bluuebunny/crossref_metadata_2025 huggingface dataset:
Velocity rays for heterogeneous anisotropic media: Theory and implementation
Authors: Iversen Einar
Published: September 2006

The surface of equal two-way time referred to as the isochron is a fundamental concept in seismic imaging. The shape of an isochron depends on the source and receiver locations, on the wave type, and on the parameters constituting the seismic velocity model. A perturbation of a parameter of the velocity model forces the isochron points to move along trajectories called velocity rays, with the selected model parameter as the variable along the rays. Based on earlier work describing first-order approximations to velocity rays, I develop a general theory for velocity rays valid for 3D heterogeneous and anisotropic velocity models. By this theory, velocity rays can be obtained in a way similar to the way conventional rays are computed by numeric integration of a system of ordinary differential equations (ODEs). The process is organized with ODE solvers on two levels, where the upper level is model independent. The lower level includes conventional one-way kinematic and dynamic tracing of source and receiver rays, as well as calculation of ray perturbation quantities. Accurate velocity rays are expected to be useful for perturbation of reflectors mapped from the time domain to the depth domain, for remigration of seismic images in the depth domain, and for velocity model updating.
Drill-bit displacement-source model: Source performance and drilling parameters
Authors: Poletto Flavio , Bellezza Cinzia
Published: September 2006

The emission properties of a drill-bit source and the signature of the drill-bit seismograms depend on the dynamic action of the drill bit, which in turn is a function of the geological conditions, rock properties, and drilling parameters. In fact, drilling is a variable dynamic process, in which the vibrations produced by the drill bit are transmitted into the drillstring and formation with a partition of energy determined by the impedances at the bit. In this analysis, we study drill-bit performance and calculate the forces produced by an ideal drill bit to determine the variations in the signal signature and, ultimately, the conditions of source repeatability as a function of average drilling parameters and signal frequency. The model includes near-field effects and assumes the drill bit acts as a displacement source, producing axial bit forces with relative bit/formation displacement and vertical penetration in the formation. The analysis shows that the expected bit signature, which is equivalent to the ground force in Vibroseis, depends on average tooth impact area, percussion frequency, rate of penetration, formation strength, bit wear, and downhole pressure. In particular, the results show that larger amplitudes of the axial forces are expected at a lower rate of penetration, higher formation strength, and lower formation pressure.
Linearized amplitude variation with offset (AVO) inversion with supercritical angles
Authors: Downton Jonathan E. , Ursenbach Charles
Published: September 2006

Contrary to popular belief, a linearized approximation of the Zoeppritz equations may be used to estimate the reflection coefficient for angles of incidence up to and beyond the critical angle. These supercritical reflection coefficients are complex, implying a phase variation with offset in addition to amplitude variation with offset (AVO). This linearized approximation is then used as the basis for an AVO waveform inversion. By incorporating this new approximation, wider offset and angle data may be incorporated in the AVO inversion, helping to stabilize the problem and leading to more accurate estimates of reflectivity, including density reflectivity.
An expanding-wavefront method for solving the eikonal equations in general anisotropic media
Authors: Wang Yue , Nemeth Tamas , Langan Robert T.
Published: September 2006

We present a procedure that solves the eikonal equation for general anisotropic media. It allows one to incorporate arbitrary shapes and types of anisotropic formations. We use an expanding-wavefront scheme and explicit tracking of group velocity propagation directions to choose the causal upgrade stencils for computing traveltime. The method is of first degree in accuracy and is unconditionally stable. The relative traveltime errors are controlled mainly by initial wavefront formation and by the choice of the update stencils. We illustrate the method’s ability to generate smoothly changing qP traveltimes in models of arbitrary anisotropy.
Computation of dips and azimuths with weighted structural tensor approach
Authors: Luo Yi , Wang Yuchun Eugene , AlBinHassan Nasher M. , Alfaraj Mohammed N.
Published: September 2006

The structural tensor method can be used to compute dips and azimuths (i.e., orientation) encased in seismic data. However, this method may produce erratic and uninterpretable orientations when noisy data are encountered. To overcome this difficulty, we incorporate a data-adaptive weighting function to reformulate the gradient structural tensor. In our experiment, the squared instantaneous power is adopted as the weight factor; this can simplify the computation when the instantaneous phase is used as input. The real data examples illustrate that such a weighting function can produce more interpretable and spatially consistent orientations than conventional approaches.
Tomographic imaging of permafrost using three-component seismic cone-penetration test
Authors: LeBlanc Anne-Marie , Fortier Richard , Cosma Calin , Allard Michel
Published: September 2006

