Aerodynamics of the Cupped Wings during Peregrine Falcon’s Diving Flight

During a dive peregrine falcons can reach velocities of more than 320 km/h and makes themselves the fastest animals in the world. The aerodynamic mechanisms involved are not fully understood yet and the search for a conclusive answer to this fact motivates the three-dimensional (3-D) flow study. Especially the cupped wing configuration which is a unique feature of the wing shape in falcon peregrine dive is our focus herein. In particular, the flow in the gap between the main body and the cupped wing is studied to understand how this flow interacts with the body and to what extend it affects the integral forces of lift and drag. Characteristic shapes of the wings while divingare studied with regard to their aerodynamics using computational fluid dynamics (CFD). The results of the numerical simulations via ICEM CFD and OpenFOAM show predominant flow structures around the body surface and in the wake of the falcon model such as a pair of body vortices and tip vortices. The drag for the cupped wing profile is reduced in relation to the configuration of opened wings (without cupped-like profile) while lift is increased. The purpose of this study is primarily the basic research of the aerodynamic mechanisms during the falcon’s diving flight. The results could be important for maintaining good maneuverability at high speeds in the aviation sector

Diving-flight aerodynamics of a peregrine falcon (Falco peregrinus)

This study investigates the aerodynamics of the falcon Falco peregrinus while diving. During a dive peregrines can reach velocities of more than 320 km h⁻¹. Unfortunately, in freely roaming falcons, these high velocities prohibit a precise determination of flight parameters such as velocity and acceleration as well as body shape and wing contour. Therefore, individual F. peregrinus were trained to dive in front of a vertical dam with a height of 60 m. The presence of a well-defined background allowed us to reconstruct the flight path and the body shape of the falcon during certain flight phases. Flight trajectories were obtained with a stereo high-speed camera system. In addition, body images of the falcon were taken from two perspectives with a high-resolution digital camera. The dam allowed us to match the high-resolution images obtained from the digital camera with the corresponding images taken with the high-speed cameras. Using these data we built a life-size model of F. peregrinus and used it to measure the drag and lift forces in a wind-tunnel. We compared these forces acting on the model with the data obtained from the 3-D flight path trajectory of the diving F. peregrinus. Visualizations of the flow in the wind-tunnel uncovered details of the flow structure around the falcon's body, which suggests local regions with separation of flow. High-resolution pictures of the diving peregrine indicate that feathers pop-up in the equivalent regions, where flow separation in the model falcon occurred

Activated plasma coagulation β-Factor XII-induced vasoconstriction in rats

By inducing BK (bradykinin)-stimulated adrenomedullary catecholamine release, bolus injection of the β-fragment of activated plasma coagulation Factor XII (β-FXIIa) transiently elevates BP (blood pressure) and HR (heart rate) of anaesthetized, vagotomized, ganglion-blocked, captopril-treated bioassay rats. We hypothesized that intravenous infusion of β-FXIIa into intact untreated rats would elicit a qualitatively similar vasoconstrictor response. BN (Brown Norway) rats received for 60 min either: (i) saline (control; n=10); (ii) β-FXIIa (85 ng/min per kg of body weight; n=9); or (iii) β-FXIIa after 2ADX (bilateral adrenalectomy; n=9). LV (left ventricular) volume and aortic BP were recorded before (30 min baseline), during (60 min) and after (30 min recovery) the infusion. TPR (total peripheral resistance) was derived from MAP (mean arterial pressure), SV (stroke volume) and HR. Saline had no haemodynamic effects. β-FXIIa infusion increased its plasma concentration 3-fold in both groups. In adrenally intact rats, β-FXIIa infusion increased MAP by 6% (5±2 mmHg) and TPR by 45% (0.50±0.12 mmHg/ml per min), despite falls in SV (−38±8 μl) and HR [−18±5 b.p.m. (beats/min)] (all P<0.05). In 2ADX rats, β-FXIIa had no HR effect, but decreased SV (−89±9 μl) and MAP (−4±1 mmHg), and increased TPR by 66% (0.59±0.15 mmHg/ml per min) (all P<0.05). After infusion, adrenally intact rats exhibited persistent vasoconstriction (MAP, 10±1 mmHg; TPR, 0.55±0.07 mmHg/ml per min; both P<0.05), whereas in 2ADX rats, MAP remained 5±1 mmHg below baseline (P<0.05) and TPR returned to baseline. End-study arterial adrenaline (epinephrine) concentrations in the three groups were 1.9±0.6, 9.8±4.1 and 0.6±0.2 nmol/l respectively. Thus, in neurally intact lightly anaesthetized untreated rats, β-FXIIa infusion induces both adrenal catecholamine-mediated and adrenally independent increases in peripheral resistance

