Low Pitch Research Articles

EMIC Wave‐Driven Bounce Resonance Scattering of Energetic Electrons in the Inner Magnetosphere

AbstractWhile electromagnetic ion cyclotron (EMIC) waves have been long studied as a scattering mechanism for ultrarelativistic (megaelectron volt) electrons via cyclotron‐resonant interactions, these waves are also of the right frequency to resonate with the bounce motion of lower‐energy (approximately tens to hundreds of kiloelectron volts) electrons. Here we investigate the effectiveness of this bounce resonance interaction to better determine the effects of EMIC waves on subrelativistic electron populations in Earth's inner magnetosphere. Using wave and plasma parameters directly measured by the Van Allen Probes, we estimate bounce resonance diffusion coefficients for four different events, illustrative of wave and plasma parameters to be encountered in the inner magnetosphere. The range of electron energies and pitch angles affected is examined to better assess the realistic effects of EMIC‐driven bounce resonance on energetic electron populations based on actual, locally observed event‐based parameters. Significant local diffusion coefficients (~ > 10−6 s−1) for 50‐ to 100‐keV electrons are achieved for both H+ band wave events as well as He+ band, with diffusion coefficients peaking for near‐90° pitch angles but remaining elevated for intermediate ones as well. Diffusion coefficients for higher‐energy 200‐keV electrons are typically multiple orders of magnitude lower (ranging from 10−11 to 10−6 s−1) and often peak at lower pitch angles (~20–30°). These results suggest that both H+ and He+ band EMIC waves can play a role in shaping lower‐energy electron dynamics via bounce‐resonant interactions, in addition to their role in relativistic electron loss via cyclotron resonance.

Comparison of Pitch Accent in Native Speakers of English & Mandarin Learners of English

This research project was conducted as a pilot study to explore how pitch accent is used by NCES (Native Canadian English Speakers) and MLE (Mandarin Learners of English). Pitch accents are the prominent high or low tones, that are predominantly found on content words (N, V, Adv, Adj, etc.) in English. In order to compare how both speech communities use pitch accent in English, participants were given an EI (Elicited Imitation) Task. The EI involved participants hearing and then repeating a sentence. It is also reconstructive in nature meaning that the participants process the sentence, then reconstruct it with their own grammar, and finally reproduce it. The results showed that Mandarin speakers had more pitch accents than English speakers, adding pitch accents on function words (Art, Pro, Prep, etc.) as well. The results also demonstrated that Mandarin speakers had less creaky words (words said in a very low pitch, also known as laryngealization or vocal fry) than the English participants. Implications of this study concern ESL Education; such as should English pitch accent patterns and creak in English be taught to English language learners.

Geometric optimisation of piezoelectric fan arrays for low energy cooling

A numerical model of a typical piezoelectric fan blade is derived and validated against experimental data. Numerical error is found to be 5.4% and 9.8% using two data comparison methods. The model is used to explore the variation of pitch as a function of amplitude, A, for a confined two-blade piezoelectric fan array in face-to-face orientation, with the blades oscillating both in-phase and counter-phase. It has been reported that in-phase oscillation is optimal for generating maximum downstream velocity and flow rate in unconfined conditions, due at least in part to the beneficial coupling between the adjacent blades that leads to an increased oscillation amplitude. The present model demonstrates that confinement has a significant detrimental effect on in-phase oscillation. Even at low pitch, counter-phase oscillation produces enhanced downstream air velocities and flow rates. Downstream air velocity from counter-phase oscillation can be maximally enhanced, relative to that generated from a single blade, by 17.7% at P=8A. Flow rate enhancement at the same pitch is found to be 18.6%. By comparison, in-phase oscillation at the same pitch outputs 23.9% and 24.8% reductions in peak downstream air velocity and flow rate, relative to that generated from a single blade. This optimal pitch, equivalent to those reported in the literature, suggests that counter-phase oscillation is less affected by confinement. The optimal pitch for generating bulk airflow from counter-phase oscillation is large, P>16A, due to the small but significant downstream velocity across the span between adjacent blades. However, by considering design in a confined space, counter-phase pitch should be minimised to maximise the bulk airflow generated from a certain cross-sectional area within a channel flow application. Quantitative values are found to deviate to a small degree as other geometric and operational parameters are varied, but the established relationships are maintained.

