bluuebunny/crossref_metadata_2025 huggingface dataset:
Rush University Guidelines and Protocols for the Management of Hyperglycemia in Hospitalized Patients
Authors: Donaldson Sandra , Villanuueva Griselda , Rondinelli Lara , Baldwin David
Published: November 2006

The management of inpatient hyperglycemia has received much recent attention because of an expanding literature supporting the benefits of quality improvement and the creation of guidelines in this area. The authors began a process in 2002 to create modern protocols for glycemic control with intravenous insulin in their intensive care units and with subcutaneous basal-prandial insulin in all of their non-intensive care units. In this report, they describe both the process employed and the current protocols they are using. They also describe the process, perpetually ongoing, for educating nurses and residents in a large academic medical center. The annual cycle of senior residents passing on the regular insulin sliding scale to first-year interns and students can be broken. The hospital ward can be a valuable setting in which to teach basal/prandial insulin protocols, which will readily translate into the outpatient clinic. Where better to teach the importance and real-time usefulness of HbA1c than on the inpatient ward of a teaching hospital? Protocols to prevent and treat hypoglycemia can also be taught and widely accepted, hospital insulin formularies can be streamlined, and modern information technology can be used to track and improve multiple metrics of care for inpatients with hyperglycemia. The inpatient encounter with diabetic care can be a golden window of opportunity for patient as well as physician and nurse education.
Placebo/Nocebo Symptom Reporting in a Sham Herbal Supplement Trial
Authors: Link Jessica , Haggard Rob , Kelly Kimberly , Forrer Dan
Published: November 2006

The present study examined reports of placebo and nocebo symptoms in a college sample. The study was presented under the guise of a clinical trial to evaluate the effectiveness of an over-the-counter herbal supplement intended to enhance cognitive performance. Participants were informed they would be receiving either an herbal supplement or a placebo, and each was provided with a mock list of possible beneficial and adverse effects of the “supplement.” In fact, all participants received placebo. Symptoms were endorsed by a significant majority of participants following placebo ingestion. More important, results indicated that the few participants who believed they received an herbal supplement endorsed (via self-report) significantly more symptoms than those who believed they received a placebo. Neither anxiety nor social desirability was significantly related to symptom reporting. Results suggest that beliefs concerning treatment received may subsequently affect the degree of placebo response in a no-treatment group. Implications for clinical trials and future research are discussed.
Biomechanical Evaluation of Two Techniques for Double-Bundle Anterior Cruciate Ligament Reconstruction
Authors: Petersen Wolf , Tretow Henning , Weimann Andre , Herbort Mirco , Fu Freddie H. , Raschke Michael , Zantop Thore
Published: November 2006

Background

This research was undertaken to determine whether there is a need for a second tibial tunnel in anatomic anterior cruciate ligament reconstruction.

Hypothesis

Anatomic two-bundle reconstruction with two tibial tunnels restores knee anterior tibial translation in response to 134 N and to 5-N·m internal tibial torque combined with 10-N·m valgus torque more closely to normal than does double-bundle reconstruction with one tibial tunnel.

Study Design

Controlled laboratory study.

Methods

Ten cadaveric knees were subjected to a 134-N anterior tibial load at 0°, 30°, 60°, and 90° and to 5-N·m internal tibial torque and 10-N·m valgus torque at 15° and 30°. Resulting knee kinematics and in situ force in the anterior cruciate ligament or replacement graft were determined by using a robotic/universal force-moment sensor testing system for (1) intact, (2) anterior cruciate ligament–deficient, (3) double-bundle/one tibial tunnel, and (4) double-bundle/two tibial tunnels.

Results

Anterior tibial translation for the reconstruction with two tibial tunnels was significantly closer to that of the intact knee than was the reconstruction with one tibial tunnel at 0° and 30° of flexion (0° = 3.82 vs 6.0 mm, P < .05; 30° = 7.99 vs 11 mm, P < .05). The in situ force normalized to the intact anterior cruciate ligament for the reconstruction with two tibial tunnels was significantly higher than the in situ force of the reconstruction with one tibial tunnel (30° = 89 vs 82 N, P < .05). With a combined rotatory load, the anterior tibial translation of specimens with a tibial two-tunnel technique was significantly lower than that of specimens with one tunnel (0° = 5.7 vs 8.4 mm, P < .05; 30° = 7.5 vs 9.5 mm, P < .05).

Conclusions

Anatomic reconstruction with two tibial tunnels may produce a better biomechanical outcome, especially close to extension.

