bluuebunny/crossref_metadata_2025_split huggingface dataset:
C‐Met Overexpression in Supraglottic Laryngeal Squamous Cell Carcinoma and its Relation to Lymph Node Metastases
Authors: Taskin Yücel Ö , Sungur Arzu , Kaya Sefa 
Published: June 2004

BACKGROUNDThe c‐met oncogene encodes the receptor for the hepatocyte growth factor/scatter factor (HGF/SF), which is known to have the effects of stimulation of cell motility, dissociation of epithelial sheets, invasion of cellular matrix, and induction of angiogenesis. Many studies in solid tumors have indicated a role for c‐met and HGF/SF in the progression of the disease.METHODSThe expression of c‐met in tissue specimens was studied by immunohistochemical examination in 60 patients with supraglottic laryngeal squamous cell carcinoma. Patients were chosen such that there were 30 with lymph node metastases in the neck and 30 without metastases. TNM staging, differentiation, lymphovascular and perineural invasion, and growth pattern for tumors were also recorded, and their relation to lymph node metastases was analyzed.RESULTSOverexpression of c‐met was observed in 90% of the cases at the primary site and in 83% of the cases with lymph node metastases in the neck. Lymphovascular invasion (P = 0.005) and the N stage (P = 0.001) were found to be related to lymph node metastases, but other variables—c‐met over‐expression, the T stage, perineural invasion, and growth pattern—were found to have no relation to lymph node metastases in multivariate analysis of the data with linear regression.CONCLUSIONSc‐met overexpression is observed in both the primary site and the neck in supraglottic laryngeal squamous cell carcinoma. We believe that it may have a role in the progression of malignancy, but we were unable to find a definite relation between c‐met expression and lymph node metastases. (Otolaryngol Head Neck Surg 2004;130:698‐703.)
Tone Perception of Cantonese‐Speaking Prelingually Hearing‐Impaired Children with Cochlear Implants
Authors: Wong Angela O. C. , Wong Lena L. N. 
Published: June 2004

OBJECTIVE: To evaluate tone perception performance in Cantonese‐speaking prelingually hearing‐impaired children with cochlear implants.STUDY DESIGN AND SETTING: The ability to discriminate and identify Cantonese tones was evaluated on 17 native Cantonese‐speaking prelingually hearing‐impaired children. Performance was correlated to factors like age of implantation and general communication ability.RESULTS: Subjects' performance in discrimination and identification tasks was slightly above chance level. Although variations in the contour fundamental frequency of the tones provided some cues for tone discrimination, these distinctions proved insufficient for subjects to perform well. Tone 6 (low level tone) was the most difficult to identify. Subjects' performance did not correlate with gender, age of implantation, duration of implant use, frequency of auditory training session, or general communication ability.CONCLUSION: Although some children were able to discriminate and/or identify Cantonese tones, their performance was poor. Further studies are needed to understand how tone perception relate to daily speech understanding.SIGNIFICANCE: Cochlear implant speech coding strategies may need modification to optimize tone perception. (Otolaryngol Head Neck Surg 2004; 130:751‐8.)
Tuberculous Otitis Media: A Significant Diagnostic Challenge
Authors: Vaamonde Pedro , Castro Crisanto , García‐Soto Nicolas , Labella Torcuato , Lozano Ascension 
Published: June 2004

OBJECTIVEThis study was undertaken to revise the diagnostic characteristics of tuberculous otitis media (TOM), a disorder that is often diagnosed late, leading to delay in specific treatment.STUDY DESIGN AND SETTINGRetrospective study of a longitudinal series of 10 TOM patients over a 7‐year period at an institutional referral center.RESULTSMost patients showed intractable otorrhea, moderately severe hearing loss, and necrotic eardrums with granulation tissue and single perforations. Multiple perforations, facial palsy, and cervical adenopathies were rare (<10% of patients). CT generally showed soft tissue involvement of the middle ear without bone erosion. The most effective laboratory test microbiological culture of exudate (diagnostic efficacy 71%). Specific antibiotic treatment was effective in all cases.CONCLUSIONThe diagnosis of TOM remains a significant challenge for otorhinolaryngologists.SIGNIFICANCE: If there are strong clinical grounds for suspicion, standard laboratory tests for tuberculosis should be repeated even if initially negative. (Otolaryngol Head Neck Surg 2004;130:759‐66.)
Observed Abundance Features and their Implications for Chemical Evolution
Authors: Tsujimoto Takuji , Shigeyama Toshikazu 
Published: June 2004

