Root Position Research Articles

Variability in human tooth cementum thickness reflecting functional processes.

The aim of this study was to investigate the thickness of acellular extrinsic fibre cementum (AEFC) at four root positions of anterior and posterior teeth with special focus on functional aspects. Furthermore, the correlations between cementum thickness and chronological age and sex are investigated. While numerous studies confirm continuous cementum apposition with age, masticatory forces as well as physiological and orthodontically induced tooth movements also have the potential to affect tooth cementum thickness. Undecalcified teeth were embedded in resin and transverse-sectioned in the cervical third of the root. Two sections per root were selected, and digital images at four positions were obtained (mesial, distal, oral, and vestibular) using light microscopy. The AEFC thickness of 99 teeth (anterior = 66, posterior = 33, male = 54, female = 45) were measured in both sections. The differences in mean values between root positions and the association of root position variation with tooth type, age, sex, and subject as well as the overall effects of age and sex were analysed using a mixed model. First incisors and canines showed the greatest mean AFEC thickness, in contrast to premolars which had the lowest values. Differences were found across the four root positions, with a pattern varying considerably between anterior and posterior teeth and between maxilla and mandible in the anterior teeth. An interaction between root position and subject pointed to the existence of an individual component in the variation of AEFC thickness across the four root positions. There was an age trend with an almost linear increase in cementum thickness of 1 μm per year. Overall, females tended to exhibit a significantly lesser AEFC thickness compared to males. Distinct differences in the pattern of thickness values across the four root positions in anterior and posterior teeth support the assumption that the AEFC is strongly affected by functional processes. In addition to sex-specific differences and age-related trends, the root position variation of AEFC thickness varies from individual to individual.

EMS: 3D Eyebrow Modeling from Single-View Images

Eyebrows play a critical role in facial expression and appearance. Although the 3D digitization of faces is well explored, less attention has been drawn to 3D eyebrow modeling. In this work, we propose EMS, the first learning-based framework for single-view 3D eyebrow reconstruction. Following the methods of scalp hair reconstruction, we also represent the eyebrow as a set of fiber curves and convert the reconstruction to fibers growing problem. Three modules are then carefully designed: RootFinder firstly localizes the fiber root positions which indicate where to grow; OriPredictor predicts an orientation field in the 3D space to guide the growing of fibers; FiberEnder is designed to determine when to stop the growth of each fiber. Our OriPredictor directly borrows the method used in hair reconstruction. Considering the differences between hair and eyebrows, both RootFinder and FiberEnder are newly proposed. Specifically, to cope with the challenge that the root location is severely occluded, we formulate root localization as a density map estimation task. Given the predicted density map, a density-based clustering method is further used for finding the roots. For each fiber, the growth starts from the root point and moves step by step until the ending, where each step is defined as an oriented line segment with a constant length according to the predicted orientation field. To determine when to end, a pixel-aligned RNN architecture is designed to form a binary classifier, which outputs stop or not for each growing step. To support the training of all proposed networks, we build the first 3D synthetic eyebrow dataset that contains 400 high-quality eyebrow models manually created by artists. Extensive experiments have demonstrated the effectiveness of the proposed EMS pipeline on a variety of different eyebrow styles and lengths, ranging from short and sparse to long bushy eyebrows.

Transcatheter aortic valve implantation with commissural alignment

Transcatheter aortic valve implantation (TAVI) is commonly accepted method of treatment of aortic stenosis in most patients with currently increasing number of TAVI procedures. Patients after TAVI frequently have indications for percutaneous coronary intervention (PCI) that might be technically challenging due to the presence of transcatheter valve. Compromising coronary ostia involves such issues as design of the prosthesis and its position in the aortic root with respect to the commissures of native aortic valve. Since TAVI with commissural alignment can mitigate risk of compromising coronary ostia, this option should be considered while planning TAVI, especially in younger patients with coronary atherosclerosis and relatively high probability of PCI in the future. The algorithm of commissural alignment in clinical practice of TAVI up to date has been proposed only for several transcatheter heart valves reported in this paper.

