2,221 research outputs found
Effectively Regulating E-Cigarettes and Their Advertising—and the First Amendment
If tobacco smoking did not exist in the United States, there would be no reason, from a public health perspective, to allow addictive, nicotine-containing e-cigarettes to be marketed and sold. Because e-cigarette use, by itself, is neither beneficial nor benign to users and nonusers, the only public health justification for allowing e-cigarettes in the existing U.S. market would be if doing so would not sustain or increase existing smoking levels but would help smokers quit completely or provide addicted smokers a less harmful way to obtain the nicotine they crave. Yet e-cigarettes are now pervasive in the U.S. market, being sold with unnecessary harmful characteristics and being advertised in ways that encourage youth experimentation and use. Unless effectively regulated, e-cigarette use will be more harmful than necessary and their advertising will work to: (a) increase initiation among both youth and non-tobacco-using adults; (b) prompt former smokers to relapse back into addicted nicotine use; (c) encourage smokers to use e-cigarettes where they cannot smoke; and (d) prompt smokers to switch to e-cigarettes instead of quitting all tobacco and nicotine use. This paper proposes a viable way to regulate e-cigarettes and their advertising both to minimize the health harms they might cause and to allow e-cigarettes to fulfill their potential as cessation aids or harm-reduction products. Normally, any efforts by FDA to establish effective advertising restrictions must accommodate considerable constraints from the First Amendment’s commercial speech protections. However, because of existing text in the Tobacco Control Act, on the effective date of the final FDA deeming rule that puts e-cigarettes under FDA’s active tobacco product jurisdiction all nicotine-containing e-cigarettes will be on the U.S. market illegally until they can obtain permissive orders from FDA. That situation should reduce applicable First Amendment constraints, providing FDA with a tremendous opportunity to place the kinds of substantial restrictions and requirements on e-cigarette advertising necessary to minimize their harmful aspects and maximize their potential to produce substantial net public health benefits
Filling in the Blanks on Reducing Tobacco Product Addictiveness in the FCTC Partial Guidelines for Articles 9 & 10
The existing Partial Guidelines for Implementation of Articles 9 & 10 of the WHO Framework Convention for Tobacco Control includes a strategy for regulating tobacco products to reduce their attractiveness, but does not yet provide any guidance for reducing either the toxicity or the addictiveness of tobacco products. Section 1.2.1.2, “Addictiveness (dependence liability),” states only that: “This section has been left blank intentionally to indicate that guidance will be proposed at a later stage.” A related footnote says that the blanks will be filled “as new country experience, and scientific, medical and other evidence become available. . . [and] will also depend on the validation of the analytical chemical methods for testing and measuring cigarette contents and emissions.”
This article details that sufficient evidence and accurate testing methods are now available to begin providing useful guidance to countries that have the capacity to implement new measures to reduce the addictiveness of tobacco products and enforce compliance. Using the format of the existing partial guidelines, this working paper suggests possible draft text for the blank “Addictiveness” section, followed by a concise summary of supporting research and analysis
Effect of hyperon bulk viscosity on neutron-star r-modes
Neutron stars are expected to contain a significant number of hyperons in
addition to protons and neutrons in the highest density portions of their
cores. Following the work of Jones, we calculate the coefficient of bulk
viscosity due to nonleptonic weak interactions involving hyperons in
neutron-star cores, including new relativistic and superfluid effects. We
evaluate the influence of this new bulk viscosity on the gravitational
radiation driven instability in the r-modes. We find that the instability is
completely suppressed in stars with cores cooler than a few times 10^9 K, but
that stars rotating more rapidly than 10-30% of maximum are unstable for
temperatures around 10^10 K. Since neutron-star cores are expected to cool to a
few times 10^9 K within seconds (much shorter than the r-mode instability
growth time) due to direct Urca processes, we conclude that the gravitational
radiation instability will be suppressed in young neutron stars before it can
significantly change the angular momentum of the star.Comment: final PRD version, minor typos etc correcte
Nonlinear r-Modes in Neutron Stars: Instability of an unstable mode
We study the dynamical evolution of a large amplitude r-mode by numerical
simulations. R-modes in neutron stars are unstable growing modes, driven by
gravitational radiation reaction. In these simulations, r-modes of amplitude
unity or above are destroyed by a catastrophic decay: A large amplitude r-mode
gradually leaks energy into other fluid modes, which in turn act nonlinearly
with the r-mode, leading to the onset of the rapid decay. As a result the
r-mode suddenly breaks down into a differentially rotating configuration. The
catastrophic decay does not appear to be related to shock waves at the star's
surface. The limit it imposes on the r-mode amplitude is significantly smaller
than that suggested by previous fully nonlinear numerical simulations.Comment: Published in Phys. Rev. D Rapid Comm. 66, 041303(R) (2002
