Wake Development behind Paired Wings with Tip and Root Trailing Vortices: Consequences for Animal Flight Force Estimates

Recent experiments on flapping flight in animals have shown that a variety of unrelated species shed a wake behind left and right wings consisting of both tip and root vortices. Here we present an investigation using Particle Image Velocimetry (PIV) of the behaviour and interaction of trailing vortices shed by paired, fixed wings that simplify and mimic the wake of a flying animal with a non-lifting body. We measured flow velocities at five positions downstream of two adjacent NACA 0012 aerofoils and systematically varied aspect ratio, the gap between the wings (corresponding to the width of a non-lifting body), angle of attack, and the Reynolds number. The range of aspect ratios and Reynolds number where chosen to be relevant to natural fliers and swimmers, and insect flight in particular. We show that the wake behind the paired wings deformed as a consequence of the induced flow distribution such that the wingtip vortices convected downwards while the root vortices twist around each other. Vortex interaction and wake deformation became more pronounced further downstream of the wing, so the positioning of PIV measurement planes in experiments on flying animals has an important effect on subsequent force estimates due to rotating induced flow vectors. Wake deformation was most severe behind wings with lower aspect ratios and when the distance between the wings was small, suggesting that animals that match this description constitute high-risk groups in terms of measurement error. Our results, therefore, have significant implications for experimental design where wake measurements are used to estimate forces generated in animal flight. In particular, the downstream distance of the measurement plane should be minimised, notwithstanding the animal welfare constraints when measuring the wake behind flying animals

Risk and Protective Factors for the Occurrence of Sporadic Pancreatic Endocrine Neoplasms

Pancreatic neuroendocrine neoplasms (PNENs) represent 10% of all pancreatic tumors by prevalence. Their incidence has reportedly increased over recent decades in parallel with that of pancreatic adenocarcinoma. PNENs are relatively rare, and of the few institutions that have published potential risk factors, findings have been heterogeneous. Our objective was to investigate the association between potential risk and protective factors for the occurrence of sporadic PNENs across a European population from several institutions. A multinational European case-control study was conducted to examine the association of selected environmental, family and medical exposure factors using a standardized questionnaire in face-to-face interviews. A ratio of 1:3 cases to controls were sex and age matched at each study site. Adjusted univariate and multivariate logistic regression analysis were performed for statistically significant factors. The following results were obtained: In 201 cases and 603 controls, non-recent onset diabetes (OR 2.09, CI 1.27-3.46) was associated with an increased occurrence of PNENs. The prevalence of non-recent onset diabetes was higher both in cases with metastatic disease (TNM stage III-IV) or advanced grade (G3) at the time of diagnosis. The use of metformin in combination with insulin was also associated with a more aggressive phenotype. Drinking coffee was more frequent in cases with localized disease at diagnosis. Our study concluded that non-recent onset diabetes was associated with an increased occurrence of PNENs and the combination of metformin and insulin was consistent with a more aggressive PNEN phenotype. In contrast to previous studies, smoking, alcohol and first-degree family history of cancer were not associated with PNEN occurrence

Efficiency of Lift Production in Flapping and Gliding Flight of Swifts

Many flying animals use both flapping and gliding flight as part of their routine behaviour. These two kinematic patterns impose conflicting requirements on wing design for aerodynamic efficiency and, in the absence of extreme morphing, wings cannot be optimised for both flight modes. In gliding flight, the wing experiences uniform incident flow and the optimal shape is a high aspect ratio wing with an elliptical planform. In flapping flight, on the other hand, the wing tip travels faster than the root, creating a spanwise velocity gradient. To compensate, the optimal wing shape should taper towards the tip (reducing the local chord) and/or twist from root to tip (reducing local angle of attack). We hypothesised that, if a bird is limited in its ability to morph its wings and adapt its wing shape to suit both flight modes, then a preference towards flapping flight optimization will be expected since this is the most energetically demanding flight mode. We tested this by studying a well-known flap-gliding species, the common swift, by measuring the wakes generated by two birds, one in gliding and one in flapping flight in a wind tunnel. We calculated span efficiency, the efficiency of lift production, and found that the flapping swift had consistently higher span efficiency than the gliding swift. This supports our hypothesis and suggests that even though swifts have been shown previously to increase their lift-to-drag ratio substantially when gliding, the wing morphology is tuned to be more aerodynamically efficient in generating lift during flapping. Since body drag can be assumed to be similar for both flapping and gliding, it follows that the higher total drag in flapping flight compared with gliding flight is primarily a consequence of an increase in wing profile drag due to the flapping motion, exceeding the reduction in induced drag

Endosonography and pretreatment tumor profiling - from sampling, staining, to sequencing

