Publications by authors named "Snowdon C"

Second-order Møller-Plesset perturbation theory (MP2) using the Resolution of the Identity approximation (RI-MP2) is a widely used method for computing molecular energies beyond the Hartree-Fock mean-field approximation. However, its high computational cost and lack of efficient algorithms for modern supercomputing architectures limit its applicability to large molecules. In this paper, we present the first distributed-memory many-GPU RI-MP2 algorithm explicitly designed to utilize hundreds of GPU accelerators for every step of the computation.

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Background: Sharing trial results with participants is a moral imperative, but too often does not happen in appropriate ways.

Methods: We carried out semi-structured interviews with patients (n = 13) and site staff (n = 11), and surveyed 180 patients and 68 site staff who were part of the Show RESPECT study, which tested approaches to sharing results with participants in the context of the ICON8 ovarian cancer trial (ISRCTN10356387). Qualitative and free-text data were analysed thematically, and findings used to develop the SHOW RESPECT adaptable framework of considerations for planning how to share trial results with participants.

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Objectives: This study aimed to understand the role of surgical Trainee Research Collaboratives (TRCs) in conducting randomised controlled trials and identify strategies to enhance trainee engagement in trials.

Design: This is a mixed methods study. We used observation of TRC meetings, semi-structured interviews and an online survey to explore trainees' motivations for engagement in trials and TRCs, including barriers and facilitators.

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Background/aims: Sharing trial results with participants is an ethical imperative but often does not happen. Show RESPECT (ISRCTN96189403) tested ways of sharing results with participants in an ovarian cancer trial (ISRCTN10356387). Sharing results via a printed summary improved patient satisfaction.

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Electronic structure calculations have the potential to predict key matter transformations for applications of strategic technological importance, from drug discovery to material science and catalysis. However, a predictive physicochemical characterization of these processes often requires accurate quantum chemical modeling of complex molecular systems with hundreds to thousands of atoms. Due to the computationally demanding nature of electronic structure calculations and the complexity of modern high-performance computing hardware, quantum chemistry software has historically failed to operate at such large molecular scales with accuracy and speed that are useful in practice.

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Background: The COVID-19 pandemic brought rapid and major changes to research, and those wishing to carry out Patient and Public Involvement (PPI) activities faced challenges, such as restrictions on movement and contact, illness, bereavement and risks to potential participants. Some researchers moved PPI to online settings during this time but remote consultations raise, as well as address, a number of challenges. It is important to learn from PPI undertaken in this period as face-to-face consultation may no longer be the dominant method for PPI.

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The luteal-placental shift is an important milestone of mammalian pregnancy signifying when endocrine control of pregnancy shifts from the corpus luteum of the ovary to the placenta. The corpus luteum is maintained by chorionic gonadotropin (CG). Upon sufficient placental maturation, CG production wanes, the corpus luteum involutes, and control is shifted to the placenta, one consequence of which is a midgestational rise in glucocorticoid production, especially cortisol and cortisone, by both mother and fetus.

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Article Synopsis
  • The c-TRAK TN trial investigated the use of circulating tumor DNA (ctDNA) surveillance as a method to predict relapse in early-stage triple-negative breast cancer (TNBC) patients after treatment.
  • The trial enrolled patients with residual disease post-chemotherapy and involved blood tests every three months for a year to monitor ctDNA levels, with ctDNA+ patients receiving pembrolizumab if indications of recurrence were found.
  • Out of 161 patients monitored, 27.3% tested positive for ctDNA within 12 months, but only five were treated with pembrolizumab, and none showed a complete response, highlighting challenges in effectively using ctDNA monitoring for treatment decisions.
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Direct care of offspring by the father (sire) is relatively rare in primates. Besides humans, there are a number of species where the male is essential for the survival of offspring: marmosets, tamarins, titis and owl monkeys, some lemurs, and siamangs. All these species show reduced sexual dimorphism, territoriality, and biparental care.

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  • Late-phase platform protocols, such as basket and master protocols, are more efficient than traditional two-arm trials but are underutilized; this study shares operational recommendations from successful implementations.* -
  • A meeting of UK clinical trial experts was held to discuss the practical challenges and operational aspects specific to running late-phase platform trials, leading to a set of guidance for trialists.* -
  • The recommendations cover all stages of a platform trial, emphasizing key areas like protocol development, funding, staffing, data management, and effective communication with participants and stakeholders.*
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Adaptive designs are a class of methods for improving efficiency and patient benefit of clinical trials. Although their use has increased in recent years, research suggests they are not used in many situations where they have potential to bring benefit. One barrier to their more widespread use is a lack of understanding about how the choice to use an adaptive design, rather than a traditional design, affects resources (staff and non-staff) required to set-up, conduct and report a trial.

