Large Systems Research Articles

Clamp for Safety: Improving Intravesical Chemotherapy Practices.

Processes for intravesical chemotherapy after transurethral resection of nonmuscle invasive bladder tumors may lack standardization. In 2019, at a large health care system in Los Angeles, California, five incident reports involving chemotherapeutic agent spills from urinary catheters after bladder tumor procedures necessitated a quality improvement project. The project lead determined that a cost-effective alternative device for securing the chemotherapeutic agent in the bladder was needed at four surgical locations of the health care system. In addition, a review of the literature and an observational assessment revealed lack of adherence to standard and recommended processes for using personal protective equipment (PPE) when handling hazardous medications. After revising existing processes, acquiring a cost-effective clamp and recommended chemotherapy PPE, instructing personnel on the clamping process and use of PPE, and implementing use of the clamp, there have been no spills associated with intravesical chemotherapy across the four surgical locations.

Evaluation of Aspirin Prescribing and Gastrointestinal Bleeding in Adults 60 Years of Age and Older in a Large, Academic Health System.

Background National guidelines no longer recommend adults 60 years of age and older to begin treatment with low-dose daily aspirin for primary prevention of atherosclerotic cardiovascular disease (CVD) due to a lack of proven net benefit and a higher risk of bleeding. Objective The objective of this cross-sectional retrospective analysis was to evaluate the appropriateness of low-dose aspirin prescribing and subsequent gastrointestinal bleeding in older persons receiving primary care in a large academic health system. Setting Large, academic health system within Colorado. Patients Patients with an active order for daily low-dose aspirin as of July 1, 2021, were assessed for appropriateness based on indication (primary vs secondary prevention) and use of a concomitant proton-pump inhibitor (PPI). Incident gastrointestinal bleeds (GIBs) in the subsequent 12 months and GIB risk factors were also evaluated. Results A total of 19,525 patients were included in the analysis. Eighty-nine percent of patients identified as White and 54% identified as male. Of the total cohort, 44% had CVD and 19% were co-prescribed a PPI. GIB occurred in 247 patients (1.27%) within the subsequent year. Risk factors significantly associated with a GIB within 1 year included: history of GIB, history of peptic ulcer disease, other esophageal issue (esophagitis, Barrett's esophagus, Mallory Weiss tears, etc.), 75 years of age or older, and history of gastroesophageal reflux disease. Conclusion This evaluation found that many older persons at this institution may be inappropriately prescribed aspirin, providing opportunities for pharmacists to improve medication safety by deprescribing aspirin among primary prevention patients or potentially co-prescribing a PPI in secondary prevention patients.

Lipoprotein(a) Levels in Disaggregated Racial and Ethnic Subgroups Across Atherosclerotic Cardiovascular Disease Risk Levels

BackgroundLipoprotein(a) [Lp(a)] is a causal risk factor for atherosclerotic cardiovascular disease (ASCVD). ObjectivesThe authors assessed differences in Lp(a) testing and levels by disaggregated race, ethnicity, and ASCVD risk. MethodsThis was a retrospective cohort study of patients from a large California health care system from 2010 to 2021. Eligible individuals were ≥18 years old, with ≥2 primary care visits, and complete race and ethnicity data who underwent Lp(a) testing. Race and ethnicity were self-reported and categorized as follows: non-Hispanic (NH) White, NH-Black, Hispanic (Mexican, Puerto Rican, other), NH-Asian (Asian Indian, Chinese, Filipino, Japanese, Korean, Vietnamese, other). Logistic regression models tested associations between elevated Lp(a) (≥50 mg/dL) and race, ethnicity, and ASCVD risk. Results13,689 (0.9%) individuals underwent Lp(a) testing with a mean age of 54.6 ± 13.8 years, 49% female, 28.8% NH Asian. Over one-third of those tested had Lp(a) levels ≥50 mg/dL, ranging from 30.7% of Mexican patients to 62.6% of NH-Black patients. The ASCVD risk of those tested varied by race: 73.6% of Asian Indian individuals had <5% 10-year risk, whereas 27.2% of NH-Black had established ASCVD. Lp(a) prevalence ≥50 mg/dL increased across the ASCVD risk spectrum. After adjustment, Hispanic (OR: 0.76 [95% CI: 0.66-0.88]) and Asian (OR: 0.88 [95% CI: 0.81-0.96]) had lower odds of Lp(a) ≥50 mg/dL, whereas Black individuals had higher odds (OR: 2.46 [95% CI: 1.97-3.07]). ConclusionsLp(a) testing is performed infrequently. Of those tested, Lp(a) levels were frequently elevated and differed significantly across disaggregated race and ethnicity groups. The prevalence of elevated Lp(a) increased with increasing ASCVD risk, with significant variation by race and ethnicity.

