677 research outputs found

    Performances of peace: Utrecht 1713

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    The Peace of Utrecht (1713), which brought an end to the War of the Spanish Succession, was a milestone in global history. Performances of Peace aims to rethink the significance of the Peace of Utrecht by exploring the nexus between culture and politics. For too long, cultural and political historians have studied early modern international relations in isolation. By studying the political as well as the cultural aspects of this peace (and its concomitant paradoxes) from a broader perspective, this volume aims to shed new light on the relation between diplomacy and performative culture in the public spher

    Photosystem II: Thermodynamics and Kinetics of Electron Transport from QA- to QB(QB- ) and Deleterious Effects of Copper(II)

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    Studies on thermodynamics and kinetics of electron transfer from QA- to QB(QB-) were performed by monitoring laser flash induced changes of the relative fluorescence emission as a function of temperature (220 K < T < 310 K) in isolated thylakoids and PS II membrane fragments. In addition, effects of bivalent metal ions on PS II were investigated by measuring conventional fluorescence induction curves, oxygen evolution, manganese content and atrazine binding mostly in PS II membrane fragments. It was found: a) the normalized level of the fluorescence remaining 10 s after the actinic flash (Ft/F0) steeply increases at temperatures below -10 to - 20 °C, b) the fast phase of the transient fluorescence change becomes markedly retarded with decreasing temperatures, c) among different cations (Cu2+, Zn2+, Cd2+, Ni2+, Co2+) only Cu2+ exhibits marked effects in the concentration range below 100 μᴍ and d) Cu2+ decreases the normalized variable fluorescence, inhibits oxygen evolution and diminishes the affinity to atrazine binding without affecting the number of binding sites. The content of about four manganeses per functionally competent oxygen evolving complex is not changed by [Cu2+] < 70 μᴍ. Based on these findings it is concluded: i) a temperature dependent equilibrium between an inactive (I) and active (A) state of QA- reoxidation by QB(QB- ) is characterized by standard enthalpies ΔH° of 95 kJ mol-1 and 60 kJ mol-1 and standard entropies ΔS° of 370 kJ K-1 mol-1 and 240 kJ K-1 mol-1 in isolated thylakoids and PS II membrane fragments, respectively, ii) the activation energies of QA- reoxidation by plastoquinone bound to the QB site are about 30 kJ mol-1 (thylakoids) and 40 kJ mol-1 (PS II membrane fragments) in 220 K < T < 300 K, and iii) Cu2+ causes at least a two-fold effect on PS II by modifying the atrazine binding affinity at lower concentrations ( ~ 5 μᴍ) and interference with the redox active tyrosine Yz at slightly higher concentration ( ~ 10 μᴍ) leading to blockage of oxygen evolution

    Eine gelungene Neuordnung. Die Ballei Utrecht des Deutschen Ordens, 1753–1795

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    A successful reorganization. The Teutonic Order Bailiwick of Utrecht, 1753–1795In 1753 the newly elected coadjutor of the Teutonic Order Bailiwick of Utrecht, Unico Wilhelm Count van Wassenaer van Twickel, analyzed the state of the order, being a total chaos after a long period of decay. After he was commissioned by the other members to make a plan for improvement, Van Wassenaer managed to implement a reorganization that was highly successful. It was based on a rational management of the possessions by a professional steward, concentration of supervision at the land commanderie in Utrecht, a reduced role of the members and automatic succession of the land commander after his death by the coadjutor to prevent an interregnum as between 1751 and 1753. According to new rules, Van Wassenaer became land commander in 1761 and finished the reorganization during his time in office. After his death in 1766 his successor followed his course. The competent steward Gijsbert Dirk Cazius managed to turn the deficits into increasing surpluses, making the Baliwick of Utrecht an organization that was financially robust by the time it was threatened by the French Revolution. In the success of his financial policy Cazius, who worked closely together with the land commanders he served, was helped by the economic developments: the rising prices of agricultural products enabled farmers to pay higher rents that were  collected punctually by the steward. In its rational and utilitarian character the reorganization seems to breeze the spirit of the Enlightenment, but the emphasis on noble ancestors and Reformed confession as prerequisites for membership make the Bailiwick of Utrecht a typical institution of the Ancien Regime. However, the realized plans of Van Wassenaer led the Baliwick out of a desperate state and played a crucial role in the survival to the present day

    Vertical motion of the thermocline, nitracline and chlorophyll maximum layers in relation to currents on the Southern California Shelf

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    A continuous four-day time series of nitrate concentration, temperature, chlorophyll fluorescence, and currents, sampled at fixed depths, revealed that distributions of temperature and nitrate could be accounted for by vertical motions in the water column associated with the semidiurnal internal tide and internal waves. A probable mixing event was observed: the transport of nitrate into the surface-layer associated with shear instabilities generated by internal waves. On temporal scales of less than a few hours, the variation of chlorophyll fluorescence could also be explained by vertical advection. However, on longer scales, swimming behavior of the phytoplankton assemblage (dominated by Ceratium spp.), along with vertical motions in the water column, appears to account for the vertical distribution of chlorophyll. These results indicate that the nitracline maintains a stable relationship with the density structure of the water column on a scale of days, whereas the subsurface chlorophyll maximum can change significantly over several hours

