다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

J. Appl. Cryst.の発刊に際して

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

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The Observation of Gravitational Waves from a Binary Black Hole Merger

We review the field of cavity optomechanics, which explores the interaction between electromagnetic radiation and nano- or micromechanical motion This review covers the basics of optical cavities and mechanical resonators, their mutual optomechanical interaction mediated by the radiation pressure force, the large variety of experimental systems which exhibit this interaction, optical measurements of mechanical motion, dynamical backaction amplification and cooling, nonlinear dynamics, multimode optomechanics, and proposals for future cavity quantum optomechanics experiments In addition, we describe the perspectives for fundamental quantum physics and for possible applications of optomechanical devices

Cavity Optomechanics

Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Bose-Einstein condensation in a gas of sodium atoms

An optical parameter oscillator system is proposed for use in a continuous wave pump laser system having a single-frequency pump source. The system comprises a single-resonance resonator having a nonlinear medium to produce a first and second parametrically generated wave in response to the pump wave from the single-frequency pump source. The system includes means for controlling the cavity length of the resonator, means for controlling the pump frequency of the pump source and means for controlling the temperature of the nonlinear medium. The system provides for a reliable singly-resonant optical parametric oscillator capable of emitting laser light with high spectral purity and frequency stability over a wide spectral range and is resistant to mode hopping.

Tunable optical parametric oscillator

We demonstrate a doubly resonant optical para- metric oscillator that operated on a single mode pair for 18 h without mode hops, and whose output frequencies can be tuned by almost 10 GHz without mode hops by the tuning of the pump laser frequency. The tuning range is limited by the available pump tuning range. Active stabilization is used that minimizes the detuning of the parametrically generated waves with respect to the DRO cavity resonances. Absolute fre- quency stabilization of the idler wave is achieved by locking its frequency to an ultra-stable cryogenic reference resonator, using the pump laser frequency as control parameter. The fre- quency instability reached is below the 1-kHz level.

http://www.spektron.de/Publikationen/1998/APB66_733.pdf

Long-term stable operation and absolute frequency stabilization of a doubly resonant parametric oscillator

It has been suggested that space-time might undergo fluctuations because of its intrinsic quantum nature. These fluctuations would pose a fundamental limit to the ability of measuring distances with arbitrary precision, beyond any limitations due to standard quantum mechanics. Laser interferometers have recently been proposed as being suited for a search for the existence of space-time fluctuations. Here we present results of a search for space-time fluctuations of very low fluctuation frequencies, in the range from 1 \ensuremath{\mu}Hz to 0.5 Hz. Rigid optical interferometers made out of sapphire and operated at cryogenic temperature were used. We find an upper limit of $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}{\mathrm{Hz}}^{\ensuremath{-}1}$ for the normalized distance noise spectral density at 6 \ensuremath{\mu}Hz, and of $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}28}{\mathrm{Hz}}^{\ensuremath{-}1}$ above 5 mHz, and establish an experimental limit for the parameter of a recently proposed random-walk hypothesis.

Experimental limits for low-frequency space-time fluctuations from ultrastable optical resonators

We present a novel approach for the generation of highly frequency-stable, widely tunable, single-frequency cw UV light that is suitable for high-resolution spectroscopy. Sum-frequency generation (SFG) of two solid-state sources with a single cavity resonant for both fundamental waves is employed. Using a highly stable, narrow-linewidth frequency-doubled cw Nd:YAG laser as a master laser and slaving to it the SFG cavity and the other fundamental wave from a Ti:sapphire laser, we generate UV radiation of 33-mW output power around 313 nm. Alternatively, we use a diode laser instead of the Ti:sapphire laser and produce an output power of 2.1 mW at 313 nm. With both setups we obtain a continuous tunability of >15 GHz, short-term frequency fluctuations in the submegahertz range, a long-term frequency drift below 100 MHz/h, and stable operation for several hours. The theory of optimized doubly resonant SFG is also given.

http://exphy.uni-duesseldorf.de/Publikationen/2002/ApplOptics_Schnitzler_2002.pdf

All-solid-state tunable continuous-wave ultraviolet source with high spectral purity and frequency stability

We have produced large samples of ultracold (<20 mK) ArH+, ArD+, N2H+, N2D+, H3+, D3+, D2+, H2D+ and D2D+ molecular ions, by sympathetic cooling and crystallization via laser-cooled Be+ ions in a linear radio-frequency trap. As technique, we used chemical reactions with sympathetically cooled noble gas atomic ions or N2+ and O2+ molecular ions. These ultracold molecules are interesting targets for high-precision measurements in fundamental physics and may open new routes for the study of state-selective chemical reactions relevant to interstellar chemistry.

http://www.exphy.uni-duesseldorf.de/Publikationen/2006/Roth%20et%20al%20Molecular%20ion%20production%20JPhysB2006.pdf

Stephan Schiller

Papers

Tunable optical parametric oscillator

Long-term stable operation and absolute frequency stabilization of a doubly resonant parametric oscillator

Experimental limits for low-frequency space-time fluctuations from ultrastable optical resonators

All-solid-state tunable continuous-wave ultraviolet source with high spectral purity and frequency stability

Production of ultracold diatomic and triatomic molecular ions of spectroscopic and astrophysical interest