bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐resolution XPS study of crosslinking and segregation phenomena in hexamethoxymethyl melamine–polyester resins
Authors: Perruchot Christian , Abel Marie‐Laure , Watts John F. , Lowe Chris , Maxted James T. , White Richard G. 
Published: October 2002

AbstractThermally initiated reactions that occur between a polyester resin and a hexamethoxymethyl melamine crosslinker, together with the segregation phenomenon of minor components such as flow agents, have been investigated by high‐resolution XPS. High‐resolution monochromated XPS C 1s spectra can be peak‐fitted by taking into account all functionalities of the respective components of the formulation. Uncured and cured coatings based on a mixture of hexamethoxymethyl melamine and a polyester resin exhibit minor differences in terms of surface composition and in the high‐resolution C 1s peak fitting. Examination of both the elemental and chemical surface compositions clearly demonstrates that the use of flow agents in the formulation leads to their preferential segregation towards the air/film interface. Copyright © 2002 John Wiley & Sons, Ltd.
Surface property modification of a polyethylene powder by coupling fluidized bed and far cold remote nitrogen plasma technologies
Authors: Vivien C. , Wartelle C. , Mutel B. , Grimblot J. 
Published: October 2002

AbstractA far cold remote nitrogen (FCRN) plasma, eventually doped with oxygen, was used to modify the surface properties of a polyethylene (PE) powder. The process associates both remote plasma and fluidized bed technologies. Two applications are described. The first one, for increasing the hydrophilic character of PE, only requires a single plasma treatment. The second application involves FCRN plasma polymerization of 1,1,3,3‐tetramethyldisiloxane mixed with oxygen to obtain a hydrophobic film on the powder surface. The wettability evolution of the PE powder was followed by contact angle measurements (Washburn method) versus different experimental parameters. The surface modifications induced by the treatments were studied by XPS. Copyright © 2002 John Wiley & Sons, Ltd.
Formation of cubic boron nitride films by r.f. magnetron sputtering
Authors: Jiang Liudi , Fitzgerald A. G. , Rose M. J. , Lousa A. , Gimeno S. 
Published: October 2002

AbstractBoron nitride thin films have been deposited on silicon by tuned substrate r.f. magnetron sputtering from a sintered hexagonal BN target using a mixture of Ar (90%) and N2 (10%) as sputtering gas at different substrate bias conditions. The deposited films have been characterized by Fourier transform infrared spectroscopy (FTIR) and x‐ray photoelectron spectroscopy (XPS). Both FTIR and XPS results show that the formation of nearly pure cubic boron nitride films were achieved when the films were deposited by a two‐step process at a lower substrate bias voltage after the initial formation of the cubic boron nitride layer. Also, as indicated by FTIR measurements, this two‐step process caused a reduction of the residual stress in the deposited films and no re‐sputtering effects were present during the cubic BN growing process. Copyright © 2002 John Wiley & Sons, Ltd.
Performance of weighted estimating equations for longitudinal binary data with drop‐outs missing at random
Authors: Preisser John S. , Lohman Kurt K. , Rathouz Paul J. 
Published: October 2002

AbstractThe generalized estimating equations (GEE) approach is commonly used to model incomplete longitudinal binary data. When drop‐outs are missing at random through dependence on observed responses (MAR), GEE may give biased parameter estimates in the model for the marginal means. A weighted estimating equations approach gives consistent estimation under MAR when the drop‐out mechanism is correctly specified. In this approach, observations or person‐visits are weighted inversely proportional to their probability of being observed. Using a simulation study, we compare the performance of unweighted and weighted GEE in models for time‐specific means of a repeated binary response with MAR drop‐outs. Weighted GEE resulted in smaller finite sample bias than GEE. However, when the drop‐out model was misspecified, weighted GEE sometimes performed worse than GEE. Weighted GEE with observation‐level weights gave more efficient estimates than a weighted GEE procedure with cluster‐level weights. Copyright © 2002 John Wiley & Sons, Ltd.
Ethical issues in clinical trials in developing countries
Authors: Brody Baruch A. 
Published: October 2002

