bluuebunny/crossref_metadata_2025 huggingface dataset:
3D 3-C full-wavefield elastic inversion for estimating anisotropic parameters: A feasibility study with synthetic data
Authors: Chang Hui , McMechan George
Published: December 2009

Traveltime-based inversions cannot solve for all of the anisotropy parameters for orthorhombic media. Vertical velocities cannot be recovered simultaneously with the dimensionless anisotropy parameters. Also, the density cannot be solved because it does not affect the normal moveout of P and S reflections. These limitations can be overcome using full-wavefield inversion for anisotropy parameters for orthorhombic media and for transversely isotropic media with vertical and horizontal symmetry axes. Tsvankin’s parameters and the orientation of the local (anisotropic) coordinates are inverted from three-component, wide-azimuth data sets containing P reflected and PS converted waves. The inversions are performed in two steps. The first step uses only reflections from the top of an anisotropic layer, whichdoes not constrain the trade-offs between the vertical velocities, the anisotropies, and density, as shown by parameter correlation analysis. The results from the first step are refined by using them as the starting model for the second step, which fits reflections from the top and bottom of the layer. The properties of the target layer influence the amplitudes of top and bottom reflections as well as the traveltime of the bottom reflections; when all these data are used, the inversion is highly overdetermined and all model parameters are estimated accurately. When Gaussian noise is added, the inversion results are very similar to those for the noise-free data because only the coherent signal is fitted. The residual at convergence for the noisy data corresponds to the noise level. Concurrent inversion of data from multiple sources increases the azimuthal illumination of a target.
Three-dimensional frequency-domain full-waveform inversion with an iterative solver
Authors: Plessix René-Édouard
Published: December 2009

With the acquisition of wide-aperture seismic data sets, full-waveform inversion is an attractive method for deriving velocity models. Three-dimensional implementations require an efficient solver for the wave equation. Computing 3D time-harmonic responses with a frequency-domain solver is complicated because a large linear system with negative and positive eigenvalues must be solved. Time-domain schemes are an alternative. Nevertheless, existing frequency-domain iterative solvers with an efficient preconditioner are a viable option when full-waveform inversion is formulated in the frequency domain. An iterative solver with a multigrid preconditioner is competitive because of a high-order spatial discretization. Numerical examples illustrated the efficiency of the iterative solvers. Three dimensional full-waveform inversion was then studied in the context of deep-water ocean-bottom seismometer acquisition. Three dimensional synthetic data inversion results showed the behavior of full-waveform inversion with respect to the initial model and the minimum frequency available in the data set. Results on a 3D real ocean-bottom seismometer data set demonstrated the relevance of full-waveform inversion, especially to image the shallow part of the model.
Nonstationary phase estimation using regularized local kurtosis maximization
Authors: van der Baan Mirko , Fomel Sergey
Published: December 2009

Phase mismatches sometimes occur between final processed seismic sections and zero-phase synthetics based on well logs — despite best efforts for controlled-phase acquisition and processing. Statistical estimation of the phase of a seismic wavelet is feasible using kurtosis maximization by constant-phase rotation, even if the phase is nonstationary. We cast the phase-estimation problem into an optimization framework to improve the stability of an earlier method based on a piecewise-stationarity assumption. After estimation, we achieve space-and-time-varying zero-phasing by phase rotation.
Effects of surface scattering in full-waveform inversion
Authors: Bleibinhaus Florian , Rondenay Stéphane
Published: December 2009

In full-waveform inversion of seismic body waves, often the free surface is ignored on grounds of computational efficiency. A synthetic study was performed to investigate the effects of this simplification. In terms of size and frequency, the test model and data conform to a real long-offset survey of the upper crust across the San Andreas fault. Random fractal variations are superimposed on a background model with strong lateral and vertical velocity variations ranging from 1200 to 6800 m/s. Synthetic data were computed and inverted for this model and different topographies. A fully viscoelastic time-domain code was used to synthesize the seismograms, and a viscoacoustic frequency-domain code was utilized to invert them. The inversion was focused on early arrivals, which are dominated by P-waves but also contain strong P-Rayleigh wave conversions from the near-field of the receiver. Resulting waveform models show artifacts and a loss of resolution from neglecting the free surface in the inversion, but the inversions are stable, and they still improve the resolution of kinematic models. The extent of deterioration depends more on the subsurface than on the surface structure. Inversion results were improved at no additional expense by introducing a weak contrast along a staircase function above shots and receivers.
3D seismic reflection imaging of volcanic-hosted massive sulfide deposits: Insights from reprocessing Halfmile Lake data, New Brunswick, Canada
Authors: Malehmir Alireza , Bellefleur Gilles
Published: December 2009