We conducted seismic cone-penetration tests (SCPT) and tomographic imaging in a permafrost mound in northern Quebec, Canada, to study the cryostratigraphy and assess the seismic properties of permafrost at temperatures near [Formula: see text]. A swept impact source generating both P- and S-waves and penetrometer-mounted three-component accelerometers were used to acquire surface-to-depth first-arrival times as input to produce 2D images of P- and S-wave velocities. Based on the three-component accelerometer records and the propagation modes of body waves, the P- and S-wave first arrivals were detected and discriminated. The inversion of the first-arrival times was based on the simultaneous iterative reconstruction technique. The multioffset surface-to-depth geometry used in this study limits the lateral resolution of tomographic imaging. However, the vertical variation in seismic velocities in the permafrost mound shows good reproducibility and can be compared to the cone data. The gathering of cone data such as cone resistance, friction ratio, electrical resistivity, and temperature, along with the seismic velocities, provides new insights into the cryostratigraphy of permafrost. While the cone data are affected by the vertical heterogeneity because of the complex sequence of ice lenses and frozen soil layers of a few centimeters thickness, the smooth velocity variations of P- and S-waves characterized by a wavelength of a few meters depend on the bulk physical properties of permafrost. The P- and S-wave velocities varied from [Formula: see text] and from [Formula: see text], respectively, for a temperature range between [Formula: see text] and [Formula: see text]. At this temperature range, the variations in unfrozen water content are important and affect directly the seismic properties of permafrost. The decrease in P- and S-waves velocities in depth with the permafrost mound depends nonlinearly on the increase of unfrozen water content from 9% to 30% for a temperature increase from [Formula: see text].
Spatial orientation and distribution of reservoir fractures from scattered seismic energy
Authors: Willis Mark E. , Burns Daniel R. , Rao Rama , Minsley Burke , Toksöz M. Nafi , Vetri Laura
Published: September 2006

We present the details of a new method for determining the reflection and scattering characteristics of seismic energy from subsurface fractured formations. The method is based upon observations we have made from 3D finite-difference modeling of the reflected and scattered seismic energy over discrete systems of vertical fractures. Regularly spaced, discrete vertical fracture corridors impart a coda signature, which is a ringing tail of scattered energy, to any seismic waves which are transmitted through or reflected off of them. This signature varies in amplitude and coherence as a function of several parameters including: (1) the difference in angle between the orientation of the fractures and the acquisition direction, (2) the fracture spacing, (3) the wavelength of the illuminating seismic energy, and (4) the compliance, or stiffness, of the fractures. This coda energy is most coherent when the acquisition direction is parallel to the strike ofthe fractures. It has the largest amplitude when the seismic wavelengths are tuned to the fracture spacing, and when the fractures have low stiffness. Our method uses surface seismic reflection traces to derive a transfer function that quantifies the change in an apparent source wavelet before and after propagating through a fractured interval. The transfer function for an interval with no or low amounts of scattering will be more spikelike and temporally compact. The transfer function for an interval with high scattering will ring and be less temporally compact. When a 3D survey is acquired with a full range of azimuths, the variation in the derived transfer functions allows us to identify subsurface areas with high fracturing and to determine the strike of those fractures. We calibrated the method with model data and then applied it to the Emilio field with a fractured reservoir. The method yielded results which agree with known field measurements and previously published fracture orientations derived from PS anisotropy.
Numerical analysis of a narrow-angle, one-way, elastic-wave equation and extension to curvilinear coordinates
Authors: Angus D. A. , Thomson C. J.
Published: September 2006

In this paper, we review the finite-difference implementation of a narrow-angle, one-way vector wave equation for elastic, 3D media. Extrapolation is performed in the frequency domain, where the second-order-accurate lateral spatial-difference operators are sufficiently accurate for narrow-angle propagation. We perform a numerical analysis of the finite-difference scheme to highlight the stability and dispersion characteristics. The von Neumann stability criterion indicates that extracting a reference phase during the extrapolation step noticeably improves the forward marching scheme, and dispersion analysis shows that numerical grid anisotropy is minimal for the propagation path lengths, source pulse spectral content, and angular range of forward propagation of interest. Although the algorithm is reasonable, its computational efficiency is limited by the second-order-accurate extrapolation step; therefore, the extrapolation scheme can be improved. We extend the Cartesian narrow-angle formulation to curvilinear coordinates, where the computational grid tracks the true wavefront in a reference medium and the wavefield derivative normal to the reference wavefront is evaluated locally using the Cartesian propagator. An example of curvilinear extrapolation for a simple model consisting of a high-velocity sphere within a homogeneous background velocity structure shows that the narrow-angle propagator is capable of modeling frequency-dependent geometric spreading and diffraction effects in curvilinear coordinates.
Gravity inversion of basement relief and estimation of density contrast variation with depth
Authors: Silva João B. , Costa Denis C. , Barbosa Valéria C.
Published: September 2006

We present a method to estimate the basement relief as well as the density contrast at the surface and the hyperbolic decaying factor of the density contrast with depth, assuming that the gravity anomaly and the depth to the basement at a few points are known. In both cases, the interpretation model is a set of vertical rectangular 2D prisms whose thicknesses are parameters to be estimated and that represent the depth to the interface separating sediments and basement. The solutions to both problems are stable because of the incorporation of additional prior information about the smoothness of the estimated relief and the depth to the basement at a few locations, presumably provided by boreholes. The method was tested with synthetic gravity anomalies produced by simulated sedimentary basins with smooth relief, providing not only well-resolved estimated relief, but also good estimates for the density contrasts at the surface and for the decaying factors of the density contrast with depth. The method was applied to the Bouguer anomaly from Recôncavo Basin, estimating the surface density contrast and the decaying factor of the density contrast with depth as [Formula: see text] and [Formula: see text], respectively.
Low-frequency dielectric dispersion and microwave dielectric properties of dry and water-saturated limestones of Jodhpur region
Authors: Sengwa R. J. , Soni A.
Published: September 2006

