6,588 research outputs found

    Automated method for study of drug metabolism

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    Commercially available equipment can be modified to provide automated system for assaying drug metabolism by continuous flow-through. System includes steps and devices for mixing drug with enzyme and cofactor in the presence of pure oxygen, dialyzing resulting metabolite against buffer, and determining amount of metabolite by colorimetric method

    Effect of sweep angle on the pressure distributions and effectiveness of the ogee tip in diffusing a line vortex

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    Low-speed wind tunnel tests were conducted to study the influence of sweep angle on the pressure distributions of an ogee-tip configuration with relation to the effectiveness of the ogee tip in diffusing a line vortex. In addition to the pressure data, performance and flow-visualization data were obtained in the wind tunnel tests to evaluate the application of the ogee tip to aircraft configurations. The effect of sweep angle on the performance characteristics of a conventional-tip model, having equivalent planform area, was also investigated for comparison with the ogee-tip configuration. Results of the investigation generally indicate that sweep angle has little effect on the characteristics of the ogee in diffusing a line vortex

    CMOS array design automation techniques

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    A low cost, quick turnaround technique for generating custom metal oxide semiconductor arrays using the standard cell approach was developed, implemented, tested and validated. Basic cell design topology and guidelines are defined based on an extensive analysis that includes circuit, layout, process, array topology and required performance considerations particularly high circuit speed

    Random Time-Scale Invariant Diffusion and Transport Coefficients

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    Single particle tracking of mRNA molecules and lipid granules in living cells shows that the time averaged mean squared displacement δ2\overline{\delta^2} of individual particles remains a random variable while indicating that the particle motion is subdiffusive. We investigate this type of ergodicity breaking within the continuous time random walk model and show that δ2\overline{\delta^2} differs from the corresponding ensemble average. In particular we derive the distribution for the fluctuations of the random variable δ2\overline{\delta^2}. Similarly we quantify the response to a constant external field, revealing a generalization of the Einstein relation. Consequences for the interpretation of single molecule tracking data are discussed.Comment: 4 pages, 4 figures.Article accompanied by a PRL Viewpoint in Physics1, 8 (2008

    Academic Language Acquisition

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    The implementation of the Common Core State Standards (CCSS) has promoted the increased teaching of academic vocabulary in all subject areas. The current study examined the rationale behind the CCSS’s decision to increase academic language acquisition. Multiple sources were systematically reviewed to find implications for teaching academic language in the content areas. Research studies were examined to determine the impact of requiring academic language acquisition in the classroom with English Language Learners (ELLs). The current study found that ELLs struggle to achieve academic language proficiency in a short time because ELLs acquire social language before academic language. Results suggest that Academic language needs to be explicitly taught by all educators to prepare children for college and careers

    Small violations of full correlation Bell inequalities for multipartite pure random states

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    We estimate the probability of random NN-qudit pure states violating full-correlation Bell inequalities with two dichotomic observables per site. These inequalities can show violations that grow exponentially with NN, but we prove this is not the typical case. For many-qubit states the probability to violate any of these inequalities by an amount that grows linearly with NN is vanishingly small. If each system's Hilbert space dimension is larger than two, on the other hand, the probability of seeing \emph{any} violation is already small. For the qubits case we discuss furthermore the consequences of this result for the probability of seeing arbitrary violations (\emph i.e., of any order of magnitude) when experimental imperfections are considered.Comment: 16 pages, one colum

    Critical percolation of free product of groups

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    In this article we study percolation on the Cayley graph of a free product of groups. The critical probability pcp_c of a free product G1G2...GnG_1*G_2*...*G_n of groups is found as a solution of an equation involving only the expected subcritical cluster size of factor groups G1,G2,...,GnG_1,G_2,...,G_n. For finite groups these equations are polynomial and can be explicitly written down. The expected subcritical cluster size of the free product is also found in terms of the subcritical cluster sizes of the factors. In particular, we prove that pcp_c for the Cayley graph of the modular group PSL2(Z)\hbox{PSL}_2(\mathbb Z) (with the standard generators) is .5199....5199..., the unique root of the polynomial 2p56p4+2p3+4p212p^5-6p^4+2p^3+4p^2-1 in the interval (0,1)(0,1). In the case when groups GiG_i can be "well approximated" by a sequence of quotient groups, we show that the critical probabilities of the free product of these approximations converge to the critical probability of G1G2...GnG_1*G_2*...*G_n and the speed of convergence is exponential. Thus for residually finite groups, for example, one can restrict oneself to the case when each free factor is finite. We show that the critical point, introduced by Schonmann, pexpp_{\mathrm{exp}} of the free product is just the minimum of pexpp_{\mathrm{exp}} for the factors

    Impact of non-Poisson activity patterns on spreading processes

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    Halting a computer or biological virus outbreak requires a detailed understanding of the timing of the interactions between susceptible and infected individuals. While current spreading models assume that users interact uniformly in time, following a Poisson process, a series of recent measurements indicate that the inter-contact time distribution is heavy tailed, corresponding to a temporally inhomogeneous bursty contact process. Here we show that the non-Poisson nature of the contact dynamics results in prevalence decay times significantly larger than predicted by the standard Poisson process based models. Our predictions are in agreement with the detailed time resolved prevalence data of computer viruses, which, according to virus bulletins, show a decay time close to a year, in contrast with the one day decay predicted by the standard Poisson process based models.Comment: 4 pages, 3 figure

    Universities, knowledge networks and regional policy

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    As knowledge becomes an increasingly important part of regional innovation and development processes, the role of universities has come to the fore of regional innovation and economic development policy The objective of this paper is to critically review and assess the structure and function of knowledge networks and modes of engagement between universities and the business community in regional settings and contexts. It is argued that while regional knowledge networks and modes of engagement between universities and the business community are becoming increasingly prevalent, it is often difficult to ascribe investments in knowledge-based infrastructure to improved regional competitiveness. It is concluded that in a globalised knowledge environment the engagement between universities and regional business communities must be based on a mutual understanding of the role of both network and market-based knowledge interactions
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