bluuebunny/crossref_metadata_2025_split huggingface dataset:
Real‐time magnetic resonance with physiologic monitoring for improved scan localization
Authors: Stainsby Jeffrey A. , Sussman Marshall S. , Flexman Molly L. , Wright Graham A. 
Published: March 2005

AbstractImaging of the coronary arteries at diagnostic resolutions is made difficult due to cardiac and respiratory motion during data acquisition. Cardiac gating and respiratory gating or breath holding are effective ways to reduce the effects of motion. The optimal cardiac and respiratory timings vary widely across individuals. This work presents a real‐time magnetic resonance imaging approach with physiologic monitoring that can be used to predict the optimal timings on a subject‐by‐subject basis during a brief real‐time prescan. The feasibility of this approach at determining the optimal cardiac trigger delay and respiratory phase is demonstrated. Magn Reson Med 53:954–959, 2005. © 2005 Wiley‐Liss, Inc.
Mathematical framework for simulating diffusion tensor MR neural fiber bundles
Authors: Leemans A. , Sijbers J. , Verhoye M. , Van der Linden A. , Van Dyck D. 
Published: March 2005

AbstractWhite matter (WM) fiber tractography (i.e., the reconstruction of the 3D architecture of WM fiber pathways) is known to be an important application of diffusion tensor magnetic resonance imaging (DT‐MRI). For the quantitative evaluation of several fiber‐tracking properties, such as accuracy, noise sensitivity, and robustness, synthetic ground‐truth DT‐MRI data are required. Moreover, an accurate simulated phantom is also required for optimization of the user‐defined tractography parameters, and objective comparisons between fiber‐tracking algorithms. Therefore, in this study a mathematical framework for simulating DT‐MRI data, based on the physical properties of WM fiber bundles, is presented. We obtained a model of a WM fiber bundle by parameterizing the various features that characterize this bundle. We then evaluated three different synthetic DT‐MRI models using experimental data in order to test the proposed methodology, and to determine the optimum model and parameter settings for constructing a realistic simulated DT‐MRI phantom. Several examples of how the mathematical framework can be applied to compare fiber‐tracking algorithms are presented. Magn Reson Med 53:944–953, 2005. © 2005 Wiley‐Liss, Inc.
Flip angle calculation for consistent contrast in spoiled gradient echo imaging
Authors: Busse Reed F. 
Published: March 2005

AbstractIn spoiled gradient echo sequences, the T1‐weighting of image contrast is strongly affected by a nonlinear interaction of two sequence parameters, repetition time (TR) and flip angle (α). If α is not properly adjusted to compensate for variation in TR due to changing resolution, bandwidth, or number of slices, any optimization of contrast‐to‐noise may be compromised. Currently, there is no direct way to compare or reproduce the contrast properties of one sequence to another with a different TR. Here, it is demonstrated that for short TRs α may be calculated and automatically adjusted such that relative contrast—the shape of the signal‐versus‐T1 curve—remains consistent and signal scales proportionally to √TR in all tissues. TR is then free to vary to accommodate a range of sequence parameters without impacting relative contrast and the T1‐weighting of one sequence can be compared to, or reproduced in, another study with a different TR. Magn Reson Med 53:977–980, 2005. © 2005 Wiley‐Liss, Inc.
Exchange‐influenced T2ρ contrast in human brain images measured with adiabatic radio frequency pulses
Authors: Michaeli Shalom , Gröhn Heidi , Gröhn Olli , Sorce Dennis J. , Kauppinen Risto , Springer Charles S. , Uğurbil Kâmil , Garwood Michael 
Published: March 2005

AbstractTransverse relaxation in the rotating frame (T2ρ) is the dominant relaxation mechanism during an adiabatic Carr–Purcell (CP) spin‐echo pulse sequence when no delays are used between pulses in the CP train. The exchange‐induced and dipolar interaction contributions (T2ρ,ex and T2ρ,dd) depend on the modulation functions of the adiabatic pulses used. In this work adiabatic pulses having different modulation functions were utilized to generate T2ρ contrast in images of the human occipital lobe at magnetic field of 4 T. T2ρ time constants were measured using an adiabatic CP pulse sequence followed by an imaging readout. For these measurements, adiabatic full passage pulses of the hyperbolic secant HSn (n = 1 or 4) family having significantly different amplitude—and frequency—modulation functions were used with no time delays between pulses. A dynamic averaging (DA) mechanism (e.g., chemical exchange and diffusion in the locally different magnetic susceptibilities) alone was insufficient to fully describe differences in brain tissue water proton T2ρ time constants. Measurements of the apparent relaxation time constants (T) of brain tissue water as a function of the time between centers of pulses (τcp) at 4 and 7 T permitted separation of the DA contribution from that of dipolar relaxation. The methods presented assess T2ρ relaxation influenced by DA in tissue and provide a means to generate T2ρ contrast in MRI. Magn Reson Med 53:823–829, 2005. © 2005 Wiley‐Liss, Inc.
Dynamic autocalibrated parallel imaging using temporal GRAPPA (TGRAPPA)
Authors: Breuer Felix A. , Kellman Peter , Griswold Mark A. , Jakob Peter M. 
Published: March 2005

