Publications by authors named "Walters P"

Many physical and chemical processes in a condensed phase environment exhibit non-Markovian quantum dynamics. As such simulations are challenging on classical computers, we developed a variational quantum algorithm that is capable of simulating non-Markovian dynamics on noisy intermediate-scale quantum (NISQ) devices. We used a quantum system linearly coupled to its harmonic bath as the model Hamiltonian.

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The theory of open quantum systems has many applications ranging from simulating quantum dynamics in condensed phases to better understanding quantum-enabled technologies. At the center of theoretical chemistry are the developments of methodologies and computational tools for simulating charge and excitation energy transfer in solutions, biomolecules, and molecular aggregates. As a variety of these processes display non-Markovian behavior, classical computer simulation can be challenging due to exponential scaling with existing methods.

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Aircraft are manufactured according to design parameters that must account for the size and physical characteristics of the pilot. While cockpit dimensions, seats, restraints, and related components do not change substantially over the airframe lifecycle, it is conceivable that the occupant may, even if initially well-suited. This investigation focused on longitudinal body mass index (BMI) changes within a cohort of British Army Air Corps pilots.

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The dynamics of the excitation energy transfer (EET) in photosynthetic complexes is an interesting question both from the perspective of fundamental understanding and the research in artificial photosynthesis. Over the past decade, very accurate spectral densities have been developed to capture spatial inhomogeneities in the Fenna-Matthews-Olson (FMO) complex. However, challenges persist in numerically simulating these systems, both in terms of parameterizing them and following their dynamics over long periods of time because of long non-Markovian memories.

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Understanding the pathways taken by a quantum particle during a transport process is an enormous challenge. There are broadly two different aspects of the problem that affect the route taken. First is obviously the couplings between the various sites, which translates into the intrinsic "strength" of a state-to-state channel.

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Background: The Single Ventricle Reconstruction (SVR) Trial was the first randomized clinical trial of a surgical approach for treatment of congenital heart disease. Infants with hypoplastic left heart syndrome (HLHS) and other single right ventricle (RV) anomalies were randomized to a modified Blalock Taussig Thomas shunt (mBTTS) or a right-ventricular-to-pulmonary-artery shunt (RVPAS) at the time of the Norwood procedure. The aim of the Long-term Outcomes of Children with HLHS and the Impact of Norwood Shunt Type (SVR III) study is to compare early adolescent outcomes including measures of cardiac function, transplant-free survival, and neurodevelopment, between those who received a mBTTS and those who received an RVPAS.

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The recently introduced multisite tensor network path integral (MS-TNPI) method [Bose and Walters, , 2022, , 24101] for simulating quantum dynamics of extended systems has been shown to be effective in studying one-dimensional systems coupled with local baths. Quantum transport in these systems is typically studied at a constant temperature. However, temperature seems to be a very obvious parameter that can be spatially changed to control this transport.

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The recently introduced multisite tensor network path integral (MS-TNPI) allows simulation of extended quantum systems coupled to dissipative media. We use MS-TNPI to simulate the exciton transport and the absorption spectrum of a B850 bacteriochlorophyll (BChl) ring. The MS-TNPI network is extended to account for the ring topology of the B850 system.

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Objectives: To identify, describe and critically appraise the quality of studies of interventions developed to reduce the rate of secondary care utilisation and investigate interventions' impact on patients with type 2 diabetes mellitus (T2DM).

Method: Using a systematic approach, five databases were searched between 01 January 1995 and 01 February 2021 (MEDLINE, EMBASE, PsycINFO, CINAHL and Cochrane database). Inclusion criteria were studies (published in English) in adults with T2DM offered intervention(s) involving medicines/services/educational programmes in any country or setting, with investigated outcomes including the rate of hospital admission/re-admission/accident and emergency visits.

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Tensor network decompositions of path integrals for simulating open quantum systems have recently been proven to be useful. However, these methods scale exponentially with the system size. This makes it challenging to simulate the non-equilibrium dynamics of extended quantum systems coupled with local dissipative environments.

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We report on the genomic characterization of three novel classes in the phylum Desulfobacterota. One class (proposed name Candidatus 'Anaeroferrophillalia') was characterized by heterotrophic growth capacity, either fermentatively or utilizing polysulfide, tetrathionate or thiosulfate as electron acceptors. In the absence of organic carbon sources, autotrophic growth via the Wood-Ljungdahl (WL) pathway and using hydrogen or Fe(II) as an electron donor is also inferred for members of the 'Anaeroferrophillalia'.