AbstractThe vertical transmission trials conducted in a variety of developing countries by researchers from more developed countries illustrate a variety of crucial ethical issues. Three crucial issues are the injustice of the use of placebo control groups, the coerciveness of the offer to participate, and the exploitation of Third World countries. This paper examines each of these issues separately. It develops a new standard for when such control groups are acceptable. It concludes that the issue of coercive offers is not well founded. It also concludes that concerns about exploitation are better addressed by assurances about the future care of the subjects in the trial than by assurances of availability of the drugs in the country in general. Copyright © 2002 John Wiley & Sons, Ltd.
Combined endpoints: can we use them?
Authors: Lubsen Jacobus , Kirwan Bridget‐Anne 
Published: October 2002

AbstractAnalysing specific non‐fatal events in isolation may lead to spurious conclusions about efficacy unless the events considered are combined with all‐cause mortality. The use of combined endpoints has therefore become widespread, at least in cardiovascular disease trials. Combining all‐cause mortality with selected non‐fatal events is useful because event‐free survival, an important criterion in therapy evaluation, is addressed in this manner. In many clinical trials, symptoms, signs or paraclinical measures (for example, blood pressure, exercise duration, quality of life scores) are used as endpoints. If the patient died before the endpoint was measured, or it was otherwise not possible to perform follow‐up assessments as planned, the effect of treatment on these endpoints may be distorted if the patients concerned are ignored in the analysis. Examples are given of how distortion can be avoided by including all patients randomized in an analysis that uses a ranked combined endpoint based both on clinical events and on paraclinical measures. A distinction is made between a pseudo intention‐to‐treat analysis that disregards study medication status at the time of endpoint assessment but is confined to patients with data, and a true intention‐to‐treat analysis that takes into account all patients randomized based on a ranked combined endpoint. Copyright © 2002 John Wiley & Sons, Ltd.
Sense of personal control, stress and coping style: a cross‐cultural study
Authors: O'Connor Daryl B. , Shimizu Mikiko 
Published: October 2002

AbstractThe relationship between personal control, stress, and psychological health is well documented, but these associations may represent a Western bias—a sense of personal control may only reflect individualistic Western values—distinct from Eastern collectivist values. This study examined the relationship between sense of personal control, stress, coping and psychological distress in a Japanese and British sample. Japanese respondents were found to have a significantly lower sense of personal control, report higher perceived stress and negative mood compared to British respondents. Cultural differences in coping styles were also identified: Japanese respondents were found to employ significantly more emotion‐focused strategies (i.e. escape–avoidance and positive reappraisal) when faced with stressful encounters compared to the British sample. No differences were found for problem‐focused coping. Sense of personal control was only associated with stress, psychological distress and coping style in the British sample—providing support for the notion of a Western bias. The results are discussed within the context of cross‐cultural stress and coping research and implications for future investigations are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Is low cortisol release an indicator of positive health?
Authors: Lindfors Petra , Lundberg Ulf 
Published: October 2002

AbstractCompared to the knowledge of physiological processes associated with stress, ill‐health, and disease, the understanding of physiological processes associated with positive psychological functioning is lagging behind. The present study aimed to examine the relationships between psychological well‐being and physiological indicators, including blood pressure, catecholamines, and cortisol. Initial questionnaires concerning demographic information, work characteristics (decision authority, job demands, and skill discretion), physical symptoms, nicotine use, and Ryff's Psychological Well‐Being scales (RPWB) which cover self‐acceptance, environmental mastery, positive relations with others, personal growth, purpose in life and autonomy, were completed by a group of highly educated white‐collar workers. Subsequent assessments of blood pressure, urinary catecholamines, and salivary cortisol were performed during two separate workdays. Analyses of data from 12 women and 11 men revealed that individuals with high psychological well‐being had significantly lower total cortisol output than individuals with low psychological well‐being (p < 0.01), while no significant differences emerged for blood pressure and catecholamines. Further, individuals with high psychological well‐being had significantly lower levels of general (p < 0.01) as well as musculoskeletal symptoms (p < 0.01). In conclusion, the findings suggest a link between positive psychological functioning and lowered cortisol release. Copyright © 2002 John Wiley & Sons, Ltd.
Acute and delayed effects of phencyclidine upon mRNA levels of markers of glutamatergic and GABAergic neurotransmitter function in the rat brain
Authors: Cochran Susan M. , Fujimura Masatake , Morris Brian J. , Pratt Judith A. 
Published: October 2002