AbstractCurrent parallel imaging techniques for accelerated imaging require a fully encoded reference data set to estimate the spatial coil sensitivity information needed for reconstruction. In dynamic parallel imaging a time‐interleaved acquisition scheme can be used, which eliminates the need for separately acquiring additional reference data, since the signal from directly adjacent time frames can be merged to build a set of fully encoded full‐resolution reference data for coil calibration. In this work, we demonstrate that a time‐interleaved sampling scheme, in combination with autocalibrated GRAPPA (referred to as TGRAPPA), allows one to easily update the coil weights for the GRAPPA algorithm dynamically, thereby improving the acquisition efficiency. This method may update coil sensitivity estimates frame by frame, thereby tracking changes in relative coil sensitivities that may occur during the data acquisition. Magn Reson Med 53:981–985, 2005. Published 2005 Wiley‐Liss, Inc.
Variability of metabolite yield using STEAM or PRESS sequences in vivo at 3.0 T, illustrated with myo‐inositol
Authors: Kim Hyeonjin , Thompson Richard B. , Hanstock Christopher C. , Allen Peter S. 
Published: March 2005

AbstractUsing as an example the myo‐inositol (mI) band at ∼3.6 ppm in the proton spectrum from brain, an evaluation is presented that highlights the difficulties of quantifying metabolites with strongly coupled spins with either STEAM or PRESS and demonstrates some advantages of prospective sequence analysis when measuring their concentrations. The analysis emphasizes the variation in coupled‐spin signal yield and lineshape, compared with that of uncoupled singlets such as N‐acetylaspartate, a variation that differs from one metabolite spin system to another. This difference in variation between a target metabolite (e.g., mI) and its contaminating background metabolites (e.g., glutamate and taurine, etc.) is shown to provide in certain circumstances a substantial reduction in background contamination (both metabolite and macromolecule) while maintaining sufficient signal‐to‐noise ratio for precise quantification. For example, sequence times are demonstrated, both for STEAM and for PRESS, that, relative to the short echo‐time sequences typical in the literature, enhance the signal to metabolite background of the 3.6‐ppm band of mI by factors of 1.7 and 1.3, respectively, essentially eliminate the macromolecular baseline, and yet in vivo retain an S/N ∼ 10 in both cases. Magn Reson Med 53:760–769, 2005. © 2005 Wiley‐Liss, Inc.
Starter sequence for steady‐state free precession imaging
Authors: Foxall D. L. 
Published: March 2005

AbstractThe dynamic equilibrium exploited by balanced steady‐state free precession imaging develops slowly because its formation is dependent on both spin–spin and spin–lattice relaxation times. Attempting to image before steady state is established results in artifacts due to transient signal oscillations. Using a starter sequence to precondition the spin system can significantly reduce the delay before imaging. An improved design for a steady‐state starter sequence is presented. The new sequence has the advantage of uniformly exciting the steady‐state response for all resonance offsets and can be phase cycled to suppress banding artifacts. Magn Reson Med 53:919–929, 2005. © 2005 Wiley‐Liss, Inc.
Input parameter sensitivity analysis and comparison of quantification models for continuous arterial spin labeling
Authors: Steger Theodore R. , White R. Allen , Jackson Edward F. 
Published: March 2005

