WorldWideScience

Sample records for click-evoked otoacoustic emissions

  1. Temporal suppression and augmentation of click-evoked otoacoustic emissions

    DEFF Research Database (Denmark)

    Verhulst, Sarah; Harte, James; Dau, Torsten

    2008-01-01

    This study investigates and models temporal suppression of click-evoked otoacoustic emissions (CEOAEs). This suppression-effect is created when a suppressor-click is presented close in time to a test-click. The analysis was carried out for short time-frames of short- and long-latency CEOAEs. The...... latter is defined as a CEOAE with duration greater than 20 ms, typically observed for test subjects with spontaneous otoacoustic emissions (SOAEs). Previous studies have tended to exclude these test subjects but they are incorporated here. The results from six exemplary subjects demonstrate that temporal...... temporal suppression and augmentation of CEOAEs. Recently, a feedback automatic gain control (AGC) system has been used to model CEOAE suppression. However, this system cannot account for augmentation and therefore another, dynamic nonlinear model was developed. Suppression and augmentation were modeled...

  2. Temporal suppression of long-latency click-evoked otoacoustic emissions

    DEFF Research Database (Denmark)

    Verhulst, Sarah; Harte, James; Dau, Torsten

    2007-01-01

    A comprehensive set of results from double click suppression experiments on otoacoustic emissions (OAEs) have been presented by Hine and Thornton (2002) and Kapadia and Lutman (2000). They found that suppression of a click-evoked otoacoustic emission (CEOAE) varied with the timing and level...

  3. Click-evoked otoacoustic emissions in children and adolescents with gender identity disorder

    NARCIS (Netherlands)

    Burke, Sarah M; Menks, Willeke M; Cohen-Kettenis, Peggy T; Klink, Daniel T; Bakker, J.

    2014-01-01

    Click-evoked otoacoustic emissions (CEOAEs) are echo-like sounds that are produced by the inner ear in response to click-stimuli. CEOAEs generally have a higher amplitude in women compared to men and neonates already show a similar sex difference in CEOAEs. Weaker responses in males are proposed to

  4. Effect of age on click-evoked otoacoustic emission A systematic review

    Institute of Scientific and Technical Information of China (English)

    Jinfeng Liu; Ningyu Wang

    2012-01-01

    OBJECTIVE: The aims of this study were to investigate the changes of the total intensity of transient evoked otoacoustic emission (TEOAE) and signal-to-noise ratio in various frequency bands as a function of aging, and to explore the role of age-related decline of cochlear outer hair cells.DATA SELECTION: Inclusion criteria: (1) Articles should involve the total TEOAE level or sig-nal-to-noise ratio. (2) The measurement and analysis system used was Otodynamics ILO analysis system (ILO88, ILO92, ILO96 or ILO292). (3) Studies involved groups of greater than 10 subjects and TEOAE results were from normally hearing ears. (4) If more papers from the same author or laboratory analyzed the same subjects, only one was used. MAIN OUTCOME MEASURES: The correlations of the age scale with the total level and sig-nal-to-noise ratio of TEOAE was determined, respectively.RESULTS: (1) TEOAE total level gradually increased until 2 months of age, and then decreased with increasing age. Significant negative correlations between total TEOAE level and age were found (r = -0.885, P = 0.000). (2) The most rapid decrease of TEOAE amplitude occurred at 1 year old. The total TEOAE level decreased about 4.25 dB SPL between 2 months to 1 year old, then about 0.26-0.52 dB SPL from 1 year to 10 years old, about 0.23 dB SPL from 11 years to 25 years old, and about 0.14 dB SPL from 26 years to 60 years old. (3) The signal-to-noise ratio in the fre-quency bands centered at 1.5, 2, 3 and 4 kHz decreased with increasing age after 2 months of age. Significant negative correlations between the signal-to-noise ratio and age were found for frequency bands ranging from 1.5 kHz to 4 kHz, with the highest correlations at 4 kHz (r = -0.890, P < 0.01), then at 3 kHz (r = -0.889, P < 0.01), at 2 kHz (r = -0.850, P < 0.01) and at 1.5 kHz (r = -0.705, P < 0.05). Conversely, a positive correlation between the signal-to-noise ratio centered at 1 kHz and age was found, but was not statistically significant (r = 0

  5. Noise-evoked otoacoustic emissions in humans

    NARCIS (Netherlands)

    Maat, B; Wit, HP; van Dijk, P

    2000-01-01

    Click-evoked otoacoustic emissions (CEOAEs) and acoustical responses evoked by bandlimited Gaussian noise (noise-evoked otoacoustic emissions; NEOAEs) were measured in three normal-hearing subjects. For the NEOAEs the first- and second-order Wiener kernel and polynomial correlation functions up to t

  6. Wiener kernel analysis of a noise-evoked otoacoustic emission

    NARCIS (Netherlands)

    van Dijk, P; Maat, A; Wit, H P

    1997-01-01

    In one specimen of the frog species, Rana esculenta, the following were measured: (1) a spontaneous otoacoustic emission; (2) a click-evoked otoacoustic emissions; and (3) a noise evoked otoacoustic emission. From the noise evoked emission response, a first-and a second-order Wiener kernel and the f

  7. Otoacoustic emissions in preterm infants : Indications for cochlear development?

    NARCIS (Netherlands)

    Brienesse, P; Anteunis, L; Wit, H; Gavilanes, D; Maertzdorf, W

    1996-01-01

    A longitudinal study of click-evoked otoacoustic emissions (CEOAEs) in 19 ears of 11 preterm infants-post-conceptional age (PCA): 30 to 39 weeks-resulted in a total of 90 CEOAE recordings. All but one of the 19 ears showed an increase of CEOAE amplitude at increasing PCA. The mean increase rate was

  8. Investigating the periodicity of transient-evoked otoacoustic emission envelopes

    DEFF Research Database (Denmark)

    Verhulst, Sarah

    2011-01-01

    This study investigates the cochlear origin of the multiple temporal lobes that are often observed in the transient-evoked otoacoustic emission (TEOAE) envelope. This "waxing and waning" of the OAE amplitude can be observed in tone-burst (TB) OAEs and sometimes also in click-evoked (CE) OAEs. TBOAE...... and the middle-ear boundary may contribute to the TBOAE envelope periodicity, but were not the main modulation component in waxing and waning of the investigated TBOAEs....

  9. Can a static nonlinearity account for the dynamics of otoacoustic emission suppression?

    DEFF Research Database (Denmark)

    Verhulst, Sarah; Shera, Christopher A.; Harte, James;

    2011-01-01

    This study investigates whether time-dependent compression mechanisms in the cochlea are necessary to explain dynamic properties of otoacoustic emissions (OAEs). Dynamic properties of click-evoked OAEs (CEOAEs) have been observed in temporal suppression; the effect where the CEOAE magnitude......-invariant nonlinearity, was able to simulate temporal suppression, but was unable to account for the exact time scale and magnitude of the effect. The results suggest that temporal overlap of BMimpulse responses can account for suppression in CEOAEs, but that an additional time-dependent cochlear gain mechanism may...

  10. Backward Propagation of Otoacoustic Emissions

    Institute of Scientific and Technical Information of China (English)

    HE Wenxuan; REN Tianying

    2006-01-01

    Normal mammalian ears not only detect but also generate sounds. The ear-generated sounds, I.e., otoacoustic emissions (OAEs), can be measured in the external ear canal using a tiny sensitive microphone. In spite of wide applications of OAEs in diagnosis of hearing disorders and in studies of cochlear functions, the question of how the cochlea emits sounds remains unclear. The current dominating theory is that the OAE reaches the cochlear base through a backward traveling wave. However, recently published works, including experimental data on the spatial pattern ofbasilar membrane vibrations at the emission frequency, demonstrated only forward traveling waves and no signs of backward traveling waves. These new findings indicate that the cochlea emits sounds through cochlear fluids as compression waves rather than through the basilar membrane as backward traveling waves. This article reviews different mechanisms of the backward propagation of OAEs and summarizes recent experimental results.

  11. Exploiting dual otoacoustic emission sources

    Science.gov (United States)

    Abdala, Carolina; Kalluri, Radha

    2015-12-01

    Two distinct processes generate otoacoustic emissions (OAEs). Reflection-source emissions, here recorded as stimulus frequency OAEs, are optimally informative at low sound levels and are more sensitive to slight hearing loss; they have been linked to cochlear amplifier gain and tuning. Distortion-source emissions are strongest at moderate-high sound levels and persist despite mild hearing loss; they likely originate in the nonlinear process of hair cell transduction. In this preliminary study, we exploit the unique features of each by generating a combined reflection-distortion OAE profile in normal hearing and hearing-impaired ears. Distortion-product (DP) and stimulus-frequency (SF) OAEs were recorded over a broad range of stimulus levels and frequencies. Individual I/O and transfer functions were generated for both emission types in each ear, and OAE peak strength, compression threshold, and rate of compression were calculated. These combined SFOAE and DPOAE features in normal and hearing-impaired ears may provide a potentially informative and novel index of hearing loss. This is an initial step toward utilizing OAE source in characterizing cochlear function and dysfunction.

  12. Dynamics of spontaneous otoacoustic emissions

    Science.gov (United States)

    Bergevin, Christopher; Salerno, Anthony

    2015-12-01

    Spontaneous otoacoustic emissions (SOAEs) have become a hallmark feature in modern theories of an `active' inner ear, given their numerous correlations to auditory function (e.g., threshold microstructure, neurophysiological tuning curves), near universality across tetrapod classes, and physiological correlates at the single hair cell level. However, while several different classes of nonlinear models exist that describe the mechanisms underlying SOAE generation (e.g., coupled limit-cycle oscillators, global standing waves), there is still disagreement as to precisely which biophysical concepts are at work. Such is further compounded by the idiosyncratic nature of SOAEs: Not all ears emit, and when present, SOAE activity can occur at seemingly arbitrary frequencies (though always within the most sensitive range of the audiogram) and in several forms (e.g., peaks, broad `baseline' plateaus). The goal of the present study was to develop new signal processing and stimulation techniques that would allow for novel features of SOAE activity to be revealed. To this end, we analyzed data from a variety of different species: human, lizard, and owl. First, we explored several strategies for examining SOAE waveforms in the absence of external stimuli to further ascertain what constitutes `self-sustained sinusoids' versus `filtered noise'. We found that seemingly similar peaks in the spectral domain could exhibit key differences in the time domain, which we interpret as providing critical information about the underlying oscillators and their coupling. Second, we introduced dynamic stimuli (swept-tones, tone bursts) at a range of levels, whose interaction with SOAEs could be visualized in the time-frequency domain. Aside from offering a readily accessible way to visualize many previously reported effects (e.g., entrainment, facilitation), we observed several new features such as subharmonic distortion generation and competing pulling/pushing effects when multiple tones were

  13. Can components in distortion-product otoacoustic emissions be separated?

    DEFF Research Database (Denmark)

    Christensen, Anders Tornvig; W. Purcell, David; Christensen, Flemming;

    2012-01-01

    to improve hearing sensitivity by means of nonlinear amplification, which produces distortion. In the measurement of otoacoustic emissions, two tones can be delivered to the cochlea to invoke this nonlinearity and elicit the distortion-product otoacoustic emission (DPOAE). DPOAEs arise mainly from two...

  14. Otoacoustic emissions measured in children diagnosed with attention-deficit/hyperactivity disorder

    Science.gov (United States)

    McFadden, Dennis; Westhafer, J. Gregory; Pasanen, Edward G.; Tucker, David M.; Carlson, Caryn L.

    2003-10-01

    Attention-deficit/hyperactivity disorder (ADHD) is generally acknowledged to be more prevalent in males than in females. Further, some precursors to ADHD appear early in life. Together these facts suggest that ADHD may be influenced by androgenic mechanisms operating early in development. This reasoning raises the question of whether the otoacoustic emissions (OAEs) of children with ADHD are masculinized. Click-evoked OAEs were measured for one click level in 8 boys and 3 girls diagnosed as ADHD/Combined, in 11 males and 5 females diagnosed as ADHD/Inattentive (IA), and in 17 male and 18 female controls. The ages of these samples ranged between 7 and 15. As in adults, the CEOAEs of the control males were weaker than those of the control females. Further, the CEOAEs of the ADHD/IA males were weaker than in the control males (a hypermasculinization) and the CEOAEs of the IA females were weaker than in the female controls (a masculinization). The CEOAEs of the Combined groups were slightly stronger (feminized) than those of the control males and females. One interpretation is that the IA subgroup of ADHD boys and girls (but not the Combined subgroup) was exposed to higher-than-normal levels of androgens sometime early in development. [Work supported by NIDCD.

  15. Multi-variant analysis of otoacoustic emissions and estimation of hearing thresholds: transient evoked otoacoustic emissions.

    Science.gov (United States)

    Vinck, B M; Van Cauwenberge, P B; Corthals, P; De Vel, E

    1998-01-01

    Evaluation of cochlear hearing loss by means of transiently evoked otoacoustic emissions is already established in clinical practice. However, accurate prediction of pure-tone thresholds is still questioned and is still regarded as troublesome. Both click- and tone-burst-evoked otoacoustic emissions at several intensity levels were measured and analysed in 157 ears from normally hearing and 432 ears from patients with different degrees of pure sensory hearing loss using the ILO88/92 equipment. Results of otoacoustic emissions (OAE), elicited by clicks and tone-bursts at centre frequencies from 1 to 5 kHz, were analysed using two different statistical methods. Both multivariate discriminant analysis and forward multiple regression analysis were used to determine which OAE variables were most discriminating and best at predicting hearing thresholds. We found that a limited set of variables obtained from both tone-burst and click measurements can accurately predict and categorize hearing loss levels up to a limit of 60 dB HL. We found correct classification scores of pure-tone thresholds between 500 and 4000 Hz up to 100 per cent when using combined click and tone-burst otoacoustic measurements. Prediction of pure-tone thresholds was correct with a maximum estimation error of 10 dB for audiometric octave frequencies between 500 and 4000 Hz. Measurements of multiple tone-bursts OAEs have a significant clinical advantage over the use of clicks alone for clinical applications, and a good classification and prediction of pure-tone thresholds with otoacoustic emissions is possible.

  16. Spontaneous Otoacoustic Emissions in Tinnitus Patients

    Institute of Scientific and Technical Information of China (English)

    SHI Yongbing; William Martin

    2006-01-01

    Otoacoustic emissions (OAEs) are believed to be the products of active cochlear mechanics. They are generally associated with relatively intact outer hair cell function. OAEs usually decrease or become undetectable when hearing loss of cochlear origin exceeds 40-50 dB HL. Subjective tinnitus is a perception of sound without detectable corresponding source. It is most often seen in patients with hearing loss. It is also frequently seen in patients with head injuries. Studies have suggested that the prevalence of spontaneous otoacoustic emissions(SOAEs) is lower in patients with hearing loss and tinnitus than in normal population. There have also been reports on association between tinnitus and SOAEs of unusually high amplitudes, which can be controlled by aspirin administration. The current paper is a preliminary review of clinical data collected from a group oftinnitus patients in an attempt to elucidate on the relationship between SOAEs and tinnitus from a clinical point of view. Audiometric, tinnitus and SOAE data from 59 patients seen at the Oregon Health & Science University Tinnitus Clinic were retrospectively studied. Fifty-four of these 59 patients showed sensorineural hearing loss of various degrees at the time of evaluation, mostly affecting high frequencies. SOAEs were detected in 26 ears (22%) of 1 8 patients(30.5%). There was no difference in SOAE prevalence between male and female patients. SOAEs were recorded in four of the five patients whose pure tone thresholds were within normal limits up to 8000 Hz. SOAEs appeared to be recorded at a higher rate in patients whose tinnitus started following motor vehicle accidents or head injuries(5/10) than in other patients.Time course of tinnitus did not appear to affect SOAE detection rate. There were no correlations between SOAE frequency and matched tinnitus pitch or frequency of maximum hearing loss. Significance of these findings is discussed.

  17. Evoked otoacoustic emissions in patients with Meniere's disease

    NARCIS (Netherlands)

    de Kleine, E; Mateijsen, DJM; Wit, HP; Albers, FWJ

    2002-01-01

    Hypothesis: This study investigated whether otoacoustic emissions (OAEs) in patients with Meniere's disease show abnormal properties. Background: Patients with Meniere's disease experience vertigo. tinnitus, and hearing loss. OAEs are sounds generated in the inner ear. and their presence is associat

  18. Evoked otoacoustic emissions in workers exposed to noise: A review

    Directory of Open Access Journals (Sweden)

    Alcarás, Patrícia Arruda de Souza

    2012-01-01

    Full Text Available Introduction: The otoacoustic emissions test is an essential tool in the evaluation of auditory function, since it allows the early detection of cochlear damage of occupational origin. Objective: To present a review of the literature and analyze the effectiveness of the clinical application of the otoacoustic emissions test in workers exposed to noise. Methods: A bibliographical search covering a period of 10 years was performed in the Virtual Health Library including published articles in national and international journals indexed in the internationally recognized databases for the health sciences, LILACS, SCIELO, and MEDLINE, using the terms "otoacoustic emissions" and "occupational exposure." The type of published article (national/international, the type and intensity of the stimulus most commonly used for the evoked otoacoustic emissions, the gender and age of the subjects, and the conclusions from the retrospective studies were all taken into consideration. Results and Conclusions: A total of 19 articles were analyzed, 7 national and 12 international, covering subjects from 17 to 77 years of age, mostly men. The type of stimulus most commonly used for the evoked otoacoustic emissions was the distortion method (12. Through this review, we have concluded that testing of evoked otoacoustic emissions in workers exposed to noise is an important tool in the early diagnosis of noise-induced cochlear hearing disorders.

  19. Distortion product otoacoustic emissions in geriatric dogs.

    Science.gov (United States)

    Strain, G M; Rosado Martinez, A J; McGee, K A; McMillan, C L

    2016-10-01

    Recordings of distortion product otoacoustic emissions (DPOAE) were taken from 28 geriatric dogs aged 12.2 ± 2.2 years and 15 control dogs aged 5.9 ± 3.0 years (mean ± standard deviation) to demonstrate frequency-specific changes in cochlear responses. Recordings were performed for primary frequencies of 2-12 kHz in 2 kHz increments. Brainstem auditory evoked response (BAER) recordings were also made from geriatric dogs for comparison with DPOAE responses. Significant decreases in DPOAE response amplitudes were observed at frequencies of 6-12 kHz in geriatric dogs compared to control dogs, reflecting loss of cochlear outer hair cells along the length of the cochlea. Significant decreases in response amplitudes were not seen at frequencies of 2 or 4 kHz. Decreases in BAER response amplitudes subjectively paralleled the depressed DPOAE amplitudes. No significant linear regression relationships were found for DPOAE response amplitude vs. age despite the progressive nature of age-related hearing loss. The reductions in response at all frequencies starting at the age where dogs are considered geriatric indicate that age-related hearing loss begins earlier in the life span. DPOAE recordings provide a means to assess cochlear function across different portions of the auditory spectrum for assessing hearing loss associated with aging, and potentially for losses from other causes of decreased auditory function. PMID:27687934

  20. Distortion product otoacoustic emission fine structure of symphony orchestra musicians

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    Otoacoustic emissions (OAE) are sounds produced by the healthy inner ear. They can be measured as low-level signals in the ear canal and are used to monitor the functioning of outer hair cells.Several studies indicate that OAE might be a more sensitive measure to detect early noise-induced hearing...... losses than puretone audiometry. The distortion product otoacoustic emission (DPOAE) fine structure is obtained when the ear is stimulated by dual tone stimuli using a high frequency resolution. It is characterized by quasi-periodic variations across frequency, as it can be observed in the hearing...

  1. Distortion product otoacoustic emission fine structure of symphony orchestra musicians

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2006-01-01

    Otoacoustic emissions (OAE) are sounds produced by the healthy inner ear. They can be measured as low-level signals in the ear canal and are used to monitor the functioning of outer hair cells. Many studies indicate that OAE might be a more sensitive measure to detect early noise-induced haring...... losses than pure-tone audiometry. The distortion product otoacoustic emission (DPOAE) fine structure is obtained when the ear is stiumulated by dual tone stimuli using a high frequency resolution. It is characterized by quasi-periodic variations across frequency, as it can be observed in the hearing...

  2. [Mass screening of deafness in neonates using otoacoustic emissions].

    Science.gov (United States)

    François, M

    There is no clinical sign of hearing loss in the infant. Defective language acquisition and altered voice quality always occur late making early diagnosis essential for therapeutic management of deaf children. Subjective assessment of behavioral is highly dependent on the experience of the examinator and cannot be used as an effective routine method. Electrophysiological recordings of otoacoustic emissions have the advantage of allowing objective measurement. Otoacoustic emissions originate in the inner ear. A quantity of energy is transmitted via the tympanic membrane which acts as a microphone, allowing recordings in the external auditory canal. In certain infants these emissions are spontaneous and can be used to detect certain types of hearing loss. Stimulation is required however for screening tests. Recording provoked otoacoustic emissions is simple. A small probe in placed in the external auditory canal. This probe carries two microphones, one which emits clicks recorded by the other captor microphone. The examination lasts approximately 15 minutes, including the time needed to explain the procedure to the mother. There are two possible results. The presence of recorded otoacoustic emissions confirms that the inner ear is normal. If the absence of emissions is confirmed at a second examination, an evoked potential recording is required to identify the hearing loss. This safe, simple and reliable method for detecting hearing loss in infants is recommended for screening programmes during the neonatal period.

  3. Temperature dependence of anuran distortion product otoacoustic emissions

    NARCIS (Netherlands)

    Meenderink, Sebastlaan W. F.; Van Dijk, Pim

    2006-01-01

    To study the possible involvement of energy dependent mechanisms in the transduction of sound within the anuran ear, distortion product otoacoustic emissions (DPOAEs) were recorded in the northern leopard frog over a range of body temperatures. The effect of body temperature depended on the stimulus

  4. Effects of spontaneous otoacoustic emissions on frequency discrimination

    DEFF Research Database (Denmark)

    Hansen, Rói; Santurette, Sébastien; Verhulst, Sarah

    2013-01-01

    When an external tone is presented in proximity to the frequency of a spontaneous otoacoustic emission (SOAE), the SOAE typically synchronizes to the external tone, a phenomenon known as "entrainment". As the tone moves further away from the SOAE frequency, beating patterns between the SOAE and t...

  5. Transient Evoked and Distortion Product Otoacoustic Emissions in a Group of Neonates

    Science.gov (United States)

    Silva, Giovanna Cesar; Delecrode, Camila Ribas; Kemp, Adriana Tahara; Martins, Fabiana; Cardoso, Ana Claudia Vieira

    2015-01-01

    Introduction The most commonly used method in neonatal hearing screening programs is transient evoked otoacoustic emissions in the first stage of the process. There are few studies comparing transient evoked otoacoustic emissions with distortion product, but some authors have investigated the issue. Objective To correlate the results of transient evoked and distortion product otoacoustic emissions in a Brazilian maternity hospital. Methods This is a cross-sectional, comparative, and prospective study. The study included 579 newborns, ranging from 6 to 54 days of age, born in a low-risk maternity hospital and assessed for hearing loss. All neonates underwent hearing screening by transient evoked and distortion product otoacoustic emissions. The results were analyzed using the Spearman correlation test to relate the two procedures. Results The pass index on transient evoked otoacoustic emissions was 95% and on distortion product otoacoustic emissions was 91%. The comparison of the two procedures showed that 91% of neonates passed on both procedures, 4.5% passed only on transient evoked otoacoustic emissions, 0.5% passed only on distortion product otoacoustic emissions, and 4% failed on both procedures. The inferential analysis showed a significant strong positive relationship between the two procedures. Conclusion The failure rate was higher in distortion product otoacoustic emissions when compared with transient evoked; however, there was correlation between the results of the procedures. PMID:26157501

  6. Wavelet analysis demonstrates no abnormality in contralateral suppression of otoacoustic emissions in tinnitus patients

    NARCIS (Netherlands)

    Geven, Leontien I.; Wit, Hero P.; de Kleine, Emile; van Dijk, Pim

    2012-01-01

    The efferent auditory system is thought to play a role in the origin of tinnitus. Part of this system can be tested in humans with contralateral suppression of otoacoustic emissions. Stimulation of the medial olivocochlear efferent system is responsible for this reduction of otoacoustic emissions af

  7. Effects of changes in dynamic characteristics of the middle ear on transient-evoked otoacoustic emissions

    Directory of Open Access Journals (Sweden)

    Špirić Sanja

    2011-01-01

    Full Text Available Transient-evoked otoacoustic emissions are transmitted through the middle ear. The purpose of this study was to investigate the effects of dynamic properties of the transmission system on the measurability of transient otoacoustic emissions. The authors analyzed the presence of transient otoacoustic emissions in 48 children with serous otitis media regarding the tympanogram, presence and type of effusion and pure tone average findings. The results obtained in this research show the predominant absence of transient otoacoustic emissions in patients with type B tympanogram (69.1% especially if the effusion is mucoid (77.5% with the hearing loss of 15 decibel hearing level. This research shows that disorders in dynamic characteristics of the middle ear in patients with serous otitis obstruct the transmission of acoustic energy and affect the measurability of transient otoacoustic emissions, especially if the effusion is mucoid and hearing loss of 15 decibel hearing level.

  8. Over-exposure effects on the distortion product otoacoustic emission

    DEFF Research Database (Denmark)

    Reuter, Karen

    with hearing-loss. Reported measurements of OAEs before and after noise exposure suggest that OAE is a more sensitive measure for the hearing function than pure-tone audiometry and therefore might be a measure for the early identification of hearing loss. No individual diagnosis of OAEs is possible today......, however. In the present study it was investigated, whether Distortion Product OtoAcoustic Emission (DPOAE) parameters exist, which indicate the early stage of a hearing loss. DPOAE was obtained with high frequency resolution, and its characteristic spectral fine structure was analyzed. Data of subjects...

  9. Effects of noise overexposure on distortion product otoacoustic emissions

    DEFF Research Database (Denmark)

    de Toro, Miguel Angel Aranda

    with measurements of distortion product otoacoustic emissions (DPOAE). The assumption is that a difference in the temporary changes from the stimuli may be indicative of a higher risk of NIHL. The results suggest that the risk of NIHL for low-level impulses may be predicted on an energy basis, whereas the penalty...... on the auditory system and the need for penalization. A total of 16 normal-hearing human subjects were exposed under laboratory conditions to three noise stimuli with equal energy: (1) continuous broadband; (2) impulsive+continuous; and (3) tonal. Temporary changes on the hearing of the subjects were evaluated...

  10. Common substructure in otoacoustic emission spectra of land vertebrates

    Science.gov (United States)

    Manley, Geoffrey A.; Köppl, Christine; Bergevin, Christopher

    2015-12-01

    In humans, a similar spectral periodicity is found in all otoacoustic emission types and in threshold fine structure. This may reflect travelling wave phase and reflectance from "structural roughness" in the organ of Corti, or entrainment and suppressive interactions between emissions. To further understand these phenomena, we have examined spontaneous otoacoustic emission (SOAE) spectra in 9 lizard species and the barn owl and find a comparable periodicity. Importantly, the frequency spacing between SOAE peaks was independent of the physical spacing and of the frequency space constants in hearing organs. In 9 lizard species, median spectral gaps lay between 219 and 461 Hz, with no correlation to papillar length (0.3 to 2.1 mm). Similarly in much longer organs: In humans (35 mm), SOAE spectral gaps vary up to 220 Hz at 4 kHz; in the barn owl (11 mm), the median SOAE peak spacing was 395Hz. In the barn owl, a very large space constant between 5 and 10 kHz (5 mm/octave) contrasts with stable SOAE spacing between 1 and 11 kHz. Similar SOAE spectral gaps across all species suggests they represent a basic frequency grating revealing local phase-dependent interactions between active hair cells, a feature not determined by macro-structural anatomy. Emission spectral spacing is independent of cochlear length, of the frequency space constant, of the existence of travelling waves or of a tectorial membrane. Our data suggest that there are greater similarities between frequency selectivity reflected at the level of the hair cells' spontaneous mechanical output (OAEs) than there are at the level of the auditory nerve, where macro-structural anatomy links hair-cell activity differentially to the neural output. Apparently, all hair-cell arrays show a similar frequency substructure not directly replicated in neural tuning.

  11. Human cochlear tuning estimates from stimulus-frequency otoacoustic emissions

    DEFF Research Database (Denmark)

    Bentsen, Thomas; Harte, James; Dau, Torsten

    2011-01-01

    Two objective measures of human cochlear tuning, using stimulus-frequency otoacoustic emissions (SFOAE), have been proposed. One measure used SFOAE phase-gradient delay and the other twotone suppression (2TS) tuning curves. Here, it is hypothesized that the two measures lead to different frequency......-of-tuning curves was observed for experiment 2, consistent with objective and behavioural estimates from the literature. Most importantly, the absolute difference between the two tuning estimates was very large and statistically significant. It is argued that the 2TS estimates of cochlear tuning likely represents...... the underlying properties of the suppression mechanism, and not necessarily cochlear tuning. Thus the phase-gradient delay estimate is the most likely one to reflect cochlear tuning....

  12. Forte Fortissimo for amateur musicians: no effect on otoacoustic emissions.

    Science.gov (United States)

    Møllerløkken, Ole J; Magerøy, Nils; Bråtveit, Magne; Lind, Ola; Moen, Bente E

    2013-03-01

    Many amateur musicians are likely to be exposed to high sound levels during rehearsals. Measuring otoacoustic emissions (OAE) is an objective technique to assess hearing ability and can be used as an early predictor of hearing loss. This study aimed to record sound levels at an amateur brass band rehearsal and to examine the cochlear function of the musicians by evaluating distortion product (DP) OAE amplitudes before and after sound exposure. Twenty-four brass band musicians and 10 office workers were examined with personal noise measurements and DPOAE tests before and after a music rehearsal or one office workday, respectively. The sound levels in the brass band ranged from 92 to 100 dBA, LaEQ 96 dBA. However, the amateur brass band members had no change in DPOAEs after this exposure compared to pre-exposure levels and compared to office workers.

  13. Application of transient evoked otoacoustic emissions to pediatric populations.

    Science.gov (United States)

    Norton, S J

    1993-02-01

    Transient evoked otoacoustic emissions (TEOAEs) occur after presentation of brief acoustic stimuli such as clicks and tone pips. They represent physiological activity from within the cochlea, specifically from normal functioning outer hair cells. TEOAEs are frequency specific in that their spectra are determined by the spectra of the evoking stimulus and the audiometric configuration. TEOAEs are sensitive to mild to moderate degrees of cochlear hearing loss up to about 40 to 50 dB HL. They can be measured rapidly and noninvasively in infants and children. Among the potential applications in pediatric audiology are screening for hearing impairment in neonates, separating peripheral hearing loss and central auditory dysfunction, and monitoring cochlear status in children receiving ototoxic drugs.