Three-dimensional seismic reflection data from the Halfmile Lake area, New Brunswick, Canada, was reprocessed over an 18- [Formula: see text] grid to improve the seismic signatures of a 5-million-ton volcanic-hosted massive sulfide (VHMS) deposit located at 1200-m depth, known as the deep zone, as well as key host-rock structures. We chose a prestack dip moveout (DMO) and poststack migration processing sequence to preserve the possible diffraction signature of the deep VHMS zone. Despite the high level of source-generated noise and large statics caused by near-surface conditions, our processing results revealed improved 3D seismic images for shallow and deep structures. Many of the imaged structures were easily correlated with known lithological con-tacts constrained by boreholes and petrophysical measurements. A short, flat-lying segment of high-amplitude reflection at about 800-m depth in the unmigrated cube was interpreted to originate from a small portion of the lower VHMS zone. The DMO stack was characterized by a large, high-amplitude asymmetric diffraction signature originating from the deep VHMS zone. The asymmetry of the diffraction hyperbola relative to the location of the deep zone was interpreted as resulting from a shape effect from the zone, with the strongest amplitudes along the diffraction hyperbola found north-northwest of the apex. This indicated that the deep VHMS zone dips in a similar direction. This diagnostic diffraction signature was not preserved with the prestack migration approach previously implemented for processing Halfmile Lake data.
An overview of full-waveform inversion in exploration geophysics
Authors: Virieux J. , Operto S.
Published: December 2009

Full-waveform inversion (FWI) is a challenging data-fitting procedure based on full-wavefield modeling to extract quantitative information from seismograms. High-resolution imaging at half the propagated wavelength is expected. Recent advances in high-performance computing and multifold/multicomponent wide-aperture and wide-azimuth acquisitions make 3D acoustic FWI feasible today. Key ingredients of FWI are an efficient forward-modeling engine and a local differential approach, in which the gradient and the Hessian operators are efficiently estimated. Local optimization does not, however, prevent convergence of the misfit function toward local minima because of the limited accuracy of the starting model, the lack of low frequencies, the presence of noise, and the approximate modeling of thewave-physics complexity. Different hierarchical multiscale strategies are designed to mitigate the nonlinearity and ill-posedness of FWI by incorporating progressively shorter wavelengths in the parameter space. Synthetic and real-data case studies address reconstructing various parameters, from [Formula: see text] and [Formula: see text] velocities to density, anisotropy, and attenuation. This review attempts to illuminate the state of the art of FWI. Crucial jumps, however, remain necessary to make it as popular as migration techniques. The challenges can be categorized as (1) building accurate starting models with automatic procedures and/or recording low frequencies, (2) defining new minimization criteria to mitigate the sensitivity of FWI to amplitude errors and increasing the robustness of FWI when multiple parameter classes are estimated, and (3) improving computational efficiency by data-compression techniques to make 3D elastic FWI feasible.
The domain of applicability of acoustic full-waveform inversion for marine seismic data
Authors: Barnes Christophe , Charara Marwan
Published: December 2009

Marine reflection seismic data inversion is a compute-intensive process, especially in three dimensions. Approximations often are made to limit the number of physical parameters we invert for, or to speed up the forward modeling. Because the data often are dominated by unconverted P-waves, one popular approximation is to consider the earth as purely acoustic, i.e., no shear modulus. The material density sometimes is taken as a constant. Nonlinear waveform seismic inversion consists of iteratively minimizing the misfit between the amplitudes of the measured and the modeled data. Approximations, such as assuming an acoustic medium, lead to incorrect modeling of the amplitudes of the seismic waves, especially with respect to amplitude variation with offset (AVO), and therefore have a direct impact on the inversion results. For evaluation purposes, we have performed a series of inversions with different approximations and different constraints whereby the synthetic data set to recover is computed for a 1D elastic medium. A series of numerical experiments, although simple, help to define the applicability domain of the acoustic assumption. Acoustic full-wave inversion is applicable only when the S-wave velocity and the density fields are smooth enough to reduce the AVO effect, or when the near-offset seismograms are inverted with a good starting model. However, in many realistic cases, acoustic approximation penalizes the full-wave inversion of marine reflection seismic data in retrieving the acoustic parameters.
Nonlinear impedance inversion for attenuating media
Authors: Oliveira Sérgio , Loures Luiz , Moraes Fernando , Theodoro Carlos
Published: December 2009

Applications of seismic impedance inversion normally assume the data are free of multiples and transmission effects, requiring knowledge of the seismic pulse that is assumed to be stationary. An alternative formulation for impedance inversion is based on an exact frequency-domain, zero-offset reflectivity function for a 1D medium. Analytical formulas for the Fréchet derivatives are derived for efficient implementation of an iterative nonlinear inversion. The exact zero-offset reflectivity accounts for internal multiples and transmission effects in the data. Absorption and dispersion are also conveniently handled if a reasonable estimate for the quality [Formula: see text] factor of the medium is available. A series of convenient features are included in the inversion algorithm: an automatic estimation of the amplitude spectrum of the seismic pulse, an impedance transform that makes the inversion independent from the initial smooth model, and a practical approach to estimate the regularization weight. Numerical tests using synthetic and real data show that the method is stable and needs only a few iterations to converge.
Some Swedish Stepping-Stones to Growth Economics
Authors: Boianovsky Mauro
Published: December 2009

