856 research outputs found

    That's Where the Money Was: Foreign Bias and English Investment Abroad, 1866-1907

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    Why did Victorian Britain invest so much capital abroad? We collect over 500,000 monthly returns of British and foreign securities trading in London and the United States between 1866 and 1907. These heretofore-unknown data allow us to better quantify the historical benefits of international diversification and revisit the question of whether British Victorian investor bias starved new domestic industries of capital. We find no evidence of bias. A British investor who increased his investment in new British industry at the expense of foreign diversification would have been worse off. The addition of foreign assets significantly expanded the mean-variance frontier and resulted in utility gains equivalent to a meaningful increase in lifetime consumption.Capital markets, Home bias, History, Victorian overseas investment

    4D offline PET-based treatment verification in ion beam therapy

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    Due to the accessible sharp dose gradients, external beam radiotherapy with protons and heavier ions enables a highly conformal adaptation of the delivered dose to arbitrarily shaped tumour volumes. However, this high conformity is accompanied by an increased sensitivity to potential uncertainties, e.g., due to changes in the patient anatomy. Additional challenges are imposed by respiratory motion which does not only lead to rapid changes of the patient anatomy, but, in the cased of actively scanned ions beams, also to the formation of dose inhomogeneities. Therefore, it is highly desirable to verify the actual application of the treatment and to detect possible deviations with respect to the planned irradiation. At present, the only clinically implemented approach for a close-in-time verification of single treatment fractions is based on detecting the distribution of β+-emitter formed in nuclear fragmentation reactions during the irradiation by means of positron emission tomography (PET). For this purpose, a commercial PET/CT (computed tomography) scanner has been installed directly next to the treatment rooms at the Heidelberg Ion-Beam Therapy Center (HIT). Up to present, the application of this treatment verification technique is, however, still limited to static target volumes. This thesis aimed at investigating the feasibility and performance of PET-based treatment verification under consideration of organ motion. In experimental irradiation studies with moving phantoms, not only the practicability of PET-based treatment monitoring for moving targets, using a commercial PET/CT device, could be shown for the first time, but also the potential of this technique to detect motion-related deviations from the planned treatment with sub-millimetre accuracy. The first application to four exemplary hepato-cellular carcinoma patient cases under substantially more challenging clinical conditions indicated potential for improvement by taking organ motion into consideration, particularly for patients exhibiting motion amplitudes of above 1cm and a sufficiently large number of detected true coincidences during their post-irradiation PET scan. Despite the application of an optimised PET image reconstruction scheme, as retrieved from a dedicated phantom imaging study in the scope of this work, the small number of counts and the resulting high level of image noise were identified as a major limiting factor for the detection of motion-induced dose inhomogeneities within the patient. Moreover, the biological washout modelling of the irradiation-induced isotopes proved to be not sufficiently accurate and thereby impede a quantitative analysis of measured and simulated data under consideration of target motion. In future, improvements are particularly foreseen through dedicated noise-robust time-resolved (4D) image reconstruction algorithms, an improved tracking of the organ motion, e.g., by ultrasound (US) imaging, as implemented for the first time in 4D PET imaging in the scope of this work, as well as by patient-specific washout models

    Image-guided adaptive photon and proton radiotherapy

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    Trade, Production Sharing and the International Transmission of Business Cycles

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    This paper is motivated by three observations about the link between international trade and international business cycle synchronization: (1) a large increase in trade in manufactures over the last 30 years, (2) a larger fraction of trade between core and periphery regions relative to core regions is in the form of production sharing, (3) crosscountry output correlations have increased between core and periphery regions relative to core regions. We examine to what extent these observations can be reconciled in a multi-country version of a standard model of international business cycles. Production sharing is captured in a simple way as trade in intermediate inputs that are complements in production. We find that the model is successful qualitatively in account for these observations. Quantitatively, we find that the direct effects from trade do not generate large divergence in output correlationsacrosscountries. Weextendthemodel to allow for cost reduction spillovers from MNEs in the core country to their affiliates in the periphery. This mechanism increases the impact that product sharing has on output correlations between core and peripheral countries.

    Pre-College Deaf Students’ Understanding of Fractional Concepts: What We Know and What We Do Not Know

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    Mathematical knowledge and skills are crucial to success in academics and the workplace. The Common Core State Standards emphasizes fraction teaching and learning in elementary school. This mixed-method study explores fraction concept understanding among 14 deaf and hard of hearing participants between the ages of 8 and 16, as quantitatively measured by their ability to describe the properties of fractional numbers, convert between fractional numbers and their visual representations, and determine the order and equivalence of fractional numbers. Furthermore, the qualitative study was supplemented by interviews with the deaf participants and surveys with their parents and teachers to examine use of mathematical fraction concepts in the student participant\u27s experience, at home and in the classroom. Results indicated a strong understanding of fractional magnitude; however, putting fractions in order from the smallest to the largest was a struggle for the participants. The findings also support the call for increased incidental learning opportunities between deaf and hard of hearing children and their parents along with increased use of practical applications of fractional numbers, and additional training for teachers who teach fractions to deaf students

    That’s Where the Money Was: Foreign Bias and English Investment Abroad, 1866-1907

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    The Importance of Early Number Concepts for Learning Mathematics in Deaf and Hard of Hearing Children

