bluuebunny/crossref_metadata_2025 huggingface dataset:
Racial differences in the expression of cell cycle–regulatory proteins in breast carcinoma
Authors: Porter Peggy L. , Lund Mary Jo , Lin Ming Gang , Yuan Xiaopu , Liff Jonathan M. , Flagg Elaine W. , Coates Ralph J. , Eley J. William
Published: April 2004

BACKGROUND

African‐American (AA) women are more likely to be diagnosed with an advanced stage of breast carcinoma than are white women. After adjustment for disease stage, many studies indicate that tumors in AA women are more likely than tumors in white women are to exhibit a high level of cell proliferation and features of poor prognosis. The purpose of the current study was to compare tumor characteristics and cell cycle alterations in AA women and white women that might affect the aggressiveness of breast carcinoma.

METHODS

The study included 124 AA and 397 white women, ages 20–54 years. These women were enrolled in a case–control study in Atlanta, Georgia, between 1990 and 1992. Breast tumor specimens obtained from these women were centrally reviewed for histologic characteristics and evaluated for expression of estrogen and progesterone receptors (ER/PR), c‐ErbB‐2, Ki‐67, p53, cyclin E, cyclin D1, p27, p16, pRb, and p21 by immunohistochemistry. Logistic regression models were used to assess the age‐ and stage‐adjusted associations of various tumor characteristics with race.

RESULTS

The odds of a breast carcinoma diagnosis at a younger age and at a later stage were higher for AA women than for white women. After adjustment for disease stage and age at diagnosis, AA women also were found to have increased odds of having a higher‐grade tumor, a higher mitotic index, marked tumor necrosis, ductal histology, loss of ER and PR, overexpression of cyclin E, p16, and p53 and low expression of cyclin D1 at diagnosis.

CONCLUSIONS

The observed differences between tumor specimens obtained from AA women and tumor specimens obtained from white women, independent of stage and age at diagnosis, indicated that race may be a determinant, or a surrogate for other determinants, of aggressive breast carcinoma and specific cell cycle defects. Cancer 2004. Published 2004 American Cancer Society.
Inhibition of macrophage development and foreign body giant cell formation by hydrophilic interpenetrating polymer network
Authors: Collier Terry O. , Anderson James M. , Brodbeck William G. , Barber Thomas , Healy Kevin E.
Published: April 2004

The ability of monocytes to adhere, differentiate into macrophages, and fuse to form foreign body giant cells (FBGCs) on an implanted material surface is a critical step toward biomaterial degradation. Novel homogenous surfaces were utilized to mediate adhesion. These surfaces consisted of N‐(2 aminoethyl)‐3‐aminopropyltrimethoxysilane (EDS) and an interpenetrating polymer network (IPN) of polyacrylamide and poly(ethylene glycol). These surfaces were designed to control cell adhesion and morphology and mediate cell differentiation, activation, metabolic ability, and apoptosis, resulting in a reduced or controlled inflammatory response. The EDS surface promotes cell adhesion and the IPN minimizes protein adsorption and subsequent cell adhesion. Both surfaces had similar cellular adhesion rates at each respective time point. However, the adherent macrophage morphology was similar at 2 h and day 3, and at days 7 and 10 adherent macrophages on the EDS surface formed FBGCs (46% at day 7 and 40% at day 10). Adherent cells on the IPN surface did not form FBGCs but instead formed monocyte aggregates (73% of adherent cells formed aggregates at day 7 and 63% at day 10). It is indicated that the two surface chemistries differentially controlled monocyte differentiation into macrophages and subsequent macrophage fusion to form FBGCs. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 644–650, 2004
Tooth–composite interface from specific and nonspecific adhesive restorative systems
Authors: Haßhoff Gitte , Schneider Hartmut , Merte Knut
Published: April 2004

The aim of this in vitro study was to do a morphological comparison of tooth/composite interface by means of three composite systems: (1) a specific formulated primer adhesive and Organically Modified Ceramics (ORMOCER) composite, (2) an universal self‐etching adhesive and the same ORMOCER composite, (3) and the same universal adhesive used for Group 2 and a fine‐particle hybrid resin composite. The rational for this study was based on the recommendations from manufacturers that nonspecific dentin bonding agents can be used with ORMOCER. Twenty‐one Class II cavities were prepared in extracted third molars. Seven randomly assigned teeth were restored with one of the three methods according to the instructions provided by the manufacturer. Following completion of the restorations, the teeth were sectioned and evaluated by means of scanning electron microscopy for evaluation of interfacial morphology and light microscopy for the determination of microleakage. The last was scored as being present or absent. The best results were observed using method 1, in which a special primer adhesive and ORMOCER composite was used. In this group there were statistically significant fewer gaps in enamel (4.7± 7.5%) and dentin (22.8 ± 7.4%) compared to the other two groups (Group 2: enamel 21.1 ± 8.3% and dentin 66.3 ± 17.3%; and Group 3: enamel 40.6 ± 35.2% and dentin 89.4 ± 13.3%). The interfaceof method 2, universal self‐etching adhesive and ORMOCER, was of a lesser quality than Group 1. Within the limitations of this study the recommendation is made to use the ORMOCER tested in this experiment with the matching specifically formulated primer adhesive system. A lack of adhesion as well as microleakage, were prominent features for Groups 2 and 3. From the data of this study the practitioner is cautioned not to indiscriminately exchange specific dentin bonding agents for nonspecific ones. Considering the shear endless number of possible combinations and the numerous different tests that would be required to test these all, selection of different combinations will remain a theoretical exercise. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 38–45, 2004
Transperineal sonographic findings in a woman with urethral mucosa prolapse
Authors: Yang Jenn‐Ming , Huang Wen‐Chen
Published: April 2004

