The evolution of energy-transducing systems. Studies with an extremely halophilic archaebacterium

The halobacterial ATPase was labeled with C-14-dicyclohexylcarbodiimide and subunit 2 of the enzyme was prepared by electroelution. Subunit 2 was cleaved by several chemical and enzymatic procedures for further preparation of peptides. Immunoreactions (Western blotting) of halobacterial membranes were performed with an antiserum against subunit A of the vacuolar ATPase from Neurospora crassa. A 85 K band (subunit 1) from the membranes of H saccharovorum and from two halobacterial isolates, which were isolated from Permian salt sediments, reacted strongly with the antiserum. The ATPase from the latter isolates resembled the ATPase from H saccharovorum, but had a higher content of acidic amino acids. If it can be verified that the age of the bacterial isolates is in the same range as when deposition of salt occurred, an extremely interesting system for the study of evolutionary questions would be available, since the salt-embedded bacteria presumably did not undergo mutational and selectional events

The BFKL-Pomeron In Deep Inelastic Diffractive Dissociation near t=0

The small-$t$ behaviour of the deep inelastic diffractive dissociation cross section in the triple Regge region is investigated, using the BFKL approximation in perturbative QCD. We show that the cross section is finite at $t=0$, but the diffusion in $\ln{k_t^2}$ leads to a large contribution of small momenta at the triple Pomeron vertex. We study the dependence upon the total energy and the invariant mass. At $t=0$, there is a decoupling of the three BFKL singularities which is a consequence of the conservation of the conformal dimension. For large invariant masses, the four gluon state in the upper t-channel plays an important role and cannot be neglected.Comment: 43 pages, LaTex , 11 ps-figures (uuencoded) appende

Unsupervised Learning of Visual Structure using Predictive Generative Networks

The ability to predict future states of the environment is a central pillar of intelligence. At its core, effective prediction requires an internal model of the world and an understanding of the rules by which the world changes. Here, we explore the internal models developed by deep neural networks trained using a loss based on predicting future frames in synthetic video sequences, using a CNN-LSTM-deCNN framework. We first show that this architecture can achieve excellent performance in visual sequence prediction tasks, including state-of-the-art performance in a standard 'bouncing balls' dataset (Sutskever et al., 2009). Using a weighted mean-squared error and adversarial loss (Goodfellow et al., 2014), the same architecture successfully extrapolates out-of-the-plane rotations of computer-generated faces. Furthermore, despite being trained end-to-end to predict only pixel-level information, our Predictive Generative Networks learn a representation of the latent structure of the underlying three-dimensional objects themselves. Importantly, we find that this representation is naturally tolerant to object transformations, and generalizes well to new tasks, such as classification of static images. Similar models trained solely with a reconstruction loss fail to generalize as effectively. We argue that prediction can serve as a powerful unsupervised loss for learning rich internal representations of high-level object features.Comment: under review as conference paper at ICLR 201

A comparison of an ATPase from the archaebacterium Halobacterium saccharovorum with the F1 moiety from the Escherichia coli ATP Synthase

A purified ATPase associated with membranes from Halobacterium saccharovorum was compared with the F sub 1 moiety from the Escherichia coli ATP Synthase. The halobacterial enzyme was composed of two major (I and II) and two minor subunits (III and IV), whose molecular masses were 87 kDa, 60 kDa, 29 kDa, and 20 kDa, respectively. The isoelectric points of these subunits ranged from 4.1 to 4.8, which in the case of the subunits I and II was consistent with the presence of an excess of acidic amino acids (20 to 22 Mol percent). Peptide mapping of sodium dodecylsulfate-denatured subunits I and II showed no relationship between the primary structures of the individual halobacterial subunits or similarities to the subunits of the F sub 1 ATPase (EC 3.6.1.34) from E. coli. Trypsin inactivation of the halobacterial ATPase was accompanied by the partial degradation of the major subunits. This observation, taken in conjunction with molecular masses of the subunits and the native enzyme, was consistent with the previously proposed stoichiometry of 2:2:1:1. These results suggest that H. saccharovorum, and possibly, Halobacteria in general, possess an ATPase which is unlike the ubiquitous F sub o F sub 1 - ATP Synthase

The potential hazard of staphylococci and micrococci to human subjects in a life support systems evaluator while on a simulated GT-7 mission Final report, 19 Sep. - 1 Nov. 1965

Potential hazard of staphylococci and micrococci to human subjects in life support system

How to judge scientific research articles

How should scientists judge the quality of research articles? In this article I present general criteria for judging the scientific value of a research report submitted for publication. These criteria can improve the quality of research articles and produce fair referee reports that are scientifically justifiable. My view is based on four fundamental rules that guide all good science. These rules ought to determine whether scientific research reports merit publication in scientific journals. The rules for good science also structure this article. They are as follows. [1] Scientists must use specialised problem-solving; [2] scientists must refer to previous work; [3] scientists must justify their findings; and [4] scientists must convince their scientific community

The Intellectual Legacy of Stephen Bantu Biko (1946-1977)

In this essay I will attempt to explain the significance of Stephen Bantu Biko's life. This I will do in terms of his intellectual contribution to the liberation of black people from the radically unjust apartheid society in South Africa. Firstly, I will discuss his contribution to liberate blacks psychologically from the political system of apartheid, pointing out how he broke through the normative and pragmatic acceptance of the situation in the radically unjust apartheid society. He experienced black people as being defeated people, and he wanted to direct their attention to the fact that the cause of their unjust situation was other human beings and thus they could change it. Secondly, I point out how he gave black people a new self-understanding and self worth. One way of doing this was by means of community projects which fostered self-reliance. For Biko it was important that black people should act autonomously, and not let other people make decisions on their behalf. They also had to re-evaluate their cultural heritage to discover the positive aspects thereof. Lastly, I focus on his views on his ideal for a future just South Africa and show how important he regarded dialogue as a political tool

Modernity, postmodernism and politics (in places like South Africa)

In this chapter I show that it is possible to interpret an important group of postmodern texts as presenting intellectual and practical challenges with a specific focus that is worth the serious attention of everyone interested in politics. My interpretation shows that a certain strand of postmodern thought is not only consonant with a liberal democratic political morality, but also modifies and extends it in an eminently desirable direction. Such an interpretation has become possible because a significant consensus has emerged from the writings of prominent commentators and participants in the debates about postmodernism. I reconstruct this emerging consensus by referring specifically to the contribution of these postmodern texts to politics, thus leaving aside its possible contribution to the arts and sciences. I start by giving an exposition of a new understanding of modernity that has been brought about by the debates on modernity / postmodernism. Then I characterize the postmodern political condition by describing those changes in contemporary modern societies that stimulate and facilitate the development and growth of postmodernism. The next section provides an interpretation of the political philosophy contained in the work of prominent postmodern thinkers such as Derrida, Foucault, Lyotard and Jencks. In this overview I show that an emphasis on the importance of heterogeneity and otherness unifies the diverse contributions of these postmodernists to political philosophy. I conclude the article by drawing some implications for politics in places like South Africa, from the insights I judge postmodernism provides to political philosophy in general