bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Resorbable Wrap-Around Implant as an Alternative Nerve Repair Technique
Authors: HAZARI A. , JOHANSSON-RUDÉN G. , JUNEMO-BOSTROM K. , LJUNGBERG C. , TERENGHI G. , GREEN C. , WIBERG M. 
Published: September 2002

Poly-3-hydroxybutyrate (PHB), a bacterial storage product, is available as bioabsorbable sheets and has been used in this study for primary nerve repair. The aim was to assess axonal regeneration following such repair and determine the inflammatory response to PHB. In 20 adult cats, the transected superficial radial nerve was wrapped in PHB sheets, while primary epineural repair was carried out in the contralateral limb. At 6 and 12 months, the repair sites were assessed immunohistochemically for macrophage infiltration and myelinated axons were counted in the distal nerve. Mean macrophage counts across the whole width of the nerve in both groups at 6 and 12 months showed no statistically significant difference. Nor was there any significant difference between the two groups at both time-points in axon counts, axon diameter, myelin thickness and g-ratio. There was a statistically significant increase in fibre diameters at 12 months, indicating that fibres were undergoing continuous maturation.
Hand Surgery and Quality of Life
Authors: COLVILLE R. J. I. , NICHOLSON K. S. , BELCHER H. J. C. R. 
Published: September 2002

The outcome in patients having surgery to the hand was assessed subjectively using a questionnaire that covered activities of daily living (ADL), hand pain and psychological well-being. The questionnaires were completed on average 6.9 months preoperatively and 20.6 months postoperatively by 15 patients with osteoarthritis undergoing trapeziectomy and 25 patients with rheumatoid arthritis undergoing Swanson arthroplasties of the metacarpophalangeal joints. Surgery resulted in significant improvements in reported ADL and hand pain, in both groups. Improvement in perception of hand function and health was only seen in the osteoarthritic group. There was no improvement in arthritis activity, mood or quality of life in either group. These results confirm that surgery for arthritis of the hand relieves pain and improves ADL. However, it has a greater effect in patients with localized osteoarthritis than in those with rheumatoid arthritis.
Rapid Repeat Testing of Grip Strength for Detection of Faked Hand Weakness
Authors: TREDGETT M. W. , DAVIS T. R. C. 
Published: September 2002

This study assessed the use of rapid, repeated measurement of grip strength to detect feigned hand weakness. Normal participants, performing with maximum effort or feigning hand weakness, and patients recovering from carpal tunnel surgery were asked to grip a Jamar dynamometer alternately with each hand on ten occasions. The results showed that grip strength fatigued by an average of 23% during the test in the normal participants, 18% in participants faking weakness, and increased by 2% in the carpal tunnel decompression patients. An increase in grip strength after the first effort was found in 39% of normal participants, 52% of participants faking hand weakness and in 69% of the carpal tunnel decompression patients. These results suggest that rapid, repeated measurement of grip strength is not a reliable discriminator of true and faked hand weakness.
DETERMINATION OF THE OPTICAL CONSTANTS OF InxSey THIN FILMS DEPOSITED BY EVAPORATION AND COEVAPORATION
Authors: SANDINO J. , GORDILLO G. 
Published: September 2002

In x Se y thin films, grown on soda lime glass substrates in the In 6 Se 7 phase by evaporation of the In 2 Se 3 compound and in the In 2 Se 3 phase by coevaporation of In and Se, were optically characterized through spectral transmittance measurements. A special procedure was developed to determine the thickness d and the optical constants (refractive index n, absorption coefficient α, and optical gap Eg). This includes experimental measurements of the spectral transmittance and the use of a model taking into account interference effects induced by internal reflections presented in the interfaces substrate/film and film/air and the fitting of the n vs. λ curve to the Cauchy equation (n = A + B/λ2). The optical constants of the In x Se y thin films were corrected comparing the experimental transmittance spectrum with the theoretical one. The results revealed that the optical constants of the In x Se y films were significantly affected by the deposition method.
New theoretical and practical aspects of electromagnetic soundings at low induction numbers
Authors: Gómez‐Treviño Enrique , Esparza Francisco J. , Méndez‐Delgado Sóstenes 
Published: September 2002