We present a case of urethral mucosa prolapse in a postmenopausal woman. Transperineal gray‐scale sonograms revealed a clover‐shaped, hypoechoic mass protruding from the urethral meatus. Doppler studies revealed blood flow within the protruding mass. Detection of feeding arteries and draining veins contributed to exclude the possibility of necrosis and gangrene, thus allowing conservative medical treatment to be tried. The mucosal prolapse regressed after 1 week's treatment with topical estrogen and antibiotics and sitz baths. Follow‐up sonograms showed a normal urethral configuration and diminished vascular flow when compared with the initial study. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:261–263, 2004; Published online in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/jcu.20026
Sonographic demonstration of duodenobiliary reflux with soda enhancement
Authors: Wu Chien‐Hsien , Chiu Han‐Mo , Liu Kao‐Lang , Lin Jaw‐Town , Wang Hsiu‐Po
Published: April 2004

Cholangitis rarely occurs after sphincteroplasty if there is no biliary obstruction. We report the case of a patient who developed recurrent cholangitis despite having a patent biliary tract after sphincteroplasty. Duodenobiliary reflux was demonstrated on sonography after enhancement of the reflux flow with a novel oral contrast agent, a carbonated soda beverage. Sonography with contrast enhancement provided by soda solution may prove satisfactory to detect duodenobiliary reflux after sphincteroplasty safely, effectively, and economically. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:249–252, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.20030
The role of polyadenylation signal secondary structures on the resistance of plasmid vectors to nucleases
Authors: Ribeiro Sofia C. , Monteiro Gabriel A. , Prazeres Duarte M. F.
Published: April 2004

Background

Nuclease degradation of plasmid DNA (pDNA) vectors after delivery and during trafficking to the nucleus is a barrier to gene expression. This barrier may be circumvented by shielding the pDNA from the nuclease‐rich cell environment with adjuvants or by using nuclease inhibitors. A different alternative that is explored in this work is to make pDNA vectors more nuclease‐resistant a priori.

Methods and results

The hypothesis that a significant part of nuclease attack is directed towards certain labile sequences in a pDNA model (pVAX1/lacZ) was first tested. Homopurine‐rich tracts in the bovine growth hormone polyadenylation signal (BGH poly A) were identified as labile sequences using S1 nuclease as a probe. Two pDNA variants were then created by replacing the BGH poly A region with the SV40 or a synthetic poly A signal. A study of plasmid degradation in eukaryotic cell lysates and mice plasma showed that the half‐life of the supercoiled isoforms of the new vectors was always higher when compared with the control plasmid. An in vitro assay of the reporter β‐galactosidase in transfected CHO cells further showed that gene expression with the new pDNA variants was not affected negatively by the plasmid modifications.

Conclusions

The replacement of labile sequences in plasmid DNA vectors improves resistance towards nuclease attack as shown by the increased half‐lives of supercoiled plasmid isoforms incubated with endo/lysosomal, cytoplasmatic and blood plasma enzymes. Copyright © 2004 John Wiley & Sons, Ltd.
Dependent edges in Mycielski graphs and 4‐colorings of 4‐skeletons
Authors: Collins Karen L. , Tysdal Kimberly
Published: April 2004

A dependent edge in an acyclic orientation of a graph is one whose reversal creates a directed cycle. In answer to a question of Erdös, Fisher et al. [5] define dmin(G) to be the minimum number of dependent edges of a graph G, where the minimum is taken over all acyclic orientations of G, and also rm,k as the supremum of the ratio dmin(G)/e(G), where e(G) is the number of edges in G and the supremum is taken over all graphs G with chromatic number m and girth k. They show that $r_{m,k}\le (m-2)/m$ and r4,4 ≥ 1/20. We show that r5,4 ≥ 4/71, r6,4 ≥ 7/236, and r7,4 ≥ 11/755 and that the Mycielski construction on a triangle‐free graph with at least one dependent edge yields a graph with at least three dependent edges. In addition, we give an alternative proof of the answer to Erdös's question, based on Tysdal [6] and Youngs [7]. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 285–296, 2004
Volatile organic compound permeation through porous polymeric films for modified atmosphere packaging of foods
Authors: Del‐Valle Valeria , Almenar Eva , Hernández‐Muñoz Pilar , Lagarón José M , Catala Ramón , Gavara Rafael
Published: April 2004

The use of perforated packaging films is increasing with the application of modified atmosphere packaging (MAP) to fresh produce. These films provide high to very high mass exchange rates which usefully allow oxygen ingress and carbon dioxide exit. However, the use of porous films also increases the loss of other food volatile components through similar processes. In this paper we present data on the permeation through porous films of several organic compounds found in many fruits and vegetables. The results are compared with those predicted by theoretical equations describing pore permeation processes. A discussion on the significance of these very high permeation values for product quality is also presented through the analysis of ethanol concentration evolution during MAP of mandarin segments. It was found that the barrier effectiveness of the fruit cuticle and the elevated partition coefficient of the organic compounds between the fruit (flesh) and the headspace appear to be responsible for the reduced food aroma compound loss. Copyright © 2004 Society of Chemical Industry
Effect of α‐tocopherol and α‐tocotrienol on the performance of Chilean hazelnut oil (Gevuina avellana Mol) at high temperature
Authors: Romero Nalda , Robert Paz , Masson Lilia , Ortiz Jaime , Pavez Jacquelinne , Garrido Carolina , Foster Mariela , Dobarganes Carmen
Published: April 2004

