bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synaptic activity modifies the levels of dorsal and cactus at the neuromuscular junction of drosophila
Authors: Bolatto Carmen , Chifflet Silvia , Megighian Aram , Cantera Rafael 
Published: January 2003

AbstractThe Drosophila Rel transcription factor Dorsal and its inhibitor Cactus participate in a signal transduction pathway involved in several biologic processes, including embryonic pattern formation, immunity, and muscle development. In contrast with embryonic muscle, where Dorsal is reportedly absent, this protein and Cactus accumulates in the neuromuscular junctions in the muscle of both larvae and adults. The phenotype of homozygous dorsal mutant larvae suggested that Dorsal and Cactus maybe necessary for normal function and maintenance of the neuromuscular system. Here we investigate if these proteins can respond to synaptic activity. Using larval body wall preparations and antibodies specific for Dorsal or Cactus we show that the amount of these proteins at the neuromuscular junction is substantially decreased after electrical stimulation of the nerves or incubation in glutamate, the principal transmitter in this type of synapse. The specificity of the response was tested with a glutamate receptor antagonist (argiotoxin 636). Because the effect can be reproduced using a calcium ionophore (ionomycin treatment) as well as blocked by the inhibition of the muscle ryanodine receptor (tetracaine treatment), the involvement of calcium in this process seems likely. We also observed that the inhibition of the calcium dependent protein phosphatase calcineurin prevents the effect of glutamate on the fluorescence for Dorsal and Cactus, suggesting its participation in a signal transduction cascade that may activate Dorsal in the muscle independently of Toll. Our results are consistent with a novel function of the Rel factor Dorsal in a molecular pathway turned on by neural activity and/or contractile activity. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 525–536, 2003
Teen pregnancy, motherhood, and unprotected sexual activity
Authors: Koniak‐Griffin Deborah , Lesser Janna , Uman Gwen , Nyamathi Adeline 
Published: January 2003

AbstractThe sexual behaviors and attitudes toward condom use of adolescent mothers (N = 572) from ethnic minority groups were examined. Constructs from social cognitive theory (SCT), the theory of reasoned action (TRA), and the theory of planned behavior (TPB; e.g., intentions to use condoms, self‐efficacy, outcome expectancies) were measured with questionnaires. Measures of AIDS and condom‐use knowledge and selected psychosocial, behavioral, and demographic variables were included. Many adolescents reported early onset of sexual activity, multiple lifetime sexual partners, substance use, and childhood sexual or physical abuse. Only 18% stated a condom was used at last intercourse. Using hierarchical regression analysis, 13% of the variance for factors associated with unprotected sex was accounted for by TRA constructs. Other variables contributed an additional 17% of the variance. Unprotected sex was associated with behavioral intentions to use condoms, pregnancy, having a steady partner, more frequent church service attendance, and ever having anal sex. Findings support the urgent need for broad‐based HIV prevention efforts for adolescent mothers that build on theoretical concepts and address the realities of their lives. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:4–19, 2003
Effectiveness of a pilot project of discharge planning in Taiwan
Authors: Dai Yu‐Tzu , Chang Ying , Hsieh Chang‐Yao , Tai Tong‐Yuan 
Published: January 2003

AbstractThe purpose of this study was to examine the effects of a nurse‐designed discharge‐planning project in a teaching hospital in Taiwan. A before‐and‐after quasi‐experimental design was used. Craniotomy (n = 112) and stroke (n = 171) patients were recruited and divided into control and intervention groups. Outcome indicators included length of hospital stay, change in activities of daily living (ADL), rate of nursing home placement, rate of unplanned readmission, and level of satisfaction. In the stroke sample length of hospital stay was shorter in the intervention group than in the control group. In the craniotomy sample unplanned readmission was less frequent in the intervention group than in the control group. No differences were found between the control and intervention groups in other outcome indicators. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:53–63, 2003
Testing the relationship between self‐agency and enactment of health behaviors
Authors: DeSocio Janiece , Kitzman Harriet , Cole Robert 
Published: January 2003

