bluuebunny/crossref_metadata_2025_split huggingface dataset:
Аспекты численного моделирования процессов разрушения упруго-хрупких тел
Authors: Вильдеман Валерий Эрвинович , Феклистова Евгения Вячеславовна , Мугатаров Артур Ильдарович , Муллахметов Максим Николаевич , Кучуков Артур Марсович 
Published: January 2024

Understanding the nucleation and evolution of microdefects in solid bodies is important to ensure the reliability and safety of critical structures and to identify their strength and deformation resources. In numerical modeling, failure zones can be represented as areas with significantly underestimated rigid characteristics by analogy with the method of variable elastic parameters used in solving the boundary-value problems of the theory of plasticity. However, the formal application of numerical algorithms of plasticity does not always lead to an adequate description of failure processes especially in elastic-brittle bodies. This paper considers some aspects of the numerical simulation of failure processes, such as the calculation of a stress-strain state after reducing the rigidity of finite elements under constant boundary conditions by organizing an appropriate iteration procedure, and the selection of the maximum number of finite elements fractured per iteration, the value of a loading step, and the discretization degree of the computational domain. The influence of the above aspects on the results of failure simulation is illustrated by comparing the numerical solutions to the problem of deformation of the strip made of elastic-brittle material with the edge stress concentrator, which were obtained by different algorithms. The loading diagrams were plotted, and the implementation of the post-critical stage at the macro level was demonstrated. Failure kinetics was analyzed for different variants of implementation of the iterative procedure and at a variable number of elements fractured per iteration. It has been found that, in order to get an accurate description of deformation and failure processes, the automatic selection of a loading step seems to be more reasonable. Analysis has indicated that the discretization degree of the computational domain has a strong impact on the modeling results. This suggests that the finite element size should correspond to a certain strength constant of a material having the dimensions of length.
A Critical Appraisal of Clinical Practice Guidelines for Pharmacological Treatments of Paroxysmal Nocturnal Hemoglobinuria
Authors: Pires Yara Maria da Silva , Deffert Flávia , Humenhuk Thais , Vilela Ana Paula Oliveira , Bonetti Aline de Fátima , Wiens Astrid 
Published: January 2024

Aims: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare chronic disease characterized by complement-mediated hemolysis, thrombosis, and bone marrow failure. This study aims to identify methodological limitations in Clinical Practice Guidelines (CPG) for the treatment of PNH. Thus, we critically evaluate the guidelines, highlighting relevant recommendations supported by high-quality evidence to improve healthcare strategies.
Methodology: A systematic search was carried out in PubMed/MEDLINE, Scopus, Embase, COCHRANE, and TRIP databases. From 1995 initially identified references, 1649 articles underwent title and abstract screening. Twenty-three references were selected for full-text screening. Ultimately, 12 CPGs were included. Four independent reviewers assessed the CPGs’ methodological quality using the instruments “Appraisal of Guidelines for Research and Evaluation II” (AGREE II) and “Recommendation Excellence” (AGREE-REX). Their characteristics, as well as any differences in recommendations, were summarized and compared.
Results: Twelve guidelines published from 2011 to 2022 by Spain, Brazil, Mexico, Israel, Canada, Turkey, Scotland, and the United Kingdom were included. The UK’s and Brazil’s CPGs received the highest scores. Overall, the CPGs scored strongly in the domains of “Scope and Purpose” and “Clarity of Presentation” since they addressed fundamental aspects, such as aim, specific health questions, target population, and language. All guidelines presented deficiencies in the “Editorial Independence” in AGREE II, and “Values and Preferences” in AGREE-REX, demonstrating the need for a careful revision and improvement of future versions.
Conclusion: We found disparities in the methodological quality of the available CPGs. Despite being extremely important, recommendations on adapting treatment to local policies and further updates that include newly approved medications were absent. Approaches that prioritize the engagement of methodologists and multidisciplinary collaborators may also lead to higher quality CPGs for treating PNH.
In vivo and in vitro studies exploring the pharmacokinetic interaction between bosentan, a dual endothelin receptor antagonist, and glyburide
Authors: van Giersbergen Paul L. M. , Treiber Alexander , Clozel Martine , Bodin Frédéric , Dingemanse Jasper 
Published: August 2002

