Showing 581 - 590 of 733 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.
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.
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.
Tainted resurrection: metal pollution is linked with reduced hatching and high juvenile mortality inDaphniaegg banks
Date: 2015-05-01
Creator: Mary A. Rogalski
Access: Open access
Messenger RNA transport in the opportunistic fungal pathogen Candida albicans
Date: 2017-12-01
Creator: Anne E. McBride
Access: Open access
- Candida albicans, a common commensal fungus, can cause disease in immunocompromised hosts ranging from mild mucosal infections to severe bloodstream infections with high mortality rates. The ability of C. albicans cells to switch between a budding yeast form and an elongated hyphal form is linked to pathogenicity in animal models. Hyphal-specific proteins such as cell-surface adhesins and secreted hydrolases facilitate tissue invasion and host cell damage, but the specific mechanisms leading to asymmetric protein localization in hyphae remain poorly understood. In many eukaryotes, directional cytoplasmic transport of messenger RNAs that encode asymmetrically localized proteins allows efficient local translation at the site of protein function. Over the past two decades, detailed mechanisms for polarized mRNA transport have been elucidated in the budding yeast Saccharomyces cerevisiae and the filamentous fungus Ustilago maydis. This review highlights recent studies of RNA-binding proteins in C. albicans that have revealed intriguing similarities to and differences from known fungal mRNA transport systems. I also discuss outstanding questions that will need to be answered to reach an in-depth understanding of C. albicans mRNA transport mechanisms and the roles of asymmetric mRNA localization in polarized growth, hyphal function, and virulence of this opportunistic pathogen.
Convergence of successive approximation methods with parameter target sets
Date: 2005-01-01
Creator: A.B. Levy
Access: Open access
Nonlinear localized modes in two-dimensional hexagonally-packed magnetic lattices
Date: 2021-04-01
Creator: Christopher Chong, Yifan Wang, Donovan Maréchal, Efstathios G. Charalampidis, Miguel, Molerón, Alejandro J. Martínez
Access: Open access
- We conduct an extensive study of nonlinear localized modes (NLMs), which are temporally periodic and spatially localized structures, in a two-dimensional array of repelling magnets. In our experiments, we arrange a lattice in a hexagonal configuration with a light-mass defect, and we harmonically drive the center of the chain with a tunable excitation frequency, amplitude, and angle. We use a damped, driven variant of a vector Fermi-Pasta-Ulam-Tsingou lattice to model our experimental setup. Despite the idealized nature of this model, we obtain good qualitative agreement between theory and experiments for a variety of dynamical behaviors. We find that the spatial decay is direction-dependent and that drive amplitudes along fundamental displacement axes lead to nonlinear resonant peaks in frequency continuations that are similar to those that occur in one-dimensional damped, driven lattices. However, we observe numerically that driving along other directions results in asymmetric NLMs that bifurcate from the main solution branch, which consists of symmetric NLMs. We also demonstrate both experimentally and numerically that solutions that appear to be time-quasiperiodic bifurcate from the branch of symmetric time-periodic NLMs.
Systematic ENSO-driven nutrient variability recorded by central equatorial Pacific corals
Date: 2013-08-16
Creator: Michèle LaVigne, Intan S. Nurhati, Kim M. Cobb, Helen V. McGregor, Daniel, Sinclair, Robert M. Sherrell
Access: Open access
- Variations in ocean productivity are driven largely by nutrient supply to the photic zone, but temporal records of nutrient variability are sparse. Here we show scleractinian coral P/Ca proxy records of variations in phosphate concentrations during El Niño Southern Oscillation (ENSO) cycles in the central equatorial Pacific. Covarying P/Ca records in Porites corals from Christmas and Fanning Islands show a regional ∼40% decrease during the upwelling relaxation of the 1997-1998 El Niño, consistent with less frequent nutrient measurements from this area. Similar ∼35-45% skeletal P/Ca decreases occur during the 1982-1983 and 1986-1987 El Niño events, which predate satellite color and regional nutrient measurements. After each El Niño event, nutrient increases lag temperature recovery by 4-12 months, likely reflecting uptake by massive phytoplankton blooms that followed resumption of upwelling. The results support the utility of coral P/Ca to probe the mechanisms linking ENSO, equatorial upwelling, and carbon cycling in the past. © 2013. American Geophysical Union. All Rights Reserved.