Easton Wren - Profile on Academia.edu (original) (raw)

Papers by Easton Wren

Geophysical Prospecting, 1975

Exploration Seismology Volume 1: History, Theory and Data Acquisition

Geoscience Canada, 1984

This book is intended both as a text for students in advanced courses and also as a reference boo... more This book is intended both as a text for students in advanced courses and also as a reference book for persons engaged in seismic exploration. The theoretician and student need to appreciate what is practical, and practitioners need to understand theory and the possibilities it may ...

The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by ... more The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by the focussed on velocity inversion and the generation of derivation of the reflectivity sequence, allows the the pseudo-acoustic log from the seismic trace. ideal pre-conditioning for seismic velocity inverThere are several published methods on wavelet sion. extraction which invariably make assumptions about the wavelet, in terms of the phase spectrum, The significance of this approach is demonstrated as well as assumotions about the reflectivity. in a series of synthetic and real data examoles. The The SONISEIS method will provide the basic statistically computed wavelets allow for synthetic wavelet using a statistical estimation, indepenseismograms which consistently outmatch those dently of any assumptions about the wavelet. The with Ricker or best-estimate zero or minimumderived wavelet is re&ced in the seismic trace phase wavelets, with a spike of approphate amplitude and polarity. ...

Geophysics: Target Shooting for the Drill

While the oil industry was totally familiar with applied geophysics in the 1930’s, it was during ... more While the oil industry was totally familiar with applied geophysics in the 1930’s, it was during the 25-year span following World War II that geophysical technology and expertise underwent substantial development. Major innovations during this period included multifold acquisition, non-dynamite sources, competent marine acquisition, the transition from analog to digital recording and the corresponding emphasis on computer processing. However, geophysical objectives did not change during the same period. Primary targets remained structural traps (including reefs) and the collective development in acquisition and processing technology represented essentially an improvement in data quality. While interpretation techniques remained virtually static, the industry became intoxicated with aesthetic seismic sections and very little attention was paid to what the sections should look like. An elusive butterfly that taunted the industry was the idealistic possibility of using seismic data to ...

Geophysics: Target Shooting for the Drill

Seismic Signal Amplitude and Stratigraphy: Back to the Basics: ABSTRACT

Aapg Bulletin, 1986

THE APPLICATION OF OPTIMAL WAVELETS IN SEISMIC INVERSION

The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by ... more The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by the focussed on velocity inversion and the generation of derivation of the reflectivity sequence, allows the the pseudo-acoustic log from the seismic trace. ideal pre-conditioning for seismic velocity inver- There are several published methods on wavelet sion. extraction which invariably make assumptions about the wavelet, in

Geophysical Prospecting, 1975

With few exceptions, traditional approaches to contouring have been too subjective. Contouring an... more With few exceptions, traditional approaches to contouring have been too subjective. Contouring and contour maps are too often discussed in terms more appropriate to art than to science. With hand contouring there is some justification for this attitude; with machine (i.e. programmed) contouring there is none.Hand contouring is highly susceptible to interpretive judgement and the interpreter is not bound by rigid mathematical constraints. Hence, in allowing for the interpreter's “freedom of expression” it may be difficult to evaluate hand contouring in a totally analytical and objective manner. Machine contouring, however, is based upon mathematical formulation. It is therefore a consistent and objective procedure, ideally suited to objective definition and analysis.It can be demonstrated that the combined process of sampling plus contouring constitutes a two-dimensional filter. The contouring component is that part which introduces “distortion” or wavenumber discrimination. An ideal contour package is one that acts as an all-pass filter where the distortion is zero.The application of filter theory to the evaluation of a machine contour package and its performance permits description in the more convenient language and terminology of the wavenumber domain, rather than that of the space domain. A more important advantage is that the contour package can be subjected to the various standards of filter evaluation such as amplitude and phase response.The practical application, as well as the benefit, of this approach is revealed through the comparison, in both the space and wavenumber domains, of contour maps generated from various machine contour packages.

