bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the use of the stochastic Liouville equation in nuclear magnetic resonance: Application to R1ρ relaxation in the presence of exchange
Authors: Abergel Daniel , Palmer Arthur G. 
Published: October 2003

AbstractThe nuclear magnetic resonance (NMR) spin relaxation rate constant in the rotating frame of reference R1ρ provides information on microsecond to millisecond (μs‐ms) timescale kinetic processes that stochastically modulate the resonance frequencies of nuclear spins in molecules. Expressions for R1ρ are presented for two‐site chemical exchange using both the conventional perturbation approach for evolution of the density operator in the interaction frame of reference and the stochastic Liouville equation (SLE) for evolution of the average density operator in the rotating frame of reference. The former approach is limited to the fast‐exchange regime, in which the chemical exchange kinetics are faster than the frequency difference between spins in the two sites. The latter approach provides approximate expressions for R1ρ that are accurate when chemical exchange is not fast. Expressions for R1ρ that are accurate over the widest range of experimental conditions facilitate the interpretation of chemical exchange phenomena. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part A 19A: 134–148, 2003.
Pulsed field gradient nuclear magnetic resonance as a tool for studying drug delivery systems
Authors: Momot Konstantin I. , Kuchel Philip W. 
Published: October 2003

AbstractPulsed field gradient (PFG) nuclear magnetic resonance (NMR) is a versatile method for studying molecular transport and exchange in solution. Stejskal‐Tanner diffusion plots can be used to distinguish between chemical species even in the absence of chemical shift or T1 resolution, provided that certain conditions are satisfied. This can be used advantageously in colloidal drug delivery systems containing two drug populations, free and bound, which often differ only by their diffusion coefficients. We discuss the conditions required for the resolution of the two pools in Stejskal‐Tanner plots, as well as the effects of chemical exchange. We also present two practical examples of this analysis: surfactant micelles containing the general anesthetic propofol and lipid/water liquid crystalline mesophase vehicles (cubosomes). © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part A 19A: 51–64, 2003.
Quantification of magnetization transfer by sampling the transient signal using MT‐prepared single‐shot EPI
Authors: Helms Gunther , Hagberg Gisela E. 
Published: October 2003

AbstractWe describe the standard model for magnetization transfer (MT): a two‐pool system with pseudo‐linear exchange kinetics; under the influence of repetitive “MT‐pulses” that create arbitrary instantaneous saturation. The influence of the pulse repetition period on the steady state (Part I) and the transient behavior of the system (Part II) provides similar but not equivalent information about relaxation, exchange and saturation. A quantification of all six parameters was possible by sampling the transitions and steady state at pulse repetition times between 8 ms and 200 ms by means of single‐shot echo‐planar imaging of the human brain in vivo. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part A 19A: 149–152, 2003.
Atypical glandular cells—an update
Authors: Cangiarella Joan F. , Chhieng David C. 
Published: October 2003

AbstractThe diagnostic category of atypical glandular cells (AGC) in the Bethesda system for the reporting of cervicovaginal cytology has undergone significant modification since its inception in 1988. More than a decade later, this category remains a diagnostic challenge to both clinicians and cytopathologists because of the lack of uniform cytologic criteria, the lack of interobserver agreement in the diagnosis, and the lack of standardized patient management guidelines. This article reviews the current classification of AGC in the Bethesda system, the cytomorphologic features and differential diagnosis, the clinical significance of a diagnosis of AGC, and the clinical management of patients with AGC. This article provides a comprehensive clinicopathologic review of the category of AGC. Diagn. Cytopathol. 2003;29:271–279. © 2003 Wiley‐Liss, Inc.
Detection of herpes simplex virus DNA by in situ hybridization technique and polymerase chain reaction in Papanicolaou‐stained cervicovaginal smears
Authors: Iwa Nobuzo , Noguchi Hideki 
Published: October 2003

