Compensation in epitaxial cubic SiC films

Hall measurements on four n-type cubic SiC films epitaxially grown by chemical vapor deposition on SiC substrates are reported. The temperature dependent carrier concentrations indicate that the samples are highly compensated. Donor ionization energies, E sub D, are less than one half the values previously reported. The values for E sub D and the donor concentration N sub D, combined with results for small bulk platelets with nitrogen donors, suggest the relation E sub D (N sub D) = E sub D(O) - alpha N sub N sup 1/3 for cubic SiC. A curve fit gives alpha is approx 2.6x10/5 meV cm and E sub D (O) approx 48 meV, which is the generally accepted value of E sub D(O) for nitrogen donors in cubic SiC

A Network Inversion Filter combining GNSS and InSAR for tectonic slip modeling

Studies of the earthquake cycle benefit from long-term time-dependent slip modeling, as it can be a powerful means to improve our understanding on the interaction of earthquake cycle processes such as interseismic, coseismic, postseismic, and aseismic slip. Observations from Interferometric Synthetic Aperture Radar (InSAR) allow us to model slip at depth with a higher spatial resolution than when using GNSS alone. While the temporal resolution of InSAR has typically been limited, the recent fleet of SAR satellites including Sentinel-1, COSMO-SkyMED, and RADARSAT-2 permits the use of InSAR for time-dependent slip modeling, at intervals of a few days when combined. With the vast amount of SAR data available, simultaneous data inversion of all epochs becomes challenging. Here, we expanded the original Network Inversion Filter to include InSAR observations of surface displacements in addition to GNSS. In the NIF framework, geodetic observations are limited to those of a given epoch, with a stochastic model describing slip evolution over time. The combination of the Kalman forward filtering and backward smoothing allows all geodetic observations to constrain the complete observation period. Combining GNSS and InSAR allows modeling of time-dependent slip at unprecedented spatial resolution. We validate the approach with a simulation of the 2006 Guerrero slow slip event. We highlight the importance of including InSAR covariance information, and demonstrate that InSAR provides an additional constraint on the spatial extent of the slow slip

The Impact Of Consumer Attitudes About Bioengineering On Purchase Behavior Intentions: Moderating Effects Of Innate Consumer Innovativeness And Anxiety

Biotechnology is anticipated to be the next generation of innovations and is predicted to surpass the IT revolution in terms of economic prosperity (Darby and Zucher, 2003).  But available behavioral and social research relating to biotechnology is at its infant stage.  Most studies are qualitative in nature (i.e., focus groups) and are limited to public policy issues such as awareness, knowledge, and perception of risks (Bredahl, 1999; Frewer et al., 1997; Frewer, Howard, and Shepherd, 1997). According to Bredahl, 2001, few research projects have yet to determine how consumer attitudes can be expected to influence subsequent purchase behavior intentions with genetically modified products. As the U.S. Food and Drug Administration (FDA) continues to approve more and more inventions of biotechnology (i.e., foods such as genetically engineered potatoes and rice; industrial plastic from genetically modified organisms; and life saving pharmaceuticals for diseases such as cancer, HIV, and Alzheimer’s) there is a need for research that investigates how consumer attitudes about genetically modified products influence their purchase intentions and subsequent purchase behavior.  The primary purpose of this research is to investigate how consumer attitudes about bioengineering influence their purchase behavior intentions. Second, the influence of two personal variables innate consumer innovativeness and general anxiety about bioengineering as they relate to purchase behavior intentions will be investigated.  Finally, the study also makes an attempt to determine if the relationship between attitude and behavior intentions is moderated by the two personal variables innate consumer innovativeness and general anxiety about bioengineering.  Personal variables such as these can reasonably be expected to have a differential impact on the relationship between attitude about bioengineering and purchase behavior intentions.  That is, the strength of the relationship between attitude and purchase behavior intentions is likely to be stronger for consumers that are innovative and less anxious about bioengineering than others.  The study results have implications for both researchers and promoters of bioengineering. For researchers, it should be noted that an extensive literature search was unable to find any empirical research to date that have investigated the moderating effects on the relationship between attitude about bioengineering and purchase behavior intentions.  For practitioners, the study will aid biotechnology firms in their efforts in building a more positive attitude about biotechnology in general and to identify the profile of consumers that are more likely to purchase and use products of this technology

The Bacterial Chemotactic Response Reflects a Compromise Between Transient and Steady State Behavior

Swimming bacteria detect chemical gradients by performing temporal comparisons of recent measurements of chemical concentration. These comparisons are described quantitatively by the chemotactic response function, which we expect to optimize chemotactic behavioral performance. We identify two independent chemotactic performance criteria: in the short run, a favorable response function should move bacteria up chemoattractant gradients, while in the long run, bacteria should aggregate at peaks of chemoattractant concentration. Surprisingly, these two criteria conflict, so that when one performance criterion is most favorable, the other is unfavorable. Since both types of behavior are biologically relevant, we include both behaviors in a composite optimization that yields a response function that closely resembles experimental measurements. Our work suggests that the bacterial chemotactic response function can be derived from simple behavioral considerations, and sheds light on how the response function contributes to chemotactic performance.Comment: 19 pages, 5 figure

Raman frequency shift in oxygen functionalized carbon nanotubes

In terms of lattice dynamics theory, we study the vibrational properties of the oxygen-functionalized single wall carbon nanotubes (O-SWCNs). Due to the C-O and O-O interactions, many degenerate phonon modes are split and even some new phonon modes are obtained, different from the bare SWCNs. A distinct Raman shift is found in both the radial breathing mode and G modes, depending not only on the tube diameter and chirality but also on oxygen coverage and adsorption configurations. With the oxygen coverage increasing, interesting, a nonmonotonic up- and down-shift is observed in G modes, which is contributed to the competition between the bond expansion and contraction, there coexisting in the functionalized carbon nanotube.Comment: 4 pages, 3 figures, 1 tabl

From sensorimotor dependencies to perceptual practices: making enactivism social

Proponents of enactivism should be interested in exploring what notion of action best captures the type of action-perception link that the view proposes, such that it covers all the aspects in which our doings constitute and are constituted by our perceiving. This article proposes and defends the thesis that the notion of sensorimotor dependencies is insufficient to account for the reality of human perception, and that the central enactive notion should be that of perceptual practices. Sensorimotor enactivism is insufficient because it has no traction on socially dependent perceptions, which are essential to the role and significance of perception in our lives. Since the social dimension is a central desideratum in a theory of human perception, enactivism needs a notion that accounts for such an aspect. This article sketches the main features of the Wittgenstein-inspired notion of perceptual practices as the central notion to understand perception. Perception, I claim, is properly understood as woven into a type of social practices that includes food, dance, dress, music, etc. More specifically, perceptual practices are the enactment of culturally structured, normatively rich techniques of commerce of meaningful multi- and inter-modal perceptible material. I argue that perceptual practices explain three central features of socially dependent perception: attentional focus, aspects’ saliency, and modal-specific harmony-like relations