Machine learning assisted improved desalination pilot system design and experimentation for the circular economy

Desalination is among the most feasible solutions to supply sustainable and clean drinking water in water scarcity areas. In this regard, Multi-Effect Desalination (MED) systems are particularly preferred for harsh feeds (high temperature and salinity) because of their robust mode of operation for water production. However, maintaining the efficient operation of the MED systems is challenging because of the large system design and variables' interdependencies that are sensitive to the distillate production. Therefore, this research leverages the power of machine learning and optimization to estimate the optimal operating conditions for the maximum distillate production from the MED system. In the first step, detailed experimentation is conducted for distillate production against hot water temperature (HWT) varying from 38 to 70 °C, and feed water temperature (FWT) is changed from 34 to 42 °C. Whereas, the feed flow rate (FFR) is investigated to be varied nearly from 3.6 to 8.7 LPM in the three stages, i.e., FFR-S1, FFR-S2 and FFR-S3. The compiled dataset is used to make the process models of the MED system by three ML-based algorithms, i.e., Artificial Neural Network (ANN), Support Vector Machine (SVM), and Gaussian Process Regression (GPR) under rigorous hyperparameters optimization. GPR exhibited superior predictive performance than those of ANN and SVM on R2 value of 0.99 and RMSE of 0.026 LPM. Monte Carlo technique-based variable significance analysis revealed that the HWT has the highest effect on distillate production with a percentage significance of 95.6 %. Then Genetic Algorithm is used to maximize the distillate production with the GPR model embedded in the optimization problem. The GPR-GA driven maximum distillate production is estimated on HWT = 70 ± 0.5 °C, FWT = 40 ± 2.5 °C, FFR-S1 = 6 ± 2.6 LPM, FFR-S2 = 7 ± 1 LPM and FFR-S3 = 7 ± 1. The ML-GA-based system analysis and optimization of the MED system can boost the distillate production that promotes operation excellence and circular economy from the desalination sector.

The eXact integral simplified time-dependent density functional theory (XsTD-DFT).

In the framework of simplified quantum chemistry methods, we introduce the eXact integral simplified time-dependent density functional theory (XsTD-DFT). This method is based on the simplified time-dependent density functional theory (sTD-DFT), where all semi-empirical two-electron integrals are replaced by exact one- and two-center two-electron integrals, while other approximations from sTD-DFT are kept. The performance of this new parameter-free XsTD-DFT method was benchmarked on excited state and (non)linear response properties, including ultra-violet/visible absorption, first hyperpolarizability, and two-photon absorption (2PA). For a set of 77 molecules, the results from the XsTDA approach were compared to the TDA data. XsTDA/B3LYP excitation energies only deviate on average by 0.14eV from TDA while drastically cutting computational costs by a factor of 20 or more depending on the energy threshold chosen. The absolute deviations of excitation energies with respect to the full scheme are decreasing with increasing system size, showing the suitability of XsTDA/XsTD-DFT to treat large systems. Comparing XsTDA and its predecessor sTDA, the new scheme generally improves excitation energies and oscillator strengths, in particular, for charge transfer states. TD-DFT first hyperpolarizability frequency dispersions for a set of push-pull π-conjugated molecules are faithfully reproduced by XsTD-DFT, while the previous sTD-DFT method provides redshifted resonance energy positions. Excellent performance with respect to the experiment is observed for the 2PA spectrum of the enhanced green fluorescent protein. The obtained robust accuracy similar to TD-DFT at a fraction of the computational cost opens the way for a plethora of applications for large systems and in high throughput screening studies.

