bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incipient weathering rind development on introduced machine‐polished granite discs in an Arctic alpine environment, northern Scandinavia
Authors: Dixon John C. , Campbell Sean W. , Thorn Colin E. , Darmody Robert G. 
Published: September 2005

AbstractWeathering rinds, zones of alteration on the exterior surfaces of rock outcrops and coarse unconsolidated surficial debris are widely used by geomorphologists and Quaternary geologists as indicators of the relative age of landforms and landscapes. Additionally they provide unique insights into the earliest stages of rock and mineral weathering, yet the origin of these alteration zones is relatively poorly understood. This lack of understanding applies especially to the initial stages of rind formation. The study reported in this paper has two principal objectives. The first is to use lightly polished granite discs inserted in soil profiles under several different plant communities in an Arctic alpine environment for a period of four or five years to investigate the nature of incipient weathering rind development. The second is to investigate the factors responsible for spatial variability in the nature and rates of rind formation.Incipient weathering rind development on the outer edges of the granite discs is observable and measurable over a period of time as short as four years in the mild Arctic alpine environment of Swedish Lapland. The earliest stages of rind development involve the development of a porous structure consisting of a combination of pits and fractures which have been solutionally enlarged and modified. Solution appears to be preferentially concentrated on the surfaces of feldspars and, to a lesser extent, quartz. In addition, iron oxides are present along grain boundaries and in grain interiors and are interpreted to have been derived from the oxidation of ferromagnesian minerals. Spatial variability in weathering rind development appears to be particularly driven by differences in moisture but is not related to soil pH. Copyright © 2005 John Wiley & Sons, Ltd.
A learning rule for place fields in a cortical model: Theta phase precession as a network effect
Authors: Scarpetta Silvia , Marinaro Maria 
Published: September 2005

AbstractWe show that a model of the hippocampus introduced recently by Scarpetta et al. (2002, Neural Computation 14(10):2371–2396) explains the theta phase precession phenomena. In our model, the theta phase precession comes out as a consequence of the associative‐memory‐like network dynamics, i.e., the network's ability to imprint and recall oscillatory patterns, coded both by phases and amplitudes of oscillation. The learning rule used to imprint the oscillatory states is a natural generalization of that used for static patterns in the Hopfield model, and is based on the spike‐time‐dependent synaptic plasticity, experimentally observed.In agreement with experimental findings, the place cells' activity appears at consistently earlier phases of subsequent cycles of the ongoing theta rhythm during a pass through the place field, while the oscillation amplitude of the place cells' firing rate increases as the animal approaches the center of the place field and decreases as the animal leaves the center. The total phase precession of the place cell is lower than 360°, in agreement with experiments. As the animal enters a receptive field, the place cells' activity comes slightly less than 180° after the phase of maximal pyramidal cell population activity, in agreement with the findings of Skaggs et al. (1996, Hippocampus 6:149–172). Our model predicts that the theta phase is much better correlated with location than with time spent in the receptive field. Finally, in agreement with the recent experimental findings of Zugaro et al. (2005, Nature Neuroscience 9(1):67–71), our model predicts that theta phase precession persists after transient intrahippocampal perturbation. © 2005 Wiley‐Liss, Inc.
Silica sol‐gel monolithic materials and their use in a variety of applications
Authors: Kato Masaru , Sakai‐Kato Kumiko , Toyo'oka Toshimasa 
Published: September 2005

AbstractSol‐gel technology was first discovered in the late 1800s, but it was not until the early 1970s that renewed interest in the technique was generated, when monolithic inorganic gels were formed at low temperature. In this review, we introduce the sol‐gel reaction and the properties of the gel matrix in the first half and the applications of the matrix in the latter half.
Relationship between damaged fraction and reflected spectra of denaturing tissues
Authors: Yoshimura Hiroyuki , Viator John A. , Jacques Steven L. 
Published: September 2005