AbstractPapanicolaou‐stained cervicovaginal smears from six patients with herpes simplex virus (HSV) infection were destained and reprocessed by means of in situ hybridization (ISH) technique to demonstrate the presence of HSV DNA utilizing biotinylated probe. Positive results were obtained in all six cases with intense staining signal for the HSV DNA in the nuclei of cells having a ground‐glass nuclear appearance as well as in multinucleated giant cells. Furthermore, a hybridization signal was also noted in smears that had been prepared as much as 3 yr previously. HSV type 2‐specific antigen was confirmed in six destained smears by means of immunoperoxidase staining. Moreover, polymerase chain reaction (PCR) was also performed for four patients from Pap‐destained cervicovaginal smears. Amplified HSV DNA was detected in all four cases as 106 basepair PCR products by polyacrylamide gel electrophoresis. The combined use of cytology and the ISH technique and PCR amplification was of great value for the rapid cytodiagnosis of genital infection of HSV. Diagn. Cytopathol. 2003;29:246–249. © 2003 Wiley‐Liss, Inc.
Histiocytic aggregates in benign nodular goiters mimicking cytologic features of papillary thyroid carcinoma (PTC)
Authors: Nassar Aziza , Gupta Prabodh , LiVolsi Virginia A. , Baloch Zubair 
Published: October 2003

AbstractMacrophages/histiocytes are commonly seen in fine‐needle aspiration biopsy (FNAB) specimens of thyroid nodules with varying degrees of cystic change. In some cases the histiocytic component of a cystic thyroid nodule can occur as large tissue fragments with marked nuclear atypia, including elongated nuclei with chromatin clearing, nuclear grooves, and membrane thickening. These nuclear changes mimic cytologic features of papillary thyroid carcinoma (PTC), thus leading to diagnostic difficulty in interpretation of FNAB specimens of benign cystic thyroid nodules. We evaluated ethanol‐fixed Papanicolaou‐stained smears of 273 cases of FNAB thyroid specimens from goitrous nodules with cystic change. Twenty cases were selected due to the presence of large aggregates of histiocytic cells with the above‐mentioned nuclear atypia. An immunostain for histiocytic cells using CD68 was performed on alcohol‐fixed slides. Histiocytic cells in tissue fragments with nuclear atypia mimicking PTC nuclei showed strong cytoplasmic staining for CD68; thyroid follicular cells stained negative for CD68. We conclude that histiocytic cells in cystic goitrous nodules can show nuclear features, which appear similar to PTC nuclei. Immunostaining for CD68 may be of value in differentiating between benign cystic thyroid nodules with histiocytic aggregates that mimic cytologic features of papillary carcinoma, and PTC with cystic change. Diagn. Cytopathol. 2003;29:243–245. © 2003 Wiley‐Liss, Inc.
Metastatic ovarian Sertoli‐cell tumor: FNA findings with immunohistochemistry
Authors: Watson Brian , Siegel Cary L. , Ylagan Lourdes R. 
Published: October 2003

AbstractA malignant Sertoli cell tumor of the ovary is a rare sex‐cord stromal derived neoplasm. Sertoli cell tumors account for ∼4% of Sertoli‐stromal cell tumors (Hsu et al., J Histochem Cytochem 1981;29:577–580). The diagnosis of this entity by fine‐needle aspiration and needle core biopsy can be difficult when the differential also includes a metastatic renal cell carcinoma, due to the overlap of both cytological and histological features. Here, we show that immunohistochemical staining on cytological material including alpha‐inhibin can be used to differentiate between these two malignant tumors. Diagn. Cytopathol. 2003;29:283–286. © 2003 Wiley‐Liss, Inc.
Fine‐needle aspiration smears from lipomatous hemangiopericytoma need not be confused with myxoid liposarcoma
Authors: Domanski Henryk A. 
Published: October 2003

AbstractLipomatous hemangiopericytoma (LHPC) is a rare benign soft tissue tumor that may mimic soft tissue sarcoma clinically. Despite the fact that LHPC shares most of the histologic features with solitary fibrous tumor, it may be occasionally misdiagnosed as myxoid liposarcoma or some other type of spindle‐cell sarcoma. While some studies have addressed the histological features and origin of LHPC, no reports of cytological findings have been published. The author describes the cytological features of LHPC in two patients with correlations to histological and clinical findings. One of aspirates was misdiagnosed as being myxoid liposarcoma, while the other one was correctly diagnosed by a combination of FNAB and core needle biopsy (CNB). Cytological evaluation of LHPC can be problematic due to its rarity and to its similarity with other spindle‐cell or fatty tumors. Correct diagnosis requires an awareness of cytologic features of this rare tumor and the use of ancillary studies. Diagn. Cytopathol. 2003;29:287–291. © 2003 Wiley‐Liss, Inc.
Effectiveness of the SurePath liquid‐based Pap test in automated screening and in detection of HSIL
Authors: Cengel Keith A. , Day Sarah J. , Davis‐Devine Sharon , Adams Christina L. , Madison‐Henness Darcy , Hartman Matthew E. , Freund Gregory G. 
Published: October 2003

