bluuebunny/crossref_metadata_2025 huggingface dataset:
Arsenite induces delayed mutagenesis and transformation in human osteosarcoma cells at extremely low concentrations
Authors: Mure Kanae , Uddin Ahmed N. , Lopez Laura C. , Styblo Miroslav , Rossman Toby G.
Published: June 2003

Arsenite is a human multisite carcinogen, but its mechanism of action is not known. We recently found that extremely low concentrations (≤0.1 μM) of arsenite transform human osteosarcoma TE85 (HOS) cells to anchorage‐independence. In contrast to other carcinogens which transform these cells within days of exposure, almost 8 weeks of arsenite exposure are required for transformation. We decided to reexamine the question of arsenite mutagenicity using chronic exposure in a spontaneous mutagenesis assay we previously developed. Arsenite was able to cause a delayed increase in mutagenesis at extremely low concentrations (≤0.1 μM) in a dose‐dependent manner. The increase in mutant frequency occurred after almost 20 generations of growth in arsenite. Transformation required more than 30 generations of continuous exposure. We also found that arsenite induced gene amplification of the dihydrofolate reductase (DHFR) gene in a dose‐dependent manner. Since HOS cells are able to methylate arsenite at a very low rate, it was possible that active metabolites such as monomethylarsonous acid (MMAIII) contributed to the delayed mutagenesis and transformation in these cells. However, when the assay was repeated with MMAIII, we found no significant increase in mutagenesis or transformation, suggesting that arsenite‐induced delayed mutagenesis and transformation are not caused by arsenite's metabolites, but by arsenite itself. Our results suggest that long‐term exposure to low concentrations of arsenite may affect signaling pathways that result in a progressive genomic instability. Environ. Mol. Mutagen. 41:322–331, 2003. © 2003 Wiley‐Liss, Inc.
Analysis of 8‐hydroxydeoxyguanosine 5′‐monophosphate (8‐OH‐dGMP) as a reliable marker of cellular oxidative DNA damage after γ‐irradiation
Authors: Mei Nan , Tamae Kazuyoshi , Kunugita Naoki , Hirano Takeshi , Kasai Hiroshi
Published: June 2003

In order to improve 8‐hydroxyguanine (8‐OH‐Gua) detection in DNA, we digested isolated DNA with nuclease P1 and analyzed for 8‐hydroxydeoxyguanosine 5′‐monophosphate (8‐OH‐dGMP) using a high‐performance liquid chromatography system equipped with an electrochemical detector (HPLC‐ECD). The amount of 8‐OH‐Gua in the DNA was expressed as the ratio of 8‐OH‐dGMP to deoxycytidine monophosphate (dCMP). Using this analysis, the background level of 8‐OH‐Gua in DNA from human lung carcinoma cells (A549) was several‐fold lower than that obtained by a previous method. A549 cells were exposed to 20–60 Gy of γ‐radiation and an increase in 8‐OH‐Gua concentration was observed with increasing γ‐ray dose (0.3 residues per 107 dCMP per Gy). Moreover, by an immunohistochemical procedure using a commercial FITC‐kit, 8‐OH‐Gua was clearly detected in A549 cells and the fluorescence intensity of cells with oxidative DNA damage increased with the doses of γ‐irradiation. Using an endonuclease nicking assay, we also found that γ‐rays decreased 8‐OH‐Gua repair activity. The results indicate that 8‐OH‐dGMP is a useful and sensitive marker for estimating oxidative damage in DNA. Environ. Mol. Mutagen. 41:332–338, 2003. © 2003 Wiley‐Liss, Inc.
Seasonal variations in the onset of childhood leukemia/lymphoma: April 1996 to March 2000, Shiraz, Iran
Authors: Karimi Mehran , Yarmohammadi Hooman
Published: June 2003

Infection has long been suspected as a possible factor in the aetiology of leukemia and lymphoma, one of the most common malignancies in children. Since most viral infections have seasonal variations of onset, if seasonal trends in 1 month of diagnosis of leukemia and lymphoma could be proved, this would be supportive evidence for an infectious aetiology. A total of 367 cases in the Hospitals of Shiraz University of Medical Sciences, from April 1996 through March 2000, who were diagnosed as having acute lymphocytic leukemia (ALL), acute myeloblastic leukemia (AML), Burkitt's lymphoma (BL) chronic myeloblastic lymphoma (CML), Hodgkin's disease (HD) or non‐Burkitt's type non‐Hodgkin's lymphoma (NBNHL) were analysed. The month of appearance of the first symptom and the date of diagnosis were recorded. ALL demonstrated statistically significant monthly variation in the date of appearance of the first symptom (p < 0.05; peak in October) and the date of diagnosis (p < 0.05; peak in November). Seasonal variation was demonstrated in the date of the first appearance of symptoms in BL (p < 0.042), and in the date of diagnosis in AML (p < 0.049). There was no statistically significant seasonal variation in the month of diagnosis for other groups. Analysis based on the date of the first symptoms and the date of diagnosis for ALL patients, using summer–winter ratios, also showed a significant winter excess (p < 0.001). Our data provide modest support for an autumn–winter peak in the diagnosis of childhood ALL, underlying mechanisms that account for these patterns are likely to be complex and need more definitive studies. Copyright © 2003 John Wiley & Sons, Ltd.
The effects of STI571 on antigen presentation of dendritic cells generated from patients with chronic myelogenous leukemia
Authors: Sato Naoko , Narita Miwako , Takahashi Masuhiro , Yagisawa Kumiko , Liu Aichun , Abe Takashi , Nikkuni Kohji , Furukawa Tatsuo , Toba Ken , Aizawa Yoshifusa
Published: June 2003

