954 research outputs found

    Kinetics and mechanism of the formation of water cluster ions from O2(plus) and H2O in He, Ar, N2, and O2 at 296 K

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    The reaction sequence leading from O2(+) to H3O(+)-H2O was examined in He, Ar, N2 and O2 carrier gases in a flowing afterglow system. The rate constants for the reactions were measured and the kinetic analysis for their determination is presented. For M = N2, two new steps involving the formation and reaction of O2(+)-N2 were proposed and examined. The rate constants are discussed and compared with other experimental values

    Modifications of Hyaluronan Influence the Interaction with Human Bone Morphogenetic Protein-4 (hBMP-4).

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    n this study, we have demonstrated that the modification of hyaluronan (hyaluronic acid; Hya) with sulfate groups led to different binding affinities for recombinant human bone morphogenetic protein-4 (rhBMP-4). The high-sulfated sHya2.8 (average degree of sulfation (D.S.) 2.8) exhibited the tightest interaction with rhBMP-4, followed by the low-sulfated sHya1.0, as determined with surface plasmon resonance (SPR), ELISA, and competition ELISA. Unmodified Hya, chondroitin-sulfate (CS), and heparan sulfate (HS) showed significantly less binding affinity. SPR data could be fitted to an A + B = AB Langmuir model and binding constants were evaluated ranging from 13 pM to 5.45 microM. The interaction characteristics of the differentially sulfated Hyas are promising for the incorporation of these modified polysaccharides in bioengineered coatings of biomaterials for medical applications

    Deterministic and stochastic descriptions of gene expression dynamics

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    A key goal of systems biology is the predictive mathematical description of gene regulatory circuits. Different approaches are used such as deterministic and stochastic models, models that describe cell growth and division explicitly or implicitly etc. Here we consider simple systems of unregulated (constitutive) gene expression and compare different mathematical descriptions systematically to obtain insight into the errors that are introduced by various common approximations such as describing cell growth and division by an effective protein degradation term. In particular, we show that the population average of protein content of a cell exhibits a subtle dependence on the dynamics of growth and division, the specific model for volume growth and the age structure of the population. Nevertheless, the error made by models with implicit cell growth and division is quite small. Furthermore, we compare various models that are partially stochastic to investigate the impact of different sources of (intrinsic) noise. This comparison indicates that different sources of noise (protein synthesis, partitioning in cell division) contribute comparable amounts of noise if protein synthesis is not or only weakly bursty. If protein synthesis is very bursty, the burstiness is the dominant noise source, independent of other details of the model. Finally, we discuss two sources of extrinsic noise: cell-to-cell variations in protein content due to cells being at different stages in the division cycles, which we show to be small (for the protein concentration and, surprisingly, also for the protein copy number per cell) and fluctuations in the growth rate, which can have a significant impact.Comment: 23 pages, 5 figures; Journal of Statistical physics (2012

    Climate change adaptation to escape the poverty trap: role of the private sector

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    Climate change adaptation and poverty alleviation call for an integrated strategy, because poverty exacerbates the vulnerability to climate change and vice versa. The private sector, which has traditionally been excluded from adaptation planning, may contribute greatly to the development of an integrated strategy. Here, we identify the differences in adaptation trajectories between the private sector and communities by proposing a conceptual framework and report on a case study in a dryland area of China, where the private sector led a successful adaptation and poverty alleviation project. We found that their win–win strategy achieved both climate change adaptation and development, thereby helping a disadvantaged community to escape the poverty trap and achieve sustainable development. The private sector played a dominant role in the response, as this sector can adapt in ways that are not possible for governments or communities. We suggest that participatory governance that includes private-sector stakeholders is more likely to achieve sustainable development

    Weirdest Martensite: Smectic Liquid Crystal Microstructure And Weyl-poincaré Invariance

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    Smectic liquid crystals are remarkable, beautiful examples of materials microstructure, with ordered patterns of geometrically perfect ellipses and hyperbolas. The solution of the complex problem of filling three-dimensional space with domains of focal conics under constraining boundary conditions yields a set of strict rules, which are similar to the compatibility conditions in a martensitic crystal. Here we present the rules giving compatible conditions for the concentric circle domains found at two-dimensional smectic interfaces with planar boundary conditions. Using configurations generated by numerical simulations, we develop a clustering algorithm to decompose the planar boundaries into domains. The interfaces between different domains agree well with the smectic compatibility conditions. We also discuss generalizations of our approach to describe the full three-dimensional smectic domains, where the variant symmetry group is the Weyl-Poincaré group of Lorentz boosts, translations, rotations, and dilatations. © 2016 American Physical Society.1161

    Chronic and transitory poverty in the Kyrgyz Republic: what can synthetic panels tell us?

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    Optics and Quantum Electronics

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    Contains table of contents for Section 2 and reports on eleven research projects.Joint Services Electronics Program Contract DAAL03-89-C-0001National Science Foundation Grant EET 87-00474U.S. Air Force - Office of Scientific Research Contract F49620-88-C-0089Charles S. Draper Laboratory Contract DL-H-404179National Center for Integrated PhotonicsNational Science Foundation Grant ECS 87-18417NEC Research InstituteNational Science Foundation Grant ECS 85-52701Medical Free Electron Laser Program Contract N00014-86-K-0117National Institutes of Health Grant 5-RO1-GM35459Lawrence Livermore National Laboratory Contract B048704U.S. Department of Energy Grant DE-FG02-89-ER14012Columbia University Contract P016310

    Communicating risk in active surveillance of localised prostate cancer: A protocol for a qualitative study

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    Introduction One in five men is likely to receive a diagnosis of prostate cancer (PCa) by the age of 85 years. Men diagnosed with low-risk PCa may be eligible for active surveillance (AS) to monitor their cancer to ensure that any changes are discovered and responded to in a timely way. Communication of risk in this context is more complicated than determining a numerical probability of risk, as patients wish to understand the implications of risk on their lives in concrete terms. Our study will examine how risk for PCa is perceived, experienced and communicated by patients using AS with their health professionals, and the implications for treatment and care. Methods and analysis This is a proof of concept study, testing out a multimethod, qualitative approach to data collection in the context of PCa for the first time in Australia. It is being conducted from November 2016 to December 2017 in an Australian university hospital urology clinic. Participants are 10 men with a diagnosis of localised PCa, who are using an AS protocol, and 5 health professionals who work with this patient group (eg, urologists and Pca nurses). Data will be collected using observations of patient consultations with health professionals, patient questionnaires and interviews, and interviews with healthcare professionals. Analysis will be conducted in two stages. First, observational data from consultations will be analysed thematically to encapsulate various dimensions of risk classification and consultation dialogue. Second, interview data will be coded to derive meaning in text and analysed thematically. Overarching themes will represent patient and health professional perspectives of risk communication. Ethics and dissemination Ethical approval for the study has been granted by Macquarie University Human Research Ethics Committee, approval 5201600638. Knowledge translation will be achieved through publications, reports and conference presentations to patients, families, clinicians and researchers
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