AbstractGlutamatergic and GABAergic neurotransmitter systems exist in equilibrium to maintain “normal” brain function. Evidence is accumulating that disturbance of this equilibrium may be one of the key factors giving rise to schizophrenia. While there is widespread evidence that the psychotomimetic phencyclidine (PCP) induces schizophrenia‐related symptoms, it is not clear how this dramatic effect is mediated. This study was designed to investigate acute and delayed effects of PCP on the mRNA expression of a range of markers of neuronal function associated with the glutamatergic and GABAergic systems within the rat brain. The mRNA levels of CaMKIIα, an enzyme which is located within the postsynaptic density and phosphorylates AMPA receptors, remained unaltered both 2 and 24 h posttreatment. Homer 1a, an immediate early gene associated with metabotropic glutamate receptors within the postsynaptic density, displayed region‐specific differential changes within the prefrontal, primary auditory, and retrosplenial cortices 2 and 24 h posttreatment. Parvalbumin, a calcium‐binding protein located within a subpopulation of GABAergic interneurones, displayed altered mRNA levels within the reticular nucleus of the thalamus at 2 and 24 h posttreatment and the substantia nigra pars reticulata 24 h posttreatment only. These phencyclidine‐induced changes in mRNA expression were not accompanied by any changes in hsp‐70 mRNA levels, a marker of NMDA antagonist‐induced reversible neurotoxicity. These results indicate that the glutamatergic (group I metabotropic glutamate receptors) and GABAergic (parvalbumin‐containing interneurones) neurotransmitter systems are differentially modulated in a region‐ and time‐dependent manner by exposure to phencyclidine. Synapse 46:206–214, 2002. © 2002 Wiley‐Liss, Inc.
Formulating measures of effectiveness
Authors: Sproles Noel 
Published: October 2002

AbstractAlthough Measures of Effectiveness (MOEs) are an important element of the Systems Engineering process, they have yet to gain acceptance from practitioners. This is caused not only by the confusion surrounding their definition but also the perceived difficulty in formulating appropriate MOEs. This paper builds on previously published papers that address the issue of the definition of MOEs and the distinction to be drawn with Measures of Performance. Following a brief review of this existing work, a process for formulating MOEs is suggested and explained. This is supplemented by several examples from everyday life and from historical references. The examples build on the issues raised in the discussion of the process and provide practical examples to reinforce what has been previously discussed. © 2002 Commonwealth of Australia. Exclusive worldwide publication rights in the article have been transferred to Wiley Periodicals, Inc. Syst Eng 5, 253–263, 2002
Biologically Important Reactions Catalyzed by RNA Molecules
Authors: Ikeda Yutaka , Taira Kazunari 
Published: October 2002

AbstractThe last few years have seen a considerable increase in our understanding of catalysis by naturally occurring RNA molecules called ribozymes. The biological functions of RNA molecules depend upon their adoption of appropriate three‐dimensional structures. The structure of RNA has a very important electrostatic component, which results from the presence of charged phosphodiester bonds. Metal ions are usually required to stabilize the folded structures and/or catalysis. Some ribozymes utilize metal ions as catalysts, whereas others use the ions to maintain appropriate three‐dimensional structures. In the latter case, the correct folding of the RNA structures can perturb the pKa values of the nucleotide(s) within a catalytic pocket such that they act as general acid/bases catalysts. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 307–318, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10031
Prevention of fumonisin B1‐induced neural tube defects by folic acid
Authors: Sadler T.W. , Merrill Alfred H. , Stevens Victoria L. , Sullards M. Cameron , Wang Elaine , Wang Ping 
Published: October 2002

