Quantum-assisted Monte Carlo algorithms for fermions

Quantum computing is a promising way to systematically solve the longstanding computational problem, the ground state of a many-body fermion system. Many efforts have been made to realise certain forms of quantum advantage in this problem, for instance, the development of variational quantum algorithms. A recent work by Huggins et al. reports a novel candidate, i.e. a quantum-classical hybrid Monte Carlo algorithm with a reduced bias in comparison to its fully-classical counterpart. In this paper, we propose a family of scalable quantum-assisted Monte Carlo algorithms where the quantum computer is used at its minimal cost and still can reduce the bias. By incorporating a Bayesian inference approach, we can achieve this quantum-facilitated bias reduction with a much smaller quantum-computing cost than taking empirical mean in amplitude estimation. Besides, we show that the hybrid Monte Carlo framework is a general way to suppress errors in the ground state obtained from classical algorithms. Our work provides a Monte Carlo toolkit for achieving quantum-enhanced calculation of fermion systems on near-term quantum devices

Measurement-efficient quantum Krylov subspace diagonalisation

The Krylov subspace methods, being one category of the most important classical numerical methods for linear algebra problems, their quantum generalisation can be much more powerful. However, quantum Krylov subspace algorithms are prone to errors due to inevitable statistical fluctuations in quantum measurements. To address this problem, we develop a general theoretical framework to analyse the statistical error and measurement cost. Based on the framework, we propose a quantum algorithm to construct the Hamiltonian-power Krylov subspace that can minimise the measurement cost. In our algorithm, the product of power and Gaussian functions of the Hamiltonian is expressed as an integral of the real-time evolution, such that it can be evaluated on a quantum computer. We compare our algorithm with other established quantum Krylov subspace algorithms in solving two prominent examples. It is shown that the measurement number in our algorithm is typically $10^4$ to $10^{12}$ times smaller than other algorithms. Such an improvement can be attributed to the reduced cost of composing projectors onto the ground state. These results show that our algorithm is exceptionally robust to statistical fluctuations and promising for practical applications.Comment: 18 pages, 5 figure

Quantum algorithms for optimal effective theory of many-body systems

A common situation in quantum many-body physics is that the underlying theories are known but too complicated to solve efficiently. In such cases, one usually builds simpler effective theories as low-energy or large-scale alternatives to the original theories. Here the central tasks are finding the optimal effective theories among a large number of candidates and proving their equivalence to the original theories. Recently quantum computing has shown the potential of solving quantum many-body systems by exploiting its inherent parallelism. It is thus an interesting topic to discuss the emergence of effective theories and design efficient tools for finding them based on the results from quantum computing. As the first step towards this direction, in this paper, we propose two approaches that apply quantum computing to find the optimal effective theory of a quantum many-body system given its full Hamiltonian. The first algorithm searches the space of effective Hamiltonians by quantum phase estimation and amplitude amplification. The second algorithm is based on a variational approach that is promising for near-future applications.Comment: 8 pages, 4 figure

Outbreak of OXA-232-producing carbapenem-resistant Klebsiella pneumoniae ST15 in a Chinese teaching hospital: a molecular epidemiological study

Background and AimsThe incidence of OXA-232-producing carbapenem-resistant Klebsiella pneumoniae (CRKP) has been on the rise in China over the past five years, potentially leading to nosocomial epidemics. This study investigates the first outbreak of CRKP in the Second Affiliated Hospital of Jiaxing University.MethodsBetween February 2021 and March 2022, 21 clinical isolates of OXA-232-producing CRKP were recovered from 16 patients in the Second Affiliated Hospital of Jiaxing University. We conducted antimicrobial susceptibility tests, whole genome sequencing, and bioinformatics to determine the drug resistance profile of these clinical isolates.ResultsWhole-genome sequencing revealed that all 21 OXA-232-producing CRKP strains belonged to the sequence type 15 (ST15) and shared similar resistance, virulence genes, and plasmid types, suggesting clonal transmission between the environment and patients. Integrated genomic and epidemiological analysis traced the outbreak to two clonal transmission clusters, cluster 1 and cluster 2, including 14 and 2 patients. It was speculated that the CRKP transmission mainly occurred in the ICU, followed by brain surgery, neurosurgery, and rehabilitation department. Phylogenetic analysis indicated that the earliest outbreak might have started at least a year before the admission of the index patient, and these strains were closely related to those previously isolated from two major adjacent cities, Shanghai and Hangzhou. Comparative genomics showed that the IncFII-type and IncHI1B-type plasmids of cluster 2 had homologous recombination at the insertion sequence sites compared with the same type of plasmids in cluster 1, resulting in the insertion of 4 new drug resistance genes, including TEM-1, APH(6)-Id, APH(3’’)-Ib and sul2.ConclusionsOur study observed the clonal spread of ST15 OXA-232-producing between patients and the hospital environment. The integration of genomic and epidemiological data offers valuable insights and facilitate the control of nosocomial transmission

Molecular engineering tuning optoelectronic properties of thieno[3,2-b]thiophenes-based electrochromic polymers

