bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermokarst ponds as indicators of the former distribution of palsas in Finnish Lapland
Authors: Luoto Miska , Seppälä Matti 
Published: March 2003

AbstractThermokarst ponds resulting from thawing of palsas were mapped in a 95 km‐long transect area in northern Finland. The spatial distribution of thermokarst was related to palsa distribution and to geographical variables using GIS techniques and multivariate spatial modelling. In our 3370 km2 study area, the former distribution of palsas was about three times larger than the present one. This indicates that the formation and thawing of permafrost are not in balance; palsas are collapsing and melting more often than palsas are forming. Copyright © 2003 John Wiley & Sons, Ltd.
Learning to teach science in contemporary and equitable ways: The successes and struggles of first‐year science teachers
Authors: Bianchini Julie A. , Johnston Carol C. , Oram Susannah Y. , Cavazos Lynnette M. 
Published: March 2003

AbstractRecent studies of beginning science teachers make clear that learning to integrate contemporary nature of science descriptions and equitable instructional strategies into educational practices is a complex and challenging endeavor. In this research project, we examined the views and practices of three first‐year science teachers, recent graduates of a teacher education program in California known for its attention to gender equitable and multicultural content and instruction. We explored these beginning teachers' attempts to present contemporary descriptions of the nature of science and implement equitable instructional strategies in their classrooms; we videotaped two of their curricular units and conducted individual interviews after each unit lesson. From qualitative analysis of these interviews, we developed case studies that described the ideas and practices these beginning teachers took up from their preservice experiences, as well as the reasons provided and constraints identified for science topics taught and instructional approaches used. In our discussion, we examined commonalties across beginning teachers' successes and struggles in learning to teach science in contemporary and equitable ways, as well as lessons we learned about ways to improve preservice science teacher education. © 2003 Wiley Periodicals, Inc.Sci Ed87:419–443, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10058
Challenges of standards‐based reform: The example of California's science content standards and textbook adoption process
Authors: Bianchini Julie A. , Kelly Gregory J. 
Published: March 2003

AbstractIn this paper, we debate the strengths and limitations of standards‐based science education reform in the United States. Our purpose is to raise questions and encourage conversations about the mis/uses of standards to shape science curriculum and instructional practices at both state and national levels. We begin by examining the case of California: California recently developed science content standards and used these standards to guide the development, assessment, and adoption of K‐8 science instructional materials, a process in which we participated. We offer substantive critique of the California standards themselves and the ways such standards narrowly frame science education for the state's teachers and students. We then move to more general challenges posed by fashioning standards as instruments of reform: the proliferation of increasingly unwieldy instructional materials and the muting of teachers' voices in local decision‐making processes. While we do not call for the elimination of standards, we argue for greater awareness of the challenges in using standards to achieve science education reform and for renewed effort to include teachers in the translation of standards into local, responsive practice. © 2003 Wiley Periodicals, Inc. Sci Ed 87:378–389, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10064
Measurements of L subshell and L shell x‐ray fluorescence cross‐sections for U and Th
Authors: Gürol A. , Polat R. , Karabulut A. , Budak G. 
Published: March 2003

AbstractThe Ll, Lα1, 2, Lη, Lβ6, Lβ2, 4, 15, 17, Lβ1, 3, 5, Lβ9, 10, Lγ1, Lγ2, 3, 6, 8, Lγ4,4′ and Lγ5 x‐ray fluorescence cross‐sections for U and Th were measured at 59.5 keV incident photon energy by using theoretical Li subshell photoelectric cross‐sections, fluorescence and Coster–Kronig yields and fractional emission rates, and calculated theoretically by using atomic parameters. The measured values were compared with the theoretical values and experimental results available in the literature. Copyright © 2003 John Wiley & Sons, Ltd.
Improvement of peak‐to‐background ratio in PIXE and XRF methods using thin Si‐PIN detectors
Authors: Karydas A. G. , Zarkadas Ch. , Kyriakis A. , Pantazis J. , Huber A. , Redus R. , Potiriadis C. , Paradellis T. 
Published: March 2003