Clinical Relevance

At the time of initial fixation, there appears to be a small biomechanical advantage to the second tibial tunnel in the setting of two-bundle anterior cruciate ligament reconstruction.
Shear Behavior of 3D Orthogonal Woven Fabric Composites under High Strain Rates
Authors: Sun Baozhong , Gu Bohong
Published: November 2006

The shear behavior of 3D orthogonal woven composite materials at various strain rates is investigated using the punch shear method both for quasi-static and high strain rate tests. Shear behavior in warp and weft directions respectively at strain rates from 900 to 3400/s are tested using modified split Hopkinson pressure bar (SHPB). The quasi-static tests are conducted on an MTS 810.23 material tester and compared with shear behavior in high strain rates. The results indicate that the shear strain and stiffness are rate sensitive both in the warp and weft directions. The shear stiffness increases, and shear failure strain decreases with the increase of strain rate. However, the failure shear stress in the warp direction is rate-independent while it increases with the strain rate increasing in the weft direction due to the different rate-sensitivity of Twaron yarns and glass yarns. The shear failure becomes more severe as the strain rate increases both in the warp and weft directions. The failure is the punch shear in the warp direction and punch accompanied with crack in the weft direction at various strain rates.
Swedish Families’ Lived Experience When a Child Is First Diagnosed as Having Insulin-Dependent Diabetes Mellitus
Authors: Wennick Anne , Hallström Inger
Published: November 2006

Sweden has the second highest nationwide incidence of childhood diabetes in Europe, and it is rapidly increasing. The diagnosis of Type 1 insulin-dependent diabetes mellitus has been indicated as a crisis in the life of the individual and family. The purpose of this study was to elucidate the whole family’s lived experience when a child in the family is diagnosed as having diabetes. It was designed as a longitudinal, descriptive, inductive study including qualitative interviews. Family members in 12 families were recruited from a children’s university hospital in Sweden to participate in a series of three interviews: when first diagnosed, and 1 and 3 years after diagnosis. This article derives from the first interview. All invited families agreed to participate and were interviewed 1 to 3 months after diagnosis using a hermeneutic phenomenological approach. The family’s lived experience was identified as an ongoing learning process including learning about the inevitable and learning about the extent. The learning process was experienced as a recurrent phenomenon when the family was exposed to new situations or contexts. Therefore, individualized treatment may reduce the difficulties experienced in coping with the diabetic management regimen after discharge, thus making the transition smoother.
Responsive Evaluation and Performance Management
Authors: Van Der Knaap Peter
Published: November 2006

Worldwide, governments are under increasing pressure to deliver results. There is general recognition of the importance of performance measurement and a results-oriented focus for effective public management. The shift from inputs to outputs and outcomes is accompanied by an increased use of performance indicators and policy targets. Critics point to the negative effects of static forms of performance-measuring and governance: simplification, resistance to change and a strategic use of indicators. They stress the need for an approach to governance that respects and is responsive to diversity and dynamism. Such an approach to public policy should recognize the importance of stakeholders’ opinions and motives and, hence, dialogue. Herein, policy evaluation can help by systematically questioning the validity of policy goals and performance indicators. Based upon recent experiences with results-oriented budgeting in the Netherlands, this article outlines a possible approach to a responsive, ‘verifying’ policy evaluation. Against the background of the traditional functions of evaluation in results-oriented management (assessing efficiency and effectiveness), the paradoxical nature of performance indicators is considered: on the one hand they are ‘frozen ambitions’, yet on the other they must facilitate dialogue and learning. Building on these attributes, a dynamic perspective on evaluation is put forward. In this, using information and insights from stakeholders, policy evaluation should explicitly question the validity of the policy objectives and performance indicators without compromising their value and significance altogether. In this way, the evaluator may fulfil the ambition of the ‘argumentative turn’ in policy evaluation: to help to raise the quality of dialogue and decision-making between stakeholders.
The Effects of Institutional Design on the Utilization of Evaluation
Authors: Balthasar Andreas
Published: November 2006

This article presents some of the results from a study in progress, focusing on the influence of the institutional distance between evaluators and evaluees on the utilization of evaluations. The basis for the results presented here is an analysis of ten case studies from Switzerland. These cases involve evaluations that were carried out in different institutional contexts, with widely varying institutional distances between evaluators and evaluees. ‘Qualitative Comparative Analysis’ (QCA) has been used to interpret the cases, in order to allow a combination of case-and variable-centred comparisons. The analysis indicates that, under certain conditions, the institutional distance between evaluators and evaluees has no influence on the use of evaluations. In particular, formative objectives can be achieved quite independently of distance. When interpreting the results, however, one should not neglect the fact that they are solely based on a systematic evaluation of ten case studies with QCA. Generalization is not possible on this basis, nor is this the aim of the present article. On the contrary, the objective is to continue developing the debate about the influence of the institutional distance between evaluators and evaluees on the utilization of evaluations.
The Trident
Authors: Ellis Roger , Hogard Elaine
Published: November 2006

