University of California

About: University of California is a education organization based out in Oakland, California, United States. It is known for research contribution in the topics: Population & Layer (electronics). The organization has 55175 authors who have published 52933 publications receiving 1491169 citations. The organization is also known as: UC & University of California System.

Clot capture coil

Abstract: A clot and foreign body removal device is described which comprises a catheter with at least one lumen. Located within the catheter is a clot capture coil that is connected to an insertion mandrel. In one embodiment, the clot capture coil is made out of a solid elastic or superelastic material which has shape memory, preferably nitinol. The elasticity or superelasticity of the coil allows it to be deformed within the catheter and to then reform its original coil configuration when the coil is moved outside of the catheter lumen. In another embodiment the coil is a biphasic coil which changes shape upon heating or passing an electric current. Once the coil configuration has been established, the coil can be used to ensnare and corkscrew a clot in a vessel. A clot is extracted from the vessel by moving the clot capture coil and catheter proximally until the clot can be removed or released into a different vessel that does not perfuse a critical organ. Foreign bodies are similarly captured by deploying the coil distal to the foreign body and moving the clot capture coil proximally until the foreign body is trapped within the coil. By removing the device from the body, the foreign material is also removed.

Convergence Rate Analysis of Several Splitting Schemes

Abstract: Operator-splitting schemes are iterative algorithms for solving many types of numerical problems. A lot is known about these methods: they converge, and in many cases we know how quickly they converge. But when they are applied to optimization problems, there is a gap in our understanding: The theoretical speed of operator-splitting schemes is nearly always measured in the ergodic sense, but ergodic operator-splitting schemes are rarely used in practice. In this chapter, we tackle the discrepancy between theory and practice and uncover fundamental limits of a class of operator-splitting schemes. Our surprising conclusion is that the relaxed Peaceman-Rachford splitting algorithm, a version of the Alternating Direction Method of Multipliers (ADMM), is nearly as fast as the proximal point algorithm in the ergodic sense and nearly as slow as the subgradient method in the nonergodic sense. A large class of operator-splitting schemes extend from the relaxed Peaceman-Rachford splitting algorithm. Our results show that this class of operator-splitting schemes is also nearly as slow as the subgradient method. The tools we create in this chapter can also be used to prove nonergodic convergence rates of more general splitting schemes, so they are interesting in their own right.

Optical-Field-Induced Birefringence and Freedericksz Transition in a Nematic Liquid Crystal

Abstract: Optical-field-induced birefringence in nematic 4-cyano-4′-pentylbiphenyl was measured with cw pump and probe beams, and the optical-field-induced Freedericksz transition was observed for the first time. The results are in quantitative agreement with the theoretical prediction.

Etchants for use in micromachining of CMOS Microaccelerometers and microelectromechanical devices and method of making the same

Abstract: What is described in the present specification are accelerometers using tiny proof masses and piezoresistive force detection. Conventional wisdom would indicate that this approach would not yield useful sensors. However, in fact, according to the invention, such devices are suitable in a wide range of applications. The devices may include deformable hinges to allow the fabrication of three dimensional structures. A new system has been developed which etches silicon highly selectively at moderate temperatures and without hydrodynamic forces potentially damaging to small structures and features. The system is based on the use of the gas phase etchant xenon diflouride, which is an unremarkable white solid at standard temperature and pressure.

Animated exploration of dynamic graphs with radial layout

Abstract: We describe a new animation technique for supporting interactive exploration of a graph. We use the well-known radial tree layout method, in which the view is determined by the selection of a focus node. Our main contribution is a method for animating the transition to a new layout when a new focus node is selected. In order to keep the transition easy to follow, the animation linearly interpolates the polar coordinates of the nodes, while enforcing ordering and orientation constraints. We apply this technique to visualizations of social networks and of the Gnutella file-sharing network, and discuss the results from our informal usability tests.