Panoramic Radiography vs. CBCT in the Evaluation of the Maxillary Third Molar Roots.

Background and Objectives: A comprehensive understanding of the position of third molar roots and adjacent structures, such as the maxillary sinus (MS), is essential for safe extractions. Diagnostic imaging plays a fundamental role in achieving accurate treatment planning. This study aimed to compare panoramic radiography (PR) and cone-beam computed tomography (CBCT) for the evaluation of maxillary third molar roots and their relationship with the MS. Materials and Methods: Two trained radiologists evaluated third molar images. The number of roots, morphology (fused/conical, divergent, dilacerated, or atypical), and their relationship with the MS in PR and CBCT were registered. Descriptive and inferential statistics were performed using the weighted Kappa test. Results: Regarding the number and morphology of the roots, Kappa values showed moderate (κ = 0.42) and fair agreement (κ = 0.38), respectively. Regarding the proximity with the MS, most of the roots showed close contact (30.6%), or 1/3 of root superimposition (35%), in PR evaluation, while in CBCT, the third molars were in contact with the MS floor (32%), and with alveolar domes (27.2%). Conclusions: PR is a moderately reliable image technique to identify the number of roots and root morphology of maxillary third molars. PR, however, does not provide any radiographic signs that clearly indicate the anatomical relationship between the maxillary third molar roots and the maxillary sinus detected in CBCT images.

Zygomatic arch root position in relation to dietary type in haplorhine primates.

The zygomatic root, along with other key craniofacial features, is hypothesized to play a crucial role in strengthening the face in response to stresses and strains related to feeding. As such, it has been cited as indicative of dietary specialization among fossil taxa, although it remains unknown how variable zygomatic arch root position is among living primates, and whether its positioning predicts differences in diet. We test whether primates that consume more mechanically challenging foods possess more anteriorly positioned zygomatic roots compared to those consuming less challenging foods. Zygomatic root position, as defined by the zygomaxillare landmark, was identified and recorded from digital images and physical specimens of adult primate crania. Data were collected from 33 haplorhine species (n = 722). Published data were used to assign species to a dietary type based on patterns of overall consumption along with reliance on especially challenging foods. Pairwise comparisons between mechanically challenging (hard and/or tough) and less mechanically challenging (soft) consumers found significant differences (p < 0.05) in the position of the zygomatic root in 17 of 20 pairs, 11 of which supported the prediction that a more mechanically challenging diet is associated with a more anteriorly placed zygomatic root. PGLS analysis found no significant effect of phylogeny on root position. This suggests that a more anteriorly positioned zygomatic root is useful for identifying dietary specialization in some taxa but is not required for consuming a mechanically challenging diet given that other craniofacial and behavioral factors can facilitate the consumption of such foods.

Relationship Between Sagittal Root Position and Alveolar Wall Thickness of Maxillary Teeth in the Esthetic Area for Immediate Implant Treatment Planning in a Peruvian Population.

The purpose of this retrospective study was to assess facial and palatal alveolar wall thickness (AWT) in relation to sagittal root position (SRP) of maxillary anterior teeth using cone-beam computed tomography (CBCT). 102 CBCT images (60 females, 42 males) of anterior maxillary teeth were reviewed. SRP was classified according to Kan's classification, and AWT was evaluated at coronal (4 mm from the cementoenamel junction), mid-root, and apical (2 mm from the apex) levels of the facial and palatal. Secondary variables of sex, age and tooth type were analyzed. The SRP distribution was 76.6% class I, 11.3% class II, 0.8% class III, and 11.3% class IV. AWT, from thickest to thinnest, was found in palatal apical>mid>coronal, followed by facial coronal>mid>apical. AWT was thickest in SRP class II, followed by class I and III, and least thick in class IV at all measured areas (P<.05). A significantly higher AWT was associated with class I in central incisors, class II in canine teeth and in males, and class IV in central incisors and canines.

