bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between the positive temperature coefficient of resistivity and dynamic rheological behavior for carbon black‐filled high‐density polyethylene
Authors: Zheng Qiang , Song Yihu , Wu Gang , Song Xubing
Published: March 2003

Studies on the relationship between resistivity and dynamic rheological properties of carbon black‐filled high‐density polyethylene (CB/HDPE) composites were carried out. Change of resistivity ρ is associated with the dynamic modulus before the positive temperature coefficient/negative temperature coefficient (PTC/NTC) transition temperature. When the temperature approaches the melting point of HDPE, ρ increases rapidly with a decreasing modulus, corresponding to PTC transition. The resistivity‐dynamic viscoelasticity relationship in the PTC region can be divided into two parts in which the changes of ρ with storage modulus G′ and loss modulus G″ can be described by the scaling laws given by the critical storage modulus and loss modulus G′c and G″c; adjustable parameters ρ′1c, ρ′2c, ρ″1c and ρ″2c; and nonlinear exponents n and m, respectively. The accordance between the experimental data and the scaling functions of the dimensionless quantities (G′/G′c − 1) and (G″/G″c − 1) in the PTC transition region suggests that the ρ jump may be the result of a modulus‐induced percolation. G′c and G″c increase, but the four scaling resistivitis, ρ′1c, ρ′2c, ρ″1c, and ρ″2c, decrease with increasing CB concentration, implying that the microstructure change of the composites is the determinant factor for the PTC behavior and the resistivity‐dynamic modulus relationship. However, ρ′2c and ρ″2c exhibit no scaling dependence. It is suggested that a threshold concentration exists for the modulus of the composites on the basis of examining the plot of both G′c and G″c against CB concentration. The scaling laws G′ ∼ Φx and G″ ∼ Φy hold for the concentration dependence of the critical modulus when Φ > Φc and the estimated values of x and y are 1.10 ± 0.10 and 0.89 ± 0.29, respectively. The resistivity‐dynamic modulus can shift to form a master curve. The horizontal factors aG′ and aG″ and the vertical factors a′ and a″ are relevant to the concentration dependence of the dynamic modulus or PTC behavior. It is believed that the former would be involved in changing the mechanical microstructure formed by the complicated interaction of CB particle and polymer segments, and the latter would be involved in the overall changes of conducting a network during the PTC transition region. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 983–992, 2003
Dialdehyde starch‐crosslinked chitosan films and their antimicrobial effects
Authors: Tang Rupei , Du Yumin , Fan Lihong
Published: March 2003

For improved mechanical and water‐swelling properties of chitosan films, a series of transparent films were prepared with dialdehyde starch as a crosslinking agent. Fourier transform infrared and X‐ray analysis results demonstrated that the formation of Schiff's base disturbed the crystallization of chitosan. The mechanical properties and water‐swelling properties of the films were significantly improved. The best values of the tensile strength and breaking elongation were 113.1 MPa and 27.0%, respectively, when the dialdehyde starch content was 5%. All the crosslinked films still retained obvious antimicrobial effects toward S. aureus and E. coli, and they showed potential for biomedical applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 993–997, 2003
Smectic structures in electrochemically prepared poly(3,4‐ethylenedioxythiophene) films
Authors: Breiby Dag W. , Samuelsen Emil J. , Groenendaal L. “Bert” , Struth Bernd
Published: March 2003

Sub‐micrometer layers of electrochemically prepared methyl‐ and decyl‐substituted poly(3,4‐ethylenedioxythiophene) (PEDOT) carrying perchlorate counterions have been examined with grazing incidence X‐ray diffraction with synchrotron radiation. The materials were found to be partially crystalline, and the data could be ascribed to a model of sheets of π‐π stacked polymer chains with a smectic ordering of these sheets. An unsubstituted PEDOT sample with the polymeric polystyrenesulfonic acid as a counterion was also investigated and turned out to be essentially amorphous. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 945–952, 2003
Warpage prediction of optical media
Authors: Fan Bingfeng , Kazmer David O. , Bushko Wit C. , Theriault Richard P. , Poslinski Andrew J.
Published: March 2003

