Getting Close Without Touching: Near-Gathering for Autonomous Mobile Robots

In this paper we study the Near-Gathering problem for a finite set of dimensionless, deterministic, asynchronous, anonymous, oblivious and autonomous mobile robots with limited visibility moving in the Euclidean plane in Look-Compute-Move (LCM) cycles. In this problem, the robots have to get close enough to each other, so that every robot can see all the others, without touching (i.e., colliding with) any other robot. The importance of solving the Near-Gathering problem is that it makes it possible to overcome the restriction of having robots with limited visibility. Hence it allows to exploit all the studies (the majority, actually) done on this topic in the unlimited visibility setting. Indeed, after the robots get close enough to each other, they are able to see all the robots in the system, a scenario that is similar to the one where the robots have unlimited visibility. We present the first (deterministic) algorithm for the Near-Gathering problem, to the best of our knowledge, which allows a set of autonomous mobile robots to nearly gather within finite time without ever colliding. Our algorithm assumes some reasonable conditions on the input configuration (the Near-Gathering problem is easily seen to be unsolvable in general). Further, all the robots are assumed to have a compass (hence they agree on the "North" direction), but they do not necessarily have the same handedness (hence they may disagree on the clockwise direction). We also show how the robots can detect termination, i.e., detect when the Near-Gathering problem has been solved. This is crucial when the robots have to perform a generic task after having nearly gathered. We show that termination detection can be obtained even if the total number of robots is unknown to the robots themselves (i.e., it is not a parameter of the algorithm), and robots have no way to explicitly communicate.Comment: 25 pages, 8 fiugre

Touching Freud's dog: H.D.'s tactile poetics

"Do not touch me", Frau Emmy warns Freud in 1889. "Do not touch", Freud echoes in 1933. This time, he is referring to his pet chow, Yofi, warning H.D. that "she snaps - she is very difficult with strangers". Examining the prohibition in light of work by Jacques Derrida and Jean-Luc Nancy, this article charts the withdrawal that always interrupts touch. Despite Freud's taboo, however, H.D.'s writing seeks to make contact in strange and unnerving ways. Developing Julia Kristeva's account of the semiotic, this paper proposes a literature of touch. Reading H.D.'s poems, alongside Tribute to Freud, and her letters, the author demonstrates that H.D.'s poetics are always haunted by the very (im)possibility of contact

Influence of solvent granularity on the effective interaction between charged colloidal suspensions

We study the effect of solvent granularity on the effective force between two charged colloidal particles by computer simulations of the primitive model of strongly asymmetric electrolytes with an explicitly added hard sphere solvent. Apart from molecular oscillating forces for nearly touching colloids which arise from solvent and counterion layering, the counterions are attracted towards the colloidal surfaces by solvent depletion providing a simple statistical description of hydration. This, in turn, has an important influence on the effective forces for larger distances which are considerably reduced as compared to the prediction based on the primitive model. When these forces are repulsive, the long-distance behaviour can be described by an effective Yukawa pair potential with a solvent-renormalized charge. As a function of colloidal volume fraction and added salt concentration, this solvent-renormalized charge behaves qualitatively similar to that obtained via the Poisson-Boltzmann cell model but there are quantitative differences. For divalent counterions and nano-sized colloids, on the other hand, the hydration may lead to overscreened colloids with mutual attraction while the primitive model yields repulsive forces. All these new effects can be accounted for through a solvent-averaged primitive model (SPM) which is obtained from the full model by integrating out the solvent degrees of freedom. The SPM was used to access larger colloidal particles without simulating the solvent explicitly.Comment: 14 pages, 16 craphic

A journey to soul-touching research in social sciences and humanities

We researchers in the humanities and social sciences, similar to the archaeologists but only less literally, are constantly digging through unknown dirt and even uncharted territories in hopes of finding “diamonds.

