bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative lithostratigraphic interpretation of seismic data for characterization of the Unayzah Formation in central Saudi Arabia
Authors: Fournier Frédérique , Déquirez Pierre‐Yves , Macrides Costas G. , Rademakers Marty 
Published: September 2002

A lithostratigraphic interpretation of seismic data sets covering the Unayzah fluviatile formation in central Saudi Arabia has allowed us to map the sandstone distribution and to characterize the average porosity of the formation. First, sandstone distribution was predicted through seismic facies identification and interpretation with well information. Seismic facies analysis was performed with statistical pattern recognition applied to the portions of traces at the reservoir level, these traces being characterized by a series of seismic attributes. A good convergence of results from unsupervised and supervised pattern recognition was observed. This increases the confidence in the interpretation of sandprone facies. Second, using a statistical relationship between the reservoir average porosity defined at the wells and selected amplitudes of adjacent traces, the porosity was predicted all over the area covered by the seismic information. The model was based on a multivariate linear regression, showing satisfying quality criteria (correlation coefficient, residuals, etc.). The porosity variation predicted from the seismic data complements the sandstone distribution, derived from the seismic facies analysis. In particular, some areas where sandstones are predicted do not appear as porous as could have been suspected from their lithological content, perhaps as the result of diagenetic effects. Last, seismic facies analysis with pattern recognition applied to 2‐D exploratory lines, partly intersecting the 3‐D data set, led to the identification of potential prospects (Unayzah interval with a high sand–shale ratio).
Converted‐wave seismic exploration: Methods
Authors: Stewart Robert R. , Gaiser James E. , Brown R. James , Lawton Don C. 
Published: September 2002

Multicomponent seismic recording (measurement with vertical‐ and horizontal‐component geophones and possibly a hydrophone or microphone) captures the seismic wavefield more completely than conventional single‐element techniques. In the last several years, multicomponent surveying has developed rapidly, allowing creation of converted‐wave or P‐S images. These make use of downgoing P‐waves that convert on reflection at their deepest point of penetration to upcoming S‐waves. Survey design for acquiring P‐S data is similar to that for P‐waves, but must take into account subsurface VP/VSvalues and the asymmetric P‐S ray path. P‐S surveys use conventional sources, but require several times more recording channels per receiving location. Some special processes for P‐S analysis include anisotropic rotations, S‐wave receiver statics, asymmetric and anisotropic binning, nonhyperbolic velocity analysis and NMO correction, P‐S to P‐P time transformation, P‐S dip moveout, prestack migration with two velocities and wavefields, and stacking velocity and reflectivity inversion for S‐wave velocities.Current P‐S sections are approaching (and in some cases exceeding) the quality of conventional P‐P seismic data. Interpretation of P‐S sections uses full elastic ray tracing, synthetic seismograms, correlation with P‐wave sections, and depth migration. Development of the P‐S method has taken about 20 years, but has now become commercially viable.
Seismic data reconstruction by inversion to common offset
Authors: Chemingui Nizar , Biondi Biondo 
Published: September 2002

