Ultra-fast escape maneuver of an octopus-inspired robot

We design and test an octopus-inspired flexible hull robot that demonstrates outstanding fast-starting performance. The robot is hyper-inflated with water, and then rapidly deflates to expel the fluid so as to power the escape maneuver. Using this robot we verify for the first time in laboratory testing that rapid size-change can substantially reduce separation in bluff bodies traveling several body lengths, and recover fluid energy which can be employed to improve the propulsive performance. The robot is found to experience speeds over ten body lengths per second, exceeding that of a similarly propelled optimally streamlined rigid rocket. The peak net thrust force on the robot is more than 2.6 times that on an optimal rigid body performing the same maneuver, experimentally demonstrating large energy recovery and enabling acceleration greater than 14 body lengths per second squared. Finally, over 53% of the available energy is converted into payload kinetic energy, a performance that exceeds the estimated energy conversion efficiency of fast-starting fish. The Reynolds number based on final speed and robot length is $Re \approx 700,000$. We use the experimental data to establish a fundamental deflation scaling parameter $\sigma^*$ which characterizes the mechanisms of flow control via shape change. Based on this scaling parameter, we find that the fast-starting performance improves with increasing size.Comment: Submitted July 10th to Bioinspiration & Biomimetic

Sensitivity of the N. AEGEAN SEA ecosystem to Black Sea Water inputs

The effect of Black Sea Water (BSW) inputs on the North Aegean Sea productivity and food web dynamics was investigated, by means of sensitivity simulations, investigating the effect of the inflowing BSW, in terms of inorganic nutrients and dissolved organic matter. The model used has been successfully applied in the area in the past and extensively presented. Considering the importance of the microbial loop in the ecosystem functioning, the role of the dissolved organics and in order to achieve a more realistic representation of the Dissolved Organic Matter pool, the bacteria sub-model was appropriately revised. The importance of the microbial loop is highlighted by the carbon fluxes where almost 50% of carbon is channelled within it. The impact of dissolved organic matter (DOM) (in the inflowing to the Aegean Sea, BSW) appears to be stronger than the impact of dissolved inorganic nutrients, showing a more extended effect over the N Aegean. Bacterial production and biomass is more strongly affected in the simulations by modified DOM, unlike phytoplankton biomass and production, which are more dependent on the inflowing nutrients and particularly phosphorus (inorganic and dissolved organic). In the phytoplankton composition, the dinoflagellates appear to be mostly affected, being favoured by higher nutrient availability at the expense of all other groups, particularly picoplankton, indicating a shift to a more classical food chain

Shape of retracting foils that model morphing bodies controls shed energy and wake structure

The flow mechanisms of shape-changing moving bodies are investigated through the simple model of a foil that is rapidly retracted over a spanwise distance as it is towed at constant angle of attack. It is shown experimentally and through simulation that by altering the shape of the tip of the retracting foil, different shape-changing conditions may be reproduced, corresponding to: (i) a vanishing body, (ii) a deflating body and (iii) a melting body. A sharp-edge, ‘vanishing-like’ foil manifests strong energy release to the fluid; however, it is accompanied by an additional release of energy, resulting in the formation of a strong ring vortex at the sharp tip edges of the foil during the retracting motion. This additional energy release introduces complex and quickly evolving vortex structures. By contrast, a streamlined, ‘shrinking-like’ foil avoids generating the ring vortex, leaving a structurally simpler wake. The ‘shrinking’ foil also recovers a large part of the initial energy from the fluid, resulting in much weaker wake structures. Finally, a sharp edged but hollow, ‘melting-like’ foil provides an energetic wake while avoiding the generation of a vortex ring. As a result, a melting-like body forms a simple and highly energetic and stable wake, that entrains all of the original added mass fluid energy. The three conditions studied correspond to different modes of flow control employed by aquatic animals and birds, and encountered in disappearing bodies, such as rising bubbles undergoing phase change to fluid

Diagnostic yield of endoscopic ultrasound-guided tissue acquisition in autoimmune pancreatitis: a systematic review and meta-analysis

Background and study aims There is limited evidence on the diagnostic performance of endoscopic ultrasound (EUS)-guided tissue acquisition in autoimmune pancreatitis (AIP). The aim of this meta-analysis was to provide a pooled estimate of the diagnostic performance of EUS-guided fine-needle aspiration (FNA) and fine-needle biopsy (FNB) in patients with AIP. Patients and methods Computerized bibliographic search was performed through January 2020. Pooled effects were calculated using a random-effects model by means of DerSimonian and Laird test. Primary endpoint was diagnostic accuracy compared to clinical diagnostic criteria. Additional outcomes were definitive histopathology, pooled rates of adequate material for histological diagnosis, sample adequacy, mean number of needle passes. Diagnostic sensitivity and safety data were also analyzed. Results Fifteen studies with 631 patients were included, of which four were prospective series and one randomized trial. Overall diagnostic accuracy of EUS tissue acquisition was 54.7 % (95 % confidence interval, 40.9 %-68.4 %), with a clear superiority of FNB over FNA (63 %, 52.7 % to 73.4 % versus 45.7 %, 26.5 %-65 %; p < 0.001). FNB provided level 1 of histological diagnosis in 44.2 % of cases (30.8 %-57.5 %) as compared to 21.9 % (10 %-33.7 %) with FNA ( P < 0.001). The rate of definitive histopathology of EUS tissue sampling was 20.7 % (12.9 %-28.5 %) and it was significantly higher with FNB (24.3 %, 11.8 %-36.8 %) as compared to FNA (14.7 %, 5.4 %-23.9 %; P < 0.001). Less than 1 % of subjects experienced post-procedural acute pancreatitis. Conclusion The results of this meta-analysis demonstrate that the diagnostic performance of EUS-guided tissue acquisition is modest in patients with AIP, with an improved performance of FNB compared to FNA

