1,253 research outputs found

    Federalism in the Second Republic\u27s Third Century

    Get PDF
    I advance three propositions: (1) that the absence of amendment has not in the past, and need not in the future, stand as a barrier to startling redistribution of governmental powers; (2) that many of the circumstances which can be identified as historical precursors of such power shifts stalk current institutional arrangements at both the state and national levels and underpin the vague feeling that government just does not seem to work; and (3) that there is a new dimension to the debate which must be acknowledged if we are to profit from the experience we have already launched

    Room temperature ionic liquids with two symmetric ions

    Get PDF
    Room temperature ionic liquids typically contain asymmetric organic cations. The asymmetry is thought to enhance disorder, thereby providing an entropic counter-balance to the strong, enthalpic, ionic interactions, and leading, therefore, to lower melting points. Unfortunately, the synthesis and purification of such asymmetric cations is typically more demanding. Here we introduce novel room temperature ionic liquids in which both cation and anion are formally symmetric. The chemical basis for this unprecedented behaviour is the incorporation of ether-containing side chains – which increase the configurational entropy – in the cation. Molecular dynamics simulations indicate that the ether-containing side chains transiently sample curled configurations. Our results contradict the long-standing paradigm that at least one asymmetric ion is required for ionic liquids to be molten at room temperature, and hence open up new and simpler design pathways for these remarkable materials

    Effect of the cation structure on the properties of homobaric imidazolium ionic liquids

    Get PDF
    In this work we investigate the structure-property relationships in a series of alkylimidazolium ionic liquids with almost identical molecular weight. Using a combination of theoretical calculations and experimental measurements, we have shown that re-arranging the alkyl side chain or adding functional groups results in quite distinct features in the resultant ILs. The synthesised ILs, although structurally very similar, cover a wide spectrum of properties ranging from highly fluid, glass forming liquids to high melting point crystalline salts. Theoretical ab initio calculations provide insight on minimum energy orientations for the cations, which then are compared to experimental X-ray crystallography measurements to extract information on hydrogen bonding and to verify our understanding of the studied structures. Molecular dynamics simulations of the simplest (core) ionic liquids are used in order to help us interpret our experimental results and understand better why methylation of C^{2} position of the imidazolium ring results in ILs with such different properties compared to their non-methylated analogues

    Theory of Parabolic Arcs in Interstellar Scintillation Spectra

    Full text link
    Our theory relates the secondary spectrum, the 2D power spectrum of the radio dynamic spectrum, to the scattered pulsar image in a thin scattering screen geometry. Recently discovered parabolic arcs in secondary spectra are generic features for media that scatter radiation at angles much larger than the rms scattering angle. Each point in the secondary spectrum maps particular values of differential arrival-time delay and fringe rate (or differential Doppler frequency) between pairs of components in the scattered image. Arcs correspond to a parabolic relation between these quantities through their common dependence on the angle of arrival of scattered components. Arcs appear even without consideration of the dispersive nature of the plasma. Arcs are more prominent in media with negligible inner scale and with shallow wavenumber spectra, such as the Kolmogorov spectrum, and when the scattered image is elongated along the velocity direction. The arc phenomenon can be used, therefore, to constrain the inner scale and the anisotropy of scattering irregularities for directions to nearby pulsars. Arcs are truncated by finite source size and thus provide sub micro arc sec resolution for probing emission regions in pulsars and compact active galactic nuclei. Multiple arcs sometimes seen signify two or more discrete scattering screens along the propagation path, and small arclets oriented oppositely to the main arc persisting for long durations indicate the occurrence of long-term multiple images from the scattering screen.Comment: 22 pages, 11 figures, submitted to the Astrophysical Journa

    The Effect of Topical Fluoride on Dental Caries Experience in Adult Females of a Military Population

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66668/2/10.1177_00220345550340011801.pd

    Automating Change of Representation for Proofs in Discrete Mathematics (Extended Version)

