Regulatory Reform: In the Land of the \u27Coffeenet\u27

Sitting down to write this article at a desk some 30 miles south of central London, and less than one degree west of the Greenwich meridian, I became immediately more conscious than usual of geography. The frequently interwoven use of such western-centric cartographic labels as Middle East, and Far East, with the geographically more precise terms of Western or Central Asia, and East and South-East Asia, sometimes causes us to confuse the actual proximity of Europe\u27s, much larger, near-neighbour

Overview: A+B+C = VSAT

The benefits of VSAT systems and services are being realised in all spheres across the globe, both private and public. Banks, government departments, schools, hospitals, home offices, small enterprises, multi-national corporates, and rural telephony… all sectors are seizing upon the opportunity to get connected through satellite communications

Regulatory Reform: WANTED: A bridge for Africa\u27s digital divide APPLY: Pretty much anywhere in Africa QUOTE REFERENCE: VSAT

For Africa, and for the economy of the whole planet, those hundreds of millions of people across the continent who are currently denied reasonable access to even simple voice service represent a vast untapped pool of creativity. This very large and potentially very powerful economic dynamo demands access to more than the simplest tools of communication, and requires the means to unleash the potential productivity of its own knowledge-base into an increasingly connected world. The International Telecommunications Union acknowledges this, as does its sister organisation, the United Nations. The Global VSAT Forum enjoins you to acknowledge it too

Issue 7: Contributors

List of Issue 7 Contributors

Issue 7: From the Guest Editors

During the past 15 years, the international satellite communications industry has been developing and refining network solutions such that today, there are more than one million so-called Very Small Aperture Terminal (VSAT) systems installed and operating in more than 120 countries

Ion Funnels for the Masses: Experiments and Simulations with a Simplified Ion Funnel

A modified ion funnel is described. Counterintuitively, increased spacing between electrodes results in enhanced “focusing” of the ions through the funnel. Consequently, the internal diameter (i.d.) of the funnel need not decrease to the conductance limit (as in previous designs). A simple dc-only lens, which also serves as the conductance limit, combined with the natural flow of gas is used to extract the ions from the funnel. Ions with mass to charge ratios varying between 75 and 3000 m/z are passed through the funnel with no apparent discrimination. The funnel can be operated under mild conditions that preserve weakly bound noncovalent complexes. After testing several designs, a thin closely spaced dc lens was found to be the best solution for extracting ions. A simple method for simulating ion trajectories at nonzero pressures based on ion mobility and explicit diffusion is described. This theoretical approach was used to design and calculate ion trajectories for the modified funnel presented here. Finally, the increased spacing between electrodes in the current funnel significantly relaxes machining constraints, reduces cost, and enhances ease of use versus previous funnel designs

Crossed beam studies of ion-molecule reactions.

A new crossed beam instrument for the study of ion-molecule collision processes is described. During the development work a novel method of focussing an ion beam from a quadrupole mass filter was devised. Using an electrostatic octopole lens it is possible to obtain low energy ion beams with narrow energy distributions and with intensities and angular distributions close to the fundamental space charge limit. The aim of this work has been to investigate the dynamics of the reactions of diatomic ions with diatomic molecules. The results of a detailed study of the reactions CO+ + O2 = CO+2 + O CO+ + NO = CO+2 + N CO+ + NO = (NCO)+ + O are presented and discussed. All the reactions were found to proceed by a direct mechanism over the energy range studied although there is substantial evidence for the coupling of the motion of all atoms in reactive collisions. At high energy the total cross sections decline as the dynamics become dominated by product stability restrictions and there is evidence for the formation of electronically excited product

Modeling working memory: An interference model of complex span

This article introduces a new computational model for the complex-span task, the most popular task for studying working memory. SOB-CS is a two-layer neural network that associates distributed item representations with distributed, overlapping position markers. Memory capacity limits are explained by interference from a superposition of associations. Concurrent processing interferes with memory through involuntary encoding of distractors. Free time in-between distractors is used to remove irrelevant representations, thereby reducing interference. The model accounts for benchmark findings in four areas: (1) effects of processing pace, processing difficulty, and number of processing steps; (2) effects of serial position and error patterns; (3) effects of different kinds of item-distractor similarity; and (4) correlations between span tasks. The model makes several new predictions in these areas, which were confirmed experimentall