Oxidation and removal of atmospheric constituents involve complex sequences of reactions which can lead to the production of photo-oxidants such as ozone. In order to understand and model these complex reaction sequences, it is necessary to have a comprehensive understanding of reaction mechanisms and accurate estimates of kinetic parameters for relevant gas-phase atmospheric reactions. This book presents recent advances in the field and includes the following topics: e.g. the oxidation of simple organic compounds, NOx kinetics and mechanisms, OH radical production and rate constants for the OH attack on more complex organic compounds, peroxy and alkoxy radical reactions, photo-oxidation of aromatic and biogenic compounds, and the interaction between radical species.

One of the most important techniques for determining the atomic structure of a material is X-ray diffraction. One of the great problems of the technique, however, is the fact that only the intensity of the diffraction pattern can be measured, not its phase. The inverse problem, of determining the structure from the pattern thus contains ambiguities that must be resolved by other means. Quantitative X-ray analysis provides one way to resolve this phase problem: mixing the material in question with a material of known structure yields interferences that can be analyzed to yield the unknown phases. Invented in 1916, but little used at the time, the technique has seen a recent revival due to the development of extremely precise X-ray diffractometers coupled with powerful computers.

The range at which a weapon has been fired is an important measurement for the reconstruction of firearms offenses (murder, suicide, accident). All changes caused by a shot and which vary according to the distance from the weapon are suitable in principle for determining this distance. However, some procedures are very elegant in theory but hardly applicable in practice. The constructions of ammunition and the sequence of events during a shot are dealt with first as this knowledge forms a basis for understanding the various methods. \ The individual zones (classes) of firing distances (contact shot, intermediate shot, distance shot) are described. In this connection, the morphological methods for determining the firing distance are discussed. From the shape and size of the powder residue distribution (soot stains, powder tattooing) and with the knowledge of the weapon and ammunition, the distance from the target can be elucidated. In this chapter, the methods of making an invisible distribution visible are also dealt with. In order to determine the range of the shot from the appearance of the wound no complicated apparatus is necessary. One can judge with the naked eye. These procedures have a great advantage over the methods discussed in the following chapter in that they give stronger proof. They are more vivid and convincing for the uninitiated (judge or jury) than abstract measurements obtained by scientific devices.

This book is intended to collect in one place as much information as possible on the use of EPR spectroscopy in the analysis of systems in which two or more spins are magnetically coupled. This is a field where research is very active and chemists are elbow-to-elbow with physicists and biologists in the forefront. Here, as in many other fields, the contributions coming from different disciplines are very important, but for active researchers it is sometimes difficult to follow the literature, due to differences in languages, and sources which are familiar to, e. g. , a physicist, are exotic to a chemist. Therefore, an effort is needed in order to provide a unitary description of the many different phenomena which are collected under the title. In order to define the arguments which are treated, it is useful to state clearly what is not contained here. So we do not treat magnetic phenomena in conductors and we neglect ferro- and antiferromagnetic resonance. The basic foundations of EPR spectroscopy are supposed to be known by the reader, while we introduce the basis of magnetic interactions between spins. In the first two chapters we review the foundations of exchange interactions, trying to show how the magnetic parameters are bound to the electronic structure of the interacting centers.

The increasing interest in NMR spectroscopy of what in some confer ences in this field is commonly termed "other nuclei" is unmistakable. Chemists and biologists who employ NMR spectroscopy to study their problems have, however, been somewhat reluctant to study nuclei with electric quadrupole moments. These nuclei frequently give rise to broad NMR signals, sometimes too broad to be detectable with ordinary high resolution NMR spectrometers. Spectrometers that could cope with broad NMR signals of low intensity, "wide-line" spectrometers, have been available since the mid 1950: s but it appears that most of these instruments ended up in physical laboratories where the research was primarily directed towards solid state problems. The study of quadrupolar nuclei can provide unique and very valuable information on a variety of physico-chemical and biological systems. For one thing the relaxation of quadrupolar nuclei is in many ways easier to interpret than the relaxation of non-quadrupolar nuclei, since the former is in many cases caused by purely intramolecular interactions modulated by the molecular motion. Studies of quadrupolar relaxation have therefore furnished important information about molec ular reorientation and association in liquids and have played - and will certainly play for many years - an important role in testing new theoretical models of molecular motion in liquids."

