Location Of Constriction Research Articles

Comparison of working length determination with radiographs and four electronic apex locators

To evaluate the accuracy of the Root ZX, Elements-Diagnostic, Precision AL and Raypex 5 electronic apex locators when compared to radiographs for locating the apical constriction. The apical constriction of 693 canals in 245 maxillary and mandibular teeth was located in vivo with four electronic apex locators (EALs) and radiographically. After extraction the actual location of the apical constriction was determined visually and with magnification. A paired samples t-test, X2 test and a repeated measure anova at the 0.05 level of significance were used to determine differences between the groups. For anterior teeth, the Root ZX, Elements, Precision AL, Raypex 5 and radiographs located the apical constriction 89.09%, 83.63%, 85.45%, 81.81% and 32.72% of the time, respectively. For premolar teeth, the Root ZX, Elements, Precision AL, Raypex 5 and radiographs located the apical constriction 75%, 61.60%, 64.28%, 61.60% and 32.14% of the time, respectively. For molar teeth, the Root ZX, Elements, Precision AL, Raypex 5 and radiographs located the apical constriction 69.01%, 50.49%, 65.40%, 43.93% and 14.59% of the time, respectively. There was no statistically significant difference between the four EALs (P = 0.05). Measuring the location of the apical constriction using the four apex locators was more accurate than radiographs and would reduce the risk of instrumenting and filling beyond the apical foramen.

A comparative cytogenetic analysis of five pine species from North America, Pinus banksiana, P. contorta, P. monticola, P. resinosa, and P. strobus

The genus Pinus comprises more than 100 species, which are widely distributed in the Northern hemisphere. Cytogenetic information on North American pines is very limited despite their economic importance. In the present study, a detailed comparative cytogenetic analysis is presented for five pine species from North America, P. resinosa, P. monticola, P. contorta, P. banksiana, and P. strobus. Morphometric analysis and physical mapping of rDNA probes were performed. The karyotype of P. monticola was considered ancestral with small difference in relative chromosome lengths. P. banksiana, P. contorta, and P. strobus karyotypes were considered semi-asymmetrical and less ancestral type. P. banksiana showed five secondary constrictions, P. strobus six, and P. contorta eight. P. resinosa karyotype was semi-asymmetrical and derived with 14 secondary constrictions identified on eight different chromosomes. Karyological data were consistent with molecular cytogenetic information. A significant association was observed between the number and locations of secondary constrictions and the 18S-5.8S-26S rDNA sites detected using fluorescence in situ hybridization. The two methods were used to establish a reliable comparative karyotype of the selected pines. In general, karyotype and chromosome evolution were not related to genetic relationships among pine species studied.

Comparative karyological analysis of four diplozoid species (Monogenea, Diplozoidae), gill parasites of cyprinid fishes

The present study has revealed new data on chromosome complements of diplozoid parasites, namely Diplozoon paradoxum from freshwater bream Abramis brama, Paradiplozoon bliccae from white bream Blicca bjoerkna, Paradiplozoon sapae from white-eye bream Ballerus sapa, and Paradiplozoon nagibinae from zope Ballerus ballerus. Particularly, D. paradoxum is characterized by four pairs (2n=8) of long (up to 22.1 μm) chromosomes: pairs 1, 2, and 3 are metacentric and pair 4 acrocentric. Karyotypes of three Paradiplozoon species are nearly identical in number and morphological classification of chromosomes, each comprising diploid number of 14 one-armed chromosomes of very similar length ranging up to 12.5 μm in P. bliccae, 9.2 μm in P. sapae, and 9.9 μm in P. nagibinae. All four species are similar in their total complement length, ranging from 64.4 to 50.4 μm. Interspecific differences were found in location of secondary constriction: it is situated on short arm of the 1st chromosome pair in D. paradoxum, on long arm of the 7th pair in P. bliccae and on long arm of the 4th pairs in P. sapae and P. nagibinae. Phylogenetic interrelationship within the diplozoids and hypothetic karyotype evolution is here discussed.

