6,283 research outputs found
Fragmentation in the Governance of EU External Relations: Legal Institutional Dilemmas and the New Constitution for Europe
The European Union, an Ongoing Process of Integration contains 27 original contributions authored by prominent EU lawyers from academia and practice and concentrates on the three main areas of European integration that mark the career path of Alfred E. Kellermann: institutional and constitutional aspects (part I), general principles and substantive aspects (part II), and new Member States and Eastern Europe (part III). The contributions included in this Liber Amicorum vary from thematic in-depth studies to studies of a comparative nature. Their themes cover, inter alia, the structure of the Union according to the Constitution for Europe, the changes and challenges with which the Union¿s institutions are faced, including the creation of the positions of the President of the European Council and the Union Minister for Foreign Affairs, the future paths of flexibility (enhanced cooperation, partial agreements and pioneer groups), the role of national competition authorities and national courts under Regulation 1/2003, the constitutional preparation for EU accession in the new Member States, and the influence of European integration on the development of law in Russia. All contributions have been written in honour of Alfred E. Kellermann. Born in The Hague, raised in Switzerland during the Second World War and having studied and trained at Leiden University and at the European Commission¿s Legal Service in Brussels in the founding years of the European integration process, Doctor Honoris Causa Alfred E. Kellermann is a European by nature and vocation. For almost forty years, Alfred E. Kellermann has worked for the T.M.C. Asser Institute in The Hague. For many, he has become the face of the Institute in the Netherlands and abroad. This is the result of his work as a lecturer and consultant in EU law in countless short and long-term projects all over Europe, including Russia. Perhaps his finest accomplishment in raising awareness and expertise in the law of the European Union concerns the organisation of the famous `Asser Colloquia¿ on EU law and the publication of their proceedings
Critical Entropy of Quantum Heisenberg Magnets on Simple-Cubic Lattices
We analyze the temperature dependence of the entropy of the spin-1/2
Heisenberg model on the three-dimensional simple-cubic lattice, for both the
case of antiferromagnetic and ferromagnetic nearest neighbor exchange
interactions. Using optimized extended ensemble quantum Monte Carlo
simulations, we extract the entropy at the critical temperature for magnetic
order from a finite-size scaling analysis. For the antiferromagnetic case, the
critical entropy density equals 0.341(5), whereas for the ferromagnet, a
larger value of 0.401(5) is obtained. We compare our simulation results
to estimates put forward recently in studies assessing means of realizing the
antiferromagnetic N\'eel state in ultra-cold fermion gases in optical lattices.Comment: 3 pages, 2 figures; published versio
Magnetocaloric effect in quantum spin-s chains
We compute the entropy of antiferromagnetic quantum spin-s chains in an
external magnetic field using exact diagonalization and Quantum Monte Carlo
simulations. The magnetocaloric effect, i.e., temperature variations during
adiabatic field changes, can be derived from the isentropes. First, we focus on
the example of the spin-s=1 chain and show that one can cool by closing the
Haldane gap with a magnetic field. We then move to quantum spin-s chains and
demonstrate linear scaling with close to the saturation field. In passing,
we propose a new method to compute many low-lying excited states using the
Lanczos recursion.Comment: 11 pages including 6 figures, to appear in Condensed Matter Physics
(Lviv
What do WMAP and SDSS really tell about inflation?
We derive new constraints on the Hubble function H(phi) and subsequently on
the inflationary potential V(phi) from WMAP 3-year data combined with the Sloan
Luminous Red Galaxy survey (SDSS-LRG), using a new methodology which appears to
be more generic, conservative and model-independent than in most of the recent
literature, since it depends neither on the slow-roll approximation, nor on any
extrapolation scheme for the potential beyond the observable e-fold range, nor
on additional assumptions about initial conditions for the inflaton velocity.
This last feature represents the main improvement of this work, and is made
possible by the reconstruction of H(phi) prior to V(phi). Our results only rely
on the assumption that within the observable range, corresponding to ~ 10
e-folds, inflation is not interrupted and the function H(phi) is smooth enough
for being Taylor-expanded at order one, two or three. We conclude that the
variety of potentials allowed by the data is still large. However, it is clear
that the first two slow-roll parameters are really small while the validity of
the slow-roll expansion beyond them is not established.Comment: 5 pages, 3 figures. Numerical module available at
http://wwwlapp.in2p3.fr/~valkenbu/inflationH/ . References added, discussion
expande
The European Court of Justice blocks the EU's accession to the ECHR
The European Court of Justice delivered a long-awaited opinion on the accession of the European Union to the European Convention of Human Rights (Opinion 2/13) on 18 December 2014. To the surprise of many, the judges in Luxembourg held that the draft Accession Agreement is not compatible with the EU treaties because it undermines the autonomy of EU law. As a consequence, the negotiators will be called back to the drawing board to take the Court’s conclusions into account, or to come up with other solutions. The Accession Agreement would require a major revision, not just cosmetic changes. Moreover, any deal would require the consent of all ECHR contracting parties, including Turkey and Russia. With this opinion, the Court of Justice went against the will of the member states and has thus put itself on a collision course with them
Supersolids in confined fermions on one-dimensional optical lattices
Using quantum Monte Carlo simulations, we show that density-density and
pairing correlation functions of the one-dimensional attractive fermionic
Hubbard model in a harmonic confinement potential are characterized by the
anomalous dimension of a corresponding periodic system, and hence
display quantum critical behavior. The corresponding fluctuations render the
SU(2) symmetry breaking by the confining potential irrelevant, leading to
structure form factors for both correlation functions that scale with the same
exponent upon increasing the system size, thus giving rise to a
(quasi)supersolid.Comment: 4 pages, 5 figures, published versio
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