AbstractWe describe the star formation histories of the Milky Way dwarf spheroidal galaxy and the globular cluster ω Centauri in terms of an inhomogeneous chemical evolution model developed for the Galactic halo. The observed abundance trends seen in neutron-capture elements together with α-elements constrain our models to shed light on the histories of these nearby galaxies and ω Cen. The origin of low-α stars and a new picture of the globular cluster formation scenario induced by cloud–cloud collisions are also presented.
Modelling Galaxies with a 3D Multi-Phase ISM
Authors: Harfst Stefan , Theis Christian , Hensler Gerhard 
Published: June 2004

AbstractWe present a modified TREE-SPH code to model galaxies in three dimensions. The model includes a multi-phase description of the interstellar medium which combines two numerical techniques. A diffuse warm/hot gas phase is modelled by SPH, whereas a cloudy medium is represented by a sticky particle scheme. Interaction processes (such as star formation and feedback), cooling, and mixing by condensation and evaporation, are taken into account. Here we apply our model to the evolution of a Milky Way type galaxy. After an initial stage, a quasi-equilibrium state is reached. It is characterised by a star formation rate of ∼1 M⊙ yr–1. Condensation and evaporation rates are in balance at 0.1–1 M⊙ yr–1.
Solar Neighbourhood Age–Metallicity Relation Based on Hipparcos Data
Authors: Ibukiyama Akihiko 
Published: June 2004

AbstractWe derive age–metallicity relations (AMRs) and orbits for the 1658 solar neighbourhood stars for which accurate distances are measured by the Hipparcos satellite. The sample comprises 1382 thin disk stars, 229 thick disk stars, and 47 halo stars according to their orbital parameters. We find a considerable scatter for thin disk AMRs along the one-zone Galactic chemical evolution (GCE) model. Orbits and metallicities of thin disk stars show no clear relation to each other. The scatter along the AMR exists even if stars with the same orbits are selected. We examine simple extensions of one-zone GCE models which account for inhomogeneity in the effective yield and inhomogeneous star formation rate in the Galaxy. Both extensions of the one-zone GCE model cannot account for the scatter in the age–[Fe/H]–[Ca/Fe] relation simultaneously. We conclude, therefore, that the scatter along the thin disk AMR is an essential feature in the formation and evolution of the Galaxy. The AMR for thick disk stars shows that star formation terminated 8 Gyr ago in the thick disk. As previously reported, thick disk stars are more Ca-rich than thin disk stars with the same [Fe/H]. We find that thick disk stars show a vertical abundance gradient. These three facts — AMR, vertical gradient, and [Ca/Fe]–[Fe/H] relation — support monolithic collapse and/or accretion of satellite dwarf galaxies as likely thick disk formation scenarios.
Multiple Supernova Explosions in a Forming Galaxy
Authors: Mori Masao , Umemura Masayuki , Ferrara Andrea 
Published: June 2004

AbstractUltra-high resolution hydrodynamic simulations using 10243 grid points are performed of a very large supernova burst in a forming galaxy, with properties similar to those inferred for Lyman Break Galaxies (LBGs). Explosions produce kpc-sized expanding hot bubbles enclosed by cool, dense shells, and the engulfed gas is polluted with freshly-synthesised heavy elements. We show that the resultant inhomogeneous mixing produces a large spread ([Fe/H] ≈ –1 to –5) of metallicities, which affects the subsequent galactic chemical evolution and leaves its imprint on metal-poor stars. By combining a spectral synthesis model with the numerical results, we predict Lyα emission from such galaxy at z = 3. We find that the simulated galaxy, whose peak star formation rate is ≈200 M⊙ yr–1, produces a Lyα luminosity Lα = 9.7 × 1042 erg s–1. This value favorably matches the observed one, but some discrepancies are left for the Lyα line width, the metallicity, and X-ray properties. Since the results of the simulation is applicable only at the very early epoch of the galaxy formation, the metallicity is still lower than that of LBGs. However, the analysis presented here demonstrates a way to enable a systematic comparison with observational data.It is concluded that LBGs are optimal objects to scrutinise the early self-enrichment in forming galaxies. In the future, the predicted bubbly structure carved by SNe may be directly detected by high resolution observations with JWST.
On the Shape of the Galactic Dark Matter Halo
Authors: Helmi Amina 
Published: June 2004