This article investigates original contributions made by Swedish economists to the interpretation of the process of economic growth. Knut Wicksell studied the optimal capital accumulation path and applied the aggregate production function approach to growth with land scarcity. Gustav Cassel developed the notion of steady-state growth and its determinants. Erik Lundberg built on Cassel to put forward the so-called Harrod-Domar condition, and he introduced the “Horndal effect” in growth economics. Ingvar Svennilson advanced a hypothesis about the positive relation between the growth rates of production and productivity, together with the notion that economic growth results from the competition between old and new capital goods. The article relates those contributions to the formation of the field of growth economics by Robert Solow and others.
A Nonlinear History of Growth and Cycle Theories
Authors: Punzo Lionello F.
Published: December 2009

Relying on historical evidence as well as on rational arguments, this article reconstructs the birth of the neoclassical theory as a key episode of the parallel though interconnected evolution of the aggregate theories of growth and oscillations. As a by-product, it explains why that theory could be invented, practically at the same time, by two independent researchers, Solow and Swan. In our argument, the neoclassical theory represented a partially successful attempt to overcome the difficulties arising in the Harrodian interpretation of the classical macrodynamics program, which had led to its failure to produce a unified theoretical explanation of economic dynamics. The way out was seen in the adoption of the general equilibrium research agenda, shifting thus the focus on existence and stability issues. This, however, has implied the acceptance of the divorce of the theory of growth from the theory of fluctuations, a divorce that has prevailed until recently. We maintain that the conceptual limitations and high costs in terms of interpretive capacity involved in the neoclassical solution account for the repeated emergence of certain unanswered questions.
Trevor Swan and the Neoclassical Growth Model
Authors: Dimand Robert W. , Spencer Barbara J.
Published: December 2009

The independent contributions of Robert Solow and the Australian economist Trevor Swan in developing the neoclassical growth model are sometimes recognized by reference to the “Solow-Swan” model, but often reference is made only to the “Solow” model. Both Solow (1956) and Swan (1956) created a simple, convenient, and powerful apparatus for finding the steady-state growth path of a one-commodity world. This paper examines the differences and similarities between Swan's and Solow's analysis and diagrams, the reasons why Solow's version received more attention, and, drawing on Swan's unpublished papers, the place of Swan's growth model in his intellectual development.
Dynamizing Stability
Authors: Boumans Marcel
Published: December 2009

This article aims to show the mathematical contexts out of which emerged Solow's 1957 article “Technical Change and the Aggregate Production Function.” In particular, it seeks to provide some understanding of its most striking feature, namely, the highly aggregate level on which technical change is discussed and the simple way in which it is represented. The approach is similar to Weintraub's (1991) contextualization of Samuelson's Foundations of Economic Analysis (1947), but it will map out the two mathematical contexts in which Solow's 1957 article can be located. Samuelson's concepts of stability provided Solow the tools for the aggregation of technical change. However, Samuelson's concepts were defined in relation to static equilibrium and not to growth. To arrive at his 1957 representation of technical change, Solow successfully applied P. H. Leslie's concepts and tools of population mathematics. The main mathematical concepts around which this development is described are eigenvalue and eigenvector. It is by the use of these two concepts that aggregation of input-output tables was made feasible.
The Growing of Ramsey's Growth Model
Authors: Duarte Pedro Garcia
Published: December 2009

Frank Plumpton Ramsey (1903–1930) was a Cambridge mathematician who made important contributions not only to philosophy, mathematics, logic, and probability, but also to economics. Ramsey made two major contributions to economics, both published in the Economic Journal in 1927 and 1928, which became popular only in the 1950s and 1960s. In both cases, economists portrayed Ramsey as a sleeping giant: a mathematician who had almost no impact on the economics profession prior to 1950 because his mathematical analysis was out of the reach of the typical economist of his time. My goal in this article is to understand how Ramsey's growth model became part of the neoclassical literature on economic growth in the 1950s and 1960s and how Ramsey became a sacred predecessor of this field. In order to better understand the stabilization of Ramsey's growth model in postwar economics, I conduct a JSTOR search and consult a few book references. Based on this dataset, I conclude that Ramsey was in fact “awake” in the economic growth literature pre-1950. I discuss as well the main economists who transported Ramsey from the Cambridge milieu of the 1920s to the North American economics of the postwar period.
Solow and Growth Accounting: A Perspective from Quantitative Economic History
Authors: Crafts Nicholas
Published: December 2009

This paper examines the use of growth accounting by economic historians developed following Robert Solow's famous 1957 paper. Several general tendencies are identified, including a desire to account for Solow's residual and a reluctance to adopt the data-demanding methodological refinements of Dale Jorgenson, whose influence on the field was less than that of Edward Denison. Results from historical growth accounting studies are reviewed, and it is clear that the “crude residual” typically accounts for much less than the seven-eighths of labor productivity growth found by Solow and also that when TFP growth is rapid, improvements in efficiency are usually an important complement to technological progress. Nevertheless, growth accounting was important in undermining the “capital fundamentalism” of the 1950s and has been central to putting the contribution of technological progress in the Industrial Revolution into a clearer focus, free of the misleading “take-off” perspective advanced by Walt Rostow.
The Solow Model, Poverty Traps, and the Foreign Aid Debate
Authors: Snowdon Brian
Published: December 2009