BackgroundIn a clinical trial with patients with chronic heart failure, a higher incidence ofelevated levels of liver transaminases was observed during concomitant treatment with bosentan, a dual endothelin receptor antagonist, and glyburide (INN, glibenclamide), a sulfonylurea‐type antidiabetic drug, than with treatment withbosentan alone. This study was conducted to investigate a possible pharmacokinetic interaction between bosentan and glyburide.MethodsIn a randomized, 2‐way crossover study, 12 healthy volunteers received treatments A and B. Treatment A consisted of 125 mg bosentan twice a day for 10 days plus concomitant 2.5 mg glyburide twice a day on days 6 to 10. Treatment B consisted of 2.5 mg glyburide twice a day for 10 days plus concomitant 125 mg bosentan twice a day on days 6 to 10. Plasma concentrations of bosentan and its metabolites and of glyburide were measured on days 5 and 10 of treatment A and treatment B, respectively.ResultsBosentan reduced the area under the concentration‐versus‐time curve of glyburide approximately 40% (P < .05). Glyburide decreased the area under the concentration‐versus‐time curve of bosentan and its metabolites 20% to 30% (P < .05). Results of in vitro experiments showed that glyburide is metabolized bycytochrome P450 (CYP) 2C9, 2C19, and 3A4. No interaction was observed on the level of serum protein binding.ConclusionsThe plasma levels of both bosentan and glyburide were reduced after concomitant administration. This finding is consistent with a CYP3A4‐inducing potential of both drugs. The observed pharmacodynamic interaction between bosentan and glyburide in patients with chronic heart failure cannot be explained by a pharmacokinetic interaction.Clinical Pharmacology & Therapeutics (2002) 71, 253–262; doi: 10.1067/mcp.2002.122473
What Does Second-Order Vision See in an Image?
Authors: Schofield Andrew J 
Published: August 2002

The human visual system is sensitive to both first-order variations in luminance and second-order variations in local contrast and texture. Although there is some debate about the nature of second-order vision and its relationship to first-order processing, there is now a body of results showing that they are processed separately. However, the amount, and nature, of second-order structure present in the natural environment is unclear. This is an important question because, if natural scenes contain little second-order structure in addition to first-order signals, the notion of a separate second-order system would lack ecological validity. Two models of second-order vision were applied to a number of well-calibrated natural images. Both models consisted of a first stage of oriented spatial filters followed by a rectifying nonlinearity and then a second set of filters. The models differed in terms of the connectivity between first-stage and second-stage filters. Output images taken from the models indicate that natural images do contain useful second-order structure. Specifically, the models reveal variations in texture and features defined by such variations. Areas of high contrast (but not necessarily high luminance) are also highlighted by the models. Second-order structure—as revealed by the models—did not correlate with the first-order profile of the images, suggesting that the two types of image ‘content’ may be statistically independent.
Fundamentals of Magnetorheological Fluid Utilization in High Precision Finishing
Authors: Kordonski W. I. , Golini D. 
Published: August 2002

Magnetorheological finishing (MRF) is an enabling technology that may produce surface accuracy on the order of 30 nm peak to valley (p-v) and surface micro-roughness less than 10 A rms. In MRF, mechanical energy for material removal over the portion of the workpiece surface is generated by the magnetically controlled hydrodynamic flow of a magnetorheological polishing fluid. A fundamental advantage of MRF over existing technologies is that the polishing tool does not wear, since the recirculated fluid is continuously monitored and maintained. Polishing debris and heat are continuously removed. The technique requires no dedicated tooling or special setup. A unique attribute of the MRF process is its determinism that is attained through the use of a well-defined material removal function to eliminate known surface error. The efficiency of material removal and the removal process stability are the crucial factors in MRF. In turn, they are primarily dependent on MR polishing fluid stability. It is shown that the joint use of physicochemical and rheological factors along with specially developed methods of the slurry handling, pumping, and in-line monitoring and maintaining provides a level of MR slurry stability that is quite adequate for high precision finishing. Attention is given to methods of MR slurry property measurements.
The Year in Review: Critical Care Medicine
Authors: Rudis Maria I. , Hoang David Q. 
Published: August 2002

