98 research outputs found

    Pollination ecology and circadian patterns of inflorescence opening of the Madagascan climber Dalechampia aff. bernieri (Euphorbiaceae)

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    Floral morphology often directly influences interactions with pollinators, but less is known about the role of extrafloral structures. We studied the relationship between bract motility, floral structural specialization and pollination in Dalechampia aff. bernieri, an endemic Madagascan species with floral structures indicating specialized buzz-pollination.Wemeasured circadian bract angles in 47 inflorescences from 11 plants of D. aff. bernieri; in addition, we recorded any flower-visiting insects observed. The inflorescences hadmotile bracts with mean angles varying from about 50° at 00h00 to about 90° at 10h45. They were visited by buzz-pollinating Nomia viridilimbata bees (Halictidae), but also by non-buzz-pollinating Liotrigona bees (Apidae). The temporal pattern of bractmotility observed in D. aff. bernieri may represent an extra-floral specialization to reduce visitation by non-pollinating visitors while maximizing visitation by diurnal buzz-pollinating bees

    Going one step further: towards cognitively enhanced problem-solving teaming agents

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    Operating current advanced production systems, including Cyber-Physical Systems, often requires profound programming skills and configuration knowledge, creating a disconnect between human cognition and system operations. To address this, we suggest developing cognitive algorithms that can simulate and anticipate teaming partners' cognitive processes, enhancing and smoothing collaboration in problem-solving processes. Our proposed solution entails creating a cognitive system that minimizes human cognitive load and stress by developing models reflecting humans individual problem-solving capabilities and potential cognitive states. Further, we aim to devise algorithms that simulate individual decision processes and virtual bargaining procedures that anticipate actions, adjusting the system’s behavior towards efficient goal-oriented outcomes. Future steps include the development of benchmark sets tailored for specific use cases and human-system interactions. We plan to refine and test algorithms for detecting and inferring cognitive states of human partners. This process requires incorporating theoretical approaches and adapting existing algorithms to simulate and predict human cognitive processes of problem-solving with regards to cognitive states. The objective is to develop cognitive and computational models that enable production systems to become equal team members alongside humans in diverse scenarios, paving the way for more efficient, effective goal-oriented solutions

    Convolutional neuronal networks combined with X-ray phase-contrast imaging for a fast and observer-independent discrimination of cartilage and liver diseases stages

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    We applied transfer learning using Convolutional Neuronal Networks to high resolution X-ray phase contrast computed tomography datasets and tested the potential of the systems to accurately classify Computed Tomography images of different stages of two diseases, i.e. osteoarthritis and liver fibrosis. The purpose is to identify a time-effective and observer-independent methodology to identify pathological conditions. Propagation-based X-ray phase contrast imaging WAS used with polychromatic X-rays to obtain a 3D visualization of 4 human cartilage plugs and 6 rat liver samples with a voxel size of 0.7x0.7x0.7 mu m(3) and 2.2x2.2x2.2 mu m(3), respectively. Images with a size of 224x224 pixels are used to train three pre-trained convolutional neuronal networks for data classification, which are the VGG16, the Inception V3, and the Xception networks. We evaluated the performance of the three systems in terms of classification accuracy and studied the effect of the variation of the number of inputs, training images and of iterations. The VGG16 network provides the highest classification accuracy when the training and the validation-test of the network are performed using data from the same samples for both the cartilage (99.8%) and the liver (95.5%) datasets. The Inception V3 and Xception networks achieve an accuracy of 84.7% (43.1%) and of 72.6% (53.7%), respectively, for the cartilage (liver) images. By using data from different samples for the training and validation-test processes, the Xception network provided the highest test accuracy for the cartilage dataset (75.7%), while for the liver dataset the VGG16 network gave the best results (75.4%). By using convolutional neuronal networks we show that it is possible to classify large datasets of biomedical images in less than 25 min on a 8 CPU processor machine providing a precise, robust, fast and observer-independent method for the discrimination/classification of different stages of osteoarthritis and liver diseases

    Artifact reduction of coaxial needles in magnetic resonance imaging-guided abdominal interventions at 1.5 T: a phantom study