Recent developments with the new tools for collimation simulations in Xsuite

Simulations of single-particle tracking involving collimation systems need dedicated tools to perform the different tasks needed. These include the accurate description of particle-matter interactions when a tracked particle impacts a collimator jaw; a detailed aperture model to identify the longitudinal location of losses; and others. One such tool is the K2 code in SixTrack, which describes the scattering of high-energy protons in matter. This code has recently been ported into the Xsuite tracking code that is being developed at CERN. Another approach is to couple the tracking with existing tools, such as FLUKA or Geant4, that offer better descriptions of particle-matter interactions and can treat lepton and ion beams. This includes the generation of secondary particles and fragmentation when tracking ions. In addition to the development of coupling with Geant4, the SixTrack-FLUKA coupling has recently been translated and integrated into the Xsuite environment as well. In this paper, we present the ongoing development of these tools. A thorough testing of the new implementation was performed, using as case studies various collimation layout configurations for the LHC Run 3

Association between pancreatic intraductal papillary mucinous neoplasms and extrapancreatic malignancies: A systematic review with meta-analysis

Background: It is unclear whether patients with intraductal papillary mucinous neoplasia harbor a higher risk of developing extrapancreatic malignancies. Aims: We performed a pooled estimate of the incidence of extrapancreatic malignancies in patients with intraductal papillary mucinous neoplasia, with a particular focus on the comparison to the general population. Methods: Computerized bibliographic search of main databases was performed through February 2021. The primary endpoint was the pooled incidence of extrapancreatic malignancies in patients with intraductal papillary mucinous neoplasms. Additional outcome was the comparison between intraductal papillary mucinous neoplasia patients and the general population, expressed in terms of standardized incidence ratio along with 95% confidence intervals. Results: Eighteen studies with 8709 patients were included. The pooled rate of metachronous extrapancreatic malignancies was 10 (6e13)/1000 persons-year. No difference was observed according to intraductal papillary mucinous neoplasia histology and sex, whereas a significantly superior incidence of extrapancreatic malignancies was observed in patients with main-duct (36.7%, 25.4ä8%) as compared to branch-duct intraductal papillary mucinous neoplasia (26.2%, 17.6ã4.8%; p 1⁄4 0.03). Pooled standardized incidence ratio comparing expected rates in the general population was 1.01 (0.79e1.29); no difference was observed concerning rates of metachronous gastric cancer (standardized incidence ratio 1.60, 0.72e3.54) and colorectal cancer (1.29, 0.92e1.18), whereas biliary cancer was observed more frequently in intraductal papillary mucinous neoplasia patients (2.29, 1.07e4.93). Conclusion: Patients with intraductal papillary mucinous neoplasia harbor an overall rate of extrapancreatic malignancies as high as 27.3%. The rate of metachronous extrapancreatic malignancies is not superior to the general population

Predicting Treatment Response in Social Anxiety Disorder From Functional Magnetic Resonance Imaging

Context: Current behavioral measures poorly predict treatment outcome in social anxiety disorder (SAD). To our knowledge, this is the first study to examine neuroimaging-based treatment prediction in SAD. Objective: To measure brain activation in patients with SAD as a biomarker to predict subsequent response to cognitive behavioral therapy (CBT). Design: Functional magnetic resonance imaging (fMRI) data were collected prior to CBT intervention. Changes in clinical status were regressed on brain responses and tested for selectivity for social stimuli. Setting: Patients were treated with protocol-based CBT at anxiety disorder programs at Boston University or Massachusetts General Hospital and underwent neuroimaging data collection at Massachusetts Institute of Technology. Patients: Thirty-nine medication-free patients meeting DSM-IV criteria for the generalized subtype of SAD. Interventions: Brain responses to angry vs neutral faces or emotional vs neutral scenes were examined with fMRI prior to initiation of CBT. Main Outcome Measures: Whole-brain regression analyses with differential fMRI responses for angry vs neutral faces and changes in Liebowitz Social Anxiety Scale score as the treatment outcome measure. Results: Pretreatment responses significantly predicted subsequent treatment outcome of patients selectively for social stimuli and particularly in regions of higher-order visual cortex. Combining the brain measures with information on clinical severity accounted for more than 40% of the variance in treatment response and substantially exceeded predictions based on clinical measures at baseline. Prediction success was unaffected by testing for potential confounding factors such as depression severity at baseline. Conclusions: The results suggest that brain imaging can provide biomarkers that substantially improve predictions for the success of cognitive behavioral interventions and more generally suggest that such biomarkers may offer evidence-based, personalized medicine approaches for optimally selecting among treatment options for a patient