29,217 research outputs found
Geography-related sub-generic diversity within the Mediterranean trapdoor spider genus Nemesia (Araneae, Mygalomorphae, Nemesiidae)
Three different male and female super-specific types are distinguished according to variations in the morphology of the bulb and spermathecae within the genus Nemesia Audouin, 1826. Plotting the distributions of these sexual types on a map of the Mediterranean indicates the existence of geography-related sub-generic diversity in which the Nemesia fauna of the eastern Mediterranean differs markedly from that of the western Mediterranean. While the eastern Mediterranean Nemesia fauna is highly homogeneous, the fauna of the western Mediterranean is very diverse. The eastern and western Nemesia faunae appear to overlap in the central Mediterranean. Efforts to relate the specific bulb types to the particular types of spermathecae described here were only partly successful
Ground influence on airfoils
The question of ground influence on airplanes has recently attracted some attention in view of the claims made by certain designers that the landing speed of their airplanes is much decreased by an increase in lift coefficient due to the proximity of the ground in landing. The results of wind tunnel tests indicate that ground effect is not entirely beneficial. It decreases the landing speed and cushions the landing shock somewhat. However, it does so at the expense of an increased length of preliminary skimming over the ground. By decreasing the drag and increasing the lift, it lengthens the distance necessary for the airplane to travel before losing enough speed to land. On the other hand, its influence is helpful in taking off, especially in the case of flying boats with their low-lying wings. In the conventional tractor airplane, the height of the wings above the ground is determined largely by propeller clearance. However, a small low-speed airplane like the Pischoff and large low-speed commercial aircraft with engines between wings can utilize ground influence to good advantage
Traditional Athabascan Law Ways and Their Relationship to Contemporary Problems of "Bush Justice": Some Preliminary Observations on Structure and Function.
This paper is directed toward helping achieve a better understanding of traditional law ways among Alaska's Athabascan Indians and of the present state of the administration of law in the "bush"-village Alaska. An outgrowth of the 1970 Bush Justice Conference sponsored by the Alaska Judicial Council, the paper's primary purpose is to help facilitate establishment of more appropriate delivery and administration of legal services for ethnically distinct populations of Alaska.Introduction /
Traditional Athabascan Culture /
Social Organization and Leadership /
Values and Their Relationship to Law Ways /
Athabascan Law Ways — The Philosophical Basis /
The Pragmatic Structure and Operation of Athabascan Law Ways /
Major Offenses and Their Resolution (Adultery, Theft, Murder) /
Summary of Athabascan Law Ways /
Law Ways and Culture Change /
Past and Present Law Ways: Some Disjunctions /
Reference
Northern Eskimo Law Ways and Their Relationship to Contemporary Problems of "Bush Justice": Some Preliminary Observations on Structure and Function
This paper describes the how the basic values, personality, and culture of Northern (Inupiat) Eskimos contribute to attitudes toward conflict and their society’s capacity to resolve conflict. The paper analyzes the influence of Anglo-American agents of change on that capacity and, especially, the legal system and procedures that developed in the post-contact use of the village council to resolve disputes. It discusses the formal intervention of state law through the magisterial system and its interaction with Eskimo law ways that the village council encouraged. A comparison of village councils and magistrate courts points out the apparent success of the councils due to their unique fit with Eskimo values and expectations. Finally, shortcomings of .the current magistrate system are analyzed with recommendations for policy adaptations.Introduction /
The Genesis of Eskimo Law Ways in Aboriginal Conflict Resolution /
Aboriginal Eskimo Conflict Resolution: An Overview /
American Intervention and Eskimo Law Ways /
The Village Council /
The Contemporary Period: The Magistrate System /
Implications for Bush Justice /
Conclusion /
Bibliograph
Symmetry breaking in general relativity
Bifurcation theory is used to analyze the space of solutions of Einstein's equations near a spacetime with symmetries. The methods developed here allow one to describe precisely how the symmetry is broken as one branches from a highly symmetric spacetime to nearby spacetimes with fewer symmetries, and finally to a generic solution with no symmetries. This phenomenon of symmetry breaking is associated with the fact that near symmetric solutions the space of solutions of Einstein's equations does not form a smooth manifold but rather has a conical structure. The geometric picture associated with this conical structure enables one to understand the breaking of symmetries. Although the results are described for pure gravity, they may be extended to classes of fields coupled to gravity, such as gauge theories. Since most of the known solutions of Einstein's equations have Killing symmetries, the study of how these symmetries are broken by small perturbations takes on considerable theoretical significance
Constraint-consistent Runge-Kutta methods for one-dimensional incompressible multiphase flow
New time integration methods are proposed for simulating incompressible
multiphase flow in pipelines described by the one-dimensional two-fluid model.
The methodology is based on 'half-explicit' Runge-Kutta methods, being explicit
for the mass and momentum equations and implicit for the volume constraint.
These half-explicit methods are constraint-consistent, i.e., they satisfy the
hidden constraints of the two-fluid model, namely the volumetric flow
(incompressibility) constraint and the Poisson equation for the pressure. A
novel analysis shows that these hidden constraints are present in the
continuous, semi-discrete, and fully discrete equations.
Next to constraint-consistency, the new methods are conservative: the
original mass and momentum equations are solved, and the proper shock
conditions are satisfied; efficient: the implicit constraint is rewritten into
a pressure Poisson equation, and the time step for the explicit part is
restricted by a CFL condition based on the convective wave speeds; and
accurate: achieving high order temporal accuracy for all solution components
(masses, velocities, and pressure). High-order accuracy is obtained by
constructing a new third order Runge-Kutta method that satisfies the additional
order conditions arising from the presence of the constraint in combination
with time-dependent boundary conditions.
Two test cases (Kelvin-Helmholtz instabilities in a pipeline and liquid
sloshing in a cylindrical tank) show that for time-independent boundary
conditions the half-explicit formulation with a classic fourth-order
Runge-Kutta method accurately integrates the two-fluid model equations in time
while preserving all constraints. A third test case (ramp-up of gas production
in a multiphase pipeline) shows that our new third order method is preferred
for cases featuring time-dependent boundary conditions
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