Design principles of hardware-based phong shading and bump-mapping

The VISA+ hardware architecture is the first of a new generation of graphics accelerators designed primarily to render bump-, texture-, environment- and environment-bump-mapped polygons. This paper presents examples of the main graphical capabilities and discusses methods and simplifications used to create high quality images. One of the key concepts in the VISA+ design, the use of reflectance cubes, is predestined for environment mapping. In combination with bump- and texture-mapping it shows the strength of our new architecture. Furthermore it justifies some of the decisions made during simulation and development of the complex VISA+ architecture

A QUANTITATIVE ASSESSMENT OF E-GROCERS

Agribusiness,

Defence and space expenditures in the US: An inter-firm analysis

The economic impact of defence and space expenditures has been an important policy issue because of the secondary benefits expected to be accruing from it. Although defence and space activities can stimulate the early development of many technologies, the lasting economic impact of these technologies is difficult to measure. To capture the scientific and technological values added of defence and space financed productions, we have depended on the patents and scientific and technical publications as the indicators. The economic performance has been measured by two separate indicators: (a) firm growth in terms of average annual rate of change in the number of employees, and (b) rate of return on sales measured by the company's net profits in relation to sales. From 1970-75 and 1980-85 the weight within the manufacturing sector of both defence contractors and the civilian companies increased. Defence firms gained considerably in terms of sales, employment, gross plants and company funded R&D in the latter period under the Reagan Administration. Whereas this may be considered a Reagan effect in defence procurement, other indicators point to in the opposite direction: (a) decrease in the shares of defence R&D contracts, (b) relatively low growth of patent output as percent of total manufacturing from the defence firms, and (c) decrease in scientific publications from defence firms per 1000 employees. Firm level analysis showed that military R&D contracts did not contribute to economic or technical efficiency. Space expenditure did not contribute to improvement of economic performance as measured by company growth and profitability. NASA contracts were not associated with technical progress measured by patents, but they improved scientific publications. Defence expenditures are not of importance for the overall economic efficiency. The standard financial variables, capital formation and own R&D activities prove mostly relevant. The study is restricted to an efficiency analysis in a cross sectional comparison and does not include the effect of market structure.

Twelve-spin "Schrodinger cat"

Pseudopure "cat" state, a superposition of quantum states with all spins up and all spins down, is experimentally demonstrated for a system of twelve dipolar-coupled nuclear spins of fully 13C-labeled benzene molecule oriented in a liquid-crystalline matrix.Comment: Submitted to Applied Physics Letter

The Computational Complexity of the Lorentz Lattice Gas

The Lorentz lattice gas is studied from the perspective of computational complexity theory. It is shown that using massive parallelism, particle trajectories can be simulated in a time that scales logarithmically in the length of the trajectory. This result characterizes the ``logical depth" of the Lorentz lattice gas and allows us to compare it to other models in statistical physics.Comment: 9 pages, LaTeX, to appear in J. Stat. Phy

Robust Logic Gates and Realistic Quantum Computation

The composite rotation approach has been used to develop a range of robust quantum logic gates, including single qubit gates and two qubit gates, which are resistant to systematic errors in their implementation. Single qubit gates based on the BB1 family of composite rotations have been experimentally demonstrated in a variety of systems, but little study has been made of their application in extended computations, and there has been no experimental study of the corresponding robust two qubit gates to date. Here we describe an application of robust gates to Nuclear Magnetic Resonance (NMR) studies of approximate quantum counting. We find that the BB1 family of robust gates is indeed useful, but that the related NB1, PB1, B4 and P4 families of tailored logic gates are less useful than initially expected.Comment: 6 pages RevTex4 including 5 figures (3 low quality to save space). Revised at request of referee and incorporting minor corrections and updates. Now in press at Phys Rev

Calculating error bars for neutrino mixing parameters

One goal of contemporary particle physics is to determine the mixing angles and mass-squared differences that constitute the phenomenological constants that describe neutrino oscillations. Of great interest are not only the best fit values of these constants but also their errors. Some of the neutrino oscillation data is statistically poor and cannot be treated by normal (Gaussian) statistics. To extract confidence intervals when the statistics are not normal, one should not utilize the value for chisquare versus confidence level taken from normal statistics. Instead, we propose that one should use the normalized likelihood function as a probability distribution; the relationship between the correct chisquare and a given confidence level can be computed by integrating over the likelihood function. This allows for a definition of confidence level independent of the functional form of the !2 function; it is particularly useful for cases in which the minimum of the !2 function is near a boundary. We present two pedagogic examples and find that the proposed method yields confidence intervals that can differ significantly from those obtained by using the value of chisquare from normal statistics. For example, we find that for the first data release of the T2K experiment the probability that chisquare is not zero, as defined by the maximum confidence level at which the value of zero is not allowed, is 92%. Using the value of chisquare at zero and assigning a confidence level from normal statistics, a common practice, gives the over estimation of 99.5%.Comment: 9 pages, 6 figure

TRACKING THE EVOLUTION OF E-GROCERS: A QUANTITATIVE ASSESSMENT

Forecasts of the proportion of food retailing likely to be conducted over the Internet remain small, perhaps only contributing 2 percent of sales. One reason for this low market share is the challenge E-Grocers face in developing strategies which respond to four key areas of interest to consumers: signals of firm quality; signals of product quality; the range of products offered; and service, or customer-relationship management (CRM). Careful attention to these consumer concerns is important in all retail relationships–-online or offline. This paper compares indicators of these factors across U.S. E-Grocers. A quantitative four-period ranking of online food-retailing strategies is presented for the nascent industry. Data from the third and fourth quarters of 2001, the fourth quarter of 2002, and the first quarter of 2004 provide the basis of this discussion. After initial setbacks, data show traditional ("“bricks”") grocery retailers successfully developing online strategies. Firms not primarily focused on groceries exited the E-Grocery sector, while the development of specialty food suppliers blurred the concept of online food retailing. Gaps in current strategies are indicated using content analyses of E-Grocery web sites.Agribusiness,