Mean Amplitude Values Research Articles

Sensitivity of shear-driven internal condensing flows to pressure fluctuations and its utilization for heat flux enhancements

The reported experimental results are for annular zones of fully condensing flows of pure FC-72 (perfluorohexane) vapor. The flow condenses on the bottom surface (316 stainless steel) of a horizontal, rectangular cross-section duct. The sides and top of the duct are made of clear plastic. The annular portion of the flow in the test-section is driven, under negligible to zero gravity effects along the flow direction, by pressure-difference and cooling conditions. Since the annular regime condensate motion is primarily driven by an effective interfacial shear stress, all such flows are termed shear-driven flows. The experimental system in which this condenser is used is able to control quasi-steady (termed quasi-steady) values of inlet mass flow rate, inlet (or exit) pressure, and wall cooling conditions. For the experimental results reported here, the mean (time-averaged) inlet mass flow rate, mean inlet pressure, and condensing-surface cooling conditions were held fixed at their quasi-steady values. Under these conditions, it was found that the imposition of small inlet pressure fluctuations (relative to the mean inlet pressure) induces significant mass flow rate fluctuations at the condenser inlet, and that there is a change in the very nature of the quasi-steady annular condensing flow regime. The resulting phenomena change the mean local heat flux values with significant (>200%) enhancements. There are accompanying time-varying changes in the liquid–vapor configurations within the annular and the non-annular regimes. This changes the mean and fluctuation amplitude values (with induced harmonics) in the pressure at any interior location within the annular regime. It is shown here that the heat flux enhancement phenomenon is real and occurs regardless of the method of cooling for a suitable range of fluctuation frequencies and amplitudes. This paper experimentally investigates how the strength of this sensitivity varies with amplitude and frequency of pressure or mass flow rate fluctuations imposed at the inlet of the condenser. Associated theory and rudimentary experiments (not reported here) suggest that similar enhancement may be observed in annular flows which do not completely condense before the exit, provided that suitable arrangements at the condenser exit allow similar or equivalent liquid–vapor interfacial wave structures with the help of similar acoustic wave reflections in the vapor phase.

Semantic priming in children: an event-related potential (ERP) study

Event-related potential (ERP) analysis associated with semantic priming is traditionally based on the comparison between experimental conditions of the mean amplitude values, which are within the range of the N400 component latency. In this study, we used a complete ERP dataset to examine whether middle- and long-latency components are modulated by semantic priming in school-age children. ERPs were recorded while normal children read pairs of words and decided whether the second word of the pair belonged to the same semantic category as the first word. We used nonparametric multivariate permutation analysis to compare whole ERP amplitude values between related and unrelated word pairs. We also obtained ERPs from a sample of children with poor reading skills (reading disabled children) to evaluate the effect of semantic priming in a population with known information retrieval failures. We found larger P200 amplitudes for responses to related word pairs compared to unrelated word pairs and larger N400 amplitudes for responses to unrelated word pairs compared to related word pairs in normal children. In contrast, children with reading disabilities did not exhibit any significant differences regarding either of these components. Thus, changes in the topographical distribution of ERP components over time might reflect the activation of several brain structures. These results suggest that semantic priming is a process that is not only associated with the N400 component.

Semantic priming in children: an event-related potential (ERP) study

Event-related potential (ERP) analysis associated with semantic priming is traditionally based on the comparison between experimental conditions of the mean amplitude values, which are within the range of the N400 component latency. In this study, we used a complete ERP dataset to examine whether middle- and long-latency components are modulated by semantic priming in school-age children. ERPs were recorded while normal children read pairs of words and decided whether the second word of the pair belonged to the same semantic category as the first word. We used nonparametric multivariate permutation analysis to compare whole ERP amplitude values between related and unrelated word pairs. We also obtained ERPs from a sample of children with poor reading skills (reading disabled children) to evaluate the effect of semantic priming in a population with known information retrieval failures. We found larger P200 amplitudes for responses to related word pairs compared to unrelated word pairs and larger N400 amplitudes for responses to unrelated word pairs compared to related word pairs in normal children. In contrast, children with reading disabilities did not exhibit any significant differences regarding either of these components. Thus, changes in the topographical distribution of ERP components over time might reflect the activation of several brain structures. These results suggest that semantic priming is a process that is not only associated with the N400 component.