AbstractBackground and ObjectivesDuring thermal therapy of tissue, such as induced by microwave heating, the initiation of denaturation should be monitored for proper thermal dosage. Additionally, denaturation should be confined to the pathologic volume, while preserving surrounding healthy tissue. The relationship between the damaged fraction and reflected spectra of denaturing tissues was investigated for a variation of the temperature of the tissues.Study Design/Materials and MethodsDenaturation of muscle, liver, and milk was studied in vitro by measuring the temperature‐varying reflectance spectrum as heating occurs. A high‐resolution fiber optic spectrometer was used to measure the reflectance changes. Temperature was monitored using a thermocouple embedded within the tissue along the side of the optical fiber probe.ResultsThe values of average free energy to initiate denaturation in muscle and liver at about 60°C were 94.8 and 96.3 kJ/mole, respectively. The reflectance spectra increased in amplitude for muscle and liver, and the peak shifted from approximately 700 to 720 nm in accordance with the damage fraction of tissue. The reflectance spectrum for milk was essentially unchanged.ConclusionsSpectral changes from heated muscle and liver reflect denaturation of proteins contained therein. The spectral information at 800 nm can be used to determine the average free energy for the initiation of denaturation. Lasers Surg. Med. © 2005 Wiley‐Liss, Inc.
Effect of partial melting on the crystallization kinetics of nylon‐1212
Authors: Song Jianbin , Chen Qingyong , Ren Minqiao , Sun Xiaohong , Zhang Huiliang , Zhang Hongfang , Mo Zhishen 
Published: September 2005

AbstractThe isothermal and nonisothermal crystallization kinetics of partially melted nylon‐1212 was investigated with differential scanning calorimetry. Because of partial melting, the pre‐existing crystals changed the crystallization mechanism and had a strong effect on the crystallization process. The Avrami exponent and interfacial free energy of the chain‐folded surface of partially melted nylon‐1212 were higher than those of completely melted nylon‐1212. The work of chain folding was determined to be 5.9 kcal/mol. The activation energy of the isothermal crystallization process was determined to be 399.1 kJ/mol, far higher than that of complete melting. The crystallization rate coefficient and Jeziorny analysis indicated that the ability of nonisothermal crystallization for partially melted nylon‐1212 was enhanced. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3222–3230, 2005
Soy‐oil‐based segmented polyurethanes
Authors: Petrović Zoran S. , Cevallos Maria J. , Javni Ivan , Schaefer Dale W. , Justice Ryan 
Published: September 2005

AbstractSegmented polyurethanes were prepared from soy polyol, diphenyl methane diisocyanate (MDI), and ethylene glycol or butane diol as chain extenders. Samples were prepared with true hard‐segment concentrations (HSC) of about 0, 10, and 40%. Both the soft MDI–polyol and hard MDI/diol segments are glassy at room temperature. These samples were also crosslinked through the polyfunctional polyol soft segment. Partial crystallinity and phase separation were detected in samples with 40% HSC, on the basis of DSC data. Small‐angle X‐ray scattering shows the existence of phase separation with domain sizes of about 10 nm in the 40% HSC samples, but not in the others. The distribution of domain sizes is considerably broader for the ethylene‐glycol extended system compared with that for the butane‐diol case. Although the presence of hard segments lowers the crosslink density, samples with higher HSC had higher glass transition temperatures, higher strengths, higher moduli, lower swelling, lower elongation at break, and lower impact strengths. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3178–3190, 2005
Electrospinning of polyurethane/organically modified montmorillonite nanocomposites
Authors: Hong Ji Hye , Jeong Eun Hwan , Lee Han Sup , Baik Du Hyun , Seo Seung Won , Youk Ji Ho 
Published: September 2005

AbstractPolyurethane/organically modified montmorillonite (PU/O‐MMT) nanocomposites were electrospun and the effect of O‐MMT on the morphology and physical properties of the PU/O‐MMT nanofiber mats were investigated for the first time. The average diameters of the PU/O‐MMT nanofibers were ranged from 150 to 410 nm. The conductivities of the PU/O‐MMT solutions were linearly increased with increasing the content of O‐MMT, which caused a decrease in the average diameters of the PU/O‐MMT nanofibers. The as‐electrospun PU and PU/O‐MMT nanofibers were not microphase separated. The exfoliated MMT layers were well distributed within the PU/O‐MMT nanofibers and oriented along the fiber axis. When the PU/O‐MMT nanofibers were annealed, the exfoliated MMT layers hindered the microphase separation of the PU. The electrospinning of PU/O‐MMT nanocomposites resulted in PU nanofiber mats with improved Young's modulus and tensile strength. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3171–3177, 2005
Understanding the effect of skin formation on the removal of solvents from semicrystalline polymers
Authors: Wong Sim‐Siong , Altinkaya Sacide Alsoy , Mallapragada Surya K. 
Published: September 2005