Relation of vocal tract shape, formant transitions, and stop consonant identification.

The present study was designed to investigate the relation of formant transitions to place-of-articulation for stop consonants. A speech production model was used to generate simulated utterances containing voiced stop consonants, and a perceptual experiment was performed to test their identification by listeners. Based on a model of the vocal tract shape, a theoretical basis for reducing highly variable formant transitions to more invariant formant deflection patterns as a function of constriction location was proposed. A speech production model was used to simulate vowel-consonant-vowel (VCV) utterances for 3 underlying vowel-vowel contexts and for which the constriction location was incrementally moved from the lips toward the velar part of the vocal tract. These simulated VCVs were presented to listeners who were asked to identify the consonant. Listener responses indicated that phonetic boundaries were well aligned with points along the vocal tract length where there was a shift in the deflection polarity of either the 2nd or 3rd formant. This study demonstrated that regions of the vocal tract exist that, when constricted, shift the formant frequencies in a predictable direction. Based on a perceptual experiment, the boundaries of these acoustically defined regions were shown to coincide with phonetic categories for stop consonants.

Vowel constrictions are recoverable from formants

The area function of the vocal tract in all of its spatial detail is not directly computable from the speech signal. But is partial, yet phonetically distinctive, information about articulation recoverable from the acoustic signal that arrives at the listener's ear? The answer to this question is important for phonetics, because various theories of speech perception predict different answers. Some theories assume that recovery of articulatory information must be possible, while others assume that it is impossible. However, neither type of theory provides firm evidence showing that distinctive articulatory information is or is not extractable from the acoustic signal. The present study focuses on vowel gestures and examines whether linguistically significant information, such as the constriction location, constriction degree, and rounding, is contained in the speech signal, and whether such information is recoverable from formant parameters. Perturbation theory and linear prediction were combined, in a manner similar to that in Mokhtari (1998) [Mokhtari, P. (1998). An acoustic-phonetic and articulatory study of speech-speaker dichotomy. Doctoral dissertation, University of New South Wales], to assess the accuracy of recovery of information about vowel constrictions. Distinctive constriction information estimated from the speech signal for ten American English vowels were compared to the constriction information derived from simultaneously collected X-ray microbeam articulatory data for 39 speakers [ Westbury (1994). Xray microbeam speech production database user's handbook. University of Wisconsin, Madison, WI]. The recovery of distinctive articulatory information relies on a novel technique that uses formant frequencies and amplitudes, and does not depend on a principal components analysis of the articulatory data, as do most other inversion techniques. These results provide evidence that distinctive articulatory information for vowels can be recovered from the acoustic signal.

Perception of articulatory dynamics from acoustic signatures

This study investigated the degree to which the articulatory trajectory of the tongue dorsum in the production of a vowel-vowel sequence is perceptually relevant. Previous research has shown that the tongue dorsum takes a path that leads to a pattern of area function change, termed the pivot pattern. In this study, articulatory synthesis was used to generate paths of tongue motion for the production of the vowel sequence /ai/. These paths differed in their curvature, leading to stimuli that conform to the pivot pattern and stimuli that violate it. Participants gave naturalness ratings and discriminated the stimuli. The acoustic properties were also compared to acoustic measurements made on productions of /ai/ by 34 speakers. The curvature of the tongue path and the curvature of the F1-F2 trajectory correlate highly with the naturalness-rating task results, but not the discrimination results. However, the particular way in which constriction location changes, particularly whether the change is discrete or continuous, and the maximal velocity of F2 through the transition, explain the perceptual patterns evident in both perception tasks, as well as the patterns in the observed acoustic data. Consequences of these results for the links between production and perception and the segmentation problem are discussed.

