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Unlike some other reproductions of classic texts (1) We have not
used OCR(Optical Character Recognition), as this leads to bad
quality books with introduced typos. (2) In books where there are
images such as portraits, maps, sketches etc We have endeavoured to
keep the quality of these images, so they represent accurately the
original artefact. Although occasionally there may be certain
imperfections with these old texts, we feel they deserve to be made
available for future generations to enjoy.
Coastal dunes occur in almost every latitude - from tropical to
polar - and have been substantially altered by human activities.
Many are already severely and irreversibly degraded. Although these
ecosystems have been studied for a long time (as early as 1835),
there has been a strong emphasis on the mid-latitude dune systems
and a lack of attention given to the tropics where, unfortunately,
much of the modern exploitation and coastal development for tourism
is occurring.
This book brings together coastal dune specialists from tropical
and temperate latitudes, which together cover a wide set of topics,
including: geomorphology, community dynamics, ecophysiology, biotic
interactions and environmental problems and conservation. A major
product of this book is a set of recommendations for future
research, identifying relevant topics where detailed knowledge is
still lacking. It also identifies management tools that will
promote and maintain the rich diversity of the dune environments in
the context of continuing coastal development.
Modern Methods of Plant Analysis When the handbook Modern Methods
of Plant Analysis was first introduced in 1954 the considerations
were: 1. the dependence of scientific progress in biology on the
improvement of existing and the introduction of new methods; 2. the
difficulty in finding many new analytical methods in specialized
journals which are normally not accessible to experimental plant
biologists; 3. the fact that in the methods sections of papers the
description of methods is frequently so compact, or even sometimes
so incomplete that it is difficult to reproduce experiments. These
considerations still stand today. The series was highly successful,
seven volumes appearing between 1956 and 1964. Since there is still
today a demand for the old series, the publisher has decided to
resume publication of Modern Methods of Plant Analysis. It is hoped
that the New Series will be just as acceptable to those working in
plant sciences and related fields as the early volumes undoubtedly
were. It is difficult to single out the major reasons for success
of any publication, but we believe that the methods published in
the first series were up-to-date at the time and presented in a way
that made description, as applied to plant material, complete in
itself with little need to consult other publications. Contributing
authors have attempted to follow these guidelines in this New
Series of volumes.
After the proton and carbon, nitrogen is, with oxygen, the most
impor tant atom in organic and especially bioorganic molecules.
However, the development of nitrogen spectroscopy is indeed very
recent. This is due to the fact that nitrogen-14, which is the
naturally abundant iso tope, suffers, for structural studies, from
the disadvantages inherent in nuclei with a quadrupolar moment
(Table 1.1). Actually, indirect 15N measurements were reported in
the early days of double resonance spectroscopy and the first
direct detection of 15N resonance signals at the natural abundance
level was realized in 1964 (R 17) at 4.33 MHz 1 (~ 1T) using a 15
mm o.d. cell in the field sweep mode (~ 0.16 min- ).
Signal-to-noise ratios only of 3-4 were obtained for neat liquids
and this low sensitivity of the 15N resonance still remains the
main dis advantage for 15 spectroscopy (Table 1.1). However,
nitrogen-15 has, N probably more than any other nucleus, benefited
from the advances of NMR technology, i.e. Fourier transformation,
multinuclear facilities, wide-bore super conducting solenoids, and,
with the new generation of spectrometers, 15N-NMR is entering the
field of routine investigation. Nevertheless, in spite of these
spectacular improvements, obtaining 15N spectra of diluted species
or large biochemical molecules is often not very easy and a good
knowledge of the relaxation properties pecu liar to 15N may be
necessary in order to adjust the pulse sequences and the decoupler
duty cycle correctly (Section 2).
In 1931 Vrey, Brickwedde, and Murphy discovered the hydrogen
isotope deuterium. The isotopic enrichment was found to arise from
the fact that the electrolysis oflight water is faster than of
heavy water [1,2]. This success showed that although different
isotopes of an element behave identically from a chemical
standpoint the different isotopic masses nevertheless lead to both
isotope effects on equilibrium as well as on rate constants of
chemical reactions. Soon, ratios of equilibrium constants of
isotopic reactions were called "equilibrium isotope effects" (EIE),
ratios of isotopic rate constants "kinetic isotope effects" (KIE).
Isotope effects have been found to be especially large for those
elements which are directly involved in bond breaking and bond
formation during the reaction studied [3]. Such effects are,
therefore, referred to as "primary". Isotopic substitution in
atomic sites which maintain all chemical bonds with their neighbors
during the reaction of interest leads then only to smaller
"secondary" isotope effects. Because of the unique mass relation
between the different hydrogen isotopes hydrogen/deuterium isotope
effects are particularly large and have attracted most attention.
The largest contributions to these effects arise from changes in
the vibrational frequencies of the reactants. The theory of
equilibrium isotope effects has been founded by Vrey [4] and
Bigeleisen [5,6] and has widely been accepted [3].
Coastal dunes occur in almost every latitude - from tropical to
polar - and have been substantially altered by human activities.
Many are already severely and irreversibly degraded. Although these
ecosystems have been studied for a long time (as early as 1835),
there has been a strong emphasis on the mid-latitude dune systems
and a lack of attention given to the tropics where, unfortunately,
much of the modern exploitation and coastal development for tourism
is occurring.
This book brings together coastal dune specialists from tropical
and temperate latitudes, which together cover a wide set of topics,
including: geomorphology, community dynamics, ecophysiology, biotic
interactions and environmental problems and conservation. A major
product of this book is a set of recommendations for future
research, identifying relevant topics where detailed knowledge is
still lacking. It also identifies management tools that will
promote and maintain the rich diversity of the dune environments in
the context of continuing coastal development.
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