This paper presents a theoretical yet practical study of electromagnetic (EM) soundings at low induction numbers for vertical and horizontal magnetic dipoles. The physical model is a heterogeneous half‐space with arbitrary vertical conductivity variations. The study comprises a novel approach for solving forward problems, analytical formulas for inversion, and a practical algorithm for recovering conductivity variations from field measurements. The basis of the theoretical approach is a series representation of the EM field in terms of ascending powers of frequency. At low induction numbers only two terms are required. When substituted into Maxwell's equations, one term in the series can be obtained in terms of the other. Furthermore, if the electrical conductivity varies only with depth, the imaginary part of the field can be obtained from its real part through a differential equation. The real part, which corresponds to zero frequency, plays the role of a distributed source for the frequency‐dependent imaginary part. In the case of vertical magnetic dipoles, the approach applies directly to the real and imaginary components of the magnetic field, while for horizontal dipoles one must use the Hertz potential, but the procedure is exactly the same.In each case this leads to a statement of the forward problem as the solution of a real differential equation. The solutions are integral expressions valid for arbitrary conductivity profiles. Assuming that these expressions represent integral equations for conductivity, analytical inverse formulas are derived for both vertical and horizontal dipoles. These formulas ensure a unique recovery of the conductivity profile under ideal conditions.An algorithm based on linear programming offers a variety of practical advantages for the inversion of field data. Numerical experiments and applications to field data illustrate the performance of the algorithm.
Volumetric wavefield recording and wave equation inversion for near‐surface material properties
Authors: Curtis Andrew , Robertsson Johan O. A. 
Published: September 2002

“Volumetric recording” of the seismic wavefield implies that the local receiver group or array approximately encloses a volume of the earth. We show how volumetric recording can be used to measure several spatial derivatives of the wavefield. By making use of the full elastic wave equation, the free surface condition on elastic wavefields, and derivative centering techniques analagous to Lax‐Wendroff corrections used in synthetic finite‐difference modeling, these derivative estimates can be inverted for P‐ and S‐velocities in the near surface directly beneath the receiver group. The quantities estimated are the effective velocities of the P‐ and S‐components experienced by the wavefield at any point in time. Hence, the velocity estimates may vary with both wave type and wavelength. The estimates may be useful to aid statics estimation and are exactly the effective velocities required for separation of the wavefield into P‐ and S‐, and up‐ and down‐going components.
Joint inversion of PP and PS reflection data for VTI media: A North Sea case study
Authors: Grechka Vladimir , Tsvankin Ilya , Bakulin Andrey , Hansen Jan Ove , Signer Claude 
Published: September 2002

Despite the significant advantages of combining PP and PS reflection data in anisotropic parameter estimation, application of this approach has been hindered by the inherent complexity of PS‐wave moveout. To overcome this problem, V. Grechka and I. Tsvankin suggested a model‐independent procedure to construct the traveltimes of pure SS‐wave reflections from PP and PS data. Here, we apply their method and anisotropic multicomponent stacking‐velocity tomography to a 2‐D line acquired over the lower Tertiary Siri reservoir in the North Sea.The computed traveltimes of SS reflections from several horizons are used to estimate the effective SS‐wave normal‐moveout (NMO) velocities, which are combined with the NMO velocities of PP‐waves in the tomographic velocity analysis. Comparison of the vertical and NMO velocities of the PP‐ and SS‐waves provides clear evidence of anisotropy in the section above the reservoir. The interval parameter estimation is performed under the assumption that the section is composed of transversely isotropic layers with a vertical symmetry axis (VTI media). Since the subsurface structure is close to horizontally layered, the reflection data cannot be uniquely inverted for the VTI parameters without additional information (e.g., the vertical velocities found from borehole data).The parameter‐estimation algorithm produces a family of equivalent VTI models that fit the PP and PS (or SS) traveltimes equally well. Although the range of variations in ε and δ for the equivalent models is rather wide, it does not include isotropic media (ε = δ = 0), which implies that accurate matching of both PP and PS data is impossible without accounting for anisotropy. To overcome the nonuniqueness in the inversion of reflection data and build a VTI depth model, we use P‐wave check shots acquired in the only borehole drilled on the processed line. Throughout the section ε > δ, with the largest values of both anisotropic coefficients observed in the depth range 0.7–1.5 km where ε reaches almost 0.25. Time sections of the original PS data computed using the VTI model have a much higher quality than the conventional isotropic sections.
The GPR refraction method
Authors: Bohidar Rabi N. , Hermance John F. 
Published: September 2002