AbstractWe have shown that SurePath when compared to conventional Paps fails to increase HSIL detection. In this study, assessment of test performance characteristics for the FocalPoint showed that sensitivity was 96% when manual screening was used as the “gold standard.” When cervical biopsy, however, was used as the “gold standard” FocalPoint sensitivity decreased to 93%, which was the same as manual screening. Examination of the FocalPoint “no further review” cases showed that 4/296 were SIL. To understand better the implication of an SIL diagnosis, cervical biopsies generated from SurePath and conventional Paps were compared. Conventional Paps diagnosed as LSIL had a biopsy LSIL:HSIL ratio of 3.1/1, while SurePath Paps had a biopsy LSIL:HSIL ratio of 1.5/1. These results indicate that when cervical biopsy is used as the “gold standard,” FocalPoint and manual screening of SurePath Paps have similar test performance but that the FocalPoint can fail to detect LSIL. Importantly, LSIL in a SurePath Pap is 1.6 times more likely to be HSIL on biopsy than LSIL in a conventional Pap. Diagn. Cytopathol. 2003;29:250–255. © 2003 Wiley‐Liss, Inc.
Rhabdoid meningioma: Intraoperative diagnosis using smear preparation
Authors: Kirby Patricia A. 
Published: October 2003

AbstractTumors with rhabdoid morphology were first described by Beckwith and Palmer in 1978 as aggressive renal tumors in very young children. Subsequently, rhabdoid tumors and tumors with rhabdoid features have been described in many other organ systems and all tend to have a poor outcome no matter what the histogenesis of the original tumor. Rhabdoid cells are plump, with abundant eosinophilic fibrillary to hyaline cytoplasm and peripheral, vesicular, variably pleomorphic nuclei. Nucleoli are invariably present. While their morphology is well recognized in processed biopsy material, their presence on a smear preparation can be quite startling. A case is presented to highlight the appearance of rhabdoid cells on an intraoperative smear preparation of a rhabdoid meningioma. An accompanying secretory component added to the complex picture. Diagn. Cytopathol. 2003;29:292–296. © 2003 Wiley‐Liss, Inc.
Correlation of manual screening and automated (AutoPap 300) analysis of conventional cervicovaginal smears with HPV typing using Digene HC II assay
Authors: Walts Ann E. , Thomas Premi 
Published: October 2003

AbstractEfforts to improve the accuracy and efficacy of diagnosis of cervical cancer and its precursor lesions have prompted the development of new technologies, including several automated screening systems and human papillomavirus (HPV) hybrid capture assay. In this study of 89 conventional cervicovaginal (Papanicolaou [Pap]) smears, diagnoses based on manual screening are correlated with analyses by the AutoPap 300 primary screening system and results of the Digene HPV hybrid capture II assay. We found that (1) the AutoPap system did not “miss” (place in the “no further review” category) any of the high‐risk HPV DNA positive cases, (2) quintile assignments by the AutoPap system did not reliably predict the presence or absence of high‐risk HPV DNA, (3) cases of low‐grade squamous intraepithelial lesion (LGSIL) were associated with high‐risk rather than low‐risk HPV genotypes, (4) diagnoses of atypical squamous cells of undetermined significance (ASCUS) and above were more frequent in smears from patients whose cervicovaginal specimens tested positive rather than negative for high‐risk HPV DNA (37 of 45 vs 14 of 44) by the Digene HPV hybrid capture II assay, and (5) there was a high incidence of high‐risk HPV DNA among women whose smears did not show cytomorphologic changes of high‐grade squamous intraepithelial lesion (HGSIL). These findings emphasize that high‐risk HPV DNA is an indication of risk for HGSIL, not the equivalent for it. Diagn. Cytopathol. 2003;29:256–261. © 2003 Wiley‐Liss, Inc.
Sensitive cytologic criteria for the identification of follicular variant of papillary thyroid carcinoma in fine‐needle aspiration biopsy
Authors: Wu Howard Her‐Juing , Jones Jennifer N. , Grzybicki Dana Marie , Elsheikh Tarik M. 
Published: October 2003

