208 research outputs found

    Measurement of the local Jahn-Teller distortion in LaMnO_3.006

    Full text link
    The atomic pair distribution function (PDF) of stoichiometric LaMnO_3 has been measured. This has been fit with a structural model to extract the local Jahn-Teller distortion for an ideal Mn(3+)O_6 octahedron. These results are compared to Rietveld refinements of the same data which give the average structure. Since the local structure is being measured in the PDF there is no assumption of long-range orbital order and the real, local, Jahn-Teller distortion is measured directly. We find good agreement both with published crystallographic results and our own Rietveld refinements suggesting that in an accurately stoichiometric material there is long range orbital order as expected. The local Jahn-Teller distortion has 2 short, 2 medium and 2 long bonds.Comment: 5 pages, 3 postscript figures, minor change

    Nanosized Sodium-Doped Lanthanum Manganites: Role of the Synthetic Route on their Physical Properties

    Full text link
    In this paper we present the results of the synthesis and characterisation of nanocrystalline La1-xNaxMnO3+delta samples. Two synthetic routes were employed: polyacrylamide-based sol-gel and propellant synthesis. Pure, single phase materials were obtained with grain size around 35 nm for the sol-gel samples and around 55 nm for the propellant ones, which moreover present a more broaden grain size distribution. For both series a superparamagnetic behaviour was evidenced by means of magnetisation and EPR measurements with peculiar features ascribable to the different grain sizes and morphology. Preliminary magnetoresistivity measurements show enhanced low-field (< 1 T) magnetoresistance values which suggest an interesting applicative use of these manganites.Comment: 31 Pages 10 Figures to appear in Chem. Mate

    Randomised trial of a decision aid and its timing for women being tested for a BRCA1/2 mutation

    Get PDF
    Contains fulltext : 57882.pdf (publisher's version ) (Closed access)The aim of the study was to evaluate the impact of a decision aid (DA) and its timing in women being tested for a BRCA1/2 mutation. Women with and without a previous history of cancer were included after blood sampling for genetic testing. The DA consisted of a brochure and video providing information on screening and prophylactic surgery. To evaluate the impact of the DA, women were randomised to the DA group (n=184), receiving the DA 2 weeks after blood sampling, or to the control group (n=184). To evaluate the impact of timing, mutation carriers who had received the DA before the test result (n=47) were compared to mutation carriers who received the DA after the test result (n=42). Data were collected on well-being, treatment choice, decision and information related outcomes. The impact of the DA was measured 4 weeks after blood sampling. The impact of timing was measured 2 weeks after a positive test result. The DA had no impact on well-being. Regarding decision related outcomes, the DA group more frequently considered prophylactic surgery (P=0.02) corroborated with higher valuations (P=0.04). No differences were found for the other decision related outcomes. Regarding information related outcomes, the DA group felt better informed (P=0.00), was more satisfied with the information (P=0.00), and showed more accurate risk perceptions. Timing of the DA had no effect on any of the outcomes. No interactions were found between the DA and history of cancer. In conclusion, women being tested for a BRCA1/2 mutation benefit from the DA on information related outcomes. Because timing had no effect, the DA is considered useful either before or after the test result

    Strain effect on electronic transport and ferromagnetic transition temperature in La0.9_{0.9}Sr0.1_{0.1}MnO3_{3} thin films

    Full text link
    We report on a systematic study of strain effects on the transport properties and the ferromagnetic transition temperature TcT_{c} of high-quality La0.9_{0.9}Sr0.1_{0.1}MnO3_{3} thin films epitaxially grown on (100) SrTiO3_{3} substrates. Both the magnetization and the resistivity are critically dependent on the film thickness. TcT_{c} is enhanced with decreasing the film thickness due to the compressive stain produced by lattice mismatch. The resistivity above 165 K of the films with various thicknesses is consistent with small polaronic hopping conductivity. The polaronic formation energy EPE_{P} is reduced with the decrease of film thickness. We found that the strain dependence of TcT_{c} mainly results from the strain-induced electron-phonon coupling. The strain effect on EPE_{P} is in good agreement with the theoretical predictions.Comment: 6 pages and 5 figures, accepted for publication in Phys. Rev.

    Development of a multiplexed bead-based immunoassay for the simultaneous detection of antibodies to 17 pneumococcal proteins

    Get PDF
    Presently, several pneumococcal proteins are being evaluated as potential vaccine candidates. Here, we gather novel insights in the immunogenicity of PLY, PsaA, PspA, PspC, NanA, Hyl, PpmA, SlrA, Eno, IgA1-protease, PdBD, BVH-3, SP1003, SP1633, SP1651, SP0189 and SP0376. We developed a multiplex bead-based immunoassay (xMAP® Technology, Luminex Corporation) to simultaneously quantify antibodies against these 17 pneumococcal proteins in serum. The median fluorescence intensity (MFI) values obtained for human pooled serum with the multiplex assay were between 82% and 111% (median 94%) of those obtained with the singleplex assays. For IgG, the coefficient of variation (CV) in serum ranged from 2% to 9%, for IgA, the CV ranged from 3% to 14% and for IgM, the CV ranged from 11% to 15%. Using this immunoassay, we showed that anti-pneumococcal antibody levels exhibited extensive inter-individual variability in young children suffering from invasive pneumococcal disease. All proteins, including the proteins with, as yet, unknown function, were immunogenic. In conclusion, the multiplex Streptococcus pneumoniae immunoassay based on proteins is reproducible. This assay can be used to monitor anti-S. pneumoniae antibody responses in a material- and time-saving manner