Analysis of Root Angulation of Maxillary Central Incisor Using Cone Beam Computed Tomography (CBCT)

Background: Variance in anatomical morphology is influenced by the axial inclination of the tooth. When looking at the axial tilt of the crown, it's common to assume that it follows the same axis as the root. This study aims to use Cone Beam Computed Tomography (CBCT) to determine the root angulation correlation in maxillary central incisors. Methods: This cross-sectional observational research was performed at Dow University of Health Sciences (DUHS). The CBCT scans of patients who matched the inclusion criteria were done by skilled radiography technicians and primary investigators on ROTOGRAPH EVO 3D. For statistical analysis, one-way ANOVA was utilized to examine the Root Angulation (RA) with different root positions. p-value &lt;0.05 was considered significant. Results: This study examined n=152 CBCT images. Mean age was 27.2 + 5.9 years, with 32(42.1%) men and 44(44.1%) females. Buccal subtype I was most prevalent (59, 38.8%) in maxillary central incisors, while buccal subtype III was least common (5, 3.3%). The root angulations varied significantly between root location classifications (p=0.007). These were intermediate root location (14.9 2.6 degrees) and buccal subtype III (14.28 2.25 degrees). The palatal root type had the least angle (3.73 1.5 degrees). Conclusion: The buccal root position was shown to be the most common root location. Buccal subtype I was by far the most common. Buccal subtype III and middle root location had the maximum root angle. The palatal root position had the smallest angle.

Aplikasi Asam Giberelin dan Peletakan Akar Terhadap Produksi Benih Padi (Oryza sativa L.) Varietas Situ Bagendit

Rice is one of the main food sources for the people of Indonesia, therefore it is necessary to increase rice production to meet these needs. The purpose of this study was to determine the interaction of Gibberellin application and horizontal root placement on rice seed production. This research was conducted in Triwungan Village, Kota Anyar Subdistrict, Probolinggo Regency from August to November 2022. The implementation of the research used a Randomized Group Design (RGD) which was repeated 4 times. The first factor is GA3 concentration which consists of 4 levels, namely G0 (0 ppm), G1 (200 ppm), G2 (250 ppm), G3 (300 ppm). The second factor is the placement of root position consisting of A1 (vertical placement), A2 (horizontal placement). Observational data were analyzed using ANOVA, if there was a significant difference between treatments, it was continued with LSD further test at 1% level. The results showed that horizontal root laying showed a result of 2.35 in the number of tillers 4 weeks after planting. Gibberellin concentration of 250 ppm with the results of 20.625 cm on the parameters of panicle length, 70.04 grains on the number of grains per panicle, 57.21 grains on the number of grains per panicle, 25.99 grams on the weight of 1000

GH3-mediated auxin inactivation attenuates multiple stages of lateral root development.

Lateral root (LR) positioning and development rely on the dynamic interplay between auxin production, transport but also inactivation. Nonetheless, how the latter affects LR organogenesis remains largely uninvestigated. Here, we systematically analyze the impact of the major auxin inactivation pathway defined by GRETCHEN HAGEN3-type (GH3) auxin conjugating enzymes and DIOXYGENASE FOR AUXIN OXIDATION1 (DAO1) in all stages of LR development using reporters, genetics and inhibitors in Arabidopsis thaliana. Our data demonstrate that the gh3.1/2/3/4/5/6 hextuple (gh3hex) mutants display a higher LR density due to increased LR initiation and faster LR developmental progression, acting epistatically over dao1-1. Grafting and local inhibitor applications reveal that root and shoot GH3 activities control LR formation. The faster LR development in gh3hex is associated with GH3 expression domains in and around developing LRs. The increase in LR initiation is associated with accelerated auxin response oscillations coinciding with increases in apical meristem size and LR cap cell death rates. Our research reveals how GH3-mediated auxin inactivation attenuates LR development. Local GH3 expression in LR primordia attenuates development and emergence, whereas GH3 effects on pre-initiation stages are indirect, by modulating meristem activities that in turn coordinate root growth with LR spacing.