Refracted phases have been a recognized feature in wide‐angle common midpoint (CMP) and common shotpoint (CSP) ground‐penetrating radar (GPR) surveys for many years, but historically their use has been limited and overshadowed by conventional reflection profiling techniques. In truth, the GPR refraction method holds great promise, as we show using four field examples from three sites in the northeastern United States. Typical refractors are shallow bedrock or coarse‐grained unconsolidated sediments (where the dielectric constant K ≈ 6–7) beneath partially saturated fine‐grained sand or silt (K ≈ 15–16). Under appropriate conditions, refracted phases can be detected readily at transmitter–receiver (Tx–Rx) offsets of >15 m and from depths of >2 m. Adapting procedures from refraction seismology, we interpret GPR data from reversed CSP soundings using dipping planar interface models and delay time analyses. Results from the two approaches are quite consistent, further corroborated at one of the sites by a GPR reflection profile and directly verified by a series of hammer‐driven probes. In addition to refractions from higher velocity layers in the subsurface, the air refracted phase (the ubiquitous phase refracted from the air–earth interface) can provide important constraints on interpreting the subsurface—particularly useful when attempting to resolve a shallow interface (depth ≤ 0.5 m) whose GPR signature might be masked by interacting phases at early traveltime and small transmitter–receiver offsets. Finally, a cautionary note for interpreting conventional reflection profile data when delineating a higher velocity interface at a depth that might be on the order of the antenna separation or less. Since the refracted phase arrives earlier than the reflected phase for Tx–Rx offsets beyond the critical distance, in certain cases the first break on a reflection radargram may actually be a refraction. CMP or CSP soundings in support of conventional GPR profiles can resolve such concerns.
Prediction of 3‐D fluid permeability and mudstone distributions from ground‐penetrating radar (GPR) attributes: Example from the Cretaceous Ferron Sandstone Member, east‐central Utah
Authors: Corbeanu Rucsandra M. , McMechan George A. , Szerbiak Robert B. , Soegaard Kristian 
Published: September 2002

A 3‐D fluid permeability distribution is estimated inside a channel sandstone reservoir analog in the Cretaceous Ferron Sandstone fluvio‐deltaic complex in east‐central Utah from ground‐penetrating radar (GPR) attributes. Fluid permeability measurements at 5 cm spacing along four boreholes and one pseudohole section at the adjacent cliff face are used together with instantaneous amplitude and frequency attributes of GPR data to predict fluid permeabilities away from the measured vertical transects and to delineate the distribution and geometry of mudstone layers inside the reservoir analog. Statistically significant relationships are determined between the well data (fluid permeability and mudstone content) and the GPR attributes. These calibrations are applied to the entire GPR volume to estimate the 3‐D fluid permeability variation and the lateral development of mudstone units.Measured and predicted fluid permeabilities range from 0.1 to 290 md. One of the five units considered contained no mudstone layers; cores from the other four units contained 18–42% mudstone and mudstone intraclast conglomerate. The mudstone content is estimated to be 8% by volume in these four units. Variograms show that the mudstone bodies fall into two main categories; most are 2.3–3.5 m in extent in the maximum correlation direction, with anisotropies of 0.4 to 0.7. A few ribbonlike mudstone bodies are also present, with 20‐ to 30‐m extents in the maximum correlation direction and with anisotropies of ∼0.1.
Multicomponent stacking‐velocity tomography for transversely isotropic media
Authors: Grechka Vladimir , Pech Andres , Tsvankin Ilya 
Published: September 2002