Seismic Amplitude: Its True"Meaning and Benefit: ABSTRACT

Aapg Bulletin, 1994

THE APPLICATION OF INVERSION TO SEISMIC INTERPRETATION PROBLEMS IN THE FOOTHlLLSt

Norman Christie: The ambassador of Canadian geophysics

Geophysics, 1998

Geophysical Prospecting, 1975

Transactions of The Royal Society of Tropical Medicine and Hygiene, 2008

Burkholderia pseudomallei Disease susceptibility Virulence Vaccine Animal models Summary A range ... more Burkholderia pseudomallei Disease susceptibility Virulence Vaccine Animal models Summary A range of animal models of Burkholderia pseudomallei infection have been reported, and the host species differ widely both in their susceptibility to infection and in the pathogenesis of disease. In mice, and depending on the route of infection, dose, and mouse strain, the disease can range from a chronic, and in some cases, an apparently latent infection to an acute fulminant disease. Alternative small animal models of infection include diabetic rats or hamsters. Larger animal models of disease have not yet been fully developed. It is not clear which of the small animal models of melioidosis most accurately reflect disease in humans. However, the findings that diabetic rats are susceptible to infection, that some strains of mice can develop persistent subclinical infections that can spontaneously reactivate, and that inhalation exposure generally results in more acute disease suggest that these different models mimic different aspects of human melioidosis.

Infection and Immunity, 2007

Burkholderia pseudomallei, the causative agent of melioidosis, is an important human pathogen in ... more Burkholderia pseudomallei, the causative agent of melioidosis, is an important human pathogen in Southeast Asia and northern Australia for which a vaccine is unavailable. A panel of 892 double signature-tagged mutants was screened for virulence using an intranasal BALB/c mouse model of infection. A novel DNA tag microarray identified 33 mutants as being attenuated in spleens, while 6 were attenuated in both lungs and spleens. The transposon insertion sites in spleen-attenuated mutants revealed genes involved in several stages of capsular polysaccharide biosynthesis and DNA replication and repair, a putative oxidoreductase, ABC transporters, and a lipoprotein that may be important in intercellular spreading. The six mutants identified as missing in both lungs and spleens were found to have insertions in recA involved in the SOS response and DNA repair; putative auxotrophs of leucine, threonine, p-aminobenzoic acid, and a mutant with an insertion in aroB causing auxotrophy for aromatic compounds were also found. Murine challenge studies revealed partial protection in BALB/c mice vaccinated with the aroB mutant. The refined signature-tagged mutagenesis approach developed in this study was used to efficiently identify attenuating mutants from this highly pathogenic species and could be applied to other organisms.

The Gilbreths' quality system stands the test of time

Journal of Management History, 2009

Purpose – This paper aims to discuss the work of Frank and Lillian Gilbreth and how it is still a... more Purpose – This paper aims to discuss the work of Frank and Lillian Gilbreth and how it is still a fundamental part of business in the twenty-first century. It is also proposed that the system developed by the Gilbreths could be added as a supplement, or even considered as a replacement to certain modern process management systems. Design/methodology/approach – A qualitative methodology is used and the Gilbreths' system as described in their original works are compared and contrasted with modern process management systems appearing in contemporary literature. Findings – It is found that most modern process management systems are based on the work of the Gilbreths and other seminal thinkers. However, it is suggested that by paying more attention to the human element, the Gilbreths might have developed a more comprehensive system in comparison with current ones. Originality/value – This paper attempts to reemphasize the role and importance of Frank and Lillian's work as foundational to modern process management systems and to suggest that more attention needs to be given to the human interface in such systems.

Atmospheric Environment (1967), 1978

The rates of removal of gaseous SO* over solids commonly found in urban aerosols were measured in... more The rates of removal of gaseous SO* over solids commonly found in urban aerosols were measured in the laboratory. A tubular flow reactor, in which the walls of an inner, concentric cylinder were coated with the solid of interest, was used in these studies. Analysis of the data, using models that specifically accounted for mass transport in the laboratory system, yielded collision efficiencies or the fraction of gas-solid collisions that are effective in removing SO,. Experimentally measured collision efficiencies for freshsolid coatings range from c 10m6 to 10e3. Wet chemical and X-ray photoelectron spectroscopic results indicate that, to within an experimental error ofa factor of 2, gaseous SOz is converted to adsorbed sulfate on most of the solids examined.

