bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of non‐uniform radiative damping on the zonal‐mean dynamics of the extratropical middle atmosphere
Authors: Semeniuk K. , Shepherd T. G. 
Published: January 2003

AbstractThe effect of spatial and temporal variations in the radiative damping rate on the response to an imposed forcing or diabatic heating is examined in a zonal‐mean model of the middle atmosphere. Attention is restricted to the extratropics, where a linear approach is viable. It is found that regions with weak radiative damping rates are more sensitive in terms of temperature to the remote influence of the diabatic circulation. The delay in the response in such regions can mean that ‘downward’ control is not achieved on seasonal time‐scales. A seasonal variation in the radiative damping rate modulates the evolution of the response and leaves a transient‐like signature in the annual mean temperature field.Several idealized examples are considered, motivated by topical questions. It is found that wave drag outside the polar vortex can significantly affect the temperatures in its interior, so that high‐latitude, high‐altitude gravity‐wave drag is not the only mechanism for warming the southern hemisphere polar vortex. Diabatic mass transport through the 100 hPa surface is found to lag the seasonal evolution of the wave drag that drives the transport, and thus cannot be considered to be in the downward control regime. On the other hand, the seasonal variation of the radiative damping rate is found to make only a weak contribution to the annual mean temperature increase that has been observed above the ozone hole. Copyright © 2002 Royal Meteorological Society.
Multi‐model multi‐analysis ensembles in quasi‐operational medium‐range forecasting
Authors: Mylne Kenneth R. , Evans Ruth E. , Clark Robin T. 
Published: January 2003

AbstractEnsemble prediction systems (EPS) for medium‐range forecasting attempt to account for uncertainty in numerical weather prediction (NWP) by sampling the distribution function of future atmospheric states. Forecast uncertainty derives from uncertainty in both the analysed initial conditions (analysis errors) and in the forecast evolution (model errors). Current operational systems are primarily based on sampling the analysis errors through initial‐condition perturbations with, at best, only limited sampling of model errors. One approach to sampling model errors and also to widening the sampling of analysis errors, is to include more than one NWP model, and more than one operational analysis to which perturbations are added, in the ensemble system. Previous work has demonstrated from a small number of case‐studies that this multi‐model multi‐analysis ensemble (MMAE) approach can perform significantly better than a single‐model system such as the Ensemble Prediction System (EPS) run by the ECMWF (European Centre for Medium‐Range Weather Forecasts). In this study a MMAE was created by combining the ECMWF ensemble with an ensemble using the Met Office model and analysis, and was run daily for a year to assess the benefits over a larger, quasi‐operational sample of forecasts. The results are compared with the operational ECMWF EPS which includes the latest upgrades, including stochastic physics which makes some allowance for uncertainty due to model errors. Results show that both for probabilistic forecasts (assessed by Brier skill scores and relative operating characteristics) and for deterministic forecasts based on the ensemble mean (assessed by root‐mean square errors) the MMAE has increased forecast skill relative to the EPS. These improvements are obtained with no overall increase in ensemble size. Ensemble spread is also greater in the MMAE, and the increased skill is believed to be due to the additional model producing solutions which are synoptically more different than those produced by a single model ensemble. Benefits of the MMAE vary both in time and with geographical region, depending on which individual ensemble system performs better in particular synoptic situations. It is found that the MMAE almost always performs as well as the best individual ensemble, and on occasions better than either of them. © Crown copyright, 2002.
Grid‐point response to the incremental strategy for variational applications
Authors: Tanguay Monique , Laroche Stéphane 
Published: January 2003