AbstractThe confined nature of the debris from the Sagittarius dwarf to a narrow trail on the sky has recently prompted the suggestion that the dark matter halo of our Galaxy should be nearly spherical (Ibata et al. 2001; Majewski et al. 2003). This would seem to be in strong contrast with predictions from cold dark matter (CDM) simulations, where dark halos are found to have typical density axis ratios of 0.6 to 0.8. Here I present numerical simulations of the evolution of a system like the Sagittarius dSph in a set of Galactic potentials with varying degrees of flattening. These simulations show that the Sagittarius streams discovered so far are too young dynamically to be sensitive to the shape of the dark halo of the Milky Way. The data presently available are entirely consistent with a Galactic dark matter halo that could either be oblate or prolate, with density axis ratios c/a that range from 0.6 to 1.6 within the region of the halo probed by the orbit of the Sagittarius dwarf.
STAR: an algorithm to Search for Tandem Approximate Repeats
Authors: Delgrange Olivier , Rivals Eric 
Published: June 2004

Abstract
Motivation: Tandem repeats consist in approximate and adjacent repetitions of a DNA motif. Such repeats account for large portions of eukaryotic genomes and have also been found in other life kingdoms. Owing to their polymorphism, tandem repeats have proven useful in genome cartography, forensic and population studies, etc. Nevertheless, they are not systematically detected nor annotated in genome projects. Partially because of this lack of data, their evolution is still poorly understood.
Results: In this work, we design an exact algorithm to locate approximate tandem repeats (ATR) of a motif in a DNA sequence. Given a motif and a DNA sequence, our method named STAR, identifies all segments of the sequence that correspond to significant approximate tandem repetitions of the motif. In our model, an Exact Tandem Repeat (ETR) comes from the tandem duplication of the motif and an ATR derives from an ETR by a series of point mutations. An ATR can then be encoded as a number of duplications of the motif together with a list of mutations. Consequently, any sequence that is not an ATR cannot be encoded efficiently by this description, while a true ATR can. Our method uses the minimum description length criterion to identify which sequence segments are ATR. Our optimization procedure guarantees that STAR finds a combination of ATR that minimizes this criterion.
Availability: for use at http://atgc.lirmm.fr/star
Supplementary information: an appendix is available at http://atgc.lirmm.fr/star under ‘Paper and contacts’.
A spline function approach for detecting differentially expressed genes in microarray data analysis
Authors: He Wenqing 
Published: June 2004

Abstract
Motivation: A primary objective of microarray studies is to determine genes which are differentially expressed under various conditions. Parametric tests, such as two-sample t-tests, may be used to identify differentially expressed genes, but they require some assumptions that are not realistic for many practical problems. Non-parametric tests, such as empirical Bayes methods and mixture normal approaches, have been proposed, but the inferences are complicated and the tests may not have as much power as parametric models.
Results: We propose a weakly parametric method to model the distributions of summary statistics that are used to detect differentially expressed genes. Standard maximum likelihood methods can be employed to make inferences. For illustration purposes the proposed method is applied to the leukemia data (training part) discussed elsewhere. A simulation study is conducted to evaluate the performance of the proposed method.
Pre‐attentive perception of vowel phonemes from variable speech stimuli
Authors: Jacobsen Thomas , Schröger Erich , Alter Kai 
Published: June 2004

AbstractUnderstanding speech requires the construction of phonetic representations while abstracting from specific sound features. To understand different speakers of varying pitches of voice, loudness, or timbre, categorical phoneme information needs to be rapidly extracted from dynamic, changing speech input. The present study demonstrated a genuine MMN to tokens of /a/ and /i/ vowels varying in pitch of voice and amplitude envelope when they occurred infrequently among the respective other vowels. These data indicate that the speech perception system pre‐attentively extracted the F1/F2 formant information despite the language‐irrelevant variation in the sound input.
Regional cerebral blood flow correlates with heart period and high‐frequency heart period variability during working‐memory tasks: Implications for the cortical and subcortical regulation of cardiac autonomic activity
Authors: Gianaros Peter J. , Van der Veen Frederik M. , Jennings J. Richard 
Published: June 2004