The warpage of injection–compression‐molded optical media, such as compact discs and digital video discs, due to asymmetric cooling during production is predicted. Thermally induced stress is calculated with a nonisothermal compressible flow simulation with a viscoelastic constitutive model. A finite element analysis is formulated with axisymmetric plate elements based on Kirchhoff thin‐plate theory to simulate the warpage of the disc due to the asymmetric thermal stress and gravity after demolding. Simulation results of warpage for compact‐disc‐recordable moldings are compared with experimental observations under different processing conditions, such as the melt temperature, mold temperature, and packing pressure, with an optical grade of polycarbonate. The comparison shows that the simulation well predicts the effects of various processing conditions. Both the simulation and experiment indicate that of the processing conditions, the mold temperature has the greatest effect on warpage. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 859–872, 2003
Miscibility and ferroelectric behavior in blends of poly(vinylidene fluoride/trifluoroethylene) and poly(vinyl acetate)
Authors: Tang Yiwen , Scheinbeim Jerry
Published: March 2003

The blend system containing a poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)] copolymer (68/32 mol %) and poly(vinyl acetate) (PVAc) was miscible from the results of differential scanning calorimetry (DSC) studies that exhibit the presence of a single, composition‐dependent glass transition temperature (Tg) and a strong melting point depression for the semicrystalline P(VDF/TrFE) component. However, differences between the DSC and dielectric measurements, which showed a separate P(VDF/TrFE) Tg peak, suggests that the P(VDF/TrFE)/PVAc blends are actually partially miscible. Because of the lower dielectric constant of PVAc and the reduced sample crystallinity caused by the addition of PVAc, both the dielectric constant and the remanent polarization of the copolymer blends decrease with increasing PVAc content. The presence of a small amount of PVAc stabilized the anomalous ferroelectric behavior of ice–water‐quenched P(VDF/TrFE), and the blend portrayed normal polarization reversal behavior after adding only 1 wt % PVAc. The piezoelectric response suggests small changes with an increasing number of poling cycles. It is believed that PVAc affects the D‐E hysteresis behavior at the interface between crystalline and amorphous phases, although much work remains to be done to confirm this hypothesis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 927–935, 2003
Flame retardancy and smoke suppression of magnesium hydroxide filled polyethylene
Authors: Kim Sangcheol
Published: March 2003

In this work, halogen‐free, flame‐retarded polyethylene was investigated to study the effect of inorganic fillers on the improvement of flame retardancy and the suppression of smoke density. Through analyses on the thermal stability and smoke density, it was found that the flame retardancy developed by magnesium hydroxide could effectively be increased by the additional incorporation of zinc borate and talc. Furthermore, a synergistic effect was observed when zinc borate and talc were incorporated together. This result was confirmed by the observation of fire performance with cone calorimetry. A morphological study supported the idea that the improvement in the flame retardancy and the suppression of smoke density was due to hard and compact charred layers formed by the interactions between polymer and inorganic fillers. The charred layers provided a good thermal and flame barrier. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 936–944, 2003
Crystallization and morphology of poly(vinylidene fluoride)/poly(3‐hydroxybutyrate) blends. I. Spherulitic morphology and growth by polarized microscopy
Authors: Liu Jieping , Jungnickel Bernd‐J.
Published: March 2003

The development of the poly(3‐hydroxybutyrate) (PHB) morphology in the presence of already existent poly(vinylidene fluoride) (PVDF) spherulites was studied by two‐stage solidification with two separate crystallization temperatures. PVDF formed irregular dendrites at lower temperatures and regular, banded spherulites at elevated temperatures. The transition temperature of the spherulitic morphology from dendrites to regular, banded spherulites increased with increasing PVDF content. A remarkable amount of PHB was included in the PVDF dendrites, whereas PHB was rejected into the remaining melt from the banded spherulites. When PVDF crystallized as banded spherulites, PHB could consequently crystallize only around them, if at all. In contrast, PHB crystallized with a common growth front, starting from a defined site in the interfibrillar regions of volume‐filling PVDF dendrites. It formed by itself dendritic spherulites that included a large number of PVDF spherulites. For blends with a PHB content of more than 80 wt %, for which the PVDF dendrites were not volume‐filling, PHB first formed regular spherulites. Their growth started from outside the PVDF dendrites but could later interpenetrate them, and this made their own morphology dendritic. These PHB spherulites melted stepwise because the lamellae inside the PVDF dendrites melted at a lower temperature than those from outside. This reflected the regularity of the two fractions of the lamellae because that of those inside the dendrites of PVDF was controlled by the intraspherulitic order of PVDF, whereas that from outside was only controlled by the temperature and the melt composition. The described morphologies developed without mutual nucleating efficiency of the components. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 873–882, 2003
Mapping of periglacial geomorphology using kite/balloon aerial photography
Authors: Boike Julia , Yoshikawa Kenji
Published: March 2003