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    This chapter discusses important background knowledge and research findings from a variety of disciplines that inform best practices for supporting optimal mathematical achievement in all children. First, discussion will begin with the importance of early numeracy for later academic outcomes, and why prioritization of instruction time and early intervention are needed to increase the likelihood of a strong foundation in numeracy. Second, a brief overview of numeracy development milestones will provide a basis for discussion of our central thesis: language experiences can impact numerical cognition, which then have a significant impact on academic outcomes. Third, given the importance of numeracy skills in academic outcomes, we describe pedagogical trends that are likely to support the development of numerical cognition. This discussion will justify language remediation, increased mathematics talk, and visual-spatial representation as key goals for early intervention programs. Finally, we offer some future directions of research that will further account for underlying mechanisms of numeracy development in very young and preschool-aged children

    4D offline PET-based treatment verification in ion beam therapy

    Get PDF
    Due to the accessible sharp dose gradients, external beam radiotherapy with protons and heavier ions enables a highly conformal adaptation of the delivered dose to arbitrarily shaped tumour volumes. However, this high conformity is accompanied by an increased sensitivity to potential uncertainties, e.g., due to changes in the patient anatomy. Additional challenges are imposed by respiratory motion which does not only lead to rapid changes of the patient anatomy, but, in the cased of actively scanned ions beams, also to the formation of dose inhomogeneities. Therefore, it is highly desirable to verify the actual application of the treatment and to detect possible deviations with respect to the planned irradiation. At present, the only clinically implemented approach for a close-in-time verification of single treatment fractions is based on detecting the distribution of β+-emitter formed in nuclear fragmentation reactions during the irradiation by means of positron emission tomography (PET). For this purpose, a commercial PET/CT (computed tomography) scanner has been installed directly next to the treatment rooms at the Heidelberg Ion-Beam Therapy Center (HIT). Up to present, the application of this treatment verification technique is, however, still limited to static target volumes. This thesis aimed at investigating the feasibility and performance of PET-based treatment verification under consideration of organ motion. In experimental irradiation studies with moving phantoms, not only the practicability of PET-based treatment monitoring for moving targets, using a commercial PET/CT device, could be shown for the first time, but also the potential of this technique to detect motion-related deviations from the planned treatment with sub-millimetre accuracy. The first application to four exemplary hepato-cellular carcinoma patient cases under substantially more challenging clinical conditions indicated potential for improvement by taking organ motion into consideration, particularly for patients exhibiting motion amplitudes of above 1cm and a sufficiently large number of detected true coincidences during their post-irradiation PET scan. Despite the application of an optimised PET image reconstruction scheme, as retrieved from a dedicated phantom imaging study in the scope of this work, the small number of counts and the resulting high level of image noise were identified as a major limiting factor for the detection of motion-induced dose inhomogeneities within the patient. Moreover, the biological washout modelling of the irradiation-induced isotopes proved to be not sufficiently accurate and thereby impede a quantitative analysis of measured and simulated data under consideration of target motion. In future, improvements are particularly foreseen through dedicated noise-robust time-resolved (4D) image reconstruction algorithms, an improved tracking of the organ motion, e.g., by ultrasound (US) imaging, as implemented for the first time in 4D PET imaging in the scope of this work, as well as by patient-specific washout models

    Trade, Production Sharing, and the International Transmission of Business Cycles

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    Countries that are more engaged in production sharing exhibit higher bilateral manufacturing output correlations. We use data on trade flows between US multinationals and their affiliates as well as trade between the United States and Mexican maquiladoras to measure production-sharing trade and its link with the business cycle. We then develop a quantitative model of international business cycles that generates a positive link between the extent of vertically integrated production-sharing trade and internationally synchronized business cycles. A key assumption in the model is a relatively low elasticity of substitution between home and foreign inputs in the production of the vertically integrated good.

    Using Information Communications Technologies to Implement Universal Design for Learning

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    The purpose of this paper is to assist Ministries of Education, their donors and partners, Disabled Persons Organizations (DPOs), and the practitioner community funded by and working with USAID to select, pilot, and (as appropriate) scale up ICT4E solutions to facilitate the implementation of Universal Design for Learning (UDL), with a particular emphasis on supporting students with disabilities to acquire literacy and numeracy skills. The paper focuses primarily on how technology can support foundational skills acquisition for students with disabilities, while also explaining when, why, and how technologies that assist students with disabilities can, in some applications, have positive impacts on all students’ basic skills development. In 2018, USAID released the Toolkit for Universal Design for Learning to Help All Children Read, section 3.1 of which provides basic information on the role of technologies to support UDL principles and classroom learning. This paper expands upon that work and offers more extensive advice on using ICT4E1 to advance equitable access to high quality learning. Like the UDL toolkit, the audience for this guide is mainly Ministries of Education and development agencies working in the area of education, but this resource can also be helpful for DPOs and non-governmental organizations (NGOs) wishing to pilot or spearhead ICT initiatives. Content for this paper was informed by expert interviews and reviews of field reports during 2018. These included programs associated with United Nations, Zero Project, World Innovation Summit, UNESCO Mobile Learning Awards, and USAID’s All Children Reading: A Grand Challenge for Development. Relevant case studies of select education programs integrating technology to improve learning outcomes for students with disabilities were summarized for this document
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