Specific Modulation Frequencies Research Articles

Comparison of the Performance of Bioresonance, Electrophoresis and RT-PCR in the Diagnosis of Feline Infectious Peritonitis.

Feline infectious peritonitis (FIP) continues to be one of the most researched infectious diseases of cats. The diagnosis of FIP is challenging, and diverse techniques have been developed for its accurate diagnosis. However, they have some limitations. The present study was conducted to investigate the efficacy of specific modulation frequency (SMF), compared to other routine diagnostic methods for detecting feline coronavirus. Blood samples were collected from 30 diseased cats suspected of having FIP based on clinical signs. Electrophoresis, polymerase chain reaction (PCR), and SMF tests were performed for each sample. The sensitivity and specificity of each test, as well as the agreement between the tests and the gold standard (the combination of PCR, electrophoresis, and bioresonance results), were calculated using the Kappa coefficient method. The sensitivity and specificity of electrophoresis, PCR, and SMF for the diagnosis of FIP were 70.6%, 70.6%, 100%, and 100%, 72.7%, 81.8%, respectively. According to the findings of the present study, SMF is effective and safe in FIP diagnosis, which is a challenge in veterinary medicine diagnosis.

Evaluation of a Specific Modulation Frequency Technique for Detecting H. pylori in a Model of Experimentally Infected Mice.

Diagnosis of Helicobacter pylori is challenging. Diverse techniques have been developed for accurate diagnosis. However, they have some limitations. This research investigated the efficacy of specific modulation frequency (SMF) compared to other routine diagnostic methods for detecting H. pylori in gastric biopsy samples of experimentally infected mice. One-hundred and fifty healthy male C57BL/6 mice were included and divided into the control and treatment groups. The mice in the treatment group were treated with 0.2 ml of 0.2 M NaHCO3 to neutralize gastric acidity. Then, 109 colony-forming units of H. pylori (ATCC 43504) mixed in PBS were used intragastrically to inoculate the mice. Mice were kept for up to 28 days and examined on days 0, 7, 14, 21, and 28 using culture, polymerase chain reaction (PCR), and SMF. On day 0, only the SMF and PCR could detect the H. pylori in the stomach of 60% and 20% of mice, respectively. On day 7, culture, PCR, and SMF could detect H. pylori in 40%, 80%, and 100% of mice, respectively. SMF detected all infected mice from days 7 to 28 (100%). PCR detected all H. pylori-infected mice at days 14 to 27 (100%). Another test (culture) detected all infected mice only on day 28. Significant differences were found among the three diagnostic methods on days 0, 7, 14, and 21 of the experiment (P<0.05). SMF was found to have high sensitivity and specificity for H. pylori detection in the early stages of infection.

Dual tapered optical fiber for simultaneous detection of curvature and strain

We present a study of simultaneous detection of curvature and strain in optical fiber. This contains a micro tapered section and a nano tapered section. The transmission spectrum shows interference of multiple modes, and the frequency of the modulation can be used to distinguish and monitor specific physical parts of the fiber structure. The curvature detection is achieved using one specific modulation frequency component; this component shows an intensity modulation with a sensitivity of 0.26 dB/m−1. The strain information is extracted by applying a phase analysis over a second spatial frequency component; this analysis shows a sensitivity close to 8 mrad/με. The strain phase analysis exhibits a linear response, and the intensity curvature data indicates an exponential model. The proposed signal analysis can be employed for simultaneous detection in optical fiber interferometric sensors.

Multicomponent gas detection technology of FDM and TDM based on photoacoustic spectroscopy.

In this paper, a multicomponent gas detection system based on photoacoustic spectroscopy (PAS) is proposed with a combination of frequency division multiplexing (FDM) and time division multiplexing (TDM), combining a resonance photoacoustic cell and broadband microphone. A PAS gas cell with a wide frequency response bandwidth was used to achieve the FDM by selecting a specific modulation frequency of each component gas. The sawtooth wave driver current of each laser was output at a constant time interval for achieving the TDM. Compared with the laser channel control using a photoswitch, the driver current control was a simpler and more convenient means to implement TDM. The four gas components of methane (CH4), water (H2O) vapor, carbon dioxide (CO2), and acetylene (C2H2) were selected as sample gases for testing the feasibility of the method. The experimental results showed that the gas detection limits of CH4, H2O vapor, CO2, and C2H2 were 75.435, 2.502, 341.960, and 4.284 ppm, respectively. In addition, the linear fittings of gas concentration were 0.99386, 0.99772, 0.98995, and 0.98955, respectively.

