Holographic RG flows and nearly-marginal operators

The holographic renormalization group flows associated with marginally relevant operators are analyzed. The associated perturbative and non-perturbative beta-functions are calculated and the consistent scalar potentials are identified. The presence of a Zamolodchikov metric in the multiscalar case is shown to affect beta-functions starting at two loops.Comment: Latex, 23 pages. Minor corrections. Version to be published in Classical and Quantum Gravit

The exact Schur index of N=4\mathcal{N}=4 SYM

The Witten index counts the difference in the number of bosonic and fermionic states of a quantum mechanical system. The Schur index, which can be defined for theories with at least $\mathcal{N}=2$ supersymmetry in four dimensions is a particular refinement of the index, dependent on one parameter $q$ serving as the fugacity for a particular set of charges which commute with the hamiltonian and some supersymmetry generators. This index has a known expression for all Lagrangian and some non-Lagrangian theories as a finite dimensional integral or a complicated infinite sum. In the case of $\mathcal{N}=4$ SYM with gauge group $U(N)$ we rewrite this as the partition function of a gas of $N$ non interacting and translationally invariant fermions on a circle. This allows us to perform the integrals and write down explicit expressions for fixed $N$ as well as the exact all orders large $N$ expansion.Comment: 11 pages; v2: typos correcte

The N=2\mathcal{N}=2 Schur index from free fermions

We study the Schur index of 4-dimensional $\mathcal{N}=2$ circular quiver theories. We show that the index can be expressed as a weighted sum over partition functions describing systems of free Fermions living on a circle. For circular $SU(N)$ quivers of arbitrary length we evaluate the large $N$ limit of the index, up to exponentially suppressed corrections. For the single node theory ($\mathcal{N}=4$ SYM) and the two node quiver we are able to go beyond the large $N$ limit, and obtain the complete, all orders large $N$ expansion of the index, as well as explicit finite $N$ results in terms of elliptic functions.Comment: 36 pages, 1 figure; v2: Minor corrections, version published in JHEP; v3: Minor correction

Vortex-induced vibrations of a non-linearly supported rigid cylinder

Vortex-Induced Vibrations (VIV) are a complex fluid-structure interaction problem.VIV are particularly strong for low-mass structures subject to a low damping, asencountered in the offshore industry, in which structures experiencing VIV can alsobe subject to strong structural non-linearities.In this project, investigation of the VIV of a low-mass low-damping rigid cylindersubject to structural non-linearities is carried out first experimentally. Non-linearitiesconsidered are the symmetric or asymmetric limitation of the amplitude of thecylinder with soft or stiff stops placed at different offsets from the cylinder andimplying a non-smooth non-linearity of the system. Experimental results show that astrong perturbation of the dynamics of the cylinder occurs when amplitude limitationis strong, and flow visualisations displaying a modification of the vortex wake suggesta change in the fluid-structure interaction affecting the vortex formation process.Attention is also given to the impact velocities in the different cases of amplitudelimitation with stiff stops, as they are an important factor in the design of structures.Two different wake oscillator models are then used to simulate the VIV of the samerigid circular cylinder in the same conditions of non-linear structural restraints.Results show that these simple models exhibit some features observed experimentally,giving in some cases a good estimation of the experimental data

From Confrontation to Mediation: Cambodian Farmers Expelled by a Vietnamese Company

Concessions granted to investors in Cambodia have generated a deep sense of insecurity in rural forested areas. Villagers are not confined to a passive “everyday resistance of the poor,” as mentioned by James Scott, insofar as they frequently engage in frontal strategies for recovering land. Such has been the case in the northeastern provinces, where indigenous livelihoods are recurrently threatened by foreign and national companies. But what happens when a land conflict ends up in a stakeholder dialogue? The article intends to follow such a story that occurred for the first time in Ratanakiri, in a vast territory inhabited by several ethnic groups. After gruelling hostilities with the encroacher, dispossessed farmers finally accepted, encouraged by international/national NGOs, to comply with existing mechanisms associated with international law regulations and World Bank procedures. It ends up in an institutionalised mediation, technical and apolitical, which turned to the disadvantage of the people, with evident power imbalance. Our analysis, while portraying the trajectories of national/international actors involved in the mediation process, reveals the effects on this mediation on local sociopolitical organisations