We investigated the complex dielectric constant of 17 different grades of dry and water-saturated limestone samples from the Jodhpur region in the frequency range of [Formula: see text] to [Formula: see text] and also at [Formula: see text] at room temperature. The Cole-Cole dielectric dispersion model was used to compute the values of low-frequency-limit dielectric constant, high-frequency-limit dielectric constant, dielectric strength, and principal value of the relaxation time for each dry limestone sample. The chemical composition, sample bulk density, and porosity of each sample studied were determined to learn which of these factors govern their dielectric parameters. Analysis of the low-frequency dielectric constant confirms that chemical composition and bulk density are the ma-jor factors governing the dielectric constant values; but for water-saturated samples, the frequency-dependent dielectric constant values are also sensitive to porosity and grain size. The ac conductivity of all of the dry samples increases with the increase in frequency from [Formula: see text] to [Formula: see text], but water-saturated samples have comparatively high conductivity; some samples have values independent of the frequency. The microwave dielectric constant of dry samples depends mainly on the amount of the constituents of the oxide, their chemical composition, and sample bulk density. The contribution of the measured dielectric-constant values of each oxide present in the sample is identified by using their density-reduced values of the dielectric constant. The porosity-dependent mixing equations for solid and fluid components of the system were also found suitable for determining the dielectric constant of water-saturated limestone samples at microwave frequency.
The origin of the observed low-frequency electrical polarization in sandstones
Authors: Scott Julian B.
Published: September 2006

There has been an increasing debate regarding the mechanism controlling the low-frequency polarization (megahertz to kilohertz) in sandstones. The polarization and related electrical relaxation are extremely important because they can be used to provide a significant amount of information on length scales within the sandstone. Complex electrical measurements, in the mHz to kHz range, were made on gel-filled samples. This gel decreases the ionic mobility in the bulk pore fluid while keeping the ionic composition similar to that in a water-saturated sample. The presence of the gel was shown to have little effect on the electrical relaxation. This adds to the argument that the electrical double layer close to the grain surface is where the polarization originates. The correlation between pore-throat size and the relaxation time is consistent with the polarization mechanism of ion diffusion within the electrical double layer. The membrane-type polarization model, used previously to explain the polarization in pore-throat regions, is likely to be incorrect because of the relative thinness of the electrical double layer.
3D seismic refraction traveltime tomography at a groundwater contamination site
Authors: Zelt Colin A. , Azaria Aron , Levander Alan
Published: September 2006

We have applied traveltime tomography to 3D seismic refraction data collected at Hill Air Force Base, Utah, in an approximately [Formula: see text] area over a shallow [Formula: see text] groundwater contamination site. The purpose of this study is to test the ability of 3D first-arrival-time data to characterize the shallow environment and aid remediation efforts. The aquifer is bounded below by a clay aquiclude, into which a paleochannel has been incised and acts as a trap for dense nonaqueous phase liquid (DNAPL) contaminants. A regularized nonlinear tomographic approach was applied to [Formula: see text] first-arrival traveltimes to obtain the smoothest minimum-structure 3D velocity model. The resulting velocity model contains a velocity increase from less than [Formula: see text] in the upper [Formula: see text]. The model also contains a north-south-trending low-velocity feature interpreted to be the paleochannel, based on more than 100 wells in the area. Checkerboard tests show [Formula: see text] lateral resolution throughout most of the model.

The preferred final model was chosen after a systematic test of the free parameters involved in the tomographic approach, including the starting model. The final velocity model compares favorably with a 3D poststack depth migration and 2D waveform inversion of coincident reflection data. While the long-wavelength features of the model reveal the primary target of the survey, the paleochannel, the velocity model is likely a very smooth characterization of the true velocity structure, particularly in the vertical direction, given the size of the first Fresnel zone for these data.
Small-angle AVO response of PS-waves in tilted transversely isotropic media
Authors: Behura Jyoti , Tsvankin Ilya
Published: September 2006

Field records for small source-receiver offsets often contain intensive converted PS-waves that may be caused by the influence of anisotropy on either side of the reflector. Here, we study the small-angle reflection coefficients of the split converted [Formula: see text]- and [Formula: see text]-waves ([Formula: see text] and [Formula: see text]) for a horizontal interface separating two transversely isotropic (TI) media with arbitrary orientations of the symmetry axis.

The normal-incidence reflection coefficients [Formula: see text] and [Formula: see text] vanish when both half-spaces have a horizontal symmetry plane, which happens if the symmetry axis is vertical or horizontal (i.e., if the medium is VTI or HTI). For a tilted symmetry axis in either medium, however, the magnitude of the reflection coefficients can reach substantial values that exceed 0.1, even if the anisotropy strength is moderate. To study the influence exerted by the orientation of the symmetry axis and the anisotropy parameters, we develop concise weak-contrast, weak-anisotropyapproximations for the PS-wave reflection coefficients and com-pare them with exact numerical results. In particular, the analytic solutions show that the contributions made by the Thomsen parameters [Formula: see text] and [Formula: see text] and the symmetry-axis tilt [Formula: see text] to the coefficients [Formula: see text] and [Formula: see text] can be expressed through the first derivative of the P-wave phase velocity at normal incidence. If the symmetry-axis orientation and anisotropy parameters do not change across the interface, the normal-incidence reflection coefficients are insignificant, regardless of the strength of the velocity and density contrast. The AVO (amplitude variation with offset) gradients of the PS-waves are influenced primarily by the anisotropy of the incidence medium that causes shear-wave splitting and determines the partitioning of energy between the [Formula: see text] and [Formula: see text] modes.

