112 research outputs found
Coherent coupling between radio frequency, optical, and acoustic waves in piezo-optomechanical circuits
The interaction of optical and mechanical modes in nanoscale optomechanical
systems has been widely studied for applications ranging from sensing to
quantum information science. Here, we develop a platform for cavity
optomechanical circuits in which localized and interacting 1550 nm photons and
2.4 GHz phonons are combined with photonic and phononic waveguides. Working in
GaAs facilitates manipulation of the localized mechanical mode either with a
radio frequency field through the piezo-electric effect, or optically through
the strong photoelastic effect. We use this to demonstrate a novel acoustic
wave interference effect, analogous to coherent population trapping in atomic
systems, in which the coherent mechanical motion induced by the electrical
drive can be completely cancelled out by the optically-driven motion. The
ability to manipulate cavity optomechanical systems with equal facility through
either photonic or phononic channels enables new device and system
architectures for signal transduction between the optical, electrical, and
mechanical domains
Cauda equina entrapment in a pseudomeningocele after lumbar Schwannoma extirpation
Incidental or intentional durotomy causing cerebrospinal fluid (CSF) leakage, leading to the formation of a pseudomeningocele is a known complication in spinal surgery. Herniation of nerve roots into such a pseudomeningocele is very rare, but can occur up to years after initial durotomy and has been described to cause permanent neurologic deficit. However, cauda equina fiber herniation and entrapment into a pseudomeningocele has not been reported before. Here, we present a case of symptomatic transdural cauda equina herniation and incarceration into a pseudomeningocele, 3Â months after extirpation of a lumbar Schwannoma. A 59-year-old man, who previously underwent intradural Schwannoma extirpation presented 3Â months after surgery with back pain, sciatica and loss of bladder filling sensation caused by cauda equina fiber entrapment into a defect in the wall of a pseudomeningocele, diagnosed with magnetic resonance imaging. On re-operation, the pseudomeningocele was resected and the herniated and entrapped cauda fibers were released and replaced intradurally. The dura defect was closed and the patient recovered completely. In conclusion, CSF leakage can cause neurological deficit up to years after durotomy by transdural nerve root herniation and subsequent entrapment. Clinicians should be aware of the possibility of this potentially devastating complication. The present case also underlines the importance of meticulous dura closure in spinal surgery
Radiation damping optical enhancement in cold atoms
This work is licensed under the Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/Open Access journalThe typically tiny effect of radiation damping on a moving body can be amplified to a favorable extent by exploiting the sharp reflectivity slope at one edge of an optically induced stop-band in atoms loaded into an optical lattice. In this paper, this phenomenon is demonstrated for the periodically trapped and coherently driven cold 87Rb atoms, where radiation damping might be much larger than that anticipated in previous proposals and become comparable with radiation pressure. Such an enhancement could be observed even at speeds of only a few meters per second with less than 1.0% absorption, making radiation damping experimentally accessible
Nano-Opto-Electro-Mechanical Systems
A new class of hybrid systems that couple optical, electrical and mechanical
degrees of freedom in nanoscale devices is under development in laboratories
worldwide. These nano-opto-electro-mechanical systems (NOEMS) offer
unprecedented opportunities to dynamically control the flow of light in
nanophotonic structures, at high speed and low power consumption. Drawing on
conceptual and technological advances from cavity optomechanics, they also bear
the potential for highly efficient, low-noise transducers between microwave and
optical signals, both in the classical and quantum domains. This Progress
Article discusses the fundamental physical limits of NOEMS, reviews the recent
progress in their implementation, and suggests potential avenues for further
developments in this field.Comment: 27 pages, 3 figures, 2 boxe
A rare tonsillar disease
A 16 year old woman with Tangier disease in palatine tonsils is reported. She has recurrent sore throat. In physical examination the palatine tonsils are hypertrophied and has very yellowish points. The facial skin is yellowish but the skin of another areas of body is normal. After tonsillectomy the pathologist report Tangier disease in palatine tonsil
- âŠ