bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison between permeability anisotropy and elasticity anisotropy of reservoir rocks
Authors: Rasolofosaon Patrick N. J. , Zinszner Bernard E.
Published: October 2002

We developed new experimental and theoretical tools for the measurement and the characterization of arbitrary elasticity tensors and permeability tensors in rocks. They include an experimental technique for the 3‐D visualization of hydraulic invasion fronts in rock samples by monitoring the injection of salt solutions by X‐ray tomography, and a technique for inverting the complete set of the six coefficients of the permeability tensor from invasion front images. In addition, a technique for measuring the complete set of the 21 elastic coefficients, a technique allowing the identification and the orientation in the 3‐D space of the symmetry elements (planes, axes), and a technique for approximating the considered elastic tensor by a tensor of simpler symmetry with the quantification of the error induced by such an approximation have been developed.

We apply these tools to various types of reservoir rocks and observed quite contrasted behaviors. In some rocks, the elastic anisotropy and the hydraulic anisotropy are closely correlated, for instance in terms of the symmetry directions. This is the case when elastic anisotropy and hydraulic anisotropy share the same cause (e.g., layering, fractures). In contrast, in some other rocks, hydraulic properties and elastic properties are clearly uncorrelated. These results highlight the challenge we have to face in order to estimate the rock permeability and to monitor the fluid flow from seismic measurements in the field.
Estimating rock porosity and fluid saturation using only seismic velocities
Authors: Berryman James G. , Berge Patricia A. , Bonner Brian P.
Published: October 2002

Evaluation of the fluid content in deep earth reservoirs or fluid contaminants in shallow earth environments has required the use of geophysical imaging methods such as seismic reflection prospecting. Interpretation of seismic velocities and amplitudes is based on theories of fluid‐saturated and partially saturated rocks that have been available since the 1950s. Here we present a new synthesis of the same physical concepts that uses compressional‐wave velocities together with shear‐wave velocities in a scheme that is much simpler to understand and apply yet yields detailed information about porosity and fluid saturation magnitudes and spatial distribution. The key idea revolves around the fact that the density and the Lamé elastic parameter λ are the only two parameters determining seismic velocities that also contain information about fluid saturation. At low enough frequencies, Gassmann's well‐known equations show that the shear modulus is independent of the fluid saturation level. We use these facts to construct saturation‐proxy and data‐sorting plots from seismic velocity data. The new method does not require reflectivity data, although it can use such information if available. The method can therefore be applied to a wide range of source–receiver configurations, including seismic reflection profiling (surface to surface), vertical seismic profiling (well to surface), and cross‐well seismic transmission tomography (well to well), since availability of reflection data is not a requirement.
Real time quasi–2-D inversion of array resistivity logging data using neural network
Authors: Zhang Zhiyi , Zhou Zhiqiang
Published: October 2002

We present a quasi-2-D real-time inversion algorithm for a modern galvanic array tool via dimensional reduction and neural network simulation. Using reciprocity and superposition, we apply a numerical focusing technique to the unfocused data. The numerically focused data are much less subject to 2-D and layering effects and can be approximated as from a cylindrical 1-D earth. We then perform 1-D inversion on the focused data to provide approximate information about the 2-D resistivity structure. A neural network is used to perform forward modeling in the 1-D inversion, which is several hundred times faster than conventional numerical forward solutions. Testing our inversion algorithm on both synthetic and field data shows that this fast inversion algorithm is useful for providing formation resistivity information at a well site.
The boundary element method for 3‐D dc resistivity modeling in layered earth
Authors: Ma Qinzhong
Published: October 2002

The integral equation for dc resistivity modeling of 3‐D inhomogeneous bodies buried in a layered earth is derived by using Green's theorem. The main features of this method are (1) the layers above and below the 3‐D object can be included, (2) multiple subsurface inhomogeneous bodies can be embedded in the different layers, and (3) the boundary element method (BEM) is used to solve the integral equation using triangular surface elements. Linear variation of the electrical properties is assumed within each element. The potential on the ground surface is obtained by solving the linear equation system with Gaussian elimination.

Model calculations demonstrate that the results obtained by this method compare well with the analytical solution of a sphere in a uniform half‐space and the asymptotic behavior for the solution of a buried body beneath a surficial layer as the layer resistivity approaches that of the half‐space. A comparison of responses over elongate 3‐D bodies with responses over 2‐D bodies of identical cross‐section also shows satisfactory agreement.
Books—War Victims
Authors: Shaffer K. R.
Published: October 2002

During the war, the libraries of half the world were destroyed in the fires of battle and in the fires of hate and fanaticism. Where they were spared physical damage, they were impoverished by isolation. There is an urgent need—now—for the printed materials which are basic to the reconstruction of devastated areas and which can help to remove the intellectual blackout of Europe and the Orient.
Discussions on Induced Polarization: Authors’ Second Reply
Authors: Frische Richard H. , Von Buttlar Haro
Published: October 2002