AbstractThe regional cerebral blood flow (rCBF) values determined using continuous arterial spin labeling (CASL) are subject to several sources of variability, including natural physiologic variations, sensitivity to the input parameters, and the use of different quantification models. To date, a thorough analysis of the impact of input parameters and the choice of quantification model has not been performed. These sources of variability were investigated through computer simulations using bootstrap techniques on actual CASL data. Coefficients of variation for representative single voxels were 6.7% for gray matter and 29% for white matter, and for eight‐voxel regions of interest they were 4.5% for gray matter and 23% for white matter. Comparison of nine CASL quantification models showed differences in gray matter rCBF values of up to 42%. An analysis of the sensitivity of the rCBF to input parameters for each of the nine quantification models demonstrated that accurate quantification of the inversion efficiency, tissue and arterial blood longitudinal relaxation times, and transit times were critical in calculating precise rCBF values. The large potential variations in rCBF and the effect of the choice of quantification model suggest that interpreting absolute rCBF values in CASL studies can be challenging and requires great care. Magn Reson Med 53:895–903, 2005. © 2005 Wiley‐Liss, Inc.
Jochimsen TH, et al. Quantifying the Intra‐ and Extravascular Contributions to Spin‐Echo fMRI at 3 T, Magn Reson Med 2004;52:724‐732.
Authors: Jochimsen Thies H. 
Published: March 2005

AbstractThe original article to which this Erratum refers was published in Magnetic Resonance in Medicine (2004) 52(4) 724–732.
Stabilized Crouzeix‐Raviart element for the Darcy‐Stokes problem
Authors: Burman Erik , Hansbo Peter 
Published: March 2005

AbstractWe stabilize the nonconforming Crouzeix‐Raviart element for the Darcy‐Stokes problem with terms motivated by a discontinuous Galerkin approach. Convergence of the method is shown, also in the limit of vanishing viscosity. Finally, some numerical examples verifying the theoretical predictions are presented. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 21, 2005.
Risk factors for and prevention of tobacco use
Authors: Sussman Steve 
Published: March 2005

AbstractThis study describes the risk factors for and prevention of tobacco use among young people. Risk factors show differential importance along the course of tobacco use development. The contents of an effective prevention effort vary as a function of the age of target group. However, the mediation of the effects of effective programs is not well known. Various modalities of implementation of prevention programming may be important, though a majority of program evaluation has occurred in the school context. The majority of well‐evaluated tobacco use prevention programs that employ a comprehensive social influences model show effects over an average of 6 years post‐programming. Pediatr Blood Cancer 2005;44:614–619. © 2005 Wiley‐Liss, Inc.
High cumulative rate of secondary leukemia after continuous etoposide treatment for solid tumors in children and young adults
Authors: Le Deley Marie‐Cécile , Vassal Gilles , Taïbi Ahmed , Shamsaldin Akthar , Leblanc Thierry , Hartmann Olivier 
Published: March 2005

AbstractBackgroundIn a national pediatric case‐control study, we observed a very high relative risk of leukemia in patients who had received continuous etoposide (CE) over 6 months or more, but we could not estimate the absolute risk. The purpose of the present study was to estimate this absolute risk after CE.ProceduresWe report a study of 18 patients with refractory or recurrent tumors who received CE over 6 months or more between 1995 and 1997. It was administered either 3 days a week for 3/4 weeks (“3 × 3”, 14 patients) or 7 days a week for 3/4 weeks (“7 × 3”, four patients).ResultsFive patients developed secondary leukemia 10–25 months after the initiation of CE. All the others died of their first tumor. The cumulative incidence of leukemia at 30 months was 28% (95% CI, 10%–53%). A chromosome 11q23 rearrangement was found in 3/5 cases. All four patients who received the “7 × 3” CE schedule developed leukemia compared to 1/14 treated with the “3 × 3” CE schedule (P = 0.002).ConclusionsGiven its efficacy, CE may still have a place as a palliative treatment. However, the risk of leukemia must be borne in mind when considering its use in patients with a better prognosis. Pediatr Blood Cancer 2005; 45:25–31. © 2005 Wiley‐Liss, Inc.
Pilomyxoid astrocytoma in a patient with neurofibromatosis
Authors: Khanani Muhammad Faisal , Hawkins Cynthia , Shroff Manohar , Dirks Peter , Capra Michael , Burger P.C. , Bouffet Eric 
Published: March 2005