Localization 1. C.S. Bosch, J.J.H. Ackerman, St. Louis, MO/USA SurfaceCoil Spectroscopy 2. P. Styles, Oxford, UK Rotating Frame Spectroscopyand Spectroscopic Imaging 3. P.A. Bottomley, Schenectady, NY/USA DepthResolved Surface Coil Spectroscopy (Dress) 4. R.J. Ordidge, J.A. Helpern, Detroit, MI/USA Image Guided Volume Selective Spectroscopy: A Comparison of Techniques for In-Vivo 31P NMR Spectroscopy of Human Brain 5. M. Decorps, D. Bourgeois, Grenoble, France Localized Spectroscopy Using Static Magnetic Field Gradients: Comparison of Techniques 6. J.A. den Hollander, P.R. Luyten, Ad J.H. Marien, Best, The Netherlands 1H NMR Spectroscopy and Spectroscopic Imaging of the Human Brain Spectral Editing and Kinetic Measurements 7. H.P. Hetherington, Birmingham, AL/USA Homo- and Heteronuclear Editing in Proton Spectroscopy 8. D. Freeman, R. Hurd, Fremont, CA/USA Metabolite Specific Methods Using Double Quantum Coherence Transfer Spectroscopy 9. B.A. Berkowitz, Research Triangle Park, NC/USA Two-Dimensional Correlated Spectroscopy In-Vivo 10. G. Navon, Tel Aviv, Israel; T. Kushnir, Tel Hashomer, Israel; N. Askenasy, O. Kaplan, Tel Aviv, Israel Two-Dimensional 31P-1H Correlation Spectroscopy in Intact Organs and Their Extracts 11. M. Rudin, A. Sauter, Basel, Switzerland Measurement of Reaction Rates In Vivo Using Magnetization Transfer Techniques

Isolated Cells and Perfused Organs 1. O. Kaplan, P.C.M. van Zijl, J.S. Cohen, Washington, DC/USA NMR Studies of Metabolism of Cells and Perfused Organs Individual Nuclei 2. S.R. Williams, London, UK In Vivo Proton Spectroscopy: Experimental Asoects and Potential 3. N. Beckmann, Basel, Switzerland In Vivo 13C Spectroscopy in Humans 4. M.J.W. Prior, R.J. Maxwell, J.R. Griffiths, London, UK Fluorine - 19F NMR Spectroscopy and Imaging In Vivo 5. J.S. Ingwall, Boston, MA/USA Measuring Cation Movements Across the Cell Wall Using NMR Spectroscopy: Sodium Movements in Striated Muscle 6. M. Rudin, A. Sauter, Basel, Switzerland In Vivo Phosphorus-31 NMR: Potential and Limitations

Methamphetamine is one of the most widely abused stimulants and together with amphetamine has led to serious social problems. Numerous papers in the fields of medicine, toxicology, pharmacology, sociology, etc. have appeared. In Japan for example about 20,000 to 22,000 persons have been arrested in recent years on suspicion of abuse, smuggling or illegal manufacture of drugs. In other countries, stimulant drugs also present social problems and efforts have been directed toward prevention. Although marked development of analytical techniques in the field of forensic sciences has been achieved, there is a need for a continuous review of recent advances. A review of studies on methamphetamine has therefore been made from the standpoint of forensic toxicology and legal medicine. Attention has been directed to biological samples because analyses and interpretation for the purpose of t.oxicological and As a detailed survey on abuse drugs involving clinical practice are important. 1 methamphetamine and amphetamine has been made by Fishbein and covered the time before 1980, we refer only to data and events appearing after 1980.

