bluuebunny/crossref_metadata_2025_split huggingface dataset:
A variational calculation of TE and TM cutoff wavenumbers in circular eccentric guides by conformal mapping
Authors: Yang Hyunkieu , Lee Sangseol 
Published: August 2002

AbstractThe cutoff wavenumbers of higher order modes in circular eccentric guides are computed with the variational analysis combined with a conformal mapping. A conformal mapping is applied to the variational formulation, and the variational equation is solved by the finite‐element method. Numerical results for TE and TM cutoff wavenumbers are presented for different distances between the centers and ratio of the radii. Comparisons with numerical results found in the literature validate the presented method. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 381–384, 2001.
A practical technique for optimum matching of two‐element antenna arrays
Authors: Ozdemir Caner 
Published: August 2002

AbstractA fast and effective method for the matching of two‐ element symmetric antenna arrays is presented. The full geometry is subdivided into two half‐space problems with the help of an even‐ and odd‐mode (EOM) analysis scheme. An interpretation based on the EOM representation is made for any radiation pattern mode that is constructed by arbitrarily exciting the antenna ports. Also, a relationship between the radiation efficiency for the full geometry and the even‐ and odd‐mode S‐parameters is derived. A unique technique for matching the two‐element antenna arrays is developed by exploiting the EOM representation. Numerical examples that illustrate the effectiveness of our matching technique for different radiation pattern modes are provided. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 224–229, 2002.
Dependence of optical power confinement on core/cladding chiralities in chirofibers
Authors: Choudhury P. K. , Yoshino T. 
Published: August 2002

AbstractAn analytical study of the optical power confinement of a chirofiber is presented. Using Maxwell's field equations and considering the cases of meridional and skew modes, variation of the power confinement is presented in two events, viz. 1) with the change in cladding chirality (for fixed values of core chirality), and 2) with the change in core chirality (for fixed values of cladding chirality). Studies are made for two different fiber core diameters, and it is found that, in general, the power confinement in the core section reduces with the increase in its chirality admittance. Further, the amount of transmitted power increases with the mode index. However, as the core cross‐sectional size increases, the skew modes present almost similar behavior, and the power transported by them is much higher as compared to that by the meridional modes. Thus, the skew modes in such chirofibers with a little larger size present an event close to degeneracy, which is useful in integrated‐optic applications and optical‐communication systems. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 359–364, 2002.
MMIC medium‐power amplifier in K band with matching and power‐divider/combiner networks implemented with the use of lumped elements
Authors: Álvarez L. , Portilla J. , de la Fuente M.L. , Artal E. 
Published: August 2002

AbstractThe design and measurements of a monolithic K‐band medium‐power amplifier are reported. The matching, biasing, and power‐splitter networks have been implemented with the use of lumped elements, reducing the chip size. The model predictions of passive circuitry have been tested through electromagnetic simulations. The amplifier has shown interesting performance in K band. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 397–400, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10334
Genetic determinants of basal cell carcinoma risk*
Authors: Epstein Ervin 
Published: August 2002

AbstractBasal cell carcinomas are can be induced by ionizing radiation, in particular in patients with the rare autosomal dominant basal cell nevus syndrome (BCNS). These patients also are prone to medulloblastomas, and curative ionizing radiation therapy for the latter is followed soon by the development of sheets of basal cell carcinomas in the overlying skin. Positional cloning of the gene mutant is BCNS patients has identified the hedgehog signaling pathway as crucial to the development of all basal cell carcinomas and presumably to this susceptibility to post‐ionizing radiation carcinogenesis. Thus this pathway is a candidate for susceptibility to second, post‐therapy cancers in the broader population. Med. Pediatr. Oncol. 36:555–558, 2001. © 2001 Wiley‐Liss, Inc.
Extraction of T2 from NMR linewidths in simple spin systems by use of reference deconvolution
Authors: Mladenov G. , Dimitrov V. S. 
Published: August 2002

AbstractWe investigated the possibility of obtaining transverse relaxation times through linewidth measurements in NMR spectra of simple spin systems (subsystems). The spectra are subjected to reference deconvolution and subsequently to time domain data analysis. The time for the experiment is usually short; stringent instrumental stability should be maintained during the experiment. The approach described here produces correct results if the lineshape is Lorentzian. Rough width estimation is achievable in other cases. As an additional result, detection of very small couplings is possible. Copyright © 2001 John Wiley & Sons, Ltd.
Expression of glutamate‐cysteine ligase during mouse development
Authors: Díaz Dolores , Krejsa Cecile M. , Kavanagh Terrance J. 
Published: August 2002

