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Designing a Magnetic Endoscope for In Vivo Contact-Based Tissue Scanning Using Developable Roller
Get PDFMagnetic manipulation has been adopted as a method of actuation in both wireless capsule endoscopy and soft-tethered endoscopy, with the goal of improving gastrointestinal procedures. However, by nature of magnetic manipulation, these endoscopes are typically limited to a maximum of five degrees of freedom (DoF). With the need to introduce additional contact-based sensing modalities for subsurface investigation into these systems as well as to improve overall dexterity, it is both practically and clinically beneficial to recover the lost DoF i.e. the roll around the main axis. This paper presents a method of achieving the magnetic manipulation of an underactuated device by leveraging developable surfaces, specifically, the oloid shape. The design of a clinically relevant magnetic endoscope with all its ancillary elements, as well as contact sensors, is proposed and demonstrated in vivo. The contact sensor data from the in vivo experiments show that for sweeping motions over 100° of roll, contact between the endoscope’s sensor region and the colon wall can be maintained for 74% of the motion
Predictors of independence in older people: A longitudinal, population-based study using the CARE75 + cohort
Get PDFBackground
The ability to predict older people’s functional independence has implications for the development and provision of services to improve individual sense of self and wellbeing.
Methods
Using linear regression analyses we identified predictors of independence, measured using the Nottingham Extended Activities of Daily Living (NEADL) scale, at 12 and 24-months from baseline. Data were obtained from 1277 community-dwelling people aged ≥ 75. Multivariable models included predictors that were selected through review of existing literature, perspectives of older people, and univariable analyses. Multiple imputation was used to account for missing data.
Results
Participants’ mean age was 84.61 years (SD 4.95) and just over half were female (n = 655, 51.29%). At baseline, participants had a mean NEADL score of 53.82 (SD 13.19). Younger age, fewer hours of informal help received, no registered visual impairment, lower frailty, living alone, higher cognitive function, greater physical function, absence of depression, and higher baseline NEADL were significant predictors of greater independence at 12-months. Younger age, higher baseline NEADL score, living alone, less frailty, higher cognitive function, alcohol consumption, greater physical function, and absence of depression predicted greater independence at 24-months.
Conclusion
Depression and frailty are important predictors of an older person’s independence with other variables such as activities of daily living, age, cognitive function, alcohol consumption, and living status also having an impact over a prolonged period. Refining understanding of the mechanisms within frailty and depression is likely to improve targeting of support and interventions, which will have a lasting impact on older people’s independence
Smooth linear-parameter-varying identification of gas turbine engine models: a polynomial approach
Get PDFInterpretability and explainability are at the core of applications developed for control of safety-critical systems, requiring low-complexity models, with physically meaningful insights, and maximum prediction accuracy. This can lead to two very distinct representations of non-linear systems: models purely based on first-principles, highly explainable but extremely difficult to use in practice, or data-intensive, with almost no interpretability but tailored to each specific application. To harness the advantages of both approaches, this paper introduces a novel polynomial linear-parameter-varying framework with stability guarantees to model gas turbine engines, with interpretable dynamical states. The identification problem is split into three stages: (i) identification of the scheduling variable mapping via least squares; (ii) identification of the state dynamics via constrained least squares optimisation involving linear matrix inequalities; (iii) identification of the output equation via least squares. The modelling framework inherits interpretability through the selection of physical variables as dynamical states, while model smoothness is enforced by the use of polynomial functions, which are amenable for control design and optimisation. A unique model for the gas turbine engine is obtained at sea level static, and then extended to wider operating conditions through transformations to referred variables. The effectiveness of the modelling framework is demonstrated on two scenarios, using an engine from the literature, in which low prediction errors were observed, including avoidance of instabilities. Potential applications range from digital-twins and Monte-Carlo simulations, to gain-scheduled and model predictive control, or even economic optimisation, among others
