932 resultados para Godfrey, of Bouillon, ca. 1060-1100


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Mode of access: Internet.

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Includes bibliographical references.

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Mode of access: Internet.

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"Gesta Heinrici VI. versibus celebrata ... quin revera Gotifredo tribuendi sint vix dubito."--Ex praefatione Waitzil.

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The Glossar which forms v. 3-4 has the special title "Sprachschatz der angelsächsischen Dichter."

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Vol. 4 has imprint: London, Printed for H. M. Stationery off., by Eyre and Spottiswoode.

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Includes bibliographical references (p. [208]-211) and indexes.

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Tracking the movement of migratory freshwater fish is essential to those invested in rebuilding declining fish populations. Using strontium isotopic signatures to match calcified fish tissues to streams where fish spawn is a useful method of tracking migratory fish where physical tracking methods such as radio, acoustic, or external tags, have proven unsuccessful. In this study, we develop tools to practice this method of tracking fish in Lake Roosevelt and its upstream tributaries in Washington State by analyzing the elemental concentrations and 87Sr/86Sr ratios of water samples, and mussel shell samples. This study evaluates whether mussel shells act as an appropriate proxy for water chemistry by comparing the 87Sr/86Sr isotope ratios of water samples to the 87Sr/86Sr isotope ratios of mussel shells sampled from the same, or nearby, locations. We compare concentrations of Ba, Ca, Cd, Cu, Fe, Mg, Pb, Sr, and U in the water and mussel shell samples to determine the feasibility of using mussel shells as a proxy for water chemistry. If it is determined that the concentrations of these elements in mussel shells reflect that of the surrounding water composition, the elemental composition of mussel shells can be compared to that of calcified tissues in fish, such as otoliths, to infer the location of the natal stream. We report analyses of water and mussel shell samples collected from Lake Roosevelt, Sanpoil River, Spokane River, Colville River, Kettle River, Pend Oreille River, Kootenay River, and Columbia River in Washington State. Each of these rivers is a tributary to Lake Roosevelt, and each flows through different geologic units. We hypothesize that the differences in the rock units of each stream’s watershed are reflected in the elemental concentrations and strontium isotopic ratios of water in each stream and in the lake. We also hypothesize that the composition of the mussel shells will match the composition of the water samples, therefore allowing us to use the mussel shells as a proxy for local water chemistry. Additionally, we hypothesize that the composition of the mussel shells will vary by location, and that we will be able to then infer where a fish is from by matching the composition of the fish in question to the mussels we have analyzed. We found that 87Sr/86Sr values for water and mussel hinge samples collected from tributaries east of Lake Roosevelt are significantly higher than the 87Sr/86Sr values for samples collected from tributaries west of Lake Roosevelt with averages of 0.7235 and 0.7089, respectively. The average 87Sr/86Sr ratios for water and mussel hinge samples collected within Lake Roosevelt is 0.7158, which is between the averages for samples collected east and west of the lake. Generally, older rocks are exposed on the east side of the lake, and younger rocks on the west side of the lake, so our 87Sr/86Sr values support the hypothesis that geologic units are a primary control on water chemistry, and that tributary compositions mix to form an average weighed by flow in Lake Roosevelt. The 87Sr/86Sr values for water and mussel shell samples collected from the same locations have a strong, positive linear correlation, suggesting that mussel shell 87Sr/86Sr ratios reflect the 87Sr/86Sr ratios of the ambient water. With these data, we can distinguish between different streams and the lake, but cannot distinguish between samples from within the same stream or within Lake Roosevelt. The Sr:Ca and Fe:Ca ratios of water samples show positive correlations with mussel shell compositions, with R2 values of 0.82 and 0.52, respectively. Ratios of Mg, Ba, Cu, Cd, Pb, and U to Ca showed little or no positive correlation between water and mussel shell samples. The elemental concentration data collected for this study do not demonstrate whether a correlation between elemental ratios in water samples and elemental ratios in mussel shell samples collected from the same location exists. Positive Sr:Ca and Fe:Ca correlations for water versus mussel shell samples indicate that perhaps for some elements, the composition of mussel shells are representative of the composition of ambient water. Using elemental concentration ratios to complement 87Sr/86Sr isotopic data may enhance our ability to identify correlations between water and mussel shell samples, and ultimately between mussel shell and otolith samples. The hinge part of a mussel shell may be used as a proxy for local water composition because the mussel shell composition reflects that of the local ambient water. The hinge of the mussel has the same composition as the whole mussel shell. We measured variation of 87Sr/86Sr ratios in the water among different streams and Lake Roosevelt. The 87Sr/86Sr values for samples collected in tributaries east of Lake Roosevelt, which erode older rocks, are higher for mussel shell and water samples than the average 87Sr/86Sr values for mussel shell and water samples collected in tributaries west of Lake Roosevelt, which flow through younger rocks.