For almost thirty years the Solow model experienced relative neglect within the field of development economics. However, since the mid-1980s the neoclassical growth model has been at the heart of the debate among economists interested in the important issues of growth, development, and convergence. More recently, the case for increasing foreign aid to sub-Saharan Africa has reemerged and has been linked to the Solow model via the hypothesis that many poor countries are caught in a poverty trap. This paper provides critical commentary on the literature relating to the Solow model, economic development, poverty traps, and the case for foreign aid.
The Solow Residual as a Black Box: Attempts at Integrating Business Cycle and Growth Theories
Authors: Mata Tiago , Louçã Francisco
Published: December 2009

Robert Solow's “Technical Change and the Aggregate Production Function” (1957) has had an enduring influence on macroeconomics. In this article, we examine the history of fluctuations in growth theory through the story of the “Solow residual” as a “black box.” We show that after Solow's seminal contribution, the “residual” became a reproducible object. Losing its ties with the intentions and beliefs of its originator, it was given new and unexpected uses in other branches of macroeconomics. While the residual had always remained a problematic result in growth accounting, its borrowing by real business cycle theorists sought to establish it as a definitive representation of technology. As the claims of the New Classicals came under scrutiny, so did the status and meaning of the object residual. The integration of growth and cycle has since been shaped by the opening of this “black box.” Edward Prescott has remained committed to his earlier interpretation of the “Solow residual” as stochastic technology. Others have sought to bracket multiple supply shocks as the residual, abandoning attempts to decompose it. To the New Keynesians the “residual” has been more evidence of market power and the need to integrate rigidities in the study of the cycle.
A simple gas turbine system and co-generation power plant improvement based on endogenous and exogenous exergy destruction
Authors: Razmara N , Khoshbakhti Saray R
Published: December 2009

Exergy analysis provides useful information about system optimization. An exergy analysis identifies the sources of thermodynamic inefficiencies by evaluating the exergy destruction within each system component. Splitting the exergy destruction into endogenous/exogenous parts represents a new development in the exergy analysis of energy conversion systems. The present work is an attempt to investigate the combustion process in a simple gas turbine (GT) and a cogeneration power plant based on the general concept of endogenous and exogenous exergy destruction. Therefore, using a graphical approach, an advanced exergy analysis is applied to both cycles with different fuels such as natural gas (NG) and diesel. Also, dual-fueling of the combustion chamber (CC) is investigated based on the aforementioned approach in which different substitutions of NG fuel with diesel fuel are considered. It is found that in both cycles, the CC has the largest value of the endogenous exergy destruction. The exergetic efficiency of the CC is the least value of the three components of the GT system and increases by about 1.76 per cent, when NG fuel is substituted for diesel fuel. Also, for the cogeneration power plant, it can be seen that the exergetic efficiency of CC increases by about 1.87 per cent, when NG fuel is substituted for diesel fuel. As a result, the total system exergetic efficiency for simple GT and co-generation power plants increases by 1.05 per cent and 1.6 per cent, respectively. Therefore, cycles have been improved by increasing the substitution of NG fuel with diesel fuel. The results obtained here may provide some useful information on the optimal design and performance improvement of these cycles.
How patients use access to their full health records: a qualitative study of patients in general practice
Authors: Fisher Brian , Bhavnani Vanita , Winfield Marlene
Published: December 2009

Summary

Objective

To explore how patients use record access, its impact and the benefits and drawbacks of using it.

Design

Qualitative study using focus group interviews, individual interviews and telephone interviews.

Setting

General practice offering electronic access to full medical records using PAERS system.

Participants

Forty-three patients aged between 20 and 71 years participated. Of these, nine were in the healthy group, eight had long-term health conditions, 10 were in the mental health group and 16 were pregnant.

Results

Three themes emerged as to how patients used record access – participation in care, quality of care and self-care strategies. Record access was used to help prepare patients for consultations, compensate for poor or complex communication during consultations and to reduce the fragmentation of care. Record access had a small impact on health behavior intentions. Overall patients felt that record access reinforced trust and confidence in doctors and helped them feel like partners in healthcare.

Conclusion

This study suggests that record access improves shared management, with patients using their records to improve interactions with healthcare providers, make decisions about their health and improve the quality of the care they receive. These findings also suggest a possible long-term potential for record access to improve health outcomes.
Thyroidal radioactive iodide uptake in the lactating rhesus monkey
Authors: Ozpinar Aysel , Bruss Michael , Shelton David , Gillespie Jerry
Published: December 2009