This contribution describes a ‘trident’ approach to programme evaluation, which focuses on three ‘prongs’ that might be used to structure an evaluation. These prongs represent the measurement of outcomes; the description and analysis of process; and the sampling of multiple stakeholder perspectives. The prongs thus address the questions: did it work, what happened and what did stakeholders think of it? The origins of the approach are described and its approach related to the needs of contractors and the purposes of evaluation. The methodological implications of the three ‘prongs’ are considered, including objective specification and outcome measurement; approaches to process description and analysis; and the techniques available to sample stakeholder perspectives. Three case studies of the trident in action are presented, including evaluations of clinical facilitation for student nurses; a skills laboratory for the acquisition of clinical techniques; and a scheme for the educational, social and health development of children under the age of four.
Ectopic Pregnancy Within a Cesarean Section Scar
Authors: Rajan Shamin
Published: November 2006

A gestational sac implanted in the anterior portion of the lower uterine segment is characteristic of a cesarean delivery scar pregnancy, although it is the rarest of locations for an ectopic pregnancy. More common locations for an ectopic pregnancy include the isthmus of the tube, ovaries, uterine cornua, and abdomen. In addition to sonographic diagnosis, elevated serum beta-human chorionic gonadotropin levels can help to confirm the pregnancy. If detected early, a future pregnancy may be possible; otherwise, the patient is at risk for uterine scar rupture, hemorrhage, and maternal morbidity. Ectopic pregnancies are becoming more prevalent, although it is difficult to say if it is due to an increase in cesarean sections performed, the use of in vitro fertilization procedures, or better diagnosis and documentation. This case illustrates implantation of a pregnancy within the scar of a previous cesarean section delivery, diagnosed with pelvic, endovaginal, and 3D sonography.
Talc: an indicator of recent anthropogenic activity
Authors: Ruch P. , Bapst A. , Kübler B.
Published: November 2006

Talc is very often an important constituent of suspended matter in marine and lacustrine environments but is rarely detected in sediments. The presence of talc is usually attributed to its industrial and agricultural application. Its recent anthropogenic use, long residence time in the water column due to its small particle size, transport by surface currents and winds, and its tendency to resuspension from the sediment are factors which contribute to the preferential detection of talc in suspended matter.
Fe(III)-pillared montmorillonites: preparation and characterization
Authors: Martin-Luengo M. A. , Martins-Carvalho H. , Ladriere J. , Grange P.
Published: November 2006

Porous, high surface area solids have been prepared by intercalation of a trinuclear acetato hydroxy-iron(III) complex cation between the layers of montmorillonite and the resulting materials have been characterized in order to identify the nature of the iron intercalates formed during and after the cation exchange step. Spectroscopic studies demonstrated that at 623 K, the iron complex was partially decomposed and α-Fe2O3 was only detected in samples heated at high temperatures, > 923 K. Under these conditions, the dehydroxylation of the montmorillonite layers led to the collapse of the structure.
The formation of corundum and aluminous hematite by the thermal dehydroxylation of aluminous goethite
Authors: Wells M. A. , Gilkes R. J. , Anand R. R.
Published: November 2006

Dehydroxylation of synthetic and natural goethites with a range of Al-substitution from 0–28 mole% was investigated with a view to predicting the behaviour of soil goethites heated by bush fires. Hematites formed at temperatures ≤ 500°C retain the initial Al-content of the precursor goethite up to a maximum of 28 mole% Al. Loss of Al from the hematite structure occurred at 700°C for synthetic hematites with levels of substitution ≥18 mole% Al, but no crystalline alumina phase was present. Crystallization of corundum occurred for synthetic Al-goethites with levels of substitution ≥18 mole% when heated at 900°C. Formation of corundum reduces the maximum level of Al-substitution in hematites to ∼ 12 mole%. The exsolved corundum occurs as aggregated, platy crystals, 40–45 nm in diameter, containing a maximum of 7 mole% Fe. Al-substituted maghemite (7 mole% Al) formed from high Al-goethites heated at 900°C. Although some corundum in soils may be produced by heating of aluminous goethite by fires, the absence of corundum in natural Al-goethites calcined at 900°C, and the very high temperature (900°C) at which corundum formed from synthetic goethite suggest that other sources of Al may be required as precursors for the corundum formed by heating of soils.
Luminescence and ESR studies of relationships between O−-centres and structural iron in natural and synthetically hydrated kaolinites
Authors: Coyne Lelia M. , Costanzo Patricia M. , Theng B. K. G.
Published: November 2006

Luminescence, induced by dehydration and by wetting with hydrazine and unsymmetrically substituted hydrazine, and related ESR spectra have been observed from several kaolinites, synthetically hydrated kaolinites, and metahalloysites. The amine-wetting luminescence results suggest that intercalation, not a chemiluminescence reaction, is the luminescence trigger. Correlation between dehydration-induced luminescence and g = 2 ESR signals associated with O−-centres in several natural halloysites, and concurrent diminution of the intensity of both these signal types as a function of aging in two 8.4 Å synthetically hydrated kaolinites, confirm a previously-reported relationship between the luminescence induced by dehydration and in the presence of O−-centres (holes, i.e., electron vacancies) in the tetrahedral sheet. Furthermore, the ESR spectra of the 8.4 Å hydrate showed a concurrent change in the line shape of the g = 4 signal from a shape usually associated with structural Fe in an ordered kaolinite, to a simpler one typically observed in more disordered kaolinite, halloysite, and montmorillonite. Either structural Fe centres and the O−-centres interact, or both are subject to factors previously associated with degree of order. The results question the long-term stability of the 8.4 Å hydrate, although XRD does not indicate interlayer collapse over this period. Complex inter-relationships are shown between intercalation, stored energy, structural Fe, and the degree of hydration which may be reflected in catalytic as well as spectroscopic properties of the clays.
Hematite Identification in Pseudo-Particles of Moroccan Rubified Soils
Authors: Michalet R. , Guillet B. , Souchier B.
Published: November 2006