AbstractA theoretical review provides a rationale for examining self‐agency as a developmental foundation underlying processes of self‐regulated change and a potential moderator of intervention effectiveness among participants in a nurse home‐visitation program. Self‐agency is defined as the conceptual understanding of self as an agent capable of shaping motives, behavior, and future possibilities (Damon & Hart, 1991). Availability of a sample of 186 mothers who received nurse home visitation provided an opportunity to test the relationship between participant self‐agency and enactment of targeted health behaviors. Self‐agency items from the Pearlin Mastery Scale (1978) were used to differentiate mothers who endorsed self‐agency from those who did not. Consistent with the theoretical premise, mothers who endorsed self‐agency at an established threshold were significantly more likely to enact health behaviors promoted during nurse visitation. Results provide support for the relationship between the development of self‐agency and enactment of health behaviors targeted by a nurse home‐visitation program. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:20–29, 2003
Molecular weight control of polyacrylamide with sodium formate as a chain‐transfer agent: Characterization via size exclusion chromatography/multi‐angle laser light scattering and determination of chain‐transfer constant
Authors: Fevola Michael J. , Hester Roger D. , McCormick Charles L. 
Published: January 2003

AbstractWe discuss the synthesis and characterization of polyacrylamide (PAM) homopolymers with carefully controlled molecular weights (MWs). PAM was synthesized via free‐radical solution polymerization under conditions that yield highly linear polymer with minimal levels of hydrolysis. The MW of the PAM homopolymers was controlled by the addition of sodium formate (NaOOCH) to the polymerization medium as a conventional chain‐transfer agent. MWs and polydispersity indices (PDIs) were determined via size exclusion chromatography/multi‐angle laser light scattering analysis; for polymerizations carried out to high conversion, PAM MWs ranged from 0.23 to 6.19 × 106 g/mol, with most samples having PDI ≈2.0. Zero‐shear intrinsic viscosities of the polymers were determined via low‐shear viscometry in 0.514 M NaCl at 25 °C. Data derived from the polymer characterization were used to determine the chain‐transfer constant to NaOOCH under the given polymerization conditions and to calculate Mark–Houwink–Sakurada K and a values for PAM in 0.514 M NaCl at 25 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 560–568, 2003
Anionic copolymerization of hexanelactam with functionalized polyisoprene
Authors: Mateva R. , Filyanova R. , Velichkova R. , Gancheva V. 
Published: January 2003

AbstractBlock copolymers of the A‐B‐C‐B‐A type were synthesized for the first time via the activated anionic polymerization of hexanelactam (HL) with Na‐HL as an initiator and macroactivators [or polymeric activators (PACs)] as elastificators for nylon‐6. The PACs were prepared by the functionalization of telechelic hydroxyl‐terminated poly(ethylene oxide)–polyisoprene–poly(ethylene oxide) copolymers with different diisocyanates. Hexamethylene diisocyanate (1,6‐diisocyanatohexane) and isophorone diisocyanate (5‐isocyanate1‐isocyanatomethyl‐1,3,3‐trimetylcyclohexane) were used as functionalizing agents. This article reports on the effects that the various central elastomeric PAC blocks (type, content, and molecular weight) had on the polymerization kinetics and on the structure and molecular weights of the multiblock copolymers obtained. The copolymers were characterized spectroscopically. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 487–496, 2003
Ultraviolet–ultraviolet dual‐cure process based on acrylate oxetane monomers
Authors: El‐ghayoury Abdelkrim , Boukaftane Chouaib , de Ruiter Barteld , van der Linde Rob 
Published: January 2003

