Internal chemical communication within flatworms

An understanding of reproductive function is important for control of parasitic helminths. In cestodes and trematodes virtually nothing is known about regulatory and coordinating mechanisms that control maturation, gamete formation, egg production, and related processes. Neurosecretory neurons have been reported in various species but specific modes of action of neurohormones have yet to be demonstrated. The role of ecdysone is being investigated.     

Adverse reactions to radiopharmaceuticals

This review covers the side effects and adverse reactions to radiopharmaceuticals that were reported in the literature over the past 25 years. The information published prior to 1970 is sporadic, but due to the increased utilization of nuclear medicine procedures and the recognition that radiopharmaceuticals may have pharmacologic side effects, a registry has existed since 1971 to tabulate information on such effects. This survey is medical, rather than pharmaceutical in emphasis and so the adverse reactions are classified according to the target-organ systems involved rather than according to the specific radionuclides or to pharmaceuticals. If any of the radiopharmaceuticals of present or past use are not mentioned in this review, it is because no reports on their side effects were retrived by us. Hopefully, the organized registry system suggested by the Society of Nuclear Medicine (SNM) will enable a more complete recording of side effects from radiopharmaceuticals in the future.     

Evidence for a short-range sex pheromone in female Maladera matrida beetle

Laboratory studies with live and frozen Maladera matrida female and male beetles showed that males were attracted to chemical substances emanating from the females at dusk. Beetles exhibited sexual activity (including mating) at dusk towards frozen females but not towards frozen males. Frozen females that had been extracted with methanol together with either hexane or dichloromethane or with a mixture of all three solvents did not elicit male sexual activity. Activity was fully restored when a concentrate of the extract was applied to the previously extracted frozen females. Males also responded with vigorous sexual activity to frozen males to which female extract had been applied. Deterrent chemicals appear to be absent from the male body. Males exposed to females that had been frozen during the morning displayed weak sexual activity, indicating that females lack active semiochemicals. Differences between dusk and morning extracts were found with respect to more than 20 compounds, some of which were present in much higher concentrations at dusk than in the morning, while others were not detected in the morning extract. The active component(s) of the short-range sex pheromone of female M. matrida is (are) presumably to be found among these compounds.     

Molecular simulation for adsorption of chlorinated hydrocarbon in zeolites

Equilibrium and isosteric heat of adsorption for the system of chloroform and USY-type zeolite were studied. The USY-type zeolite (PQ Co., SiO₂/Al₂O₃=70) was used both as a pure crystalline powder and as granulated particles with binder. Chloroform was reagent grade. The adsorption equilibria were measured using a gravimetric method and were expressed as isotherms. A chromatographic method (i.e. pulse response of chloroform through the USY column with helium carrier) was used to get the initial slope of the isotherms. In the simulation, the GCMC method was used to calculate amounts adsorbed for various conditions. FF parameters were confidently applied. And modified structure model was effective for simulation. This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between August 19 and 21, 1999.     

FISCHERPLOTS: An Excel spreadsheet for computing Fischer plots of accommodation change in cyclic carbonate successions in both the time and depth domains

Fischer plots are plots of accommodation (derived by calculating cumulative departure from mean cycle thickness) versus cycle number or stratigraphic distance (proxies for time), for cyclic carbonate platforms. Although many workers have derived programs to do this, there are currently no published, easily accessible programs that utilize Excel. In this paper, we present an Excel-based spreadsheet program for Fischer plots, illustrate how the data are input, and how the resulting plots may be interpreted. The plots can be used to derive periods of increased accommodation, shown on the plots as a rising limb (which commonly matches times of more open marine, subtidal parasequence development). Times of decreased accommodation, shown on the plots as a falling limb, generally are coincident with thin, shallow, peritidal parasequences.     

A novel, wideband, lithium niobate electrooptic modulator

A set of floating electrodes and a relatively thick buffer layer of low-dielectric constant is interspaced between the coplanar RF transmission line and the LiNbO₃ substrate containing the optical wave-guide structure. The composite structure is designed to feature a 50-Ω characteristic impedance, to have an effective dielectric constant equal to that of the optical wave for close velocity match, and to have a 3 dB bandwidth of 40 GHz. The purpose of the floating electrodes is to optimize the modulation sensitivity resulting in an improvement of about 6 dB. As a result, the RF power required for full modulation is lower than heretofore reported changing over the range from below 2 GHz to 20 GHz, from 44 mW to less than 70 mW. The close agreement between the theoretical and experimental values of the design parameters demonstrates the usefulness of the quasistatic assumption in the analysis of the composite structure     

Analyzing UV/Vis/NIR spectra with the single-layer model—Sputtered SnS thin films I: Space-time dependencies

Exact, contact-free and non-destructive, optical analysis of semiconducting layers, are advantageous for thin film solar cell applications. A non-numerical theoretical model has been developed to extract approximation-free optical and electrical data from UV/Vis/NIR spectra. Special focus has been set on single layers; an adequate single-layer model is provided. Complex parameter evaluation is possible.This exact data acquisition model provides deeper insights in the process-parameter dependencies of pulsed direct current and radio frequency sputtered, opaque tin-sulphide thin films upon glass substrates. They have been analysed with respect to space-time dependencies of the sputter process. Therefore, sputter-depositions have been examined, referring to positions upon the substrate, r, target-substrate distances, d_TarSub, and sputter durations, t_Sp. Theoretical sputter-concepts were proved and enhanced. Results were compared with those of the well-known Keradec/Swanepoel model. The necessity of taking both spectra—transmission and reflection spectra—into account has been shown.A non-contact, optical conductivity measurement possibility by use of UV/Vis/NIR spectroscopy has been provided. Optically evaluated conductivities, σ_L, were compared with electrically taken values, by use of a four-tip measurement system.     

OC-12c digital crossconnect switch

This paper describes the design of an OC-12c crossconnect switch developed for the VISTAnet research testbed and installed in GTE's Parkwood central office. The crossconnect switch has been designed as SONET-compliant line terminating equipment and provides switching for up to 16 OC-12c signals. The system consists of up to eight trunk interface cards with two bidirectional OC-12 ports, a synchronous switch card, and a control module with craft interface to provide service monitoring, provisioning, and maintenance functions. Several novel concepts, such as distributed power systems and integrated electro-optical backplane connectors, were incorporated in the design of the crossconnect. The system was implemented using a judicious mix of GaAs, ECL, and CMOS technology. Particular attention was given to equipping the crossconnect with extensive diagnostic capability to facilitate network performance monitoring. Graphic user interface technology provides an easy interface for either operator or maintenance personnel