7,931 research outputs found

    Evolution of magnetic polarons and spin-carrier interactions through the metal-insulator transition in Eu1āˆ’x_{1-x}Gdx_{x}O

    Full text link
    Raman scattering studies as functions of temperature, magnetic field, and Gd-substitution are used to investigate the evolution of magnetic polarons and spin-carrier interactions through the metal-insulator transition in Eu1āˆ’x_{1-x}Gdx_{x}O. These studies reveal a greater richness of phase behavior than have been previously observed using transport measurements: a spin-fluctuation-dominated paramagnetic (PM) phase regime for T >> Tāˆ—^{*} >> TC_{C}, a two-phase regime for T << Tāˆ—^{*} in which magnetic polarons develop and coexist with a remnant of the PM phase, and an inhomogeneous ferromagnetic phase regime for T << TC_{C}

    An Experimental Study of Effects of Step Roughness in Skimming Flows on Stepped Chutes

    Get PDF
    On a spillway chute, a stepped design increases the rate of energy dissipation on the chute itself and reduces the size of a downstream energy dissipator. Up to date, the effects of step roughness on the flow properties remain unknown despite the practical relevance to damaged concrete steps, rock chutes and gabions weirs. New measurements were conducted in a large-size laboratory facility with two step conditions (smooth and rough) and three types of step roughness. Detailed air-water flow properties were measured systematically for several flow rates. The results showed faster flow motion on rough step chutes. Although the finding is counter-intuitive, it is linked with the location of the inception point of free-surface aeration being located further downstream than for a smooth stepped chute for an identical flow rate. In the aerated flow region, the velocities on rough-step chutes were larger than those of smooth chute flows for a given flow rate and dimensionless location from the inception point of free-surface aeration both at step edges and between step edges. The results suggest that design guidelines for smooth (concrete) stepped spillway may not be suitable to rough stepped chutes including gabion stepped weirs, and older stepped chutes with damaged steps

    How to teach fully illiterate adults to read.

    Get PDF
    About 750 million adults (15%) worldwide lack any literacy skills, most because they lack adequate learning opportunities (UNESCO, 2016). In this chapter, we discuss how to teach to read to such people. We first examine scientific evidence suggesting that literacy acquisition does not radically differ as a function of age of acquisition. We then discuss the data relevant for designing effective methods aimed at teaching literacy to fully illiterate adults. We argue that the available adult data confirm those relative to teaching methods and learning processes that have been gathered on literacy acquisition by children. On the basis of those works we propose principles that should underlie any method aiming at rapidly developing basic literacy skills. Lastly, we present evidence (Kolinsky, Leite, Carvalho, Franco, & Morais, submitted) suggesting that implementing these principles does indeed allow teaching illiterate adults to decode words and pseudo-words in a very short period of time

    Fluctuation induced hopping and spin polaron transport

    Full text link
    We study the motion of free magnetic polarons in a paramagnetic background of fluctuating local moments. The polaron can tunnel only to nearby regions of local moments when these fluctuate into alignment. We propose this fluctuation induced hopping as a new transport mechanism for the spin polaron. We calculate the diffusion constant for fluctuation induced hopping from the rate at which local moments fluctuate into alignment. The electrical resistivity is then obtained via the Einstein relation. We suggest that the proposed transport mechanism is relevant in the high temperature phase of the Mn pyrochlore colossal magneto resistance compounds and Europium hexaboride.Comment: 8 pages, 3 figure

    Health-related quality of life in Huntingtonā€™s Disease patients: a comparison of proxy assessment and patient self-rating using the disease-specific Huntingtonā€™s Disease health-related quality of life questionnaire (HDQoL)

    Get PDF
    Huntingtonā€™s disease (HD) is a fatal, neurodegenerative disease for which there is no known cure. Proxy evaluation is relevant for HD as its manifestation might limit the ability of persons to report their health-related quality of life (HrQoL). This study explored patientā€“proxy ratings of HrQoL of persons at different stages of HD, and examined factors that may affect proxy ratings. A total of 105 patientā€“proxy pairs completed the Huntingtonā€™s disease health-related quality of life questionnaire (HDQoL) and other established HrQoL measures (EQ-5D and SF-12v2). Proxyā€“patient agreement was assessed in terms of absolute level (mean ratings) and intraclass correlation. Proxiesā€™ ratings were at a similar level to patientsā€™ self-ratings on an overall Summary Score and on most of the six Specific Scales of the HDQoL. On the Specific Hopes and Worries Scale, proxies on average rated HrQoL as better than patientsā€™ self-ratings, while on both the Specific Cognitive Scale and Specific Physical and Functional Scale proxies tended to rate HrQoL more poorly than patients themselves. The patientā€™s disease stage and mental wellbeing (SF-12 Mental Component scale) were the two factors that primarily affected proxy assessment. Proxy scores were strongly correlated with patientsā€™ self-ratings of HrQoL, on the Summary Scale and all Specific Scales. The patientā€“proxy correlation was lower for patients at moderate stages of HD compared to patients at early and advanced stages. The proxy report version of the HDQoL is a useful complementary tool to self-assessment, and a promising alternative when individual patients with advanced HD are unable to self-report

    The urban wage growth premium: sorting or learning?

    Get PDF
    This paper is concerned with the urban wage premium and addresses two central issues about which the field has not yet reached a consensus: first, the extent to which sorting of high ability individuals into urban areas explains the urban wage premium and second, whether workers receive this wage premium immediately, or through faster wage growth over time. Using a large panel of worker-level data from Britain, we first demonstrate the existence of an urban premium for wage levels, which increases in city size. We next provide evidence of a city size premium on wage growth, but show that this effect is driven purely by the increase in wage that occurs in the first year that a worker moves to a larger location. Controlling for sorting on the basis of unobservables we find no evidence of an urban wage growth premium. Experience in cities does have some impact on wage growth, however. Specifically, we show that workers who have at some point worked in a city experience faster wage growth than those who have never worked in a city
    • ā€¦
    corecore