Université libre de Bruxelles

About: Université libre de Bruxelles is a education organization based out in Brussels, Belgium. It is known for research contribution in the topics: Population & Breast cancer. The organization has 24974 authors who have published 56969 publications receiving 2084303 citations. The organization is also known as: ULB.

Experimental demonstration of quantum memory for light

Abstract: The information carrier of today's communications, a weak pulse of light, is an intrinsically quantum object. As a consequence, complete information about the pulse cannot be perfectly recorded in a classical memory, even in principle. In the field of quantum information, this has led to the long-standing challenge of how to achieve a high-fidelity transfer of an independently prepared quantum state of light onto an atomic quantum state1,2,3,4. Here we propose and experimentally demonstrate a protocol for such a quantum memory based on atomic ensembles. Recording of an externally provided quantum state of light onto the atomic quantum memory is achieved with 70 per cent fidelity, significantly higher than the limit for classical recording. Quantum storage of light is achieved in three steps: first, interaction of the input pulse and an entangling field with spin-polarized caesium atoms; second, subsequent measurement of the transmitted light; and third, feedback onto the atoms using a radio-frequency magnetic pulse conditioned on the measurement result. The density of recorded states is 33 per cent higher than the best classical recording of light onto atoms, with a quantum memory lifetime of up to 4 milliseconds.

Corporate Governance and Control

Abstract: Corporate governance is concerned with the resolution of collective action problems among dispersed investors and the reconciliation of conflicts of interest between various corporate claimholders. In this survey we review the theoretical and empirical research on the main mechanisms of corporate control, discuss the main legal and regulatory institutions in different countries, and examine the comparative corporate governance literature. A fundamental dilemma of corporate governance emerges from this overview: regulation of large shareholder intervention may provide better protection to small shareholders; but such regulations may increase managerial discretion and scope for abuse.

Management of bleeding following major trauma: an updated European guideline

Abstract: Introduction: Evidence-based recommendations are needed to guide the acute management of the bleeding trauma patient, which when implemented may improve patient outcomes. Methods: The multidisciplinary Task Force for Advanced Bleeding Care in Trauma was formed in 2005 with the aim of developing a guideline for the management of bleeding following severe injury. This document presents an updated version of the guideline published by the group in 2007. Recommendations were formulated using a nominal group process, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) hierarchy of evidence and based on a systematic review of published literature. Results: Key changes encompassed in this version of the guideline include new recommendations on coagulation support and monitoring and the appropriate use of local haemostatic measures, tourniquets, calcium and desmopressin in the bleeding trauma patient. The remaining recommendations have been reevaluated and graded based on literature published since the last edition of the guideline. Consideration was also given to changes in clinical practice that have taken place during this time period as a result of both new evidence and changes in the general availability of relevant agents and technologies. Conclusions: This guideline provides an evidence-based multidisciplinary approach to the management of critically injured bleeding trauma patients.

The Breakup of Nations: A Political Economy Analysis

Abstract: This paper develops a model of the breakup or unification of nations. In each nation the decision to separate is taken by majority voting. A basic trade-off between the efficiency gains of unification and the costs in terms of loss of control on political decisions is highlighted. The model emphasizes political conflicts over redistribution policies. The main results of the paper are i) when income distributions vary across regions and the efficiency gains from unification are small, separation occurs in equilibrium; and ii) when all factors of production are perfectly mobile, all incentives for separation disappear. I. INTRODUCTION Following the demise of communism, the entire map of Europe, from the Atlantic coast to the Urals, is being redrawn and issues of separation, unification, and the redrawing of borders are yet again at the forefront of European concerns. Many of the issues raised by this process are primarily of a political, cultural, or linguistic nature. However, there are also economic considerations that bear on this problem. The objective of this paper is to analyze some important economic and political determinants of the process of unification and separation of democratic nations. The starting point of our analysis is to suppose that from an economic efficiency point of view, separation of nations is never desirable. A unified nation is always more efficient since free trade among regions is guaranteed, duplication costs in defense and law enforcement are avoided, and local public goods provision (such as transportation and communication networks, or common standards) can be coordinated. Furthermore, any benefits of decentralization that might be obtained in a world with several nations may also be achieved within a unified nation by replicating the administrative structure of the world with several