AbstractThe cytologic diagnosis of follicular variant of papillary thyroid carcinoma (FVPTC) can be extremely challenging and may be associated with false negative diagnoses. The purpose of this study was to determine the minimal cytologic criteria needed to identify FVPTC. We examined sixty‐nine fine‐needle aspiration (FNA) cases, processed with Diff‐Quik and Papanicolaou stains, that were either diagnostic or suspicious of FVPTC. All cases had histologic confirmation. These cases included 29 FVPTC, 18 classic papillary thyroid carcinoma (PTC), 17 follicular neoplasm (6 adenomas, 10 carcinomas, 1 neoplasm NOS), 2 lymphocytic thyroiditis and 3 nodular goiter. Seven of the most commonly cited cytomorphologic features, including flat syncytial sheets, nuclear enlargement, fine chromatin, nuclear grooves, nuclear pseudoinclusions, and amount of colloid and cytoplasm, were evaluated. A diffuse distribution of fine chromatin, nuclear grooves, and colloid was seen more often in FVPTC than in follicular neoplasm (p<0.01). The combination of flat/syncytial sheets, nuclear enlargement, and fine chromatin was observed in all our cases of FVPTC, and is therefore considered a sensitive marker in detecting FVPTC. Logistic regression analysis revealed colloid to be the only positive predictor in favor of FVPTC over classic PTC. Diagn. Cytopathol. Diagn. Cytopathol. 2003;29:262–266. © 2003 Wiley‐Liss, Inc.
Hybrid LES‐RANS modelling: a one‐equation SGS model combined with a k–ω model for predicting recirculating flows
Authors: Davidson L. , Peng S. H. 
Published: October 2003

AbstractA hybrid LES‐RANS modelling approach is proposed. RANS is used in the near wall regions (y+≲60), and the turbulence is modelled with a k–ω model. LES is used in the remaining part of the flow, and the SGS turbulence is modelled with a one‐equation ksgs model. The same continuity and momentum equations are solved throughout the domain, the only difference being that the turbulent viscosity is taken from the k–ω model in the RANS region, and from the one‐equation ksgs model in the LES region. The new modelling approach is applied to two incompressible flow test cases. They are fully developed flow in a plane channel and the flow over a 2D‐hill in a channel. Copyright © 2003 John Wiley & Sons, Ltd.
Computation of an unsteady complex geometry flow using novel non‐linear turbulence models
Authors: Tucker Paul G. , Liu Yan , Chung Yongmann M. , Jouvray Alex 
Published: October 2003

AbstractNon‐linear zonal turbulence models are applied to an unsteady complex geometry flow. These are generally found to marginally improve predicted turbulence intensities. However, relative to linear models, convergence is mostly difficult to achieve. Clipping of some non‐linear Reynolds stress components is required along with velocity field smoothing or alternative measures. Smoothing is naturally achieved through multilevel convergence restriction operators. As a result of convergence difficulties, generally, non‐linear model computational costs detract from accuracy gains. For standard Reynolds stress model results, again computational costs are prohibitive. Also, mean velocity profile data accuracies are found worse than for a simple mixing length model. Of the non‐linear models considered, the explicit algebraic stress showed greatest promise with respect to accuracy and stability. However, even this shows around a 30% error in total (the sum of turbulence and unsteadiness) intensity. In strong contradiction to measurements the non‐linear and Reynolds models predict quasi‐steady flows. This is probably a key reason for the total intensity under‐predictions. Use of LES in a non‐linear model context might help remedy this modelling aspect. Copyright © 2003 John Wiley & Sons, Ltd.
A parallel implementation of the fast multipole method for Maxwell's equations
Authors: Havé Pascal 
Published: October 2003

AbstractIt is well known that the resolution of Maxwell equations may provide large dense matrices, being thus a computer intensive problem. Even small problems require a huge amount of memory to manipulate matrices during the O(N3) involved operations.The fast multipole method enables to compress and approximate matrices. Coupled with an iterative resolution of the linear system the complexity reduces to O(Niter N log N) operations.In order to use multiprocessors machine and to reduce computation times, we propose here a parallel implementation of the fast multiple method. This article relates our first results, as well as the difficulties encountered. Copyright © 2003 John Wiley & Sons, Ltd.
Numerical techniques for flow problems with singularities
Authors: Farrell Paul A. , Hegarty Alan F. , Miller John J. H. , O'Riordan Eugene , Shishkin Grigorii I. 
Published: October 2003

