2,213 research outputs found

    Effectively Regulating E-Cigarettes and Their Advertising—and the First Amendment

    Get PDF
    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

    Get PDF
    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

    Full text link
    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

    Get PDF
    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

    Get PDF
    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

    Get PDF
    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 n=1/2n=1/2 polytropic star with a ratio of rotational to gravitational potential energy T/W=0.181T/|W| = 0.181 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

    Get PDF
    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

    Full text link
    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

    Full text link
    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
    corecore