Proceedings of the Spacecraft Charging Technology Conference: Executive Summary

Aerospace environments are reviewed in reference to spacecraft charging. Modelling, a theoretical scheme which can be used to describe the structure of the sheath around the spacecraft and to calculate the charging currents within, is discussed. Materials characterization is considered for experimental determination of the behavior of typical spacecraft materials when exposed to simulated geomagnetic substorm conditions. Materials development is also examined for controlling and minimizing spacecraft charging or at least for distributing the charge in an equipotential manner, using electrical conductive surfaces for materials exposed to space environment

Wildfire, climate, and perceptions in northeast Oregon

Wildfire poses a rising threat in the western USA, fueled by synergies between historical fire suppression, changing land use, insects and disease, and shifts toward a drier, warmer climate. The rugged landscapes of northeast Oregon, with their historically forest- and resource-based economies, have been one of the areas affected. A 2011 survey found area residents highly concerned about fire and insect threats, but not about climate change. In 2014 we conducted a second survey that, to explore this apparent disconnect, included questions about past and future summertime (fire season) temperatures. Although regional temperatures have warmed in recent decades at twice the global rate, accompanied by increasing dryness and fire risks, the warming itself is recognized by only 40 % of our respondents. Awareness of recent warming proves unrelated to individual characteristics that might indicate experience on the land: old-timer versus newcomer status, year-round versus seasonal residence, and ownership of forested land. Perceptions of past warming and expectations of future warming are more common among younger respondents and less common among Tea Party supporters. The best-educated partisans stand farthest apart. Perceptions about local temperatures that are important for adaptation planning thus follow ideological patterns similar to beliefs about global climate change

Time dependence of evanescent quantum waves

The time dependence of quantum evanescent waves generated by a point source with an infinite or a limited frequency band is analyzed. The evanescent wave is characterized by a forerunner (transient) related to the precise way the source is switched on. It is followed by an asymptotic, monochromatic wave which at long times reveals the oscillation frequency of the source. For a source with a sharp onset the forerunner is exponentially larger than the monochromatic solution and a transition from the transient regime to the asymtotic regime occurs only at asymptotically large times. In this case, the traversal time for tunneling plays already a role only in the transient regime. To enhance the monochromatic solution compared to the forerunner we investigate (a) frequency band limited sources and (b) the short time Fourier analysis (the spectrogram) corresponding to a detector which is frequency band limited. Neither of these two methods leads to a precise determination of the traversal time. However, if they are limited to determine the traversal time only with a precision of the traversal time itself both methods are successful: In this case the transient behavior of the evanescent waves is at a time of the order of the traversal time followed by a monochromatic wave which reveals the frequency of the source.Comment: 16 text pages and 9 postscript figure

Forest Views: Shifting Attitudes Toward the Environment in Northeast Oregon

This brief reports on a telephone survey conducted in fall 2014 as part of the ongoing Communities and Forests in Oregon (CAFOR) project. CAFOR focuses on seven counties in the Blue Mountains of northeast Oregon (Baker, Crook, Grant, Umatilla, Union, Wallowa, and Wheeler), where the landscape and local livelihoods are changing in interconnected ways. In an effort to inform policy development around natural resource management, the study seeks to understand how public perceptions of climate change and forest management intersect. Authors Angela Boag, Joel Hartter, Lawrence Hamilton, Forrest Stevens, Mark Ducey, Michael Palace, Nils Christoffersen, and Paul Oester report that 65 percent of those surveyed believe that forests are less healthy than they were twenty years ago. Approximately half of residents support increased user fees to improve forest health on federal land, and a majority believes that climate change is happening, although opinion is split between those who believe it is human-caused and those who believe it is caused by natural forces. The authors conclude that innovative economic and policy solutions are needed across the Inland West to help people and forests regain a strong and productive relationship that both supports livelihoods and sustains working landscapes

Does it matter if people think climate change is human caused?

There is a growing consensus that climate is changing, but beliefs about the causal factors vary widely among the general public. Current research shows that such causal beliefs are strongly influenced by cultural, political, and identity-driven views. We examined the influence that local perceptions have on the acceptance of basic facts about climate change. We also examined the connection to wildfire by local people. Two recent telephone surveys found that 37% (in 2011) and 46% (in 2014) of eastern Oregon (USA) respondents accept the scientific consensus that human activities are now changing the climate. Although most do not agree with that consensus, large majorities (85–86%) do agree that climate is changing, whether by natural or human causes. Acceptance of anthropogenic climate change generally divides along political party lines, but acceptance of climate change more generally, and concerns about wildfire, transcend political divisions. Support for active forest management to reduce wildfire risks is strong in this region, and restoration treatments could be critical to the resilience of both communities and ecosystems. Although these immediate steps involve adaptations to a changing climate, they can be motivated without necessarily invoking human-caused climate change, a divisive concept among local landowners