Screws with larger core diameter and lower thread pitch increase the stability of locked plating in osteoporotic proximal humeral fractures

BackgroundLittle is known about the screw design as a factor for stability of the bone-implant interface in locking plate fixation of proximal humeral fractures. Aim of the present study was to analyze if locking screws with a large core diameter and a low thread pitch provide increased stability when compared to conventional locking screws. Methods3-Part proximal humeral fractures were created in ten pairs of osteoporotic human cadaveric humeri and fixed with a locking plate. Head fixation was performed with screws with a large core diameter (soft bone screws) in one humerus and with conventional cancellous locking screws in the other humerus of each donor. Specimens were loaded in the varus bending position. Stiffness, failure loads, plate bending and motion at the bone-implant interface were evaluated using mechanical sensors and an optical motion capture system. FindingsThe stiffness of the construct for the soft bone screws was 299.8 N/mm (IR, 72.1 N/mm) and 203.9 N/mm (IR, 37.3 N/mm) for the conventional locking screws (p = 0.005). Plate bending did not differ between the two groups. Motion at the bone-implant interface was significantly reduced in the soft bone screw group (p < 0.05). The median load-to-failure was significantly higher in the soft bone screw group (358 N vs. 313 N; p = 0.012). InterpretationThe use of soft bone screws is associated with less motion at the bone-implant interface and therefore greater fixation strength when compared to fixation with conventional locking screws. Clinical studies are needed to prove these biomechanical findings in the in vivo situation.Level of evidence: Controlled laboratory study.

Loudness Trumps Pitch in Politeness Judgments: Evidence from Korean Deferential Speech.

Social meaning is not conveyed through words alone, but also through how words are produced phonetically. This paper investigates the role of loudness and pitch in determining the perception of politeness-related judgments in Korean. It has been proposed that high pitch is universally associated with polite or deferential social meanings. In contrast to this, Experiment 1 examined the perceptual effect of pitch and found no effect. Experiment 2 tested the effect of loudness, and found that listeners associate quieter speech with deference. Finally, Experiment 3 investigated the simultaneous effects of loudness and pitch, and found again that loudness had a consistent effect, whereas pitch only had a weak effect. Analyses of individual differences suggest that in contrast to loudness, which is interpreted uniformly across Korean listeners, pitch has more variegated social meanings: Some listeners associate high pitch with deferential meaning, others associate low pitch with deferential meaning. Thus, we find loudness to be a more unambiguous indicator of deferential speech than pitch. These findings shed light on how different acoustic properties contribute to the indexing of social stances, and they suggest that the role of pitch in conveying politeness may have been overstated in past research.

An Acoustic Examination of Pitch Variation in Soprano Singing

The ability to perform acoustic inspection of data and to correlate the results with perceptual and physiological aspects facilitates vocal behavior analysis. The singing voice has specific characteristics and parameters that are involved during the phonation mechanism, which may be analyzed acoustically. To describe and analyze the fundamental frequency and formants in pitch variation in the /a/ vowel in sopranos. The sample consisted of 30 female participants between the ages of 20 to 45 years without vocal complaints. All sustained vowel sounds were recorded with the /a/ vowel sustained for 5 seconds, with three replications at low (C4-261 Hz), medium (Eb4-622 Hz), and high (Bb4-932 Hz) frequencies that were comfortable for the voice classification. In total, 90 samples were analyzed with digital extraction of the fundamental frequency (f0) and the first five formants (F1, F2, F3, F4, and F5) and manual confirmation. The middle segment was considered for analysis, whereas the onset and offset segments were not considered. Subsequently, FFT (fast Fourier transform) plots, LPC (linear predictive coding) graphs, and tube diagrams were created. The Shapiro-Wilks test was applied for adherence and the Friedman test was applied for comparison of paired samples. For vocalizations at low and medium pitches, higher values were observed for the first five formant frequencies than for the f0 value. Overlaying the LPC and FFT graphs revealed a similarity between F1 and F2 at the two pitches, with clustered harmonics in the F3, F4, and F5 region in the low pitch. At the medium pitch, there was similarity between F3 and F4, an F5 peak, and tuned harmonics. However, in the high-pitch vocalizations, there was an increase in the F2, F3, F4, and F5 values in relation to f0, and there was similarity between them along with synchrony between f0 and F1, H2 and F2, H3 and F3, H4 and F4, and H5 and F5. Pitch changes indicate differences in the behavior of the fundamental frequency and sound formants in sopranos. The comparison of the sustained vowels sounds in f0 at the three pitches revealed specific vocal tract changes on the LPC curve and FFT harmonics, with an extra gain range at 261 Hz, synchrony between peaks of formants and harmonics at 622 Hz, and equivalence of f0 and F1 at 932 Hz.