AbstractA dual‐cure process consisting of two subsequent ultraviolet‐initiated radical and cationic polymerizations was investigated. The process was studied with two acrylate oxetane monomers, one of them having a spacer between the two polymerizable moieties. It was shown by Fourier transform infrared (FTIR) that the first (radical) step was performed successfully for both systems. As for the second (cationic) step, only the monomer with the spacer was able to polymerize, allowing the crosslinking of the polyacrylic chains generated by the first step. The efficiency of the process was confirmed by differential scanning calorimetry because the glass‐transition temperatures of the cured films were −16 and + 34 °C after the first and second steps, respectively. The dual cure of this system was further analyzed by real‐time FTIR, which showed that 86% of the acrylate and 80% of the oxetane moieties were converted after 20 and 50 s of light exposure, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 469–475, 2003
Synthesis and characterization of sulfonated poly(phthalazinone ether ketone) for proton exchange membrane materials
Authors: Gao Yan , Robertson Gilles P. , Guiver Michael D. , Jian Xigao 
Published: January 2003

AbstractAs a novel class of proton exchange membrane materials for use in fuel cells, sulfonated poly(phthalazinone ether ketone)s (SPPEKs) were prepared by the modification of poly(phthalazinone ether ketone). Sulfonation reactions were conducted at room temperature with mixtures of 95–98% concentrated sulfuric acid and 27–33% fuming sulfuric acid with different acid ratios, and SPPEK was obtained with a degree of sulfonation (DS) in the desired range of 0.6–1.2. The presence of sulfonic acid groups in SPPEK was confirmed by Fourier transform infrared analysis, and the DS and structures were characterized by NMR. The introduction of sulfonic groups into the polymer chains increased the glass‐transition temperature above the decomposition temperature and also led to an overall decrease in the decomposition temperature. Membrane films were cast from SPPEK solutions in N,N‐dimethylacetamide. Water uptakes and swelling ratios of SPPEK membrane films increased with DS, and SPPEKs with DS > 1.23 were water‐soluble at 80 °C. Proton conductivity increased with DS and temperature up to 95 °C, reaching 10−2S/cm. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 497–507, 2003
Monitoring photopolymerization reactions with optical pyrometry
Authors: Falk Benjamin , Vallinas Santiago M. , Crivello James V. 
Published: January 2003

AbstractThis article describes the development of optical pyrometry (OP) as a new analytical technique for the continuous monitoring of the progress of both free‐radical and cationic photopolymerizations. The method is rapid, reproducible, and very easy to implement. A temperature profile of a photopolymerization can be obtained. Preliminary studies have shown that the temperatures of some polymerizing monomers can easily reach temperatures in excess of 250 °C. The effects of the mass and reactivity of the monomer, light intensity, structures, and concentrations of the photoinitiators and monomers as well as the presence or absence of oxygen on various free‐radical and cationic photopolymerizations were examined with this method. Coupling of real‐time infrared spectroscopy with OP provides a convenient method for simultaneously monitoring both the chemical conversion and the temperature of a photopolymerization. This combined technique affords new insights into the effects of temperature‐induced autoacceleration on the course of photopolymerizations. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 579–596, 2003
Local chain‐configuration dependence of the mechanisms of the chemical reaction of poly(vinyl chloride). IX. Novel results on stereoselectivity of chlorination reaction
Authors: Martínez G. , Millán J. , Contreras J. 
Published: January 2003

AbstractA poly(vinyl chloride) (PVC) sample was chlorinated in solution in the presence of 2,2′‐azobisisobutyronitrile and by the fluid‐bed method. The aim was to evaluate the scope of the stereoselectivity of the chlorination reaction. The quantitative microstructural analysis of the residual PVC with a degree of chlorination was followed by 13C NMR spectroscopy. From the evolution of the content of isotactic (mm), heterotactic (mr), and syndiotactic (rr) triads and of mmmm, mmmr, and rmmr isotactic pentads in the unchlorinated parts of the polymer, it was unambiguously inferred that the chlorination reaction proceeds by a stereoselective mechanism in that the mr heterotactic triads are the most reactive structures followed by the isotactic triad at mmmr and rmmr pentads. This conclusion was confirmed on the basis of the Fourier transform infrared results. The results provide valuable information regarding the effect of tacticity and related local conformations in the chemical reactions of PVC. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 508–519, 2003
Polystyrene latices containing dodecanamide‐modified poly(propyleneimine) dendrimers
Authors: Xu Zushun , Ford Warren T. 
Published: January 2003