AbstractThis paper deals with grid approximations to Prandtl's boundary value problem for boundary layer equations on a flat plate in a region including the boundary layer, but outside a neighbourhood of its leading edge. The perturbation parameter ε= Re‐1 takes any values from the half‐interval (0,1] ; here Re is the Reynolds number. To demonstrate our numerical techniques we consider the case of the self‐similar solution. By using piecewise uniform meshes, which are refined in a neighbourhood of the parabolic boundary layer, we construct a finite difference scheme that converges ε‐uniformly. We present the technique of experimental substantiation of ε‐uniform convergence for both the numerical solution and its normalized (scaled) difference derivatives, outside a neighbourhood of the leading edge of the plate. By numerical experiments we demonstrate the efficiency of numerical techniques based on the fitted mesh method. We discuss also the applicability of fitted operator methods for the numerical approximation of the Prandtl problem. It is shown that the use of meshes refined in the parabolic boundary layer region is necessary for achieving ε‐uniform convergence. Copyright © 2003 John Wiley & Sons, Ltd.
Computing realistic Reynolds‐uniform error bounds for discrete derivatives of flow velocities in the boundary layer for Prandtl's problem
Authors: Farrell Paul A. , Hegarty Alan F. , Miller John J. H. , O'Riordan Eugene , Shishkin Grigorii I. 
Published: October 2003

AbstractIn this paper, we describe an experimental error analysis technique for computing realistic values of the parameter‐uniform order of convergence and error constant in the maximum norm associated with a parameter‐uniform numerical method for solving singularly perturbed problems. We then employ this technique to compute Reynolds‐uniform error bounds in the maximum norm for appropriately scaled discrete derivatives of the numerical solutions generated by a fitted‐mesh upwind finite‐difference method applied to Prandtl's problem arising from laminar flow past a thin flat plate. Here the singular perturbation parameter is the reciprocal of the Reynolds number. This illustrates the efficiency of the technique for finding realistic parameter‐uniform error bounds in the maximum norm for numerical approximations to scaled derivatives of solutions to problems in cases where no theoretical error analysis is available. Copyright © 2003 John Wiley & Sons, Ltd.
A Reynolds‐uniform numerical method for Prandtl's boundary layer problem for flow past a wedge
Authors: Butler J. S. , Miller John J. H. , Shishkin Grigorii I. 
Published: October 2003

AbstractIn this paper, we deal with Prandtl's boundary layer problem for incompressible laminar flow past a wedge. When the Reynolds number is large the solution of this problem has a parabolic boundary layer. We construct a direct numerical method for computing approximations to the solution of this problem using a piecewise uniform fitted mesh technique appropriate to the parabolic boundary layer. We use the numerical method to approximate the self‐similar solution of Prandtl's problem in a finite rectangle excluding the leading edge of the wedge, which is the source of an additional singularity caused by incompatibility of the problem data. We verify that the constructed numerical method is robust, in the sense that the computed errors for the velocity components and their derivatives in the discrete maximum norm are Reynolds uniform. We construct and apply a special numerical method related to the Falkner–Skan technique to compute a reference solution for the error analysis of the velocity components and their derivatives. By means of extensive numerical experiments we show that the constructed direct numerical method is Reynolds uniform. Copyright © 2003 John Wiley & Sons, Ltd.
A Reynolds‐uniform numerical method for the Prandtl solution and its derivatives for stagnation line flow
Authors: Miller John J. H. , Musgrave Alison P. , Shishkin Grigorii I. 
Published: October 2003

AbstractFarrell et al. (Robust Computational Techniques for Boundary Layers. Chapman & Hall/CRC: Boca Raton, 2000) develop a Reynolds‐uniform numerical method for the solution of the Prandtl equations in the case of flow past a flat plate. In this paper, we examine the applicability of this Prandtl method to the stagnation line flow problem in a domain that includes the stagnation line. Stagnation line flow has been chosen because of its self‐similar nature; reference solutions that approximate the exact solution of the problem to high levels of accuracy can be numerically obtained, allowing the error in the numerical approximations generated by the Prandtl method to be calculated. We present detailed results which verify that the method is Reynolds uniform. Global Reynolds‐uniform error bounds are constructed for the numerical approximations to the velocity components and their scaled first derivatives, and the practical uses of these bounds are discussed. We show that the number of iterations required for convergence of this iterative method is Reynolds uniform. In addition, we test an experimental technique for computing global Reynolds‐uniform error bounds, which can be used when solving flow problems for which no exact or reference solution is available. Experimental error bounds are constructed using this technique and are shown to be realistic upper bounds for the error values obtained with the use of the reference solutions. Copyright © 2003 John Wiley & Sons, Ltd.