Monte Carlo explicitly correlated many-body Green's function theory.

A highly scalable stochastic algorithm is proposed and implemented for computing the basis-set-incompleteness correction to the diagonal, frequency-independent self-energy of the second-order many-body Green's function (GF2) theory within the explicitly correlated (F12) formalism. The 6-, 9-, 12-, and 15-dimensional integrals comprising the F12 correction are directly evaluated by the Monte Carlo method using appropriate weight functions for importance sampling. The method is naturally and easily parallelized, involves minimal memory space and no disk I/O, and can use virtually any mathematical form of a correlation factor. Its computational cost to correct all ionization energies (IEs) is observed to increase as the fourth power of system size, as opposed to the fifth power in the case of the deterministic counterparts. The GF2 calculations and their F12 corrections for the first IEs of C60 and C70 were executed on 128 graphical processing units (GF2) and 896 central processing units (F12), respectively, to reach the results with statistical errors of 0.04 eV or less. They showed that the basis-set-incompleteness (from aug-cc-pVDZ) accounts for only 50%-60% of the deviations from experiments, suggesting the significance of higher-order perturbation corrections.

The making of a pest: Insights from the evolution of chemosensory receptor families in a pestiferous and invasive fly, Drosophila suzukii.

BACKGROUND: Drosophila suzukii differs from other melanogaster group members in their proclivity for laying eggs in fresh fruit rather than in fermenting fruits. Olfaction and gustation play a critical role during insect niche formation, and these senses are largely mediated by two important receptor families: olfactory and gustatory receptors (Ors and Grs). Earlier work from our laboratory has revealed how the olfactory landscape of D. suzukii is dominated by volatiles derived from its unique niche. Signaling and reception evolve in synchrony, since the interaction of ligands and receptors together mediate the chemosensory behavior. Here, we manually annotated the Ors and Grs in D. suzukii and two close relatives, D. biarmipes and D. takahashii, and compared these repertoires to those in other melanogaster group drosophilids to identify candidate chemoreceptors associated with D. suzukii's unusual niche utilization. RESULTS: Our comprehensive annotations of the chemosensory genomes in three species, and comparative analysis with other melanogaster group members provide insights into the evolution of chemosensation in the pestiferous D. suzukii. We annotated a total of 71 Or genes in D. suzukii, with nine of those being pseudogenes (12.7 %). Alternative splicing of two genes brings the total to 62 genes encoding 66 Ors. Duplications of Or23a and Or67a expanded D. suzukii's Or repertoire, while pseudogenization of Or74a, Or85a, and Or98b reduced the number of functional Ors to roughly the same as other annotated species in the melanogaster group. Seventy-one intact Gr genes and three pseudogenes were annotated in D. suzukii. Alternative splicing in three genes brings the total number of Grs to 81. We identified signatures of positive selection in two Ors and three Grs at nodes leading to D. suzukii, while three copies in the largest expanded Or lineage, Or67a, also showed signs of positive selection at the external nodes. CONCLUSION: Our analysis of D. suzukii's chemoreceptor repertoires in the context of nine melanogaster group drosophilids, including two of its closest relatives (D. biarmipes and D. takahashii), revealed several candidate receptors associated with the adaptation of D. suzukii to its unique ecological niche.

Monte Carlo explicitly correlated second-order many-body perturbation theory.

A stochastic algorithm is proposed and implemented that computes a basis-set-incompleteness (F12) correction to an ab initio second-order many-body perturbation energy as a short sum of 6- to 15-dimensional integrals of Gaussian-type orbitals, an explicit function of the electron-electron distance (geminal), and its associated excitation amplitudes held fixed at the values suggested by Ten-no. The integrals are directly evaluated (without a resolution-of-the-identity approximation or an auxiliary basis set) by the Metropolis Monte Carlo method. Applications of this method to 17 molecular correlation energies and 12 gas-phase reaction energies reveal that both the nonvariational and variational formulas for the correction give reliable correlation energies (98% or higher) and reaction energies (within 2 kJ mol-1 with a smaller statistical uncertainty) near the complete-basis-set limits by using just the aug-cc-pVDZ basis set. The nonvariational formula is found to be 2-10 times less expensive to evaluate than the variational one, though the latter yields energies that are bounded from below and is, therefore, slightly but systematically more accurate for energy differences. Being capable of using virtually any geminal form, the method confirms the best overall performance of the Slater-type geminal among 6 forms satisfying the same cusp conditions. Not having to precompute lower-dimensional integrals analytically, to store them on disk, or to transform them in a nonscalable dense-matrix-multiplication algorithm, the method scales favorably with both system size and computer size; the cost increases only as O(n4) with the number of orbitals (n), and its parallel efficiency reaches 99.9% of the ideal case on going from 16 to 4096 computer processors.

Outcomes Following Anterior Cruciate Ligament Reconstruction with Patellar Tendon vs Hamstring Autografts: A Systematic Review of Randomized Controlled Trials with a Mean Follow-up of 15 Years.

Background: The two most common surgical treatment modalities for anterior cruciate ligament reconstruction (ACL), patellar tendon (PT) and hamstring tendon (HS) autografts, have been shown to have outcomes that are both similar and favorable; however, many of these are short or intermediate-term. The objective of this systematic review is to evaluate randomized controlled trials (RCTs) with a minimum 10-year follow-up data to compare the long-term outcomes of ACL reconstructions performed using PT and HS autografts. Methods: This systematic review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A search of three databases (PubMed, Cochrane and EMBASE) was performed to identify RCTs with a minimum of 10-year follow-up that compared clinical and/or functional outcomes between PT and HS autografts. Results: Four RCTs with a total of 299 patients were included in the study. The mean follow-up ranged from 10.2 to 17 years (mean, 14.79 years). No significant differences in knee laxity or clinical outcome scores were demonstrated in any of the studies. One study found that PT autografts were significantly more likely to have osteoarthritis identified by radiographic findings. Two studies found that patients with PT autografts reported increase kneeling pain, while none of the four studies reported a difference in anterior knee pain. There were no significant differences in graft failure rates. Conclusion: This review demonstrates no long-term difference in clinical or functional outcomes between PT and HS autografts. However, radiographic and subjective outcomes indicate that patients with PT autografts may experience greater kneeling pain and osteoarthritis. Therefore, orthopaedic surgeons should consider patient-centric factors when discussing graft options with patients.