AbstractThe tripeptide glutathione (GSH), which plays a crucial role in protecting cells against oxidative stress, is synthesized in a two‐step process. The rate‐limiting step is the binding of glutamate and cysteine, which is catalyzed by the enzyme glutamate‐cysteine ligase (GCL). This enzyme is composed of two subunits: a large catalytic subunit (GCLc) and a smaller modifying subunit (GCLm), originating from different genes. Control of cellular GSH levels is essential for normal development. In the current study, we investigated the tissue distribution of Gclc and Gclm transcripts, as well as GCLc protein, in the developing mouse embryo. We found that both mRNAs were highly expressed in the liver and CNS at gestational day 10 (gd 10) and gd 12, with Gclm being more abundant than Gclc in the liver relative to other tissues. Also, the expression of the two subunit mRNAs was not always parallel in the embryo, in that some tissues expressed one of the subunits preferentially, suggesting that the two genes are differentially expressed during mouse development. The GCLc protein was also widely expressed throughout the embryo, and, in general, it co‐localized with the Gclc mRNA. Mol. Reprod. Dev. 62: 83‐91, 2002. © 2002 Wiley‐Liss, Inc.
Flow cytometric sperm sorting: Effects of varying laser power on embryo development in swine*
Authors: Guthrie H.D. , Johnson L.A. , Garrett W.M. , Welch G.R. , Dobrinsky J.R. 
Published: August 2002

AbstractThis study was conducted to determine fertilization rate and embryo development using the Beltsville Sperm Sexing Technology with two different laser power outputs, 25 and 125 milliwatts (mW). Freshly ejaculated boar semen was diluted; one aliquot was not stained or sorted (nonsort) and a second aliquot was stained with Hoechst 33342 and sorted as a complete population, not separated into X and Y populations (all‐sort). Ovulation controlled gilts were surgically inseminated with 2 × 105 spermatozoa (44–46 hr after human chorionic gonadotropin (hCG)) into the isthmus of each oviduct, one oviduct receiving nonsort and the other all‐sort at 25 or 125 mW. A total of 426 embryos were flushed from oviducts at slaughter 43 hr after laparotomy and prepared for determination of fertilization and cleavage rates using confocal laser microscopy for analysis of actin cytoskeleton and chromatin configuration. The percentage of fertilized eggs and embryos was less for the 25 mW all‐sort compared to nonsort or the 125 mW all‐sort (77.9 vs. 96.3 and 96.2%, P < 0.05). The percentage of fragmented embryos was greater for the 25 mW all‐sort than the nonsort (15.2 vs. 4.5%, P < 0.05), but did not differ significantly from 125 mW all‐sort mean (7.2%). The percentage of normal embryos (80.4% overall) did not differ (P > 0.05) among treatments. However, the rate of embryo development was slower (P < 0.05) after insemination with the 25 mW all‐sort spermatozoa compared to nonsort spermatozoa. Embryos in the 3–4 and 5–9 cell stages for the 25‐mW all‐sort and nonsort were 78 and 20% vs. 49 and 50%, respectively. The embryo percentages for the 125 mW (3–4 and 5–9 cell stages, 59 and 35%) did not differ significantly (P > 0.05) from the nonsort or 25 mW all‐sort. We conclude that the use of 125 mW laser power for sorting boar spermatozoa is advantageous to maintain high resolution separation and has no detrimental effect on embryo development compared to 25 mW. Mol. Reprod. Dev. 61: 87–92, 2002. © 2002 Wiley‐Liss, Inc.
Detection of lymph node metastases by contrast‐enhanced MRI in an experimental model
Authors: Wunderbaldinger Patrick , Josephson Lee , Bremer Christoph , Moore Anna , Weissleder Ralph 
Published: August 2002