AbstractThe incremental approach is an efficient way to reduce the computational cost of four‐dimensional variational assimilation. In this approach, the discrepancy between the forecast fields and the observations is calculated with a full physics model at high resolution, but the minimization is performed at a lower resolution with a simplified physics model. The incremental approach is also used in sensitivity‐analysis applications where errors in the initial conditions are estimated a posteriori by replacing observations by a subsequent analysis. The incremental strategy as used in typical sensitivity analyses with observations corresponding to a full model state is re‐examined in the context of a grid‐point model by establishing how the grid‐transfer operations in grid‐point space influence the convergence properties of the whole incremental process. We show that two incremental grid‐point formulations are possible. In the first formulation, the tangent‐linear perturbations are interpolated at high resolution to be compared with the forecast errors. In the second one, the forecast errors are interpolated to low resolution before the minimization. Using a one‐dimensional study and identical twin experiments in three dimensions, we study the impact of aliasing associated with the grid‐transfer operations on the two incremental formulations. They are both affected by the misinterpretation of unresolved forecast errors leading to a contribution to resolved forecast errors. However, the first formulation has the property of damping this aliasing contribution and this effect is stronger with higher‐order grid‐transfer operators. Copyright © 2002 Royal Meteorological Society.
Physical, mechanical, and viscoelastic properties of natural rubber vulcanizates cured with new binary accelerator system
Authors: Aprem Abi Santhosh , Joseph Kuruvilla , Laxminarayanan R. , Thomas Sabu 
Published: January 2003

AbstractNatural rubber was vulcanized with a new binary accelerator system based on 1‐phenyl‐2,4‐dithiobiuret (DTB) and dicyclohexyl benzothiazyl sulfenamide. A significant reduction in cure time was observed with the addition of DTB. The cure kinetics was investigated and the activation energy was determined. The mechanical properties were improved by adding DTB, and the maximum values are shown at an optimum concentration. Estimates of the concentration of crosslinks and of the relative proportions of different types of crosslinks were made by the chemical characterization of the vulcanizates. The crosslink densities obtained from swelling measurements and stress–strain measurements were compared with those obtained from modulus measurements. All of them follow a similar trend and support the observed mechanical properties. A dynamic mechanical analysis of the mixes was carried out and the activation energy was determined from Arrhenius plots. The glass‐transition temperature was found to increase with the increase in crosslink density and frequency of measurements. The stress–strain curves were found to not deviate from the strain crystallizing nature of natural rubber. The mechanical properties, network characterization, and processing characteristics were used to optimize the DTB concentration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2193–2203, 2003
A polyampholyte triblock copolymer synthesized for using as the surfactant of miniemulsion polymerization and production of highly uniform microspheres
Authors: Ou Jinn‐Luh , Lim Min‐Shyan , Chen Hui 
Published: January 2003

AbstractMiniemulsions based on styrene/azobisisobutyronitrile (AIBN) in the presence of polyampholyte triblock copolymers as a surfactant and hexadecane (HD) as a cosurfactant were developed. The polyampholyte was prepared by using methyl methacrylate (MMA), methacrylic acid (MAA), and 2‐(dimethylamino) ethyl methacrylate (DMAEMA) as monomers. For the sake of comparison, a miniemulsion polymerization with sodium dodecyl sulfate (SDS) was carried out using the same procedure as the above series. The monomer droplet sizes and their shelf life tests revealed that the polyampholyte could stabilize miniemulsion and lead nucleation mechanisms to droplet nucleation. Miniemulsion polymerization using SDS as the surfactant possess a higher polymerization rate than that of polyampholyte, probably due to the smaller droplet size. Production of uniform microspheres was also carried out in this work. Highly uniform microspheres prepared using polyampholyte as the surfactant in the presence of acetone could be obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2230–2237, 2003
Autohesive properties of polyolefins photografted with hydrophilic monomers
Authors: Yamada Kazunori , Kimura Jun , Hirata Mitsuo 
Published: January 2003

