scholarly journals Critical Repetition Rates for Perceptual Segregation of Time-Varying Auditory, Visual and Vibrotactile Stimulation

2021 ◽  
pp. 1-20
Author(s):  
Carlos Jurado ◽  
Marcelo Larrea ◽  
David Rosero ◽  
Juan Vizuete ◽  
Torsten Marquardt
Keyword(s):  
Pressure Fluctuations ◽  
Perceptual Quality ◽  
Vibrotactile Stimulation ◽  
Experimental Conditions ◽  
Sensory Modalities ◽  
Recovery Times ◽  
Distinctive Property ◽  
Hearing Range ◽  
Domain Similarity ◽  
Main Factor

Abstract What sound quality has led to exclude infrasound from sound in the conventional hearing range? We examined whether temporal segregation of pressure pulses is a distinctive property and evaluated this perceptual limit via an adaptive psychophysical procedure for pure tones and carriers of different envelopes. Further, to examine across-domain similarity and individual covariation of this limit, here called the critical segregation rate (CSR), it was also measured for various periodic visual and vibrotactile stimuli. Results showed that sequential auditory or vibrotactile stimuli separated by at least ~80‒90 ms (~11‒12-Hz repetition rates), will be perceived as perceptually segregated from one another. While this limit did not statistically differ between these two modalities, it was significantly lower than the ~150 ms necessary to perceptually segregate successive visual stimuli. For the three sensory modalities, stimulus periodicity was the main factor determining the CSR, which apparently reflects neural recovery times of the different sensory systems. Among all experimental conditions, significant within- and across-modality individual CSR correlations were observed, despite the visual CSR (mean: 6.8 Hz) being significantly lower than that of both other modalities. The auditory CSR was found to be significantly lower than the frequency above which sinusoids start to elicit a tonal quality (19 Hz; recently published for the same subjects). Returning to our initial question, the latter suggests that the cessation of tonal quality — not the segregation of pressure fluctuations — is the perceptual quality that has led to exclude infrasound (sound with frequencies < 20 Hz) from the conventional hearing range.

Modeling Control Adaptations During Recovery From Anterior Cruciate Ligament Reconstruction

2013 ◽  
Author(s):  
Louis A. DiBerardino ◽  
Harry Dankowicz ◽  
Elizabeth T. Hsiao-Wecksler
Keyword(s):  
Anterior Cruciate Ligament ◽  
Ligament Reconstruction ◽  
Cruciate Ligament ◽  
Functional Results ◽  
Compensation Strategy ◽  
Anterior Cruciate Ligament Repair ◽  
Recovery Times ◽  
Anterior Cruciate ◽  
Functional Task ◽  
Main Factor

In this paper, we aim to model a functional task affected by injury, along with the corresponding neuromuscular compensation strategy, in order to understand differences in task performance during recovery from the injury. This study is motivated by differing rates of functional task improvements during recovery from anterior cruciate ligament repair. In particular, clinical studies have shown faster recovery times for single-limb forward hopping versus single-limb crossover hopping (hopping back and forth laterally while moving forward). Modeling this hopping task will help us understand whether the main factor of the differing functional results is from the physical restrictions of the injury, the compensation strategies used to overcome these restrictions, or a combination of both. Our hypothesis is that the discrepancies in clinical functional results will be reproduced by employing a feedforward compensation strategy, where the compensation is learned and adjusted over time.

scholarly journals Model analysis of the relationship between intracellular Po2 and energy demand in skeletal muscle

2012 ◽  
Vol 303 (11) ◽  
pp. R1110-R1126 ◽  
Author(s):  
Jessica Spires ◽  
L. Bruce Gladden ◽  
Bruno Grassi ◽  
Gerald M. Saidel ◽  
Nicola Lai
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Contraction ◽  
Energy Demand ◽  
Experimental Studies ◽  
Experimental Conditions ◽  
Permeability Surface ◽  
The Relationship ◽  
And Diffusion ◽  
Main Factor