Chronic myelogenous leukemia is caused by the acquisition of the reciprocal (9;22)(q34;q11) chromosomal translocation in hematopoietic stem cells. The fusion protein showed higher and aberrant tyrosine kinase activity. The inhibition of the tyrosine kinase activity of the protein represents a specific therapeutic strategy for bcr/abl‐expressing leukemias. STI571 is a compound of the 2‐phenylaminopyrimidine class that selectively inhibits the tyrosine kinase activity of the Abl protein tyrosine kinase. In this study, we evaluated the effects of STI571 on antigen presentation of dendritic cells generated from the patients with CML. The data showed that by the addition of STI571 the dendritic cells derived from CML clone showed an increased expression of CD1a, CD83, CD80 and CD86 by flow cytometry analysis and showed more intense abilities of allogeneic antigen presentation by mixed leukocyte culture, compared with the control cells without STI571. Our results suggested that STI571 not only has a direct cytotoxic effect on bcr‐abl gene rearranged cells but also an indirect effect associated with increased anti‐leukemic immunological function due to an intensified antigen presentation. Copyright © 2003 John Wiley & Sons, Ltd.
Psychosomatic liaison service in hematological oncology: need for psychotherapeutic interventions and their realization
Authors: Fritzsche Kurt , Struss Yvonne , Stein Barbara , Spahn Claudia
Published: June 2003

Empirical investigations examining the psychosocial distress and need for care of inpatients with hematological malignancies are rare. Little is known about the use of psychotherapeutic interventions in routine care. To evaluate the psychosocial distress of hemato‐oncological inpatients, the need for psychotherapeutic interventions and their realization in the framework of a psychosomatic liaison service has been assessed. Seventy‐two patients from two hematological oncology wards underwent psychodiagnostic interviews and completed self‐rating instruments, elucidating mental disorders, psychosocial distress, coping strategies, quality of life, treatment motivation and psychotherapeutic interventions. Using ICD‐10 criteria, mental and behavioural disorders were diagnosed in 53% of patients. Professional assessment indicated a need for psychotherapeutic treatment in 49%, while 38% of the patients wished to receive psychological support. Actual intervention occurred for all patients in the bone marrow transplantation unit and for 23% of patients in the general hemato‐oncological ward. There is considerable need for psychotherapeutic treatment which can only be handled within the framework of a liaison service in close cooperation with oncologists, nurses and mental health specialists. Copyright © 2003 John Wiley & Sons, Ltd.
Empirical estimation of the effect of urban heat advection on the temperature series of De Bilt (The Netherlands)
Authors: Brandsma T. , Können G. P. , Wessels H. R. A.
Published: June 2003

The influence of urban heat advection on the temperature time series of the Dutch GCOS station De Bilt has been studied empirically by comparing the hourly meteorological observations (1993–2000) with those of the nearby (7.5 km) rural station at Soesterberg. Station De Bilt is in the transition zone (TZ) between the urban and rural area, being surrounded by three towns, Utrecht, De Bilt and Zeist. The dependence of the hourly temperature differences between De Bilt and Soesterberg on wind direction has been examined as a function of season, day‐ and night‐time hours and cloud amount. Strong dependence on wind direction was apparent for clear nights, with the greatest effects (up to 1 °C on average) for wind coming from the towns. The magnitude of the effect decreased with increasing cloudiness. The analysis suggests that most of the structure in the wind direction dependence is caused by urban heat advection to the measuring site in De Bilt. The urban heat advection is studied in more detail with an additive statistical model. Because the urban areas around the site expanded in the past century, urban heat advection trends contaminate the long‐term trends in the temperature series (1897–present) of De Bilt. Based on the present work, we estimate that this effect may have raised the annual mean temperatures of De Bilt by 0.10 ± 0.06 °C during the 20th century, being almost the full value of the present‐day urban heat advection. The 0.10 ± 0.06 °C rise due to urban heat advection corresponds to about 10% of the observed temperature rise of about 1.0 °C in the last century. Copyright © 2003 Royal Meteorological Society
The 850 hPa relative vorticity centres of action for winter precipitation in the Greek area
Authors: Bartzokas A. , Lolis C. J. , Metaxas D. A.
Published: June 2003