Improved mountain gazelle optimizer based interactive distributed strategy to solving large scale OPF

This paper focuses on solving the multi-objective optimal power flow of large-scale power systems under critical loading margin stability with accuracy using a novel improved mountain gazelle optimizer (IMGO)-based flexible distributed strategy. Multi-shunt compensator-based flexible alternative current transmission systems (FACTS), such as SVC and STATCOM devices, are integrated at specified locations to exchange reactive power with the network. Several metaheuristic methods can solve the standard OPF related to small and medium test systems. However, by considering large-scale electric systems based on FACTS devices and renewable energy and by considering the operation under loading margin stability, the majority of these techniques fail to achieve a near-global solution because of the high dimension and nonlinearity of the problem to be solved. This study proposes the Multi-Objective OPF-Based Distributed Strategy (MO-OPFDS), a new planning strategy that optimizes individually and simultaneously various objective functions, in particular the total power loss (T∆P), and the total voltage deviation (T∆V). Standard MGO search is enhanced by automatically balancing exploration and exploitation throughout the search. The robustness of the proposed variant was validated on a large electric test system, the IEEE 118-Bus, and on the Algerian Network 114-Bus under normal conditions and at critical loading margin stability. The obtained results compared with several recent techniques clearly confirm the high performance of the proposed method in terms of solution accuracy and convergence behavior.

Late Paleozoic high-K calc-alkaline to shoshonitic series magmatism and related W(-Mo-Cu-Au) metallogeny of the Kyrgyz Tien Shan, Central Asia

Abstract In the Kyrgyz Tien Shan, numerous high-K calc-alkaline to shoshonitic series intrusions are associated with the large fault system known as the “Major structural line of Tien Shan”, or “Nikolaev Line”. During the Carboniferous, this lineament represented a zone of intracontinental, possibly back-arc rifting associated with a north-dipping subduction, whereas in the Late Carboniferous to Permian it was part of a larger continental collision structure. These Late Paleozoic high-potassic intrusions comprise numerous intrusive phases that vary in composition from the early mafic (monzogabbro, monzodiorite) through intermediate (monzonite, syenite, quartz syenite) to late stage and more evolved (quartz monzonite, granodiorite, monzogranite, leucogranite-alaskite) members locally intersected by monzodiorite-porphyry and lamprophyre dikes. They can be related to low degrees (from ∼1-2 to 2-2.5 vol.%) partial melting of metasomatically-enriched upper mantle followed by magma fractionation and emplacement at shallower crustal levels. In summary, the high-K magmas formed in continental- and post-collisional arc settings with a progressive input of crustal material. From the west to the east, the potassic intrusions contain progressively higher Nb and Y concentrations reflecting their derivation in a post-collisional setting. The A-type granite signatures also become more distinct in this direction. This is consistent with the tectonic model implying the “scissor-like” closure of the Late Paleozoic Turkestan paleo-ocean from east to west. These high-potassic intrusions are accompanied by W-Mo-Cu-Au skarn/porphyry to Au(-W) replacement-style deposits, which are part of the extended Au (Au-W-Mo-Cu) metallogenic belt of Tien Shan. The association of skarn and porphyry-style W-Mo to Mo-Cu-Au-W mineralization defines these “porphyry-skarn” systems as a distinct group containing strongly oxidized andradite-dominant skarns. An early W partitioning into magmatic-hydrothermal fluid, together with Mo and Cu, is typical of this magmatic-hydrothermal system and can be explained by an early H 2 O saturation of the parental magma. The late-stage mafic dykes including lamprophyres probably reflect the presence of another, but concealed, mafic intrusion releasing CO 2 and metals, such as Au, As, Sb, Bi, and Te, into the hydrothermal mineral system.

