bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of scientific evidence of risks and benefits in determining risk management policies for medications
Authors: Andrews Elizabeth , Dombeck Michael 
Published: September 2004

AbstractRecent changes in the regulatory environment have called attention to the need for and potential benefits of greater and more detailed evidence to inform decisions based on the risk–benefit profile of medications. Nevertheless, access to potentially beneficial therapies continues to be impeded by a lack of sufficient information that could help optimize benefits and minimize risks of treatments for patients. Over‐reliance on pre‐marketing clinical trials and the FDA's spontaneous reporting adverse event system to support regulatory decisions has sustained an information void. Clinical trials are the gold standard for demonstrating efficacy, but they cannot fully predict safety when drugs are used in the real world. Spontaneous reporting can identify new signals, but cannot quantify those signals or place them in appropriate clinical context. In the face of new safety signals, absence of better information on how medications are used and how they perform in the real world setting, regulators are often limited to either continuing drug marketing without significant changes or withdrawing a medication from the market. Experience shows that information collected proactively, to better understand the background risks associated with the underlying disease and to better quantify the product risks, can influence these decisions to include a wider range of options regarding a product's availability, labeling and additional risk management strategies. This article presents several case studies of medications, including those in which insufficient data were available to address important safety signals and decisions were made to withdraw products, as well as those in which epidemiologic data were available to provide reassurance of product safety and allow continued product use, even though some may be marketed with additional risk management programs. More extensive and earlier epidemiologic assessment of risks and benefits of new products will create a new standard of evidence for industry and regulators and is likely to result in more effective and balanced regulatory actions, thereby affording better care for patients. Copyright © 2003 John Wiley & Sons, Ltd.
Dimerization mechanisms of heterocyclic carbenes
Authors: Graham David C. , Cavell Kingsley J. , Yates Brian F. 
Published: September 2004

AbstractThe dimerization reactions of a series of heterocyclic carbenes based on the 1,3‐dimethylimidazol‐2‐ylidene template were studied extensively using molecular orbital calculations. The carbenes studied were the 1,3‐XY five‐membered ring heterocyclic carbenes with all 10 possible combinations of X,Y = NCH3, PCH3, O and S. Two different mechanisms for dimerization were studied: a direct carbene plus carbene dimerization reaction and a proton‐catalysed dimerization. The parent carbene with XY = NN is found to be kinetically and thermodynamically stable under both mechanisms, whereas XY = NS is predicted to be kinetically stable under aprotic conditions. All remaining carbenes were predicted to be not particularly stable towards dimerization. Indirect schemes for calculating the stability of carbenes towards dimerization were found to give good estimates of the enthalpy of dimerization, but do not take into account the activation barriers. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis of core‐shell poly(divinylbenzene) microspheres via reversible addition fragmentation chain transfer graft polymerization of styrene
Authors: Barner Leonie , Li Chao'En , Hao Xiaojuan , Stenzel Martina H. , Barner‐Kowollik Christopher , Davis Thomas P. 
Published: September 2004

AbstractStyrene has been grafted from crosslinked poly(divinylbenzene) core microspheres by both reversible addition fragmentation chain transfer (RAFT) polymerization and conventional free radical polymerization. The core microspheres were prepared by precipitation polymerization. Crosslinked poly(DVB) core microspheres containing double bonds on the particle surface can be used directly to graft polymers from the surface by RAFT without prior modification of the core microspheres. The RAFT agent 1‐phenylethyl dithiobenzoate (PEDB) was used: Particle sizes increased from 2 μm up to 3.06 μm, and the particle weight increased by up to 6.5%. PEDB controls the particle weight gain, the particle volume, and the molecular weight of the soluble polymer. PEDB was also used to synthesize core poly(DVB) RAFT microspheres that contain residual RAFT end groups on the surface and within the particle. Styrene was subsequently grafted from the surface of these core poly(DVB) RAFT microspheres. The generated microspheres were characterized by 1H‐NMR spectroscopy, focused ion beam (FIB) milling, Coulter particle sizing, and size exclusion chromatography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5067–5076, 2004
Selectivity in anionic and cationic ring‐opening polymerizations of tetramethyl‐1‐(3′‐trifluoromethylphenyl)‐1‐phenylcyclotrisiloxane and tetramethyl‐1‐[3′,5′‐bis(trifluoromethyl)phenyl]‐1‐phenylcyclotrisiloxane
Authors: Gädda Thomas M. , Nelson Allison K. , Weber William P. 
Published: September 2004