Kite and balloon aerial photography is introduced as a remote‐sensing method for periglacial features and vegetation. High‐resolution aerial pictures obtained by this method from Alaskan study sites are used for geometric analysis of ice‐wedge networks, quantification of patterned ground, and mapping of water and vegetation. High‐resolution aerial photographs could be an important data set for monitoring changes in permafrost pattern, periglacial processes and vegetation over time and space. Copyright © 2003 John Wiley & Sons, Ltd.
The development of periglacial geomorphology: 1‐ up to 1965
Authors: French Hugh
Published: March 2003

The earliest observations upon cold, non‐glacial processes and phenomena were made in the eighteenth and nineteenth centuries by the European explorers of the vast sub‐arctic regions of North America and Eurasia. The initial beginnings of periglacial geomorphology can be traced to Lozinski and the participants of the XI International Geological Congress excursion to Spitzbergen in 1910–11. The real growth in periglacial geomorphology occurred in the two decades after the Second World War. By the mid‐1960s periglacial geomorphology was recognized as a descriptive branch of climatic geomorphology. There were two broad sub‐categories: (i) Pleistocene and Quaternary studies dealing largely with the mid‐latitudes, and (ii) present‐day process studies conducted in the sub‐arctic and arctic regions of North America and Scandinavia. Permafrost studies were being conducted in relative isolation in North America and the Soviet Union, not only to each other, but also to mainstream periglacial geomorphology. The merging of all these interests, and the development of quantitative, process‐oriented studies aimed at understanding periglacial landforms did not come about for several more decades. Copyright © 2003 John Wiley & Sons, Ltd.
Thermokarst ponds as indicators of the former distribution of palsas in Finnish Lapland
Authors: Luoto Miska , Seppälä Matti
Published: March 2003

Thermokarst 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

Recent 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

In 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

The 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

This 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

A 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

A 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

Invariant 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

The 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.
Involvement of Protein Tyrosine Kinases and Phosphatases in Uptake and Intracellular Replication of Virulent and Avirulent Leishmania donovani Promastigotes in Mouse Macrophage Cells
Authors: Ghosh Debjani , Chakraborty Prasanta
Published: March 2003

In this study we show that protein tyrosine kinases (PTKs) and also protein tyrosine phosphatases are involved in the uptake of virulent and avirulent Leishmania donovani promastigotes by macrophage cells. Protein tyrosine kinase inhibitors such as genistein or tyrphostin 25 decrease parasite uptake in a dose-dependent manner. Addition of sodium orthovanadate, a protein tyrosine phosphatase inhibitor, prior to infection significantly increases parasite internalization. A similar uptake profile was observed with both virulent and avirulent L. donovani promastigotes. Treatment of macrophages with cytochalasin B, an inhibitor of actin polymerization prevents promastigote uptake, indicating that a tyrosine kinase induced actin polymerization signal may be necessary for the entry of the parasites. In contrast, neither genistein nor tyrphostin significantly reduce intracellular replication of this pathogen or nitric oxide production, suggesting that the PTK-mediated signal is not related to the ultimate virulence mechanism associated with intracellular replication of this pathogen. These data collectively suggest that protein tyrosine kinase mediated entry of L. donovani promastigotes into macrophages is not a virulence-associated event.
F0 Cysteine, bCys21, in the Escherichia coli ATP Synthase Is Involved in Regulation of Potassium Uptake and Molecular Hydrogen Production in Anaerobic Conditions
Authors: Mnatsakanyan Nelli , Bagramyan Karine , Vassilian Anait , Nakamoto Robert K. , Trchounian Armen
Published: March 2003

