27,369 research outputs found

    Exit from inflation and a paradigm for vanishing cosmological constant in self-tuning models

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    We propose a paradigm for the inflation and the vanishing cosmological constant in a unified way with the self-tuning solutions of the cosmological constant problem. Here, we consider a time-varying cosmological constant in self-tuning models of the cosmological constant. As a specific example, we demonstrate it with a 3-form field in 5D.Comment: 11 pages of LaTeX fil

    Biodegradable polymeric prodrugs of naltrexone

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    The development of a biodegradable polymeric drug delivery system for the narcotic antagonist naltrexone may improve patient compliance in the treatment of opiate addiction. Random copolymers consisting of the ¿-amino acids N5-(3-hydroxypropyl--glutamine and -leucine were synthesized with equimolar initial monomer feeds. The molecular weight of this chemical carrier was determined by viscometry and wide-angle light scattering. In order to get selective covalent coupling of drug to polymer the 3-acetate derivative and the 14-acetate derivative of naltrexone were synthesized and characterized by NMR. Hydrolytic conversion of each monoacetate to parent drug was monitored by HPLC and the rate constant was determined. Both derivatives were coupled via hydrolytically labile carbonate linkages to the polymer hydroxyl groups. The drug conjugates were prepared as particles of various size ranges between 20 and 350 ¿. In vitro studies in phosphate-buffered saline (pH 7.4) demonstrated a release rate dependence on particle size. Nearly constant plasma levels of naltrexone were obtained for one month after subcutaneous injection in rats

    Taste symmetry breaking with HYP-smeared staggered fermions

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    We study the impact of hypercubic (HYP) smearing on the size of taste breaking for staggered fermions, comparing to unimproved and to asqtad-improved staggered fermions. As in previous studies, we find a substantial reduction in taste-breaking compared to unimproved staggered fermions (by a factor of 4-7 on lattices with spacing a0.1a\approx 0.1 fm). In addition, we observe that discretization effects of next-to-leading order in the chiral expansion (O(a2p2){\cal O}(a^2 p^2)) are markedly reduced by HYP smearing. Compared to asqtad valence fermions, we find that taste-breaking in the pion spectrum is reduced by a factor of 2.5-3, down to a level comparable to the expected size of generic O(a2){\cal O}(a^2) effects. Our results suggest that, once one reaches a lattice spacing of a0.09a\approx 0.09 fm, taste-breaking will be small enough after HYP smearing that one can use a modified power counting in which O(a2)O(p2){\cal O}(a^2) \ll {\cal O}(p^2), simplify fitting to phenomenologically interesting quantities.Comment: 14 pages, 13 figures, references updated, minor change

    Increasing participation in the information society by people with disabilities and their families in lower-income countries using mainstream technologies

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    Assistive technology (AT) has been actively researched, developed and implemented throughout higher-income countries, but is relatively absent from lower-income countries. In lower-income countries, there is very little AT for reading, writing, communicating and for participation in the information society. In order for persons with disabilities in lower-income countries to participate fully in society, mainstream information and communication technologies (ICTs) such as mobile phones should be used as AT. This paper explores the potential for using mainstream ICTs as AT in lower-income countries, keeping in mind current ICT trends, characteristics of the post-PC era and ICT-based AT in higher-income countries. The paper concludes with a case study where mobile phones and SMS were used by people with disabilities and their caregivers to access information in a resourced-limited community in Bogota, Colombia. Mobile phones, a readily available mainstream ICT in this community, were a useful tool for addressing the information exclusion of people with disabilities and caregivers

    Strange and singlet form factors of the nucleon: Predictions for G0, A4, and HAPPEX-II experiments

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    We investigate the strange and flavor-singlet electric and magnetic form factors of the nucleon within the framework of the SU(3) chiral quark-soliton model. Isospin symmetry is assumed and the symmetry-conserving SU(3) quantization is employed, rotational and strange quark mass corrections being included. For the experiments G0, A4, and HAPPEX-II we predict the quantities GE0+βGM0G^{0}_E + \beta G^{0}_M and GEs+βGMsG^{\rm s}_E + \beta G^{\rm s}_M. The dependence of the results on the parameters of the model and the treatment of the Yukawa asymptotic behavior of the soliton are investigated.Comment: 16 pages, 3 figures, Final version for publication in Eur. Phys. J.

    Linking a Pharmaceutical Chemistry Workshop to Pharmacy Practice

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    This paper describes the design and implementation of a workshop to enhance pharmacy students’ appreciation of the importance of chemistry for pharmacy practice. The workshop was designed to form part of the practical work of two modules taught in the second year of the MPharm degree. In this mandatory workshop, second year pharmacy students were required to spot in the dispensary drugs based on their chemical properties like chirality, their origin and chemical structure. The lecturers involved in the workshop showed examples of the application of chemistry in the day to day work of the dispensary (e.g. calculating the dose for a patient in millimoles or how small modifications from a natural product can change its ability to cross the blood-brain-barrier). Feedback from participating students was collected via two survey instruments to examine the impact of the intervention. The survey results showed a clear shift towards a more positive perception by students of the chemistry taught in the MPharm curriculum
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