Anatomy, pathology, and physiology of the tracheobronchial tree: Emphasis on the distal airways

This article covers the airway tree with respect to anatomy, pathology, and physiology. The anatomic portion discusses various primate groups so as to help investigators understand similarities and differences between animal models. An emphasis is on distal airway findings. The pathology section focuses on the inflammatory responses that occur in proximal and distal airways. The physiologic review brings together the anatomic and pathologic components to the functional state and proposes ways to evaluate the small airways in patients with asthma.

Computational modeling of juncture strength using articulatory synthesis of prosodic gestures.

Prosodic boundary gestures or “pi‐gestures” (Byrd and Saltzman, J. Phonetics, 2003) have been introduced to model the local slowing or lengthening of articulatory gestures in the vicinity of phrase boundaries. Computational modeling of articulatory dynamics is an important tool in assessing the predicted effects of pi‐gestures of varying boundary strength on constriction gestures in varying contexts. We simulate pi‐gestures within the TaDA task dynamics computational model [Nam and Kim, JASA, 116, 172–185 (2004)] and examine how functional data analysis can provide a tool for connecting articulatory lengthening with underlying pi‐gesture activation strength. Specifically, the model is applied to the articulatory synthesis of two sequences: [CV#CV] and [CVC#CV], where C is bilabial or alveolar. The pi‐gesture’s midpoint is coordinated synchronously with the midpoint of following consonant’s constriction gesture, and pi‐gesture activation strength and duration are manipulated. Results indicate that pi‐gesture activation strength has a much stronger effect on slowing than its duration. The slowing effect is asymmetrical, skewed earlier than the midpoint in the pi‐gesture interval. After removing linear‐time slowing effect (i.e., after length normalization), the slowing effect is slightly stronger in [CV#CV] than in [CVC#CV]. The strength of pi‐gesture also affects spatial articulatory characteristics depending on constriction location and sequential context. [Work supported by NIH.]

Relation of vocal tract constriction location to identification of voiced stop consonants.

Consonant identification experiments are typically based on stimuli produced with a formant synthesizer where a particular acoustic characteristic is varied along some continuum of values (e.g., onset frequency of F2). In this experiment, however, vowel-consonant-vowel (VCV) stimuli were generated with a synthesizer based on a kinematic model of the vocal tract shape [B. H. Story, JASA, 117(5), 3231–3254 (2005)] where the acoustic characteristics result from the time-varying tract configuration. Each VCV was produced by superimposing a constriction at a particular location within the vocal tract on an underlying vowel-vowel sequence. Five different vowel-vowel sequences were produced, and for each, a constriction was imposed at 20 consecutive locations extending from the lips to approximately the velum. VCVs were presented in random order, ten times each, to ten listeners, using a forced choice paradigm where only the voiced English consonants /b, d, g/ were available. Listener responses indicated that the relation of formant frequencies near the consonant, to those of the preceding or succeeding vowel can provide reasonably accurate predictions of regions within the vocal tract that correspond to specific consonants. It was also revealed that the location and length of each region is dependent on the vowel. [Research supported by NIH R01-DC04789.]

Probing airway conditions governing ventilation defects in asthma via hyperpolarized MRI image functional modeling

Image functional modeling (IFM) has been introduced as a method to simultaneously synthesize imaging and mechanical data with computational models to determine the degree and location of airway constriction in asthma. Using lung imaging provided by hyperpolarized (3)He MRI, we advanced our IFM method to require matching not only to ventilation defect location but to specific ventilation throughout the lung. Imaging and mechanical data were acquired for four healthy and four asthmatic subjects pre- and postbronchial challenge. After provocation, we first identified maximum-size airways leading exclusively to ventilation defects and highly constricted them. Constriction patterns were then found for the remaining airways to match mechanical data. Ventilation images were predicted for each pattern, and visual and statistical comparisons were done with measured data. Results showed that matching of ventilation defects requires severe constriction of small airways. The mean constriction of such airways leading to the ventilation defects needed to be 70-80% rather than fully closed. Also, central airway constriction alone could not account for dysfunction seen in asthma, so small airways must be involved.