We have received a copy of W.’s second discussion on the induced polarization problem. After reading it thoroughly, our position is unchanged. The aquifer is not a “linear medium” because the motions of the ions are essentially different with and without electric field. Therefore, values for the dielectric constant calculated on the decay part of the curves do not have to agree with the ones calculated from the magnitude of the induced polarization signal.
Reply by Dr. Rosenbach
Authors: Rosenbach Otto
Published: October 2002

The errors involved in the second derivative coefficient sets of Elkins and myself are not as divergent as one would expect from the respective standard deviation figures, [Formula: see text] and [Formula: see text], given by the authors of the discussion.
Reply by authors to discussion by H. A. Meinardus
Authors: Berg J. W. , Odegard M. E.
Published: October 2002

The following items pertain to the comments made by Mr. Meinardus about the paper.
Reply by author to discussion by Hubert Guyod.
Authors: Worthington A. E.
Published: October 2002

The purpose of this paper is to make available a practical, rapid, relatively inexpensive, and reasonably accurate method of measuring cation exchange capacity (CEC) of oil‐field rocks. There is no dearth of sound, detailed descriptions of how this information should be used by explorationists to enhance their ability to interpret resistivity and SP logs in shaly sands (see references in Introduction). Waxman and Thomas (1972) have subsequently published additional information on the application to oil‐saturated shaley sands. Smits (1969) has confirmed the role of CEC in shales, a matter not considered in this paper.
Reply to N. C. Steenland by the authors
Authors: Pilkington Mark , Crossley D. J.
Published: October 2002

We welcome the chance to respond to the comments by Steenland on our two recent papers. Let us first acknowledge the gap that exists between geophysical practice, discussed by Steenland, and geophysics research development of the type presented in our papers. It is correct, healthy, and inevitable that such a gap should exist and yet understandable that not all techniques get transferred (as a successful example, take use of log spectral density which, while problematical from an analytical point of view, is widely used to ascertain depth to sources; Spector and Grant, 1970). On the other hand, we are reluctant to concede defeat in our case (and this applies to a host of similar theoretical studies of potential‐field interpretation) simply on the basis of there being limitations to the theory. Where theoretical demonstrations of a new technique are found to be practically useful, they will be adopted (often with appropriate modifications) by the industry; a good example is the use of Werner deconvolution, quoted by Steenland. Even where their limitations prevent this, theoretical developments often show the way for future studies.
Reply by the authors to I. Késmárky
Authors: Hajnal Zoltan , Serada Ivan T.
Published: October 2002

We appreciate Mr. Kérmárky’s deep interest in our paper. The points he raised are based on the implementation of error analysis to a specific, well‐defined exploration experiment. We agree that under these conditions, when high‐quality data, after a sophisticated processing sequence, permit the assumption of a horizontal layered‐earth model, small random time shifts can be foreseen as the major source of error in velocity estimation. In these cases, computing the variance of the interval velocity is more likely sufficient.
Reply by the author to L. Eskola
Authors: Sampaio Edson E. S.
Published: October 2002

The paper by Eskola and Tervo (1980) actually does not discuss or compute any case where there is a magnetic contrast between the air and the country rock, so I maintain my statement; however, this is in no way a criticism to the above‐mentioned paper.
Reply by the authors to S. H. Danbom and S. N. Domenico
Authors: Krail P. M. , Brysk H.
Published: October 2002

There is no real contradiction between our paper and Danbom and Domenico’s comments. There is not much overlap in subject matter and, as a consequence, there is an obvious difference of emphasis. All of us adhere to the basic concept of the seismic method that a quantitative analysis of the measured reflection amplitudes can deduce the material parameters of the earth layers and reveal the likely presence of hydrocarbons. We also realize that common midpoint gathers at different offsets contain more information in this respect than a stacked section.
Reply by the author to Christopher Juhlin
Authors: Burnett R. C.
Published: October 2002

I thank Christopher Juhlin for his comments and appreciate his modeling which supports my conclusions, something my original modeling failed to do. As a result I have run some additional models and while some of the results are similar to Juhlin’s, there are some differences. For the models shown here, I have listed the P‐wave and shear‐wave velocities to eliminate any ambiguities associated with Poisson’s ratio, after being convinced by Thomson (1990) to return to the term [Formula: see text].
Reply by the author to Peter Hood
Authors: Hardwick C. D.
Published: October 2002

The paper acknowledged that military‐type compensators have been used in geophysical exploration to produce useful vertical gradient maps. In fact, at NAE we flew a CAE nine‐term compensator (9‐TC), the type referred to by Dr. Hood, in a four‐engine North Star aircraft from 1964 to 1976, and many thousand line‐miles of total field survey were flown for the GSC with this system. Excellent in‐band compensations were always obtainable. However, the compensated dc value of the total field varied from compensation to compensation over a range of 40 nT. This was before the GSC’s Bourget calibration facility became operational, and we had no way of knowing when or if the correct value of compensated total field had been obtained. Furthermore, the compensation procedure required considerable flying, particularly if no a priori knowledge of the compensator settings was assumed.
On: “Wave Propagation in heterogeneous, porous media: A velocity‐stress, finite difference method,” by N. Dai, A. Vafidis, and E. R. Kanasewich (March‐April 1995 GEOPHYSICS, p. 327–340).
Authors: Gurevich Boris
Published: October 2002

