4216 Application of artificial neural networks for image analysis of organ culture preserved donor corneas: A pilot study

Gastrointestinal (GI) cancers account for 1.5 million deaths worldwide. Endoscopic Submucosal Dissection (ESD) is an advanced therapeutic endoscopy technique with superior clinical outcome due to the minimally invasive and en bloc removal of tumours. In the western world, ESD is seldom carried out, due to its complex and challenging nature. Various surgical systems are being developed to make this therapy accessible, however, these solutions have shown limited operational workspace, dexterity, or low force exertion capabilities. The current paper shows the ESD CYCLOPS system, a bimanual surgical robotic attachment that can be mounted at the end of any flexible endoscope. The system is able to achieve forces of up to 46N, and showed a mean error of 0.217mm during an elliptical tracing task. The workspace and instrument dexterity is shown by pre-clinical ex vivo trials, in which ESD is successfully performed by a GI surgeon. The system is currently undergoing pre-clinical in vivo validation

A study of the deep structure of the energy landscape of glassy polystyrene: the exponential distribution of the energy-barriers revealed by high-field Electron Spin Resonance spectroscopy

The reorientation of one small paramagnetic molecule (spin probe) in glassy polystyrene (PS) is studied by high-field Electron Spin Resonance spectroscopy at two different Larmor frequencies (190 and 285 GHz). The exponential distribution of the energy-barriers for the rotational motion of the spin probe is unambigously evidenced at both 240K and 270K. The same shape for the distribution of the energy-barriers of PS was evidenced by the master curves provided by previous mechanical and light scattering studies. The breadth of the energy-barriers distribution of the spin probe is in the range of the estimates of the breadth of the PS energy-barriers distribution. The evidence that the deep structure of the energy landscape of PS exhibits the exponential shape of the energy-barriers distribution agrees with results from extreme-value statistics and the trap model by Bouchaud and coworkers.Comment: Final version in press as Letter to the Editor on J.Phys.:Condensed Matter. Changes in bol

Experimental Investigation of the Classical Rayleigh-Taylor Instability

The evolution of the Rayleigh-Taylor (RT) instability in a compressible medium has been investigated at an accelerating embedded interface and at the ablation front in a series of experiments on the Nova laser. The x-ray drive generated in a gold hohlraum ablatively accelerated a planar target consisting of a doped plastic pusher backed by a higher density titanium payload with perturbations placed at the plastic-Ti interface. The targets were diagnosed by face-on and side-on radiography. In previous work focusing on single mode perturbations, wavelengths as short as 10 m have been observed to grow strongly at the embedded interface. Here multimode perturbations consisting of either 2, 10 or 20 modes superposed in phase have been investigated

Strong field ionization in arbitrary laser polarizations

Published versio

High-pressure, High-strain-rate Materials Effects

A 3-year LDRD-ER project to study the response of shocked materials at high pressure and high strain rate has concluded. This project involved a coordinated effort to study single crystal samples that were shock loaded by direct laser irradiation, in-situ and post-recovery measurements, and molecular dynamics and continuum modeling. Laser-based shock experiments have been conducted to study the dynamic response of materials under shock loading materials at a high strain-rate. Experiments were conducted at pressures above the published Hugoniot Elastic Limit (HEL). The residual deformation present in recovered samples was characterized by transmission electron microscopy, and the response of the shocked lattice during shock loading was measured by in-situ x-ray diffraction. Static film and x-ray streak cameras recorded x-rays diffracted from lattice planes of Cu and Si both parallel and perpendicular to the shock direction. Experiments were also conducted using a wide-angle detector to record x-rays diffracted from multiple lattice planes simultaneously. This data showed uniaxial compression of Si (100) along the shock direction and 3-dimensional compression of Cu (100). In the case of the Si diffraction, there was a multiple wave structure observed. We present results of shocked Si and Cu obtained with a new large angle diffraction diagnostic, and discuss the results in the context of detailed molecular dynamics simulations and post-processing

Review of experiments and calculations of the compressible richtmyer-meshkov instability from a single-mode, nonlinear initial perturbation

We review experiments and calculations of the compressible Richtmyer-Meshkov instability from a single-mode, nonlinear initial perturbation. These experiments were performed using the Nova laser. Measurements of the time-evolution of the mixing region were reported previously. We compared the experimental measurements with numerical simulations [1,2]. We found both experiment and simulation to be in good agreement with recent theories for the nonlinear evolution of the instability [3,4]. Experimental results beyond those previously presented provide additional support for the use of two phase flow models to describe the flow in the nonlinear regime. These experiments include measurement of the mixing region at additional times, including times earlier in the evolution of the instability than previously reported. We have also carried out experiments to examine the difference in the evolution of the instability from initial perturbations consisting of circular sawtooth grooves as well as rectilinear sawteeth. Our previous two-dimensional numerical simulations approximated the experimental linear grooves as circular grooves. We reasoned that the difference between the two cases would be small, based on scaling arguments, and limited to a very small region near the centerline. New experimental and numerical results confirm this. Finally, we discuss some additional issues in the derivation of the two-phase flow model used previously in describing the growth of the Richtmyer-Meshkov instability in the nonlinear phase relevant to other work presented at this meeting [5,6]

Strongly exchange-coupled triplet pairs in an organic semiconductor

From biological complexes to devices based on organic semiconductors, spin interactions play a key role in the function of molecular systems. For instance, triplet-pair reactions impact operation of organic light-emitting diodes as well as photovoltaic devices. Conventional models for triplet pairs assume they interact only weakly. Here, using electron spin resonance, we observe long-lived, strongly-interacting triplet pairs in an organic semiconductor, generated via singlet fission. Using coherent spin-manipulation of these two-triplet states, we identify exchange-coupled (spin-2) quintet complexes co-existing with weakly coupled (spin-1) triplets. We measure strongly coupled pairs with a lifetime approaching 3 µs and a spin coherence time approaching 1 µs, at 10 K. Our results pave the way for the utilization of high-spin systems in organic semiconductors.Gates-Cambridge Trust, Winton Programme for the Physics of Sustainability, Freie Universität Berlin within the Excellence Initiative of the German Research Foundation, Engineering and Physical Sciences Research Council (Grant ID: EP/G060738/1)This is the author accepted manuscript. The final version is available from Nature Publishing Group at http://dx.doi.org/10.1038/nphys3908