The New Business Currency

Thomas H. Davenport and John C. Beck, The Attention Economy: Understanding the New Currency of Business, Boston, MA: Harvard Business School Press (2001), 253 pp.

Brad Hansen, The Dictionary of Computing and Digital Media: Terms and Acronyms, Wilsonville, OR: Franklin, Beedle, and Associates (1999), 543 pp.

Piotr Jankowski and Timothy Nyerges, Geographic Information Systems for Group Decision Making: Towards a Participatory Geographic Information Science, New York: Taylor and Francis (2001), 273 pp.

Jeffrey A. Rohlfs, Bandwagon Effects in High Technology Industries, Cambridge, MA: MIT Press (2001), 256 pp.     

Demand-driven logic simulation using a network of loosely coupled processors

Logic simulation is used extensively in the design of digital systems for the purpose of studying the behaviour of circuits under various conditions and for verifying the required performance of circuits. There is considerable interest in methods which reduce the simulation time during the design process. In this paper, we investigate how this can be achieved by simulating the action of logic circuits using a network of loosely coupled processors. Circuits modelled as directed graphs comprising clocked sequential components and (unclocked) arbitrary combinational logic gates can be partitioned into separate tasks each consisting of a sequential component with an associated network of combinational components. We present cost functions for evaluating a task subject to probabilistic assumptions about the functioning of the circuits. The circuit evaluation method used in the simulation process is significant. We apply lazy evaluation, a demand-driven evaluation strategy in which signals in the circuit are evaluated on a ‘need to do' basis, resulting in a considerable saving in circuit simulation time. We achieve distributed logic simulation using a network of workstations and show from experimental results that by using such a configuration, we essentially obtain a single computation engine which can be used to obtain speedups in circuit simulation when compared with uniprocessor simulation systems. Interprocess communications between tasks on different workstations proceed via remote procedure calls while local communications between tasks take place via shared memory. The method of partitioning used in the circuit model ensures that communications between tasks take place only at defined times in the simulation sequence.     

Moving Beyond Combinatorial Chemistry for Greater Efficiency in Lead Discovery

Pfizer Inc. is a research based global pharmaceutical company committed to the discovery and development of innovative medicines that improve the quality of life of individuals throughout the world. In order to gain a competitive advantage over competitor companies in the discovery of new medicines, we must speed up drug discovery and drive down costs. Using non-combinatorial chemistry techniques increases the efficiency with which we discover new ‘leads,’ leveraging our drug discovery efforts through retaining complete control over the properties of each product made. Compound purification, managed through in-house software, augments the quality of data obtained upon biological screening of compounds.     

Influence of the modelling approach on the estimation of the minimum temperature for growth in Belehrádek-type models

This paper compares three different approaches for describing the growth rate dependence on sub-optimal temperatures {e.g., the square-root model described by Ratkowsky et al. (1982. J. Bacteriol. 154, 1222–1226): √μ=b.(T−T_min1) or μ=b². (T−T_min1)², the model originally found by Belehrádek (1926a. Nature11, 117–118): μ=a. (T−T₀)^αand a dimensionless analysis described previously, (Dantigny 1998. J. Ind. Microbiol. Biotechnol.21, 215–218.):

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Data sets, growth rate vs temperature, have been taken from the literature for various organisms (e.g. Lactobacillus plantarum, Yersinia enterolitica and Acinetobacter).Firstly, this paper analyses the effect of using dimensionless (e.g. T_dimand μ_dim) or natural variables (e.g. T and μ) on the estimation of the minimum temperature for growth (e.g. T₀and T_min) and the α value. Secondly, the Belehrádek model is compared to the square-root model by using the natural variables. It has been demonstrated that the use of the square-root model leads to an under-estimation of the minimum temperature for growth when the α -value is significantly less than 2. In such a case, it has been highlighted that the dimensionless approach provides a closer estimation of the experimental minimum temperature for growth than the square-root model.     

Habitat-specific Signal Structure for Olfaction: An Example from Artificial Streams

Many animals use chemical signals to acquire information about their habitats. The structure of this information is dependent upon specific features within a habitat, and the information in signals can be habitat-specific. We quantified the spatial and temporal information in an aquatic odor plume in three different artificial stream habitats with different substrate types by measuring turbulent odor plumes with an electrochemical detection system. Streams had one of three substrate types that correlated with typical aquatic habitats: sand (4.2 × 10^–2 cm diameter), gravel (2.5 cm), and cobble (4.5 cm). As predicted from the hydrodynamics, the spatial and temporal structures of the signals were different on different substrates. Spectral analysis showed that the sand and cobble substrates had signals that were dominated by lower frequency fluctuations, whereas gravel had the highest and broadest range of signal fluctuations. Cross- and autocorrelations showed that signals on the gravel substrate had the largest spatial and shortest temporal components. Our results imply that the information obtained from chemical signals may be limited in some habitats. These constraints on information may affect how organisms perform chemically mediated behaviors.     

Solving A\underline x =\underline b Using a Modified Conjugate Gradient Method Based on Roots of A

We consider the modified conjugate gradient procedure for solving A = in which the approximation space is based upon the Krylov space associated with A ^1/p and , for any integer p. For the square-root MCG (p=2) we establish a sharpened bound for the error at each iteration via Chebyshev polynomials in . We discuss the implications of the quickly accumulating effect of an error in in the initial stage, and find an error bound even in the presence of such accumulating errors. Although this accumulation of errors may limit the usefulness of this method when is unknown, it may still be successfully applied to a variety of small, almost-SPD problems, and can be used to jump-start the conjugate gradient method. Finally, we verify these theoretical results with numerical tests.     

Call for Papers

Call for Papers

Call for Papers     

High-Speed Tools for Global Information Management.II. Specifications and Uses of the Transparent Query Language (TQL) Part IIF. Additional Uses of TQL, Data Structures, Concise Definitions, Conclusions and Acknowledgments

This part, PART IIF [6], concludes the document HIGH-SPEED TOOLS FOR GLOBAL INFORMATION MANAGEMENT. II. Specifications and Uses of the Transparent Query Language (TQL) [1–6]. It describes novel applications of TQL, the key data structures, and contains a dictionary of Transparent Query Language terms. PART IIF references PART IIA [1], PART IIB [2], PART IIC [3], PART IID [4], and PART IIE [5] and contains Conclusions and Acknowledgements.