AbstractThe aim of the present study was to characterize the functional relationships between behaviorally evoked regional brain activation and cardiac autonomic activity in humans. Concurrent estimates of regional cerebral blood flow (rCBF; obtained by positron emission tomography), heart period, and high‐frequency heart period variability (HF‐HPV; an indicator of cardiac parasympathetic activity) were examined in 93 adults (aged 50–70 years) who performed a series of increasingly difficult working‐memory tasks. Increased task difficulty resulted in decreased heart period (indicating cardioacceleration) and decreased HF‐HPV (indicating decreased cardiac parasympathetic activity). Task‐induced decreases in heart period and HF‐HPV were associated with concurrent increases and decreases in rCBF to cortical and subcortical brain regions that are speculated to regulate cardiac autonomic activity during behavioral processes: the medial‐prefrontal, insular, and anterior cingulate cortices, the amygdala–hippocampal complex, and the cerebellum. These findings replicate and extend a small number of functional neuroimaging studies that suggest an important role for both cortical and subcortical brain systems in human cardiac autonomic regulation.
Abolished circadian rhythm of melatonin secretion in sedated and artificially ventilated intensive care patients
Authors: Olofsson K. , Alling C. , Lundberg D. , Malmros C. 
Published: June 2004

Background:  Sleep disturbance is common in intensive care patients. Aside from its unpleasantness, there is a correlation with intensive care unit (ICU) syndrome/delirium. Reasons for sleep deprivation appear to be multifactorial, including the underlying illness, an acute superimposed disturbance, medications, and the ICU environment itself. There are reasons to believe that alterations of the ‘biological clock’ might contribute. Melatonin secretion is one reflection of this internal sleep/wake mechanism. Melatonin levels are normally high during the night and low during daytime, being suppressed by bright light.Methods:  Melatonin levels in blood and urine were studied over 3 consecutive days in eight critically ill patients during deep sedation and mechanical ventilation. Sedation was assessed with the sedation‐agitation (SAS) scale and bispectral index (BIS) monitor.Results:  The circadian rhythm of melatonin release was abolished in all but one patient, who recovered much more quickly than the others. There was no correlation between melatonin levels and levels of sedation.Conclusions:  This study indicates that dyssynchronization of the melatonin secretion rhythm is common in critically ill and mechanically ventilated patients. It could be hypothesized that an impairment of the melatonin rhythm may play a role in the development of sleep disturbances and delirium in intensive care patients, and that melatonin supply could reduce the incidence of these phenomena.
The role of smoking intentions in predicting future smoking among youth: findings from Monitoring the Future data
Authors: Wakefield Melanie , Kloska Deborah D. , O'Malley Patrick M. , Johnston Lloyd D. , Chaloupka Frank , Pierce John , Giovino Gary , Ruel Erin , Flay Brian R. 
Published: June 2004

ABSTRACTAims  To demonstrate that intentions predict long‐term future levels of smoking, irrespective of level of past smoking experience. A growing body of research suggests that intentions about future smoking might play an important role in addition to the influence of past smoking experience on the likelihood of smoking in future.Design  Using logistic regression analyses, we assessed the relationship between baseline smoking experience and a firm intention ‘not to be smoking cigarettes 5 years from now’ with four outcome measures of smoking at follow‐up: 30‐day smoking at a 3/4‐ and 5/6‐year follow‐up and current established smoking (self‐described regular smokers or former smokers who had smoked in the past 30 days) at a 3/4‐ and 5/6‐year follow‐up.Participants  US nationally representative samples of 12th graders who responded to the Monitoring the Future (MTF) survey from the years 1976 to 1993, inclusive. For these panels, we linked stage of smoking and intentions at 12th grade to follow‐up measures of smoking collected at 3/4 years after baseline and 5/6 years after baseline.Findings  Analysis of 3/4‐year follow‐up data (weighted n = 4544) and 5/6‐year follow‐up data (weighted n = 3885) for both definitions of smoking outcome indicated that there was a dose–response relationship between levels of baseline smoking experience and the likelihood of future smoking. In addition, independent of baseline smoking experience, there was a statistically significant protective effect for a firm intention not to smoke in five year's time on future smoking behavior.Conclusions  The findings suggest that evaluative studies of tobacco control policies and programs might usefully employ smoking uptake categories that incorporate smoking intentions as early indicators of outcome.
Determination of the regularization level of truncated singular‐value decomposition inversion: The case of 1D inversion of MT data
Authors: Pedersen Laust B. 
Published: June 2004