Tooth Extraction using Vertical, Conventional, and Surgical Techniques in Sebha Dental College: A Descriptive “Cross-sectional Study”

Objective: This study aimed to describe different techniques (vertical, conventional, and surgical) used in routine exodontia as well as the most teeth extracted per procedure. Methods: A descriptive cross-sectional study using data collected at the Department of Oral Maxillofacial Surgery, the Faculty of Dentistry, Sebha University, from March to December 2021, included 509 participants. The patient's age and gender, techniques of extraction, and tooth type were recorded. Results: The study included 509 participants aged 16 to 90. About 38.1% of the participants were male, and 61.9% were female. The conventional technique was the most performed (70.0%), followed by vertical (elevator) (26%), and then the surgical technique. The third molar was the most common tooth extracted by conventional technique. The vertical approach was the most successful for single and multirooted teeth. Conclusion: The result of this study suggests that the vertical extraction method may be used with a high success rate for the extraction of teeth unsuitable for conventional techniques. Therefore, the effectiveness of the exodontia technique is influenced by root morphology, position, and type of tooth.

Root system architecture and genomic plasticity to salinity provide insights into salt-tolerant traits in tall fescue

Salinity is detrimental to soil health, plant growth, and crop productivity. Understanding salt tolerance mechanisms offers the potential to introduce superior crops, especially in coastal regions. Root system architecture (RSA) plasticity is vital for plant salt stress adaptation. Tall fescue is a promising forage grass in saline regions with scarce RSA studies. Here, we used the computer-integrated and -automated programs EZ-Rhizo II and ROOT-Vis II to analyze and identify natural RSA variations and adaptability to high salt stress at physiological and genetic levels in 17 global tall fescue accessions. Total root length rather than the number of lateral roots contribute more to water uptake and could be used to separate salt-tolerant (LS-11) and -sensitive accessions (PI531230). Comparative evaluation of LS-11 and PI531230 demonstrated that the lateral root length rather than the main root contributed more towards the total root length in LS-11. Also, high water uptake was associated with a larger lateral root vector and position while low water intake was associated with an insignificant correlation between root length, vector, and position. To examine candidate gene expression, we performed transcriptome and transcription analyses using high-throughput RNA sequencing and real-time quantitative PCR, respectively of the lateral and main roots. The main root displayed more differentially expressed genes than the lateral root. A Poisson comparison of LS-11 vs PI531230 demonstrated significant upregulation of PLASMA MEMBRANE AQUAPORIN 1 and AUXIN RESPONSE FACTOR 22 in both the main and lateral root, which are associated with transmembrane water transport and the auxin-activated signaling system, respectively. There is also an upregulation of BASIC HELIX-LOOP-HELIX 5 in the main root and a downregulation in the lateral root, which is ascribed to sodium ion transmembrane transport, as well as an upregulation of THE MEDIATOR COMPLEX 1 assigned to water transport in the lateral root and a downregulation in the main root. Gene-protein interaction analysis found that more genes interacting with aquaporins proteins were upregulated in the lateral root than in the main root. We inferred that deeper main roots with longer lateral roots emanating from the bottom of the main root were ideal for tall fescue water uptake and salt tolerance, rather than many shallow roots, and that, while both main lateral roots may play similar roles in salt sensing and water uptake, there are intrinsic genomic differences.

A Nanosyntactic Analysis of Arabic Complementizers

This study investigates the syntactic composition of complementizers in Arabic from a nanosyntactic perspective (Starke, 2009). The study unravels the dichotomy in the behavior of root complementizers in Arabic; it highlights how the selection of complementizers is impacted by presupposed information and the degree of certainty. In spoken varieties of Arabic, such as Jordanian Arabic and Lebanese Arabic, root complementizers are blocked from root positions, but such positions are accessible for Modern Standard Arabic. Refining Ross' (1970) hidden verbs theorem and Fassi Fehri’s (2012) featural distinction, the study shows that if a complementizer is selected by different triggers of veridicality, such as ʔanna in MSA, ʔɨnn in Jordanian Arabic and ʔɘnno in Lebanese Arabic, the complementizer cannot appear without its trigger, whereas if a complementizer is selected by one trigger, such as ʔɪnna in MSA, the complementizer can be used in root positions without a trigger. Comparing the findings of the study with Baunz' (2018) universal hierarchy, we show that the hierarchy in its current status fails to account for Arabic data. The conclusion gives a stronger contribution for the semantic composition of complementizers.