On the basis of experimental studies, the intracellular O2 (iPo2)-work rate (WR) relationship in skeletal muscle is not unique. One study found that iPo2 reached a plateau at 60% of maximal WR, while another found that iPo2 decreased linearly at higher WR, inferring capillary permeability-surface area ( PS) and blood-tissue O2 gradient, respectively, as alternative dominant factors for determining O2 diffusion changes during exercise. This relationship is affected by several factors, including O2 delivery and oxidative and glycolytic capacities of the muscle. In this study, these factors are examined using a mechanistic, mathematical model to analyze experimental data from contracting skeletal muscle and predict the effects of muscle contraction on O2 transport, glycogenolysis, and iPo2. The model describes convection, O2 diffusion, and cellular metabolism, including anaerobic glycogenolysis. Consequently, the model simulates iPo2 in response to muscle contraction under a variety of experimental conditions. The model was validated by comparison of simulations of O2 uptake with corresponding experimental responses of electrically stimulated canine muscle under different O2 content, blood flow, and contraction intensities. The model allows hypothetical variation of PS, glycogenolytic capacity, and blood flow and predictions of the distinctive effects of these factors on the iPo2-contraction intensity relationship in canine muscle. Although PS is the main factor regulating O2 diffusion rate, model simulations indicate that PS and O2 gradient have essential roles, depending on the specific conditions. Furthermore, the model predicts that different convection and diffusion patterns and metabolic factors may be responsible for different iPo2-WR relationships in humans.

Concrete and Abstract Terms and Relations in Testing a Rule

1974 ◽  
Vol 26 (3) ◽  
pp. 355-359 ◽  
Author(s):  
K. J. Gilhooly ◽  
W. A. Falconer
Keyword(s):  
Abstract Form ◽  
Experimental Conditions ◽  
Improved Performance ◽  
Main Factor

Subjects have more difficulty in correctly testing a conditional rule stated in abstract form than the same rule given in “thematic” form. The “thematic” form of the rule involves both concrete terms and a concrete relation. Four experimental conditions were formed by combining concrete abstract terms and relations. Fifty subjects were tested in each condition. The results indicated that concrete-ness of the terms is the main factor leading to improved performance with “thematic” as against abstract material in the rule testing task.

Wavelet decomposition of hydrodynamic and acoustic pressures in the near field of the jet

2017 ◽  
Vol 813 ◽  
pp. 716-749 ◽  
Author(s):  
Matteo Mancinelli ◽  
Tiziano Pagliaroli ◽  
Alessandro Di Marco ◽  
Roberto Camussi ◽  
Thomas Castelain
Keyword(s):  
Near Field ◽  
Pressure Fluctuations ◽  
Hydrodynamic Pressure ◽  
Far Field ◽  
Simple Arrangement ◽  
Number Variation ◽  
Distinctive Property ◽  
Processing Techniques ◽  
Measured Pressure ◽  
Higher Sensitivity

An experimental investigation of pressure fluctuations generated by a single-stream compressible jet is carried out in an anechoic wind tunnel. Measurements are performed using a linear array of microphones installed in the near region of the jet and a polar arc of microphones in the far field. The main focus of the paper is on the analysis of the pressure fluctuations in the near field. Three novel signal processing techniques are presented to provide the decomposition of the near-field pressure into hydrodynamic and acoustic components. The procedures are all based on the application of the wavelet transform to the measured pressure data and possess the distinctive property of requiring a very simple arrangement to obtain the desired results (one or two microphones at most). The hydrodynamic and acoustic pressures are characterized separately in terms of their spectral and statistical quantities and a direct link between the acoustic pressure extracted from the near field and the actual noise in the far field is established. The analysis of the separated pressure components sheds light on the nearly Gaussian nature/intermittent behaviour of the acoustic/hydrodynamic pressure. The higher sensitivity of the acoustic component to the Mach number variation has been highlighted as well as the different propagation velocities of the two pressure components. The achieved outcomes are validated through the application to the same data of existing separation procedures evidencing the advantages and limitations of the new methods.

Turbulent pressure fluctuations on surface of model vascular stenoses

1991 ◽  
Vol 261 (3) ◽  
pp. H644-H650 ◽  
Author(s):  
H. M. Loree ◽  
R. D. Kamm ◽  
C. M. Atkinson ◽  
R. T. Lee
Keyword(s):  
Peak Pressure ◽  
Plaque Rupture ◽  
Pressure Fluctuations ◽  
Experimental Conditions ◽  
Flow Rates ◽  
Turbulent Pressure ◽  
Stenosis Severity ◽  
Artery Flow ◽  
Diameter Reduction ◽  
Carotid Flow