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Objectives: To investigate the perception and experience of patients and the public (PP) about community pharmacy (CP) services and other primary care services after hospital discharge back home.

Design And Setting: A rapid review and qualitative study exploring PP perceptions of primary care, focusing on CP services in the UK.

Methods: A mixed-methods approach was adopted including a rapid review undertaken between 24 April and 8 May 2019 across four databases (MEDLINE, EMBASE, PsycINFO and CINAHL).

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Purpose: Electronic medical case files of male prisoners in a category B prison in London were studied to establish a prevalence during an eight-month period of the use of and the reasons for prescribing gabapentinoids in prison and also to establish prescribing standards in prison and compliance with these. In addition, the prevalence of co-prescription of gabapentinoids with opioids and antidepressants, particularly tricyclic antidepressants such as amitriptyline, was also assessed in light of the increased risk of respiratory depression resulting in death when these drugs are used in combination. The paper aims to discuss these issues.

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Accurate measurement of clonal genotypes, mutational processes, and replication states from individual tumor-cell genomes will facilitate improved understanding of tumor evolution. We have developed DLP+, a scalable single-cell whole-genome sequencing platform implemented using commodity instruments, image-based object recognition, and open source computational methods. Using DLP+, we have generated a resource of 51,926 single-cell genomes and matched cell images from diverse cell types including cell lines, xenografts, and diagnostic samples with limited material.

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Single-cell RNA sequencing has enabled the decomposition of complex tissues into functionally distinct cell types. Often, investigators wish to assign cells to cell types through unsupervised clustering followed by manual annotation or via 'mapping' to existing data. However, manual interpretation scales poorly to large datasets, mapping approaches require purified or pre-annotated data and both are prone to batch effects.

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Measuring gene expression of tumor clones at single-cell resolution links functional consequences to somatic alterations. Without scalable methods to simultaneously assay DNA and RNA from the same single cell, parallel single-cell DNA and RNA measurements from independent cell populations must be mapped for genome-transcriptome association. We present clonealign, which assigns gene expression states to cancer clones using single-cell RNA and DNA sequencing independently sampled from a heterogeneous population.

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Myofibroblasts play key roles in wound healing and pathological fibrosis. Here, we used an RNAi screen to characterize myofibroblast regulatory genes, using a high-content imaging approach to quantify α-smooth muscle actin stress fibers in cultured human fibroblasts. Screen hits were validated on physiological compliance hydrogels, and selected hits tested in primary fibroblasts from patients with idiopathic pulmonary fibrosis.

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Objectives: To identify and evaluate interventions aimed at increasing uptake of, or access to, physical health screening by adults with severe mental illness; to examine why interventions might work.

Design: Realist review.

Setting: Primary, secondary and tertiary care.

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Thermoregulation is critical for athletes, particularly those for those who must perform in the heat. Most strategies aimed at reducing heat stress have cooled participants before or during activity. The objective of this study is to investigate whether seven minutes of head cooling applied between bouts of aerobic exercise in hot (35 ± 1.

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We present a direct procedure for determining the parameters of a discrete harmonic bath modeling the influence of a complex condensed phase environment on the system of interest. The procedure employs an efficient discretization of the spectral density into modes that correspond to equal fractions of the reorganization energy. The new procedure uses directly the classical correlation function (available from molecular dynamics calculations) as input, avoiding numerical computation of the spectral density by means of a discrete Fourier transform.

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Background: Adults with severe mental illness (i.e. schizophrenia or other related psychotic disorders and bipolar disorder) can be at greater risk of cancer than those without severe mental illness (SMI).

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Influence functional methods provide a powerful approach for simulating the dynamics of a system embedded in a harmonic bath, which may be parametrized to reflect a variety of environments and chemical processes. In this work, we develop a procedure for calculating the coefficients of the discretized influence functional using the classical approximation to the time correlation function, which is usually available through molecular dynamics simulations. This procedure circumvents the calculation of a spectral density via Fourier inversion of the correlation function.

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Background: Cancers are a leading cause of death worldwide. People with mental illness are 30 % more likely to die from cancer than the general population. One reason for this may be low uptake of nationally offered cancer screening tests by people with mental illness.

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