Soft X-rays are a powerful probe of matter. They interact selectively with electrons in atoms and molecules and can be used to study atomic physics, chemical reactions, surfaces and solids, and biological entities. Over the past 20 years, synchrotrons have emerged as powerful sources of soft X-rays for experimental use. A new, third generation of synchrotron light sources is scheduled to start operation over the next few years, beginning in 1993. These facilities are distinguished by their ultra-low emittance electron beams and by their undulators -- precisely engineered magnetic devices that cause the electrons passing through them to produce highly coherent X-rays and ultraviolet light of unprecedented spectral brightness. This volume emphasizes third-generation sources that produce light in the 10 eV--10 KeV energy range. It describes potential applications ranging from the purely scientific to the commercially viable and includes chapters on the practical aspects of designing undulators and beam line optics. Unique in its coverage, the book is a vital addition to the library of any scientist who needs information on the world's most advanced imaging and spectroscopic techniques. (ABSTRACT) This volume emphasizes the applications of new third generation synchrotron radiation sources that produce light in the ultraviolet and soft X-ray range of the spectrum. The unprecedented brightness of this light enables experiments to be conducted with greatly increased spatial and spectral resolution. Scientists can exploit these properties for imaging and spectroscopic applications that until now were impossible or impractical. Prominent researchers in the field describe these applications and others made possible by the light's pulsed time structure and polarization. The volume also includes chapters on the practical aspects of designing undulators and beam line optics.

Manipulation and Dilution Tools for Ruling Abundant Species "NMR is dead" was the slogan heard in the late 1960s at least among physicists, until John S. Waugh and his co-workers initiated a series of new NMR experiments, which employed the coherent modulation of interactions by strong radiofrequency fields. A wealth of new phenomena was observed, which are summarized in the introduction for the convenience of the unbiased reader, whereas Section 2 collects the basic spin interactions observed in solids. Line-narrowing effects in dipolar coupled solids by the application of multiple pulse experiments are extensively discussed in Section 3. Numerous extensions of the basic Waugh, Huber, and Haeberlen experiment have been developed by different groups and have been applied to the nuclei IH, 9Be, 19F, 27Al, 31p, 63CU in solids. Application of this technique to a variety of systems is still in progress and should reveal interesting insights into weak spin interactions in solids. It was soon realized that rare spins could be used as monitors for molecular fields in the solid state; however, rare spin observation is difficult because of the small signal-to-noise ratio. Pines, Gibby, and Waugh introduced a new concept of cross-polarization, based on ideas of Hahn and co-workers, which allows the detection ofrare spins with increased sensitivity. The dynamics involved are treated in detail. Other sections merely list results obtained by the techniques described and demonstrate their usefulness in the investigation of dynamical problems in molec ular and solid state physics."

Liquid-crystalline phases are now known to be formed by an ever growing range of quite diverse materials, these include those of low molecular weight as well as the novel liquid-crystalline polymers, such phases can also be induced by the addition of a solvent to amphiphilic systems leading to lyotropic liquid crystals. Irrespective of the structure of the constituent molecules these numerous liquid-cl)'Stailine phases are characterised by their long range orientational order. In addition certain phases exhibit elements of long range positional order. Our understanding, both experimental and theoretical, at the molecular level of the static behaviour of these fascinating and important materials is now well advanced. In contrast the influence of the long range order; both orientational and positional, on the molecular dynamics in liquid Cl)'Stais is less well understood. In an attempt to address this situation a NATO Advanced Study Institute devoted to liquid ctystal dynamics was held at n Ciocco, Barga, Italy in September 1989. This brought together experimentalists and theoreticians concerned with the various dynamical processes occurring in all liquid crystals. The skills of the participants was impressively wide ranging; they spanned the experimental techniques used in the study of molecular dynamics, the nature of the systems investigated and the theoretical models employed to understand the results. While much was learnt it was also recognised that much more needed to be done in order to advance our understanding of molecular dynamics in liquid Cl)'Stais.

In recent years, a number of textbooks on forensic science have been published, most of them directed to two groups, viz. the students of forensic science, and the customers so to say, (prosecutors, police officers, judges, defense lawyers). In this book, while covering fundamental concepts, we try to go a little further and address also active workers in the field of forensic chemistry. This is mainly achieved by relatively nu merous literature references. We hope that they may assist the forensic chemist in penetrating further into the subjects covered in this volume. At the end of most chapters there are examples of actual cases handled at the Swedish National Laboratory of Forensic Science. Many of these cases could, no doubt, have been investigated in greater detail, but they reflect the compromises often necessary for achieving a reasonable turnover. Some parts of the book are quite strongly colored by the personal opinions of the authors. We felt that these passages will give a little more life to the text than in other treatises of a more objective, but possibly duller character. The authors welcome all constructive criticism which will help to improve the book, should there be a second edition."