In their interesting paper the authors present a new advanced approach to the simulation of seismic wave propagation in media described by Biot’s theory of dynamic poroelasticity in two dimensions. The algorithm developed can be used to accurately simulate the effect of dynamic poroelasticity on seismic wavefields over hydrocarbon reservoirs. In cases where this effect proves significant this algorithm can be incorporated in the seismic modeling technology.
Reply by the authors to J. M. Mendel
Authors: Bamberger A.
Published: October 2002

We thank Professor Mendel for his remarks about our paper “Inversion of normal incidence seismograms.” First of all, we used the word “uncertainty” as (perhaps inexact) translation for the French “incertitude”, which is currently used in engineering circles to denote an upper bound on the first order estimate of the error on any physical quantity. Hence the [Formula: see text] and the [Formula: see text] are always positive, and equations (6) and (9) in our paper are right.
Reply by the author to the Discussion by J. M. Mendel
Authors: Ziolkowski Anton
Published: October 2002

I thank Professor Mendel for his comments on my paper. I first examine his model of the seismogram and show that losses in the earth cannot be convolutional. I then examine the structure of his “reflectivity sequence” and show that this cannot be random. I suggest that the theory of probability, random variables and stochastic processes is not applicable to our non‐random seismic data. I suggest that we need, and use, a definition of whiteness in geophysics which comes from optics. Finally I show that none of the methods I am proposing for the determination of the source signature relies on the earth being loss‐free.
Fast Frechet derivative calculation using an auxiliary source array method: An application to array resistivity measurements
Authors: Wang Tsili , Mezzatesta Alberto
Published: October 2002

Frechet derivatives provide the vital information for parametric resistivity inversion, but the calculation for a multidimensional problem is often computer intensive. This paper presents a new technique for fast calculation of the Frechet derivatives of resistivity measurements with respect to formation resistivity properties. The technique, referred to as the auxiliary source array method (ASAM), generalizes the reciprocity principle‐based methods in that for closely spaced receivers it may not be necessary to place a fictitious source at each receiver location. Rather, an auxiliary source array comprised of sparsely spaced fictitious sources can be constructed from which the field for any fictitious source location can be reconstructed. The ASAM was tested with a deviated‐well resistivity model for an array resistivity device that acquires 8 potential, 16 first potential difference, and 14 second potential difference data points at each depth level. The Frechet derivatives calculated by the ASAM agree well with those obtained through the parameter perturbation method. The tests showed that the calculation time of the ASAM has little dependence on the number of parameters for which the Frechet derivatives are to be calculated. The method can calculate the Frechet derivatives of 5 to 138 resistivity parameters with only 20% to 50% additional computer time. For the 138‐parameter model, the ASAM is about two orders of magnitude faster than the parameter perturbation method.
Direct inversion of the apparent complex‐resistivity spectrum
Authors: Xiang J. , Jones N. B. , Cheng D. , Schlindwein F. S.
Published: October 2002

Cole‐Cole model parameters are widely used to interpret electrical geophysical methods and are obtained by inverting the induced polarization (IP) spectrum. This paper presents a direct inversion method for parameter estimation based on multifold least‐squares estimation. Two algorithms are described that provide optimal parameter estimation in the least‐squares sense. Simulations demonstrate that both algorithms can provide direct apparent spectral parameter inversion for complex resistivity data. Moreover, the second algorithm is robust under reasonably high noise.
Imaging refractors with the convolution section
Authors: Palmer Derecke
Published: October 2002

Seismic refraction data are characterized by large moveouts between adjacent traces and large amplitude variations across the refraction spread. The moveouts are the result of the predominantly horizontally traveling trajectories of refraction signals, whereas the amplitude variations are the result of the rapid geometric spreading factor, which is at least the reciprocal of the distance squared. The large range of refraction amplitudes produces considerable variation in signal‐to‐noise (S/N) ratios. Inversion methods which use traveltimes only, employ data with a wide range of accuracies, which are related to the variations in the S/N ratios. The time section, generated by convolving forward and reverse seismic traces, addresses both issues of large moveouts and large amplitude variations. The addition of the phase spectra with convolution effectively adds the forward and reverse traveltimes. The convolution section shows the structural features of the refractor, without the moveouts related to the source‐to‐detector distances. Unlike the application of a linear moveout correction or reduction, a measure of the refractor wavespeed is not required beforehand. The multiplication of the amplitude spectra with convolution, compensates for the effects of geometric spreading and dipping interfaces to a good first approximation, and it is sufficient to facilitate recognition of amplitude variations related to geologic causes. These amplitude effects are not as easily recognized in the shot records. The convolution section can be generated very rapidly from shot records without a detailed knowledge of the wavespeeds in either the refractor or the overburden.
Comparison of standard horizontal geophones and newly designed horizontal detectors
Authors: Sambuelli L. , Deidda G. P. , Albis G. , Giorcelli E. , Tristano G.
Published: October 2002