The high temperature antioxidant efficiency of α‐tocopherol, α‐tocotrienol and a mixture of both on hazelnut oil were evaluated. Crude hazelnut oil (HZO), crude hazelnut oil treated with alumina (THZO), as well as three samples of THZO to which 150 mg kg−1 of α‐tocopherol, 140 mg kg−1 of α‐tocotrienol or a mixture containing 70 mg kg−1 of α‐tocopherol and 70 mg kg−1 of α‐tocotrienol, were added and submitted to thermal treatment at 180°C for 18 h. The addition of tocols to THZO decreased the formation of polar compounds and increased its oxidative stability in all the systems studied. However, α‐tocopherol showed a higher antioxidant capacity than α‐tocotrienol at high temperature. In addition, α‐tocotrienol showed a more rapid degradation rate than α‐tocopherol under the conditions studied. Copyright © 2004 Society of Chemical Industry
Synthesis of branched polyethylene by ethylene homopolymerization using titanium catalysts that contain a bridged bis(phenolate) ligand
Authors: Capacchione Carmine , Proto Antonio , Okuda Jun
Published: April 2004

The synthesis of branched polyethylene from single ethylene feed has been achieved by using a methylaluminoxane‐activated titanium complex bearing a tetradentate bis(phenolate) ligand with a 1,4‐dithiabutanediyl bridge 1. This catalyst produces polyethylene with activities up to 6200 kg polymer/mol h bar. As evidenced by 13C NMR analyses, the polyethylenes contain ethyl, n‐butyl, and long‐chain (n‐hexyl or longer) branches in a range variable from 0.2 to 2.0%, depending on the experimental parameters. NMR and gas chromatography/mass spectrometry analyses suggest that such polymer microstructure arises from the in situ production of oligomers and their subsequent incorporation into the growing polyethylene chain. The broad molecular weight distribution of these polyethylenes indicates the presence of different catalytic species. The related catalyst system 2 bearing a longer 1,5‐dithiapentanediyl bridge produces linear polyethylene with moderate activity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2815–2822, 2004
The cis‐pro touch‐turn: A rare motif preferred at functional sites
Authors: Videau Lizbeth L. , Arendall W. Bryan , Richardson Jane S.
Published: April 2004

A new motif of three‐dimensional (3D) protein structure is described, called the cis‐Pro touch‐turn. In this four‐residue, three‐peptide motif, the central peptide is cis. Residue 2, which precedes the proline, has ϕ, ψ values either in the “prePro region” of the Ramachandran plot near −130°, 75° or in the Lα region near +60°, +60°. The Cα(1)–Cα(4) distance is 4–5 Å and the two flanking peptides lie parallel to one another, making van der Waals contact rather than a hydrogen bond. Apparently, this arrangement is locally unfavorable and therefore rare, usually occurring only if needed for biological function. Of the 12 examples in a 500‐protein database, cis‐Pro touch‐turns are found at the catalytic sites of pectate lyase, Ni‐Fe hydrogenase, glucoamylase, xylanase, and opine dehydrogenase and at the primary binding sites of ribonuclease H, type I DNA polymerase, ribotoxin, and phage gene 3 protein. In each of these protein families, the touch‐turns serve different roles; their functional importance is supported by conservation and mutagenesis data. In analyzing the conservation patterns of these 3D motifs, new methods for in‐depth quality evaluation of the structural bioinformatic data are employed to distinguish between significant exceptions and errors. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Predicted role for the archease protein family based on structural and sequence analysis of TM1083 and MTH1598, two proteins structurally characterized through structural genomics efforts
Authors: Canaves Jaume M.
Published: April 2004

Recently, the structures of two proteins belonging to the archease family, TM1083 from Thermotoga maritima and MTH1598 from Methanobacterium thermoautotrophicum, have been solved independently by two Protein Structure Initiative structural genomics pilot centers using X‐ray crystallography and NMR, respectively. The archease protein family is a good example of one of the paradoxes of structural genomics: Approximately one third of protein structures produced by structural genomics centers have no known function and are still annotated as “hypothetical proteins” in the Protein Data Bank. In the case of archeases, despite the existence of two protein structures and abundant sequence information, there is still no function assigned to this protein family. Here, our group predicts, based on structural similarity, sequence conservation, and gene context analyses, that members of this protein family might function as chaperones or modulators of proteins involved in DNA/RNA processing. The conservation of genomic context for this protein family is constant from Archaea and Bacteria to humans, and suggests that unannotated open reading frames contiguous to them could be novel RNA/DNA binding proteins. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Ab initio study of the CH3O2 self‐reaction in gas phase: Elucidation of the CH3O2 CH3O2 → 2CH3O O2 pathway
Authors: Feria L. , Gonzalez C. , Castro M.
Published: April 2004