AbstractBackgroundThe mycotoxin fumonisin B1 (FB1) inhibits sphingolipid synthesis, blocks folate transport, and has been associated with increased incidences of cancer and neural tube defects. Results from reproductive studies in animal models in vivo and in vitro have demonstrated toxicity in some cases, but no specific terata after fumonisin exposure. No information is available about folic acid's potential to protect against this toxicity.MethodsNeurulating mouse embryos were exposed to fumonisin or folinic acid in whole embryo culture and assessed for effects on growth and development.ResultsFumonisin exposure inhibited sphingolipid synthesis, reduced growth, and caused cranial neural tube defects in a dose dependent manner. Supplemental folinic acid ameliorated the effects on growth and development, but not inhibition of sphingolipid synthesis.ConclusionFumonisin has the potential to inhibit embryonic sphingolipid synthesis and to produce embryotoxicity and neural tube defects. Folic acid can reverse some of these effects, supporting results showing that fumonisin disrupts folate receptor function. Teratology 66:169–176, 2002. © 2002 Wiley‐Liss, Inc.
Genome‐wide search of Schizosaccharomyces pombe genes causing overexpression‐mediated cell cycle defects
Authors: Tallada Victor A. , Daga Rafael R. , Palomeque Cristina , Garzón Andrés , Jimenez Juan 
Published: October 2002

AbstractGenetic studies in yeasts enable an in vivo analysis of gene functions required for the cell division cycle (cdc genes) in eukaryotes. In order to characterize new functions involved in cell cycle regulation, we searched for genes causing cell division defects by overexpression in the fission yeast Schizosaccharomyces pombe. By using this dominant genetic strategy, 26 independent clones were isolated from a Sz. pombe cDNA library. The cloned cDNAs were partially sequenced and identified by computer analysis. The 26 clones isolated corresponded to 21 different genes. Among them, six were genes previously characterized in Sz. pombe, 11 were homologues to genes identified and characterized in other organisms, and four represented genes with unknown functions. In addition to known cell cycle regulators encoding inhibitory protein kinases (wee1, pka1) and DNA checkpoint proteins (Pcna, rad24), we have identified genes that are involved in a number of cellular processes. This includes protein synthesis (ribosomal proteins L7, L10, L29, L41, S6, S11, S17 and the PolyA‐Binding Protein PABP), protein degradation (UBI3), nucleolar rRNA expression (fib, imp1, dbp2), cell cytoskeleton (act1) and glycolysis (pfk1). The interference caused in the cell cycle by overexpression of these genes may elucidate novel mechanisms coupling different cellular processes with the control of the cell division. The effect caused by some of them is described in more detail. Copyright © 2002 John Wiley & Sons, Ltd.
Putative xylose and arabinose reductases in Saccharomyces cerevisiae
Authors: Träff K. L. , Jönsson L. J. , Hahn‐Hägerdal B. 
Published: October 2002

AbstractSaccharomyces cerevisiae mutants, in which open reading frames (ORFs) displaying similarity to the aldo‐keto reductase GRE3 gene have been deleted, were investigated regarding their ability to utilize xylose and arabinose. Reduced xylitol formation from D‐xylose in gre3 mutants of S. cerevisiae suggests that Gre3p is the major D‐xylose‐reducing enzyme in S. cerevisiae. Cell extracts from the gre3 deletion mutant showed no detectable xylose reductase activity. Decreased arabitol formation from L‐arabinose indicates that Gre3p, Ypr1p and the protein encoded by YJR096w are the major arabinose reducers in S. cerevisiae. The ypr1 deletion mutant showed the lowest specific L‐arabinose reductase activity in cell extracts, 3.5 mU/mg protein compared with 7.4 mU/mg protein for the parental strain with no deletions, and the lowest rate of arabitol formation in vivo. In another set of S. cerevisiae strains, the same ORFs were overexpressed. Increased xylose and arabinose reductase activity was observed in cell extracts for S. cerevisiae overexpressing the GRE3, YPR1 and YJR096w genes. These results, in combination with those obtained with the deletion mutants, suggest that Gre3p, Ypr1p and the protein encoded by YJR096w are capable of xylose and arabinose reduction in S. cerevisiae. Both the D‐xylose reductase and the L‐arabinose reductase activities exclusively used NADPH as co‐factor. Copyright © 2002 John Wiley & Sons, Ltd.
Protection against exercise‐induced bronchoconstriction by montelukast in aspirin‐sensitive and aspirin‐tolerant patients with asthma
Authors: Mastalerz L. , Gawlewicz‐Mroczka A. ,   E. Nizankowska, Cmiel A. , Szczeklik A. 
Published: October 2002

