1,303 research outputs found
Ageing and pensions in the Euro Area Survey and projection results
Population ageing will impose a significant burden on European fiscal balances, in particular through pay-as-you-go pension systems. This study presents an independent estimate of this burden for the euro area, and quantifies the impact of two reform scenarios. Based on widely used, but optimistic assumptions, the present value of future pension deficits through 2050 is estimated at 51percent of GDP, adding to the current average explicit debt stock of around 67 percent of GDP. In this calculation, the deficits currently incurred by many pension systems as revenues fall short of expenditures, are not included. Viable parametric reforms represent no durable solution to alleviate the burden sufficiently, as they can balance pension systems at best temporarily. A comprehensive reform, including reforms of current systems, and a move towards partial funding, is found to ensure permanent financial viability of the public pension system.Pensions&Retirement Systems,Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Economic Stabilization
The structure of a single sharp quantum Hall edge probed by momentum-resolved tunneling
Momentum resolved magneto-tunnelling spectroscopy is performed at a single
sharp quantum Hall edge. We directly probe the structure of individual integer
quantum Hall (QH) edge modes, and find that an epitaxially overgrown cleaved
edge realizes the sharp edge limit, where the Chklovskii picture relevant for
soft etched or gated edges is no longer valid. The Fermi wavevector in the
probe quantum well probes the real-space position of the QH edge modes, and
reveals inter-channel distances smaller than both the magnetic length and the
Bohr radius. We quantitatively describe the lineshape of principal conductance
peaks and deduce an edge filling factor from their position consistent with the
bulk value. We observe features in the dispersion which are attributed to
fluctuations in the ground energy of the quantum Hall system.Comment: 4 pages, 3 figure
Die Messung von Wingner-Energien an einigen GRaphiten mit einem Kalorimeter. EUR 4036. = The measurement of wigner energies on some graphites with a calorimeter. EUR 4036.
Dynamical mean-field theory of indirect magnetic exchange
To analyze the physical properties arising from indirect magnetic exchange
between several magnetic adatoms and between complex magnetic nanostructures on
metallic surfaces, the real-space extension of dynamical mean-field theory
(R-DMFT) appears attractive as it can be applied to systems of almost arbitrary
geometry and complexity. While R-DMFT describes the Kondo effect of a single
adatom exactly, indirect magnetic (RKKY) exchange is taken into account on an
approximate level only. Here, we consider a simplified model system consisting
of two magnetic Hubbard sites ("adatoms") hybridizing with a non-interacting
tight-binding chain ("substrate surface"). This two-impurity Anderson model
incorporates the competition between the Kondo effect and indirect exchange but
is amenable to an exact numerical solution via the density-matrix
renormalization group (DMRG). The particle-hole symmetric model at half-filling
and zero temperature is used to benchmark R-DMFT results for the magnetic
coupling between the two adatoms and for the magnetic properties induced in the
substrate. In particular, the dependence of the local adatom and the nonlocal
adatom-adatom static susceptibilities as well as the magnetic response of the
substrate on the distance between the adatoms and on the strength of their
coupling with the substrate is studied. We find both, excellent agreement with
the DMRG data even on subtle details of the competition between RKKY exchange
and the Kondo effect but also complete failure of the R-DMFT, depending on the
parameter regime considered. R-DMFT calculations are performed using the
Lanczos method as impurity solver. With the real-space extension of the
two-site DMFT, we also benchmark a simplified R-DMFT variant.Comment: 14 pages, 8 figure
Palm pairs and the general mass-transport principle
We consider a lcsc group G acting properly on a Borel space S and measurably
on an underlying sigma-finite measure space. Our first main result is a
transport formula connecting the Palm pairs of jointly stationary random
measures on S. A key (and new) technical result is a measurable disintegration
of the Haar measure on G along the orbits. The second main result is an
intrinsic characterization of the Palm pairs of a G-invariant random measure.