Although radioactive iodide uptake (RAIU) is one of the reliable diagnostic methods for thyroid function in adult humans, especially in the diagnosis of thyrotoxicosis, there are limited data for RAIU during pregnancy and lactation in humans and animals. Therefore, we proposed to validate RAIU for the lactating rhesus monkey to further human model studies in thyroid disease. RAIU was performed at 6 and 24 h using 100 µCi of 123I orally in four lactating monkeys. The thyroid and thigh were counted using a scintillation probe and multichannel analyser. A dose/standard ratio of counts/minute was calculated to compensate for background, utilizing differences in the activity between the dose administered and a standard. Thyroidal RAIU varied significantly among monkeys: 6.71 ± 2.40% for the 6 h uptake and 15.44 ± 7.71% for the 24 h uptake. These data showed that the RAIU test may allow a rational clinical approach to thyroid function testing for lactating rhesus monkeys. Additional studies are needed for assessing thyroid function in rhesus monkeys of varying ages and gender with clinical abnormalities.
How an Adolescent's Childbearing Affects Siblings' Pregnancy Risk: A Qualitative Study Of Mexican American Youths
Authors: East Patricia L. , Slonim Ashley , Horn Emily J. , Trinh Cyndy , Reyes Barbara T.
Published: December 2009

CONTEXT: The siblings of teenage parents are known to be at very high risk of teenage pregnancy, but little is known about how an older sister's childbearing affects a younger sibling's risk. Understanding these influences could help address the very high rates of pregnancy and childbearing among Latino adolescents.

METHODS: From 2005 through 2007, a sample of 41 Mexican American 12–18‐year‐olds from southern California completed in‐depth interviews about how an older sister’s teenage childbearing had affected them. Themes that emerged were categorized as risk factors (circumstances that increased youths’ likelihood of becoming involved in a teenage pregnancy) or protective factors (conditions that reduced this likelihood) on the basis of well‐established findings in the literature.

RESULTS: Interview data reflected six risk factors and 11 protective factors. The most commonly reported risk factors (discussed by more than a quarter of participants) were that youths did not perceive early parenting as a hardship, had increased difficulties in school and wanted to have a baby too. The most commonly cited protective factors (mentioned by more than half) were an increased motivation to avoid early parenting, an increased appreciation of the difficulties of parenting, mothers' explicitly discouraging early parenting and youths' feeling of greater closeness with their mother.

CONCLUSIONS: Interventions that build on the protective factors that result when a youth's older sibling has a teenage birth, while reducing the risk factors, might help families prevent younger children from becoming involved in a teenage pregnancy.
Casual Sex and Psychological Health Among Young Adults: Is Having “Friends with Benefits” Emotionally Damaging?
Authors: Eisenberg Marla E. , Ackard Diann M. , Resnick Michael D. , Neumark‐Sztainer Dianne
Published: December 2009

CONTEXT: Speculation in public discourse suggests that sexual encounters outside a committed romantic relationship may be emotionally damaging for young people, and federal abstinence education policy has required teaching that sexual activity outside of a marital relationship is likely to have harmful psychological consequences.

METHODS: In 2003–2004, a diverse sample of 1,311 sexually active young adults (mean age, 20.5) participating in a longitudinal study in Minnesota completed a survey including measures of sexual behavior and psychological wellbeing. Chi‐square tests were used to compare the prevalence of recent casual partnerships by selected demographic and personal categories. General linear modeling was then used to compare mean levels of each psychological wellbeing measure between those reporting recent casual partners and those reporting committed partners; partner type was measured both dichotomously and categorically.

RESULTS: One‐fifth of participants reported that their most recent sex partner was a casual partner (i.e., casual acquaintance or close but nonexclusive partner). Casual partnerships were more common among men than among women (29% vs. 14%), and the proportions of male and female respondents reporting a recent casual partner diff ered by race or ethnicity. Scores of psychological well‐being were generally consistent across sex partner categories, and no significant associations between partner type and well‐being were found in adjusted analyses.

CONCLUSIONS: Young adults who engage in casual sexual encounters do not appear to be at greater risk for harmful psychological outcomes than sexually active young adults in more committed relationships.
Detailed Educational Pathways Among Females After Very Early Sexual Intercourse
Authors: Steward Nicole R. , Farkas George , Bingenheimer Jeffrey B.
Published: December 2009

CONTEXT: Although studies have shown that early sex is negatively associated with high school graduation and college enrollment, no recent study has examined the extent to which early sex affects educational attainment, and the mediating mechanisms have not been established.

METHODS: Data from 4,613 female participants in the National Educational Longitudinal Study were used to examine the relationship between early sexual intercourse (i.e., first sex prior to age 15) and educational attainment. Logistic regression analyses that controlled for background characteristics, school performance, behavioral factors and academic aspirations were conducted to assess this association, as well as to explore the potential mediating role of early marriage and childbearing.

RESULTS:  Young women who had had early sex had reduced odds of having graduated from high school (odds ratio, 0.4) and from college (0.5). Postsecondary enrollment was positively associated with expectations of postsecondary education (1.5) and levels of academic achievement (1.4–1.5), but not with early sex. Respondents who had married before their expected high school graduation date had reduced odds of having graduated from high school (0.1), enrolled in postsecondary school (0.4) or completed college (0.1); those who had a child before their expected high school graduation date had reduced odds of having graduated from high school (0.3) or college (0.1).