SummaryBackground Montelukast, a cysteinyl‐leukotriene receptor antagonist, was reported to have a protective effect against exercise‐induced bronchoconstriction (EIB). Aspirin‐induced asthma (AIA) is characterized by overproduction of cysteinyl‐leukotrienes.Objective The aim of the study was to compare the response to exercise and the effect of montelukast on EIB in AIA as compared to aspirin‐tolerant asthma (ATA).Methods A placebo‐controlled, double blind, cross‐over randomized study was performed in 19 AIA and 21 ATA patients with stable asthma. A single dose of montelukast (10 mg) or placebo (PL), was given orally one hour prior to exercise challenge. FEV1 was measured before and 5, 10, 15 min after exercise and then at 15‐minute intervals for 4 h. Urinary LTE4 excretion and blood eosinophil count were measured at baseline, 2 h and 4 h following exercise challenge.Results Positive bronchial response to exercise was observed in 47.5% of all patients studied. Exercise led to almost identical maximal fall in FEV1 in AIA and ATA patients (23.5% ± 6.8% vs. 21.8% ± 12.0%, respectively; P = 0.7). Montelukast, as compared to PL, significantly attenuated EIB in 63.2% of 19 patients with positive exercise test preceded by PL. The mean of maximum fall in FEV1 from the pre‐exercise value was 10.2% ± 13.8 after montelukast as compared to 22.5% ± 10.2 after placebo (P < 0.001). No significant differences between protective effect of montelukast was observed in AIA as compared to ATA patients (P = 0.63, anova). Urinary LTE4 excretion showed no change following exercise, irrespective of the result of the test in all subjects.Conclusion Patients with AIA and ATA react similarly to exercise challenge and obtain similar protection against EIB by montelukast.
Estimation of projection errors in human ocular fundus imaging
Authors: Doelemeyer Arno , Petrig Benno L. 
Published: October 2002

SummaryPhotogrammetric analysis of features in human ocular fundus images is affected by various sources of errors, for example aberrations of the camera and eye optics. Another—usually disregarded—type of distortion arises from projecting the near spherical shape of the fundus onto a planar imaging device. In this paper we quantify such projection errors based on geometrical analysis of the reduced model eye imaged by a pinhole camera. The projection error found near the edge of a 50° fundus image is 24%. In addition, the influence of axial ametropia is investigated for both myopia and hyperopia. The projection errors found in hyperopia are similar to those in emmetropia, but decrease in myopia. Spherical as well as ellipsoidal eye shapes were used in the above calculation and their effect was compared. Our results suggest that the simple spherical eye shape is sufficient for correcting projection distortions within a range of ametropia from −5 to +5 diopters.
Macular pigment optical density measurement: a novel compact instrument
Authors: Beatty Stephen , Koh Hui‐Hiang , Carden David , Murray Ian J. 
Published: October 2002

SummaryA compact device to derive the optical density of human macular pigment (MP) using heterochromatic flicker photometry is described. The validity of the system is assessed by measuring the optical density spectra of MP in 12 healthy subjects and comparing this with well‐established previously published values. The mean spectral absorbance characteristics of MP across subjects corresponds well with accepted values. As reported in other studies, our measurements show a wide variation of MP optical densities between individuals. In our technique within‐subject variability is low; standard deviations are between 0.025 and 0.15 in most cases. The overall optical density of MP ranged from 0.08 to 0.84 with a mean of 0.496 and standard deviation of 0.257 at 460 nm. The stimulus size was 0.95 degrees. The unique feature of the technique is that it allows free viewing (not Maxwellian View) of the stimulus, it can be conducted easily and quickly and does not need frequent re‐calibration.