Convective heat transfer studies on helically corrugated tubes with spiraled rod inserts using TiO2/DI water nanofluids

Convective heat transfer and friction factor studies are experimentally carried out in a smooth and five helically corrugated tubes of different heights and pitches of corrugation with spiraled rod inserts. The experiment is conducted under turbulent flow (Re = 4800–8900) and constant wall heat flux conditions. Deionized (DI) water and titanium dioxide (TiO2)/DI water nanofluids are used as working fluids. The average size of TiO2 nanoparticles is 32 nm. Two volume concentrations of nanofluids (0.25 and 0.5%) are used in this study. The combined effects of nanofluids, inserts and corrugation in tubes on Nusselt number and friction factor are investigated. The results indicate that (i) the addition of TiO2 nanoparticles in DI water upsurges the heat transfer rate, which increases with nanofluids volume concentrations; (ii) use of inserts and corrugation in tubes enhances the heat transfer rate further; (iii) among the corrugated tubes, the tube having highest corrugation height (hc = 1 mm) and lowest pitch (pc = 8 mm) with spiraled rod insert of smaller pitch (pi = 30 mm) shows the maximum thermal performance factor of 1.56 for 0.5% volume concentration of nanofluids.

Aerodynamic characteristics and surface flow structures of moderate aspect-ratio leading-edge tubercled wings

Abstract Aerodynamic performance for NACA634-021 wings with different leading-edge (LE) tubercle configurations was tested under both finite- and infinite- wing conditions, and the general results show that larger tubercle amplitude A leads to gentler stall and smaller tubercle wavelength λ improve maximum lift. The ratios of tubercle amplitude and wavelength to wing chord, A/c and λ /c, as well as the A/ λ ratio should be considered together to determine the optimum design. Wings with smaller A and λ shows relatively better performance with lift-to-drag ratio significantly enhanced at lower pitch angles, which are also associated with their cruise condition. Surface flow structures for the tubercled wings under finite-wing condition were specially revealed by the fluorescent oil visualization technique. High quality nice fluorescent images reveal that wavy laminar separation bubbles (LSBs) are formed on pressure surface for the tubercled wings at lower pitch angles, with the waviness of LSBs strongly depending on those of wavy LE. Wavy LSB for the two wings with the largest tubercle A are even transited into small surface counter-rotating vortex-pairs (CRVPs). On the suction surface, separated flows behind the troughs also lead to surface CRVPs due to the spanwise pressure gradient. In addition, LSBs formed behind the tubercle peaks for the wings with smaller λ also resemble the surface CRVPs, possibly driven by the flow shearing arising from the narrower regions of upstream surface CRVPs. In the post-stall regime, except for the wing with larger tubercle λ andsmallest A, other tubercled wings are observed to induce drastically attached flows on suction surface, especially downstream of tubercle peaks.

High-Pitch Wide-Coverage Fast-Kilovoltage-Switching Dual-Energy CT: Impact of Pitch on Noise, Spatial Resolution, and Iodine Quantification in a Phantom Study.