Ab initio electronic structure calculations have been performed to determine the mechanism governing the 2CH3O2 → 2CH3O + O2 chemical reaction in gas phase. Geometry optimizations for reactants, intermediates, transition states, and products were performed at the MP2 level of theory with the 6‐311G(2d,2p) basis sets. Further, PMP4(SDTQ)/6‐311G(3df,2p) single‐point calculations were performed on the previous MP2/6‐311G(2d,2p)‐optimized geometries. For the past 50 years, it has been proposed that the production of CH3O and O2 in the self‐reaction of methylperoxyl radicals is the result of the direct dissociation of a noncyclic tetraoxide intermediate via a concerted mechanism involving a single step. Our theoretical results indicate that the reaction path is more complex than expected. We found that the reaction proceeds through a nonconcerted mechanism involving two tetraoxide intermediates that have different geometries and relative energies. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Wiener polynomials of some chemically interesting graphs
Authors: Yang Bo‐Yin , Yeh Yeong‐Nan
Published: April 2004

The chemist Harold Wiener found 𝒲(G), the sum of distances between all pairs of vertices in a connected graph G, to be useful as a predictor of certain physical and chemical properties. The q‐analogue of 𝒲, called the Wiener polynomial 𝒲(G; q), is also useful, but it has few existing useful formulas. We will evaluate 𝒲(G; q) for certain graphs G of chemical interest. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Paramagnetic NMR study of Cu2+–IDA complex localization on a protein surface and its application to elucidate long distance information
Authors: Nomura Makoto , Kobayashi Toshitatsu , Kohno Toshiyuki , Fujiwara Kenichiro , Tenno Takeshi , Shirakawa Masahiro , Ishizaki Itsuko , Yamamoto Kazuo , Matsuyama Toshifumi , Mishima Masaki , Kojima Chojiro
Published: April 2004

The paramagnetic metal chelate complex Cu2+‐iminodiacetic acid (Cu2+–IDA) was mixed with ubiquitin, a small globular protein. Quantitative analyses of 1H and 15N chemical shift changes and line broadenings induced by the paramagnetic effects indicated that Cu2+–IDA was localized to a histidine residue (His68) on the ubiquitin surface. The distances between the backbone amide proton and the Cu2+ relaxation center were evaluated from the proton transverse relaxation rates enhanced by the paramagnetic effect. These correlated well with the distances calculated from the crystal structure up to 20 Å. Here, we show that a Cu2+–IDA is the first paramagnetic reagent that specifically localizes to a histidine residue on the protein surface and gives the long‐range distance information.
Four Seychelles lichens new to science
Authors: SEAWARD Mark R. D. , APTROOT André
Published: April 2004

Illustrated descriptions are provided for four new lichen species found in The Seychelles: Arthothelium feuereri Aptroot & Seaward, Dimerella straminea Aptroot & Seaward, D. subsquamosa Aptroot & Seaward and Fellhanera silhouettae Aptroot & Seaward.
Micarea subalpina Coppins & Spribille, a new subalpine species from the Rocky Mountains, USA
Authors: COPPINS Brian J. , SPRIBILLE Toby
Published: April 2004

Micarea subalpina sp. nov. is described from plant detritus in subalpine forest parkland in the mountains of western Montana (USA). It has similarities to M. assimilata and M. erratica.
A new eight-spored species of Menegazzia from Australia
Authors: KANTVILAS Gintaras , LOUWHOFF Simone
Published: April 2004

The new species, Menegazzia jamesii Louwhoff & Kantvilas from Victoria and Tasmania, closely related to M. pertransita (Stirt.) R. Sant., is described. Chemical and nomenclatural notes on M. caliginosa P. James & D. J. Galloway and M. pertransita are provided, and the new combination, M. stirtonii (Zahlbr.) Kantvilas & Louwhoff, is proposed. The name M. weindorferi (Zahlbr.) R. Sant., widely applied in Australian literature, is considered synonymous with M. pertransita, whereas M. bullata (Stirt.) Bitter is considered a synonym of M. stirtonii.
PLASTID INHERITANCE IN STREPTOCARPUS (GESNERIACEAE) AND AN INFERRED HYBRID ORIGIN FOR A POPULATION OF S. AFF. PRIMULIFOLIUS FROM IGODA RIVER, SOUTH AFRICA
Authors: MÖLLER M. , BROOKS K. J. , HUGHES M.
Published: April 2004

A length polymorphism in the trnL/trnF intergenic spacer was used as a marker to determine the mode of chloroplast inheritance in Streptocarpus (Gesneriaceae). Exclusively maternal inheritance was recorded for all the F1 progeny of reciprocal intraspecific crosses between S. primulifolius and a population referred to as S. aff. primulifolius from the Igoda River mouth, Eastern Cape, South Africa, and for interspecific crosses between S. rexii and S. dunnii. A combination of molecular and morphological data was used to clarify the origin of S. aff. primulifolius, which possesses S. rexii-type cpDNA and rDNA, while the morphological data suggest an intermediate position between S. rexii and S. primulifolius. The distribution of S. rexii and S. primulifolius, combined with molecular and morphological data, supports the hypothesis that the S. aff. primulifolius population is a hybrid between S. rexii and S. primulifolius, with S. rexii as the maternal parent, and that substantial molecular but limited morphological introgression into S. primulifolius has taken place.
The 1997–1998 Umbria‐Marche sequence (central Italy): Source, path, and site effects estimated from strong motion data recorded in the epicentral area
Authors: Bindi D. , Castro R. R. , Franceschina G. , Luzi L. , Pacor F.
Published: April 2004

