Reduction of trapped ion anomalous heating by in situ surface plasma cleaning

Anomalous motional heating is a major obstacle to scalable quantum information processing with trapped ions. While the source of this heating is not yet understood, several previous studies suggest that surface contaminants may be largely responsible. We demonstrate an improvement by a factor of four in the room-temperature heating rate of a niobium surface electrode trap by in situ plasma cleaning of the trap surface. This surface treatment was performed with a simple homebuilt coil assembly and commercially-available matching network and is considerably gentler than other treatments, such as ion milling or laser cleaning, that have previously been shown to improve ion heating rates. We do not see an improvement in the heating rate when the trap is operated at cryogenic temperatures, pointing to a role of thermally-activated surface contaminants in motional heating whose activity may freeze out at low temperatures.Comment: 5 pages, 4 figure

DIMINISHING MARGINAL VALUE

The notion of diminishing marginal value has had a profound impact on the development of neoclassical theory. Early neoclassical scholars had considerable difficulty convincing contemporaries of the new paradigm's value until political economists, including Jevons and Walras, used the critical assumption of diminishing marginal value to link utility and demand. While diminishing marginal value remains a key component of modern economic intuition, there is surprisingly little empirical verification of its existence or level. This paper gathers field data across a myriad of subject pools--from undergraduate students to PTA members to sportscard enthusiasts--to examine several aspects of preferences in both price and exchange institutions. Examining behavior of nearly 900 subjects across several treatments, we find strong evidence of diminishing marginal value.Research Methods/ Statistical Methods,

LibTube Team: Creating Tutorials Together, on a Dime, and in No Time

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REVIEW: Reading Faulkner: Introductions to the First Thirteen Novels

Review of the non-fiction book Reading Faulkner: Introductions to the First Thirteen Novels. Content by Richard Marius, compiled and edited by Nancy Grisham Anderson

Alien Registration- Mcconnell, John (Litchfield, Kennebec County)

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Sheltering Corporate Assets from Political Extraction

We hypothesize that firms structure their asset holdings so as to shelter assets from extraction by politicians and bureaucrats. In countries where the threat of political extraction is higher, we hypothesize that firms hold a lower fraction of their assets in liquid form. Consistent with this conjecture, using data for over 30,000 firms across 109 countries, we find that corporate holdings of liquid assets are negatively correlated with measures of political corruption. Further, annual investment in property, plant, equipment, and inventory plus dividends is positively correlated with measures of political corruption suggesting that owners channel their cash into harder to extract assets. To the extent that the threat of political extraction moves firms away from their otherwise optimal levels of liquid assets, our findings suggest that the threat of political extraction may reduce economic development not only through the direct costs of political payoffs, but also because the potential for asset extraction moves firms away from their otherwise optimal asset holdings.

Why Did Auction Rate Bond Auctions Fail During 2007-2008?

The auction rate bond market grew from inauspicious beginnings in 1985 to representing a significant fraction of the municipal bond market in 2007 with a total of 603 issuances that year raising more than $35 billion in capital. Since March of 2008 not a single auction rate bond has been issued. The last issuance coincided with a wave of “failures” of auction rate bond auctions during the early winter of 2008. Pundits have attributed the auction failures to a “frozen” market and hint that irrationality on the part of investors precipitated the auction failures. Missing from the headlines is that all auction rate bonds have interest rate caps that limit their yields. We find that, contrary to the impression given by news headlines, not all auctions failed and that investors rationally discriminated among bonds such that it was primarily those with low caps that experienced high failure rates. We further conclude that, in the absence of such caps, few if any, auctions would have failed.

Straying, stress, and potential for reproductive interactions between hatchery-produced and wild chum salmon (Oncorhynchus keta) in Southeast Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2017Approximately 1.5 billion juvenile hatchery-produced Pacific salmon (Oncorhynchus spp.) are currently released each year into Alaskan waters with goals of enhancing important fisheries and minimizing detrimental impacts on wild stocks. As the abundance of hatchery-produced salmon has increased, so have concerns about hatchery-origin strays entering wild systems and interactions with wild individuals on the spawning grounds. The influx of non-native strays and their associated fitness-related traits can reduce the resilience and productivity of recipient wild stocks, and is likely to be most deleterious when disparities in population sizes and heritable phenotypic characteristics between wild and hatchery fish exist. Thus, understanding the ecological and life-history mechanisms that regulate gene flow between hatchery and wild populations is crucial for conservation and management strategies in areas where hatchery enhancement is common. Currently, the ecology of strays on the spawning grounds and proximate physiological factors associated with straying (e.g., stress) are not well known. In this thesis I examine, 1) differences and similarities in several fitness-related phenotypic traits between naturally produced (presumably wild local individuals) and stray hatchery-produced chum salmon (Oncorhynchus keta) that died on the spawning grounds of Sawmill Creek, a small watershed near Juneau, Alaska, and 2) physiological differences in cortisol concentrations and the frequency of crystalline (vaterite) structure of otoliths between straying and correctly homing salmon. Hatchery-strays comprised 51.4% of the adult chum salmon that returned to Sawmill Creek during the 2015 spawning season. Hatchery males and females returned approximately seven days later, were consistently smaller (10% for males, 6% for females) in length, and younger on average than their naturally-produced counterparts. Additionally, hatchery-produced females lived fewer days on the spawning grounds during the spawning season, and retained a higher proportion of their eggs than did naturally produced females. To explore the potential role of stress on straying, I compared cortisol samples and frequency of vaterite formation in otoliths among groups of hatchery-produced fish that homed to the hatchery, hatchery-produced fish that strayed to Sawmill Creek, and naturally produced chum salmon that presumably homed to Sawmill Creek. No significant differences in cortisol concentration were found among any groups, though differences between the sexes were detected. Males of all groups had significantly lower cortisol concentrations than did females. No differences in frequency of vaterite occurrence were found between hatchery-stray and hatchery-home groups, though both hatchery groups were higher than naturally produced groups, which is consistent with findings of other studies. Thermal marking while at the hatchery during early development was not associated with vaterite formation, and no difference in frequency of vaterite formation was observed among groups of varying mark intensities. Overall, these results revealed there was ample opportunity for reproductive interactions between stray hatchery-produced and naturally produced chum salmon in Sawmill Creek during the 2015 spawning season, and consistent differences in phenotypic traits suggests the potential for gene flow to alter population-level phenotypic variation. However, despite the potential for gene flow, these results also reveal potential barriers to introgression and indicate that at least some of the presumed locally adapted traits of the natural stock remain intact. It remains unknown what the characteristics of the wild stock were prior to regional hatchery production and the extent to which the traits of this population are reflections of genetic differences between the hatchery and wild groups or phenotypic plasticity. To the extent these results are generalizable, observed differences in fitness-related traits between naturally produced and stray hatchery-produced fish may underlie the reduced reproductive success often reported in the literature. There were no differences in cortisol concentrations and frequency of vaterite occurrence between hatchery chum salmon that strayed and those that homed correctly, and the frequency of vaterite occurrence of hatchery chum salmon did not change as thermal mark intensity increased, which suggests that thermal marking may not directly alter homing ability of adults or development of juveniles, at least via otolith formation. Despite not having an effect on straying, the consistent findings of higher frequency of vaterite occurrence in hatchery-produced fish compared to naturally produced counterparts highlight the need for future work to uncover the causal underlying mechanisms and implications of vaterite on survival of the 1.5 billion salmon released each year in Alaskan waters