  14. Transiently Evoked Otoacoustic Emissions in Children with Otitis Media with Effusion

    Directory of Open Access Journals (Sweden)

    Dimitris G. Balatsouras

    2012-01-01

    Full Text Available Introduction. Otitis media with effusion is a common pediatric disease whose diagnosis is based on pneumatic otoscopy, pure-tone audiometry, and tympanometry. The aim of this study was to evaluate transiently evoked otoacoustic emissions in the diagnosis of otitis media with effusion as compared to tympanometry. Patients and Methods. 38 children with bilateral otitis media with effusion were studied. 40 normal children of similar age and sex were used as controls. All subjects underwent pneumatic otoscopy, standard pure-tone audiometry, tympanometry, and transiently evoked otoacoustic emissions. Results. In the group of children with bilateral otitis media, transiently evoked otoacoustic emissions were absent in 51 ears (67%. In the remaining 25 ears (33% the mean emission amplitude was reduced, as compared to the mean value of the control group. Conclusions. Transiently evoked otoacoustic emissions should be included in the diagnostic workup of otitis media with effusion because it is a fast, reliable, and objective test. Transiently evoked otoacoustic emissions should always be used in conjunction with tympanometry, because a more meaningful interpretation of transiently evoked otoacoustic emissions measures is possible.

  15. Nonlinear time-domain cochlear model for transient stimulation and human otoacoustic emission

    DEFF Research Database (Denmark)

    Verhulst, Sarah; Dau, Torsten; Shera, Christopher A.

    2012-01-01

    This paper describes the implementation and performance of a nonlinear time-domain model of the cochlea for transient stimulation and human otoacoustic emission generation. The nonlinearity simulates compressive growth of measured basilar-membrane impulse responses. The model accounts for reflect......This paper describes the implementation and performance of a nonlinear time-domain model of the cochlea for transient stimulation and human otoacoustic emission generation. The nonlinearity simulates compressive growth of measured basilar-membrane impulse responses. The model accounts...

  16. Otoacoustic emissions recorded in people with chronic migraine

    Institute of Scientific and Technical Information of China (English)

    Lori Cameron; Wei Sun

    2014-01-01

    Migraine, a moderate to severe chronic headache occurring on one or both sides, is a common disease affects young people. Although hearing loss in subjects with migraine is not rare, the correlation of migraine with hearing loss is not clear. In this study, we examined hearing loss in young migraine subjects to determine if migraine may be a factor in causing cochlear dysfunction. Seven college students with migraine and three age matched subjects without history of migraine were assessed using extended high frequency audiometry and distortion product otoacoustic emissions (DPOAEs). There was no significant difference in regular audiometry threshold between the migraine group and the control group. However, high frequency audiometry (9e16 kHz) showed thresholds at 25 dB nHL or higher in six out of twenty ears in the migraine group. The amplitude of DPOAEs were reduced for more than 10 dB in the migraine group in comparison with the control group. These data suggest that migraine may affect cochlear dysfunction evidenced by the reduced amplitude of DPOAE and high frequency pure-tone audiometry.

  17. Music Listening Behavior, Health, Hearing and Otoacoustic Emission Levels

    Directory of Open Access Journals (Sweden)

    Kathleen Hutchinson Marron

    2014-07-01

    Full Text Available This study examined the relationship between hearing levels, otoacoustic emission levels and listening habits related to the use of personal listening devices (PLDs in adults with varying health-related fitness. Duration of PLD use was estimated and volume level was directly measured. Biomarkers of health-related fitness were co-factored into the analyses. 115 subjects ages 18–84 participated in this study. Subjects were divided into two sub-groups; PLD users and non-PLD users. Both groups completed audiological and health-related fitness tests. Due to the mismatch in the mean age of the PLD user versus the non-PLD user groups, age-adjusted statistics were performed to determine factors that contributed to hearing levels. Age was the most significant predictor of hearing levels across listening and health-related fitness variables. PLD user status did not impact hearing measures, yet PLD users who listened less than 8 hours per week with intensities of less than 80 dBA were found to have better hearing. Other variables found to be associated with hearing levels included: years listening to PLD, number of noise environments and use of ear protection. Finally, a healthy waist-to-hip ratio was a significant predictor of better hearing, while body mass index approached, but did not reach statistical significance.

  18. Transient evoked otoacoustic emission input/output function and cochlear reflectivity: experiment and model.

    Science.gov (United States)

    Sisto, Renata; Moleti, Arturo

    2008-11-01

    The complex input/output function of transient evoked otoacoustic emissions is evaluated at different stimulus levels. The experimental response functions were best fitted to the reflectivity functions predicted by theoretical one-dimensional transmission-line models in the perturbative limit. Along with the otoacoustic emission sources usually considered, linear reflection from roughness (place-fixed) and nonlinear distortion (wave-fixed), a wave-fixed scattering potential is also considered, associated with the breaking of the scale-invariance symmetry, as a new additional mechanism for otoacoustic emission generation. A good fit was obtained, across stimulus level and frequency, for roughness, and not for nonlinear distortion, nor for scale-invariance violation. The phase-gradient delay of the same transient evoked otoacoustic emissions was consistent with the latency measured using a wavelet time-frequency technique, at all stimulus levels and frequencies. The results suggest that cochlear reflectivity is dominated by a component with a rapidly rotating phase, at all stimulus levels, in apparent contradiction with the usual assumption that, at high stimulus levels, a significant contribution to the transient evoked otoacoustic response should come from nonlinear distortion. Possible interpretations of this phenomenology are critically reviewed and discussed, considering the theoretical uncertainties and the limitations of the experimental technique. PMID:19045787

  19. Effects of spontaneous otoacoustic emissions on pure-tone frequency difference limens

    DEFF Research Database (Denmark)

    Hansen, Rói; Santurette, Sébastien; Verhulst, Sarah

    2014-01-01

    Pure-tone frequency difference limens (FDLs) have been shown to vary in the vicinity of spontaneous otoacoustic emissions (SOAEs). As lower FDLs have been observed near SOAEs when measured ipsi- and contralaterally to the emission ear, it has been proposed that prolonged ongoing stimulation of ne...

  20. Artifact rejection of distortion product otoacoustic emissions measured after sound exposure

    DEFF Research Database (Denmark)

    Reuter, Karen; Ordoñez, Rodrigo Pizarro; de Toro, Miguel Angel Aranda;

    2007-01-01

    In a previous study [3] distortion product otoacoustic emissions (DPOAEs) were measured both before and after a moderate sound exposure, which caused a reduction of DPOAE levels. After the exposure DPOAEs had often levels below the noise floor. In the present paper it is discussed, whether these ...

  1. Optimization of distortion product otoacoustic emission (DPOAE) measurements with the system IL096

    DEFF Research Database (Denmark)

    de Toro, Miguel Angel Aranda; Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte

    2007-01-01

    Measurements of distortion product otoacoustic emissions (DPOAEs) at Aalborg University are performed with the commercial system ILO96 from Otodynamics. The default measuring setup is not adequate for monitoring the recovery of DPOAEs after noise exposure because (1) data collection is interrupte...

  2. Noise Levels during Aerobics and the Potential Effects on Distortion Product Otoacoustic Emissions

    Science.gov (United States)

    Torre, Peter, III; Howell, Jennifer C.

    2008-01-01

    The purpose of this study was to measure noise levels during aerobics classes and to examine how outer hair cell (OHC) function, using distortion product otoacoustic emissions (DPOAEs), may be affected by this exposure. Fifty individuals (48 women and 2 men, ages 19-41 years) participated in 50-min aerobics classes. Noise levels were measured…

  3. A pilot study of changes in otoacoustic emissions after exposure to live music

    DEFF Research Database (Denmark)

    Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte; Borg, Carsten;

    2012-01-01

    The objectives of this investigation were to document typical sound exposure levels at concerts and to relate them to measurable changes on hearing. Changes in the auditory function of human subjects were measured using Distortion Product Otoacoustic Emissions (DPOAE) and Transient Evoked...

  4. Relating 2f1-f2 distortion product otoacoustic emission and equivalent rectangular bandwidth

    DEFF Research Database (Denmark)

    Christensen, Anders Tornvig; Ordoñez, Rodrigo; Hammershøi, Dorte

    2016-01-01

    To explore the extent of distortion product otoacoustic emission (DPOAE) toward low frequencies we measured in 21 normal-hearing human subjects its dependence on the ratio between evoking stimulus frequencies, f1 and f2, at 2f1-f2 distortion frequencies 88, 176 and 264 Hz. The "optimal" ratio...

  5. Otoacoustic emissions and auditory brainstem responses in patients with sudden sensorineural hearing loss. Do otoacoustic emissions have prognostic value?

    Directory of Open Access Journals (Sweden)

    Manoochehr Amiridavan

    2006-11-01

    prognostic factor in SSNHL, hence we recommend performing TEOAE in every patient with SSNHL. KEY WORDS: Sudden sensorineural hearing loss, pure tone audiometry, otoacoustic emissions, overall correlation, signal to noise ratio (S/N ratio, auditory brainstem responses, Interpeak latencies, retrocochlear lesion.

  6. Do perceptual consequences of spontaneous otoacoustic emissions reflect a central plasticity effect?

    DEFF Research Database (Denmark)

    Hansen, Rói; Santurette, Sébastien; Verhulst, Sarah

    Frequency difference limens (FDLs) have been found to improve in the vicinity of spontaneous otoacoustic emissions (SOAEs). This effect has been observed ipsilaterally and contralaterally to the emission ear, suggesting that prolonged ongoing stimulation of nerve cells tuned to the SOAE frequency...... by continuous ipsilateral presentation of a pure tone aimed at emulating an SOAE. These findings suggest a peripheral rather than central plasticity origin for perceptual consequences of SOAEs....

  7. Newborn hearing screening by transient evoked otoacoustic emissions: analysis of response as a function of risk factors.

    Science.gov (United States)

    De Capua, B; De Felice, C; Costantini, D; Bagnoli, F; Passali, D

    2003-02-01

    Hearing loss can be considered as the most common birth defect. Early detection of hearing loss by screening at, or shortly after, birth and appropriate intervention are critical to speech, language and cognitive development. In the present study, the characteristics of Transient Evoked Otoacoustic Emissions have been evaluated as a function of known pre- and perinatal risk factors for hearing loss. All newborns were screened for hearing loss using a physiologic test of hearing function, the Transient Evoked Otoacoustic Emissions. A total of 532 consecutive newborn infants received binaural Transient Evoked Otoacoustic Emission testing (262 males, 270 females; mean gestational age 39.2 +/- 2.1 weeks, range 26-43; birth weight: 3,240 +/- 550 g, range 910-4,780). The population examined comprised 448 control infants and 84 high-risk for hearing loss infants (Joint Committee on Infant Hearing 1994 criteria). All Transient Evoked Otoacoustic Emission recordings were performed at comparable postconceptional ages. Audiological screening by Transient Evoked Otoacoustic Emission recording showed an overall 100% sensitivity, 99.02% specificity, with negative and positive predictive values of 100% and 62.5%, respectively. As compared to controls, high-risk infants showed: 1. increased rates of Fail-1 (Transient Evoked Otoacoustic Emissions absent at first examination, 21.4% vs 9.8%, p = 0.004), Fail-2 (Transient Evoked Otoacoustic Emissions absent on retesting: 8.64% vs 1.37%, p = 0.0014), false positives (Transient Evoked Otoacoustic Emissions absent/V wave present: 3.7% vs 0.46%, p = 0.029) and true positives (Transient Evoked Otoacoustic Emissions absent, V wave absent: 2.47% or 24.5 per 1,000 live births vs 0.22% or 2.2 per 1,000 live births, p = 0.013); 2. significantly reduced Transient Evoked Otoacoustic Emission intensity in the 0.7-1 kHz (right side) and 1-2 kHz (left side) frequency ranges. Multivariate logistic regression analysis showed a significant positive

  8. Otoacoustic emissions as an instrument of epidemiological surveillance in the health of the workers

    Directory of Open Access Journals (Sweden)

    Oliveira, Priscila Feliciano de

    2011-10-01

    Full Text Available Introduction: The noise is a harmful agent to the hearing, being frequent in urban and work environments. Among the structures of the hearing system, the outer hair cells are the first to be injured, and otoacoustic emissions identify minimal cochlear alterations. Objective: Analyze cochlear alterations with otoacoustic emissions transient evoked in individuals exposed to combined risk: noise and chemical products. Method: 49 workers of a cement company participated of the research, aged between 19 and 49 years old, exposure time of at least two years and normal hearing thresholds. Was performed an anamnesis and otoacoustic emissions before and post work activity. The results of the exam were related with the variable: time of exposure to the noise, age, exposure to chemical products and sound habits. The statistical tests used were: T of Student, chi-squared Pearson test and Fisher's exact test and is characterized by a prospective clinical study. Results: At the first testing, had presence of emissions in all of the workers. The average of amplitude is of 10,22 dBSPL in the right ear and 9,48 dBSPL in the left ear. In the second testing there were a variation of 0,69 dBSPL in the lef ear and 0,42 dBSPL in the right ear, of which 79,6% of individuals had presence of emission bilaterally and 20,4% absence in at least one ear. Analyzing the relation between variations of emissions with the variable was not observed statistically significant data. Conclusion: The otoacoustic emissions in the workers health search to prevent the damage to the hearing system through cochlear changings.

  9. Effects of Low-Frequency Biasing on Otoacoustic and Neural Measures Suggest that Stimulus-Frequency Otoacoustic Emissions Originate Near the Peak Region of the Traveling Wave

    OpenAIRE

    Lichtenhan, Jeffery T.

    2011-01-01

    Stimulus-frequency otoacoustic emissions (SFOAEs) have been used to study a variety of topics in cochlear mechanics, although a current topic of debate is where in the cochlea these emissions are generated. One hypothesis is that SFOAE generation is predominately near the peak region of the traveling wave. An opposing hypothesis is that SFOAE generation near the peak region is deemphasized compared to generation in the tail region of the traveling wave. A comparison was made between the effec...

  10. Distortion product otoacoustic emission fine structure as an early hearing loss predictor

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2006-01-01

    Otoacoustic emissions (OAEs) are a promising method to monitor early noise-induced hearing losses. When distortion product otoacoustic emissions (DPOAEs) are obtained with a high-frequency resolution, a ripple structure across frequency can be seen, called DPOAE fine structure. In this study DPOAE...... fine structures are obtained from 74 normal-hearing humans using primary levels of L1/L2=65/45 dB. The subjects belong to groups with different ages and exposure histories. A classification algorithm is developed, which quantifies the fine structure by the parameter's ripple place, ripple width, ripple...... and vary from subject to subject within groups. The results do not indicate that the DPOAE fine structure alters with the state of hearing, as it is suggested in the literature. The data analysis is still in process at this stage.  ...

  11. Does over-exposure modify the fine structure of distortion product otoacoustic emissions?

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2008-01-01

    It is investigated, whether the pattern of distortion product otoacoustic emission (DPOAE) fine structure (quasi-periodic variations across frequency) is altered by an acoustical over-exposure. DPOAE fine structures are determined in 16 normal-hearing humans using a high frequency-resolution and ......It is investigated, whether the pattern of distortion product otoacoustic emission (DPOAE) fine structure (quasi-periodic variations across frequency) is altered by an acoustical over-exposure. DPOAE fine structures are determined in 16 normal-hearing humans using a high frequency......-resolution and primary levels of L1/L2=65/45 dB. DPOAEs are measured both before and after the subjects are monaurally exposed to a 1 kHz tone lasting for 3 min at an equivalent threshold sound pressure level of 105.5 dB. After the exposure the DPOAE levels are shifted to lower values and recover to the initial levels...

  12. Simultaneous measurement of auditory-steady-state responses and otoacoustic emissions to estimate peripheral compression

    DEFF Research Database (Denmark)

    Sanchez Lopez, Raul; Epp, Bastian

    2016-01-01

    Assessment of the compressive nonlinearity in the hearing system provides useful information about the inner ear. Auditory-steady state responses (ASSR) have recently been used to estimate the state of the compressive nonlinearity in the peripheral auditory system. Since it is commonly assumed...... otoacoustic emissions (SAMOAEs). It is hypothesized that the stimulus used to evoke ASSRs will cause acoustic energy to be reflected back from the inner ear into the ear canal, where it can be picked up as an otoacoustic emission (OAE) and provide information about cochlear processing. Results indicate...... that SAMOAEs can be extracted while measuring ASSRs using sinusoidallyamplitude modulated tones. However, comparison of simulations using a transmission model and the data show that the SAMOAE measured above 50 dB SPL are strongly influenced by the system distortion. A robust extraction and evaluation...

  13. Individual cochlear delays measured with tone-burst-evoked otoacoustic emissions

    DEFF Research Database (Denmark)

    Pigasse, Gilles; Harte, James; Dau, Torsten

    Methods to estimate cochlear delay in humans have been traditionally based on either phase-derived group delays from otoacoustic emissions (OAEs), or auditory brainstem responses (ABR). These methods demonstrate large variability in cochlear delay estimates, and are derived from across subject...... averages. This work aims to assess the individual variability in cochlear delay. Tone-burst evoked otoacoustic emissions (TBOAEs) are used in this study to estimate cochlear delay. The OAE is analysed by separating the non-linear components of cochlear origin, and the linear reflection in the time domain...... with previous studies. However, care must be taken when comparing the results of previous studies. This is due to an ambiguity in the time domain regarding the true onset point of the OAE, and hence the derived cochlear travelling wave latency. The inter-subject variability explains the discrepancy observed...

  14. Influence of acute hyperglycemia on otoacoustic emissions and the medial olivocochlear reflexa)

    OpenAIRE

    Jacobs, Peter G.; Konrad-Martin, Dawn; Mcmillan, Garnett P.; McDermott, Daniel; Fausti, Stephen A.; Kagen, David; Wan, Eric A.

    2012-01-01

    Stimulus-frequency (SF) otoacoustic emission (OAE) amplitude and the amplitude of medial olivocochlear (MOC) inhibition of SF OAEs for ipsilateral, contralateral and bilateral MOC reflex elicitors were recorded in six subjects with type 2 diabetes during a glucose tolerance test (GTT). Five of the six subjects were tested twice for a total of 11 trials and three subjects were tested in a control experiment. During the GTT experiment, the subjects’ blood glucose was elevated from a euglycemic ...

  15. High frequency hearing thresholds and product distortion otoacoustic emissions in cystic fibrosis patients,

    Directory of Open Access Journals (Sweden)

    Lucia Bencke Geyer

    2015-12-01

    Full Text Available ABSTRACT INTRODUCTION: The treatment of patients with cystic fibrosis involves the use of ototoxic drugs, mainly aminoglycoside antibiotics. Due to the use of these drugs, fibrocystic patients are at risk of developing hearing loss. OBJECTIVE: To evaluate the hearing of patients with cystic fibrosis by High Frequency Audiometry and Distortion Product Otoacoustic Emissions. METHODS: Cross-sectional study. The study group consisted of 39 patients (7-20 years of age with cystic fibrosis and a control group of 36 individuals in the same age group without otologic complaints, with normal audiometric thresholds and type A tympanometric curves. High Frequency Audiometry and Distortion Product Otoacoustic Emissions tests were conducted. RESULTS: The study group had significantly higher thresholds at 250, 1000, 8000, 9000, 10,000, 12,500, and 16,000 Hz (p = 0.004 as well as higher prevalence of otoacoustic emission alterations at 1000 and 6000 Hz (p = 0.001, with significantly lower amplitudes at 1000, 1400, and 6000 Hz. There was a significant association between alterations in hearing thresholds in High Frequency Audiometry with the number of courses of aminoglycosides administered (p = 0.005. Eighty-three percent of patients who completed more than ten courses of aminoglycosides had hearing loss in High Frequency Audiometry. CONCLUSION: A significant number of patients with cystic fibrosis who received repeated courses of aminoglycosides showed alterations in High Frequency Audiometry and Distortion Product Otoacoustic Emissions. The implementation of ten or more aminoglycoside cycles was associated with alterations in High Frequency Audiometry.

  16. Deriving cochlear delays in humans using otoacoustic emissions and auditory evoked potentials

    DEFF Research Database (Denmark)

    Pigasse, Gilles

    . These methods include: otoacoustic emissions (OAEs), auditory brainstem responses (ABRs) and auditory steady-state responses (ASSRs). A comparison between the three methods was made across and within subjects, in order to highlight the impact of inter-subject variability on the cochlear delay estimates...... results are also given for an experiment using stimuli designed to compensate for OAE delays. These were designed to try and reproduce the success of similar stimuli now used routinely to improve ABR signal-to-noise ratio....

  17. Distortion Product Otoacoustic Emissions: A Tool for Hearing Assessment and Scientific Study

    OpenAIRE

    Abdala, Caroline; Visser-Dumont, Leslie

    2001-01-01

    Distortion product otoacoustic emissions (DPOAEs) reflect outer hnir cell integrity and cochlear function. When used appropriately in the audiology clinic, they are an effective diagnostic tool and can detect hearing loss with accuracy. DPOAEs are easily and rapidly recorded in newborns and children, and provide basic hearing screening information as well as detailed diagnostic information in cases of suspected hearing loss. In the past decade, solid guidelines hnve been established to select...

  18. Community based universal neonatal hearing screening by health visitors using otoacoustic emissions

    OpenAIRE

    Owen, M.(School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom); Webb, M.; Evans, K.

    2001-01-01

    OBJECTIVES—To carry out a pilot study to test the feasibility of health visitors (HVs) performing neonatal otoacoustic emissions (OAE) hearing screening in the community using Echoport ILO288 and to evaluate its acceptability to parents and HVs.
DESIGN—Prospective cohort study.
SETTING—Local health centres and babies' homes in urban and rural settings in West Gloucestershire.
PARTICIPANTS—Twelve HVs, 683 babies, and their parents.
MAIN OUTCOME MEASURES—Coverage rate, a...

  19. Modification of otoacoustic emissions following ear-level exposure to MP3 player music.

    Science.gov (United States)

    Bhagat, Shaum P; Davis, Anne M

    2008-12-01

    The purpose of this study was to examine if a pre-determined exposure level and duration of MP3 player music would result in significant changes in cochlear function when measured with audiometric and physiological methods. Distortion-product otoacoustic emissions (DPOAEs), synchronized spontaneous otoacoustic emissions (SSOAEs), and hearing thresholds were measured in 20 normal-hearing adults before and after a 30-minute MP3 player music exposure. DPOAEs were acquired with 65/45 dB SPL primary tones (f(2)=0.842-7.996 kHz) with a frequency resolution of 8 points/octave. A probe microphone system recorded ear-canal music levels and was used to equalize levels at approximately 85 dBC across individuals during the music presentation. Comparison of pre- and post-exposure measurements revealed no significant differences in hearing thresholds, but DPOAE levels in half-octave bands centered from 1.4-6.0 kHz were significantly reduced following the music exposure. Post-exposure shifts in SSOAE frequency and level were highly variable in individuals identified with SSOAEs. The results for the exposure conditions explored in this study indicate that changes in otoacoustic emissions may precede the development of music-induced hearing threshold shifts. PMID:19085399

  20. [Neonatal screening of deafness: evoked otoacoustic emissions or acoustic distortion products?].

    Science.gov (United States)

    Roman, S; Mondain, M; Triglia, J M; Uziel, A

    2001-01-01

    Transiently evoked otoacoustic emissions (TEOAE) allows an auditory screening in neonates above 30 dB and between 2 kHz to 4 kHz. Another type of otoacoustic emissions, the distortion product (DP) allows a similar screening and provides more specific frequency information over a broader frequency range, including frequencies below 2 kHz and above 4 kHz. The goal of this study was to determine 1) the interest of distortion product in comparison with TEOAE in a auditory screening program in neonates; 2) The predictive value of information extracted from otoacoustic emissions recordings, on frequential parameters of distortion product (DP). In this prospective study, TEOAE and DP were successively recorded in 20 neonates (34 ears) with risk of hearing impairment, using the ILO92 software and hardware. When TEOAs were no detectable (9/34), the DPs were no detectable neither (10/34). When TEOAs were detectable, the Dps carried more specific frequency information above 1 kHz in 52 to 80% of the patients. DP amplitudes have been quantitatively correlated with TEOA energy bands. Correlations between DP and TEOA have been objectivized for DP2.5 and DP4 with OE2, and for DP4 and DP6 with OE5. The correlation predictive value was above 85%. In conclusion, this study demonstrated that analysis of TEOA spectrums procures frequential information without requiring DP recordings.

  1. Interactions between hair cells shape spontaneous otoacoustic emissions in a model of the tokay gecko's cochlea.

    Directory of Open Access Journals (Sweden)

    Michael Gelfand

    Full Text Available BACKGROUND: The hearing of tetrapods including humans is enhanced by an active process that amplifies the mechanical inputs associated with sound, sharpens frequency selectivity, and compresses the range of responsiveness. The most striking manifestation of the active process is spontaneous otoacoustic emission, the unprovoked emergence of sound from an ear. Hair cells, the sensory receptors of the inner ear, are known to provide the energy for such emissions; it is unclear, though, how ensembles of such cells collude to power observable emissions. METHODOLOGY AND PRINCIPAL FINDINGS: We have measured and modeled spontaneous otoacoustic emissions from the ear of the tokay gecko, a convenient experimental subject that produces robust emissions. Using a van der Pol formulation to represent each cluster of hair cells within a tonotopic array, we have examined the factors that influence the cooperative interaction between oscillators. CONCLUSIONS AND SIGNIFICANCE: A model that includes viscous interactions between adjacent hair cells fails to produce emissions similar to those observed experimentally. In contrast, elastic coupling yields realistic results, especially if the oscillators near the ends of the array are weakened so as to minimize boundary effects. Introducing stochastic irregularity in the strength of oscillators stabilizes peaks in the spectrum of modeled emissions, further increasing the similarity to the responses of actual ears. Finally, and again in agreement with experimental findings, the inclusion of a pure-tone external stimulus repels the spectral peaks of spontaneous emissions. Our results suggest that elastic coupling between oscillators of slightly differing strength explains several properties of the spontaneous otoacoustic emissions in the gecko.

  2. Localization of the Reflection Sources of Stimulus-Frequency Otoacoustic Emissions.

    Science.gov (United States)

    Moleti, A; Sisto, R

    2016-10-01

    The generation of stimulus-frequency otoacoustic emission (SFOAE) residuals in humans is analyzed both theoretically and experimentally to investigate the relation between the frequency difference between the probe and the suppressor tone and the localization of the residual source. Experimental measurements of the SFOAE residual were performed using suppressors of increasing frequency to separate the otoacoustic response from the probe stimulus. From the response to the probe alone, the SFOAE response was also estimated, using spectral smoothing, and compared with the residuals obtained for different frequency suppressors. A nonlinear delayed-stiffness active cochlear model was used to compute the spatial distribution of the residual sources according to a recent model of the local reflectivity from roughness, as a function of the suppressor frequency. The simulations clarified the role of high-frequency suppressors, showing that in humans, with increasing suppressor frequency, the generation region of the residual is only slightly basally shifted with respect to the case of a near-frequency suppressor, near the basal edge of the peak of the resonant basilar membrane response. As a consequence, the hierarchy among different-delay components correspondingly changes, gradually favoring short-delay components, with increasing suppressor frequency. Good agreement between the experimental and theoretical dependence of the level of otoacoustic components of different delay on the frequency shift between probe and suppressor confirms the validity of this interpretation.

  3. Stimulus Ratio and Level Dependence of Low- and Mid-Frequency Distortion-Product Otoacoustic Emissions

    DEFF Research Database (Denmark)

    Christensen, Anders Tornvig; Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte

    2014-01-01

    Active amplifiers within the cochlea generate, as a by-product of their function, distortion-product otoacoustic emissions (DPOAEs) in response to carefully chosen two-tone stimuli. Focus has been on invoking emissions in a mid-frequency range from 500 to 4000 Hz. Below 500 Hz, physiological noise...... audiometrically normal hearing for inclusion in our experiment. DPOAEs were measured with pure-tone stimuli in four configurations: f2 fixed around a mid-frequency (2050-2180 Hz), f2 fixed around a low frequency (512-545 Hz), fdp fixed at a mid-frequency (1231 Hz) and fdp low frequency (246 Hz). Eight stimulus...

  4. Comparison of transient and distortion-product otoacoustic emissions during the luteal and follicular phases of the menstrual cycle.

    Science.gov (United States)

    Gurbuzler, Levent; Yelken, Kursat; Aladag, Ibrahim; Eyibilen, Ahmet; Koc, Sema

    2012-08-01

    We conducted a study to examine cochlear activity in women with a naturally occurring menstrual cycle by measuring transient otoacoustic emissions (TOAEs) and distortion-product otoacoustic emissions (DPOAEs). Our study population was made up of 11 women aged 20 to 40 years (mean: 35.6) who were not taking a contraceptive medication or hormone therapy. Measurements of TOAEs and DPOAEs were made during both the follicular phase and the luteal phase of the menstrual cycle. We found no statistically significant difference in any of the TOAE amplitude values between the two phases. Although a sharp decrease at the 0.75 kHz frequency was seen in DPOAEs during both phases, none of the amplitude values in the tested frequencies were significantly different between the two phases. The absence of TOAE and DPOAE amplitude changes suggests that it is unnecessary to take into account the phase of the menstrual cycle when interpreting the results of otoacoustic emissions testing. PMID:22930081

  5. A STUDY OF HEARING EVALUATION FOR NEONATES WITH HYPERBILIRUBINEMIA USING OTOACOUSTIC EMISSION AND BRAIN STEM AUDITORY EVOKED RESPONSE

    Directory of Open Access Journals (Sweden)

    Poornima

    2014-03-01

    Full Text Available Jaundice is one of the most common problems occurring in newborns. Although most of jaundiced patients are normal; because of the bilirubin toxicity, high serum levels can lead to kernicterus. It is important to identify and evaluate the jaundice early to prevent complications like bilirubin encephalopathy leading to hearing loss. Such early detection is possible only if some form of routine screening is used, one of which is otoacoustic emission. By detecting the hearing loss in time with screening methods we can ensure normal language development by appropriate intervention like hearing aids and infant stimulation. In this study otoacoustic emission will be followed by brain stem auditory evoked response and the results will be analyzed to look for the effectiveness of using otoacoustic emission for mass screening. METHODOLOGY: after obtaining approval and clearance from the institutional ethics committee this study included 105 children which satisfied the inclusion criteria. A standard case record was maintained for each subject. The neonate was subjected to otoacoustic emission just before discharge from the hospital. Otoacoustic emission was followed by brain stem auditory evoked response and the results compiled. Result of brain stem auditory evoked response was taken as gold standard and the results were analyzed. RESULTS: Abnormal OAE changes were seen in 6 and abnormal BERA was seen in 9 babies out of a total of 105 babies tested with hyperbilirubinemia. CONCLUSION: use of otoacoustic emissions as initial screening test provides as easy, cost effective and quick method to detect infants with hearing loss. As it is less invasive and less time consuming than BERA, dpOAE can be used as initial screening method for hearing loss in infants with BERA being reserved for infants that fail dpOAE.

  6. Recovery of distortion product otoacoustic emissions (DPOAE) after impulse vs. continuous equal-energy exposures

    DEFF Research Database (Denmark)

    de Toro, Miguel Angel Aranda; Ordoñez, Rodrigo Pizarro; Reuter, Karen;

    2008-01-01

    impulse and continuous noise. Noise exposures are normalized to have the same energy (LAeq,8h= 80dB). The effects in the hearing of the subjects are monitored by measuring the recovery of the distortion product otoacoustic emissions (DPOAE) with high-time resolution. The results can be used to investigate...... the validity of current assessment methods and descriptors of the temporal characteristics of sound exposures and their relation to the temporal effects produced on the human hearing as well as investigating selected issues that may lead to possible improvements or alternative measuring methods. [Work...... supported by the Danish Research Council for Technology and Production.]...