Capillary electrophoresis (CE) is a brand-new analytical me- thod with the capability of solving many analytical separa- tion problems very fast and economically. This method gives new information about the investigated substances which can- not easily be obtained by other means. CE has become an established method only recently, but will be implemented in almost every analytical laboratory in industry, service units and academia in the near future. The most important fields of CE application are pharmaceutical and biochemical research and quality control. The authors have exhaustive practical experience in the application of CE methods in the pharmaceutical industry and provide the reader with a comprehensive treatment of this method. The main focus is on how to solve problems when applying CE in the laboratory. Physico-chemical theory is only dealt with in depth when necessary to understand the underlying separation mechanisms in order to solve your problems at the analytical bench. An addendum includes tables on the preparation of buffers and recommended further reading.

Competitive binding techniques such as radioimmunoassay (RIA) are widely used to measure an enormous variety of compounds in biological fluids. Current methods have 1 2 arisen from the pioneering work ofYalow and Berson in the U. S. A. and Ekins in the u. K. Much of the early development was concerned with the analysis of protein hormones, and nearly a decade passed before attention focussed also on small molecules such as steroids and drugs. The potential of immunoassay methods for drug monitoring in clinical and forensic laboratories and in addict treatment programmes resulted in the commercial production of immunoassays for various therapeutic and abused drugs, making the technique available to laboratories lacking the facilities to raise their own antisera and synthesise labelled compounds. However, commercial assays are not only expensive but are restricted in range, and so it is advantageous for a forensic laboratory to have the capability to devise "in-house" immunoassays suited to its particular requirements. This chapter describes the theory and practice of RIA in forensic drug analysis. Much of the theory and some of the practice are applicable to immunoassays in which non isotopic labels are used, but such assays are not described in detail since, to date, the versatility and sensitivity of RIA have made it the immunoassay technique of choice in forensic toxicology. The particular advantages of RIA are its sensitivity and the fact that samples such as haemolysed blood can be assayed with little or no prior preparation."

The awareness and development of 'biodegradable' surfactants pre-dates current pressures by the environmental movement by nearly three decades, wherein a responsible industry mutually agreed to replace 'hard', non-biodegradable com ponents of household detergents by 'soft', biodegradable alternatives, without course to legislation. The only requirement at that time was for surfactants used in detergents to exhibit a 'primary biodegradability' in excess of 80%; this referring to the disap pearance or removal from solution of the intact surface active material as de tected by specified analytical techniques. This proved useful, as observed environmental impacts of surfactants, e.g. visible foam on rivers, are associated with the intact molecule. Test methods for 'primary biodegradability' were eventually enshrined in EU legislation for nonionic surfactants (Directive 821242/EEC, amended 73/404IEEC) and for anionic surfactants (Directive 8212431EEC, amended 73/405IEEC). No approved test methods and resultant legislation have been developed for cationic and amphoteric surfactants to date. The environmental classification of chemical substances, which of course includes surfactants, and associated risk assessment utilises a second criterion 'ready biodegradability'. This may be assessed by a number of methods which monitor oxygen uptake (BOD), carbon dioxide production or removal of dis solved organic carbon (DOC). Some surfactants which comply with the above Detergents Directive are borderline when it comes to 'ready biodegradability'."

Procedures for extracting or refining sensitive substances using dense gases have been developed for numerous purposes. Dense carbon dioxide is already being used industrially for decaffeination of coffee and extraction of hops. Further possible applications have been tested on the laboratory or pilot plant scales and shown to be mostly economical. Uses as varied as the non-aggressive extraction of spice, extraction of polymers, refining of spent oil, pyrolysis/extraction of wood and liquefaction of coal show the extremely wide range of application. The book comprehensively reviews the present state of development and features examples of application of this new technique.