Testing for an effect of a mindfulness induction on child executive functions

Several sessions of mindfulness practice can exert positive gains for child executive functions (EF); however, the evidence for effects of a mindfulness induction, on EF for adults, is mixed and this effect has not been tested in children. The immediate effect of an age appropriate 3-min mindfulness induction on EF of children aged 4–7 years was tested. Participants (N = 156) were randomly assigned to a mindfulness induction or dot-to-dot activity comparison group before completing four measures of EF. A composite score for EF was calculated from summed z scores of the four EF measures. A difference at baseline in behavioural difficulties between the mindfulness induction and comparison group meant that data was analysed using a hierarchical regression. The mindfulness induction resulted in higher average performance for the composite EF score (M = 0.12) compared to the comparison group (M = − 0.05). Behavioural difficulties significantly predicted 5.3% of the variance in EF performance but participation in the mindfulness or comparison induction did not significantly affect EF. The non-significant effect of a mindfulness induction to exert immediate effects on EF fits within broader evidence reporting mixed effects when similar experimental designs have been used with adults. The findings are discussed with consideration of the extent to which methodological differences may account for these mixed effects and how mindfulness inductions fit within broader theoretical and empirical understanding of the effects of mindfulness on EF

4D visualization study of a vortex ring life cycle using modal analyses

In this study, the life cycle of a vortex ring is visualized and simultaneously investigated in a three-dimensional (3D) domain and time resolved for an observer in a reference frame moving with the ring. By traversing the system, the object of interest is captured within the measurement volume during the entire cycle. The 4D (time-resolved 3D) data gained from the experiment are postprocessed by using modal analyses such as proper orthogonal decomposition and dynamic mode decomposition (DMD). The latter is used to reconstruct the vortex dynamics by means of the Q values, based on the most dominant modes in the DMD. These modal analyses allow reconstructing the dominant dynamics of the behavior of the secondary structures and their interaction with the vortex core. The visualization for the vortex ring at ReΓ = 5500 shows the well-known azimuthal instability and its growth at n = 6 in our experiments. As the process of transition further develops, we found a zig-zag-like mesh of tilted secondary structure and finally, helical coil-type vortex ribbons wrapped around the core, which emerge in the late-stage process. It is hypothesized that the initial state of this process is the emergence of a pair of standing helical waves both counterbalancing each other at the beginning and forming the zig-zag pattern. Azimuthal core flow is only weak in this phase. Later in the transition, one of the helical waves starts to take over the other and finally dominates. This results in the helical coil-type vortex structure seen in the reconstructed results, which goes with the increase in axial flow along the core. The hypothesis of coexisting helical waves is drawn from similarities in the transition of attached vortex rings in axisymmetric wakes

Measuring Behavioral Regulation in Four Societies

The present study examined the psychometric properties of scores from a direct measure of behavioral regulation, the Head&ndash;Toes&ndash;Knees&ndash;Shoulders task (HTKS) with 3- to 6-year-old children in the United States, Taiwan, South Korea, and China. Specifically, we investigated (a) the nature and variability of HTKS scores, including relations to teacher-rated classroom behavioral regulation; and (b) relations between the HTKS and early mathematics, vocabulary, and literacy skills. Higher HTKS scores were significantly related to higher teacher ratings of classroom behavioral regulation in the United States and South Korea but not in Taiwan and China. Also, higher HTKS scores were significantly related to higher early mathematics, vocabulary, and literacy skills beyond the influence of demographic variables and teacher-rated classroom behavioral regulation. These&nbsp; initial&nbsp;findings suggest that HTKS scores may be interpreted as reflecting early behavioral regulation in these 4 societies and that behavioral regulation is important for early academic success in the United States and in Asian countries.The present study examined the psychometric properties of scores from a direct measure of behavioral regulation, the Head-Toes-Knees-Shoulders task (HTKS) with 3- to 6-year-old children in the United States, Taiwan, South Korea, and China. Specifically, we investigated (a) the nature and variability of HTKS scores, including relations to teacher-rated classroom behavioral regulation; and (b) relations between the HTKS and early mathematics, vocabulary, and literacy skills. Higher HTKS scores were significantly related to higher teacher ratings of classroom behavioral regulation in the United States and South Korea but not in Taiwan and China. Also, higher HTKS scores were significantly related to higher early mathematics, vocabulary, and literacy skills beyond the influence of demographic variables and teacher-rated classroom behavioral regulation. These initial findings suggest that HTKS scores may be interpreted as reflecting early behavioral regulation in these 4 societies and that behavioral regulation is important for early academic success in the United States and in Asian countries