Slice Stretching Effects for Maximal Slicing of a Schwarzschild Black Hole

Slice stretching effects such as slice sucking and slice wrapping arise when foliating the extended Schwarzschild spacetime with maximal slices. For arbitrary spatial coordinates these effects can be quantified in the context of boundary conditions where the lapse arises as a linear combination of odd and even lapse. Favorable boundary conditions are then derived which make the overall slice stretching occur late in numerical simulations. Allowing the lapse to become negative, this requirement leads to lapse functions which approach at late times the odd lapse corresponding to the static Schwarzschild metric. Demanding in addition that a numerically favorable lapse remains non-negative, as result the average of odd and even lapse is obtained. At late times the lapse with zero gradient at the puncture arising for the puncture evolution is precisely of this form. Finally, analytic arguments are given on how slice stretching effects can be avoided. Here the excision technique and the working mechanism of the shift function are studied in detail.Comment: 16 pages, 4 figures, revised version including a study on how slice stretching can be avoided by using excision and/or shift

Suppression of thermally activated escape by heating

The problem of thermally activated escape over a potential barrier is solved by means of path integrals for one-dimensional reaction dynamics with very general time dependences. For a suitably chosen but still quite simple static potential landscape, the net escape rate may be substantially reduced by temporally increasing the temperature above its unperturbed constant level.Comment: 4 pages, 2 figure

Interplay of frequency-synchronization with noise: current resonances, giant diffusion and diffusion-crests

We elucidate how the presence of noise may significantly interact with the synchronization mechanism of systems exhibiting frequency-locking. The response of these systems exhibits a rich variety of behaviors, such as resonances and anti-resonances which can be controlled by the intensity of noise. The transition between different locked regimes provokes the development of a multiple enhancement of the effective diffusion. This diffusion behavior is accompanied by a crest-like peak-splitting cascade when the distribution of the lockings is self-similar, as it occurs in periodic systems that are able to exhibit a Devil's staircase sequence of frequency-lockings.Comment: 7 pages, 6 figures, epl.cls. Accepted for publication in Europhysics Letter

Slice Stretching at the Event Horizon when Geodesically Slicing the Schwarzschild Spacetime with Excision

Slice-stretching effects are discussed as they arise at the event horizon when geodesically slicing the extended Schwarzschild black-hole spacetime while using singularity excision. In particular, for Novikov and isotropic spatial coordinates the outward movement of the event horizon (``slice sucking'') and the unbounded growth there of the radial metric component (``slice wrapping'') are analyzed. For the overall slice stretching, very similar late time behavior is found when comparing with maximal slicing. Thus, the intuitive argument that attributes slice stretching to singularity avoidance is incorrect.Comment: 5 pages, 2 figures, published version including minor amendments suggested by the refere

Rolling and sliding of a nanorod between two planes: Tribological regimes and control of friction

The motion of a cylindrical crystalline nanoparticle sandwiched between two crystalline planes, one stationary and the other pulled at a constant velocity and pressed down by a normal load, is considered theoretically using a planar model. The results of our model calculations show that, depending on load and velocity, the nanoparticle can be either rolling or sliding. At sufficiently high normal loads, several sliding states characterized by different friction forces can coexist, corresponding to different orientations of the nanoparticle, and allowing one to have low or high friction at the same pulling velocity and normal load.Comment: 5 figure

Building Networks from the Outside In: Japanese NGOs and the Kyoto Climate Change Conference

This chapter looks at changing patterns of Japanese environmental NGOs active in the international sphere and argues that in the early 1990s changes in the international realm provided activists new opportunities and frameworks that allowed them to overcome steep domestic organizational barriers and participate in new activities focused on global environmental issues. Building upon recent work done by sociologists and political scientists, it outlines how international opportunity, transational diffusion, and international socialization of state actors have encouraged the growth of NGOs and new forms of social action

Up to No Good? Recent Critics and Critiques of NGOs

This chapter examines the various criticisms of NGOs and calls attention to both the validity of these criticisms as well as contradictions and inconsistencies. Critics of NGOs can be found across the political spectrum, ranging from rightists who object to NGOs in principle to leftists who criticize NGOs for their failures to advance a progressive agenda or for deferring to government preferences. Despite their ideological differences and ultimate objectives, however, critics are remarkably similar in terms of many of their main complaints about NGOs. During the course of the 1990s and early 2000s, a clearly defined set of critiques of NGOs have appeared focusing on: (1) their performance and actual effectiveness, (2) accountability issues, (3) issues of autonomy, (4) commercialization, and (5) ideological and/or political interpretations of their rising influence. Now appearing with increasing regularity and frequency in the academic literature, the policy world, and the popular press, these critiques have been directed towards not only NGOs working in the area of conflict resolution (the main subject of this book), but to all NGOs: advocacy NGOs, service NGOs, and NGOs working in various issues areas. In order to provide both a comprehensive and a refined examination of the debate, this chapter will present the major criticisms of NGOs in general, while distinguishing critiques as they apply to various types of NGOs

Circular 78

Historically, sales of exotic meats have been limited only by supply. As supply has increased in recent years, national and international exotic game markets have grown rapidly. In the United States, growth has occurred primarily in the restaurant section, although over-the-counter sales have also increased. The Alaskan reindeer industry is exploring the potential of expanding its meat sales as well as antler sales. Meat production increased from 320,000 pounds in 1987 to 432,000 pounds in 1988. This production increase is reflected in a 27 percent increase in dollar value (Alaska Crop and Livestock Reporting Service, 1989). Under current management procedures, potential meat production has been estimated at 500,000 pounds (Pearson and Lewis, 1988). Any future market expansion is likely to occur in urban Alaska and in areas outside the state (Jones, 1988)

Hexagons become second if symmetry is broken

Pattern formation on the free surface of a magnetic fluid subjected to a magnetic field is investigated experimentally. By tilting the magnetic field the symmetry can be broken in a controllable manner. When increasing the amplitude of the tilted field, the flat surface gives way to liquid ridges. A further increase results in a hysteretic transition to a pattern of stretched hexagons. The instabilities are detected by means of a linear array of magnetic hall sensors and compared with theoretical predictions.Comment: accepted for publication by Physical Review E/Rapid Communicatio

Quantum Ratchets at High Temperatures

Using the continued-fraction method we solve the Caldeira-Leggett master equation in the phase-space (Wigner) representation to study Quantum ratchets. Broken spatial symmetry, irreversibility and periodic forcing allows for a net current in these systems. We calculate this current as a function of the force under adiabatic conditions. Starting from the classical limit we make the system quantal. In the quantum regime tunnel events and over-barrier wave reflection phenomena modify the classical result. Finally, using the phase-space formalism we give some insights about the decoherence in these systems.Comment: submitted to Physia E (proceedings of conference "Frontiers of Quantum and Mesoscopic Thermodynamics", Prague 26-29 July 2004