To increase the speed and efficiency of shallow seismic SH‐wave data recording and to decrease acquisition costs, we have designed, constructed, and tested a new velocity tool that detects horizontal movements better than standard horizontal geophones. A comparative evaluation of significant characteristics and field performances of this new detector was conducted through laboratory and field tests on two sets of receivers: one consisting of 24 prototypes of the new detector and the other consisting of 24 standard horizontal geophones. Laboratory measurements revealed similar behaviors of impedance curves and geophone responses for the two types of detectors, but the impedance amplitudes and the frequency‐response amplitudes of the new detector were twice those of the standard geophones. However, comparison of the horizontal‐to‐vertical (response) ratios, proved that the new detector better discriminates (6 dB on average) between the horizontal and vertical excitements. Field data proved that the energy, the maximum amplitude in the trace, and the maximum reflected amplitude were always higher in the data recorded with the new detector, although only half the source energy was used. The extra cost and weight of the new detector should be outweighed by its advantages, such as higher sensitivity to horizontal motions, better energy efficiency, and greater cost effectiveness. When a wavefield can be interpreted as SH‐waves, SH‐wave records can be acquired without the traditional drawbacks such as acquiring two records in each shot position, preprocessing of each record, and the final trace‐to‐trace subtraction needed to produce a pure SH‐wave record.
Efficient calculation of a partial‐derivative wavefield using reciprocity for seismic imaging and inversion
Authors: Shin Changsoo , Yoon Kwangjin , Marfurt Kurt J. , Park Keunpil , Yang Dongwoo , Lim Harry Y. , Chung Seunghwan , Shin Sungryul
Published: October 2002

Linearized inversion of surface seismic data for a model of the earth’s subsurface requires estimating the sensitivity of the seismic response to perturbations in the earth’s subsurface. This sensitivity, or Jacobian, matrix is usually quite expensive to estimate for all but the simplest model parameterizations. We exploit the numerical structure of the finite‐element method, modern sparse matrix technology, and source‐receiver reciprocity to develop an algorithm that explicitly calculates the Jacobian matrix at only the cost of a forward model solution. Furthermore, we show that we can achieve improved subsurface images using only one inversion iteration through proper scaling of the image by a diagonal approximation of the Hessian matrix, as predicted by the classical Gauss‐Newton method. Our method is applicable to the full suite of wave scattering problems amenable to finite‐element forward modeling. We demonstrate our method through some simple 2‐D synthetic examples.
Factors affecting the success of building management system installations
Authors: Lowry G
Published: October 2002

It is widely reported that building management systems (BMS) are not fully utilized. The failure to exploit the potential of these systems leads to sub-optimal performance of building services plant in terms of both energy consumption and the maintenance of internal building conditions. In this paper the variation in BMS use, and the perceptions of BMS users are examined in a questionnaire survey of industry-based personnel. The results show that BMS are most successful in their role as plant control systems, with the more strategic functions remaining under-utilized. The significant factors associated with the success of BMS installations are user involvement in the specification, the user's perception of the performance of the BMS vendor, and satisfactory commissioning of the system.
Assessment criteria in a large-scale writing test: what do they really mean to the raters?
Authors: Lumley Tom
Published: October 2002

The process of rating written language performance is still not well understood, despite a body of work investigating this issue over the last decade or so (e.g., Cumming, 1990; Huot, 1990; Vaughan, 1991; Weigle, 1994a; Milanovic et al., 1996). The purpose of this study is to investigate the process by which raters of texts written by ESL learners make their scoring decisions using an analytic rating scale designed for multiple test forms. The context is the Special Test of English Proficiency ( step), which is used by the Australian government to assist in immigration decisions. Four trained, experienced and reliable step raters took part in the study, providing scores for two sets of 24 texts. The first set was scored as in an operational rating session. Raters then provided think-aloud protocols describing the rating process as they rated the second set. A coding scheme developed to describe the think-aloud data allowed analysis of the sequence of rating, the interpretations the raters made of the scoring categories in the analytic rating scale, and the difficulties raters faced in rating.

Data show that although raters follow a fundamentally similar rating process in three stages, the relationship between scale contents and text quality remains obscure. The study demonstrates that the task raters face is to reconcile their impression of the text, the specific features of the text, and the wordings of the rating scale, thereby producing a set of scores. The rules and the scale do not cover all eventualities, forcing the raters to develop various strategies to help them cope with problematic aspects of the rating process. In doing this they try to remain close to the scale, but are also heavily influenced by the complex intuitive impression of the text obtained when they first read it. This sets up a tension between the rules and the intuitive impression, which raters resolve by what is ultimately a somewhat indeterminate process. In spite of this tension and indeterminacy, rating can succeed in yielding consistent scores provided raters are supported by adequate training, with additional guidelines to assist them in dealing with problems. Rating requires such constraining procedures to produce reliable measurement.
The systemic inflammatory response syndrome following cardiac surgery: different expression of proinflammatory cytokines and procalcitonin in patients with and without multiorgan dysfunctions
Authors: Sablotzki Armin , Friedrich Ivar , Mühling Jörg , Dehne Marius G , Spillner Jan , Silber Rolf E , Czeslik Elke
Published: October 2002

