No abstract

Details of the kinematics of free flight are very important to understanding insect flight mechanics. Important data for aerodynamic analysis and modeling include flight trajectory, body attitude and wing kinematics for individuals flying over a diverse array of behaviors, such as hovering, climbing and turning.A number of recent studies have focused on the kinematics of hovering and forward flight, using a variety of techniques. Azuma and Watanabe (1988) changed the velocity of the wind tunnel in their measurements. Dudley and Ellington (1990) calculated angles of attack in the free forward flight of bumblebees. Willmott and Ellington (1997) employed a variable-speed wind tunnel associated with the optomotor response to investigate wing and body kinematics during free forward flight of a hawkmoth over a range of speeds from hovering to 5 m s -1 . Wakeling and Ellington (1997) filmed the free flights of dragonflies and damselflies flying over the pond in the greenhouse at the University of Cambridge. The individuals were not restrained by either tethers or wind tunnels, but were free to vary the velocity and acceleration and could perform any flight action. In their analyses of forward flight, the stroke plane was constructed based on the assumption of bilateral wing symmetry, and variations in roll, yaw and pitch angles of the body through each flapping cycle were neglected. To date no detailed information on wing orientation or shape during free flight has been acquired.All kinds of flight behaviors are important for studying the aerodynamics and the control of flight. In turning maneuvers, the wings move asymmetrically, and the change in attitude is obvious even during one flapping cycle. We have also found that dragonflies exhibit substantial chordwise deformation and changes in camber during free flight, which might be important for aerodynamic models of flight performance.To study turning maneuvers involving obvious changing of the insect attitude, the description of wing kinematics should be based on a local body-centered coordinate system, together with the body attitude and flight trajectory. We have developed a method utilizing a Projected, Comb-Fringe technique combined with the Landmarks procedure (PCFL), in which a comb-fringe pattern with high intensity and sharpness was projected onto the transparent wing of a dragonfly in free flight. Images of the wings with distorted fringes were then recorded by a high-speed camera. Based on the distorted fringe pattern and the natural landmarks on the dragonfly wings, we reconstructed wing shape and established the body-centered coordinate system. This method allowed us to derive kinematic parameters without assumptions of rigid chords or kinematic symmetry, except for the assumption of rigid leading edges. The instantaneous attitude of the body was also measured simultaneously. We measured dragonflies in two flight behaviors: forward flight and turning maneuvers, and compared the kinematics results obtained for each of them. A robust technique for determinin...

Koi carps frequently swim in burst-and-coast style, which consists of a burst phase and a coast phase. We quantify the swimming kinematics and the flow patterns generated by the carps in burst-and-coast swimming. In the burst phase, the carps burst in two modes: in the first, the tail beats for at least one cycle (multiple tail-beat mode); in the second, the tail beats for only a half-cycle (half tail-beat mode). The carp generates a vortex ring in each half-cycle beat. The vortex rings generated during bursting in multiple tail-beat mode form a linked chain, but only one vortex ring is generated in half tail-beat mode. The wake morphologies, such as momentum angle and jet angle, also show much difference between the two modes. In the burst phase, the kinematic data and the impulse obtained from the wake are linked to obtain the drag coefficient (C d,burst Ϸ0.242). In the coast phase, drag coefficient (C d,coast Ϸ0.060) is estimated from swimming speed deceleration. Our estimation suggests that nearly 45% of energy is saved when burst-and-coast swimming is used by the koi carps compared with steady swimming at the same mean speed.

Osteosarcoma (OS) is the most common primary malignant tumor of bone with a high propensity for lung metastasis. Despite significant advances in surgical techniques and chemotherapeutic regimens over the past few decades, there has been minimal improvement in OS patient survival. There is an urgent need to identify novel antitumor agents to treat human OS. Repurposing the clinically-used drugs represents a rapid and effective approach to the development of new anticancer agents. The anthelmintic drug niclosamide has recently been identified as a potential anticancer agent in human cancers. Here, we investigate if niclosamide can be developed as an anti-OS drug. We find that niclosamide can effectively inhibit OS cell proliferation and survival at low micromolar concentrations. Cell migration and wounding closure are significantly inhibited by niclosamide. Niclosamide induces cell apoptosis and inhibits cell cycle progression in OS cells. Analysis of niclosamide's effect on 11 cancer-related signal pathway reporters reveals that three of them, the E2F1, AP1, and c-Myc-responsive reporters, are significantly inhibited. To a lesser extent, the HIF1α, TCF/LEF, CREB, NFκB, Smad/TGFβ, and Rbpj/Notch pathway reporters are also inhibited, while the NFAT and Wnt/β-catenin reporters are not significantly affected by niclosamide treatment. We demonstrate that the expression of c-Fos, c-Jun. E2F1, and c-Myc in OS cells is effectively inhibited by niclosamide. Furthermore, niclosamide is shown to effectively inhibit tumor growth in a mouse xenograft tumor model of human osteosarcoma cells. Taken together, these results strongly suggest that niclosamide may exert its anticancer activity in OS cells by targeting multiple signaling pathways. Future investigations should be directed to exploring the antitumor activity in clinically relevant OS models and ultimately in clinical trials.

In this report, we present a novel microfluidic islet array based on a hydrodynamic trapping principle. The lab-on-a-chip studies with live-cell multiparametric imaging allow understanding of physiological and pathophysiological changes of microencapsulated islets under hypoxic conditions. Using this microfluidic array and imaging analysis techniques, we demonstrate that hypoxia impairs the function of microencapsulated islets at single islet level, showing a heterogeneous pattern reflected in intracellular calcium signaling, mitochondrial energetic, and redox activity. Our approach demonstrates an improvement over conventional hypoxia chambers that is able to rapidly equilibrate to true hypoxia levels through the integration of dynamic oxygenation. This work demonstrates the feasibility of array-based cellular analysis and opens up new modality to conduct informative analysis and cell-based screening for microencapsulated pancreatic islets.