AbstractLymph node size, the accumulation of a nodal lymphotrophic contrast agent (LCDIO), and MRI were compared as methods for detecting nodal metastases in an experimental murine model. Lymph node metastases (B16‐F1 melanoma expressing green fluorescent protein (GFP) and C57BL/6 mice) were generated to obtain a wide spectrum of nodes, including normal nodes and nodes bearing micrometastases, small metastases, or large metastases. Nodal uptake of LCDIO was measured using 111Indium‐labeled LCDIO and was found to be lower in micrometastastic nodes (4.20 ± 1.4%ID/gm) than in normal nodes (8.60 ± 0.22% ID dose/gram, P < 0.005). Nodal tumor burden was quantified from the amount of GFP present in nodes measured using the Western blot method, and was found to correlate with the decrease of LCDIO uptake. By MRI, nodes bearing small and large metastases contained regions of high signal intensity (SI) that corresponded to the visual pattern of tumor in nodes. Micrometastatic nodes were distinguishable from normal nodes based on a diffuse pattern of inhomogeneous SI. The signal‐to‐background ratio (SBR) of normal nodes (0.0112 ± 0.0061) was different from micrometastatic nodes (0.179 ± 0.080, P < 0.00046) and nodes bearing small metastases (0.723 ± 0.269, P < 0.00013), with high degrees of significance. Magn Reson Med 47:292–297, 2002. © 2002 Wiley‐Liss, Inc.
Self‐calibrating parallel imaging with automatic coil sensitivity extraction
Authors: McKenzie Charles A. , Yeh Ernest N. , Ohliger Michael A. , Price Mark D. , Sodickson Daniel K. 
Published: August 2002

AbstractCalibration of the spatial sensitivity functions of coil arrays is a crucial element in parallel magnetic resonance imaging (PMRI). The most common approach has been to measure coil sensitivities directly using one or more low‐resolution images acquired before or after accelerated data acquisition. However, since it is difficult to ensure that the patient and coil array will be in exactly the same positions during both calibration scans and accelerated imaging, this approach can introduce sensitivity miscalibration errors into PMRI reconstructions. This work shows that it is possible to extract sensitivity calibration images directly from a fully sampled central region of a variable‐density k‐space acquisition. These images have all the features of traditional PMRI sensitivity calibrations and therefore may be used for any PMRI reconstruction technique without modification. Because these calibration data are acquired simultaneously with the data to be reconstructed, errors due to sensitivity miscalibration are eliminated. In vivo implementations of self‐calibrating parallel imaging using a flexible coil array are demonstrated in abdominal imaging and in real‐time cardiac imaging studies. Magn Reson Med 47:529–538, 2002. © 2002 Wiley‐Liss, Inc.
Detunable transverse electromagnetic (TEM) volume coil for high‐field NMR
Authors: Vaughan J.T. , Adriany G. , Garwood M. , Yacoub E. , Duong T. , DelaBarre L. , Andersen P. , Ugurbil K. 
Published: August 2002

AbstractMost high‐field MRI systems do not have the actively detuned body coils that are integral to clinical systems operating at 1.5T and lower field strengths. Therefore, many clinical applications requiring homogeneous volume excitation in combination with local surface coil reception are not easily implemented at high fields. To solve this problem for neuroimaging applications, actively detunable transverse electromagnetic (TEM) head coils were developed to be used with receive‐only surface coils for signal‐to‐noise ratio (SNR) gains and improved spatial coverage from homogeneously excited regions. These SNR and field of view (FOV) gains were achieved by application of a detunable TEM volume coil to human brain imaging at 4T. Magn Reson Med 47:990–1000, 2002. © 2002 Wiley‐Liss, Inc.
Improved efficiency in double‐inversion fast spin‐echo imaging
Authors: Parker Dennis L. , Goodrich K. Craig , Masiker Marilyn , Tsuruda Jay S. , Katzman Gregory L. 
Published: August 2002

AbstractDouble‐inversion fast spin‐echo (FSE) pulse sequences can be designed to provide excellent suppression of blood signal in black‐blood MRI. However, because a nonselective inversion is used, these sequences typically have been highly inefficient. In this work it is demonstrated that the efficiency of double‐inversion sequences can be greatly improved by a form of interleaving in which all of the slices to be imaged in a single pass are reinverted each time a signal is obtained from any single slice. To date, several studies have demonstrated a high level of blood suppression with these more efficient techniques. Magn Reson Med 47:1017– 1021, 2002. © 2002 Wiley‐Liss, Inc.
MRA of hemodialysis access grafts and fistulae using selective contrast injection and flow interruption
Authors: Bos Clemens , Smits Johannes H.M. , Zijlstra Jan J. , van der Mark Wil A.M.A. , Blankestijn Peter J. , Bakker Chris J.G. , Viergever Max A. , Mali Willem P.Th.M. 
Published: August 2002