In this work, the relationship between atmospheric circulation over Europe and precipitation in Greece is studied during high winter (January–February). Specifically, the 850 hPa relative vorticity centres, affecting or related to precipitation in the various areas of Greece, are defined and the corresponding temporal variability of both parameters is examined. Factor analysis is first applied on both fields, in order to reduce the dimensionality of the original data sets. Canonical correlation analysis is then applied on the factor analysis results, in order to interrelate the two parameters. It is found that: (i) precipitation over western and northern Greece, the eastern Aegean islands and the western Turkish coasts is mainly controlled by vorticity over Italy and the Gulf of Genoa; (ii) southern Aegean Sea and Crete precipitation is controlled by relative vorticity west of Crete; and (iii) eastern mainland areas precipitation is significantly affected by a vorticity seesaw between Tunisia and the northern Aegean. The temporal variations of precipitation and relative vorticity parameters over the above areas show a precipitation reduction over most Greek stations, combined with enhanced anticyclonic activity over almost the whole Mediterranean during the late 1980s and the early 1990s, a period characterized by high North Atlantic oscillation index values. Finally, cluster analysis is applied on the factor scores time series of precipitation, in order to classify the winter precipitation anomaly patterns into objectively defined clusters. Six main precipitation patterns were revealed and the corresponding relative vorticity mean anomaly regimes over southern Europe indicate the atmospheric circulation characteristics causing these specific patterns. Copyright © 2003 Royal Meteorological Society
Dendroclimatic signals in long tree‐ring chronologies from the Himalayas of Nepal
Authors: Cook Edward R. , Krusic Paul J. , Jones Philip D.
Published: June 2003

We describe the development of a tree‐ring chronology network in Nepal that is suitable for reconstructing temperature‐related climate forcing over the past few hundred years. The network is composed of 32 tree‐ring chronologies and is represented by five indigenous tree species. An empirical orthogonal function analysis of the chronologies over the common interval 1796–92 indicates the existence of coherent large‐scale signals among the tree‐ring chronologies that are hypothesized to reflect, in part, broad‐scale climate forcing related to temperatures. A long monthly temperature record for Kathmandu is developed and used to test this hypothesis. In so doing, significant monthly and seasonal temperature responses are identified that provide guidance for the formal reconstruction of two temperature seasons: February–June (1546–91) and October–February (1605–91). Each reconstruction indicates the occurrence of unusually cold temperatures in 1815–22, which coincides with the eruption of Tambora in Indonesia. A novel method is also used to add probable missing multi‐centennial temperature variance to each reconstruction. The resulting ‘adjusted’ reconstructions strongly reflect patterns of temperature variability associated with Little Ice Age cooling and warming into the 20th century, with the October–February season exhibiting the strongest increase in temperature over the past ∼400 years. Only the October–February season shows any evidence for late‐ 20th century warming, whereas February–June temperatures have actually cooled since 1960 (as with the observational series). Copyright © 2003 Royal Meteorological Society
Long‐term snow climate trends of the Swiss Alps (1931–99)
Authors: Laternser Martin , Schneebeli Martin
Published: June 2003

The mean snow depth, the duration of continuous snow cover and the number of snowfall days in the Swiss Alps all show very similar trends during the observation period 1931–99: a gradual increase until the early 1980s (with insignificant interruptions during the late 1950s and early 1970s) followed by a statistically significant decrease towards the end of the century. Regional and altitudinal variations are large; high altitudes show only slight changes, and the trends become more pronounced at mid and low altitudes. At any particular time the southern part of the Alps often has different conditions than the north. Shorter snow duration is mainly caused by earlier snow melting in spring than by later first snowfalls in autumn.

Trends for heavy snowfall events are somewhat different: at elevations above 1300 m a.s.l. a very weak increasing trend towards heavier snowfalls has persisted since the 1960s, and only low altitudes below 650 m a.s.l. show a marked drop since the early 1980s, indicating that heavy winter precipitation to an increasing degree falls in the form of rain instead of snow.

A literature review confirms that, throughout the temperate and subpolar Northern Hemisphere, a similar general pattern of temporal snow variations occurred during the 20th century. Copyright © 2003 Royal Meteorological Society
The effect of large‐scale circulation on precipitation and streamflow in the Gulf of California continental watershed
Authors: Brito‐Castillo Luis , Douglas Arthur V. , Leyva‐Contreras Amando , Lluch‐Belda Daniel
Published: June 2003

The interannual variability of summer and winter rainfall and streamflow in the Gulf of California continental watershed is compared. Varimax‐rotated empirical orthogonal function (EOF) analysis is applied to 15 streamflow series, in the period from 1960 to 1990, and two regions are defined: a central region and a southern region. Results show that in both regions, between 1944 and 1999, the long‐term rainfall variability is well explained by the long‐term streamflow variability in both seasons, the result being statistically significant at the 95% level. We conclude that regional streamflows in that period are climate driven. This conclusion is reinforced when we show that the large‐scale circulation (700 hPa heights) explains: (i) wet and dry conditions in both regions; (ii) conditions of wet and dry years with the same signal of El Niño and La Niña events; and (iii) long‐term periods in association with the Pacific decadal oscillation (PDO). When the PDO is in its warm phase, summers are likely to be dry with an El Niño event and wet with a La Niña event. In the cool phase of the PDO, summers are influenced by more localized events (i.e. the position of the subtropical continental ridge). In winter, warm and cool phases of the PDO are likely to be associated with wet and dry winters respectively. Copyright © 2003 Royal Meteorological Society
A historical upper air‐data set for the 1939–44 period
Authors: Brönnimann Stefan
Published: June 2003