AbstractPolymerization of styrene in aqueous dispersions of the dodecanamide derivative of poly(propyleneimine) dendrimer DAB‐dendr‐(NH2)64 and sodium dodecyl sulfate (SDS) produced stable latices. With initial SDS concentrations of 10 mM or less, molar ratios of SDS to dendrimer end groups ranging from 2.3:1 to 9.5:1, and less than 10 wt % of SDS relative to styrene, the polystyrene latices had diameters of 30–60 nm and coefficients of variation of diameters of less than 10% when measured by transmission electron microscopy. Higher concentrations of SDS gave more polydisperse latices. The polystyrene latices formed with SDS and the dodecanamide‐modified dendrimer were almost the same size and polydispersity as those formed with SDS and the parent primary amine dendrimer DAB‐dendr‐(NH2)64. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 597–605, 2003
Preparation of supported yttrium alkoxides as catalysts for the polymerization of lactones and oxirane
Authors: Martin E. , Dubois Ph. , Jerome R. 
Published: January 2003

AbstractTwo methods have been reported that allow yttrium alkoxides to be supported on porous silica and to be used afterward as heterogeneous catalysts in the ring‐opening polymerization of oxirane and ϵ‐caprolactone. In the two methods, [tris(hexamethyldisilyl)‐amide]yttrium {Y[N(SiMe3)2]3} is the metal alkoxide precursor. It is directly reacted with the silanol groups of the support, in the first method, and this is followed by alcoholysis of the unreacted amide groups. The flexibility of this method seems to be limited because the grafting density and the structure of the grafted Y alkoxide (less than one alkoxide by metal) are independent of the experimental conditions. In the second method, Y[N(SiMe3)2]3 is first reacted with 1 or 2 equiv of alcohol with the formation of the mixed Y alkoxide/amide. The amide functions are used to attach Y to the support. This method is free from side reactions, quite reproducible, and well suited to support one type of active species (monoalkoxide or dialkoxide). Preliminary experiments with ϵ‐caprolactone polymerization have confirmed the activity of the supported Y alkoxide, whatever preparation method is used. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 569–578, 2003
Theoretical study of the thermolysis reaction of β‐hydroxynitriles in the gas phase
Authors: Chamorro Eduardo , Quijano Jairo , Notario Rafael , Sánchez Claudia , León Luis A. , Chuchani Gabriel 
Published: January 2003

AbstractThe gas‐phase thermal decomposition of 3‐hydroxypropionitrile, 3‐hydroxybutyronitrile, and 3‐hydroxy‐3‐methylbutyronitrile has been studied at the MP2/6‐31G(d) level of theory at 683.15 K and 0.06 atm. Results based both in energy and structure data seem to indicate a favorable route of decomposition via a six‐membered cyclic transition state (similar to those suggested for thermal decomposition of other related compounds, such as β‐hydroxyketones, β‐hydroxyalkenes, and β‐hydroxyalkynes) rather than a four‐membered cyclic transition state or even a quasiheterolytic pathway. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Computation of quantum system by second‐order matrix symplectic scheme
Authors: Hanwei Yi , Zhongyuan Zhou , Peizhu Ding , Yu L. H. 
Published: January 2003

AbstractIn this article the work of Vazquez and Zhang Meiqing et al. has been developed in such a way that it can be used to calculate time evolution of quantum system. In Heisenberg picture, operator symplectic schemes have been changed into matrix symplectic schemes by use of the expansion method, the matrix schemes satisfy equal time commutation relation (ETCR) in the matrix form. The second‐order matrix scheme is used to calculate one‐dimensional nonlinear harmonic oscillator. The calculated result is compared with results obtained by Runge–Kutta scheme. Calculated results show that results computed by ETCR‐preserving and symplectic scheme is consistent with physics theory. It also shows that it is rational and effective as well as reliable to use ETCR‐preserving symplectic scheme to calculate time evolution of quantum system in Heisenberg picture. It is proved that second‐order symplectic scheme has more computing accuracy than does first‐order symplectic scheme. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Modeling the dynamics of human energy regulation and its implications for obesity treatment
Authors: Abdel‐Hamid Tarek K. 
Published: January 2003

