Three ages of Venus

A central question for any planet is the age of its surface. Based on comparative planetological arguments, Venus should be as young and active as the Earth (Wood and Francis). The detection of probable impact craters in the Venera radar images provides a tool for estimating the age of the surface of Venus. Assuming somewhat different crater production rates, Bazilevskiy et al. derived an age of 1 + or - 0.5 billion years, and Schaber et al. and Wood and Francis estimated an age of 200 to 400 million years. The known impact craters are not randomly distributed, however, thus some area must be older and others younger than this average age. Ages were derived for major geologic units on Venus using the Soviet catalog of impact craters (Bazilevskiy et al.), and the most accessible geologic unit map (Bazilevskiy). The crater counts are presented for (diameters greater than 20 km), areas, and crater densities for the 7 terrain units and coronae. The procedure for examining the distribution of craters is superior to the purely statistical approaches of Bazilevskiy et al. and Plaut and Arvidson because the bins are larger (average size 16 x 10(6) sq km) and geologically significant. Crater densities define three distinct groups: relatively heavily cratered (Lakshmi, mountain belts), moderately cratered (smooth and rolling plains, ridge belts, and tesserae), and essentially uncratered (coronae and domed uplands). Following Schaber et al., Grieve's terrestrial cratering rate of 5.4 + or - 2.7 craters greater than 20 km/10(9) yrs/10(6) sq km was used to calculate ages for the geologic units on Venus. To improve statistics, the data was aggregated into the three crater density groups, deriving the ages. For convenience, the three similar age groups are given informal time stratigraphic unit names, from youngest to oldest: Ulfrunian, Sednaian, Lakshmian

Risk and Return in an Electronic Market: An Examination of Investments in Online Rare Coin Auctions Over a Short Horizon

Collectables are often considered as an alternative to stocks for investing. Technological advancements have facilitated collectible investment, allowing information to be transferred worldwide between millions of investors in electronic markets such as online auctions. This research examines the behaviors of these electronic market investors, especially as they compare to traditional stock market investors. This research examines risk and returns in 13,263 auctions involving 755 distinct rare coins collected over 128 days. While stock investors typically ignore risk that can be eliminated through diversification, this research finds evidence that collectible investors who trade in online auctions do not consider diversification over short horizons, but rather they their bid levels include diversifiable risk adjustments, supporting a contention that typical online auction collectible investors view collectibles as stand-alone assets, differing from typical the stock investor’s perspective that diversifiable risk can be ignored when an investment is added to a collection or portfolio

Alien Registration- Wood, Charles A. (Danforth, Washington County)

https://digitalmaine.com/alien_docs/1903/thumbnail.jp

Trust and Experience in Online Auctions

This paper aims to shed light on the complexities and difficulties in predicting the effects of trust and the experience of online auction participants on bid levels in online auctions. To provide some insights into learning by bidders, a field study was conducted first to examine auction and bidder characteristics from eBay auctions of rare coins. We proposed that such learning is partly because of institutional-based trust. Data were then gathered from 453 participants in an online experiment and survey, and a structural equation model was used to analyze the results. This paper reveals that experience has a nonmonotonic effect on the levels of online auction bids. Contrary to previous research on traditional auctions, as online auction bidders gain more experience, their level of institutional-based trust increases and leads to higher bid levels. Data also show that both a bidder’s selling and bidding experiences increase bid levels, with the selling experience having a somewhat stronger effect. This paper offers an in-depth study that examines the effects of experience and learning and bid levels in online auctions. We postulate this learning is because of institutional-based trust. Although personal trust in sellers has received a significant amount of research attention, this paper addresses an important gap in the literature by focusing on institutional-based trust

Running up the Bid: Modeling Seller Opportunism in Internet Auctions

Although the Internet is great for transferring information, transactions in Internet auctions have a greater information asymmetry than corresponding transactions in traditional environments because current auction market mechanisms allow the seller to remain anonymous and to easily change identities. Buyers must rely on the seller\u27s description of a product and ability to deliver the product as promised. Internet auction environments make opportunistic behavior more attractive to sellers because the chance of detection and punishment is decreased. In this research, we examine auction data to see the effect of opportunism in the online auction environment