AbstractIn an attempt to provide polyolefins such as low‐ and high‐density polyethylene and polypropylene with autohesive properties, hydrophilic monomers such as methacrylic acid (MAA), acrylic acid (AA), and 2‐(dimethylamino)ethyl methacrylate (DMAEMA) were photografted onto their surfaces. The wettabilities of the grafted plates stayed constant above full coverage of the substrate surfaces with grafted polymer chains, except for the AA‐grafted plates. The amount of absorbed water for the grafted layers formed increased with an increase in the number of grafted polymer chains. The autohesive strength increased with an increase in the wettability and water absorptivity of the grafted plates as well as the temperature and load on heat pressing. For all grafted plates substrate breaking at autohesive strength measurements was observed for grafted amounts 2–3 times as much as those at adhesive strength measurements. The substrate breakings for the HDPE and PP plates photografted with AA and DMAEMA at adhesive strength measurements were observed at lower grafted amounts compared with those photografted with MAA. This study has made it clear that the photografting of hydrophilic monomers onto polyolefin materials can markedly enhance autohesivity without any adhesives as well as the adhesivity for high grafted amounts. Therefore, polyolefin materials with improved autohesivity and adhesivity can be widely applied in adhesive fields, including for novel uses. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2244–2252, 2003
1,3,5‐trihydroxy benzene as a surface modifier of carbon black and its effect on the filler–rubber interaction
Authors: Ganguly S. , Bhattacharya P. , Banerjee A. N. , Chakraborty S. 
Published: January 2003

AbstractA surface‐modified rubber‐grade carbon black has been prepared by treating it with 1,3,5‐trihydroxy benzene (phluroglucinol) in aqueous solution at different molar concentrations. This modified carbon black has been used as one of the compounding ingredients with natural rubber. An attempt has been made to establish a concentration optimum for the modifier. Improved physicomechanical properties like hardness, heat buildup, hysteresis loss, and improved dynamic mechanical properties are observed for the compounded rubber. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2272–2278, 2003
Study of the isothermal curing of an epoxy prepreg by near‐infrared spectroscopy
Authors: Wang Qian , Storm Birgit K. , Houmøller Lars P. 
Published: January 2003

AbstractThe commercial epoxy prepreg SPX 8800, containing diglycidyl ether of bisphenol A, dicyanodiamide, diuron, and reinforcing glass fibers, was isothermally cured at different temperatures from 75 to 110°C and monitored via in situ near‐infrared Fourier transform spectroscopy. Two cure conditions were investigated: curing the epoxy prepreg directly (condition 1) and curing the epoxy prepreg between two glass plates (condition 2). Under both curing conditions, the epoxy group could not reach 100% conversion with curing at low temperatures (75–80°C) for 24 h. A comparison of the changes in the epoxy, primary amine, and hydroxyl groups during the curing showed that the samples cured under condition 2 had lower initial epoxy conversion rates than those cured under condition 1 and that more primary amine–epoxy addition occurred under condition 2. In addition, the activation energy under cure condition 2 (104–97 kJ/mol) was higher than that under condition 1 (93–86 kJ/mol), but a lower glass‐transition temperature of the cured samples was observed via differential scanning calorimetry. The moisture in the prepreg was assumed to account for the different reaction kinetics observed and to have led to different reaction mechanisms. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2295–2305, 2003
Water vapor sorption and transport in dense polyimide membranes
Authors: Huang Jingui , Cranford Richard J. , Matsuura Takeshi , Roy Christian 
Published: January 2003

AbstractThe sorption and transport of water vapor in five dense polyimide membranes were studied by thermogravimetry. The sorption isotherms of water vapor in the polyimides could be successfully interpreted by both the dual‐mode sorption model and the Guggenheim–Anderson–de Boer equation. The water vapor diffusion behavior was found to be nearly Fickian at higher water vapor activities, whereas non‐Fickian diffusion was observed at lower water activities. The phenomena could be well described by the mechanism of combined Fickian and time‐dependent diffusion. The diffusion coefficient and water vapor uptake in the polyimides were strongly dependent on the polymer molecular structure. Except for the polyimide prepared from 3,3′,4,4′‐diphenylsulfone tetracarboxylic dianhydride and 1,3‐bis(4‐aminophenoxy) benzene, the permeability of water vapor in the dense polyimide membranes predicted from the sorption measurement at 30°C corresponded well with the water vapor permeability measured at 85°C. Among the polyimides studied, pyromellitic dianhydride–4,4′‐diaminophenylsulfone (50 mol%)/4,4′‐oxydianiline (50 mol%) showed both high water sorption and diffusion and, therefore, high water vapor permeability, which for vapor permeation membranes is necessary for the separation of water vapor from gas streams. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2306–2317, 2003
Temperature distribution effects during polymerization of methacrylate‐based monoliths
Authors: Mihelič Igor , Koloini Tine , Podgornik Aleš 
Published: January 2003