CONCLUSIONS:  Programs that target early parenthood and marriage, and that provide hope for future educational opportunities, could lessen the impact of early sex for young women.
Sweetening the Pot: Adding Glycosylation to the Biomarker Discovery Equation
Authors: Drake Penelope M , Cho Wonryeon , Li Bensheng , Prakobphol Akraporn , Johansen Eric , Anderson N Leigh , Regnier Fred E , Gibson Bradford W , Fisher Susan J
Published: December 2009

Background: Cancer has profound effects on gene expression, including a cell’s glycosylation machinery. Thus, tumors produce glycoproteins that carry oligosaccharides with structures that are markedly different from the same protein produced by a normal cell. A single protein can have many glycosylation sites that greatly amplify the signals they generate compared with their protein backbones.

Content: In this article, we survey clinical tests that target carbohydrate modifications for diagnosing and treating cancer. We present the biological relevance of glycosylation to disease progression by highlighting the role these structures play in adhesion, signaling, and metastasis and then address current methodological approaches to biomarker discovery that capitalize on selectively capturing tumor-associated glycoforms to enrich and identify disease-related candidate analytes. Finally, we discuss emerging technologies—multiple reaction monitoring and lectin-antibody arrays—as potential tools for biomarker validation studies in pursuit of clinically useful tests.

Summary: The future of carbohydrate-based biomarker studies has arrived. At all stages, from discovery through verification and deployment into clinics, glycosylation should be considered a primary readout or a way of increasing the sensitivity and specificity of protein-based analyses.
Definition of reference ranges for the platelet distribution width (PDW): a local need
Authors: Farias Mariela Granero , Schunck Elias Guilherme , Dal Bó Suzane , de Castro Simone Martins
Published: December 2009

Background:Automated hematological analyzers have contributed to more precise and faster results. They also make it possible to measure several blood cell parameters automatically. Among the parameters provided, platelet indices are probably the most ignored by clinical laboratories due to the difficulty of standardization, as well as being affected by a range of methodological problems. It has been suggested that each laboratory determines its own reference intervals with the equipment used.

Methods:Our goal was to determine the reference range of platelet distribution width (PDW) in venous blood samples from 231 patients using the Pentra 120 ABX hematology analyzer.

Results:The PDW median was 13.3%, with a reference range of 10.0%–17.9% for the 5th–95th percentiles, with a confidence interval of 95%.

Conclusions:Among all indices, the PDW has been receiving attention due to its usefulness for distinguishing between reactive thrombocytosis and thrombocytosis associated with myeloproliferative disorder. Determination of the PDW reference range is fundamental, and the association of this parameter with the platelet number and mean platelet volume may be used for the diagnosis and differentiation of several pathologies.

Clin Chem Lab Med 2010;48:255–7.
Stability of cerebrospinal fluid/serum glucose ratio and cerebrospinal fluid lactate concentrations over 24 h: analysis of repeated measurements
Authors: Dujmovic Irena , Deisenhammer Florian
Published: December 2009

Background: The cerebrospinal fluid/serum glucose ratio (CSF/Sglu) and CSF lactate measurements are part of the routine CSF work-up. The in-vitro stability of both metabolites in CSF has not been formally investigated.

Methods: Following collection, CSF/Sglu and CSF L-lactate concentrations were measured repeatedly at five time points (baseline, 1 h, 2 h, 4 h and 24 h) in CSF and whole blood specimens stored at 4°C.

Results: CSF glucose and lactate concentrations were stable over 24 h in samples with both normal and increased CSF cell counts. The CSF cell count did not influence CSF glucose concentrations, but correlated significantly with CSF lactate concentrations. The CSF/Sglu increased significantly over time due to glucose consumption.

Conclusions: Glucose and L-lactate are stable in CSF specimens at 4°C over 24 h. The CSF/Sglu seems to be more reliable than CSF lactate because it is independent of the cell count. Falsely increased CSF/Sglu may be corrected by the rate of consumption of blood glucose.

Clin Chem Lab Med 2010;48:209–12.
Performance analysis of the ARCHITECT anti-cyclic citrullinated peptide antibody in the diagnosis of rheumatoid arthritis
Authors: Hwang Sang Mee , Kim Jeong-Ok , Yoo Young-Mi , Shin Sue , Kim Jin Q , Park Myoung Hee , Song Eun Young
Published: December 2009

Background: Anti-cyclic citrullinated peptide (CCP) antibody is emerging as an important diagnostic marker for rheumatoid arthritis (RA). We evaluated the analytical and diagnostic performance of the ARCHITECT anti-CCP (Abbott Diagnostics), a new fully automated chemiluminescent microparticle immunoassay.

Methods: Serum samples from 69 patients with RA and 86 non-RA patients were used to evaluate the performance of the ARCHITECT anti-CCP assay, and the results were compared with those of EliA CCP (Phadia). The optimal cut-off value was calculated using receiver operating characteristic (ROC) curve analysis.

