bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of inelastic mean free paths for polymers and other organic materials: use of quantitative structure–property relationships
Authors: Cumpson Peter J. 
Published: August 2002

AbstractInelastic mean free path values are needed for quantitative XPS analysis of a range of important polymers and other organic materials. Measured reference data are limited, although some semi‐empirical equations to estimate IMFP are available. Existing estimation methods often require values for such quantities as the bandgap (in electron‐volts) or the density, for which accurate measurements may not be available.Here we develop a scheme for estimation of the IMFP that can be applied across a range of organic structures for kinetic energies of ∼200–2000 eV. This involves a quantitative structure–property relationship (QSPR), which allows the IMFP to be estimated for any organic material from its structural formula alone, either via a straightforward calculation on paper or instantly using one of a number of commercial molecular‐modelling software packages. The accuracy of this IMFP estimate is better than existing methods, such as the TPP‐2M equation for organic materials. In the majority of analytical problems involving surface analysis in chemistry or biochemistry, the structural formula of the organic material is known or can be conjectured with reasonable confidence, so that the approach described here is more widely applicable in practise and likely to be more accurate than previous methods for estimating the IMFP in organic materials. © Crown Copyright 2001 Reproduced by permission of the Controller of HMSO.
Comparison of smoothing techniques for CD4 data in a Markov model with states defined by CD4: an example on the estimation of the HIV incubation time distribution
Authors: Sypsa V. , Touloumi G. , Kenward M. , Karafoulidou A. , Hatzakis A. 
Published: August 2002

AbstractMulti‐state models defined in terms of CD4 counts are useful for modelling HIV disease progression. A Markov model with six progressive CD4‐based states and an absorbing state (AIDS) was used to estimate the cumulative probability of progressing to AIDS in 158 HIV‐1 infected haemophiliacs with known seroconversion (SC) dates. A problem arising in such analysis is how to define CD4‐based states, since this marker is subject to measurement error and short timescale variability. Four approaches were used: no smoothing, ad hoc smoothing (to move to a later/previous state two consecutive measurements to later/previous states are needed), kernel smoothing and random effects (RE) models. The estimates were compared with the Kaplan–Meier estimate based solely on data concerning time to AIDS. There was an apparent lack of agreement between the Kaplan–Meier and the ‘no smoothing’ estimate. With the exception of the ‘no smoothing’ method, ‘ad hoc’, kernel and RE estimates fell within the range of the 95 per cent CIs of the Kaplan–Meier curve. Simulations demonstrated that the use of raw CD4 counts provides overestimated transition intensities. Compared to the kernel method, ad hoc is easier to implement and overcomes the problem of the choice of bandwidth. The RE approach leads to simple models, since it usually results in very few transitions to previous states, and can handle individuals with sparse data by smoothing their predictions towards the population mean. Ad hoc was the method that performed better, in terms of bias, than the other smoothing approaches. Copyright © 2001 John Wiley & Sons, Ltd.
Experimental evaluation of hypertext access structures
Authors: Koskinen Jussi 
Published: August 2002

AbstractTransient hypertextual access structures (THASs) are temporary graphs formed automatically on the basis of the situation‐dependent information needs of software engineers. The approach is implemented in the HyperSoft system, which is a hypertext‐based software maintenance support tool. THASs highlight the relevant parts of the program and enable nonlinear browsing between them. The system also supports various graphical views whose elements are linked to the program text. This paper describes the effects of using these hypertextual structures in two separate experiments. The subjects of both experiments were computer science students (total $N=70$). In both experiments, the subjects performed a series of sample information accesses from a C program. HyperSoft and conventional text browsing and searching were compared. The results from the two experiments are well in line with our hypothesis of the usefulness of the approach and with each other. The results indicate better task performance while using THASs as compared to using the information seeking capabilities of a conventional compiler environment. The difference is statistically significant ($p&#60;0.001$). Copyright © 2002 John Wiley & Sons, Ltd.
Pointing towards some superior metaphysics, ontology and epistemology
Authors: Tsagdis Dimitrios 
Published: August 2002