AbstractAnionic and cationic ring‐opening polymerizations of two novel cyclotrisiloxanes, tetramethyl‐1‐(3′‐trifluoromethylphenyl)‐1‐phenylcyclotrisiloxane (I) and tetramethyl‐1‐[3′,5′‐bis(trifluoromethyl)phenyl]‐1‐phenylcyclotrisiloxane (II), are reported. Anionic ring‐opening polymerization of I or II leads to copolymers with highly regular microstructures. Copolymers obtained by cationic polymerizations of I or II, initiated by triflic acid, have less regular microstructures characteristic of chemoselective polymerization processes. The composition and microstructure of copolymers have been characterized by 1H and 29Si‐NMR, the molecular weight distributions by GPC, and the thermal properties by DSC and TGA. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5235–5243, 2004
Oxygen permeability in blends of a vinyl alcohol/ethylene copolymer and a metallocenic ethylene/1‐octene copolymer
Authors: Laguna M. F. , Cerrada M. L. , Benavente R. , Pérez E. 
Published: September 2004

AbstractThis work describes the preparation, characterization, and evaluation of the oxygen permeability of blends based on a polyolefin synthesized with a metallocene catalyst (ethylene/1‐octene copolymer) and a vinyl alcohol/ethylene copolymer in an attempt to establish the corresponding relationships between the composition, morphology, and transport properties to design materials with optimized and enhanced agricultural and food packaging performances. Moreover, microhardness measurements have been used to analyze the mechanical response of these blends and to obtain information about the dispersion of the two immiscible components within the blends. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3766–3774, 2004
A Grand Canonical Monte Carlo Study of Adsorption and Capillary Phenomena in Nanopores of Various Morphologies and Topologies: Testing the BET and BJH Characterization Methods
Authors: Coasne Benoit , Gubbins Keith E. , Pellenq Roland J.‐M. 
Published: September 2004

AbstractWe report a Grand Canonical Monte Carlo simulation study of Ar adsorption at 77 K in silica nanopores having various morphologies/topologies. Both the morphological and topological disorders are shown to significantly affect the capillary condensation phenomenon. In the case of an ellipsoidal pore, we observe that the filling mechanism is similar to that of a cylindrical pore having the same section area but with a lower condensation pressure. We show that the adsorption/desorption hysteresis loop is asymmetrical for the pore with constrictions while it is symmetrical for the regular cylindrical pore. Moreover, the Ar adsorption isotherm for the constricted pore reproduces the main features of that for the fully disordered Vycor‐like porous matrix. The results for the different pore geometries (having no direct interface with the gas reservoir) indicate that the desorption occurs through cavitation at a pressure driven by the smallest void size. We also consider the validity of the BET and BJH methods for the different porous matrices. Except for the Vycor‐like matrix, the BET surface assessed from Ar adsorption isotherm at 77 K always significantly overestimates the intrinsic surface of the pore (even for a planar surface). The disagreement between the BET surface and the geometrical surface is found to increase as the confinement increases (cylindrical pore) and/or the shape of the pore becomes asymmetrical (ellipsoidal pore). Interestingly, the best agreement between the BET and the geometrical surface is found in the case of the pore with a constriction, i.e. a system that exhibits a surface with both negative and positive curvature regions. This idea is supported by the results for the Vycor‐like matrix, which has a distorted surface (many negative curvature regions combined with positive curvature regions): for this disordered porous matrix, the BET surface is found to underestimate the intrinsic surface. Finally, we show that the pore size determined using the BJH method always underestimates the pore size, in agreement with previous experimental and simulation studies.
Peptides containing 4‐amino‐1,2‐dithiolane‐4‐carboxylic acid (Adt): conformation of Boc‐Adt‐Adt‐NHMe and NH ⃛S interactions
Authors: Morera Enrico , Nalli Marianna , Mollica Adriano , Paglialunga Paradisi Mario , Aschi Massimiliano , Gavuzzo Enrico , Mazza Fernando , Lucente Gino 
Published: September 2004

