Existence of Positive Steady States for Mass Conserving and Mass-Action Chemical Reaction Networks with a Single Terminal-Linkage Class

in arXiv preprint arXiv:1105.2359 (2013)

We establish that mass conserving, single terminal-linkage networks of chemical reactions admit positive steady states regardless of network deficiency and the choice of reaction rate constants. This ... [more ▼]

We establish that mass conserving, single terminal-linkage networks of chemical reactions admit positive steady states regardless of network deficiency and the choice of reaction rate constants. This result holds for closed systems without material exchange across the boundary, as well as for open systems with material exchange at rates that satisfy a simple sufficient and necessary condition. Our proof uses a fixed point of a novel convex optimization formulation to find the steady state behavior of chemical reaction networks that satisfy the law of mass-action kinetics. A fixed point iteration can be used to compute these steady states, and we show that it converges for weakly reversible homogeneous systems. We report the results of our algorithm on numerical experiments. [less ▲]

Classes moyennes : des espèces menacées?

Article for general public (2013)

100 ans de politique pragmatique

Article for general public (2013)

CertiCloud and JShadObf. Towards Integrity and Software Protection in Cloud Computing Platforms

Doctoral thesis (2013)

A simple concept that has emerged out of the notion of heterogeneous distributed computing is that of Cloud Computing (CC) where customers do not own any part of the infrastructure; they simply use the ... [more ▼]

A simple concept that has emerged out of the notion of heterogeneous distributed computing is that of Cloud Computing (CC) where customers do not own any part of the infrastructure; they simply use the available services and pay for what they use. This approach is often viewed as the next ICT revolution, similar to the birth of the Web or the e-commerce. Indeed, since its advent in the middle of the 2000's, the CC paradigm arouse enthusiasm and interest from the industry and the private sector, probably because it formalizes a concept that reduces computing cost at a time where computing power is key to reach competitiveness. Despite the initiative of several major vendors to propose CC services (Amazon, Google, Microsoft etc.), several security research questions remain open to transform the current euphoria into a wide acceptance. Moreover, these questions are not always tackled from the user's point of view. In this context, the purpose of this thesis is to investigate and design novel mechanisms to cover the following domains: - Integrity and confidentiality of Infrastructure-as-a-Service (IaaS) infrastructures, to provide guarantees on programs and data running in a virtualised environment, either before, during or after a deployment on the CC platform. - Software protection on Software-as-a-Service (SaaS) and Platform-as-a-Service (PaaS) architectures, using code obfuscation techniques. This dissertation details thus two main contributions. The first one is the development and implementation of CertiCloud, a CC framework which relies on the concepts developed in the Trusted Computing Group (TCG) together with hardware elements, i.e., Trusted Platform Module (TPM) to offer a secured and reassuring environment within IaaS platforms. At the heart of CertiCloud reside two protocols: TCRR and VerifyMyVM. When the first one asserts the integrity of a remote resource and permits to exchange a private symmetric key, the second authorizes the user to detect trustfully and on demand any tampering attempt on its running VM. These protocols being key components in the proposed framework, their analysis against known cryptanalytic attacks has been deeply analysed and testified by their successful validation by AVISPA [1] and Scyther [66], two reference tools for the automatic verification of security protocols. The second major contribution proposed in this manuscript is an obfuscation framework named JShadObf, designed to improve the protection of Javascript-based software running typically on SaaS and PaaS platforms. This framework combines obfuscation transformations, code complexity measurements and Multi-Objective Evolutionary Algorithms (MOEAs) to protect Javascript code, the most ubiquitous programming language at the heart of most modern web services deployed over those CC infrastructures such as Google Office Apps, Dropbox or Doodle. [less ▲]

Maximal Surface in AdS convex GHM 3-manifold with particles

E-print/Working paper (2013)

We prove the existence of a unique maximal surface in an anti-de Sitter (AdS) convex Globally Hyperbolic Maximal (GHM) manifold with particles (i.e. with conical singularities along timelike lines) for ... [more ▼]

We prove the existence of a unique maximal surface in an anti-de Sitter (AdS) convex Globally Hyperbolic Maximal (GHM) manifold with particles (i.e. with conical singularities along timelike lines) for cone-angles less than $\pi$. We reinterpret this result in terms of Teichm\"uller theory, and prove the existence of a unique minimal Lagrangian diffeomorphism isotopic to the identity between two hyperbolic structures with conical singularities of the same angles on a closed surface with marked points. [less ▲]

Riemann Surfaces. Lecture notes. Winter semester 2013/2014.