Is a non-radiological-assisted method valid for establishing crown-root relationships in an orthodontic set-up incorporating the roots? A retrospective study

This study aimed to obtain information on the relationship between crown and root in terms of morphology - dimensions and crown-root angles -to be used for orthodontic set-ups without the use of radiological examinations. All the good quality CBCTs of patients obeying the eligibility criteria, from 2000 to 2015, were analysed. All teeth were analysed except for third molars. Six variables were evaluated: crown (CL) and root length (RL), crown width (CW), root width (RW), crown-root angles in both the frontal (CR-frontal) and sagittal plane (CR-sagittal). All teeth were divided into 3 groups according to number of root (single, two, three-rooted). The measurements were assessed with the Invivo professional software and then, subjected to correlation matrices and linear regression statistical analysis in order to find any significant correlations between crown and root measurements (α≤0.05). Seventy-three out of 247 good quality CBCTs were assessed. Correlation matrices statistical analysis showed linear correlations for some variables investigated, especially for CW/RW pairing in all subgroups (r=0.81, r=0.70 and r=0.58 respectively for single-, two- and three-rooted) and CL/RL in the single-rooted subgroup (r=0.29). Subsequent linear regression analysis allowed to obtain information about roots starting from crown measurements by means of equations [RW=0.76+(0.73×CW) and RL=10.94+(0.25×CL) for single-rooted teeth; RL=1.11+(0.73×CW) and RW=0.99+(0.76×CW), respectively for single- and two-rooted teeth]. No linear correlation was found between crown measurements and C-R angular values. It is possible to obtain root information starting from some crown measurements but these do not fulfil the need of minimal information to guarantee a perfect root position starting from that of crown.

Study on the effect of sulfonic acid root position on the stability of SDBS emulsified asphalt

Emulsified asphalt systems require emulsifiers to reduce oil–water interfacial energy generation to improve their stability. In this paper, the effect of the molecular structure of the SDBS emulsifier on the stability of emulsified asphalt was investigated using microscopic simulation (MD) and macroscopic tests. The effect of the molecular structure of asphalt emulsifiers on the stability of emulsified asphalt was quantified by varying the position of sulfonic acid roots in SDBS (2-1ΦC12S, 3-1ΦC12S, 4-1ΦC12S). The macroscopic tests included conventional, laser particle size tests and differential scanning calorimetry tests. The simulation results showed that 4-1ΦC12S reduced the oil–water interface energy the most and was the most hydrophilic, forming a more stable emulsified asphalt system; 2-1ΦC12S and 3-1ΦC12S were less stable due to the spatial site resistance effect of the sulfonic acid root position too close to the alkyl chain end. The test results showed that 4-1ΦC12S emulsified asphalt, with the smallest volume mean particle size, had the best thermal stability. Therefore, the isomer type of SDBS has a greater influence on the stability of emulsified asphalt, and 4-1ΦC12S has a better emulsification effect. The results indicate that future molecular structure synthesis of emulsifiers needs to fully consider the effect of isomers of emulsifiers on the emulsification effect, and the results of this paper can provide a theoretical basis for the future synthesis of high-performance emulsifiers.

X-RAY ASSESSMENT OF THE OROANTRAL COMMUNICATION POTENTIAL RISK IN PATIENTS DEPENDING ON GENDER

Tooth extraction is the most common operation in the practice of a dentist-surgeon. With the increase in the number of surgical interventions, the number of complications also increases, one of which is the occurrence of an oroantral communication with the maxillary sinus. Knowing the causes and patterns of the prevalence of potential risk factors can significantly reduce the number of complications. Thus, the need to diagnose the presence of a potential risk of an oroantral communication formation comes to the fore. Cone beam computed tomography is the most informative and accessible method of radiodiagnosis of the relative position of the upper jaw teeth roots and maxillary sinus. This article presents the results of a study of the dependence of potential anatomical risk factors on the patient's gender according to cone-beam computed tomography.

