No abstract

There is increasing interest in the diving behavior of marine mammals. However, identifying foraging among recorded dives often requires several assumptions. The simultaneous acquisition of images of the prey encountered, together with records of diving behavior will allow researchers to more fully investigate the nature of subsurface behavior. We tested a novel digital camera linked to a time‐depth recorder on Antarctic fur seals (Arctocephalus gazella). During the austral summer 2000–2001, this system was deployed on six lactating female fur seals at Bird Island, South Georgia, each for a single foraging trip. The camera was triggered at depths greater than 10 m. Five deployments recorded still images (640 × 480 pixels) at 3‐sec intervals (total 8,288 images), the other recorded movie images at 0.2‐sec intervals (total 7,598 frames). Memory limitation (64 MB) restricted sampling to approximately 1.5 d of 5–7 d foraging trips. An average of 8.5% of still pictures (2.4%‐11.6%) showed krill (Euphausia sulperba) distinctly, while at least half the images in each deployment were empty, the remainder containing blurred or indistinct prey. In one deployment krill images were recorded within 2.5 h (16 km, assuming 1.8 m/sec travel speed) of leaving the beach. Five of the six deployments also showed other fur seals foraging in conjunction with the study animal. This system is likely to generate exciting new avenues for interpretation of diving behavior.

We use multiple scattering of ultrasound waves to characterize the lung micro-architecture in order to differentiate between a healthy lung and a lung suffering from Alveolar Interstitial Lung Diseases. The experimental setup consists of a linear transducer array with an 8 MHz central frequency placed in direct contact of the lung to be assessed. The diffusion constant D and scattering mean free path L* of the lung parenchyma are estimated by separating the incoherent and the coherent intensities in the near field. 2D FDTD numerical simulations were carried out on rabbit histology images with varying degrees of lung collapse. Phantom experiments were conducted in melamine sponges to study the variations in D and L* with varying air volume fraction. Significant correlations were observed between air volume fraction and L* in simulation (r = -0.9542, p<0.0117) and sponge phantom experiments (r = -0.9932, p<0.0068). Finally, in vivo measurements were conducted in healthy and edematous rat lungs. In the control rat lung, L* was found equal to 83 μm ( + /-14.9), whereas in the edematous lung, it was found equal to 260 μm ( + /-27). These results are extremely promising for the assessment of lung pathologies using ultrasound.

Current hydrogel or fabric patches for organ repair are generally not designed to conform to the complex mechanics of dynamic organs such as the lung or heart. This study presents a new, biocompatible and bilayered, hydrogelbased patch platform, consisting of a non-fouling top layer and a cell adhesive bottom layer, that caters to the anisotropic and auxetic characteristics of dynamic organs. Integrated computational and experimental studies are used to screen over 116 unique anisotropic-auxetic architectures to establish design rules and tailor the patches to a broad range of target organ dynamics. The patches are then validated in ex vivo and in vivo animal models, where the auxetic patches outperformed non-auxetic patches in conforming to the volumetric dilation-contraction of dynamic organs. To further expand the functionality of the auxetic patch platform, novel hole-filling auxetic patches are developed. These hole-filling patches composited with fibrin robustly reduce pulmonary air leakage in rats with surgically induced lung puncture. This is the first demonstration of a rational patch design framework that features both anisotropic and auxetic properties to cater to a wide range of organ dynamics. These studies pave the way for future clinical development of biomimetic patches.