An Intramural, Tension-modulating Reflex in the Rat Caudal Artery

Electrical field stimulation (EES) of preconstricted arteries causes relaxation. This relaxation is of either neuronal, vascular smooth muscle, and/or endothelial origins. We have shown that EFS-induced relaxation of intact, phenylephrine (PE) preconstricted rat tail artery (RTA) rings was dependent upon the extracellular concentration of Ca++. Inhibiting either nitric oxide (NO) synthesis with N-nitro-L-arginine methyl ester (L-NAME), or the synthesis of cyclic guanosine monophosphate (cGMP) with methylene blue (MB) reduced the EFS-induced relaxation. In addition, inhibition of KCa++-dependent hyperpolarization with tetraethylammonium (TEA), or KATP hyperpolarization with BaCl2 or glibenclamide also reduced EFS-induced relaxation. L-arginine reversed the effect of L-NAME. When either MB and KCl, L-NAME and KCl, or L-NAME and BaCl2 were used, the EFS-induced relaxation was completely inhibited. The EFS-induced relaxation was not inhibited by tetrodotoxin, a voltage-operated Na+ channel antagonist. EFS-induced relaxation was partially inhibited by endothelium denuding. The remaining EFS-induced relaxation in the denuded RTA was inhibited by BaCl2 and KCl. EFS-induced relaxation in the intact, KCl preconstricted RTA was inhibited by L-NAME and MB. Effluent from freshly isolated, bovine aortic endothelial cells (BAEC) exposed to EES relaxed denuded RTA and could be blocked by L-NAME, MB, KCl, and TEA. L-arginine reversed the effect of L-NAME as in the ring experiments. EFS-induced relaxation of intact, pressurized, and PE preconstricted RTA was frequency and voltage-dependent, and inhibited by either L-NAME, BaCl2, or the voltage-operated Ca++ channel antagonist diltiazem. As in all the other studies, L-arginine reversed the effect of L-NAME. Membrane potential recordings of EFS-induced relaxation showed a mean membrane hyperpolarization of -20 mV simultaneously with relaxation. A positive correlation was shown to exist between the initial level of tone and the EFS-induced relaxation. It can be concluded that the vascular smooth muscle contains an endogenous hyperpolarization mechanism that regulates initial changes in arterial tone. Higher arterial tension causes the release of NO and another hyperpolarization factor from the endothelium which function to further regulate arterial tone

Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae

We systematically surveyed period variations of superhumps in SU UMa-type dwarf novae based on newly obtained data and past publications. In many systems, the evolution of superhump period are found to be composed of three distinct stages: early evolutionary stage with a longer superhump period, middle stage with systematically varying periods, final stage with a shorter, stable superhump period. During the middle stage, many systems with superhump periods less than 0.08 d show positive period derivatives. Contrary to the earlier claim, we found no clear evidence for variation of period derivatives between superoutburst of the same object. We present an interpretation that the lengthening of the superhump period is a result of outward propagation of the eccentricity wave and is limited by the radius near the tidal truncation. We interpret that late stage superhumps are rejuvenized excitation of 3:1 resonance when the superhumps in the outer disk is effectively quenched. Many of WZ Sge-type dwarf novae showed long-enduring superhumps during the post-superoutburst stage having periods longer than those during the main superoutburst. The period derivatives in WZ Sge-type dwarf novae are found to be strongly correlated with the fractional superhump excess, or consequently, mass ratio. WZ Sge-type dwarf novae with a long-lasting rebrightening or with multiple rebrightenings tend to have smaller period derivatives and are excellent candidate for the systems around or after the period minimum of evolution of cataclysmic variables (abridged).Comment: 239 pages, 225 figures, PASJ accepte

LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie

Colonial Archives and the Arts of Governance

Anthropologists engaged inpost-colonial studies are increasingly adoptingan historical perspective and using archives. Yet their archival activity tends to remain morean extractive than an ethnographic one.Documents are thus still invokedpiecemeal to confirm the colonial invention ofcertain practices or to underscore culturalclaims, silent. Yet such mining of the content of government commissions,reports, and other archival sources rarely paysattention to their peculiar placement and form .Scholars need to move fromarchive-as-source to archive-as-subject. Thisarticle, using document production in the DutchEast Indies as an illustration, argues thatscholars should view archives not as sites ofknowledge retrieval, but of knowledgeproduction, as monuments of states as well assites of state ethnography. This requires asustained engagement with archives as culturalagents of ``fact'' production, of taxonomies inthe making, and of state authority. What constitutes thearchive, what form it takes, and what systemsof classification and epistemology signal atspecific times are (and reflect) critical featuresof colonial politics and state power. The archive was the supreme technology of thelate nineteenth-century imperial state, arepository of codified beliefs that clustered(and bore witness to) connections betweensecrecy, the law, and power.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41825/1/10502_2004_Article_5096461.pd