    Get PDF
    Representation determines how we can reason about a specific problem. Sometimes one representation helps us find a proof more easily than others. Most current automated reasoning tools focus on reasoning within one representation. There is, therefore, a need for the development of better tools to mechanise and automate formal and logically sound changes of representation. In this paper we look at examples of representational transformations in discrete mathematics, and show how we have used Isabelle's Transfer tool to automate the use of these transformations in proofs. We give a brief overview of a general theory of transformations that we consider appropriate for thinking about the matter, and we explain how it relates to the Transfer package. We show our progress towards developing a general tactic that incorporates the automatic search for representation within the proving process

    Experimental violation of a Bell's inequality in time with weak measurement

    Full text link
    The violation of J. Bell's inequality with two entangled and spatially separated quantum two- level systems (TLS) is often considered as the most prominent demonstration that nature does not obey ?local realism?. Under different but related assumptions of "macrorealism", plausible for macroscopic systems, Leggett and Garg derived a similar inequality for a single degree of freedom undergoing coherent oscillations and being measured at successive times. Such a "Bell's inequality in time", which should be violated by a quantum TLS, is tested here. In this work, the TLS is a superconducting quantum circuit whose Rabi oscillations are continuously driven while it is continuously and weakly measured. The time correlations present at the detector output agree with quantum-mechanical predictions and violate the inequality by 5 standard deviations.Comment: 26 pages including 10 figures, preprint forma

    Barriers to development of private sector investment in water and sewage industry

    Get PDF
    PurposePrivatization is a complex issue in many developing countries; therefore, it is vital to examine the obstacles that prevent its proper implementation. The goal of this study is to identify and analyze the barriers to private sector investment in the Water and Sewage Industry (WSI) and to suggest effective ways to attract the private investors to this sector.Design/methodology/approachThe obstacles to private sector investment in the WSI were identified by conducting a desktop literature review and interviewing an expert panel, using the fuzzy Delphi technique. The most important barriers were identified and categorized. A structured survey was then developed and distributed to private sector investment experts. The Fuzzy Analytic Hierarchy Process (FAHP) was applied to further examine the responses and to rank the identified barriers.FindingsThe results showed that the greatest barrier to privatization is the weakness of insurance companies in controlling investment risks, and the second greatest barrier is the weakness of the country's capitalist culture. A review of recent success stories revealed that these barriers can be overcome with transparent price policies and increased interaction between the public and private sectors, which motivate private investors to invest in the WSI.Originality/valueThe elicitation of this study can be useful to both private and public sectors for the development of infrastructure projects, particularly for the WSI.</jats:sec

    Impact of metabolic comorbidity on the association between body mass index and heatlh-related quality of life: a Scotland-wide cross-sectional study of 5,608 participants

    Get PDF
    &lt;p/&gt;Background: The prevalence of obesity is rising in Scotland and globally. Overall, obesity is associated with increased morbidity, mortality and reduced health-related quality of life. Studies suggest that "healthy obesity" (obesity without metabolic comorbidity) may not be associated with morbidity or mortality. Its impact on health-related quality of life is unknown. &lt;p/&gt;Methods: We extracted data from the Scottish Health Survey on self-reported health-related quality of life, body mass index (BMI), demographic information and comorbidity. SF-12 responses were converted into an overall health utility score. Linear regression analyses were used to explore the association between BMI and health utility, stratified by the presence or absence of metabolic comorbidity (diabetes, hypertension, hypercholesterolemia or cardiovascular disease), and adjusted for potential confounders (age, sex and deprivation quintile). &lt;p/&gt;Results: Of the 5,608 individuals, 3,744 (66.8%) were either overweight or obese and 921 (16.4%) had metabolic comorbidity. There was an inverted U-shaped relationship whereby health utility was highest among overweight individuals and fell with increasing BMI. There was a significant interaction with metabolic comorbidity (p = 0.007). Individuals with metabolic comorbidty had lower utility scores and a steeper decline in utility with increasing BMI (morbidly obese, adjusted coefficient: -0.064, 95% CI -0.115, -0.012, p = 0.015 for metabolic comorbidity versus -0.042, 95% CI -0.067, -0.018, p = 0.001 for no metabolic comorbidity). &lt;p/&gt;Conclusions: The adverse impact of obesity on health-related quality of life is greater among individuals with metabolic comorbidity. However, increased BMI is associated with reduced health-related quality of life even in the absence of metabolic comorbidity, casting doubt on the notion of "healthy obesity"
    corecore