AbstractTo study the conformational preferences induced by the insertion of the 4‐amino‐1,2‐dithiolane‐4‐carboxylic acid (Adt) residue into a peptide backbone, the achiral N‐protected dipeptide methylamide Boc‐Adt‐Adt‐NHMe (1) was synthesized and its crystal state and solution conformation studied and compared with that exhibited by its carba‐analogue Boc‐Ac5c‐Ac5c‐NHMe containing two residues of 1‐aminocyclopentane‐1‐carboxylic acid (Ac5c). Compound 1 in the crystal adopts a type‐III β‐turn conformation and an analogous structure is that preferred in chloroform solution as established by 1H‐NMR and NOE information. In the crystal packing three different Adt rings form a cavity and the involved sulphur atoms give rise to unusual multiple interactions with one NH group. The chemical nature of these intermolecular and intramolecular main‐chain ⃛side‐chain NH ⃛S interactions are discussed in terms of quantum chemical calculations. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
Optical and electrical properties of ZnO doped with nitrogen
Authors: Kang Seungmo , Shin Kyoungchul , Prabakar Kandasamy , Lee Chongmu 
Published: September 2004

AbstractUltraviolet (UV) and visible photoluminescence (PL) has been achieved at room temperature from ZnO films deposited on the sapphire substrate by RF‐magnetron sputtering. The electrical and optical properties of as‐deposited and annealed films were investigated as a function of N2O/Ar gas flow ratio. All the ZnO films deposited by sputtering show a typical hexagonal wurtzite crystallographic orientation with a c‐axis perpendicular to the substrate surface. The growth rate decreases with the increase of the gas flow ratio. The high carrier mobility and low resistivity films were prepared at a N2O/Ar gas flow ratio of 0.33. The most intense UV and week blue luminescence was observed for the as‐deposited films. A strong blue luminescence emission due to oxygen vacancies was obtained from the films annealed at 1000 °C. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximate Reliability and Availability Models for High Availability and Fault‐tolerant Systems with Repair
Authors: Bowles John B. , Dobbins J. Gregory 
Published: September 2004

AbstractSystems designed for high availability and fault tolerance are often configured as a series combination of redundant subsystems. When a unit of a subsystem fails, the system remains operational while the failed unit is repaired; however, if too many units in a subsystem fail concurrently, the system fails. Under conditions usually met in practical situations, we show that the reliability and availability of such systems can be accurately modeled by representing each redundant subsystem with a constant, ‘effective’ failure rate equal to the inverse of the subsystem mean‐time‐to‐failure (MTTF). The approximation model is surprisingly accurate, with an error on the order of the square of the ratio mean‐time‐to‐repair to mean‐time‐to‐failure (MTTR/MTTF), and it has wide applicability for commercial, high‐availability and fault‐tolerant computer systems. The effective subsystem failure rates can be used to: (1) evaluate the system and subsystem reliability and availability; (2) estimate the system MTTF; and (3) provide a basis for the iterative analysis of large complex systems. Some observations from renewal theory suggest that the approximate models can be used even when the unit failure rates are not constant and when the redundant units are not homogeneous. Copyright © 2004 John Wiley & Sons, Ltd.
Confined systems and the modified virial theorem from semiclassical considerations
Authors: Mukhopadhyay S. , Bhattacharyya K. 
Published: September 2004

AbstractWe show that two simple semiclassical strategies, one based on the Wilson–Sommerfeld rule and the other on the uncertainty principle, yield the exact modified form of the virial theorem for confined systems. An alternative, easier quantum mechanical route to arrive at this result is also sketched. Pilot calculations on confined oscillators reveal decisive trends. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Method development for the quantitation of ABT‐578 in rabbit artery tissue by 96‐well liquid‐liquid extraction and liquid chromatography/tandem mass spectrometric detection
Authors: Ji Qin C. , Zhang Jun , Rodila Ramona , Watson Pamela , El‐Shourbagy Tawakol 
Published: September 2004

