Critical fluctuations and quenched disordered two-dimensional charge stripes in La5/3Sr1/3NiO4

[[abstract]]Using high-resolution x-ray scattering, we have demonstrated the existence of quenched disordered charge stripes in a single crystal of La5/3Sr1/3NiO4 at low temperatures. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. The charge stripes are shown to be two dimensional in nature both by measurements of their correlation lengths (xi(a) approximate to 185 Angstrom, xi(b) = 400 Angstrom, and xi(c) approximate to 25 Angstrom) and by the critical exponents of the charge strip transition. The charge stripe orderings did not develop long-range order even at low temperatures, indicating that the charge stripes are disordered and that the length scale of the disorder is quenched.[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

The stability of the ways of coping (revised) questionnaire over time in parents of children with Downs-Syndrome:a research note

The stability of the Ways of Coping (Revised) Questionnaire over time was assessed by comparing the scores of 68 mothers and 53 fathers of school-aged children with Down's syndrome over a 3-year time interval on the five coping strategy subscales described by Knussen et al. (1992). For this analysis, mothers' and fathers' scores were analysed separately. It was shown by t tests that mothers' and fathers' scores on the coping strategy subscales had not significantly changed over the three-year period. Time 1 and Time 2 scores on all of the coping subscales were strongly positively associated, with the exception of fathers' scores on the Stoicism subscale. Test-retest reliability was adequate for all subscales except mothers' scores on the Passive Acceptance subscale and fathers' scores on the Stoicism subscale. These results, by demonstrating the stability of the Ways of Coping (Revised) Questionnaire over a 3-year time period, further illustrate the utility of this instrument for investigating coping in families with special problems

Racial and economic factors in attitudes to immigration

In this paper we distinguish between three channels that determine attitudes to further immigration: labour market concerns, welfare concerns, and racial or cultural concerns. Our analysis is based on the British Social Attitudes Survey. A unique feature of the survey is that it includes questions on attitudes towards immigration from different origin countries, with populations differing in ethnic similarity to the resident population. It also contains sets of questions relating directly to the labour market, benefit expenditure and welfare concerns, and racial and cultural prejudice. Based on this unique data source, we specify and estimate a multiple factor model that allows comparison of the relative magnitude of association of attitudes to further immigration with the three channels, as well as comparison in responses across potential immigrant groups of different origin. Our results suggest that, overall, welfare concerns play a more important role in determination of attitudes to further immigration than labour market concerns, with their relative magnitude differing across potential emigration regions and characteristics of the respondent. In addition, we find strong evidence that racial or cultural prejudice is an important component to attitudes towards immigration; however, this is restricted to immigration from countries with ethnically different populations

Design diversity: an update from research on reliability modelling

Diversity between redundant subsystems is, in various forms, a common design approach for improving system dependability. Its value in the case of software-based systems is still controversial. This paper gives an overview of reliability modelling work we carried out in recent projects on design diversity, presented in the context of previous knowledge and practice. These results provide additional insight for decisions in applying diversity and in assessing diverseredundant systems. A general observation is that, just as diversity is a very general design approach, the models of diversity can help conceptual understanding of a range of different situations. We summarise results in the general modelling of common-mode failure, in inference from observed failure data, and in decision-making for diversity in development.

Charmonium properties from lattice QCD + QED: hyperfine splitting, J/ψJ/\psi leptonic width, charm quark mass and aμca_{\mu}^c

We have performed the first $n_f = 2+1+1$ lattice QCD computations of the properties (masses and decay constants) of ground-state charmonium mesons. Our calculation uses the HISQ action to generate quark-line connected two-point correlation functions on MILC gluon field configurations that include $u/d$ quark masses going down to the physical point, tuning the $c$ quark mass from $M_{J/\psi}$ and including the effect of the $c$ quark's electric charge through quenched QED. We obtain $M_{J/\psi}-M_{\eta_c}$ (connected) = 120.3(1.1) MeV and interpret the difference with experiment as the impact on $M_{\eta_c}$ of its decay to gluons, missing from the lattice calculation. This allows us to determine $\Delta M_{\eta_c}^{\mathrm{annihiln}}$ =+7.3(1.2) MeV, giving its value for the first time. Our result of $f_{J/\psi}=$ 0.4104(17) GeV, gives $\Gamma(J/\psi \rightarrow e^+e^-)$=5.637(49) keV, in agreement with, but now more accurate than experiment. At the same time we have improved the determination of the $c$ quark mass, including the impact of quenched QED to give $\overline{m}_c(3\,\mathrm{GeV})$ = 0.9841(51) GeV. We have also used the time-moments of the vector charmonium current-current correlators to improve the lattice QCD result for the $c$ quark HVP contribution to the anomalous magnetic moment of the muon. We obtain $a_{\mu}^c = 14.638(47) \times 10^{-10}$, which is 2.5$\sigma$ higher than the value derived using moments extracted from some sets of experimental data on $R(e^+e^- \rightarrow \mathrm{hadrons})$. This value for $a_{\mu}^c$ includes our determination of the effect of QED on this quantity, $\delta a_{\mu}^c = 0.0313(28) \times 10^{-10}$.Comment: Added extra discussion on QED setup, some new results to study the effects of strong isospin breaking in the sea (including new Fig. 1) and a fit stability plot for the hyperfine splitting (new Fig. 7). Version accepted for publication in PR

