70 research outputs found
Shift work and use of psychotropic medicine:A follow-up study with register linkage
OBJECTIVE: This study aimed to investigate a prospective association between shift work and use of psychotropic medicine. METHODS: Survey data from random samples of the general working population of Denmark (N=19 259) were linked to data from national registers. Poisson regression was used for analyses of prospective associations between shift work and redeemed prescriptions of psychotropic medicine. Prevalent cases were excluded at baseline. In secondary analyses, we tested differential effects on subsets of psychotropic medicine and, cross-sectionally, we studied correspondence between estimates based on psychotropic medicine and self-reported mental health. According to the protocol we interpret results from the secondary analyses following the principles for nested hypothesis testing, if the primary analyses reject the null-hypothesis, and otherwise we regard it as hypothesis generating exploratory analyses. RESULTS: In the primary analysis, the rate ratio for incidence of psychotropic medicine among shift workers was 1.09 (95% confidence interval 0.99–1.21). Results from the secondary analyses suggested increased incidence of use of hypnotics, sedatives and antidepressants and decreased incidence of use of anxiolytics. Cross-sectional analysis suggested increased risk for use of psychotropic medicine (all kinds), but not for poor self-rated mental health. CONCLUSIONS: Results did not support that working in shifts to the extent that is currently practiced in Denmark is associated with an increased incidence of overall psychotropic medicine use. Future studies should test, whether there is a differential incidence for different drugs among shift workers as suggested by the secondary analyses and how psychotropic medicine use and mental health are related
Determining eigenstates and thermal states on a quantum computer using quantum imaginary time evolution
The accurate computation of Hamiltonian ground, excited and thermal states on quantum computers stands to impact many problems in the physical and computer sciences, from quantum simulation to machine learning. Given the challenges posed in constructing large-scale quantum computers, these tasks should be carried out in a resource-efficient way. In this regard, existing techniques based on phase estimation or variational algorithms display potential disadvantages; phase estimation requires deep circuits with ancillae, that are hard to execute reliably without error correction, while variational algorithms, while flexible with respect to circuit depth, entail additional high-dimensional classical optimization. Here, we introduce the quantum imaginary time evolution and quantum Lanczos algorithms, which are analogues of classical algorithms for finding ground and excited states. Compared with their classical counterparts, they require exponentially less space and time per iteration, and can be implemented without deep circuits and ancillae, or high-dimensional optimization. We furthermore discuss quantum imaginary time evolution as a subroutine to generate Gibbs averages through an analogue of minimally entangled typical thermal states. Finally, we demonstrate the potential of these algorithms via an implementation using exact classical emulation as well as through prototype circuits on the Rigetti quantum virtual machine and Aspen-1 quantum processing unit
Determining eigenstates and thermal states on a quantum computer using quantum imaginary time evolution
The accurate computation of Hamiltonian ground, excited, and thermal states
on quantum computers stands to impact many problems in the physical and
computer sciences, from quantum simulation to machine learning. Given the
challenges posed in constructing large-scale quantum computers, these tasks
should be carried out in a resource-efficient way. In this regard, existing
techniques based on phase estimation or variational algorithms display
potential disadvantages; phase estimation requires deep circuits with ancillae,
that are hard to execute reliably without error correction, while variational
algorithms, while flexible with respect to circuit depth, entail additional
high-dimensional classical optimization. Here, we introduce the quantum
imaginary time evolution and quantum Lanczos algorithms, which are analogues of
classical algorithms for finding ground and excited states. Compared to their
classical counterparts, they require exponentially less space and time per
iteration, and can be implemented without deep circuits and ancillae, or
high-dimensional optimization. We furthermore discuss quantum imaginary time
evolution as a subroutine to generate Gibbs averages through an analog of
minimally entangled typical thermal states. Finally, we demonstrate the
potential of these algorithms via an implementation using exact classical
emulation as well as through prototype circuits on the Rigetti quantum virtual
machine and Aspen-1 quantum processing unit.Comment: 18 pages, 7 figures; improved figures and tex
Modes of Foreign Entry under Asymmetric Information about Potential Technology Spillovers
This paper studies the effect of technology spillovers on the entry decision of a multinational enterprise into a foreign market. Two alternative entry modes for a foreign direct investment are considered: Greenfield investment versus acquisition. We find that with quantity competition a spillover makes acquisitions less attractive, while with price competition acquisitions become more attractive. Asymmetric information about potential spillovers always reduces the number of
acquisitions independently of whether the host country or the entrant has private information. Interestingly, we find that asymmetric information always hurts the entrant, while it sometimes is in favor of the host country
Correct quantum chemistry in a minimal basis from effective Hamiltonians
We describe how to create ab-initio effective Hamiltonians that qualitatively
describe correct chemistry even when used with a minimal basis. The
Hamiltonians are obtained by folding correlation down from a large parent basis
into a small, or minimal, target basis, using the machinery of canonical
transformations. We demonstrate the quality of these effective Hamiltonians to
correctly capture a wide range of excited states in water, nitrogen, and
ethylene, and to describe ground and excited state bond-breaking in nitrogen
and the chromium dimer, all in small or minimal basis sets
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