Accurate estimation of the velocity field is the most difficult step in imaging of seismic data for anisotropic media. Here, the velocity‐analysis problem is examined for the most common anisotropic model of sedimentary formations—transverse isotropy (TI) with arbitrary orientation of the symmetry axis. We show that supplementing wide‐azimuth reflected PP data with mode‐converted (PS) waves yields more stable estimates of the anisotropic coefficients and, in many cases, helps to constrain the model in depth.An important processing step preceding the inversion is computation of the traveltimes of the pure SS‐waves from those of the PP‐, and PS‐waves based on a technique recently developed by Grechka and Tsvankin. This procedure allows us to replace PS‐wave moveout, which is generally asymmetric with respect to zero offset, with the symmetric (hyperbolic on short spreads) moveout of the pure SS reflections. Then, generalizing the algorithm previously suggested for PP data, we develop a joint tomographic inversion of the normal‐moveout (NMO) ellipses and zero‐offset traveltimes of PP‐ and SS‐waves.Application of the method to wide‐azimuth PP and PS reflections from a dipping interface beneath a homogeneous TI layer shows that for a range of reflector dips and tilt angles of the symmetry axis, it is possible to build the anisotropic velocity field in the depth domain. We also extend our inversion procedure to layered TI media with curved interfaces and study its stability in the presence of noise and heterogeneity.
Traveltime and amplitude calculation using a perturbation approach
Authors: Shin Changsoo , Marfurt Kurt J. , Park Kwon Gyu , Min Dong‐Joo , Yoon Kwangjin , Yang Dongwoo , Ha Taeyoung , Ko Seungwon , Kim Wonsik , Hong Soonduk 
Published: September 2002

Accurate amplitudes and correct traveltimes are critical factors that govern the quality of prestack migration images. Because we never know the correct velocity initially, recomputing traveltimes and amplitudes of updated velocity models can dominate the iterative prestack migration procedure. Most tomographic velocity updating techniques require the calculation of the change of traveltime due to local changes in velocity. For such locally updated velocity models, perturbation techniques can be a significantly more economic way of calculating traveltimes and amplitudes than recalculating the entire solutions from scratch. In this paper, we implement an iterative Born perturbation theory applied to the damped wave equation algorithm. Our iterative Born perturbation algorithm yields stable solutions for models having velocity contrasts of 30% about the initial velocity estimate, which is significantly more economic than recalculating the entire solution.
Velocity analysis in the presence of amplitude variation
Authors: Sarkar Debashish , Baumel Robert T. , Larner Ken L. 
Published: September 2002

Conventional semblance velocity analysis is equivalent to modeling prestack seismic data with events that have hyperbolic moveout but no amplitude variation with offset (AVO). As a result of its assumption that amplitude is independent of offset, this method might be expected to perform poorly for events with strong AVO—especially for events with polarity reversals at large offset, such as reflections from tops of some class 1 and class 2 sands. We find that substantial amplitude variation and even phase change with offset do not compromise the conventional semblance measure greatly. Polarity reversal, however, causes conventional semblance to fail. The semblance method can be extended to take into account data with events that have amplitude variation, expressed by AVO intercept and gradient (i.e., the Shuey approximation). However, because of the extra degrees of freedom introduced in AVO‐sensitive semblance, resolution of the estimated velocities is decreased. This is because the data can be modeled acceptably with a range of combined erroneous velocity and AVO behavior. To address this problem, in addition to using the Shuey equation to describe the amplitude variation, we constrain the AVO parameters (intercept and gradient) to be related linearly within each semblance window. With this constraint we can preserve velocity resolution and improve the quality of velocity analysis in the presence of amplitude and even polarity variation with offset. Results from numerical tests suggest that the modified semblance is accurate in the presence of polarity reversals. Tests also indicate, however, that in the presence of noise, the signal peak in conventional semblance has better standout than does that in the modified semblance measures.
The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study
Authors:   HAPO Study Cooperative Research Group
Published: September 2002