Results: Within-run and total imprecision (%CV) of the ARCHITECT anti-CCP were <6% and good linearity was observed over the claimed range. The areas under the ROC curves for the ARCHITECT anti-CCP and EliA CCP were 0.90 and 0.89, respectively. The sensitivity and specificity were 76.8% and 95.3% for the ARCHITECT anti-CCP and 78.3% and 95.3% for EliA CCP using the manufacturer's cut-off thresholds. Both assays showed sensitivity of 84.1% and specificity of 94.2% using the optimal cut-off values.

Conclusions: The analytical performance of the ARCHITECT anti-CCP was satisfactory and diagnostic performance was comparable to that of EliA CCP. The use of optimal cut-off thresholds can yield higher sensitivity with minimal loss of specificity.

Clin Chem Lab Med 2010;48:225–30.
Determination of globotriaosylceramide in plasma and urine by mass spectrometry
Authors: Krüger Ralf , Bruns Kai , Grünhage Silke , Rossmann Heidi , Reinke Jörg , Beck Michael , Lackner Karl J.
Published: December 2009

Background: Fabry disease is an X-chromosomally inherited lysosomal storage disorder leading to accumulation of glycosphingolipids, mainly globotriaosylceramide (ceramide-trihexoside, Gb3). Concentrations of Gb3 in plasma and urine have been used to diagnose Fabry disease and to monitor enzyme replacement therapy with recombinant α-galactosidase.

Methods: Gb3 was purified from plasma or urine by combined liquid extraction/protein precipitation and solid-phase extraction, and was detected by flow-injection analysis electrospray mass spectrometry (MS) using multi-reaction-monitoring. Calibration was performed via standard addition using C17-Gb3 as internal standard. The most abundant isoforms were monitored for calculation of total Gb3.

Results: A MS-based assay for quantification of Gb3 in plasma and urine was established and validated. Intra- and inter-assay coefficient of variation (CV) of the method were ≤12%. However, at low concentrations the CV was 16%. The linear range covers roughly two orders of magnitude, down to 0.54 mg/L in plasma and 0.07 mg/L in urine. Careful adjustment of tuning parameters was necessary to obtain identical isoform intensities and quantitative results on different mass spectrometers. Gb3 concentrations in healthy controls were <4 mg/L in EDTA-plasma and <10 μg/mmol creatinine in urine. Significantly increased Gb3 concentrations were found in plasma and urine from male and female patients with Fabry disease.

Conclusions: An improved MS protocol for Gb3 quantification has been developed, validated, and shown to be suitable for diagnosis and monitoring of Fabry patients.

Clin Chem Lab Med 2010;48:189–98.
Oxidative polymerisation of models for phenolic lignin end-groups by laccase
Authors: Areskogh Dimitri , Li Jiebing , Nousiainen Paula , Gellerstedt Göran , Sipilä Jussi , Henriksson Gunnar
Published: December 2009

The redox enzyme laccase can lead to cross-linking of lignin molecules by oxidising phenolic end groups to resonance-stabilised radicals that can undergo radical coupling to form covalent bonds. This property has potential for many technical applications. However, laccase treatment can also lead to degradation. Experiments were performed with two laccases of different oxidation potential and pH and temperature optima. The predominant reaction following laccase oxidation is the formation of 5-5′ and 4-O-5′ bonds. If the 5-position is blocked, other reactions occur, including coupling of the 1-position and oxidation of the α-position, which aggravates cross-linking of different lignin molecules. The product profile generated by the two laccases is somewhat different, mainly because of the different pH rather than differences in enzyme activity. Reaction mechanisms and the technical and biological significance of the results are discussed.
Moisture-induced stresses and distortions in spruce cross-laminates and composite laminates
Authors: Gereke Thomas , Hass Philipp , Niemz Peter
Published: December 2009

The crosswise gluing of cross-laminated panels made of solid wood can cause problems when exposed to moisture variations. In the present study, the substitution of the spruce middle layer by a wood composite is tested for its influence on moisture-induced stresses and deformations in laboratory tests and numerical simulations. Furthermore, slits in the spruce middle layer were investigated. The hygroscopic warping due to a moisture gradient, stresses caused by moistening and cracks due to drying were studied. The results show larger warping in composite laminates compared to the spruce cross-laminate, which is governed by the modulus of elasticity of the middle layer. The in-plane swelling was found to be larger in composite laminates, while stresses were lower. The drying test discovered that cracks develop in the middle layer of spruce-medium density fiberboard laminates due to shear stresses and tensile stresses in the thickness direction. It was concluded that slits can be applied in the middle layer, as they have no significant influence on moisture-induced stresses but increase the thermal insulation. If the substitution of the spruce layer is required, the application of oriented strand board in the middle layer is recommended.
Recovery of cellulose and xylan liquefied in ionic liquids by precipitation in anti-solvents
Authors: Nakamura Atsushi , Miyafuji Hisashi , Saka Shiro , Mori Midori , Takahashi Haruo
Published: December 2009

No abstract available
Initiating ECF bleaching sequences of eucalyptus kraft pulps with Z/D and Z/E stages
Authors: García Juan C. , López Francisco , Pérez Antonio , Pèlach M. Angels , Mutjé Pere , Colodette Jorge L.
Published: December 2009