AbstractThe effect of glassy skin formation on the drying of semicrystalline polymers was investigated with a comprehensive mathematical model developed for multicomponent systems. Polymers with high glass‐transition temperatures can become rubbery at room temperature under the influence of solvents. As the solvents are removed from the polymer, a glassy skin can form and continue to develop. The model takes into account the effects of diffusion‐induced polymer crystallization as well as glassy–rubbery transitions on the overall solvent content and polymer crystallinity. A Vrentas–Duda free‐volume‐based diffusion scheme and crystallization kinetics were used in our model. The polymer–solvent system chosen was a poly(vinyl alcohol) (PVA)–water–methanol system. The drying kinetics of PVA films were obtained by gravimetric methods with swollen films with known water/methanol concentrations. The overall drying behaviors of the polymer system determined by our model and experimental methods were compared and found to match well. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3191–3204, 2005
Crystal structure of a new class of glutathione transferase from the model human hookworm nematode Heligmosomoides polygyrus
Authors: Schuller David J. , Liu Qun , Kriksunov Irina A. , Campbell Alison M. , Barrett John , Brophy Peter M. , Hao Quan 
Published: September 2005

AbstractThe crystal structure of GST Nu2‐2 (HpolGSTN2‐2) from the model hookworm nematode Heligmosomoides polygyrus has been solved by the molecular replacement method and refined to a resolution of 1.71 Å, providing the first structural data from a class of nematode‐specific GSTs. By structural alignment with two Sigma class GSTs, glutathione could be rationally docked into the G‐site of the enzyme. By comparing with all mammalian GST classes, a novel, long, and deep cleft was identified at the H‐site, providing a potential site for ligand binding. This new GST class may support the establishment of infection parasitic nematodes by passively neutralizing chemical toxins derived from host environment. The structure serves as a starting point for structure‐based drug/inhibitor design that would aim to selectively disrupt nematode chemical defenses. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Estimation of prevalence and incidence based on occurrence of health‐related events
Authors: Støvring Henrik , Vach Werner 
Published: September 2005

AbstractA new method for estimating incidence and prevalence is developed, which only requires observation of occurrence of health‐related events within a given time window. Occurrence data are often easy to collect but estimating incidence and prevalence of a disease from such data is non‐trivial, since the true disease status is not directly observed for all at the beginning of the study period. Our method for overcoming this problem is based on an idea first presented in ‘The waiting time distribution as a graphical approach to epidemiologic measures of drug utilization’ (Epidemiology 1997; 8:666–670). Their fundamental idea is to analyse the waiting time from start of the window to the first event of each individual, and we formalize this by establishing a parametric likelihood which allows ordinary maximum likelihood analysis and explicit modelling of censoring. The developed method is used to analyse incidence and prevalence of hypertension in a Danish cohort of 70+‐year‐olds. A simulation study on the finite sample properties of the method is reported, which indicates that the method gives a quite robust and cost‐effective alternative to ordinary surveys and follow‐up studies for estimating incidence and prevalence. Copyright © 2005 John Wiley & Sons, Ltd.
Assessing uncertainty in reference intervals via tolerance intervals: application to a mixed model describing HIV infection
Authors: Katki Hormuzd A. , Engels Eric A. , Rosenberg Philip S. 
Published: September 2005