Learning material (2013)

This is a preliminary version of lecture notes for the course 'Riemann surfaces' (14 Lectures, 90 minutes each).

Die Verteidigung der osteuropäischen Firmenbeteiligungen der Arbed in der Nachkriegszeit

Doctoral thesis (2013)

CHD4 Is a RanGTP-Dependent MAP that Stabilizes Microtubules and Regulates Bipolar Spindle Formation

in Current Biology (2013), 23(24), 2443-2451

Background Production of the GTP-bound form of the Ran GTPase (RanGTP) around chromosomes induces spindle assembly by activating nuclear localization signal (NLS)-containing proteins. Several NLS proteins ... [more ▼]

Background Production of the GTP-bound form of the Ran GTPase (RanGTP) around chromosomes induces spindle assembly by activating nuclear localization signal (NLS)-containing proteins. Several NLS proteins have been identified as spindle assembly factors, but the complexity of the process led us to search for additional proteins with distinct roles in spindle assembly. Results We identify a chromatin-remodeling ATPase, CHD4, as a RanGTP-dependent microtubule (MT)-associated protein (MAP). MT binding occurs via the region containing an NLS and chromatin-binding domains. In Xenopus egg extracts and cultured cells, CHD4 largely dissociates from mitotic chromosomes and partially localizes to the spindle. Immunodepletion of CHD4 from egg extracts significantly reduces the quantity of MTs produced around chromatin and prevents spindle assembly. CHD4 RNAi in both HeLa and Drosophila S2 cells induces defects in spindle assembly and chromosome alignment in early mitosis, leading to chromosome missegregation. Further analysis in egg extracts and in HeLa cells reveals that CHD4 is a RanGTP-dependent MT stabilizer. Moreover, the CHD4-containing NuRD complex promotes organization of MTs into bipolar spindles in egg extracts. Importantly, this function of CHD4 is independent of chromatin remodeling. Conclusions Our results uncover a new role for CHD4 as a MAP required for MT stabilization and involved in generating spindle bipolarity. © 2013 Elsevier Ltd. [less ▲]

States of Education: Reflections on the Relationship between Welfare State and Education in Finland and the Federal Republic of Germany

Doctoral thesis (2013)

This PhD thesis examines the impact of political ideologies on the welfare state developments of the Republic of Finland and Federal Republic of Germany. It explores the issue by asking whether different ... [more ▼]

This PhD thesis examines the impact of political ideologies on the welfare state developments of the Republic of Finland and Federal Republic of Germany. It explores the issue by asking whether different ideas of ruling parties mattered in these developments or were there other factors, such as the level of economic strength, which became more influential in explaining cross-national welfare variations. Whereas mainstream analysts of comparative social policy since the early 1990s have taken for granted that politics mattered in the immediate post-war era reflecting the more pronounced left-right, catholic-protestant and other historical cleavages, this research moves beyond the oversimplified traditional welfare regime typologies and instead considers how welfare systems became intertwined with other more control-focused aspects of state development: in effect, whether and how they became instruments of discipline through educating citizens. Drawing on the Foucauldian idea of power of normalisation – and using educational expansion of the 1960s as a case study – it is suggested that there are aspects of the development of Finnish and West German policing which had a direct bearing on the emergence of the welfare state. [less ▲]

Computational Tools for Mass Spectrometry Based Metabolic Profiling

Doctoral thesis (2013)