AbstractThis paper describes the peak‐to‐background ratio improvement that can be achieved in PIXE and XRF applications by the use of thin crystal detectors. This improvement becomes apparent in the presence of an intense γ‐ray source, which can be produced either during proton irradiation of a sample (PIXE) or in the deexcitation of the radionuclide in radioisotope‐induced XRF analysis (RIXRF). In order to study theoretically the energy response of a silicon crystal in the x‐ray energy region with respect to its thickness and the energy of the incident γ‐radiation, a Monte Carlo simulation was performed. Experimentally, two detectors having crystal thicknesses of 300 µm and 3 mm were employed in specific analytical applications of PIXE, PIXE‐induced XRF and RIXRF techniques. The peak‐to‐background ratios obtained for various characteristic x‐rays were compared between the two detectors. The performances of the two detectors were also compared in the monochromatic XRF analysis of samples with low average atomic number matrix content. Copyright © 2003 John Wiley & Sons, Ltd.
A risk assessment study of heavy metals in ambient air by WD‐XRF spectrometry using aerosol‐generated filter standards
Authors: Vanhoof C. , Chen H. , Berghmans P. , Corthouts V. , De Brucker N. , Tirez K. 
Published: March 2003

AbstractA risk assessment study of the air quality in the surrounding of roads covered with slags coming from the non‐ferrous metal industry was performed. A monitoring campaign was carried out at three locations in Flanders by collecting the PM10 fraction and the total suspended particulates (TSP) of the airborne dust particles, entrapping heavy metals, on membrane filters. The heavy metal concentration on the dust filters was determined by wavelength‐dispersive x‐ray fluorescence (WD‐XRF) spectrometry. The XRF calibration curves were set up with filter standards prepared in the laboratory using an aerosol‐generated loading system. The acquired WD‐XRF results were confirmed by inductively coupled plasma atomic emission spectrometric (ICP‐AES) measurements after acid digestion on a selected number of filters. Electron probe microanalysis (EPMA) confirmed that aerosol‐loaded filter standards and dust filters with a concentration level of the analyzed element below 3300 ng cm−2 were homogeneously distributed. Dust filters with higher concentrations, and especially filters loaded with the TSP fraction, reflected an inhomogeneous distribution of the analyzed element on the filter. The WD‐XRF analytical results acquired in the monitoring campaign revealed that the concentration of Pb on the dust filters never exceeded the immission standard (yearly average) of 2000 ng m−3. It can be stated that the impact on human health is limited and can still be reduced by covering the polluted roads with a layer of asphalt. Further evaluation of soil and water samples from the nearby surroundings reveals that the heavy metal content in the slags makes an important contribution to environmental pollution, especially the contamination of groundwater. Copyright © 2003 John Wiley & Sons, Ltd.
Description of Compton peaks in energy‐dispersive x‐ray fluorescence spectra
Authors: Van Gysel M. , Lemberge P. , Van Espen P. 
Published: March 2003

AbstractA new model for the description of incoherent peaks observed in energy‐dispersive x‐ray fluorescence spectra is proposed. The model was derived after a systematic study of peak shapes based on Monte Carlo simulations. The model consists of a Gaussian modified by two exponential tail functions. The model is implemented in a non‐linear least‐squares fitting procedure and tested on spectra measured with a 109Cd excitation XRF setup using an HPGe detector. Copyright © 2003 John Wiley & Sons, Ltd.
Thin‐film characterization with x‐ray microanalysis. Extending and improving invariant embedding results
Authors: Heluani Silvia P. , Hoffmann C. 
Published: March 2003

AbstractInvariant embedding theoretical results for the recorded x‐ray intensities in electron probe microanalysis were used to develop a procedure for thin films. The method presented here gives the possibility of achieving thin‐film characterization directly from characteristic x‐rays intensities measurements, without the necessity to make an explicit calculation of the ϕ(ρz) function. Theoretical results are found to follow the general trend of experimental data. Copyright © 2003 John Wiley & Sons, Ltd.
Measurements of Coster–Kronig enhancement factors of some elements in the atomic number range 66 ≤ Z ≤ 72
Authors: Öz E. , Ekinci N. , Ertuǧrul M. , Şahin Y. 
Published: March 2003