Historical upper‐air data from radiosonde ascents and weather flights were re‐evaluated in order to study the circulation of the upper troposphere and lower stratosphere during the 1939–44 period. Temperature and geopotential height data from 132 records, comprising around 26 500 single atmospheric profiles and 1750 monthly mean profiles, were compiled, digitized, controlled, adjusted, and assessed. The data stem from a number of countries in the extratropical Northern Hemisphere, including Germany and occupied areas, Sweden, the UK, the former Soviet Union, and the USA. In this paper, the principal procedures used to correct the historical radiosonde data for the effects of lag and radiation errors are presented and ways of assessing the accuracy and precision of the data are discussed. The results show that the specified quality criteria are generally met by most data records. Some of the records had to be corrected for systematic errors; a few were rejected. Many series, however, were too short for a reasonable assessment. Also, individual ascents may have a larger error. Monthly anomaly maps of upper‐level temperature and geopotential height based on the re‐evaluated data show clear spatial patterns that are consistent with each other and with corresponding anomaly fields from the Earth's surface. The re‐evaluated data can be used to study synoptic to interannual variability, but they are not suitable for long‐term trend analysis. Copyright © 2003 Royal Meteorological Society
Why people (don't) shop online: A lifestyle study of the internet consumer
Authors: Swinyard William R. , Smith Scott M.
Published: June 2003

This study examines the lifestyle characteristics of on‐line households. By means of a U.S. national probability sample of on‐line heads of households, this descriptive research is the first of its kind to provide a lifestyle perspective of who is using the Internet to shop, who does not shop, and why. It is hypothesized and shown that, compared with on‐line nonshoppers, on‐line shoppers are younger, wealthier, better educated, have higher computer literacy, spend more time on their computer, spend more time on the Internet, find on‐line shopping to be easier and more entertaining, and are more fearful of financial loss from on‐line shopping. The study further hypothesizes that on‐line shoppers, and on‐line nonshoppers, are heterogeneous groups comprised of particular market segments having unique Internet‐related lifestyles. Four on‐line shopper segments and four on‐line nonshopper segments are identified. Each segment is profiled and its marketing implications discussed. © 2003 Wiley Periodicals, Inc.
Exploring consumers' answers to survey questions: Are uninformed responses truly uninformed?
Authors: Graeff Timothy R.
Published: June 2003

Researchers have observed that consumers often give answers to questions about which they are uninformed. Drawing from work in cognitive psychology, this research explores why, how, and when consumers answer survey questions about which they are uninformed. Results from a telephone survey of 1348 consumers suggest that the effects of stimulus factors designed to increase item response rates (pressure to respond in the introduction to the survey, absence of a DK option) are moderated by consumers' familiarity with other similar‐sounding attitude objects. Implications for future research are discussed. © 2003 Wiley Periodicals, Inc.
Novel ion‐exchange resin beads with acid–base indicator property
Authors: Ratna D. , Dalvi V. , Chakraborty B. C. , Deb P. C.
Published: June 2003

Copolymers of styrene and methyl acrylate were synthesized in the form of spherical beads (0.4–1.2 mm) and sulfonated with concentrated sulfuric acid. The sulfonated copolymer shows an in‐built acid–base indicator property; the yellow color in the acid medium changes to an intense pink color at the equivalence point. Also, the ion‐exchange capacity of the sulfonated copolymer increases with time, reaches a maximum, and decreases thereafter. The results were explained in terms of Fourier transform infrared spectroscopic analysis considering internal Friedel–Craft acylation followed by cyclic dehydration leading to a conjugated structure. The developed ion‐exchange resin also demonstrated better performance in demineralization of water as compared with the conventional polystyrene‐based beads. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2166–2170, 2003
A series of new high‐performance materials based on poly[4′‐fluorophenyl‐bis(4‐phenyl)phosphine oxide]
Authors: Rusch‐Salazar Laura A. , Sheares Valerie V.
Published: June 2003

A new series of high‐performance poly(arylene phosphine oxide) (PAPO) materials were synthesized postpolymerization from fluorinated poly(arylene phosphine oxide) (f‐PAPO). The new materials had increased solubility and film‐forming ability over the parent f‐PAPO. With the careful choice of the nucleophile, the thermal stability was also increased. The parent polymer f‐PAPO was synthesized via Ni(0) coupling from aromatic chloride and mesylate monomers. Both monomers were polymerized successfully to create polymers with intrinsic viscosities of 0.235 and 0.123 dL/g, respectively. The higher molecular weight f‐PAPO gave a glass transition of 320 °C and a char yield of 54% at 650 °C in air. The substitution of f‐PAPO via nucleophilic aromatic substitution produced PAPO thermoplastics with significant changes in the properties. The largest increase in the thermal stability relative to f‐PAPO was from 563 to 600 °C 10% weight‐loss values in nitrogen after the displacement of fluoride by 4‐aminophenol, which yielded poly[4‐(4‐aminopheonxyphenyl)bis(4′‐phenyl)phosphine oxide]. Additionally, the char yield increased from 54 to 71% in air at 650 °C. The solubility of the parent polymer was improved after substitution with 3‐tert‐butylphenol, n‐nonylamine, and poly(ethylene glycol)monomethyl ether. All of these became soluble in chloroform, N,N‐dimethylacetamide, and dimethyl sulfoxide. Copolymers were synthesized with 2,5‐dichloro‐4′‐fluorobenzophenone to improve the solubility of f‐PAPO without the loss of thermal stability. These copolymers also underwent nucleophilic aromatic substitution to create an epoxy cure agent that was used with the DEN 431 resin. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2277–2287, 2003
Influence of the bisphenol structure on the direct synthesis of sulfonated poly(arylene ether) copolymers. I
Authors: Harrison William L. , Wang Feng , Mecham Jeffery B. , Bhanu Vinayak A. , Hill Melinda , Kim Yu Seung , McGrath James E.
Published: June 2003