AbstractGerard de Zeeuw's conception of scientific research as an evolving organized activity that aims to improve upon observation is employed in this paper in an attempt to help contemporary users and producers of scientific research and its outcomes in ‘stepping out’ of some major generic metaphysical, ontological and epistemological difficulties and see for themselves (e.g. better) how (a migration to) the metaphysics, ontology and epistemology proposed in this paper can be of help in resolving such difficulties. Copyright © 2002 John Wiley & Sons, Ltd.
Demonstration of competition between endogenous dopamine and [11C]raclopride binding in in vitro brain slices using a dynamic autoradiography technique
Authors: Sasaki Toru , Ishiwata Kiichi , Murata Tetsuhito , Senda Michio 
Published: August 2002

AbstractTo elucidate the mechanism of in vivo binding competition between radioligand and endogenously released transmitter, we examined the influence of depolarization‐induced dopamine (DA) release on [11C]raclopride‐specific binding to D2 receptors in slices of living brain tissues using dynamic positron autoradiography. Rat brain slices were incubated in a chamber with [11C]raclopride in oxygenated medium at 34°C for 150 min. Two‐dimensional images of radioactivity in the slices were recorded on a storage phosphor screen and dynamic changes were measured. When the brain slices were exposed to the depolarization agents (25 mM K+, 50 mM K+, and 20 μM veratridine), the percentage inhibition of striatal [11C]raclopride‐specific binding was 22 ± 4%, 44 ± 8% and 54 ± 7% of the control, respectively. The percentage inhibition of [11C]raclopride‐specific binding during each depolarization treatment agreed proportionally with the amount of DA released into the medium. However, preexposure of brain slices to the same depolarization treatment (50 mM K+) did not affect the [11C]raclopride‐specific binding, suggesting that the reduction in receptor density and/or affinity was not involved in the decrease of [11C]raclopride‐specific binding. [11C]Raclopride‐specific binding decreased dose‐dependently in the presence of exogenously added DA (range 0.005–3mM). The synaptic DA concentration during each depolarization treatment estimated using three different methods.These results suggest that the decrease of [11C]raclopride‐specific binding to striatal slices following evoked DA release is due to competition between endogenous DA and raclopride. It is unlikely that changes in D2 receptor density or in affinity of the receptors for raclopride are involved. These results provide supportive evidence for in vivo binding competition between radioligand and endogenous neurotransmitter. Synapse 44:42–50, 2002. © 2002 Wiley‐Liss, Inc.
Standards‐based reform and its unintended consequences: Implications for science education within America's urban schools
Authors: Settlage John , Meadows Lee 
Published: August 2002

AbstractThis conceptual article examines the influence of the current standards‐based reform upon science education policies and practices within urban schools. We identify four negative yet unforeseen effects of the reform movement: undermining urban teachers' professionalism, eroding teacher–student relationships, diluting the science curriculum, and disparate instruction based on predicted individual test performance. Our awareness of these nuisances emerged from our first‐hand engagement with urban science teaching and through our collegial relationships with exemplary urban teachers. In closing, we propose mechanisms by which university‐based science educators might address these issues by assisting exemplary urban teachers to resist the reform‐induced perils and by incorporating the urban milieu as a substantive aspect of science teacher education. © 2002 John Wiley & Sons, Inc. J Res Sci Teach 39: 114‐127, 2002
Creating relevant science through urban planning and gardening
Authors: Fusco Dana 
Published: August 2002

AbstractThe purpose of this article is to describe a community‐based science project that was coproduced with urban teenagers and to elaborate on my understanding of what it means to create a practicing culture of science learning. This understanding will be positioned in relation to various educationally relevant discourses and research on urban science education, concluding with an exploration of these questions: In what ways did an urban planning and community gardening project help to create a learning environment in which science was relevant? To whom was science relevant and toward what ends? It is argued that in a practicing culture of science learning, science was relevant because (a) it was created from participants' concerns, interests, and experiences inside and outside science, (b) it was an ongoing process of researching and then enacting ideas, and (c) it was situated within the broader community. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 860–877, 2001
Phenytoin‐induced cleft palate: Evidence for embryonic cardiac bradyarrhythmia due to inhibition of delayed rectifier k+ channels resulting in hypoxia–reoxygenation damage
Authors: Azarbayjani Faranak , Danielsson Bengt R. 
Published: August 2002