Tune modulation effects for colliding beams in the High Luminosity Large Hadron Collider

Several transverse noise sources, such as power supply ripples, can potentially act as an important limiting mechanism for the luminosity production of the Large Hadron Collider (LHC) and its future High-Luminosity upgrade (HL-LHC). In the presence of non-linearities, depending on the spectral components of the power supply noise and the nature of the source, such a mechanism can increase the diffusion of the particles in the distribution through the excitation of sideband resonances in the vicinity of the ones driven by the lattice non-linearities. For the HL-LHC, due to the reduction of the beam size in the Interaction Points (IP) of the high luminosity experiments (IP1 and 5), increased sensitivity to noise effects is anticipated for the quadrupoles of the inner triplets. The modulation that may arise from the power supply ripples will be combined with the tune modulation that intrinsically emerges from the coupling of the transverse and longitudinal plane for off-momentum particles through chromaticity. To this end, the aim of this paper is to study the impact of tune modulation effects on the transverse beam motion resulting from the interplay between quadrupolar power supply ripples and synchro-betatron coupling. A power supply noise threshold for acceptable performance is estimated with single-particle tracking simulations by investigating the impact of different modulation frequencies and amplitudes on the Dynamic Aperture. The excitation of sideband resonances due to the modulation is demonstrated with frequency maps and the higher sensitivity to specific modulation frequencies is explained. Finally, a power supply noise spectrum consisting of several tones is considered in the simulations to determine whether the presence of power supply ripples in the quadrupoles of the inner triplet will limit the luminosity production in the HL-LHC era.

Effect of fuel line acoustics on the flame dynamics of H2/CH4 syngas in a partially premixed gas turbine combustor

This paper investigates the dynamic response of flames, considering H2-enriched CH4 fuels that are submitted to upstream mechanical perturbations in a model gas turbine combustor, resulting in fuel velocity oscillations. Flame transfer function (FTF) and cold-flow transfer function (CTF), which represent, respectively, the dynamic responses in the flow of the flame and fuel induced by a velocity modulation in the fuel feed line (FFL), are derived. The gain of FTF shows a low-pass behavior and gradually increases until a specific modulation frequency is reached, which is identical to the frequencies of the corresponding peak gains of the CTF. The periodic variation of OH* intensity is observed from the images collected with a high-speed OH-PLIF. The high oscillation near the injector indicates that the fuel velocity perturbation leads to the amplification of the heat release fluctuation at specific modulation frequencies. The singularity frequencies corresponding to the peaks of the gain of both transfer functions coincide with the resonance frequencies in the FFL. The phase of FTF and CTF decreases as the H2 ratio increases and the phase of FTF is well fitted into a single line by nondimensionalization through Strouhal number. Most of these findings on the characteristics of combustion instability and acoustical characteristics of FFL can be used as a crucial methodology of H2 combustor design, such as an anti-resonance fuel/air feed line, which can ensure the stable operation of combustion system by avoiding H2 induced combustion instability failure.

Measurements and analysis of diode laser modulation wavelength at high accuracy and response rate

It is a key procedure of measuring the diode laser wavelength in the wavelength modulation spectroscopy (WMS) technique since it determines the selection of specific modulation amplitude and frequency and thus the overall accuracy of the WMS technique. However, the wavelength modulation frequency of lasers is usually from tens of kHz to hundreds of kHz, which makes the traditional methods difficult to measure the wavelength with the sufficient accuracy and time response rate. Therefore, in this paper, we developed a method to measure the modulated wavelength with improved accuracy and time response rate by using a customized long fiber ring etalon. In the method, the free spectral range (FSR) of the etalon was determined by using two adjacent absorption lines of water. And the amplitude of the laser wavelength and its phase relative to the driving voltage were determined by means of interference peak identification and sinusoidal fitting. Finally, we used the developed method to measure dynamic wavelengths as well as phases of a distribute feedback (DFB) diode laser with the modulation frequency from 1 to 500 kHz and the modulation voltage from 0.2 to 1 V. Based on the measurements, the response characteristics of both the linear and nonlinear wavelengths as well as phases with modulation frequency and amplitude were obtained, which provide necessary data for the application of quantitative and high-repetition WMS technique in combustion diagnostics.