Crystal-mush remobilization timescales and magma storage depth in the Snæfellsnes Volcanic Zone (W-Iceland): insights from olivine Fe-Mg diffusion chronometry and fluid inclusion barometry
Get PDFConstraining the conditions and timescales of magma storage, mixing, and transfer—and understanding how deep-seated unrest progresses towards eruption—is key to deciphering early stages of magma system reactivation. While these processes are increasingly well-resolved in Iceland’s on-rift zones, magma dynamics in off-rift flank zones remain poorly understood, despite their potential for hazardous explosive eruptions after long periods of dormancy. We investigate magma storage depths and pre-eruptive timescales of magma mobilization and crystal-mush erosion in the Snæfellsnes Volcanic Zone (SNVZ), a relict Tertiary volcanic belt hosting the most extensive off-rift volcanism in Iceland. Integrating olivine Fe-Mg diffusion chronometry with fluid inclusion and clinopyroxene barometry, we reconstruct storage conditions preceding the Holocene Búðahraun and Berserkjahraun eruptions. Our results identify a key magma storage zone at ~ 11–15 km depth. The absence of fluid inclusions recording shallow magma storage suggests rapid olivine entrainment and swift magma ascent from mid-crustal depths to the surface. These storage depths broadly align with deep (15–20 km, median depth: 17 km) seismicity detected in the SNVZ since August 2024, consistent with potential reactivation of a mid-crustal magma domain by ongoing mantle-derived melt intrusions. Olivine diffusion chronometry indicates mush erosion began ~ 4.9 and ~ 1.8 years before the Búðahraun and Berserkjahraun eruptions, respectively, with final mobilization occurring within ~ 1.5 months. Re-modelling reversely zoned olivines with a Combined Diffusion-and-Growth (CDG) model shortens timescale estimates by ~ 60% compared to isothermal approaches, yielding refined durations of 7 days to 1.8 years (median ~ 22.5 days). Across the full dataset, however, median timescales cluster at 39–47 days. These records are broadly comparable to those in on-rift systems, suggesting off-rift and on-rift volcanoes may mobilize magma in more similar ways than previously thought. Given ongoing seismicity in the SNVZ, our findings highlight the need for enhanced monitoring and provide a framework for comparing magma dynamics in on- and off-rift settings, improving hazard assessment for systems without historical eruption records
Life cycle assessment of power generation with CCS and low-emission natural gas production: how close to zero can the carbon footprint be?
No full textNatural gas (NG) is expected to provide a substantial portion of electricity generation in many jurisdictions for the foreseeable future. Post-combustion carbon capture and storage (CCS) effectively abates direct CO2 emissions; however, indirect NG supply chain emissions in most jurisdictions are incompatible with climate change mitigation goals. This life cycle assessment evaluates specific opportunities to reduce the carbon footprint of combined cycle gas turbine (CCGT) generation with CCS using existing low-emission NG production practices, technologies, and processes combined with emerging CCS techniques to achieve high CO2 capture rates and mitigate startup emissions. We find baseload life cycle greenhouse gas (GHG) emission intensity ranges from 22-62 kgCO2e/MWh for 95-98.5% CO2 capture – within the range of published estimates for wind and photovoltaic power and considerably below prior estimates of CCGT with CCS. We also show how interim solvent storage can effectively mitigate emissions from CCGT start/stop cycles. This work highlights the importance of mitigating both CO2 and methane emissions from NG supply chains and proposes a more nuanced discussion regarding the potential contribution of NG to future energy supply
Impact and cost-effectiveness of the community-led AMETHIST intervention among female sex workers in Zimbabwe
Get PDFFemale sex workers (FSW) face high HIV risk of HIV transmission and acquisition. The AMETHIST ("Adapted Microplanning: Eliminating Transmissible HIV In Sex Transactions") trial enhanced Zimbabwe's Key Populations (KP) programme by providing targeted, community-based support for FSW. We used the HIV Synthesis Model to assess its long-term impact and cost-effectiveness. Given USAID's major role in funding, we also evaluated the effects of ending US support on the KP programme. We modelled a KP programme from 2010. From 2024 we compared (i) continuation of KP programme to (ii) continuation of KP programme + 'AMETHIST' intervention. We assessed HIV outcomes in 2030 and conducted cost-effectiveness analysis over a 50 year time horizon. Similar analyses were undertaken comparing continuation of the current KP programme to discontinuation. Here we show that AMETHIST had greater positive impact than the KP programme alone; a higher proportion of FSW tested for HIV in the past year, were diagnosed, on ART and had undetectable viral loads compared to the KP programme alone. Disability adjusted life years were averted with AMETHIST and it was cost-saving within 15 years. Continuing the current KP programme was also cost-saving compared to discontinuation of the KP programme