  7. Comparison of cochlear delay estimates using otoacoustic emissions and auditory brainstem responses

    DEFF Research Database (Denmark)

    Harte, James; Pigasse, Gilles; Dau, Torsten

    2009-01-01

    Different attempts have been made to directly measure frequency specific basilar membrane (BM) delays in animals, e.g., laser velocimetry of BM vibrations and auditory nerve fiber recordings. The present study uses otoacoustic emissions (OAEs) and auditory brainstem responses (ABRs) to estimate B...... and synaptic delays. This allows a comparison between individual OAE and BM delays over a large frequency range in the same subjects, and offers support to the theory that OAEs are reflected from a tonotopic place and carried back to the cochlear base via a reverse traveling wave....

  8. CONTRALATERAL SUPPRESSION OF DISTORTION PRODUCT OTOACOUSTIC EMISSION IN CHILDREN WITH AUDITORY PROCESSING DISORDERS

    Institute of Scientific and Technical Information of China (English)

    Jessica Oppee; SUN Wei; Nancy Stecker

    2014-01-01

    Previous research has demonstrated that the amplitude of evoked emissions decreases in human sub-jects when the contralateral ear is stimulated by noise. The medial olivocochlear bundle (MOCB) is be-lieved to control this phenomenon. Recent research has examined this effect in individuals with auditory pro-cessing disorders (APD), specifically with difficulty understanding speech in noise. Results showed tran-sient evoked otoacoustic emissions (TEOAEs) were not affected by contralateral stimulation in these sub-jects. Much clinical research has measured the function of the MOCB through TEOAEs.This study will use an alternative technique, distortion product otoacoustic emissions (DPOAEs), to examine this phenomenon and evaluate the function of the MOCB. DPOAEs of individuals in a control group with normal hearing and no significant auditory processing difficulties were compared to the DPOAEs of children with signifi-cant auditory processing difficulties.Results showed that the suppression effect was observed in the control group at 2 kHz with 3 kHz of narrowband noise. For the auditory processing disorders group, no significant suppression was observed.Overall, DPOAEs showed suppression with contralateral noise, while the APD group levels increased overall.These results provide further evidence that the MOCB may have reduced function in children with APD.

  9. Spontaneous otoacoustic emissions in an active nonlinear cochlear model in the time domain

    Science.gov (United States)

    Fruth, Florian; Jülicher, Frank; Lindner, Benjamin

    2015-12-01

    A large fraction of human cochleas emits sounds even in the absence of external stimulation. These so-called spontaneous otoacoustic emissions (SOAEs) are a hallmark of the active nonlinear amplification process taking place in the cochlea. Here, we extend a previously proposed frequency domain model and put forward an active nonlinear one-dimensional model of the cochlea in the time domain describing human SOAEs [5]. In our model, oscillatory elements are close to an instability (Hopf bifurcation), they are subject to dynamical noise and coupled by hydrodynamic, elastic and dissipative interactions. Furthermore, oscillators are subject to a weak spatial irregularity in their activity (normally distributed and exponentially correlated in space) that gives rise to the individuality of each simulated cochlea. Our model captures main statistical features of the distribution of emission frequencies, the distribution of the numbers of emissions per cochlea, and the distribution of the distances between neighboring emissions as were previously measured in experiment [14].

  10. Distortion product otoacoustic emission generation mechanisms and their dependence on stimulus level and primary frequency ratio.

    Science.gov (United States)

    Botti, Teresa; Sisto, Renata; Sanjust, Filippo; Moleti, Arturo; D'Amato, Luisa

    2016-02-01

    In this study, a systematic analysis of the dependence on stimulus level and primary frequency ratio r of the different components of human distortion product otoacoustic emissions has been performed, to check the validity of theoretical models of their generation, as regards the localization of the sources and the relative weight of distortion and reflection generation mechanisms. 2f1 - f2 and 2f2 - f1 distortion product otoacoustic emissions of 12 normal hearing ears from six human subjects have been measured at four different levels, in the range [35, 65] dB sound pressure level, at eight different ratios, in the range [1.1, 1.45]. Time-frequency filtering was used to separate distortion and reflection components. Numerical simulations have also been performed using an active nonlinear cochlear model. Both in the experiment and in the simulations, the behavior of the 2f1 - f2 distortion and reflection components was in agreement with previous measurements and with the predictions of the two-source model. The 2f2 - f1 response showed a rotating-phase component only, whose behavior was in general agreement with that predicted for a component generated and reflected within a region basal to the characteristic place of frequency 2f2 - f1, although alternative interpretations, which are also discussed, cannot be ruled out.

  11. Spontaneous otoacoustic emissions in the European edible frog (Rana esculenta): spectral details and temperature dependence.

    Science.gov (United States)

    van Dijk, P; Wit, H P; Segenhout, J M

    1989-11-01

    Spontaneous otoacoustic emissions were recorded in 41 ears of 29 European edible frogs (Rana esculenta). Emission frequencies ranged from 450 to 1350 Hz. The distribution of frequencies shows two distinct populations: one above and one below 1 kHz. With one exception, a maximum number of two emissions were recorded per ear, each in a different population. An amplitude distribution of a frog emission was sampled, from which it was concluded that the emission is generated by an active oscillator. The spectral width of an emission ranged from 1 to 200 Hz (average 38 Hz). There was negative correlation between sound pressure level of an emission and spectral width. In 4 frogs the dependence of emission power and frequency on temperature was investigated. An emission could be 'switched on and off' within a few degrees centigrade. At temperatures below the switching interval no emission was recorded; for higher temperatures emission power showed no dependence on temperature. Frequency increased with temperature (Q10 = 1.1 to 1.3). This yields a mismatch with temperature dependence of best frequencies of auditory fibers. The consequences of this mismatch are discussed. PMID:2691473

  12. Overexposure effects of a 1-kHz tone on the distortion product otoacoustic emission in humans

    DEFF Research Database (Denmark)

    Reuter, Karen; Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte

    2007-01-01

    The effects of overexposure on the properties of distortion product otoacoustic emissions (DPOAEs) are investigated. In total, 39 normal-hearing humans were monaurally exposed to a 1-kHz tone lasting for 3 min at an equivalent threshold sound-pressure level of 105.5 dB. The effects of overexposure...

  13. Compensating for Deviant Middle Ear Pressure in Otoacoustic Emission Measurements, Data, and Comparison to a Middle Ear Model

    NARCIS (Netherlands)

    Hof, Janny R.; de Kleine, Emile; Avan, Paul; Anteunis, Lucien J. C.; Koopmans, Peter J.; van Dijk, Pim

    2012-01-01

    Objective: Deviant middle ear pressure has a negative effect on the forward and backward transmission of stimulus and emissions through the middle ear. Resolving this deviant middle ear pressure is expected to lead to better middle ear transmission and, as a result of this, stronger otoacoustic emis

  14. Middle ear influence on otoacoustic emissions. I : Noninvasive investigation of the human transmission apparatus and comparison with model results

    NARCIS (Netherlands)

    Avan, P; Buki, B; Maat, B; Dordain, M; Wit, HP

    2000-01-01

    Evoked otoacoustic emissions (EOAEs) are generated within the cochlea in response to external sounds, and they can be acoustically detected in the external auditory meatus after backward propagation through the middle ear. In addition to being used to probe the cochlear mechanisms, they are expected

  15. Effects of background noise on transiently evoked otoacoustic emissions in newborn hearing screening

    Directory of Open Access Journals (Sweden)

    Chandrakant Vishwakarma

    2015-01-01

    Full Text Available Introduction: Newborn hearing screening program is one of the services offered in Neonatal Intensive Care Units (NICU by most of the neonatologist today. Aim of the Study: Present study aimed to investigate the ambient noise levels which allow successful transient evoked otoacoustic emission testing. Method: 25 normal hearing neonates (group 1 and 25 normal hearing adults (group 2 participated in the study. Both groups were tested at 30 dB sound pressure level (SPL, 40 dB SPL and 50 dB SPL noise levels. Results and Discussion: Tests results showed with increase in noise levels number of passing subjects decreased and also testing was done at times more than once. Conclusion: Tester should take care of noise levels while doing the test in NICU, which can give false negative responses.

  16. Avoiding spectral leakage in measurements of distortion-product otoacoustic emissions

    DEFF Research Database (Denmark)

    Christensen, Anders Tornvig; Ordoñez, Rodrigo Pizarro; Hammershøi, Dorte

    2014-01-01

    The typical measurement of distortion-product otoacoustic emissions (DPOAEs) relies on the discrete Fourier transformation (DFT) to extract amplitude and phase of the response at the 2f1-f2 DPOAE frequency, f1 and f2 being the frequencies of the stimulus. The DFT measures the DPOAE response....... They allow for a maximum DPOAE resolution of 4, 7 and 3 DFT bins, respectively. Simulation shows that, as the distortion-frequency 2f1-f2 decreases, the error at 2f1-f2 due to spectral leakage from f1 and f2 increases to more than 10 dB depending on relative levels. Controlling for this error by selecting...... as the distortion-frequency decreases. Contrary to the impression one might get from the literature, there is no indication that the nonlinearity producing distortion in the cochlea rolls off towards low frequencies....

  17. Separating medial olivocochlear from acoustic reflex effects on transient evoked otoacoustic emissions in unanesthetized mice

    Science.gov (United States)

    Xu, Yingyue; Cheatham, Mary Ann; Siegel, Jonathan

    2015-12-01

    Descending neural pathways in the mammalian auditory system are believed to modulate the function of the peripheral auditory system [3, 8, 10]. These pathways include the medial olivocochlear (MOC) efferent innervation to the cochlear outer hair cells (OHCs) and the acoustic reflex pathways mediating middle ear muscle (MEM) contractions. The MOC effects can be monitored noninvasively using otoacoustic emissions (OAEs) [5, 6], which are acoustic byproducts of cochlear function [7]. In this study, we applied a sensitive method to determine when and to what degree contralateral MEM suppression contaminated MOC efferent effects on TEOAEs in unanesthetized mice. The lowest contralateral broadband noise evoking MEM contractions varied across animals. Examples of potential MOC-mediated TEOAE suppression with contralateral noise below MEM contraction thresholds were seen, but this behavior did not occur in the majority of cases.

  18. Relation of distortion product otoacoustic emission and tinnitus in normal hearing patients: A pilot study

    Directory of Open Access Journals (Sweden)

    Datt Modh

    2014-01-01

    Full Text Available Introduction: Tinnitus, the perception of the sound in the absence of an external acoustic source, disrupts the daily life 1 out of every 200 adults, yet its physiological basis remains largely a mystery. The generation of tinnitus is commonly linked with the impaired functioning of the outer hair cells (OHC inside the cochlea. Otoacoustic emissions are the objective test used to assess their activity. Objective: The objective of the investigation was to study the features of Distortion product OtoAcoustic emissions (DPOAE in a group of tinnitus patients with normal hearing and to find out whether there is any difference in DPOAE findings in the tinnitus patients with normal hearing and in persons with normal hearing with no complaint of tinnitus. Materials and Methods: The participants consisted of two groups. The subject group consisted of 16 ears of patients, in which 6 subjects were having tinnitus in both ears while 4 subjects were having tinnitus only in one ear. All subjects were aged between 20 to 60 years with complaint of tinnitus with audiometrically normal hearing. Control group was comprised of 16 audiometrically normal hearing ears of persons who were age and gender matched with the subject groups and had no complaint of tinnitus. Both the subject group as well as control group was subjected for DPOAE test. Findings of both the groups were compared using the unpaired t test. Result and conclusion: It was observed that the amplitudes of DPOAE were significantly lower in tinnitus patients than that of persons without complaint of tinnitus, at a frequency of 1281-1560, 5120-6250, 7243-8837 Hz, which imply that decrease of DPOAEs amplitudes may be related to the presence of tinnitus. It can be concluded that there is association between tinnitus and reduced OHC activity which indicate the OHC of cochlea are involved in the generation of tinnitus.

  19. Distortion-product otoacoustic emission reflection-component delays and cochlear tuning: Estimates from across the human lifespan

    DEFF Research Database (Denmark)

    Abdala, Carolina; Guérit, François; Luo, Ping;

    2014-01-01

    A consistent relationship between reflection-emission delay and cochlear tuning has been demonstrated in a variety of mammalian species, as predicted by filter theory and models of otoacoustic emission (OAE) generation. As a step toward the goal of studying cochlear tuning throughout the human...... lifespan, this paper exploits the relationship and explores two strategies for estimating delay trends—energy weighting and peak picking—both of which emphasize data at the peaks of the magnitude fine structure. Distortion product otoacoustic emissions (DPOAEs) at 2f1f2 were recorded, and their reflection...... yielding slightly shorter delays and the latter somewhat smaller confidence intervals. Delay and tuning estimates from young adults roughly match those obtained from SFOAEs. Although the match is imperfect, reflection-component delays showed the expected bend (apical-basal transition) near 1 k...

  20. Otoacoustic emission (OAE)-based measurement of the functioning of the human cochlea and the efferent auditory system

    OpenAIRE

    Mishra, Srikanta Kumar

    2010-01-01

    The discovery of otoacoustic emissions (OAE) has advanced our understanding of cochlear mechanics and the efferent auditory system. OAE are sounds generated within normal cochlea either spontaneously or in response to stimulation. The ability to measure OAE non-invasively, objectively and quickly makes a powerful tool to probe cochlear mechanics. Stimulation of the efferent auditory system causes changes in cochlear amplification processes and hence changes characteristics of OAE. Contrala...

  1. Fluid Shifts: Otoacoustical Emission Changes in Response to Posture and Lower Body Negative Pressure

    Science.gov (United States)

    Melgoza, R.; Kemp, D.; Ebert, D.; Danielson, R.; Stenger, M.; Hargens, A.; Dulchavsky, S.

    2016-01-01

    INTRODUCTION: The purpose of the NASA Fluid Shifts Study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to correlate these findings with vision changes and other elements of the visual impairment and intracranial pressure (VIIP) syndrome. VIIP signs and symptoms, as well as postflight lumbar puncture data, suggest that elevated intracranial pressure (ICP) may be associated with spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. Due to the invasive nature of direct measures of ICP, a noninvasive technique of monitoring ICP is desired for use during spaceflight. The phase angle and amplitude of otoacoustic emissions (OAEs) have been shown to be sensitive to posture change and ICP (1, 2), therefore use of OAEs is an attractive option. OAEs are low-level sounds produced by the sensory cells of the cochlea in response to auditory stimulation. These sounds travel peripherally from the cochlea, through the oval window, to the ear canal where they can be recorded. OAE transmission is sensitive to changes in the stiffness of the oval window, occurring as a result of changes in cochlear pressure. Increased stiffness of the oval window largely affects the transmission of sound from the cochlea at frequencies between 800 Hz and 1600 Hz. OAEs can be self-recorded in the laboratory or on the ISS using a handheld device. Our primary objectives regarding OAE measures in this experiment were to 1) validate this method during preflight testing of each crewmember (while sitting, supine and in head-down tilt position), and 2) determine if OAE measures (and presumably ICP) are responsive to lower body negative pressure and to spaceflight. METHODS: Distortion-product otoacoustic emissions (DPOAEs) and transient evoked otoacoustic emissions (TEOAEs) were recorded preflight using the Otoport Advance OAE system (Otodynamics Ltd., Hatfield, UK). Data were collected in four conditions (seated

  2. Time-frequency analysis of transient-evoked otoacoustic emissions in children exposed to carboplatin chemotherapy.

    Science.gov (United States)

    Bhagat, Shaum; Bass, Johnnie; Qaddoumi, Ibrahim; Brennan, Rachel; Wilson, Matthew; Wu, Jianrong; Galindo, Carlos-Rodriguez; Paglialonga, Alessia; Tognola, Gabriella

    2013-01-01

    The aims of this study were to characterize and quantify time-frequency changes in transient-evoked otoacoustic emissions (TEOAEs) recorded in children diagnosed with retinoblastoma who were receiving carboplatin chemotherapy. A signal processing technique, the wavelet transform (WT), was used to analyze TEOAE waveforms in narrow-band frequency components. Ten children (aged 3-72 months) diagnosed with unilateral or bilateral retinoblastoma were enrolled in the study. TEOAEs were acquired from the children with linear sequences of 70 dB peak equivalent SPL clicks. After WT analysis, TEOAE energy, latency and normalized energy in the narrow-band frequency components were compared before and during carboplatin chemotherapy treatment (average dose 1693 mg/m2). On a group basis, no significant differences (p>0.05) in the TEOAE energy, latency or normalized energy before and after carboplatin treatment were observed. There were decreases in normalized energy on an individual basis in 10 out of 18 ears in the sample. Exposure to carboplatin chemotherapy did not cause significant changes in TEOAE energy, latency and normalized energy during treatment. However, long-term monitoring of hearing with measurements of TEOAEs is warranted, given the risks of delayed hearing loss in some children receiving carboplatin chemotherapy.

  3. Adaptive filter based two-probe noise suppression system for transient evoked otoacoustic emission detection.

    Science.gov (United States)

    Subotić, Miško; Šarić, Zoran; Jovičić, Slobodan T

    2012-03-01

    Transient otoacoustic emission (TEOAE) is a method widely used in clinical practice for assessment of hearing quality. The main problem in TEOAE detection is its much lower level than the level of environmental and biological noise. While the environmental noise level can be controlled, the biological noise can be only reduced by appropriate signal processing. This paper presents a new two-probe preprocessing TEOAE system for suppression of the biological noise by adaptive filtering. The system records biological noises in both ears and applies a specific adaptive filtering approach for suppression of biological noise in the ear canal with TEOAE. The adaptive filtering approach includes robust sign error LMS algorithm, stimuli response summation according to the derived non-linear response (DNLR) technique, subtraction of the estimated TEOAE signal and residual noise suppression. The proposed TEOAE detection system is tested by three quality measures: signal-to-noise ratio (S/N), reproducibility of TEOAE, and measurement time. The maximal TEOAE detection improvement is dependent on the coherence function between biological noise in left and right ears. The experimental results show maximal improvement of 7 dB in S/N, improvement in reproducibility near 40% and reduction in duration of TEOAE measurement of over 30%.

  4. Distortion-product otoacoustic emissions: body position effects with simultaneous presentation of tone pairs

    Directory of Open Access Journals (Sweden)

    Samuel R. Atcherson

    2011-11-01

    Full Text Available This study examined the effect of three different body positions on distortion-product otoacoustic emission (DPOAE amplitude and noise levels with multiple primary tone pairs simultaneously-presented to 36 normal-hearing female human adults. Other studies have demonstrated that the simultaneously presented tone pairs method shows clinical promise as a screener, but the sequential method remains in widespread clinical use. Postural changes have been suggested to have an effect not only on DPOAEs, but also transient-evoked OAEs and stimulus- frequency OAEs. DPOAE amplitude and noise levels were recorded in seated, supine, and side-lying positions to the following order of simultaneously-presented tone pairs relative to the f2 frequencies: 1187, 2375, and 4812 Hz; 1500, 3000, and 6062 Hz; and 1875, 3812, and 7625 Hz. No DPOAE could be detected reliably at 7625 Hz as result of poor signal-to-noise ratio. For remaining DPOAEs, statistical analyses revealed that amplitudes were not significantly different among the three body positions. However, at 1500 Hz and below, body position did have a statistically significant effect on noise levels though they are likely clinically negligible. Except at 7625 Hz, results suggest that DPOAEs recorded using a simultaneously presented tone pairs appear to be comparably recorded regardless of an individual’s body position.

  5. Masculinizing effects on otoacoustic emissions and auditory evoked potentials in women using oral contraceptives.

    Science.gov (United States)

    McFadden, D

    2000-04-01

    The otoacoustic emissions (OAEs) and auditory evoked potentials (AEPs) measured in two separate large scale studies were examined retrospectively for potential differences between those women using, and those not using, oral contraception (OC). Fourteen dependent variables were examined, all of which exhibited substantial sex differences. For 13 of those 14 dependent variables, the means for the users of OC were shifted away from the means of the non-users in the direction of the males. Specifically, for four different measures of OAE strength, for seven of eight measures of AEP latency or amplitude, and for two cognitive tests (mental rotation and water level), the means for the users of OC were located intermediate to those of the non-users of OC and the males. Few of these differences between users and non-users of OC achieved statistical significance, but the near universality of the direction of the difference suggests that oral contraceptives do produce a weak masculinizing effect on some auditory structures. These weak masculinizing effects appear to run contrary to the facts that the levels of both free testosterone and estradiol are lower in women using OC than in normal-cycling women. Past findings on auditory sex differences may have underestimated those sex differences. PMID:10748325

  6. Tinnitus is associated with reduced sound level tolerance in adolescents with normal audiograms and otoacoustic emissions

    Science.gov (United States)

    Sanchez, Tanit Ganz; Moraes, Fernanda; Casseb, Juliana; Cota, Jaci; Freire, Katya; Roberts, Larry E.

    2016-01-01

    Recent neuroscience research suggests that tinnitus may reflect synaptic loss in the cochlea that does not express in the audiogram but leads to neural changes in auditory pathways that reduce sound level tolerance (SLT). Adolescents (N = 170) completed a questionnaire addressing their prior experience with tinnitus, potentially risky listening habits, and sensitivity to ordinary sounds, followed by psychoacoustic measurements in a sound booth. Among all adolescents 54.7% reported by questionnaire that they had previously experienced tinnitus, while 28.8% heard tinnitus in the booth. Psychoacoustic properties of tinnitus measured in the sound booth corresponded with those of chronic adult tinnitus sufferers. Neither hearing thresholds (≤15 dB HL to 16 kHz) nor otoacoustic emissions discriminated between adolescents reporting or not reporting tinnitus in the sound booth, but loudness discomfort levels (a psychoacoustic measure of SLT) did so, averaging 11.3 dB lower in adolescents experiencing tinnitus in the acoustic chamber. Although risky listening habits were near universal, the teenagers experiencing tinnitus and reduced SLT tended to be more protective of their hearing. Tinnitus and reduced SLT could be early indications of a vulnerability to hidden synaptic injury that is prevalent among adolescents and expressed following exposure to high level environmental sounds. PMID:27265722

  7. Distortion product otoacoustic emission fine-structure: An insight into the ear asymmetries

    Directory of Open Access Journals (Sweden)

    Bhamini Sharma

    2014-01-01

    Full Text Available Context: Use of distortion product otoacoustic emission (DPOAE as a measure of hearing sensitivity is common in clinical practice. However, use of a more informative DPOAE fine-structure has been limited due to non-reliability of DPOAE fine-structure. Aim: The current study was aimed at testing the interaural differences between the DPOAE fine-structure across three age groups. Settings and Design: Acoustically treated room with a calibrated dual channel audiometer (Orbiter 922 along with TDH-39 headphones and B-71 bone vibrator. GSI Tympstar was used for tympanometry and acoustic reflex measurements while ′ILO V6′ OAE analyzer was used for recording of DPOAE and DPOAE fine-structure. Material and Methods : A total of 98 subjects with normal peripheral hearing sensitivity were tested for DPOAE fine-structure. The three age groups consisted of young (8-18 years; n = 50, middle aged (30-40 years; n = 30, and elderly (50-60 years; n = 18. DPOAE fine-structure was studied at 8 points per octave on a total of 25 frequencies from 1000 to 8000 Hz. Statistical Analysis Used: Repeated measure analysis of variance. Results: There was a significant difference (P < 0.05 in the amplitudes at frequencies between 2000 and 3000 Hz. This was evident irrespective of the age groups. There was also a decrease in DPOAE amplitude in elderly group. Conclusions: Interaural asymmetry can be attributed as a reason to these findings and it occurred mostly in the speech perception frequencies. Reduced amplitude of DPAOE in the elderly group can be attributed to presbycusis.

  8. Contralateral acoustic suppression of transient evoked otoacoustic emissions: Activation of the medial olivocochlear system

    Directory of Open Access Journals (Sweden)

    Komazec Zoran

    2003-01-01

    Full Text Available Medial olivocochlear pathway represents the final part of efferent acoustic pathway which comes from the superior olivary complex ending at outer hair cells. Activation of medial olivocochlear system (MOCS alters the cochlear output decreasing the travelling wave within cochlea. Stimulation of MOCS provides protection against moderate levels of noise, encoding noise signals as well as selecting hearing attention. Activation of MOCS can be performed using contralateral acoustic stimulation. The principal result of presentation of contralateral acoustic stimulation during screening of transient evoked otoacoustic emission (TEOAE is an attenuation of the TEOAE amplitude. Thirty-eight ears were examined in this study: twenty-eight ears from 14 normal-hearing adults and 10 patients with unilateral deafness. Healthy subjects were exposed to contralateral broad-band noise of various intensities (40, 30, 20 and 10 dB SL, as well as 30 dB SL pure tone stimulation (1 kHz and 4 kHz. A decrease of TEOAE amplitudes during contralateral stimulation with 40 and 30 dB SL broad-band noise and pure tones was established. This effect was a result of MOCS activation. A greater intensity of contralateral stimulation evoked greater decrease of TEOAE amplitude; stimulation with broad-band noise caused greater attenuation than with pure tone stimulation. Contralateral stimulation of deaf ears in the group with unilateral deafness was also performed. Statistically significant difference between TEOAE amplitude before and during contralateral stimulation was not established. This circumstance explains that activation of MOCS and consequent reduction of outer hair cells motility is very possibly caused by contralateral acoustic stimulation. Apart from studying physiological significance of efferent auditory system, results of this and similar studies can be used for production of hearing aids improving speech discrimination in noisy environment.

  9. Mechanical tuning of the moth ear: distortion-product otoacoustic emissions and tympanal vibrations.

    Science.gov (United States)

    Mora, Emanuel C; Cobo-Cuan, Ariadna; Macías-Escrivá, Frank; Pérez, Martha; Nowotny, Manuela; Kössl, Manfred

    2013-10-15

    The mechanical tuning of the ear in the moth Empyreuma pugione was investigated by distortion-product otoacoustic emissions (DPOAE) and laser Doppler vibrometry (LDV). DPOAE audiograms were assessed using a novel protocol that may be advantageous for non-invasive auditory studies in insects. To evoke DPOAE, two-tone stimuli within frequency and level ranges that generated a large matrix of values (960 frequency-level combinations) were used to examine the acoustic space in which the moth tympanum shows its best mechanical and acoustical responses. The DPOAE tuning curve derived from the response matrix resembles that obtained previously by electrophysiology, and is V-shaped and tuned to frequencies between 25 and 45 kHz with low Q10dB values of 1.21±0.26. In addition, while using a comparable stimulation regime, mechanical distortion in the displacement of the moth's tympanal membrane at the stigma was recorded with a laser Doppler vibrometer. The corresponding mechanical vibration audiograms were compared with DPOAE audiograms. Both types of audiograms have comparable shape, but most of the mechanical response fields are shifted towards lower frequencies. We showed for the first time in moths that DPOAE have a pronounced analogy in the vibration of the tympanic membrane where they may originate. Our work supports previous studies that point to the stigma (and the internally associated transduction machinery) as an important place of sound amplification in the moth ear, but also suggests a complex mechanical role for the rest of the transparent zone. PMID:23868848

  10. Stimulus Frequency Otoacoustic Emission Delays and Generating Mechanisms in Guinea Pigs, Chinchillas, and Simulations.

    Science.gov (United States)

    Berezina-Greene, Maria A; Guinan, John J

    2015-12-01

    According to coherent reflection theory (CRT), stimulus frequency otoacoustic emissions (SFOAEs) arise from cochlear irregularities coherently reflecting energy from basilar membrane motion within the traveling-wave peak. This reflected energy arrives in the ear canal predominantly with a single delay at each frequency. However, data from humans and animals indicate that (1) SFOAEs can have multiple delay components, (2) low-frequency SFOAE delays are too short to be accounted for by CRT, and (3) "SFOAEs" obtained with a 2nd ("suppressor") tone ≥2 octaves above the probe tone have been interpreted as arising from the area basal to the region of cochlear amplification. To explore these issues, we collected SFOAEs by the suppression method in guinea pigs and time-frequency analyzed these data, simulated SFOAEs, and published chinchilla SFOAEs. Time-frequency analysis revealed that most frequencies showed only one SFOAE delay component while other frequencies had multiple components including some with short delays. We found no systematic patterns in the occurrence of multiple delay components. Using a cochlear model that had significant basilar membrane motion only in the peak region of the traveling wave, simulated SFOAEs had single and multiple delay components similar to the animal SFOAEs. This result indicates that multiple components (including ones with short delays) can originate from cochlear mechanical irregularities in the SFOAE peak region and are not necessarily indicative of SFOAE sources in regions ≥2 octaves basal of the SFOAE peak region. We conclude that SFOAEs obtained with suppressors close to the probe frequency provide information primarily about the mechanical response in the region that receives amplification, and we attribute the too-short SFOAE delays at low frequencies to distortion-source SFOAEs and coherent reflection from multiple cochlear motions. Our findings suggest that CRT needs revision to include reflections from multiple

  11. Audiologic and otoacoustic emission evaluation in individuals exposed to noise and plaguecides

    Directory of Open Access Journals (Sweden)

    Morini, Renata Graziele

    2009-09-01

    Full Text Available Introduction: The noise induced hearing loss (NIHL has been studied for many years and today the specialized literature also studies the synergic action of chemicals. Objective: To research the audiologic findings and DPOAE in workers exposed to occupational noise and plaguecides and to compare them with data obtained in individuals without exposure to these harmful elements. Method: 51 individuals were evaluated (102 ears, divided into three groups. Group I was composed by 17 workers with exposure to noise and plaguecides, all with neurosensorial auditory loss; group II was composed by 17 workers with exposure to noise and plaguecides with audiometric thresholds within normality standards (up to 25 dBNA and group III by 17 healthy individuals without auditory alterations and without exposure to noise and plaguecides, control group. Results: In the audiologic anamnesis, as for groups I and II, we observed that the main auditory complaints presented by the workers were those of recruitment (29.5%, tinnitus (26.5%, allergy (23.5% and arterial hypertension (12%. The findings of the audiometry appointed that the research's individuals did not present with auditory losses in the frequencies of 500 Hz, 1 and 2 kHz, the losses occurred in the frequencies of 3 and 8 kHz. As for the distortion-product otoacoustic emissions (DPOAEs, we observed that the individuals in group III had a major incidence of responses when compared to those of groups I and II. Conclusion: The results analysis allowed us to conclude that the DPOAE test represents an important tool for follow up and prevention of NIHL.

  12. Distortion product otoacoustic emissions in college music majors and nonmusic majors.

    Science.gov (United States)

    Henning, Rebecca L Warner; Bobholz, Kate

    2016-01-01

    The presence and absence of distortion product otoacoustic emissions (DPOAEs) as well as DPOAE amplitudes were compared between college music majors and a control group of nonmusic majors. Participants included 28 music majors and 35 nonmusic majors enrolled at a university with ages ranging from 18-25 years. DPOAEs and hearing thresholds were measured bilaterally on all the participants. DPOAE amplitudes were analyzed at the following f2 frequencies: 1,187 Hz, 1,500 Hz, 1,906 Hz, 2,531 Hz, 3,031 Hz, 3812 Hz, 4,812 Hz, and 6,031 Hz. Significantly more music majors (7/28) than nonmusic majors (0/35) exhibited absent DPOAEs for at least one frequency in at least one ear. Both groups of students reported similar histories of recreational and occupational noise exposures that were unrelated to studying music, and none of the students reported high levels of noise exposure within the previous 48 h. There were no differences in audiometric thresholds between the groups at any frequency. At DPOAE f2 frequencies from 3,031 Hz to 6,031 Hz, nonsignificantly lower amplitudes of 2-4 dB were seen in the right ears of music majors versus nonmajors, and in the right ears of music majors playing brass instruments compared to music majors playing nonbrass instruments. Given the greater prevalence of absent DPOAEs in university music majors compared to nonmusic majors, it appears that early stages of cochlear damage may be occurring in this population. Additional research, preferably longitudinal and across multiple colleges/universities, would be beneficial to more definitively determine when the music students begin to show signs of cochlear damage, and to identify whether any particular subgroups of music majors are at a greater risk of cochlear damage.