AbstractQuantitative determination of drug concentrations in tissue samples can provide critical information for drug metabolism, kinetics, and toxicity evaluations. For analysis of tissue samples using liquid chromatography/tandem mass spectrometric (LC/MS/MS) detection, homogenization is a critical step in achieving good assay performance. Assay performance can be closely evaluated by spiking the drug directly into tissue samples prior to homogenization. It is especially important to include this assay evaluation for the analysis of artery tissue samples because artery tissue is very elastic, making it quite a challenge to develop an effective procedure for homogenization. An LC/MS/MS assay in 96‐well format using liquid‐liquid extraction was developed for analyzing ABT‐578 in rabbit artery samples. Tissue quality control samples were prepared by spiking ABT‐578 stock solutions directly into the tissue before homogenization. The usage of the tissue control samples gives a thorough evaluation of the sample preparation process that includes both homogenization and sample extraction. A 20% blood in saline solution was used as a homogenization solution. Calibration standards were made by spiking ABT‐578 into rabbit whole blood. Blood quality control samples were also prepared by spiking ABT‐578 into rabbit whole blood. These blood QC samples were used to confirm the validity of the calibration curve. A lower limit of quantitation of 0.050 ng/mL was achieved. The linear dynamic range of blood standards was from 0.050–30.3 ng/mL with the correlation coefficient (r) ranging from 0.9969–0.9996. Overall %CV was between 1.3 and 7.0%, and analytical recovery was between 98.2 and 105.8% for blood QC samples. The %CVs for tissue QC samples were between 6.7 and 13.0%, and analytical recovery after correction was between 93.5 and 114.3%. Copyright © 2004 John Wiley & Sons, Ltd.
Atmospheric‐pressure Penning ionization mass spectrometry
Authors: Hiraoka Kenzo , Fujimaki Susumu , Kambara Shizuka , Furuya Hiroko , Okazaki Shigemitsu 
Published: September 2004

AbstractA preliminary study on the atmospheric‐pressure Penning ionization (APPeI) of gaseous organic compounds with Ar* has been made. The metastable argon atoms (Ar*: 11.55 eV for 3P2 and 11.72 eV for 3P0) were generated by the negative‐mode corona discharge of atmospheric‐pressure argon gas. By applying a high positive voltage (+500 to +1000 V) to the stainless steel capillary for the sample introduction (0.1 mm i.d., 0.3 mm o.d.), strong ion signals could be obtained. The ions formed were sampled through an orifice into the vacuum and mass‐analyzed by an orthogonal time‐of‐flight mass spectrometer. The major ions formed by APPeI are found to be molecular‐related ions for alkanes, aromatics, and oxygen‐containing compounds. Because only the molecules with ionization energies less than the internal energy of Ar* are ionized, the present method will be a selective and highly sensitive interface for gas chromatography/mass spectrometry. Copyright © 2004 John Wiley & Sons, Ltd.
Development of a gas chromatography/ion trap mass spectrometry based method for the quantification of polybrominated diphenyl ethers and polychlorinated biphenyls in adipose tissue
Authors: Naert Caroline , Saeger Sarah De , Van Peteghem Carlos 
Published: September 2004

AbstractA combined gas chromatographic mass spectrometric (GC/MS/MS) method for the determination of seven polybrominated diphenyl ethers (PBDEs) and seven marker polychlorinated biphenyls (PCBs) in adipose tissue has been developed. Adipose tissue was melted and filtered through anhydrous sodium sulphate to obtain pure fat. Clean‐up was performed using a glass column containing acidified silica, deactivated alumina and anhydrous sodium sulphate. Polybrominated biphenyl (PBB) 155 and Mirex were added as internal standards for PBDEs and PCBs, respectively. Injection standards, PBB 103 and PCB 143, for PBDEs and PCBs, respectively, were added before analysis with GC/MS/MS. The developed GC/MS/MS method has the advantage of being more selective than single MS methods because matrix effects are largely eliminated. Validation of this method was conducted according to Commission Decision 2002/657/EC. Decision limits for PBDEs and PCBs ranged from 0.06–0.15 ng g−1 and from 0.35–1.22 ng g−1, respectively. Detection capabilities were all between 0.23–0.55 ng g−1 for PBDEs and between 0.98–2.29 ng g−1 for PCBs. Precision, recovery, bias and selectivity were tested, with satisfactory results. Copyright © 2004 John Wiley & Sons, Ltd.
Formation of a geometric pattern with a mobile wireless sensor network
Authors: Lee Justin , Venkatesh Svetha , Kumar Mohan 
Published: September 2004