The purpose of this study was to assess the impact of high pitch values on image noise, spatial resolution, and iodine quantification in single-source wide-coverage fast-kilovoltage-switching dual-energy CT (DECT). Two phantom experiments were conducted. First, image noise and spatial resolution in the x-, y-, and z-directions were assessed. Second, the accuracy of iodine quantification was investigated with multiple-size phantoms with pure iodine and blood-iodine inserts. Both phantoms were scanned repeatedly with a third-generation fast-kilovoltage-switching DECT scanner with a collimation width of 80 mm at four different pitch values (0.5, 0.99, 1.375, 1.53) and three different gantry rotation times (0.6, 0.8, 1.0 second). Image noise, spatial resolution, and absolute error of iodine concentration (E) were measured. A linear mixed effects model was used to determine the effect of pitch, rotation time, and size on the error of iodine concentration. Image noise and xy spatial resolution were comparable among the four pitch values. Spatial resolution in the z-direction was inferior and had higher variance at a low pitch of 0.5 compared with pitches of 0.99, 1.375, and 1.53. Error of iodine concentration was significantly affected by pitch and rotation time (p < 0.001). E decreased with increasing pitch and decreasing rotation time. In detail, mean E was 0.91 ± 0.47 mg I/mL for a pitch of 0.5, 0.52 ± 0.29 mg I/mL for 0.99, 0.44 ± 0.25 mg I/mL for 1.375, and 0.40 ± 0.25 mg I/mL for 1.53. High-pitch wide-coverage fast-kilovoltage-switching DECT can be performed without impairing image quality or iodine quantification, and the results are superior to those of imaging at a low pitch of 0.5.

Symmetric Versus Asymmetric Pitching of a Cycloidal Rotor Blade at Ultra-Low Reynolds Numbers

This paper provides a fundamental understanding of the unsteady aerodynamic phenomena on a cycloidal rotor blade operating with symmetric as well as asymmetric pitching at ultralow Reynolds numbers () by using a combination of experimental (force and flowfield measurements) and computational fluid dynamics (CFD) studies. The instantaneous blade fluid dynamic forces on a rotating cycloidal rotor blade were measured, which, along with particle image velocimetry (PIV) based flowfield measurements revealed the key fluid dynamic mechanisms acting on the blade. A two-dimensional CFD analysis of the cycloidal rotor was developed and systematically validated using both force and flowfield measurements. The CFD flow solution and PIV-measured flowfield correlated well, especially in the upper half of the circular blade trajectory, and both showed the formation and shedding of strong dynamic stall or leading-edge vortices at high pitch amplitudes, which is the reason for the stall delay and force enhancement. The dynamic virtual camber induced by the flow curvature decreased the blade lift in the upper half due to negative induced camber; however, the lift increased in the lower half due to positive camber. Therefore, introducing an asymmetry in pitch kinematics with higher pitch in the upper half and lower pitch in the bottom half counteracted this inherent lift asymmetry and improved efficiency through a more uniform lift production.

Relating tinnitus features and audiometric characteristics in a cohort of 34 tinnitus subjects

Although tinnitus, the conscious perception of a sound without a sound source external or internal to the body, is highly correlated with hearing loss, the precise nature of such correlation remains still unknown. People with high pitch tinnitus are used to suffer from high frequency hearing losses, and vice versa, low pitch tinnitus is mostly associated with low frequency hearing losses. However, many subjects with low or high frequency losses do no develop tinnitus. Thus, studies trying to relate audiometric characteristics and tinnitus features are still relevant. This article presents a correlational study of audiometric and tinnitus variables in a sample of 34 subjects, paying special attention to the heterogeneous subtypes of both audiometry shape and tinnitus etiology. Our results, which concur with others previously published, demonstrate that the tinnitus pitch, the main frequency of the tinnitus spectrum, in subjects with high-steep high-frequency and continuously steep hearing losses, are highly correlated with the frequency at which hearing loss reaches 50 dB HL.

Impact of Blade Flexibility on Wind Turbine Loads and Pitch Settings

Along with the upscaling tendency, lighter and so more flexible wind turbine blades are introduced for reducing material and manufacturing costs. The flexible blade deforms under aerodynamic loads and in turn affects the flow field, arising the aeroelastic problems. In this paper, the impacts of blade flexibility on the wind turbine loads, power production, and pitch actions are discussed. An advanced aeroelastic model is developed for the study. A free wake vortex lattice model instead of the traditionally used blade element momentum (BEM) method is used to calculate the aerodynamic loads, and a geometrically exact beam theory is adopted to compute the blade structural dynamics. The flap, lead-lag bending, and torsion degrees-of-freedom (DOFs) are all included and nonlinear effects due to large deflections are considered. The National Renewable Energy Laboratory (NREL) 5 MW reference wind turbine is analyzed. It is found that the blade torsion deformations are significantly affected by both the aerodynamic torsion moment and the sectional aerodynamic center offset with respect to the blade elastic axis. Simulation results further show that the largest bending deflection of the blade occurs at the rated wind speed, while the torsion deformation in toward-feather direction continuously increases along with the above-rated wind speed. A significant reduction of the rotor power is observed especially at large wind speed when considering the blade flexibility, which is proved mainly due to the blade torsion deformations instead of the pure-bending deflections. Lower pitch angle settings are found required to maintain the constant rotor power at above-rated wind speeds.