New sulfonated poly(arylene ether sulfone) copolymers with high molecular weights were successfully synthesized with controlled degrees of disulfonation of up to 70 mol % via the direct copolymerization of sulfonated aromatic dihalides, aromatic dihalides, and one of four structurally distinct bisphenols. The disodium salts of the 3,3′‐disulfonated‐4,4′‐dichlorodiphenyl sulfone and 3,3′‐disulfonated‐4,4′‐difluorodiphenyl sulfone comonomers were synthesized via the sulfonation of 4,4′‐dichlorodiphenyl sulfone or 4,4′‐difluorodiphenyl sulfone with 30% fuming sulfuric acid at 110 °C. Four bisphenols (4,4′‐bisphenol A, 4,4′‐bisphenol AF, 4,4′‐biphenol, and hydroquinone) were investigated for the syntheses of novel copolymers with controlled degrees of sulfonation. The composition and incorporation of the sulfonated repeat unit into the copolymers were confirmed by 1H NMR and Fourier transform infrared spectroscopy. Solubility tests on the sulfonated copolymers confirmed that no crosslinking and probably no branching occurred during the copolymerizations. Tough, ductile films were solvent‐cast that exhibited increased water absorption with increasing degrees of sulfonation. These copolymers are promising candidates for high temperature proton‐exchange membranes in fuel cells, which will be reported separately in part II of this series. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2264–2276, 2003
Poly[1‐(trimethylgermyl)‐1‐propyne] and poly[1‐(trimethylsilyl)‐1‐propyne] with various geometries: Their synthesis and properties
Authors: Khotimsky V. S. , Tchirkova M. V. , Litvinova E. G. , Rebrov A. I. , Bondarenko G. N.
Published: June 2003

The polymerization of 1,2‐disubstituted acetylenes [1‐(trimethylgermyl)‐1‐propyne and 1‐(trimethylsilyl)‐1‐propyne] initiated by Nb‐ and Ta‐based catalytic systems was studied within a wide temperature range (−10 to +80 °C) with solvents (cyclohexane, CCl4, toluene, anisol, and n‐chlorobutane) with variable dielectric constants (2.023–7.390). Conditions ensuring the synthesis of poly[1‐(trimethylsilyl)‐1‐propyne] (PTMSP) containing 20–80% cis units and poly[1‐(trimethylgermyl)‐1‐propyne] (PTMGP) containing 3–65% cis units were determined. The PTMSP and PTMGP samples were amorphous, exhibited a two‐phase structure characterized by the presence of less ordered regions and regions with an enhanced level of ordering, and differed in solubility. A correlation was found between the cis/trans ratio and the morphology, the geometrical density of PTMSP and PTMGP films, and the gas permeability of the polymers. The gas permeability and solubility behavior of PTMSP and PTMGP were examined in terms of the molecular characteristics of the polymer samples (the thermodynamic Kuhn segment and the Kerr electrooptic effect). It was demonstrated that the gas permeability, as well as the solubility of the polymers, was defined by their supramolecular ordering, which depended on the lengths of continuous sequences composed of units of analogous microstructures and on the flexibility of macrochains. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2133–2155, 2003
Evolution of multimodal particle size distribution in vinyl acetate/butyl acrylate emulsion copolymerizations
Authors: Immanuel Charles D. , Crowley Timothy J. , Meadows Edward S. , Cordeiro Cajetan F. , Doyle Francis J.
Published: June 2003

This article presents a study on the engineering of multimodal distributions in semibatch emulsion polymerizations with nonionic surfactants. Various methods of producing multimodal distributions are demonstrated, and the sensitivity of the process to the properties of the reagents are analyzed. A test‐bed emulsion polymerization system, equipped with instrumentation to measure particle size distribution (capillary hydrodynamic fractionator) and monomer conversion (densitometer and flow meters), is used for this purpose. The process is monitored and controlled with an industrial distributed control system, which enables the automated operation of the process through sequential or logic controllers operating over lower level proportional integral derivative controllers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2232–2249, 2003
Intrachain chromophore interactions in silanylene‐spaced divinylbenzene copolymers
Authors: Hwu Tsyr‐Yuan , Basu Sourav , Chen Ruey‐Min , Cheng Yen‐Ju , Hsu Jui‐Hung , Fann Wunshain , Luh Tien‐Yau
Published: June 2003

A range of silanylene‐spaced divinylbenzene copolymers (1) and the corresponding monomers (2) have been synthesized by the rhodium‐catalyzed hydrosilylation of the corresponding bisalkynes with bissilyl hydrides, and the photophysical properties of 1 and 2 have been investigated. The silicon moiety in 1 serves as an insulating tetrahedral spacer that makes 1 highly folded. The two chromophores may be in close proximity such that a ground‐state intrachain interaction between two conjugated moieties through space might occur. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2218–2231, 2003
In situ ethylene homopolymerization and copolymerization catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonite
Authors: Liu Chengbin , Tang Tao , Wang Dun , Huang Baotong
Published: June 2003