AbstractMonolithic stationary phases are becoming increasingly important in the field of liquid chromatography. Methacrylate‐based monoliths are produced via free‐radical bulk polymerization. The preparation of large‐volume monoliths is a major problem because the intensive heat released during polymerization causes distortion of the porous monolithic structure. This work presents experimental measurements of temperature distributions during polymerization in moulds of different sizes and at various experimental conditions. A mathematical model for the prediction of temporal and spatial temperature distribution during the polymerization of methacrylate‐based monolithic columns is introduced. The polymerization is described by an unsteady‐state heat conduction equation with the generation of heat related to the general kinetics of polymerization. Predictions from the mathematical model are in good agreement with the experimental measurements at different experimental conditions. A method for construction of large‐volume monolithic columns is presented and an attempt is made to adopt the developed mathematical model in annular geometry. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2326–2334, 2003
Copolymerizations of carbon dioxide and epoxides in the presence of rare earth coordinate catalyst
Authors: Guo Jin‐Tang , Wang Xin‐Ying , Xu Yong‐Shen , Sun Jing‐Wu 
Published: January 2003

AbstractCarbon dioxide (CO2) as a direct material was copolymerized with epoxides to synthesize new aliphatic polycarbonates, and the copolymerization was catalyzed by the coordinate catalyst composed of rare earth yttrium phosphonate and triisobutylaluminum [Y(P204)3–A1(i‐Bu)3]. The epoxides used in this research included epichlorohydrin (ECH) and some new glycidol ether (GE) monomers prepared by the reaction of ECH and phenol or alcohol, such as α‐allyl glycidol ether, β‐chloroethyl glycidol ether, benzene glycidol ether, m‐tolyl glycidol ether, and benzyl glycidol ether. The copolymers were characterized by infrared (IR), 1H nuclear magnetic resonance (‐NMR), and dynamic mechanical analysis. The results show that Y(P204)3–A1(i‐Bu)3 had better catalytic activity in the copolymerization of CO2 with epoxide, and the copolymerization rate of aryl GE was distinctly higher than that of aliphatic GE. Dynamic mechanical analysis indicated the glass transition temperature Tg of the copolymers GE–CO2 were lower than that of ECH–CO2. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2356–2359, 2003
Thermal analysis of ultrafine wool powder
Authors: Xu Weilin , Guo Weiqi , Li Wenbin 
Published: January 2003

AbstractWool powder was produced from wool fiber by pretreatment and then ground by a specially designed machine. Scanning electron micrograph (SEM) photos show that ultrafine wool powder around 2 μm in diameter can be produced from fiber around 25 μm in the diameter, and most of the powder is in the form of needles. The powder can be widely applied in new biomedical material development and cosmetic products. Thermal analysis of thermogravimetry (TG) and differential scanning calorimetry (DSC) show that the temperature for moisture evaporation in the powder was elevated to around 150°C from the control wool fiber, which was around 120°C. As the powder particle size decreases, the temperature corresponding to the crystal cleavage and the destruction of the crosslinkages increased, which is perhaps mostly due to the new crosslinks and new crystal that were produced during powder processing. The temperature for the liquefaction was also elevated and the relative TG results show that the last residue of the powder after 600°C is higher than that of the control sample. The thermal results show that as the powder particle size decreases, the thermal stability increases slightly. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2372–2376, 2003
Epidemiologic analysis of maternal factors and amniotic band defects
Authors: Werler Martha M. , Louik Carol , Mitchell Allen A. 
Published: January 2003