Touching the void: affective history and the impossible

In order to understand the persistence of History, we need to understand the appeal of historical work, its pleasures. Without such an understanding, theory and research will continue to talk at cross purposes, the one insisting that the past is unknowable; the other unable to ignore the vitality of its sources. The contention of this essay is that historical research is an affective experience of such intensity that it has been able to withstand the challenges of post-structuralism and postmodernism and so continue with ‘business as usual’ (Jenkins 2003, 15). While the intensity of the archival encounter is not often admitted in print, it continues to motivate the efforts of individual historians. The abstractions of theory cannot intrude upon the physical experience of holding a piece of the past. It demands our attention. But the intellectual consequences of the physicality of the archival encounter need to be effectively theorised: what is the role of touching and feeling in the pursuit of knowing? The archive is the place where historians can literally touch the past, but in doing so are simultaneously made aware of its unreachability. In a maddening paradox, concrete presence conveys unfathomable absence. In the archive, researchers are both confronted with the absolute alterity of the past and tempted by the challenge of trying to overcome it. It is suggested that this impossibility underpins the powerful attraction of the historical endeavour

Don’t touch! hands off! art, blindness and the conservation of expertise

The embargo on touching in museums is increasingly being brought into question, not least by blind activists who are calling for greater access to collections. The provision of opportunities to touch could be read as a potential conflict between established optic knowledge and illicit haptic experience, between the conservation of objects and access to collections. Instead I suggest that touch is not necessarily other to the museum; rather, the status of who does the touching and knowing is crucial and not the use of touch per se. It is expert territory and vested academic interests that are at stake here. Using Bruno Latour’s (1993) conceptions of hybrid networks and purified zones of academic practice, I then explore what the unacknowledged existence of touch means for museums and for notions of authority more generally. I suggest that if the apparent boundaries of disciplines are unconvincing in practice, then the possibility of expert knowledge is seriously undermined. Blind people’s demand for access through touch is not then a challenge of one paradigm to another but implicitly questions the accreditation of authority itself. As such it forms part of a wider institutional shift with regard to expertise and an increased need for negotiating between different conceptual frameworks. The ocularcentric bias of museums is increasingly being questioned by blind and visually impaired visitors who emphasize touch as a learning and aesthetic experience. This challenge is contentious not least because it ostensibly brings the individuals’ rights of access into direct conflict with museum conservation. I argue that concerns over conservation can, however, mask and serve to legitimate preconceptions about who should have access to collections; what counts as damage or dirt; and the means by which art and artefacts can be understood or enjoyed. It is expertise rather than the conservation of objects which is at stake. This article suggests that in campaigning for access through touch, blind people physically move beyond the barriers which reserve contact for the museum elite and simultaneously establish the viability of learning in a way that is not sanctioned by the art historical community. Thus resistance to touch in museums is not so much a concern for preservation as a defence of territory and expertise

The Pond

A collection of creative texts written concurrently with the creation of the artist’s thesis exhibition. A range of written forms coexist - poetry, prose, and dialogue - to open up the narrative and emotional space of the visual work. The text emerges from the point-of-view of different voices, describing experiences and body states that hinge upon the physical and conceptual space of the pond. Amphibiousness offers a gateway to a state of becoming and transformation. Some of the following texts appear in video works by the artist

Communicable Diseases and the Workplace

[Excerpt] Coming to work when we are sick raises some interesting questions: How contagious are we? Should we stay home? What could be done to prevent disease transmission to others, with its effects on absenteeism, performance, and efficiency, as well as in the interests of public health? Is working from home an option? Shouldn’t the employer provide sick leave or flextime to discourage working when sick? Without sick leave, aren’t people more likely to go to work sick, as well as send sick kids to school? Should an employer sponsor, or even require, vaccinations? When trying to change policy and attitudes on communicable infectious diseases in the workplace, there is a good business case to be made. Workplaces traditionally plan for a variety of crises – especially infrastructure damage and its recovery – but planning and prevention for diseases seems to get overlooked, despite its very significant cost in both human suffering and dollars. Some diseases that have had a costly impact on businesses include mumps, measles, norovirus, SARS, tuberculosis, and whooping cough