Geophysical Prospecting, 1975

Exploration Seismology Volume 1: History, Theory and Data Acquisition

Geoscience Canada, 1984

This book is intended both as a text for students in advanced courses and also as a reference boo... more This book is intended both as a text for students in advanced courses and also as a reference book for persons engaged in seismic exploration. The theoretician and student need to appreciate what is practical, and practitioners need to understand theory and the possibilities it may ...

The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by ... more The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by the focussed on velocity inversion and the generation of derivation of the reflectivity sequence, allows the the pseudo-acoustic log from the seismic trace. ideal pre-conditioning for seismic velocity inverThere are several published methods on wavelet sion. extraction which invariably make assumptions about the wavelet, in terms of the phase spectrum, The significance of this approach is demonstrated as well as assumotions about the reflectivity. in a series of synthetic and real data examoles. The The SONISEIS method will provide the basic statistically computed wavelets allow for synthetic wavelet using a statistical estimation, indepenseismograms which consistently outmatch those dently of any assumptions about the wavelet. The with Ricker or best-estimate zero or minimumderived wavelet is re&ced in the seismic trace phase wavelets, with a spike of approphate amplitude and polarity. ...

Geophysics: Target Shooting for the Drill

While the oil industry was totally familiar with applied geophysics in the 1930’s, it was during ... more While the oil industry was totally familiar with applied geophysics in the 1930’s, it was during the 25-year span following World War II that geophysical technology and expertise underwent substantial development. Major innovations during this period included multifold acquisition, non-dynamite sources, competent marine acquisition, the transition from analog to digital recording and the corresponding emphasis on computer processing. However, geophysical objectives did not change during the same period. Primary targets remained structural traps (including reefs) and the collective development in acquisition and processing technology represented essentially an improvement in data quality. While interpretation techniques remained virtually static, the industry became intoxicated with aesthetic seismic sections and very little attention was paid to what the sections should look like. An elusive butterfly that taunted the industry was the idealistic possibility of using seismic data to ...

Geophysics: Target Shooting for the Drill

Seismic Signal Amplitude and Stratigraphy: Back to the Basics: ABSTRACT

Aapg Bulletin, 1986

THE APPLICATION OF OPTIMAL WAVELETS IN SEISMIC INVERSION

The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by ... more The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by the focussed on velocity inversion and the generation of derivation of the reflectivity sequence, allows the the pseudo-acoustic log from the seismic trace. ideal pre-conditioning for seismic velocity inver- There are several published methods on wavelet sion. extraction which invariably make assumptions about the wavelet, in

Geophysical Prospecting, 1975

With few exceptions, traditional approaches to contouring have been too subjective. Contouring an... more With few exceptions, traditional approaches to contouring have been too subjective. Contouring and contour maps are too often discussed in terms more appropriate to art than to science. With hand contouring there is some justification for this attitude; with machine (i.e. programmed) contouring there is none.Hand contouring is highly susceptible to interpretive judgement and the interpreter is not bound by rigid mathematical constraints. Hence, in allowing for the interpreter's “freedom of expression” it may be difficult to evaluate hand contouring in a totally analytical and objective manner. Machine contouring, however, is based upon mathematical formulation. It is therefore a consistent and objective procedure, ideally suited to objective definition and analysis.It can be demonstrated that the combined process of sampling plus contouring constitutes a two-dimensional filter. The contouring component is that part which introduces “distortion” or wavenumber discrimination. An ideal contour package is one that acts as an all-pass filter where the distortion is zero.The application of filter theory to the evaluation of a machine contour package and its performance permits description in the more convenient language and terminology of the wavenumber domain, rather than that of the space domain. A more important advantage is that the contour package can be subjected to the various standards of filter evaluation such as amplitude and phase response.The practical application, as well as the benefit, of this approach is revealed through the comparison, in both the space and wavenumber domains, of contour maps generated from various machine contour packages.