Assessing Corridor Safety Performance at Approaches to Freeway Interchanges Using Lane Change Data

Urban arterials near freeway interchanges are vital components of urban road infrastructure, connecting high-mobility freeway networks to the more accessible but lower-mobility urban network. In this study, the operational safety of these arterials is examined and the relationship between roadway geometry and safety performance is investigated. To assess operational safety, lane changes were considered as a risk factor, and the number of lane changes in each study subsegment was recorded. Segments were categorized as upstream or downstream based on their location relative to the intersection. The number of lane changes served as a safety performance measure, and was analyzed using linear regression models. The results indicate that downstream segments experienced decreased safety performance when median storages were present, while adding right running bays improved safety. Median openings and increased numbers of driveways negatively affected safety in these segments. For upstream segments, right turning bays were found to impair safety performance the most, followed by the number of driveways. The closer the driveways were to the interchange; the worse was the effect on the safety performance. In summary, this research highlights the importance of geometric design elements when considering the safety performance of urban arterials. It is crucial to consider geometric design elements, such as median storages, driveways, and other elements, as a part of a larger system rather than isolated elements, so as to provide safer arterials near freeway interchanges.

A retrospective review of rasburicase utilization in pediatric and adult patients across a large health system.

This study aimed to characterize rasburicase dosing and duration. Secondary objectives included characterizing the indication of rasburicase and identifying the utilization of prophylactic therapy for tumor lysis syndrome (TLS). This retrospective review included patients 0 to 89 years old admitted between 1 January 2021 and 31 December 2021, and received at least one dose of rasburicase. Patients were excluded if they were >89 years old, pregnant, lactating, or received rasburicase outpatient. A total of 192 patients, 176 adults and 16 pediatric patients were included in the retrospective review. Of the total population, 184 received a fixed dose of rasburicase and 8 patients received a weight-based dose (0.15 mg/kg/dose) of rasburicase. The average dose administered was 3.4 mg for fixed and 2.99 mg for weight-based dosing. Nearly half (49.5%) the patients received rasburicase for an elevated uric acid but did not meet Cairo-Bishop criteria for TLS. Only 42.2% received at least one dose of allopurinol within 5 days prior to rasburicase and 18.8% received aggressive hydration within 72 h prior to rasburicase. The majority of rasburicase administered was ordered as fixed dose for a uric acid level ≥7.5 mg/dL. Most patients did not meet criteria for laboratory or clinical TLS and less than half the patients received prophylactic allopurinol and/or aggressive hydration. These study results are supported by recent literature for fixed dose rasburicase as a safe and economical dosing strategy compared to weight-based dosing.

Duality between predictability and reconstructability in complex systems

Predicting the evolution of a large system of units using its structure of interaction is a fundamental problem in complex system theory. And so is the problem of reconstructing the structure of interaction from temporal observations. Here, we find an intricate relationship between predictability and reconstructability using an information-theoretical point of view. We use the mutual information between a random graph and a stochastic process evolving on this random graph to quantify their codependence. Then, we show how the uncertainty coefficients, which are intimately related to that mutual information, quantify our ability to reconstruct a graph from an observed time series, and our ability to predict the evolution of a process from the structure of its interactions. We provide analytical calculations of the uncertainty coefficients for many different systems, including continuous deterministic systems, and describe a numerical procedure when exact calculations are intractable. Interestingly, we find that predictability and reconstructability, even though closely connected by the mutual information, can behave differently, even in a dual manner. We prove how such duality universally emerges when changing the number of steps in the process. Finally, we provide evidence that predictability-reconstruction dualities may exist in dynamical processes on real networks close to criticality.

Neonatal and Obstetrical Outcomes of Pregnancies Complicated by Alloimmunization.