Vestibular evoked myogenic potentials in children with sensorineural hearing loss

Objective of the studyTo assess the saccular function using the vestibular evoked myogenic potential (VEMP) test in children with severe to profound sensorineural hearing loss. Methods15 children (12 males and 3 females) with severe to profound sensorineural hearing loss in the age range of 4–12 years constituted the study group. 10 children (6 males and 4 females) with normal hearing constituted the control group. All the children were evaluated for saccular function by using the vestibular evoked myogenic potentials (VEMP). ResultsFor study group the mean P1 and N1 latencies values were 15.12ms and 23.86ms, respectively. For control group the mean P1 and N1 latencies were 15.39ms and 23.68ms. The comparison of mean P1 and N1 latencies values between study and control groups revealed no significant difference (p>0.05). Furthermore, the mean amplitude values of VEMP responses for study and control groups were 75.78μV and 160.51μV, respectively. The comparison mean amplitude values between study and control groups revealed statistically significant difference (p<0.05). Out of 15 children in the study group 2 children had the absent VEMP response in both the ears. ConclusionBecause the vestibular function plays an important role in gross motor development in children, audiologists and otologist should recognize and understand the vestibular dysfunction in hearing impaired children and be prepared to undertake appropriate evaluations.However, additional research is needed on a larger sample size to determine the value of routine vestibular evaluation in children with sensorineural hearing loss and its potential benefit on the clinical outcome of these patients along with VEMP testing.

Acute effects of Achilles tendon vibration on soleus and tibialis anterior spinal and cortical excitability

Prolonged vibration is known to alter muscle performance. Attenuation of Ia afferent efficacy is the main mechanism suggested. However, changes in motor cortex excitability could also be hypothesized. The purpose of the present study was therefore to analyze the acute and outlasting effects of 1 h of Achilles tendon vibration (frequency, 50 Hz) on the soleus (SOL) and tibialis anterior (TA) neuromuscular excitability. Spinal excitability was investigated by means of H-reflexes and F-waves while cortical excitability was characterized by motor evoked potentials (MEPs) obtained by transcranial magnetic stimulation. Twelve subjects performed the experimental procedures 3 times: at the beginning of the testing session (PRE), immediately after 1 h of Achilles tendon vibration (POST), and 1 h after the end of vibration (POST-1H). Prolonged vibration led to acute reduced H-reflex amplitudes for SOL only (46.9% ± 7.7% vs. 32.8% ± 7%; p = 0.006). Mainly presynaptic inhibition mechanisms were thought to be involved because of unchanged F-wave persistence and amplitude mean values, suggesting unaffected motoneuronal excitability. While no acute effects were reported for SOL and TA cortical excitability, both muscles were characterized by an outlasting increase in their MEP amplitude (0.64 ± 0.2 mV vs. 0.43 ± 0.18 mV and 2.17 ± 0.56 mV vs. 1.26 ± 0.36 mV, respectively; p < 0.05). The high modulation of Ia afferent input by vibration led to changes in motor cortex excitability that could contribute to the enhancement in muscular activation capacities reported after chronic use of tendon vibration.

