Should You Accept a Take-it-or-Leave-it Job Offer?
If you find yourself in such a situation, there are many more options than yes or no.
Author(s): Horacio Falcão, INSEAD Senior Affiliate Professor

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Rights not set

Nick Atkins: Aero Engine Internal Flows

The November 5, 2012 New Trends in Aerospace presentation. This talk introduced the role of research into the aero-thermodynamics of the flow internal to an aero-engine core within the context of these future engine architectures. In places, the fluid physics share characteristics with atmospheric weather systems. In addition, the fluid flow is often coupled to the thermal field and it is fair to say that the accuracy of numerical predictions is perhaps a generation behind that of the blades
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Monetary policy and the financial crisis 2006-2009 [Audio]
Speaker(s): Cheryl Schonhardt-Bailey | Cheryl Schonhardt-Bailey is Reader in Political Science in the Government Department of the London School of Economics and Political Science, where she teaches courses in the politics of economic policy and legislative politics.
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Public Perceptions of Privacy
Would you give somebody your bank PIN for a candy bar? Cryptanalyst Orr Dunkelman tells the cryptography panel about a surprising study that found that most people would. Why is that? Perhaps because this bit of information is just one part of a system that may also require their
name, address, card number, and so on, they assume it is safe to share this one detail. But in today’s information-based world, where much of one’s personal information is available at the click of a

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UK Minister on latest unemployment figures
Dec. 12 - Minister for Employment, Mark Hoban, gives his outlook for the UK jobs market and reaction to the latest figures.
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Monsterlijke onderzoeken : Taalexperiment bij weeskinderen
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Een onderzoek dat de geschiedenis inging als “the monster study”, hoort zonder twijfel thuis in de reeks van de gruwelijkste psychologische experimenten.


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Kleuters maken een knuffel : Stappenplan
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De kleuters maken een knuffelbeer. Eerst maken ze aan de hand van het stappenplan het hoofd, dit wordt op een groot blad gekleefd. Onder het hoofd wordt dan een lichaam getekend dat ze met watten mogen beplakken, zodat ze een zachte beer …


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The Future of Academic Impacts - Conference - Breakout summaries - 18:00 Breakout summaries [Audio]
Speaker(s): Conference Attendees | The Future of Academic Impacts was an all day conference hosted by the LSE’s Impact of Social Sciences project team held on Tuesday, 4th December at Beveridge Hall, Senate House, London. The event is to mark the end of the three-year Impact of Social Sciences project based at the London School of Economics that has been funded by HEFCE. Working with colleagues at Imperial College London and the University of Leeds, we have looked at the nature and measurement
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Why Learn Chinese?
Why Learn Chinese?
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4.2 Reducing eutrophication

In Britain, water supply companies have tended to regard eutrophication as a serious problem only when it becomes impossible to treat drinking water supplies in an economic way. Threshold concentrations at which action is taken to reduce nutrient loadings thus depend on economic factors, as well as wildlife conservation objectives.

There are two possible approaches to reducing eutrophication:

  1. Reduce the source of nutrients (e.g. by phosphate str
    Author(s): The Open University

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4.1 Measuring and monitoring eutrophication

During the 1990s there was increased demand in the UK for effective methods of monitoring eutrophication. There was also considerable interest in the development of monitoring systems based on biotic indices. Several ‘quality indices’ based on a variety of organisms were explored. For monitoring tools to have practical application, they must satisfy certain requirements:

  • sampling must be quick and easy;

  • monitoring must be based on
    Author(s): The Open University

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3.2 Anthropogenic sources of nutrients

In addition to the natural sources of nutrients referred to above, nitrogen and phosphorus enter the environment from a number of anthropogenic sources. These are considered below.


Author(s): The Open University

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The DPS protein compacts the eubacterial chromosome during stress

When an E. coli cell enters into stationary phase, transcription and cell division cease completely. In such cells, the normal chromatin components, such as those described above, are replaced by a negatively charged protein called DPS. The interaction between DPS and DNA appears to be a specialised bacterial adaptation to survive starvation. In normal conditions of growth, the DNA within the bacterial cell is distributed evenly throughout the entire cytoplasm. In stationary cells, how
Author(s): The Open University

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6.2 Non-covalent bonding in site-specific binding

The affinity of a protein for DNA is determined in thermodynamic terms by the free energies of the individual components compared to the free energy of the DNA-protein complex. DNA binding proteins, which contain different binding motifs, demonstrate a wide range of thermodynamic strategies.

The affinity of a site-specific DNA binding protein for its specific DNA sequence is generally of the order of 104−107 times greater than its affinity for non-specific sequen
Author(s): The Open University

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4.6 Summary

  1. RNA chains play fundamentally important roles within the cell, including genetic information transfer (mRNA), components of the translation machinery (rRNA in ribosomes and tRNAs) and as regulatory small RNAs.

  2. The tertiary structure of RNA is determined by interactions that maximise base pairing. Despite instability and isolation problems, the tertiary structures of several major cellular RNAs are known.

  3. Transfer RNA struct
    Author(s): The Open University

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Aptamers

Aptamers are nucleic acid molecules that have been developed to mimic the selective and tight binding of other molecules such as antibodies. In order to identify an aptamer that is capable of binding to a target molecule, a process called Selex (systematic evolution of ligands by exponential enrichment) is utilised. The strategy relies upon a combination of a selective binding assay and amplification by PCR. A ‘library’ of short single-stranded DNA oligonucleotides is synthesised <
Author(s): The Open University

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Antisense regulation of gene expression

The term antisense refers to the use of a nucleic acid that is complementary to the coding (i.e. ‘sense’) base sequence of a target gene. When nucleic acids that are antisense in nature are introduced into cells, they can hybridise to the complementary ‘sense’ mRNA through normal Watson-Crick base pairing. Synthetic antisense DNA chains as short as 15–17 nucleotides in length have been used to block specific gene expression by either physically blocking translation of the tar
Author(s): The Open University

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3.2 Higher-order DNA structures: DNA twisting and torsional effects

As discussed earlier, the helical nature of DNA results for the most part from the properties of the bases, their interactions and the geometry of the helix itself. There is, however, another important contributor to the structure of DNA that is found within the cell. The DNA helix is actually under a torsional stress due to what is called DNA twisting, which arises when the two strands of the helix are twisted around the axis, as shown in Figure 11a.


Author(s): The Open University

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1.2 Nucleic acids: genetic, functional and structural roles in the cell

The first role that one immediately thinks about for nucleic acids is that of an inherited genetic material, principally in the form of DNA. In some cases, the inherited genetic material is RNA instead of DNA. For example, almost 60% of all characterised viruses have RNA genomes and these are more common in plant viruses than in animal viruses. There is considerable variation in the amount of genetic material present within organisms (Author(s): The Open University

Learning outcomes

After studying this unit you should be able to:

  • define and use each of the terms printed in bold in the text;

  • understand the properties of nucleotides, how they contribute to secondary and tertiary structures of nucleic acids at the molecular level, and how torsional states are maintained in cellular DNA;

  • understand the different composition and roles of nucleic acids in the cell and their interactions with each other and with agents that cau
    Author(s): The Open University

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