Evaluation of root position during orthodontic treatment via multiple intraoral scans with automated registration technology

This study aimed to introduce a method for dynamically monitoring root position with intraoral scans using automated crown registration and root segmentation with artificial intelligence technology and to evaluate its accuracy using a novel semiautomatic root apical distance measurement procedure. The sample consisted of 412 teeth from 16 patients whose intraoral scans and cone-beam computed tomography (CBCT) were obtained before and after treatment. Crowns from intraoral scans and roots segmented from CBCT with artificial intelligence technology before treatment were registered, integrated, and divided into individual teeth. With an automated registration program, the virtual root was constructed by crown registration before and after treatment. The distance deviation of the root position at the apex between the virtual root and the actual root, which served as a control, was measured and decomposed into the distance deviation in the mesiodistal and buccolingual directions. The shell deviation of crown registration between CBCT and oral scan before treatment was 0.19 ± 0.04 mm and 0.22 ± 0.04 mm in the maxilla and mandible, respectively. The apical root position distance deviations were 0.27 ± 0.12 mm in the maxilla and 0.31 ± 0.11 mm in the mandible. There was no significant difference between root position in mesiodistal and buccolingual directions. Applying automated crown registration and root segmentation with artificial intelligence technology in this study improved the accuracy and efficiency of monitoring root position. In addition, the innovative semiautomatic distance measurement procedure can more precisely distinguish the root position discrepancy.

Mandarin overt wh-fronting as focus movement

This study reexamines the syntactic encoding of information structure embodied by Mandarin overt wh-fronting questions. The sentence patterns that this paper is concerned with are wh-questions containing one or more fronted wh-phrases surfacing in (i) a clause-initial position (in root or non-root contexts) or (ii) a position immediately following a topicalized subject (also in root or non-root contexts). Departing from previous literature that obscures the exhaustifying effect exerted by a clause-initial shi ‘be’, I propose a more fine-grained classification of the focus interpretations of this type of question: a bare wh-fronting question coerces a plain (non-exhaustive) contrastive focus or a mirative focus reading (when the wh-phrase is prosodically marked) of the wh-variable, and shi-marked wh-fronting questions are shown to enforce an exhaustive focus in the answer. These three types of focus-associated interpretations are treated as conventional implicatures following Bianchi et al. (2015).

Estimating the occurrence of labial bone perforation and implantation into the maxillary sinus maxillary premolars based on the morphology of maxillary premolars: A clinical study

Statement of problemPrevious studies have classified the sagittal root position of the maxillary anterior teeth and measured buccal plate thickness to aid treatment planning. A thin labial wall and buccal concavity may cause buccal perforation, dehiscence, or both in maxillary premolars. However, data on the restoration-driven principle to classify the maxillary premolar region are lacking. PurposeThe purpose of this clinical study was to investigate the occurrence of labial bone perforation and implantation into the maxillary sinus between various tooth-alveolar classifications with respect to the crown axis in maxillary premolars. Material and methodsCone beam computed tomography images of 399 participants (1596 teeth) were analyzed to determine the probability of labial bone perforation and implantation into the maxillary sinus when associated with variables that included tooth position and tooth-alveolar classification. ResultsThe morphology in the maxillary premolars was classified as straight, oblique, or boot-shaped. The first premolars were 62.3% straight, 37.0% oblique, and 0.8% boot-shaped, and labial bone perforation occurred in 4.2% (21 of 497) of the straight, 54.2% (160 of 295) of the oblique, and 83.3% (5 of 6) of the boot-shaped first premolars when the virtual implant was 3.5×10 mm. When the virtual tapered implant was 4.3×10 mm, labial bone perforation occurred in 8.5% (42 of 497) of the straight, 68.5% (202 of 295) of the oblique, and 83.3% (5 of 6) of the boot-shaped first premolars. The second premolars were 92.4% straight, 7.5% oblique, and 0.1% boot-shaped, and labial bone perforation occurred in 0.5% (4 of 737) of the straight, 33.3% (20 of 60) of the oblique, and 0% (0 of 1) of the boot-shaped, respectively, when the virtual tapered implant was 3.5×10 mm; and labial bone perforation occurred in 1.3% (10/737) of the straight, 53.3% (32/60) of the oblique, and 100% (1/1) of the boot-shaped second premolars when the virtual tapered implant was 4.3×10 mm. ConclusionsWhen an implant is placed in the long axis of a maxillary premolar, the tooth position and tooth-alveolar classification should be considered when assessing the risk of labial bone perforation. Attention should be paid to the implant direction, diameter, and length in the oblique and boot-shaped maxillary premolars.

