Parametric instabilities in magnetized multicomponent plasmas

This paper investigates the excitation of various natural modes in a magnetized bi-ion or dusty plasma. The excitation is provided by parametrically pumping the magnetic field. Here two ion-like species are allowed to be fully mobile. This generalizes our previous work where the second heavy species was taken to be stationary. Their collection of charge from the background neutral plasma modifies the dispersion properties of the pump and excited waves. The introduction of an extra mobile species adds extra modes to both these types of waves. We firstly investigate the pump wave in detail, in the case where the background magnetic field is perpendicular to the direction of propagation of the pump wave. Then we derive the dispersion equation relating the pump to the excited wave for modes propagating parallel to the background magnetic field. It is found that there are a total of twelve resonant interactions allowed, whose various growth rates are calculated and discussed.Comment: Published in May 2004; this is a late submission to the archive. 14 pages, 8 figure

The Manring Mounds: A Hopewell Center in the Mad River Drainage, Clark County, Ohio

Author Institution: Department of Sociology and Anthropology, Kent State UniversityThe Manring archaeological site is a Hopewell center located on Beaver Creek, a tributary of the Mad River, in Clark County, Ohio. Comparisons with other excavated sites show the Manring site to represent a substantial labor commitment; it includes one of the very largest known Hopewell mounds. The presence of such exotica as an obsidian spear, a copper breastplate, copper celts and marine shell beads are also noteworthy, especially given the site's hinterland location. The juxtaposition of major routes of travel is suggested to be a more important factor in explaining site location than any direct subsistence advantage. Cross-dating indicates that Manring was occupied shortly after A. D. 100, or coincident with the early Pike phase as defined in the Illinois Valley

How Will Wildlife Crossings Mitigate Roads for Wildlife in the Face of Climate Change?

This paper will address the developing trends in wildlife crossing structure research across the western U.S. and along US 93 South in Montana. This discussion may help to better design and retrofit structures to facilitate wildlife movement in the face of climate change. The objectives of our wildlife crossing structure research across the west are to determine wildlife use of crossing structures and structure designs that work best in passing large and medium mammals. Many of today’s wildlife crossing structures and existing culverts and bridges along roadways were designed before the science of transportation ecology had developed enough to understand what designs worked for different species. Our method of evaluating these new and existing structures is to place motion-sensed camera traps 10 m from the entrances to the culverts and bridges to monitor wildlife reactions to the structures. Wildlife approaches, successful passages through the structure, and repels away from the structure are tallied for every individual. Species’ reactions to culverts and bridges differ. White-tailed deer are willing to use many different sized culverts and bridges, while mule deer are more cautious. Carnivores use structures of all types, although the landscape factors such as human development may play a role in their willingness to use some structures. These and other results have greater implications for species adaptations to climate change: it will be critical that roads be permeable for the entire suites of species in an area as they need to move to adapt to changing conditions

Diagnostic criteria for grading the severity of acute motion sickness

Diagnostic criteria for grading severity of acute motion sicknes

Moving Wildlife Under US Highway 93 in Montana’s Bitterroot Valley through Wildlife Crossing Structures

The impediment that the Bitterroot Valley’s roads and vehicle traffic pose for wildlife movement can be partially mitigated with wildlife crossing structures. This study evaluates 18 wildlife crossing structures installed by Montana Department of Transportation along US Highway 93, south of Missoula. Through the use of camera traps, this ongoing study evaluates the efficacy of these crossing in allowing wildlife to move safely under the road, and in reducing wildlife-vehicle collisions between the communities of Lolo and Hamilton. Photographic data on white-tailed deer use were analyzed for success rate and rate of repellence. Use of structures by other species of wildlife was also analyzed. In three years of post-construction monitoring, success rates ranged from zero to two white tailed-deer passes per day. Carnivores were photographed using crossings and moving over the highway at grade. At this time, bridge structures have a higher success at passing white-tail deer that approach them than culverts, except for a large (6 m wide and high) steel culvert, which worked as well as bridges. Fencing to crossings is important: bridges without wildlife fencing had success rates well under 0.2 deer passes per day. At this time overall trends appear to suggest that: wildlife fencing, more vegetation at the ends of structures, and wider structures result in higher success rates for white-tailed deer. When the study is completed in 2015 we will have a better understanding of the structure and landscape variables important to facilitate wildlife use of wildlife crossing structures

Parametric instability in dark molecular clouds

The present work investigates the parametric instability of parallel propagating circularly polarized Alfven(pump) waves in a weakly ionized molecular cloud. It is shown that the relative drift between the plasma particles gives rise to the Hall effect resulting in the modified pump wave characteristics. Although the linearized fluid equations with periodic coefficients are difficult to solve analytically, it is shown that a linear transformation can remove the periodic dependence. The resulting linearized equations with constant coefficients are used to derive an algebraic dispersion relation. The growth rate of the parametric instability is a sensitive function of the amplitude of the pump wave as well as to the ratio of the pump and the modified dust-cyclotron frequencies. The instability is insensitive to the plasma-beta The results are applied to the molecular clouds.Comment: 27 page, 5 figures, accepted in Ap

Structure of the specificity domain of the Dorsal homologue Gambif1 bound to DNA

Background: NF-κB/Rel transcription factors play important roles in immunity and development in mammals and insects. Their activity is regulated by their cellular localization, homo- and heterodimerization and association with other factors on their target gene promoters. Gambif1 fromAnopheles gambiae is a member of the Rel family and a close homologue of the morphogen Dorsal, which establishes dorsoventral polarity in theDrosophila embryo.Results: We present the crystal structure of the N-terminal specificity domain of Gambif1 bound to DNA. This first structure of an insect Rel protein–DNA complex shows that Gambif1 binds a GGG half-site element using a stack of three arginine sidechains. Differences in affinity to Dorsal binding sites in target gene promoters are predicted to arise from base changes in these GGG elements. An arginine that is conserved in class II Rel proteins (members of which contain a transcription activation domain) contacts the outermost guanines of the DNA site. This previously unseen specific contact contributes strongly to the DNA-binding affinity and might be responsible for differences in specificity between Rel proteins of class I and II.Conclusions: The Gambif1–DNA complex structure illustrates how differences in Dorsal affinity to binding sites in developmental gene promoters are achieved. Comparison with other Rel–DNA complex structures leads to a general model for DNA recognition by Rel proteins

Effects of noise and confidence thresholds in nominal and metric Axelrod dynamics of social influence

We study the effects of bounded confidence thresholds and of interaction and external noise on Axelrod's model of social influence. Our study is based on a combination of numerical simulations and an integration of the mean-field Master equation describing the system in the thermodynamic limit. We find that interaction thresholds affect the system only quantitatively, but that they do not alter the basic phase structure. The known crossover between an ordered and a disordered state in finite systems subject to external noise persists in models with general confidence threshold. Interaction noise here facilitates the dynamics and reduces relaxation times. We also study Axelrod systems with metric features, and point out similarities and differences compared to models with nominal features. Metric features are used to demonstrate that a small group of extremists can have a significant impact on the opinion dynamics of a population of Axelrod agents.Comment: 15 pages, 12 figure

Wormholes, Gamma Ray Bursts and the Amount of Negative Mass in the Universe

In this essay, we assume that negative mass objects can exist in the extragalactic space and analyze the consequences of their microlensing on light from distant Active Galactic Nuclei. We find that such events have very similar features to some observed Gamma Ray Bursts and use recent satellite data to set an upper bound to the amount of negative mass in the universe.Comment: Essay awarded ``Honorable Mention'' in the Gravity Foundation Research Awards, 199