Stochastic Properties of Static Friction

The onset of frictional motion is mediated by rupture-like slip fronts, which nucleate locally and propagate eventually along the entire interface causing global sliding. The static friction coefficient is a macroscopic measure of the applied force at this particular instant when the frictional interface loses stability. However, experimental studies are known to present important scatter in the measurement of static friction; the origin of which remains unexplained. Here, we study the nucleation of local slip at interfaces with slip-weakening friction of random strength and analyze the resulting variability in the measured global strength. Using numerical simulations that solve the elastodynamic equations, we observe that multiple slip patches nucleate simultaneously, many of which are stable and grow only slowly, but one reaches a critical length and starts propagating dynamically. We show that a theoretical criterion based on a static equilibrium solution predicts quantitatively well the onset of frictional sliding. We develop a Monte-Carlo model by adapting the theoretical criterion and pre-computing modal convolution terms, which enables us to run efficiently a large number of samples and to study variability in global strength distribution caused by the stochastic properties of local frictional strength. The results demonstrate that an increasing spatial correlation length on the interface, representing geometric imperfections and roughness, causes lower global static friction. Conversely, smaller correlation length increases the macroscopic strength while its variability decreases. We further show that randomness in local friction properties is insufficient for the existence of systematic precursory slip events. Random or systematic non-uniformity in the driving force, such as potential energy or stress drop, is required for arrested slip fronts. Our model and observations..

R&D Sourcing, Joint Ventures and Innovation: A Multiple Indicators Approach

This paper reexamines the limits of the firm in Research and Development (R&D). Using evidence drawn from industrial laboratories we study the causes and effects of R&D sourcing. We begin with the causes of sourcing, finding that Research Joint Ventures (RJVs), the option to purchase and acquire, and research with federal government contribute to sourced R&D. We then consider the effects of sourcing, RJVs, and the firm's internal research on innovation, as defined by patents and new products. Our results are that sourcing has little effect on innovation, but that RJVs and internal research increase innovation. This suggests specialization: cost saving is the primary motivation for sourcing, while innovation is the primary motivation for RJVs and internal research. Therefore, shared R&D comes in several varieties: R&D sourcing is not concerned with innovation, but consistent with their purpose, RJVs are instrumental in jointly commercializing the research of different firms.

Appendicular mass – a rare form of tuberculosis

Tuberculosis is in the top 10 causes of death worldwide, being one of the most deadly infectious diseases. It is estimated that one of three people from the entire earth population has a latent infection with M tuberculosis. This aerobic bacterium possesses the ability to persist in host tissues for years and to begin replication once immunity declines. The lungs are most frequent site of infection as the Mycobacterium tuberculosis is carried by aerosol droplets and is commonly transmitted by respiratory route. The second way of transmission is by contaminated food. Intestinal contamination coexists with pulmonary tuberculosis and only 10% represent primitive enteric diseases. The ileocecal region is involved most frequently. Even in this context isolated appendicular involvement remains rare. We report the case of appendicular tuberculosis in a 17-year-old woman with no evidence of other location of disease elsewhere in the body

RFID AND INFORMATION SYSTEMS IN COMMERCE

The paper analysis the possibilities of using, a relative new technology, RFID, in commerce. The main features of this technology, the components of the system, the way the system functions and the stages of the implementing process are also presented. Another part of the paper is devoted to the identification of the advantages of RFID technology and of the hurdels faced by companies in adopting it. The interest for this technology, used as solution for the management of information systems, is in a continuous increase, despite all the problems related to the high cost of the implementation and the wrong legislation, which stops the spread of this technology on a larger scale. The technology is now presented in a relatively small number of companies, but, certainly, it will be adopted, by more and more information systems in the future and it will extend in other activities too.information, radio waves, labels, antenna, reader

Results of Evolution Supervised by Genetic Algorithms

A series of results of evolution supervised by genetic algorithms with interest to agricultural and horticultural fields are reviewed. New obtained original results from the use of genetic algorithms on structure-activity relationships are reported.Comment: 6 pages, 1 Table, 2 figure

Adelic Integrable Systems

Incorporating the zonal spherical function (zsf) problems on real and $p$-adic hyperbolic planes into a Zakharov-Shabat integrable system setting, we find a wide class of integrable evolutions which respect the number-theoretic properties of the zsf problem. This means that at {\it all} times these real and $p$-adic systems can be unified into an adelic system with an $S$-matrix which involves (Dirichlet, Langlands, Shimura...) L-functions.Comment: 23 pages, uses plain TE

BUSINESS INTELLIGENT AGENTS FOR ENTERPRISE APPLICATION

Fierce competition in a market increasingly crowded and frequent changes in consumer requirements are the main forces that will cause companies to change their current organization and management. One solution is to move to open architectures and virtual type, which requires addressing business methods and technologies using distributed multi-agent systems. Intelligent agents are one of the most important areas of artificial intelligence that deals with the development of hardware and software systems able to reason, learn to recognize natural language, speak, make decisions, to recognize objects in the working environment etc. Thus in this paper, we presented some aspects of smart business, intelligent agents, intelligent systems, intelligent systems models, and I especially emphasized their role in managing business processes, which have become highly complex systems that are in a permanent change to meet the requirements of timely decision making. The purpose of this paper is to prove that there is no business without using the integration Business Process Management, Web Services and intelligent agents.business intelligence, intelligent agents, intelligent systems, management, enterprise, web services