bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractIn 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

AbstractWe 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

AbstractThe 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

AbstractThe 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

AbstractHistorical 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

AbstractThis 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

AbstractResearchers 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

AbstractCopolymers 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

AbstractA 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

AbstractNew 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

AbstractThe 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

AbstractThis 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

AbstractA 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

AbstractEthylene 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

AbstractThe 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

AbstractThe 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

AbstractThe 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