AbstractObjective: The objective of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study is to clarify unanswered questions on associations of maternal glycemia, less severe than overt diabetes mellitus, with risks of adverse pregnancy outcome. This report describes the background and design of the HAPO Study. Methods: HAPO is a 5‐year investigator‐initiated prospective observational study that will recruit approximately 25 000 pregnant women in 10 countries. HAPO utilizes a Central Laboratory for measurement of key metabolic variables, a Clinical Coordinating Center, a Data Coordinating Center, and an independent Data Monitoring Committee. Glucose tolerance is assessed by a 75 g 2‐h OGTT at 24–32 weeks’ gestation. Results are unblinded to the woman and her caregivers if: fasting plasma glucose >5.8 mmol/l, 2‐h plasma glucose >11.1 mmol/l or any plasma glucose <2.5 mmol/l. Random plasma glucose measurement is performed at 34–37 weeks or if symptoms suggest hyperglycemia; results are unblinded for values ≥8.9 mmol/l. Sociodemographic and health history data are collected via questionnaire and medical record abstraction. Maternal blood is obtained for measurement of serum C‐peptide and hemoglobin A1c (HbA1C), cord blood for serum C‐peptide and plasma glucose, and a capillary specimen is taken between 1 and 2 h following delivery for neonatal plasma glucose. Neonatal anthropometrics are obtained, and follow‐up data are collected at 4–6 weeks post‐delivery. The primary outcomes to be assessed in relation to maternal glycemia are cesarean delivery, increased fetal size (macrosomia/LGA/obesity), neonatal morbidity (hypoglycemia), and fetal hyperinsulinism.
Faecal contamination and enterotoxigenic Escherichia coli in street-vended chili sauces in Mexico and its public health relevance
Authors: ESTRADA-GARCIA T. , CERNA J. F. , THOMPSON M. R. , LOPEZ-SAUCEDO C. 
Published: September 2002

The street-vended food industry provides employment and cheap ready-to-eat meals to a large proportion of the population in developing countries like Mexico, yet little is known about its role in the transmission of food borne diseases (FBD). Because of its wide consumption, street-vended chili sauces in Mexico are potential vehicles of FBD. An observational study was performed in Mexico City collecting 43 street-vended chili sauces. These sauces were prepared under poor hygienic conditions of handling and selling. Consumers add 4–8 ml of chili sauce per taco, ingest 2–5 tacos per meal and on average, 50 consumers frequent a stall per day. Seventeen (40%) samples were faecally contaminated and 2(5%) sauces harboured sufficient enterotoxigenic Escherichia coli to cause disease. We estimate that the consumption of only one of these chili sauces could result in ETEC disease in at least 21000 consumers per year, making them important potential vehicles of FBD.
Decline in epidemic of multidrug resistant Salmonella Typhi is not associated with increased incidence of antibiotic-susceptible strain in Bangladesh
Authors: RAHMAN M. , AHMAD A. , SHOMA S. 
Published: September 2002

Since 1987, multidrug resistant (MDR) strains of Salmonella Typhi, resistant simultaneously to ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole, have caused epidemics of severe typhoid fever in Asia and Africa. A retrospective analysis of blood culture results (1989–96) in a Diarrhoea Treatment Centre in Dhaka, Bangladesh detected MDR strains in 0.3% (8 of 2793) of samples in 1990. The isolation rate peaked to 3.2% (240 of 7501) in 1994 (P<0.01) and decreased to 1.8% (165 of 9348) in 1995 and further to 1.0% (82 of 8587) in 1996 (P<0.01 compared to 1994) indicating the emergence and decline of MDR typhoid epidemic. Ten of 15 MDR strains tested had a 176 kb conjugative R plasmid that mediates resistance to ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole to Escherichia coli K12. Unlike MDR strains, the isolation rate (∼3.3%) of susceptible S. Typhi remained remarkably unchanged during the study. The significant decrease in isolation of MDR strains suggests that cheaper and effective first-line antibiotics may re-emerge as drugs of choice for the treatment of typhoid fever in Bangladesh.