We apply a nonparametric spectral inversion scheme to calculate source spectra, S wave attenuation, and site transfer functions from strong motion records in the epicentral region of the 1997–1998 Umbria‐Marche seismic sequence (central Italy). We use records from moderate size earthquakes (4.6 ≤ Ml ≤ 5.9) to parameterize the spectral amplitude decay in the distance range from 5 to 40 km. We find that the average quality factor Q can be approximated by Q(f) = 49 f0.9, between 0.5 and 8 Hz, and the geometrical spreading by r−0.9. At high frequencies (f > 8 Hz) the dependence of Q on frequency weakens, and it takes an approximate constant value of 318. We fit the source spectra to the ω‐square model and calculate an average stress drop of (2 ± 1) MPa. The average value is consistent with the previous estimates from the weak events (1.4 < Ml < 4.5) of the Umbria‐Marche seismic sequence. The most remarkable site effects are found in correspondence of large sedimentary basins, filled by alternation of sandy‐clayey deposits. The estimated spectral parameters are used to simulate acceleration spectra recorded during several earthquakes of the Umbria‐Marche sequence. Both point source and finite fault effects are considered. Furthermore, attenuation relationships for peak ground velocity and ground acceleration are estimated using synthetic data, and compared to existing relationships.
First Place—Resident Clinical Science Award 1998: Parents cannot detect mild hearing loss in children
Authors: Brody Robin , Rosenfeld Richard M. , Goldsmith Ari J. , Madell Jane R.
Published: April 2004

Otitis media with effusion is among the most common illnesses of childhood and is often associated with chronic or persistent middle ear effusion (MEE). Our goal was to develop and validate a self‐administered parent survey that would identify children at high risk for mild hearing loss caused by MEE. We evaluated 115 children. Parents rated their child's hearing using the HL‐7, a 7‐item self‐administered survey, and a global visual‐analog scale. Static admittance and gradient were recorded. Test‐retest reliability, internal consistency, and validity of the HL‐7 were compared with the 4‐frequency pure‐tone average (PTA) hearing level (HL) for the better hearing ear. The HL‐7 had good test‐retest reliability and internal consistency. Survey scores correlated well with the global hearing rating (R = 0.67, P < 0.001) but did not correlate with PTA (R = 0.10, P = 0.29). Tympanometric gradient was unrelated to ear‐specific PTA, but not abnormal static admittance (<0.2 cc), which produced a mean 7‐dB HL decrease in hearing (ANOVA, P = 0.02). The HL‐7 is a reliable and internally consistent measure of parent perception of child hearing, but unfortunately these perceptions are inaccurate for mild hearing loss. Abnormal static admittance is a risk factor for hearing loss.
Diplophonia in unilateral vocal fold paralysis and intracordal cyst
Authors: Hong Ki Hwan , Kim Hyun Ki
Published: April 2004

Diplophonia is the production by the voice of 2 separate tones through quasiperiodic variations in the vocal fold vibration (Ward PH, Moore GP. Ann Otol Rhinol Laryngol 1969;78:771‐7). Clinically, diplophonia can be observed in patients with unilateral vocal fold paralysis with incomplete glottal closure and a mass lesion of the vocal fold, intracordal cyst, and granuloma (Kiritani S, et al. Ann Bull RILP 1991; 25:55‐62; Hirano M, et al. Ann Otol Rhinol Laryngol 1989;98:791‐5). In this study we report 16 subjects with unilateral vocal cord paralysis or an intracordal cyst characterized perceptually by diplophonia. Diplophonia during tension imbalance may occur after surgery and is characterized by an improved perceptual score, a reduced number of vibratory cycles in each quasiperiodic waveform, and a reduced occurrence rate of the diplophonic waveform. During mass imbalance, no diplophonia occurred after surgery. Regarding the relationship of diplophonia with glottal condition at production of stops, in our study diplophonia varied significantly according to the different phonologic environments of stops during tension imbalance. We presume that there is a close relationship between the occurrence of diplophonia and the glottal conditions in tension imbalance, but not in mass imbalance.
Airway Abnormalities in Patients with Arnold‐Chiari Malformation
Authors: Choi Sukgi S. , Tran Lenhanh P. , Zalzal George H.
Published: April 2004

OBJECTIVES

The goal was to determine the incidence and types of airway abnormalities in patients with Arnold‐Chiari malformation (ACM).

METHODS

The study was a retrospective chart review of 24 patients with ACM who were evaluated and treated between November 1991 and August 1997.

RESULTS

Eighteen (75%) and 6 (25%) of the 24 patients had types I and II ACM, respectively. Three (12.5% of 24 patients) of the type II ACM patients had vocal cord impairment: 1 bilateral paralysis, 1 bilateral paresis, and 1 unilateral paralysis. None of the type I ACM patients had vocal cord impairment. Tracheotomy was necessary in 3 of the 24 patients and all in patients with type II ACM. Central sleep apnea was found in 5 of 6 type II ACM patients, but not in any of the type I ACM patients.

