A.M. Stoneham
- Published in print:
- 2001
- Published Online:
- September 2007
- ISBN:
- 9780198507802
- eISBN:
- 9780191709920
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198507802.003.0007
- Subject:
- Physics, Condensed Matter Physics / Materials
Theoretical chemistry has developed a large number of approaches for molecular electronic structure. These include systematic simplifications as well as helpful concepts. Some of the basic ideas ...
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Theoretical chemistry has developed a large number of approaches for molecular electronic structure. These include systematic simplifications as well as helpful concepts. Some of the basic ideas (like valence bond and molecular orbital methods) and some of the more detailed approaches (such as singlet-triplet splittings) carry over to defect studies. This chapter gives a concise discussion, with selected topics dealt with in detail (localized orbitals, singlet-triplet splittings, and weak covalency).Less
Theoretical chemistry has developed a large number of approaches for molecular electronic structure. These include systematic simplifications as well as helpful concepts. Some of the basic ideas (like valence bond and molecular orbital methods) and some of the more detailed approaches (such as singlet-triplet splittings) carry over to defect studies. This chapter gives a concise discussion, with selected topics dealt with in detail (localized orbitals, singlet-triplet splittings, and weak covalency).
W. Maxwell Cowan, Thomas M. Jessell, and S. Lawrence Zipursky (eds)
- Published in print:
- 1998
- Published Online:
- May 2009
- ISBN:
- 9780195111668
- eISBN:
- 9780199865833
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195111668.001.0001
- Subject:
- Neuroscience, Molecular and Cellular Systems, Development
Although the major features of neural development have been known for nearly a century, it is only relatively recently that the underlying molecular and cellular mechanisms have begun to be ...
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Although the major features of neural development have been known for nearly a century, it is only relatively recently that the underlying molecular and cellular mechanisms have begun to be uncovered. Among the many factors accountable for the transformation of developmental neurobiology from a largely descriptive to an analytic and mechanistic discipline, two stand out as singularly important. First has been the application of molecular genetic methods to the study of such events and neural induction, the determination of neuronal phenotypes, the establishment of neuronal processes, and the formation of specific patterns of connections. The second factor has been the use of a variety of “model” organisms: each offering particular advantages in the study of one or another developmental process. The pace of new advances often overwhelms experienced workers in the field. This book updates and introduces the subject and also details recent successes in understanding the early events of neural development.Less
Although the major features of neural development have been known for nearly a century, it is only relatively recently that the underlying molecular and cellular mechanisms have begun to be uncovered. Among the many factors accountable for the transformation of developmental neurobiology from a largely descriptive to an analytic and mechanistic discipline, two stand out as singularly important. First has been the application of molecular genetic methods to the study of such events and neural induction, the determination of neuronal phenotypes, the establishment of neuronal processes, and the formation of specific patterns of connections. The second factor has been the use of a variety of “model” organisms: each offering particular advantages in the study of one or another developmental process. The pace of new advances often overwhelms experienced workers in the field. This book updates and introduces the subject and also details recent successes in understanding the early events of neural development.
Alexandra Kraberg, Katja Metfies, and Rowena Stern
- Published in print:
- 2017
- Published Online:
- October 2017
- ISBN:
- 9780199233267
- eISBN:
- 9780191835698
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780199233267.003.0009
- Subject:
- Biology, Aquatic Biology, Ecology
This chapter reviews phytoplankton sampling and analysis techniques, discussing them in light of their advantages and disadvantages. Different sampling methods have varying levels of precision and ...