Vestibular evoked myogenic potentials in children affected by myelomeningocele

The aim of the present study is to establish if the vestibular evoked myogenic potentials (VEMPs) could be used as a clinical test for the evaluation of vestibular function in children affected by myelomeningocele (MMC). Fifteen children, aged between 3 and 17 years, who had been affected by MMC were investigated. Data obtained from these children were compared with normal data from healthy children of the same age. Electromyographic activity of sternocleidomastoid muscle was recorded, while children were laid supine and asked to raise their head off the bed in order to activate their neck flexors bilaterally. The saccular receptors were acoustically stimulated with a logon of 500 Hz at an intensity of 130 dB peSPL presented monaurally through earphones. In each recording, we analyzed latencies and amplitudes of the p13-and n23 waves and the amplitude ratio between the two ears. VEMPs were detected to be normal in 13 patients. In particular, the mean p13 and mean n23 latencies were 15.7 (±1.4) and 21.7 (±1.1) ms, respectively; the mean amplitude value was 84.7 (±36.6), while the mean amplitude ratio was 17.4 (±12). A comparison of latencies and amplitude ratios between the children and healthy control group did not reveal any significant difference. On the contrary, a comparison of amplitude values between the two groups showed significant differences. In conclusion, vestibulocollic reflex is normal in patients affected by MMC, and VEMPs could represent a valid and noninvasive technique eligible to investigate the vestibular functions in these children.

Maximum-entropy closure for a Galerkin model of an incompressible periodic wake

AbstractA statistical closure is proposed for a Galerkin model of an incompressible periodic cylinder wake. This closure employs Jaynes’ maximum entropy principle to infer the probability distribution for mode amplitudes using exact statistical balance equations as side constraints. The analysis predicts mean amplitude values and modal energy levels in good agreement with direct Navier–Stokes simulation. In addition, it provides an analytical equation for the modal energy distribution.

Biomechanical events of swallowing are determined more by bolus consistency than by age or gender

The biomechanics of swallowing saliva and substances of different consistencies were investigated in healthy children and adults. To this end, the duration and mean amplitude value (MAV) of surface electromyography (sEMG) of the submental muscle group (SMG) activity, the maximum anterior tongue pressure (ATP), and the rise and release slopes of ATP were measured while participants (39 female and 39 male participants, age 5–65years) swallowed saliva, 5mL water (reference), 5mL thick liquid, and 5mL solid food. Mean outcome parameters varied with the consistency of the liquid or food swallowed, with the exception of the rise slope of ATP. Moreover, outcome variables were not substantially affected by age with children of 5years and older showing similar biomechanical events to those of adults. It is important to gain insight into the biomechanics of swallowing saliva and substances of different consistencies in order to understand the underlying mechanisms of dysphagia children and adults.

Relationship between decreased swimming velocity and muscle activity during 200-m front crawl

The aims of this study were (1) to evaluate changes in muscle activity associated with physiological fatigue and decreased swimming velocity (SV) during 200 m of front crawl swimming, and (2) to examine the relationship between the decreased SV and changes in kinematic or electromyogram parameters. Twenty swimmers participated in a 4 × 50-m swim test. The surface EMG of 11 muscles (7 in the upper limbs and 4 in the lower limbs) was measured and the mean amplitude value (MAV) for one stroke cycle was obtained. The SV and arm angular velocity (AAV) of shoulder flexion during the first (early stroke) and second (late stroke) half of the underwater arm stroke were analyzed using an underwater camera. The AAV, the MAV of flexor carpi ulnaris (FCU), biceps brachii (BB), and triceps brachii during the early stroke, and the MAV of rectus femoris decreased along with a decrease in SV. In contrast, the MAV of the pectoralis major (PM) increased significantly in the final 50 m. The rate of change in MAVs (ΔMAVs) of FCU, BB and latissimus dorsi during the early stroke, and ΔMAV of biceps femoris were significantly correlated with ΔSV and/or ΔAAV. Positive correlations were identified between ΔMAVs of several muscles. However, no negative correlations were observed between ΔMAVs. These results suggest that the decrease in SV was related to decreases in the activities of several muscles that coordinated with each other, and that a compensating strategy occurred between PM and other muscles in the final 50 m.

