179,676 research outputs found
The early role of nitric oxide in evolution
Nitric oxide (NO), which today serves many different purposes in regulating complex cellular functions, must have played a crucial role in the early stages of the evolution of life. The formation of NO may have been a critical defence mechanism for primitive microorganisms at a time when life faced the problem of rising atmospheric levels of ozone (03) formed upon photolysis of oxygen (Oz), which occurred shortly after the development of respiration in cyanobacteria. The production of NO by organisms would have allowed neutralization of toxic 03 by chemical reaction outside the cell, thus acting as a protective mechanism against oxidative destruction, allowing evolutionary advantage. Later, NO production might have allowed the control of reactive OZ species within cells before the development of specific electron-accepting enzymes. The pathway of NO formation was then consequently developed further to serve other useful functions. Although mammalian cells produce NO from L-arginine, the origin of this ability might have arisen from the essential process of either nitrification or denitrification in prokaryotic cells
Georgia's Corporate Taxes: Should the Corporate Income Tax be Repealed?
An analysis prepared for the Georgia Public Policy Foundation
French Canadian Participation in the War of 1812: A Social Study of the Voltiguers Canadians
During the War of 1812, the participation of French Canadians in colonial militia units such as the Voltigeurs Canadiens was of great importance for the defence of Lower Canada. The colony’s lack of regular British toops combined with threats of American invasion rendered crucial to the mobilization of the local populace, most of which was of French descent. Although lacking the discipline and structure of British regular soldiers. Lower-Canadian militiamen were able to neutralize numerous American invasion attempts. Altogether, this impressive participation in the war effort helped redefine the military character of French Canadians. It also dissipated the British authorities’ fears that French Canadians were disloyal subjects. This study analyses the military organization of the Voltigeurs Canadiens to demonstrate the importance of French Canadian participation in the war, especially in Lower Canada, their military campaigns and how the Voltigeurs’ victories became the pride of all French Canada
Competition between finite-size effects and dipole-dipole interactions in few-atom systems
In this paper, we study the competition between finite-size effects (i.e.
discernibility of particles) and dipole-dipole interactions in few-atom systems
coupled to the electromagnetic field in vacuum. We consider two hallmarks of
cooperative effects, superradiance and subradiance, and compute for each the
rate of energy radiated by the atoms and the coherence of the atomic state
during the time evolution. We adopt a statistical approach in order to extract
the typical behavior of the atomic dynamics and average over random atomic
distributions in spherical containers with prescribed with the
radiation wavenumber and the average interatomic distance. Our approach
allows us to highlight the tradeoff between finite-size effects and
dipole-dipole interactions in superradiance/subradiance. In particular, we show
the existence of an optimal value of for which the superradiant
intensity and coherence pulses are the less affected by dephasing effects
induced by dipole-dipole interactions and finite-size effects.Comment: 11 pages, 11 figure
Abstraction and registration: conceptual innovations and supply effects in Prussian and British Copyright (1820-50)
It is one of the orthodoxies of modern copyright law that the enjoyment and the exercise of the rights granted “shall not be subject to any formality” (Berne Convention 1886, Berlin revision 1908, Art.4), such as a registration requirement. In this article, we trace the origins of this provision to a conceptual shift that took place during the early 1800s. Specific regulations of the book trade were superseded by the protection of all instantiations (such as performances, translations and adaptations) of abstract authored work. For two seminal copyright acts of the period, the Prussian Act of 1837 and the UK Act of 1842, we show there was considerable concern about the economic implications of this new justificatory paradigm, reflected in a period of experimentation with sophisticated registration requirements. We indicate market responses to these requirements and plea for a reconsideration of “formalities” as redressing justificatory problems of copyright in the digital environment
Summary results of the DOE flywheel development effort
The technology and applications evaluation task focuses on defining performance and cost requirements for flywheels in the various areas of application. To date the DOE program has focused on automotive applications. The composite materials effort entails the testing of new commercial composites to determine their engineering properties. The rotor and containment development work uses data from these program elements to design and fabricate flywheels. The flywheels are then tested at the Oak Ridge Flywheel Evaluation Laboratory and their performance is evaluated to indicate possible areas for improvement. Once a rotor has been fully developed it is transferred to the private sector
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