  13. Distortion product otoacoustic emissions in college music majors and nonmusic majors

    Directory of Open Access Journals (Sweden)

    Rebecca L. Warner Henning

    2016-01-01

    Full Text Available The presence and absence of distortion product otoacoustic emissions (DPOAEs as well as DPOAE amplitudes were compared between college music majors and a control group of nonmusic majors. Participants included 28 music majors and 35 nonmusic majors enrolled at a university with ages ranging from 18-25 years. DPOAEs and hearing thresholds were measured bilaterally on all the participants. DPOAE amplitudes were analyzed at the following f2 frequencies: 1,187 Hz, 1,500 Hz, 1,906 Hz, 2,531 Hz, 3,031 Hz, 3812 Hz, 4,812 Hz, and 6,031 Hz. Significantly more music majors (7/28 than nonmusic majors (0/35 exhibited absent DPOAEs for at least one frequency in at least one ear. Both groups of students reported similar histories of recreational and occupational noise exposures that were unrelated to studying music, and none of the students reported high levels of noise exposure within the previous 48 h. There were no differences in audiometric thresholds between the groups at any frequency. At DPOAE f2 frequencies from 3,031 Hz to 6,031 Hz, nonsignificantly lower amplitudes of 2-4 dB were seen in the right ears of music majors versus nonmajors, and in the right ears of music majors playing brass instruments compared to music majors playing nonbrass instruments. Given the greater prevalence of absent DPOAEs in university music majors compared to nonmusic majors, it appears that early stages of cochlear damage may be occurring in this population. Additional research, preferably longitudinal and across multiple colleges/universities, would be beneficial to more definitively determine when the music students begin to show signs of cochlear damage, and to identify whether any particular subgroups of music majors are at a greater risk of cochlear damage.

  14. Distortion product otoacoustic emissions in college music majors and nonmusic majors.

    Science.gov (United States)

    Henning, Rebecca L Warner; Bobholz, Kate

    2016-01-01

    The presence and absence of distortion product otoacoustic emissions (DPOAEs) as well as DPOAE amplitudes were compared between college music majors and a control group of nonmusic majors. Participants included 28 music majors and 35 nonmusic majors enrolled at a university with ages ranging from 18-25 years. DPOAEs and hearing thresholds were measured bilaterally on all the participants. DPOAE amplitudes were analyzed at the following f2 frequencies: 1,187 Hz, 1,500 Hz, 1,906 Hz, 2,531 Hz, 3,031 Hz, 3812 Hz, 4,812 Hz, and 6,031 Hz. Significantly more music majors (7/28) than nonmusic majors (0/35) exhibited absent DPOAEs for at least one frequency in at least one ear. Both groups of students reported similar histories of recreational and occupational noise exposures that were unrelated to studying music, and none of the students reported high levels of noise exposure within the previous 48 h. There were no differences in audiometric thresholds between the groups at any frequency. At DPOAE f2 frequencies from 3,031 Hz to 6,031 Hz, nonsignificantly lower amplitudes of 2-4 dB were seen in the right ears of music majors versus nonmajors, and in the right ears of music majors playing brass instruments compared to music majors playing nonbrass instruments. Given the greater prevalence of absent DPOAEs in university music majors compared to nonmusic majors, it appears that early stages of cochlear damage may be occurring in this population. Additional research, preferably longitudinal and across multiple colleges/universities, would be beneficial to more definitively determine when the music students begin to show signs of cochlear damage, and to identify whether any particular subgroups of music majors are at a greater risk of cochlear damage. PMID:26780957

  15. Distortion product otoacoustic emissions in college music majors and nonmusic majors

    Science.gov (United States)

    Henning, Rebecca L. Warner; Bobholz, Kate

    2016-01-01

    The presence and absence of distortion product otoacoustic emissions (DPOAEs) as well as DPOAE amplitudes were compared between college music majors and a control group of nonmusic majors. Participants included 28 music majors and 35 nonmusic majors enrolled at a university with ages ranging from 18-25 years. DPOAEs and hearing thresholds were measured bilaterally on all the participants. DPOAE amplitudes were analyzed at the following f2 frequencies: 1,187 Hz, 1,500 Hz, 1,906 Hz, 2,531 Hz, 3,031 Hz, 3812 Hz, 4,812 Hz, and 6,031 Hz. Significantly more music majors (7/28) than nonmusic majors (0/35) exhibited absent DPOAEs for at least one frequency in at least one ear. Both groups of students reported similar histories of recreational and occupational noise exposures that were unrelated to studying music, and none of the students reported high levels of noise exposure within the previous 48 h. There were no differences in audiometric thresholds between the groups at any frequency. At DPOAE f2 frequencies from 3,031 Hz to 6,031 Hz, nonsignificantly lower amplitudes of 2-4 dB were seen in the right ears of music majors versus nonmajors, and in the right ears of music majors playing brass instruments compared to music majors playing nonbrass instruments. Given the greater prevalence of absent DPOAEs in university music majors compared to nonmusic majors, it appears that early stages of cochlear damage may be occurring in this population. Additional research, preferably longitudinal and across multiple colleges/universities, would be beneficial to more definitively determine when the music students begin to show signs of cochlear damage, and to identify whether any particular subgroups of music majors are at a greater risk of cochlear damage. PMID:26780957

  16. Sex differences in distortion product otoacoustic emissions as a function of age in CBA mice.

    Science.gov (United States)

    Guimaraes, Patricia; Zhu, Xiaoxia; Cannon, Trinitia; Kim, SungHee; Frisina, Robert D

    2004-06-01

    Age-related hearing loss--presbycusis--is the number one communication problem of the aged. A major contributor to presbycusis is the progressive degeneration of cochlear outer hair cells (OHCs). Distortion product otoacoustic emissions (DPOAEs) are effective in vivo, physiological measures of hearing, assessing the health and functioning of the OHCs in mammals. We and others have previously demonstrated that DPOAE amplitudes decline with age in humans and mice. The present study's objective was to measure age-related declines in the OHCs in CBA mice (slow, progressive age-related hearing loss) by comparing DPOAEs and auditory brainstem responses (ABRs) generated from females and males. Young adult (2.1-2.9 months) and middle-aged CBA (14.0-16.4 months) mice were tested, as well as old CBAs (24.3-29.0 months). DPOAE-grams were obtained with L1 = 65 and L2 = 50 dB SPL, f1/f2 = 1.25, using eight points per octave covering a frequency range from 5.6 to 44.8 kHz (geometric mean frequency). ABRs ranged from 3 to 48 kHz. Analyses revealed that DPOAE levels decreased with age for middle-aged and old male CBAs, but for female CBAs, declines did not occur until old age - after menopause. In contrast, ABR amplitudes for female and male young adult and middle-aged CBAs were the same. Female ABR thresholds were lower than males for old CBAs. In conclusion, we discovered that pre-menopausal CBA female mice have healthier OHCs relative to middle-aged males, but much of this relative advantage is lost post-menopause. Understanding sex differences in age-related sensory disorders will be quite helpful for the goals of preventing, slowing or curing sensory problems in old age for both women and men.

  17. Using a third tone to probe the physiological generation site of distortion product otoacoustic emissions in gerbil

    Science.gov (United States)

    Dong, Wei

    2015-12-01

    The generation of distortion product otoacoustic emissions (DPOAEs) has been summarized using a two-mechanism theory consisting of nonlinear distortion and linear coherent reflection. However, the precise generation site in the cochlea is still unclear. The current study in gerbils used a third tone in different cochlear regions to probe the cochlear origin site of DPOAEs. DPOAEs and their intracochlear sources, distortion products (DPs), were simultaneously measured. Our results suggest that the major generation site of DPOAEs evoked by an f2/f1 ratio of 1.25 extends basal to the primary f2 place, which is consistent with notions about the location of the cochlear amplifier.

  18. Comparing Distortion Product Otoacoustic Emissions to Intracochlear Distortion Products Inferred from a Noninvasive Assay.

    Science.gov (United States)

    Martin, Glen K; Stagner, Barden B; Dong, Wei; Lonsbury-Martin, Brenda L

    2016-08-01

    The behavior of intracochlear distortion products (iDPs) was inferred by interacting a probe tone (f3) with the iDP of interest to produce a "secondary" distortion product otoacoustic emission termed DPOAE(2ry). Measures of the DPOAE(2ry) were then used to deduce the properties of the iDP. This approach was used in alert rabbits and anesthetized gerbils to compare ear-canal 2f1-f2 and 2f2-f1 DPOAE f2/f1 ratio functions, level/phase (L/P) maps, and interference-response areas (IRAs) to their simultaneously collected DPOAE(2ry) counterparts. These same measures were also collected in a human volunteer to demonstrate similarities with their laboratory animal counterparts and their potential applicability to humans. Results showed that DPOAEs and inferred iDPs evidenced distinct behaviors and properties. That is, DPOAE ratio functions elicited by low-level primaries peaked around an f2/f1 = 1.21 or 1.25, depending on species, while the corresponding inferred iDP ratio functions peaked at f2/f1 ratios of ~1. Additionally, L/P maps showed rapid phase variation with DPOAE frequency (fdp) for the narrow-ratio 2f1-f2 and all 2f2-f1 DPOAEs, while the corresponding DPOAE(2ry) measures evidenced relatively constant phases. Common features of narrow-ratio DPOAE IRAs, such as large enhancements for interference tones (ITs) presented above f2, were not present in DPOAE(2ry) IRAs. Finally, based on prior experiments in gerbils, the behavior of the iDP directly measured in intracochlear pressure was compared to the iDP inferred from the DPOAE(2ry) and found to be similar. Together, these findings are consistent with the notion that under certain conditions, ear-canal DPOAEs provide poor representations of iDPs and thus support a "beamforming" hypothesis. According to this concept, distributed emission components directed toward the ear canal from the f2 and basal to f2 regions can be of differing phases and thus cancel, while these same components directed toward fdp add in

  19. The Effect of Acute Otitis Media on Transient Otoacoustic Emissions A Clinical Guide to Successful Treatment Course

    Directory of Open Access Journals (Sweden)

    A. Bayat

    Full Text Available Introduction & Objective: Acute otitis media (AOM is the most common causes of acquired hearing loss in children with increasing incidence. In young children the diagnosis is restricted to otoscopy and tympanometry whereas evaluation of the auditory function is impossible due to noncompliance during pure tone audiometry. For this purpose, measurement of otoacoustic emissions, especially transient evoked ones (TEOAEs, can be applied. The aim of this study was to evaluate the effect of AOM on TEOAEs in young children before and after treatment course.Material & Methods: In an analytic, cross-sectional design, 42 young children with AOM, both sexes, aged 2 to 4.5 years were evaluated through tympanometry and transient otoacoustic emissions (TEOAEs. TEOAEs signal to noise ratio (SNR and reproducibility of AOM patients were compared before, two weeks and six weeks after the treatment course. Then AOM responses were compared with an age-matched control group. The results were analyzed using SPSS 16.Results: Our findings revealed that TEOAE parameters in AOM subjects were the most affected on highest frequencies. Significant changes of TEOAE parameters were found 2 weeks after the treatment with further improvement 6 weeks after the treatment course (P 0.05.Conclusion: The results of this study suggest that there was an improvement in TEOAE SNR and band reproducibility in serial TEOAEs measurements. Thus,application of TEOAEs is a beneficial method to follow up medical treatment in young children with AOM. (Sci J Hamadan Univ Med Sci 2011;18(3:17-21

  20. Effects of the depth of anesthesia on distortion product otoacoustic emissions.

    Science.gov (United States)

    Ropposch, Thorsten; Walch, Christian; Avian, Alexander; Mausser, Gerlinde; Spary, Manuela

    2014-11-01

    To analyze the effects of the depth of anesthesia on inner ear function measured with distortion product otoacoustic emissions (DPOAEs) at 2f 1 - f 2. Thirty patients who underwent tonsillectomy under general anesthesia (GA) were included. Patients were assigned randomly to one of two groups: group 1 (n = 15) received propofol, group 2 (n = 15) sevoflurane as anesthetic agent. The sedation level was assessed by the bispectral index system. DPOAE measurements were performed before premedication (T 1), 5 min after premedication (T 2), 3 min after induction of general anesthesia (T 3) and every 10 min (T 4, T 5) thereafter until the end of surgery at about 23 min post-anesthetic induction, while sedation levels were obtained starting at the beginning until the end of anesthesia. After premedication, both blood oxygen saturation and heart rate decreased. Following induction of anesthesia systolic and diastolic blood pressure decreased, while, as expected, the level of sedation increased. Analyzing the propofol and sevoflurane group separately, both groups showed comparable overall courses of DPOAE levels at higher frequencies (2.8 kHz p = 0.310, 4 kHz p = 0.193, 6 kHz p = 0.269, 8 kHz p = 0.223) and no changes of DPOAE levels compared with baseline values were observed. At T5 the 1 kHz DPOAE level increased in the propofol group and slightly decreased in the sevoflurane group (p < 0.001). While the 1.4 kHz DPOAE level in the propofol group did not change over time the 1.4 kHz DPOAE level decreased in the sevoflurane group (baseline to T 4 p = 0.045; Baseline to T 5 p = 0.004). While overall there were different courses between these two groups in the 2 kHz DPOAE level, in the post hoc analysis only a tendency in the change from baseline to T 4 could be observed (p = 0.082). These results indicate that while the amplitudes of certain DPOAEs were influenced by GA, the depth of anesthesia had no effect on this measure of cochlear function in clinical routine. Therefore

  1. [New method for analysis and visualization of the fine temporal structure of the transient evoked otoacoustic emission signal].

    Science.gov (United States)

    Belov, O A; Alekseeva, N N; Tavartkiladze, G A

    2014-01-01

    We have developed the new method for the analysis and visualization of the fine temporal structure of the transient evoked otoacoustic emission signal. The method consists of the presentation of the signal in the form of a set of tone components with a rapidly changing amplitude and relatively stable frequency. It is based on the combination of three spectrograms differing in frequency and temporal resolution by means of fuzzy logic amplitude estimation with subsequent frequency refining with the use of the least square procedure, reduction of the number of the insignificant components, and final re-ordering of the results for the simplification of further data processing. The new method was named Pitch Envelope Analysis (PEA). For data representation, a new type of diagram named componentogram was designed. The proposed method can be used for the real time processing of the continuous data stream especially for speech processing.

  2. Consequences of outer hair cell damage for otoacoustic emissions and audio-vocal feedback in the mustached bat.

    Science.gov (United States)

    Kössl, M; Vater, M

    2000-12-01

    The cochlea of the mustached bat is adapted to process ultrasonic echolocation signals. To assess the involvement of active sound amplification by outer hair cells in high-frequency hearing and in audio-vocal interaction, selective hair cell damage was induced by the antibiotic Amikacin. Amikacin preferentially damaged the first row of outer hair cells in the basal cochlear turn. The cochlear regions coding for the second-harmonic constant-frequency component of the echolocation call (CF2) at 61 kHz and for frequencies between 75 and 100 kHz were the most affected. This was reflected in an increase of mechanical thresholds obtained by measuring distortion-product otoacoustic emissions. During initial periods of minor hair cell damage, when thresholds had deteriorated by less than 40 dB, a sharp, mechanical, cochlear resonance that is responsible for enhanced tuning to 61 kHz was still measurable as a stimulus-frequency otoacoustic emission and its frequency decreased by 350 Hz. The persistence of the resonance suggests that passive structures like the tectorial or basilar membrane are important for generation of the resonance. Behaviorally, the bats reacted to the change in cochlear micromechanics with a decrease of their CF2 frequency by 360 Hz. After larger hair cell damage, when the cochlear resonance had disappeared, the bats vocalized only sparsely and the CF2 frequency increased by up to 2 kHz, which may correspond to a state without audiovocal feedback. This indicates that audio-vocal feedback in the nondamaged animal works to lower the call frequency. PMID:11547810

  3. Effects of age on contralateral suppression of distortion product otoacoustic emissions in human listeners with normal hearing.

    Science.gov (United States)

    Kim, SungHee; Frisina, D Robert; Frisina, Robert D

    2002-01-01

    The auditory efferent system presumably plays a role in enhancing signals in noise and, in particular, speech perception in background noise. This study measured the age-related changes of the medial olivocochlear (MOC) system by comparing distortion product otoacoustic emissions (DPOAEs) with and without contralateral white noise stimulation. Otoacoustic emissions were typically reduced in level (magnitude) when white noise was presented to the contralateral ear. This contralateral suppression (CS) is attributed to activation of the MOC system, which has an inhibitory effect on the outer hair cell (OHC) system. By studying CS on cochlear output in human listeners of different ages, it is possible to describe aging effects on the MOC system. Human subjects were young adult, middle aged and old (n = 10/group). All subjects had normal hearing and middle-ear function based upon standard audiometric criteria. The present study recorded 2f(1)-f(2) DPOAE-grams in response to moderate primary tones (L1 = 75, L2 = 65 dB SPL), from 1 to 6.3 kHz. The principal findings were that DPOAE levels were smaller in the old compared to the young group and that CS declined with age for the middle-aged and old groups. In addition, CS in the 1- to 2-kHz range was greater than in the 4- to 6-kHz range for all ages, but especially for the old group. These findings suggest that a functional decline of the MOC system with age precedes OHC degeneration. Moreover, the MOC system maintains better function in the 1- to 2-kHz range than in the 4- to 6-kHz range as a function of age.

  4. Efeito da acupuntura sobre as emissões otoacústicas de pacientes com zumbido Impact of acupuncture on otoacoustic emissions in patients with tinnitus

    Directory of Open Access Journals (Sweden)

    Renata Frasson de Azevedo

    2007-10-01

    Full Text Available O tratamento do zumbido continua a ser um desafio da atualidade. Na medicina tradicional chinesa, a acupuntura é recomendada para o alívio do zumbido, apesar de faltarem provas cientificas nesta área. OBJETIVO: Verificar o efeito da acupuntura sobre a função coclear de indivíduos com zumbido através do uso das emissões otoacústicas. CASUÍSTICA E MÉTODO: Foi realizado um estudo clínico-prospectivo, no qual foram avaliados 38 pacientes do ambulatório de zumbido. Os pacientes foram avaliados por meio de emissões otoacústicas transitórias e pela medida da supressão das emissões otoacústicas transitórias. Essa avaliação foi realizada antes e após a aplicação de acupuntura em um ponto na região têmporo-parietal, correspondente à área cócleo-vestibular (no grupo intervenção 1 n=19 e em um ponto 3cm acima dessa região (para o grupo intervenção 2 n=19. RESULTADOS: Os resultados mostraram uma diferença estatisticamente significante na amplitude das emissões otoacústicas antes e após a aplicação da acupuntura para o grupo intervenção 1. Não foram observadas diferenças para o grupo intervenção 2. CONCLUSÃO: Os resultados sugerem que houve um efeito da acupuntura sobre as emissões otoacústicas dos pacientes com zumbido.The treatment of tinnitus is still a challenge. Acupuncture is recommended for the relief of tinnitus in traditional Chinese Medicine, although scientific evidence is lacking. AIM: The aim of this study was to assess the effect of acupuncture on the cochlear function in patients with tinnitus by analyzing otoacoustic emissions. METHODS: Thirty eight patients with tinnitus were included in the prospective clinical study. Measures of transitory otoacoustic emissions and suppression of otoacoustic emissions were obtained from all subjects before and after acupuncture. Patients were assigned to one of two groups: intervention group 1 (n=19, in which needle acupuncture was applied at the

  5. Low-frequency tone-pip-evoked otoacoustic emissions originate over a broad cochlear region in chinchillas

    Science.gov (United States)

    Charaziak, Karolina K.; Siegel, Jonathan H.

    2015-12-01

    Otoacoustic emissions evoked with transient sounds (TEOAEs) are believed to originate within the tonotopic region of the stimulus in the cochlea via the same mechanisms as emissions evoked with single tones. However, we found that emissions evoked by low frequency ( 6 mm) in chinchillas (Charaziak and Siegel, 2014, ARO Abst., 119). Here we test whether a broad region of generation for low-frequency stimuli is also a characteristic of TEOAEs evoked with 1-kHz tone pips extracted with compression and suppression methods. The TEOAE could be revealed with moderate level suppressors with frequencies extending beyond the stimulus bandwidth (up to 12.1 kHz), with the largest responses obtained with 3.1 - 4.1 kHz suppressors. There was a consistent decline in group delays of suppressor-revealed TEOAEs with increasing suppressor frequency, as expected if higher-frequency suppressors acted on more basal TEOAE generators. Effects of mid- to high-frequency acoustic trauma on TEOAE levels confirm the notion that the suppressors interact with emission components arising near the tonotopic place of the suppressor.

  6. [Neonatal deafness screening with the evoked otoacoustic emissions technique. Study of 320 newborns at the neonatal resuscitation service of the Amiens neonatal care unit].

    Science.gov (United States)

    Ayache, S; Kolski, C; Stramandinoli, E; Leke, A; Krim, G; Strunski, V

    2001-04-01

    Between January 1997 and June 1999, we screened for hearing loss using evoked otoacoustic emissions in 320 newborns in the neonate intensive care unit at the Amiens University Hospital. The purpose of this study was to search for correlations between deafness and one of the hearing loss risk factors identified by the Joint Committee on Infant Screening. Three risk factors were found to be significant: craniofacial abnormalities, low birth weight (less than 1500 g) and a familial history of hearing loss. Unfortunately a large proportion of the infants were lost to follow-up. Evoked otoacoustic emission provide an excellent screening technique for hearing loss in newborns. Such screening implies however the creation of networks to assure patient follow-up.

  7. Absent otoacoustic emissions predict otitis media in young Aboriginal children: A birth cohort study in Aboriginal and non-Aboriginal children in an arid zone of Western Australia

    OpenAIRE

    Stokes Annette; Finucane Janine; Elsbury Dimity; Jacoby Peter; Weeks Sharon; Lehmann Deborah; Monck Ruth; Coates Harvey

    2008-01-01

    Abstract Background Otitis media (OM) is the most common paediatric illness for which antibiotics are prescribed. In Australian Aboriginal children OM is frequently asymptomatic and starts at a younger age, is more common and more likely to result in hearing loss than in non-Aboriginal children. Absent transient evoked otoacoustic emissions (TEOAEs) may predict subsequent risk of OM. Methods 100 Aboriginal and 180 non-Aboriginal children in a semi-arid zone of Western Australia were followed ...

  8. Distortion-product otoacoustic emissions in middle-aged subjects with normal versus potentially presbyacusic high-frequency hearing loss.

    Science.gov (United States)

    Nieschalk, M; Hustert, B; Stoll, W

    1998-01-01

    Distortion-product otoacoustic emissions (DPOAEs) are still undergoing evaluation for clinical use. Although the effects of ageing on otoacoustic emissions have been studied quite extensively in the past, DPOAE response-growth or input-output (I-O) measures, which are well suited as an objective method for monitoring cochlear function at specific frequencies, have been less thoroughly examined. The aim of the present study was to assess the 2f1-f2 DPOAEs in a clinical setting in order to examine the response of 20 normally hearing middle-aged adults and to compare the results with those of 20 people of the same age with ears of sensorineural high-frequency hearing loss (HL). The experiment consisted of two stages. First, the DPOAE-gram was recorded in 1-4-octave steps at a stimulus level of 70 dB SPL over a frequency range of the f2 primary tone which extended from 1.001 to 6.299 kHz. Secondly, in order to elicit DPOAE I-O functions, the two primary stimuli were presented at equilevel intensities ranging from 20 to 71 dB SPL. The stimulus-level step size was 3 dB. The I-O functions were recorded at five separate DPOAE frequencies, with the f2 frequency most closely related to the clinical audiogram (f2 = 1.0, 1.5, 2.0, 4.0 and 6.0 kHz). Two clearly separated portions in the form of the I-O function for normally hearing ears were found. The first portion, in response to primary levels of 60 dB SPL and below, showed a plateau (saturating) behaviour. If primary levels exceeded 60 dB SPL, I-O functions became more linear. The attenuation of the saturation portion of the I-O function in ears with high-frequency HL across the frequency-test range is difficult to explain because elevated behavioural thresholds were observed only for frequencies > 1.5 kHz. Thus, the more linear I-Os associated with the hearing-loss frequencies may indicate deficiencies in the active properties of outer hair cells (OHCs), whereas those for I-Os signal processing and in the passive

  9. Lack of contralateral suppression in transient-evoked otoacoustic emissions in multiple chemical sensitivity: a clinical correlation study.

    Science.gov (United States)

    Micarelli, Alessandro; Viziano, Andrea; Genovesi, Giuseppe; Bruno, Ernesto; Ottaviani, Fabrizio; Alessandrini, Marco

    2016-01-01

    Multiple chemical sensitivity (MCS) is a chronic disorder characterized by a variety of symptoms associated with the exposure to chemicals at a concentration below the toxic level. Previous studies have demonstrated peculiar responses in brain activity in these patients with respect to sensory stimuli while the association between chemical sensitivity and other environmental intolerances such as noise sensitivity has been questioned by researchers. In this study, a cohort of 18 MCS patients underwent transient-evoked otoacoustic emission (TEOAE) testing with and without contralateral suppression to evaluate the functionality of the medial olivocochlear (MOC) reflex involved in speech-in-noise sensitivity. Results were compared with an age- and gender-matched control group (n = 20) and correlation analysis with disease onset and quick environmental exposure sensitivity inventory (qEESI) symptom severity scale was performed. Subjects affected by MCS showed statistically significant impairment of MOC reflex, and the onset of the disease and several symptom subscales showed to be correlated to such reduction in some of the frequencies tested. These data suggest that alterations of MOC reflex could be part of the complex features of this disease although more studies are needed to further explore auditory perception disorders in environmental intolerances. PMID:27157687

  10. Lack of contralateral suppression in transient-evoked otoacoustic emissions in multiple chemical sensitivity: a clinical correlation study

    Directory of Open Access Journals (Sweden)

    Alessandro Micarelli

    2016-01-01

    Full Text Available Multiple chemical sensitivity (MCS is a chronic disorder characterized by a variety of symptoms associated with the exposure to chemicals at a concentration below the toxic level. Previous studies have demonstrated peculiar responses in brain activity in these patients with respect to sensory stimuli while the association between chemical sensitivity and other environmental intolerances such as noise sensitivity has been questioned by researchers. In this study, a cohort of 18 MCS patients underwent transient-evoked otoacoustic emission (TEOAE testing with and without contralateral suppression to evaluate the functionality of the medial olivocochlear (MOC reflex involved in speech-in-noise sensitivity. Results were compared with an age- and gender-matched control group (n = 20 and correlation analysis with disease onset and quick environmental exposure sensitivity inventory (qEESI symptom severity scale was performed. Subjects affected by MCS showed statistically significant impairment of MOC reflex, and the onset of the disease and several symptom subscales showed to be correlated to such reduction in some of the frequencies tested. These data suggest that alterations of MOC reflex could be part of the complex features of this disease although more studies are needed to further explore auditory perception disorders in environmental intolerances.

  11. Comparison between distortion product otoacoustic emissions and nerve fiber responses from the basilar papilla of the frog

    Science.gov (United States)

    Meenderink, Sebastiaan W. F.; van Dijk, Pim; Narins, Peter M.

    2005-05-01

    The basilar papilla (BP) is one of the three end organs in the frog inner ear that is sensitive to airborne sound. Its anatomy and physiology are unique among all classes of vertebrates. Essentially, the BP functions as a single auditory filter presumably arising from a mechanically-tuned mechanism. As such, both neural and distortion product otoacoustic emission (DPOAE) tuning may reflect a single mechanical filtering mechanism. Using the Duffing oscillator as a simple model for both neural and DPOAE tuning from the BP, two predictions can be made: [1] the characteristic frequency (CF) of neural tuning and the best frequency (BF) of DPOAE tuning will coincide and [2] the neural tuning curve and DPOAE-audiogram have a similar shape when the neural tuning curve is scaled by a factor of 4 along the y-axis. We recorded both neural tuning curves and DPOAE-audiograms from the BP of the leopard frog. These recordings show good agreement with the model predictions when the stimulus tones are related by relatively small stimulus frequency ratios. For larger stimulus frequency ratios, DPOAE recordings clearly deviate from model predictions. These differences are most likely caused by the oversimplified representation of the frog BP by the model. .

  12. Contralateral suppression of distortion product otoacoustic emissions and the middle-ear muscle reflex in human ears.

    Science.gov (United States)

    Sun, Xiao-Ming

    2008-03-01

    Distortion product otoacoustic emissions (DPOAEs) were measured in the absence and presence of contralateral noise at five levels--below, equal to, and above the middle-ear muscle (MEM) reflex threshold. The resultant changes in DPOAE level and phase were dependent on stimulus frequency and noise level. Both low-level noise, believed to elicit the medial olivocochlear (MOC) reflex, and high-level noise, thought to activate both MOC and MEM reflexes, significantly decreased the DPOAE level. However, the shift from sole MOC effect to mixed MOC and MEM effects was not as dramatic as we thought. While low-level noise resulted in a minimum DPOAE phase change, high-level noise caused a substantial phase lead for 1 and 2kHz. With increasing frequency, phase lag became more notable. The present study suggests the following: (1) DPOAE contralateral suppression by low-level sound most likely does not involve the effect of the MEM reflex and signal crossover; and (2) combined analysis of DPOAE level and phase changes warrants further investigations to overcome the difficulty in separating the effects of MOC efferents and MEM contraction. The results also imply that OAE measurement has the potential for being used to investigate the effect of the MEM reflex on sound transmission. PMID:18258398

  13. Relating the variability of tone-burst otoacoustic emission and auditory brainstem response latencies to the underlying cochlear mechanics

    Science.gov (United States)

    Verhulst, Sarah; Shera, Christopher A.

    2015-12-01

    Forward and reverse cochlear latency and its relation to the frequency tuning of the auditory filters can be assessed using tone bursts (TBs). Otoacoustic emissions (TBOAEs) estimate the cochlear roundtrip time, while auditory brainstem responses (ABRs) to the same stimuli aim at measuring the auditory filter buildup time. Latency ratios are generally close to two and controversy exists about the relationship of this ratio to cochlear mechanics. We explored why the two methods provide different estimates of filter buildup time, and ratios with large inter-subject variability, using a time-domain model for OAEs and ABRs. We compared latencies for twenty models, in which all parameters but the cochlear irregularities responsible for reflection-source OAEs were identical, and found that TBOAE latencies were much more variable than ABR latencies. Multiple reflection-sources generated within the evoking stimulus bandwidth were found to shape the TBOAE envelope and complicate the interpretation of TBOAE latency and TBOAE/ABR ratios in terms of auditory filter tuning.

  14. Auditory efferent feedback system deficits precede age-related hearing loss: contralateral suppression of otoacoustic emissions in mice.

