On set systems with restricted intersections modulo p and p-ary t-designs

We consider bounds on the size of families ℱ of subsets of a v-set subject to restrictions modulo a prime p on the cardinalities of the pairwise intersections. We improve the known bound when ℱ is allowed to contain sets of different sizes, but only in a special case. We show that if the bound for uniform families ℱ holds with equality, then ℱ is the set of blocks of what we call a p-ary t-design for certain values of t. This motivates us to make a few observations about p-ary t-designs for their own sake

On t -designs

Introduction and preliminaries An incidence structure is a triple S=(X, <J,9 S} where X and JL are disjoint sets andc^ci^fX^?. Elements x^X are called points and elements A^JL are called blocks of S. A point x and a block ^4 are incident iff (#, ^4)ec?. For any block A, (A) will denote the set of points incident with A

Space Electrochemical Research and Technology

Individual papers presented at the conference address the following topics: development of a micro-fiber nickel electrode for nickel-hydrogen cell, high performance nickel electrodes for space power application, bending properties of nickel electrodes for nickel-hydrogen batteries, effect of KOH concentration and anions on the performance of a Ni-H2 battery positive plate, advanced dependent pressure vessel nickel hydrogen spacecraft cell and battery design, electrolyte management considerations in modern nickel hydrogen and nickel cadmium cell and battery design, a novel unitized regenerative proton exchange membrane fuel cell, fuel cell systems for first lunar outpost - reactant storage options, the TMI regenerable solid oxide fuel cell, engineering development program of a closed aluminum-oxygen semi-cell system for an unmanned underwater vehicle, SPE OBOGS on-board oxygen generating system, hermetically sealed aluminum electrolytic capacitor, sol-gel technology and advanced electrochemical energy storage materials, development of electrochemical supercapacitors for EMA applications, and high energy density electrolytic capacitor

A Reply to H. S. Gutowsky and E. M. Peterson Regarding the Ozone Spectrum

To avoid unnecessary confusion regarding the ozone spectrum it appears desirable to point out that the analysis of the infra-red spectrum based upon an acute angled molecular model proposed by Gutkowsky and Peterson (1) appears to be completely excluded on at least two different grounds. (Incidentally the heading of columns 2 and 3 of the Table I appear to be interchanged)

Power-Ups in Digital Games: The Rewarding Effect of Phantom Game Elementson Player Experience

Power-ups are a type of game reward that allow the player tocustomise their experience by altering gameplay for a shortperiod of time. Despite the wide use of power-ups in videogames, little is known about their effect on gaming experiences.To explore this, we conducted an experimental study that compares the experiences of players depending on their exposureto power-ups in a recreational video game. The results show that players who collected power-ups felt significantly more immersed in the game, experienced more autonomy, but didnot feel more competent or challenged than those who played the game without these collectables. Interestingly, a similareffect was observed for those players who picked up ‘placebo ’power-ups, despite the items having no effect on the gameplay. We provide a discussion of these results and their implications both for games user researchers and game designers

The Corporate Income Tax in Canada: Does its Past Foretell its Future?

Corporate tax reform has long been a contentious issue in Canada. Official commissions, academics and others have often proposed changes in the way we tax corporations. During the last 30 years, perhaps largely owing to concerns about international competitiveness, the corporate tax rate has been substantially reduced. Since revenues did not decline as a result, those concerned by increased inequality who believe that corporate taxes are paid mainly by the rich have suggested that corporate rates should be increased. Others, more persuaded by the increasing evidence that much of the burden of the corporate tax ultimately falls on workers and wages and that even to the extent it falls on capital the economic price paid in terms of reduced output and productivity for each corporate tax dollar collected is high have taken the opposite tack and argued that, if anything, corporate tax reform should be aimed at reducing even further the effective tax rate on corporate capital. Both the technical and the political aspects of corporate taxation are thus at play in the current discussion of possible corporate tax reform. After a brief review of the history, we consider what is now known about the relation between corporate rates and revenue, the surprisingly complex question of who ultimately pays the tax, and the largely undesirable economic effects of corporate income taxes. If all voters were economists and familiar with the evidence, it is unlikely any would favour big increases in corporate taxes. However, even economists who have read all the studies mentioned here (and more) do not agree about the best way to reform the corporate income tax. We sketch three recent major reform proposals Canadian experts have recently put forward (1) replace the existing corporate tax by a tax on ‘rents’ (above-normal returns on capital), (2) replace both it and the current personal income tax by a ‘dual income tax’ with a flat rate on all capital income (corporate and personal), or (3) adopt a more gradual approach to reform that would broadly keep the present system but make it more uniform in its treatment of investment. On the whole, we suggest that, although the ‘rent’ proposal is clearly the favourite in the academic horse race, and we think a much closer look should be taken at the second (dual income tax), the more incremental third proposal – improve what we now have – is perhaps not only the way we should go now but is also likely to be the politically most acceptable of these schemes. Finally, since one reason corporate tax reform is so difficult is because it is closely related to a number of other issues that are often both technically complex and politically sensitive, we consider several such issues. Some, such as small business taxation, could be reformed independently of the sorts of more general reforms just mentioned. We sketch several reforms that would simplify the system, maintain some incentive for small businesses and reduce the extent to which the current system provides a shelter for the rich. But other issues cannot be dealt with separately. What is the appropriate level and nature of ‘integration’ between the corporate and personal income taxes? What is the appropriate role of federal and provincial governments with respect to the corporate income tax? And, assuming that we continue to use taxes to provide preferences (incentives) to specific sectors and activities, what is the best way in which to do so? Within entering too far in the ‘dismal swamp’ of the inner workings of the tax system, we suggest some possible directions for reform in these areas such as a ‘sunset’ clause for tax preferences to reduce the likelihood that they will be indefinitely preserved whether socially useful or not