Background and aims: Endosonography-guided fine needle aspiration (EUS-FNA) is imperfect in diagnosing solid pancreatic lesions (SPL) and subepithelial lesions (SEL) including gastrointestinal stromal tumors (GIST). In GISTs, imatinib therapy is effective only in variants of oncogenes KIT and PDGFRA. The global aim was to improve the EUS-diagnostics and study a biopsy approach (EUS-FNB) to obtain a reliable diagnosis of SPLs and SELs. In GISTs, the aim was to evaluate pretreatment samples for tumor risk assessment and the guidance of down-sizing imatinib therapy. Methods: In two prospective, single-center studies (2012–2015), SPLs (n=68,Paper I) and SELs (n=70,Paper II) were sampled with EUS-FNA and EUS-FNB. A reference cohort (2006–2011) was used for comparison. The EUS-FNB-tissue of all GISTs (n=44) was subjected to Ki-67-indexing and DNA-sequencing of KIT and PDGFRA (Paper III). In a last study (Paper IV), pretreatment sequencing of GISTs (n=59) was performed. Results: Paper I: In SPLs, EUS-FNB and EUS-FNA had a comparable diagnostic accuracy (69% vs 78%, p=0.31). The combination EUS-FNA+FNB was superior to EUS-FNA alone in pancreatic non-adenocarcinoma neoplasms (89% vs 69%, p=0.02). Paper II: In SELs, EUS-FNB had a higher diagnostic accuracy compared with EUS-FNA (83% vs 49%, p<0.001) leading to the reduced need for additional diagnostic procedures (14% vs 53%, p<0.001). Paper III: The EUS-FNB-tissue was diagnostic for GIST in 98%, accurate for Ki-67-indexing in 92%, and adequate for successful sequencing in 98% of the cases. In patients treated with down-sizing imatinib [KIT exon 11 (n=9); PDGFRA exon 12 (n=1)], the Ki-67-index was significantly higher in pretreatment FNB-tissue compared with resection specimens: Ki-67DIFF = 2.3 (95% CI: 0.67-5.37, p=0.005). Paper IV: Pretreatment sequencing, compared with no sequencing, lead to a higher rate of accurate down-sizing therapy (97% vs 70 %, p<0.001) and to the increased preoperative tumor size reduction on CT scan (32% vs 22%, p=0.036). Conclusions: The performance of endosonography-guided fine-needle biopsy sampling has a significant diagnostic and clinical value in subepithelial lesions; especially in gastrointestinal stromal tumors. The acquired tissue is also accurate for the early tumor proliferation rate assessment and genetic profiling of GISTs. The suggested work-up approach facilitates the guidance and evaluation of down-sizing tyrosine kinase inhibitor therapy

Aerodynamics of gliding flight in common swifts.

Gliding flight performance and wake topology of a common swift (Apus apus L.) were examined in a wind tunnel at speeds between 7 and 11 m s(-1). The tunnel was tilted to simulate descending flight at different sink speeds. The swift varied its wingspan, wing area and tail span over the speed range. Wingspan decreased linearly with speed, whereas tail span decreased in a nonlinear manner. For each airspeed, the minimum glide angle was found. The corresponding sink speeds showed a curvilinear relationship with airspeed, with a minimum sink speed at 8.1 m s(-1) and a speed of best glide at 9.4 m s(-1). Lift-to-drag ratio was calculated for each airspeed and tilt angle combinations and the maximum for each speed showed a curvilinear relationship with airspeed, with a maximum of 12.5 at an airspeed of 9.5 m s(-1). Wake was sampled in the transverse plane using stereo digital particle image velocimetry (DPIV). The main structures of the wake were a pair of trailing wingtip vortices and a pair of trailing tail vortices. Circulation of these was measured and a model was constructed that showed good weight support. Parasite drag was estimated from the wake defect measured in the wake behind the body. Parasite drag coefficient ranged from 0.30 to 0.22 over the range of airspeeds. Induced drag was calculated and used to estimate profile drag coefficient, which was found to be in the same range as that previously measured on a Harris' hawk

Data for Henningsson et al 2018-J R Soc Interface-Part 1

Sequences 1 to 4 of the dat

Data for Henningsson et al 2018-J R Soc Interface-Part 3

Sequences 8 to 10 of the dat

Data from: Aerodynamics of manoeuvring flight in brown long-eared bats (Plecotus auritus)

In this study, we explicitly examine the aerodynamics of manoeuvring flight in animals. We studied brown long-eared bats flying in a wind tunnel while performing basic sideways manoeuvres. We used particle image velocimetry in combination with high-speed filming to link aerodynamics and kinematics to understand the mechanistic basis of manoeuvres. We predicted that the bats would primarily use the downstroke to generate the asymmetries for the manoeuvre since it has been shown previously that the majority of forces are generated during this phase of the wingbeat. We found instead that the bats more often used the upstroke than they used the downstroke for this. We also found that the bats used both drag/thrust-based and lift-based asymmetries to perform the manoeuvre and that they even frequently switch between these within the course of a manoeuvre. We conclude that the bats used three main modes: lift asymmetries during downstroke, thrust/drag asymmetries during downstroke and thrust/drag asymmetries during upstroke. For future studies, we hypothesize that lift asymmetries are used for fast turns and thrust/drag for slow turns and that the choice between up- and downstroke depends on the timing of when the bat needs to generate asymmetries

Data for Henningsson et al 2018-J R Soc Interface-Part 2

Sequences 5 to 7 of the dat