Ethylene homopolymerizations and copolymerizations were catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonites that had been rendered organophilic via the ion exchange of the interlamellar cations of layered montmorillonite with hydrochlorides of L‐amino acids (AAH+Cl−) or their methyl esters (MeAAH+Cl−), with or without the further addition of hexadecyltrimethylammonium bromide (C16H33N+Me3Br−; R4N+Br−). In contrast to the homogeneous Cp2ZrCl2/methylaluminoxane catalyst for ethylene homopolymerizations and copolymerizations with 1‐octene, the intercalated Cp2ZrCl2 activated by methylaluminoxane for ethylene homopolymerizations and copolymerizations with 1‐octene proved to be more effective in the synthesis of polyethylenes with controlled molecular weights, chemical compositions and structures, and properties, including the bulk density. The effects of the properties of the organic guests on the preparation and catalytic performance of the intercalated zirconocene catalysts were studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2187–2196, 2003
Living/controlled radical copolymerization of N‐substituted maleimides with styrene in 1‐butyl‐3‐methylimidazolium hexafluorophosphate and anisole
Authors: Zhao You‐Liang , Chen Chuan‐Fu , Xi Fu
Published: June 2003

The atom transfer radical copolymerization of N‐substituted maleimides such as N‐phenylmaleimide (PhMI), N‐cyclohexylmaleimide (ChMI), and N‐butylmaleimide (NBMI) with styrene initiated with dendritic polyarylether 2‐bromoisobutyrates in an ionic liquid, 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim][PF6]), at room temperature and anisole at 110 °C was investigated. The dendritic‐linear block copolymers obtained in ionic liquid possessed well‐defined molecular weight and low polydispersity (1.05 < Mw/Mn < 1.32) and could be used as a macroinitiator for chain‐extension polymerization, suggesting the living nature of the reaction system. The ionic liquids containing catalyst could be recycled in the atom transfer radical polymerization systems without further treatment. Compared with polymerization conducted in anisole, the polymerization in ionic liquid had a stronger tendency for alternation. The tendency for alternation decreased in the order PhMI > NBMI > ChMI in [bmim][PF6] and PhMI > ChMI > NBMI in anisole. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2156–2165, 2003
Chain composition dependence of luminescence properties for copolymers of 2‐methoxy‐5‐2′‐ethyl‐hexyloxy‐1,4‐phenylenevinylene and 2,3‐diphenyl‐5‐octyl‐1,4‐phenylenevinylene
Authors: Chiu Chi‐Chia , Lin King‐Fu , Chou Hsuan‐Liang
Published: June 2003

The copolymers of 2‐methoxy‐5‐2′‐ethyl‐hexyloxy‐1,4‐phenylenevinylene (MEH‐PV) and 2,3‐diphenyl‐5‐octyl‐1,4‐phenylenevinylene were prepared via the Gilch route with their chain compositions and the reactivity ratios of the monomers estimated by 1H NMR spectroscopy. The results indicated that the copolymers tended to form an alternative copolymer as the feed ratio of the monomers closed to one‐half. When an individual copolymer solution in tetrahydrofuran was spun‐cast to form a film, the MEH‐PV units were able to attract the like units from the adjacent chains. As a result, the ultraviolet–visible absorption spectrum of the alternative copolymer in film form was broader than the spectra of those with different compositions. The photoluminescence spectra of the copolymers in film form exhibited the characteristic shoulder of poly(2‐methoxy‐5‐2′‐ethyl‐hexyloxy‐1,4‐phenylenevinylene), even though the content of MEH‐PV units was not great enough for the formation of repeat units in sequence. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2180–2186, 2003
Complexation of copper(II) ions with imidazole–carboxylic polymeric systems
Authors: Annenkov V. V. , Danilovtseva E. N. , Saraev V. V. , Mikhaleva A. I.
Published: June 2003

The interaction of two polyampholyte systems, poly(1‐vinylimidazole‐co‐acrylic acid) and interpolymer complex poly(acrylic acid)/poly(1‐vinylimidazole) with copper(II) ions in water, was examined with potentiometry (pH‐metry and Cu‐selective electrode) and electron spin‐resonance spectroscopy. Coordination of Cu2+with copolymer proceeded by carboxylic groups, whereas the interpolymer system azole units were also involved in the inner sphere of the complex. Synergism between coordination with metal ions and intramolecular hydrogen or ionic bonds was shown. The interpolymer complex was an effective system for binding, extracting, and concentrating copper ions from water. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2256–2263, 2003
Nonstoichiometric polyelectrolyte complex of carboxymethylcellulose and N‐methylated poly(2‐vinylpyridine): Formation of a gel‐like structure
Authors: Vishalakshi B. , Ghosh Soumyadeb
Published: June 2003

The formation of polyelectrolyte complexes between carboxymethylcellulose and N‐methylated poly(2‐vinylpyridine), at a nonstoichiometric mixing ratio, was studied. Various methods, such as viscometry, turbidimetry, electrophoresis, and optical spectroscopy, were used to investigate the complexes with respect to their composition, structure, and stability in aqueous systems of different ionic strengths. A gel‐like structure was proposed for the nonstoichiometric polyelectrolyte complexes. Two steps of complex formation—ionic bond formation followed by its rearrangement—were identified. The conformational change of the polyelectrolyte chains in the complexes, responsible for the slower and latter step, was followed by viscometry, and the results were interpreted on the basis of a model proposed for the kinetics of swelling of hydrogels. A similarity was found between the kinetics of diffusion of polymer segments responsible for the swelling of a macrogel of a nonionic polymer and the rearrangement of ionic bonds leading to the formation of a nonstoichiometric polyelectrolyte complex el. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2288–2295, 2003
Building sustainable science curriculum: Acknowledging and accommodating local adaptation
Authors: Barab Sasha Alexander , Luehmann April Lynn
Published: June 2003

