2nd-order many-body perturbation approximations to the coupled-cluster Greens-function

The time‐consuming step in coupled cluster Green’s function or equivalently equation of motion coupled cluster calculations of ionization potentials is the solution of the CCSD equations. We investigate here the accuracy that can be obtained if the CCSD coefficients are replaced by their MBPT(2) analogs. We discuss some additional diagonal approximations that might prove especially useful in polymer calculations, and compare with traditional Green’s function calculations based on a second order approximation to the irreducible self‐energy

Review of biorthogonal coupled cluster representations for electronic excitation

Single reference coupled-cluster (CC) methods for electronic excitation are based on a biorthogonal representation (bCC) of the (shifted) Hamiltonian in terms of excited CC states, also referred to as correlated excited (CE) states, and an associated set of states biorthogonal to the CE states, the latter being essentially configuration interaction (CI) configurations. The bCC representation generates a non-hermitian secular matrix, the eigenvalues representing excitation energies, while the corresponding spectral intensities are to be derived from both the left and right eigenvectors. Using the perspective of the bCC representation, a systematic and comprehensive analysis of the excited-state CC methods is given, extending and generalizing previous such studies. Here, the essential topics are the truncation error characteristics and the separability properties, the latter being crucial for designing size-consistent approximation schemes. Based on the general order relations for the bCC secular matrix and the (left and right) eigenvector matrices, formulas for the perturbation-theoretical (PT) order of the truncation errors (TEO) are derived for energies, transition moments, and property matrix elements of arbitrary excitation classes and truncation levels. In the analysis of the separability properties of the transition moments, the decisive role of the so-called dual ground state is revealed. Due to the use of CE states the bCC approach can be compared to so-called intermediate state representation (ISR) methods based exclusively on suitably orthonormalized CE states. As the present analysis shows, the bCC approach has decisive advantages over the conventional CI treatment, but also distinctly weaker TEO and separability properties in comparison with a full (and hermitian) ISR method

Efficacy and safety of systemic induction therapy in initially unresectable locally advanced intrahepatic and perihilar cholangiocarcinoma: A systematic review

Background: According to international guidelines, induction therapy may be considered in selected patients with initially unresectable locally advanced cholangiocarcinoma. The criteria for (un)resectability in cholangiocarcinoma varies between studies and no consensus-based agreement is available about these criteria. By performing a systematic literature review, we aimed to investigate the efficacy and safety of systemic induction therapy in initially unresectable locally advanced perihilar (pCCA) and intrahepatic cholangiocarcinoma (iCCA) and summarize resectability criteria used across studies. Methods: A literature search was performed in PubMed, EMBASE, Web of Science and Cochrane library to identify studies on systemic induction therapy in locally advanced pCCA and/or iCCA. The primary outcome was resection rate (RR) after induction therapy and secondary outcomes were overall survival (OS) and objective response rate (ORR). Results: Ten studies with a total of 1167 patients met the inclusion criteria and were included in this review. Among these patients, 334 (28.6%) were treated with systemic induction therapy. Across the studies, different types of chemotherapy regimens were administered (e.g., gemcitabine (based) chemotherapy and 5-FU (based) chemotherapy). Only six studies provided sufficient data and were used to analyze pooled (radical) resection rates. After induction therapy, 94 patients (39.2%) underwent a resection, of which R0 resections (22.9%). Pooled data on OS showed, better OS for chemotherapy plus resection versus chemotherapy only (pooled HR = 0.31, 95% CI = 0.19–0.50; P value < 0.0001). Conclusion: Adequately selected patients with locally advanced pCCA or iCCA may benefit from induction therapy followed by surgical resection. Prospective randomized controlled trials are warranted