The single cysteine in the b subunit of the membranous F0 sector and the 19 cysteines in extramembranous F1 sector of the Escherichia coli ATP synthase were replaced by alanine. When cells were grown under anaerobic conditions on glucose, the kcat for ATP hydrolysis of membrane vesicles containing the bCys21Ala mutant enzyme, but not enzymes with other cysteine replacements, was lower, while ATP-driven H+ pumping was unchanged. However, the ATP-dependent increase in the number of accessible thiol groups in membrane vesicles was negated. Furthermore, K+ uptake and molecular hydrogen production by whole cells and protoplasts was greatly decreased. These results indicate a role for the F0 subunit bCys21 in the functionality of F0F1 and coupling to other membranous activities under fermentative conditions.
A Combination of Cation Exchange and Ligand-Affinity Chromatography for Purification of Two Molecular Species of the Folate Binding Protein in Human Milk, One Equipped with a Hydrophobic Glycosyl Phosphatidylinositol Tail: Characterization of Hydrophobicity and Electrical Charge
Authors: Holm Jan , Hansen Steen Ingemann , Høier-Madsen Mimi
Published: March 2003

Cation exchange chromatography combined with ligand (methotrexate) affinity chromatography on a column desorbed with a pH-gradient was used for separation and large scale purification of two folate binding proteins in human milk. One of the proteins, which had a molecular size of 27 kDa on gel filtration and eluted from the affinity column at pH 5–6 was a cleavage product of a 100 kDa protein eluted at pH 3–4 as evidenced by identical N-terminal amino acid sequences and a reduction in the molecular size of the latter protein to 27 kDa after cleavage of its hydrophobic glycosylphosphatidyl-inositol tail that inserts into Triton X-100 micelles. Chromatofocusing showed that both proteins possessed multiple isoelectric points within the pH range 7–9. The 100 kDa protein exhibited a high affinity to hydrophobic interaction chromatographic gels, whereas this was only the case with unliganded forms of the 27 kDa protein indicative of a decrease in the hydrophobicity of the protein after ligand binding.
Silent disaster: A European perspective on threat perception from Chernobyl far field fallout
Authors: Tønnessen Arnfinn , Mårdberg Bertil , Weisæth Lars
Published: March 2003

Surveys 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.
The 78 kDa Glucose-Regulated Protein (GRP78/BIP) Is Expressed on the Cell Membrane, Is Released into Cell Culture Medium and Is Also Present in Human Peripheral Circulation
Authors: Delpino Andrea , Castelli Mauro
Published: March 2003

In human rabdomiosarcoma cells (TE671/RD) chronic exposure to 500 nM thapsigargin (a powerful inhibitor of the endoplasmic reticulum Ca2+-ATPases) resulted in the induction of the stress protein GRP78/BIP. Making use of the surface biotinylation method, followed by the isolation of the GRP78 using ATP-agarose affinity chromatography, it was found that a fraction of the thapsigargin-induced GRP78 is expressed on the cell surface. The presence of GRP78 on the membrane of thapsigargin-treated cells was confirmed by fractionation of cell lysates into a soluble and a membrane fraction, followed by Western blot analysis with an anti-GRP78 antibody. It was also found that conspicuous amounts of GRP78 are present in the culture medium collected from thapsigargin-treated cultures. This extracellular GRP78 originates mostly by an active release from intact cells and does not result solely from the leakage of proteins from dead cells. Moreover, small amounts of circulating, free GRP78 and naturally-occurring anti-GRP78 autoantibodies were detected in the peripheral circulation of healthy human individuals.
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

This 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

Follow‐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

Prenatal 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

Recent 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

Although 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

Three 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

This 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.
Baire's Category Theoretic Classification of Compact Expansive Dynamical Systems
Authors: Sakai Kazutaka
Published: March 2003

A revised version of the estimation inequality of Akashi [2] is given, and this result is applied to Baire's category theoretic classification of ∊-expansive dynamical systems. Moreover, this classification method is applied to topological classification of shift dynamical systems on finite-dimensional compact domains.
Open Systems and Consciousness: A Physical Discussion
Authors: Ingarden Roman S.
Published: March 2003