In Moroccan calcareous mountains, red soils are distinguishable from brown soils, not only by their colour but also by their microaggregated structure. Clay mineral dispersion studies of these soils were carried out by increasing pH, after different treatments. The formation of the pseudo-particles appears to be dependent on the fixation of amorphous Fe on clay and on the chemical binding of those clays by amorphous Al-hydroxy-polycations. This can be explained by the high isoelectric point of ferric compounds such as ferrihydrite which are soluble in ammonium oxalate. Based on these results and using techniques of granulometric analysis, red clays aggregated in pseudo-particles were separated from less rubified clays. Hematite was identified in pseudoparticles from red soils and an increase of amorphous Fe has been shown in aggregated clays. These microstructural conditions characterizing rubification could also favour it, by creating microsites where water activity decreases and allows the crystallization of hematite by dehydration of ferrihydrite.
First Data on Clay Mineral Assemblages and Geochemical Characteristics of Toarcian Sedimentation in the umbriamarche basin (central italy)
Authors: Ortega-Huertas M. , Monaco P. , Palomo I.
Published: November 2006

A moderate to high rate of clay sedimentation is characteristic of the Toarcian sequences in the Umbria-Marche basin. The clay mineral assemblages and geochemical characteristics indicate that the Marne di Monte Serrone Formation and the Rosso Ammonitico Umbro-Marchigiano Unit were deposited in a shallow marine environment. In this general palaeogeographic scheme, a reducing subenvironment must have exsisted in which black shale-type facies were deposited resulting in geochemical anomalies in As, Sb, Zn, Co, Cu, Pb, V, Cr, and Ba, among other elements. The high values of both the detrital index and the Ce/Ce* ratio reveal the influence of proximal emerged reliefs. It is suggested that the palaeosoils that developed on the Liassic carbonate Laziale-Abuzzese platform were the source area of these sediments, following a palaeogeographic scheme analogous to that proposed for the Betic Cordilleras (Spain) during the Middle Domerian to Middle Toarcian. The positive and negative Eu anomalies are due to the decisive influence of the weathering process in which sediments with heterogeneous Eu anomaly size were mixed. The final distribution pattern of REE is the result of the different environments to which the clay minerals were subjected and the differences in intensity of weathering.
Controls on Clay Mineral Distribution and Chemistry in the Early Permian Rotliegend of Germany
Authors: Platt J. D.
Published: November 2006

Authigenic clay minerals in the German Rotliegend formed mainly at burial depths >1.5 km. Illite is the dominant cement, although kaolinite, dickite and early radial chlorite are abundant locally. Illites contain more AI and late chlorites more AI and Fe in sequences showing extensive grain dissolution. This relationship between clay chemistry and grain dissolution suggests that clay cementation is linked to grain dissolution. Sequences at relatively shallow burial depths (<3-5 km) contain less clay cement. In the more deeply buried sections, increased illite and kandite cementation, together with extensive grain dissolution, is evident where the Rotliegend is juxtaposed against Carboniferous Coal Measures. Faults also acted as important conduits for acidic fluids. Illite and kandite growth occurred at similar depths and from waters of similar isotopic composition (618O = 1-6‰ SMOW) throughout most of the Southern Permian Basin. However, the timing of illite growth varied between areas and corresponded to periods to tectonic activity.
Leukocytosis as a major thrombotic risk factor in patients with polycythemia vera
Authors: Landolfi Raffaele , Di Gennaro Leonardo , Barbui Tiziano , De Stefano Valerio , Finazzi Guido , Marfisi RosaMaria , Tognoni Gianni , Marchioli Roberto ,   for the European Collaboration on Low-Dose Aspirin in Polycythemia Vera (ECLAP)
Published: November 2006