Because of their substantial amplitude, small-angle PS reflections in TI media contain valuable information for anisotropic AVO inversion of multicomponent data. Our analytic solutions provide a foundation for linear AVO-inversion algorithms and can be used to guide nonlinear inversion that is based on the exact reflection coefficients.
Q(z) model building using walkaway VSP data
Authors: Guerra Rafael , Leaney Scott
Published: September 2006

Advanced seismic processing applications that use inverse [Formula: see text]-filtering for enhanced seismic resolution and true amplitude processing require reliable [Formula: see text] earth models. While interval [Formula: see text] may be accurately estimated by zero offset VSP surveys, quality data are obtained over relatively limited depth intervals, and shallower well sections pose special problems because of hole size, multiple casings, and lack of cementation. To obtain a more complete [Formula: see text] model, we have developed a theoretical method for combining zero offset VSP [Formula: see text] measurements with either effective-[Formula: see text] measurements from walkaway VSP surveys or surface seismic common midpoint (CMP) gathers.

Using a simple crustal model of isotropic and homogenous flat layers, we derive an analytical result for the effective-[Formula: see text] measured from walkaway VSP surveys or from CMP gathers. We have found that effective-[Formula: see text] approaches a weighted harmonic mean ⟨[Formula: see text] of the overburden interval [Formula: see text]-values for short source-receiver offsets. This new method allows [Formula: see text] models to be constructed from the surface down to the total depth of the well, or even deeper, by combining offset-dependent effective-[Formula: see text] measurements with depth-dependent interval [Formula: see text] estimates from zero-offset VSP. The technique is also a simple method of compensating surface seismic gathers for anelastic [Formula: see text] absorption in an offset-dependent and time-variant way. We tested our new method using both synthetic data and walkaway and zero-offset VSP field data from the North Sea.
A reusable implosive seismic source for midwater or seafloor use
Authors: Dorman LeRoy M. , Sauter Allan W.
Published: September 2006

We have developed a new implosive seismic or acoustic source for seafloor or midwater use. The fact that this device does not use pyrotechnics simplifies logistic and permitting problems. It produces relatively little high-frequency output, so it is wildlife friendly. This device enables us to place the source nearer to the image target compared to surface sources, which thus increases resolution. The simple [Formula: see text] version we have constructed must be reset after each use by bringing it to the sea surface. We present measurements of seafloor shear velocity at a depth of about [Formula: see text] in the San Diego Trough. There the surficial shear velocity is [Formula: see text], and the gradient is about [Formula: see text].
Mapping fractures with GPR: A case study from Turtle Mountain
Authors: Theune Ulrich , Rokosh Dean , Sacchi Mauricio D. , Schmitt Douglas R.
Published: September 2006

Ground-penetrating radar (GPR) surveys were acquired of rocks on the highly fractured summit of Turtle Mountain in Canada. In 1903 a disastrous rock slide occurred at Turtle Mountain and it still poses a geologic hazard. Dips, shapes, and penetration depths of fractures are important parameters in slope-stability analysis. Determination of fracture orientation at Turtle Mountain has been based mostly on areal geologic mapping and, most recently, on data collected from boreholes. The purpose of GPR surveys was to test, confirm, and extend information about fractures and bedding planes. Data acquisition was complicated by the rough terrain; because slopes are steep and uneven. This also complicated analysis of the data. Measurement of in situ velocity — an important value for migration — was impossible. Instead, data were migrated with different velocities and data results were chosen that were considered to be reasonable. Analysis and interpretation of the data, resulted in confirmation and extension of the a priori information on orientations of fractures and bedding planes at Turtle Mountain. Despite the rough terrain and highly fractured rock mass, GPR surveys provide reliable information about the shapes and density of fractures — information important for slope-stability evaluation. The most reliable migration results obtained for velocities were considerably less than the standard velocities recorded for limestone, the dominant lithofacies at Turtle Mountain. We interpret this observation as an indicator of water within the rock. However, thorough investigation of this conclusion remains a project for future work.
Time-domain inversion of GPR data containing attenuation due to conductive losses
Authors: Di Qingyun , Zhang Meigen , Wang Maioyue
Published: September 2006

Many seismic data processing and inversion techniques have been applied to ground-penetrating radar (GPR) data without including the wave field attenuation caused by conductive ground. Neglecting this attenuation often reduces inversion resolution. This paper introduces a GPR inversion technique that accounts for the effects of attenuation. The inversion is formulated in the time domain with the synthetic GPR waveforms calculated by a finite-element method (FEM). The Jacobian matrix can be computed efficiently with the same FEM forward modeling procedure. Synthetic data tests show that the inversion can generate high-resolution subsurface velocity profiles even with data containing strong random noise. The inversion can resolve small objects not readily visible in the waveforms. Further, the inversion yields a dielectric constant that can help to determine the types of material filling underground cavities.
Porosity inference and classification of siliciclastic rocks from multiple data sets
Authors: Loures Luiz G. , Moraes Fernando S.
Published: September 2006

