498 resultados para Feldstein-Horioka Puzzle.


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Mode of access: Internet.

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Early childhood research beginning in the 1960s has focused on the literacy experiences of preschool children in the home and the contribution of those experiences to later school success. Decades of research since then have investigated learning experiences of preschool children as they interacted with caregivers, siblings or peers prior to formal schooling (Durkin, 1966; Heath, 1983). ^ In this qualitative investigation into early literacy events that occur between disadvantaged Irish mothers and their children, four research questions were investigated. (1) How do disadvantaged Irish mothers engage their preschool children in literacy events such as storybook reading and jigsaw puzzle building? (2) How does the mother's previous school experience affect her role as the child's first teacher? (3) How does the culture of the neighborhood affect the child's developing literacy? (4) What risk factors inhibit literacy development in these Irish children? ^ This study examined the conversational exchanges between three disadvantaged Irish mothers and their preschool children living near Dublin, Ireland, as the mothers read a storybook to their children and assisted them in jigsaw puzzle building. Conversations were recorded, transcribed and analyzed into reading skill and teaching strategy categories for the purpose of determining the mothers' literacy intent during her turn. Journal notes, field notes and interviews with the mothers recorded other information and allowed for triangulation of data. ^ The results of this investigation indicated four findings. The first finding was that these disadvantaged mothers employed many of the same techniques that classroom teachers use during the reading lesson. They attempted high-level and low-level questions, teaching strategies, and other interactions that are so familiar in the classroom. The second finding was that jigsaw puzzle building produced a richer literacy interaction than storybook reading. The third finding was that the environment of the disadvantaged neighborhood posed many risks to children's literacy development. A final finding was that the mothers used thinking out loud behavior to vocalize their inner thoughts during literacy interactions. ^ Future research suggests studying mother/child dyads in other socio-economic environments and cultures to determine if other mothers practice the same skills and strategies as these mothers. ^

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The electromagnetic form factors are the most fundamental observables that encode information about the internal structure of the nucleon. The electric (GE) and the magnetic ( GM) form factors contain information about the spatial distribution of the charge and magnetization inside the nucleon. A significant discrepancy exists between the Rosenbluth and the polarization transfer measurements of the electromagnetic form factors of the proton. One possible explanation for the discrepancy is the contributions of two-photon exchange (TPE) effects. Theoretical calculations estimating the magnitude of the TPE effect are highly model dependent, and limited experimental evidence for such effects exists. Experimentally, the TPE effect can be measured by comparing the ratio of positron-proton elastic scattering cross section to that of the electron-proton [R = σ(e +p)/σ(e+p)]. The ratio R was measured over a wide range of kinematics, utilizing a 5.6 GeV primary electron beam produced by the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. This dissertation explored dependence of R on kinematic variables such as squared four-momentum transfer (Q2) and the virtual photon polarization parameter (&epsis;). A mixed electron-positron beam was produced from the primary electron beam in experimental Hall B. The mixed beam was scattered from a liquid hydrogen (LH2) target. Both the scattered lepton and the recoil proton were detected by the CEBAF Large Acceptance Spectrometer (CLAS). The elastic events were then identified by using elastic scattering kinematics. This work extracted the Q2 dependence of R at high &epsis;(&epsis; > 0.8) and the $&epsis; dependence of R at ⟨Q 2⟩ approx 0.85 GeV2. In these kinematics, our data confirm the validity of the hadronic calculations of the TPE effect by Blunden, Melnitchouk, and Tjon. This hadronic TPE effect, with additional corrections contributed by higher excitations of the intermediate state nucleon, largely reconciles the Rosenbluth and the polarization transfer measurements of the electromagnetic form factors.

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Attention-deficit hyperactivity disorder (ADHD) is the most prevalent and impairing neurodevelopmental disorder, with worldwide estimates of 5.29%. ADHD is clinically characterized by hyperactivity-impulsivity and inattention, with neuropsychological deficits in executive functions, attention, working memory and inhibition. These cognitive processes rely on prefrontal cortex function; cognitive training programs enhance performance of ADHD participants supporting the idea of neuronal plasticity. Here we propose the development of an on-line puzzle game based assessment and training tool in which participants must deduce the ‘winning symbol’ out of N distracters. To increase ecological validity of assessments strategically triggered Twitter/Facebook notifications will challenge the ability to ignore distracters. In the UK, significant cost for the disorder on health, social and education services, stand at £23m a year. Thus the potential impact of neuropsychological assessment and training to improve our understanding of the pathophysiology of ADHD, and hence our treatment interventions and patient outcomes, cannot be overstated.