AbstractMR is a potentially attractive modality for evaluating hemodialysis access anatomy and function. However, the wide range of flow rates in the hemodialysis access complicates interpretation of phase contrast, time‐of‐flight, and even contrast‐enhanced MR angiograms. At high flow rates, signal voids may easily arise at mild narrowings or sharp‐angled anastomoses. A method is proposed which visualizes hemodialysis accesses without flow artifacts. Diluted Gd‐DTPA is hand‐injected directly into the access, while a cuff is used to reduce and subsequently interrupt access flow. Filling of the access is monitored using a fast projection technique with complex subtraction. When filling is satisfactory, a 3D acquisition is started. The feasibility of this selective contrast‐enhanced MR angiography technique is demonstrated in four Cimino‐fistulae and four PTFE grafts. Magn Reson Med 45:557–561, 2001. © 2001 Wiley‐Liss, Inc.
Whole body detection and imaging of nitric oxide generation in mice following cardiopulmonary arrest: Detection of intrinsic nitrosoheme complexes
Authors: Kuppusamy Periannan , Shankar Ravi A. , Roubaud Valerie M. , Zweier Jay L. 
Published: August 2002

AbstractIschemic tissues generate nitric oxide (NO) by direct reduction of tissue nitrite under the acidic conditions that occur during ischemia. In view of the important implications of this enzyme‐independent mechanism of NO generation on the pathogenesis and treatment of tissue injury, the NO formation in mice subjected to cardiopulmonary arrest was measured and imaged. Real‐time measurement of NO generation was performed by detection of naturally generated NO‐heme complexes in tissues using L‐band electron paramagnetic resonance (EPR) spectroscopy. To distinguish NO generated from nitrite, animals were labeled with isotopically enriched 15N‐nitrite. Mice were infused with nitrite (70 mg/kg, intravenous), cardiopulmonary arrest induced by an overdose of phenobarbital, and transferred to the EPR resonator. Measurements of NO generation were performed on the intact animal at the levels of the head, thorax, and abdomen. At the end of 3 hr, major organs were isolated and analyzed for their NO signal. The NO complexes were found to have maximum levels in lung, heart, and liver. Three‐dimensional spatial mapping of the NO complex in the intact animal subjected to cardiopulmonary arrest was performed using EPR imaging techniques. The images also confirmed the maximum formation in the lungs, heart, and liver. The present data reveal that mice subjected to cardiopulmonary arrest generate large amounts of NO, which is nitrite mediated. The observed signal was largely due to heme‐bound NO, which accounted for the high concentrations found in these organs. This increased NO formation during cardiopulmonary arrest could contribute to the difficulty of resuscitation after long periods of arrest. Magn Reson Med 45:700–707, 2001. © 2001 Wiley‐Liss, Inc.
Detection of an intense resonance at 2.4 ppm in 1H MR spectra of patients with severe late‐delayed, radiation‐induced brain injuries
Authors: Yeung David K.W. , Chan Yu‐leung , Leung Sing‐fai , Poon Priscilla M.K. , Pang Chi‐pui 
Published: August 2002

AbstractProton MRS and MRI were used to monitor the progression of severe cerebral radiation injuries in 10 patients over a period of 18 months. An unknown resonance (Px) in the 2.37–2.40 ppm region was consistently detected in the affected temporal lobes of four patients. The detection of Px was only confined to spectra with lactate (Lac) and in patients with the highest severity grading of radiation injury. The incidence of Px in Lac‐positive spectra was 42.8% (15/35) and in lesions with highest injury grading was 46.8% (15/32). Lesions with Px had significantly higher Lac/creatine (Cr) ratios and more extensive mass effect changes when compared to lesions without Px. The probable identity of Px was examined in the context of anaerobic glycolysis producing pyruvate (2.37 ppm) and the model of metabolic changes in brain abscess formation implicating succinate (2.40 ppm). Magn Reson Med 45:994–1000, 2001. © 2001 Wiley‐Liss, Inc.
New devices to deliver somatosensory stimuli during functional MRI
Authors: Graham S.J. , Staines W.R. , Nelson A. , Plewes D.B. , McIlroy W.E. 
Published: August 2002

