Viscosity of an ideal relativistic quantum fluid: A perturbative study

We show that a quantized ideal fluid will generally exhibit a small but non-zero viscosity due to the backreaction of quantum soundwaves on the background. We use an effective field theory expansion to estimate this viscosity to first order in perturbation theory. We discuss our results, and whether this estimate can be used to obtain a more model-independent estimate of the "quantum bound" on the viscosity of physical systemsComment: Accepted for publication, Phys.Rev.D. Discussion slightly clarified and extended, references added, error in calculation fixed. COnclusions unchange

Défence d’afficher: An exhibition -and- From snap-shot photography to digital printmaking via the concept of the flâneur: An exegesis

The aim of this research project was to consider the construction of meaning within visual arts, with a view to possible applications of the concept of the flâneur as method of research. My purpose was to open new insights into the experience of everyday life through a consideration of peripheral phenomena. I formulated this as a concept through my artwork and retraced a history of development via a background of artists who paradoxically create artworks from debris. I focused on the practice of a small group of French, German and Italian artists who called themselves the “Affichistes”, in referral to the torn and shredded posters (“affiche” is the French word for poster) they use to make their art work, in a process called décollage, meaning the reverse of collage. An element of absurdity, embedded in the concept of making art by bringing debris into the gallery and thereby proposing a re-examination of commonly accepted cultural values, refers to a critical evaluation of seemingly absurd socio-economic aspects of mainstream culture that were part of the impulse initiating the wide spread counter-cultural movement associated with the 1960s. My art practice aims to bring attention to incidental photography, the principle of décollage, as well as the method of the flâneur. Using the methodology of practice-led research, I have enquired into visual aspects of public urban spaces and into the use of these spaces in contemporary visual art. The studio practice was divided into three parts. Fieldwork was conducted in and around the Perth metropolitan area, as well as on various locations in Germany and France, during two short stays in February and November 2017. The printmaking practice was conducted in various studios in Perth, Western Australia. The project also extended to a four-week residency at the University of Western Australia’s ARTLAAB studio, including an exhibition during the month of June 2017. Arising from the ARTLAAB residency, a substantial body of work was developed and produced, including digital prints, a light box, as well as a sculptural installation. An exegesis and exhibition demonstrated the aesthetic as well the conceptual potential of décollage in conjunction with the concept of the flâneur used as a research method. The method of the flâneur was explored in terms of a perambulating manner of gathering data, in form of snap-shot photography as a way of sketching found images relating to the aesthetic of the “Affichistes”. The studio practice developed these images into the artworks exhibited in “Défence d’afficher”. The perambulating manner also applied to the literature consulted for this research, encompassing, apart from academic texts, a wide variety of haphazardly gathered literary sources, such as novels, daily newspapers and magazines, rock-music lyrics and information gleaned from private conversations and personal observation

Guidelines for the use and interpretation of assays for monitoring autophagy

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Guidelines for the use and interpretation of assays for monitoring autophagy

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field