Technology\u27s Effect on Firm Size: Manufacturing vs. Service

We develop theory that describes how increased IT investment motivates different actions within different types of industries. We contend that manufacturing firms tend to have revenue that is firm dependent, regardless of the number of employees and thus use IT to reduce costs by reducing firm size, as stated in previous theory. However, retail and service firms tend to have revenue that is tied to the number of employees and use IT to increase firm size in order to allow greater revenue. Using 629 yearly observations from 37 industries from 1985 to 2005, we find that IT investment precedes size decreases with manufacturing firms and size increases with retail and service firms. Further, impulse response functions indicate that differences in firm size differences following IT investment eventually vanish, and non- IT-investing firms eventually achieve the same firm size after several years, indicating that IT allows firms to be more responsive

Report of the panel on volcanology, section 4

Two primary goals are identified as focal to NASA's research efforts in volcanology during the 1990s: to understand the eruption of lavas, gases, and aerosols from volcanoes, the dispersal of these materials on the Earth's surface and through the atmosphere, and the effects of these eruptions on the climate and environment; and to understand the physical processes that lead to the initiation of volcanic activity, that influence the styles of volcanic eruptions, and that dictate the morphology and evolution of volcanic landforms. Strategy and data requirements as well as research efforts are discussed

Impact Craters on Titan? Cassini RADAR View

Titan is a planet-size (diameter of 5,150 km) satellite of Saturn that is currently being investigated by the Cassini spacecraft. Thus far only one flyby (Oct. 26, 2004; Ta) has occurred when radar images were obtained. In February, 2005, and approximately 20 more times in the next four years, additional radar swaths will be acquired. Each full swath images about 1% of Titan s surface at 13.78 GHz (Ku-band) with a maximum resolution of 400 m. The Ta radar pass [1] demonstrated that Titan has a solid surface with multiple types of landforms. However, there is no compelling detection of impact craters in this first radar swath. Dione, Tethys and other satellites of Saturn are intensely cratered, there is no way that Titan could have escaped a similar impact cratering past; thus there must be ongoing dynamic surface processes that erase impact craters (and other landforms) on Titan. The surface of Titan must be very young and the resurfacing rate must be significantly higher than the impact cratering rate

An Immunochemical Study of the Combining Sites of the Second Lectin Isolated from \u3ci\u3eBandeiraea simplicifolia\u3c/i\u3e (BS II)

Two lectins with different binding specificities have been isolated from extracts of seeds of Bandeiraea simplicifolia. The first, Bandeiraea lectin I [11] was specific for terminal non-reducing αDGalactosyl residues. It reacted with B substances from human ovarian cysts and with several galactomannans to form precipitin lines in agar gels. Polysaccharides with terminal αDGalactosyl residues, such as larch galactan, did not react. The lectin agglutinated B erythrocytes strongly but also reacted to a lower titre with A1 and very weakly with A2 erythrocytes [15, 28] indicating that terminal non-reducing αDGalNAc [24] can be accommodated in the-site to some extent. Recently, it was shown that B. simplicifolia lectin I (BS I) consists of five isolectins each of which is a tetrameric glycoprotein composed of A and B subunits; the A subunits are specific for αDGalNAc, the B subunits for αDGal [30]. The second lectin, Bandeiraea lectin II (BS II), isolated by affinity chromatography on chitin [13], is a glycoprotein (molecular weight 113,000) of four subunits of molecular weight 30,000. It does not agglutinate A, B or O erythrocytes. Quantitative precipitin assays showed it to react better with BSA conjugated to p-azophenyl αDGalNAc than with the β compound. In inhibition studies, the unusual observation was made that N,N’-diacetylchitobiose (DGlcNAcβ1 → 4DGlcNAc) and pNO2 phenyl αDGalNAc were highly active; methyl αDGalNAc was only one half as active but was eight times more active than methyl βDGlcNAc