81 research outputs found
Small donors in world politics: The role of trust funds in the foreign aid policies of Central and Eastern European donors
The Central and Eastern European (CEE) EU member states have emerged as new donors of international development assistance since the turn of the millennium. The literature has tended to focus on the bilateral components of these policies, and neglected CEE multilateral aid. This paper contributes to filling this gap by examining how and why CEE donors contribute to trust funds operated by multilateral donors. The aim of the paper is twofold: First, it provides a descriptive account of how CEE countries use trust funds in the allocation of their foreign aid. Second, it explains this allocation using data from qualitative interviews with CEE officials. CEE countries make much less use of trust funds than might be expected. This is due not only to the loss of visibility and control over their resources, but also to how CEE companies and non-governmental organisations (NGOs) rarely achieve funding successes at multilateral organisations
Confinement effects on glass forming liquids probed by DMA
Many molecular glass forming liquids show a shift of the glass transition T-g
to lower temperatures when the liquid is confined into mesoporous host
matrices. Two contrary explanations for this effect are given in literature:
First, confinement induced acceleration of the dynamics of the molecules leads
to an effective downshift of T-g increasing with decreasing pore size. Second,
due to thermal mismatch between the liquid and the surrounding host matrix,
negative pressure develops inside the pores with decreasing temperature, which
also shifts T-g to lower temperatures. Here we present dynamic mechanical
analysis measurements of the glass forming liquid salol in Vycor and Gelsil
with pore sizes of d=2.6, 5.0 and 7.5 nm. The dynamic complex elastic
susceptibility data can be consistently described with the assumption of two
relaxation processes inside the pores: A surface induced slowed down relaxation
due to interaction with rough pore interfaces and a second relaxation within
the core of the pores. This core relaxation time is reduced with decreasing
pore size d, leading to a downshift of T-g proportional to 1/d in perfect
agreement with recent differential scanning calorimetry (DSC) measurements.
Thermal expansion measurements of empty and salol filled mesoporous samples
revealed that the contribution of negative pressure to the downshift of T-g is
small (<30%) and the main effect is due to the suppression of dynamically
correlated regions of size xi when the pore size xi approaches
Time and length scales in supercooled liquids
We numerically obtain the first quantitative demonstration that development
of spatial correlations of mobility as temperature is lowered is responsible
for the ``decoupling'' of transport properties of supercooled liquids. This
result further demonstrates the necessity of a spatial description of the glass
formation and therefore seriously challenges a number of popular alternative
theoretical descriptions.Comment: 4 pages, 4 figs; improved version: new refs and discussion
Conformational and Structural Relaxations of Poly(ethylene oxide) and Poly(propylene oxide) Melts: Molecular Dynamics Study of Spatial Heterogeneity, Cooperativity, and Correlated Forward-Backward Motion
Performing molecular dynamics simulations for all-atom models, we
characterize the conformational and structural relaxations of poly(ethylene
oxide) and poly(propylene oxide) melts. The temperature dependence of these
relaxation processes deviates from an Arrhenius law for both polymers. We
demonstrate that mode-coupling theory captures some aspects of the glassy
slowdown, but it does not enable a complete explanation of the dynamical
behavior. When the temperature is decreased, spatially heterogeneous and
cooperative translational dynamics are found to become more important for the
structural relaxation. Moreover, the transitions between the conformational
states cease to obey Poisson statistics. In particular, we show that, at
sufficiently low temperatures, correlated forward-backward motion is an
important aspect of the conformational relaxation, leading to strongly
nonexponential distributions for the waiting times of the dihedrals in the
various conformational statesComment: 13 pages, 13 figure
The Shapes of Cooperatively Rearranging Regions in Glass Forming Liquids
The shapes of cooperatively rearranging regions in glassy liquids change from
being compact at low temperatures to fractal or ``stringy'' as the dynamical
crossover temperature from activated to collisional transport is approached
from below. We present a quantitative microscopic treatment of this change of
morphology within the framework of the random first order transition theory of
glasses. We predict a correlation of the ratio of the dynamical crossover
temperature to the laboratory glass transition temperature, and the heat
capacity discontinuity at the glass transition, Delta C_p. The predicted
correlation agrees with experimental results for the 21 materials compiled by
Novikov and Sokolov.Comment: 9 pages, 6 figure
The nature of slow dynamics in a minimal model of frustration-limited domains
