151 research outputs found

    Experimental Realization of the Quantum Box Problem

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    The three-box problem is a gedankenexperiment designed to elucidate some interesting features of quantum measurement and locality. A particle is prepared in a particular superposition of three boxes, and later found in a different (but nonorthogonal) superposition. It was predicted that appropriate "weak" measurements of particle position in the interval between preparation and post-selection would find the particle in two different places, each with certainty. We verify these predictions in an optical experiment and address the issues of locality and of negative probability.Comment: 5 pages, 4 figure

    Practical measurement of joint weak values and their connection to the annihilation operator

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    Weak measurements are a new tool for characterizing post-selected quantum systems during their evolution. Weak measurement was originally formulated in terms of von Neumann interactions which are practically available for only the simplest single-particle observables. In the present work, we extend and greatly simplify a recent, experimentally feasible, reformulation of weak measurement for multiparticle observables [Resch and Steinberg (2004, Phys. Rev. Lett., 92, 130402)]. We also show that the resulting ``joint weak values'' take on a particularly elegant form when expressed in terms of annihilation operators.Comment: 13 pages, accepted to Physics Letters A (Dec. 2004

    Staff perceptions towards virtual reality-motivated treadmill exercise for care home residents: a qualitative feedback study with key stakeholders and follow-up interview with technology developer

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    Objectives Health and care resources are under increasing pressure, partly due to the ageing population. Physical activity supports healthy ageing, but motivating exercise is challenging. We aimed to explore staff perceptions towards a virtual reality (VR) omnidirectional treadmill (MOTUS), aimed at increasing physical activity for older adult care home residents. Design Interactive workshops and qualitative evaluation. Settings Eight interactive workshops were held at six care homes and two university sites across Cornwall, England, from September to November 2021. Participants Forty-four staff participated, including care home, supported living, clinical care and compliance managers, carers, activity coordinators, occupational therapists and physiotherapists. Interventions Participants tried the VR treadmill system, followed by focus groups exploring device design, potential usefulness or barriers for care home residents. Focus groups were audio-recorded, transcribed verbatim and thematically analysed. We subsequently conducted a follow-up interview with the technology developer (September 2022) to explore the feedback impact. Results The analysis produced seven key themes: anticipated benefits, acceptability, concerns of use, concerns of negative effects, suitability/unsuitability, improvements and current design. Participants were generally positive towards VR to motivate care home residents’ physical activity and noted several potential benefits (increased exercise, stimulation, social interaction and rehabilitation). Despite the reported potential, staff had safety concerns for frail older residents due to their standing position. Participants suggested design improvements to enhance safety, usability and accessibility. Feedback to the designers resulted in the development of a new seated VR treadmill to address concerns about falls while maintaining motivation to exercise. The follow-up developer interview identified significant value in academia–industry collaboration. Conclusion The use of VR-motivated exercise holds the potential to increase exercise, encourage reminiscence and promote meaningful activity for care home residents. Staff concerns resulted in a redesigned seated treadmill for those too frail to use the standing version. This novel study demonstrates the importance of stakeholder feedback in product design

    Microplastics in personal care products: Exploring perceptions of environmentalists, beauticians and students

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    Microplastics enter the environment as a result of larger plastic items breaking down (‘secondary’) and from particles originally manufactured at that size (‘primary’). Personal care productsare an important contributor of secondary microplastics (typically referred to as ‘microbeads’), for example in toothpaste, facial scrubs and soaps. Consumers play an important role in influencing the demand for these products and therefore any associated environmental consequences. Hence we need to understand public perceptions in order to help reduce emissions of microplastics. This study explored awareness of plastic microbeads in personal care products in three groups: environmental activists, trainee beauticians and university students in South West England. Focus groups were run, where participants were shown the quantity of microbeads found in individual high-street personal care products. Qualitative analysis showed that while the environmentalists were originally aware of the issue, it lacked visibility and immediacy for the beauticians and students. Yet when shown the amount of plastic in a range of familiar everyday personal care products, all participants expressed considerable surprise and concern at the quantities and potential impact. Regardless of any perceived level of harm in the environment, the consensus was that their use was unnatural and unnecessary. This research could inform future communications with the public and industry as well as policy initiatives to phase out the use of microbeads

    Intravital imaging technology guides FAK-mediated priming in pancreatic cancer precision medicine according to Merlin status