Consonance and Dissonance of Simultaneous Trichords in Western Music

Previous empirical studies have suggested that the perceived consonance/dissonance (C/D) of a musical chord depends on its psychoacoustic smoothness (lack of roughness), spectral harmonicity (perceptual fusion), and/or musical familiarity. We tested the dependence of C/D on smoothness and harmonicity in a hearing experiment that included all 19 possible trichords in musical pitch-class set theory. In each trial, a listener heard a chord (duration: 300 or 500 ms) and rated its C/D on an 11-point scale. Each trichord was presented 10 times: 4 times constructed from octave-complex tones (OCTs, sounding like an electronic organ) and 6 times from natural piano tones. Each OCT chord was presented in 4 different transpositions. The piano chords were in close or open position, and root position or 1st/2nd inversion (2 levels of spacing x 3 levels of inversion = 6 levels of voicing). We found no main effect of timbre (OCT versus piano) and no interaction between trichord and timbre. Results correlated closely with predictions of simple models of roughness and harmonicity. The roughness model performed better, and the predictions correlated with each other. A combined model was not superior to roughness alone. The results were consistent with a multifactorial model of the C/D of a musical chord, the main factors being roughness, harmonicity, and familiarity.

Influence of pilot H[formula omitted] injection on methane-air swirled flame stabilization and acoustic response

Large Eddy Simulation is used to investigate the effect of localized pilot H2 injection on the Flame Transfer Function (FTF) of a premixed CH4-air swirled flame. The response of a perfectly premixed methane-air flame is compared to the one with an additional pilot hydrogen injection that supplies 10% of the original power. Numerical simulations are validated against experiments in terms of global FTF values at selected forcing frequencies, acoustic pressure and velocity signals, CH* flame images and flame root position dynamics. The unforced cases are first considered showing that, when H2 is injected in the center, the flame becomes slightly lifted with a localized diffusion front above the pilot injection. As in the experiments, LES retrieves that hydrogen pilot injection leads to a global redistribution of the heat release rate towards the flame root due to higher burning rates which translates to an overall FTF gain reduction over the entire frequency range explored. Then, the flame acoustic response for the two injection strategies is scrutinized at two distinct forcing frequencies: 240 Hz where the FTF gain difference is maximum, and 590 Hz where the FTF phase shift is maximum. LES reveals that, despite H2 pilot injection does not modify the dynamics of the large vortical structures shed in the external shear layer of the swiling jet which are synchronized by the acoustic forcing, the redistribution of the heat release rate towards the flame base weakens their interaction with the flame tip, explaining partly the FTF gain reduction at the two selected frequencies. In addition to that, a marked axial movement of the internal recirculation zone is observed at 240 Hz during the forcing cycle. For the pilot injection, it leads to an oscillation of the lifted flame root while, for the CH4-air case, the flame anchoring point is not affected. This additional oscillation leads for the pilot case to heat release rate fluctuations acting in phase opposition with respect to those observed at the flame tip, generating a further drop of the FTF gain at this specific frequency. The increased burning rate at the flame root and the flame length reduction of the pilot hydrogen flame also affect the characteristic time lag of the flame response. For both frequencies f = 240 Hz and 590 Hz, the phase shift between the two injection strategies is proportional to the flame length reduction caused by hydrogen injection. These simulations confirm that pilot hydrogen injection is an efficient way to reduce the acoustic response of swirled flames over a large frequency bandwidth.