Supervised versus Uncontrolled Rehabilitation of Patients after Rotator Cuff Repair-Clinical and Neurophysiological Comparative Study

The purpose of this study was the evaluation of the effectiveness of supervised rehabilitation in comparison to uncontrolled exercise therapy after surgical reconstruction of rotator cuff interrupted tendons. Twenty two patients with comparable level of disability after the same type of surgery were randomly divided into two equal groups. The first group took part in a supervised therapy and the second one performed simple exercises without supervision. Clinical and neurophysiological examinations were performed prior to rehabilitation and after 20 and 40 days of treatment. The evaluation included the assessment of the pain level with visual analog scale, active range of motion with gonio-meter, activity of muscle's motor units at rest and during maximal effort with electromyography and transmission of motor fibers in brachial plexus with electroneurography (M-wave stimulation studies). In the group of supervised patients the active range of movement changed significantly from 26.4º to 101.5º on average for flexion with adduction while flexion with abduction improved from 21º to 95.5º. Pain sensation changed from 6.4 to 3.2. The mean resting electromyogram amplitude decreased to the greatest degree from 80.9 µV to 36.8 µV in trapezius muscle while maximal effort electromyogram amplitude increased in this muscle from 381.8 µV to 790.9 µV. The mean values of amplitudes in electroneurographical suprascapular nerve examinations increased from 536.4µV to 1691µV. No significant differences at P=0.05 were found in these parameters recorded in the patients performing uncontrolled exercises. The supervised exercise therapy is more effective than uncontrolled one after the rotator cuff surgical reconstruction.

Electrophysiological differences in sensorineural hearing loss patients with and without problem-tinnitus

EnAbstract Objects Problem-tinnitus refers to tinnitus that is sufficiently severe to produce a major disruption in the patient’s life; tinnitus of such severity involves a number of regions of the auditory system and other brain systems may also play an essential role. Auditory brainstem responses (ABR) and event-related potentials (ERP) were recorded from sensorineural hearing loss (SNHL) patients with problem-tinnitus and were then compared with responses from normal hearing and hearing loss tinnitus-free patients. Aim To study whether differences exist in ABR and/or ERP parameters in SNHL patients with and without problem-tinnitus when matched as closely as possible for hearing loss, age, and sex to investigate the mechanism responsible for tinnitus. Materials and Methods Ninety participants were included in this study. They were divided into two groups: the study group included 66 participants with bilateral symmetrical SNHL that did not exceed a moderate degree. The study group was divided into two subgroups: 36 patients had problem-tinnitus and 30 patients were tinnitus-free (SNHL, age, and sex matched). Participants in each of these subgroups were compared with each other and were also compared with 24 healthy individuals in the control group (age and sex matched with the study group). All participants were subjected to a basic audiological evaluation and electrophysiological tests (ABR and ERP). Results This work had shown a higher prevalence of ABR abnormalities in tinnitus patients in comparison with either the control group or the SNHL tinnitus-free group. Statistically significant differences were found in III–V and I–V interpeak latencies and in the VI amplitude ratio in problem-tinnitus female patients compared with tinnitus-free female patients. Meanwhile, in problem tinnitus male patients when compared with tinnitus-free male patients at III–V interpeak latencies and at VI amplitude ratio. As regards the results of ERP in this work, an increase in latency and amplitude reduction were found. Statistically significant differences were observed regarding both the mean latency values of waves N1, P2, and P300 and the amplitude mean values of P2 and P300 when we compared the problem-tinnitus subgroup with either the tinnitus-free subgroup or the control group (both female and male patients. Conclusion A variety of ABR and ERP components are altered in tinnitus patients; this would indicate impairment in both the central auditory pathway and central auditory processing. Thus, it is suggested that this form of ABR, ERP testing could be considered as an objective measure to complement behavioral, audiologic, and other physiologic methods of assessing tinnitus, rather than a single definitive tinnitus measure in an attempt to supplement and thereby extend knowledge of the nature and origins of tinnitus. Furthermore, these results provide the basis for future neurofeedback-based tinnitus therapies aiming at maximizing the ability to shift attention away from the tinnitus.