We then proceed with deriving a general version of the mass-transport principle
for possibly non-transitive and non-unimodular group operations first in a
deterministic and then in its full probabilistic form.Comment: 26 page
Harnessing finance for a new era of decentralised electricity access: A review of private investment patterns and emerging business models
Achieving the Sustainable Development Goals (SDGs) requires ensuring universal energy access. Yet, governments of low-income countries face significant budget constraints for the capital-intensive infrastructure required to reach the hundreds of millions of households and businesses without grid electricity. In this context, private investors are the key actors capable of channelling such large capital requirements. Compared to the previous decades, the 2010s witnessed a growing mobilization of private funding in the off-grid electricity access sector, including some success stories. Nonetheless, with less than ten years left until the SDGs horizon, off-grid companies systematically struggle to ensure the financial sustainability of projects, as the industry still seeks to demonstrate its maturity and profitability. In this paper, we critically review the main business approaches adopted by private decentralised electricity access service providers. The aim of the analysis is to identify the main drivers of risk and failure which have been hindering sectoral investment. We then propose and discuss four potential game-changing factors that could foster the next generation of private investment in decentralised electricity solutions: (i) anchor-businesses-community (ABC) models; (ii) the design of integrated business models centred around income generation; (iii) the growing role for “local” financiers; (iv) the securitization of assets. Our paper targets private infrastructure developers and financiers aiming at fostering investment in financially sustainable decentralised electricity access projects
Lifetime measurements in Co and Co
Lifetimes of the and states in Co and the
state in Co were measured using the recoil distance Doppler
shift and the differential decay curve methods. The nuclei were populated by
multi-nucleon transfer reactions in inverse kinematics. Gamma rays were
measured with the EXOGAM Ge array and the recoiling fragments were fully
identified using the large-acceptance VAMOS spectrometer. The E2 transition
probabilities from the and states to the ground
state could be extracted in Co as well as an upper limit for the
(E2) value in Co. The experimental
results were compared to large-scale shell-model calculations in the and
model spaces, allowing to draw conclusions on the single-particle
or collective nature of the various states.Comment: 8 pages, 8 figures, 1 table, accepted for publication in Physical
Review
Effects of water on the stochastic motions of propane confined in MCM-41-S pores
Hydrocarbons confined in porous media find applications in a wide variety of industries and therefore their diffusive behavior is widely studied. Most of the porous media found in natural environments are laden with water, which might affect the confined hydrocarbons. To quantify the effect of hydration, we report here a combined quasielastic neutron scattering (QENS) and molecular dynamics (MD) simulation study on the dynamics of propane confined in the 1.5 nm-wide micropores of MCM-41-S in the presence of water at 230 and 250 K. To eliminate the strong incoherent signal from water and emphasize the propane signal we have used heavy water (D2O). QENS data show two dynamically different populations of propane in MCM-41-S and suggest that the presence of water hinders the diffusion of propane. Weak elastic contributions to the QENS spectra suggest that only long-range translational motion of propane molecules contributes to the quasielastic broadening. MD simulations carried out using a model cylindrical silica pore of 1.6 nm diameter filled with water and propane agree with the experimental finding of water hindering the diffusion of propane. Further, the simulation results suggest that the slowing down of propane motions is a function of the water content within the pore and is stronger at higher water contents. At high water content, the structure and the dynamics, both translational and rotational, of propane are severely impacted. Simulation data suggest that the rotational motion of the propane molecule occurs on time scales much faster than those accessible with the QENS instrument used, and thus explain the weak elastic contribution to the QENS spectra measured in the experiments. This study shows the effects of hydration on the structure and dynamics of volatiles in porous media, which are of interest for fundamental understanding and applied studies of confined fluids
Observation of isotonic symmetry for enhanced quadrupole collectivity in neutron-rich 62,64,66Fe isotopes at N=40
The transition rates for the 2_{1}^{+} states in 62,64,66Fe were studied
using the Recoil Distance Doppler-Shift technique applied to projectile Coulomb
excitation reactions. The deduced E2 strengths illustrate the enhanced
collectivity of the neutron-rich Fe isotopes up to N=40. The results are
interpreted by the generalized concept of valence proton symmetry which
describes the evolution of nuclear structure around N=40 as governed by the
number of valence protons with respect to Z~30. The deformation suggested by
the experimental data is reproduced by state-of-the-art shell calculations with
a new effective interaction developed for the fpgd valence space.Comment: 4 pages, 2 figure
Keep it SMPL: Automatic Estimation of 3D Human Pose and Shape from a Single Image
We describe the first method to automatically estimate the 3D pose of the
human body as well as its 3D shape from a single unconstrained image. We
estimate a full 3D mesh and show that 2D joints alone carry a surprising amount
of information about body shape. The problem is challenging because of the
complexity of the human body, articulation, occlusion, clothing, lighting, and
the inherent ambiguity in inferring 3D from 2D. To solve this, we first use a
recently published CNN-based method, DeepCut, to predict (bottom-up) the 2D
body joint locations. We then fit (top-down) a recently published statistical
body shape model, called SMPL, to the 2D joints. We do so by minimizing an
objective function that penalizes the error between the projected 3D model
joints and detected 2D joints. Because SMPL captures correlations in human
shape across the population, we are able to robustly fit it to very little
data. We further leverage the 3D model to prevent solutions that cause
interpenetration. We evaluate our method, SMPLify, on the Leeds Sports,
HumanEva, and Human3.6M datasets, showing superior pose accuracy with respect
to the state of the art.Comment: To appear in ECCV 201
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