Despite advances in the prevention of rhesus (Rh)(D) alloimmunization, alloantibodies to Rh(D) and non-Rh(D) red blood cell antigens continue to be detected in ∼4% of US pregnancies and can result in hemolytic disease of the fetus and newborn (HDFN). Recent reports on HDFN lack granularity and are unable to provide antibody-specific outcomes. The objective of this study was to calculate the frequency of alloimmunization in our large hospital system and summarize the outcomes based on antibody specificity, titer, and other clinical factors. We identified all births in a 6-year period after a positive red blood cell antibody screen result during pregnancy and summarized their characteristics and outcomes. A total of 707 neonates were born after a positive maternal antibody screen result (3.0/1000 live births). In 31 (4%), the positive screen result was due to rhesus immune globulin alone. Of the 676 neonates exposed to alloantibodies, the direct antibody test (DAT) result was positive, showing antigen-positivity and evidence of HDFN in 37% of those tested. Neonatal disease was most severe with DAT-positive anti-Rh antibodies (c, C, D, e, E). All neonatal red blood cell transfusions (15) and exchange transfusions (6) were due to anti-Rh alloimmunization. No neonates born to mothers with anti-M, anti-S, anti-Duffy, anti-Kidd A, or anti-Lewis required NICU admission for hyperbilirubinemia or transfusion. Alloimmunization to Rh-group antibodies continues to cause a majority of the severe HDFN cases in our hospital system. In neonates born to alloimmunized mothers, a positive DAT result revealing antigen-positivity is the best predictor of anemia and hyperbilirubinemia.

Beyond Single-Reference Fixed-Node Approximation in Ab Initio Diffusion Monte Carlo Using Antisymmetrized Geminal Power Applied to Systems with Hundreds of Electrons.

Diffusion Monte Carlo (DMC) is an exact technique to project out the ground state (GS) of a Hamiltonian. Since the GS is always bosonic, in Fermionic systems, the projection needs to be carried out while imposing antisymmetric constraints, which is a nondeterministic polynomial hard problem. In practice, therefore, the application of DMC on electronic structure problems is made by employing the fixed-node (FN) approximation, consisting of performing DMC with the constraint of having a fixed, predefined nodal surface. How do we get the nodal surface? The typical approach, applied in systems having up to hundreds or even thousands of electrons, is to obtain the nodal surface from a preliminary mean-field approach (typically, a density functional theory calculation) used to obtain a single Slater determinant. This is known as single reference. In this paper, we propose a new approach, applicable to systems as large as the C60 fullerene, which improves the nodes by going beyond the single reference. In practice, we employ an implicitly multireference ansatz (antisymmetrized geminal power wave function constraint with molecular orbitals), initialized on the preliminary mean-field approach, which is relaxed by optimizing a few parameters of the wave function determining the nodal surface by minimizing the FN-DMC energy. We highlight the improvements of the proposed approach over the standard single-reference method on several examples and, where feasible, the computational gain over the standard multireference ansatz, which makes the methods applicable to large systems. We also show that physical properties relying on relative energies, such as binding energies, are affordable and reliable within the proposed scheme.

Time‐Resolved Optical Response of the Dicke's Model via the Nonequilibrium Green's Function Approach

Due to their conceptual appeal and computational convenience, two‐level systems (TLSs) and generalizations are used to investigate nonlinear behavior in quantum optics and assess the applicability of theoretical methods. Herein, the focus is on second‐harmonic generation (SHG) and, as system of interest, on the Dicke model, which consists of several TLSs inside an optical cavity. The main aspect addressed is the scope of nonequilibrium Green's function (NEGF) to describe the effect of inhomogeneities and electron–electron (e–e) interactions on the SHG signal. For benchmarking purposes, exact diagonalization (ED) results are also presented and discussed. SHG spectra obtained with NEGF and ED are found to be in very good mutual agreement in most situations. Furthermore, inhomogeneity in the TLS and e–e interactions reduce the SHG signal, and the reduction is stronger with inhomogeneity than with interactions. This trend is consistently noted across different (small to large) system sizes. Finally, a modified NEGF approach is proposed to account for cavity leakage, where the quantum photon fields are coupled to a bath of classical oscillators. As expected, within this mixed quantum‐classical scheme, a decrease in the intensity of the fluorescent spectra takes place depending on the entity of leakage.