We develop a Bayesian formulation for joint inference of porosity and clay volume, incorporating multiple data sets, prior information, and rock physics models. The derivation is carried out considering the full uncertainty involved in calculations from unknown hyperparameters required by either rock physics equations (model coefficients) or statistical models (data variances). Eventually, data variances are marginalized in closed form, and the model coefficients are fixed using a calibration procedure. To avoid working with a high-dimension probability density function in the parameter space, our formulation is derived and implemented using a moving window along the data domain. In thisway, we compute a collection of 2D posterior distributions forinterval porosity and clay volume, corresponding to each positionalong the window’s path. We test the methodology on both synthetic and real well logs consisting of gamma-ray, neutron, compressional and shear sonic velocity, and density. Tests demonstrate that integrating the relevant pieces of information about porosity and clay volume reduces the uncertainties associated with the estimates. Error analysis of a synthetic data example shows that neutron and density logs provide more information about porosity, whereas gamma-ray logs and velocities provide more information about clay volume. Additionally, we investigate a change in fluid saturation as a source of systematic error in porosity prediction. A real data example, incorporating porosity measurements on core samples, further demonstrates the consistency of our methodology in reducing the uncertainties associated with our final estimates.
MDM2 Promoter Polymorphism Is Associated With Both an Increased Susceptibility to Gastric Carcinoma and Poor Prognosis
Authors: Ohmiya Naoki , Taguchi Ayumu , Mabuchi Nobuyuki , Itoh Akihiro , Hirooka Yoshiki , Niwa Yasumasa , Goto Hidemi
Published: September 2006

Purpose

Recently, a single-nucleotide polymorphism in the MDM2 promoter (SNP309) has been found to lower the age of onset of tumors and increase the occurrence of multiple primary tumors in Li-Fraumeni syndrome, and accelerate the development of sporadic adult soft tissue sarcoma. The aim of this study was to determine whether SNP309 is associated with susceptibility to gastric carcinoma and its prognosis.

Patients and Methods

In a case-control study including 438 controls and 410 patients with sporadic gastric carcinoma, MDM2 SNP309 was genotyped. Serum pepsinogens (PGs) I and II were measured in 438 control subjects and 253 cases selected from 410 patients. Tumor tissue was immunostained with p53 and examined for mutations in exons 5 to 8 of p53 using polymerase chain reaction–based single strand conformational polymorphism analysis and direct sequencing.

Results

The risk of overall gastric carcinoma for SNP309 (G/G) was significantly increased when compared with T carriers (P = .039), especially carcinomas with extragastric tumors (P = .005), carcinoma with severe atrophic gastritis positive for PG assay (PG I level < 70 ng/mL and PG I/II < 3.0; P = .005), antral carcinoma (P = .020), intestinal-type carcinoma (P = .023), p53-immunopositive carcinoma (P = .007), and carcinoma with p53 mutations (P = .007). No significant difference in age at diagnosis was observed among genotypes. SNP309 (G/G) was an independent marker of poor overall survival in advanced carcinoma (hazard ratio, 3.16; 95% CI, 1.22 to 8.20; P = .018).

Conclusion

This study provides evidence supporting the association of SNP309 with gastric carcinogenesis via p53 tumor suppressor pathway, extragastric tumorigenesis, and poor prognosis.
Designing Dose-Escalation Trials With Late-Onset Toxicities Using the Time-to-Event Continual Reassessment Method
Authors: Normolle Daniel , Lawrence Theodore
Published: September 2006

Purpose

The standard design for phase I trials of combined chemotherapy and radiation, which enters either three or six patients per dose level, has little statistical basis and is subject to opening and closing because of delayed toxicities that disrupt patient accrual. We compared the operating characteristics of this standard design and the time-to-event continual reassessment method (TITE-CRM) for dose-escalation trials of combination chemotherapy and radiation.

Methods

The operating characteristics were determined by Monte Carlo simulation of 60,000 phase I trials.

Results

Compared with the standard trial design, in studies with delayed toxicity (ie, where four or more patients are expected to enter onto the study during a single previously enrolled patient's observation for toxicity), TITE-CRM trials are significantly shorter when toxicity observation times are long, treat more patients at or above the maximum-tolerated dose, identify the maximum-tolerated dose (MTD) more accurately, and provide phase II information, but do not expose patients to significant additional risk. Estimation precision and overdose control of TITE-CRM increase as the design assumptions more closely resemble the true state of nature, but are reduced if, for instance, the toxicity of treatment has been grossly underestimated.