AbstractThe Lι, Lα, Lβ and Lγ x‐ray production cross‐sections in four elements with Z ranging from 66 to 72 at seven different energies in the interval 8.265–11.730 keV were measured. Experimental measurements were carried out on a few elemental samples to examine the effect of Coster–Kronig transitions on fluorescence cross‐sections for the L x‐ray line using an Si(Li) detector system with an energy resolution of 160 eV at 5.96 keV x‐ray energy. Absolute values of L x‐ray cross‐sections were calculated with incorporation of the enhancement due to the Coster–Kronig effect for these elements. The measured enhancement factors are smaller than predicted by theory. Copyright © 2003 John Wiley & Sons, Ltd.
Silent disaster: A European perspective on threat perception from Chernobyl far field fallout
Authors: Tønnessen Arnfinn , Mårdberg Bertil , Weisæth Lars 
Published: March 2003

AbstractSurveys investigated the perceived threat of radioactive fallout and public coping following a “silent disaster” (Chernobyl) across Europe. Survey data from national representative samples in 12 European countries are compiled, 6 months and 2 years after the accident, across 12 countries. Exposure to information about the accident, and perception of the consequences of Chernobyl as a health threat, were significantly related to the level of fallout in each country. Another significant relationship was found between the level of fallout in these 12 countries and the proportion of respondents who reported having taken countermeasures. Information challenges for the authorities are highlighted.
Short‐term dietary interventions in children and adolescents with treated phenylketonuria: Effects on neuropsychological outcome of a well‐controlled population
Authors: Huijbregts S. C. J. , De Sonneville L. M. J. , Licht R. , Van Spronsen F. J. , Sergeant J. A. 
Published: March 2003

AbstractThis study addressed two questions: is there an effect of dietary interventions that induce relatively small changes in phenylalanine (Phe) concentration on neuropsychological outcome of early‐ and continuously treated phenylketonuria (PKU) patients, and are there differences in effects for PKU children and adolescents? To answer the first question, the effect of a short‐term dietary intervention (1–2 weeks) was compared for patients whose Phe concentrations increased vs those whose Phe concentrations decreased. Controls were tested twice to control for learning effects. To answer the second question, the effect of dietary interventions was examined in younger patients (aged 7–10 years) and older patients (aged 11–14 years). The effect of dietary interventions was determined with three neuropsychological tasks: one requiring sustained attention; a second demanding maintenance in working memory; and a third in which complex operations were performed in working memory. Relatively small fluctuations in Phe concentration were found to influence neuropsychological task performance of PKU patients. Patients whose Phe concentrations decreased at the second assessment showed generally more improvement than controls. Patients whose Phe concentrations had increased showed minimal improvement or deterioration of task performance. The strongest effects were observed when sustained attention and manipulation of working memory content were required. There were some indications of a greater sensitivity of younger patients to fluctuations in Phe concentration.
Mutations in the sterol 27‐hydoxylase gene (CYP27A) cause hepatitis of infancy as well as cerebrotendinous xanthomatosis
Authors: Clayton P. T. , Verrips A. , Sistermans E. , Mann A. , Mieli‐Vergani G. , Wevers R. 
Published: March 2003

AbstractFollow‐up investigations were undertaken on a previously reported patient who had severe familial giant cell hepatitis in infancy associated with substantially increased urinary excretion of bile alcohol glucuronides. By the age of 11 years, he had developed a profile of cholanoids in plasma and urine that closely resembled the pattern seen in cerebrotendinous xanthomatosis (CTX). Sequencing of the sterol 27‐hydroxylase gene (CYP27A) showed that he was homozygous for a deletion (525/526delG) that causes a frameshift and a premature stop codon. This genotype has previously been described in an adult female with classical symptoms of CTX (tendon xanthomata, cataracts and deteriorating cognitive function). A review of past medical histories of a group of patients with CTX revealed that prolonged neonatal cholestatic jaundice was common. The family histories also revealed fetal and neonatal deaths among siblings of patients with CTX. We conclude that defective activity of cholesterol 27‐hydroxylase can lead to neonatal cholestatic jaundice (‘hepatitis of infancy’), which may be self‐limiting. After a latent period, however, progressive accumulation of cholesterol and cholestanol can lead to the xanthomata, neurodegeneration, cataracts and atherosclerosis that are typical of CTX.
Prenatal diagnosis of succinate semialdehyde dehydrogenase deficiency in non‐identical twins
Authors: Aligianis I. A. , Farndon P. A. , Gray R. G. F. , Heath S. K. , Kilby M. , Gibson K. M. , Akaboshi S. 
Published: March 2003