Charge ordering and the related structural phase transition in single crystal Bi0.24Ca0.76MnO3

[[abstract]]A single crystal of ~Bi0.24Ca0.76!MnO3 has been extensively studied using both laboratory and synchrotron radiation x-ray scattering. Using x-ray techniques we can directly observe the formation of charge stripes associated with the low-temperature structural phase transition. Weak satellite peaks with a modulation wave vector q'(0.24, 0.24, 0) were observed below the transition temperature. These are associated with the charge ordering of Mn31 and Mn41 ions into charge ~and spin! stripes within the perovskite structure. Measurements of the temperature dependence of the intensity and width of the charge-ordering satellites over the temperature range 10–240 K were also completed. These demonstrate the first-order nature of the structural phase transition that accompanies the formation of charge and spin ordering. Measurements of the width of the charge-order satellites demonstrate that the correlation length of the charge order is long range at all temperatures, and in all directions, below the structural phase transition.[[incitationindex]]SCI[[booktype]]紙

Rapid Mix Preparation of Bioinspired Nanoscale Hydroxyapatite for Biomedical Applications

Hydroxyapatite (HA) has been widely used as a medical ceramic due to its good biocompatibility and osteoconductivity. Recently there has been interest regarding the use of bioinspired nanoscale hydroxyapatite (nHA). However, biological apatite is known to be calcium-deficient and carbonate-substituted with a nanoscale platelet-like morphology. Bioinspired nHA has the potential to stimulate optimal bone tissue regeneration due to its similarity to bone and tooth enamel mineral. Many of the methods currently used to fabricate nHA both in the laboratory and commercially, involve lengthy processes and complex equipment. Therefore, the aim of this study was to develop a rapid and reliable method to prepare high quality bioinspired nHA. The rapid mixing method developed was based upon an acid-base reaction involving calcium hydroxide and phosphoric acid. Briefly, a phosphoric acid solution was poured into a calcium hydroxide solution followed by stirring, washing and drying stages. Part of the batch was sintered at 1,000 °C for 2 h in order to investigate the products' high temperature stability. X-ray diffraction analysis showed the successful formation of HA, which showed thermal decomposition to β-tricalcium phosphate after high temperature processing, which is typical for calcium-deficient HA. Fourier transform infrared spectroscopy showed the presence of carbonate groups in the precipitated product. The nHA particles had a low aspect ratio with approximate dimensions of 50 x 30 nm, close to the dimensions of biological apatite. The material was also calcium deficient with a Ca:P molar ratio of 1.63, which like biological apatite is lower than the stoichiometric HA ratio of 1.67. This new method is therefore a reliable and far more convenient process for the manufacture of bioinspired nHA, overcoming the need for lengthy titrations and complex equipment. The resulting bioinspired HA product is suitable for use in a wide variety of medical and consumer health applications

An Overview of Poly(lactic-co-glycolic) Acid (PLGA)-Based Biomaterials for Bone Tissue Engineering

Poly(lactic-co-glycolic) acid (PLGA) has attracted considerable interest as a base material for biomedical applications due to its: (i) biocompatibility; (ii) tailored biodegradation rate (depending on the molecular weight and copolymer ratio); (iii) approval for clinical use in humans by the U.S. Food and Drug Administration (FDA); (iv) potential to modify surface properties to provide better interaction with biological materials; and (v) suitability for export to countries and cultures where implantation of animal-derived products is unpopular. This paper critically reviews the scientific challenge of manufacturing PLGA-based materials with suitable properties and shapes for specific biomedical applications, with special emphasis on bone tissue engineering. The analysis of the state of the art in the field reveals the presence of current innovative techniques for scaffolds and material manufacturing that are currently opening the way to prepare biomimetic PLGA substrates able to modulate cell interaction for improved substitution, restoration, or enhancement of bone tissue function