4,849 research outputs found

    Terminal deoxynucleotidyltransferase. Serological studies and radioimmunoassay

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    Mouse antisera against calf terminal deoxynucleotidyltransferase (terminal transferase) have been prepared. The sera have been used to characterize terminal transferase both by studying inhibition of enzyme activity and by developing a competition radioimmunoassay using highly purified 125I-labeled terminal transferase. By either assay, anti-terminal transferase serum did not cross-react significantly with calf DNA polymerases alpha and beta, Escherichia coli DNA polymerase I, or the reverse transcriptase of Moloney mouse leukemia virus. The calf terminal transferase did, however, share cross-reactive but not identical determinants with human and murine terminal transferase. The radioimmunoassay could detect as little as 2 ng of terminal transferase/mg of soluble protein in a tissue extract. Thymocytes were found to contain 280 ng of terminal transferase/mg of cell protein or about 1 X 10^(5) molecules/cell; bone marrow had about 1% of the level of enzyme found in thymus. Extracts of spleen, peripheral white blood cells, lymph nodes, liver, muscle, and kidney all lacked detectable antigenicity of terminal transferase. These data indicate that terminal transferase is a tissue-specific enzyme and is not related to other DNA polymerases

    Workflow Variability for Autonomic IoT Systems

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    Autonomic IoT systems require variable behaviour at runtime to adapt to different system contexts. Building suitable models that span both design-time and runtime is thus essential for such systems. However, existing approaches separate the variability model from the behavioural model, leading to synchronization issues such as the need for dynamic reconfiguration and dependency management. Some approaches define a fixed number of behaviour variants and are therefore unsuitable for highly variable contexts. This paper extends the semantics of the DX-MAN service model so as to combine variability with behaviour. The model allows the design of composite services that define an infinite number of workflow variants which can be chosen at runtime without any reconfiguration mechanism. We describe the autonomic capabilities of our model by using a case study in the domain of smart homes

    Analysis and Classification of Service Interactions for the Scalability of the Internet of Things

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    Scalability is an important concern for Internet of Things (IoT) applications since the amount of service interactions may become overwhelming, due to the huge number of interconnected nodes. In this paper, we present an IoT scenario for real-time Electrocardiogram (ECG) monitoring, in order to analyze how well different kinds of service interactions can fulfill the scalability requirements of IoT applications

    Stability of nonuniform rotor blades in hover using a mixed formulation

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    A mixed formulation for calculating static equilibrium and stability eigenvalues of nonuniform rotor blades in hover is presented. The static equilibrium equations are nonlinear and are solved by an accurate and efficient collocation method. The linearized perturbation equations are solved by a one step, second order integration scheme. The numerical results correlate very well with published results from a nearly identical stability analysis based on a displacement formulation. Slight differences in the results are traced to terms in the equations that relate moments to derivatives of rotations. With the present ordering scheme, in which terms of the order of squares of rotations are neglected with respect to unity, it is not possible to achieve completely equivalent models based on mixed and displacement formulations. The one step methods reveal that a second order Taylor expansion is necessary to achieve good convergence for nonuniform rotating blades. Numerical results for a hypothetical nonuniform blade, including the nonlinear static equilibrium solution, were obtained with no more effort or computer time than that required for a uniform blade

    It\u27s getting complicated-A fresh look at p53-MDM2-ARF triangle in tumorigenesis and cancer therapy

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    Anti-tumorigenic mechanisms mediated by the tumor suppressor p53, upon oncogenic stresses, are our bodies\u27 greatest weapons to battle against cancer onset and development. Consequently, factors that possess significant p53-regulating activities have been subjects of serious interest from the cancer research community. Among them, MDM2 and ARF are considered the most influential p53 regulators due to their abilities to inhibit and activate p53 functions, respectively. MDM2 inhibits p53 by promoting ubiquitination and proteasome-mediated degradation of p53, while ARF activates p53 by physically interacting with MDM2 to block its access to p53. This conventional understanding of p53-MDM2-ARF functional triangle have guided the direction of p53 research, as well as the development of p53-based therapeutic strategies for the last 30 years. Our increasing knowledge of this triangle during this time, especially through identification of p53-independent functions of MDM2 and ARF, have uncovered many under-appreciated molecular mechanisms connecting these three proteins. Through recognizing both antagonizing and synergizing relationships among them, our consideration for harnessing these relationships to develop effective cancer therapies needs an update accordingly. In this review, we will re-visit the conventional wisdom regarding p53-MDM2-ARF tumor-regulating mechanisms, highlight impactful studies contributing to the modern look of their relationships, and summarize ongoing efforts to target this pathway for effective cancer treatments. A refreshed appreciation of p53-MDM2-ARF network can bring innovative approaches to develop new generations of genetically-informed and clinically-effective cancer therapies

    Edited NSSL meso-scale upper air network data in southwestern Oklahoma, 1966 and 1967

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    Cover title."Atmospheric General Circulation Technical Document No. 1.

    Probing the inter-layer exciton physics in a MoS2_2/MoSe2_2/MoS2_2 van der Waals heterostructure

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    Stacking atomic monolayers of semiconducting transition metal dichalcogenides (TMDs) has emerged as an effective way to engineer their properties. In principle, the staggered band alignment of TMD heterostructures should result in the formation of inter-layer excitons with long lifetimes and robust valley polarization. However, these features have been observed simultaneously only in MoSe2_2/WSe2_2 heterostructures. Here we report on the observation of long lived inter-layer exciton emission in a MoS2_2/MoSe2_2/MoS2_2 trilayer van der Waals heterostructure. The inter-layer nature of the observed transition is confirmed by photoluminescence spectroscopy, as well as by analyzing the temporal, excitation power and temperature dependence of the inter-layer emission peak. The observed complex photoluminescence dynamics suggests the presence of quasi-degenerate momentum-direct and momentum-indirect bandgaps. We show that circularly polarized optical pumping results in long lived valley polarization of inter-layer exciton. Intriguingly, the inter-layer exciton photoluminescence has helicity opposite to the excitation. Our results show that through a careful choice of the TMDs forming the van der Waals heterostructure it is possible to control the circular polarization of the inter-layer exciton emission.Comment: 19 pages, 3 figures. Just accepted for publication in Nano Letters (http://pubs.acs.org/doi/10.1021/acs.nanolett.7b03184
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