Thieno[3,2-b]thiophene (TT) monomers end-capped with 3,4-ethylenedioxythiophene (EDOT) moieties are electropolymerized to form pi-conjugated polymers with distinct electrochromic (EC) properties. Steric and electronic factors (electron donor and acceptor substituents) in the side groups of the TT core, as well as the structure of the polymer backbone strongly affect the electrochemical and optical properties of the polymers and their electrochromic characteristics. The studied polymers show low oxidation potentials, tunable from-0.78 to +0.30 V (vs. Fc/Fc(+)) and the band gaps from 1.46 to 1.92 eV and demonstrate wide variety of color palettes in polymer films in different states, finely tunable by structural variations in the polymer backbone and the side chains. EC materials of different colors in their doped/dedoped states have been developed (violet, deep blue, light blue, green, brown, purple-red, pinkish-red, orange-red, light gray, cyan and colorless transparent). High optical contrast (up to 79%), short response time (0.57-0.80 s), good cycling stability (up to 91% at 2000 cycles) and high coloration efficiency (up to 234.6 cm(2) C-1) have been demonstrated and the influence of different factors on the above parameters of EC polymers have been discussed.Shenzhen Key Laboratory of Organic Optoelectromagnetic Functional Materials of Shenzhen Science and Technology Plan [ZDSYS20140509094114164]; Shenzhen Peacock Program [KQTD2014062714543296]; Shenzhen Science and Technology Research Grant [JCYJ20140509093817690]; Nanshan Innovation Agency Grant [KC2015ZDYF0016A]; Guangdong Key Research Project [2014B090914003, 2015B090914002]; Guangdong Talents Project; National Basic Research Program of China [2015CB856505]; National Natural Science Foundation of China [51373075]; Guangdong Academician Workstation [2013B090400016]; Natural Science Foundation of Guangdong Province [2014A030313800]; Santander Universities Research Mobility AwardSCI(E)中国科学引文数据库(CSCD)ARTICLE163-766

Standard-Dose Proton Pump Inhibitors in the Initial Non-eradication Treatment of Duodenal Ulcer: Systematic Review, Network Meta-Analysis, and Cost-Effectiveness Analysis

Background: Short-term use of standard-dose proton pump inhibitors (PPIs) is the first-line initial non-eradication treatment for duodenal ulcer (DU), but the choice on individual PPI drug is still controversial. The purpose of this study is to compare the efficacy, safety, and cost-effectiveness of standard-dose PPI medications in the initial non-eradication treatment of DU.Methods: We searched PubMed, Embase, Cochrane Library, Clinicaltrials.gov, China National Knowledge Infrastructure, VIP database, and the Wanfang database from their earliest records to September 2017. Randomized controlled trials (RCTs) evaluating omeprazole (20 mg/day), pantoprazole (40 mg/day), lansoprazole (30 mg/day), rabeprazole (20 mg/day), ilaprazole (10 mg/day), ranitidine (300 mg/day), famotidine (40 mg/day), or placebo for DU were included. The outcomes were 4-week ulcer healing rate (4-UHR) and the incidence of adverse events (AEs). A network meta-analysis (NMA) using a Bayesian random effects model was conducted, and a cost-effectiveness analysis using a decision tree was performed from the payer’s perspective over 1 year.Results: A total of 62 RCTs involving 10,339 participants (eight interventions) were included. The NMA showed that all the PPIs significantly increased the 4-UHR compared to H2 receptor antagonists (H2RA) and placebo, while there was no significant difference for 4-UHR among PPIs. As to the incidence of AEs, no significant difference was observed among PPIs, H2RA, and placebo during 4-week follow-up. Based on the costs of both PPIs and management of AEs in China, the incremental cost-effectiveness ratio per quality-adjusted life year (in US dollars) for pantoprazole, lansoprazole, rabeprazole, and ilaprazole compared to omeprazole corresponded to $5134.67,$17801.67, $25488.31, and$44572.22, respectively.Conclusion: Although the efficacy and tolerance of different PPIs are similar in the initial non-eradication treatment of DU, pantoprazole (40 mg/day) seems to be the most cost-effective option in China

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

A complex fracture network is generally generated during the hydraulic fracturing treatment in shale gas reservoirs. Numerous efforts have been made to model the flow behavior of such fracture networks. However, it is still challenging to predict the impacts of various gas transport mechanisms on well performance with arbitrary fracture geometry in a computationally efficient manner. We develop a robust and comprehensive model for real gas transport in shales with complex non-planar fracture network. Contributions of gas transport mechanisms and fracture complexity to well productivity and rate transient behavior are systematically analyzed. The major findings are: simple planar fracture can overestimate gas production than non-planar fracture due to less fracture interference. A “hump” that occurs in the transition period and formation linear flow with a slope less than 1/2 can infer the appearance of natural fractures. The sharpness of the “hump” can indicate the complexity and irregularity of the fracture networks. Gas flow mechanisms can extend the transition flow period. The gas desorption could make the “hump” more profound. The Knudsen diffusion and slippage effect play a dominant role in the later production time. Maximizing the fracture complexity through generating large connected networks is an effective way to increase shale gas production

Cross-talk between PRMT1-mediated methylation and ubiquitylation on RBM15 controls RNA splicing

RBM15, an RNA binding protein, determines cell-fate specification of many tissues including blood. We demonstrate that RBM15 is methylated by protein arginine methyltransferase 1 (PRMT1) at residue R578 leading to its degradation via ubiquitylation by an E3 ligase (CNOT4). Overexpression of PRMT1 in acute megakaryocytic leukemia cell lines blocks megakaryocyte terminal differentiation by downregulation of RBM15 protein level. Restoring RBM15 protein level rescues megakaryocyte terminal differentiation blocked by PRMT1 overexpression. At the molecular level, RBM15 binds to pre-mRNA intronic regions of genes important for megakaryopoiesis such as GATA1, RUNX1, TAL1 and c-MPL. Furthermore, preferential binding of RBM15 to specific intronic regions recruits the splicing factor SF3B1 to the same sites for alternative splicing. Therefore, PRMT1 regulates alternative RNA splicing via reducing RBM15 protein concentration. Targeting PRMT1 may be a curative therapy to restore megakaryocyte differentiation for acute megakaryocytic leukemia