Two-photon frequency division multiplexing for functional in vivo imaging: a feasibility study.

Recently, we presented a new approach to create high-speed amplitude modulation of femtosecond laser pulses and tag multiple excitation beams with specific modulation frequencies. In this work, we discuss the utility of this method to record calcium signals in brain tissue with two-photon frequency-division multiplexing (2P-FDM) microscopy. While frequency-multiplexed imaging appears slightly inferior in terms of image quality as compared to conventional two-photon laser scanning microscopy due to shot noise-induced cross-talk between frequency channels, applying this technique to record average signals from regions of interest (ROI) such as neuronal cell bodies was found to be promising. We use phase information associated with each pixel or waveform within a selected ROI to phase-align and recombine the signals into one extended amplitude-modulated waveform. This procedure narrows the frequency detection window, effectively decreasing noise contributions from other frequency channels. Using theoretical analysis, numerical simulations, and in vitro imaging, we demonstrate a reduction of cross-talk by more than an order of magnitude and predict the usefulness of 2P-FDM for functional studies of brain activity.

Exploring Auditory-Inspired Acoustic Features for Room Acoustic Parameter Estimation From Monaural Speech

Room acoustic parameters that characterize acoustic environments can help to improve signal enhancement algorithms such as for dereverberation, or automatic speech recognition by adapting models to the current parameter set. The reverberation time (RT) and the early-to-late reverberation ratio (ELR) are two key parameters. In this paper, we propose a blind ROom Parameter Estimator (ROPE) based on an artificial neural network that learns the mapping to discrete ranges of the RT and the ELR from single-microphone speech signals. Auditory-inspired acoustic features are used as neural network input, which are generated by a temporal modulation filter bank applied to the speech time-frequency representation. ROPE performance is analyzed in various reverberant environments in both clean and noisy conditions for both fullband and subband RT and ELR estimations. The importance of specific temporal modulation frequencies is analyzed by evaluating the contribution of individual filters to the ROPE performance. Experimental results show that ROPE is robust against different variations caused by room impulse responses (measured versus simulated), mismatched noise levels, and speech variability reflected through different corpora. Compared to state-of-the-art algorithms that were tested in the acoustic characterisation of environments (ACE) challenge, the ROPE model is the only one that is among the best for all individual tasks (RT and ELR estimation from fullband and subband signals). Improved fullband estimations are even obtained by ROPE when integrating speech-related frequency subbands. Furthermore, the model requires the least computational resources with a real time factor that is at least two times faster than competing algorithms. Results are achieved with an average observation window of 3 s, which is important for real-time applications.

Firing-rate resonances in the peripheral auditory system of the cricket, Gryllus bimaculatus.

In many communication systems, information is encoded in the temporal pattern of signals. For rhythmic signals that carry information in specific frequency bands, a neuronal system may profit from tuning its inherent filtering properties towards a peak sensitivity in the respective frequency range. The cricket Gryllus bimaculatus evaluates acoustic communication signals of both conspecifics and predators. The song signals of conspecifics exhibit a characteristic pulse pattern that contains only a narrow range of modulation frequencies. We examined individual neurons (AN1, AN2, ON1) in the peripheral auditory system of the cricket for tuning towards specific modulation frequencies by assessing their firing-rate resonance. Acoustic stimuli with a swept-frequency envelope allowed an efficient characterization of the cells' modulation transfer functions. Some of the examined cells exhibited tuned band-pass properties. Using simple computational models, we demonstrate how different, cell-intrinsic or network-based mechanisms such as subthreshold resonances, spike-triggered adaptation, as well as an interplay of excitation and inhibition can account for the experimentally observed firing-rate resonances. Therefore, basic neuronal mechanisms that share negative feedback as a common theme may contribute to selectivity in the peripheral auditory pathway of crickets that is designed towards mate recognition and predator avoidance.