Ozone bleaching is a common practice in pulping, and also of eucalyptus, where it is usually applied in combination with bleaching sequences based on oxygen, hydrogen peroxide, or chlorine dioxide. Ozone has been proven to be a highly efficient and competitive bleaching chemical in terms of delignification efficiency, low costs, and reducing ecological impact. The objective of the present work was to evaluate technology with ozone/alkaline extraction (Z/E) and ozone/chlorine dioxide (Z/D) for bleaching of eucalyptus kraft pulp. Primarily, the impact of these bleaching steps on refinability and quality of pulp should be investigated. As reference, the sequence D*(EP)D (hot chlorine dioxide, extraction in presence of hydrogen peroxide, chlorine dioxide) was selected, which is considered as the state-of-the-art bleaching in elemental chlorine free (ECF) bleaching technology. Various bleaching sequences with ozone in their first step (Z/D(EP)DP, Z/D(EP)DD, Z/EDP, Z/EDD and A*Z/EDP) were found to provide kraft pulps of similar brightness and in similar yield as the reference sequence D*(EP)D. The kappa number, viscosity, and the contents of glucose and xylose, and hexenuronic acid of the pulps were also similar. In addition, the Z sequences resulted in a substantial reduction of the total chlorine dioxide consumption (more than 30.3% in all cases). The A*Z/EDP sequence, which proved to be the most efficient, yielded 87.5% ClO2 reduction. The studied bleaching sequences also resulted in substantially improved brightness reversal with regard to the reference sequence. The sequence A*Z/EDP was also the most efficient as regards the removal or organochlorines (OX) from the pulp and their reduction in the effluents (AOX). Ozone bleaching sequences improved paper strength, especially with the A*Z/EDP sequence.
Effects of calcium-based materials and iron impurities on wood degradation by the brown rot fungus Serpula lacrymans
Authors: Schilling Jonathan S.
Published: December 2009

Calcium-containing materials have been implicated in promoting wood degradation by Serpula lacrymans, but mechanisms remain unresolved. In this study, S. lacrymans and Serpula himantioides degraded pine sapwood in agar-block microcosms with one of four treatments: calcium-free, 5 mM agar CaCl2, high-purity gypsum (CaSO4), and gypsum amended with 1% FeSO4. Calcium and iron availability were limited in minimal nutrient agar. At week 5, pine degradation was significantly higher for S. lacrymans in iron-amended gypsum treatments than other treatments, and the respective agar oxalate levels were also higher. Oxalate solubility was lowest in pure calcium microcosms. Scanning electron microscopy showed hyphae in contact with gypsum and precipitation of calcium oxalate. At week 15, wood degradation by S. lacrymans was severe (>60%) in both calcium-free and iron-amended treatments, but was significantly less in pure calcium treatments (≈45%). Cation analysis in week 15 wood revealed higher calcium and iron levels in treatments containing those element additions. Serpula himantioides had decayed wood equally among treatments at both harvests. Results demonstrate that calcium has an inhibiting effect – and not a promoting effect as hitherto believed – on wood degradation by S. lacrymans. It appears that oxalate and iron play a role in stimulating wood degradation by this destructive fungus.
Tensile stress relaxation of wood impregnated with different ACQ formulations at various temperatures
Authors: Yu Lili , Cao Jinzhen , Zhao Guangjie
Published: December 2009

The reactions between constituents of alkaline copper quat (ACQ) and of wood were investigated by a tensile stress relaxation approach. Small samples were stressed and impregnated with various ACQ solutions, in which the ratios of monoethanolamine (MEA), ACQ, and didecyl dimethyl ammonium chloride (DDAC) were varied. The other parameters included temperature and concentration of the treating solutions. The stress relaxation curves of wood were recorded during the impregnation period and the effects of impregnation parameters were investigated by an orthogonal experimental design (OED). The effects of water, MEA, and DDAC on stress relaxation of the samples were also observed. The bulking effect of water was tested separately in samples treated with distilled water without stretching. The results showed that the stress relaxes dramatically in the initial period and then changes slightly over a long period, which is readily visible in double logarithmic plots of f (t)/f (0) versus time (t). There are complex interactions between the components of ACQ solutions and wood matrix: (1) in rapid phase I, the splitting of the easily accessible hydrogen bonds (mainly in the amorphous hemicelluloses) are prevalent by interaction with components of ACQ solution; (2) in slow phase II, Cu penetrates deeper in less accessible regions (e.g., in paracrystalline regions of cellulose) and renders possible further relaxation. The results of range and variance analysis reveal that the molar ratio of Cu to MEA and temperature of ACQ solution have significant effects on the rate of reaction during phase I, whereas in phase II only the temperature of ACQ solution has a significant effect. The stress relaxation curves of samples impregnated in water, MEA, and DDAC all showed a quasi one phase stress relaxation rate, which suggests that phase II is mostly related to Cu in ACQ formulations. It is concluded that the formation of complexes with Cu is still the major reaction in wood although there is competition among ACQ constituents for reaction sites.