Spectral coarse-graining of complex networks

Reducing the complexity of large systems described as complex networks is key to understand them and a crucial issue is to know which properties of the initial system are preserved in the reduced one. Here we use random walks to design a coarse-graining scheme for complex networks. By construction the coarse-graining preserves the slow modes of the walk, while reducing significantly the size and the complexity of the network. In this sense our coarse-graining allows to approximate large networks by smaller ones, keeping most of their relevant spectral properties.Comment: 4 pages, 2 figure

Finding instabilities in the community structure of complex networks

The problem of finding clusters in complex networks has been extensively studied by mathematicians, computer scientists and, more recently, by physicists. Many of the existing algorithms partition a network into clear clusters, without overlap. We here introduce a method to identify the nodes lying ``between clusters'' and that allows for a general measure of the stability of the clusters. This is done by adding noise over the weights of the edges of the network. Our method can in principle be applied with any clustering algorithm, provided that it works on weighted networks. We present several applications on real-world networks using the Markov Clustering Algorithm (MCL).Comment: 4 pages, 5 figure

“As a vegetarian, we never do well enough”: Positioning in the normative landscape of meat consumption.

Food is an area that receives little attention from psychologists, despite the fact that it provides many interesting situations and dilemmas through which human activity and development can be examined. Currently – at least in the WEIRD (western, educated, industrial, rich and democratic) countries (Henrich et al., 2010), – these activities are an important object of normative discourses and injunctions about how we should behave as consumers and how we should eat, notably when it comes to products of animal origin and meat in particular. In these countries, a large majority of people regularly consumes meat. Vegetarianism can be seen as a deviant behavior to this norm (Boyle, 2011), that provokes reactions as it questions the taken-for-granted normality and necessity of meat consumption (Larue, 2015). However, the issue of meat consumption also intersects with many other normative discourses, such as the imperatives to be an ethical consumer or to be a hedonist. In this paper, I examine how people orient themselves in relation to these norms and possibly take distance from some of them. More specifically I propose to do so through the notion of positioning. Position and positioning are notions that are increasingly used and discussed in psychology. The theorization of these notions is recent, and thus quite disparate (Gülerce et al., 2014), although a few scholars worked on possible synthesis of different traditions (Gillespie & Martin, 2014; Raggatt, 2015). I argue that examining positioning processes in relation to normative discourses and behaviors constitutes a way to understand the relation between the person and some social norms, and that this use will also contribute to deepen the conceptualization of positioning. I draw on empirical work conducted with people who recently changed their habits of consumption of food of animal origin. The questions I examine are: how do people position themselves in the normative and contested world of consumption of food of animal origin, and what are the processes possibly allowing them to question and transgress the norms in this area

Die offenen Spulen : das elektromagnetische Atelier ; eine kurze begriffliche Rückschau auf Schweizerisches Videoschaffen vor 1980

Im Rahmen einer Vortragsreihe am Schweizerischen Institut für Kunstwissenschaft in Zürich, die unter dem Mollo "Tankstelle USA" verschiedene Facetten amerikanisch-schweizerischer {Wechsel-)Wirkungen thematisierte, fiel mir die Ehre zu, Ober das Verhältnis von amerikanischer und schweizerischer Videokunst zu referieren. Das Korpus, besonders in Übersee, ist umfangreich: weniger die Gefahr, etwas zu Obersehen, als alles vermeintlich zu Oberblicken, legte eine Schwerpunktsetzung nahe. Obgleich von der Schweizer Kunstgeschichte bisher mehrheitlich verschlafen (die Einladung ans SIK gehört wohl zu den noch seltenen und löblichen Erwachnissen ... ), ist ja Video längst nicht mehr die monothematische Sparte, die es zwar nie war, aber die es in den Augen so mancher auch professioneller .. Kunstinteressierter .. noch 150 Jahre bleiben wird : wir erinnern uns an das nie ausdiskutierte Verhältnis von Kunst und Fotografie. ..

