The organization of this chapter follows the development of the shell of Nautilus from the formation of the cicatrix through hatching. The description of the cicatrix is based mainly on study of one embryo of N. belauensis in early organogenesis, in which periostracum and crystals of aragonite were just beginning to form (Arnold and Carlson, 1986). Development through the one-chambered stage is based largely on a second embryo of N. belauensis, in which the first chamber was in the process of forming, but a calcified septum had not yet developed (Arnold and Carlson, 1986).

Optical self seeding feedback techniques can be used to improve the noise characteristics of passively mode-locked laser diodes. External cavities such as fiber optic cables can increase the memory of the phase and subsequently improve the timing jitter. In this work, an improved optical feedback architecture is proposed using an optical fiber loop delay as a cavity extension of the mode-locked laser. We investigate the effect of the noise reduction as a function of the loop length and feedback power. The well known composite cavity technique is also implemented for suppressing supermode noise artifacts presented due to harmonic mode locking effects. Using this method, we achieve a record low radio frequency linewidth of 192 Hz for any high frequency (>1 GHz) passively mode-locked laser to date (to the best of the authors' knowledge), making it promising for the development of high frequency optoelectronic oscillators.

We present an ultralow RF linewidth (192 Hz) and subpicosecond phase noise (260 fs) using a passively mode-locked quantum-well laser with feedback via a dual optical fiber loop.

The monolithic integration of four 10 GHz multi-colored mode-locked lasers with a 4×1 MMI, a SOA and an electroabsorption modulator has been demonstrated. The lasers produce 2.49 ps Sech2-pulses with TBP of 0.389.

In the past 15 years, there has been tremendous progress in our understanding of many aspects of Nautilus biology. This progress is due in part to an increase in the number of investigators now interested in this genus, but is largely due to successful collection and aquarium culture techniques (Carlson, 1979; Mikami et al., 1976) (see also Chapter 35). When I began writing this chapter, I jokingly offered to leave four blank pages to cover what was then known about the embryonic development of Nautilus. That same afternoon, I opened some neglected egg capsules and found the first living Nautilus embryo (Arnold and Carlson, 1986). What follows is more a progress report than an attempt to present definitive data and meaningful interpretations.

A new efficient technique that models the behavior of pulsed optical beams in homogenous medium, metallic and dielectric waveguides, is introduced and verified using both linear nondispersive and dispersive examples that have analytical predictions. Excellent accuracy results have been observed. The method is called time-domain beam-propagation method (TD-BPM) because it is similar to the classical continuous-wave BPM with additional time dependence. The explicit finite difference and the Du Fort-Frankel approaches were used to discretize the TD-BPM equation. Comparisons between these techniques are also given with the application of the perfectly matched layers as spatial boundary conditions to the Du Fort-Frankel. Then the TD-BPM was successfully applied to model a two-dimensional dielectric Y-junction. It is concluded that the new technique is more efficient than the traditional finite-difference TD method, especially in modeling large optical devices.

We implement the Du Fort–Frankel modified explicit finite-difference beam propagation method (MEFD) to model three-dimensional optical devices using parallel computers. Accuracy comparisons with other parallel FD–BPMs are made, and we observe that the MEFD is very accurate and efficient. The parallel implementation of MEFD shows a large run-time computer savings compared to other parallel FD–BPM algorithms. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 24: 179–182, 2000.