    Science.gov (United States)

    Zhu, Xiaoxia; Vasilyeva, Olga N; Kim, Sunghee; Jacobson, Michael; Romney, Joshua; Waterman, Marjorie S; Tuttle, David; Frisina, Robert D

    2007-08-10

    The C57BL/6J mouse has been a useful model of presbycusis, as it displays an accelerated age-related peripheral hearing loss. The medial olivocochlear efferent feedback (MOC) system plays a role in suppressing cochlear outer hair cell (OHC) responses, particularly for background noise. Neurons of the MOC system are located in the superior olivary complex, particularly in the dorsomedial periolivary nucleus (DMPO) and in the ventral nucleus of the trapezoid body (VNTB). We previously discovered that the function of the MOC system declines with age prior to OHC degeneration, as measured by contralateral suppression (CS) of distortion product otoacoustic emissions (DPOAEs) in humans and CBA mice. The present study aimed to determine the time course of age changes in MOC function in C57s. DPOAE amplitudes and CS of DPOAEs were collected for C57s from 6 to 40 weeks of age. MOC responses were observed at 6 weeks but were gone at middle (15-30 kHz) and high (30-45 kHz) frequencies by 8 weeks. Quantitative stereological analyses of Nissl sections revealed smaller neurons in the DMPO and VNTB of young adult C57s compared with CBAs. These findings suggest that reduced neuron size may underlie part of the noteworthy rapid decline of the C57 efferent system. In conclusion, the C57 mouse has MOC function at 6 weeks, but it declines quickly, preceding the progression of peripheral age-related sensitivity deficits and hearing loss in this mouse strain.

  15. Age-related declines in distortion product otoacoustic emissions utilizing pure tone contralateral stimulation in CBA/CaJ mice.

    Science.gov (United States)

    Varghese, George I; Zhu, Xiaoxia; Frisina, Robert D

    2005-11-01

    One role of the medial olivocochlear (MOC) auditory efferent system is to suppress cochlear outer hair cell (OHC) responses when presented with a contralateral sound. Using distortion product otoacoustic emissions (DPOAEs), the effects of active changes in OHC responses due to the MOC as a function of age can be observed when contralateral stimulation with a pure tone is applied. Previous studies have shown that there are age-related declines of the MOC when broad band noise is presented to the contralateral ear. In this study, we measured age-related changes in CBA/CaJ mice by comparing DPOAE generation with and without a contralateral pure tone at three different frequencies (12, 22, and 37 kHz). Young (n = 16), middle (n = 10) and old-aged (n = 10) CBA mice were tested. DPOAE-grams were obtained using L1 = 65 and L2 = 50 dB SPL, F1/F2 = 1.25, using eight points per octave covering a frequency range from 5.6-44.8 kHz. The pure tone was presented contralaterally at 55 dB SPL. DPOAE-grams and ABR levels indicated age-related hearing loss in the old mice. In addition, there was an overall change in DPOAEs in the middle-aged and old groups relative to the young. Pure tone stimulation was not as effective as a suppressor compared to broadband noise. An increase in pure tone frequency from 12 to 22 kHz induced greater suppression of DPOAEs, but the 37 kHz was least effective. These results indicate that as the mouse ages, there are significant changes in the efficiency of the suppression mechanism as elicited by contralateral narrowband stimuli. These findings reinforce the idea that age-related changes in the MOC or the operating points of OHCs play a role in the progression of presbycusis - age-related hearing loss in mammals.

  16. Recovery of distortion product otoacoustic emissions after a 2-kHz monaural sound-exposure in humans: effects on fine structures

    DEFF Research Database (Denmark)

    de Toro, Miguel Angel Aranda; Ordoñez, Rodrigo Pizarro; Reuter, Karen;

    2010-01-01

    A better understanding of the vulnerability of the fine structures of distortion-product otoacoustic emissions (DPOAEs) after acoustic overexposure may improve the knowledge about DPOAE generation, cochlear damage, and lead to more efficient diagnostic tools. It is studied whether the DPOAE fine...... structures of 16 normal-hearing human subjects are systematically affected after a moderate monaural sound-exposure of 10 min to a 2-kHz tone normalized to an exposure level LEX,8h of 80 dBA. DPOAEs were measured before and in the following 70 min after the exposure. The experimental protocol allowed...

  17. Temporary and Permanent Level Shifts in Distortion Product Otoacoustic Emissions following Noise Exposure in an Animal Model

    Directory of Open Access Journals (Sweden)

    M Akbari

    2012-06-01

    Full Text Available Background: Noise-induced hearing loss (NIHL is one of the most common occupational illnesses. Most of the studies on NIHL were conducted at high noise levels that people are rarely exposed to but in industries. The function of the outer hair cells (OHCs is impaired after exposure to industrial noise. Distortion product otoacoustic emissions (DPOAEs are useful in examination of noise-induced level shifts.Objectives: To assess the function of OHCs by DPOAE temporary and permanent level shifts (TLSdp and PLSdp in rabbits exposed to white noise at realistic levels typically found in industrial settings over a broad range of frequencies.Methods: 12 albino rabbits were divided into two groups: the experimental group rabbits which were exposed to 95 dB SPL white noise at 500–8000 Hz for 8 hrs/day for 5 consecutive days, and the control group rabbits with no exposure to noise. The function of OHCs was examined by DPOAE level (Ldp in different occasions. The study groups were compared for DPOAE temporary and permanent level shifts (TLSdp and PLSdp to assess the effect of noise on OHCs function.Results: Noise-induced DPOAE levels (Ldp were decreased up to 20.65 dB (on day 8 and 18.93 dB (on day 11 at 5888.50 Hz (p=0.081. TLSdp and PLSdp were significantly decreased up to 17.99 dB and 16.27 dB, respectively in the experimental group. The most and least Ldp were significantly different (p<0.05; they occurred at 5888.50 and 588.00 Hz, respectively. There were significant differences between temporary and permanent threshold shift at various frequencies (p<0.05. These differences were mainly related to 5888.50 Hz compared to other frequencies in each ear (p<0.05.Conclusion: DPOAEs are an attractive tool for obtaining information about small temporary or permanent threshold shifts, even when the pure tone audiogram is normal.

  18. Characterization of spontaneous otoacoustic emissions in 2-4 day old neonates with respect to gender and ear

    Institute of Scientific and Technical Information of China (English)

    Jinfeng Liu; Baoyu Shi; Ningyu Wang; Jinlan Li

    2009-01-01

    BACKGROUND: Spontaneous otoacoustic emissions (SOAEs) are regarded as a valuable audiometric parameter that objectively reflects the function of outer hair cells (OHCs). Many studies have reported that the incidence of SOAEs in adults is less than 50%. Therefore, measurement of SOAEs may be of little value to clinical examinations. However, the incidence of SOAEs in infants and neonates is higher than in adults.OBJECTIVE: To analyze the basic characteristics of SOAEs in 2-4 day old neonates, and to demonstrate the difference in OHC function between sexes and ears.DESIGN, TIME AND SETTING: Neurophysiological contrast study, performed in the Department of Neonates, Beijing Chaoyang Hospital, Capital Medical University, between December 2007 and August 2008.PARTICIPANTS: A total of 112 newborns (224 ears) consisting of 59 females and 53 males were included in this study.METHODS: The probe was adapted and embedded in the neonate external auditory canal with a foam rubber earplug after checking and clearing up the outer ear canal. The presence of SOAEs was determined when the signal amplitude had a clear peak exceeding -30 dB, or was 3 dB above the noise floor.MAIN OUTCOME MEASURES: The incidence of SOAEs, the number of SOAE signal peaks, and the maximal tension of SOAEs.RESULTS: The incidence in females (79.7%) was higher than males (76.4%) (P> 0.05), and the incidence in right ears (86.6%) was higher than in left ears (69.6%) (P 0.05). The mean maximum SOAE level per ear in females (-3.29 ± 9.28) dB sound pressure level (SPL) was slightly higher than that in males (-3.91 ±9.14) dB SPL(P>0.05). Also, the mean maximum SOAE level in right ears (-2.03 ±9.11) dB SPL was higher than in left ears (-5.50 ± 9.65) dB SPL (P < 0.05). The maximum SOAE level showed a positive correlation with maximum SOAE number in emitting ears (r= 0.55, P< 0.01).CONCLUSION: The incidence of SOAEs in neonates is high (78.1%) within 4 days of birth. The incidence of SOAEs and the maximum SOAE

  19. Evidence for the distortion product frequency place as a source of distribution product otoacoustic emission (DPOAE) fine structure in humans. I. Fine structure and higher-order DPOAE as a function of the frequency ratio f2/f1

    NARCIS (Netherlands)

    Mauermann, M; Uppenkamp, S; van Hengel, PWJ; Kollmeier, B

    1999-01-01

    Critical experiments were performed in order to validate the two-source hypothesis of distortion product otoacoustic emissions (DPOAE) generation. Measurements of the spectral fine structure of DPOAE in response to stimulation with two sinusoids have been:performed with normal-hearing subjects. The

  20. Recovery of distortion product otoacoustic emissions (DPOAE) with high time-resolution from a moderate monaural-exposure to 2-kHz in human subjects

    DEFF Research Database (Denmark)

    de Toro, Miguel Angel Aranda; Ordoñez, Rodrigo Pizarro; Reuter, Karen;

    2008-01-01

    The amplitude of distortion product otoacoustic emissions (DPOAE) decreases temporarily after exposure to a sound of moderate level. These changes show similarities to the changes observed in absolute hearing thresholds after similar sound exposures. This paper presents the experimental protocol...... to study how DPOAEs in human subjects are affected after a monaural exposure of ten minutes to a pure tone of 2 kHz. The experimental protocol allows to measure fine structures of the DPOAE with high time-resolution in a limited frequency range. Thus, the results give a detailed description of the DPOAE...... recovery process and can be used to develop a mathematical model of the recovery. This is the first approximation to study the recovery of more complex exposures. [Work supported by the Danish Research Council for Technology and Production.]...

  1. Emissões otoacústicas por produtos de distorção em ovinos normais e após indução de hiperinsulinemia Distortion product otoacoustic emissions in sheep before and after hyperinsulinemia induction

    Directory of Open Access Journals (Sweden)

    Francisco Carlos Zuma e Maia

    2008-04-01

    Full Text Available As emissões otoacústicas transientes evocadas e as emissões otoacústicas por produtos de distorção vêm assumindo importância significativa na identificação de alterações cocleares. OBJETIVO: Através da monitorização das emissões otoacústicas, registrar os limiares dos produtos de distorção em condições normais e na presença de modificações eletrofisiológicas nas células ciliadas externas cocleares de ovelhas após a indução de hiperinsulinemia aguda. MATERIAL E MÉTODO: Estudo experimental com sete ovelhas no grupo-controle e sete no grupo-estudo. Os níveis de insulina e glicose foram verificados simultaneamente ao registro das emissões otoacústicas por produtos de distorção de 10 em 10 minutos, até o tempo de 90 minutos. O grupo-controle recebeu soro fisiológico, e o grupo-estudo, injeção em bolo de 0,1 U/kg de insulina humana regular. RESULTADOS: Houve diminuição significante nos limiares dos produtos de distorção no grupo-estudo em relação ao grupo-controle nas freqüências acima de 1.500 Hz e após o tempo de 60 minutos (P Transient evoked otoacoustic emissions and distortion product otoacoustic emissions have gained significant importance in the identification of cochlear alterations. AIM: To record distortion product thresholds through the monitoring of otoacoustic emissions in normal conditions and in the presence of electrophysiologic changes in cochlear outer hair cells in sheep after hyperinsulinemia induction. MATERIAL AND METHODS: Experimental study, with seven sheep in the control group and seven in the study group. Insulin and glucose concentrations were measured simultaneously for the recording of distortion product otoacoustic emission every 10 minutes, all the way to 90 minutes. The control group received saline solution, and the study group received a bolus injection of 0.1 U/kg of regular human insulin. RESULTS: There was a significant reduction in distortion product thresholds in

  2. Individual differences and the reliability of 2F1-F2 distortion-product otoacoustic emissions: effects of time-of-day, stimulus variables, and gender.

    Science.gov (United States)

    Cacace, A T; McClelland, W A; Weiner, J; McFarland, D J

    1996-12-01

    Distortion product otoacoustic emissions (DPOAEs) measured from the ear canal can be a sensitive tool to detect changes in cochlear function over time. However, if multiple-measurement procedures are to be useful clinically, testing needs to be reliable and sources of variability within individuals should be known. Herein, the influence of time-of-day (TOD), stimulus frequency, stimulus sound pressure level (SPL), and gender were evaluated on 2f1-f2 DPOAE amplitude in 16 adult volunteers with normal hearing. The effects of oral temperature and resting-pulse rate were also assessed. This study demonstrated a TOD main effect, with a period approximating one cycle-per-day. The magnitude of this effect averaged less than one dB and was not dependent on stimulus (frequency or SPL) or participant variables (gender, oral temperature, or resting-pulse rate), nor was it synchronized to a particular point-in-time. Stimulus level and gender effects on DPOAEs across frequency were also observed. Using generalizability theory (GT), DP iso-level/frequency profiles (DPILFPs) were found to be reliable measures within-subjects over a contiguous 24-hour time period. Significant and reliable between-subject differences were also documented. This study demonstrates the influence of stimulus and participant variables, quantifies the within-subject reliability over a 24-hour time period, and confirms that significant and reliable between-subject differences exist on DPOAEs across frequency, SPL, and gender.

  3. Portadores de vitiligo: estudo das emissões otoacústicas e efeito de supressão A study on otoacoustic emissions and supression effects in patients with vitiligo

    Directory of Open Access Journals (Sweden)

    Rosanna Mariangela Giaffredo Angrisani

    2009-02-01

    Full Text Available Vitiligo é uma doença cutânea, caracterizada pela ausência da melanina, por destruição de melanócitos. OBJETIVO: Verificar a ocorrência de alteração auditiva em indivíduos com vitiligo. MÉTODO: Avaliação audiológica, pesquisa das emissões otoacústicas evocadas transientes e do efeito de supressão em estudo prospectivo de 24 pacientes com vitiligo. A faixa etária variou de 15 a 45 anos. RESULTADOS: 21 pacientes (87.5% apresentaram audiometria normal; dois apresentaram perda auditiva unilateral em freqüências altas e um apresentou perda coclear de grau moderado à esquerda. Destes 21 sujeitos, 66,7% tiveram ausência de emissões, sugerindo disfunção coclear. As emissões estiveram presentes em todas as bandas de freqüência em apenas 7 pacientes (29,2% e ausentes em 17 (70,8%, com maior ocorrência de falha no sexo masculino, na orelha direita. Na pesquisa da supressão, seis indivíduos falharam, todos do sexo feminino, sendo a orelha esquerda a mais afetada. CONCLUSÃO: Pela análise das emissões otoacústicas verificou-se que os portadores de vitiligo possuem maior predisposição à disfunção coclear, com maior ocorrência no sexo masculino na orelha direita. Quanto ao efeito de supressão, houve maior alteração no sistema eferente em mulheres, com maior ausência à esquerda. As alterações auditivas não diferiram quanto à idade, tipo de vitiligo e tempo de evolução da doença.Vitiligo is a skin disease characterized by absence of melanin due to melanocytes destruction. AIM: to study the incidence of hearing alterations in patients with vitiligo. METHOD: prospective audiological evaluation, transient-evoked otoacoustic emission recordings and study the effects of suppression in 24 patients with vitiligo. Their ages ranged from 15 to 45 years. RESULTS: 21 patients (87.5% had normal audiometry; 2 had unilateral hearing loss in the high frequencies and 1 had cochlear moderate hearing loss in the left ear. Of

  4. Absent otoacoustic emissions predict otitis media in young Aboriginal children: A birth cohort study in Aboriginal and non-Aboriginal children in an arid zone of Western Australia

    Directory of Open Access Journals (Sweden)

    Stokes Annette

    2008-08-01

    Full Text Available Abstract Background Otitis media (OM is the most common paediatric illness for which antibiotics are prescribed. In Australian Aboriginal children OM is frequently asymptomatic and starts at a younger age, is more common and more likely to result in hearing loss than in non-Aboriginal children. Absent transient evoked otoacoustic emissions (TEOAEs may predict subsequent risk of OM. Methods 100 Aboriginal and 180 non-Aboriginal children in a semi-arid zone of Western Australia were followed regularly from birth to age 2 years. Tympanometry was conducted at routine field follow-up from age 3 months. Routine clinical examination by an ENT specialist was to be done 3 times and hearing assessment by an audiologist twice. TEOAEs were measured at ages Results At routine ENT specialist clinics, OM was detected in 55% of 184 examinations in Aboriginal children and 26% of 392 examinations in non-Aboriginal children; peak prevalence was 72% at age 5–9 months in Aboriginal children and 40% at 10–14 months in non-Aboriginal children. Moderate-severe hearing loss was present in 32% of 47 Aboriginal children and 7% of 120 non-Aboriginal children aged 12 months or more. TEOAE responses were present in 90% (46/51 of Aboriginal children and 99% (120/121 of non-Aboriginal children aged Overall prevalence of type B tympanograms at field follow-up was 50% (n = 78 in Aboriginal children and 20% (n = 95 in non-Aboriginal children. Conclusion The burden of middle ear disease is high in all children, but particularly in Aboriginal children, one-third of whom suffer from moderate-severe hearing loss. In view of the frequently silent nature of OM, every opportunity must be taken to screen for OM. Measurement of TEOAEs at age 1–2 months to identify children at risk of developing OM should be evaluated in a routine health service setting.

  5. Otoacoustic Estimates of Cochlear Tuning: Testing Predictions in Macaque

    Science.gov (United States)

    Shera, Christopher A.; Bergevin, Christopher; Kalluri, Radha; Mc Laughlin, Myles; Michelet, Pascal; van der Heijden, Marcel; Joris, Philip X.

    2011-11-01

    Otoacoustic estimates of cochlear frequency selectivity suggest substantially sharper tuning in humans. However, the logic and methodology underlying these estimates remain untested by direct measurements in primates. We report measurements of frequency tuning in macaque monkeys, Old-World primates phylogenetically closer to humans than the small laboratory animals often taken as models of human hearing (e.g., cats, guinea pigs, and chinchillas). We find that measurements of tuning obtained directly from individual nerve fibers and indirectly using otoacoustic emissions both indicate that peripheral frequency selectivity in macaques is significantly sharper than in small laboratory animals, matching that inferred for humans at high frequencies. Our results validate the use of otoacoustic emissions for noninvasive measurement of cochlear tuning and corroborate the finding of sharper tuning in humans.

  6. Medidas da latência das emissões otoacústicas - produto de distorção em neonatos Measures of distortion product otoacoustic emissions latency in neonates

    Directory of Open Access Journals (Sweden)

    Renata Frasson de Azevedo

    2003-10-01

    Full Text Available A latência do produto de distorção das emissões otoacústicas é definido como o tempo que o estimulo acústico leva para alcançar o local gerador da emissão otoacústica na cóclea e retornar ao meato acústico externo, no local do registro. A latência das emissões otoacústicas pode ser um instrumento útil para analisar mudanças na maturação coclear assim como os micromecanismos cocleares, já que há uma relação entre a latência das emissões otoacústicas produto de distorção EOAPD e a onda viajante coclear. Estudos em adultos mostram uma diminuição da latência com o aumento da freqüência sonora, variando de 13.8 ms em 787 Hz a 4.4 ms em 5 Hz. Esta diminuição ocorre devido à organização tonotópica da cóclea. São escassos os trabalhos nesta área e não são encontrados critérios de normalidade para estas medidas, principalmente em recém-nascidos. OBJETIVO: Sendo assim, o objetivo deste trabalho foi caracterizar as medidas da latência das EOAPD em neonatos nascidos a termo e não pertencentes ao grupo de risco para perda auditiva. FORMA DE ESTUDO: Caso controle. MATERIAL E MÉTODO: Foram avaliados 31 neonatos, de ambos os sexos e nascidos a termo, sem intercorrências. O procedimento utilizado foi o programa Latencygram. As freqüências testadas foram de 3 a 6 KHz na intensidade de 70 dBNA para f1 e f2. RESULTADO: Os resultados obtidos mostraram uma diminuição da latência com o aumento da freqüência sonora e uma diferença entre os sexos.Latency of distortion product otoacoustic emissions (DPOE is defined as the time that the acoustic stimulus takes to reach the site generating the otoacoustic emission, inside de cochlea, and the return to the external acoustic meatus, to be register. DPOE latency may serve as a useful tool to study cochlear maturational changes as well as the micromechanics of the cochlea, since a relationship between DPE latency and the cochlear traveling wave was observed. Studies on

  7. Triagem auditiva neonatal com emissões otoacusticas e reflexo cocleo-palpebral: estudo da sensibilidade e especificidade Newborn Hearing Screening with otoacoustic emissions and cochlear-palpebral reflex: sensitivity and specificity study

    Directory of Open Access Journals (Sweden)

    Rosanna Mariangela Giaffredo Angrisani

    2012-10-01

    Full Text Available OBJETIVO: analisar a especificidade e sensibilidade da TAN com emissões otoacústicas evocadas por estimulo transiente (EOAT associadas à pesquisa do reflexo cócleo-palpebral (RCP, comparando-os aos resultados do Potencial Evocado Auditivo de Tronco Encefalico (PEATE. MÉTODO: a casuística do presente estudo foi composta por 369 RN de risco para deficiência auditiva que foram submetidos à triagem com a captação das emissões otoacústicas evocadas por estímulo transiente e pesquisa do reflexo cócleo- palpebral. Os resultados foram comparados aos resultados do Potencial Evocado Auditivo de Tronco Encefalico (PEATE. RESULTADOS: a incidência do tipo da perda auditiva na população geral foi de 4RN (1,1% com perda coclear, 22 (5,9% com perda condutiva, 2 (0,5% com espectro da neuropatia auditiva (ENA, 14 (3,8% com alteração central e 15 (4,1% com atraso de maturação da via auditiva. A TAN mostrou 100% de sensibilidade e 94,6% de especificidade na detecção de alterações cocleares e espectro da neuropatia auditiva; 77,3% de sensibilidade e 94,6% de especificidade na detecção de alterações condutivas e 42,9% de sensibilidade e 94,6% de especificidade na detecção de alterações centrais. Todos os achados evidenciaram diferenças estatisticamente significantes em relação aos neonatos auditivamente normais. CONCLUSÃO: este protocolo de TAN mostrou-se eficaz na detecção de RN com alterações de cocleares e espectro da neuropatia auditiva com sensibilidade e especificidade elevadas.PURPOSE: to study the specificity and sensitivity of NHS with otoacoustic emissions transient stimulus (TEOAE associated with cochlear-palpebral reflex (CPR, and comparing the results of Auditory Evoked Potential (BAEP. METHOD: three hundred and sixty-nine neonates under risk of hearing loss were evaluated. Evaluation procedures consisted of transient otocoustic emissions(TOAEs, cochlear-palpebral reflex (CPR, and ABR diagnostic carried out in the

  8. A study on relationship between distortion product otoacoustic emissions and therapeutic effects in tinnitus%畸变产物耳声发射结果与耳鸣疗效的相关性研究

    Institute of Scientific and Technical Information of China (English)

    张静; 周慧芳; 许轶; 张耕

    2009-01-01

    Objective:To find mechanism of tinnitus and explore effective treatment for tinnitus. Method: The 133 tinnitus patients were assigned into two groups by relationship between Distortion product otoacoustic emissions and frequencies of tinnitus: relationship group(73 cases) and non-relationship group(60 cases). All 133 cases were treated with drug,such as injection of Lipo PGE1. Vitamine B1 and VitamineB12 . After 14 days of treatment the efficacy of the medicines in two groups was observed. Result:The effective rate of two groups mentioned above were 75. 3% and 36. 7% respectively( P 0.05).结论:对于DPOAE异常频率与耳鸣的主调存在对应关系的耳鸣患者,尤其是急性耳鸣患者,改善内耳微循环的药物治疗是一种有效的治疗方法.针对不同DPOAE特点的耳鸣患者,应采取个性化的治疗方案.

  9. Medidas de imitância acústica em lactentes com 226hz e 1000hz: correlação com as emissões otoacústicas e o exame otoscópico Accoustic immitance measures in infants with 226 and 1000 hz probes: correlation with otoacoustic emissions and otoscopy examination

    Directory of Open Access Journals (Sweden)

    Michele Vargas Garcia

    2009-02-01

    Full Text Available A avaliação audiológica do lactente deve ser composta pela verificação das condições de orelha média (medidas de imitância acústica e otoscopia e pela avaliação coclear (Emissões Otoacústicas. OBJETIVO: Verificar qual tom teste da timpanometria (226Hz ou 1000Hz tem maior correlação com o exame otoscópico e com o resultado das Emissões Otoacústicas por estímulo transiente. MÉTODO: Realizou-se emissões otoacústicas nos 60 lactentes da amostra, com idade entre de zero e quatro meses. Foram distribuídos em dois grupos, sendo o grupo I 30 lactentes com EOA presente e o grupo II 30 lactentes com EOA ausente. Foram submetidos à timpanometria de múltiplas freqüências, com tom teste de 226Hz e 1000Hz e avaliação otoscópica. RESULTADOS: Na timpanometria, o tom teste de 1000Hz apresentou mais sensibilidade para identificar as alterações de orelha média. Nas crianças com curva timpanométrica dentro da normalidade, ambos os tons-teste (226 e 1000Hz apresentaram alta especificidade. Todas as correlações foram significantes com o tom teste de 1000Hz. CONCLUSÃO: O tom teste de 1000Hz apresentou maior correlação estatisticamente significante com as EOA e com a avaliação otoscópica para lactentes de zero a quatro meses.Audiological evaluation in infants should include the middle ear (immitance measures and otoscopy and also a cochlear evaluation. AIM: To check which tympanometry tone test (226 Hz or 1000 Hz, transient otoacoustic emissions and otoscopy. METHODS: Transient otoacoustic emissions were taken from sixty infants ranging from zero to four months of age. The babies were assigned to two groups of 30 infants each, according to the presence or absence of otoacoustic emissions (OAE. All babies have undergone tympanometry with probe tones of 226 and 1000 Hz and ENT evaluation. RESULTS: Tests performed with 1000 Hz probe tone were more sensitive in identifying middle ear disorders. In children with normal

  10. 自觉听力正常耳鸣患者纯音听力及畸变产物耳声发射临床分析%Audiometry and distortion product otoacoustic emissions in tinnitus patients without hearing complaints

    Institute of Scientific and Technical Information of China (English)

    王晓晖; 肖玉丽

    2011-01-01

    Objective To study pure tone audiometry and distortion product otoacoustic emissions (DPOAE) features in tinnitus patients who do not perceive hearing loss. Methods Pure tone threshold, hearing loss, SNR of DPOAE were performed in 114 (190 ears) adults with tinnitus cases with never perceived hearing loss, investigate the relationship between every risk factor and tinnitus. Results Audiometry showed high frequency hearing loss in 46.31% (88/ 190), low frequency hearing loss in 14.73% (28/190), normal hearing in 23.15% (44/190), and other types of audio-grams in 15.78%(30/190) of the patients. Risk factors included noise exposure, fatigue, stress, and pre-existing diseases. There was a negative correlation between DPOAE amplitude and pure tone threshold. DPOAE response frequencies were closely related to frequency distribution of pure tone thresholds. Conclusion A significant number of patients with tinnitus but no hearing complaints may still have abnormal hearing, especially in the high frequency range. A negative correlation exists between DPOAE amplitude and pure tone threshold. DPOAEs may serve as an objective indicator of the level of hearing loss in tinnitus patients with no hearing complaints, which may be of value in the clinic.%目的 分析自觉听力正常耳鸣患者的纯音听力特征,并探讨自觉听力正常耳鸣患者畸变产物耳声发射(distortion product otoacoustic emission,DPOAE)测定值与纯音听阈值之间的相关性及其意义.方法 2010-2011年在我科就诊的以耳鸣为第一主诉但无明显自觉听力障碍患者114例(190耳),对所有入组患者进行纯音测听及DPOAE检测.分析DPOAE测定值与纯音听阈值之间的相关性,并结合其发病的可能危险因素进行相关分析.结果 自觉听力正常的耳鸣患者中,听力异常可达76.84% (146/190).纯音测听表现为:高频下降型46.31% (88/190);低频下降型14.73% (28/190);正常23.15% (44/190);其它类型15.78% (30/190).

  11. 梅尼埃病畸变产物耳声发射的临床听力学特征%The feature of distortion product otoacoustic emissions in clinical audiometry on Meniere disease

    Institute of Scientific and Technical Information of China (English)

    王建明; 王斌全

    2002-01-01

    目的探讨梅尼埃病畸变产物耳声发射(distortion product otoacoustic emissions,DPOAE)听力学表现,明确梅尼埃病DPOAE临床听力学特征.方法收治梅尼埃病336例,行纯音听阈与DPOAE测试,并绘出纯音听力图与DPOAE图.结果纯音听力测试,297名为感音神经性耳聋,39名听力正常;在DPOAE测试中,患耳检出率均较健耳低;对刺激频率组的几何平均频率(Fm)及它们所对应的DPOAE幅值,均显著低于健耳,且幅值重复性差;患耳检出阈显著高于健耳.纯音听阈均值(Pure tone average,PTA)≥40 dB的145例,DPOAE反应缺失;PTA≤35 dB,伴低频下降的98例,DPOAE低频或低、中频振幅下降或反应消失;DPOAE图与纯音听力图的病损频率范围一致,曲线基本吻合.39例听阈正常的梅尼埃病患者,DPOAE测试显示有程度不同的高频或高、中频或低频振幅下降或缺失.结论 DPOAE能鉴别出亚临床的病理改变,对梅尼埃病的早期诊断、动态监测与预后等有指导意义.

