Effects of Prostaglandins on Cyclic AMP Content of Superior Cervical Ganglia of the Cow and Cat

Dopamine and prostaglandin E2 (PGE2) produced time- and concentration-dependent increases in cyclic AMP levels of bovine superior cervical ganglia (SCG). Maximal increases in cyclic AMP levels were produced within 1 min by PGE2, compared to l0 min for dopamine. Dopamine and PGE2 were synergistic in their effects on cyclic AMP levels. By contrast, prostaglandin F2a had no effect on cyclic AMP levels. In the feline SCG, the modest increases in cyclic AMP levels produced by dopamine were not statistically significant. Neither PGE2 nor PGF2a increased cyclic AMP levels in feline SCG. Interpretation: Dopamine increased cyclic AMP synthesis in bovine SCG by stimulating a dopamine receptor-adenylate cyclase complex. PGE2 increased cyclic AMP synthesis in bovine SCG by stimulating an adenylate cyclase complex. This complex may or may not be the same one stimulated by dopamine. The stimulatory effect of PGE2 is specific for prostaglandins of the E series, since PGF2a had no effect. Neither dopamine nor PGE2 stimulated cyclic AMP synthesis in the feline SCG because this ganglion lacks significant adenylate cyclase activity

Magnetically coupled signal isolator

A current determiner having an output at which representations of input currents are provided having an input conductor for the input current and a current sensor supported on a substrate electrically isolated from one another but with the sensor positioned in the magnetic fields arising about the input conductor due to any input currents. The sensor extends along the substrate in a direction primarily perpendicular to the extent of the input conductor and is formed of at least a pair of thin-film ferromagnetic layers separated by a non-magnetic conductive layer. The sensor can be electrically connected to electronic circuitry formed in the substrate including a nonlinearity adaptation circuit to provide representations of the input currents of increased accuracy despite nonlinearities in the current sensor, and can include further current sensors in bridge circuits

Magnetic current sensor

A current determiner having an output at which representations of input currents are provided having an input conductor for the input current and a current sensor supported on a substrate electrically isolated from one another but with the sensor positioned in the magnetic fields arising about the input conductor due to any input currents. The sensor extends along the substrate in a direction primarily perpendicular to the extent of the input conductor and is formed of at least a pair of thin-film ferromagnetic layers separated by a non-magnetic conductive layer. The sensor can be electrically connected to a electronic circuitry formed in the substrate including a nonlinearity adaptation circuit to provide representations of the input currents of increased accuracy despite nonlinearities in the current sensor, and can include further current sensors in bridge circuits

Hail Britannia?: Institutional Investor Behavior Under Limited Regulation

A central puzzle in understanding the governance of large American public firms is why most institutional shareholders are passive. Why would they rather sell than fight? Until recently, the Berle-Means paradigm – the belief that separation of ownership and control naturally characterizes the modern corporation – reigned supreme. Shareholder passivity was seen as an inevitable result of the scale of modern industrial enterprise and of the collective action problems that face shareholders, each of whom owns only a small fraction of a large firm\u27s shares. A paradigm shift may be in the making, however. Rival hypotheses have recently been offered to explain shareholder passivity. According to a new political theory of corporate governance, financial institutions in the United States are not naturally apathetic but rather have been regulated into submission by legal rules that – sometimes intentionally, sometimes inadvertently – hobble American institutions and raise the costs of participation in corporate governance

The Use of 2,4-Dinitrophenylhydrazine Derivatives of Ovarian Ketosteroids in Steroid Analysis

This paper reports the development of a technically simple analytical technique for the characterization and quantitative determination of ovarian ketosteroids employing derivative formation with 2,4-dinitrophenylhydrazine (2,4-DNP), separation by thin-layer chromatography (TLC), and quantitative determination by spectrophotometry. The chemical identities of the derivatives were established by nitrogen analysis. The melting point, chromatographic mobilities of the free steroids and their derivatives on silica gel G in three systems, wavelength of maximum absorption in chloroform and ethanol, and molar absorption coefficient are reported for the 2,4-DNP derivatives of ovarian ketosteroids. The relationship between the absorption maximum in chloroform and the chemical structure of the derivatives has been analyzed

Microparticle image velocimetry approach to flow measurements in isolated contracting lymphatic vessels

We describe the development of an optical flow visualization method for resolving the flow velocity vector field in lymphatic vessels, in vitro. The aim is to develop an experimental protocol for accurately estimating flow parameters, such as flow rate and shear stresses, with high spatial and temporal resolution. Previous studies in situ have relied on lymphocytes as tracers, but their low density resulted in a reduced spatial resolution whereas the assumption that the flow was fully developed in order to determine the flow parameters of interest may not be valid, especially in the vicinity of the valves, where the flow is undoubtedly more complex. To overcome these issues, we have applied the time-resolved micro-Particle Image Velocimetry technique, a well-established method that can provide increased spatial and temporal resolution that this transient flow demands. To that end, we have developed a custom light source, utilizing high-power light-emitting diodes, and associated control and image processing software. This manuscript reports the performance of the system and the results of a series of preliminary experiments performed on vessels isolated from rat mesenteries, demonstrating, for the first time, the successful application of the micro-PIV technique in these vessels

Beyond Documentation: 3D Data in Archaeology

As the costs associated with the collection of 3D data continue to plummet, there is little doubt that the number of available archaeology-related 3D datasets will increase dramatically in the coming decade. While our analytical procedures continue to evolve as new applications are contemplated, analyses of 3D data are increasing in frequency within the archaeological literature. In this article, we seek to provide a brief overview of a few examples from our own research and explore some possibilities that may add value to existing collections. In the following pages, we discuss some of the ways that 3D data have been used in studies of morphometrics, public archaeology, excavation, and comparative endeavors