On Nonnegative Integer Matrices and Short Killing Words

Let $n$ be a natural number and $\mathcal{M}$ a set of $n \times n$-matrices over the nonnegative integers such that the joint spectral radius of $\mathcal{M}$ is at most one. We show that if the zero matrix $0$ is a product of matrices in $\mathcal{M}$, then there are $M_1, \ldots, M_{n^5} \in \mathcal{M}$ with $M_1 \cdots M_{n^5} = 0$. This result has applications in automata theory and the theory of codes. Specifically, if $X \subset \Sigma^*$ is a finite incomplete code, then there exists a word $w \in \Sigma^*$ of length polynomial in $\sum_{x \in X} |x|$ such that $w$ is not a factor of any word in $X^*$. This proves a weak version of Restivo's conjecture.Comment: This version is a journal submission based on a STACS'19 paper. It extends the conference version as follows. (1) The main result has been generalized to apply to monoids generated by finite sets whose joint spectral radius is at most 1. (2) The use of Carpi's theorem is avoided to make the paper more self-contained. (3) A more precise result is offered on Restivo's conjecture for finite code

Digital demodulator-correlator

An apparatus for demodulation and correlation of a code modulated 10 MHz signal is presented. The apparatus is comprised of a sample and hold analog-to-digital converter synchronized by a frequency coherent 40 MHz pulse to obtain four evenly spaced samples of each of the signal. Each sample is added or subtracted to or from one of four accumulators to or from the separate sums. The correlation functions are then computed. As a further feature of the invention, multipliers are each multiplied by a squarewave chopper signal having a period that is long relative to the period of the received signal to foreclose contamination of the received signal by leakage from either of the other two terms of the multipliers

Statistical Interpretation of Joint Multiplicity Distributions of Neutrons and Charged Particles

Experimental joint multiplicity distributions of neutrons and charged particles emitted in complex nuclear reactions provide an important test of theoretical models. The method is applied to test three different theoretical models of nuclear multi-fragmentation, two of which fail the test. The measurement of neutrons is decisive in distinguishing between the Berlin and Copenhagen models of nuclear multi-fragmentation and challenges the interpretation of pseudo- Arrhenius plots. Statistical-model evaporation calculations with GEMINI give a good reproduction first and second moments of the experimental multiplicity correlations.Comment: 12 pages, 3 figures Added GEMINI calculations of multiplicity correlations Added brief discussion of how neutron emission is treated in MMM

Does Regionalism Hinder Multilateralism: A Case Study of India.

Today many developing countries fear that regional movements in other parts of the world will adversely impact their trade as regionalism overtakes multilateralism. The response has been that most of them are trying to get into one regional bloc or the other via regional trade arrangements (RTAs). In this paper we have investigated how India as a non-member country is affected by formation of RTAs like ASEAN, EU, NAFTA, and MERCOSUR..Controlling for non-RTA factors that influence exports, we find thatIndia?s exports to these RTAs seem to be affected not by the formation of these RTAs pese but by demand side factors.

Light me up: power and expertise in risk communication and policy-making in the e-cigarette health debates

This paper presents a detailed account of policy-making in a contemporary risk communication arena, where strong power dynamics are at play that have hitherto lacked theoretical analysis and empirical validation. Specifically, it expands on the understanding of how public health policy decisions are made when there is a weak evidential base and where multiple interpretations, power dynamics and values are brought to bear on issues of risk and uncertainty. The aim of the paper is to understand the role that power and expertise play in shaping public health risk communication within policy-related debates. By drawing on insight from a range of literatures, the paper argues that there several interacting factors that shape how a particular narrative gains prominence within a wider set of perspectives and how the arguments and findings associated with that perspective become amplified within the context of policy choices. These findings are conceptualised into a new model – a policy evaluation risk communication (PERC) framework – and are then tested using the Electronic cigarette debate as a case study

Working Memory Networks for Learning Temporal Order, with Application to 3-D Visual Object Recognition

Working memory neural networks are characterized which encode the invariant temporal order of sequential events. Inputs to the networks, called Sustained Temporal Order REcurrent (STORE) models, may be presented at widely differing speeds, durations, and interstimulus intervals. The STORE temporal order code is designed to enable all emergent groupings of sequential events to be stably learned and remembered in real time, even as new events perturb the system. Such a competence is needed in neural architectures which self-organize learned codes for variable-rate speech perception, sensory-motor planning, or 3-D visual object recognition. Using such a working memory, a self-organizing architecture for invariant 3-D visual object recognition is described. The new model is based on the model of Seibert and Waxman (1990a), which builds a 3-D representation of an object from a temporally ordered sequence of its 2-D aspect graphs. The new model, called an ARTSTORE model, consists of the following cascade of processing modules: Invariant Preprocessor --> ART 2 --> STORE Model --> ART 2 --> Outstar Network.Defense Advanced Research Projects Agency (90-0083); British Petroleum (89-A1-1204); National Science Foundation (IRI 90-00530, IRI 87-16960); Air Force Office of Scientific Research (90-128, 90-0175

An investigation into standards in sustainable design and manufacture

This paper reports upon the application of standards to reduce the negative environmental impacts of manufacturing through product lifecycle planning and closed loop production. By eliminating waste and retaining the energy embodied within materials and components, manufacturing can become more sustainable from both ecological and financial perspectives. Energy consumption and the associated carbon pollution can thus be minimised. Environmental Management System implementation is also considered