Identification of the chromosomes of rye by distribution patterns of DNA.

Ultramicrospectrophotometric measurements were made on unstained and Feulgen-stained rye chromosomes at 265 mμ and 546 mμ, respectively. The total extinction values of the individual chromosomes corresponded to their relative lengths. Similarly, the long/short arm extinction values agreed well with the index ratios, and were thus useful for the classification of the chromosomes into groups. The distribution of the nucleic acids along the chromosomes was determined by scanning individual chromosomes transversally and in a few instances longitudinally. More details were found in the pattern curves obtained from measurements made on unstained than stained chromosomes. Also the greater the length of the chromosome, the greater was the detail that could be seen. The distribution pattern of DNA was in accordance with the heteropycnotic differentiation along late prophase chromosomes. A specific pattern of nucleic acid distribution along each of the seven chromosome types was useful for chromosome identification. In the pattern curves, sites indicating a markedly low nucleic acid content coincided with the positions of primary and secondary constrictions. Sites with slightly lower nucleic acid content than adjacent areas most likely indicate positions of potential secondary constrictions, since most of these sites coincided with locations of faint constrictions that were detectable in the rye chromosomes when these were present in the intergeneric hybrid Elymus arenarius X Secale cereale. Factors such as the technique for chromosome preparations, degree of chromosome contraction, intensity of Feulgen coloration, chromosomal RNA cycle, nucleolar behavior during mitosis, and background effects may lead to inconsistencies in the photometric measurements.

Estimation of Place of Articulation During Stop Closures of Vowel–Consonant–Vowel Utterances

Production of vowel-oral stop consonant-vowel utterances involves movement of articulators from the articulatory position of the initial vowel towards that of the oral stop closure, and then to that of the final vowel. As the closure segments have zero or low signal energy, linear predictive coding (LPC)-based estimation of vocal tract shape fails during stop closure. This paper reports a technique for estimation of place of articulation during stop closures by performing bivariate polynomial modeling on vocal tract area values during transition segments preceding and following the closure. The technique with second-degree polynomial modeling was found to be suitable for estimating the place of maximum constriction during stop closure segments of vowel-consonant-vowel utterances with bilabial, alveolar, and velar stops. The estimated places compared well with the actual constriction locations observed from the articulatory data. The technique may be useful for improving effectiveness of speech-training aids for production of stop consonants by providing visual feedback of the estimated place of articulation.

Does vowel inventory or inventory size condition the articulation of /i/ and /y/?

Wood [J. Acoust. Soc. Am. 80, 391–401 (1986)] and dispersion‐focalization theory (DFT) [Schwartz et al., J. Phonetics 25, 255–86 (1997)] have made differing predictions about variation in the articulation of /i/ and /y/. Wood claimed that there are “language‐specific tendencies to either prepalatal or midpalatal tongue positions for palatal vowels … languages contrasting [i] with [y] preferring the prepalatal position for both vowels” [Wood (1986), p. 392]. However, DFT predicts that the high‐front vowel /i/ is always driven to near the high‐front corner of the acoustic space in order to maximize perceptual‐acoustic distinctness from the rest of the vowels in the inventory of the language. In addition, it is possible that languages with smaller vowel inventories have less extreme articulations for “corner” vowels such as /i/ and /y/ overall. In this study, we compare articulatory measures of constriction location, extent, and degree in four languages (with /y/ versus without /y/ and small inventory versus large inventory).

Fuz1, a MYND domain protein, is required for cell morphogenesis in Ustilago maydis.