Is EMG of the Lower Leg Dependent on Weekly Running Mileage?

Neuromuscular activity of the lower leg is dependent on the task performed, speed of movement and gender. Whether training volume influences neuromuscular activity is not known. The EMG of physically active persons differing in running mileage was analysed to investigate this. 55 volunteers were allocated to a low (LM: < 30 km), intermediate (IM: > 30 km & < 45 km) or high mileage (HM: > 45 km) group according to their weekly running volume. Neuromuscular activity of the lower leg was measured during running (3.33 m·s - 1). Mean amplitude values for preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle.Higher activity in the gastrocnemius group was observed in weight acceptance in LM compared to IM (+30%) and HM (+25%) but lower activity was present in the push-off for LM compared to IM and HM. For the peroneal muscle, differences were present in the push-off where HM showed increased activity compared to IM (+24%) and LM (+60%). The tibial muscle revealed slightly lower activity during preactivation for the high mileage runners. Neuromuscular activity differs during stance between the high and intermediate group compared to low mileage runners. Slight adaptations in neuromuscular activation indicate a more target-oriented activation strategy possibly due to repetitive training in runners with higher weekly mileage.

Frequency response of biospeckle laser images of bean seeds contaminated by fungi

Biospeckle laser (BSL) images of bean seeds artificially contaminated by Fusarium oxysporum or Aspergillus flavus have been analysed using inertia moment (IM) and frequency values of the spatial time speckle (STS) signals. BSL imaging was performed with a He-Ne red beam laser (632.8 nm; 10 mW) and a CCD camera (image size 780 x 480 pixels), and frequencies of the STS signals were derived using convolution and fast Fourier transform. Intensities of the IM values of contaminated seeds were significantly greater than those of disease-free control seeds. Furthermore, A. flavus -contaminated seeds presented IM values that were significantly higher than those of seeds contaminated by F. oxysporum . The mean amplitude values of the frequencies components of FFT analysis detected in F. oxysporum -contaminated seeds were higher than those of A. flavus -contaminated and control seeds. In contrast, when the third harmonic was analysed independently, the amplitude values of the frequencies detected in A. flavus -contaminated seeds were significantly lower than those of control seeds which, in turn, were similar to those of seeds contaminated with F. oxysporum. It is concluded that frequency analysis may be used to complement the information provided by IM values, thus strengthening the application of BSL in the study of biological materials. ► Biospeckle laser and fast Fourier transform analysis used to study fungi in seeds. ► Inertia moment for Aspergillus flavus -contaminated higher than F. Oxysporum and control seed. ► Third spatial time speckle harmonic for A. flavus lower than control. ► Frequency analysis complements biospeckle laser analysis.

V˙O2Kinetics in 200-m Race-Pace Front Crawl Swimming

Studies that aim to characterize oxygen uptake kinetics in efforts above maximal oxygen consumption intensity are scarce. Our aim was to analyze the oxygen kinetics in a maximal 200-m front crawl, all measurements being conducted in swimming pool conditions. 10 high-level male swimmers performed a maximal 200-m bout and oxygen uptake was directly measured through breath-by-breath gas analysis. Mean (±SD) peak oxygen uptake was 68.58 (±5.79) ml.kg(-1).min(-1), evidencing a fast component phase. As expected, peak oxygen uptake presented a direct relationship with mean swimming speed of the first 50-m lap and with the 200-m effort, and was also correlated with the amplitude of the fast component (r=0.75, r=0.72, r=0.73, p<0.05, respectively). The observed mean amplitude value was higher than those observed in the literature for other exercise intensity domains. However, the time for its onset, as well as the duration for attaining the steady state, was shorter, as the peak oxygen uptake was not correlated with these 2 components. Moreover, as previously described for swimming at high intensities, the slow component phenomenon was not observed. Aerobic metabolic pathway accounted for 78.6%, confirming the high aerobic contribution in middle distance swimming events.