    How a Diverse Research Ecosystem Has Generated New Rehabilitation Technologies: Review of NIDILRR’s Rehabilitation Engineering Research Centers

    Get PDF
    Over 50 million United States citizens (1 in 6 people in the US) have a developmental, acquired, or degenerative disability. The average US citizen can expect to live 20% of his or her life with a disability. Rehabilitation technologies play a major role in improving the quality of life for people with a disability, yet widespread and highly challenging needs remain. Within the US, a major effort aimed at the creation and evaluation of rehabilitation technology has been the Rehabilitation Engineering Research Centers (RERCs) sponsored by the National Institute on Disability, Independent Living, and Rehabilitation Research. As envisioned at their conception by a panel of the National Academy of Science in 1970, these centers were intended to take a “total approach to rehabilitation”, combining medicine, engineering, and related science, to improve the quality of life of individuals with a disability. Here, we review the scope, achievements, and ongoing projects of an unbiased sample of 19 currently active or recently terminated RERCs. Specifically, for each center, we briefly explain the needs it targets, summarize key historical advances, identify emerging innovations, and consider future directions. Our assessment from this review is that the RERC program indeed involves a multidisciplinary approach, with 36 professional fields involved, although 70% of research and development staff are in engineering fields, 23% in clinical fields, and only 7% in basic science fields; significantly, 11% of the professional staff have a disability related to their research. We observe that the RERC program has substantially diversified the scope of its work since the 1970’s, addressing more types of disabilities using more technologies, and, in particular, often now focusing on information technologies. RERC work also now often views users as integrated into an interdependent society through technologies that both people with and without disabilities co-use (such as the internet, wireless communication, and architecture). In addition, RERC research has evolved to view users as able at improving outcomes through learning, exercise, and plasticity (rather than being static), which can be optimally timed. We provide examples of rehabilitation technology innovation produced by the RERCs that illustrate this increasingly diversifying scope and evolving perspective. We conclude by discussing growth opportunities and possible future directions of the RERC program

    Intranasal Delivery of Influenza Subunit Vaccine Formulated with GEM Particles as an Adjuvant

    Get PDF
    Nasal administration of influenza vaccine has the potential to facilitate influenza control and prevention. However, when administered intranasally (i.n.), commercially available inactivated vaccines only generate systemic and mucosal immune responses if strong adjuvants are used, which are often associated with safety problems. We describe the successful use of a safe adjuvant Gram-positive enhancer matrix (GEM) particles derived from the food-grade bacterium Lactococcus lactis for i.n. vaccination with subunit influenza vaccine in mice. It is shown that simple admixing of the vaccine with the GEM particles results in a strongly enhanced immune response. Already after one booster, the i.n. delivered GEM subunit vaccine resulted in hemagglutination inhibition titers in serum at a level equal to the conventional intramuscular (i.m.) route. Moreover, i.n. immunization with GEM subunit vaccine elicited superior mucosal and Th1 skewed immune responses compared to those induced by i.m. and i.n. administered subunit vaccine alone. In conclusion, GEM particles act as a potent adjuvant for i.n. influenza immunization

    Maternal health interventions in resource limited countries: a systematic review of packages, impacts and factors for change

    Get PDF
    The burden of maternal mortality in resource limited countries is still huge despite being at the top of the global public health agenda for over the last 20 years. We systematically reviewed the impacts of interventions on maternal health and factors for change in these countries. A systematic review was carried out using the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Articles published in the English language reporting on implementation of interventions, their impacts and underlying factors for maternal health in resource limited countries in the past 23 years were searched from PubMed, Popline, African Index Medicus, internet sources including reproductive health gateway and Google, hand-searching, reference lists and grey literature. Out of a total of 5084 articles resulting from the search only 58 qualified for systematic review. Programs integrating multiple interventions were more likely to have significant positive impacts on maternal outcomes. Training in emergency obstetric care (EmOC), placement of care providers, refurbishment of existing health facility infrastructure and improved supply of drugs, consumables and equipment for obstetric care were the most frequent interventions integrated in 52%-65% of all 54 reviewed programs. Statistically significant reduction of maternal mortality ratio and case fatality rate were reported in 55% and 40% of the programs respectively. Births in EmOC facilities and caesarean section rates increased significantly in 71%-75% of programs using these indicators. Insufficient implementation of evidence-based interventions in resources limited countries was closely linked to a lack of national resources, leadership skills and end-users factors. This article presents a list of evidenced-based packages of interventions for maternal health, their impacts and factors for change in resource limited countries. It indicates that no single magic bullet intervention exists for reduction of maternal mortality and that all interventional programs should be integrated in order to bring significant changes. State leaders and key actors in the health sectors in these countries and the international community are proposed to translate the lessons learnt into actions and intensify efforts in order to achieve the goals set for maternal health
    corecore