Abstract: Ustilago maydis is a Basidiomycete fungus that exhibits a yeast-like nonpathogenic form and a dikaryotic filamentous pathogenic form. Generation of these two forms is controlled by two mating type loci, a and b. The fungus undergoes additional morphological transitions in the plant that result in formation of a third cell type, the teliospore. The fuz1 gene is necessary for this developmental program. Here we report cloning and sequencing of fuz1 and show that it contains an open reading frame with coding capacity for a protein of 1421 amino acids. The Fuz1 protein belongs to the family of MYND Zn finger domain proteins. We generate a null mutation in strains of opposite mating type and show that fuz1 is necessary for conjugation tube formation, a morphological transition that occurs in response to pheromones. We generate fuz1- diploid strains heterozygous at a and b and show that fuz1 is also necessary for postfusion events (maintenance of filamentous growth). We also demonstrate that fuz1 is necessary for cell morphogenesis of the yeast-like cell: normal cell length, location and number of septa, cell separation and constriction of the neck region. Fuz1 is also required for cell wall integrity and to prevent secretion of a dark pigment. We propose that the MYND domain may interact with different proteins to regulate cell morphogenesis.

Fuz1, a MYND domain protein, is required for cell morphogenesis in Ustilago maydis

Ustilago maydis is a Basidiomycete fungus that exhibits a yeast-like nonpathogenic form and a dikaryotic filamentous pathogenic form. Generation of these two forms is controlled by two mating type loci, a and b. The fungus undergoes additional morphological transitions in the plant that result in formation of a third cell type, the teliospore. The fuz1 gene is necessary for this developmental program. Here we report cloning and sequencing of fuz1 and show that it contains an open reading frame with coding capacity for a protein of 1421 amino acids. The Fuz1 protein belongs to the family of MYND Zn finger domain proteins. We generate a null mutation in strains of opposite mating type and show that fuz1 is necessary for conjugation tube formation, a morphological transition that occurs in response to pheromones. We generate fuz1− diploid strains heterozygous at a and b and show that fuz1 is also necessary for postfusion events (maintenance of filamentous growth). We also demonstrate that fuz1 is necessary for cell morphogenesis of the yeast-like cell: normal cell length, location and number of septa, cell separation and constriction of the neck region. Fuz1 is also required for cell wall integrity and to prevent secretion of a dark pigment. We propose that the MYND domain may interact with different proteins to regulate cell morphogenesis.

Vowel space parameters

Vowels are universal in human languages and have long been categorized in feature systems. However, the feature systems are based on introspection and include a notion of ‘‘height’’ or ‘‘closeness,’’ that is not anatomically straightforward. From x-ray and other imaging data, the important aspects seem to be palatal, velar, and pharyngeal closures, with secondary effects of lip rounding. Describing vowels in terms of location of constriction makes some assimilation patterns more direct, as with palatal vowels (e.g., /i/) conditioning palatal fricatives. Vowels can also be described as intrinsically slower than consonants, which allows for a more straightforward description of their timing relationships, and a possible explanation for the crosslinguistic preference for CV syllables. The use of fricatives for syllabic nuclei is common in languages and derives easily from a narrowing of the constriction to the point at which frication is generated. More and less vowel-like patterns in consonants have also been noted, such as in coarticulation of laterals and rhotics. Gesture-based systems have difficulty describing some phonological patterns (e.g., vowel lowering). The status of schwa, which seems to lack a constriction, is unclear. With two competing systems having different advantages, work directly comparing the approaches is needed within speech science.

An electropalatographic and acoustic study of affricates and fricatives in two Catalan dialects