Preserving amplitude information when imaging 3‐D multichannel seismic data is a challenging task. The imaging process can be described as seeking the inverse for a large matrix that relates the data to a reflectivity model. Due to irregular coverage at the surface and uneven illumination of the subsurface, the matrix is often ill‐conditioned and its coefficients are badly scaled. We present a new approach for regularizing the coverage of 3‐D surveys by partial imaging before migration. After regularization, 3‐D data become better suited for prestack migration using either “true amplitude” Kirchhoff methods or wave extrapolation techniques.Posing partial stacking before migration as an inverse problem, we develop a new optimization technique named “inversion to common offset” (ICO) that solves for optimal partial stacks from multifold 3‐D data. The inversion approach takes advantage of the redundancy of information present in multichannel recording to recover densely and regularly sampled common‐offset common‐azimuth volumes. The reconstruction of each of these volumes combines data from multiple incomplete experiments over a common earth model to simulate the ideal data that would have been recorded from a single common‐offset common‐azimuth experiment. The method is based on the inversion of a partial prestack migration operator that maps seismic data from a given acquisition geometry to an arbitrary one. This data mapping operator is the azimuth moveout operator (AMO). The main advantage of ICO is that the AMO operator is compact and consequently cheaper to apply than other imaging operators, such as full 3‐D prestack migration.We present a cost‐effective implementation of ICO based on a log‐stretch transformation of the time axis. After this transformation, AMO becomes time invariant, so the inversion can be performed in the Fourier domain on each temporal‐frequency slice independently. To accelerate the convergence of the iterative solution, we precondition the system of linear equations by two diagonal transformations that scale the rows and columns of the modeling operator. A stable solution is achieved by adding a penalty function that constrains the spatial variability of the model.Results of applying ICO to a field 3‐D land survey show that we can recover the high‐frequency features of the reflectivity function from a severely undersampled data set obtained by decimating a densely sampled prestack data set. The images produced by prestack migration after regularization are superior to those produced by direct migration of the decimated data.
Comparison of vaccination strategies for the control of dog rabies in Machakos District, Kenya
Authors: KITALA P. M. , McDERMOTT J. J. , COLEMAN P. G. , DYE C. 
Published: September 2002

Demographic and epidemiological field data were used in a deterministic model to describe dog rabies transmission in Machakos District, Kenya and to predict the impact of potential vaccination strategies for its control. The basic reproduction number (R0) was estimated to be 2.44 (1.52–3.36, 95% confidence limits). There were three key model predictions. The first was that a threshold dog density (KT) of 4.5 dogs km−2 (3.8–5.2 dogs km−2, 95% confidence limits) was required to maintain transmission. The second was that the estimated annual vaccination rate of 24% failed to decrease incidence and actually increased the stability of transmission and may be counter-productive. Thirdly, to control rabies, it was predicted that 59% (34%–70%, 95% confidence limits) of dogs should be vaccinated at any one time. This requires approximately 70% coverage for annual but only 60% coverage for semi-annual vaccination campaigns. Community-level vaccination trials are needed to test these predictions.
Hypoxia Does Not Activate ATP‐Sensitive K+ Channels in Arteriolar Muscle Cells
Authors: Jackson William F. 
Published: September 2002

ABSTRACTObjective: To test the hypothesis that hypoxia activates ATP‐sensitive K+ (KATP) channels in cremasteric arteriolar muscle cells, resulting in membrane hyperpolarization and inhibition of norepinephrine‐induced contraction. Methods: Arteriolar muscle cells were isolated enzymatically from second‐ and third‐order arterioles that were surgically removed from hamster cremaster muscles. The effects of hypoxia (PO2 = 12–15 mm Hg) were then examined on norepinephrine‐induced contraction, membrane currents, and membrane potential in these cells at room temperature. Whole‐cell currents and membrane potential were recorded using the perforated patch technique. Results: Hypoxia (12–15 mm Hg PO2) reversibly inhibited norepinephrineinduced contraction to 52 ± 6% of the response in normoxic solutions (156 mm Hg, n = 12 digests, p < 0.05). These effects of hypoxia could be prevented by superfusion of the cells with either solutions containing the KATP channel antagonist glibenclamide (1 µM) or solutions containing 35 mM K+ to reduce the electrochemical gradient for K+ diffusion. Cromakalim, an activator of KATP channels, also inhibited norepinephrine‐induced contraction to a similar extent as hypoxia, and in a glibenclamide and 35 mM K+‐sensitive manner. These results are consistent with the KATP channel hypothesis. In contrast, hypoxia had no effect on estimated whole‐cell membrane conductance between −40 and −90 mV in voltage‐clamp experiments; on holding current measured at −60 mV in cells superfused with 143 mM K+ under voltage‐clamp conditions; or on membrane potential in current‐clamp experiments, despite positive effects of cromakalim in all three protocols. These electrophysiological data lead to rejection of the hypothesis that hypoxia activates KATP channels. Conclusions: Hypoxia inhibits norepinephrine‐induced contraction of cremasteric arteriolar muscle cells by a mechanism that does not involve KATP channels. It is speculated that the inhibitory effects of glibenclamide and 35 mM K+ on the effects of hypoxia on contraction resulted from depolarization induced by these treatments rather than specific inhibition of KATP channels.
The development and validation of a Greek version of the short‐form McGill Pain Questionnaire
Authors: Georgoudis George , Watson Paul J. , Oldham Jacqueline A. 
Published: September 2002

