Itinéraire d’un blogueur : entre quête de reconnaissance et visibilité limitée

On sait que les blogs ont facilité l’accès des usagers de l’Internet à la publication en ligne. Néanmoins, derrière cette simplicité technique relative, la pratique du blogging s’avère semée d’embûches. Par le biais de la trajectoire d’un blogueur, notre intention est d’illustrer ces difficultés et de dévoiler les rouages d’une pratique. Cette trajectoire peut se révéler à la lumière d’une tension, inhérente à l’activité de publication, entre une limitation de ses apparitions et une reconnaissance de la part des pairs, en maintenant leur monde dans une dynamique d’expansion permanente.Blogs are known to have facilitated the access of Internet users to online publication. Nevertheless, behind this comparatively technical simplicity, the practice of blogging appears to be fraught with many traps. Through the trajectory of a blogger, our intention is to illustrate those difficulties and to show up the springs of a practice. That trajectory can be revealed in the light of a tension, inherent to the activity of publication, between peculiar appearances and a recognition on the part of peers by supporting their own world in a dynamics of permanent expansion

Evaluating topology quality through random walks

A distributed system or network can be modeled as a graph representing the "who knows who" relationship. The conductance of a graph expresses the quality of the connectivity. In a network composed of large dense clusters, connected through only a few links, the risk of partitioning is high; this is typically reflected by a low conductance of the graph. Computing the conductance of a graph is a complex and cumbersome task. Basically, it requires the full knowledge of the graph and is prohibitively expensive computation-wise. Beyond the information carried by the conductance of a graph, what really matters is to identify critical nodes from the topology point of view. In this paper we propose a fully decentralized algorithm to provide each node with a value reflecting its connectivity quality. Comparing these values between nodes, enables to have a local approximation of a global characteristic of the graph. Our algorithm relies on an anonymous probe visiting the network in a unbiased random fashion. Each node records the time elapsed between visits of the probe (called return time in the sequel). Computing the standard deviation of such return times enables to give an information to all system nodes, information that may be used by those nodes to assess their relative position, and therefore the fact that they are critical, in a graph exhibiting low conductance. Based on this information, graph improvement algorithms may be triggered. Moments of order 1 and 2 of the return times are evaluated analytically using a Markov chain model, showing that standard deviation of return time is related to the position of nodes in the graph. We evaluated our algorithm through simulations. Results show that our algorithm is able give informations that are correlated to the conductance of the graph. For example we were able to precisely detect bridges in a network composed of two dense clusters connected through a single link

Qu’est ce qu’un algorithme en boîte noire ? Tractatus des décisions algorithmiques

Les entreprises ou institutions (Divinités) désintermédient leurs relations avec les utilisateurs via des algorithmes décisionnels (Pythies) :les usagers (mortels) se voient proposer des décisions arbitraires (oracles) lors de leurs interactions. Comment appréhender ces algorithmesen boîte noire, du point de vue d’un usager ou regulateur

What is a black box algorithm?: Tractatus of algorithmic decision-making

v1.0International audienceCompanies or institutions (Divinities) disintermediate their relations with users via decision-making algorithms (Pythias): users (mortals) are offered arbitrary decisions (oracles) during their interactions.How to apprehend these black box algorithms, from the point of view of a user or regulator

Les Recommandations de YouTube Prédisent les Sondages: Une note sur l’élection présidentielle Française de 2022

We ask if YouTube political recommendations follow the polls performed during the 2022 presidential campaign in France. We find that these recommendations to users, particularly the exposure time in recommended videos, allow for a good prediction of polls, with a daily Mean Absolute Error of solely 3.24% over all candidates. Compared to final election results, polls were 1.11% accurate, whereas our approach was 1.93% accurate.Nous nous demandons si les recommandations politiques de YouTube suivent les sondages réalisés lors de la campagne présidentielle de 2022 en France. Nous constatons que ces recommandations aux utilisateurs, notamment le temps d'exposition des candidats dans les vidéos recommandées, permettent une bonne prédiction des sondages, avec une erreur moyenne absolue quotidienne (MAE) de seulement 3,24% sur l'ensemble des candidats. Par rapport aux résultats finaux des élections, les sondages ont présenté une erreur de 1,11%, alors que celle de notre approche a été de 1,93%

