Slowly modulated oscillations in nonlinear diffusion processes

It is shown here that certain systems of nonlinear (parabolic) reaction-diffusion equations have solutions which are approximated by oscillatory functions in the form R(ξ - cτ)P(t^*) where P(t^*) represents a sinusoidal oscillation on a fast time scale t* and R(ξ - cτ) represents a slowly-varying modulating amplitude on slow space (ξ) and slow time (τ) scales. Such solutions describe phenomena in chemical reactors, chemical and biological reactions, and in other media where a stable oscillation at each point (or site) undergoes a slow amplitude change due to diffusion

The Future of Nanotechnology Risk Perceptions: An Experimental Investigation of Two Hypotheses

This paper reports the results of an experiment designed to test competing conjectures about the evolution of public attitudes toward nanotechnology. The rational enlightenment hypothesis holds that members of the public will become favorably disposed to nanotechnology as balanced and accurate information about it disseminates. The cultural cognition hypothesis, in contrast, holds that members of the public are likely to polarize along cultural lines when exposed to such information. Using a between-subjects design (N = 1,862), the experiment compared the perceptions of subjects exposed to balanced information on the risks and benefits of nanotechnology to the perceptions of subjects exposed to no information. The results strongly confirmed the cultural polarization hypothesis and furnished no support for the rational enlightenment hypothesis. Data obtained in the experiment also suggested that the observed correlation in the general public between familiarity with nanotechnology and a positive view of it is spurious: familiarity does not cause a favorable view; rather other influences, including individualistic cultural values, incline certain individuals both to form a positive view and to learn about nanotechnology. The paper also discusses the implications of these findings for promoting informed public understandings of nanotechnology

Cultural Cognition of the Risks and Benefits of Nanotechnology

We conducted an experimental public opinion study of the effect of balanced information on nanotechnology risk-benefit perceptions. The study found that subjects did not react in a uniform, much less a uniformly positive manner, but rather polarized along lines consistent with cultural predispositions toward technological risk generally

The Future of Nanotechnology Risk Perceptions: An Experimental Investigation of Two Hypotheses

This paper reports the results of an experiment designed to test competing conjectures about the evolution of public attitudes toward nanotechnology. The rational enlightenment hypothesis holds that members of the public will become favorably disposed to nanotechnology as balanced and accurate information about it disseminates. The cultural cognition hypothesis, in contrast, holds that members of the public are likely to polarize along cultural lines when exposed to such information. Using a between-subjects design (N = 1,862), the experiment compared the perceptions of subjects exposed to balanced information on the risks and benefits of nanotechnology to the perceptions of subjects exposed to no information. The results strongly confirmed the cultural polarization hypothesis and furnished no support for the rational enlightenment hypothesis. Data obtained in the experiment also suggested that the observed correlation in the general public between familiarity with nanotechnology and a positive view of it is spurious: familiarity does not cause a favorable view; rather other influences, including individualistic cultural values, incline certain individuals both to form a positive view and to learn about nanotechnology. The paper also discusses the implications of these findings for promoting informed public understandings of nanotechnology

Recent Clean Air Act Developments—2006

Air is the ultimate public good. No one owns it but everyone uses it. Protecting it is clearly a great challenge. Since its inception in the mid-1960s, the federal Clean Air Act (CAA) has been a crucial component in managing this resource, but it has also been a source of strife and discontent. The law was forward-looking for its time, pressing polluters to radically change their ways, while still accounting for the fact that we would never be a zero-pollution society. It has also changed with the times, as problems that could not have been imagined in 1970, such as atmospheric ozone depletion and acid rain, have since been addressed, while other issues have been revisited as scientific understanding of atmospheric processes, such as those governing the formation of smog and the distribution of airborne toxics, has improved

Cultural Cognition of the Risks and Benefits of Nanotechnology

We conducted an experimental public opinion study of the effect of balanced information on nanotechnology risk-benefit perceptions. The study found that subjects did not react in a uniform, much less a uniformly positive manner, but rather polarized along lines consistent with cultural predispositions toward technological risk generally

Who Fears the HPV Vaccine, Who Doesn\u27t, and Why? An Experimental Study of the Mechanisms of Cultural Cognition

The cultural cognition hypothesis holds that individuals are disposed to form risk perceptions that reflect and reinforce their commitments to contested views of the good society. This paper reports the results of a study that used the controversy over mandatory HPV vaccination to test the cultural cognition hypothesis. Although public health officials have recommended that all girls aged 11 or 12 be vaccinated for HPV - a virus that causes cervical cancer and that is transmitted by sexual contact - political controversy has blocked adoption of mandatory school-enrollment vaccination programs in all but one state. A multi-stage experimental study of a large and diverse sample of American adults (N = 1,500) found evidence that cultural cognition generates disagreement about the risks and benefits of the HPV vaccine. It does so, the experiment determined, through two mechanisms: biased assimilation, and the credibility heuristic. In addition to describing the study, the paper discusses the theoretical and practical implications of these findings

A digital boxcar integrator for IMS spectra

When trying to detect or quantify a signal at or near the limit of detectability, it is invariably embeded in the noise. This statement is true for nearly all detectors of any physical phenomena and the limit of detectability, hopefully, occurs at very low signal-to-noise levels. This is particularly true of IMS (Ion Mobility Spectrometers) spectra due to the low vapor pressure of several chemical compounds of great interest and the small currents associated with the ionic detection process. Gated Integrators and Boxcar Integrators or Averagers are designed to recover fast, repetitive analog signals. In a typical application, a time 'Gate' or 'Window' is generated, characterized by a set delay from a trigger or gate pulse and a certain width. A Gated Integrator amplifies and integrates the signal that is present during the time the gate is open, ignoring noise and interference that may be present at other times. Boxcar Integration refers to the practice of averaging the output of the Gated Integrator over many sweeps of the detector. Since any signal present during the gate will add linearly, while noise will add in a 'random walk' fashion as the square root of the number of sweeps, averaging N sweeps will improve the 'Signal-to-Noise Ratio' by a factor of the square root of N

Biased Assimilation, Polarization, and Cultural Credibility: An Experimental Study of Nanotechnology Risk Perceptions

We present the results from the second in a series of ongoing experimental studies of public perceptions of nanotechnology risks. Like the first study, the current one found that members of the public, most of whom know little or nothing about nanotechnology, polarize along cultural lines when exposed to information about it. Extending previous results, the current study also found that cultural polarization of this sort interacts with the perceived cultural identities of policy advocates. Polarization along expected lines grew even more extreme when subjects of diverse cultural outlooks observed an advocate whose values they share advancing an argument they were predisposed to accept, and an advocate whose values they reject advancing an argument they were predisposed to resist. But when those same advocates were assigned the opposite positions, subjects formed perceptions of nanotechnology risks diametrically opposed to the ones normally associated with their own cultural predispositions. Finally, when there was no consistent relationship between the perceived values of advocates and positions taken on nanotechnology risk and benefits, cultural polarization was neutralized. The significance of these findings for promotion of informed public understanding of nanotechnology is discussed

Mixer Assembly for a Gas Turbine Engine

A mixer assembly for a gas turbine engine is provided, including a main mixer with fuel injection holes located between at least one radial swirler and at least one axial swirler, wherein the fuel injected into the main mixer is atomized and dispersed by the air flowing through the radial swirler and the axial swirler