Background: The short form of the McGill Pain Questionnaire (SFMPQ) is a widely used instrument for assessing the quality of pain where use of the full form is not possible. To date however, this instrument has not been translated into the Greek language.Aims: It is the aim of this study to validate an adopted Greek version of the short form of the McGill Pain Questionnaire.Methods: A systematic translation procedure was followed before development of the final version. Sixty spinal and osteoarthritis chronic musculoskeletal pain patients completed the questionnaire. A large percentage of the subjects (43%) was of elementary educational level.Results: The analysis of the results indicated that an internally consistent (Cronbach’s α =0.71) and content valid (all 15 descriptors were used at least by the 33% of the subjects) instrument has been developed. It has been shown to be suitable, easy to understand and administer for this sample of chronic musculoskeletal patients.Conclusions: A Greek version of the SFMPQ (the GR‐SFMPQ) has been constructed which has the properties of internal validity and consistency. It is easy to administer, easy to understand even for an elementary educational level and it is capable of describing multidimensionally the pain experience of chronic musculoskeletal pain patients.
Computer‐controlled pneumatic pressure algometry—a new technique for quantitative sensory testing
Authors: Polianskis Romanas , Graven‐Nielsen Thomas , Arendt‐Nielsen Lars 
Published: September 2002

Hand‐held pressure algometry usually assesses pressure‐pain detection thresholds and provides little information on pressure–pain stimulus–response function. In this article, a cuff pressure algometry for advanced pressure‐pain function evaluation is proposed.The experimental set‐up consisted of a pneumatic tourniquet cuff, a computer‐controlled air compressor and an electronic visual analogue scale (VAS) for constant pain intensity rating. Twelve healthy volunteers were included in the study. In the first part, hand‐held algometry and cuff algometry were performed over the gastrocnemius muscle with constant compression rate. In the second part, the cuff algometry was performed with different compression rates to evaluate the influence of the compression rate on pain thresholds and other psychophysical data. Pressure‐pain detection threshold (PDT), pain tolerance threshold (PTT), pain intensity, PDT–PTT time and other psychophysical variables were evaluated.Pressure‐pain detection thresholds recorded over the gastrocnemius muscle with a hand‐held and with a cuff algometer, were 482 ± 19 kPa and 26 ± 1.6 kPa, respectively. Pressure and pain intensities were correlated during cuff algometry. During increasing cuff compression, the subjective pain tolerance limit on VAS was 5.6 ± 0.95 cm. There was a direct correlation between the number of compressions, the compression rate and pain thresholds.The cuff algometry technique is appropriate for pressure‐pain stimulus–response studies. Cuff algometry allowed quantification of psychophysical response to the change of stimulus configuration.
The management of chronic pain in Switzerland: A comparative survey of Swiss medical specialists treating chronic pain
Authors: Wilder‐Smith Oliver H.G. , Möhrle Jörg J. , Dolin Paul J. , Martin Nadine C. 
Published: September 2002