The phonological status of Low tones in Shanghai tone sandhi

Abstract In Shanghai tone sandhi, with the exception of T5 (yangru) sandhi, a pitch-fall occurs at the second or third syllable of a phonological word (or a sandhi domain). Previous analyses argue that this is invoked by the insertion of a default Low tone to satisfy the Well-formedness Condition of the autosegmental theory. However, in the framework of the present autosegmental theory, that condition is no longer necessarily satisfied, and an alternative interpretation, adopting a boundary Low tone, has been suggested. To evaluate the appropriateness of the default and boundary interpretations, we compared pitch contours among di- to tetrasyllabic words in greater detail. The results show that, in T1 to T4 sandhi, disyllabic words tend to have lower pitch contours than tri- and tetrasyllabic words at the first and second syllables, and that, in tetrasyllables, minimum pitch values were constantly attested at the third syllable. These results indicate that in Shanghai tone sandhi, a boundary Low tone is assigned at the right edge of a phonological word, and it is further associated with the third syllable in tetrasyllables. This boundary interpretation further gives an appropriate explanation of the difference of the pitch-fall between Middle and New Shanghai.

Evaluation of Low-contrast Detectability of Iterative Reconstruction Algorithm in High-speed CT Technology for Head

The purpose of this study was to assess the feasibility of high-speed CT technology for head without deterioration of low-contrast detectability using the brain LCD (Canon Medical Systems) of iterative reconstruction. System performance (SP) function analysis, low-contrast object specific contrast-to-noise ratio (CNRLO) analysis, and visual evaluation using Scheffe's paired comparison were performed. Additionally, analysis of the correlation of CNRLO and visual scores was performed. SP was performed with the self-made phantom. CNRLO was calculated with the catphan 504 phantom (CTP 515). Visual evaluation was performed using the brain phantom which simulated such as cerebral infarction and investigated on a fivepoint scale. All images were acquired with pitch factor of 0.61 (low pitch) and 1.40 (high pitch). All images were reconstructed with filtered back projection (FBP), brain LCD standard (LCD STD) and strong (LCD STR). SP of brain LCD improved compared with FBP. CNRLO of FBP decreased in high pitch compared with low pitch. CNRLO of brain LCD images acquired by low- and high pitch were improved compared with FBP. Visual scores denoted similar trends to that of CNRLO and there was high correlation with CNRLO. It was suggested that using brain LCD can achieve the high speed CT technology for head without deterioration of low-contrast detectability.

A Sweet Voice: The Influence of Cross-Modal Correspondences Between Taste and Vocal Pitch on Advertising Effectiveness.

We have seen a rapid growth of interest in cross-modal correspondences between sound and taste over recent years. People consistently associate higher-pitched sounds with sweet/sour foods, while lower-pitched sounds tend to be associated with bitter foods. The human voice is key in broadcast advertising, and the role of voice in communication generally is partly characterized by acoustic parameters of pitch. However, it remains unknown whether voice pitch and taste interactively influence consumer behavior. Since consumers prefer congruent sensory information, it is plausible that voice pitch and taste interactively influence consumers' responses to advertising stimuli. Based on the cross-modal correspondence phenomenon, this study aimed to elucidate the role played by voice pitch-taste correspondences in advertising effectiveness. Participants listened to voiceover advertisements (at a higher or lower pitch than the original narrator's voice) for three food products with distinct tastes (sweet, sour, and bitter) and rated their buying intention (an indicator of advertising effectiveness). The results show that the participants were likely to exhibit greater buying intention toward both sweet and sour food when they listened to higher-pitched (vs lower-pitched) voiceover advertisements. The influence of a higher pitch on sweet and sour food preferences was observed in only two of the three studies: studies 1 and 2 for sour food, and studies 2 and 3 for sweet food. These findings emphasize the role that voice pitch-taste correspondence plays in preference formation, and advance the applicability of cross-modal correspondences to business.

