406 research outputs found
Acupuncture fails to reduce but increases anaesthetic gas required to prevent movement in response to surgical incision.
Background: Acupuncture is used for clinical pain relief but has not been evaluated under clinical anaesthesia. This study was designed to compare movement in response to surgical incision in anaesthetized patients subjected to electro-acupuncture (EA) or sham procedures. Our hypothesis was that EA stimulation would reduce the requirements for anaesthetic gas. Methods: Forty-six healthy women, scheduled for laparoscopic sterilization at a Swedish county hospital, were randomized to have either the electro-acupuncture (n = 23) or sham (n = 23) procedure between the induction of general anaesthesia and the start of surgery. The minimal alveolar concentration (MAC) of sevoflurane required to prevent neck or major limb movements in response to surgical incision was determined in each group of patients. Results: The MAC for sevoflurane was found to be higher in the group given acupuncture than in the control group (2.1 ± 0.3% vs. 1.8 ± 0.4%; P = 0.008). Conclusion: Electro-acupuncture given during general anaesthesia with sevoflurane failed to reduce but instead increased the clinical need for anaesthetic gas, possibly by reducing the anaesthetic effect of sevoflurane and/or by facilitating nociceptive transmission and/or reflex activity
Sufficient conditions for the anti-Zeno effect
The ideal anti-Zeno effect means that a perpetual observation leads to an
immediate disappearance of the unstable system. We present a straightforward
way to derive sufficient conditions under which such a situation occurs
expressed in terms of the decaying states and spectral properties of the
Hamiltonian. They show, in particular, that the gap between Zeno and anti-Zeno
effects is in fact very narrow.Comment: LatEx2e, 9 pages; a revised text, to appear in J. Phys. A: Math. Ge
Purification through Zeno-like Measurements
A series of frequent measurements on a quantum system (Zeno-like
measurements) is shown to result in the ``purification'' of another quantum
system in interaction with the former. Even though the measurements are
performed on the former system, their effect drives the latter into a pure
state, irrespectively of its initial (mixed) state, provided certain conditions
are satisfied.Comment: REVTeX4, 4 pages, 1 figure; to be published in Phys. Rev. Lett.
(2003
Survival law in a potential model
The radial equation of a simple potential model has long been known to yield
an exponential decay law in lowest order (Breit-Wigner) approximation. We
demonstrate that if the calculation is extended to fourth order the decay law
exhibits the quantum Zeno effect. This model has further been studied
numerically to characterize the extra exponential time parameter which
compliments the lifetime. We also investigate the inverse Zeno effect.Comment: 16 pages, 2 tables, 3 figures, AMS-Te
The decay law can have an irregular character
Within a well-known decay model describing a particle confined initially
within a spherical potential shell, we consider the situation when the
undecayed state has an unusual energy distribution decaying slowly as
; the simplest example corresponds to a wave function constant
within the shell. We show that the non-decay probability as a function of time
behaves then in a highly irregular, most likely fractal way.Comment: 4 pages, 3 eps figure
Certificates of Confidentiality: Protecting Human Subject Research Data in Law and Practice
The federal Certificate of Confidentiality plays an important role in research on sensitive topics by authorizing researchers to refuse to disclose identifiable research data in response to subpoenas in any legal setting. However, there is little known about how effective Certificates are in practice. This article draws on our legal and empirical research on this topic to fill this information gap. It includes a description of the purpose of Certificates, their legislative and regulatory history, and a summary of the few reported and unreported cases that have dealt with Certificates. In addition, we outline other statutory confidentiality protections, compare them to the Certificate\u27s protections, and analyze some of the vulnerabilities of a Certificate\u27s protections. This analysis allows us to make specific recommendations for strengthening the protections afforded to research data
Quantum Zeno effect in a probed downconversion process
The distorsion of a spontaneous downconvertion process caused by an auxiliary
mode coupled to the idler wave is analyzed. In general, a strong coupling with
the auxiliary mode tends to hinder the downconversion in the nonlinear medium.
On the other hand, provided that the evolution is disturbed by the presence of
a phase mismatch, the coupling may increase the speed of downconversion. These
effects are interpreted as being manifestations of quantum Zeno or anti-Zeno
effects, respectively, and they are understood by using the dressed modes
picture of the device. The possibility of using the coupling as a nontrivial
phase--matching technique is pointed out.Comment: 11 pages, 4 figure
Quantum Zeno subspaces
The quantum Zeno effect is recast in terms of an adiabatic theorem when the
measurement is described as the dynamical coupling to another quantum system
that plays the role of apparatus. A few significant examples are proposed and
their practical relevance discussed. We also focus on decoherence-free
subspaces.Comment: 5 pages, 1 figure, to be published in Phys. Rev. Let
Zeno dynamics yields ordinary constraints
The dynamics of a quantum system undergoing frequent measurements (quantum
Zeno effect) is investigated. Using asymptotic analysis, the system is found to
evolve unitarily in a proper subspace of the total Hilbert space. For spatial
projections, the generator of the "Zeno dynamics" is the Hamiltonian with
Dirichlet boundary conditions.Comment: 6 page
Polarizing Tweets on Climate Change
We introduce a framework to analyze the conversation between two competing
groups of Twitter users, one who believe in the anthropogenic causes of climate
change (Believers) and a second who are skeptical (Disbelievers). As a case
study, we use Climate Change related tweets during the United Nation's (UN)
Climate Change Conference - COP24 (2018), Katowice, Poland. We find that both
Disbelievers and Believers talk within their group more than with the other
group; this is more so the case for Disbelievers than for Believers. The
Disbeliever messages focused more on attacking those personalities that believe
in the anthropogenic causes of climate change. On the other hand, Believer
messages focused on calls to combat climate change. We find that in both
Disbelievers and Believers bot-like accounts were equally active and that
unlike Believers, Disbelievers get their news from a concentrated number of
news sources
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