Constraining Conceptual Hydrological ModelsWith Multiple Information Sources

The calibration of hydrological models without streamflow observations is problematic, and the simultaneous, combined use of remotely sensed products for this purpose has not been exhaustively tested thus far. Our hypothesis is that the combined use of products can (1) reduce the parameter search space and (2) improve the representation of internal model dynamics and hydrological signatures. Five different conceptual hydrological models were applied to 27 catchments across Europe. A parameter selection process, similar to a likelihood weighting procedure, was applied for 1,023 possible combinations of 10 different data sources, ranging from using 1 to all 10 of these products. Distances between the two empirical distributions of model performance metrics with and without using a specific product were determined to assess the added value of a specific product. In a similar way, the performance of the models to reproduce 27 hydrological signatures was evaluated relative to the unconstrained model. Significant reductions in the parameter space were obtained when combinations included Advanced Microwave Scanning Radiometer ‐ Earth Observing System and Advanced Scatterometer soil moisture, Gravity Recovery and Climate Experiment total water storage anomalies, and, in snow‐dominated catchments, the Moderate Resolution Imaging Spectroradiometer snow cover products. The evaporation products of Land Surface Analysis ‐ Satellite Application Facility and MOD16 were less effective for deriving meaningful, well‐constrained posterior parameter distributions. The hydrological signature analysis indicated that most models profited from constraining with an increasing number of data sources. Concluding, constraining models with multiple data sources simultaneously was shown to be valuable for at least four of the five hydrological models to determine model parameters in absence of streamflow

Value of routine intraoperative frozen sections of proximal bile duct margins in perihilar cholangiocarcinoma, a retrospective multicenter and matched case-control study

Background: Currently, the potential benefits of additional resection after positive proximal intraoperative frozen sections (IFS) in perihilar cholangiocarcinoma (pCCA) on residual disease and oncological outcome remain uncertain. Therefore, the aim of this study is to investigate the number of R0 resections after additional resection of a positive proximal IFS and the influence of additional resections on overall survival (OS) in patients with pCCA. Materials and methods: A retrospective, multicenter, matched case-control study was performed, including patients undergoing resection for pCCA between 2000 and 2019 at three tertiary centers. Primary outcome was the number of achieved ‘additional’ R0 resections. Secondary outcomes were OS, recurrence, severe morbidity and mortality. Results: Forty-four out of 328 patients undergoing resection for pCCA had a positive proximal IFS. An additional resection was performed in 35 out of 44 (79.5%) patients, which was negative in 24 (68.6%) patients. Nevertheless, seven out of these 24 patients were eventually classified as R1 resection due to other positive resection margins. Therefore, 17 (48.6%) patients could be classified as “true” R0 resection after additional resection. Ninety-day mortality after R1 resections was high (25%) and strongly influenced OS. After correction for 90-day mortality, median OS after negative additional resection was 33 months (95%CI:29.5–36.5) compared to 30 months (95%CI:24.4–35.6) after initial R1 (P = 0.875) and 46 months (95%CI:32.7–59.3) after initial R0 (P = 0.348). Conclusion: There were only 17 patients (out of a total of 328 patients) that potentially benefitted from routine IFS. Additional resection for a positive IFS leading to R0 resection was not associated with improved long-term survival

Value of routine intraoperative frozen sections of proximal bile duct margins in perihilar cholangiocarcinoma, a retrospective multicenter and matched case-control study

Background: Currently, the potential benefits of additional resection after positive proximal intraoperative frozen sections (IFS) in perihilar cholangiocarcinoma (pCCA) on residual disease and oncological outcome remain uncertain. Therefore, the aim of this study is to investigate the number of R0 resections after additional resection of a positive proximal IFS and the influence of additional resections on overall survival (OS) in patients with pCCA. Materials and methods: A retrospective, multicenter, matched case-control study was performed, including patients undergoing resection for pCCA between 2000 and 2019 at three tertiary centers. Primary outcome was the number of achieved ‘additional’ R0 resections. Secondary outcomes were OS, recurrence, severe morbidity and mortality. Results: Forty-four out of 328 patients undergoing resection for pCCA had a positive proximal IFS. An additional resection was performed in 35 out of 44 (79.5%) patients, which was negative in 24 (68.6%) patients. Nevertheless, seven out of these 24 patients were eventually classified as R1 resection due to other positive resection margins. Therefore, 17 (48.6%) patients could be classified as “true” R0 resection after additional resection. Ninety-day mortality after R1 resections was high (25%) and strongly influenced OS. After correction for 90-day mortality, median OS after negative additional resection was 33 months (95%CI:29.5–36.5) compared to 30 months (95%CI:24.4–35.6) after initial R1 (P = 0.875) and 46 months (95%CI:32.7–59.3) after initial R0 (P = 0.348). Conclusion: There were only 17 patients (out of a total of 328 patients) that potentially benefitted from routine IFS. Additional resection for a positive IFS leading to R0 resection was not associated with improved long-term survival