Background: There have been significant recent advances in the pharmacotherapeutic management of critically ill patients. The purpose of this article is to review and discuss the most pertinent published literature in the areas of neurology, cardiovascular diseases, infectious diseases, nephrology, hematology, and gastroenterology as it pertains to critical care in order to provide an update for the critical care practitioner. Methods: We performed a Medline search from July 1999 to December 2000 utilizing terms relating to the pharmacotherapy of the specific aforementioned topics in critical care medicine. We focused on English-language clinical studies performed in adult intensive care unit (ICU) patients. From these articles we selected those that would have a practical impact on drug therapy in the ICU or the development of drug usage guidelines for critically ill patients. Review articles were generally not included. Results: The following topics were found to be either new developments or of potentially significant impact in the management of adult critically ill patients. In the area of neurology, advances were found with respect to optimization of regimens for sedative and neuromuscular blocking agents, validation of sedation scales and tools, and in the treatment of head injury patients. In the cardiovascular diseases, most studies related to the hemodynamic support of septic shock. We focus on developments in fluid resuscitation, optimization of global and regional oxygen transport variables, the repositioning of vasopressor agents, and a return to the use of steroids. Given the high mortality rate associated with the development of acute renal failure in the ICU, there has been a consistent attempt to develop preventative and treatment strategies for these patients, including optimization of antimicrobial dosing methods. Several epidemiological and longitudinal studies document changes in multi-drug antimicrobial resistance patterns. The use of treatment guidelines for antimicrobials in the critically ill improves outcomes in most patients. Significant attention has focused on the characterization of anemia in the ICU and the development of alternative pharmacological strategies in its treatment. Finally, in gastroenterology, the main focus has been the investigation of methods to optimize the delivery of enteral nutrition given its proven benefits in critically ill patients. Conclusions: Significant advances in the areas of neurological, cardiovascular, infectious diseases, renal, hematological, and gastrointestinal issues in the pharmacotherapy of critically ill patients have been published over the course of the past year. Many of these studies have yielded data that may be incorporated into the pharmacotherapeutic management of ICU patients, hence maximizing outcomes.
Significant Drug Interactions in the HIV Patient
Authors: Conry John M. 
Published: August 2002

Current treatment guidelines advocate the use of triple combination antiretroviral therapy for the management of human immunodeficiency virus (HIV) infection with one protease inhibitor (PI) or nonnucleoside reverse transcriptase inhibitor (NNRTI) plus two nucleoside reverse transcriptase inhibitors (NRTIs). Additionally, patients often receive medications for prophylaxis and treatment of opportunistic infections and comorbid illnesses. Polypharmacy with potent medications places the patient with HIV at significant risk of drug interactions. The purpose of this review is to assist clinicians regarding awareness and management of clinically significant drug interactions frequently encountered in the HIV population. Pharmacodynamic and pharmacokinetic interactions are discussed in depth with several tables of significant interactions encountered in the patient with HIV. Certain combinations of NRTIs have antagonistic antiretroviral action (e.g., zidovudine plus stavudine), and thus should be avoided. All of the currently available PIs and delavirdine are cytochrome (CYP) 450 inhibitors and can cause significant inhibition of concomitant drug metabolism. Nevirapine is a CYP 450 inducer and can cause induction of drug metabolism, whereas efavirenz may cause inhibition or induction. Drug-herbal interactions are reviewed, including the decreased concentrations of indinavir following the administration of St. John’s wort. Additionally, the pharmacist’s role as an integral member of the HIV patient care team is discussed.
A Comparison of Natural-Image-Based Models of Simple-Cell Coding
Authors: Willmore Ben , Watters Paul A , Tolhurst David J 
Published: August 2002