AbstractWe define the reference interval as the range between the 2.5th and 97.5th percentiles of a random variable. We use reference intervals to compare characteristics of a marker of disease progression between affected populations. We use a tolerance interval to assess uncertainty in the reference interval. Unlike the tolerance interval, the estimated reference interval does not contains the true reference interval with specified confidence (or credibility). The tolerance interval is easy to understand, communicate and visualize. We derive estimates of the reference interval and its tolerance interval for markers defined by features of a linear mixed model. Examples considered are reference intervals for time trends in HIV viral load, and CD4 per cent, in HIV‐infected haemophiliac children and homosexual men. We estimate the intervals with likelihood methods and also develop a Bayesian model in which the parameters are estimated via Markov‐chain Monte Carlo. The Bayesian formulation naturally overcomes some important limitations of the likelihood model. Published in 2005 by John Wiley & Sons, Ltd.
Adjusted Kaplan–Meier estimator and log‐rank test with inverse probability of treatment weighting for survival data
Authors: Xie Jun , Liu Chaofeng 
Published: September 2005

AbstractEstimation and group comparison of survival curves are two very common issues in survival analysis. In practice, the Kaplan–Meier estimates of survival functions may be biased due to unbalanced distribution of confounders. Here we develop an adjusted Kaplan–Meier estimator (AKME) to reduce confounding effects using inverse probability of treatment weighting (IPTW). Each observation is weighted by its inverse probability of being in a certain group. The AKME is shown to be a consistent estimate of the survival function, and the variance of the AKME is derived. A weighted log‐rank test is proposed for comparing group differences of survival functions. Simulation studies are used to illustrate the performance of AKME and the weighted log‐rank test. The method proposed here outperforms the Kaplan–Meier estimate, and it does better than or as well as other estimators based on stratification. The AKME and the weighted log‐rank test are applied to two real examples: one is the study of times to reinfection of sexually transmitted diseases, and the other is the primary biliary cirrhosis (PBC) study. Copyright © 2005 John Wiley & Sons, Ltd.
Pulsatile hemodynamic effects of candesartan in patients with chronic heart failure: The CHARM Program
Authors: Mitchell Gary F. , Arnold J. Malcolm O. , Dunlap Mark E. , O'Brien Terrence X. , Marchiori Gordon , Warner Elaine , Granger Christopher B. , Desai Shashank S. , Pfeffer Marc A. 
Published: September 2005

AbstractBackground:Abnormal large artery function and increased pulsatile load are exacerbated by excess angiotensin‐II acting through the AT1 receptor and contribute to the pathogenesis and progression of chronic heart failure (CHF).Aims:To evaluate effects of the AT1 receptor blocker candesartan (N=30) or placebo (N=34) on pulsatile hemodynamics in participants with CHF in the CHARM program.Methods and results:Noninvasive hemodynamics were assessed following 6 and 14 months of treatment and averaged. Using calibrated tonometry and aortic outflow Doppler, characteristic impedance was calculated as the ratio of the change in carotid pressure and aortic flow in early systole. Total arterial compliance was calculated by the diastolic area method. Brachial blood pressure, cardiac output and peripheral resistance did not differ between groups. Lower central pulse pressure in the candesartan group (57±20 vs. 67±17 mmHg, P=0.043) was accompanied by lower characteristic impedance (200±78 vs. 240±74 dyne s/cm5, P=0.039) and higher total arterial compliance (1.87±0.70 vs. 1.47±0.48 ml/mmHg, P=0.008). Similar favorable differences were seen when analyses were stratified for ejection fraction (≤0.40 vs. >0.40) and baseline angiotensin converting enzyme inhibitor use.Conclusions:Candesartan has a favorable effect on large artery function in patients with chronic heart failure.
Measuring body composition in chronic heart failure: A comparison of methods
Authors: Uszko‐Lencer Nicole H.M.K. , Bothmer Francien , van Pol Petra E.J. , Schols Annemie M.W.J. 
Published: September 2005

