An Efficient Algorithm to Determine Equivalence of Pipelined Dependency Graphs for Their Simplification

　依存性グラフに基づいた非同期式パイプライン制御回路の設計方法が提案されている．この設計法の最終段階においては，依存性グラフと縮小した依存性グラフの等価性を何度も繰返し判定することにより，簡単化した依存性グラフが得られる．しかし，この判定には多数の状態をもつオートマトンを扱うため，その計算量は極めて大きい．本論文では，この等価性判定のための新たな効率的なアルゴリズムを提案する．まず，基本操作の実行順序の半順序をコンパクトに表現するために，基本操作直結因果関係グラフ O˙ を定義する．次に，分 岐系列ごとに O˙ の高々二つの部分グラフが一致するとき，かつそのときに限り，二つの依存性グラフが等価であることを証明する．更に，等価性の判定に必要な分岐系列のサイズと数が有限であることを証明する．最後に，上述の原理を用いたアルゴリズムの計算量が従来法に比べて大幅に小さいことを示す

Beat-frequency-resolved two-dimensional electronic spectroscopy: disentangling vibrational coherences in artificial fluorescent proteins with sub-10-fs visible laser pulses

We perform a beat-frequency-resolved analysis for two-dimensional electronic spectroscopy using a high-speed and stable 2D electronic spectrometer and few-cycle visible laser pulses to disentangle the vibrational coherences in an artificial fluorescent protein. We develop a highly stable ultrashort light source that generates 5.3-fs visible pulses with a pulse energy of 4.7 uJ at a repetition rate of 10 kHz using multi-plate pulse compression and laser filamentation in a gas cell. The above-5.3-fs laser pulses together with a high-speed multichannel detector enable us to measure a series of 2D electronic spectra, which are resolved in terms of beat frequency related to vibrational coherence. We successfully extract the discrete vibrational peaks behind the inhomogeneous broadening in the absorption spectra and the vibrational quantum beats of the excited electronic state behind the strong stationary signal in the typical 2D electronic spectra

Direct Observation of the Protonation States in the Mutant Green Fluorescent Protein

Neutron crystallography has been used to elucidate the protonation states for the enhanced green fluorescent protein, which has revolutionized the imaging technologies. The structure has a deprotonated hydroxyl group in the fluorescent chromophore. Also, the protonation states of His148 and Thr203, as well as the orientation of a critical water molecule in direct contact with the chromophore, could be determined. The results demonstrate that the deprotonated hydroxyl group in the chromophore and the nitrogen atom ND1 in His148 are charged negatively and positively, respectively, forming an ion pair. The position of the two deuterium atoms in the critical water molecule appears to be displaced slightly toward the acceptor oxygen atoms according to their omit maps. This displacement implies the formation of an intriguing electrostatic potential realized inside the protein. Our findings provide new insights into strategy for future protein design with developments for quantum chemical calculations

Direct Observation of the Protonation States in the Mutant Green Fluorescent Protein

Neutron crystallography has been used to elucidate the protonationstates for the enhanced green fluorescent protein, which has revolutionized imagingtechnologies. The structure has a deprotonated hydroxyl group in the fluorescentchromophore. Also, the protonation states of His148 and Thr203, as well as theorientation of a critical water molecule in direct contact with the chromophore, couldbe determined. The results demonstrate that the deprotonated hydroxyl group in thechromophore and the nitrogen atom ND1 in His148 are charged negatively andpositively, respectively, forming an ion pair. The position of the two deuterium atomsin the critical water molecule appears to be displaced slightly toward the acceptoroxygen atoms according to their omit maps. This displacement implies the formationof an intriguing electrostatic potential realized inside of the protein. Our findingsprovide new insights into future protein design strategies along with developments inquantum chemical calculations