CONCLUSIONS

Vocal cord impairment and sleep apnea were found in 12.5% and 21%, respectively, of this ACM Population. When type II ACM patients were considered separately, the incidences of vocal cord impairment and sleep apnea were 50% and 83%, respectively. Type II ACM patients tend to have a higher incidence of airway abnormalities and other neurologic dysfunctions. Flexible fiberoptic laryngoscopy is recommended in the airway evaluation of ACM patients. Early recognition, diagnosis, and management of these abnormalities may be lifesaving.
Interferon in the treatment of base of the skull hemangioendothelioma
Authors: Freeman A. I. , Lossos A. , Gomori J. M. , Schwartz A. , Elidan J. , Siegal T.
Published: April 2004

Hemangioendothelioma is an uncommon vascular tumor that falls between hemangioma and angiosarcomas in behavior and appearance. These tumors may occur anywhere in the body, even very rarely in the brain.1 In certain locations, when not excisable, they may threaten the life of the patient because they are slowly progressive in nature. The base of the brain is such a location. In the past, when a hemangioendothelioma could not be excised, various approaches were used with limited success. Recently, α‐interferon has been reported to be successful in the treatment of this tumor.1‐3 We present a 3‐year‐old child with an extensive hemangioendothelioma arising at the base of the skull that responded dramatically to prolonged administration of α‐interferon.
Electrodynamics of the magnetosphere–ionosphere coupling in the nightside subauroral zone
Authors: Streltsov A. V. , Foster J. C.
Published: April 2004

Results from a numerical study of the oscillations of the electric field measured by the Millstone Hill incoherent scatter radar in the E-layer of the nightside subauroral ionosphere during the geomagnetic storm of May 25, 2000 are presented. The frequencies of these oscillations correspond to the discrete frequencies of geomagnetic pulsations usually attributed to the field line resonances or global cavity modes at a high-latitude auroral zone, but they are well below the fundamental eigenfrequency of the subauroral magnetosphere. It is shown that these oscillations can be interpreted as an ionospheric footprint of the surface Alfvén waves generated at the equatorial magnetosphere on a steep transverse gradient in the background plasma density associated with the inner edge of the plasmapause developed during strong geomagnetic storms/substorms. This density gradient together with the ionospheric Pedersen conductivity defines the location and amplitude of the electric field in the E-layer: the amplitude of the field is proportional to the amplitude of the density inhomogeneity and inversely proportional to its scale-size and the ionospheric conductivity. Interaction of the large amplitude perpendicular electric field with the low-conducting ionosphere can cause the ionospheric feedback instability, which leads to the formation of small-scale, intense structures in the electric field and the parallel current density in the subauroral magnetosphere.
Interpretation of Cluster data on chorus emissions using the backward wave oscillator model
Authors: Trakhtengerts V. Y. , Demekhov A. G. , Titova E. E. , Kozelov B. V. , Santolik O. , Gurnett D. , Parrot M.
Published: April 2004

The measurements of chorus emissions by four closely separated Cluster spacecraft provide important information concerning the chorus generation mechanism. They confirm such properties of the wave source as their strong localization near the equatorial cross section of a magnetic flux tube, an almost parallel average wave-vector direction with respect to the geomagnetic field, and an energy flux direction pointing outward from the generation region. Inside this region, Cluster discovered strong temporal and spatial variations in the amplitude with correlation scale lengths of the order of 100 km across the magnetic flux. The wave electric field reached 30 mV/m, and the maximum growth and damping rates are of the order of a few hundreds of s−1. These and other properties of the detected chorus emissions are discussed here in relation with the backward wave oscillator mechanism. According to this mechanism, a succession of whistler wave packets is generated in a small near-equatorial region with temporal and spatial characteristics close to the Cluster data. Amplitudes and frequency spectra, as well as dynamical features of the Poynting flux of chorus are estimated and compared with the Cluster measurements.
Wavelet analysis of magnetic turbulence in the Earth’s plasma sheet
Authors: Vörös Z. , Baumjohann W. , Nakamura R. , Runov A. , Volwerk M. , Zhang T. L. , Balogh A.
Published: April 2004

Recent studies provide evidence for the multiscale nature of magnetic turbulence in the plasma sheet. Wavelet methods represent modern time series analysis techniques suitable for the description of statistical characteristics of multiscale turbulence. Cluster FGM (fluxgate magnetometer) magnetic field high-resolution (67 Hz) measurements are studied during an interval in which the spacecraft are in the plasma sheet. As Cluster passes through different plasma regions, physical processes exhibit nonsteady properties on magnetohydrodynamic (MHD) and small, possibly kinetic scales. As a consequence, the implementation of wavelet-based techniques becomes complicated due to the statistically transitory properties of magnetic fluctuations and finite size effects. Using a supervised multiscale technique which allows existence test of moments, the robustness of higher-order statistics is investigated. On this basis the properties of magnetic turbulence are investigated for changing thickness of the plasma sheet.
On the poloidal localization and stability of multi-faceted asymmetric radiation from the edge (MARFE)
Authors: Chankin A. V.
Published: April 2004

A possible explanation for differences in the behavior of multi-faceted asymmetric radiation from the edge (MARFE) in normal and reversed toroidal field configurations, based on the influence of poloidal E×B drift, is offered. The poloidal E×B drift creates poloidal rotation that tends to shift the MARFE away from its stable position near the inner midplane. For a neoclassical radial electric field (Er≡−dΦ/dr<0), and in normal toroidal field configurations (ion ∇B drift towards the X-point), the E×B poloidal rotation shifts the MARFE towards another stable position, near the X-point. In the reversed toroidal field configurations (ion ∇B drift away from the X-point), the E×B poloidal rotation is shifting the MARFE away from the X-point. These trends are in agreement with experimental observations.
Acceleration of positrons by a relativistic electron beam
Authors: Shokri B. , Khorashadizadeh S. M.
Published: April 2004