Cardiopulmonary bypass is associated with an injury that may cause pathophysiological changes in the form of systemic inflammatory response syndrome (SIRS) or multiple organ dysfunction syndrome (MODS). In the present study, we investigated the inflammatory response of patients with multiple organ dysfunctions following open-heart surgery. Plasma levels of cytokines (IL-1β, IL-6, IL-8, IL-18) and procalcitonin (PCT) were measured on the first four postoperative days in 12 adult male patients with SIRS and two or more organ dysfunctions after myocar-dial revascularization (MODS group), and 15 patients without organ dysfunctions (SIRS group). All cytokines (except IL-1β) and PCT were significantly elevated in MODS patients, with peak values at the first two postoperative days. The results of our study show a different expression of members of the IL-1 family following extracorporeal circulation. For the first time, we can document that IL-18 is involved in the inflammatory response and the initiation of the MODS following cardiopulmonary bypass. In addition to APACHE-II score, PCT, IL-8, and IL-18 may be used as parameters for the prognosis of patients with organ dysfunctions after cardiac surgery. Furthermore, it must be noted that the duration of the surgical procedure is one of the most important factors for the initiation of the inflammatory response.
Depression in palliative care: a systematic review. Part 2. Treatment
Authors: Ly Kelly Lan , Chidgey Jayne , Addington-Hall Julia , Hotopf Matthew
Published: October 2002

Objective: To summarize available literature containing data on the treatment of depression in palliative care patients.

Methods: A systematic review was conducted using extensive electronic databases and hand searches. All randomized controlled trials (RCTs) of interventions for depression in patients with advanced disease were eligible.

Results: Three RCTs assessed pharmacological treatments. Of these, two were placebo controlled and assessed mianserin and thioridazine. The third compared two antidepressants. There were no RCTs that specifically assessed psychotherapy for patients with depression.

Conclusion: There are too few adequate studies to draw clear conclusions about management of depression in this setting. The treatment of depression in patients with advanced disease must, for now, be informed by the larger body of evidence on effective treatments for depression in patients with either no physical illness or less severe medical conditions.
High-resolution multiproxy climatic records from ice cores, tree-rings, corals and documentary sources using eigenvector techniques and maps: assessment of recovered signal and errors
Authors: Fisher David A.
Published: October 2002

Palaeotemperature sensitive series from tree-rings, ice cores, corals and documentary sources are combined to producepalaeo summer-temperaturereconstructions (AD 1970-1761)and geographical eigenvector (EOF) maps in both hemispheres. They are compared favourably to those of existing summer-temperature average series. There are 51 palaeoseries in the Northern Hemisphere (mostly north of 40° N) and 16 series in the Southern Hemisphere. The statistics and significance of the palaeoreconstructions are examined by: (1) finding the correlation coefficient (palaeo to measured) as a function of the number and geographical distribution of the palaeo series; (2) developing and running a multiproxy model that generates pseudo series containing a signal and the same types and amounts of noise found in the various real palaeo series. The model reproduces the measured correlation coefficients and the eigenvector's (EOF) explained variances as functions of the number of sites. About 77% of the signal variance can be recovered with 51 well-distributed palaeo series and about 90% with greater than 100 series. The 1st eigenvector (EOF l) component maps in the Northern and Southern Hemispheres are fundamentally different, with the Northern having much less longitudinal variation than the Southern. This means (statistically) that simple hemispheric averages of summer temperature have more meaning in the Northern Hemisphere than in the Southern. Even though the various palaeoseries have different spectral biases, noise types and amounts, they were all used together and the common signal extracted. The results of this work strongly suggest that the multiproxy method is valid and that with enough sites most of the summer signal and geographical pattern can be extracted.
The environmental impact of the Minoan eruption of Santorini (Thera): statistical analysis of palaeoecological data from Golbisar, southwest Turkey
Authors: Eastwood W. J. , Tibby J. , Roberts N. , Birks H. J.B. , Lamb H. F.
Published: October 2002

A tephra layer originating from the mid-second millennium BC (3300 14C yr BP) ‘Minoan’ eruption of Santorini (or Thera) in the Aegean has been found in lake sediments at G6lhisar in southwest Turkey. Microstratigraphic analyses of tephra shard concentration (TSC), pollen, diatoms, sponge spicules and nonsiliceous microfossils in sediments from Gtlhisar permit the impact of this major volcanic eruption on terrestrial and aquatic biota to be investigated quantitatively. Partial redundancy analysis and associated Monte Carlo permutation tests suggest that TSC alone cannot be shown to have had a demonstrable independent and statistically significant effect on terrestrial pollen, non-siliceous microfossil or diatom assemblages. The lack of any clear, discernible change in the terrestrial pollen composition following tephra deposition suggests that there was minimal impact on regional vegetation over decadal-to-century timescales. However, evidence that the deposition of Santorini tephra may have had an impact on the lake system comes from the combined effect of lithology and TSC (which significantly covary) that explains a significant amount of variance in the aquatic data sets. In particular, diatoms and non-siliceous algae show increases in concentration following tephra deposition, exhibiting what appear to be decadal response times to perturbation. These imply enhanced lake productivity due to accelerated input of silica and other nutrients following tephra dissolution.
Inferences about population means of health care costs
Authors: Zhou Xiao-Hua
Published: October 2002

The analysis of health care costs is complicated by the skewed and heteroscedastic nature of their distribution with possibly additional zero values. Statistical methods that do not adjust for these features can lead to incorrect conclusions. This paper reviews recent developments in statistical methods for the analysis of health care costs; our focus is on population means.
Capecitabine: a novel, orally administered, tumour-activated treatment for colorectal cancer
Authors: Summerhayes Maxwell
Published: October 2002

Objective. To provide a comprehensive review of the preclinical and clinical pharmacology and toxicology of the fluoropyrimidine, capecitabine, with particular reference to its use in its new indication, advanced colorectal cancer.

