Afrikaanse gereformeerde kerke in Suid-Afrika en ekologie

The Afrikaans reformed churches in South Africa and ecologyA plethora of studies describing the scope of destruction of the ecology has been published since the 1970s. Lately, Christianity has been accused of being partly responsible for this. Despite the fact that South Africa is one of the ten largest polluters in the world, local religious communities only started voicing an opinion on this matter during the late 1980s. Only in the early 1990s did the reformed churches in South Africa begin some soul searching and the matter was placed on the agenda. The question raised in this article is: What contribution have the reformed churches in South Africa made towards averting this crisis? The author considers criticism levelled at Christianity in general and at the reformed churches in particular; the status of ecology in the dogma of these churches; the contributions made by theologians, and important decisions taken by synods. Three phases were noted in the way the synods dealt with the issue: Firstly, it was acknowledged that a crisis exists and that the church is neither innocent nor can she remain indifferent; secondly, theologians reflected deeply on this matter and offered a refined formulation of a creed to articulate the relationship between God, creation and man. Lastly, practical guidelines were proposed. It was found that the reformed churches have contributed significantly towards alerting people to the fact that the crisis also has religious implications; that the faithful should obey Biblical guidelines; and that there are implications for life, liturgy, education, and theological training.

Regularization, renormalization and consistency conditions in QED with x-electric potential steps

The present article is an important addition to the nonperturbative formulation of QED with x-steps presented by Gavrilov and Gitman (Phys. Rev. D. 93:045002, 2016). Here we propose a new renormalization and volume regularization procedures which allow one to calculate and distinguish physical parts of different matrix elements of operators of the current and of the energy–momentum tensor, at the same time relating the latter quantities with characteristics of the vacuum instability. For this purpose, a modified inner product and a parameter $$\tau $$ τ of the regularization are introduced. The latter parameter can be fixed using physical considerations. In the Klein zone this parameter can be interpreted as the time of the observation of the pair-production effect. In the refined formulation of QED with x-steps, we succeeded to consider the back-reaction problem. In the case of an uniform electric field E confined between two capacitor plates separated by a finite distance L, we see that the smallness of the back-reaction implies a restriction (the consistency condition) on the product EL from above.

Intrinsic properties of conservation-dissipation formalism of irreversible thermodynamics

This paper proposes four fundamental requirements for establishing PDEs (partial differential equations) modelling irreversible processes. We show that the PDEs derived via the CDF (conservation-dissipation formalism) meet all the requirements. In doing so, we find useful constraints on the freedoms of CDF and point out that a shortcoming of the formalism can be remedied with the help of the Maxwell iteration. It is proved that the iteration preserves the gradient structure and strong dissipativeness of the CDF-based PDEs. A refined formulation of the second law of thermodynamics is given to characterize the strong dissipativeness, while the gradient structure corresponds to nonlinear Onsager relations. Further advantages and limitations of CDF will also be presented. This article is part of the theme issue ‘Fundamental aspects of nonequilibrium thermodynamics’.

Why Sextus? The Pros logikous as Reliable Source for Gorgias’ Peri tou me ontos

Two versions of Peri tou mē ontos ptmo by Gorgias, related by an Anonymous Author MXG and by Sextus Empiricus SE, have been alternatively accredited by scholars according to their disposition to seek a doctrine or a rhetorical- communicational dimension respectively with the first tendency prevailing. Comparing the ptmo to the rest of Gorgiasʼ works, we verify and clearly demonstrate how SE manages to convey a precise modus argumentandi. In effect, SE shows Gorgias’ demonstrative reasoning as employing: 1 the application of demonstrandum and quod erat demonstrandum typical of Gorgiasʼ speeches, reinforced by a substantial and abundant use of verbs of explanation and demonstration, especially in comparison to the rest of the same Against the Logicians’ section. Otherwise, MXG reduces this lexicon to the more generic phēmi; 2 the continuous employment of the reductio ad absurdum, like in all of Gorgias’ works; 3 a very refined formulation of the principle of non-contradiction §67, similar to the one seen in Pal. 25. In addition, MXG is accurate in the discussion of some arguments as in the third kephalaion, however, presents as an overcorrected interpreter, more interested in questioning Gorgias than reporting his original text, also directly referring to Zeno, Melissus, and Leucippus. The context of the ptmo in SE’s work the structure presented leads us to believe that SE had the text or at least an accurate summary of the ptmo different from MXG. The aims of this paper are: 1 to demonstrate that SE shows well the Gorgianic demonstrative reasoning and, for this specific reason, he is reliable and valuable resource for us; 2 to hypothesise that SE’s version is based on and independent as yet unknown source.

Following Sextus: Demonstrative Argument in Gorgias’ Peri tou mē ontos

The two extant versions of Gorgias’ Peri tou mē ontos (PTMO) have been preserved by an anonymous author (MXG) and by Sextus Empiricus (S.E.). Both versions have been differently interpreted by scholars who examine either the doctrine or the rhetorical-communicational dimen­sion (the first option being dominant). When comparing the PTMO with the rest of Gorgias’ works, the present paper aims to demonstrate that S.E. offers a more precise account of Gorgias’ modus argumentandi. Thus, S.E. shows the following, typical features of Gorgias’ demonstra­tive reasoning: 1) application of demonstrandum and quod erat demon­strandum, 2) continuous employment of reductio ad absurdum and 3) a refined formulation of the principle of non-contradiction (similar to the one in Pal. 25). The MXG, on the other hand, is accurate in the discussion of particular arguments (e.g. the third kephalaion), but presents an interpreter who is more interested in questioning Gorgias rather than doing justice to his thought. Hence, this article concludes that it was S.E., who had the text or at least a relatively accurate summa­ry of the PTMO.

A refined method for calculating equivalent effective stratospheric chlorine

Chlorine and bromine atoms lead to catalytic depletion of ozone in the stratosphere. Therefore the use and production of ozone-depleting substances (ODSs) containing chlorine and bromine is regulated by the Montreal Protocol to protect the ozone layer. Equivalent effective stratospheric chlorine (EESC) has been adopted as an appropriate metric to describe the combined effects of chlorine and bromine released from halocarbons on stratospheric ozone. Here we revisit the concept of calculating EESC. We derive a refined formulation of EESC based on an advanced concept of ODS propagation into the stratosphere and reactive halogen release. A new transit time distribution is introduced in which the age spectrum for an inert tracer is weighted with the release function for inorganic halogen from the source gases. This distribution is termed the release time distribution. We show that a much better agreement with inorganic halogen loading from the chemistry transport model TOMCAT is achieved compared with using the current formulation. The refined formulation shows EESC levels in the year 1980 for the mid-latitude lower stratosphere, which are significantly lower than previously calculated. The year 1980 is commonly used as a benchmark to which EESC must return in order to reach significant progress towards halogen and ozone recovery. Assuming that – under otherwise unchanged conditions – the EESC value must return to the same level in order for ozone to fully recover, we show that it will take more than 10 years longer than estimated in this region of the stratosphere with the current method for calculation of EESC. We also present a range of sensitivity studies to investigate the effect of changes and uncertainties in the fractional release factors and in the assumptions on the shape of the release time distributions. We further discuss the value of EESC as a proxy for future evolution of inorganic halogen loading under changing atmospheric dynamics using simulations from the EMAC model. We show that while the expected changes in stratospheric transport lead to significant differences between EESC and modelled inorganic halogen loading at constant mean age, EESC is a reasonable proxy for modelled inorganic halogen on a constant pressure level.