Long Live the Loophole

Editor's Note: Although negotiations concerning the "fiscal cliff" seem to be at an impasse, the one thing both Democrats and Republicans agree on is their desire to close tax loopholes. That is bad news for the economy, because as Ludwig von Mises said, "Capitalism breathes through those loopholes." Closing loopholes to "broaden the tax base" has been a supply
Author(s): No creator set

License information
Related content

The loss of a DNA base causes an abasic site

Hydrolysis of the deoxyribose Cl'–base linkage results in the complete loss of a purine or pyrimidine base, resulting in what is called an abasic site, an event with obvious genetic consequences. This hydrolysis reaction is much more likely to occur at purine bases, resulting in depurination of the DNA (Table 3a<
Author(s): The Open University

2.5 Obesity and brain reward systems

Very palatable foods, especially those high in fat and carbohydrate may be potent stimuli for neural pathways in the brain. Direct evidence for this idea has been found in recent studies of non-human animals. For example, it is known that many types of both natural (i.e. food, sex) and drug (e.g. cocaine or amphetamine, opiates, nicotine) rewards are able to stimulate activity within a brain pathway that innervates the ventral striatum at the base of the forebrain (Author(s): The Open University

2.3 Broadband spectra

The broadband spectrum is the spectrum over all the observed wavelength ranges. To plot the broadband spectrum of any object it is necessary to choose logarithmic axes.

  • Why is it necessary to use logarithmic axes?

  • Because both the spectral flux density, Fλ, and the wavelength vary by many powers of 10.

Author(s): The Open University

Introduction

Active galaxies provide a prime example of high-energy processes operating in the Universe. This unit introduces the evidence for activity from the spectra of some galaxies, and the concept of a compact active galactic nucleus as a unifying model for the observed features of several types of active galaxy. It also develops the key skill of applying arithmetic and simple algebra to solving scientific problems.

This course is an adapted extract fromt he course Author(s): The Open University

Acknowledgements

The content acknowledged below is Proprietary (see terms and conditions) and is used under licence.

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:

Readings

The readings acknowledged below are proprietary and used under licence

Other third party material is acknowledged as it appears within the content of the unit.

Reading 1: Miller, S. (2001) ‘Publ
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

3.1 Introduction

On an autumnal morning in November 1994, a group of people gathered at Regent's College, London, conscious that they were making history. The purpose of the meeting was to discuss an important issue: plant biotechnology and how it should be regulated in the UK. At the time, the genetic engineering of plants was emerging as a technology of great potential for the development of new pest-resistant, higher yield crops, although the technique hadn't attracted the degree of media attention and pub
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

Acknowledgements

The content acknowledged below is Proprietary (see terms and conditions) and is used under licence. This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:


Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

3.6.2 Experiencing the pregnancy

If a woman does find herself pregnant, what can she expect? Pregnancy is a time of enormous physical and emotional changes, and these are often difficult to cope with. To begin with, the physical effects of early pregnancy can be extremely unpleasant. The nausea and vomiting of morning sickness can be very severe, and although in many women the symptoms abate after a while, in others they persist right through the pregnancy. Sickness is thought to be due to the high levels of progestogen circ
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

3.1 Introduction

The simplest and oldest way of storing surface water is in reservoirs and this has been done for thousands of years. Most reservoirs are still built to increase water supplies, but some are also built for other purposes, especially for generating hydroelectric power and for protection against floods. The Tennessee River in the United States, for example, has reservoirs to trap and store water that would otherwise cause floods, the water being released when the height of the river falls to saf
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

6 Direct heating using geothermal energy

In the same way that waste heat from conventional power stations can be used for direct heating of buildings, and in industrial production and horticulture, low-grade geothermal energy has considerable potential. Many existing developments, such as those in Iceland, use spent fluids from geothermal electricity generation. Areas of natural hot springs are an obvious target, but it is also relatively simple to exploit normal heat flow using either natural groundwater or a variety of heat-exchan
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

4 Locating high-enthalpy geothermal fields

The search for potentially useful geothermal fields focuses initially on locating rocks that have been chemically altered by natural geothermal fluids, as well as looking for obvious surface features of geothermal activity such as geysers and hot springs. Measurements of fluid flow through the field allow estimation of its likely economic potential.

When a promising resource has been located exploration wells are drilled. However, given the high pressures and temperatures typical of a g
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

2.7 Summary

  1. Eukaryotic cells contain numerous distinct types of membrane-bound compartment. Transport vesicles move proteins and other molecules between the compartments.

  2. Proteins contain signalling sequences or patches that specify their destination compartment.

  3. Proteins destined for lysosomes, secretion or the plasma membrane are synthesised in the ER, transported to the cis Golgi, modified in the Golgi apparatus, and sorted and pa
    Author(s): The Open University

    License information
    Related content

    Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

6.2 Catalytic mechanisms

In general terms, the following mechanisms operate at the active site of an enzyme to bring about the conversion of substrate to product:

  1. Charged groups at the enzyme active site alter the distribution of electrons in the substrate. By affecting the electron distributions in key atoms in the substrate, the enzyme can destabilise existing bonds and favour the formation of new bonds. This principle is illustrated below, using as an example the hydrolysis
    Author(s): The Open University

    License information
    Related content

    Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

6.1 Introduction

Among those proteins of known function, the majority are enzymes. Enzymes act as catalysts, i.e. they increase the rates of reactions, making and breaking bonds, without themselves undergoing any permanent change. They are highly specific for particular reactions and are excellent examples of how a protein's function is entirely dependent on its structure.

First of all, a protein must bind its substrate (or substrates) in a specific fashion; it must then convert the substrate(s) into th
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

1.1 So what's it all about?

iSpot is a website aimed at helping anyone identify anything in nature. Once you've registered, you can add an observation to the website and suggest an identification yourself or see if anyone else can identify it for you. You can also help others by adding an identification to an existing observation, which you may like to do as your knowledge grows. Your reputation on the site will grow as people agree with you identifications. You may also like to visit our forums which offer lively debat
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

4.2 Social dynamics

Yet another type of diagram is given in this section. Take a preliminary look at Figure 7, which is a way of illustrating the relationship
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

2.2 Size and shape

The shape of the head is determined mainly by the relative sizes of the jaws and the nose and the back of the skull containing the brain, eyes, ears and, in artiodactyls, the horns or antlers. All these structures may differ greatly between otherwise similar species.

SAQ 7


Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

5.3.3 Ring-tailed lemurs

LoM p. 239 describes the life and habits of the ring-tailed lemur, drawing attention to what are commonly called their ‘stink-fights’ – a further example of the importance of smell in lemur society. But here the habit is prevalent in a species that is active by day and can spend as much as 40 per cent of its waking time on the ground. In fact, these animals seem equally at home on the ground and in the trees. Over time, some populations in Madagascar have become more ground-based than o
Author(s): The Open University

License information
Related content

Except for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share