Measurement of Two-Dimensional Movement Parameters of the Carotid Artery Wall for Early Detection of Arteriosclerosis: A Preliminary Clinical Study

The aim of this study was to clinically investigate the association between the risk factors of early-stage atherosclerosis and the two-dimensional (2-D) movement of the artery wall. To meet this objective, a speckle tracking approach for the estimation of the 2-D trajectory of the vessel wall was proposed and applied to B-mode ultrasound (US) sequences of the left common carotid artery (CCA). A deformable skeleton model was also introduced in the block matching scheme. Finally, the 2-D movements of both proximal and distal walls were investigated in three different local regions, with 1.5 × 0.3 mm 2 kernel blocks. A clinical study was conducted in which two different populations (26 young healthy volunteers and 26 older diabetic patients) were studied. The results show that the mean amplitude value of the diameter change Δ D , of the longitudinal displacement of the proximal wall Δ X p and of the longitudinal displacement of the distal wall Δ X d were 0.65 ± 0.17 vs. 0.41 ± 0.12 mm ( p < 0.001), 0.48 ± 0.21 vs. 0.26 ± 0.18 mm ( p < 0.001) and 0.48 ± 0.20 vs. 0.35 ± 0.23 mm ( p = 0.006) for the young healthy volunteers and the older diabetic patients, respectively. The results of the three dynamic parameters Δ D , Δ X p and Δ X d were systematically and significantly lower for the diabetic subjects, respectively 37%, 46% and 27%. The method introduced in this feasibility study might constitute a pertinent approach to assess the presence of early-stage arteriosclerosis by the noninvasive estimation of the 2-D motion of the intima-media complex in the CCA.

Comparison in lower leg neuromuscular activity between runners with unilateral mid-portion Achilles tendinopathy and healthy individuals

Neuromuscular control in functional situations and possible impairments due to Achilles tendinopathy are not well understood.Thirty controls (CO) and 30 runners with Achilles tendinopathy (AT) were tested on a treadmill at 3.33ms−1 (12kmh−1). Neuromuscular activity of the lower leg (tibialis anterior, peroneal, and gastrocnemius muscle) was measured by surface electromyography. Mean amplitude values (MAV) for the gait cycle phases preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle.MAVs of the tibialis anterior did not differ between CO and AT in any gait cycle phase. The activation of the peroneal muscle was lower in AT in weight acceptance (p=0.006), whereas no difference between CO and AT was found in preactivation (p=0.71) and push-off (p=0.83). Also, MAVs of the gastrocnemius muscle did not differ between AT and CO in preactivity (p=0.71) but were reduced in AT during weight acceptance (p=0.001) and push-off (p=0.04).Achilles tendinopathy does not seem to alter pre-programmed neural control but might induce mechanical deficits of the lower extremity during weight bearing (joint stability). This should be addressed in the therapy process of AT.

Padronização do potencial evocado auditivo de tronco encefálico utilizando um novo equipamento