Second-order rotational effects on the r-modes of neutron stars
Techniques are developed here for evaluating the r-modes of rotating neutron
stars through second order in the angular velocity of the star. Second-order
corrections to the frequencies and eigenfunctions for these modes are evaluated
for neutron star models. The second-order eigenfunctions for these modes are
determined here by solving an unusual inhomogeneous hyperbolic boundary-value
problem. The numerical techniques developed to solve this unusual problem are
somewhat non-standard and may well be of interest beyond the particular
application here. The bulk-viscosity coupling to the r-modes, which appears
first at second order, is evaluated. The bulk-viscosity timescales are found
here to be longer than previous estimates for normal neutron stars, but shorter
than previous estimates for strange stars. These new timescales do not
substantially affect the current picture of the gravitational radiation driven
instability of the r-modes either for neutron stars or for strange stars.Comment: 13 pages, 5 figures, revte
Nonlinear Development of the Secular Bar-mode Instability in Rotating Neutron Stars
We have modelled the nonlinear development of the secular bar-mode
instability that is driven by gravitational radiation-reaction (GRR) forces in
rotating neutron stars. In the absence of any competing viscous effects, an
initially uniformly rotating, axisymmetric polytropic star with a ratio
of rotational to gravitational potential energy is driven by
GRR forces to a bar-like structure, as predicted by linear theory. The pattern
frequency of the bar slows to nearly zero, that is, the bar becomes almost
stationary as viewed from an inertial frame of reference as GRR removes energy
and angular momentum from the star. In this ``Dedekind-like'' state, rotational
energy is stored as motion of the fluid in highly noncircular orbits inside the
bar. However, in less than 10 dynamical times after its formation, the bar
loses its initially coherent structure as the ordered flow inside the bar is
disrupted by what appears to be a purely hydrodynamical, short-wavelength,
``shearing'' type instability. The gravitational waveforms generated by such an
event are determined, and an estimate of the detectability of these waves is
presented.Comment: 25 pages, 9 figures, accepted for publication in ApJ, refereed
version, updated, for quicktime movie, see
http://www.phys.lsu.edu/~ou/movie/fmode/new/fmode.b181.om4.2e5.mo
Stability of the r-modes in white dwarf stars
Stability of the r-modes in rapidly rotating white dwarf stars is
investigated. Improved estimates of the growth times of the
gravitational-radiation driven instability in the r-modes of the observed DQ
Her objects are found to be longer (probably considerably longer) than 6x10^9y.
This rules out the possibility that the r-modes in these objects are emitting
gravitational radiation at levels that could be detectable by LISA. More
generally it is shown that the r-mode instability can only be excited in a very
small subset of very hot (T>10^6K), rather massive (M>0.9M_sun) and very
rapidly rotating (P_min<P<1.2P_min) white dwarf stars. Further, the growth
times of this instability are so long that these conditions must persist for a
very long time (t>10^9y) to allow the amplitude to grow to a dynamically
significant level. This makes it extremely unlikely that the r-mode instability
plays a significant role in any real white dwarf stars.Comment: 5 Pages, 5 Figures, revte
Differential rotation of nonlinear r-modes
Differential rotation of r-modes is investigated within the nonlinear theory
up to second order in the mode amplitude in the case of a slowly-rotating,
Newtonian, barotropic, perfect-fluid star. We find a nonlinear extension of the
linear r-mode, which represents differential rotation that produces large scale
drifts of fluid elements along stellar latitudes. This solution includes a
piece induced by first-order quantities and another one which is a pure
second-order effect. Since the latter is stratified on cylinders, it cannot
cancel differential rotation induced by first-order quantities, which is not
stratified on cylinders. It is shown that, unlikely the situation in the
linearized theory, r-modes do not preserve vorticity of fluid elements at
second-order. It is also shown that the physical angular momentum and energy of
the perturbation are, in general, different from the corresponding canonical
quantities.Comment: 9 pages, revtex4; section III revised, comments added in Introduction
and Conclusions, references updated; to appear in Phys. Rev.
The rotational modes of relativistic stars: Numerical results
We study the inertial modes of slowly rotating, fully relativistic compact
stars. The equations that govern perturbations of both barotropic and
non-barotropic models are discussed, but we present numerical results only for
the barotropic case. For barotropic stars all inertial modes are a hybrid
mixture of axial and polar perturbations. We use a spectral method to solve for
such modes of various polytropic models. Our main attention is on modes that
can be driven unstable by the emission of gravitational waves. Hence, we
calculate the gravitational-wave growth timescale for these unstable modes and
compare the results to previous estimates obtained in Newtonian gravity (i.e.
using post-Newtonian radiation formulas). We find that the inertial modes are
slightly stabilized by relativistic effects, but that previous conclusions
concerning eg. the unstable r-modes remain essentially unaltered when the
problem is studied in full general relativity.Comment: RevTeX, 29 pages, 31 eps figure
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