Frequency-resolved optical gating (FROG) is a technique to measure ultrashort laser pulses that optically constructs a spectrogram of a laser pulse. A two-dimensional (2-D) phase retrieval algorithm is used to extract the intensity and phase of a pulse from its spectrogram. We have improved a recently presented principal component generalized projections algorithm (PCGPA) making it easier to im...

The possibility of acetylation of nucleic acids was examined. Although protein is actively acetylated with [1-(14)C]acetic acid in rat liver systems in vivo and in vitro and in a frog liver system in vivo, nucleic acids are not acetylated under these conditions; nucleic acids purified from these sources are without radioactivity. Requirements for acetylation in vitro of protein in rat liver are...

We analyze experimentally the sensitivity of second-harmonic generation frequencyresolved optical gating (SHG-FROG) for the complete intensity and phase characterization of both a sinusoidal beat signal and a train of 1.3 ps pulses at a repetition rate of 160GHz at 1550nm. Using a commercially-available optical spectrum analyzer in the SHG-FROG setup, incident pulses with energies of only 125fJ...

Ultrashort-pulse-characterization techniques generally require instantaneously responding media. We show that this is not the case for frequency-resolved optical gating (FROG). We include, as an example, the noninstantaneous Raman response of fused silica, which can cause errors in the retrieved pulse width of as much as 8% for a 25-fs pulse in polarization-gate FROG. We present a modified puls...

We use the algorithmic method of generalized projections (GP's) to retrieve the intensity and phase of an ultrashort laser pulse from the experimental trace in frequency-resolved optical gating (FROG). Using simulations, we show that the use of GP's improves significantly the convergence properties of the algorithm over the basic FROG algorithm. In experimental measurements, the GP-based algori...

Consider a Poisson process on R with intensity f where 0 ≤ f(x) <∞ for x ≥ 0 and f(x) = 0 for x < 0. The “points” of the process represent sleeping frogs. In addition, there is one active frog initially located at the origin. At time t = 0 this frog begins performing Brownian motion with leftward drift λ (i.e. its motion is a random process of the form Bt − λt). Any time an active frog arrives ...

Synapses with a cleft with ' thickened' membranes and presynaptic vesicles and mitochondria occur commonly throughout the grey matter of the spinal cord of goldfish, frog and various mammals studied. Such synapses are generally thought to have a chemical mode of transmission. The absence or rare occurrence of presynaptic neurofilaments in fish and frog accounts for the failure to detect boutons...

Shuffled frog leaping algorithm is a new kind of swarm intelligence optimization algorithm. Due to the local search of the basic shuffled frog leaping algorithm which is the only by the worst frog to search and jump, searching ability of which was limited; therefore it had the low precision, slow convergence speed and easy premature convergence etc. Therefore, in order to enhance the ability of...