7,758 research outputs found

    The St. Bartholomew’s Icon of the Virgin Hodegetria: How Context Controls Meaning

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    Strong Analytic Controllability for Hydrogen Control Systems

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    The realization and representation of so(4,2) associated with the hydrogen atom Hamiltonian are derived. By choosing operators from the realization of so(4,2) as interacting Hamiltonians, a hydrogen atom control system is constructed, and it is proved that this control system is strongly analytically controllable based on a time-dependent strong analytic controllability theorem.Comment: 6 pages; corrected typo; added equations in section III for representation states of so(4,2). accepted by CDC 200

    Cryptocurrency: A Panacea for Economic Growth and Sustainability? A Critical Review of Crypto Innovation

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    Distributed ledger technology is highlighted as a solid tool to address social and ecological challenges.Cryptocurrency is seen as a network with a socio-technical structure since the systems are composed of technical infrastructure and the social relations between users of the crypto ecosystem. The sociopolitical ramifications of cryptocurrency are critically assessed to identify key features and conceptualize issues to unlock opportunities to guarantee a sociotechnical approach to blockchains. Despite progressive initiatives, a series of challenges, such as trust, cybersecurity, and scalability, have emerged as cryptocurrency begins to develop its full potential. With these issues, sociotechnical concerns have surfaced regarding how to respond to the possible consequences that such a policy choice would entail, how to govern the crypto economy, and how to create a sustainable crypto ecosystem. We argue that cryptocurrency is a socio-technical system that constitutes new and important objects of social inquiry that must be addressed beyond the myopic context of a financial asset

    Fuzzy approach to construction activity estimation

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    Past experience has shown that variations in production rate value for the same work item is attributed to a wide range of factors. The relationships between these factors and the production rates are often very complex. It is impossible to describe an exact mathematical causal relationship between the qualitative factors(QF) and production rates. Various subjective approaches have been attempted to quantify the uncertainties contained in these causal relationships. This thesis presents one such approach by adopting a fuzzy set theory in conjunction with a fuzzy rule based system that could improve the quantification of the qualitative factors in estimating construction activity durations and costs. A method to generate a Standard Activity Unit Rate(SAUR) is presented. A construction activity can be defined by combining the Design Breakdown Structure, Trade Breakdown Structure and Work Section Breakdown Structure. By establishing the data structure of an activity, it is possible to synthesis the SAUR from published estimating sources in a systematic way. After the SAUR is defined, it is then used as a standard value from which an appropriate Activity Unit Rate(AUR) can be determined. A proto-type fuzzy rule based system called 'Fuzzy Activity Unit Rate Analyser(FAURA)' was developed to formalise a systematic framework for the QF quantification process in determining the most likely activity duration/cost. The compatibility measurement method proposed by Nafarieh and Keller has been applied as an inference strategy for FAURA. A computer program was developed to implement FAURA using Turbo Prolog. FAURA was tested and analysed by using a hypothetical bricklayer's activity in conjunction with five major QF as the input variables. The results produced by FAURA iii show that it can be applied usefully to overcome many of the problems encountered in the QF quantification process. In addition, the analysis shows that a fuzzy rule base approach provides the means to model and study the variability of AUR. Although the domain problem of this research was in estimation of activity duration/cost, the principles and system presented in this study are not limited to this specific area, and can be applied to a wide range of other disciplines involving uncertainty quantification problems. Further, this research highlights how the existing subjective methods in activity duration/cost estimation can be enhanced by utilising fuzzy set theory and fuzzy logic

    Therapeutic applications of ghrelin agonists in the treatment of gastroparesis

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    There remains an unmet need for effective pharmacologic treatments for gastroparesis. Ghrelin is the endogenous ligand for the growth hormone secretagogue receptor and has been shown to regulate energy homeostasis and exert prokinetic effects on gastrointestinal motility. In recent years, several ghrelin receptor agonists have been studied in clinical trials of patients with diabetic gastroparesis. The intravenous macrocyclic peptidomimetic, TZP-101, initially suggested improvement in gastroparesis symptoms with intravenous administration when compared to placebo. However, in subsequent studies of oral preparations, TZP-102 failed to confirm these results. Another ghrelin receptor agonist, RM-131, was recently shown to significantly accelerate gastric emptying (GE) in patients with type 1 and type 2 diabetes and delayed GE. RM-131 reduced total Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD) and composite scores among type 1 diabetics. Continued development of ghrelin agonists should be explored in attempts to expand therapeutic options for the treatment of gastroparesis

    Functional characterization of a constitutively active kinase variant of Arabidopsis phototropin 1

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    Phototropins (phots) are plasma membrane-associated serine/threonine kinases that coordinate a range of processes linked to optimizing photosynthetic efficiency in plants. These photoreceptors contain two light-, oxygen- or voltage-sensing (LOV) domains within their N-terminus, with each binding one molecule of flavin mononucleotide (FMN) as a UV/blue light absorbing chromophore. Although phots contain two LOV domains, light-induced activation of the C-terminal kinase domain and subsequent receptor autophosphorylation is controlled primarily by the A′α-LOV2-Jα photosensory module. Mutations that disrupt interactions between the LOV2-core and its flanking helical segments can uncouple this mode of light regulation. Yet, the impact of these mutations on phot function in Arabidopsis has not been explored. Here, we report that histidine substitution of Arg-472 located within the A′α-helix of Arabidopsis phot1 to histidine results in constitutively activates kinas activity in vitro without affecting LOV2 photochemistry. Expression analysis of phot1 R472H in the phot-deficient mutant confirmed that it is autophosphorylated in darkness in vivo, but was unable to initiate phot1 signaling in the absence of light. Instead, we found that the phot1 R472H mutant is poorly functional under low-light conditions, but can restore phototropism, chloroplast accumulation, stomatal opening, and leaf positioning and expansion at higher light intensities. Our findings suggest that Arabidopsis can adapt to the elevated phosphorylation status of the phot1 R472H mutant by in part reducing its stability, whereas the activity the mutant under high-light conditions can be attributed to additional increases in LOV2-mediated photoreceptor autophosphorylation
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