Technion – Israel Institute of Technology

About: Technion – Israel Institute of Technology is a education organization based out in Haifa, Israel. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 31714 authors who have published 79377 publications receiving 2603976 citations. The organization is also known as: Technion Israel Institute of Technology & Ṭekhniyon, Makhon ṭekhnologi le-Yiśraʼel.

Central Vein Catheterization. Failure and Complication Rates by Three Percutaneous Approaches

Abstract: • We prospectively studied the results of 714 attempts at central venous catheterization during an eight-month period in our intensive care department. We compared the rates of failure of catheterization and early complications among three percutaneous approaches: subclavian, anterior jugular, and posterior jugular veins. The procedures were performed by experienced staff or resident physicians and inexperienced interns and residents under teaching supervision. Overall rates of failure and complication were similar for each percutaneous approach within each group of physicians. Overall failure rate was 10.1% for the experienced group and 19.4% for the inexperienced. The complication was 5.4% for experienced and 11% for inexperienced. Among inexperienced physicians, the success rate was 86.7% and the complication rate 7.6% in unconscious patients, whereas in conscious patients these rates were 70.5% and 13.8%, respectively. The inexperienced physicians caused fewer complications in mechanically ventilated than in spontaneously breathing patients. We suggest that inexperienced physicians should first attempt central vein catheterizations in unconscious and mechanically ventilated patients. (Arch Intern Med1986;146:259-261)

The a.c. and d.c. Josephson effects in a Bose-Einstein condensate.

Abstract: The alternating- and direct-current (a.c. and d.c.) Josephson effects were first discovered in a system of two superconductors, the macroscopic wavefunctions of which are weakly coupled via a tunnelling barrier. In the a.c. Josephson effect, a constant chemical potential difference (voltage) is applied, which causes an oscillating current to flow through the barrier. Because the frequency is proportional to the chemical potential difference only, the a.c. Josephson effect serves as a voltage standard. In the d.c. Josephson effect, a small constant current is applied, resulting in a constant supercurrent flowing through the barrier. In a sense, the particles do not 'feel' the presence of the tall tunnelling barrier, and flow freely through it with no driving potential. Bose-Einstein condensates should also support Josephson effects; however, while plasma oscillations have been seen in a single Bose-Einstein condensate Josephson junction, the a.c. Josephson effect remains elusive. Here we observe the a.c. and d.c. Josephson effects in a single Bose-Einstein condensate Josephson junction. The d.c. Josephson effect has been observed previously only in superconducting systems; in our study, it is evident when we measure the chemical potential-current relation of the Bose-Einstein condensate Josephson junction. Our system constitutes a trapped-atom interferometer with continuous readout, which operates on the basis of the a.c. Josephson effect. In addition, the measured chemical potential-current relation shows that the device is suitable for use as an analogue of the superconducting quantum interference device, which would sense rotation.

Optical spatial solitons: historical overview and recent advances

Abstract: Solitons, nonlinear self-trapped wavepackets, have been extensively studied in many and diverse branches of physics such as optics, plasmas, condensed matter physics, fluid mechanics, particle physics and even astrophysics. Interestingly, over the past two decades, the field of solitons and related nonlinear phenomena has been substantially advanced and enriched by research and discoveries in nonlinear optics. While optical solitons have been vigorously investigated in both spatial and temporal domains, it is now fair to say that much soliton research has been mainly driven by the work on optical spatial solitons. This is partly due to the fact that although temporal solitons as realized in fiber optic systems are fundamentally one-dimensional entities, the high dimensionality associated with their spatial counterparts has opened up altogether new scientific possibilities in soliton research. Another reason is related to the response time of the nonlinearity. Unlike temporal optical solitons, spatial solitons have been realized by employing a variety of noninstantaneous nonlinearities, ranging from the nonlinearities in photorefractive materials and liquid crystals to the nonlinearities mediated by the thermal effect, thermophoresis and the gradient force in colloidal suspensions. Such a diversity of nonlinear effects has given rise to numerous soliton phenomena that could otherwise not be envisioned, because for decades scientists were of the mindset that solitons must strictly be the exact solutions of the cubic nonlinear Schrodinger equation as established for ideal Kerr nonlinear media. As such, the discoveries of optical spatial solitons in different systems and associated new phenomena have stimulated broad interest in soliton research. In particular, the study of incoherent solitons and discrete spatial solitons in optical periodic media not only led to advances in our understanding of fundamental processes in nonlinear optics and photonics, but also had a very important impact on a variety of other disciplines in nonlinear science. In this paper, we provide a brief overview of optical spatial solitons. This review will cover a variety of issues pertaining to self-trapped waves supported by different types of nonlinearities, as well as various families of spatial solitons such as optical lattice solitons and surface solitons. Recent developments in the area of optical spatial solitons, such as 3D light bullets, subwavelength solitons, self-trapping in soft condensed matter and spatial solitons in systems with parity-time symmetry will also be discussed briefly.