AbstractBackgroundPhenytoin (PHT) teratogenicity has been related to embryonic arrhythmia due to the capacity of PHT to block IK channels pharmacologically, resulting in hypoxia–reoxygenation damage. The aim of this study was to further elucidate the proposed mechanism.MethodsPregnant CD‐1 mice were given PHT (85 mg/kg) or saline intraperitoneally on gestational days 10–11. Embryonic heart rhythm and presence of hemorrhage in orofacial region was recorded on day 12, fetuses were examined for malformations on day 18. Embryonic heart rate was also recorded on individual days after dosing days 9–16. In addition, PHT was given at doses of 10, 25, or 85 mg/kg on day 12 for analysis of plasma concentrations.ResultsPTH‐induced bradycardia and arrhythmia in ∼20% of the embryos, 48% showed hemorrhage in the orofacial region; 39% of the fetuses had cleft palate. The region in which hemorrhages were visible in the embryo corresponded with the region where tissue deficiency (cleft palate) was visible in the fetus at term. None of the controls showed hemorrhages, dysrhythmia, or cleft palate. PHT affected embryonic heart rates on days 9–13, but not on days 14–16. Single dose administration on day 12, the most sensitive day, resulted in a dose‐dependent decrease in embryonic heart rate (12–34%). Embryonic arrhythmia occurred at 25 and 85, but not at 10 mg/kg or in the controls. Mean maternal free plasma concentrations were 6 and 14 μmol/L in the10‐ and 25‐mg/kg groups, respectively.ConclusionsPHT‐induced cleft palate was preceded by embryonic dysrhythmia and hemorrhage in the orofacial region. Embryonic heart rhythm was phase specifically affected, as described for selective IKr channel blockers, at clinically relevant concentrations. The results support the idea that PHT teratogenicity is a consequence of pharmacologically induced dysrhythmia and hypoxia‐related damage. Teratology 63:152–160, 2001. © 2001 Wiley‐Liss, Inc.
Effects of a pre‐incubation period on the photoinduced toxicity of polycyclic aromatic hydrocarbons to the luminescent bacterium Vibrio fischeri
Authors: El‐Alawi Yousef S. , Dixon D. George , Greenberg Bruce M. 
Published: August 2002

AbstractIrradiation of polycyclic aromatic hydrocarbons (PAHs) in aqueous solution with simulated solar radiation (SSR; a light source with a visible light : UV‐A : UV‐B ratio similar to that of sunlight) can greatly enhance their toxicity. Two microbial toxicity tests with Vibrio fischeri were used to investigate the effect of composition of the growth medium and pre‐incubation on the photoinduced toxicity of PAHs. The assays were a short‐term test (15 min) and long‐term test (18 h). Both assays were carried out in SSR and darkness to examine for photoinduced toxicity of PAHs. For the short‐term toxicity assay, inhibition of bacterial luminescence was measured. For the long‐term toxicity assay, both inhibition of bacterial luminescence and inhibition of growth were recorded. To broaden this test, V. fischeri cells were pre‐incubated with PAHs in medium without a carbon source (minimal medium) for 8 h to facilitate assimilation and photooxidation of the contaminants, and to prevent bacterial growth at the outset of the assay. V. fischeri was more sensitive in minimal medium than in complex medium in both the short‐ and long‐term toxicity assays. Moreover, in the long‐term assay, SSR greatly increased toxicity, especially if there was a pre‐incubation period in minimal medium. This indicates that both assimilation and photooxidation of PAHs are important to their toxicity to V. fischeri. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 277–286, 2001
An overview of x‐ray spectrometry at research centers in Chile
Authors: Romo‐Kröger C. M. , Cornejo‐Ponce L. , Morales J. R. , Dinator M. I. , Avila M. J. , Poblete V. H. , Galvez J. , Goldschmidt A. , Trier A. , Valdes J. , Rojas C. M. , Cantillano M. E. , Vera R. , Figueroa R. , Garcia M. 
Published: August 2002