    Why the belief in one’s equal rights matters:Self-respect, depressive symptoms, and suicidal ideation in Western and non-Western countries

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    The present research investigated the relationship between self-respect (i.e., a person’s belief of possessing the same rights as others) and depressive symptoms. Based on earlier longitudinal findings that self-respect fosters assertiveness and that assertiveness negatively predicts depressive symptoms, we tested these relationships in Western and non-Western countries. Additionally, we explored associations with suicidal ideation. Across seven countries ( N = 2408) we found that self-respect and depressive symptoms were negatively correlated. In addition, we found evidence for an indirect path via assertiveness as well as negative correlations with suicidal ideation in countries with available measures. Finally, within-manuscript meta-analyses confirmed the main path between self-respect and depressive symptoms across all seven countries. This research presents the first evidence for the negative association between self-respect (feeling equal to others) and depressive symptoms and highlights new directions for linking self and self-regard to mental health

    Isolation and properties of PS II membrane fragments depleted of the non heme iron center

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    AbstractThe functional properties and the content of non heme iron and cytochrome b559 were investigated by measuring flash induced transient changes of the relative fluorescence quantum yield and applying Mössbauer spectroscopy. It was found that untreated PS II membrane fragments contain a heterogeneous population of two types of non heme iron centers and about 2 cytochrome b559 per PS II. Twofold treatment of these samples with a recently described ‘iron depletion’ procedure (MacMillan, F., Lendzian, F., Renger, G. and Lubitz, W. (1995) Biochemistry 34, 3144–8156) leads to a complete loss (below the detection limit of Mössbauer spectroscopy) of the non heme iron center while more than 50% of the PS II complexes retain the functional integrity for light induced formation of the ‘stable’ radical pair YZOX P680Pheo QA−.. This sample type deprived of virtually all non heme iron in PS II provides a most suitable material for magnetic resonance studies that require an elimination of the interaction between Fe2+ and nearby radicals

    Polymers in Curved Boxes

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    We apply results derived in other contexts for the spectrum of the Laplace operator in curved geometries to the study of an ideal polymer chain confined to a spherical annulus in arbitrary space dimension D and conclude that the free energy compared to its value for an uncurved box of the same thickness and volume, is lower when D<3D < 3, stays the same when D=3D = 3, and is higher when \mbox{D>3D > 3}. Thus confining an ideal polymer chain to a cylindrical shell, lowers the effective bending elasticity of the walls, and might induce spontaneous symmetry breaking, i.e. bending. (Actually, the above mentioned results show that {\em {any}} shell in D=3D = 3 induces this effect, except for a spherical shell). We compute the contribution of this effect to the bending rigidities in the Helfrich free energy expression.Comment: 20 pages RevTeX, epsf; 4 figures; submitted to Macromoledule

    Krueppel-like factor 15 regulates Wnt/beta-catenin transcription and controls cardiac progenitor cell fate in the postnatal heart

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    Wnt/beta-catenin signalling controls adult heart remodelling in part via regulation of cardiac progenitor cell (CPC) differentiation. An enhanced understanding of mechanisms controlling CPC biology might facilitate the development of new therapeutic strategies in heart failure. We identified and characterized a novel cardiac interaction between Krueppel-like factor 15 and components of the Wnt/beta-catenin pathway leading to inhibition of transcription. In vitro mutation, reporter assays and co-localization analyses revealed that KLF15 requires both the C-terminus, necessary for nuclear localization, and a minimal N-terminal regulatory region to inhibit transcription. In line with this, functional Klf15 knock-out mice exhibited cardiac beta-catenin transcriptional activation along with functional cardiac deterioration in normal homeostasis and upon hypertrophy. We further provide in vivo and in vitro evidences for preferential endothelial lineage differentiation of CPCs upon KLF15 deletion. Via inhibition of beta-catenin transcription, KLF15 controls CPC homeostasis in the adult heart similar to embryonic cardiogenesis. This knowledge may provide a tool for reactivation of this apparently dormant CPC population in the adult heart and thus be an attractive approach to enhance endogenous cardiac repair

    Binuclear Manganese(III) Complexes as Electron Donors in D1/D2/Cytochrome b559 Preparations Isolated from Spinach Photosystem II Membrane Fragments

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    The capability of different manganese complexes to act as PS II electron donors in D1/D2/ cytochrome b 559 complexes has been analyzed by measuring actinic light-induced absorption changes at 680 nm (650 nm) and 340 nm, reflecting the photoaccumulation of Pheophytin- (Pheo-) and the reduction of NADP+ respectively. The data obtained reveal: a) the donor capacity of synthetic binuclear Mn(III)2 complexes containing aromatic ligands significantly exceeds that for MnCl2 in both cases, i.e. Pheo- photoaccumulation and NADP+ reduction; b) manganese complexes can serve as suitable electron donors for light-induced NADP+ reduction catalyzed by D1/D2/cytochrome b559 complexes and ferredoxin plus ferredoxin- NADP+ reductase under anaerobic conditions and c) the specific turnover rate of the system leading to NADP+ reduction is extremely small. The implications of these findings are briefly discussed
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