Effect of Chin-Down Position on Vocal Mean Pitch and Intensity

Abstract Background Voice, a unique characteristic of each individual, is an outcome of the configuration and function of various components of the vocal tract. Pitch and loudness, being integral parts of voice, vary with changes in factors such as muscle tension, subglottal pressure, and position. Chin down is often the recommended voice therapy for lowering pitch. But there is no literature available as to by how much does it actually change the mean pitch and intensity. The present study was undertaken to understand the effect on the vocal mean pitch and intensity when head position is changed to chin-down position. Methods Thirty women aged 18 to 25 years were included in this preliminary study. Individuals having any history of voice disorder were excluded. Voice samples were collected using clinical microphone and acoustically analyzed using the Praat software. The participants were instructed to phonate and count numbers in neutral position and chin down position. Results It was observed that there was no change in the acoustic or perceptual measure of pitch with change in the head position. However, there was a significant reduction in the intensity for phonation task in the chin-down position. Conclusion Speech language pathologists need to provide chin down as a facilitative technique for lowering larynx along with other voice therapies which are proved to effectively lower pitch.

Meeting the Mahatma.

Meeting the Mahatma.

Nanostructured Anti-Reflection Coatings for Enhancing Transmission of Light

Nanostructured, sub-wavelength anti-reflection layers (NALs) have attracted much attention as a new generation of anti-reflection surfaces. Among different designs, sub-wavelength periodic nanostructures are capable of enhancing transmission of coherent light through an interface without inducing scattering. In this work, we have explored a new profile for periodic NALs capable of transmitting IR light with higher efficiency compared to NALs based on a parabolic profile. To achieve high transmission and low diffraction, the profile and pitch of the nanostructured NALs are calculated using a combination of a multi-layer modeling and Rigorous Coupled Wave (RCWA) analysis.

Impact resistance of nanocellulose films with bioinspired Bouligand microstructures.

The Bouligand structure features a helicoidal (twisted plywood) layup of fibers that are uniaxially arranged in-plane and is a hallmark of biomaterials that exhibit outstanding impact resistance. Despite its performance advantage, the underlying mechanisms for its outstanding impact resistance remain poorly understood, posing challenges for optimizing the design and development of bio-inspired materials with Bouligand microstructures. Interestingly, many bio-sourced nanomaterials, such as cellulose nanocrystals (CNCs), readily self-assemble into helicoidal thin films with inter-layer (pitch) angles tunable via solvent processing. Taking CNC films as a model Bouligand system, we present atomistically-informed coarse-grained molecular dynamics simulations to measure the ballistic performance of thin films with helicoidally assembled nanocrystals by subjecting them to loading similar to laser-induced projectile impact tests. The effect of pitch angle on the impact performance of CNC films was quantified in the context of their specific ballistic limit velocity and energy absorption. Bouligand structures with low pitch angles (18–42°) were found to display the highest ballistic resistance, significantly outperforming other pitch angle and quasi-isotropic baseline structures. Improved energy dissipation through greater interfacial sliding, larger in-plane crack openings, and through-thickness twisting cracks resulted in improved impact performance of optimal pitch angle Bouligand CNC films. Intriguingly, decreasing interfacial interactions enhanced the impact performance by readily admitting dissipative inter-fibril and inter-layer sliding events without severe fibril fragmentation. This work helps reveal structural and chemical factors that govern the optimal mechanical design of Bouligand microstructures made from high aspect ratio nanocrystals, paving the way for sustainable, impact resistant, and multi-functional films.

A peculiar case of hearing loss followed years later by tinnitus and vertigo

Vestibular paroxysmia (also known as disabling positional vertigo) is a clinical syndrome generated by a symptomatic neurovascular compression of the eighth cranial nerve. Although doubted by some authors, this syndrome must be suspected in presence of brief spells of positional vestibular symptoms associated with temporary or permanent but worsening cochlea-vestibular symptoms and signs, not explained by other diseases. We report a case of a 20-year-old girl affected by permanent sensorineural hearing loss on the right since the age of 4-5 years, who subsequently developed intermittent low pitch tinnitus on the right ear and spells of vertigo or dizziness generated by position or physical activity. Angio-MRI of the brain showed a singular neurovascular contact between the right vertebral artery and the right eighth cranial nerve. The excellent response to carbamazepine confirms the presence of this syndrome.