High-energy photon generation from self-organized plasma cavities in field-enhanced laser-preplasma interactions
Get PDFThe interaction of an ultraintense Nd:glass laser pulse with a near-critical plasma self-organizes into a highly efficient γ-ray source. Three-dimensional particle-in-cell simulations demonstrate that relativistic self-focusing, aided by a self-generated electron cavity, enhances the laser intensity by more than an order of magnitude, driving the system into the radiation-reaction-dominated regime, i.e., one where the electrons lose a substantial amount of their energy as hard radiation. Peak photon emission occurs near 0.5 times the relativistic critical density, with a γ-photon yield exceeding 20% of the laser energy. Compared to Ti:Sa lasers of the same power, the longer duration of Nd:glass laser pulses leads to an order of magnitude increase in γ-photon number in the extreme conversion efficiency regime, making them particularly well suited for photonuclear physics applications. These findings point to a robust and scalable mechanism for compact, ultrabright γ-ray generation in the multipetawatt regime
Faux paw: Capnocytophaga canimorsus endocarditis following a dog lick: A case report
No full textCapnocytophaga canimorsus (C. canimorsus) is a fastidious Gram-negative bacterium found in the mouths of dogs and cats. It is a rare cause of infective endocarditis, when it is often associated with dog bites. We present a case of C. canimorsus infective endocarditis complicated by aortic regurgitation and root abscess, in a patient with a history of previous infective endocarditis. The patient underwent re-do aortic valve surgery with aortic valve replacement. Blood cultures and 16S ribosomal ribonucleic acid gene amplification and sequencing from the excised valve tissue confirmed C. canimorsus as the cause. The patient was treated with beta-lactam antibiotics and discharged home. Rather than secondary to a dog bite, infection most likely occurred due to a dog licking an open wound. It is important to remember that dog contact, often perceived as innocuous, such as being licked, can be a source of serious infection particularly in the context of an open wound. Over a third of households in the United Kingdom own a dog as a pet. With C. canimorsus infections thought to be on the rise, in part due to increased pet ownership, there is a need to ensure pet owners, particularly those at risk of infections and chronic skin wounds are educated on such risks, and the appropriate preventative steps
Logical convergence laws via stochastic approximation and Markov processes
Get PDFSince the paper of Kleinberg and Kleinberg, SODA’05, where it was proven that the preferential attachment random graph with degeneracy at least 3 does not obey the first order 0-1 law, no general methods were developed to study logical limit laws for recursive random graph models with arbitrary degeneracy. Even in the (possibly) simplest case of the uniform attachment, it is still not known whether the first order convergence law holds in this model. We prove that the uniform attachment random graph with bounded degrees obeys the first order convergence law. To prove the law, we describe dynamics of first order equivalence classes of the random graph using Markov chains. The convergence law follows from the existence of a limit distribution of the considered Markov chain. To show the latter convergence, we use stochastic approximations
Adaptive affordance design for social robots: tailoring to role-specific preferences
Get PDFAs social robots become integral to diverse interaction scenarios, their design must effectively engage users emotionally while accurately conveying their functional capabilities through coherent design. While previous research in adaptive human-robot interaction has predominantly focused on enabling robots to learn and adapt to users' dynamic behavior, less attention has been paid to robots' affordances. This study addresses this gap by investigating how users' preferences for a social robot's affordances, such as look and voice, vary across different social roles and scenarios. Using the Stereotype Content Model's dimensions of warmth and competence, we conducted a quantitative survey with Likert-scale measures to assess preferences for affordance designs in general and context-dependent use cases. Our results show a medium to low preference for humanlike affordances when the robot's intended use is unspecified. While human likeness positively correlates with perceived warmth and competence, these social perceptions do not significantly drive preferences for humanlike features. Instead, preferences are primarily influenced by robots' intended situational roles, which differ from the stereotypical occupational roles in human society. These results highlight the importance of context-specific adaptive affordance design, which should focus on aligning robot characteristics with contextual expectations of social attributes
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