Auditory envelope following responses in the mature and developing human brain

Event Abstract Back to Event Auditory envelope following responses in the mature and developing human brain Huizhen Tang1*, Jon Brock1, Stephen Crain2 and Blake Johnson1 1 Macquarie University , Cognitive Science , Australia 2 Macquarie University , Linguistics , Australia Recent theories of speech perception propose that the speech envelope (the overall waveform of the speech signal) plays a crucial role in speech perception by aligning brain excitability patterns with the intensity fluctuations of the speech sounds. We tested two main hypotheses derived from these theories: (1) That the sound envelope provides crucial cues for encoding of temporal information in sounds; (2) that temporal encoding is not fully mature in preschool-aged children (3 to 5 years old). The acoustic stimulus was a broadband noise amplitude-modulated in a continuous sweep of frequencies from 1 to 80 Hz. Brain responses were measured with magnetoencephalography. The adult temporal modulation transfer function showed precise and continuous phase tracking throughout the frequency range, while children showed significantly worse tracking at both high and low modulation frequencies. Adult and child transfer functions also differed significantly in their preferred modulation frequencies, and hemispheric asymmetries. These results are the first to describe the auditory temporal modulation transfer function in preschool children. They show that the immature brain differs markedly from the adult brain in its capacity to encode temporal information in sounds. These results must be accounted for by neurolinguistic theories that emphasize the role of specific temporal modulation frequencies for the neural encoding of speech. Keywords: Auditory Perception, Brain Mapping, Language, Magnetoencephalography, Brain Development Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Language Citation: Tang H, Brock J, Crain S and Johnson B (2015). Auditory envelope following responses in the mature and developing human brain. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00363 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Ms. Huizhen Tang, Macquarie University, Cognitive Science, North Ryde, Australia, joann.tang@mq.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Huizhen Tang Jon Brock Stephen Crain Blake Johnson Google Huizhen Tang Jon Brock Stephen Crain Blake Johnson Google Scholar Huizhen Tang Jon Brock Stephen Crain Blake Johnson PubMed Huizhen Tang Jon Brock Stephen Crain Blake Johnson Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Low levels of radiofrequency electromagnetic fields and cancer cell proliferation in vivo.

e15049 Background: The incidence of hepatocellular carcinoma (HCC) is increasing but five-year survival remains dismal. Intrabuccal administration of amplitude-modulated radiofrequency electromagnetic fields (RF EMF) is a novel, non-invasive treatment modality resulting in whole body absorption of very low levels of RF EMF. Recent studies show that this approach elicits radiological responses in patients with HCC and breast cancer (J Exp Clin Cancer Res, 2009, 28:51; Br J Cancer, 2011, 105:640). Using an in vitro exposure system replicating the levels of exposure achieved in humans, we have shown that HCC cells and breast cancer cells are growth inhibited by HCC-specific and breast cancer-specific frequencies, respectively. Additionally, RF EMF exposure causes modulation of gene expression and disruption of the mitotic spindle (Br J Cancer 2012, 106:307). Methods: HCC cells were exposed to radiofrequency electromagnetic fields modulated at specific frequencies previously identified in HCC patients. MicroRNA arrays compared exposed and control groups of HCC cells. HCC cells were injected subcutaneously in NOD SCID mice. Following palpable tumor establishment, mice were exposed to HCC-specific RF EMF at a specific absorption rate of 0.4 W/kg and euthanized following excessive tumor burden. Results: We identified increased levels of miRNAs targeting proteins belonging to the PI3K pathway, specifically IP3/DAG signaling and intracellular calcium release, a pathway frequently disrupted in HCC and breast cancer. While HCC xenografts grew in control mice, we observed significant tumor shrinkage in mice exposed to HCC-specific modulation frequencies and residual xenograft tumor cells were infiltrated with fibrous tissue and showed significantly decreased proliferation and increased apoptosis. There was no evidence of altered cell proliferation or fibrosis in other organs. Conclusions: These findings are the first in vivo evidence of the efficacy of RF EMF in HCC and uncover a novel mechanism that targets cancer cell growth at specific modulation frequencies, by means of changes in PI3K signaling and release of intracellular calcium.