#1704 GLP-1RA versus DPP-4 inhibitors and rates of hyperkalemia and discontinuation of renin-angiotensin system (RAS) blockade in Swedish routine care

Abstract Background and Aims Emerging evidence suggest that glucagon-like peptide-1 receptor agonists (GLP-1RA) influence tubular handling of electrolytes and increase potassium excretion, which may translate into reduced risk of hyperkalemia. Hyperkalemia is a common complication that limits persistence on guideline-recommended RAS inhibitors (RASi). Here, we quantified and compared rates of hyperkalemia and RASi discontinuation among users of GLP-1RA versus dipeptidyl peptidase-4 inhibitors (DPP-4i) in a large healthcare system. Method We used data from the SCREAM project (Jan 2008-Dec 2021) to conduct a population-based active-comparator, new-user cohort study of adults with type-2 diabetes who started GLP-1RA or DPP-4i. The primary outcome was hyperkalemia occurrence, overall (plasma potassium&amp;gt;5.0 mmol/L) and by severity (mild -potassium &amp;gt;5-≤5.5 mmol/L- and moderate-severe -potassium &amp;gt;5.5 mmol/L- hyperkalemia). Among ongoing RASi users, we assessed time to RASi discontinuation through evaluation of subsequent RASi dispensations. Cox regression with inverse probability of treatment weighting (IPTW) was used to estimate pooled hazard ratios (HRs) and rate differences. Major cardiovascular events (MACEs) served as positive control outcome to evaluate unmeasured confounding bias. Results During a median follow-up of 3.0 (Interquartile range [IQR] 1.2-5.6) years, we identified 33 280 eligible participants, of which 13 633 started GLP-1RA and 19 647 DPP-4i. Mean age was 64 years and 40% were women. Compared with DPP-4i, starting GLP-1RA was associated with a lower rate of hyperkalemia (Hazard ratio [HR] 0.91; 95% CI: 0.84-0.99, Fig. 1), with no suggestion of effect modification by baseline eGFR strata (HR 0.91 (0.78-1.07) for eGFR ≥60 and HR 0.92 (0.83-1.01) for eGFR &amp;lt;60 ml/min/1.73 m2, P for interaction &amp;gt;0.05). Similar findings were observed for mild (HR 0.90; 0.83-0.98) and moderate-severe (HR 0.92; 0.80-1.06) hyperkalemia. Out of 21 751 participants that were using RASi, 8 463 discontinued this therapy during median 2.0 (0.7, 4.1) years of follow-up. Initiation of GLP-1RA vs. DPP-4i was associated with lower rate of RASi discontinuation (HR: 0.93; 0.87-0.98), with no interaction across strata of baseline eGFR (HR 0.97 (0.83-1.12) for eGFR ≥60 and HR 0.93 (0.87-0.99) for &amp;lt;60 ml/min/1.73 m2, P for interaction &amp;gt;0.05). Consistent with trial evidence, we observed a lower rate of MACE for GLP-1RA vs DPP-4i (HR 0.87; 0.78-0.98). Conclusion In patients with diabetes managed in routine care, the use of GLP-1RA was associated with lower rates of hyperkalemia and discontinuation of RASi compared with DPP-4i, providing further observational evidence in support of the use of these medications.

Morphometric fingerprints and downslope evolution in bathymetric surveys: insights into morphodynamics of the Congo canyon-channel

Submarine canyons and channels are globally important pathways for sediment, organic carbon, nutrients and pollutants to the deep sea, and they form the largest sediment accumulations on Earth. However, studying these remote submarine systems comprehensively remains a challenge. In this study, we used the only complete-coverage and repeated bathymetric surveys yet for a very large submarine system, which is the Congo Fan off West Africa. Our aim is to understand channel-modifying features such as subaqueous landslides, meander-bend evolution, knickpoints and avulsions by analyzing their morphometric characteristics. We used a new approach to identify these channel-modifying features via morphometric fingerprints, which allows a systematic and efficient search in low-resolution bathymetry data. These observations have led us to identify three morphodynamic reaches within the Congo Canyon-Channel. The upper reach of the system is characterized by landslides that can locally block the channel, storing material for extended periods and re-excavating material through a new incised channel. The middle reach of the system is dominated by the sweep and swing of meander bends, although their importance depends on the channel’s age, and the time since the last up-channel avulsion. In the distal and youngest part of the system, an upstream migrating knickpoint is present, which causes multi-stage sediment transport and overspill through an underdeveloped channel with shallow depths. These findings complement previous less-detailed morphometric analyses of the Congo Canyon-Channel, offering a clearer understanding of how submarine canyon-channels can store sediment (due to channel-damming landslides, meander point bars, levee building due to overspill), re-excavate that sediment (via thalweg incision, meander propagation, knickpoint migration) and finally transport it to the deep sea. This improved understanding of the morphodynamics of the Congo Canyon-Channel may help to understand the evolution of other submarine canyon-channels, and assessment of hazards faced by seabed infrastructure such as telecommunication cables.