Chronic pain management by Swiss specialist physicians with the primary hypothesis that pain clinic practitioners conform better to good practice (interdisciplinarity, diagnostic/therapeutic routines, quality control, education) than other specialists treating chronic pain was surveyed.Management of all types of chronic pain by pain clinic practitioners and rheumatologists, oncologists or neurologists was compared via a mailed questionnaire survey (n=125/group).Two hundred and twenty‐nine (46%) of 500 mailed questionnaires were returned with similar group return rates. Eighty‐six percent of responders find chronic pain therapy very difficult/difficult; they estimate only 45% of these patients achieve good outcomes. Twenty‐three per cent of responders belong to an interdisciplinary pain centre, but 72% of chronic pain patients are treated by responders alone. Fifty‐nine percent never/only occasionally use therapeutic algorithms, 38% use formal pain diagnostic procedures, 20% have a pain quality control programme. Fifty‐one percent lack past pain education, 37% do not attend continuing pain education, 69% agree that pain education is their greatest need. Pain clinic practitioners are more interdisciplinary and use more pain diagnostics than other specialists. They are matched by oncologists in education and success in therapeutic escalation, and bettered by them in algorithm use.Pain clinic practitioners and oncologists bring particular—differing—skills to chronic pain management compared to rheumatologists and neurologists. Chronic pain management diversity may result from differences in malignant and benign pain, and its generally being provided by the speciality treating the underlying cause. This survey identifies targets for improvement in areas fundamental to good chronic pain practice: interdisciplinarity, diagnostic/therapeutic tools, quality management and education.
A comparison of the SF‐36 and Nottingham Health Profile in patients with chronic neuropathic pain
Authors: Meyer‐Rosberg Karin , Burckhardt Carol S , Huizar Karin , Kvarnström Ann , Nordfors Lars‐Olof , Kristofferson Ann 
Published: September 2002

The aim of this study was to evaluate and compare the psychometric properties of two generic health‐related quality of life (HRQoL) instruments, the Short Form Health Survey (SF‐36) and the Nottingham Health Profile (NHP) in a group of patients with chronic peripheral neuropathic pain (PNP). The sample consisted of 126 adults (56 men and 70 women) with PNP following a lesion of a peripheral nerve, spinal nerve or nerve root or patients with post‐herpetic neuralgia. The battery of tests included visual analogue scales (VASs) for pain assessment and global rating of health and verbal rating scales of pain and other symptoms, as well as patient descriptors.The SF‐36 had higher internal consistency reliability coefficients (α=0.79, range 0.70–0.90) than the NHP (α=0.68, range 0.49–0.79). Correlations between comparable dimensions of the two instruments were significant (range from −0.79 for the physical and mental dimensions to −0.29 for the social dimension) indicating a moderate degree of convergent validity. The study population had significantly worse scores on all dimensions of the two instruments when compared with the general population. Subjects with high VAS scores for pain on movement and those with low global health ratings had poorer scores on the both instruments. Overall, the SF‐36 performed somewhat better on psychometric testing than did the NHP. However, the NHP contains dimensions such as sleep and more pain items which might be of particular importance in the PNP population. Since the instruments are short, both could be retained for continued testing in outcome studies of this population.
Usefulness of the evidence‐based medicine‐supported cancer pain management guideline
Authors: Hiraga Kazuaki , Nozaki‐Taguchi Natsuko 
Published: September 2002

The Japanese guidelines for the clinical practice of cancer pain management supported by evidence‐based medicine were established by the Japanese Society for Palliative Medicine in 1999 [as their Evidence‐based Medicine‐supported Cancer Pain Management Guideline. To evaluate usefulness of the Guideline for the management of cancer pain, the same questionnaires were addressed to nurses and physicians of enrolled institutions twice. The first survey was conducted before the distribution of the Guideline in July, 1999 and the second was done after the distribution in January, 2000. Usefulness of the Guideline was examined by comparing the results of two surveys. Cancer patients were divided into two groups depending on their stages (conservative or terminal).Morbidity of pain in cancer patients at each stage having some analgesics did not change at each survey period. (2) At the first survey the rate of pain relief in each stage of cancer patients was essentially unchanged from a previous result obtained in 1998. The rate of pain relief shown in the second survey tended to be higher than that shown in the first in both groups of patients. The rate of pain relief with per os morphine was shown to be significantly higher in the second survey than in the first for each group of patients at conservative or terminal stage. The rate of pain relief of patients staying in the ward where the guidance for dosing of morphine had been carried out was 37.5% at the first survey versus 47.9% at the second. The answers from physicians to questions about treatment of cancer pain remained unchanged between the first and the second survey.The usefulness of the Guideline for cancer pain management is partly confirmed by these results. The significance of the Guideline will be totally discussed by comparing its effects on nurses, pharmacists and physicians.
Neuropathic pain: evidence matters
Authors: McQuay Henry J. 
Published: September 2002