Odniesienie do nieobecności w angielskich sekwencjach no + N i w sekwencjach pas de + N i / lub aucun + N w języku francuskim

This paper enquires into the field of negative noun determination in English and in French. It focuses on the English sequences ‘No + countable noun in the singular’ (No + N-Ø) and ‘No + count­able noun in the plural’ (No + N-s), and some of their possible translations in French, namely aucun or pas de, followed by a noun either in the singular or in the plural.The existence in English of the two sequences raises the question of the differences in meaning these two sequences convey and induces one to examine their French possible translations with pas de or aucun. The aim thus is to examine examples in which both constructions are grammatically allowed in English, in order to elucidate the process through which reference is construed, and to examine the similarities and differences in meaning in the French sequences resorting to aucun or pas de. An analysis of each of the constructions will lead us to investigate the linguistic features, pertaining to sets of properties and occurrences, subjective and argumentative factors, which may or may not imply patterns of correspondences through translation. We will address these issues via the examination of translated examples taken from a parallel corpus made up of extracts from contemporary novels written in English after 1980 and of their translations into French.In English, no marks an impossible scanning operation either over a set of items defined in a space and time frame, with a noun in the plural, or over an open set defined according to proper­ties, with a noun in the singular.We have determined that in French, differentiating between two markers depends on defining a different linguistic operation for each of them: a scanning operation for aucun and a blocking of validation for pas de. We have further proved that the meanings construed by their respective operations agreed with their contextual environment.Niniejszy artykuł wkracza w dziedzinę uwarunkowań dotyczących połączeń rzeczownika ze znakiem negacji w języku angielskim i francuskim. Koncentruje się na angielskich ciągach “No + policzalny rzeczownik w liczbie pojedynczej” (No + N-Ø) i “No + policzalny rzeczownik w liczbie mnogiej” (No + N-s) i niektórych z ich możliwych tłumaczeniach w języku francuskim: aucun lub pas de, po którym następuje rzeczownik w liczbie pojedynczej lub w liczbie mnogiej.Istnienie w języku angielskim takich dwóch sekwencji rodzi pytanie o różnice w ich znaczeniu i nakłania do zbadania ich francuskich możliwych tłumaczeń za pomocą pas de lub aucun. Celem jest zatem zbadanie przykładów, w których obie konstrukcje są gramatycznie dopuszczalne w języku angielskim, w celu wyjaśnienia procesu, za pomocą którego interpretowane jest ich odniesienie, oraz w celu zbadania podobieństw i różnic w znaczeniu sekwencji francuskich wykorzystujących aucun lub pas de.Analiza każdej z konstrukcji rzeczownikowej doprowadzi nas do zbadania cech językowych, odnoszących się do zestawów właściwości oraz zdarzeń, czynników subiektywnych i argumentacyjnych, które mogą (lub nie) implikować poprzez tłumaczenie schematy zależności. Zajmiemy się tymi zagadnieniami, badając przetłumaczone przykłady zaczerpnięte z korpusu paralelnego złożonego z fragmentów współczesnych powieści napisanych po angielsku po 1980 roku i ich tłumaczeń na język francuski.W języku angielskim no oznacza niemożliwą operację skanowania zarówno na zestawie ele­mentów zdefiniowanych w ramie przestrzeni i czasu – z rzeczownikiem w liczbie mnogiej, jak i w otwartym zestawie zdefiniowanym według właściwości – z rzeczownikiem w liczbie poje­dynczej.Ustaliliśmy, że w języku francuskim rozróżnianie dwóch markerów zależy od zdefiniowania różnych operacji językowych dla każdego z nich: skanowania dla aucun i blokowania walidacji dla pas de.Udowodniliśmy ponadto, że znaczenia interpretowane przez ich działania są zgodne z ich kontekstowym otoczeniem