785 research outputs found
On Strategy and Tactics Marxism and Electoral Politics
The rise of Syriza and Podemos alongside debates amongst Egyptian and other socialists about participation in parliamentary elections has reignited considerable interest across the international left about the issue of parliamentary elections. It is hard to imagine a more apt moment for the publication of August Nimtzās study of Leninās practical and theoretical engagement with this subject. While praising Nimtzās scholarship, this essay challenges his interpretation of the relationship between strategy and tactics in Leninās thought and the position of elections therein. It concludes with an attempt to unpick what is of general significance in Leninās engagement with electoral politics from more local details of interest only to scholars of Russian history
Cryptography using evolutionary computing
We present a method of generating encryptors, in particular, Pseudo Random Number Generators (PRNG), using evolutionary computing. Working with a system called Eureqa, designed by the Cornell Creative Machines Lab, we seed the system with natural noise sources obtained from data that can include atmospheric noise generated by radio emissions due to lightening, for example, radioactive decay, electronic noise and so on. The purpose of this is to `force' the system to output a result (a nonlinear function) that is an approximation to the input noise. This output is then treated as an iterated function which is subjected to a range of tests to check for potential cryptographic strength in terms of a positive Lyapunov exponent, maximum entropy, high cycle length, key diffusion characteristics etc. This approach provides the potential for generating an unlimited number of unique PRNG that can be used on a 1-to-1 basis. Typical applications include the encryption of data before it is uploaded onto the Cloud by a user that is provided with a personalised encryption algorithm rather than just a personal key using a `known algorithm' that may be subject to a `known algorithm attack' and/or is `open' to the very authorities who are promoting its use
The Polycomb system sustains promoters in a deep OFF state by limiting pre-initiation complex formation to counteract transcription
The Polycomb system has fundamental roles in regulating gene expression during mammalian development. However, how it controls transcription to enable gene repression has remained enigmatic. Here, using rapid degron-based depletion coupled with live-cell transcription imaging and single-particle tracking, we show how the Polycomb system controls transcription in single cells. We discover that the Polycomb system is not a constitutive block to transcription but instead sustains a long-lived deep promoter OFF state, which limits the frequency with which the promoter can enter into a transcribing state. We demonstrate that Polycomb sustains this deep promoter OFF state by counteracting the binding of factors that enable early transcription pre-initiation complex formation and show that this is necessary for gene repression. Together, these important discoveries provide a rationale for how the Polycomb system controls transcription and suggests a universal mechanism that could enable the Polycomb system to constrain transcription across diverse cellular contexts
Bio-CAP:a versatile and highly sensitive technique to purify and characterise regions of non-methylated DNA
Across vertebrate genomes methylation of cytosine residues within the context of CpG dinucleotides is a pervasive epigenetic mark that can impact gene expression and has been implicated in various developmental and disease-associated processes. Several biochemical approaches exist to profile DNA methylation, but recently an alternative approach based on profiling non-methylated CpGs was developed. This technique, called CxxC affinity purification (CAP), uses a ZF-CxxC (CxxC) domain to specifically capture DNA containing clusters of non-methylated CpGs. Here we describe a new CAP approach, called biotinylated CAP (Bio-CAP), which eliminates the requirement for specialized equipment while dramatically improving and simplifying the CxxC-based DNA affinity purification. Importantly, this approach isolates non-methylated DNA in a manner that is directly proportional to the density of non-methylated CpGs, and discriminates non-methylated CpGs from both methylated and hydroxymethylated CpGs. Unlike conventional CAP, Bio-CAP can be applied to nanogram quantities of genomic DNA and in a magnetic format is amenable to efficient parallel processing of samples. Furthermore, Bio-CAP can be applied to genome-wide profiling of non-methylated DNA with relatively small amounts of input material. Therefore, Bio-CAP is a simple and streamlined approach for characterizing regions of the non-methylated DNA, whether at specific target regions or genome wide
Marxism Lost and Found: Alasdair MacIntyre and the Contemporary Debate
This paper examines the changing nature of debates that focus on the philosophy of Alasdair MacIntyre. Whilst outlining the history of MacIntyreās engagement with Marxism and some of his key ideas, it argues that it is only recently that such debates have begun to rightfully recognise the continued relevance of Marxism to such discussions. I note that crucial aspects of MacIntyreās politics and philosophy, particularly his opposition to capitalism, are now integral to the contemporary debate which helps in generating a shared vision of radical politics. Nevertheless, I point out that key disagreements still remain as to the role of Marxism within such debates, the validity of MacIntyreās critique of Marxism, as well as the potentially problematic post-Marxist practice that MacIntyre advocates in After Virtue and beyond
Overcoming the barriers to implementing urban road user charging schemes
Urban road user charging offers the potential to achieve significant improvements in urban transport, but is notoriously difficult to implement. Cities need guidance on the range of factors to be considered in planning and implementing such schemes. This paper summarises the results of a 3 year programme which has collated evidence on the issues of most concern to cities. A state of the art report has provided evidence on 14 themes, ranging from objectives and design to implementation and evaluation. A set of 16 case studies has reviewed experience in design and implementation across Europe. The paper summarises their findings, provides references to more detailed information, presents the resulting policy recommendations to European, national and local government, and outlines the areas in which further research is needed
Structure calculation, refinement and validation using CcpNmr Analysis
CcpNmr Analysis provides a streamlined pipeline for both NMR chemical shift assignment and structure determination of biological macromolecules. In addition, it encompasses tools to analyse the many additional experiments that make NMR such a pivotal technique for research into complex biological questions. This report describes how CcpNmr Analysis can seamlessly link together all of the tasks in the NMR structure-determination process. It details each of the stages from generating NMR restraints [distance, dihedral,hydrogen bonds and residual dipolar couplings (RDCs)],exporting these to and subsequently re-importing them from structure-calculation software (such as the programs CYANA or ARIA) and analysing and validating the results obtained from the structure calculation to, ultimately, the streamlined deposition of the completed assignments and the refined ensemble of structures into the PDBe repository. Until recently, such solution-structure determination by NMR has been quite a laborious task, requiring multiple stages and programs. However, with the new enhancements to CcpNmr Analysis described here, this process is now much more intuitive and efficient and less error-prone
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