Showing 1721 - 1730 of 2040 Items
2018 Table of static dipole polarizabilities of the neutral elements in the periodic table*
Date: 2019-06-18
Creator: Peter Schwerdtfeger
Jeffrey K. Nagle
Access: Open access
- A 2018 update of the most accurate calculated and experimental static dipole polarizabilities of the neutral atoms in the Periodic Table from nuclear charge Z = 1 to 120 is given. Periodic trends are analyzed and discussed.
Estimating the Impact of Ride-Hailing App Company Entry on Public Transportation Use in Major US Urban Areas
Date: 2019-01-01
Creator: Erik Nelson
Nicole Sadowsky
Access: Open access
- Since 2011, the private ride-hailing (RH) app companies Uber and Lyft have expanded into more and more US urban areas. We use a dynamic entry event study to examine the impact of Uber and Lyft's entry on public transportation (PT) use in the United States' largest urban areas. In most cases, entry into urban areas was staggered: Uber entered first, followed several months later by Lyft. We generally find that PT use increased in the representative urban area, all else equal, immediately following first RH app company entry. However, this spike in PT use largely disappeared following the entry of the second RH app company. Slightly different RH app company-PT use relationships emerge when we estimate the PT use model over various subsets of urban areas and PT modes.
The likelihood of local allies free-riding: Testing economic theories of alliances in US counterinsurgency interventions
Date: 2017-09-01
Creator: Barbara Elias
Access: Open access
- In counterinsurgency interventions, free-riding by small, local allies is persistent. Yet, the literature on free-riding by small allies is largely limited to conventional multilateral partnerships, such as the North Atlantic Treaty Organization, neglecting other types of asymmetric alliances. Using new data containing 144 US requests to local allies in Vietnam, Iraq and Afghanistan, this article tests the logic of economic theories of alliances in counterinsurgency interventions. I find even when small allies are explicitly asked to contribute to alliance-wide security goods, they are likely to free-ride almost half the time (45%), and the likelihood of free-riding is dependent on whether local allies can be excluded by larger allies. This conclusion upholds the logic of economic models, since shared defense goods that exclude local allies fail to meet the criteria of public goods.
Erratum: Stochastic boolean satisfiability (Journal of Automated Reasoning (2001) 27 (251-296))
Date: 2002-01-01
Creator: Michael L. Littman
Stephen M. Majercik
Toniann Pitassi
Access: Open access
Role of iron and organic carbon in mass-specific light absorption by particulate matter from louisiana coastal waters
Date: 2012-01-01
Creator: Margaret L. Estapa
Emmanuel Boss
Lawrence M. Mayer
Collin S. Roesler
Access: Open access
- We investigated the influences of organic content and mineralogical composition on light absorption by mostly mineral suspended particles in aquatic and coastal marine systems. Mass-specific absorption spectra of suspended particles and surface sediments from coastal Louisiana and the lower Mississippi and Atchafalaya rivers were measured with a centered sample-mount integrating sphere and analyzed in conjunction with organic carbon (OC), hydrochloric acid- (HCl-) extractable iron, and dithionite-extractable iron contents. Compositions and absorption properties were comparable to published values for similar particles. Dithionite-extractable iron was strongly correlated with absorption at ultraviolet (UV) and blue wavelengths, while OC and HCl-extractable iron were weakly but positively correlated. Oxidative removal of OC from sediments caused small and variable changes in absorption, while dithionite extraction of iron oxides strongly reduced absorption. Shoulders in the absorption spectra corresponded to absorption bands of iron oxide minerals, and their intensities were well correlated to dithionite-extractable iron contents of the samples. These findings support a primary role for iron oxide and hydroxide minerals in the mass-specific absorption of mostly inorganic particles from the terrestrially influenced coast of Louisiana. Riverine particles had higher dithionite-extractable iron contents and iron oxide- specific absorption features than did marine particles, consistent with current knowledge regarding differential transport of particulate iron oxides and hydroxides through estuarine salinity gradients and reductive alteration of these oxide phases on the Louisiana shelf. The quantifiable dependence of UV absorption features on iron oxide content suggests that, under certain conditions, in situ hyperspectral absorption measurements could be designed to monitor water-column iron mineral transport and transformation. © 2012, by the Association for the Sciences of Limnology and Oceanography, Inc.
Accounting for creativity: Lessons from the economic history of intellectual property and innovation
Date: 2020-01-01
Creator: B. Zorina Khan
Access: Open access
- Social progress depends on the realization of inventive ideas, and economic history provides valuable lessons about creativity in technology and culture. The empirical study of over one hundred thousand innovative individuals who obtained patents, copyrights, and prizes, sheds light on the relationship between institutions, incentives, and transformative ideas and expression, over the past two centuries. The European growth model assumed useful knowledge was scarce, and top-down administered innovation systems offered rights and rewards to “exclusive” groups. By contrast, American policies regarded creativity as widely distributed in the general population, and further promoted “inclusive” market-oriented mechanisms that fostered diversity in ideas and outcomes. The evidence suggests that property rights in patents facilitated markets in ideas, and ensured that returns were aligned with productivity and market demand. Whereas, such administered systems as innovation prizes and publisher’s copyrights in the “creative industries” benefited the few rather than overall social welfare.
Statement by Douglas Chapman collected by Erika Bjorum on August 9, 2023
Date: 2023-08-09
Creator: Douglas Chapman
Access: Open access
- This statement was given privately.
Waterborne cues from crabs induce thicker skeletons, smaller gonads and size-specific changes in growth rate in sea urchins
Date: 2009-04-01
Creator: Rebecca Selden
Amy S. Johnson
Olaf Ellers
Access: Open access
- Indirect predator-induced effects on growth, morphology and reproduction have been extensively studied in marine invertebrates but usually without consideration of size-specific effects and not at all in post-metamorphic echinoids. Urchins are an unusually good system, in which, to study size effects because individuals of various ages within one species span four orders of magnitude in weight while retaining a nearly isometric morphology. We tracked growth of urchins, Strongylocentrotus droebachiensis (0.013-161.385 g), in the presence or absence of waterborne cues from predatory Jonah crabs, Cancer borealis. We ran experiments at ambient temperatures, once for 4 weeks during summer and again, with a second set of urchins, for 22 weeks over winter. We used a scaled, cube-root transformation of weight for measuring size more precisely and for equalizing variance across sizes. Growth rate of the smallest urchins (summer: diameter; winter: diameter) decreased by 40-42% in response to crab cues. In contrast, growth rate of larger urchins was unaffected in the summer and increased in response to crab scent by 7% in the winter. At the end of the 22-week experiment, additional gonadal and skeletal variables were measured. Cue-exposed urchins developed heavier, thicker skeletons and smaller gonads, but no differences in spine length or jaw size. The differences depended on urchin size, suggesting that there are size-specific shifts in gonadal and somatic investment in urchins.
Peatlands as a model ecosystem of soil carbon dynamics: Reply to Comment on "peatlands and their role in the global carbon cycle"
Date: 2012-01-01
Creator: Zicheng Yu
D. W. Beilman
S. Frolking
G. M. MacDonald
N. T., Roulet
P. Camill
D. J. Charman
Access: Open access