AbstractDifferent procedures have been used to develop x‐ray fluorescence spectroscopy in Chile. In this paper we describe those groups doing basic or applied scientific research, mainly associated with units at universities and research centers. The techniques are PIXE, common XRF, XRF excited with gamma sources, x‐ray emission from an electron microprobe and the total reflection technique. Historical aspects and experimental features are mentioned. Theoretical and methodological projects are also described. Finally, the wide field of applications of XRF in Chile is presented. Copyright © 2002 John Wiley & Sons, Ltd.
Tissue‐engineered Artificial Urothelium
Authors: Kawai Koji , Hattori Kazunori , Akaza Hideyuki 
Published: August 2002

AbstractBladder wall replacement is one of the most challenging problems of urologic surgery. Various materials have been tried in experimental models, but most were not free of complications, such as leakage, infection, and stone formation. In addition, much time was needed for tissue regeneration after grafting. Bladder replacement with tissue‐engineered materials, which basically consist of autologous cells seeded on a supporting structure, represents an area of rapidly expanding interest. Recently, several investigators have reported important, successful results from in vitro systems and animal models. Here we review those experimental approaches to tissue‐engineered artificial urothelium.
Molecular and Reconstructive Urology: A Coming Together
Authors: Gardiner Robert A. 
Published: August 2002

AbstractAppreciation of the clinical utility of the protein product of kallikrein gene 3, prostate‐specific antigen (PSA), has resulted in earlier diagnosis of prostate cancer and an associated increase in the number of radical prostatectomies performed. A consequence of this change in surgical practice has been an improved understanding of sphincter anatomy and methods for sphincter preservation, which in turn have led to enhanced popularity for orthotopic urinary diversion for invasive bladder cancer. In this paper, molecular and basic science research being undertaken in an to attempt to overcome problems and limitations of the PSA/transrectal ultrasonographic biopsy approach to diagnosis are discussed. Also detailed are (1) the development of a bladder acellular matrix graft to serve as an "off the shelf" scaffold on which urothelium regenerates, (2) attempts to create a simpler, more durable bowel continence mechanism, and (3) a novel experimental technique for renal preservation based on considering the urine‐producing and urine‐directing roles of the upper tract as surgically separable entities. These research endeavors serve to illustrate how developments at the molecular and basic science levels promise to lead to further reconstructive surgical approaches when translating new developments into patient benefits during the year 2000 and beyond.
Urology in the Twenty‐first Century: Noninvasive Targeted Treatments for Urologic Malignancies
Authors: Droller Michael J. 
Published: August 2002

AbstractNotwithstanding the major advances that have been made in the treatment of bladder cancer, prostate cancer, and kidney cancer, much remains to be done if we are to translate the gains that have been made in "disease‐free survival" into actual survival in terms of quantity as well as quality of life. Indeed, we are still at an embryonic stage in understanding how cancers originate, whether defense mechanisms exist that can recognize these cancers and recognize them when they first develop, when cancers metastasize during their development, whether we have methods that are sufficiently accurate to distinguish between organ‐confined and regional extension or spread of disease, and the means by which we can identify cancers that are likely to remain organ‐confined and distinguish them from those that are predestined to metastasize. If we are to be successful in the assessment and treatment of various urologic cancers, these questions must be answered. Many new methods of assessment and treatment are being explored that in themselves may provide some answers. The present discussion focuses on these issues, on how they may lead to further understanding of the unique biology of many of these tumors, and what we may expect in terms of increased longevity and improved quality of life as we attempt to cure patients of their disease.
Future of European Urology
Authors: Debruyne Frans M.J. 
Published: August 2002

