164 research outputs found

    Fast-response cup anemometer features cosine response

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    Six-cup, low-inertia anemometer combines high resolution and fast response with a unique ability to sense only the horizontal component of the winds fluctuating rapidly in three dimensions. Cup assemblies are fabricated of expanded polystyrene plastic

    A laboratory investigation of the Lagrangian autocorrelation function in a stratified fluid

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    Enzyme kinetics for a two-step enzymic reaction with comparable initial enzyme-substrate ratios

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    We extend the validity of the quasi-steady state assumption for a model double intermediate enzyme-substrate reaction to include the case where the ratio of initial enzyme to substrate concentration is not necessarily small. Simple analytical solutions are obtained when the reaction rates and the initial substrate concentration satisfy a certain condition. These analytical solutions compare favourably with numerical solutions of the full system of differential equations describing the reaction. Experimental methods are suggested which might permit the application of the quasi-steady state assumption to reactions where it may not have been obviously applicable before

    An updated estimate of the economic costs of human illness due to food borne Salmonella in the United States

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    The Economic Research Service (ERS) of the U.S Department of Agriculture updated earlier estimates of the medical costs and productivity losses due to foodbome Salmonella infections in the United States. The update is based on a new estimate of annual salmonellosis cases by the Foodbome Diseases Active Surveillance Network (FoodNet) and new data on medical care for salmonellosis from a medical claims database. Using this information, ERS estimated that the annual economic costs of human illness due to foodbome Salmonella infections are 2.3billion(in1998dollars).Dataonfoodbomediseaseoutbreakssuggestthat6−9percentoffoodborneSalmonellainfectionsareassociatedwithporkandporkproducts,sotheannualcostsofhumanillnessduetoSalmonella−contaminatedporkappeartobeapproximately2.3 billion (in 1998 dollars). Data on foodbome disease outbreaks suggest that 6-9 percent of food borne Salmonella infections are associated with pork and pork products, so the annual costs of human illness due to Salmonella-contaminated pork appear to be approximately 0.1-0.2 billion

    The Dynamics of Viral Marketing

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    We present an analysis of a person-to-person recommendation network, consisting of 4 million people who made 16 million recommendations on half a million products. We observe the propagation of recommendations and the cascade sizes, which we explain by a simple stochastic model. We analyze how user behavior varies within user communities defined by a recommendation network. Product purchases follow a 'long tail' where a significant share of purchases belongs to rarely sold items. We establish how the recommendation network grows over time and how effective it is from the viewpoint of the sender and receiver of the recommendations. While on average recommendations are not very effective at inducing purchases and do not spread very far, we present a model that successfully identifies communities, product and pricing categories for which viral marketing seems to be very effective

    Crystal structures and magnetic order of La{0.5+delta}A{0.5-delta}Mn{0.5+epsilon}Ru{0.5-epsilon}O{3} (A= Ca, Sr, Ba): Possible orbital glass ferromagnetic state

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    The crystallographic and magnetic properties of La{0.5+delta}A{0.5-delta}Mn{0.5+epsilon}Ru{0.5-epsilon}O{3} (A= Ca, Sr, Ba) were investigated by means of neutron powder diffraction. All studied samples show the orthorhombic perovskite crystal structure, space group Pnma, with regular (Mn,Ru)O{6} octahedra and no chemical ordering of the Mn3+ and Ru4+ ions. Ferromagnetic spin structures were observed below Tc ~ 200-250 K, with an average ordered moment of ~ 1.8-2.0 Bohr magnetons per (Mn,Ru). The observation of long-range ferromagnetism and the absence of orbital ordering are rationalized in terms a strong Mn-Ru hybridization, which may freeze the orbital degree of freedom and broaden the eg valence band, leading to an orbital-glass state with carrier-mediated ferromagnetism

    Genetic Analysis of a Novel Human Adenovirus with a Serologically Unique Hexon and a Recombinant Fiber Gene

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    In February of 1996 a human adenovirus (formerly known as Ad-Cor-96-487) was isolated from the stool of an AIDS patient who presented with severe chronic diarrhea. To characterize this apparently novel pathogen of potential public health significance, the complete genome of this adenovirus was sequenced to elucidate its origin. Bioinformatic and phylogenetic analyses of this genome demonstrate that this virus, heretofore referred to as HAdV-D58, contains a novel hexon gene as well as a recombinant fiber gene. In addition, serological analysis demonstrated that HAdV-D58 has a different neutralization profile than all previously characterized HAdVs. Bootscan analysis of the HAdV-D58 fiber gene strongly suggests one recombination event
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