithms ultimately evaluate eigenvalue differences.

Poor survival after resection of early gastric cancer: extremes of survivorship analysis reveal distinct genomic profile.

A subset of patients with early gastric cancer demonstrate early recurrence and poor survival despite margin-negative resection. This study used an extremes-of-survivorship approach to identify an association between TP53 hotspot mutations co-occurring with loss of heterozygosity and unexpectedly poor survival in early gastric cancer. This distinct genomic profile may be a novel biomarker of poor survival in patients with completely resected early gastric cancer, and warrants large-scale validation. Promising, validation needed.

Nonideal transport of contaminants in heterogeneous porous media: 9 - impact of contact time on desorption and elution tailing.

A series of miscible-displacement experiments was conducted to examine the impact of sorption contact time on desorption and elution of trichloroethene from a well-characterized soil. A large number of contact times were examined, spanning 1h to 4 years (∼2 × 10(6)h). Effluent trichloroethene concentrations were monitored over a range of greater than six orders of magnitude, allowing characterization of potential asymptotic tailing. The results of the column experiments showed that trichloroethene exhibited extensive elution tailing for all experiments. Each increase in contact time resulted in a successive increase in the extent of tailing. In total, the number of pore volumes of water flushing required to reach the analytical detection limit increased from approximately 1000 for the 1-h contact time to almost 9000 for the 4-year contact time. These results indicate that a contact time of less than 1h produced a sorbed phase that is relatively resistant to desorption, and that a progressive increase in resistance to desorption occurred with increased contact time. A mathematical model incorporating nonlinear, rate-limited sorption/desorption described by a continuous-distribution reaction function was used to successfully simulate the measured data. The nonlinear sorption, the apparent rapid development of desorption resistance, and the progressive increase in resistance with increasing contact time are consistent with behavior anticipated for sorbate interactions with hard-carbon components of the soil.

Nonideal transport of contaminants in heterogeneous porous media: 10. Impact of co-solutes on sorption by porous media with low organic-carbon contents.

The impact of co-solutes on sorption of tetrachloroethene (PCE) by two porous media with low organic-carbon contents was examined by conducting batch experiments. The two media (Borden and Eustis) have similar physical properties, but significantly different organic-carbon (OC) contents. Sorption of PCE was nonlinear for both media, and well-described by the Freundlich equation. For the Borden aquifer material (OC=0.03%), the isotherms measured with a suite of co-solutes present (1,2-dichlorobenzene, bromoform, carbon tetrachloride, and hexachloroethane) were identical to the isotherms measured for PCE alone. These results indicate that there was no measurable impact of the co-solutes on PCE sorption for this system. In contrast to the Borden results, there was a measurable reduction in sorption of PCE by the Eustis soil (OC=0.38%) in the presence of the co-solutes. The organic-carbon fractions of both media contain hard-carbon components, which have been associated with the manifestation of nonideal sorption phenomena. The disparity in results observed for the two media may relate to relative differences in the magnitude and geochemical nature of these hard-carbon components.

NONIDEAL BEHAVIOR DURING COMPLETE DISSOLUTION OF ORGANIC IMMISCIBLE LIQUID: 1. IDEAL POROUS MEDIA.

Column experiments were conducted using ideal natural sands and stainless-steel beads to examine the complete dissolution behavior of an organic immiscible liquid. Trichloroethene (TCE) was used as the representative organic liquid. The elution curves exhibited multi-step behavior, with multiple extended periods of relatively constant contaminant flux. These secondary steady-state stages occurred at concentrations several orders-of-magnitude below aqueous solubility for the well-sorted sands. In contrast, the secondary steady-state stages occurred within one log of aqueous solubility for the poorly-sorted sand. The nonideal behavior is hypothesized to result from constraints to hydraulic accessibility of the organic liquid to flowing water, which may be expected to be mediated by the pore-scale configuration of the flow field and the fluid phases.

Characterizing pore-scale dissolution of organic immiscible liquid in a poorly-sorted natural porous medium.

Synchrotron X-ray microtomography was used to characterize the pore-scale morphology and distribution of an organic immiscible liquid (trichloroethene) during water flushing to examine dissolution dynamics. The experiments were conducted with a natural porous medium that has a large particle-size distribution. The results were compared to those of a previous experiment conducted with a well-sorted natural sand. The median organic-liquid blob volume was smaller, and smaller blobs composed a larger fraction of the distribution, for the poorly sorted medium. In addition, mass removal was less spatially uniform for the poorly sorted medium. The concentration of trichloroethene in the column effluent was monitored during dissolution to assess mass-flux behavior. A first-order mass transfer equation was used to simulate the measured elution curves. Organic-liquid/water interfacial areas measured with microtomography were used as input, and simulated effluent concentrations were compared to the measured effluent concentrations to determine best-fit values for the mass-transfer coefficient. The value obtained for the poorly sorted medium was approximately 10 times smaller than that obtained for the well-sorted medium. This disparity indicates that hydraulic accessibility of the organic liquid is more constrained for the poorly sorted medium, which would be consistent with a more complex pore-scale flow field for the poorly sorted medium.

Nonideal behavior during complete dissolution of organic immiscible liquid: 1. Natural porous media.

Experiments were conducted to investigate the complete dissolution of organic immiscible liquid residing within natural porous media. Organic-liquid dissolution was investigated by conducting experiments with homogeneously packed columns containing a residual saturation of organic liquid (trichloroethene). The porous media used comprised different textures (ranges of particle-size distributions) and organic-carbon contents. The dissolution behavior that was observed for the soil and aquifer sediment systems deviated from the behavior typically observed for systems composed of ideal sands. Specifically, multi-step elution curves were observed, with multiple extended periods of relatively constant contaminant flux. This behavior was more pronounced for the two media with larger particle-size distributions. Conversely, this type of dissolution behavior was not observed for the control system, which consisted of a well-sorted sand. It is hypothesized that the pore-scale configuration of the organic liquid and of the flow field is more complex for the poorly sorted media, and that this greater complexity constrains dissolution dynamics, leading to the observed nonideal behavior.