4,720 research outputs found
The Economics of Healthcare Rationing
This article examines the economics of healthcare rationing. We begin with an overview of the various dimensions across which healthcare rationing operates, or at least has the potential to operate, in the first place. We then describe the types of economic analyses used in healthcare rationing decision-making, with particular reference to cost-benefit analysis and cost-effectiveness analysis. We also discuss healthcare rationing in practice, such as how economic analyses inform decisions regarding which services to cover, and conclude by discussing various practical and conceptual challenges that may arise with economic analyses and that span both economics and ethics
Transient dynamics of a superconducting nonlinear oscillator
We investigate the transient dynamics of a lumped-element oscillator based on
a dc superconducting quantum interference device (SQUID). The SQUID is shunted
with a capacitor forming a nonlinear oscillator with resonance frequency in the
range of several GHz. The resonance frequency is varied by tuning the Josephson
inductance of the SQUID with on-chip flux lines. We report measurements of
decaying oscillations in the time domain following a brief excitation with a
microwave pulse. The nonlinearity of the SQUID oscillator is probed by
observing the ringdown response for different excitation amplitudes while the
SQUID potential is varied by adjusting the flux bias. Simulations are performed
on a model circuit by numerically solving the corresponding Langevin equations
incorporating the SQUID potential at the experimental temperature and using
parameters obtained from separate measurements characterizing the SQUID
oscillator. Simulations are in good agreement with the experimental
observations of the ringdowns as a function of applied magnetic flux and pulse
amplitude. We observe a crossover between the occurrence of ringdowns close to
resonance and adiabatic following at larger detuning from the resonance. We
also discuss the occurrence of phase jumps at large amplitude drive. Finally,
we briefly outline prospects for a readout scheme for superconducting flux
qubits based on the discrimination between ringdown signals for different
levels of magnetic flux coupled to the SQUID.Comment: 15 pages, 9 figure
Area laws in quantum systems: mutual information and correlations
The holographic principle states that on a fundamental level the information
content of a region should depend on its surface area rather than on its
volume. This counterintuitive idea which has its roots in the nonextensive
nature of black-hole entropy serves as a guiding principle in the search for
the fundamental laws of Planck-scale physics. In this paper we show that a
similar phenomenon emerges from the established laws of classical and quantum
physics: the information contained in part of a system in thermal equilibrium
obeys an area law. While the maximal information per unit area depends
classically only on the number of microscopic degrees of freedom, it may
diverge as the inverse temperature in quantum systems. A rigorous relation
between area laws and correlations is established and their explicit behavior
is revealed for a large class of quantum many-body states beyond equilibrium
systems.Comment: 5 pages, 2 figures, published version with appendi
The HI gas content of galaxies around Abell 370, a galaxy cluster at z = 0.37
We used observations from the Giant Metrewave Radio Telescope to measure the
atomic hydrogen gas content of 324 galaxies around the galaxy cluster Abell 370
at a redshift of z = 0.37 (a look-back time of ~4 billion years). The HI 21-cm
emission from these galaxies was measured by coadding their signals using
precise optical redshifts obtained with the Anglo-Australian Telescope. The
average HI mass measured for all 324 galaxies is (6.6 +- 3.5)x10^9 solar
masses, while the average HI mass measured for the 105 optically blue galaxies
is (19.0 +- 6.5)x10^9 solar masses. The significant quantities of gas found
around Abell 370, suggest that there has been substantial evolution in the gas
content of galaxy clusters since redshift z = 0.37. The total amount of HI gas
found around Abell 370 is up to ~8 times more than that seen around the Coma
cluster, a nearby galaxy cluster of similar size. Despite this higher gas
content, Abell 370 shows the same trend as nearby clusters, that galaxies close
to the cluster core have lower HI gas content than galaxies further away. The
Abell 370 galaxies have HI mass to optical light ratios similar to local galaxy
samples and have the same correlation between their star formation rate and HI
mass as found in nearby galaxies. The average star formation rate derived from
[OII] emission and from de-redshifted 1.4 GHz radio continuum for the Abell 370
galaxies also follows the correlation found in the local universe. The large
amounts of HI gas found around the cluster can easily be consumed by the
observed star formation rate in the galaxies over the ~4 billion years (from z
= 0.37) to the present day.Comment: accepted by MNRA
Solution structure of a bacterial microcompartment targeting peptide and its application in the construction of an ethanol bioreactor
Targeting of proteins to bacterial microcompartments (BMCs) is mediated by an 18-amino-acid peptide sequence. Herein, we report the solution structure of the N-terminal targeting peptide (P18) of PduP, the aldehyde dehydrogenase associated with the 1,2-propanediol utilization metabolosome from Citrobacter freundii. The solution structure reveals the peptide to have a well-defined helical conformation along its whole length. Saturation transfer difference and transferred NOE NMR has highlighted the observed interaction surface on the peptide with its main interacting shell protein, PduK. By tagging both a pyruvate decarboxylase and an alcohol dehydrogenase with targeting peptides, it has been possible to direct these enzymes to empty BMCs in vivo and to generate an ethanol bioreactor. Not only are the purified, redesigned BMCs able to transform pyruvate into ethanol efficiently, but the strains containing the modified BMCs produce elevated levels of alcohol
Perturbed disks get shocked. Binary black hole merger effects on accretion disks
The merger process of a binary black hole system can have a strong impact on
a circumbinary disk. In the present work we study the effect of both central
mass reduction (due to the energy loss through gravitational waves) and a
possible black hole recoil (due to asymmetric emission of gravitational
radiation). For the mass reduction case and recoil directed along the disk's
angular momentum, oscillations are induced in the disk which then modulate the
internal energy and bremsstrahlung luminosities. On the other hand, when the
recoil direction has a component orthogonal to the disk's angular momentum, the
disk's dynamics are strongly impacted, giving rise to relativistic shocks. The
shock heating leaves its signature in our proxies for radiation, the total
internal energy and bremsstrahlung luminosity. Interestingly, for cases where
the kick velocity is below the smallest orbital velocity in the disk (a likely
scenario in real AGN), we observe a common, characteristic pattern in the
internal energy of the disk. Variations in kick velocity simply provide a phase
offset in the characteristic pattern implying that observations of such a
signature could yield a measure of the kick velocity through electromagnetic
signals alone.Comment: 10 pages, 13 figures. v2: Minor changes, version to be published in
PR
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