A Timing Assumption and two tt-Resilient Protocols for Implementing an Eventual Leader Service in Asynchronous Shared Memory Systems

This paper considers the problem of electing an eventual leader in an asynchronous shared memory system. While this problem has received a lot of attention in message-passing systems, very few solutions have been proposed for shared memory systems. As an eventual leader cannot be elected in a pure asynchronous system prone to process crashes, the paper first proposes to enrich the asynchronous system model with an additional assumption. That assumption (denoted $\mathit{AWB}$) is particularly weak. It is made up of two complementary parts. More precisely, it requires that, after some time, (1) there is a process whose write accesses to some shared variables be timely, and (2) the timers of $(t-f)$ other processes be asymptotically well-behaved ($t$ denotes the maximal number of processes that may crash, and $f$ the actual number of process crashes in a run). The {\it asymptotically well-behaved} timer notion is a new notion that generalizes and weakens the traditional notion of timers whose durations are required to monotonically increase when the values they are set to increase (a timer works incorrectly when it expires at arbitrary times, i.e., independently of the value it has been set to). The paper then focuses on the design of $t$-resilient $\mathit{AWB}$-based eventual leader protocols. ``$t$-resilient'' means that each protocol can cope with up to $t$ process crashes (taking $t=n-1$ provides wait-free protocols, i.e., protocols that can cope with any number of process failures). Two protocols are presented. The first enjoys the following noteworthy properties: after some time only the elected leader has to write the shared memory, and all but one shared variables have a bounded domain, be the execution finite or infinite. This protocol is consequently optimal with respect to the number of processes that have to write the shared memory. The second protocol guarantees that all the shared variables have a bounded domain. This is obtained at the following additional price: all the processes are required to forever write the shared memory. A theorem is proved which states that this price has to be paid by any protocol that elects an eventual leader in a bounded shared memory model. This second protocol is consequently optimal with respect to the number of processes that have to write in such a constrained memory model. In a very interesting way, these protocols show an inherent tradeoff relating the number of processes that have to write the shared memory and the bounded/unbounded attribute of that memory

Large-scale networked systems: from anarchy to geometric self-structuring

Self-structuring in large-scale networked systems refers to the ability of the participating entities to collaboratively impose a geometric structure to the network. This structure might lead to a geographic organization of nodes or a functional structuring where participating entities get assigned a specific function in the network. Yet, self-structuring is extremely hard to achieve when no global information about the network is available. In this paper, we present the design and the evaluation of a fully decentralized and robust geometric self-structuring approach relying solely on local observation of neighboring connections for sensor networks. This approach heavily relies on the ability of each node to estimate its position in the network, with respect to other nodes. This refers to assigning virtual coordinates to participating nodes. The contribution of the paper is twofold: (i) a simple lightweight and fully decentralized virtual coordinated system (VINCOS) is proposed, relying only on local connectivity information and per-neighbor communication. This is to oppose to most existing approaches relying either on pre-defined positioning referential or signal measurement; (ii) the design and evaluation of a network geometric self-structuring approach (NetGeoS) is presented that enables a large set of nodes to configure themselves in arbitrary geometric structures. The evaluation demonstrates that the approach is both efficient and accurate while achieving the geometric structuring

Accurate Analysis of Tumor Margins Using a Fluorescent pH Low Insertion Peptide (pHLIP)

The recurrence of certain cancers remains quite high due to either incomplete surgical removal of the primary tumor or the presence of small metastases that are invisible to the surgeon. Near infrared (NIR) fluorescence imaging might improve surgical outcomes by providing sensitive, specific, and real-time visualization of normal and diseased tissues if agents can be found that discriminate between normal and diseased tissue and define tumor margins. We have developed a new approach for revealing tumor borders by using NIR fluorescently labeled pH Low Insertion Peptide (pHLIP) and have created a computational program for the quantitative assessment of tumor boundaries. The approach is tested in vivo by co-localization of GFP-tumors and NIR emission from the fluorescently labeled pHLIP, and it is found that boundaries are accurately reported and that sub-millimeter masses can be detected