In polycythemia vera, vascular risk assessment is based on age and thrombotic history, while the role of other potential predictors of this risk is still uncertain. Thus, we exploited the large database collected by the observational study of the European Collaboration on Low-Dose Aspirin in Polycythemia Vera (ECLAP) to investigate the association of hematologic variables and cardiovascular risk factors with the thrombotic risk. Among 1638 polycythemic patients followed for 2.7 ± 1.3 years, there were 205 thromboses. Subjects with hypertension had a mild nonsignificant increase in the risk of arterial thrombosis, while this risk was significantly increased by smoking (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.15-3.14; P = .012). The time-dependent analysis adjusted for potential confounders showed that patients with a white blood cell count above 15 × 109/L, compared with those with a white blood cell count below 10 × 109/L, had a significant increase in the risk of thrombosis (HR, 1.71; 95% CI, 1.10-2.65; P = .017), mainly deriving from an increased risk of myocardial infarction (HR, 2.84; 95% CI, 1.25-6.46; P = .013). Thus, leukocyte count may help in defining the vascular risk of polycythemic subjects.
Imprinting modulates processing of visual information in the visual wulst of chicks
Authors: Maekawa Fumihiko , Komine Okiru , Sato Katsushige , Kanamatsu Tomoyuki , Uchimura Motoaki , Tanaka Kohichi , Ohki-Hamazaki Hiroko
Published: November 2006

Background

Imprinting behavior is one form of learning and memory in precocial birds. With the aim of elucidating of the neural basis for visual imprinting, we focused on visual information processing.

Results

A lesion in the visual wulst, which is similar functionally to the mammalian visual cortex, caused anterograde amnesia in visual imprinting behavior. Since the color of an object was one of the important cues for imprinting, we investigated color information processing in the visual wulst. Intrinsic optical signals from the visual wulst were detected in the early posthatch period and the peak regions of responses to red, green, and blue were spatially organized from the caudal to the nasal regions in dark-reared chicks. This spatial representation of color recognition showed plastic changes, and the response pattern along the antero-posterior axis of the visual wulst altered according to the color the chick was imprinted to.

Conclusion

These results indicate that the thalamofugal pathway is critical for learning the imprinting stimulus and that the visual wulst shows learning-related plasticity and may relay processed visual information to indicate the color of the imprint stimulus to the memory storage region, e.g., the intermediate medial mesopallium.
Carotid ultrasound phenotypes in vulnerable populations
Authors: Riccio Silvia A , House Andrew A , Spence J David , Fenster Aaron , Parraga Grace
Published: November 2006

Background

Biomarkers of carotid atherosclerosis range from those that are widely available and relatively simple to measure such as serum cholesterol levels, and B-mode Ultrasound measurement of intima media thickness (IMT) to those that are more complex and technologically demanding but perhaps potentially more sensitive and specific to disease such as total plaque volume and total plaque area measured from 3-dimensional ultrasound images. In this study we measured and compared intima media thickness (IMT), total plaque volume (TPV) and total plaque area (TPA) in two separate populations, both vulnerable to carotid atherosclerosis.

Methods

In total, 88 subjects (mean age 72.8) with carotid stenosis of at least 60%, based on a peak Doppler flow, and 82 subjects (mean age 60.9) with diabetic nephropathy were assessed in a cross-sectional study. Conventional atherosclerotic risk factors were examined and the associations and correlations between these and carotid ultrasound phenotypes measured from B-mode and 3-dimensional ultrasound images were assessed.

Results

IMT and TPV were only modestly correlated in the two separate populations (r = .6, p < .01). ANOVA analyses indicated that both IMT and TPV were significantly associated with age (p < .001) and Framingham score (p < .05), but only TPV was associated with diabetes (p < .001) and presence of plaque ulcerations (p < .01)

Conclusion

IMT and TPV were modestly correlated in a diabetic patient population and only TPV was associated with diabetes and the presence of plaque ulcerations in a diabetic population and carotid stenosis group. The 3-dimensional information provided by TPV can be critically important in unmasking association with risk factors not observed with less complex single-dimension assessments of carotid atherosclerosis such as those provided by IMT.
Growth-rate regulated genes have profound impact on interpretation of transcriptome profiling in Saccharomyces cerevisiae
Authors: Regenberg Birgitte , Grotkjær Thomas , Winther Ole , Fausbøll Anders , Åkesson Mats , Bro Christoffer , Hansen Lars Kai , Brunak Søren , Nielsen Jens
Published: November 2006

Background

Growth rate is central to the development of cells in all organisms. However, little is known about the impact of changing growth rates. We used continuous cultures to control growth rate and studied the transcriptional program of the model eukaryote Saccharomyces cerevisiae, with generation times varying between 2 and 35 hours.

Results

A total of 5930 transcripts were identified at the different growth rates studied. Consensus clustering of these revealed that half of all yeast genes are affected by the specific growth rate, and that the changes are similar to those found when cells are exposed to different types of stress (>80% overlap). Genes with decreased transcript levels in response to faster growth are largely of unknown function (>50%) whereas genes with increased transcript levels are involved in macromolecular biosynthesis such as those that encode ribosomal proteins. This group also covers most targets of the transcriptional activator RAP1, which is also known to be involved in replication. A positive correlation between the location of replication origins and the location of growth-regulated genes suggests a role for replication in growth rate regulation.

