2,106 research outputs found

    Application of digital particle image velocimetry to insect aerodynamics: measurement of the leading-edge vortex and near wake of a Hawkmoth.

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    Some insects use leading-edge vortices to generate high lift forces, as has been inferred from qualitative smoke visualisations of the flow around their wings. Here we present the first Digital Particle Image Velocimetry (DPIV) data and quantitative analysis of an insect’s leading-edge vortex and near wake at two flight speeds. This allows us to describe objectively 2D slices through the flow field of a tethered Tobacco Hawkmoth (Manduca sexta). The near-field vortex wake appears to braodly resemble elliptical vortex loops. The presence of a leading-edge vortex towards the end of the downstroke is found to coincide with peak upward force production measured by a six-component force–moment balance. The topology of Manduca’s leading-edge vortex differs from that previously described because late in the downstroke, the structure extends continuously from wingtip across the thorax to the other wingtip

    Feasibility of Using Low-Cost Motion Capture for Automated Screening of Shoulder Motion Limitation after Breast Cancer Surgery

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    Objective To determine if a low-cost, automated motion analysis system using Microsoft Kinect could accurately measure shoulder motion and detect motion impairments in women following breast cancer surgery. Design Descriptive study of motion measured via 2 methods. Setting Academic cancer center oncology clinic. Participants 20 women (mean age = 60 yrs) were assessed for active and passive shoulder motions during a routine post-operative clinic visit (mean = 18 days after surgery) following mastectomy (n = 4) or lumpectomy (n = 16) for breast cancer. Interventions Participants performed 3 repetitions of active and passive shoulder motions on the side of the breast surgery. Arm motion was recorded using motion capture by Kinect for Windows sensor and on video. Goniometric values were determined from video recordings, while motion capture data were transformed to joint angles using 2 methods (body angle and projection angle). Main Outcome Measure Correlation of motion capture with goniometry and detection of motion limitation. Results Active shoulder motion measured with low-cost motion capture agreed well with goniometry (r = 0.70–0.80), while passive shoulder motion measurements did not correlate well. Using motion capture, it was possible to reliably identify participants whose range of shoulder motion was reduced by 40% or more. Conclusions Low-cost, automated motion analysis may be acceptable to screen for moderate to severe motion impairments in active shoulder motion. Automatic detection of motion limitation may allow quick screening to be performed in an oncologist\u27s office and trigger timely referrals for rehabilitation

    The de Morton Mobility Index (DEMMI) provides a valid method for measuring and monitoring the mobility of patients making the transition from hospital to the community: an observational study

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    QuestionIsthe de Morton Mobility Index (DEMMI) valid for measuring the mobility of patients making the transition from hospital to the community?DesignObservational cohort study.Participants696 consecutive patients admitted to 11 Transition Care Programs for multidisciplinary care in Victoria and Tasmania during a 6-month period. The DEMMI and Modified Barthel Index were administered within 5 working days of admission and discharge from the Transition Care Program.Outcome measuresThe DEMMI and Modified Barthel Index.ResultsNeither the DEMMI nor the Modified Barthel Index had a floor or ceiling effect. Similar evidence of convergent, discriminant and known-groups validity were obtained for each instrument. The DEMMI was significantly more responsive to change than the Modified Barthel Index using criterion- and distribution-based methods. The minimum clinically important difference estimates represented similar proportions of the scale width for the DEMMI and Modified Barthel Index and were similar using criterion- and distribution-based estimates. Rasch analysis identified the DEMMI as essentially unidimensional in a Transition Care Program cohort and therefore can be applied to obtain interval level measurement. Rasch analysis demonstrated that the DEMMI was administered similarly by physiotherapists and allied health assistants under the direction of a physiotherapist.ConclusionThe DEMMI and Modified Barthel Index are both valid measures of activity limitation for Transition Care Program patients. The DEMMI has a broader scale width, provides interval level measurement, and is significantly more responsive to change than the Modified Barthel Index for measuring the mobility of Transition Care Program patient

    Optimising Antibiotic Usage to Treat Bacterial Infections

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    The increase in antibiotic resistant bacteria poses a threat to the continued use of antibiotics to treat bacterial infections. The overuse and misuse of antibiotics has been identified as a significant driver in the emergence of resistance. Finding optimal treatment regimens is therefore critical in ensuring the prolonged effectiveness of these antibiotics. This study uses mathematical modelling to analyse the effect traditional treatment regimens have on the dynamics of a bacterial infection. Using a novel approach, a genetic algorithm, the study then identifies improved treatment regimens. Using a single antibiotic the genetic algorithm identifies regimens which minimise the amount of antibiotic used while maximising bacterial eradication. Although exact treatments are highly dependent on parameter values and initial bacterial load, a significant common trend is identified throughout the results. A treatment regimen consisting of a high initial dose followed by an extended tapering of doses is found to optimise the use of antibiotics. This consistently improves the success of eradicating infections, uses less antibiotic than traditional regimens and reduces the time to eradication. The use of genetic algorithms to optimise treatment regimens enables an extensive search of possible regimens, with previous regimens directing the search into regions of better performance

    An Empirical Study of Artifacts and Security Risks in the Pre-trained Model Supply Chain