Data sources. A MEDLINE search was conducted using the term ‘‘capecitabine’’ for the period 1995 -2001. The reference lists from retrieved articles were reviewed and other relevant papers identified. The abstract books from the annual meetings of the American Society of Clinical and Oncology and the European Society of Medical Oncology were also reviewed.

Data extraction. The aim of the review was to be comprehensive and descriptive. All studies containing information deemed to be of interest were reviewed by the author, none were excluded on grounds of quality.

Data synthesis. Capecitabine is a prodrug of the widely used cytotoxic agent 5-fluorouracil (5-FU). Unlike 5-FU it is extensively and reliably absorbed after oral administration and does not require folinate (FA) potentiation. Activation of capecitabine is a three-step enzymatic process. The final activating enzyme, thymidine phosphorylase, is found in unusually high concentrations in many solid tumours, resulting in preferential delivery of 5-FU to tumour tissues, including that of colorectal cancers, suggesting therapeutic potential in this malignancy. Large, randomized trials have demonstrated that capecitabine fulfils this potential—compared with the widely used ‘‘Mayo’’ regimen of intravenous 5-FU and folinic acid, oral capecitabine (1250 mg/m2 twice daily) produced a superior response rate and a similar time to disease progression and duration of survival. It was also better tolerated than 5-FU/FA—of seven common fluoropyrimidine-induced toxicities, four were significantly less common with capecitabine. Capecitabine also produced significantly less grade 4 toxicity or toxicity requiring hospitalization, though the hand -foot syndrome that characterizes prolonged, continuous exposure to 5-FU was more common after capecitabine.
Baton rounds
Authors: Hunter Simon , Greaves Ian
Published: October 2002

Baton rounds are the final step in a graded response to civil disturbance and have recently been adopted for use on the British mainland. Designed to be a less lethal weapon, they are still responsible for serious injuries and deaths. A review of the literature is presented covering the ballistics, demographics, and injuries resulting from the use of baton rounds and offering some specific management guidelines. The recent developments in baton round design and guidelines for use are described and the problems of terminology with plastic bullets are examined.
Fitting exponential family mixed models
Authors: Palmgren Juni , Ripatti Samuli
Published: October 2002

The generalized linear model (McCullagh and Nelder, 1972) and the semiparametric multiplicative hazard model (Cox, 1972) have significantly influenced the way in which statistical modelling is taught and practiced. Common for the two model families is the assumption that conditionally on covariate information (including time) the observations are independent. The obvious difficulty in identifying and measuring all relevant covariates has pushed for methods that can jointly handle both mean and dependence structures. The early 1990s saw a myriad of approaches for dealing with multivariate generalized linear models. More recently, the hazard models have been extended to multivariate settings. Here we review (i) penalized likelihood, (ii) Monte Carlo EM, and (iii) Bayesian Markov chain Monte Carlo methods for fitting the generalized linear mixed models and the frailty models, and we discuss the rationale for choosing between the methods. The similarities of the toolboxes for these two multivariate model families open up for a new level of generality both in teaching and applied research. Two examples are used for illustration, involving censored failure time responses and Poisson responses, respectively.
A life table approach to small area health need profiling
Authors: Congdon Peter
Published: October 2002

Recent developments in health outcome models for small areas have found benefits from pooling information over areas to produce smoothed estimates of mortality and morbidity rates. Such indices serve as proxies for the need for health care and are often used in allocating health care resources. The present paper adopts a full life table approach to such outcomes, which includes the joint modelling of mortality and health variation between small areas. A further feature of the approach here is random effects modelling of age-specific death and wellness rates, so pooling strength in estimating life table parameters for areas, such as healthy and total life expectancies, which may be based on small event counts. The basic model involves exchangeable random effects for age and area. However, structured forms of variation considered include correlations between mortality and health, spatial correlation in these outcomes, and interrelatedness in age effects. A case study illustration uses deaths and long-term illness data to develop small area life tables for two London boroughs, and includes a temporal perspective on deaths. It then considers the utility of area life table measures in predicting health activity, providing a form of validation in addition to formal statistical cross-validation.
Adjuvant Tamoxifen Prescription in Women 65 Years and Older With Primary Breast Cancer
Authors: Silliman Rebecca A. , Guadagnoli Edward , Rakowski William , Landrum Mary Beth , Lash Timothy L. , Wolf Robert , Fink Aliza , Ganz Patricia A. , Gurwitz Jerry , Borbas Catherine , Mor Vincent
Published: October 2002

PURPOSE: We examined patterns of adjuvant tamoxifen discussion and prescription among breast cancer patients age 65 years and older.