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    Needle artifacts pose a major limitation for MRI-guided interventions, as they impact the visually perceived needle size and needle-to-target-distance. The objective of this agar liver phantom study was to establish an experimental basis to understand and reduce needle artifact formation during MRI-guided abdominal interventions. Using a vendor-specific prototype fluoroscopic T1-weighted gradient echo sequence with real-time multiplanar acquisition at 1.5~T, the influence of 6 parameters (flip angle, bandwidth, matrix, slice thickness, read-out direction, intervention angle relative to B0) on artifact formation of 4 different coaxial MR-compatible coaxial needles (Nitinol, 16G-22G) was investigated. As one parameter was modified, the others remained constant. For each individual parameter variation, 2 independent and blinded readers rated artifact diameters at 2 predefined positions (15~mm distance from the perceived needle tip and at 50% of the needle length). Differences between the experimental subgroups were assessed by Bonferroni-corrected non-parametric tests. Correlations between continuous variables were expressed by the Bravais-Pearson coefficient and interrater reliability was quantified using the intraclass classification coefficient. Needle artifact size increased gradually with increasing flip angles (p = 0.002) as well as increasing intervention angles (p < 0.001). Artifact diameters differed significantly between the chosen matrix sizes (p = 0.002) while modifying bandwidth, readout direction, and slice thickness showed no significant differences. Interrater reliability was high (intraclass correlation coefficient 0.776-0.910). To minimize needle artifacts in MRI-guided abdominal interventions while maintaining optimal visibility of the coaxial needle, we suggest medium-range flip angles and low intervention angles relative to B0

    Pollination ecology and circadian patterns of inflorescence opening of the Madagascan climber Dalechampia aff. bernieri (Euphorbiaceae)

    Get PDF
    Floral morphology often directly influences interactions with pollinators, but less is known about the role of extrafloral structures. We studied the relationship between bract motility, floral structural specialization and pollination in Dalechampia aff. bernieri, an endemic Madagascan species with floral structures indicating specialized buzz-pollination. We measured circadian bract angles in 47 inflorescences from 11 plants of D. aff. bernieri; in addition, we recorded any flower-visiting insects observed. The inflorescences had motile bracts with mean angles varying from ~50° at 00h00 to ~90° at 10h45. They were visited by buzz-pollinating Nomia viridilimbata bees (Halictidae), but also by non-buzz-pollinating Liotrigona bees (Apidae). The temporal pattern of bract motility observed in D. aff. bernieri may represent an extra-floral specialization to reduce visitation by non-pollinating visitors while maximizing visitation by diurnal buzz-pollinating bee

    Incidental CT Findings in the Elderly with Low-Energy Falls: Prevalence and Implications

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    Background: Computed tomography (CT) is commonly used in trauma care, with increasing implementation during the emergency work-up of elderly patients with low-energy falls (LEF). The prevalence of incidental findings (IFs) resulting from CT imaging and requiring down-stream actions in this patient cohort is unknown. We have investigated the prevalence and urgency of IFs from emergency CT examinations in these patients. Methods: A total of 2871 patients with LEF and emergency CT examinations were consecutively included in this retrospective cohort study. The primary endpoint was the prevalence of IFs;the secondary endpoint was their urgency. Results: The median age was 82 years (64.2% were women). IFs were identified in 73.9% of patients, with an average of 1.6 IFs per patient. Of all IFs, 16.4% were classified as urgent or relevant, predominantly in the abdomen, chest and neck. Increasing age was associated with the prevalence of an IF (odds ratio: 1.053, 95% confidence interval: 1.042-1.064). Significantly more IFs were found in female patients (75.2% vs. 71.5%). Conclusion: IFs resulting from CT examinations of the elderly are frequent, but in more than 8 out of 10, they are harmless or currently asymptomatic. For the benefit of an accurate diagnosis of traumatic lesions, concerns about IFs with respect to disease burden, further work-up and resource utilisation might be disregarded

    Optimized visualization of focal liver lesions and vascular structures in real-time T1-weighted gradient echo sequences for magnetic resonance-guided liver procedures