About feasibility of SpaceX's human exploration Mars mission scenario with Starship

After decades where human spaceflight missions have been reserved to low Earth orbit, recent years have seen mission proposals and even implemented plans, e.g. with the mission Artemis I, for returning to the lunar surface. SpaceX has published over various media (e.g., its official website, conference presentations, user manual) conceptual information for its reusable Starship to enable human exploration missions to the Martian surface by the end of the decade. The technological and human challenges associated with these plans are daunting. Such a mission at that distance would require excellent system reliability and in-situ-resource utilization on a grand scale, e.g. to produce propellant. The plans contain little details however and have not yet been reviewed concerning their feasibility. In this paper we show significant technological gaps in these plans. Based on estimates and extrapolated data, a mass model as needed to fulfill SpaceX’s plans could not be reproduced and the subsequent trajectory optimization showed that the current plans do not yield a return flight opportunity, due to a too large system mass. Furthermore, significant gaps exist in relevant technologies, e.g. power supply for the Martian surface. It is unlikely that these gaps can be closed until the end of the decade. We recommend several remedies, e.g. stronger international participation to distribute technology development and thus improve feasibility. Overall, with the limited information published by SpaceX about its system and mission scenario and extrapolation from us to fill information gaps, we were not able to find a feasible Mars mission scenario using Starship, even when assuming optimal conditions such as 100% recovery rate of crew consumables during flight.

Impacts of two high‐head dams on macroinvertebrate communities in the regulated river reaches of Wujiang River, China

AbstractThe impact of two high‐head dams on macroinvertebrate communities within the regulated reaches of the Wujiang River in China was explored, using longitudinal monitoring data spanning from 2006 to 2016. In this study, we set up 10 sampling sites categorized into four areas based on different stressors and defined three stages based on the timeline of dam construction. Our findings revealed significant changes in community composition before and after dam impoundment. While certain original dominant taxa, such as Rivularia globosa and Lithoglyphopsis ovatus, remained dominant throughout the stages, mayflies and caddisflies nearly vanished in the downstream reaches of the dams. This trend was accompanied by the disappearance of taxa with low adaptability and the emergence of tolerant taxa downstream of the dams. Additionally, typical limnological taxa colonized the inundated reaches. Dam impoundment affected not only macroinvertebrate community composition but also diversity. In this study, the recovery effect of communities downstream of dams was not observed due to the limited distance, but the presence of Wujiangdu Dam upstream of the two dams for over 20 years makes us believe that in a large river system, macroinvertebrate communities downstream of high‐head dams may fully recover if the distance from the dams is long enough. The original and vulnerable species R. globosa, which demonstrated remarkable adaptability and thrived downstream of dams, should be further studied in the future.

Ultra-flat bands at large twist angles in group-V twisted bilayer materials.

Flat bands in 2D twisted materials are key to the realization of correlation-related exotic phenomena. However, a flat band often was achieved in the large system with a very small twist angle, which enormously increases the computational and experimental complexity. In this work, we proposed group-V twisted bilayer materials, including P, As, and Sb in the β phase with large twist angles. The band structure of twisted bilayer materials up to 2524 atoms has been investigated by a deep learning method DeepH, which significantly reduces the computational time. Our results show that the bandgap and the flat bandwidth of twisted bilayer β-P, β-As, and β-Sb reduce gradually with the decreasing of twist angle, and the ultra-flat band with bandwidth approaching 0eV is achieved. Interestingly, we found that a twist angle of 9.43° is sufficient to achieve the band flatness for β-As comparable to that of twist bilayer graphene at the magic angle of 1.08°. Moreover, we also find that the bandgap reduces with decreasing interlayer distance while the flat band is still preserved, which suggests interlayer distance as an effective routine to tune the bandgap of flat band systems. Our research provides a feasible platform for exploring physical phenomena related to flat bands in twisted layered 2D materials.