  12. Quick Detection of Hearing Loss Using Distortion Product Otoacoustic Emissions Evoked by Swept Tones%利用扫频畸变产物耳声发射实现听力损失的快速检测

    Institute of Scientific and Technical Information of China (English)

    陈世雄; 邓军; 李光林

    2013-01-01

    Distortion product otoacoustic emissions (DPOAEs) are sound energy generated by healthy inner ears when stimulated by two fixed-frequency pure tones. Since DPOAEs are physiologically related with the functional status of the inner ears, DPOAE measurement has been widely used in both hearing screening of newborns and hearing diagnoses of adults. However, there are some limitations in current measurements of DPOAE, such as complex operation, insufficient resolution and low efficiency. In this study, a new method in which frequency-varying swept tones were used to replace pure tones to evoke DPOAEs was proposed to overcome the limitations of current methods. In this method, a three-interval paradigm was employed to eliminate the stimulus artifacts and a dynamic tracking filter was used to extract high-quality swept-tone DPOAEs from the recorded signals. The results show that the swept-tone method can improve both the efficiency and frequency-resolution of current methods. Moreover, the swept-tone DPOAEs within a wide frequency range can help to identify the exact location of the hearing loss. Using swept tones to measure DPOAEs can be beneficial in developing a new type of OAE device with high efficiency to help doctors with accurate diagnoses and appropriate treatments in the clinic.%  畸变产物耳声发射(Distortion Product Otoacoustic Emission,DPOAE)是在两个固定频率的纯音刺激下,由健康人耳主动向外发射的声音能量。DPOAE 耳声发射信号的存在与人耳的健康状况密切相关,因而它的检测被广泛用于新生儿听力筛查和成人听力检测。然而,目前的 DPOAE 检测技术存在操作复杂、分辨率低、测试时间长等不足。本文提出用频率随时间线性增加的扫频信号替代纯音作为刺激声诱发 DPOAE 耳声发射,以克服当前方法的不足。该扫频方法采用“三段式”播放组合消除刺激声的干扰,并用动态跟踪滤波器从记录到的信号

  13. Quick Detection of Hearing Loss Using Distortion Product Otoacoustic Emissions Evoked by Swept Tones%利用扫频畸变产物耳声发射实现听力损失的快速检测

    Institute of Scientific and Technical Information of China (English)

    陈世雄; 邓军; 李光林

    2013-01-01

      畸变产物耳声发射(Distortion Product Otoacoustic Emission,DPOAE)是在两个固定频率的纯音刺激下,由健康人耳主动向外发射的声音能量。DPOAE 耳声发射信号的存在与人耳的健康状况密切相关,因而它的检测被广泛用于新生儿听力筛查和成人听力检测。然而,目前的 DPOAE 检测技术存在操作复杂、分辨率低、测试时间长等不足。本文提出用频率随时间线性增加的扫频信号替代纯音作为刺激声诱发 DPOAE 耳声发射,以克服当前方法的不足。该扫频方法采用“三段式”播放组合消除刺激声的干扰,并用动态跟踪滤波器从记录到的信号中提取高信噪比的扫频 DPOAE 信号。实验结果表明,扫频 DPOAE 检测方法可以大大缩短 DPOAE 的测量时间,提高检测结果的分辨率,并能灵敏反映受试者听力损失的频率范围。扫频 DPOAE 检测方法的提出,有利于研制一种快速高效的新型耳声发射检测仪,在临床上协助医生进行准确的听力诊断和治疗。%Distortion product otoacoustic emissions (DPOAEs) are sound energy generated by healthy inner ears when stimulated by two fixed-frequency pure tones. Since DPOAEs are physiologically related with the functional status of the inner ears, DPOAE measurement has been widely used in both hearing screening of newborns and hearing diagnoses of adults. However, there are some limitations in current measurements of DPOAE, such as complex operation, insufficient resolution and low efficiency. In this study, a new method in which frequency-varying swept tones were used to replace pure tones to evoke DPOAEs was proposed to overcome the limitations of current methods. In this method, a three-interval paradigm was employed to eliminate the stimulus artifacts and a dynamic tracking filter was used to extract high-quality swept-tone DPOAEs from the recorded signals. The results show that the swept-tone method can

  14. Otoacoustic interrelationships of the barn owl

    Science.gov (United States)

    Bergevin, Christopher; Manley, Geoffrey A.; Köppl, Christine

    2015-12-01

    Significant debate still exists about the biophysical mechanisms at work in otoacoustic emission (OAE) generation and how such may differ between mammals and non-mammals given gross morphological differences (e.g., existence of basilar membrane traveling waves, degree of tectorial membrane coupling). To further elucidate general principles at work, we examined the barn owl for interrelationships between spontaneous emissions (SOAEs) and those evoked using a single tone (SFOAEs). First, most ears exhibited SOAEs as a stable periodic `rippling' whose peak-to-peak spacing was relatively constant (˜0.4 kHz). Some ears showed substantially larger narrowband peaks, although their statistical distributions were highly noisy. Second, significant interactions between a low-level tone and SOAE activity were observed via an interference pattern as the tone frequency was swept. Using a suppression paradigm to extract SFOAEs as the residual, the magnitude exhibited a stable pattern of peaks and valleys unique to each ear. Third, SFOAE phase exhibited significant accumulation as frequency was swept, with a phase-gradient delay of approximately 2 ms that was constant across frequency. The amount of SFOAE phase accumulation between adjacent SOAE peaks tended to cluster about an integral number of cycles, as previously observed for humans. Taken together, our data suggest that the principles underlying how active hair cells work together (e.g., entrainment, phase coherence) are shared between widely different inner ear morphologies, leading to the generation of OAEs with similar properties.

  15. Estudo comparativo entre o aproveitamento escolar de alunos de escola de 1º grau e teste de inibição de emissões otoacústicas transientes Comparative study between school performance on first grade children and suppression of otoacoustic transient emission

    Directory of Open Access Journals (Sweden)

    Miguel Luiz de Sant’Ana Angeli

    2008-02-01

    Full Text Available O processamento auditivo é fundamental para a cognição e pode ocasionar deficiência no aprendizado. Os portadores de sua deficiência podem ser habilitados, melhorando o desempenho escolar. É fundamental identificá-los. Dentre os que apresentam baixo custo e facilidade operacional está o exame de emissões otoacústicas. TIPO DE ESTUDO: Clínico e experimental. OBJETIVO: Estudar a relação do aproveitamento escolar com a inibição da emissão otoacústica transiente por estímulo auditivo contralateral. Material e Métodos: Foram avaliados 39 alunos, de sete a doze anos, sendo 19 (48,7% com bom aproveitamento escolar e 20 (51,3% com aproveitamento inadequado. Os exames emissão otoacústica com inibição contralateral foram comparados aos resultados de aproveitamento escolar. RESULTADOS: A falha da supressão da otoemissão transiente por estímulo acústico contralateral foi mais encontrada no grupo de crianças com mau aproveitamento escolar. Foi estabelecido um valor de corte de 1.6 dB SPL de redução da otoemissão que caracteriza a criança como pertencente ao grupo com mau aproveitamento com sensibilidade de 65,0%, especificidade de 72,2%, acurácia de 68,4% e valor preditivo positivo de 72,2%. CONCLUSÃO: O teste da falha da inibição contralateral da emissão otoacústica por estímulo auditivo contralateral é preditivo de transtorno do aproveitamento escolar em indivíduos de seis a doze anos de idade.School learning can be hampered if there are defects on the central auditory process. Since those with auditory deficiency can be rehabilitated, it is fundamental that we identify them. Otoacoustic emissions test has low cost and operational ease. Study design: clinical and experimental. AIM: to study the relationship between school learning and transient otoacoustic emission suppression by contralateral stimuli. MATERIAL AND METHODS: 39 individuals, from 7 to 12 years of age were evaluated, 19 (48.7% with good school

  16. Recém-nascidos gerados por mães com alto risco gestacional: estudo das emissões otoacústicas produtos de distorção e do comportamento auditivo Neonates born to mothers with high-risk pregnancy: study in distortion product otoacoustic emission and auditory behavioral

    Directory of Open Access Journals (Sweden)

    Marisa Ruggieri-Marone

    2002-03-01

    auditory method. The staff must be finding the best detection and intervention way for the early diagnostic in children born in small cities. The high-risk pregnancy may have some hearing loss risk indicator. Study design: Clinical prospective randomized. Casuistic and method: This prospective work has been to study the results of distortion product otoacoustic emissions and the auditory behavior in 174 neonates. The neonates have been examined on the same day, as the neonates were to be discharged from the hospital and at the adjusted age of 37 weeks or older. Results: There was 23% Refer in the first step. This, 66,8% obtained Pass result and 4,6% was find middle and/or external ear alteration, 30 days before discharged from the hospital. There was no difference of otoacoustic emission amplitude, signal/noise ration and auditory behavior. Conclusion: The otoacoustic emissions should have been done after examining and cleaning the ear canal and that the behavioral assessment had not detected alterations of the middle ear. The concomitant use of otoacoustic emissions and assessment of auditory behavior during neonatal period has provided important information about peripheral auditory system and central auditory pathways. The high-risk pregnancy has not affected otoacoustic emission measurements or auditory behavior after instrumental sound stimulation.

  17. 分泌性中耳炎儿童治疗前后DPOAE检测结果分析%An Analysis of Distortion Product Otoacoustic Emissions on Children with Tympanotomy Tube Insertion

    Institute of Scientific and Technical Information of China (English)

    王淑芬; 王智楠; 徐忠强

    2012-01-01

    目的 分析分泌性中耳炎(SOM)儿童治疗前后畸变产物耳声发射(DPOAE)的结果.方法 对235例(442耳)分泌性中耳炎患儿(SOM组)于置管前及置管后第1天、置管后1周行DPOAE测试,并与123例(246耳)正常儿童(对照组)进行比较.结果 SOM组患儿置管前DPOAE引出率和幅值均较对照组低,置管后第1天即有提高,在1 560、4 416 Hz处引出率升高明显,在1 105、1 560、2 211、4 416 Hz处幅值显著升高,与术前比较,差异有统计学意义(P<0.05或P<0.01).置管后1周DPOAE引出率和幅值进一步升高,与术前比较,引出率在783、1 560、2 211、4 416 Hz及幅值在783~4 416 Hz差异有统计学意义(P<0.05或P<0.01).结论 SOM患儿置管后一周内DPOAE引出率和幅值均逐渐提高.%Objective To analyse the result of distortion product otoacoustic emissions on children with tym-panotomy tube insertion. Methods 235 patients (442 ears) with SOM were selected and recorded the DPOAE audio gram with Smart OAE 4. 24 otodymic analyser before, one day after and one week after tube insertion. 123 normal subjects(246 ears) were selected as control. Results The eliciting rate and amplitude increased after tube insertion. The differences at 1105. 1560,2211, 4416 Hz were statistically significant . The amplitude increased one week later. Conclusion The eliciting rate and amplitude of DPOAE increased gradually after tympanotomy tube insertion in children with SOM.

  18. 某区集体儿童耳声发射筛查8521例听力结果分析%Analysis of 8521 Cases of Children Screening by Otoacoustic Emission in a District

    Institute of Scientific and Technical Information of China (English)

    尚佳; 贾明珍; 陈庆红; 熊丽

    2013-01-01

    Objective:To understand the children’s auditory status by screening 2.5-6 years children in nurseries of Chenghua district in Chengdu, and finding out the listening loss children in early stage. Carry out early interference actions to them, effectively reducing the occurrence of language&hearing disability. Method:Utilizing the Otoacoustic Emission to do hearing test for 8521 children in nurseries total y (3048 children in city and 5473 in countryside), and analyzing the statistic results. Results:Total 1294 children are positive screening in initial Otoacoustic Emission, the rate is 15.19%, including city children 493 and countryside children 801. In the re-screening after 4 weeks, 361 children are positive stil . By acoustic impedance test, the etiologies list as below (someone has two or more repetition etiology): 291 cases of impacted cerumen, 104 cases of catarrhal otitis media, 106 cases of otitis externa, 1 of perforation of tympanic membrane, 87 cases of acute rhinitis, 4 cases of sinusitis, and 5 of nerve deafness.Conclusion:The screening result has obvious geographic differences. The positive screening in countryside children is much more than in city children, and more boys than girls. In order to make a definite diagnosis and provide the most effective treatment for children’s hearing loss, so as to timely improve their communicative skil s in language acquisition and behavior modulation, it is very necessary and important to do the early auditory screening for them.%目的:了解成都市成华区内托幼机构2.5-6岁儿童听力现状,尽早发现听力障碍问题儿童,采取早期干预措施,可有效减少听力言语残疾的发生。方法:运用客观测试技术耳声发射,随机抽取成都市成华区所属幼儿园8521名儿童进行听力检查,其中城市幼儿园3048名儿童,农村幼儿园5473名儿童,并统计分析筛查结果。结果:8521例儿童中,耳声发射初筛阳性检出1294人,占15.19%

  19. 畸变产物耳声发射在船员听力调查中的应用%Application of distortion product otoacoustic emission to hearing investigation in the ship crew

    Institute of Scientific and Technical Information of China (English)

    潘丽宁; 吴小海; 冯小玲

    2009-01-01

    目的 探讨畸变产物耳声发射(DPOAE)在船员噪声性听力损伤诊断中的应用价值.方法 100名船员(其中噪声性耳聋组52人,听阈正常组48人)为实验组,另外50名听力正常人为对照组.对2组人员进行纯音听力测定和DPOAE检测,比较2组的听阈值和DPOAE幅值及引出率.结果 噪声性聋组与对照组比较,所有频区听阚值差异均有统计学意义(P<0.05),噪声性聋组DPOAE幅值和引出率较对照组明显下降(P<0.05),随着接触噪声工龄的延长,DPOAE引出率逐渐下降(P<0.05).听阈正常组DPOAE幅值和引出率也较对照组明显下降(P<0.05).结论 船员早期噪声性听力损伤纯音听阈可能正常,应用DPOAE可用于船员噪声性听力损伤的早期诊断和评估.%Objective To explore the application of the distortion product otoacoustic emission (DPOAE) in the diagnosis of noise-induced hearing damage for the ship crew.Methods The experimental group consisted of 100 crew members,among whom 52 had noise-induced hearing damage and 48 people had normal hearing thresholds.And another 50 people with normal hearing level were chosen as control.The two groups received acoustic emission,pure tone audiometry and DPOAE testing.Hearing thresholds,DPOAE amplitude and the provocation rate were compared between the two groups.Results Statistical differences could be noted in hearing thresholds in all frequency zones,when a comparison was made between the noise-induced hearing damage group and the control group ( P < 0.05 ).DPOAE amplitude and the provocation rate of the experimental group decreased significantly ( P < 0.05 ),when compared with those of the control group.With the extension of noise exposure,DPOAE provocation rate for the ship crew decreased ( P < 0.05 ).DPOAE amplitude and the provocation rate of the normal hearing level group also decreased more significantly than those of the control group (P < 0.05 ).Conclusions Pure-tone hearing threshold for the ship crew

  20. Clinical value of distortion product otoacoustic emission in tinnitus patients with normal hearing%畸变产物耳声发射测试在听力正常的耳鸣者中的应用价值

    Institute of Scientific and Technical Information of China (English)

    朱小平; 张香玉

    2011-01-01

    Objective To investigate the clinical value of distortion product otoacoustic emission (DPOAE) application in normal hearing patients with tinnitus. Methods A total of 82 healthy volunteers (164 ears) without tinnitus or hearing loss were enrolled as control group and tested with DPOAE. Meanwhile, 84 normal hearing patients (109 ears) with tinnitus were tested with DPOAE before and after 20-days treatment including circulation improvement and supplemental nutrition for inner ear. Results At the frequency of 0.5, 0.75, 1.00, 1.50, 2.00, 3.00, 4.00, 6.00 and 8.00 kHz, the detection rate of DPOAE in tinnitus group was significantly lower than that in control group (all P0.05); the wave height in every frequency was increased after treatment, especially in high frequency (3.00. 4.00, 6.00 and 8.00 kHz, all P< 0.05). Conclusion Tinnitus with normal hearing is likely to be related to hearing loss of super high frequency caused by early impairment of outer hair cells in cochlea. DPOAE examination can be used as an objective assessment for early change of cochlea and periphery tinnitus.%目的 探讨畸变产物耳声发射( DPOAE)测试在听力正常的耳鸣患者中的临床应用价值.方法 对82名(164耳)听力正常且无耳鸣的健康者(对照组)进行DPOAE测试.同时对84例(109耳)听力正常的耳鸣患者(耳鸣组)进行DPOAE测试,并给予改善内耳循环、补充营养等治疗20 d后再次进行DPOAE测试.结果 耳鸣组中,DPOAE测试在0.50、0.75、1.00、1.50、2.00、3.00、4.00、6.00、8.00 kHz各频率点的检出率均显著低于对照组(P值均<0.05).耳鸣组治疗后DPOAE的检出率为43.1%,与治疗前(56.9%)的差异无统计学意义(P>0.05),治疗后在各频率点的DPOAE反应幅值呈提高趋势,尤其在高频(3.00、4.00、6.00、8.00 kHz)的差异有统计学意义(P值均<0.05).结论 听力正常的耳鸣发生可能与耳蜗外毛细胞的早期损伤导致的超高频听力损失有关,DPOAE检测可以

  1. Application of distort product otoacoustic emission(DPOAE)in the tinnitus patients with normal hearing capability%畸变产物耳声发射在听力正常的耳鸣患者中的应用

    Institute of Scientific and Technical Information of China (English)

    邵渊; 安燕; 张少强

    2013-01-01

    Objective To explore the clinical characteristics of the distort product otoacoustic emission( DPOAE )in the tinnitus patients with normal hearing capability and its applied value. Methods DPOAE test was held in 160 tinnitus patients with the normal hearing capability and 120 healthy controls with the normal hearing capability and no tinnitus symptoms. The results were compared between two groups. The tinnitus patients were given nerve-nourishing medicine and vasodilator medicine for consecutive 3 weeks and then DPOAE test was performed again. The results before and after treatment were compared. Results In tinnitus group, the incidence of DPOAE in each frequency was significantly lower than that in healthy controls( P <0. 05 ). After the treatment, the DPOAE reacting amplitudes in high frequency were obviously improved in the tinnitus patients( P < 0. 05 ). Conclusion The occurrence of the tinnitus may be relevant to the cochlear outer hair cell early injury-induced high frequency hearing loss, and DPOAE test can reflect the early stage cochlear injury and act as an objective method for detecting the tinnitus.%目的 探讨听力正常的耳鸣患者畸变产物耳声发射(DPOAE)的临床特点,了解畸变产物耳声发射在耳鸣患者中的应用价值.方法 对160例听力正常伴耳鸣的患者设定为耳鸣组,进行DPOAE测试,同时对120例听力正常且无耳鸣健康者设定为对照组,进行DPOAE测试,对比两组检测结果.对耳鸣患者给予营养神经药物和改善内耳血液循环药物联合治疗3周后再次进行DPOAE测试,对比治疗前后结果.结果 耳鸣组中,DPOAE测试在各频率点的检出率均显著低于健康对照组(P<0.05).耳鸣组经过治疗后,耳声发射在高频段的反应幅值明显提高,与治疗前相比,差异具有统计学意义(P<0.05).结论 耳鸣的产生可能与耳蜗外毛细胞早期损伤导致的高频听力损失相关,DPOAE的检测可反映早期耳蜗病变并可作为耳

  2. Application of Transient Evoked Otoacoustic Emission in the Screening of Neonatal Hearing%瞬态诱发耳声发射在新生儿听力筛查中的应用

    Institute of Scientific and Technical Information of China (English)

    林楚忠; 杨海弟; 王挥戈; 曾贤辉; 肖林海; 李广文; 洪世宏; 黄虹

    2013-01-01

    目的:探讨和分析瞬态诱发耳声发射在新生儿听力筛查中的应用。方法应用瞬态诱发耳声发射(TEOAE)对2009年3月至2012年12月在本院产科出生的3026例活产新生儿进行新生儿普遍听力筛查(UNHS)。初筛时间为出生后2~3d,用TEOAE进行。对于初筛没有通过的新生儿,联合应用自动听性脑干诱发电位(AABR)进行复筛,于出生后42d进行。复筛“未通过”者于3个月龄时,做诊断性检查评估听力水平,并跟踪随访1年以上。结果初筛3026例,通过2656例,通过率为87.78%;复筛370例,通过348例;复筛仍未通过22例,其中确诊听力损失为11例。在3026例新生儿中,听力损失的发病率为0.36%,初筛假阳性率为11.86%。结论瞬态诱发耳声发射在新生儿听力筛查中具有重要作用,初筛假阳性可通过对各种影响因素分析而合理处置。%Objective?To investigateanda nalyzetherateand reasons of false positive by newborn hearing screening. Methods Transient evoked otoacoustic emission (TEOAE) were used to examine the hearing of 3026 live birth newborns of our hospital's maternity department from Mar.2009 to Dec.2012. TEOAE was used for preliminary hearing screening in 2days-3day safterbirth, and both TEOAE and automated auditory brainstem response(AABR) were used for these condary hearing screening at 42 days after birth. Diagnostichearing tests were used to assess the hearing of those who failed the secondary hearing screening in 3months after birth. They were followed up for more than 1 year. Results All the 3026 new borns were had the preliminary hearing screening. 2656 of them were passed, the ratio was 87.78%. 370 in fants failed preliminary hearing screening when they underwent the secondary screen in gat 42 days after birth. 348 of them were passed, 22 of cases who failed secondary Screening were diagnosed with hearing loss, and the morbidity of 3026 new borns was 0.36%. The false

  3. Perfil audiométrico e de emissões otoacústicas evocadas por produto de distorção em gestores de trânsito expostos a monóxido de carbono e ruído Audiometric profile and evoked otoacoustic emissions per product of distortion in transit managers, exposed to carbon monoxide and noise

    Directory of Open Access Journals (Sweden)

    Soraya de Carvalho Rocha

    2013-04-01

    Full Text Available OBJETIVO: avaliar o perfil audiométrico e de emissões otoacústicas evocadas por produto de distorção em gestores de trânsito, expostos a monóxido de carbono e ruído, bem como constatar a presença de ambos agentes nos postos de trabalho. MÉTODO:estudo transversal, descritivo, com 37 gestores do trânsito, submetidos a anamnese, meatoscopia, audiometria tonal e emissões otoacústicas, distribuídos em: G1, composto por 18 indivíduos sem histórico de exposição concomitante a monóxido de carbono e ruído; e, G2, formado por 19 trabalhadores expostos simultaneamente aos dois agentes. Para pesquisa da presença dos agentes no ambiente foram utilizadas audiodosímetrias e avaliações de curta duração com medidor instantâneo. As variáveis de anamnese foram analisadas segundo o teste t Student e Mann-Whitney. Para as medidas de otoemissões acústicas e de limiares tonais utilizou-se testes de qui-quadrado (χ2 ou exato de Fisher e dos postos sinalizados de Wilcoxon com significância de 5%. RESULTADOS: foi constatada presença de monóxido de carbono e ruído durante a atividade dos trabalhadores. Não foi observada diferença significante na idade e tempo de função. O G2 obteve média de limiares tonais maior que G1, para orelha direita, em 1KHz (p=0,050 e para orelha esquerda em 3KHz (p=0,016 e 4KHz (p=0,028; e, comparados os limiares tonais alterados G2 apresentou diferença maior em 3KHz na orelha esquerda (p=0,003. Nas emissões otoacústicas, G2 apresentou maior ausência de respostas que G1 em 2.730Hz e 3.218Hz (p=0.016 para orelha direita. CONCLUSÃO: trabalhadores expostos a monóxido de carbono e ruído apresentaram piores resultados audiométricos e nas emissões otoacústicas quando comparado ao grupo de não expostos.PURPOSE: to evaluate the hearing profile and otoacoustic emission evoked by distortion product in Traffic Managers exposed to noise and carbon monoxide, as well as to establish the presence of both agents

  4. Perfil audiométrico e de emissões otoacústicas evocadas por produto de distorção em gestores de trânsito expostos a monóxido de carbono e ruído Audiometric profile and evoked otoacoustic emissions per product of distortion in transit managers, exposed to carbon monoxide and noise

    Directory of Open Access Journals (Sweden)

    Soraya de Carvalho Rocha

    2013-01-01

    Full Text Available OBJETIVO: avaliar o perfil audiométrico e de emissões otoacústicas evocadas por produto de distorção em gestores de trânsito, expostos a monóxido de carbono e ruído, bem como constatar a presença de ambos agentes nos postos de trabalho. MÉTODO:estudo transversal, descritivo, com 37 gestores do trânsito, submetidos a anamnese, meatoscopia, audiometria tonal e emissões otoacústicas, distribuídos em: G1, composto por 18 indivíduos sem histórico de exposição concomitante a monóxido de carbono e ruído; e, G2, formado por 19 trabalhadores expostos simultaneamente aos dois agentes. Para pesquisa da presença dos agentes no ambiente foram utilizadas audiodosímetrias e avaliações de curta duração com medidor instantâneo. As variáveis de anamnese foram analisadas segundo o teste t Student e Mann-Whitney. Para as medidas de otoemissões acústicas e de limiares tonais utilizou-se testes de qui-quadrado (χ2 ou exato de Fisher e dos postos sinalizados de Wilcoxon com significância de 5%. RESULTADOS: foi constatada presença de monóxido de carbono e ruído durante a atividade dos trabalhadores. Não foi observada diferença significante na idade e tempo de função. O G2 obteve média de limiares tonais maior que G1, para orelha direita, em 1KHz (p=0,050 e para orelha esquerda em 3KHz (p=0,016 e 4KHz (p=0,028; e, comparados os limiares tonais alterados G2 apresentou diferença maior em 3KHz na orelha esquerda (p=0,003. Nas emissões otoacústicas, G2 apresentou maior ausência de respostas que G1 em 2.730Hz e 3.218Hz (p=0.016 para orelha direita. CONCLUSÃO: trabalhadores expostos a monóxido de carbono e ruído apresentaram piores resultados audiométricos e nas emissões otoacústicas quando comparado ao grupo de não expostos.PURPOSE: to evaluate the hearing profile and otoacoustic emission evoked by distortion product in Traffic Managers exposed to noise and carbon monoxide, as well as to establish the presence of both agents

  5. Reconhecimento de fala em presença de ruído e suas relações com a supressão das emissões otoacústicas e o reflexo acústico Recognition of speech in noise and relations with suppression of otoacoustic emissions and the acoustic reflex

    Directory of Open Access Journals (Sweden)

    Larissa Lautenschlager

    2011-02-01

    Full Text Available Pessoas com dificuldade para compreensão de fala com som competitivo podem apresentar ausência do efeito de supressão das emissões otoacústicas e do reflexo acústico. OBJETIVO: Estudar o desempenho do sistema auditivo eferente em indivíduos normo-ouvintes com queixa de reconhecer a fala na presença de ruído. MATERIAL E MÉTODO: Estudo prospectivo, com amostra composta por 50 voluntários, com idades entre 19 e 32 anos, normo-ouvintes, que referiram (com queixa-CQ ou não (sem queixa-SQ dificuldade de compreender a fala no ruído. As emissões otoacústicas evocadas produto de distorção (EOAEPDs foram testadas nas frequências de 1500 a 6000Hz. O reflexo acústico contralateral (RAC foi pesquisado nas frequências de 500 a 4000Hz. RESULTADOS: Os grupos diferiram estatisticamente quanto à ocorrência de RAC nas orelhas do lado esquerdo na frequência de 4000Hz. Na frequência de 1500 Hz nas orelhas do lado direito constatou-se predomínio estatisticamente significante da ausência do efeito de supressão das EOAEPDs no grupo CQ. Nas orelhas do lado esquerdo, a ausência do efeito de supressão das EOAEPDs foi maior no grupo CQ em 1500Hz e 2000Hz. CONCLUSÃO: Em normo-ouvintes com autorrelato de dificuldade de reconhecer a fala na presença de ruído verificou-se: ausência de supressão das EOAEPDs nas frequências médias em ambas as orelhas e ausência de reflexo acústico contralateral em 4000Hz na orelha esquerda.Subjects presenting difficulties in understanding speech with competing sounds may have absence of otoacoustic emission suppression and the acoustic reflex. AIM: To study the performance of the efferent auditory system in normal hearing subjects complaining of difficulties to understand speech in noise. MATERIAL AND METHODS: A prospective study comprising 50 normal-hearing subjects aged from 19 to 32 years, reporting difficulties with speech recognition in noise (with complaints - WC or not (with no complaints - WNC

  6. Estimation of Otoacoustic Emision Signals by Using Synchroneous Averaging Method

    Directory of Open Access Journals (Sweden)

    Linas Sankauskas

    2011-08-01

    Full Text Available The study presents the investigation results of synchro­nous averaging method and its application in estimation of impulse evoked otoacoustic emission signals (IEOAE. The method was analyzed using synthetic and real signals. Synthetic signals were modeled as the mixtures of deterministic compo­nent with noise realizations. Two types of noise were used: normal (Gaussian and transient impulses dominated (Lapla­cian. Signal to noise ratio was used as the signal quality measure after processing. In order to account varying amplitude of deterministic component in the realizations weighted aver­aging method was investigated. Results show that the perfor­mance of synchronous averaging method is very similar in case of both types of noise Gaussian and Laplacian. Weighted aver­aging method helps to cope with varying deterministic component or noise level in case of nonhomogenous ensembles as is the case in IEOAE signal.Article in Lithuanian

  7. 影响新生儿听力筛查通过率的相关因素分析%THE RESEARCH OF DISTORTION PRODUCT OTOACOUSTIC EMISSION IN NEWBORN HEARING RE-SCREENING

    Institute of Scientific and Technical Information of China (English)

    崔欣华; 盛红; 刘恒

    2011-01-01

    [目的]主要探讨影响新生儿听力筛查通过率的相关因素.[方法]采用两阶段筛查法,印出生以后进 行第1次筛查,未通过初筛者于出生42d左右进行第2次筛查.主要采用GSI-70全自动便携武耳声发射仪进行新生儿听力筛查,单耳不通过即为不通过,不通过者均经两次以上重复测试.在筛查的同时,自制问卷调查表,对新生儿的性别、筛查时间、出生史、家族史、疾病史、母亲妊娠史、父母亲的职业和文化程度等33个因素进行调查,以了解影响新生儿听力筛查通过率的相关因素.调查结果运用SPSS10.0统计软件进行统计分析,采用x2(chi-squared test)检验进行单因素分析,P< 0.05认为差异有统计学意义.[结果]2 236名新生儿中,第1次筛查通过1 874名(83.8%),未通过的在42 d左右进行第2次筛查.362名需要第2次筛查者,实际筛查324名.324名进行第2次筛查的新生儿中,通过310名(95.7%).通过率足月儿、过期产儿高于早产儿,体重超过2 500 g者高于不足2 500 g者,健康新生儿高于有新生儿疾病史者,P值均小于0.05.[结论]新生儿的胎龄、出生体重、新生儿疾病对新生儿听力筛查的通过率有显著影响.父母亲的职业和文化程度等因素对新生儿听力筛查的结果无影响.%[Objective] To find impact factors of distortion product otoacoustic emission (DPOAE) used in newborn hearing re-screening. [Methods] The screening approach included two steps as following: (1) The initial screening was conducted just after bom. (2) The infants who failed in passing in the initial step were screened after 42 days. The screening tool was GSI-70 Automated OAE Screener. "No Pass" meant that any or/and both of two ears didn't pass. "No Pass" must be tested twice in each step and all were "No Pass". Also, we investigated by a form, which consists of 33 related factor items, such as gender of the newborn, time of screening, birth history, family

  8. 自觉听力正常的后循环缺血患者纯音听阈与耳声发射结果分析%Pure tone threshoIds and Otoacoustic Emissions in PCI Patients without Hearing Loss CompIaints

    Institute of Scientific and Technical Information of China (English)

    郭英; 周慧芳

    2015-01-01

    Objective To study the audiometry and otoacoustic emissions in patients with posterior circulation ischemia(PCI) .Methods Forty patients treated by neurologists were selected as the experimental group who re_ceived pure tone audiometry ,tympanometry ,otoacoustic emissions (OAE) and distortion products otoacoustic emis_sions (DPOAE) examinations .Thirty healthy objects were chosen as the control group .The data from the PCI groups and the control group were compared using the SPSS 14 .0 software .ResuIts The difference in pure tone thresholds across 125 to 8 000 Hz between the PCI group and the control group was not statistically significant (P>0 .05) .In the PCI patients ,the prevalence of TEOAE was only 47 .5% ,significantly different from that of in the control group .The prevalence of DPOAE at 0 .5~8 kHz were between 57 .9% ~77 .6% in PCI patients ,and the amplitudes of DPOAE were reduced significantly (P<0 .05) .ConcIusion Cochlear damages can occur to patients with PCI ,especially in the high frequency range .These results suggest that OAE can be used as an important diag_nostic test for patients with PCI ,and might be helpful for the location diagnosis of PCI .%目的:探讨自觉听力正常的后循环缺血(posterior circulation ischemia ,PCI)患者的纯音测听和耳声发射的结果及临床意义。方法选择经临床确诊为PCI且自觉听力正常的患者40例(80耳)作为实验组,健康成年人30例(60耳)作为对照组,两组均行纯音测听、瞬态诱发耳声发射(TEOAE)和畸变产物耳声发射(DPOAE)检查,对结果进行统计学分析。结果 PCI组125~8000 Hz各频率气导听阈与对照组比较差异无统计学意义( P>0.05);PCI组的TEOAE检出率(47.5%,38/80)低于对照组(95.0%,57/60),差异有统计学意义(P<0.01);PCI组DPOAE各频率检出率、幅值均低于健康对照组(P<0.05),尤以高频区明显(P<0.01)。结

  9. Emissões otoacústicas x Cisplatina: detecção precoce da ototoxicidade em pacientes oncológicos Otoacoustic emissions x Cisplatin: precocious detection of ototoxicity in oncologic patients

    OpenAIRE

    Ruysdael Zocoli; Sandro Laércio Reichow; Ângela Maria Fontana Zocoli

    2003-01-01

    Estudos mostram que existem numerosas substâncias reconhecidas como potencialmente ototóxicas e entre as principais, na classe dos medicamentos, destacam-se os quimioterápicos. OBJETIVO: o objetivo deste trabalho foi realizar um estudo da ototoxicidade através das emissões otoacústicas evocadas - produto de distorção (EOA-PD), pré e pós-aplicação do quimioterápico Cisplatina, em indivíduos adultos, moradores da cidade de Blumenau/SC. FORMA DE ESTUDO: Prospectivo clínico. MATERIAL E MÉTODO: Fo...