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To examine how precipitation patterns and climate change impact feeding choices made by a population of critically endangered cotton-top tamarins (Saguinus oedipus), we examined 22 years of feeding data (1999-2020) from 21 groups collected at Parque Natural Regional Bosque Seco El Ceibal Mono Tití in Santa Catalina, Colombia. We describe the diet and examine the role of seasonal rainfall and annual variation in rainfall on diet. Rainfall is highly seasonal (mean annual rainfall 1562 mm [range 940-2680 mm]) with a dry, early rainy, and late rainy season in each year.

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Article Synopsis
  • Platform trials are used in cancer research to test different treatments at the same time, making the process faster and more efficient.
  • The UK plasmaMATCH trial, which focused on advanced breast cancer, completed its main results within just 3 years by overcoming several challenges during its development.
  • Success in such trials relies on strong teamwork, clear planning, and good funding, ensuring everyone involved works well together.
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Objective: The success of pharmacological randomised controlled trials (RCTs) depends on the recruitment of the required number of participants. Recruitment to RCTs for patients with cirrhosis and small oesophageal varices raises specific additional challenges. The objectives of the study were 1) to explore patient perspectives on factors that influence RCT recruitment, 2) to understand factors that influence the success of recruitment from a staff perspective, and 3) to identify opportunities for tailored interventions to improve trial recruitment in this context.

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In a retrospective study of a western pygmy marmoset () colony, postmortem examination of 1/8 juvenile and 29/47 adult animals identified vascular, cardiac, and renal lesions consistent with systemic hypertension. This included frequent renal arteriolar hypertrophy, hyaline and proliferative arteriolosclerosis, fibrinoid necrosis of arterioles, glomerulosclerosis, and nephrosclerosis. Affected animals ranged from 0.

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Background: Adaptive designs offer great promise in improving the efficiency and patient-benefit of clinical trials. An important barrier to further increased use is a lack of understanding about which additional resources are required to conduct a high-quality adaptive clinical trial, compared to a traditional fixed design. The Costing Adaptive Trials (CAT) project investigated which additional resources may be required to support adaptive trials.

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Background: Sharing trial results with participants is an ethical imperative but often does not happen. We tested an Enhanced Webpage versus a Basic Webpage, Mailed Printed Summary versus no Mailed Printed Summary, and Email List Invitation versus no Email List Invitation to see which approach resulted in the highest patient satisfaction with how the results were communicated.

Methods And Findings: We carried out a cluster randomised, 2 by 2 by 2 factorial, nonblinded study within a trial, with semistructured qualitative interviews with some patients (ISRCTN96189403).

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Playing music or natural sounds to animals in human care is thought to have beneficial effects. An analysis of published papers on the use of human-based music with animals demonstrates a variety of different results even within the same species. These mixed results suggest the value of tailoring music to the sensory systems of the species involved and in selecting musical structures that are likely to produce the desired effects.

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Background: Healthcare workers (HCWs) are believed to be at increased risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. It is not known to what extent the natural production of antibodies to SARS-CoV-2 is protective against re-infection.

Methods: A prospective observational study of HCWs in Scotland (UK) from May to September 2020 was performed.

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Studies of cooperative breeding species have suggested that helpers are needed for infant survival and that helpers gain skills to successfully raise their own offspring. Studies of callitrichids in managed care and early field studies suggested that group size correlated with infant survival and that helpers needed to learn parental skills to be successful breeders. We present infant survival data from a 20-year field study of cotton-top tamarins (Saguinus oedipus) in Colombia involving 126 litters born to 41 females.

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Unlabelled: Patient and Public Involvement (PPI) describes the active involvement of patients and the public in the research process. Through PPI, patients and members of the public are increasingly involved in the design and conduct of clinical trials. PPI has been shown to improve the quality and relevance of research.

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The , the oldest continuously published journal on animal behavior, has reached its centennial year. I examined each article published in the Journal over the past 100 years to document the changing roles of women and of international authors over the past century. The analysis also documented changes in the range of species and topics studied over the Journal's history.

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Article Synopsis
  • The study investigates the effectiveness of ctDNA testing in advanced breast cancer, aimed at avoiding repeat biopsies and helping to select patients for targeted therapies based on their genetic mutations.
  • Conducted across 18 UK hospitals, it involved women with advanced breast cancer who had undergone prior treatments, and assessed responses to various mutation-specific treatments aligned with their ctDNA profiles.
  • The trial is ongoing, with recruitment completed and primary endpoints focused on measuring response rates, and is registered under several clinical trial databases.
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In nearly four decades our research and that of others on chemical signaling in callitrichid primates suggest a high degree of contextual complexity in both the use of signals and the response to these signals. We describe our research including observational field studies, behavioral bioassays ("playbacks"), functional imaging, and conditioning studies. Scent marking in both captivity and the wild is used for more than just territorial marking.

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