AbstractBACKGROUNDThe group of defects identified as amniotic bands includes amnion rupture sequence (ARS) and body wall complex (BWC). Little is known about risk factors for either ARS or BWC, except that maternal age has been shown to affect risk inversely.METHODSThe present analysis used data collected from 1976 to 1998 as part of an ongoing case control study of birth defects in the metropolitan areas of Boston, Philadelphia, and Toronto. There were 73 cases with ARS and 11 cases with BWC. ARS cases were further subdivided according to affected structures: there were 53 with only limbs affected (ARS‐L) and 20 with nonlimb defects with or without limb defects (ARS‐NL). The control group comprised 12,227 subjects with other major malformations. Mothers were interviewed within 6 months of delivery about demographic, reproductive, medical, and behavioral factors.RESULTSMultivariate adjusted odds ratios for BWC were increased more than threefold for maternal age < 25 years and maternal education < 12 years, but neither estimate was statistically significant. Corresponding estimates for ARS‐L and ARS‐NL ranged from 1.3 to 1.5 and also were not statistically significant. Cases were less likely to be white non‐Hispanic than controls and the odds ratio for ARS‐NL excluded the null. The multivariate adjusted odds ratio (MVOR) for unplanned pregnancy and BWC was 1.9 (95% confidence interval, 0.5–6.7) compared to 1.2 and 1.0 for ARS‐L and ARS‐NL, respectively. Neither parity nor maternal smoking was associated with any case group. The MVORs for first trimester acetaminophen use in relation to ARS‐L and ARS‐NL risks were 2.1 (1.1–3.9) and 3.4 (1.1–10.3), respectively. Such use was less common among BWC cases (MVOR was 0.4; 0.1–1.4).CONCLUSIONSRisk estimates tended to be similar for ARS‐L and ARS‐NL cases but different for BWC cases, suggesting different etiologies. These data suggest that young maternal age, low maternal education, unplanned pregnancy, and non‐white/non‐Hispanic race/ethnicity might increase the risk of BWC in offspring. Increased risks for acetaminophen use should be interpreted with caution because they may be confounded by indication for use. Birth Defects Research (Part A) 67:68–72, 2003. © 2003 Wiley‐Liss, Inc.
A phylogenetic hypothesis for the origin of hiccough
Authors: Straus C. , Vasilakos K. , Wilson R. J. A. , Oshima T. , Zelter M. , Derenne J‐Ph. , Similowski T. , Whitelaw W. A. 
Published: January 2003

AbstractThe occurrence of hiccoughs (hiccups) is very widespread and yet their neuronal origin and physiological significance are still unresolved. Several hypotheses have been proposed. Here we consider a phylogenetic perspective, starting from the concept that the ventilatory central pattern generator of lower vertebrates provides the base upon which central pattern generators of higher vertebrates develop. Hiccoughs are characterized by glottal closure during inspiration and by early development in relation to lung ventilation. They are inhibited when the concentration of inhaled CO2 is increased and they can be abolished by the drug baclofen (an agonist of the GABAB receptor). These properties are shared by ventilatory motor patterns of lower vertebrates, leading to the hypothesis that hiccough is the expression of archaic motor patterns and particularly the motor pattern of gill ventilation in bimodal breathers such as most frogs. A circuit that can generate hiccoughs may persist in mammals because it has permitted the development of pattern generators for other useful functions of the pharynx and chest wall muscles, such as suckling or eupneic breathing. BioEssays 25:182–188, 2003. © 2003 Wiley Periodicals, Inc.
The CRP/MLP/TLP family of LIM domain proteins: Acting by connecting
Authors: Weiskirchen Ralf , Günther Kalle 
Published: January 2003

AbstractIn vertebrates, members of the cysteine‐rich protein (CRP) family are characterized by the presence of two LIM domains linked to short glycine‐rich repeats. These proteins mediate protein–protein interactions and are of fundamental importance for cell differentiation, cytoskeletal remodeling, and transcriptional regulation. To date, a vast amount of information about vertebrate CRPs has become available, including their biological functions, interacting partners, and three‐dimensional structures. Compatible with a molecular adapter role, structural data reveal that the LIM domains within these proteins represent completely independent folded units bridged by flexible linker regions. The physiological roles for individual CRPs was determined by targeted gene disruption analysis and by identification of common and specific binding partners by means of yeast and mammalian two‐hybrid screens. Several CRP‐like LIM domain proteins with close structural and sequence similarity were identified in arthropods, protozoas and plants, supporting the notion that this subset of LIM domain proteins has been highly conserved over the span of evolution thereby emphasizing the importance of their function. BioEssays 25:152–162, 2003. © 2003 Wiley Periodicals, Inc.