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Comparison of initial Pb-isotope signatures of several early Archaean (3.65-3.82 Ga) lithologies (orthogneisses and metasediments) and minerals (feldspar and galena) documents the existence of substantial isotopic heterogeneity in the early Archaean, particularly in the Pb-207/Pb-204 ratio. The magnitude of isotopic variability at 3.82-3.65 Ga requires source separation between 4.3 and 4.1 Ga, depending on the extent of U/Pb fractionation possible in the early Earth. The isotopic heterogeneity could reflect the coexistence of enriched and depleted mantle domains or the separation of a terrestrial protocrust with a U-238/Pb-204 (mu) that was ca. 20-30% higher than coeval mantle. We prefer this latter explanation because the high-p signature is most evident in metasediments (that formed at the Earth's surface). This interpretation is strengthened by the fact that no straightforward mantle model can be constructed for these high-mu lithologies without violating bulk silicate Earth constraints. The Pb-isotope evidence for a long-lived protocrust complements similar Hf-isotope data from the Earth's oldest zircons, which also require an origin from an enriched (low Lu/Hf) environment. A model is developed in which greater than or equal to3.8-Ga tonalite and monzodiorite gneiss precursors (for one of which we provide zircon U-Pb data) are not mantle-derived but formed by remelting or differentiation of ancient (ca. 4.3 Ga) basaltic crust which had evolved with a higher U/Pb ratio than coeval mantle in the absence of the subduction process. With the initiation of terrestrial subduction at, we propose, ca. 3.75 Ga, most of the greater than or equal to3.8-Ga basaltic shell (and its differentiation products) was recycled into the mantle, because of the lack of a stabilising mantle lithosphere. We argue that the key event for preservation of all greater than or equal to3.8-Ga terrestrial crust was the intrusion of voluminous granitoids immediately after establishment of global subduction because of complementary creation of a lithospheric keel. Furthermore, we argue that preservation of !3.8-Ga material (in situ rocks and zircons) globally is restricted to cratons with a high U/Pb source character (North Atlantic, Slave, Zimbabwe, Yilgarn, and Wyoming), and that the Pb-isotope systematics of these provinces are ultimately explained by reworking of material that was derived from ca. 4.3 Ga (i.e. Hadean) basaltic crust.

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Reaction of bauxite residue with seawater results in neutralization of alkalinity through precipitation of Mg-, Ca-, and Al-hydroxide and carbonate minerals. In batch studies, the initial pH neutralization reaction was rapid (

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The effects of auxiliary calcium channel subunits on the expression and functional properties of high-voltage activated (HVA) calcium channels have been studied extensively in the Xenopus oocyte expression system, but are less completely characterized in a mammalian cellular environment. Here, we provide the first systematic analysis of the effects of calcium channel beta and alpha(2)-delta subunits on expression levels and biophysical properties of three different types (Ca(v)1.2, Ca(v)2.1 and Ca(v)2.3) of HVA calcium channels expressed in tsA-201 cells. Our data show that Ca(v)1.2 and Ca(v)2.3 channels yield significant barium current in the absence of any auxiliary subunits. Although calcium channel beta subunits were in principle capable of increasing whole cell conductance, this effect was dependent on the type of calcium channel alpha(1) subunit, and beta(3) subunits altogether failed to enhance current amplitude irrespective of channel subtype. Moreover, the alpha(2)-delta subunit alone is capable of increasing current amplitude of each channel type examined, and at least for members of the Ca(v)2 channel family, appears to act synergistically with beta subunits. In general agreement with previous studies, channel activation and inactivation gating was regulated both by beta and by alpha(2)-delta subunits. However, whereas pronounced regulation of inactivation characteristics was seen with the majority of the auxiliary subunits, effects on voltage dependence of activation were only small (< 5 mV). Overall, through a systematic approach, we have elucidated a previously underestimated role of the alpha(2)-delta(1) subunit with regard to current enhancement and kinetics. Moreover, the effects of each auxiliary subunit on whole cell conductance and channel gating appear to be specifically tailored to subsets of calcium channel subtypes.