METHODS: We selected from women diagnosed with primary breast cancer those with (1) stage I (tumor diameter ≥ 1 cm), stage II, or stage IIIa disease; (2) age 65 years or older on the date of diagnosis; and (3) permission from the attending physician to contact. Data were collected from consenting patients’ medical records, telephone interviews with patients, and mailed questionnaires completed by their physicians.

RESULTS: We obtained medical record and interview data for 698 patients. The oldest patients (odds ratio [OR], 0.45; 95% confidence interval [CI], 0.23 to 0.87 for those aged 80+ relative to those aged 65 to 69 years old), those with more comorbid conditions (each additional comorbid condition reduced the odds of discussion by 0.84; 95% CI, 0.73 to 0.96), and those who were estrogen receptor–negative (OR, 0.56; 95% CI, 0.32 to 0.99) were less likely to report discussion of tamoxifen therapy with a physician. Older patients (OR, 2.17; 95% CI, 1.18 to 4.01 for 70- to 79-year-olds relative to 65- to 69-year-olds; OR, 2.44; 95% CI, 1.11 to 5.34 for those aged 80+ relative to those aged 65 to 69 years old), those who reported a greater influence of information about tamoxifen on decision-making (an increase in 1 SD increased the odds by 7.43; 95% CI, 4.36 to 12.65), and those whose physicians believed that the benefits of tamoxifen outweighed its risks (an increase in 1 SD increased the odds by 1.87; 95% CI, 1.34 to 2.62) were more likely to be prescribed tamoxifen.

CONCLUSION: These findings highlight the key role of communication in the care of older women with breast cancer and its ultimate influence on the receipt of therapy.
Phase I Evaluation of Prolonged-Infusion Gemcitabine With Irinotecan for Relapsed or Refractory Leukemia or Lymphoma
Authors: Bass Adam J. , Gockerman Jon P. , Hammett Eve , DeCastro Carlos M. , Adams David J. , Rosner Gary L. , Payne Nancy , Davis Patti , Foster Traci , Moore Joseph O. , Rizzieri David A.
Published: October 2002

PURPOSE: To estimate the maximum-tolerated duration of infusion of gemcitabine at 10 mg/m2/min in combination with irinotecan at 40 mg/m2 daily for 3 days in the treatment of relapsed or refractory acute leukemia or lymphoma.

PATIENTS AND METHODS: Patients with leukemia or lymphoma were escalated in separate strata. Stratum I consisted of 11 patients, median age of 47 years (range, 18 to 68 years), with relapsed or refractory leukemia. Stratum II contained nine patients, median age of 48 years (range, 39 to 68 years), who had refractory non-Hodgkin’s lymphoma. Patients received irinotecan at 40 mg/m2 daily for 3 days, beginning just before the first dose of gemcitabine. Gemcitabine was given at 10 mg/m2/min, with the total duration adjusted following a modified continuous reassessment model.

RESULTS: Severe myelosuppression and stomatitis/esophagitis were the most serious hematologic and nonhematologic toxicities. Several patients developed febrile neutropenia, nausea, or vomiting. In both strata, the maximum recommended duration of infusion of gemcitabine was 12 hours delivered at 10 mg/m2/min (7,200 mg/m2). The overall response rate for one cycle of this therapy in this phase I trial for patients with leukemia was 18% (95% confidence interval, 8% to 45%), and for those with lymphoma, 33% (95% confidence interval, 17% to 66%).

CONCLUSION: A prolonged infusion of gemcitabine at 10 mg/m2/min for 12 hours with 3 days of irinotecan at 40 mg/m2/d is a tolerable induction regimen for patients with acute leukemia or lymphoma. Stomatitis/esophagitis should be anticipated; however, this regimen may induce responses in patients with difficult-to-treat hematologic malignancies.
Randomized, Controlled Trial of Written Emotional Expression and Benefit Finding in Breast Cancer Patients
Authors: Stanton Annette L. , Danoff-Burg Sharon , Sworowski Lisa A. , Collins Charlotte A. , Branstetter Ann D. , Rodriguez-Hanley Alicia , Kirk Sarah B. , Austenfeld Jennifer L.
Published: October 2002

PURPOSE: Expressing emotions and finding benefits regarding stressful experiences have been associated in correlational research with positive adjustment. A randomized trial was performed to compare effects of experimentally induced written emotional disclosure and benefit finding with a control condition on physical and psychological adjustment to breast cancer and to test whether outcomes varied as a function of participants’ cancer-related avoidance.

PATIENTS AND METHODS: Early-stage breast cancer patients completing medical treatment were assigned randomly to write over four sessions about (1) their deepest thoughts and feelings regarding breast cancer (EMO group; n = 21), (2) positive thoughts and feelings regarding their experience with breast cancer (POS group; n = 21), or (3) facts of their breast cancer experience (CTL group; n = 18). Psychological (eg, distress) and physical (perceived somatic symptoms and medical appointments for cancer-related morbidities) outcomes were assessed at 1- and 3-month follow-ups.