E.S.R. techniques which are mature from a fundamental point of view. now constitute a routine investigation tool in chemistry as well as in biophysics in order to study and to follow the behaviour of radical species. Among the practical applications. let us mention for instance : -diffusion phenomena (solid -solid. liquid -solid such as the diffusion of molecules through membranes. films fibers ... ). -study of radical species to improve the elaboration of materials with high added value (composites). -detection of ionised food. -liquid crystals. polymers. -radiochemistry. -targetting of drugs. toxicology. A better understanding of basic phenomena allows to optimize industrial products and processes applied as well as in advanced fields as in well established ones. The high sensivity of ESR Spectroscopy and its derived specific techniques (spin labelling. spin probe. spin trapping ... ) offer information on the fme morphological structure of the matter as well as on its behaviour under various treatments otherwise not available. A Symposium was organized in Lyon (France) in January 1990 to promote the use of ESR. Its originality was to deal with the practical applications of ESR to organic and bioorganic materials. The scope of this meeting was to enlarge the field of application from basic research to more applied subjects and this may concern industrial as well as academic researchers. Moreover. the purpose of this symposium was to promote exchanges between European specialists working in public or private areas.

Over the last decade, fluorescence has become the dominant tool in biotechnology and medical imaging. These exciting advances have been underpinned by the advances in time-resolved techniques and instrumentation, probe design, chemical / biochemical sensing, coupled with our furthered knowledge in biology.

Complementary volumes 9 & 10, Advanced Concepts of Fluorescence Sensing: Small Molecule Sensing and Advanced Concepts of Fluorescence Sensing: Macromolecular Sensing, aim to summarize the current state of the art in fluorescent sensing. For this reason, Drs. Geddes and Lakowicz have invited chapters, encompassing a broad range of fluorescence sensing techniques. Some chapters deal with small molecule sensors, such as for anions, cations, and CO2, while others summarize recent advances in protein-based and macromolecular sensors. The Editors have, however, not included DNA or RNA based sensing in this volume, as this were reviewed in Volume 7 and is to be the subject of a more detailed volume in the near future.

Nuclear magnetic resonance spectroscopy, which has evolved only within the last 20 years, has become one of the very important tools in chemistry and physics. The literature on its theory and application has grown immensely and a comprehensive and adequate treatment of all branches by one author, or even by several, becomes increasingly difficult. This series is planned to present articles written by experts working in various fields of nuclear magnetic resonance spectroscopy, and will contain review articles as well as progress reports and original work. Its main aim, however, is to fill a gap, existing in literature, by publishing articles written by specialists, which take the reader from the introductory stage to the latest development in the field. The editors are grateful to the authors for the time and effort spent in writing the articles, and for their invaluable cooperation. The Editors Contents o. Kanert and M. Mehring Static Quadrupole Effects in Disordered Cubic Solids 1 F. Noack Nuclear Magnetic Relaxation Spectroscopy 83 Static Quadrupole Effects in Disordered Cubic Solids O. KANERT and M. MEHRING Physikalisches Institut der Universitat MUnster, BRD Contents I. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 II. Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Zero Field Spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. High Field Spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Transformation of the Electric Field Gradient Tensor . . . . . . . . . . 7 III. The Influence of the Quadrupole Perturbation on the NMR Signal . 8 1. General Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 a) The Free Induction Decay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 b) The Wide-Line Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 c) The Spin Echo Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .: . .

Experiments showinga rapid and reversible change ofcolor s eem likemagic and are always fascinating. The process involved, photochromism, has a few real and many potential applications. Photochromic glasses thatdarken int he s unlight (protecting eyes from excessive light intensity) and bleach ind im lighta re today a part ofe v eryday life. Organic photochromic compounds in plastic ophthalmic lenses, more comfortable to wear, are now competing with silversalts in glasses, despite the longer lifetime oft he inorganic system. This successful commercial application has given a new impetus to research in the general field of photo chromism, which had its most recent revival in the early eighties. The storyo forganic photochromism with its ups anddowns, from the breakthroughs oft he pioneering periodi n the fifties, through the hardtimes dueto the drawbacks of photodegradation, tot he recent successes is in many ways a saga. The upsurges in this domain were marked by an increasing flow of articles in scientific journals andt he publication of several books (in 1971, 1990, and 1992) that have collectedt he important accumulatedknowledge. Over this period, a considerable number ofpatents have been issued. International meetings have accompanied this activity, the most recent being held in 1993 (ISOP 93 atLes Embiez Island, France) and in 1996 (ISOP 96 inClearwater, Florida). Remark ably, these meetings had good representation from both academia and industry. The next ISOP is planned for 1999 in Fukuoka, Japan.