Turbulence frequently develops when blood passes through a stenosis. To study the hypothesis that turbulence near a plaque surface can cause pressure fluctuations that may promote plaque rupture, models of intravascular stenoses were studied. Experimental conditions simulated peak flow in the coronary and carotid arteries through a stenosis of 80 or 90% diameter reduction and into a region where the plaque had widened distally to a 50-75% stenosis. For symmetric stenoses at carotid artery flow rates, peak pressure fluctuations were observed 1-1.5 upstream diameters distal to the stenosis, but there were no significant turbulent pressure fluctuations at coronary artery flow rates. Stenosis asymmetry strongly increased the intensity of turbulent pressure fluctuations at flows simulating carotid flow and resulted in significant pressure fluctuations for coronary flow conditions. Increasing stenosis severity from 80 to 90% increased the root mean square pressure fluctuations 3.6-fold. These studies predict peak to peak pressure fluctuations of 15 mmHg in a 90% asymmetric coronary stenosis; it is possible that turbulence may play a role in acute damage of atherosclerotic plaques, particularly in asymmetric stenoses.

Predicting multisensory enhancement in neuronal responses

2012 ◽  
Vol 25 (0) ◽  
pp. 3
Author(s):  
Benjamin A. Rowland
Keyword(s):  
Alternative Hypothesis ◽  
Initial Response ◽  
Neuronal Responses ◽  
Experimental Conditions ◽  
Sensory Modalities ◽  
Response Enhancement ◽  
Multisensory Enhancement ◽  
Response Profiles ◽  
The Individual ◽  
Statistical Noise

The most dramatic physiological example of multisensory integration is response enhancement, where the integration of concordant signals across multiple sensory modalities leads to a larger and more reliable response. In the model system of the superior colliculus, the largest enhancements (often greater than the predicted sum) are observed when the individual signals being combined are weak. This principle conforms to expectations based on signal detection theory, and also as expected, enhancement is not uniform throughout any response. Typically it is greatest near its onset, when the unisensory inputs are at their weakest (Initial Response Enhancement, see Rowland et al., 2007; Rowland and Stein, 2008). Despite the general accuracy of this heuristic, however, there is a substantial amount of variance in the degree of observed enhancement at all levels of responsiveness. This observation appears to violate standard Bayesian predictions that are based on overall response magnitude. Aside from statistical noise, a possible explanation is that individual neurons in the dataset are calibrated to different ‘computational modes’. An alternative hypothesis is that the amount of enhancement is influenced greatly by response properties other than magnitude, specifically, the temporal profile of the response. The present analysis advances the latter hypothesis. We present a mechanistic framework that explains these findings and extends the standard Bayesian approach to generate an accurate prediction for the multisensory response profile given known unisensory response profiles. These predictions offer a ‘null hypothesis’ that can be used to quantify the circumstances and timing of anomalies in the integrative processes in different experimental conditions; for example, when it is developing under different conditions, or when it is disrupted by experimental or surgical intervention at any stage of life.

Cavitation-Induced Unsteady Flow Characteristics in the First Stage of a Centrifugal Charging Pump

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Fan Zhang ◽  
Shouqi Yuan ◽  
Qiang Fu ◽  
Ji Pei ◽  
Martin Böhle ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Nuclear Power ◽  
Power Plants ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Absolute Error ◽  
Impeller Blade ◽  
Frequency Domains ◽  
Vapor Distribution ◽  
Main Factor

Cavitation is the main factor that causes reliability problems in centrifugal charging pumps (CCPs) in nuclear power plants. In this study, the cavitation-induced unsteady flow characteristics of a CPR1000 CCP were investigated by numerical and experimental methods. The vapor distribution in the impeller, velocity fluctuation, and pressure fluctuation results in the time and frequency domains were considered for several typical monitoring points in the impeller and volute. The pressure fluctuations in the impeller occurred at an impeller rotating frequency of fR and its integer harmonics, whereas those in the volute mainly occurred at an impeller blade-passing frequency of fB and its integer harmonics. The absolute error between the simulated and measured NPSHr was 3.6%, and that between the calculated and measured head was 2.9%, validating the simulation of the cavitation performances of a CCP.

scholarly journals Ultrasonic Vibration as a Primary Mixing Tool in Accelerating Aluminum–Copper Alloys Preparation from Their Pure Elements

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 781
Author(s):  
Abdulsalam Muhrat ◽  
Hélder Puga ◽  
Joaquim Barbosa
Keyword(s):  
Ultrasonic Vibration ◽  
Copper Alloys ◽  
Grain Refining ◽  
Alloying Element ◽  
Experimental Conditions ◽  
Melt Temperature ◽  
Cu Alloys ◽  
Aluminum Copper Alloys ◽  
Main Factor