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    Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic, chemoresistant malignancy and is characterized by a dense, desmoplastic stroma that modulates PDAC progression. Here, we visualized transient manipulation of focal adhesion kinase (FAK), which integrates bidirectional cell-environment signaling, using intravital fluorescence lifetime imaging microscopy of the FAK-based Förster resonance energy transfer biosensor in mouse and patient-derived PDAC models. Parallel real-time quantification of the FUCCI cell cycle reporter guided us to improve PDAC response to standard-of-care chemotherapy at primary and secondary sites. Critically, micropatterned pillar plates and stiffness-tunable matrices were used to pinpoint the contribution of environmental cues to chemosensitization, while fluid flow–induced shear stress assessment, patient-derived matrices, and personalized in vivo models allowed us to deconstruct how FAK inhibition can reduce PDAC spread. Last, stratification of PDAC patient samples via Merlin status revealed a patient subset with poor prognosis that are likely to respond to FAK priming before chemotherapy.Kendelle J. Murphy ... Michael S. Samuel ... et al. [Australian Pancreatic Genome Initiative (APGI), Australian Pancreatic Cancer Matrix Atlas (APMA)

    Human Health Risk Assessment For Arsenic: A Critical Review

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    Millions of people are exposed to arsenic resulting in a range of health implications.This paper provides an up-to-date review of the different sources of arsenic (water, soil and food), indicators of human exposure (biomarker assessment of hair, nail, urine and blood), epidemiological and toxicological studies on carcinogenic and non-carcinogenic health outcomes, and risk assessment approaches. The review demonstrates a need for more work evaluating the risks of different arsenic species such as; arsenate, arsenite monomethylarsonic acid, monomethylarsonous acid, dimethylarsinic acid and dimethylarsinous acid as well as a need to better integrate the different exposure sources in risk assessments

    Determinants of cognitive performance and decline in 20 diverse ethno-regional groups: A COSMIC collaboration cohort study

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    Background: With no effective treatments for cognitive decline or dementia, improving the evidence base for modifiable risk factors is a research priority. This study investigated associations between risk factors and late-life cognitive decline on a global scale, including comparisons between ethno-regional groups. Methods and findings: We harmonized longitudinal data from 20 population-based cohorts from 15 countries over 5 continents, including 48,522 individuals (58.4% women) aged 54–105 (mean = 72.7) years and without dementia at baseline. Studies had 2–15 years of follow-up. The risk factors investigated were age, sex, education, alcohol consumption, anxiety, apolipoprotein E ε4 allele (APOE*4) status, atrial fibrillation, blood pressure and pulse pressure, body mass index, cardiovascular disease, depression, diabetes, self-rated health, high cholesterol, hypertension, peripheral vascular disease, physical activity, smoking, and history of stroke. Associations with risk factors were determined for a global cognitive composite outcome (memory, language, processing speed, and executive functioning tests) and Mini-Mental State Examination score. Individual participant data meta-analyses of multivariable linear mixed model results pooled across cohorts revealed that for at least 1 cognitive outcome, age (B = −0.1, SE = 0.01), APOE*4 carriage (B = −0.31, SE = 0.11), depression (B = −0.11, SE = 0.06), diabetes (B = −0.23, SE = 0.10), current smoking (B = −0.20, SE = 0.08), and history of stroke (B = −0.22, SE = 0.09) were independently associated with poorer cognitive performance (p < 0.05 for all), and higher levels of education (B = 0.12, SE = 0.02) and vigorous physical activity (B = 0.17, SE = 0.06) were associated with better performance (p < 0.01 for both). Age (B = −0.07, SE = 0.01), APOE*4 carriage (B = −0.41, SE = 0.18), and diabetes (B = −0.18, SE = 0.10) were independently associated with faster cognitive decline (p < 0.05 for all). Different effects between Asian people and white people included stronger associations for Asian people between ever smoking and poorer cognition (group by risk factor interaction: B = −0.24, SE = 0.12), and between diabetes and cognitive decline (B = −0.66, SE = 0.27; p < 0.05 for both). Limitations of our study include a loss or distortion of risk factor data with harmonization, and not investigating factors at midlife. Conclusions: These results suggest that education, smoking, physical activity, diabetes, and stroke are all modifiable factors associated with cognitive decline. If these factors are determined to be causal, controlling them could minimize worldwide levels of cognitive decline. However, any global prevention strategy may need to consider ethno-regional differences

    The prevalence of mild cognitive impairment in diverse geographical and ethnocultural regions: The COSMIC Collaboration

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    Background Changes in criteria and differences in populations studied and methodology have produced a wide range of prevalence estimates for mild cognitive impairment (MCI). Methods Uniform criteria were applied to harmonized data from 11 studies from USA, Europe, Asia and Australia, and MCI prevalence estimates determined using three separate definitions of cognitive impairment. Results The published range of MCI prevalence estimates was 5.0%-36.7%. This was reduced with all cognitive impairment definitions: performance in the bottom 6.681% (3.2%-10.8%); Clinical Dementia Rating of 0.5 (1.8%-14.9%); Mini-Mental State Examination score of 24-27 (2.1%-20.7%). Prevalences using the first definition were 5.9% overall, and increased with age (P < .001) but were unaffected by sex or the main races/ethnicities investigated (Whites and Chinese). Not completing high school increased the likelihood of MCI (P = .01). Conclusion Applying uniform criteria to harmonized data greatly reduced the variation in MCI prevalence internationally
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