AbstractPilomyxoid astrocytoma (PMA), a recently described variant of low‐grade astrocytoma is associated with a high rate of recurrence and a propensity for CSF seeding. While cases of PMA have been reported in infants and young children, there has been no report of PMA in patients with neurofibromatosis. The first reportable case of PMA occurring in a child with neurofibromatosis type 1 (NF1) is described. Following presentation with obstructive hydrocephalus, the patient underwent a partial resection of a third ventricular tumor. Histology confirmed the typical features of PMA. The patient demonstrated a partial response to chemotherapy. The authors review the literature on PMA and discuss the specific issues associated with this diagnosis in the context of a child with neurofibromatosis. © 2005 Wiley‐Liss, Inc.
Less toxic acetylacetonates as initiators of trimethylene carbonate and 2,2‐dimethyltrimethylene carbonate ring opening polymerization
Authors: Dobrzynski Piotr , Pastusiak Malgorzata , Bero Maciej 
Published: March 2005

AbstractThis article presents the results of TMC and DMC polymerization with the use of acetylacetonates of low‐toxic metals: iron, zinc, and zirconium. Zinc (II) acetylacetonate proves to be a very good initiator of homopolymerization. The reaction carried out with the use of this initiator at 110 °C is very rapid and of high yield. Using both zinc and iron (III) acetylacetonates, as well as the zirconium (IV) one, in high temperatures it is possible to obtain PTMC possessing high molecular mass, thus ensuring optimization of the relation between the duration of the polymerization and its yield. A strong influence of thermal degradation on the course of the reaction has been observed, particularly at 160 °C, with the use of Fe(acac)3 as the initiator. DMC polymerization proceeds much more slowly when initiated by iron and zinc acetylacetonates. A high conversion of the monomer is obtained in this case as well. The relation between the molecular mass of the obtained PDMC and the conversion of the monomer is directly proportional; however, those masses, determined on the basis of polystyrene standards, are much lower than those estimated theoretically. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1913–1922, 2005
Kinetic study of the radical polymerization behavior of N‐(1‐phenylethylaminocarbonyl)methacrylamide
Authors: Seno Makiko , Yamada Takahiro , Wang Hongwei , Hirano Tomohiro , Sato Tsuneyuki 
Published: March 2005

AbstractPolymerization of N‐(1‐phenylethylaminocarbonyl)methacrylamide (PEACMA) with dimethyl 2,2′‐azobisisobutyrate (MAIB) was kinetically studied in dimethyl sulfoxide (DMSO). The overall activation energy of the polymerization was estimated to be 84 kJ/mol. The initial polymerization rate (Rp) is given by Rp = k[MAIB]0.6[PEACMA]0.9 at 60 °C, being similar to that of the conventional radical polymerization. The polymerization system involved electron spin resonance (ESR) spectroscopically observable propagating poly(PEACMA) radical under the actual polymerization conditions. ESR‐determined rate constants of propagation and termination were 140 L/mol s and 3.4 × 104 L/mol s at 60 °C, respectively. The addition of LiCl accelerated the polymerization in N,N‐dimethylformamide but did not in DMSO. The copolymerization of PEACMA(M1) and styrene(M2) with MAIB in DMSO at 60 °C gave the following copolymerization parameters; r1 = 0.20, r2 = 0.51, Q1 = 0.59, and e1 = +0.70. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2013–2020, 2005
Influence of the catalyst on monomer insertion in the syndiospecific copolymerization of styrene and para‐methylstyrene
Authors: Schellenberg Jürgen 
Published: March 2005

AbstractThe effect of the kind of transition‐metal catalyst on the extent of comonomer insertion in the syndiospecific complex‐coordinative copolymerization of styrene and para‐methylstyrene has been investigated. The results for the influence of the polymerization conditions have shown that there is no real difference between solution copolymerization in toluene and solvent‐free styrene copolymerization in bulk, with respect to the reactivity ratio for para‐methylstyrene (r2), under comparable conditions in the presence of methylaluminoxane and triisobutylaluminum and at low polymerization conversions. All the investigated catalysts lead to a preferred incorporation of para‐methylstyrene into the polymer chain in comparison with styrene and over the whole range of monomer compositions. The increasing capability of the different catalysts to provide copolymers with enhanced para‐methylstyrene concentrations can be summarized by the increasing r2 values for the copolymerization in bulk as follows: η5‐pentamethylcyclopentadienyl titanium trichloride < η5‐octahydrofluorenyl titanium trimethoxide < η5‐octahydrofluorenyl titanium tristrifluoroacetate < η5‐cyclopentadienyl titanium(N,N‐dicyclohexylamido)dichloride < η5‐cyclopentadienyl titanium trichloride. For a correlation between the catalyst structure and the comonomer insertion, the catalysts can be described by electronic effects (electrostatic charge of the transition‐metal atom) and steric effects (minimum structural cone angle). The results show that the steric properties of the transition‐metal complexes have the most important effect on the insertion of para‐methylstyrene into the copolymer. If the minimum structural cone angle of the ligand of the transition‐metal catalyst decreases, the incorporation of the comonomer para‐methylstyrene increases significantly. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2061–2067, 2005
Role of vacuum ultraviolet irradiation in plasma‐induced graft polymerization in the pore‐filling polymerization of porous materials
Authors: Kai Teruhiko , Ueno Wataru , Yamaguchi Takeo , Nakao Shin‐Ichi 
Published: March 2005