RESULTS: A significant condition × cancer-related avoidance interaction emerged on psychological outcomes; EMO writing was relatively effective for women low in avoidance, and induced POS writing was more useful for women high in avoidance. Significant effects of experimental condition emerged on self-reported somatic symptoms (P = .0183) and medical appointments for cancer-related morbidities (P = .0069). Compared with CTL participants at 3 months, the EMO group reported significantly decreased physical symptoms, and EMO and POS participants had significantly fewer medical appointments for cancer-related morbidities.

CONCLUSION: Experimentally induced emotional expression and benefit finding regarding early-stage breast cancer reduced medical visits for cancer-related morbidities. Effects on psychological outcomes varied as a function of cancer-related avoidance.
Multicenter Randomized Phase III Trial Comparing Protracted Venous Infusion (PVI) Fluorouracil (5-FU) With PVI 5-FU Plus Mitomycin in Inoperable Pancreatic Cancer
Authors: Maisey Nick , Chau Ian , Cunningham David , Norman Andrew , Seymour Matt , Hickish Tamas , Iveson Tim , O’Brien Mary , Tebbutt Niall , Harrington Angela , Hill Mark
Published: October 2002

PURPOSE: To compare protracted venous infusion (PVI) fluorouracil (5-FU) with PVI 5-FU plus mitomycin (MMC) in patients with advanced pancreatic cancer in a multicenter, prospectively randomized study.

PATIENTS AND METHODS: Two hundred eight patients were randomized to PVI 5-FU (300 mg/m2/d for a maximum of 24 weeks) or PVI 5-FU plus MMC (7 mg/m2 every 6 weeks for four courses). The major end points were tumor response, survival, toxicity, and quality of life (QOL).

RESULTS: The two treatment groups were balanced for baseline demographic factors, and 62% had metastatic disease. The overall response rate was 8.4% (95% confidence interval [CI]) 3.2% to 13.7% for patients treated with PVI 5-FU alone compared with 17.6%; 95% CI 10.3% to 25.1% for PVI 5-FU plus MMC (P = .04). Median failure-free survival was 2.8 months for PVI 5-FU and 3.8 months for PVI 5-FU plus MMC (P = .14). Median survival was 5.1 months for PVI 5-FU and 6.5 months for PVI 5-FU plus MMC (P = .34). Toxicities in both arms were mild. There was an increased incidence of neutropenia in the 5-FU plus MMC arm (P < .01), although no differences in infection were seen. No patients developed hemolytic uremic syndrome. Global QOL improved significantly after 24 weeks of treatment compared with baseline for patients receiving 5-FU plus MMC, although there was no statistically significant difference in QOL between arms.

CONCLUSION: PVI 5-FU plus MMC resulted in a superior response rate in comparison with PVI 5-FU alone in advanced pancreatic cancer, but this did not translate into a survival advantage. These results emphasize the importance of chemotherapy in this setting and the continuing value of the fluoropyrimidines in pancreatic cancer.
Prognostic Value of Tumoral Thymidylate Synthase and p53 in Metastatic Colorectal Cancer Patients Receiving Fluorouracil-Based Chemotherapy: Phenotypic and Genotypic Analyses
Authors: Etienne Marie-Christine , Chazal Maurice , Laurent-Puig Pierre , Magné Nicolas , Rosty Christophe , Formento Jean-Louis , Francoual Mireille , Formento Patricia , Renée Nicole , Chamorey Emmanuel , Bourgeon André , Seitz Jean-François , Delpero Jean-Robert , Letoublon Christian , Pezet Denis , Milano Gérard
Published: October 2002

PURPOSE: The aim of this multicenter prospective study was to evaluate the role of intratumoral parameters related to fluorouracil (FU) sensitivity in 103 metastatic colorectal cancer patients receiving FU–folinic acid.

PATIENTS AND METHODS: Liver metastatic biopsy specimens were obtained for all patients and primary tumor biopsy specimens for 54 patients. Thymidylate synthase (TS), folylpolyglutamate synthetase, and dihydropyrimidine dehydrogenase were measured by radioenzymatic assays; TS promoter polymorphism (2R/2R v 2R/3R v 3R/3R) was determined by polymerase chain reaction; and p53 protein and mutations were analyzed by immunoluminometric assay and denaturing gradient gel electrophoresis, respectively.

RESULTS: p53 mutations were observed in 56.7% of metastases. TS activity was significantly higher in 2R/3R tumors as compared with 2R/2R or 3R/3R. TS activity in metastasis was the only parameter linked to clinical responsiveness (responders exhibited the lower TS, P = .047). Univariate Cox analyses demonstrated that TS activity in primary tumor (the greater the TS, the poorer the survival; P = .040), TS promoter polymorphism in primary tumor (risk of death of 2R/3R v 2R/2R, 2.68; P = .035), and p53 stop mutation in metastasis (risk of death of stop mutations v wild type, 3.14; P = .018) were the only significant biologic predictors of specific survival. Stepwise analysis did not discriminate between TS activity and TS polymorphism.

CONCLUSION: Present results confirm the value of tumoral TS activity for predicting FU responsiveness, point out the importance of detailed p53 mutation analysis for predicting survival, and suggest that TS genotype in primary tumor carries a prognostic value similar to that of TS activity.