Further discussion of the author's ideas, as well as their confrontation with similar and different concepts of consciousness, have been given in the Introduction. Then the physical and, in lesser degree, also mathematical aspects of open systems, in particular of human person, are sketched in Sec. 2. The quantum concept of the decoherence time is treated as a model for a finite life-time of any composed physical and biological system. In Sec. 3 the role of languages of many types in living and non-living systems is briefly considered, as well as the importance of modality for sentence predicates. In Sec. 4, the structure of the cerebral neocortex and its speech centers is briefly described from the point of view of the mechanism of thinking and the consciousness. The concepts of laterality and dominance (left or right hemispheres of the brain) and their dependence on the type of culture and education are shown on the example of the differences between the Japanese and Western perception of languages (discoveries of Liberman and Tsunoda). In Secs. 5 and 6 the experimental evidence for the connection of consciousness with the speech centers are presented and some questions are posed.
The Least Action and the Metric of an Organized System
Authors: Georgiev Georgi , Georgiev Iskren
Published: March 2003

In this paper, we formulate the least action principle for organized system as the minimum of the total sum of the actions of all of the elements. This allows us to see how this most basic law of physics determines the development of the system towards states with less action — organized states. Also we state that the metric tensor can describe the specific state of the constraints of the system, which is its actual organization. With this the organization is defined in two ways: 1. quantitative: the action I; 2. qualitative: the metric tensor gmn. These two measures can describe the level of development and the specifics of the organization of a system. We consider closed and open systems.
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

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

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.
TIGR Gene Indices clustering tools (TGICL): a software
system for fast clustering of large EST datasets
Authors: Pertea Geo , Huang Xiaoqiu , Liang Feng , Antonescu Valentin , Sultana Razvan , Karamycheva Svetlana , Lee Yuandan , White Joseph , Cheung Foo , Parvizi Babak , Tsai Jennifer , Quackenbush John
Published: March 2003

TGICL is a pipeline for analysis of large Expressed Sequence Tags (EST) and mRNA databases in which the sequences are first clustered based on pairwise sequence similarity, and then assembled by individual clusters (optionally with quality values) to produce longer, more complete consensus sequences. The system can run on multi-CPU architectures including SMP and PVM.

Availability: http://www.tigr.org/tdb/tgi/software/

Contact: johnq@tigr.org; johnq@tigr.org

* To whom correspondence should be addressed.
MINRMS: an efficient algorithm for determining protein structure
similarity using root-mean-squared-distance
Authors: Jewett Andrew I. , Huang Conrad C. , Ferrin Thomas E.
Published: March 2003

Motivation: Existing algorithms for automated protein structure alignment generate contradictory results and are difficult to interpret. An algorithm which can provide a context for interpreting the alignment and uses a simple method to characterize protein structure similarity is needed.

Results: We describe a heuristic for limiting the search space for structure alignment comparisons between two proteins, and an algorithm for finding minimal root-mean-squared-distance (RMSD) alignments as a function of the number of matching residue pairs within this limited search space. Our alignment algorithm uses coordinates of alpha-carbon atoms to represent each amino acid residue and requires a total computation time of O(m3n2), where m and n denote the lengths of the protein sequences. This makes our method fast enough for comparisons of moderate-size proteins (fewer than ∼800 residues) on current workstation-class computers and therefore addresses the need for a systematic analysis of multiple plausible shape similarities between two proteins using a widely accepted comparison metric.

Availability: See http://www.cgl.ucsf.edu/Research/minrms

Contact: tef@cgl.ucsf.edu

* To whom correspondence should be addressed.
Prediction of human protein function according to Gene
Ontology categories
Authors: Jensen L. J. , Gupta R. , Stærfeldt H.-H. , Brunak S.
Published: March 2003

Motivation: The human genome project has led to the discovery of many human protein coding genes which were previously unknown. As a large fraction of these are functionally uncharacterized, it is of interest to develop methods for predicting their molecular function from sequence.

Results: We have developed a method for prediction of protein function for a subset of classes from the Gene Ontology classification scheme. This subset includes several pharmaceutically interesting categories—transcription factors, receptors, ion channels, stress and immune response proteins, hormones and growth factors can all be predicted. Although the method relies on protein sequences as the sole input, it does not rely on sequence similarity, but instead on sequence derived protein features such as predicted post translational modifications (PTMs), protein sorting signals and physical/chemical properties calculated from the amino acid composition. This allows for prediction of the function for orphan proteins where no homologs can be found. Using this method we propose two novel receptors in the human genome, and further demonstrate chromosomal clustering of related proteins.

Availability: Sequences can be submitted to the prediction server via a web interface at http://www.cbs.dtu.dk/services/ProtFun/

Contact: ljj@cbs.dtu.dk

* To whom correspondence should be addressed.