Quasi-degenerate extension of local N-electron valence state perturbation theory with pair-natural orbital method based on localized virtual molecular orbitals.

Chemical phenomena involving near-degenerate electronic states, such as conical intersections or avoided crossing, can be properly described using quasi-degenerate perturbation theory. This study proposed a highly scalable quasi-degenerate second-order N-electron valence state perturbation theory (QD-NEVPT2) using the local pair-natural orbital (PNO) method. Our recent study showed an efficient implementation of the PNO-based state-specific NEVPT2 method using orthonormal localized virtual molecular orbitals (LVMOs) as an intermediate local basis. This study derived the state-coupling (or off-diagonal) terms to implement QD-NEVPT2 in an alternative manner to enhance efficiency based on the internally contracted basis and PNO overlap matrices between different references. To facilitate further acceleration, a local resolution-of-the-identity (RI) three-index integral generation algorithm was developed using LMOs and LVMOs. Although the NEVPT2 theory is considered to be less susceptible to the intruder-state problem (ISP), this study revealed that it can easily suffer from ISP when calculating high-lying excited states. We ameliorated this instability using the imaginary level shift technique. The PNO-QD-NEVPT2 calculations were performed on small organic molecules for the 30 lowest-lying states, as well as photoisomerization involving the conical intersection of 1,1-dimethyldibenzo[b,f] silepin with a cis-stilbene skeleton. These calculations revealed that the PNO-QD-NEVPT2 method yielded negligible errors compared to the canonical QD-NEVPT2 results. Furthermore, we tested its applicability to a large photoisomerization system using the green fluorescent protein model and the ten-state calculation of the large transition metal complex, showcasing that off-diagonal elements can be evaluated at a relatively low cost.

A Primary Care–Based Weight Navigation Program

Evidence-based weight management treatments (WMTs) are underused; strategies are needed to increase WMT use and patients' weight loss. To evaluate the association of a primary care-based weight navigation program (WNP) with WMT use and weight loss. This cohort study comprised a retrospective evaluation of a quality improvement program conducted from October 1, 2020, to September 30, 2021. Data analysis was performed from August 2, 2022, to March 7, 2024. Adults with obesity and 1 or more weight-related condition from intervention and control sites in a large academic health system in the Midwestern US were propensity matched on sociodemographic and clinical factors. WNP, in which American Board of Obesity Medicine-certified primary care physicians offered weight-focused visits and guided patients' selection of preference-sensitive WMTs. Primary outcomes were feasibility measures, including rates of referral to and engagement in the WNP. Secondary outcomes were mean weight loss, percentage of patients achieving 5% or more and 10% or more weight loss, referral to WMTs, and number of antiobesity medication prescriptions at 12 months. Of 264 patients, 181 (68.6%) were female and mean (SD) age was 49.5 (13.0) years; there were no significant differences in demographic characteristics between WNP patients (n = 132) and matched controls (n = 132). Of 1159 WNP-eligible patients, 219 (18.9%) were referred to the WNP and 132 (11.4%) completed a visit. In a difference-in-differences analysis, WNP patients lost 4.9 kg more than matched controls (95% CI, 2.11-7.76; P < .001), had 4.4% greater weight loss (95% CI, 2.2%-6.4%; P < .001), and were more likely to achieve 5% or more weight loss (odds ratio [OR], 2.90; 95% CI, 1.54-5.58); average marginal effects, 21.2%; 95% CI, 8.8%-33.6%) and 10% or more weight loss (OR, 7.19; 95% CI, 2.55-25.9; average marginal effects, 17.4%; 95% CI, 8.7%-26.2%). Patients in the WNP group were referred at higher rates to WMTs, including bariatric surgery (18.9% vs 9.1%; P = .02), a low-calorie meal replacement program (16.7% vs 3.8%; P < .001), and a Mediterranean-style diet and activity program (10.6% vs 1.5%; P = .002). There were no between-group differences in antiobesity medication prescribing. The findings of this cohort study suggest that WNP is feasible and associated with greater WMT use and weight loss than matched controls. The WNP warrants evaluation in a large-scale trial.