A transient digitiser for fast air shower events

Air shower structure are often measured on time scales of a few nanoseconds. Longitudinal disk structure near the core is of the order of meters in dimension, air Cerenkov pulses have full widths at half maximum of the order of tens of nanoseconds, and fast timing over typical arrays is usually measured to nanosecond accuracy. oscilloscopes can be used but have very limited dynamic range and are expensive if measurements down to a few nanoseconds are to be made. For the fast Cerenkov work, an instrument with better dynamic range than an oscilloscope and with a time resolution sufficient to allow measurements limited only by system risetime of a few nanoseconds is needed. A 16/32 channel, 8 bit, fast transient digitizer was designed and built which runs at sample intervals down to approx. 1 nanosecond per channel

What is the problem to which interactive multimedia is the solution?

This is something of an unusual paper. It serves as both the reason for and the result of a small number of leading academics in the field, coming together to focus on the question that serves as the title to this paper: What is the problem to which interactive multimedia is the solution? Each of the authors addresses this question from their own viewpoint, offering informed insights into the development, implementation and evaluation of multimedia. The result of their collective work was also the focus of a Western Australian Institute of Educational Research seminar, convened at Edith Cowan University on 18 October, 1994. The question posed is deliberately rhetorical - it is asked to allow those represented here to consider what they think are the significant issues in the fast-growing field of multimedia. More directly, the question is also asked here because nobody else has considered it worth asking: for many multimedia is done because it is technically possible, not because it offers anything that is of value or provides the solution to a particular problem. The question, then, is answered in various ways by each of the authors involved and each, in their own way, consider a range of fundamental issues concerning the nature, place and use of multimedia - both in education and in society generally. By way of an introduction, the following provides a unifying context for the various contributions made here

Measuring Electric Fields From Surface Contaminants with Neutral Atoms

In this paper we demonstrate a technique of utilizing magnetically trapped neutral Rb-87 atoms to measure the magnitude and direction of stray electric fields emanating from surface contaminants. We apply an alternating external electric field that adds to (or subtracts from) the stray field in such a way as to resonantly drive the trapped atoms into a mechanical dipole oscillation. The growth rate of the oscillation's amplitude provides information about the magnitude and sign of the stray field gradient. Using this measurement technique, we are able to reconstruct the vector electric field produced by surface contaminants. In addition, we can accurately measure the electric fields generated from adsorbed atoms purposely placed onto the surface and account for their systematic effects, which can plague a precision surface-force measurement. We show that baking the substrate can reduce the electric fields emanating from adsorbate, and that the mechanism for reduction is likely surface diffusion, not desorption.Comment: 7 pages, 6 figures, published in Physical Review

The longitudinal thickness of air-shower fronts

Linsely (1983) has proposed a technique for the detection and analysis of air showers at large distances from the shower axis based on a measurement of the shower front thickness and the assumption that this thickness is closely related to the core distance. Some of the problems involved with realizing such a technique were investigated, and some related observations are reported. The practical problems of how consistent the measurements of the shower front would be, how one would use the measurement, and how the rate of triggered events would depend on the minimum pulse width required are studied

Plants from the park : Establishing community harvesting of plants as a conservation tool at Bwindi Impenetrable and Mgahinga National Parks, Uganda

It is now accepted that communities surrounding national parks in developing countries should benefit from conservation if the parks, and their constituent biodiversity, are to have a secure long-term future. It has also been accepted as morally questionable for communities living next to parks to pay the costs for national and international biodiversity conservation, and at the same time being excluded from any level of decision making regarding the management of those parks. Strategies to achieve conservation with equity include community involvement in park management and mechanisms to share conservation benefits

Characterizing Resting Cerebral Blood Flow in Obsessive-Compulsive Disorder with Arterial Spin Labeling

Obsessive-compulsive disorder (OCD) is a condition characterized by intrusive thoughts (obsessions) and ritualistic behaviors (compulsions) profoundly impacting daily functioning and quality of life. Neuroimaging studies using various techniques have revealed inconsistent resting cerebral blood flow (rCBF) patterns in OCD patients, particularly within the cortico-striatal-thalamo-cortical (CSTC) circuit and sensorimotor network. Arterial Spin Labeling (ASL) MRI offers a promising, noninvasive method for directly measuring rCBF. This study, using data from the Yale HCP Trio study, analyzed unmedicated OCD patients and healthy controls, who underwent two consecutive resting pulsed-ASL scans. OCD patients with lower obsessional severity exhibited higher perfusion in the pre- and postcentral gyri, indicating potential sensorimotor circuit dysregulation. However, no other results survived FDR correction. Interestingly, highly obsessional OCD patients did not show increased sensorimotor perfusion, relative to HCs, suggesting potential differences in cognitive processes during rest (e.g., obsessing, rather than mind-wandering). Future investigations should explore perfusion differences across OCD severity levels, considering individual differences in obsession type and cognitive processes at rest to better characterize group differences in rCBF

On a generalized quantum SWAP gate

The SWAP gate plays a central role in network designs for qubit quantum computation. However, there has been a view to generalize qubit quantum computing to higher dimensional quantum systems. In this paper we construct a generalized SWAP gate using only instances of the generalized controlled-NOT gate to cyclically permute the states of d qudits for d prime