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This chapter reviews phytoplankton sampling and analysis techniques, discussing them in light of their advantages and disadvantages. Different sampling methods have varying levels of precision and accuracy. This means that they affect the ways in which individual data sets can be interpreted, and methods therefore have to be kept consistent within time series to avoid creating artefacts. The discussions cover qualitative and semi-quantitative methods, quantitative methods, sample analysis, automated/semi-automated systems, and molecular methodologies. None of the methods are universally applicable but depend on the right set of tools and the scientific and financial context in which they are used. Molecular techniques hold great promise particularly for taxa that cannot be identified by routine microscopical techniques.Less
This chapter reviews phytoplankton sampling and analysis techniques, discussing them in light of their advantages and disadvantages. Different sampling methods have varying levels of precision and accuracy. This means that they affect the ways in which individual data sets can be interpreted, and methods therefore have to be kept consistent within time series to avoid creating artefacts. The discussions cover qualitative and semi-quantitative methods, quantitative methods, sample analysis, automated/semi-automated systems, and molecular methodologies. None of the methods are universally applicable but depend on the right set of tools and the scientific and financial context in which they are used. Molecular techniques hold great promise particularly for taxa that cannot be identified by routine microscopical techniques.
David J. Gibson
- Published in print:
- 2014
- Published Online:
- January 2015
- ISBN:
- 9780199671465
- eISBN:
- 9780191792496
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199671465.003.0005
- Subject:
- Biology, Plant Sciences and Forestry
This chapter describes the measurements or traits that can be made on individual plants or populations. The value of different morphological, physiological and phenological traits for testing an ...
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This chapter describes the measurements or traits that can be made on individual plants or populations. The value of different morphological, physiological and phenological traits for testing an hypothesis is discussed. Lists of easy-to-measure and hard-to-measure traits are contrasted. The topic of trait measurement is divided into eight sections in this chapter: the value of making repeated measurements, locating and marking population units, morphological measurements (e.g., counts of plant parts), measurements of seeds and dispersal units (including the soil seed bank), physiological measurements (e.g., photosynthesis), molecular measurements (e.g., protein and DNA markers, plus the newest approaches including SNPS, gene expression profiling, epigenetics, and functional metagenomics), indices for expressing plant growth (e.g, Relative Growth Rate), and the calculation of fitness, fecundity and reproductive effort.Less
This chapter describes the measurements or traits that can be made on individual plants or populations. The value of different morphological, physiological and phenological traits for testing an hypothesis is discussed. Lists of easy-to-measure and hard-to-measure traits are contrasted. The topic of trait measurement is divided into eight sections in this chapter: the value of making repeated measurements, locating and marking population units, morphological measurements (e.g., counts of plant parts), measurements of seeds and dispersal units (including the soil seed bank), physiological measurements (e.g., photosynthesis), molecular measurements (e.g., protein and DNA markers, plus the newest approaches including SNPS, gene expression profiling, epigenetics, and functional metagenomics), indices for expressing plant growth (e.g, Relative Growth Rate), and the calculation of fitness, fecundity and reproductive effort.
Claus Nielsen
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780199606023
- eISBN:
- 9780191774706
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199606023.001.0001
- Subject:
- Biology, Evolutionary Biology / Genetics, Animal Biology
This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from ...
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This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from studies using immune stainings of nerves and muscles and blastomere markings, which makes it possible to follow the fate of single blastomeres all the way to early organogenesis. Until recently, the information from analyses of gene sequences has tended to produce myriads of quite diverging trees. However, the latest generation of molecular methods, using many genes, expressed sequence tags, and even whole genomes, has brought a new stability to the field. The book brings together the information from these varied fields, and demonstrates that it is indeed now possible to build a phylogenetic tree from a combination of both morphology and gene sequences. This thoroughly revised third edition brings the subject fully up to date, especially in light of the latest advances in molecular techniques. The book is illustrated throughout with finely detailed line drawings and clear diagrams, many of them new.Less
This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from studies using immune stainings of nerves and muscles and blastomere markings, which makes it possible to follow the fate of single blastomeres all the way to early organogenesis. Until recently, the information from analyses of gene sequences has tended to produce myriads of quite diverging trees. However, the latest generation of molecular methods, using many genes, expressed sequence tags, and even whole genomes, has brought a new stability to the field. The book brings together the information from these varied fields, and demonstrates that it is indeed now possible to build a phylogenetic tree from a combination of both morphology and gene sequences. This thoroughly revised third edition brings the subject fully up to date, especially in light of the latest advances in molecular techniques. The book is illustrated throughout with finely detailed line drawings and clear diagrams, many of them new.