Abstract 5612: Cancer cell proliferation is inhibited by specific modulation frequencies.

Abstract Purpose: Hepatocellular carcinoma (HCC) incidence in the US is dramatically increasing. Five-year survival remains 3-5%, demonstrating urgent need for additional therapies. Intrabuccal administration of amplitude modulated electromagnetic fields (RF EMF) is a novel, minimally invasive treatment modality which results in whole body absorption of very low levels of RF EMF. Clinical studies show that this treatment approach elicits therapeutic responses in patients with hepatocellular carcinoma and breast cancer. Using an in vitro exposure system replicating the levels of exposure achieved in humans, we have described a phenotype in HCC cells following RF EMF exposure that included proliferative inhibition, modulation of gene expression, and disruption of the mitotic spindle. This phenotype was specific for HCC cells exposed to HCC-specific RF EMF at exposure levels ranging from 0.03 to 0.4 W/kg. Methods: HCC cells were exposed to 27.12 MHz electromagnetic fields modulated at specific frequencies from 400 Hz to 21 kHz, previously identified in HCC patients. MicroRNA arrays compared exposed and control groups of HCC cells, with microRNA validation followed by Western blot of target genes and proteins. HCC xenografts were injected subcutaneously in NOD SCID mice. Following palpable tumor establishment, mice were exposed to HCC-specific RF EMF at a specific absorption rate of 0.4 W/kg, euthanized following excessive tumor burden, and evaluated by immunohistochemistry. Results: We identified increased levels of miRNAs targeting proteins belonging to the PI3K pathway, specifically IP3/DAG signaling and intracellular calcium release. This pathway is frequently disrupted in HCC and breast cancer, making it an excellent candidate for modulation by RF EMF; furthermore, downstream effects include: cell cycle progression, proliferation, inhibition of apoptosis, and cell migration. We observed tumor shrinkage in mice exposed to HCC-specific modulation frequencies and residual xenograft tumor cells were infiltrated with fibrous tissue and showed significantly decreased proliferation and increased apoptosis. There was no evidence of altered cell proliferation or fibrosis in other organs. Conclusion: These findings are the first evidence of the efficacy and safety of RF EMF in HCC using a subcutaneous xenograft model and uncover a novel mechanism that controls cancer cell growth in vivo at specific modulation frequencies, possibly through modulation of PI3K signaling and downstream release of intracellular calcium. Citation Format: Hugo Jimenez, Jacquelyn W. Zimmerman, Michael J. Pennison, Ivan Brezovich, Nengjun Yi, Celeste T. Yang, Ryne Ramaker, Devin Absher, Richard M. Myers, Niels Kuster, Frederico P. Costa, Alexandre Barbault, Boris Pasche. Cancer cell proliferation is inhibited by specific modulation frequencies. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5612. doi:10.1158/1538-7445.AM2013-5612 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Abstract 916A: Cancer cell proliferation is inhibited by specific modulation frequencies