The present study is an electropalatographic and acoustic investigation of the fricatives /s, f/ and the affricates /ts, dz, tf, d[zcy ]/ based on data from five speakers of Majorcan Catalan and five speakers of Valencian Catalan. Results show that the articulatory characteristics of fricatives and affricates agree in several respects: the sounds traditionally labeled /f/ and /tf, d[zcy ]/ are alveolopalatal, and are articulated at a less anterior location, are less constricted and show more dorsopalatal contact than the alveolars /s/ and /ts, dz/; the two place categories are closer to each other in Valencian than in Majorcan. Compared to voiceless affricates, voiced affricates are more anterior and more constricted, and show less dorsopalatal contact. Data also show that closure location for /tf, d[zcy ]/ occurs at the alveolar zone, and that articulatory differences among affricates are better specified at frication than at closure. Strict homorganicity between the stop and frication components of affricates appears to hold provided that constriction location at frication is compared with place of articulation at closure offset. In comparison to voiceless affricates, voiced affricates were shorter, and exhibited a longer closure and a shorter frication period, in Majorcan; in Valencian, on the other hand, closures were shortest for /d[zcy ]/, and frication was systematically longer for voiceless vs. voiced affricates. These duration data appear to conform to a universal trend in Valencian but not in Majorcan where voiced affricates are lengthened intentionally. In both Catalan dialects, vowel duration varies inversely with the duration of the affricate and of its closure and frication components. The implications of these articulatory and duration characteristics for the interpretation of sound changes affecting affricates, i.e. place merging, lenition and devoicing, are discussed.

Simulation of Losses Due to Turbulence in the Time-Varying Vocal System

Flow separation in the vocal system at the outlet of a constriction causes turbulence and a fluid dynamic pressure loss. In articulatory synthesizers, the pressure drop associated with such a loss is usually assumed to be concentrated at one specific position near the constriction and is represented by a lumped nonlinear resistance to the flow. This paper highlights discontinuity problems of this simplified loss treatment when the constriction location changes during dynamic articulation. The discontinuities can manifest as undesirable acoustic artifacts in the synthetic speech signal that need to be avoided for high-quality articulatory synthesis. We present a solution to this problem based on a more realistic distributed consideration of fluid dynamic pressure changes. The proposed method was implemented in an articulatory synthesizer where it proved to prevent any acoustic artifacts

Remote acoustical reconstruction of cave and pipe geometries

Military and commercial interests desire to determine the geometry of caves, tunnels, and piping systems remotely. Advance knowledge of the geometry would allow military personnel to focus on the mission objectives rather than on cave exploration and mapping. Commercial applications of remote geometry mapping include determining locations of collapsed mines and tunnels for search and rescue missions, and determining locations of breaches or constrictions in pipelines. This research effort begins to extend acoustic pulse reflectometry to these applications and only requires simple measurements made at the waveguide entrance. This implementation first measures the acoustic reflection coefficient using a modified form of the two-microphone method and computes the waveguide impulse response. Then the system uses an inverse-scattering algorithm to solve for the cross-sectional area as a function of distance. Results are shown for a simple area expansion attached to a laboratory impedance tube with a diameter of 35 mm, and for a pedestrian tunnel with a nominal square cross-section of 5.9 m2. The impedance tube estimates match the known cross-sectional areas to within 10%. The results from the pedestrian tunnel show greater uncertainty due to frequency range limitations on the measurements, but can still capture important features of the geometry.

Phonetic Typology and Positional Allophones for Alveolar Rhotics in Catalan

The present study reports electropalatographic and acoustic data on the positionaland contextual characteristics of alveolar taps and trills in Majorcan,Valencian and Eastern Catalan. The two consonant classes are invariably opposedby degree of tongue dorsum contact and F2, but only differentiated by place ofarticulation when constriction location for the trill is sufficiently retracted. Trillsare produced with less than three contacts and may exhibit a single contact inutterance-initial position and, less often, in /Cr, VrV/ sequences. Word-final and, toa lesser extent, preconsonantal rhotics are implemented as taps in Majorcan andValencian, and strengthened into trills in Eastern Catalan. Moreover, thereappears to be an inverse relationship between initial strengthening, and intervocalicweakening and the absence of syllable-final strengthening, for Valencianrhotics, which could be indicative of a pattern of intersegmental organization.Shortening and articulatory reduction turned out not to be necessarily related forextremely short Valencian taps, which undergo much undershoot intervocalicallybut are highly constricted in /Cɾ , rC/ sequences. Other research aspects suchas devoicing and intergestural timing for Catalan alveolar rhotics are alsoinvestigated.