Kunstfehler! Elektrisch, elektronisch, digital : fünf vor zwölf zeigt die Uhr allemal ; für einen historisch informierten Umgang mit Medienkunst

The conservation and reconstruction of electronic art poses achallenge in terms of both restoration and art history. The former discipline still tends to lack the necessary technical means, while the latter lacks the descriptive tools: As concrete instances of worn-out or defective hardware or by no unplayable tapes have long been accumulating, conservational practice, where implemented, often finds itself on uncertain terrain and all too quickly seeks technocratic solutions: video tapes are copied with no thought of long-term perspectives, latterly under the motto 'digital = unproblematic', with defective devices simply being replaced by new equipment. A more selective approach would start with a better understanding of such works and allow an assessment, from case to case, of the extent to which tangible replacements can be tolerated, and from what point on they endanger the integrity of the work. This presupposes knowledge of the way works are shown but also of the characteristics of the equipment used to produce images, such as cameras, monitors or projectors. In conjunction with a process of documentation begun when the work is new, the piece can still receive an authentic showing later on, when its physical integrity is no longer guaranteed. This historically informed approach does not attempt to lend a work 'eternal youth' through continual restoration, which would make the work appear more modern than it ever was; rather it accepts that quality, perhaps even functionality, will sometimes be impaired, compensating for these losses by way of (media-based) documentation - for the sake of historical integrity. If conservation is taken seriously from the very moment of acquisition and if the 'use' of a work is sensibly limited from the start, its integrity and then authenticity can probably be preserved for a far longer period.Auch wenn es in der Regel eilt: bevor man ein Kunstwerk erhalten kann, muss man es angemessen zu beschreiben wissen, sonst läuft man Gefahr, grobe Fehler zu begehen. Dies gilt für ein Werk auf Basis "alter" Materialien wie Stein, Holz, Leinwand, Fasern, Bindemittel und Pigmente, dies gilt in nicht geringerem Masse für ein Werk, das moderne Materialien enthält: Kunststoffe, synthetische Farben, Halbleiter und elektromagnetische Felder. Die Definition dessen, was eigentlich das elektronische Kunstwerk ausmacht, führt mitten in die Thematik, was zu berücksichtigen und was zu unternehmen ist, wenn das Werk vom Neuzustand in die Alterungsphase eintritt. ..

Pixels and lines to frame : the building-blocks for a theory on preserving media

With the discovery of moving pictures around 1880, a paradigm change took place that decisively altered human perception. With the advent of electronic images, the separation between information carriers and image carriers was consummated in a radical way during the second half of the 20th century – we assume this to be a paradigm change as important as that of 120 years ago. Because, as a result of a delay in knowledge, electronic images today are all too generously labelled ‘digital’, but fail to be explained by that designation, a formal classification into analogue and digital, hardware and software appears indispensable both for understanding and for preserving this type of media (art). This reveals that it is not at all the case that we simply live in the digital age and from now on can pass on our cultural artefacts without loss. Quite the contrary: abandoning the originals – and in media art, this just happens to include also the display devices with their techno-cultural specificities – is threatening to bring about a knowledge surrogate very soon, right under our nose so to speak, encouraging a precarious relationship between action and history. In this sense, the text is also intended as a critique of the ‘Variable Media Initiative’ which – paradoxically, with regard to art being passed on on a very long-term basis – threatens to abandon the material basis of a number of contemporary works of art. The independence of information carriers and display devices has led to specialised sensitivities, making it extremely difficult to bring together works in their entirety.Der französische Physiologe Etienne-Jules Marey (1830–1904) gehörte vor 120 Jahren zu den Protagonisten eines Paradigmenwechsels. Als Pionier der Bewegungsanalyse mit mechanisch-pneumatischen Aufzeichnungssystemen wandte er sich in dem Moment der Fotografie zu, als diese Kurzzeitbelichtungen zu erlauben begann. Das war die notwendige Bedingung dafür, Serienaufnahmen in genügend kurzer Abfolge machen zu können; die hinreichenden Apparaturen hatte er sich selber zu bauen. Chronofotografie hiess das Projekt, das am Anfang des wissenschaftlichen Films schlechthin stand und das so wenig mit dem grossen K von Kino zu tun hatte, dass Marey in filmgeschichtlicher Hinsicht stets im selbst gewählten Schatten der Brüder Lumière und Thomas Edisons stand. ..

Video : das erste Jahrzehnt ; Recherchen zu einem kurzlebigen Medium im Kontext einer Fernsehsendung als Beitrag von René Pulfer

Geschichte ist nicht nur der Bodensatz einer einstmals frisch angerührten Mixtur, die wir jeweils als Gegenwart zu fassen versuchen - sie kann sich dann und wann auch als Bodenschatz erweisen, auf den damals Beteiligte wie Nachgeborene Schürfrechte beanspruchen. Nicht alles, was einmal war, wird dabei zutage gefördert: "Fortschritt" beinhalet bekanntlich auch Verluste vielfältigster Art - als handelte es sich um zwei Seiten eines Blattess Papier. Wir haben also über das Verschwinden zu sprechen. ..