Models such as that of Olshausen and Field (O&F, 1997 Vision Research37 3311–3325) and principal components analysis (PCA) have been used to model simple-cell receptive fields, and to try to elucidate the statistical principles underlying visual coding in area V1. They connect the statistical structure of natural images with the statistical structure of the coding used in V1. The O&F model has created particular interest because the basis functions it produces resemble the receptive fields of simple cells. We evaluate these models in terms of their sparseness and dispersal, both of which have been suggested as desirable for efficient visual coding. However, both attributes have been defined ambiguously in the literature, and we have been obliged to formulate specific definitions in order to allow any comparison between models at all. We find that both attributes are strongly affected by any preprocessing (eg spectral pseudo-whitening or a logarithmic transformation) which is often applied to images before they are analysed by PCA or the O&F model. We also find that measures of sparseness are affected by the size of the filters—PCA filters with small receptive fields appear sparser than PCA filters with larger spatial extent. Finally, normalisation of the means and variances of filters influences measures of dispersal. It is necessary to control for all of these factors before making any comparisons between different models. Having taken these factors into account, we find that the code produced by the O&F model is somewhat sparser than the code produced by PCA. However, the difference is rather smaller than might have been expected, and a measure of dispersal is required to distinguish clearly between the two models.
Pharmacokinetics of sertraline in relation to genetic polymorphism of CYP2C19
Authors: Wang Jiu‐Hui , Liu Zhao‐Qian , Wang Wei , Chen Xiao‐Ping , Shu Yan , He Nan , Zhou Hong‐Hao 
Published: August 2002

ObjectiveOur objective was to evaluate the relationship between the disposition of sertraline and the presence of the CYP2C19 gene and to define the contribution of cytochrome P450 2C19 (CYP2C19) to sertraline N‐demethylation.MethodsA single oral 100‐mg dose of sertraline was administered to 6 subjects who were extensive metabolizers and 6 subjects who were poor metabolizers recruited from 77 healthy Chinese volunteers whose genotypes were predetermined by polymerase chain reaction–based amplification, followed by restriction fragment length polymorphism analysis. Phenotypes were determined by use of the omeprazole metabolic rate. The plasma concentrations of sertraline and desmethylsertraline were determined by gas chromatography with electron‐capture detection.ResultsSix poor metabolizers with m1 mutation had area under the plasma concentration versus time curve (AUC0‐∞) values (983.6 ± 199.3 μg · h/L versus 697.6 ± 133.0 μg · h/L; P < .05) and terminal elimination half‐life values of sertraline (35.5 ± 5.6 hours versus 23.5 ± 4.4 hours; P < .01) that were significantly higher than the values in 6 extensive metabolizers who were either homozygous or heterozygous for CYP2C19*1. The oral clearance of sertraline in poor metabolizers (105.3 ± 19.4 L/h) was significantly lower than that of extensive metabolizers (148.4 ± 28.6 L/h). The area under the concentration‐time curve from 0 to 144 hours and the maximum plasma concentration of desmethylsertraline in poor metabolizers were significantly lower than the values of extensive metabolizers (627.6 ± 203.8 μg · h/L versus 972.1 ± 270.3 μg · h/L; P < .05; and 23.6 ± 6.5 nmol/L versus 32.4 ± 8.2 nmol/L; P < .01; respectively).ConclusionsThe polymorphic CYP2C19 appears to be a major enzyme involved in the N‐demethylation of sertraline, and both extensive and poor metabolizers had marked differences in the disposition of sertraline.Clinical Pharmacology & Therapeutics (2001) 70, 42–47; doi: 10.1067/mcp.2001.116513
Cholinergic toxic syndrome by the anticancer drug irinotecan: Acetylcholinesterase does not play a major role
Authors: Blandizzi Corrado , Danesi Romano , De Paolis Barbara , Di Paolo Antonello , Colucci Rocchina , Falcone Alfredo , Del Tacca Mario 
Published: August 2002

