Journal Staff

Imaging is an invaluable tool in many research areas and other advanced domains such as health care. When developing any system dealing with images, image quality issues are insurmountable. This report describes digital image quality from many viewpoints, from retinal receptor characteristics to perceptual compression algorithms. Special focus is given to perceptual image quality measures

Absorbed power of small children

Objective. To experimentally measure the seated vertical direction whole-body absorbed power characteristics of small children less than 18 kg in mass. Background. Several studies have reported whole-body absorbed power for adult humans, but no data has been published previously for small children. Methods. Eight children were tested in a laboratory test rig which incorporated safety features which satisfy existing international standards for human testing. Force and acceleration were measured at the point of input to a rigid seat at a sampling rate of 200 Hz, and analysis was performed over the interval from 1.0 to 45.0 Hz. A double normalised (both input acceleration and test subject mass) measure of absorbed power was used. Results. The vertical whole-body power absorption characteristics of the small children were found to present differences with respect to those of adults. The mean frequency of peak absorption was found to be 7.4 Hz as opposed to approximately 4.0–5.0 for adults. The interval of absorption was found to be from approximately 3 to 16 Hz and the total double normalised absorbed power was found to be 86% that of adults. Conclusions. The differences in dynamic response between small children and adults raise questions regarding the applicability of whole-body vibration guidelines such as ISO-2631 in the case of small children since these guidelines were developed from mechanical and subjective response data of adults

Miyashita Action in Strongly Groupoid Graded Rings

We determine the commutant of homogeneous subrings in strongly groupoid graded rings in terms of an action on the ring induced by the grading. Thereby we generalize a classical result of Miyashita from the group graded case to the groupoid graded situation. In the end of the article we exemplify this result. To this end, we show, by an explicit construction, that given a finite groupoid $G$, equipped with a nonidentity morphism $t : d(t) \to c(t)$, there is a strongly $G$-graded ring $R$ with the properties that each $R_s$, for $s \in G$, is nonzero and $R_t$ is a nonfree left $R_{c(t)}$-module.Comment: This article is an improvement of, and hereby a replacement for, version 1 (arXiv:1001.1459v1) entitled "Commutants in Strongly Groupoid Graded Rings

Noncrossed Product Matrix Subrings and Ideals of Graded Rings

We show that if a groupoid graded ring has a certain nonzero ideal property and the principal component of the ring is commutative, then the intersection of a nonzero twosided ideal of the ring with the commutant of the principal component of the ring is nonzero. Furthermore, we show that for a skew groupoid ring with commutative principal component, the principal component is maximal commutative if and only if it is intersected nontrivially by each nonzero ideal of the skew groupoid ring. We also determine the center of strongly groupoid graded rings in terms of an action on the ring induced by the grading. In the end of the article, we show that, given a finite groupoid $G$, which has a nonidentity morphism, there is a ring, strongly graded by $G$, which is not a crossed product over $G$

Commutativity and Ideals in Category Crossed Products

In order to simultaneously generalize matrix rings and group graded crossed products, we introduce category crossed products. For such algebras we describe the center and the commutant of the coefficient ring. We also investigate the connection between on the one hand maximal commutativity of the coefficient ring and on the other hand nonemptyness of intersections of the coefficient ring by nonzero twosided ideals

Foucault in Cyberspace: Surveillance, Sovereignty, and Hardwired Censors

This is an essay about law in cyberspace. I focus on three interdependent phenomena: a set of political and legal assumptions that I call the jurisprudence of digital libertarianism, a separate but related set of beliefs about the state\u27s supposed inability to regulate the Internet, and a preference for technological solutions to hard legal issues on-line. I make the familiar criticism that digital libertarianism is inadequate because of its blindness towards the effects of private power, and the less familiar claim that digital libertarianism is also surprisingly blind to the state\u27s own power in cyberspace. In fact, I argue that the conceptual structure and jurisprudential assumptions of digital libertarianism lead its practitioners to ignore the ways in which the state can often use privatized enforcement and state-backed technologies to evade some of the supposed practical (and constitutional) restraints on the exercise of legal power over the Net. Finally, I argue that technological solutions which provide the keys to the first two phenomena are neither as neutral nor as benign as they are currently perceived to be. Some of my illustrations will come from the current Administration proposals for Internet copyright regulation, others from the Communications Decency Act and the cryptography debate. In the process, I make opportunistic and unsystematic use of the late Michel Foucault\u27s work to criticise some the jurisprudential orthodoxy of the Net