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Cretaceous-Tertiaty (K-T) boundary (ca. 65 Ma) sections on a Southwest Pacific island containing dinosaurs were unknown until March 2003 when theropod bones were recovered from the Takatika Grit on the remote Chatham Islands (latitude 44 degrees S, longitude 176 degrees W), along the Chatham Rise. Tectonic and palaeontologic evidence support the eastward extension of a ca. 900 km land bridge that connected the islands to what is now New Zealand prior to the K-T boundary. The Chathams terrestrial fauna inhabited coastal, temperate environments along a low-lying, narrow, crustal extension of the New Zealand subcontinent, characterised by a tectonically dynamic, volcanic landscape with eroding hills (horsts) adjacent to flood plains and deltas, all sediments accumulating in grabens. This finger-like tract was blanketed with a conifer and clubmoss (Lycopodiopsida) dominated forest. The Chatham Islands region would have, along with New Zealand, provided a dinosaur island sanctuary after separating from the Gondwana margin ca. 80 Ma. (c) 2005 Elsevier B.V. All rights reserved.

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In-vitro calcification of poly(2-hydroxyethyl methacrylate) (PHEMA)-based hydrogels in simulated body fluid (SBF) under a steady/batch system without agitation or stirring the solutions has been investigated. It was noted that the formation of calcium phosphate (CaP) deposits primarily proceeded through spontaneous precipitation. The CaP deposits were found both on the surface and inside the hydrogels. It appears that the effect of chemical structure or reducing the relative number of oxygen atoms in the copolymers on the degree of calcification was only important at the early stage of calcification. The morphology of the CaP deposits was observed to be spherical aggregates with a thickness of the CaP layer less than 0.5 mu m. Additionally, the CaP deposits were found to be poorly crystalline or to have nano-size crystals, or to exist mostly as an amorphous phase. Characterization of the CaP phases in the deposits revealed that the deposits were comprised mainly of whitlockite [Ca9MgH(PO4)(7)] type apatite and DCPD (CaHPO4 center dot 2H(2)O) as the precursors of hydroxyapatite [Ca-10(PO4)(6)(OH)(2)]. The presence of carbonate in the deposits was also detected during the calcification of PHEMA based hydrogels in SBF solution.

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Insects have a much smaller repertoire of voltage-gated calcium (Ca-v) channels than vertebrates. Drosophila melanogaster harbors only a single ortholog of each of the vertebrate Ca(v)1, Ca(v)2, and Ca(v)3 subtypes, although its basal inventory is expanded by alternative splicing and editing of Ca-v channel transcripts. Nevertheless, there appears to be little functional plasticity within this limited panel of insect Ca-v channels, since severe loss-of-function mutations in genes encoding the pore-forming a, subunits in Drosophila are embryonic lethal. Since the primary role of spider venom is to paralyze or kill insect prey, it is not surprising that most, if not all, spider venoms contain peptides that potently modify the activity of these functionally critical insect Ca-v channels. Unfortunately, it has proven difficult to determine the precise ion channel subtypes recognized by these peptide toxins since insect Ca-v channels have significantly different pharmacology to their vertebrate counterparts, and cloned insect Ca-v channels are not available for electrophysiological studies. However, biochemical and genetic studies indicate that some of these spider toxins might ultimately become the defining pharmacology for certain subtypes of insect Ca-v channels. This review focuses on peptidic spider toxins that specifically target insect Ca-v channels. In addition to providing novel molecular tools for ion channel characterization, some of these toxins are being used as leads to develop new methods for controlling insect pests. (c) 2006 Elsevier Ltd. All rights reserved.