The beam Propagation Method (BPM) is a well-established and widely used numerical method for computing the propagation of waves in the paraxial approximation. It is generally employed for CW waves to track the spatial evolution of the complex envelope of the wave in temporal steady-state conditions. The application to nonlinear problems, such as soliton propagation in a guided-wave environment or pulse propagation in a saturating amplifier or absorber, requires the explicit time dependence to be evaluated under nonstationary conditions. For this purpose, we have developed a time-domain version of the explicit parallel-processing BPM (TD-BPM) (1). The incorporation of time dependence in the BPM is achieved by representing field quantities in the form ψ(x ,t )= {Ψ(x ,t ) exp(i(βz − ωt )) +Ψ ∗(x ,t ) exp(−i(βz − ωt))}

A time-domain simulator of integrated optical structures containing second-order nonlinearities is presented. The simulation algorithm is based on nonlinear wave equations representing the propagating fields and is solved using the finite-difference time-domain method. The simulation results for a continuous-wave operation are compared with beam propagation method simulations showing excellent agreement for the particular examples considered. Because the proposed algorithm does not suffer from the inaccuracies associated with the paraxial approximation, it should find application in a wide range of device structures and in the analysis of short-pulse propagation in second-order nonlinear devices.

A new technique to model the behavior of pulsed optical beams in waveguides is proposed and analyzed. The technique is an extension of the traditional continuous-wave beam propagation method (BPNI) to include time dependence, therefore called the time-domain BPM (TD-BPM). The method was tested using different waveguide examples and it is concluded that the technique is simple and accurate. Compared with the finite-difference TD method, the new TD-BPM is more efficient in terms of computer memory and execution time especially for large optical devices.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A new highly efficient MICROCOS technology (Microwave-assisted Combinatorial Synthesis) for generating combinatorial libraries is described. The technology is applied to the high throughput, automated, one-step, parallel synthesis of diverse substituted pyridines using the Hantzsch synthesis. The advantages of microwave-assisted chemistry for combinatorial synthesis include a broad range of available chemistries, simple reaction setup and product recovery readily amenable to automation, extremely short reaction times, and high product yields.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSynthesis of Water-Soluble Paclitaxel Derivatives by Enzymatic AcylationYuri L. Khmelnitsky, Cheryl Budde, J. Michael Arnold, Alexander Usyatinsky, Douglas S. Clark, and Jonathan S. DordickView Author Information EnzyMed, Inc., 2501 Crosspark Road Oakdale Research Park, Iowa City, Iowa 52242 Department of Chemical Engineering University of California Berkeley, California 94720 Department of Chemical and Biochemical Engineering University of Iowa, Iowa City, Iowa 52242 Cite this: J. Am. Chem. Soc. 1997, 119, 47, 11554–11555Publication Date (Web):November 26, 1997Publication History Received3 September 1997Published online26 November 1997Published inissue 1 November 1997https://pubs.acs.org/doi/10.1021/ja973103zhttps://doi.org/10.1021/ja973103zrapid-communicationACS PublicationsCopyright © 1997 American Chemical SocietyRequest reuse permissionsArticle Views1176Altmetric-Citations77LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Antineoplastic agents,Organic reactions,Peptides and proteins,Post-translational modification,Reaction products Get e-Alerts

In this work, we present a simple efficient numerical solution for the three-dimensional coupled wave equations containing a second-order nonlinearity, using an explicit finite difference beam propagation method (EFD BPM). The linear EFD-BPM is known to be very efficient and to gain large speed up when implemented on parallel computers. The new nonlinear version of the EFD-BPM has the same features of the linear counterpart in using two separate computational windows, one for the fundamental field and the other for the second-harmonic field. We demonstrate the implementation and discuss the application of this method to a nonlinear rib waveguide using the quasi-phase-matching technique.

The second-order cascade effect is a very promising means of generating large intensity-dependent self-induced phase changes in an optical field propagating in a waveguide [1,2,3]. In practice this phenomenon must be implemented in a waveguide environment with quasi-phase-matching (QPM), but most theoretical analysis has used 1-dimensional (plane-wave) approximations along with conventional phase-matching. While 1-dimensional models do exhibit the dominant physics, at least under CW excitation conditions, they are incapable of representing a variety of effects which should be considered in actually designing an optimal device, such as the effects of higher-order guided modes and radiation modes which might be excited at the second-harmonic, radiation due to scattering from the QPM grating, and many others.