Standardization of Brainstem Auditory Evoked Potential (BAEP) using a new device. To standardize BAEP responses using a new device developed (NDD) in Brazil. Analysis of absolute latencies, interpeaks and wave amplitudes of BAEP, using a new device developed to study normal-hearing groups (91 adults) and individuals (15 adults) with bilateral neurosensory hearing loss. Responses obtained in the EP15 hearing device/Interacoustics and the NDD were compared. For this, the following paramenters were used: non-filtered click of 100 microsecond (µs), totaling 2000 stimuli in rarefied polarity, stimulation frequency of 13.1 clicks/s, intensity of 80 decibels normalized hearing level (dB nHL), with a window of 10 milliseconds and bandpass filter between 100 and 3000 Hertz (Hz). Significance level was set at 0.05. Absolute latency and interpeak means for 76 normal-hearing individuals with the NDD were: wave I=1.50, III=3.57, V=5.53, I-III=2.06, III-V=1.96 and I-V=4.02. When analyzing results according to gender, there was a statistically significant difference for the absolute latencies of waves III and V and in interpeaks I-III and I-V. Mean amplitude value of wave I=0.384 microvolt (µV) and of wave V=0.825 µV. There was no statistically significant difference between the absolute latencies and interpeaks of the two devices in the same individual. The components of BAEP with the NDD in normal-hearing subjects were similar regarding the tested ears, with statistically lower latencies in women. The BAEP latencies in the same individual with NDD were similar to those obtained with the EP15 / Interacoustics. Normal values of BAEP were obtained in normal-hearing adults.

F-Wave Characteristics as Surrogate Markers of Spasticity in Patients With Secondary Progressive Multiple Sclerosis

We sought to identify significant ulnar nerve conduction abnormalities and also to detect ulnar F-wave variable changes in patients with secondary progressive multiple sclerosis (MS). Conventional conduction study was performed unilaterally to ulnar nerves of eight men and 12 women with secondary progressive MS (mean age, 47.5 +/- 6.6 years), having spastic hemiparesis and hand spasticity. A series of 40 electrical stimuli were also delivered to their ulnar nerves unilaterally so as to obtain F waves. The side of examination was ipsilateral to the side of spastic paresis. The following F-wave variables were estimated: F-wave persistence, latency, amplitude, duration, and F chronodispersion. Ten patients with remitting-relapsing MS without any evidence of hand spasticity and 20 age- and gender-matched healthy volunteers served as controls. Motor and sensory conduction study was normal in all participants. The F-wave persistence, latency, and duration parameters and also the F chronodispersion were comparable between groups. The mean and maximum F-wave amplitude values (P = 0.005) and the F mean/M (P = 0.001) and F maximal/M (P = 0.001) ratios were significantly higher than those of controls. Finally, the F-wave amplitude parameters in patients with secondary progressive MS significantly correlated with the degree of spasticity and the duration of disease. Significant amplitude F-wave abnormalities occurred in patients with secondary progressive MS and hand spasticity, emphasizing the contribution of upper motor neurons damage in the genesis of F waves.

Comparative analysis of audiometric and impedancemetric findings in workers exposed to the effects of various duration industrial noise