AbstractA new class of devices are described for improving investigation of somatosensory neuronal activation using fMRI. Dubbed magnetomechanical vibrotactile devices (MVDs), the principle of operation involves driving wire coils with small oscillatory currents in the large static magnetic field inherent to MRI scanners. The resulting Lorentz forces can be oriented to generate large vibrations that are easily converted to translational motions as large as several centimeters. Representative data demonstrate the flexibility of MVDs to generate different well‐controlled vibratory and tactile stimuli to activate special proprioceptive and cutaneous somatosensory afferent pathways. The implications of these data are discussed with respect to the literature on existing devices for producing sensorimotor activation, as well as expanding the scope of current fMRI investigations. Magn Reson Med 46:436–442, 2001. © 2001 Wiley‐Liss, Inc.
Sensitivity‐encoded spectroscopic imaging
Authors: Dydak Ulrike , Weiger Markus , Pruessmann Klaas P. , Meier Dieter , Boesiger Peter 
Published: August 2002

AbstractSensitivity encoding (SENSE) offers a new, highly effective approach to reducing the acquisition time in spectroscopic imaging (SI). In contrast to conventional fast SI techniques, which accelerate k‐space sampling, this method permits reducing the number of phase encoding steps in each phase encoding dimension of conventional SI. Using a coil array for data acquisition, the missing encoding information is recovered exploiting knowledge of the distinct spatial sensitivities of the individual coil elements. In this work, SENSE is applied to 2D spectroscopic imaging. Fourfold reduction of scan time is achieved at preserved spectral and spatial resolution, maintaining a reasonable SNR. The basic properties of the proposed method are demonstrated by phantom experiments. The in vivo feasibility of SENSE‐SI is verified by metabolic imaging of N‐acetylaspartate, creatine, and choline in the human brain. These results are compared to conventional SI, with special attention to the spatial response and the SNR. Magn Reson Med 46:713–722, 2001. © 2001 Wiley‐Liss, Inc.
Repetition time in echo planar functional MRI
Authors: Constable R. Todd , Spencer Dennis D. 
Published: August 2002

AbstractTo date, surprisingly little attention has been directed toward determining the optimum TR in a functional imaging experiment. A survey of the literature reveals a wide range of TRs, but little justification for a specific TR. Long‐TR functional imaging experiments provide maximum signal‐to‐noise ratio (SNR) in the raw images; allow for the collection of a large number of slice locations; and decrease the size of the data set acquired, simplifying storage and handling. This work, however, demonstrates that long‐TR imaging sacrifices statistical power when the paradigm timing is held fixed. That is, for a fixed‐run duration consisting of multiple activation/control blocks, shorter TR acquisitions (on the order of 1000 ms) provide better discrimination between the activated and nonactivated brain tissue regions than do long‐TR acquisitions (on the order of 4000 ms). Results are shown for modeling the functional imaging experiment and for three different paradigms performed on normal subjects. Magn Reson Med 46:748–755, 2001. © 2001 Wiley‐Liss, Inc.
Motor conduction studies in Miller Fisher syndrome with severe tetraparesis
Authors: Katsuno Masahisa , Ando Tetsuo , Hakusui Shigetaka , Yanagi Tsutomu , Sobue Gen 
Published: August 2002

AbstractSome patients with Miller Fisher syndrome (MFS) have a severe tetraparesis such as that observed in Guillain–Barré syndrome (GBS). To determine whether pathophysiologic differences exist between the tetraparesis in MFS and that in GBS, we compared clinical and motor conduction findings in 4 MFS patients who developed severe tetraparesis with those in 5 MFS patients without tetraparesis, and 14 GBS patients. MFS patients with or without tetraplegia had normal motor conduction velocities, distal motor latencies, compound muscle action potential (CMAP) amplitudes, and F‐wave latencies. CMAP amplitude tended to be lower in tetraparetic MFS patients than in MFS patients without tetraparesis, but not significantly. F‐wave occurrence was slightly reduced in 1 MFS patient with tetraparesis and 1 MFS patient without tetraparesis. Motor conduction parameters were abnormal in 13 of 14 patients with GBS, and showed demyelinating features in 10. Our results suggest that the pathophysiology of tetraparesis in MFS differs from that in GBS. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002