In this study, ultrasonic vibration (USV) was evaluated in preparation of Al–8wt.%Cu alloys at a lab-scale. Moreover, the role of Ti–6Al–4V sonotrode erosion and its contribution in grain refining were analyzed. Based on the experimental conditions/parameters, it was found that the amount of impurities and the associated porosity were significantly reduced in USV treated alloys. Furthermore, USV reduced the time needed for dissolving the alloying element Cu, nevertheless, the best dissolving of Cu in this study was not possible without introducing further holding time. As a result of using a titanium-based sonotrode, a noticeable content of Ti was found in the ultrasonically treated alloys due to sonotrode erosion under USV. The dispersion of TiAl3 promoted, as a main factor, a grain refining effect at relatively constant and high melt temperature, other possible mechanisms of grain refining have been discussed.

scholarly journals Persistence of Bacteroides Species Populations in a River as Measured by Molecular and Culture Techniques

2010 ◽  
Vol 76 (22) ◽  
pp. 7608-7616 ◽  
Author(s):  
Elisenda Ballesté ◽  
Anicet R. Blanch
Keyword(s):  
Survival Rates ◽  
Environmental Parameters ◽  
Molecular Techniques ◽  
Fecal Coliforms ◽  
Source Tracking ◽  
Experimental Conditions ◽  
Culture Techniques ◽  
Do Concentration ◽  
Survival Patterns ◽  
Main Factor

ABSTRACT Given the interest in Bacteroides species as microbial source tracking (MST) markers, and the limited knowledge of the survival of Bacteroides species in the environment, here we examine the survival of Bacteroides fragilis, B. thetaiotaomicron, and environmental species of Bacteroides by use of culture techniques and molecular tools. Two kinds of experiments were performed: (i) on-site experiments, in which bacteria were exposed to changes in the levels of several environmental parameters in a river, and (ii) microcosm assays in the laboratory, with controlled temperatures. On-site experiments showed different survival patterns for the cultivable Bacteroides strains. B. fragilis die-off rate was strongly affected by the combined effect of high temperatures and grazing predators, which were more active under warmer conditions. However, the survival rates of cultivable B. thetaiotaomicron and environmental Bacteroides spp. were more affected by dissolved oxygen (DO) concentration in water. Environmental Bacteroides strains survived longer than either type strain, due to better adaptation to environmental conditions. However, the period of their survival was shorter than that observed for fecal coliforms and enterococci, suggesting Bacteroides species as markers of recent fecal pollution. The total Bacteroides species were detected by molecular techniques throughout the experiment in winter, but they were detected on only two or three days in the summer. This indicates that temperature is the main factor affecting DNA degradation, regardless of species. The use of microcosms in the laboratory also pointed to temperature as the main factor affecting Bacteroides survival, regardless of species. However, the conditions in the laboratory may mask the effects of the environmental factors and their interactions. The observed variability in die-off rate as a function of the species analyzed, the experimental conditions, and the methodology used should be taken into consideration in future persistence studies.

scholarly journals Road to Acquisition: Preparing a MEMS Microphone Array for Measurement of Fuselage Surface Pressure Fluctuations

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 961
Author(s):  
Thomas Ahlefeldt ◽  
Stefan Haxter ◽  
Carsten Spehr ◽  
Daniel Ernst ◽  
Tobias Kleindienst
Keyword(s):  
Wind Tunnel ◽  
Surface Pressure ◽  
Microphone Array ◽  
Pressure Fluctuations ◽  
Measurement Technology ◽  
Experimental Conditions ◽  
Flight Tests ◽  
Micro Electro Mechanical Systems ◽  
Mems Microphone ◽  
Mems Microphones

Preparing and pre-testing experimental setups for flight tests is a lengthy but necessary task. One part of this preparation is comparing newly available measurement technology with proven setups. In our case, we wanted to compare acoustic Micro-Electro-Mechanical Systems (MEMS) to large and proven surface-mounted condenser microphones. The task started with the comparison of spectra in low-speed wind tunnel environments. After successful completion, the challenge was increased to similar comparisons in a transonic wind tunnel. The final goal of performing in-flight measurements on the outside fuselage of a twin-engine turboprop aircraft was eventually achieved using a slim array of 45 MEMS microphones with additional large microphones installed on the same carrier to drawn on for comparison. Finally, the array arrangement of MEMS microphones allowed for a complex study of fuselage surface pressure fluctuations in the wavenumber domain. The study indicates that MEMS microphones are an inexpensive alternative to conventional microphones with increased potential for spatially high-resolved measurements even at challenging experimental conditions during flight tests.

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