A core challenge facing science educators is how to develop and support the implementation of project‐based, technology‐rich science curriculum that is consistent with international calls for a “new approach” to science education while at the same time meeting the everyday needs of classroom teachers. In this article, we discuss the challenges of scaling out university‐developed, project‐based curricula, providing a contextualizing frame for the articles that constitute this current issue of Science Education. Specifically, we overview (1) what constitutes and why implement inquiry‐based, project‐focused learning environments, (2) the role of integrating technology to support their implementation, (3) the value of engaging in design experiments for their development, (4) the importance of allowing for local adaptation, and (5) the process of curricular diffusion. In our thinking, the process of dissemination is not simply “rubber‐stamping” the same program into multiple contexts; rather, the process of large‐scale adoption involves additional, individual teacher‐directed design, fitting, and adaptation for local circumstances. © 2003 Wiley Periodicals, Inc. Sci Ed 87:454–467, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10083
Research towards an expanded understanding of inquiry science beyond one idealized standard
Authors: Songer Nancy Butler , Lee Hee‐Sun , McDonald Scott
Published: June 2003

The work presented builds on a multiyear effort to study the implementation and adaptation of Kids as Global Scientists (KGS), an inquiry‐based, technology‐rich middle school learning environment enacted simultaneously in hundreds of classrooms across the nation. Two groups of teachers participated in this study. One group consists of “maverick” teachers: those distributed across the nation that find us and customize our program to their needs without systematic professional development. This group of teachers tends to work in schools with a relatively rich fund of resources and supports. Another group—urban teachers—resulted from a recent partnership between KGS and teachers from a large, high‐poverty urban school district. We provide these teachers with targeted professional development to help them overcome constraints common to their schools. This study provides profiles of both maverick and urban teachers, and then examines teacher and student data from five focus classrooms that were successful in implementing KGS. In all cases, successful classrooms were defined as those where students made significant positive gains on open‐ended and multiple‐choice assessments. The focus classrooms consisted of three classrooms from urban teachers in high‐poverty environments and two classrooms from maverick teachers in middle‐class suburban environments. The paper discusses the need for research that provides multiple exemplars of classroom science inquiry that are realized through large‐scale enactments responsive to diverse learning environments. © 2003 Wiley Periodicals, Inc. Sci Ed 87:490–516, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10085
WISE design for knowledge integration
Authors: Linn Marcia C. , Clark Douglas , Slotta James D.
Published: June 2003

Scaling research‐based curriculum to the multitude of science teaching standards and contexts has proven difficult in the past. To respond to the challenge, the Web‐based Inquiry Science Environment (WISE) offers designers a technology‐enhanced, research‐based, flexibly adaptive learning environment. The learning environment can incorporate new features such as modeling tools or hand‐held devices. Using WISE, design teams can create projects that bend but do not break when customized to support new school contexts and state standards. WISE curriculum projects are created by diverse design teams that include classroom teachers, technologists, discipline experts, pedagogy researchers, and curriculum designers. WISE inquiry projects incorporate Internet materials and build on the commitments and talents of teachers as well as the constraints and opportunities of their classroom contexts rather than imposing new practices without concern for past successes. These design teams create projects that incorporate diverse features of the WISE learning environment to form specific patterns that are then combined into whole projects. We refer to the whole projects as implementing curriculum design patterns for student activities. The projects are tested to determine how the curriculum design patterns promote knowledge integration, then reviewed by WISE researchers and revised accordingly (see M. C. Linn, P. Bell, & E. A. Davis, in press, Internet Environments for Science Education). Hillsdale, NJ: Erlbaum.). The most successful projects become part of the WISE library. This paper describes WISE design team practices, features of the WISE learning environment, and patterns of feature use in current library projects. The success of WISE in classrooms illustrates how flexibly adaptive projects can meet the needs of diverse teachers. Variation amongst library projects shows that designers can support inquiry with a wide variety of activities. Taken together, the library of projects and the success of students learning from them suggest that sustainable curricular innovations require extensive opportunities for customization and flexibly adaptive designs. © 2003 Wiley Periodicals, Inc. Sci Ed 87:517–538, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10086
REML and ML estimation for clustered grouped survival data
Authors: Lam K. F. , Ip David
Published: June 2003

Clustered grouped survival data arise naturally in clinical medicine and biological research. For example, in a randomized clinical trial, the variable of interest is the time to occurrence of a certain event with or without a new treatment and the data are collected from possibly correlated subjects from independent clusters. However it is sometimes impossible or too expensive to monitor the experimental subjects continuously. The subjects are examined regularly and the continuous survival data are thus grouped into a discrete time scale. With such a design, researchers are mainly interested in the effectiveness of the new treatment as well as the correlation among subjects from the same cluster, namely the intracluster correlation. This paper suggests a random effects approach to the estimation of the regression parameter with various choices of regression model and also the dependence parameter which characterizes the intracluster correlation. Time dependent covariates can be accommodated in the proposed model, and the estimation procedure will not be further complicated with large cluster sizes. The proposed method is applied to the data from the Diabetic Retinopathy Study, the objective of which is to evaluate the effectiveness of laser photocoagulation in delaying or preventing the onset of blindness in the left and right eyes of individuals with diabetes‐associated retinopathy. The intracluster correlation using a grouped proportional hazards regression model can be estimated and the relationship between the regression parameter estimates based on the random effects approach and the marginal approach using a dynamic logistic regression model are discussed. Results from a simulation study of the proposed method are also presented. Copyright © 2003 John Wiley & Sons, Ltd.
Confidence limits for the ratio of two rates based on likelihood scores: non‐iterative method
Authors: Graham P. L. , Mengersen K. , Morton A. P.
Published: June 2003