AbstractTo provide the highest medical service and to maintain the most advanced research work across national boundaries, we have developed many organizations, including the European Association of Urology (EAU), the European Board of Urology (EBU), and the European Organization for Research and Treatment of Cancer (EORTC). They also have functioned to provide equal health service for all European people. In the future, superspecialization and the multidisciplinary approach are inevitable. Major changes will occur, such as prevention of stone diseases, reconstructive urology, and immune and gene therapy in oncology. Specialists will assume major roles in the urologic clinic. In those circumstances, Europe will continue to play an important role because urologists are very much involved in future strategic developments on national and Pan‐European levels.
Surgical Strategy for Large or Malignant Endocrine Pancreatic Tumors
Authors: Hellman Per , Andersson Maria , Rastad Jonas , Juhlin Claes , Karacagil Sadettin , Eriksson Barbro , Skogseid Britt , Åkerström Göran 
Published: August 2002

AbstractEndocrine pancreatic tumors (EPTs) are rare but have a remarkably better prognosis than adenocarcinoma of the pancreas. Patients with EPTs benefit from surgical and medical therapy, which may alleviate symptoms due to hormonal excess and increase survival. Patients with large or malignant EPTs with infiltrative disease may suffer from local complications, including gastrointestinal bleeding and obstruction and involvement of the superior mesenteric (SMV) and portal (PV) veins. Among 31 patients with operable and large or malignant EPTs, 7 had hormone‐producing syndromes (insulin, glucagon), and 24 had clinically nonfunctioning EPTs. Surgery in these patients included vascular reconstruction of the SMV/PV (n= 4), resection of infiltrated adjacent organs (n= 5; stomach, transverse colon), or resection of concomitant liver metastases (n= 3). Four patients with conspicuously large insulinomas, and three with glucagonoma were successfully operated on with alleviation of hormonal symptoms. Among the 24 nonfunctioning EPTs, 5 patients had been explored earlier and their tumors judged inoperable due to locally invasive disease or misdiagnosis as pancreatic adenocarcinoma. The operations were performed with no mortality and low morbidity. We conclude that large and malignant EPTs with limited spread of disease may benefit from a combination of medical and surgical therapy.
Intramural Metastases from Thoracic Esophageal Cancer: Local Indicators of Advanced Disease
Authors: Nishimaki Tadashi , Suzuki Tsutomu , Tanaka Yoichi , Aizawa Kikuo , Hatakeyama Katsuyoshi , Muto Terukazu 
Published: August 2002

AbstractThe patterns of tumor spread and long‐term survival of patients with (n= 54) and without (n= 270) intramural metastasis from esophageal cancer were investigated after either extended radical (n= 155) or less radical (n= 169) esophagectomy. The purpose was to evaluate whether extended radical esophagectomy has an impact on the long‐term survival of patients with intramural metastases from the disease. The patients with intramural metastasis had significantly larger primary tumors (p< 0.01) and more frequent T4 tumors (p< 0.001), stage IV disease (p< 0.05), lymphatic invasion (p< 0.05), and lymph node metastasis (p< 0.01) than did those without intramural metastasis. The survival rates of patients with intramural metastases were significantly worse than those of patients without intramural metastases after resection (p< 0.001). No patient with intramural metastases survived more than 4 years after either extended or less radical esophagectomy, and there was no significant difference between the two survival curves. Therefore intramural metastases should be considered local indicators of advanced esophageal cancer, and radical esophagectomy may not be indicated for patients with intramural metastasis from the disease.
Helical Computed Tomography for Abdominal Imaging
Authors: Krasny Robert M. , Lu David S.K. 
Published: August 2002

AbstractSignificant technologic advances have taken place in computed tomography (CT). Current‐generation conventional CT scanners are able to image a slice of tissue in as little as 2 to 3 seconds and can acquire several consecutive images. Although it is a substantial improvement from the CT of 5 years ago, there remain practical limits to the utility of conventional CT imaging within the abdomen. Recently, a new type of CT gantry design (“slip‐ring”) and faster computers have contributed to the development of a new generation of CT scanners, the “helical” or “spiral” CT scanners.