  10. Emissões otoacústicas por produtos de distorção em crianças de 2 a 7 anos Otoacoustic emissions by distorcion products in children of 2 to 7 years old

    Directory of Open Access Journals (Sweden)

    Alfredo R. Dell'Aringa

    2004-06-01

    Full Text Available Com a descoberta das Emissões Otoacústicas (EOA, tornou-se possível analisar e investigar as funções auditivas das células ciliadas externas do órgão da audição. Podem ser espontâneas, evocadas transientes ou por produto de distorção. O teste das EOAEs-DP caracteriza-se por ser um exame objetivo, rápido, indolor, não-invasivo e de fácil aplicação tanto para clínica como para programas de triagem auditiva. FORMA DE ESTUDO: Coorte transversal. MATERIAL E MÉTODO: Foram avaliadas 105 crianças entre 2 e 7 anos de idade da creche "Lar da Criança", de Marília, SP. A avaliação constou de exame otorrinolaringológico completo e EOAEs-DP. Todas estas crianças, após prévia autorização dos responsáveis, foram submetidas a exame otorrinolaringológico completo e EOAEs-DP. RESULTADOS: Os resultados demonstraram que das 105 crianças avaliadas, 44,76% apresentavam cerume. 12 crianças permaneceram com cerume mesmo após uso de ceruminolítico e lavagem auricular ou não apresentaram consentimento informado de seus responsáveis. Portanto, estas foram excluídas do trabalho sendo o restante, 93 crianças, submetidas a avaliação das EOAEs-DP Após a realização das EOAEs-DP, verificou-se que 5,37% das crianças apresentaram exames alterados, sendo que 60% destas eram do sexo masculino e 60% com acometimento bilateral. DISCUSSÃO: Os resultados encontrados foram inferiores aos citados na literatura, assim como o predomínio do sexo masculino. Além disso, notou-se alta prevalência de cerume nos pacientes testados. CONCLUSÃO: É essencial uma avaliação otorrinolaringológica completa prévia. O exame de EOAEs-DP pode ser realizado em crianças para detecção precoce e prevenção de falhas no desenvolvimento cognitivo e psicoemocional.With the discovery of otoacustic emissions it has begun possible to analyze the auditive functions of external hair cells in the auditive cortex. The OAE can be spontaneous transients by

  11. Latencies of extracted distortion-product otoacoustic source components

    Science.gov (United States)

    Zelle, Dennis; Thiericke, John P.; Gummer, Anthony W.; Dalhoff, Ernst

    2015-12-01

    Distortion product otoacoustic emissions (DPOAEs) evolve as a byproduct of the nonlinear amplification process of two stimulus tones f2 ≥ f1 in the cochlea. According to a prevailing model, DPOAEs comprise a nonlinear-generation and a coherent-reflection component. Recently, we introduced a new technique using short f2 pulses which enables the extraction of both source components in the time domain by nonlinear least-square curve fitting to decompose the DPOAE response into pulse basis functions (PBFs). The analysis of the extracted DPOAE source components in the time domain enables determination of their latencies which may be used to estimate cochlear frequency tuning. Short-pulse DPOAEs were acquired from 16 subjects for f2 = 1.5, 2, 3, and 4 kHz using six primary-tone levels with L2 = 25 - 65 dB SPL. For the extracted nonlinear-generation and coherent-reflection components, latencies decrease with increasing stimulus frequency and level. The obtained latency values are in accordance with the expected behavior of the cochlear amplifier and may provide an additional diagnostic parameter to assess frequency tuning.

  12. Otoproteção da amifostina aos efeitos ototóxicos da cisplatina: estudo em cobaias albinas por emissões otoacústicas produtos de distorção e microscopia eletrônica de varredura Amifostine otoprotection to cisplatin ototoxicity: a guinea pig study using otoacoustic emission distortion products (DPOEA and scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Miguel Angelo Hyppolito

    2005-06-01

    side effects of cisplatin ototoxicity are significant: irreversible bilateral hearing damage to high frequencies (4 kHz - 8 kHz. Reports recognize some drugs that are associated with cisplatin to obtain an otoprotector effect. The ototoxicity mechanisms of cisplatin are related to injury of hair cell oxidation mechanism, especially of outer hair cells. AIM: Using otoacoustic emissions distortion products (DPOEA and scanning electron microscopy we intended to verify the action of amifostine, a radioprotective drug that has well known antioxidant characteristics and otoprotector effects to cisplatin injury. STUDY DESIGN: Experimental. MATERIAL AND METHODS: We used an experimental guinea pig model. The study was performed as follows: group 1: 6 animals, 12 ears, cisplatin 8.0 mg/Kg/day (IP, 3 days. Group 2: 6 animals, 12 ears, amifostine 100 mg/Kg/day (IP and after 90 minutes, cisplatin 8.0 mg/Kg/day (IP, 3 days and group 3: 3 animals, 6 ears, amifostine 100 mg/Kg/day (IP, 3 days. RESULTS: DPOEA were present before and after treatment in groups 2 and 3. The normal cilium architecture of outer hair cells was supported in all cochlear turns in groups 2 and 3. We concluded that amifostine has a potential otoprotector effect against cisplatin ototoxicity and could be used in clinical trials.

  13. Effects of Lipoic Acid on Abnormal Distortion Product Otoacoustic Emissions Without Hearing Lose Following Blast Noise Exposure%硫辛酸对纯音听力损失前畸变产物耳声发射异常的作用及意义

    Institute of Scientific and Technical Information of China (English)

    何端军; 郭万宏; 唐建勇; 张家超; 杨静芬; 付艳秋

    2013-01-01

    Objective To investigate the effect of lipoic acid on abnormally low distortion product otoacoustic emissions (DPOAE) with no hearing loss following military noise exposure. Methods Twenty six (41ears) artillerymen,with normal pure tone hearing thresholds and abnormal DPOAEs amplitudes following military noise exposure were randomly divided into 2 groups. The test group with 13 young adults (21 ears) received intravenous drip of lipoic acid (600 mg/day). The control group with 13 young adults (20 ears) received intravenous drip of placebo. Pure tone audiomety and otoacoustic emission were per-formed on Days 2, 4, 6, 8 and 10 after treatment. Pure tone hearing thresholds and amplitudes of DPOAEs were compared and analyzed. Results Statistical analysis showed that prior to the treatment the amplitudes of DPOAE at 3, 4 , 6 and 8 kHz did not differ significantly between the two groups. DPOAE amplitudes in the control group increased significantly on the 8th day after treatment. The amplitudes in the test group increased significantly on the 4th day after treatment, with a significant differ-ence between the test and control groups. Conclusion Lipoic acid seems to significantly improve DPOAE amplitudes toward normal in individuals with subclinical auditory system impairment caused by military noise exposure.%目的观察脉冲噪声致纯音听力损失前畸变产物耳声发射(DPOAE)异常的自然转归及硫辛酸对其转归的影响。方法纯音听阈正常、DPOAE异常者26例(41耳),随机分为对照组和治疗组,每组各13例。治疗组给予硫辛酸600mg/日静滴治疗,对照组给予安慰剂治疗,治疗后第2、4、6、8、10天,分别进行纯音听阈及DPOAE检查。结果治疗前两组各对应频率的纯音听阈及DPOAE幅值均无显著差别,DPOAE异常频率主要发生在3、4、6、8kHz。经过治疗后,两组的纯音听阈无明显变化,对照组异常频率的DPOAE的幅值自第8天开始,显著大

  14. Audiological assessment value of click-evoked auditory brainstem response combined with single stimulation of the auditory steady-state evoked response on normal young people%听性脑干诱发电位结合单刺激听觉稳态诱发反应对正常青年人听阈正常值评估的探讨

    Institute of Scientific and Technical Information of China (English)

    李倩庆; 宋江顺; 刘文婷

    2013-01-01

    目的 分析正常青年人多频刺激听觉稳态诱发电位(multiple stimuli auditory steady-state response,m-ASSR)、单频刺激听觉稳态诱发电位(single stimulusauditory steady-state response,s-ASSR)、听性脑干诱发电位(click-evoked auditory brain stem response,CABR)、纯音听力测试(pure tone auditory,PTA)阈值,探讨C-ABR结合0.5、1 kHz s-ASSR在正常青年人中反应阈的正常值.方法 对听力正常青年人(43人,共86耳)分别行PTA、m-ASSR、0.5、1.0 kHz s-ASSR、C-ABR检查.将PTA、m-ASSR、听力测试组合(C-ABR结合0.5、1 kHzs-ASSR反应阈)结果行f检验、线性回归分析等统计学分析.结果 ①0.5、1、2、4 kHz处,听力测试组合反应阈高于PTA;除1 kHz外其他频率均较m-ASSR反应阈接近PTA;②0.5、1、2、4 kHz处,听力测试组合反应阈预测PTA的回归方程分别为:y=0.75x-4.53,y=0.56x-4.46,y=0.62x-7.70和y=0.92x-12.66.结论 正常青年人中ASSR反应阈与PTA、C-ABR V波反应阈有一定的差值;听力测试组合较m-ASSR更接近PTA;听力测试组合可以更准确、更可靠评估正常成年人听阈水平.

  15. 畸变产物耳声发射和纯音听力评价突发性耳聋的临床研究%Comparative study of distortion product otoacoustic emission and pure tone audiometry in the evaluation of sudden deafness

    Institute of Scientific and Technical Information of China (English)

    孙俊; 罗婷婕

    2012-01-01

    Objective To compare the effect of distortion product otoacoustic emission (DPOAE) and pure tone audiometry (PTA) in the evaluation of sudden deafness. Methods 60 patients (64 ears) with sudden deafness admitted in our hospital from 2009 to 2011 were selected and enrolled in this study. All the 60 patients received DPOAE test and PTA test before and after treatment. The results of the two kinds of tests were compared. Results After treatment, the results of DPOAE test and PTA test were all significantly better than that before treatment (P0.05). Conclusion DPOAE test can reveal the cochlear hearing function and hair functional status, which is non-invasive, fast, comprehensive and specific.%目的 探讨利用畸变产物耳声发射(DPOAE)和纯音听力评价突发性耳聋的方法和效果.方法 随机抽取我科2009-2011年收治突发性耳聋患者60例(64耳),所有患者治疗前后均接受纯音测听检查及DPOAE检测,对比两种检测方法的结果变化.结果 治疗前后比较,患者DPOAE和纯音听力检测均优于治疗前(P<0.05);治疗后两组间比较,患者DPOAE检测通过率较纯音听力检测更灵敏(P<0.05).随着患耳听力的改善,听阈恢复率、DPOAE幅值恢复率都逐步提高,但是二者的变化并不同步(P>0.05).结论 DPOAE检测可反应耳蜗听力功能和毛细胞功能状态,具有无创、快速、全面、特异的优点,能有效地指导临床治疗.

  16. Fine structures in hearing thresholds and distortion product otoacoustic emissions

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Ordoñez, Rodrigo Pizarro; Torrente, Marina;

    2010-01-01

    . Distortion product OAEs (DPOAES) are generated in response to a two-tone external stimulus with frequencies f1 and f2. One of the strongest DPOAEs is the component at 2f1-f2. This component is elicited on the basilar membrane in the overlap region of the f1 and f2, close to the f2 place (depending...... on frequency ratio and levels of the two tone stimulus). The 2f1-f2 component travels along the basilar membrane and excites activity at the 2f1-f2 place, which yields a second component with the same frequency. The resulting sound that can be recorded in the external ear canal is the superposition...

  17. Correlation between reduction of distortion product otoacoustic emission and percentage of outer hair cell missing in chinchillas%灰鼠畸变产物耳声发射改变和外毛细胞缺失程度的相关分析

    Institute of Scientific and Technical Information of China (English)

    于栋祯; 丁大连; 殷善开; Richard J Salvi

    2009-01-01

    目的 探讨灰鼠畸变产物耳声发射(DPOAE)幅值的降低与外毛细胞缺失率之间的关系.方法 联合应用顺铂和利尿酸钠,建立灰鼠耳蜗毛细胞损伤模型.12只灰鼠在静脉注射利尿酸钠(40 mg/kg)同时,腹腔注射顺铂(0.2 mg/kg),分别于用药前和用药后的1周、2周及3周在清醒状态下检测动物DPOAE,并在施行最后1次DPOAE检测后处死动物.常规制备灰鼠耳蜗基底膜铺片并进行全耳蜗毛细胞计数.计算用药前和处死前DPOAE幅值的改变程度,通过Pearson相关分析对DPOAE幅值的降低与外毛细胞缺失程度之间的相关性进行分析.结果 顺铂和利尿酸钠引起灰鼠耳蜗外毛细胞缺失的特点是病变始发于基底膜的底回并逐渐向顶回发展,外毛细胞的缺损程度沿着基底膜从底回向顶回逐渐减轻,而不同频率DPOAE幅值降低的程度亦遵循从高频向低频发展的规律,各频率DPOAE在注射顺铂和利尿酸钠后的幅值改变与基底膜上相应部位的外毛细胞缺损程度存在一定的对应关系(r=0.796,P<0.05).外毛细胞每损失1%,可引起约0.24 dB的DPOAE幅值降低.结论 在灰鼠耳蜗损伤模型中,从DPOAE幅值的变化可以大致评估耳蜗外毛细胞的缺失程度.%Objective To explore the quantitative relationship between the reduction of distortion product otoacoustic emission (DPOAE) and the percentage of outer hair cell loss. Methods Coadministration of cisplatin (0.2 mg/kg) and ethacrynic acid (40 mg/kg) were used to estabhsh a cochlear lesion model in chinchillas. DPOAE was measured before and 1 week, 2 weeks, and 3 weeks later respectively after cisplatin and ethacrynic acid treatment. Animals were terminated 3 weeks after the treatment. Cochlear surface preparations were performed, and the cochlear hair cells were counted through entire length of the cochlea. The correlation between DPOAE reduction and outer hair cell missing was analyzed using Pearson correlation analysis

  18. Cochlear contributions to the precedence effect

    DEFF Research Database (Denmark)

    Verhulst, Sarah; Bianchi, Federica; Dau, Torsten

    2013-01-01

    Normal-hearing individuals have sharply tuned auditory filters, and consequently their basilar-membrane (BM) impulse responses (IRs) have durations of several ms at frequencies in the range from 0 to 5 kHz. When presenting clicks that are several ms apart, the BM IRs to the individual clicks...... at characterizing perceptual consequences of BM IR interactions in individual listeners based on click-evoked otoacoustic emissions (CEOAEs) and auditory brainstem responses (ABRs). Lag suppression, denoting the level difference between the CEOAE or wave-V response amplitude evoked by the first and the second...

  19. 老年人听力障碍筛查量表结合畸变产物耳声发射诊断早期老年性聋%Hearing Handicap Inventory for the Elderly combined with Distortion Product Otoacoustic Emission testing in early diagnosis of presbycusis

    Institute of Scientific and Technical Information of China (English)

    雷磊; 李剑挥; 王新; 李北成

    2015-01-01

    ObjectiveTo determine the value of the Hearing Handicap Inventory for the Elderly (HHIE)-screening version and the Distortion Product Otoacoustic Emissions testing (DPOAE) in the diagnosis of early presbycusis. Methods Ninety-five elderly patients (51 males and 44 females, over 65 years old, with hearing loss for more than 1 year because of sensorineural hearing loss) admitted in the Hainan Branch of Chinese PLA General Hospital from May 2013 to October 2014 were enrolled in this study. The cohort underwent pure tone audiometry, acoustic impedance tests, DPOAE testing and was surveyed with hearing screening scale HHIE.Results For the 11 patients diagnosed as mild hearing loss by pure tone audiometry, their HHIE scored an average of (30.1±5.0) points, including 1 case≥43 points [as severe hearing impairment, accounting for 9.1% (1/11)], and the detection rate of DPOAE was 81.8%, with a threshold of (61.3±7.0) dB SPL. For the 23 patients of moderate hearing loss by pure tone audiometry, their HHIE scores were averagely (35.6±4.0) points, including 3 cases≥43 points [as severe hearing impairment, accounting for 13.0% (3/23)], and the detection rate of DPOAE was 78.3%, with a threshold of (68.3±5.0) dB SPL. For the 34 cases of moderately severe hearing loss by pure tone audiometry, their HHIE scored an average of (39.3±6.0) points, and 12 cases of them had≥43 points [as severe hearing impairment, accounting for 35.3% (12/34)], and their DPOAE detection rate was 52.9% with a threshold of (71.3±5.0) dB SPL. For the 18 cases of severe hearing loss by pure tone audiometry, their HHIE scored an average of (61.7±2.0) points, all of them were severe hearing impairment, and the DPOAE detection rate was 11.1% with a threshold of (80.4±3.0) dB SPL. For the 9 cases of extremely severe hearing loss by pure tone audiometry, their HHIE scores were (89.7±5.0) points in average, all of them were severe hearing impairment, and the DPOAE detection rate was 0

  20. Estudo da audição de crianças de gestantes expostas ao ruído ocupacional: avaliação por emissões otoacústicas - produto de distorção Study of the hearing in children born from pregnant women exposed to occupational noise: assessment by distortion product otoacoustic emissions

    OpenAIRE

    Eduardo Bezerra Rocha; Marisa Frasson de Azevedo; João Aragão Ximenes Filho

    2007-01-01

    OBJETIVO: Detectar precocemente uma possível perda auditiva em crianças de mulheres expostas ao ruído ocupacional durante o período de gestação e verificar se há diferença nos resultados das amplitudes de resposta das emissões otoacústicas - produto de distorção - entre as crianças de mães expostas ao ruído ocupacional e as crianças de mães não-expostas ao ruído ocupacional. MÉTODOS: Crianças de mulheres expostas ao ruído ocupacional durante a gestação e crianças de mulheres não-expostas fora...

  1. Characterizing and modeling dynamic processes in the cochlea using otoacoustic emissions

    DEFF Research Database (Denmark)

    Verhulst, Sarah

    2010-01-01

    , or time-dependent, properties of cochlear gain. A time scale from 0 to 10 ms is considered to ensure that cochlear processing is investigated without including influences from higher stages in the brain. The results are expected to provide insight into how e.g. onsets of sounds are processed by the intact......An important characteristic of human hearing is that it amplifies weak sounds while attenuating louder ones. This gain transformation takes place in the inner ear (i.e., cochlea), and is responsible for a compressive relation between the level of the presented and perceived sound. The cochlear gain....... Experimental results demonstrated that the CEOAE level-curve, i.e. the relation between click and CEOAE level, altered when a click was presented close in time to the evoking click. This effect was named "temporal adaptation" of the CEOAE level-curve, and was shown to operate on a time scale of 0 to 8 ms...

  2. Otoacoustic Emissions in Sudden Sensorineural Hearing Loss: Changes of Measures with Treatment

    Directory of Open Access Journals (Sweden)

    Shadman Nemati

    2011-01-01

    In TEOAEs, the mean overall correlation (reproducibility and the mean overall strength in involved ears were 10.96±23.36 and 0.99±3.45 dB, respectively, before the treatment, which reached 22.88±36.55 and 1.85±5.3, respectively, after the treatment (P>0.05. Significant difference between “correlation score” (average of correlations at 3-4 involved frequencies before and after treatment was found: 6.52 ±18.19 vs. 21.67±37.8 (P

  3. Otoacoustic Emissions in Sudden Sensorineural Hearing Loss: Changes of Measures with Treatment

    Directory of Open Access Journals (Sweden)

    Shadman Nemati

    2011-01-01

    Full Text Available Introduction: To identify changes in OAEs parameters in treatment course of idiopathic sudden sensorineural hearing loss (iSSNHL. Materials and Methods: In aprospective studyfromAugust 2005 to January 2009, 26 patients with iSSNHL underwent conventional audiometry/tympanometry and two types of OAEs (TEOAEs and DPOAEs before and after the completion of standard drug therapy.The changes in pre- and post- treatment parameters were compared with each other and with normal-contralateral ears. Results: In TEOAEs, the mean overall correlation (reproducibility and the mean overall strength in involved ears were 10.96±23.36 and 0.99±3.45 dB, respectively, before the treatment, which reached 22.88±36.55 and 1.85±5.3, respectively, after the treatment (P>0.05. Significant difference between “correlation score” (average of correlations at 3-4 involved frequencies before and after treatment was found: 6.52 ±18.19 vs. 21.67±37.8 (P

  4. Effects of glutamate on distortion-product otoacoustic emissions and auditory brainstem responses in guinea pigs

    Institute of Scientific and Technical Information of China (English)

    SUN Qing; SUN Jian-he; SHAN Xi-zheng; LI Xing-qi

    2008-01-01

    Objective To investigate changes in evoked potentials and structure of the guinea pig cochleae during whole cochlear perfusion with glutamate. Methods CM, CAP, DPOAE, and ABR were recorded as indicators of cochlear functions during whole cochlear perfusion. The morphology of the cochlea was studied via transmission electron microscopy. Results There were no significant changes in DPOAE amplitude before and after glutamate perfusion. CM I/O function remained nonlinear during perfusion. ABR latencies were delayed following glutamate perfusion. The average CAP threshold was elevated 35 dB SPL following glutamate perfusion.. The OHCs appeared normal, but the IHCs and afferent dendrites showed cytoplasmic blebs after glutamate perfusion. Conclusions While being a primary amino acid neurotransmitter at the synapses between hair cells and spiral ganglion neurons, excessive glutamate is neurotoxic and can destroy IHCs and spiral ganglion neurons. The technique used in this study can also be used to build an animal model of auditory neuropathy.

  5. A STUDY ON NEONATAL HEARING LOSS USING TRANSIENT EVOKED OTOACOUSTIC EMISSIONS

    Directory of Open Access Journals (Sweden)

    Jayaprabha

    2016-02-01

    Full Text Available Deafness is an invisible disability that may often go undetected until school age, especially in children with no additional disabilities. It affects the social, emotional and cognitive development of an individual. However, this can be overcome through early identification and intervention, for which a screening programme is mandatory. But choosing any option needs realistic assessment of the magnitude of the problem in terms of prevalence as well as the risk factors operating in that specific context. So this study was performed to plan future neonatal screening programmes at Medical College Hospital, Thiruvananthapuram. The study was conducted on 402 babies born at SAT Hospital, Medical College, Thiruvananthapuram. The prevalence of neonatal hearing loss was found to be 0.8%. Craniofacial anomalies, family history of permanent childhood hearing loss and congenital infections were found to be the significant risk factors for hearing loss.

  6. Relationship Between Distortion Product – Otoacoustic Emissions (DPOAEs) and High-Frequency Acoustic Immittance Measures

    Science.gov (United States)

    De Paula Campos, Ualace; Hatzopoulos, Stavros; Śliwa, Lech K.; Skarżyński, Piotr H.; Jędrzejczak, Wiesław W.; Skarżyński, Henryk; Carvallo, Renata Mota Mamede

    2016-01-01

    Background Pathologies that alter the impedance of the middle ear may consequently modify the DPOAE amplitude. The aim of this study was to correlate information from 2 different clinical procedures assessing middle ear status. Data from DPOAE responses (both DP-Gram and DP I/O functions) were correlated with data from multi-component tympanometry at 1000 Hz. Material/Methods The subjects were divided into a double-peak group (DPG) and a single-peak group (SPG) depending on 1000 Hz tympanogram pattern. Exclusion criteria (described in the Methods section) were applied to both groups and finally only 31 ears were assigned to each group. The subjects were also assessed with traditional tympanometry and behavioral audiometry. Results Compared to the single-peak group, in terms of the 226 Hz tympanometry data, subjects in the DPG group presented: (i) higher values of ear canal volume; (ii) higher peak pressure, and (iii) significantly higher values of acoustic admittance. DPOAE amplitudes were lower in the DPG group only at 6006 Hz, but the difference in amplitude between the DPG and SPG groups decreased as the frequency increased. Statistical differences were observed only at 1001 Hz and a borderline difference at 1501 Hz. In terms of DPOAE I/O functions, significant differences were observed only in 4 of the 50 tested points. Conclusions The 1000-Hz tympanometric pattern significantly affects the structure of DPOAE responses only at 1001 Hz. In this context, changes in the properties of the middle ear (as detected by the 1000 Hz tympanometry) can be considered as prime candidates for the observed variability in the DP-grams and the DP I/O functions. PMID:27299792

  7. Spontaneous otoacoustic emissions are generated by active oscillators clustered in frequency plateaus

    DEFF Research Database (Denmark)

    Epp, Bastian; Wit, Hero; van Dijk, Pim

    It is commonly assumed that the active process linked to hair-cell motility is an important factor contributing to SOAEs. A chain of coupled, active and nonlinear oscillators with tonotopic organization can be used to account for key aspects of cochlear processing, including SOAEs and related...... phenomena when random irregularities of the mechanical parameters (roughness) are introduced. It was hypothesized that this roughness leads to sudden impedance mismatches leading to multiple reflections of the travelling wave in the cochlea. Recently it was shown [Wit&van Dijk, 2012; J. Acoust. Soc. Am. 132......, 918–926] that a linear array of active oscillators with nearest neighbour coupling produces clusters of oscillators with a common oscillation frequency (frequency plateaus) and a preferred frequency separation. The frequency plateaus can also be entrained to the frequency of an external tone. Both of...

  8. Comparison of peripheral compression estimates using auditory steady-state responses (ASSR) and distortion product otoacoustic emissions (DPOAE)

    DEFF Research Database (Denmark)

    Encina Llamas, Gerard; Epp, Bastian; Dau, Torsten

    The healthy auditory system shows a compressive input/output (I/O) function as a result of healthy outer-hair cell function. Hearing impairment often leads to a decrease in sensitivity and a reduction of compression, mainly caused by loss of inner and/or outer hair cells. Compression is commonly...... (DPOAEs) recordings. Results show compressive ASSR I/O functions for NH subjects. For HI subjects, ASSR reveal the loss of sensitivity at low stimulus levels. Growth slopes are smaller (more compressive) in ASSR than in DPOAE I/O functions....

  9. Effectiveness of Low Level Laser Irradiation on Tinnitus and Parameters of Electrocochleography and Distortion Product Otoacoustic Emissions

    Directory of Open Access Journals (Sweden)

    Saeed Mahmoudian

    2008-06-01

    Full Text Available Background and Aim: Tinnitus is the consciousness of sound that arises in the ear or head without any external sound origin. The efficacies of transmeatal low-level laser irradiation for tinnitus treatment were reported before. The aim of this study was to evaluate the effectiveness of low level laser therapy on tinnitus and ECochG and DPOAEs parameters. Materials and Methods: The study design was prospective, quasi experimental. This investigation conducted on 16 ears (10 patients with disabling tinnitus. All patients underwent ENT examination, complete audiological evaluation, tinnitus study, ECochG and DPOAEs, and finally completing tinnitus data sheet. The results were compared before and after irradiation. Results: Means of tinnitus loudness (LMT and CAP amplitudes were significant different before and after irradiation (p<0.005. There was no any other significant difference before and after low level laser irradiation in subjective loudness, pitch matching annoyance grade of tinnitus and DPOAEs and other ECochG parameters.Conclusion: Transmeatal low-power laser irradiation with 200 mW seems not to be effective for treatment of tinnitus. This paper is the research brief report. In clinical point of view, this study should be repeated with a greater sample size although our results were statistically important.

  10. Disappearance of click-evoked potentials on the neck of the guinea pig by pharmacological and surgical destruction of the peripheral vestibular afferent system.

    Science.gov (United States)

    Matsuzaki, Masaki; Murofushi, Toshihisa

    2003-10-01

    In order to establish an animal model of acoustically evoked vestibulo-collic reflex, the so-called vestibular evoked myogenic potential in humans, potentials evoked by loud clicks on the neck of the guinea pig were recorded using subjects whose peripheral vestibular endorgans or vestibular afferents had been damaged. Four normal control guinea pigs, four guinea pigs that received an intramuscular injection of gentamicin for 20 days (90 mg/kg/day) and five guinea pigs whose vestibular nerves were surgically sectioned were used in this study. Under general anesthesia with an intraperitoneal injection of pentobarbital sodium (40 mg/kg), auditory brainstem responses (ABRs) were recorded. Then, potentials evoked by loud clicks on the pre-vertebral muscle at the level of the third cervical vertebral bone were recorded using silver ball electrodes. As a result, a distinctive negative peak (NP) with a latency of 6-8 ms was recorded in all animals in the control group. NP was not observed in the gentamicin-administered group while ABR was preserved. After sectioning the vestibular nerve, NP was abolished while ABR was preserved. From these results, NP could be of vestibular origin. These results are in agreement with a previous report of NP using subjects whose cochlea had been damaged pharmacologically.

  11. Experimental Evidence for a Cochlear Source of the Precedence Effect

    DEFF Research Database (Denmark)

    Bianchi, Federica; Verhulst, Sarah; Dau, Torsten

    2013-01-01

    The precedence effect (PE) refers to the dominance of directional information carried by a direct sound (lead) over the spatial information contained in its multiple reflections (lags) in sound localization. Although the processes underlying the PE have been largely investigated, the extent to wh...... range from 1 to 4 ms, as indicated by the suppression of the lag-CEOAE, was the source of the reduction in the lag-ABRs and a possible peripheral contributor to the PE for click stimuli.......The precedence effect (PE) refers to the dominance of directional information carried by a direct sound (lead) over the spatial information contained in its multiple reflections (lags) in sound localization. Although the processes underlying the PE have been largely investigated, the extent....... The psychoacoustical experiments, comprising a fusion task, an interaural time difference detection task and a lateralization task, demonstrated a time range from 1 to 4.6–5 ms, in which the PE operated (precedence window). Click-evoked otoacoustic emissions (CEOAEs) were recorded in both ears to investigate the lead–lag...