AbstractMobile wireless sensor networks (MWSNs)will enable information systems to gather detailed information about the environment on an unprecedented scale. These self‐organizing, distributed networks of sensors, processors, and actuators that are capable of movement have a broad range of potential applications, including military reconnaissance, surveillance, planetary exploration, and geophysical mapping. In many of the foreseen applications, the MWSN will need toforma geometric pattern without assistance from the user. In military reconnaissance, for example, the nodes will be dropped onto the battlefield from a plane and land at random positions. The nodes will be expected to arrange themselves into a predetermined formation in order to perform a specific task. Thus, we present algorithms for forming a line, circle, and regular polygon from a given set of random positions. The algorithms are distributed and use no communication between the nodes to minimize energy consumption. Unlike past studies of geometric problems where algorithms are either tested in simulations where each node has global knowledge of all the other nodes or implemented on a small number of robots, the robustness of our algorithms has been studied with simulations that model the sensor system in detail. The simulations demonstrate that the algorithms are robust against random errors in the sensors and actuators. © 2004 Wiley Periodicals, Inc.
Optimal path planning of mobile robots for sample collection
Authors: Cardema J. C. , Wang P. K. C. , Rodriguez G. 
Published: September 2004

AbstractIn this paper, the problem of path planning for sample collection using single or multiple mobile robots such as Mars rovers is formulated as a mathematical optimization problem involving a performance metric based on the scientific values of the collected rock and soil samples. The posed optimization problem is NP‐hard and more complex than the well‐known Traveling Salesman Problem. Algorithms are proposed for obtaining near‐optimal solutions for both single and multiple robots. Their application is illustrated using real Mars surface data. The dependence of the optimal performance on the number of mobile robots is studied numerically. © 2004 Wiley Periodicals, Inc.
Versuche an Verbindungen für Glaskonstruktionen
Authors: Stutzki Christian , Vande Zande Brian J. , Stahl Douglas 
Published: September 2004

AbstractDieser Beitrag beschreibt einige Versuchsreihen zur Bestimmung der Tragfähigkeit von Verbindungen im konstruktiven Glasbau. Zwei Typen von Verbindungen werden beschrieben, Reibverbindungen und Lochleibungsverbindungen, und die Ergebnisse der Versuche werden dargestellt und diskutiert. Das Ziel der hier beschriebenen Versuche ist, im Sinne von Pilotversuchen einige Daten für die Bemessung von Verbindungen mit Glasbauteilen zu erhalten, um Berechnungen und Annahmen über diese Verbindungen zu verifizieren. Außerdem bringen diese Versuche eine Reihe wichtiger Erkenntnisse, vor allem über notwendige Qualitätskontrollen bei der Anwendung solcher Anschlüsse in der Praxis.
Experimental evaluation of the tolerance for control‐flow test criteria
Authors: Kapoor Kalpesh , Bowen Jonathan P. 
Published: September 2004

AbstractFault‐detection effectiveness of coverage criteria has remained one of the controversial issues in recent years. In order to detect a fault, a test set must execute the faulty statement, cause infection of the data state and then propagate the faulty data state to bring about a failure. This paper sheds some light on the earlier contradictory results by investigating the infection aspect of coverage criteria.For a given test criterion, the number of test sets satisfying the criterion may be very large, with varying fault‐detection effectiveness. In a recent work the measure of variation in effectiveness of a test criterion was defined as ‘tolerance’. This paper presents an experimental evaluation of tolerance for control‐flow test criteria by exhaustive test set generation, wherever possible. The approach used here is complementary to earlier empirical studies that adopted analysis of some test sets using random selection techniques. Four industrially used control‐flow testing criteria, Condition Coverage (CC), Decision Condition Coverage (DCC), Full Predicate Coverage (FPC) and Modified Condition Decision Coverage (MCDC) have been analysed against four types of faults. A new test criterion, Reinforced Condition Decision Coverage (RCDC), is also analysed and compared. Copyright © 2004 John Wiley & Sons, Ltd.