ABSTRACTThe total mean‐square error (MSE) of the estimated model, defined as the sum of the standard model variance and the bias variance, is used to define the truncation level of the singular‐value decomposition to give a reasonable balance between model resolution and model variance. This balance is determined largely by the data and no further assumptions are necessary except that the bias terms are estimated sufficiently well. This principle has been tested on the 1D magnetotelluric inverse problem with special emphasis on high‐frequency radio magnetotelluric (RMT) data. Simulations clearly demonstrate that the method provides a good balance between resolution and variance. Starting from a homogeneous half‐space, the best solution is sought for a fixed set of singular values. The model variance is estimated from the sum of the inverse eigenvalues squared, up to a certain threshold, and the bias variance is estimated from the model projections on the remaining eigenvectors. By varying the threshold, the minimum of the MSE is found for an increasing number of fixed singular values until the number of active singular values becomes greater than or equal to the estimated number. As a side‐effect, the depth of penetration of a given set of measurements can be estimated very efficiently by simply noting at which depth the final model deviates little from the starting homogeneous half‐space model. A suite of synthetic data is inverted and an example of inversion of one site is shown to illustrate how the truncation is carried out as the non‐linear inversion process proceeds. A field example with a profile across a plume of contaminated groundwater in the Netherlands shows good agreement with the electrical resistivity obtained in a nearby borehole.
Dispersion and radial depth of investigation of borehole modes
Authors: Sinha Bikash K. , Asvadurov Sergey 
Published: June 2004

ABSTRACTSonic techniques in geophysical prospecting involve elastic wave velocity measurements that are performed by placing acoustic transmitters and receivers in a fluid‐filled borehole. The signals recorded at the receivers are processed to obtain compressional‐ and shear‐wave velocities in the surrounding formation. These velocities are generally used in seismic surveys for the time‐to‐depth conversion and other formation parameters, such as porosity and lithology. Depending upon the type of transmitter used (e.g. monopole or dipole) and as a result of eccentering, it is possible to excite axisymmetric(n= 0), flexural(n= 1)and quadrupole(n= 2)families of modes propagating along the borehole. We present a study of various propagating and leaky modes that includes their dispersion and attenuation characteristics caused by radiation into the surrounding formation. A knowledge of propagation characteristics of borehole modes helps in a proper selection of transmitter bandwidth for suppressing unwanted modes that create problems in the inversion for the compressional‐ and shear‐wave velocities from the dispersive arrivals. It also helps in the design of a transmitter for a preferential excitation of a given mode in order to reduce interference with drill‐collar or drilling noise for sonic measurements‐while‐drilling. Computational results for the axisymmetric family of modes in a fast formation with a shear‐wave velocity of 2032 m/s show the existence of Stoneley, pseudo‐Rayleigh and anharmonic cut‐off modes. In a slow formation with a shear‐wave velocity of 508 m/s, we find the existence of the Stoneley mode and the first leaky compressional mode which cuts in at approximately the same normalized frequencyωa/VS= 2.5(ais the borehole radius) as that of the fast formation. The corresponding modes among the flexural family include the lowest‐order flexural and anharmonic cut‐off modes. For both the fast and slow formations, the first anharmonic mode cuts in at a normalized frequencyωa/VS= 1.5approximately. Cut‐off frequencies of anharmonic modes are inversely proportional to the borehole radius in the absence of any tool. The borehole quadrupole mode can also be used for estimating formation shear slownesses. The radial depth of investigation with a quadrupole mode is marginally less than that of a flexural mode because of its higher frequency of excitation.