Conclusion

Our data show that the cellular growth rate has great influence on transcriptional regulation. This, in turn, implies that one should be cautious when comparing mutants with different growth rates. Our findings also indicate that much of the regulation is coordinated via the chromosomal location of the affected genes, which may be valuable information for the control of heterologous gene expression in metabolic engineering.
A novel approach to the model appraisal and resolution analysis of regularized geophysical inversion
Authors: Zhdanov Michael S. , Tolstaya Ekaterina
Published: November 2006

The existing techniques for appraisal of geophysical inverse images are based on calculating the model resolution and the model covariance matrices. In some applications, however, it becomes desirable to evaluate the upper bounds of the variations in the solution of the inverse problem. It is possible to use the Cauchy inequality for the regularized least-squares inversion to quantify the ability of an experiment to discriminate between two similar models in the presence of noise in the data. We present a new method for resolution analysis based on evaluating the spatial distribution of the upper bounds of the model variations and introduce a new characteristic of geophysical inversion, resolution density, as an inverse of these upper bounds. We derive an efficient numerical technique to compute the resolution density based on the spectral Lanczos decomposition method (SLDM). The methodology was tested on 3D synthetic linear and nonlinear electromagnetic (EM) data inversions, and also to interpret the helicopter-borne EM data collected by INCO Exploration in the Voisey’s Bay area of Canada.
Estimation of distant relief effect in gravimetry
Authors: Mikuška Ján , Pašteka Roman , Marušiak Ivan
Published: November 2006

We analyze gravitational effects of distant topographic and bathymetric relief beyond the (earth-centered) angular distance of [Formula: see text] (i.e., beyond the outer limit of the Hayford-Bowie zone O, or approximately [Formula: see text]) using a spherical earth model. Our results support current procedures that neglect distant relief effects for most local gravity surveys but show their potential importance for continental- and global-scale surveys. The distant relief can produce horizontal gradients as large as [Formula: see text] [Formula: see text]. In mountainous areas, the gravitational effect of the distant relief is significant, even for local surveys, although the vertical gradient of the distant relief effect never exceeds [Formula: see text] [Formula: see text] on the earth’s surface.
Electrical and GPR prospecting at Palo Blanco archaeological site, northwestern Argentina
Authors: Martino Luis , Bonomo Néstor , Lascano Eugenia , Osella Ana , Ratto Norma
Published: November 2006

We conducted a geophysical survey at the Palo Blanco archaeological site located in Catamarca, Argentina. Age estimates from radiocarbon dating indicate first occupation of the site around 1500 years ago. The first description of thesite was done in 1960. At that time, five residential units with different architectural arrangements were reported. These structures had different levels of deterioration caused by exposure and human activities. Some of these original structures have become completely covered by sediments. To aid in the design of efficient excavation plans, detailed maps are required to locate the buried walls. For this purpose, we conducted geophysical surveys over one of the structures. We had poor documentation about the structure at the time of the survey. Only one of the walls described in the earlier report was partially visible. We used two geophysical methods: ground-penetrating radar (GPR) and electrical resistivity. We performed 2D inversion of the resistivity data, together with numerical GPR simulations. These helped to distinguish the expected reflection events from others, aiding in a correct interpretation of the data. Finally, we made a complementary interpretation of the resistivity and GPR data to compile a detailed map of the selected structure. We found that considering the two methods independently would have led to an incomplete map. We delineated a much more complex structure than originally expected and designed an excavation plan which was carried out. The layout of the rooms of the structure fully matched the predictions based on the interpretation used in detecting the walls and their depths. In this way, the geophysical forecasts were confirmed after excavation.
Repeatability study of helicopter-borne electromagnetic data
Authors: Huang Haoping , Cogbill Allen
Published: November 2006

Helicopter-borne electromagnetic (EM) responses depend very much upon the altitude and plan-view flight path, especially when the resistivity of the terrain’s materials varies laterally and/or vertically. Spatially consistent flight paths are required for repeatability analysis of the EM data. Caution should be used in examining the repeatability of the EM data because poor repeatability could result from spatially inconsistent flight paths. However, the apparent resistivity converted from the EM responses is virtually independent of the sensor altitude and directly reflects variations in the resistivity. Therefore, more meaningful repeatability analyses are achieved if the apparent resistivity is used instead of the EM response itself. We have analyzed 32 flights over a control line by using the EM amplitude, the phase, and the apparent resistivity. Our results show that the crosscorrelation for all 496 paired combinations of flights is better for the apparent resistivity than for the EM amplitude or phase. The apparent-resistivity data have average correlation coefficients from 0.89 to 0.94 as the frequency increases, whereas the amplitude and the phase data have average correlation coefficients from 0.78 to 0.85 without obvious frequency dependency.
Texture-based classification of ground-penetrating radar images
Authors: Moysey Stephen , Knight Rosemary J. , Jol Harry M.
Published: November 2006

