The Effect of Diffusion on the Particle Spectra in Pulsar Wind Nebulae

A possible way to calculate particle spectra as a function of position in pulsar wind nebulae is to solve a Fokker-Planck transport equation. This paper presents numerical solutions to the transport equation with the processes of convection, diffusion, adiabatic losses, and synchrotron radiation included. In the first part of the paper the steady-state version of the transport equation is solved as a function of position and energy. This is done to distinguish the various effects of the aforementioned processes on the solutions to the transport equation. The second part of the paper deals with a time-dependent solution to the transport equation, specifically taking into account the effect of a moving outer boundary. The paper highlights the fact that diffusion can play a significant role in reducing the amount of synchrotron losses, leading to a modification in the expected particle spectra. These modified spectra can explain the change in the photon index of the synchrotron emission as a function of position. The solutions presented in this paper are not limited to pulsar wind nebulae, but can be applied to any similar central source system, e.g. globular clusters

Kung’s Theory of Paradigm Shifts in Church History: An Evaluation

The theory of paradigms is a broad subject that has been discussed extensively from various perspectives including science, religion and history. Its strengths and weaknesses have been aptly considered. This research article seeks to investigate the extent of the theory\u27s applicability to church history. The question that we wish to address is: To what extent, is this theory of paradigms applicable in explaining the changes that have taken place through the history of Christianity

Kung’s Theory of Paradigm Shifts in Church History: An Evaluation

The theory of paradigms is a broad subject that has been discussed extensively from various perspectives including science, religion and history. Its strengths and weaknesses have been aptly considered. This research article seeks to investigate the extent of the theory\u27s applicability to church history. The question that we wish to address is: To what extent, is this theory of paradigms applicable in explaining the changes that have taken place through the history of Christianity

The Principle of Strain Reconstruction Tomography: Determination of Quench Strain Distribution from Diffraction Measurements

Evaluation of residual elastic strain within the bulk of engineering components or natural objects is a challenging task, since in general it requires mapping a six-component tensor quantity in three dimensions. A further challenge concerns the interpretation of finite resolution data in a way that is commensurate and non-contradictory with respect to continuum deformation models. A practical solution for this problem, if it is ever to be found, must include efficient measurement interpretation and data reduction techniques. In the present note we describe the principle of strain tomography by high energy X-ray diffraction, i.e. of reconstruction of the higher dimensional distribution of strain within an object from reduced dimension measurements; and illustrate the application of this principle to a simple case of reconstruction of an axisymmetric residual strain state induced in a cylindrical sample by quenching. The underlying principle of the analysis method presented in this paper can be readily generalised to more complex situations.Comment: 10 pages, 6 figure

Being a church today in South Africa's Liberal Democracy

Peer reviewedThe emergence of a liberal democracy in South Africa confronted South African churches with a new environment. Until 1994, churches were mostly involved (on both sides) in the struggle against Apartheid. This situation resulted in a church model which can be defined as institutionalism. Churches acted as megainstitutions over and against the state and confronted or supported the state in decisions taken by synods, councils and ecumenical bodies. After 1994 the churches gradually lost their political relevance and subsided into a model which can be defined as spiritualism. Spiritualism emphasises the spiritual nature of Christianity to such an extent that the social task of the church becomes obsolete. This article endeavours to formulate a model which can overcome this problem and the article proposes the model of the “church as servant”. I then describe the role of the serving church in South Africa under the following rubrics: the church as a holy community, the church as an exemplary community, the church as a preaching community and the church as a worshipping community.Research Institute for Theology and Religio

Die kerk in 'n nuwe konteks

In 1953 the well-known church historian, Latourette, was very optimistic about the twentieth century's situation of Christianity. He described mo­dern Christianity as a potent force in the contemporary world. But what are the future prospects of Christianity, especially in view of the current apparent decline of the influence of the church, virtually in all the major ecclesiological traditions? Will Latourette's arguments still be valid in the next two decades