Conclusion

Compared with the standard design, if there is any prior knowledge concerning the toxicity profile of a treatment, TITE-CRM can leverage it to produce more accurate estimates of the MTD and does not expose patients to significant excess risk, but requires timely communication between clinical investigators, data managers, and study statisticians.
Simultaneous Chemoradiotherapy Compared With Radiotherapy Alone After Induction Chemotherapy in Inoperable Stage IIIA or IIIB Non–Small-Cell Lung Cancer: Study CTRT99/97 by the Bronchial Carcinoma Therapy Group
Authors: Huber Rudolf M. , Flentje Michael , Schmidt Michael , Pöllinger Barbara , Gosse Helga , Willner Jochen , Ulm Kurt
Published: September 2006

Purpose

The aim of this study was to examine whether, after preceding induction chemotherapy, simultaneous chemoradiotherapy is superior to radiotherapy alone.

Patients and Methods

Patients with non–small-cell lung cancer in inoperable stage IIIA or IIIB received induction chemotherapy with two cycles of paclitaxel 200 mg/m2 and carboplatin area under the curve 6 every 3 weeks. Patients without progression at restaging after induction chemotherapy were randomly assigned to radiotherapy (60 Gy) or chemoradiotherapy (paclitaxel 60 mg/m2 weekly). The primary end point was overall survival; secondary end points were time to progression, response, and toxicity.

Results

Three hundred three patients entered the study, and 276 completed induction chemotherapy. Two hundred fourteen patients were randomly assigned (radiotherapy alone: n = 113; simultaneous chemoradiotherapy: n = 101). Median follow-up time of all randomly assigned patients was 13.6 months (interquartile range [IQR], 6.4 to 29.0 months), and median follow-up time of the subgroup of censored patients (n = 52) was 37.4 months (IQR, 5.9 to 57.0 months; maximum, 76.1 months). Toxicities during the induction phase were mild. During radiotherapy, overall toxicity rates were not significantly different between the two arms. Median survival times in the radiotherapy group and chemoradiotherapy group were 14.1 months (95% CI, 11.8 to 16.3 months) and 18.7 months (95% CI, 14.1 to 23.3 months; difference not statistically significant, P = .091). Median time to progression significantly favored simultaneous chemoradiotherapy (11.5 months; 95% CI, 8.3 to 14.7 months) versus radiotherapy alone (6.3 months; 95% CI, 5.0 to 7.6 months; P < .001, log-rank test).

Conclusion

Induction chemotherapy followed by chemoradiotherapy with weekly paclitaxel is feasible. Response, time to progression, and survival favor chemoradiotherapy compared with radiotherapy alone.
Delayed Nausea and Vomiting Continue to Reduce Patients' Quality of Life After Highly and Moderately Emetogenic Chemotherapy Despite Antiemetic Treatment
Authors: Bloechl-Daum Brigitte , Deuson Robert R. , Mavros Panagiotis , Hansen Mogens , Herrstedt Jørn
Published: September 2006

Purpose

Chemotherapy-induced nausea and vomiting (CINV) are major adverse effects of cancer chemotherapy. We compared the impact of acute (during the first 24 hours postchemotherapy) and delayed (days 2 through 5 postchemotherapy) CINV on patients' quality of life (QoL) after highly or moderately emetogenic chemotherapy (HEC and MEC, respectively).

Patients and Methods

This prospective, multicenter, multinational study was conducted in 14 medical practices on cancer patients undergoing either HEC or MEC treatment. Patients recorded episodes of nausea and vomiting in a diary. Patients completed the Functional Living Index-Emesis (FLIE) questionnaire at baseline and on day 6.

Results

A total of 298 patients were assessable (67 HEC patients, 231 MEC patients). Emesis was reported by 36.4% of patients (13.2% acute, 32.5% delayed) and nausea by 59.7% (36.2% acute, 54.3% delayed). HEC patients reported significantly lower mean FLIE total score than MEC patients (95.5 v 107.8 respectively; P = .0049). Among all patients, the nausea score was significantly lower than the vomiting score (50.0 and 55.3, respectively; P = .0097). Of the 173 patients who experienced neither vomiting nor nausea during the first 24 hours postchemotherapy, 22.9% reported an impact of CINV on daily life caused by delayed CINV.

Conclusion

CINV continues to adversely affect patients' QoL despite antiemetic therapy even after treatment with only moderately emetogenic chemotherapy regimens, and even in the subgroup of patients who do not experience nausea and vomiting during the first 24 hours. On the basis of the FLIE results in this study, nausea had a stronger negative impact on patients' daily lives than vomiting.
Diabetes and Cardiovascular Disease During Androgen Deprivation Therapy for Prostate Cancer
Authors: Keating Nancy L. , O'Malley A. James , Smith Matthew R.
Published: September 2006

Purpose

Androgen deprivation therapy with a gonadotropin-releasing hormone (GnRH) agonist is associated with increased fat mass and insulin resistance in men with prostate cancer, but the risk of obesity-related disease during treatment has not been well studied. We assessed whether androgen deprivation therapy is associated with an increased incidence of diabetes and cardiovascular disease.

Patients and Methods

Observational study of a population-based cohort of 73,196 fee-for-service Medicare enrollees age 66 years or older who were diagnosed with locoregional prostate cancer during 1992 to 1999 and observed through 2001. We used Cox proportional hazards models to assess whether treatment with GnRH agonists or orchiectomy was associated with diabetes, coronary heart disease, myocardial infarction, and sudden cardiac death.

