Gaussian approximations to service problems : a communication system example

Messages arrive at a group of service channels in accordance with a time-dependent Poisson process. An arrival either (1) immediately begins k-stage Markovian service if an empty channel is reached, or (2) balks and enters a retrial population if the channel sought is busy. Diffusion approximations to the number of messages in service (each stage) and in the retrial population are derived by writing stochastic differential (I+0) equations. Steady-state distributions are found and compared with certain simulation resultssupported in part by the National Science Foundation, Grant AG46 7, at the Naval Postgraduate School, and the Air Force Office of Scientific Research, Grant AFOSR74-2642, at Carnegie Mellon University.http://archive.org/details/gaussianapproxim00gaveN

Use of beneficial bacteria and their secondary metabolites to control grapevine pathogen diseases

Grapevine is one of the most important economic crops yielding berries, wine products as well as derivates. However, due to the large array of pathogens inducing diseases on this plant, considerable amounts of pesticides—with possible negative impact on the environment and health—have been used and are currently used in viticulture. To avoid negative impacts of such products and to ensure product quality, a substantial fraction of pesticides needs to be replaced in the near future. One solution can be related to the use of beneficial bacteria inhabiting the rhizo- and/or the endosphere of plants. These biocontrol bacteria and their secondary metabolites can reduce directly or indirectly pathogen diseases by affecting pathogen performance by antibiosis, competition for niches and nutrients, interference with pathogen signaling or by stimulation of host plant defenses. Due to the large demand for biocontrol of grapevine diseases, such biopesticides, their modes of actions and putative consequences of their uses need to be described. Moreover, the current knowledge on new strains from the rhizo- and endosphere and their metabolites that can be used on grapevine plants to counteract pathogen attack needs to be discussed. This is in particular with regard to the control of root rot, grey mould, trunk diseases, powdery and downy mildews, pierce’s disease, grapevine yellows as well as crown gall. Future prospects on specific beneficial microbes and their secondary metabolites that can be used as elicitors of plant defenses and/or as biocontrol agents with potential use in a more sustainable viticulture will be further discussed

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62798/1/409860a0.pd

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Diffusion approximations for the cooperative service of voice and data messages

A probability model is presented for a set of communication channels that share the service of data and voice transmissions. A diffusion-theoretic approximation is derived, utilizing new results of Burman (1979). It is shown that the data queue (which is of low priority relative to voice) is approximated by a Wiener process. (Author)A probability model is presented for a set of communication channels that share the service of data and voice transmissions. A diffusion-theoretic approximation is derived, utilizing new results of Burman (1979). It is shown that the data queue (which is of low priority relative to voice) is approximated by a Wiener process.NAhttp://archive.org/details/diffusionapproxi63lehoNAN

Non-stationary infinite server models and their relatives

A backward equation technique is used to derive properties of a timedependent infinite server system subject to compound Poisson demand. The method is used to suggest a model leading to Zipf's law.http://archive.org/details/nonstationaryinf00gav

Channels that cooperatively service a data stream and voice messages, I

A system of channels cooperatively services both voice and data messages arriving at one node of a communications network. This paper is devoted to the analysis of a particular channel-sharing strategy, in which voice traffic always occupies its channels when available, but data service is allowed to occur on empty voice channels. Voice traffic is taken to be of high priority; voice arrivals that find all voice channels busy are treated as losses. Note that voice traffic will be relatively infrequent as compared to data, and will also exhibit relatively long holding (service) times. Data traffic is taken to be heavy, and exhibits very short holding times (per word unit): compared to voice, data appears to arrive nearly continuously; when all data (and empty voice) channels are filled, queueing occursChief of Naval Research, Arlington, VAhttp://archive.org/details/channelsthatcoop00gave61152N;R000-01-10 N0001480WR00054N

A diffusion approximation model for a communication system allowing message interference

Mathematical probability models are presented to describe the service furnished to messages approaching c communications channels, on which messages in progress may be 'destroyed' by an attempted access by a new message. Re-tries by destroyed messages are modeled. Numerical results, using the models, are compared to simulations, validating model usefulness. (Author)supported by the Office of Naval Research and the Defense Communication Agency at the Naval Postgraduate Schoolhttp://archive.org/details/diffusionapproxi00gaveN

Random parameter Markov population process models and their likelihood, Bayes, and empirical Bayes analysis

Markov population stochastic processes are useful in describing repairman and logistics problems, networks of queues, pharmacological processes, and manpower situations. This paper considers statistical estimation problems arising for such mathematical models. Parameter estimation of an empirical Bayes nature, with limited shrinkage or discrepancy tolerant features is discussed and illustrated. Additional keywords: Maximum likelihood estimation; Pharmacology; Statistical inference; Statistical analysis. (Author)Office of Naval Research.http://archive.org/details/randomparameterm00gav