By making use of the dispersion relation and obtaining the growth rate and threshold for the instability development of a fully magnetized electron–positron beam plasma the acceleration of positrons by a relativistic electron beam is investigated. Furthermore, by comparing the Cherenkov and cyclotron acceleration mechanisms the dependence of the positrons acceleration on the plasma parameters and the magnetic field strength is studied.
Semiclassical theory of electronically nonadiabatic chemical dynamics: Incorporation of the Zhu–Nakamura theory into the frozen Gaussian propagation method
Authors: Kondorskiy A. , Nakamura H.
Published: April 2004

The title theory is developed by combining the Herman–Kluk semiclassical theory for adiabatic propagation on single potential-energy surface and the semiclassical Zhu–Nakamura theory for nonadiabatic transition. The formulation with use of natural mathematical principles leads to a quite simple expression for the propagator based on classical trajectories and simple formulas are derived for overall adiabatic and nonadiabatic processes. The theory is applied to electronically nonadiabatic photodissociation processes: a one-dimensional problem of H2+ in a cw (continuous wave) laser field and a two-dimensional model problem of H2O in a cw laser field. The theory is found to work well for the propagation duration of several molecular vibrational periods and wide energy range. Although the formulation is made for the case of laser induced nonadiabatic processes, it is straightforwardly applicable to ordinary electronically nonadiabatic chemical dynamics.
Nonlinear behavior of resistive pressure driven modes in stellarator/heliotron plasmas with vacuum magnetic islands
Authors: Unemura T. , Hamaguchi S. , Wakatani M.
Published: April 2004

Effects of externally applied vacuum magnetic islands (VMIs) on nonlinear saturation levels of resistive pressure driven modes in stellarator/heliotron plasmas are examined with the use of three-dimensional nonlinear time-evolution simulations for cylindrical plasmas. The simulation code is based on reduced magnetohydrodynamics equations and the equations are discretized by the finite element method in the poloidal cross section and Fourier expansion in the toroidal direction. It is shown that the growth of magnetic islands in a plasma can be controlled by an external perturbational magnetic field that generates VMIs.
Diffusion and trapping in a suspension of spheres with simultaneous reaction in the continuous phase
Authors: Vaughn Mark W.
Published: April 2004

Much progress has been made in modeling the reaction of Brownian particles with spherical traps. Previously, work has focused on the effective reaction rate of systems of particles that diffuse freely until they are trapped by spheres in the dispersion. A particularly effective and efficient method to describe the reacting system is based on first-passage time distributions, from which an effective reaction rate coefficient of the suspension can be determined. The analysis presented here addresses reaction and diffusion in systems in which particles can undergo reaction in the continuous phase as well as reaction at the sphere surface. The first-passage method is extended to allow reaction or decay of the diffusing species in the continuous phase. The diffusion path is divided into a series of first-passage regions and is considered the probability of the particle being consumed in each of these regions. This allows the determination of the total reaction rate of the suspension (continuous phase reaction plus trapping) and the relative consumption rate in each phase. The extended method is applied to a model system of concentric spheres with a known continuum solution. It is shown to be accurate for consumption of reactant in the continuous phase from ≈0 to ≈100%. The method then is applied to a suspension of spheres.
Second-order nonlinear optical coefficient of polyphosphazene-based materials: A theoretical study
Authors: Jacquemin Denis , Quinet Olivier , Champagne Benoı̂t , André Jean-Marie
Published: April 2004

The second-order nonlinear optical coefficient of polyphosphazene oligomers of increasing size has been determined by using ab initio methods taking into account electron correlation and frequency dispersion effects. The calculated first hyperpolarizability per unit cell converges rapidly with respect to chain length. It attains an amplitude of about one-third of the one of classical push–pull systems. This amplitude can be strongly increased by replacing the nitrogen of the backbone by silicon. The effects of the side groups (H, CH3, F, Cl, Br, and OH) on the first hyperpolarizability have been investigated as well. The different results have been rationalized in terms of alternations of bond lengths and atomic charges.
Kinetic theory of radio frequency quadrupole ion traps. I. Trapping of atomic ions in a pure atomic gas
Authors: Viehland Larry A. , Goeringer Douglas E.
Published: April 2004

A kinetic theory based on the Boltzmann equation is developed for the trapping of atomic ions in a radio-frequency quadrupole ion trap containing enough neutral atoms that ion-neutral collisions cannot be ignored. The collisions are treated at the same level of sophistication and detail as is used to deal with the time- and space-dependent electric fields in the trap. As a result, microscopic definitions are obtained for the damping and stochastic forces that originate from such collisions. These definitions contrast with corresponding phenomenological terms added ad hoc in previous treatments to create damped Mathieu and Langevin equations, respectively. Furthermore, the theory indicates that either collisional cooling or heating of the ions is possible, depending upon details of the ion-neutral mass ratios and interaction potential. The kinetic theory is not dependent on any special assumptions about the electric field strengths, the ion-neutral interaction potentials, or the ion-neutral mass ratio. It also provides an ab initio way to describe the ion kinetic energies, temperatures, and other properties by a series of successive approximations.
On the structural and transport properties of the soft sticky dipole and related single-point water models
Authors: Fennell Christopher J. , Gezelter J. Daniel
Published: April 2004