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Máster Universitario en Ingeniería Informática (Escuela Universitaria de Informática)

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Splenic rupture is a common complaint encountered in emergency surgery. Trauma is the most common cause of splenic rupture, while non-traumatic or occult splenic rupture (OSR) is a rare condition. The differential diagnosis weighs on treatment that ranges between close monitoring, splenorrhaphy, splenic conservation and splenectomy. We report a case of an 63-year-old man presenting with acute atraumatic left upper quadrant pain. Preliminary diagnosis was subsequently determined to be a hematoma secondary to OSR. More accurate detailed history revealed a previous trauma, which occurred more than one year before and mimicked an OSR. Delayed and occult splenic rupture are as different diagnosis as different treatment. Even in emergency surgery, the key for a target therapeutic strategy should consider an accurate diagnostic time.

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O presente estudo tem por objetivo estimar a relação entre poupança e investimento no curto prazo. Os dados utilizados ficam restritos ao Brasil, no período que varia entre 1996 e 2013. A fim de satisfazer tal finalidade, será estimado um modelo vetor autorregressivo, com base na literatura empírica do modelo Feldstein e Horioka. O resultado obtido indica uma grande mobilidade de capitais para Brasil, em conformidade a não existência de uma relação de precedência temporal (Causalidade de Granger) para as variáveis. Por meio da decomposição da variância é possível inferir também que as variáveis são responsáveis pelas suas próprias variações ao longo do tempo. Ainda, as conclusões obtidas refutam a validade do Enigma Feldstin e Horioka, de que países industrializados teriam uma pequena mobilidade de capitais.

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The electromagnetic form factors are the most fundamental observables that encode information about the internal structure of the nucleon. The electric ($G_{E}$) and the magnetic ($G_{M}$) form factors contain information about the spatial distribution of the charge and magnetization inside the nucleon. A significant discrepancy exists between the Rosenbluth and the polarization transfer measurements of the electromagnetic form factors of the proton. One possible explanation for the discrepancy is the contributions of two-photon exchange (TPE) effects. Theoretical calculations estimating the magnitude of the TPE effect are highly model dependent, and limited experimental evidence for such effects exists. Experimentally, the TPE effect can be measured by comparing the ratio of positron-proton elastic scattering cross section to that of the electron-proton $\large(R = \frac{\sigma (e^{+}p)}{\sigma (e^{-}p)}\large)$. The ratio $R$ was measured over a wide range of kinematics, utilizing a 5.6 GeV primary electron beam produced by the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. This dissertation explored dependence of $R$ on kinematic variables such as squared four-momentum transfer ($Q^{2}$) and the virtual photon polarization parameter ($\varepsilon$). A mixed electron-positron beam was produced from the primary electron beam in experimental Hall B. The mixed beam was scattered from a liquid hydrogen (LH$_{2}$) target. Both the scattered lepton and the recoil proton were detected by the CEBAF Large Acceptance Spectrometer (CLAS). The elastic events were then identified by using elastic scattering kinematics. This work extracted the $Q^{2}$ dependence of $R$ at high $\varepsilon$ ($\varepsilon > $ 0.8) and the $\varepsilon$ dependence of $R$ at $\langle Q^{2} \rangle \approx 0.85$ GeV$^{2}$. In these kinematics, our data confirm the validity of the hadronic calculations of the TPE effect by Blunden, Melnitchouk, and Tjon. This hadronic TPE effect, with additional corrections contributed by higher excitations of the intermediate state nucleon, largely reconciles the Rosenbluth and the polarization transfer measurements of the electromagnetic form factors.

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The pace at which challenges are introduced in a game has long been identified as a key determinant of both the enjoyment and difficulty experienced by game players, and their ability to learn from game play. In order to understand how to best pace challenges in games, there is great value in analysing games already demonstrated as highly engaging. Play-through videos of four puzzle games (Portal, Portal 2 Co-operative mode, Braid and Lemmings), were observed and analysed using metrics derived from a behavioural psychology understanding of how people solve problems. Findings suggest that; 1) the main skills learned in each game are introduced separately, 2) through simple puzzles that require only basic performance of that skill, 3) the player has the opportunity to practice and integrate that skill with previously learned skills, and 4) puzzles increase in complexity until the next new skill is introduced. These data provide practical guidance for designers, support contemporary thinking on the design of learning structures in games, and suggest future directions for empirical research.

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This study develops a life-cycle model where investors make investment decisions in a realistic environment. Model results show that personal illiquid projects (housing and children), fixed costs (once-off/per-period participation costs plus variable/fixed transaction costs) and endogenous risky human capital (with permanent, transitory and disastrous shocks) together are able to address both the non-participation puzzle and the age-effects puzzle. Empirical implications of the model are examined using Heckman’s two-step method with the latest five Surveys of Consumer Finance (SCF). Regression results show that liquidity, informational cost and human capital are indeed the major determinants of participation and asset allocation decisions at different stages of an investor’s life.