AbstractAims:Fat‐free mass (FFM) is increasingly recognized as a systemic marker of disease severity in chronic organ failure and is an important target for physiologic and pharmacologic interventions to improve functional status. The aim of this study was therefore to evaluate two clinical methods to assess FFM in patients with chronic heart failure (CHF) using deuterium dilution (DEU) as reference and bromide dilution to assess the ratio between intracellular (ICW) and extracellular water (ECW) as potential confounder.Methods:Body composition was measured with dual‐energy X‐ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and DEU in 22 stable patients from our heart failure outpatient clinic and 24 healthy age matched controls.Results:FFM values measured by DXA and DEU in patients (r=0.92, SEE: 3.1 kg) and controls (r=0.99, SEE: 1.3 kg) were strongly related. In both patients and controls, the inter method difference increased with higher values of FFM (DXA overestimating DEU). The ICW/ECW ratio was within the normal range and comparable between the groups. In patients, a highly significant correlation coefficient was found (r=0.93, SEE 2.1 p=0.01) between total body water (DEU) and height squared/resistance (Ht2/R). On multiple regression next to Ht2/R, body weight was an independent predictor of FFMDEU (r=0.95, SEE 2.5 kg, p<0.001; TBWdeu=0.528 Ht2/R+(0.182 weight)+8.277).Conclusion:DXA and DEU are appropriate and interchangeable laboratory methods for assessment of FFM in clinically stable heart failure patients, however, overestimation of FFMDXA should be considered. BIA is a suitable clinical alternative for diagnostic purposes.
Heart failure and sleep apnoea: To sleep perchance to dream
Authors: Ferreira Susana , Winck João , Bettencourt Paulo , Rocha‐Goncalves Francico 
Published: September 2005

AbstractHeart failure and sleep apnoea are major health problems with an increasingly recognized association; evidence suggests that sleep apnoea may play a role in the progression of heart failure. However, confounding factors such as obesity, hypertension and coronary heart disease make this relationship uncertain and an independent correlation remains unproven.Diagnosis of sleep apnoea is suboptimal, as it is often asymptomatic and polysomnography is expensive and time‐consuming. A simple and reliable screening protocol is required. All heart failure patients should be considered to be at high risk of sleep apnoea, as this association might be linked to adverse outcome. Continuous positive airway pressure has shown some beneficial effects, but long‐term outcome and improvement in survival remains to be demonstrated.Despite recent advances in the understanding of the complex relationship between heart failure and sleep apnoea, there are a number of areas requiring further investigation, which may have important implications for the management and prognosis of a significant number of patients.
Benefits of coronary revascularisation in diabetic and non‐diabetic patients with ischaemic cardiomyopathy: Role of myocardial viability
Authors: Rizzello Vittoria , Poldermans Don , Biagini Elena , Schinkel Arend F.L. , Boersma Eric , Elhendy Abdou , Sozzi Fabiola B. , Maat Alexander , Roelandt Jos R.T.C. , Bax Jeroen J. 
Published: September 2005

AbstractBackground:Diabetes mellitus in patients with coronary artery disease is associated with poor outcome. In this study, the relation between myocardial viability, diabetes, coronary revascularisation and outcome was evaluated.Methods:129 patients (31 diabetic, 98 non‐diabetic) with ischaemic cardiomyopathy underwent dobutamine stress echocardiography to assess myocardial viability. Patients with ≥4 viable segments were defined as viable and patients with <<4 viable segments as nonviable. Left ventricular ejection fraction (LVEF) was assessed before and 9–12 months post‐revascularisation. At the same time‐points, LV volumes were measured to evaluate LV remodelling. Finally, cardiac events were noted during 5‐year follow‐up.Results:The extent of viable myocardium was comparable between diabetic and non‐diabetic patients. After revascularisation, LVEF increased ≥5% in 44% of diabetic and in 40% of non‐diabetic patients. LVEF only improved in patients with viable myocardium. Ongoing LV remodelling occurred in 36% and 35% of diabetic and non‐diabetic patients respectively, and was related to non‐viability, whereas viability protected against ongoing LV remodelling, both in diabetic and non‐diabetic patients. Viability was the only predictor of survival after revascularisation.Conclusions:Diabetic, viable patients with ischaemic LV dysfunction exhibit improvement in LVEF post‐revascularisation with prevention of ongoing LV remodelling, similar to non‐diabetic patients. Myocardial viability was also the only predictor of long‐term outcome.