Industrial noise is produced in workshops due to factory machinery and tools used in technological processes. It has detrimental effect to primarily the organ of the sense of hearing, thus damaging hearing in oversensitive subjects. The aim of the study was to perform a detailed analysis of audiometric and, especially, impedancemetric parameters in workers exposed to the effects of industrial noise of various duration, as well as to determine similarities and differences in workers with differences in sensitivity to damaging effects of noise. The study included a homogenous group of 173 industrial workers involved in the same department of a huge workshop named "Kovacica" exposed to noise level above a threshold intensity, and divided into three groups: the group I of 116 workers (232 ears) exposed to noise for 8 h in the workshop "Kovacica", the group II of 41 workers (82 ears) exposed to noise only half of the working time, and the group III of 16 workers (32 ears) exposed to the same conditions and having the normal hearing sense. The group III served as a control group. Prior to the study any workers went through a thorough anamnesis and complete ORL examination, and then they were submitted to audiometric testing. The study included only the workers with no hearing damage due to diseases, injuries nor other detrimental factors in order to be sure that the hearing findings had been caused by industrial noise. The results obtained by audiometric testing showed that 90.75% of the workers had hearing damage of various degrees, while 9.25% of the workers had regular hearing although had been exposed to the same conditions. More severe hearing damage was revealed in the workers of the group I. Tympanometricly, in most ears of the group I workers (65.52%) a compliance value was found to be more than 0.9 cm3, while in the majority of those of the group II (59.75%) a compliance value was in the range from 0.5 to 0.9 cm3. In the workers of the group III with no hearing damage, a compliance value for any ears was in the range from 0.1 to 0.9 cm3. Mean value of threshold reflex (98.56 dB) at 500 Hz and 1 000 Hz in the group I was increased as compared with the group II (95.6 dB) and the group III (84.38 dB). At higher frequences, 2 000 and 4 000 Hz, threshold reflex was increased in the group I (99.05 dB), and in the group II (97.6 dB) as compared with the group III (86.4 dB). The amplitude of stapedic reflex was lowest in the group I, while mean values of amplitude at 500, 1 000, 2 000 and at 4 000 Hz were 2.31, 1.38, 1 and 0.3, respectively. In the group II mean values of amplitude at 500, 1 000, 2 000 and 4 000 Hz were 2.52, 1.80, 1.30 and 0.5, respectively. In the group III mean values of amplitude at 500, 1 000, 2 000 and at 4 000 Hz were 2.36, 2.45, 2.5 and 2.08, respectively. By measuring input (rising) and output angles it was revealed that most ears of the workers in the groups I and II had rising angle ranging from 41 to 50 degrees, and in the workers with no hearing loss from 31 to 50 degrees. In the majority of the ears of the groups I and II outlet angle was in the range from 16 to 35 degrees, and in the workers with no hearing damage from 26 to 35 degrees. By audiometric and impedancemetric examinations it was determined that for the sense of hearing it is significant not only a threshold hearing expressed in the audiometric curve at various frequences, but also a threshold of unpleasantness and pain under higher intensities shown by the occurrence of stapedic reflex. The less hearing field between threshold hearing and threshold acustic reflex is, the less capabilities of hearing perception due to the occurrence of recrutment.

骨格性下顎前突症患者における嚥下時筋活動様式の特徴

The present study investigated the pattern of muscle activity during swallowing in patients with mandibular prognathism.The subjects comprised 12 mandibular prognathism patients (5 males, 7 females, average age of 20.8 years old), and 12 volunteers (2 males, 10 females, average age of 23.8 years old) with individual normal occlusion and no abnormalities of deglutition function as a control.Electromyographic (EMG) activity was recorded from the masseter and suprahyoid muscles bilaterally, mentalis on the midline and orbicularis oris and infrahyoid muscles on the right side.Each subject was asked to perform the following: (1) maximum clenching for 5 seconds at 10-second intervals, (2) maximum jaw opening for 5 seconds at 10-second intervals, and (3) swallow 4 ml of half-solid nutrient made of 0.8% agar powder. The first two tasks were repeated four times and the last one was repeated five times.Peak amplitudes of masseter and suprahyoid EMGs during maximum clenching and jaw opening were first obtained. For analysis of swallowing, mean values of duration of EMG, mean values of amplitude, and root mean square (RMS) of EMGs of orbicularis oris, mentalis and infrahyoid muscles, and those of %peak (swallow activity/peak activity) amplitude of masseter and suprahyoid EMGs were calculated and compared between the patient group and the normal group. Morphological characteristics of the patients were also compared between the groups using lateral cephalograms.The duration of activity in all muscles recorded except the infrahyoid was significantly longer in the patient group than in the control. Peak amplitude and RMS of mentalis muscles were significantly larger in the control than in the patient group. %peak amplitude of masseter and suprahyoid muscles were both significantly larger in the patient group than in the control. On the contrary, there were no significant differences in all the variables of infrahyoid muscles.The present study successfully showed the pattern of orofacial muscle activity in patients with mandibular prognathism in terms of peak amplitude and duration. Although the activities of orofacial muscles recorded in this study are reflexively controlled at the lower brainstem during swallowing, these are also known to be voluntary muscles and therefore they are likely to adapt the activity patterns to their morphologic characteristics.