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    PURPOSEThis study aimed to determine the optimal sequence parameters of a real-time T1-weighted (T1w) gradient echo (GRE) sequence for magnetic resonance (MR)-guided liver interventions.METHODSWe included 94 patients who underwent diagnostic liver MR imaging (MRI) and acquired additional real-time T1w GRE sequences with a closed 1.5-T MRI scanner 20 min after a liver-specific contrast agent was injected. In four measurement series, one of the following four sequence parameters was changed, and repeated scans with different values for this parameter were acquired: flip angle (FA) (10–90°), repetition time (TR) (5.47–8.58 ms), bandwidth (BW) (300–700 Hz/pixel), and matrix (96 × 96–256 × 256). Two readers rated the visualizations of the target and risk structures (7-point Likert scale) and the extent of artifacts (6-point Likert scale); they also quantified the lesion–liver contrast ratio, the lesion–liver contrast-to-noise ratio (CNR), and the liver signal-to-noise ratio (SNR). Substratification analyses were performed for differences in overall visual and quantitative assessments depending on the lesion size, type, and the presence of cirrhosis.RESULTSFor the utilized FAs and matrix sizes, significant differences were found in the visual assessments of the conspicuity of target lesions, risk structures, and the extent of artifacts as well as in the quantitative assessments of lesion–liver contrast ratios and liver SNRs (all P < 0.001). No differences were observed for modified TR and BW. Significantly increased conspicuity of the target and vascular structures was observed for both higher FAs and matrix sizes, while the ghosting artifacts increased and decreased, respectively. For primary liver tumors compared with metastatic lesions, and for cirrhotic livers compared with normal liver parenchyma, significantly decreased conspicuity of the target lesions (P = 0.005, P = 0.005), lesion–liver CNRs (P = 0.005, P = 0.032), and lesion–liver contrast ratios (P = 0.015, P = 0.032) were found. All results showed no significant correlation with lesion size.CONCLUSIONWe recommend an FA of 30°–45° and a matrix size of 128 × 128–192 × 192 for MR-guided liver interventions with real-time T1w sequences to provide a balance between good visualizations of target and risk structures, high signal intensities, and low ghosting artifacts. The visualization of the target lesion may vary due to clinical conditions, such as lesion type or associated chronic liver disease

    Structured reporting of x-rays for atraumatic shoulder pain: advantages over free text?

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    Background: To analyse structured and free text reports of shoulder X-ray examinations evaluating the quality of reports and potential contributions to clinical decision-making. Methods: We acquired both standard free text and structured reports of 31 patients with a painful shoulder without history of previous trauma who received X-ray exams. A template was created for the structured report based on the template ID 0000154 (Shoulder X-ray) from radreportorg using online software with clickable decision trees with concomitant generation of structured semantic reports. All reports were evaluated regarding overall quality and key features: content, information extraction and clinical relevance. Results: Two experienced orthopaedic surgeons reviewed and rated structured and free text reports of 31 patients independently. The structured reports achieved significantly higher median ratings in all key features evaluated (P< 0.001), including facilitation of information extraction (P< 0.001) and better contribution to subsequent clinical decision-making (P<0.001). The overall quality of structured reports was significantly higher than in free text report (P< 0.001). Conclusions: A comprehensive structured template may be a useful tool to assist in clinical decision-making and is, thus, recommended for the reporting of degenerative changes regarding X-ray examinations of the shoulder

    Patentability, R&D direction, and cumulative innovation

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    We present a model of cumulative innovation where firms can conduct R&D in both a safe and a risky direction. Innovations in the risky direction produce quality improvements with higher expected sizes and variances. As patentability standards rise, an innovation in the risky direction is less likely to receive a patent that replaces the current technology, which decreases the static incentive for new entrants to conduct risky R&D, but increases their dynamic incentive because of the longer duration---and hence higher reward---for incumbency. These, together with a strategic substitution and a market structure effect, result in an inverted-U shape in the risky direction but a U shape in the safe direction for the relationship between R&D intensity and patentability standards. There exists a patentability standard that induces the efficient innovation direction, whereas R&D is biased towards (against) the risky direction under lower (higher) standards. The optimal patentability standard may distort the R&D direction to increase the industry innovation rate that is socially deficient
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