Christopher O. Oriakhi
- Published in print:
- 2009
- Published Online:
- November 2020
- ISBN:
- 9780195367997
- eISBN:
- 9780197562635
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780195367997.003.0015
- Subject:
- Chemistry, Analytical Chemistry
Volumes and densities of gases vary significantly with changes in pressure and temperature. This means that measurements of the volumes of gases will likely vary from ...
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Volumes and densities of gases vary significantly with changes in pressure and temperature. This means that measurements of the volumes of gases will likely vary from one laboratory to another. To correct for this, scientists have adopted a set of standard conditions of temperature and pressure (STP) as a reference point in reporting all measurements involving gases. They are 0°C (or 273 K) and 760mmHg or 1 atm (or 1.013×105 N m−2 in S.I. units). Therefore standard temperature and pressure, as used in calculations involving gases, are defined as 0°C (or 273 K) and 1 atmosphere (or 760 torr). (Note: For calculations involving the gas laws, temperature must be in K.) Boyle’s law states that the volume of a given mass of gas at constant temperature is inversely proportional to the pressure. The law can be expressed in mathematical terms: V α 1/P or PV = k at constant n and T Since P×V = constant, problems dealing with P–V relationships can be solved by using the simplified equation: P1V1 = P2V2 Here P1, V1 represent one set of conditions and P2, V2 represent another set of conditions for a given mass of gas. Charles’s law states that the volume of a given mass of gas is directly proportional to its absolute temperature. So if the absolute temperature is doubled, say from 300 K to 600 K, the volume of the gas will also double. A plot of the volume of a gas versus its temperature (K) gives a straight line. A notable feature of such a plot is that the volume of all gases extrapolates to zero at the same temperature, −273.2◦C. This point is defined as 0 K, and is called absolute zero. Thus, the relationship between the Kelvin and Celsius temperature scales is given as: K = 0°C + 273. Scientists believe that the absolute zero temperature, 0 K, cannot be attained, although some laboratories have reported producing 0.0001 K.
Less
Volumes and densities of gases vary significantly with changes in pressure and temperature. This means that measurements of the volumes of gases will likely vary from one laboratory to another. To correct for this, scientists have adopted a set of standard conditions of temperature and pressure (STP) as a reference point in reporting all measurements involving gases. They are 0°C (or 273 K) and 760mmHg or 1 atm (or 1.013×105 N m−2 in S.I. units). Therefore standard temperature and pressure, as used in calculations involving gases, are defined as 0°C (or 273 K) and 1 atmosphere (or 760 torr). (Note: For calculations involving the gas laws, temperature must be in K.) Boyle’s law states that the volume of a given mass of gas at constant temperature is inversely proportional to the pressure. The law can be expressed in mathematical terms: V α 1/P or PV = k at constant n and T Since P×V = constant, problems dealing with P–V relationships can be solved by using the simplified equation: P1V1 = P2V2 Here P1, V1 represent one set of conditions and P2, V2 represent another set of conditions for a given mass of gas. Charles’s law states that the volume of a given mass of gas is directly proportional to its absolute temperature. So if the absolute temperature is doubled, say from 300 K to 600 K, the volume of the gas will also double. A plot of the volume of a gas versus its temperature (K) gives a straight line. A notable feature of such a plot is that the volume of all gases extrapolates to zero at the same temperature, −273.2◦C. This point is defined as 0 K, and is called absolute zero. Thus, the relationship between the Kelvin and Celsius temperature scales is given as: K = 0°C + 273. Scientists believe that the absolute zero temperature, 0 K, cannot be attained, although some laboratories have reported producing 0.0001 K.