This paper describes a method for creating a confidence interval for the ratio of rates using the score statistic. This non‐iterative and easy to apply procedure produces confidence intervals that are suitable for use with Poisson data and simulation results indicate that it is close to the nominal level for a wide range of scenarios. Copyright © 2003 John Wiley & Sons, Ltd.
Implications of genetic traits on vaccine efficacy
Authors: Murthy B. N.
Published: June 2003

Literature on genetic screening in the community suggests that people having specific genotypes may either get or protect from infection, for example, malaria, human papiloma virus, and haemophilic influenza, for which vaccines are either already developed or being targeted. In such a situation, the evaluation of the efficacy of vaccine in the community needs to be examined with caution. In this paper, I present a method for the estimation of vaccine efficacy (VE) in the presence of genetic traits/component (θ) and the sample size required to estimate the 95 per cent CI with a given relative width for the estimated vaccine efficacy. Considering true efficacy ranging from 40 to 80 per cent and the possible values of the genetic component (θ) ranging from 0 to 60 per cent, the VE was estimated. The 95 per cent confidence intervals (CI) for the estimated VE for relative widths (R) 1.0 and 0.1 were computed. The sample sizes required for each of the unvaccinated and vaccinated cohorts were computed for estimating the 95 per cent CI for given incidence rates in the unvaccinated (Iu) cohort. In the presence of genetic traits I found that the VE was consistently overestimated. There existed change in the location as well as the asymmetry of the 95 per cent CIs over the point estimate of VE. The sample size required for estimating 95 per cent CI of VE was substantially reduced, resulting in savings. The more the genetic component (θ) affecting disease in the community, the more the savings in sample size. I examined the above estimators for (i) VE, (ii) 95 per cent CI for VE and (iii) sample size required for estimating 95 per cent CI of VE using the real‐life data from the Haemophilus influenzae type b vaccine trial conducted in Finland and the global genetic structure of encapsulated H. influenza. Because of escalated VE and large savings in sample size for estimating the 95 per cent CI for VE, I recommend that the design should consider the genetic component that causes/protects from infection/disease for the evaluation of efficacy of vaccine in the field. Copyright © 2003 John Wiley & Sons, Ltd.
Comparing HLA antigen frequencies between two groups of patients
Authors: Follmann Dean A.
Published: June 2003

For diseases that involve the immune system, the alleles of the human leukocyte antigen (HLA) complex can play a major role. For example, if responsiveness to therapy is immunologically mediated, one would think that responders and non‐responders might tend to have different HLA alleles. However, comparing the frequencies between the two groups of patients at each allele can introduce a substantial multiple comparisons problem as the number of alleles is large. This paper proposes an efficient two‐stage procedure for identifying alleles that may mediate response. In the first‐stage, the distribution of all alleles for the patients are compared to a reference population and a few alleles are selected. These candidate alleles are then compared between the two groups of patients using a modest Bonferroni correction. The two‐stage procedure strongly controls the type I error rate as the first‐stage selection is statistically independent of the second‐stage tests. We analyse a cohort of patients with bone marrow failure who are classified as responders or non‐responders to immunosuppressive therapy. Published in 2003 by John Wiley & Sons, Ltd.
Comparing longitudinal binary outcomes in an observational oral health study
Authors: Shelton Brent J. , Gilbert Gregg H. , Lu Zhenmei , Bradshaw Patrick , Chavers L. Scott , Howard George
Published: June 2003

Observational studies continue to be recognized as viable alternatives to randomized trials when making treatment group comparisons, in spite of drawbacks due mainly to selection bias. Sample selection models have been proposed in the economics literature, and more recently in the medical literature, as a method to adjust for selection bias due to observed and unobserved confounders in observational studies. Application of these models has been limited to cross‐sectional observational data and to outcomes that are continuous in nature. In this paper we extend application of these models to include longitudinal studies and binary outcomes. We apply a two‐stage probit model using GEE to account for correlated longitudinal binary chewing difficulty outcomes. Chewing difficulty was measured every six months during a 24‐month period between two groups of subjects: those either receiving or not receiving dental care. Dental care use was measured at six‐month intervals as well. Results from our proposed model are compared to results using a standard GEE model that ignores the potential selection bias introduced by unobserved confounders. In this application, accounting for selection bias made a major difference in the substantive conclusions about the outcomes of interest. This is due in part to an adverse selection phenomenon in which those most in need of treatment (and consequently most likely to benefit from it) are actually the ones least likely to seek treatment. Our application of sample selection models to binary longitudinal observational outcome data should serve as impetus for increased utilization of this promising set of models to other health outcomes studies. Copyright © 2003 John Wiley & Sons, Ltd.