We present simulation results for the dynamics of a schematic model based on
the frustration-limited domain picture of glass-forming liquids. These results
are compared with approximate theoretical predictions analogous to those
commonly used for supercooled liquid dynamics. Although model relaxation times
increase by several orders of magnitude in a non-Arrhenius manner as a
microphase separation transition is approached, the slow relaxation is in many
ways dissimilar to that of a liquid. In particular, structural relaxation is
nearly exponential in time at each wave vector, indicating that the mode
coupling effects dominating liquid relaxation are comparatively weak within
this model. Relaxation properties of the model are instead well reproduced by
the simplest dynamical extension of a static Hartree approximation. This
approach is qualitatively accurate even for temperatures at which the mode
coupling approximation predicts loss of ergodicity. These results suggest that
the thermodynamically disordered phase of such a minimal model poorly
caricatures the slow dynamics of a liquid near its glass transition
Bad governance:How privatization increases corruption in the developing world
International organizations have become key actors in the fight against corruption. Among these organizations, the International Monetary Fund (IMF) maintains a powerful position over borrowing countries in its ability to mandate far‐ranging policy reforms – so‐called “conditionalities” – in exchange for access to financial assistance. While IMF pressure can force the implementation of anti‐corruption policies, potentially reducing corruption, other IMF policy measures, such as the privatization of state‐owned enterprises, can create rent‐extraction opportunities and limit the capacity of state institutions to limit corrupt behavior. To test these mechanisms, we conduct instrumental‐variable regression analysis using an original dataset on IMF conditionality for up to 141 developing countries from 1982 to 2014. We find that conditions to privatize state‐owned enterprises exert significant detrimental effects on corruption control. Conversely, other areas of IMF intervention are not consistently related to corruption abatement. These findings offer policy lessons regarding the design of conditionality, which should avoid large‐scale privatization, especially under conditions of weak accountability
Glass transition with decreasing correlation length during cooling of Fe50Co50 superlattice and strong liquids
The glass transition GT is usually thought of as a structural arrest that
occurs during the cooling of a liquid, or sometimes a plastic crystal, trapping
a metastable state of the system before it can recrystallize to stabler forms1.
This phenomenon occurs in liquids of all classes, most recently in bulk
metallic glassformers2. Much theoretical interest has been generated by the
dynamical heterogeneity observed in cooling of fragile liquids3, 4, and many
have suggested that the slow-down is caused by a related increasing correlation
length 5-9. Here we report both kinetics and thermodynamics of arrest in a
system that disorders while in its ground state, exhibits a large !Cp on arrest
(!Cp = Cp,mobile - Cp,arrested), yet clearly is characterized by a correlation
length that is decreasing as GT is approached from above. We show that GT
kinetics in our system, the disordering superlattice Fe50Co50, satisfy the
kinetic criterion for ideally 'strong' glassformers10, and since !Cp behavior
through Tg also correlates10, we propose that very strong liquidsand very
fragile liquids exist on opposite flanks of an order-disorder transition - one
that is already known for model systems
Chlorophylls, ligands and assembly of light-harvesting complexes in chloroplasts
Chlorophyll (Chl) b serves an essential function in accumulation of light-harvesting complexes (LHCs) in plants. In this article, this role of Chl b is explored by considering the properties of Chls and the ligands with which they interact in the complexes. The overall properties of the Chls, not only their spectral features, are altered as consequences of chemical modifications on the periphery of the molecules. Important modifications are introduction of oxygen atoms at specific locations and reduction or desaturation of sidechains. These modifications influence formation of coordination bonds by which the central Mg atom, the Lewis acid, of Chl molecules interacts with amino acid sidechains, as the Lewis base, in proteins. Chl a is a versatile Lewis acid and interacts principally with imidazole groups but also with sidechain amides and water. The 7-formyl group on Chl b withdraws electron density toward the periphery of the molecule and consequently the positive Mg is less shielded by the molecular electron cloud than in Chl a. Chl b thus tends to form electrostatic bonds with Lewis bases with a fixed dipole, such as water and, in particular, peptide backbone carbonyl groups. The coordination bonds are enhanced by H-bonds between the protein and the 7-formyl group. These additional strong interactions with Chl b are necessary to achieve assembly of stable LHCs
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