538 research outputs found

    High efficiency infrared generation by difference-frequency mixing using tangential phase matching

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    Measurements have been made of the energy generated in the wavelength region 3.3 to 4.0 ”m, by difference-frequency mixing between a tunable dye laser and a Nd:YAG laser in lithium niobate. The highest mixing efficiencies have been observed with the beams aligned in a non-collinear geometry. It is demonstrated that this non-collinear geometry corresponds to the tangential phase-matching condition which increases the acceptance angle of a second-order nonlinear interaction over that achieved in a non-critically phase-matched geometry

    Factors of resilience in informal caregivers of people with dementia from integrative international data analysis

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    Background/Aims: Although caring for a person with dementia can be stressful, some caregivers appear to experience few negative consequences to their well-being. This study aimed to examine what proportion of caregivers demonstrates resilience under different challenging circumstances and to identify factors related to their resilience. Methods: Baseline data from 4 studies from the Netherlands and UK among informal caregivers of people with dementia were harmonized and integrated. Caregiver resilience was defined as high levels of psychological well-being despite different types of high caregiving demands. Multivariate regression analyses identified factors significantly related to caregiver resilience. Results: The integrated data set included 15 harmonized variables with data from 1,048 caregivers facing a high care demand. The prevalence of resilience varied between 35 and 43%, depending on the demand for high care. Being a male caregiver, caring for a female, living apart from your relative, and low caregiver burden were positively related to caregiver resilience. Conclusion: Caregivers have the capacity to demonstrate resilience despite significant challenges. This study demonstrates how harmonization of data from multiple existing studies can be used to increase power and explore the consistency of findings. This contributes to a better understanding of which factors are likely to facilitate caregiver resilience and offers insights for developing services

    Leaving the nest: the rise of regional financial arrangements and the future of global governance

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    This article examines the impact of regional financial arrangements (RFAs) on the global liquidity regime. It argues that the design of RFAs could potentially alter the global regime, whether by strengthening it and making it more coherent or by decentring the International Monetary Fund (IMF) and destabilizing it. To determine possible outcomes, this analysis deploys a ‘middle‐up’ approach that focuses on the institutional design of these RFAs. It first draws on the rational design of institutions framework to identify the internal characteristics of RFAs that are most relevant to their capabilities and capacities. It then applies these insights to the interactions of RFAs with the IMF, building on Aggarwal's (1998) concept of ‘nested’ versus ‘parallel’ institutions, to create an analytical lens through which to assess the nature and sustainability of nested linkages. Through an analysis of the Chiang Mai Initiative Multilateralization (CMIM) and the Latin American Reserve Fund (FLAR), the article demonstrates the usefulness of this lens. It concludes by considering three circumstances in which fault lines created by these RFAs’ institutional design could be activated, permitting an institution to ‘leave the nest’, including changing intentions of principals, creation of parallel capabilities and facilities, and failure of the global regime to address regional needs in a crisis.The authors would like to thank Veronica Artola, Masatsugu Asakawa, Ana Maria Carrasquilla, Junhong Chang, Paolo Hernando, Hoe Ee Khor, Kazunori Koike, Jae Young Lee, Ser-Jin Lee, Guillermo Perry, Yoichi Nemoto, Freddy Trujillo, Masaaki Watanabe, Yasuto Watanabe, Akihiko Yoshida, and others who wished to remain anonymous, for their generosity in providing in-person interviews. Further, the authors would like to thank various central bank and ministry of finance officials of both FLAR and CMIM member countries. We also thank Jose Antonio Ocampo, Diana Barrowclough, and participants in the 'Beyond Bretton Woods' Workshop at Boston University (where an earlier version of this article was presented in September 2017) for their feedback on our broader research projects on RFAs. Last but not least, the authors wish to thank the anonymous referees for their constructive comments. This work builds upon previous work funded by UNCTAD and the Global Economic Governance Initiative at the Global Development Policy Center at Boston University. (UNCTAD; Global Economic Governance Initiative at the Global Development Policy Center at Boston University)Accepted manuscrip

    Decay of the key 92-keV resonance in the 25Mg(p,Îł) reaction to the ground and isomeric states of the cosmic Îł-ray emitter 26Al

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    The 92-keV resonance in the 25Mg(p,γ)26Al reaction plays a key role in the production of 26Al at astrophysical burning temperatures of ≈100 MK in the Mg-Al cycle. However, the state can decay to feed either the ground, 26gAl, or isomeric state, 26mAl. It is the ground state that is critical as the source of cosmic γ rays. It is therefore important to precisely determine the ground-state branching fraction f0 of this resonance. Here we report on the identification of four γ-ray transitions from the 92-keV resonance, and determine the spin of the state and its ground-state branching fraction f0=0.52(2)stat(6)syst. The f0 value is the most precise reported to date, and at the lower end of the range of previously adopted values, implying a lower production rate of 26gAl and its cosmic 1809-keV γ rays.peerReviewe

    From bound states to resonances: analytic continuation of the wave function

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    Single-particle resonance parameters and wave functions in spherical and deformed nuclei are determined through analytic continuation in the potential strength. In this method, the analyticity of the eigenvalues and eigenfunctions of the Schroedinger equation with respect to the coupling strength is exploited to analytically continue the bound-state solutions into the positive-energy region by means of Pade' approximants of the second kind. The method is here applied to single-particle wave functions of the 154Sm^{154}Sm and 131Eu^{131}Eu nuclei. A comparison of the results with the direct solution of the Schroedinger equation shows that the method can be confidently applied also in coupled-channel situations requiring high numerical accuracy.Comment: 13 pages, 3 figure

    Identification of key astrophysical resonances relevant for the Al26g(p,Îł)Si27 reaction in Wolf-Rayet stars, AGB stars, and classical novae

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    A Îł-ray spectroscopy study of Al26g+p resonant states in Si27 is presented. Excitation energies were measured with improved precision and first spin-parity assignments made for excited states in Si27 above the proton threshold. The results indicate the presence of low-lying resonances with lp=0 and lp=2 captures that could strongly influence the Al26g(p,Îł)Si27 reaction rate at low stellar temperatures, found in low-mass asymptotic giant branch (AGB), intermediate-mass AGB, super AGB, and Wolf-Rayet stars

    Long range absorption in the scattering of 6He on 208Pb and 197Au at 27 MeV

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    Quasi-elastic scattering of 6He at E_lab=27 MeV from 197Au has been measured in the angular range of 6-72 degrees in the laboratory system employing LEDA and LAMP detection systems. These data, along with previously analysed data of 6He + 208Pb at the same energy, are analyzed using Optical Model calculations. The role of Coulomb dipole polarizability has been investigated. Large imaginary diffuseness parameters are required to fit the data. This result is an evidence for long range absorption mechanisms in 6He induced reactions.Comment: 10 pages, 10 figures, minor corrections. To appear in Nucl. Phys.

    Identification of analog states in the T=1/2 A=27 mirror system from low excitation energies to the region of hydrogen burning in the 26Alg ,m(p,Îł)27Si reactions

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    The reactions 26Alg(p,Îł)27Si and 26Alm(p,Îł)27Si are important for influencing the galactic abundance of the cosmic Îł-ray emitter 26Alg and for the excess abundance of 26Mg found in presolar grains, respectively. Precise excitation energies and spin assignments of states from the ground state to the region of astrophysical interest in 27Si, including the identification and pairing of key astrophysical resonances with analog states in the mirror nucleus 27Al, are reported using Îł rays observed in the 12C + 16O fusion reaction. The detailed evolution of Coulomb energy differences between the states in 27Si and 27Al is explored, including the region above the astrophysical reaction thresholds