AbstractPrenatal diagnosis was performed by both DNA and enzymatic analysis on non‐identical twins conceived by in vitro fertilization and at risk of succinate semialdehyde dehydrogenase deficiency. One fetus was predicted to be affected and one unaffected and selective fetal reduction was performed.
Individual blood–brain barrier phenylalanine transport in siblings with classical phenylketonuria
Authors: Weglage J. , Wiedermann D. , Denecke J. , Feldmann R. , Koch H.‐G. , Ullrich K. , Möller H. E. 
Published: March 2003

AbstractRecent studies indicate that individual blood–brain transport characteristics of phenylalanine may lead to different clinical outcomes in phenylketonuria (PKU) patients in spite of comparable dietary control. To check these preliminary data, we investigated four pairs of siblings with classical PKU (and identical genotype) using in vivo nuclear magnetic resonance spectroscopy in the course of an oral phenylalanine load (100 mg/kg body weight). Patients' brain phenylalanine concentrations were different in spite of similar blood levels. Interindividual variations of the apparent transport Michaelis constant, Kt,app, ranged from 0.10 to 0.84 mmol/L. The ratio of the maximal transport velocity, Tmax, over the intracerebral consumption rate, Vmet, varied between 2.61 and 14.0. Siblings with lower values for Kt,app, higher values for Tmax/Vmet, and higher concurrent brain phenylalanine levels showed a lower IQ and a higher degree of cerebral white matter abnormalities. The results indicate that blood–brain barrier transport characteristics and the resultant brain phenylalanine levels are causative factors for the individual clinical outcome in PKU.
Niemann–Pick disease type C in adults
Authors: Imrie J. , Vijayaraghaven S. , Whitehouse C. , Harris S. , Heptinstall L. , Church H. , Cooper A. , Besley G. T. N. , Wraith J. E. 
Published: March 2003

AbstractAlthough it is often perceived as a paediatric disorder, significant numbers of patients with Niemann–Pick disease type C present for the first time in adult life or survive into adult life. The presentation in these patients differs from that seen in the classical juvenile form of the disease. Adult patients are often referred to clinicians with psychosis or other major psychiatric problems. The dystonia with preserved intellectual functioning can be mistaken for other basal ganglia disorders such as Wilson disease. The presence of vertical gaze palsy is an important clinical clue and, in the presence of a modest increase in plasma chitotriosidase activity, can be very helpful in the differential diagnosis. The diagnosis should be confirmed in suspected cases by filipin staining of cultured fibroblasts, as well as cholesterol esterification studies and DNA mutation analysis.
A Survey of Clinical Supervision in Genetic Counseling
Authors: Lindh Heidi L. , Veach Patricia McCarthy , Cikanek Korinne , LeRoy Bonnie S. 
Published: March 2003

AbstractThree hundred and thirty‐five full members of the National Society of Genetic Counselors completed a survey concerning the nature of clinical supervision for genetic counseling students. Slightly over half (54.3%, n = 182) had provided clinical supervision within the past 5 years. Of those who supervised, 66.7% had 5 years or less supervision experience, and 55% had supervised 10 or fewer students. The majority became supervisors because they enjoy teaching and contributing to the profession. Common reasons for not supervising include no local graduate program, and had never been asked to supervise. Live supervision is the most prevalent student evaluation method: every supervisor reported providing one‐on‐one oral feedback, and 47.3% indicated that they always provide feedback immediately following a counseling session. The most frequent challenges involve students who lack technical knowledge and who fail to incorporate feedback. Training, policy, and research implications are discussed.
The Unmet Information and Support Needs of Women with a Family History of Breast Cancer: A Descriptive Survey
Authors: Thewes Belinda , Meiser Bettina , Tucker Monica , Tucker Kathy 
Published: March 2003