Image texture is one of the key features used for the interpretation of radar facies in ground-penetrating radar (GPR) data. Establishing quantitative measures of texture is therefore a critical step in the effective development of advanced techniques for the interpretation of GPR images. This study presents the first effort to evaluate whether different measures of a GPR image capture the features of the data that, when coupled with a neural network classifier, are able to reproduce a human interpretation. The measures compared in this study are instantaneous amplitude and frequency, as well as the variance, covariance, Fourier-Mellin transform, R-transform, and principle components (PCs) determined for a window of radar data. A [Formula: see text] GPR section collected over the William River delta in Saskatchewan, Canada, is used for the analysis. We found that measures describing the local spatial structure of the GPR image (i.e., covariance, Fourier-Mellin, R-transform, and PCs) were able to reproduce human interpretations with greater than 93% accuracy. In contrast, classifications based on image variance and the instantaneous attributes agreed with the human interpretation less than 68% of the time. Among the textural measures that preserve spatial structure, we found that the best ones are insensitive to within facies variability while emphasizing differences between facies. For the specific case of the William River delta, the Fourier-Mellin transform, which retains information about the spatial correlation of reflections while remaining insensitive to their orientation, outperformed the other measures. Our work in describing radar texture provides an important first step in defining quantitative criteria that can be used to aid in the classification of radar data.
Suppressing unwanted internal reflections in prestack reverse-time migration
Authors: Fletcher Robin P. , Fowler Paul J. , Kitchenside Phil , Albertin Uwe
Published: November 2006

Prestack reverse-time migration, a wave-equation technique using two-way propagation, correctly handles multiarrivals and enables imaging of overturned reflections. However, image artifacts occur when backscattered waves cross-correlate. These artifacts are particularly strong where high-velocity contrasts occur. A method for removing unwanted internal reflections during propagation of both the source and receiver wavefields is presented. This method applies a directional damping term to the wave equation in areas of the velocity model where unwanted reflections occur. Tests on synthetic data show good suppression of image artifacts.
Seismoelectric numerical modeling on a grid
Authors: Haines Seth S. , Pride Steven R.
Published: November 2006

Our finite-difference algorithm provides a new method for simulating how seismic waves in arbitrarily heterogeneous porous media generate electric fields through an electrokinetic mechanism called seismoelectric coupling. As the first step in our simulations, we calculate relative pore-fluid/grain-matrix displacement by using existing poroelastic theory. We then calculate the electric current resulting from the grain/fluid displacement by using seismoelectric coupling theory. This electrofiltration current acts as a source term in Poisson’s equation, which then allows us to calculate the electric potential distribution. We can safely neglect induction effects in our simulations because the model area is within the electrostatic near field for the depth of investigation (tens to hundreds of meters) and the frequency ranges ([Formula: see text] to [Formula: see text]) of interest for shallow seismoelectric surveys.We can independently calculate the electric-potential distribution for each time step in the poroelastic simulation without loss of accuracy because electro-osmotic feedback (fluid flow that is perturbed by generated electric fields) is at least [Formula: see text] times smaller than flow that is driven by fluid-pressure gradients and matrix acceleration, and is therefore negligible. Our simulations demonstrate that, distinct from seismic reflections, the seismoelectric interface response from a thin layer (at least as thin as one-twentieth of the seismic wavelength) is considerably stronger than the response from a single interface. We find that the interface response amplitude decreases as the lateral extent of a layer decreases below the width of the first Fresnel zone. We conclude, on the basis of our modeling results and of field results published elsewhere, that downhole and/or crosswell survey geometries and time-lapse applications are particularly well suited to the seismoelectric method.
Plane-wave depth migration
Authors: Stoffa Paul L. , Sen Mrinal K. , Seifoullaev Roustam K. , Pestana Reynam C. , Fokkema Jacob T.
Published: November 2006

We present fast and efficient plane-wave migration methods for densely sampled seismic data in both the source and receiver domains. The methods are based on slant stacking over both shot and receiver positions (or offsets) for all the recorded data. If the data-acquisition geometry permits, both inline and crossline source and receiver positions can be incorporated into a multidimensional phase-velocity space, which is regular even for randomly positioned input data. By noting the maximum time dips present in the shot and receiver gathers and constant-offset sections, the number of plane waves required can be estimated, and this generally results in a reduction of the data volume used for migration. The required traveltime computations for depth imaging are independent for each particular plane-wave component. It thus can be used for either the source or the receiver plane waves during extrapolation in phase space, reducing considerably the computational burden. Since only vertical delay times are required, many traveltime techniques can be employed, and the problems with multipathing and first arrivals are either reduced or eliminated. Further, the plane-wave integrals can be pruned to concentrate the image on selected targets. In this way, the computation time can be further reduced, and the technique lends itself naturally to a velocity-modeling scheme where, for example, horizontal and then steeply dipping events are gradually introduced into the velocity analysis. The migration method also lends itself to imaging in anisotropic media because phase space is the natural domain for such an analysis.
A simple method of predicting S-wave velocity
Authors: Lee Myung W.
Published: November 2006