Results

More than one third of men received a GnRH agonist during follow-up. GnRH agonist use was associated with increased risk of incident diabetes (adjusted hazard ratio [HR], 1.44; P < .001), coronary heart disease (adjusted HR, 1.16; P < .001), myocardial infarction (adjusted HR, 1.11; P = .03), and sudden cardiac death (adjusted HR, 1.16; P = .004). Men treated with orchiectomy were more likely to develop diabetes (adjusted HR, 1.34; P < .001) but not coronary heart disease, myocardial infarction, or sudden cardiac death (all P > .20).

Conclusion

GnRH agonist treatment for men with locoregional prostate cancer may be associated with an increased risk of incident diabetes and cardiovascular disease. The benefits of GnRH agonist treatment should be weighed against these potential risks. Additional research is needed to identify populations of men at highest risk of treatment-related complications and to develop strategies to prevent treatment-related diabetes and cardiovascular disease.
Confidence and Uncertainty Long After Initial Treatment for Early Prostate Cancer: Survivors' Views of Cancer Control and the Treatment Decisions They Made
Authors: Clark Jack A. , Talcott James A.
Published: September 2006

Purpose

The many years most men diagnosed with early prostate cancer live after diagnosis allow evolving assessments of their cancer control and their treatment choices, but little is known of these outcomes or the factors that influence them.

Patients and Methods

We surveyed an established, prospective cohort that had initiated treatment for early prostate cancer 4 to 8 years previously. We assessed perceived cancer control, quality of treatment decisions, and other domains of quality of life, along with treatment-related urinary, bowel, and sexual dysfunction.

Results

Most men reported high confidence in cancer control and their treatment decisions, but many reported misgivings about one or both. The diagnostic, treatment, and quality-of-life factors associated with these two outcomes were distinct. Perceived cancer control was lower among those with adverse medical factors: higher pretreatment Gleason scores, subsequent rises in prostate-specific antigen (PSA), and secondary androgen ablation therapy. Confidence in treatment decisions was unrelated to these factors and was higher in men who opted for radical prostatectomy or brachytherapy, reported close attention to current PSA, had high masculine self-esteem and little distress from sexual dysfunction, and were married.

Conclusion

Although perceptions of cancer control and the quality of their treatment decisions are linked, men can distinguish between these two outcomes. They incorporate objective indicators of high risk and adverse outcomes when assessing their cancer control; confidence in treatment decisions represents a more complex psychosocial adjustment to the persistent uncertainty that originates with their diagnosis.
Less Toxicity by Optimizing Chemotherapy, but Not by Addition of Granulocyte Colony-Stimulating Factor in Children and Adolescents With Acute Myeloid Leukemia: Results of AML-BFM 98
Authors: Creutzig Ursula , Zimmermann Martin , Lehrnbecher Thomas , Graf Norbert , Hermann Johann , Niemeyer Charlotte M. , Reiter Alfred , Ritter Jörg , Dworzak Michael , Stary Jan , Reinhardt Dirk
Published: September 2006

Purpose

To improve prognosis in children with acute myeloid leukemia (AML) by randomized comparisons of (1) two short consolidation cycles versus the Berlin-Frankfurt-Muenster (BFM) -type biphasic 6-week consolidation and (2) the prophylactic administration of granulocyte colony-stimulating factor (G-CSF) versus no G-CSF. Further, therapy for standard risk patients was intensified by addition of a second induction, HAM (high-dose cytarabine and mitoxantrone).

Patients and Methods

Four hundred seventy-three patients younger than 18 years with de novo AML were enrolled in trial AML-BFM 98. Patients received five courses of intensive chemotherapy, cranial irradiation, and 1-year maintenance therapy.

Results

Four hundred eighteen patients (88%) achieved remission. Compared with trial AML-BFM 93, early deaths decreased from 7.4 to 3.2% (P = .005), and 5-year overall survival increased from 58% to 62% (log-rank P = .03). Both types of consolidation therapy led to similar outcome (event-free survival, 51% v 50%), but in the two-cycle arm, treatment duration was shorter (median duration, 15 days), and treatment related mortality was lower (five v nine patients). G-CSF shortened neutropenia, but did not reduce the rate of severe infections. Intensification of induction therapy did not improve prognosis of standard-risk patients (event-free survival, 62% v 67%).

Conclusion

Overall results were improved by neither the administration of G-CSF nor by cycle therapy; however, the latter was easier to perform. Compared with study AML-BFM 93, therapy intensification with HAM in standard-risk patients did not result in improved prognosis. Future treatment designs have to balance intensification of treatment with higher toxicity, improve supportive care, and to consider alternative treatment strategies.
Elderly Patients Benefit From Second-Line Cytotoxic Chemotherapy: A Subset Analysis of a Randomized Phase III Trial of Pemetrexed Compared With Docetaxel in Patients With Previously Treated Advanced Non–Small-Cell Lung Cancer
Authors: Weiss Glen J. , Langer Corey , Rosell Rafael , Hanna Nasser , Shepherd Frances , Einhorn Lawrence H. , Nguyen Binh , Paul Sofia , McAndrews Patrick , Bunn Paul A. , Kelly Karen
Published: September 2006

Purpose

Numerous prospective and retrospective studies have concluded that elderly patients (≥ 70 years old) achieve a similar survival benefit, with acceptable toxicity, from first-line cytotoxic chemotherapy for the treatment of advanced non–small-cell lung cancer (NSCLC) compared with their younger counterparts. However, few published data exist on the efficacy and tolerability of second-line cytotoxic therapy in this population.