AbstractThe role of vacuum ultraviolet (VUV) rays contained in the plasma during plasma‐induced graft polymerization in the pores of a porous high‐density polyethylene (HDPE) substrate was investigated through the separation of the VUV rays from the plasma with LiF, CaF2, and quartz filters. Two characteristic phenomena, the effect of the solvent on the grafting rate and the graft polymerization in the pores of the porous substrate, were observed in the VUV‐induced graft polymerization process. These results provided clear evidence that VUV rays in the plasma played an important role in the formation of grafted layers in the pores of the HDPE substrate. The relationship between the penetration depth of the VUV rays and the distribution of the grafted layer inside the substrate was examined. The calculated penetration depth of the VUV rays (and hence the distribution of radicals) and the distribution of the grafted layer were not consistent. However, this inconsistency could be explained by the fact that the effective density of the radicals that could react with the monomer to grow the grafting polymer was very low because of the steric hindrance of the grafted chains. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2068–2074, 2005
Interferon‐γ induces neuroendocrine‐like differentiation of human prostate basal‐epithelial cells
Authors: Untergasser Gerold , Plas Eugen , Pfister Gerald , Heinrich Elmar , Berger Peter 
Published: March 2005

AbstractBACKGROUNDProstatic neuroendocrine (NE) cells are intraglandular hybrid epithelial‐neural‐endocrine cells that express and secrete numerous hormones and neuropeptides, which presumably regulate growth, differentiation, and secretory activity of the prostatic epithelium. This specialized cell type appears to differentiate from a common basal/precursor/stem cell that also gives rise to the secretory epithelium. In order to elucidate mechanisms of NE‐differentiation the effects of type 1 (α, β) and type 2 (γ) interferons (IFNs) on human prostate basal cells (PrECs) were evaluated.METHODS AND RESULTSApplication of α/β IFN increased the expression of the cell‐cycle inhibitor p21CIP1 and inhibited DNA synthesis, while only IFN‐γ led to increased apoptosis, cell‐cycle inhibitor p27KIP1 upregulation, and differentiation of PrECs into NE‐like cells. In vitro differentiated NE‐like cells expressed the glycolytic enzyme neuron‐specific enolase (NSE) and chromogranin A (CgA), known markers of NE‐cells in vivo in the prostate. These NE‐like cells also changed cytokeratin (CK) expression patterns by upregulating CK 8/18, predominantly found in terminally‐differentiated secretory luminal/NE epithelial cells.CONCLUSIONSIFN‐γ produced locally in the prostate by basal cells and, under proinflammatory conditions, by infiltrating lymphocytes could support NE cell differentiation and play a role in NE differentiation processes of tumor cells in hormone‐refractory prostate cancer. © 2005 Wiley‐Liss, Inc.
Characterization of AlGaN layer with high Al content grown by mixed‐source HVPE
Authors: Ahn H. S. , Kim K. H. , Yang M. , Yi J. Y. , Lee H. J. , Chang J. H. , Kim H. S. , Kim S. W. , Lee S. C. , Honda Y , Yamaguchi M. , Sawaki N. 
Published: March 2005

AbstractUsing mixed‐source hydride vapor‐phase epitaxy (HVPE), an AlGaN layer with high Al content on GaN/Al2O3 substrate is obtained. The AlGaN layer grown by mixed‐source HVPE is characterized by X‐ray diffraction (XRD) measurements and cathodoluminescence (CL) spectra. In the mixed‐source HVPE technique, the AlGaN material is compounded from the chemical reaction between NH3 and an aluminum–gallium chloride formed using HCl that is flowed over metallic Ga mixed with Al. The XRD measurements indicate that single‐crystal hexagonal AlGaN with high Al content had been grown. The CL spectra at 4 K show that the distribution of the Al on the AlGaN surface for very high Al content (x = 0.8 in AlxGa1–xN) is not uniform. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)