Prediction of shear-wave velocity plays an important role in seismic modeling, amplitude analysis with offset, and other exploration applications. This paper presents a method for predicting S-wave velocity from the P-wave velocity on the basis of the moduli of dry rock. Elastic velocities of water-saturated sediments at low frequencies can be predicted from the moduli of dry rock by using Gassmann’s equation; hence, if the moduli of dry rock can be estimated from P-wave velocities, then S-wave velocities easily can be predicted from the moduli. Dry rock bulk modulus can be related to the shear modulus through a compaction constant. The numerical results indicate that the predicted S-wave velocities for consolidated and unconsolidated sediments agree well with measured velocities if differential pressure is greater than approximately [Formula: see text]. An advantage of this method is that there are no adjustable parameters to be chosen, such as the pore-aspect ratios required in some other methods. The predicted S-wave velocity depends only on the measured P-wave velocity and porosity.
Imaging reflection-blind areas using transmitted PS-waves
Authors: Luo Yi , Liu Qinglin , Wang Yuchun E. , AlFaraj Mohammed N.
Published: November 2006

We illustrate the use of mode-converted transmitted (e.g., PS- or SP-) waves in vertical seismic profiling (VSP) data for imaging areas above receivers where reflected waves cannot illuminate. Three depth-domain imaging techniques — move-out correction, common-depth-point (CDP) mapping, and prestack migration — are described and used for imag-ing the transmitted waves. Moveout correction converts an offset VSP trace into a zero-offset trace. CDP mapping maps each sample on an input trace to the location where the mode conversion occurs. For complex media, prestack migration (e.g., reverse-time migration) is used. By using both synthetic and field VSP data, we demonstrate that images derived from transmissions complement those from reflections. As an important application, we show that transmitted waves can illuminate zones above highly de-viated or horizontal wells, a region not imaged by reflection data. Because all of these benefits are obtained without extra data acquisition cost, we believe transmission imag-ing techniques will become widely adopted by the oil in-dustry.
Gassmann's fluid substitution and shear modulus variability in carbonates at laboratory seismic and ultrasonic frequencies
Authors: Adam Ludmila , Batzle Michael , Brevik Ivar
Published: November 2006

Carbonates have become important targets for rock property research in recent years because they represent many of the major oil and gas reservoirs in the world. Some are undergoing enhanced oil recovery. Most laboratory studies to understand fluid and pressure effects on reservoir rocks have been performed on sandstones, but applying relations developed for sandstones to carbonates is problematic, at best. We measure in the laboratory nine carbonate samples from the same reservoir at seismic (3–3000 Hz) and ultrasonic [Formula: see text] frequencies. Samples are measured dry (humidified) and saturated with liquid butane and brine. Our carbonate samples showed typical changes in moduli as a function of porosity and fluid saturation. However, we explore the applicability of Gassmann’s theory on limestone and dolomite rocks in the context of shear- and bulk-modulus dispersion and Gassmann’s theory assumptions. For our carbonate set at high differential pressures and seismic frequencies, the bulk modulus of rocks with high-aspect-ratio pores and dolomite mineralogy is predicted by Gassmann’s relation. We also explore in detail some of the assumptions of Gassmann’s relation, especially rock-frame sensitivity to fluid saturation. Our carbonate samples show rock shear-modulus change from dry to brine saturation conditions, and we investigate several rock-fluid mechanisms responsible for this change. To our knowledge, these are the first controlled laboratory experiments on carbonates in the seismic frequency range.
An Overview of Pheochromocytoma
Authors: MANGER WILLIAM M.
Published: November 2006

Abstract:  Tragically as many as 50% of pheochromocytomas are discovered at autopsy, mainly because the diagnosis of this neuroendocrine tumor was not considered. Missing the diagnosis almost invariably results in devastating cardiovascular complications or death. Clinicians must always think of pheochromocytoma whenever evaluating a patient with sustained or paroxysmal hypertension or any manifestations suggesting hypercatecholaminemia. Very rarely, familial pheochromocytomas may cause no hypertension, symptoms, or signs. But biochemical testing can always establish the presence or absence of a pheochromocytoma, and localization with magnetic resonance imaging, computed tomography, or 131I or 123I‐MIBG is almost always possible.
A Case of Catecholamine and Glucocorticoid Excess Syndrome Due to a Corticotropin‐Secreting Paraganglioma
Authors: WILLENBERG HOLGER S. , FELDKAMP JOACHIM , LEHMANN REINER , SCHOTT MATTHIAS , GORETZKI PETER E. , SCHERBAUM WERNER A.
Published: November 2006

Abstract:  We present a case of a 61‐year‐old female patient with ectopic corticotropin (ACTH) syndrome, hypopituitarism, and catecholamine excess due to a paraganglioma at the inferior pole of the left kidney. In this article we discuss the hormonal findings in the patient and its consequences, the pitfalls of the endocrine workup, and the results of our immunohistological and molecular studies in more detail.