Patients and Methods

Retrospective analysis of a large second-line trial was performed. Data from 571 patients randomly assigned to docetaxel 75 mg/m2 or pemetrexed 500 mg/m2 every 3 weeks were analyzed for efficacy and toxicity comparisons between age groups and treatment arms.

Results

Eighty-six of 571 patients (15%) were ≥ 70 years old, similar to rates of elderly observed in the first-line setting. Elderly patients receiving pemetrexed (n = 47) or docetaxel (n = 39) had a median survival of 9.5 and 7.7 months compared with 7.8 and 8.0 months for younger patients receiving pemetrexed (n = 236) or docetaxel (n = 249), respectively. Elderly patients treated with pemetrexed had a longer time to progression and a longer survival than their counterpart patients treated with docetaxel (not statistically significant). Febrile neutropenia was less frequent in elderly patients treated with pemetrexed (2.5%) compared with docetaxel (19%; P = .025), with only one death as a result of toxicity (docetaxel arm).

Conclusion

Elderly patient participation was similar to rates observed in the first-line setting. There was no significant difference in outcome or toxicity between elderly and younger patients. For elderly patients with advanced NSCLC and good performance status, second-line cytotoxic therapy is appropriate. In this subset, pemetrexed produced a more favorable toxicity profile.
Phase II Trial of Lomustine Plus Temozolomide Chemotherapy in Addition to Radiotherapy in Newly Diagnosed Glioblastoma: UKT-03
Authors: Herrlinger Ulrich , Rieger Johannes , Koch Dorothee , Loeser Simon , Blaschke Britta , Kortmann Rolf-Dieter , Steinbach Joachim P. , Hundsberger Thomas , Wick Wolfgang , Meyermann Richard , Tan Ta-Chih , Sommer Clemens , Bamberg Michael , Reifenberger Guido , Weller Michael
Published: September 2006

Purpose

To evaluate toxicity and efficacy of the combination of lomustine, temozolomide (TMZ) and involved-field radiotherapy in patients with newly diagnosed glioblastoma (GBM).

Patients and Methods

Thirty-one adult patients (median Karnofsky performance score 90; median age, 51 years) accrued in two centers received involved-field radiotherapy (60 Gy in 2-Gy fractions) and chemotherapy with lomustine 100 mg/m2 (day 1) and TMZ 100 mg/m2/d (days 2 to 6) with individual dose adjustments according to hematologic toxicity.

Results

A median of five courses (range, one to six courses) were delivered. WHO grade 4 hematotoxicity was observed in five patients (16%) and one of these patients died as a result of septicemia. Nonhematologic toxicity included one patient with WHO grade 4 drug-induced hepatitis (leading to discontinuation of lomustine and TMZ) and one patient with WHO grade 2 lung fibrosis (leading to discontinuation of lomustine). The progression-free survival (PFS) rate at 6 months was 61.3%. The median PFS was 9 months (95% CI, 5.3 to 11.7 months), the median overall survival time (MST) was 22.6 months (95% CI, 12.5 to not assessable), the 2-year survival rate was 44.7%. O6-Methylguanine–DNA methyltransferase (MGMT) gene-promoter methylation in the tumor tissue was associated with longer PFS (P = .014, log-rank test) and MST (P = .037).

Conclusion

The combination of lomustine, TMZ, and radiotherapy had acceptable toxicity and yielded promising survival data in patients with newly diagnosed GBM. MGMT gene-promoter methylation was a strong predictor of survival.
Aerodynamic optimization design of centrifugal compressor's impeller with Kriging model
Authors: Wang X-F , Xi G , Wang Z-H
Published: September 2006

In the modern design system of centrifugal impellers, numerical simulations by computational fluid dynamics (CFD) have played a vital role. Despite the rapid growth in computer capability and the maturation of CFD software, the optimization design of centrifugal impellers, which rely fully on numerical simulations, is currently impractical due to the large computational costs required. An approximation model can be applied to overcome this obstacle. This article investigates the application of the Kriging model in the optimization of a centrifugal impeller. First, the feasibility of the Kriging model is verified by a test function and a measure to improve the accuracy of solution is proposed. Following this, on the basis of the impeller's parametric modelling, the Kriging model method is applied to the optimization of a typical industrial centrifugal impeller. It is found that the isentropic efficiency at the design point is increased by 2.49 per cent, and a distinct improvement is made in the flow inside the impeller.
Optimization of steam boiler design
Authors: Bojić M , Dragićević S
Published: September 2006

As energy and equipment costs increase, optimal production of steam becomes economically more important in the industry. In this investigation, a linear programming model has been developed to optimize the performance of a steam boiler by minimizing its total life-cycle costs. For different types of fuel, costs of fuel, investment, and production of steam, the model predicts the optimal size of the entire steam boiler and its parts. Investigations show that this approach may maximally yield savings of up to 30 per cent.