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    Deep neural networks achieve state-of-the-art performance on many tasks, but require increasingly complex architectures and costly training procedures. Engineers can reduce costs by reusing a pre-trained model (PTM) and fine-tuning it for their own tasks. To facilitate software reuse, engineers collaborate around model hubs, collections of PTMs and datasets organized by problem domain. Although model hubs are now comparable in popularity and size to other software ecosystems, the associated PTM supply chain has not yet been examined from a software engineering perspective. We present an empirical study of artifacts and security features in 8 model hubs. We indicate the potential threat models and show that the existing defenses are insufficient for ensuring the security of PTMs. We compare PTM and traditional supply chains, and propose directions for further measurements and tools to increase the reliability of the PTM supply chain

    An Empirical Study of Pre-Trained Model Reuse in the Hugging Face Deep Learning Model Registry

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    Deep Neural Networks (DNNs) are being adopted as components in software systems. Creating and specializing DNNs from scratch has grown increasingly difficult as state-of-the-art architectures grow more complex. Following the path of traditional software engineering, machine learning engineers have begun to reuse large-scale pre-trained models (PTMs) and fine-tune these models for downstream tasks. Prior works have studied reuse practices for traditional software packages to guide software engineers towards better package maintenance and dependency management. We lack a similar foundation of knowledge to guide behaviors in pre-trained model ecosystems. In this work, we present the first empirical investigation of PTM reuse. We interviewed 12 practitioners from the most popular PTM ecosystem, Hugging Face, to learn the practices and challenges of PTM reuse. From this data, we model the decision-making process for PTM reuse. Based on the identified practices, we describe useful attributes for model reuse, including provenance, reproducibility, and portability. Three challenges for PTM reuse are missing attributes, discrepancies between claimed and actual performance, and model risks. We substantiate these identified challenges with systematic measurements in the Hugging Face ecosystem. Our work informs future directions on optimizing deep learning ecosystems by automated measuring useful attributes and potential attacks, and envision future research on infrastructure and standardization for model registries

    Latent Sensitization in a Mouse Model of Ocular Neuropathic Pain

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    Purpose: Chronic ocular pain is poorly understood and difficult to manage. We developed a murine model of corneal surface injury (CSI)–induced chronic ocular neuropathic pain. The study focuses on changes in corneal nerve morphology and associated short- and long-term pain-like behavior after CSI. Methods: CSI was induced in mice by local application of an alkali solution (0.75 N NaOH). Corneal nerve architecture, morphology, density, and length were studied. Eye-wiping was evaluated before and after CSI in response to hypertonic saline (2 M NaCl). Naltrexone (NTX) or Naloxone-methiodide (NLX-me), opioid receptor antagonists, were given subcutaneously (s.c., 3 mg/kg) or topically (eye drop, 100 μM), and then an eye-wiping test was performed. Results: CSI caused partial corneal deinnervation followed by gradual reinnervation. Regenerated nerves displayed increased tortuosity, beading, and branching. CSI enhanced hypertonic saline-induced eye-wiping behavior compared to baseline or sham-injury (P \u3c 0.01). This hypersensitivity peaked at 10 days and subsided 14 days after CSI. Administration of NTX, or NLX-me, a selective peripheral opioid antagonist, reinstated eye-wiping behavior in the injury group, but not in the sham groups (P \u3c 0.05). Conclusions: This study introduces a model of chronic ocular pain and corneal neuropathy following CSI. CSI induces central and peripheral opioid receptor-dependent latent sensitization (LS) that is unmasked by systemic or topical administration of opioid antagonists. Translational Relevance: This model of chronic ocular pain establishes LS as a new inhibitory mechanism in the oculotrigeminal system and may be used for potential diagnostic and therapeutic interventions for ocular neuropathy

    Additional weekend therapy may reduce length of rehabilitation stay after stroke: a meta-analysis of individual patient data

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    Questions: Among people receiving inpatient rehabilitation after stroke, does additional weekend physiotherapy and/or occupational therapy reduce the length of rehabilitation hospital stay compared to those who receive a weekday-only service, and does this change after controlling for individual factors? Does additional weekend therapy improve the ability to walk and perform activities of daily living, measured at discharge? Does additional weekend therapy improve health-related quality of life, measured 6 months after discharge from rehabilitation? Which individual, clinical and hospital characteristics are associated with shorter length of rehabilitation hospital stay? Design: This study pooled individual data from two randomised, controlled trials (n = 350) using an individual patient data meta-analysis and multivariate regression. Participants: People with stroke admitted to inpatient rehabilitation facilities. Intervention: Additional weekend therapy (physiotherapy and/or occupational therapy) compared to usual care (5 days/week therapy). Outcome measures: Length of rehabilitation hospital stay, independence in activities of daily living measured with the Functional Independence Measure, walking speed and health-related quality of life. Results: Participants who received weekend therapy had a shorter length of rehabilitation hospital stay. In the un-adjusted analysis, this was not statistically significant (MD -5.7 days, 95% CI -13.0 to 1.5). Controlling for hospital site, age, walking speed and Functional Independence Measure score on admission, receiving weekend therapy was significantly associated with a shorter length of rehabilitation hospital stay (beta = 7.5, 95% CI 1.7 to 13.4, p = 0.001). There were no significant between-group differences in Functional Independence Measure scores (MD 1.9 points, 95% CI -2.8 to 6.6), walking speed (MD 0.06 m/second, 95% CI -0.15 to 0.04) or health-related quality of life (SMD -0.04, 95% CI -0.26 to 0.19) at discharge. Discussion: Modest evidence indicates that additional weekend therapy might reduce rehabilitation hospital length of stay
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