The density maximum and temperature dependence of the self-diffusion constant were investigated for the soft sticky dipole (SSD) water model and two related reparametrizations of this single-point model. A combination of microcanonical and isobaric–isothermal molecular dynamics simulations was used to calculate these properties, both with and without the use of reaction field to handle long-range electrostatics. The isobaric–isothermal simulations of the melting of both ice-Ih and ice-Ic showed a density maximum near 260 K. In most cases, the use of the reaction field resulted in calculated densities which were significantly lower than experimental densities. Analysis of self-diffusion constants shows that the original SSD model captures the transport properties of experimental water very well in both the normal and supercooled liquid regimes. We also present our reparametrized versions of SSD for use both with the reaction field or without any long-range electrostatic corrections. These are called the SSD/RF and SSD/E models, respectively. These modified models were shown to maintain or improve upon the experimental agreement with the structural and transport properties that can be obtained with either the original SSD or the density-corrected version of the original model (SSD1). Additionally, a novel low-density ice structure is presented which appears to be the most stable ice structure for the entire SSD family.
Are insertion compounds of CH2CHF and the rare gases stable? A computational study
Authors: McDowell Sean A. C.
Published: April 2004

Ab initio calculations, using second-order Møller–Plesset perturbation theory with a 6-311++G(2d,2p) basis set, predict the stability of two novel compounds of monofluoroethene, CH2CHF, with the rare-gas atoms Ar and Kr. The dissociation energies to the lowest-energy fragmentation products, CH2CHF+Rg (Rg=Ar,Kr), were computed to be −528 and −449 kJ mol−1, respectively, at the coupled-cluster singles, doubles, and triples level of theory. Possible transition states (at second-order Møller-Plesset theory) via a C–Rg–F bending mode for these fragmentation reactions were also located with barrier heights of about 76 and 106 kJ mol−1, for the Ar- and Kr-containing species, respectively. However, the Ar-containing species may not exist at all as it is less stable than the fragments CH2CH+F+Ar at the higher level of theory and may possibly dissociate via this route.
Thermally activated escape rate for the Brownian motion of a fixed axis rotator in a double well potential for all values of the dissipation
Authors: Coffey William T. , Kalmykov Yuri P. , Titov Sergey V.
Published: April 2004

The extension of the Kramers theory of the escape rate of a Brownian particle from a potential well to the entire range of damping proposed by Mel’nikov and Meshkov [J. Chem, Phys. 85, 1018 (1986)] is applied to the rotational Brownian motion of fixed axis rotators in a double well cosine potential. The procedure yields an expression for the Kramers escape rate valid for all values of the dissipation including the very low damping (VLD), very high damping (VHD), and crossover regimes. This equation provides a good asymptotic estimate of the correlation time τ∥ of the longitudinal dipole moment correlation function calculated by solving the underlying Langevin equation using the matrix-continued fraction method. Moreover, for low barriers, where the Mel’nikov and Meshkov approach is not applicable, analytic equations for τ∥ in the VLD and VHD limits are derived and a simple extrapolating equation that is valid for all values of the damping is proposed.
Diffusion-influenced reversible geminate recombination in one dimension. III. Field effect on the excited-state reaction
Authors: Kim Hyojoon , Shin Kook Joe
Published: April 2004

We obtain exact analytic solutions of the diffusion-influenced excited-state reversible geminate recombination reaction, A*+B↔(AB)*, with two different lifetimes and quenching under the influence of a constant external field in one dimension. These fundamental solutions generalize two previous results [Kim et al., J. Chem. Phys. 111, 3791 (1999); 114, 3905 (2001)] and provide us with the insight necessary to analyze their specific relations and asymptotic kinetic transition behaviors. We find that the number of kinetic transitions can be changed due to interplay between the field strength and lifetimes. Unlike the previous works, the number of lifetime dependent transitions is found to be one or zero. On the other hand, the number of the field dependent transitions becomes two, one, or zero. We find a new pattern of kinetic transition et→t−1/2→et when there is only one field dependent transition.
Lifetime and predissociation yield of N214 b 1Πu(v=1)
Authors: Sprengers J. P. , Ubachs W. , Johansson A. , L’Huillier A. , Wahlström C.-G. , Lang R. , Lewis B. R. , Gibson S. T.
Published: April 2004

The lifetime of the b 1Πu(v=1) state in N214 has been determined experimentally using a laser-based pump–probe scheme and an exceptionally long lifetime of 2.61 ns was found. Semiempirical close-coupling calculations of the radiative lifetime, which include Rydberg–valence interactions in the singlet manifold, are consistent with this large value, giving a value of 3.61 ns and suggesting a predissociation yield of ∼28% for this level of the b state.
“Triplet-excited region” in polyene oligomers revisited: Pariser–Parr–Pople model studied with the density matrix renormalization group method
Authors: Ma Haibo , Liu Chungen , Jiang Yuansheng
Published: April 2004

We have carried out density matrix renormalization group calculations on the T1 state of linear polyenes applying the Pariser–Parr–Pople (PPP) Model. The geometry optimization for the polyene oligomers C2nH2n+2 (n=4,5,6,…,15) shows that the S0 to T1 excitation region is composed of a soliton–antisoliton pair located symmetrically away from the center of the chain and leads to single- and double-bond interconversions in between. The distance between the soliton and antisoliton centers in T1 state changes with the length of the chain, contradictory to earlier conclusions obtained with PPP-SDCI or ab initio SCI methods. The inconsistency most possibly comes from the insufficient consideration of the electron correlations in small-scale CI methods.