AbstractObesity has reached epidemic proportions in the United States and is threatening to become a global epidemic. Even more concerning, the incidence of overweight continues to increase. The health consequences and economic costs to individuals and to society are considerable. Obesity is associated with many serious health complications, including coronary heart disease, type 2 diabetes mellitus, hypertension, selected cancers, and musculoskeletal disorders. In the U.S., direct and indirect medical costs attributable to obesity are estimated to approach $100 billion yearly. Obesity develops when a chronic imbalance exists between energy intake, in the form of food and drink, and energy expenditure. To date, the emphasis of treatment has been on the energy intake side of the energy balance equation. This, in part, is because it has been difficult to demonstrate the efficacy of exercise as a treatment strategy. This paper attempts to demonstrate the utility of system dynamics modeling to study and gain insight into the physiology related to weight gain and loss. A simulation model is presented that integrates nutrition, metabolism, hormonal regulation, body composition, and physical activity. These processes are typically fragmented between many different disciplines and conceptual frameworks. This work seeks to bring these ideas together highlighting the interdependence of the various aspects of the complex human weight regulation system. The model was used as an experimentation vehicle to investigate the impacts of physical activity on body weight and composition. The results replicate the “mix” of results reported in the literature, as well as providing causal explanation for their variability. In one experiment, weight loss from a moderate level of daily exercise was comparable to the loss from dieting (when both produced equivalent energy deficits). Perhaps of greater significance, the exercise intervention protected against the loss of fat‐free mass, which occurs when weight loss is achieved through dieting alone, and thus promoted favorable changes in body composition. In a second experiment, exercise regimens of moderate to high level of intensity proved counter‐productive as weight‐reducing strategies for an obese sedentary subject. This was due to the limited energy reserves (specifically, muscle glycogen) available to such individuals. However, when the diet was changed from a balanced composition to one that was highly loaded with carbohydrates, it became possible to sustain the intense exercise regimen over the experimental period, and achieve a significant drop in body weight. The results underscore the significant interaction effects between diet composition and physical activity, and emphasize the critical role that diet composition can have in exercise‐based treatment interventions. Copyright © 2002 John Wiley & Sons, Ltd.
Critical systems thinking as a way to manage knowledge
Authors: Gao Fei , Li Meng , Nakamori Yoshiteru 
Published: January 2003

AbstractThis paper is the first to introduce critical systems thinking into the present study of knowledge and its management. Our preliminary study showed two things about critical systems thinking. First, it provides comprehensive and creative insight into tackling the increasing complexity of human knowledge and knowledge management processes through the organic connection and division of knowledge systems. Second, it encourages the critical use of available methodologies in a coherent way to cope with corresponding subsystems or processes, which breaks down the complexity into convenient units. Based on critical systems thinking, we divided knowledge into two aspects: static substance knowledge and dynamic process knowledge. This division not only provides a concise theoretical framework but also allows knowledge managers and workers to clearly understand the gravity of their work and to selectively utilize well‐established methodologies in the practice of knowledge‐related activities. This paper serves as an introduction to an application of critical system thinking and total systems intervention in diversified human knowledge topics. Copyright © 2002 John Wiley & Sons, Ltd.
A proposed taxonomy of management systems
Authors: Felix Reto 
Published: January 2003

AbstractManagement systems are part of virtually every organization. However, so far no systematic effort has been made to distinguish different stages in the adaptive process of management systems according to sophistication criteria. By building on existing theories in the areas of systems control, cybernetics, and general systems theory, this paper develops and presents a taxonomy of management systems. It is shown that flowing‐equilibrium (F‐E) management systems can explain systems behavior that cannot be explained by management theory based on cybernetics or double‐loop learning. Copyright © 2002 John Wiley & Sons, Ltd.