Abstract Background: Hepatocellular carcinoma (HCC), a leading cause of cancer death worldwide, now has the fastest growing rate in the United States. The intrabuccal administration of amplitude modulated electromagnetic fields (AM-EMF) is a novel, minimally invasive treatment modality. There is clinical evidence that this novel treatment approach elicits therapeutic responses in patients with cancer (1, 2). However, there is no known mechanism explaining the anti-proliferative effect of very low intensity electromagnetic fields. Methods: Hepatocellular carcinoma cells were exposed to 27.12 MHz radiofrequency electromagnetic fields using in vitro exposure systems designed to replicate in vivo conditions. Cancer cells were exposed to tumor-specific modulation frequencies, previously identified by biofeedback methods in patients with a diagnosis of cancer. Control modulation frequencies consisted of randomly-chosen modulation frequencies within the same 100 Hz to 21 kHz range as cancer-specific frequencies. Growth inhibition was evaluated by measuring tritiated thymidine incorporation. RNA-Seq was used to identify genes with differential expression in cells exposed to HCC-specific AM-EMF. Confocal laser scanning microscopy allowed the visualization of the mitotic spindle. Karyotype assessment compared HepG2 receiving HCC-specific AM-EMF to those not receiving exposure. Results: The growth of hepatocellular carcinoma and breast cancer cells was significantly decreased by hepatocellular carcinoma-specific and breast cancer-specific modulation frequencies, respectively. However, the same frequencies did not affect proliferation of nonmalignant hepatocytes or breast epithelial cells. Inhibition of hepatocellular carcinoma cell proliferation was associated with downregulation of XCL2 and PLP2. Furthermore, hepatocellular carcinoma-specific modulation frequencies disrupted the mitotic spindle. Karyotype analysis was unrevealing. Conclusion: These findings uncover a novel mechanism controlling the growth of cancer cells at specific modulation frequencies without affecting normal tissues, which may have broad implications in oncology. Reference List (1) Barbault A, Costa F, Bottger B, Munden R, Bomholt F, Kuster N, et al. Amplitude-modulated electromagnetic fields for the treatment of cancer: Discovery of tumor-specific frequencies and assessment of a novel therapeutic approach. Journal of Experimental &amp; Clinical Cancer Research 2009;28:51. (2) Costa FP, de Oliveira AC, Meirelles R, Machado MCC, Zanesco T, Surjan R, et al. Treatment of advanced hepatocellular carcinoma with very low levels of amplitude-modulated electromagnetic fields. Br J Cancer 2011;105:640-8. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 916A. doi:1538-7445.AM2012-916A

Cancer cell proliferation is inhibited by specific modulation frequencies

Background:There is clinical evidence that very low and safe levels of amplitude-modulated electromagnetic fields administered via an intrabuccal spoon-shaped probe may elicit therapeutic responses in patients with cancer. However, there is no known mechanism explaining the anti-proliferative effect of very low intensity electromagnetic fields.Methods:To understand the mechanism of this novel approach, hepatocellular carcinoma (HCC) cells were exposed to 27.12 MHz radiofrequency electromagnetic fields using in vitro exposure systems designed to replicate in vivo conditions. Cancer cells were exposed to tumour-specific modulation frequencies, previously identified by biofeedback methods in patients with a diagnosis of cancer. Control modulation frequencies consisted of randomly chosen modulation frequencies within the same 100 Hz–21 kHz range as cancer-specific frequencies.Results:The growth of HCC and breast cancer cells was significantly decreased by HCC-specific and breast cancer-specific modulation frequencies, respectively. However, the same frequencies did not affect proliferation of nonmalignant hepatocytes or breast epithelial cells. Inhibition of HCC cell proliferation was associated with downregulation of XCL2 and PLP2. Furthermore, HCC-specific modulation frequencies disrupted the mitotic spindle.Conclusion:These findings uncover a novel mechanism controlling the growth of cancer cells at specific modulation frequencies without affecting normal tissues, which may have broad implications in oncology.

燃料噴射率への周期的変動付加が噴霧形成に及ぼす影響(ディーゼル噴霧とその燃焼,内燃機関の燃焼化学と排出物制御)

The effect of injection rate modulation on the spatial dispersion of fuel droplets and inner structure of fuel spray were investigated by high-speed sectional photographs of fuel spray. To obtain the injection modulation, an electronically controllable fuel injection system developed at this laboratory was used. Through the experiments ranging from OHz to 6.5kHz of modulation frequency, it was confirmed that the shape of spray with injection rate modulation became pulse like one from a specific modulation frequency. It is considered that the pulse like spray is the result of the catching up motion of the high velocity droplets crowd.