Seismic Amplitude: Its True"Meaning and Benefit: ABSTRACT

Aapg Bulletin, 1994

THE APPLICATION OF INVERSION TO SEISMIC INTERPRETATION PROBLEMS IN THE FOOTHlLLSt

Norman Christie: The ambassador of Canadian geophysics

Geophysics, 1998

Geophysical Prospecting, 1975

Transactions of The Royal Society of Tropical Medicine and Hygiene, 2008

Burkholderia pseudomallei Disease susceptibility Virulence Vaccine Animal models Summary A range ... more Burkholderia pseudomallei Disease susceptibility Virulence Vaccine Animal models Summary A range of animal models of Burkholderia pseudomallei infection have been reported, and the host species differ widely both in their susceptibility to infection and in the pathogenesis of disease. In mice, and depending on the route of infection, dose, and mouse strain, the disease can range from a chronic, and in some cases, an apparently latent infection to an acute fulminant disease. Alternative small animal models of infection include diabetic rats or hamsters. Larger animal models of disease have not yet been fully developed. It is not clear which of the small animal models of melioidosis most accurately reflect disease in humans. However, the findings that diabetic rats are susceptible to infection, that some strains of mice can develop persistent subclinical infections that can spontaneously reactivate, and that inhalation exposure generally results in more acute disease suggest that these different models mimic different aspects of human melioidosis.

Infection and Immunity, 2007

Burkholderia pseudomallei, the causative agent of melioidosis, is an important human pathogen in ... more Burkholderia pseudomallei, the causative agent of melioidosis, is an important human pathogen in Southeast Asia and northern Australia for which a vaccine is unavailable. A panel of 892 double signature-tagged mutants was screened for virulence using an intranasal BALB/c mouse model of infection. A novel DNA tag microarray identified 33 mutants as being attenuated in spleens, while 6 were attenuated in both lungs and spleens. The transposon insertion sites in spleen-attenuated mutants revealed genes involved in several stages of capsular polysaccharide biosynthesis and DNA replication and repair, a putative oxidoreductase, ABC transporters, and a lipoprotein that may be important in intercellular spreading. The six mutants identified as missing in both lungs and spleens were found to have insertions in recA involved in the SOS response and DNA repair; putative auxotrophs of leucine, threonine, p-aminobenzoic acid, and a mutant with an insertion in aroB causing auxotrophy for aromatic compounds were also found. Murine challenge studies revealed partial protection in BALB/c mice vaccinated with the aroB mutant. The refined signature-tagged mutagenesis approach developed in this study was used to efficiently identify attenuating mutants from this highly pathogenic species and could be applied to other organisms.

The Gilbreths' quality system stands the test of time

Journal of Management History, 2009

Purpose – This paper aims to discuss the work of Frank and Lillian Gilbreth and how it is still a... more Purpose – This paper aims to discuss the work of Frank and Lillian Gilbreth and how it is still a fundamental part of business in the twenty-first century. It is also proposed that the system developed by the Gilbreths could be added as a supplement, or even considered as a replacement to certain modern process management systems. Design/methodology/approach – A qualitative methodology is used and the Gilbreths' system as described in their original works are compared and contrasted with modern process management systems appearing in contemporary literature. Findings – It is found that most modern process management systems are based on the work of the Gilbreths and other seminal thinkers. However, it is suggested that by paying more attention to the human element, the Gilbreths might have developed a more comprehensive system in comparison with current ones. Originality/value – This paper attempts to reemphasize the role and importance of Frank and Lillian's work as foundational to modern process management systems and to suggest that more attention needs to be given to the human interface in such systems.

Atmospheric Environment (1967), 1978

The rates of removal of gaseous SO* over solids commonly found in urban aerosols were measured in... more The rates of removal of gaseous SO* over solids commonly found in urban aerosols were measured in the laboratory. A tubular flow reactor, in which the walls of an inner, concentric cylinder were coated with the solid of interest, was used in these studies. Analysis of the data, using models that specifically accounted for mass transport in the laboratory system, yielded collision efficiencies or the fraction of gas-solid collisions that are effective in removing SO,. Experimentally measured collision efficiencies for freshsolid coatings range from c 10m6 to 10e3. Wet chemical and X-ray photoelectron spectroscopic results indicate that, to within an experimental error ofa factor of 2, gaseous SOz is converted to adsorbed sulfate on most of the solids examined.