‘He slept less and less; they gave him opium and began to inject morphine. But this did not relieve him. The dull pain he experienced in the half asleep condition at first only relieved him as a change, but then it became as bad, or even more agonizing, than the open pain.’Tolstoy The Death of Ivan IlyitchIt comes as a surprise to many pharmacologists that not all pains are relieved by opioids. Those who work in chronic pain are unfortunately only too aware of the problems that such pains can cause. One of the hallmarks of neuropathic pain is poor or incomplete relief with opioids. As with so many things in medicine, there is nothing novel in this realization, as the Tolstoy quotation shows. © 2002 European Federation of Chapters of the International Association for the Study of Pain
Are childhood adversities relevant in patients with chronic low back pain?
Authors: Nickel R. , Egle U. T. , Hardt J. 
Published: September 2002

Previous studies have found a high number of childhood adversities in patients with chronic low back pain, particularly in patients reporting persisting problems after back surgery. Our aim was to reproduce these results.Within the framework of a comprehensive diagnostic assessment and psychometric evaluation, 109 inpatients who had been treated for low back pain were examined in the orthopedics department of a German university hospital. Five risk factors investigated by Schofferman and his staff (Schofferman et al., 1993) were re‐assessed in all of our patients using a structured biographical interview. The German chronic low back pain group was also compared with an age‐and gender‐matched control group of 109 non‐chronic pain patients with respect to these childhood adversities and additional ones.Only approximately 11% of the German chronic low back pain sample demonstrated three or more risk factors, compared with more than 50% in Schofferman's sample, and 47.7% showed none of the five risk factors, compared to only 11% in the Schofferman sample. Moreover, no significant differences in distribution either in terms of the individual risk factors or their cumulative frequency were found in the German chronic low back pain group compared with an age and gender‐matched control group without chronic pain.Childhood adversities do not occur frequently in a non‐selected group of patients with chronic low back pain. Earlier results showing an increased likelihood of the occurrence of psychosocial risk factors could not be confirmed. As a consequence, further psychic or psychosomatic diagnostics of patients with chronic low back pain are needed to define diagnostic subgroups. © 2002 European Federation of Chapters of the International Association for the Study of Pain. Published by Elsevier Science Ltd. All rights reserved.
Comparison of QT dispersion during atrial fibrillation and sinus rhythm in the same patients, at normal and prolonged ventricular repolarization
Authors: Houltz B. , Darpö B. , Swedberg K. , Blomström P. , Crijns H.J.G.M. , Jensen S.M. , Svernhage E. , Edvardsson N. 
Published: September 2002

Abstract

Aims
Drug-induced increase in QT dispersion has been associated with increased risk of ventricular proarrhythmia. The aim of the present study was to compare QT dispersion during atrial fibrillation and sinus rhythm in the same patients at normal and prolonged ventricular repolarization.

Methods and Results
Sixty-one patients who had had chronic atrial fibrillation for 8±14 months received a 6 h infusion of the Ikr-blocker almokalant, the first 90 min of which are used for this analysis. The following day, after conversion to sinus rhythm, by almokalant (n=19) or direct current cardioversion (n=42), an identical 90 min infusion was administered. Prior to infusion, there was no difference in precordial QT dispersion between atrial fibrillation and sinus rhythm (29±12 vs 36±17 ms, P=ns). During infusion, at prolonged repolarization, the increase in QT dispersion was greater during sinus rhythm than during atrial fibrillation (58±49 vs 30±15 ms,P =0·0011, after 30 min infusion). No correlation was found between QT dispersion and the QT or RR interval.

Conclusion
QT dispersion during atrial fibrillation does not differ from QT dispersion during sinus rhythm during normal repolarization, while measurement of QT dispersion during prolonged repolarization, induced by an Ikr-blocker, yielded larger values during sinus rhythm than during atrial fibrillation.