Over the past few years there has been a remarkable and rapid development of modern analytical methods, and the fields of nuclear magnetic resonance and mass spectrometry have been no exception. In addition to being able to do "more and faster," new innovative techniques have also arisen to contribute to a growing understanding of the relationship between chemical structure and biological activity. In order to explore a few of the more interesting points of those developments and applications, a seminar "From Biological Activity to Structure" was organized from September 5-7, 1988, at Interlaken. The four invited speakers, Richard M. Caprioli, Howard R. Morris, Wolfgang Steglich and Dudley H. Williams were kind enough to attend and discuss many facets of their research, especially methodological and technical developments and their applications to specific problems. Participants were introduced to continuous flow FAB (fast atom bombardment) and its use, for example, in the real time monitoring of biochemical reactions in vitro and in vivo; the structural elucidation of secondary metabolites from fungi; the analysis of molecule-receptor interactions; the determination of posttranslational modifications of peptides; and the location of S-S bridges in determining the tertiary structure of proteins.

As protein science continues to become an increasingly important aspect of academic and commercial sciences and technology, the need has arisen for a ready source of laboratory protocols for the analysis and evaluation of these biological polymers. Methods for Protein Analysis presents the methods most relevant to the generalist bench scientist working with proteins. A concise yet thorough summary, it covers laboratory methods that can be reasonably performed in a standard protein laboratory, without specialized equipment or expertise. Taking a how to approach, this book examines the techniques used to answer common protein analytical questions and describes methods useful in daily laboratory work. Methods for Protein Analysis is the ideal reference for protein laboratories in academic, government and industrial settings. It is an essential benchtop manual for first-year graduate students beginning their laboratory experience as well as for chemists, biochemists, and molecular biologists in the pharmaceutical, biotechnological, food and specialty chemical industries, and for analysts concerned with the purity and structural integrity of protein. Featuring illustrations and a convenient spiral binding, this guide offers a glossary of common abbreviations and a list of suppliers for protein science.

There are many kinds of nuc1ear data books; however some are too much specialized, while others have an arrangement of information which is inconvenient for students to use. With this book, we want to amend these situations. Handbooks of natural sciences must be exact and fair in their presentation of materials and they must be logical and convenient to use. If the users can develop new ideas or gain new insights from the books, they can be judged as valuable. The role of handbooks is not only to give a systematic representation of past knowledge, but also to serve as a basis for intellectual activity leading to future development. The purpose of this data book arises from the points described above. The chart of the nuc1ides which is frequently consulted by radioisotope users is not always convenient. By comparison, our Periodic Table with Nuc1ides has been devised with this in mind. It has been our experience that properties of a desired nuclide could be found in a much shorter time in the Periodic Table with Nuc1ides than in other nuc1ide charts. Additionally, by placing the -stabi1ity line within the nuc1ides in the table, the users may derive unam biguous ideas on the stability of the nuc1ides and the paths related to the creation of stable elements in the universe."

The importance of molybdenum, in industry, in life processes, etc., necessitates ac curate and precise analytical methods to determine its presence and its concentra tion in a variety of samples. With different samples molybdenum is present, as a major constituent, as a minor constituent, as one of several alloying components, as a trace element, and possibly in different oxidation states. The analyst is required to develop more selective and sensitive procedures for determining molyb denum in any sample type and new and improved methods for molybdenum are appearing in the literature at an ever increasing rate. It is the purpose of this work to summarize presently available methods for deter mining molybdenum. It proceeds in two parts. The first discusses procedures by tech nique, precipitation, colorimetry, electrochemistry, etc. The second discusses molyb denum in specific materials, alloys, biological, environmental, etc. In this latter por tion emphasis is placed upon sample treatment to obtain a working solution which can then be processed by the most expedient of the techniques discussed earlier."