BackgroundThe anticancer drug irinotecan induces cholinergic side effects that are currently ascribed to the blockade of acetylcholinesterase. This study investigated (1) the pattern of acetylcholinesterase activity in patients receiving treatment with irinotecan and (2) the relationship between acetylcholinesterase activity and plasma concentrations of irinotecan, 7‐ethyl‐10‐hydroxycamptothecin (SN‐38), and SN‐38 glucuronide (SN‐38G).MethodsTwenty‐five patients with advanced colorectal cancer were treated with 250 mg/m2 irinotecan administered by intravenous infusion for 60 minutes. Blood samples were collected before drug infusion and at 15 minutes and 45 minutes after the start of drug infusion. Blood acetylcholinesterase activity was determined by a colorimetric enzymatic assay, and irinotecan, SN‐38, and SN‐38G concentrations were determined in plasma by HPLC. The in vitro effects of irinotecan and other drugs on human acetylcholinesterase were also assessed.ResultsCompared with basal values, the activity of acetylcholinesterase in blood specimens collected during irinotecan infusion at 15 minutes (−0.76%) and at 45 minutes (−1.50%) showed no changes. No relationships were established between the activity of blood acetylcholinesterase at 15 or 45 minutes and plasma concentrations of irinotecan, SN‐38, or SN‐38G measured at the same time points. In vitro, the activity of acetylcholinesterase was inhibited by 100‐μmol/L irinotecan (−24.8%) and markedly reduced by 1‐μmol/L physostigmine (−86.7%), whereas neither SN‐38 nor camptothecin had an effect.ConclusionsAlthough the use of erythrocyte acetylcholinesterase as a surrogate marker of acetylcholinesterase activity in the nervous system has not been firmly established, our findings do not support the hypothesis that the toxic cholinergic syndrome associated with irinotecan treatment depends on acetylcholinesterase blockade.Clinical Pharmacology & Therapeutics (2002) 71, 263–271; doi: 10.1067/mcp.2002.121909
Failure Modes of Foams: The Influence of Orientation of Voids
Authors: Theocaris Pericles S. , Sokolis Dimitrios P. 
Published: August 2002

An experimental investigation is undertaken in this paper for the assessment of the failure behavior of a series of polyurethane foams of variable specific density. All foamy materials examined here were acknowledged as transversely isotropic materials, whose axis of symmetry is, however, the weak axis of the medium. Simple uniaxial tension and compression tests were executed, and the experimental data were introduced into the elliptic paraboloid failure surface criterion. This condition was utilized for the comparison of the failure loci, associated with primary failure, of the polyurethane foams of different porosities. As a result, it is shown that, when the specific density of the foamy solids is raised, the shape, position and alignment of their failure loci intersections by the principal stress planes, as well as by the principal diagonal planes, is adjusted significantly. In addition to this fact, their degree of anisotropy is augmented; however, it is noted that the totality of the foamy materials tested exhibit solely compression-strong failure characteristics. Next, the influence of the voids’orientation on the failure modes of foams is investigated, by evaluating the variation of the essential parameters, required for the precise definition of the failure loci of the weak-axis polyurethanes, with respect to their specific density. And, further, by contrasting this variation with the respective one for the strong-axis foams encountered in previous studies of the senior author (Theocaris, 1992a,b; 1998). Hence, a comprehensive comparison of the failure behavior of foams, which display a weak and strong-axis of symmetry, is succeeded, revealing their similarities, but most importantly, their peculiarities and idiosyncrasies. Finally, a numerical analysis is disclosed as a means of determining the failure characteristics of mixed foams, that consist of both strong and weak-axis polyurethane materials of different specific densities. Accordingly, the effect of variation of the relative proportions and the specific densities of the constituent foamy phases on the characteristic parameters, designating the failure loci of mixed foams, is studied, offering interesting results concerning the modes of failure of such foams.
Damage Tolerance and Repair of GFRP Warships
Authors: Elliott D. M. , Trask R. S. 
Published: August 2002

The United Kingdom has operated glass-fiber-reinforced plastic (GFRP) minesweeper vessels since the early 1970s. Under typical operating conditions they may sustain minor impact damage, leading to delaminations within the hull shell and debonding of the stiffener frames. Such damage is costly to repair, and hence there has been a move towards cost reduction through better understanding of the structural behavior of typical defects under the loading conditions present within the structure. This approach, using damage tolerance techniques, has led to a relaxation in the requirement for repair, and consequently the number of repairs has been substantially reduced. In addition, advance techniques have been developed using resin infusion technology for the re-attachment of debonded stiffener frames. The structural element tests used to validate the damage tolerance philosophy will be examined and the resin-infusion repair method explained using a case study detailing its first successful application.