Barite encrustation of benthic sulfur-oxidizing bacteria at a marine cold seep

Crusts and chimneys composed of authigenic barite are found at methane seeps and hydrothermal vents that expel fluids rich in barium. Microbial processes have not previously been associated with barite precipitation in marine cold seep settings. Here, we report on the precipitation of barite on filaments of sulfide-oxidizing bacteria at a brine seep in the Gulf of Mexico. Barite-mineralized bacterial filaments in the interiors of authigenic barite crusts resemble filamentous sulfide-oxidizing bacteria of the genus Beggiatoa. Clone library and iTag amplicon sequencing of the 16S rRNA gene show that the barite crusts that host these filaments also preserve DNA of Candidatus Maribeggiatoa, as well as sulfate-reducing bacteria. Isotopic analyses show that the sulfur and oxygen isotope compositions of barite have lower δ34S and δ18O values than many other marine barite crusts, which is consistent with barite precipitation in an environment in which sulfide oxidation was occurring. Laboratory experiments employing isolates of sulfide-oxidizing bacteria from Gulf of Mexico seep sediments showed that under low sulfate conditions, such as those encountered in brine fluids, sulfate generated by sulfide-oxidizing bacteria fosters rapid barite precipitation localized on cell biomass, leading to the encrustation of bacteria in a manner reminiscent of our observations of barite-mineralized Beggiatoa in the Gulf of Mexico. The precipitation of barite directly on filaments of sulfide-oxidizing bacteria, and not on other benthic substrates, suggests that sulfide oxidation plays a role in barite formation at certain marine brine seeps where sulfide is oxidized to sulfate in contact with barium-rich fluids, either prior to, or during, the mixing of those fluids with sulfate-containing seawater in the vicinity of the sediment/water interface. As with many other geochemical interfaces that foster mineral precipitation, both biological and abiological processes likely contribute to the precipitation of barite at marine brine seeps such as the one studied here

Spin-transfer mechanism of ferromagnetism in polymerized fullerenes: AbinitioAb initio calculations

A mechanism of the high temperature ferromagnetism in polymerized fullerenes is suggested. It is assumed that some of the C$_{60}$ molecules in the crystal become magnetically active due to spin and charge transfer from the paramagnetic impurities (atoms or groups), such as hydrogen, fluorine, hydroxyl group OH, amino group NH$_2$, or methyl group CH$_3$, dispersed in the fullerene matrix. The exchange interaction between the spins localized on the magnetically active fullerenes is evaluated using \textit{ab initio} calculations. The nearest neighbour and next nearest neighbour exchange interaction is found to be in the range $0.1\div 0.3$ eV, that is, high enough to account for the room temperature ferromagnetism.Comment: typos corrected, 8 pages, 3 figures, LaTe

Nuclear spin driven quantum relaxation in LiY_0.998Ho_0.002F_4

Staircase hysteresis loops of the magnetization of a LiY_0.998Ho_0.002F_4 single crystal are observed at subkelvin temperatures and low field sweep rates. This behavior results from quantum dynamics at avoided level crossings of the energy spectrum of single Ho^{3+} ions in the presence of hyperfine interactions. Enhanced quantum relaxation in constant transverse fields allows the study of the relative magnitude of tunnel splittings. At faster sweep rates, non-equilibrated spin-phonon and spin-spin transitions, mediated by weak dipolar interactions, lead to magnetization oscillations and additional steps.Comment: 5 pages, 5 eps figures, using RevTe

Time scale of forerunners in quantum tunneling

The forerunners preceding the main tunneling signal of the wave created by a source with a sharp onset or by a quantum shutter, have been generally associated with over-the-barrier (non-tunneling) components. We demonstrate that, while this association is true for distances which are larger than the penetration lenght, for smaller distances the forerunner is dominated by under-the-barrier components. We find that its characteristic arrival time is inversely proportional to the difference between the barrier energy and the incidence energy, a tunneling time scale different from both the phase time and the B\"uttiker-Landauer (BL) time.Comment: Revtex4, 14 eps figure

Spitzer/MIPS Limits on Asteroidal Dust in the Pulsar Planetary System PSR B1257+1

With the MIPS camera on Spitzer, we have searched for far-infrared emission from dust in the planetary system orbiting pulsar PSR 1257+12. With accuracies of 0.05 mJy at 24 um and 1.5 mJy at 70 um, photometric measurements find no evidence for emission at these wavelengths. These observations place new upper limits on the luminosity of dust with temperatures between 20 and 1000 K. They are particularly sensitive to dust temperatures of 100-200 K, for which they limit the dust luminosity to below $3 \times 10^{-5}$ of the pulsar's spin-down luminosity, three orders of magnitude better than previous limits. Despite these improved constraints on dust emission, an asteroid belt similar to the Solar System's cannot be ruled out