Evidence for interactions across frequency channels in the inferior colliculus of awake chinchilla

As a result of cochlear processing, information about acoustic broadband signals is distributed across many parallel frequency channels. Periodic modulations of signal envelopes – conspicuous in particular in harmonic signals – may extend across a wide frequency range and give rise to temporal response patterns in the auditory nerve, particularly useful for recombination of constituents and the separation of the signals from background noise. Herein we report evidence that across frequency processing as necessary for binding of related signal components occurs already in the auditory midbrain of mammals. Extracellular recordings were made from 231 multi and single units in the inferior colliculus of awake chinchillas. Loud pure tones evoked onset type excitation (26%) and suppression of spontaneous rate (60%) not only in the range of the units’ characteristic frequency (CF), but also in a frequency range far above CF. About 80% of all units tuned to CFs below 3 kHz gave sustained responses to low level stimuli of high frequencies (>2CF) provided the tones were sinusoidally amplitude modulated (SAM) with a unit specific modulation frequency although none of the spectral components of the amplitude modulation alone was sufficient to evoke such a response, even at high intensities. Low level high carrier SAM responses and wide band onset responses as well as inhibition must have their origin in a non-linear across frequency channel interaction of neuronal information. Many aspects of these responses cannot be explained by peripheral distortion in the cochlea. We therefore propose a mechanism of integration across frequency channels that may originate within the inferior colliculus and/or the nuclei of the lateral lemniscus. This process may lead to the binding of information that shares a common periodicity and may thereby help to distinguish different acoustic objects.

Human auditory steady-state responses to amplitude-modulated tones: phase and latency measurements

Human auditory steady-state responses were recorded to four stimuli, with carrier frequencies ( f c) of 750, 1500, 3000 and 6000 Hz, presented simultaneously at 60 dB SPL. Each carrier frequency was modulated by a specific modulation frequency ( f m) of 80.6, 85.5, 90.3 or 95.2 Hz. By using four different recording conditions we obtained responses for all permutations of f m and f c. The phase delays ( P) of the responses were unwrapped and converted to latency ( L) using the equation: L= P/(360× f m). The number of cycles of the stimulus that occurred prior to the recorded response was estimated by analyzing the effect of modulation frequency on the responses. These calculations provided latencies of 20.7, 17.7, 16.1 and 16.1 ms for carrier frequencies 750, 1500, 3000 and 6000 Hz. This latency difference of about 4.5 ms between low and high carrier frequencies remained constant over many different manipulations of the stimuli: faster modulation rates (150–190 Hz), binaural rather than monaural presentation, different intensities, stimuli presented alone or in conjunction with other stimuli, and modulation frequencies that were separated by as little as 0.24 Hz. This frequency-related delay is greater than that measured using transient evoked potentials, most likely because of differences in how transient and steady-state responses are generated and how their latencies are determined.

Intrinsic envelope fluctuations and modulation-detection thresholds for narrow-band noise carriers.

A model is presented which calculates the intrinsic envelope power of a bandpass noise carrier within the passband of a hypothetical modulation filter tuned to a specific modulation frequency. Model predictions are compared to experimentally obtained amplitude modulation (AM) detection thresholds. In experiment 1, thresholds for modulation rates of 5, 25, and 100 Hz imposed on a bandpass Gaussian noise carrier with a fixed upper cutoff frequency of 6 kHz and a bandwidth in the range from 1 to 6000 Hz were obtained. In experiment 2, three noises with different spectra of the intrinsic fluctuations served as the carrier: Gaussian noise, multiplied noise, and low-noise noise. In each case, the carrier was spectrally centered at 5 kHz and had a bandwidth of 50 Hz. The AM detection thresholds were obtained for modulation frequencies of 10, 20, 30, 50, 70, and 100 Hz. The intrinsic envelope power of the carrier at the output of the modulation filter tuned to the signal modulation frequency appears to provide a good estimate for AM detection threshold. The results are compared with predictions on the basis of the more complex auditory processing model by Dau et al.

Depth profiling of thin surface layers using the amplitude modulation method in radiofrequency-powered glow discharge optical emission spectrometry

A novel technique for accurate in-depth analysis of thin layers is described. Radiofrequency voltages applied to a Grimm-style glow discharge lamp are modulated at a very low frequency, which leads to a reduction in the sputtering rate and variation of the emission signals at the specific modulation frequency. With amplitude modulation associated with phase-sensitive detection, the resultant emission intensities can be measured with better signal-to-noise ratios, although the sputtering rate and the sampling amount are reduced by a factor of ∽10. It is possible to obtain the depth profile of a 13 nm thick Ni-electroplated layer, whereas profiling is difficult for conventional detection. © 1999 John Wiley & Sons, Ltd.