AbstractThis study aims to survey the unmet support needs of women at increased risk of developing breast cancer. In total, 173 unaffected women with a family history of breast cancer completed a 28‐item purposely‐designed mailed survey. The majority of participants did not report a high level of unmet need for support. Receiving further information about cancer genetics was the most commonly reported area of unmet need. Only about 20% of participants reported a moderate to high degree of interest in attending a hypothetical support group. However, a higher degree of interest was expressed in internet‐based information and supportive interventions. Amongst those interested in attending a support group, discussion, and receiving further information were the most preferred activities. Higher levels of unmet support needs were significantly associated with interest in attending groups. No demographic variables were found to predict interest in attending a support group. Implications for those considering establishing support groups are discussed.
Dynamic modeling of genetic networks using genetic algorithm
and S-system
Authors: Kikuchi Shinichi , Tominaga Daisuke , Arita Masanori , Takahashi Katsutoshi , Tomita Masaru 
Published: March 2003

Abstract
Motivation: The modeling of system dynamics of genetic networks, metabolic networks or signal transduction cascades from time-course data is formulated as a reverse-problem. Previous studies focused on the estimation of only network structures, and they were ineffective in inferring a network structure with feedback loops. We previously proposed a method to predict not only the network structure but also its dynamics using a Genetic Algorithm (GA) and an S-system formalism. However, it could predict only a small number of parameters and could rarely obtain essential structures. In this work, we propose a unified extension of the basic method. Notable improvements are as follows: (1) an additional term in its evaluation function that aims at eliminating futile parameters; (2) a crossover method called Simplex Crossover (SPX) to improve its optimization ability; and (3) a gradual optimization strategy to increase the number of predictable parameters.
Results: The proposed method is implemented as a C program called PEACE1 (Predictor by Evolutionary Algorithms and Canonical Equations 1). Its performance was compared with the basic method. The comparison showed that: (1) the convergence rate increased about 5-fold; (2) the optimization speed was raised about 1.5-fold; and (3) the number of predictable parameters was increased about 5-fold. Moreover, we successfully inferred the dynamics of a small genetic network constructed with 60 parameters for 5 network variables and feedback loops using only time-course data of gene expression.
Contact: kikuchi@sfc.keio.ac.jp
* To whom correspondence should be addressed.
Triplet repeats in human genome: distribution and their association
with genes and other genomic regions
Authors: Subramanian Subbaya , Madgula Vamsi M. , George Ranjan , Mishra Rakesh K. , Pandit Madhusudhan W. , Kumar Chanderashekar S. , Singh Lalji 
Published: March 2003

Abstract
Motivation: Simple sequence repeats (SSRs) or microsatellite repeats are found abundantly in many prokaryotic and eukaryotic genomes. Among SSRs, triplet repeats are of special significance because some of them have been linked to various genetic disorders. The objective of the study is to analyze the triplet repeats of complete human genome and to identify the genes that contain the triplet repeats in their coding region. The analysis will help us to identify the candidate genes that have potential for repeat expansion.
Results: We have analyzed triplet repeats in the complete human genome from the publicly available sequences. Our analysis revealed that AGC and CCG repeat were predominantly present in the coding regions of the genome while UTRs and the upstream sequences contained CCG repeats in relative abundance. Analysis of density of triplet repeats (bp/Mb) revealed that AAT and AAC were the abundant repeats whereas ACT and ACG were the rare repeats found in human genome. We could identify about 2135 known or predicted genes that were associated with at least one of the triplet repeat types. A large proportion of putative transcripts that were identified by gene finding programs were found to be associated with triplet repeats. These transcripts will be the candidate genes for analysis of triplet repeat expansion and a possible association with disease phenotypes. Identification of 171 genes which contain a minimum of ten repeat units will be of particular interest in future in correlating their association with any disease phenotype due to the expansion potential of repeats present in them. The list of genes and other details of analysis are given in the online supplementary data (http://www.ingenovis.com/tripletrepeats)
Contact: lalji@ccmb.res.in
* To whom correspondence should be addressed.