  12. Influence of aging on medial olivocochlear system function

    Directory of Open Access Journals (Sweden)

    Lisowska G

    2014-06-01

    Full Text Available Grazyna Lisowska, Grzegorz Namyslowski, Boguslawa Orecka, Maciej MisiolekDepartment of Otolaryngology, Medical University of Silesia, Zabrze, PolandBackground: There is still controversy regarding the influence of aging on medial olivocochlear (MOC system function. The main objective of this study is to measure age-related changes of MOC system function in people with normal hearing thresholds.Method: Bilateral assessment of the MOC effect for click-evoked otoacoustic emissions (CEOAEs; at 70±3 dB peak sound pressure level [pSPL], click at 50/second, 260 repeats, 2.5–20 millisecond window and for distortion product otoacoustic emissions (DPOAEs; with [frequencies] f2/f1=1.22, [levels of primary tones] L1=65 dB SPL and L2=55 dB SPL; DP-grams for 2f1-f2 were collected for the f1 frequencies varying from 977 Hz to 5,164 kHz, with the resolution of four points per octave was performed in a group of 146 (n=292 ears healthy, right-handed subjects aged from 10–60 years with a bilateral hearing threshold from 0.25–4.0 kHz, not exceeding 20 dB hearing level; normal tympanograms; and a threshold of the contralateral stapedial reflex for broadband noise (BBN of 75 dB SPL or higher. The MOC inhibition was assessed on the basis of changes in OAE level during BBN contralateral stimulation at 50 dB sensation level (mean, 65±3 dB SPL.Results: Comparative analysis of the MOC effect for CEOAE and DPOAE showed the weakest effect in the oldest age group (41–60 years at almost all tested frequencies. Moreover, a weak, albeit significant, positive correlation between the level of OAE and the size of the MOC effect was documented.Conclusion: On the basis of our study, we have found a decrease in the strength of the MOC system with increasing age in normally hearing subjects, as reflected by a decrease of the OAE suppression effects in older individuals and an increase of the number of CEOAE and DPOAE enhancements during contralateral

  13. Emission Trading

    OpenAIRE

    Kmoch, Daniel

    2009-01-01

    The work concerns Emission Trading Scheme from perspektive of taxes and accounting. I should show problems with emission trading. The work concerns practical example of trading with emission allowance.

  14. Emissions Trading

    NARCIS (Netherlands)

    Woerdman, Edwin; Backhaus, Juergen

    2014-01-01

    Emissions trading is a market-based instrument to achieve environmental targets in a cost-effective way by allowing legal entities to buy and sell emission rights. The current international dissemination and intended linking of emissions trading schemes underlines the growing relevance of this instr

  15. Emission Facilities - Air Emission Plants

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Represents the Primary Facility type Air Emission Plant (AEP) point features. Air Emissions Plant is a DEP primary facility type related to the Air Quality Program....

  16. Emission inventory; Inventaire des emissions

    Energy Technology Data Exchange (ETDEWEB)

    Fontelle, J.P. [CITEPA, Centre Interprofessionnel Technique d`Etudes de la Pollution Atmospherique, 75 - Paris (France)

    1997-12-31

    Statistics on air pollutant (sulfur dioxide, nitrogen oxides and ammonium) emissions, acid equivalent emissions and their evolution since 1990 in the various countries of Europe and the USA, are presented. Emission data from the industrial, agricultural, transportation and power sectors are given, and comparisons are carried out between countries based on Gnp and population, pollution import/export fluxes and compliance to the previous emission reduction objectives

  17. Loud click-evoked masseter myogenic potentials in alert guinea pigs%强短声诱发的清醒豚鼠咬肌肌源性电位

    Institute of Scientific and Technical Information of China (English)

    谢溯江; 贾宏博; 杨伟炎; 陈勇胜; 张素珍; 毕红哲; 武留信; 胡吟燕; 田大为

    2006-01-01

    目的 建立强短声诱发的咬肌肌源性电位的豚鼠模型,并确定该电位的起源. 方法 17只豚鼠随机分成3组,正常对照组5只;5只豚鼠以450mg/kg剂量每天肌注阿米卡星1次,持续注射18d,以选择性药物破坏耳蜗;5只豚鼠左侧圆窗区滴注庆大霉素0.05ml(40mg/ml)以选择性破坏前庭,另有2只豚鼠左侧圆窗区滴注生理盐水0.05ml以作为听泡开窗的对照.3组动物分别进行冷热实验、强短声诱发的咬肌肌源性电位以及听性脑干反应(ABR)测试. 结果 正常对照组豚鼠,120、110、100和90dB单耳声刺激,单侧记录到的豚鼠咬肌肌源性电位的反应率分别为100%、90%、70%和0%.120、110 和 100dB声刺激诱发的肌源性电位的正负波的潜伏期分别为6.73±0.59ms和8.84±0.56ms,6.80±0.43ms和8.92±0.48ms,以及 6.94±0.49ms和9.00±0.51ms.平均峰间幅度分别为6.23±2.37 μV、6.12±2.24 μV和6.36±3.13 μV,刺激强度对豚鼠的咬肌肌源性电位的平均潜伏期或峰间幅度无显著影响.采用庆大霉素单侧处理的豚鼠,损伤侧的冷热反应均缺失,而ABR阈值却正常,其损伤同侧声刺激诱发的咬肌肌源性电位缺失.阿米卡星处理组豚鼠冷热实验正常,双侧ABR阈值显著增加,但短声诱发的咬肌肌源性电位均存在. 结论 豚鼠强短声诱发的咬肌肌源性电位来源于前庭而非耳蜗.

  18. Development of distortion product emissions in the gerbil: "filter" response and signal delay.

    Science.gov (United States)

    Mills, D M; Rubel, E W

    1997-01-01

    Amplitude and phase responses of distortion product otoacoustic emissions as a function of stimulus frequency ratio were measured for frequencies between 2 and 48 kHz, in Mongolian gerbils (Meriones unguiculates) aged 15 to 30 days after birth. After baseline measurements, furosemide was administered to distinguish active from passive emissions. At all ages, structure in the form of multiple peaks was observed in the amplitude responses of specific odd-order emissions. This structure depended on the emission frequency, not the stimulus frequency ratio, and did not generally depend on the stimulus amplitude. Nor was it dependent on the functioning of the cochlear amplifier: At moderate stimulus levels, the observed emission distribution simply shifted to lower amplitudes when the cochlear amplifier was made temporarily dysfunctional by furosemide injection. The center frequencies and widths of the peaks in the amplitude response did not generally change with age, except that the relative amplitudes of the higher-frequency peaks were increased in younger animals. At 2 kHz, however, the distribution showed other evidence of maturation, with the frequency of maximum emission moving downward with age. The phase responses yielded estimates of the round trip signal (group or traveling wave) delay. At a given frequency, the active signal delay typically decreased substantially with increasing stimulus level. However, there was a rapid variation in delay as the stimulus level passed the normal active-passive crossover level. At stimulus levels measured relative to the active-passive crossover level, i.e., either 20 or 30 dB lower, the active signal delay decreased only slightly with age. Overall, both filter response and signal delay characteristics were found to be essentially mature near the onset of hearing. PMID:9000732

  19. Acoustic emission

    International Nuclear Information System (INIS)

    This paper is related to our activities on acoustic emission (A.E.). The work is made with different materials: metals and fibre reinforced plastics. At present, acoustic emission transducers are being developed for low and high temperature. A test to detect electrical discharges in electrical transformers was performed. Our experience in industrial tests to detect cracks or failures in tanks or tubes is also described. The use of A.E. for leak detection is considered. Works on pattern recognition of A.E. signals are also being performed. (Author)

  20. Objective low-frequency audiometry by distortion-product acoustic emissions.

    Science.gov (United States)

    Bonfils, P; Avan, P; Londero, A; Trotoux, J; Narcy, P

    1991-10-01

    The aim of this study was to measure distortion-product otoacoustic emissions (DPOEs) in a clinical setting. First, DPOE input-output functions were automatically realized to determine the ratio of the pure tones (primaries) f2 and f1 that would elicit the most significant DPOE input-output function. The DPOE input-output functions presented two separate portions for the f2/f1 ratio, ranging from 1.18 to 1.26: (1) below 60-dB sound pressure level (SPL), a saturating portion with a DPOE detection threshold at 36-dB SPL; and (2) above 66-dB SPL, a linear portion. For other f2/f1 ratios, DPOE input-output functions had a more linear behavior. The DPOEs generated by primary intensities below 60-dB SPL, which show saturating behavior, probably have their origin in the properties of outer hair cells. This indicates that DPOE measurements in a clinical setting must be realized with precise stimulus values: (1) f2/f1 ratio near 1.22, and (2) primary intensities below 60-dB SPL. Second, DPOE input-output functions were realized for DPOEs varying from 707.5 to 342 Hz. No more saturating plateau could be observed with DPOEs below 512.5 Hz, suggesting that active mechanisms are absent below 725 Hz within the human cochlea. These data permit us to establish the bases of an objective low-frequency audiometric test. PMID:1910706

  1. Is Emission Trading Beneficial?

    OpenAIRE

    ISHIKAWA Jota; Kiyono, Kazuharu; YOMOGIDA Morihiro

    2011-01-01

    We develop a two-country (North and South), two-good, general equilibrium model of international trade in goods and explore the effects of domestic and international emission trading under free trade in goods. Whereas domestic emission trading in North may result in carbon leakage by expanding South’s production of the emission-intensive good, international emission trading may induce North to expand the production of the emission-intensive good by importing emission permits. Emission trading...

  2. Is Emission Trading Beneficial?

    OpenAIRE

    ISHIKAWA Jota; Kiyono, Kazuharu; YOMOGIDA Morihiro

    2011-01-01

    We develop a two-country (North and South), two-good, general equilibrium model of international trade in goods and explore the effects of domestic and international emission trading under free trade in goods. Whereas domestic emission trading in North may result in carbon leakage by expanding South's production of the emission-intensive good, international emission trading may induce North to expand the production of the emission-intensive good by importing emission permits. Emission trading...

  3. Emission Inventory for Fugitive Emissions in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2007. The inventory of fugitive emissions includes CO2, CH4, N2O, NOx, CO, NMVOC, SO2, dioxin, PAH and particulate matter. In 2007 the total Danish emission of greenhouse...... gasses was 66 641 Gg CO2-eqvivalents. Fugitive emissions from fuels account for 496 Gg CO2-eqvivalents or approximately 1 %. The major part of the fugitive emissions are emitted as CO2 (74 %) due to flaring of oil and gas. The major source of fugitive CH4 emission is extraction of oil and gas...... in the North Sea, refining of oil and loading of oil onto ships both offshore and onshore. The fugitive emissions of NMVOC originate for the major part from extraction, loading of ships, transmission and distribution of oil and to a much lesser degree from natural gas and fugitive emissions from gas stations...

  4. Criteria Air Emissions Trends

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Air Emissions Trends site provides national trends of criteria pollutant and precursor emissions data based on the the National Emissions Inventory (NEI) from...

  5. Control of Emissions

    Science.gov (United States)

    Parrish, Clyde F. (Inventor); Chung, Landy (Inventor)

    2013-01-01

    Methods and apparatus utilizing chlorine dioxide and hydrogen peroxide are useful to reduce NOx emissions, as well as SOx and mercury (or other heavy metal) emissions, from combustion flue gas streams.

  6. National Emission Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The National Emission Inventory contains measured, modeled, and estimated data for emissions of all known source categories in the US (stationary sources, fires,...

  7. Pulse emission mechanisms

    OpenAIRE

    Melrose, Don

    2003-01-01

    High-energy and radio emission mechanisms for pulsars are reviewed. The source region for high energy emission remains uncertain. Two preferred radio emission mechanism are identified. Some difficulties may be resolved by appealing to nonstationary pair creation distributed widely in height.

  8. International emissions trading

    DEFF Research Database (Denmark)

    Boom, Jan Tjeerd

    This thesis discusses the design and political acceptability of international emissions trading. It is shown that there are several designs options for emissions trading at the national level that have a different impact on output and thereby related factors such as employment and consumer prices....... The differences in impact of the design make that governments may prefer different designs of emissions trading in different situations. The thesis furthermore establishes that international emissions trading may lead to higher overall emissions, which may make it a less attractive instrument....

  9. Low Emissions Aftertreatment and Diesel Emissions Reduction

    Energy Technology Data Exchange (ETDEWEB)

    None

    2005-05-27

    Detroit Diesel Corporation (DDC) has successfully completed a five-year Low Emissions Aftertreatment and Diesel Emissions Reduction (LEADER) program under a DOE project entitled: ''Research and Development for Compression-Ignition Direct-Injection Engines (CIDI) and Aftertreatment Sub-Systems''. The objectives of the LEADER Program were to: Demonstrate technologies that will achieve future federal Tier 2 emissions targets; and Demonstrate production-viable technical targets for engine out emissions, efficiency, power density, noise, durability, production cost, aftertreatment volume and weight. These objectives were successfully met during the course of the LEADER program The most noteworthy achievements in this program are listed below: (1) Demonstrated Tier 2 Bin 3 emissions target over the FTP75 cycle on a PNGV-mule Neon passenger car, utilizing a CSF + SCR system These aggressive emissions were obtained with no ammonia (NH{sub 3}) slip and a combined fuel economy of 63 miles per gallon, integrating FTP75 and highway fuel economy transient cycle test results. Demonstrated feasibility to achieve Tier 2 Bin 8 emissions levels without active NOx aftertreatment. (2) Demonstrated Tier 2 Bin 3 emissions target over the FTP75 cycle on a light-duty truck utilizing a CSF + SCR system, synergizing efforts with the DOE-DDC DELTA program. This aggressive reduction in tailpipe out emissions was achieved with no ammonia slip and a 41% fuel economy improvement, compared to the equivalent gasoline engine-equipped vehicle. (3) Demonstrated Tier 2 near-Bin 9 emissions compliance on a light-duty truck, without active NOx aftertreatment devices, in synergy with the DOE-DDC DELTA program. (4) Developed and applied advanced combustion technologies such as ''CLEAN Combustion{copyright}'', which yields simultaneous reduction in engine out NOx and PM emissions while also improving engine and aftertreatment integration by providing favorable

  10. Emissões otoacústicas por produtos de distorção na paralisia de Bell Distortion product otoacustic emissions in Bell's palsy

    Directory of Open Access Journals (Sweden)

    Cristiane A. Kasse

    2002-10-01

    Full Text Available Introdução: O núcleo do nervo facial e do núcleo olivar superior são conectados por fibras, desta forma uma lesão nesta conecção poderia interferir na função das células ciliadas externas, alterando o exame de emissão otoacústica por produtos de distorção (EOAPD. Objetivo: Observar a possibilidade da paralisia de Bell afetar a função das células ciliadas externas através da EOAPD. Forma do Estudo: Prospectivo clínico. Material e Método: Quarenta pacientes com paralisia de Bell foram comparados com 69 pacientes normais (grupo controle, usando EOAPD. Resultados: Os pacientes com paralisia de Bell e EOAPD alterados foram de 17,5% e no grupo controle de 7,2%, sem diferença estatística entre os valores. Não se observou também uma correlação entre o reflexo estapediano e o grau da paralisia facial com a EOAPD. Conclusão: Não observamos correlação entre EOAPD e a paralisia de Bell.Introduction: The facial nucleus and olivar nucleus are connected with fibers, then a lesion in this conection could interfer in the outer cell function changing the result of otoacoustic emission product distortion test (DPOE. Objective: To observe the possibility of Bell's palsy affect the function of outer hair cells, using the DPOE test. Study Design: Prospective clinical. Material and Method: Forty patients with Bell's palsy were compared with 69 patients without symptons (control group using DPOE. Results: The patients with Bell's palsy without DPOE response were 17.5% and in the control group, 7.2%, without statistical difference between them. We did not observe a correlation with stapedium reflex and degree of palsy and DPOE. Conclusion: There was no correlation with Bell's palsy and DPOE.

  11. Electrical modulation of emissivity

    OpenAIRE

    Vassant, Simon; Moldovan Doyen, Ioana Cristina; Marquier, François; Pardo, F.; Gennser, Ulf; Cavanna, Antonella; Pelouard, Jean-Luc; Greffet, Jean-Jacques

    2013-01-01

    We demonstrate that it is possible to modulate the thermal emission through an electrical modulation of the emissivity. The basic idea is to design a device where absorption is due to a resonant phenomenon. If the resonance can be electrically controlled, then absorption and, therefore, thermal emission can be controlled. We demonstrate this general concept using THz resonant absorption by surface phonon polaritons coupled through a gold grating. In our device, absorption is mostly due to a s...

  12. Global Seabird Ammonia Emissions

    Science.gov (United States)

    Riddick, S. N.; Blackall, T. D.; Dragosits, U.; Daunt, F. H.; Braban, C. F.; Tang, Y. S.; Trathan, P.; Wanless, S.; Sutton, M. A.

    2010-12-01

    Seabird colonies represent a major source of atmospheric ammonia (NH3) in remote coastal and marine systems in temperate, tropical and polar regions. Previous studies have shown that NH3 emissions from Scottish seabird colonies were substantial - of similar magnitude to the most intensive agricultural point source emissions. The UK data were used to model global seabird NH3 emissions and suggested that penguins are a major source of emissions on and around the Antarctic continent. The largest seabird colonies are in the order of millions of seabirds. Due to the isolation of these colonies from anthropogenic nitrogen sources, they may play a major role in the nitrogen cycle within these ecosystems. A global seabird database was constructed and used in conjunction with a species-specific seabird bioenergetics model to map the locations of NH3 emissions from seabird colonies. The accuracy of the modelled emissions was validated with field data of NH3 emissions measured at key seabird colonies in different climatic regions of the world: temperate (Isle of May, Scotland), tropical (Ascension Island) and polar (Signy Island, South Georgia). The field data indicated good agreement between modelled and measured NH3 emissions. The measured NH3 emissions also showed the variability of emission with climate. Climate dependence of seabird NH3 emissions may have further implications under a changing global climate. Seabird colonies represent NH3 emission ‘hotspots’, often far from anthropogenic sources, and are likely to be the major source of nitrogen input to these remote coastal ecosystems. The direct manuring by seabirds at colony locations may strongly influence species richness and biodiversity. The subsequent volatilisation and deposition of NH3 increases the spatial extent of seabird influence on nitrogen cycling in their local ecosystem. As many seabird populations are fluctuating due to changing food supply, climate change or anthropogenic pressures, these factors

  13. Ammonia emissions in Europe

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.

    2012-01-01

    The NEC (National Emission Ceiling) directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries...... technology is adopted quicker and that the farm has the right location. It is concluded that the new application process so far has not lived up to the high expectations at the outset. Despite this, the paper concludes that Denmark is likely to reduce emission by 50% from 1990 to 2020 and reach the likely...

  14. VOC emissions chambers

    Data.gov (United States)

    Federal Laboratory Consortium — In order to support the development of test methods and reference materials for volatile organic compounds (VOC) emissions from building materials and furnishings,...

  15. Smokestack emission control apparatus

    International Nuclear Information System (INIS)

    A smokestack emissions control device is mounted to a smokestack, or the like, to clean and cool the emissions from the stack. The apparatus includes a housing shaped to be mounted on top of an emission stack and has a liquid tank formed in the housing for supporting a liquid therein. The tank is mounted directly in the passageway of escaping emissions to force the emissions through the liquid. A tank baffle extends into the liquid tank and into a liquid therein to force the escaping emissions from the smokestack through the liquid. A reduced pressure chamber is located adjacent to the liquid tank to create a negative pressure on one side of the liquid in the tank to draw the smokestack emissions through the liquid. A separator is located near the base of the stack wit pipes connecting the separator to the liquid bath for circulating the liquid in the liquid tank. the liquid in the bath can be specially formulated for the particular emissions from the emission stack. Anti-foaming and bubbling means are included to prevent the liquid from forming out of the tank. The tank is lightweight and allows the entire apparatus to be placed on an existing exhaust stack

  16. Graphene field emission devices

    OpenAIRE

    DUESBERG, GEORG

    2014-01-01

    PUBLISHED Graphene field emission devices are fabricated using a scalable process. The field enhancement factors, determined from the Fowler-Nordheim plots, are within few hundreds and match the theoretical predictions. The devices show high emission current density of ∼10 nA μm−1 at modest voltages of tens of volts. The emission is stable with time and repeatable over long term, whereas the noise in the emission current is comparable to that from individual carbon nanotubes emitting under...

  17. Toluene emissions from plants

    Science.gov (United States)

    Heiden, A. C.; Kobel, K.; Komenda, M.; Koppmann, R.; Shao, M.; Wildt, J.

    The emission of toluene from different plants was observed in continuously stirred tank reactors and in field measurements. For plants growing without stress, emission rates were low and ranged from the detection limit up to 2·10-16 mol·cm-2·s-1. Under conditions of stress, the emission rates exceeded 10-14 mol·cm-2·s-1. Exposure of sunflower (Helianthus annuus L. cv. Gigantheus) to 13CO2 resulted in 13C-labeling of the emitted toluene on a time scale of hours. Although no biochemical pathway for the production of toluene is known, these results indicate that toluene is synthesized by the plants. The emission rates of toluene from sunflower are dependent on nutrient supply and wounding. Since α-pinene emission rates are also influenced by these factors, toluene and α-pinene emissions show a high correlation. During pathogen attack on Scots pines (Pinus sylvestris L.) significant toluene emissions were observed. In this case emissions of toluene and α-pinene also show a good correlation. Toluene emissions were also found in field experiments with pines using branch enclosures.

  18. Outsourcing CO2 Emissions

    Science.gov (United States)

    Davis, S. J.; Caldeira, K. G.

    2009-12-01

    CO2 emissions from the burning of fossil fuels are the primary cause of global warming. Much attention has been focused on the CO2 directly emitted by each country, but relatively little attention has been paid to the amount of emissions associated with consumption of goods and services in each country. This consumption-based emissions inventory differs from the production-based inventory because of imports and exports of goods and services that, either directly or indirectly, involved CO2 emissions. Using the latest available data and reasonable assumptions regarding trans-shipment of embodied carbon through third-party countries, we developed a global consumption-based CO2 emissions inventory and have calculated associated consumption-based energy and carbon intensities. We find that, in 2004, 24% of CO2 emissions are effectively outsourced to other countries, with much of the developed world outsourcing CO2 emissions to emerging markets, principally China. Some wealthy countries, including Switzerland and Sweden, outsource over half of their consumption-based emissions, with many northern Europeans outsourcing more than three tons of emissions per person per year. The United States is both a big importer and exporter of emissions embodied in trade, outsourcing >2.6 tons of CO2 per person and at the same time as >2.0 tons of CO2 per person are outsourced to the United States. These large flows indicate that CO2 emissions embodied in trade must be taken into consideration when considering responsibility for increasing atmospheric greenhouse gas concentrations.

  19. Air Emission Inventory for the INEEL -- 1999 Emission Report

    Energy Technology Data Exchange (ETDEWEB)

    Zohner, Steven K

    2000-05-01

    This report presents the 1999 calendar year update of the Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory (INEEL). The INEEL Air Emission Inventory documents sources and emissions of nonradionuclide pollutants from operations at the INEEL. The report describes the emission inventory process and all of the sources at the INEEL, and provides nonradionuclide emissions estimates for stationary sources.

  20. Otoproteção da amifostina aos efeitos ototóxicos da cisplatina: estudo em cobaias albinas por emissões otoacústicas produtos de distorção e microscopia eletrônica de varredura Amifostine otoprotection to cisplatin ototoxicity: a guinea pig study using otoacoustic emission distortion products (DPOEA) and scanning electron microscopy

    OpenAIRE

    Miguel Angelo Hyppolito; Antonio A. de Oliveira; Ricardo Miranda Lessa; Maria Rossato

    2005-01-01

    A Cisplatina é uma potente droga antineoplásica, largamente utilizada para o tratamento do câncer, tanto em adultos quanto em crianças. Dentre seus efeitos colaterais, a ototoxicidade se apresenta como um dos mais importantes e leva à perda auditiva irreversível, bilateral, para as altas freqüências (4KHz -8KHz). Estudos têm tentado identificar drogas que, associadas à cisplatina, possam atuar como otoprotetores. Sabe-se que o mecanismo da ototoxicidade pela cisplatina está relacionado a alte...

  1. Poultry housing emissions perspective

    Science.gov (United States)

    Concerns for climate change are expanding interest in greenhouse gas (GHG) emissions from all agricultural sectors; animal production systems are no exception. The focus of this overview is to compare emission factors among egg and meat bird poultry operations, specifically layer and broiler chicke...

  2. Uncertainties in emission inventories

    NARCIS (Netherlands)

    Aardenne, van J.A.

    2002-01-01

    Emission inventories provide information about the amount of a pollutant that is emitted to the atmosphere as a result of a specific anthropogenic or natural process at a given time or place. Emission inventories can be used for either policy or scientific purposes. For policy purpose

  3. India Co2 Emissions

    Science.gov (United States)

    Sharan, S.; Diffenbaugh, N. S.

    2010-12-01

    Is there a way to find a balance between improving living conditions for the people on the margins and also reducing emissions while limiting our negative impacts on the climate? This is a critical question today because there are many arguments between developed and developing countries about who is responsible for global warming. Developed countries believe that it is the poor countries because they are not educated enough to know about how they are affecting the climate. While the developing countries hold wealthy nations responsible because they are using the most resources. However it is important to acknowledge the fact that if there was no gap in between the developed and developing countries our emissions total would be much higher. This “gap” has been a natural controlling factor in climate change. This is why I wanted to see if I could plot what it would look like if a developing country such as India were to produce emissions that the US or Switzerland or Norway are producing as developed countries. India has a population total of 1.1 billion compared to the US with only 298 million, Switzerland with 7.5 million, and Norway with 4.6 million people. When the population is compared to the emissions output in metric tons, per capita, India produced the least emissions out of these countries, 1.4 tons per person while having the second largest population in the world, while the US produced 19 tons per capita, Switzerland produced 5.6 and Norway produced 8.7 tons per capita in 2006. The emissions rate is growing every year and increases widely and globally. If India was producing emissions that equal Norway, Switzerland and the US the total emissions it would be producing annually would be 9 billion for Norway, 6 billion for Switzerland and 20 billion emissions for the US, all in the year 2006 alone. This shows how the balance between countries with huge populations and very little emission output and average population and high emission out put has

  4. Emissivity of microstructured silicon.

    Science.gov (United States)

    Maloney, Patrick G; Smith, Peter; King, Vernon; Billman, Curtis; Winkler, Mark; Mazur, Eric

    2010-03-01

    Infrared transmittance and hemispherical-directional reflectance data from 2.5 to 25 microm on microstructured silicon surfaces have been measured, and spectral emissivity has been calculated for this wavelength range. Hemispherical-total emissivity is calculated for the samples and found to be 0.84 before a measurement-induced annealing and 0.65 after the measurement for the sulfur-doped sample. Secondary samples lack a measurement-induced anneal, and reasons for this discrepancy are presented. Emissivity numbers are plotted and compared with a silicon substrate, and Aeroglaze Z306 black paint. Use of microstructured silicon as a blackbody or microbolometer surface is modeled and presented, respectively.

  5. Emission sources and quantities

    International Nuclear Information System (INIS)

    The paper examines emission sources and quantities for SO2 and NOx. Natural SO2 is released from volcanic sources and to a much lower extent from marsh gases. In nature NOx is mainly produced in the course of the chemical and bacterial denitrification processes going on in the soil. Manmade pollutants are produced in combustion processes. The paper concentrates on manmade pollution. Aspects discussed include: mechanism of pollution development; manmade emission sources (e.g. industry, traffic, power plants and domestic sources); and emission quantities and forecasts. 11 refs., 2 figs., 5 tabs

  6. National Greenhouse Gas Emission Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The National Greenhouse Gas Emission Inventory contains information on direct emissions of greenhouse gases as well as indirect or potential emissions of greenhouse...

  7. Emissivity: A Program for Atomic Emissivity Calculations

    OpenAIRE

    Sochi, Taha

    2009-01-01

    In this article we report the release of a new program for calculating the emissivity of atomic transitions. The program, which can be obtained with its documentation from our website www.scienceware.net, passed various rigorous tests and was used by the author to generate theoretical data and analyze observational data. It is particularly useful for investigating atomic transition lines in astronomical context as the program is capable of generating a huge amount of theoretical data and comp...

  8. National Emission Inventory (NEI)

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data exchange allows states to submit data to the US Environmental Protection Agency's National Emissions Inventory (NEI). NEI is a national database of air...

  9. Photon enhanced thermionic emission

    Science.gov (United States)

    Schwede, Jared; Melosh, Nicholas; Shen, Zhixun

    2014-10-07

    Photon Enhanced Thermionic Emission (PETE) is exploited to provide improved efficiency for radiant energy conversion. A hot (greater than 200.degree. C.) semiconductor cathode is illuminated such that it emits electrons. Because the cathode is hot, significantly more electrons are emitted than would be emitted from a room temperature (or colder) cathode under the same illumination conditions. As a result of this increased electron emission, the energy conversion efficiency can be significantly increased relative to a conventional photovoltaic device. In PETE, the cathode electrons can be (and typically are) thermalized with respect to the cathode. As a result, PETE does not rely on emission of non-thermalized electrons, and is significantly easier to implement than hot-carrier emission approaches.

  10. 2011 NATA - Emissions Sources

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset includes all emissions sources that were modeled in the 2011 National Air Toxics Assessment (NATA), inlcluding point, nonpoint, and mobile sources, and...

  11. The Carbon Emission Game

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    When Chinese President Hu Jintao attended the UN climate summit on September22,he made a solemn commitment that China will cut its per GDP unit carbon emission to a significant amount in 2020 compared with that of 2005.

  12. Polarization Dependence of Emissivity

    OpenAIRE

    J, David; Strozzi,, A.G.; McDonald, Kirk T.

    2000-01-01

    We deduce the emissivity of radiation from a metallic surface as a function of angle and polarization. This effect has found application in the calibration of detectors for cosmic microwave background radiation.

  13. Galactic Diffuse Polarized Emission

    Indian Academy of Sciences (India)

    Ettore Carretti

    2011-12-01

    Diffuse polarized emission by synchrotron is a key tool to investigate magnetic fields in the Milky Way, particularly the ordered component of the large scale structure. Key observables are the synchrotron emission itself and the RM is by Faraday rotation. In this paper the main properties of the radio polarized diffuse emission and its use to investigate magnetic fields will be reviewed along with our current understanding of the galactic magnetic field and the data sets available. We will then focus on the future perspective discussing RM-synthesis – the new powerful instrument devised to unlock the information encoded in such an emission – and the surveys currently in progress like S-PASS and GMIMS.

  14. DC field emission

    International Nuclear Information System (INIS)

    The field emission project at the University of Geneva aims on the one hand at the understanding of the physical mechanism of the Enhanced Field Emission (EFE) which today is still unclear and on the other hand at the controlled production and elimination of field emitting sites. The experimental system basically consists of a UHV apparatus including Scanning Auger, SEM, and a specially constructed precision sample manipulator allowing to obtain field emission (FE) scans over 12 mm diameter cathodes at fields of 100 MV/m and higher. Also, FE sites can be localized with micrometer precision and analyzed in situ. With this experimental facility, the effect of heat treatment on niobium has been studied, and it has been found that heat treatment at high temperatures (> 10000C) reliably reduces EFE. Completely emission-free cathodes at 100 MV/m are regularly obtained. Heat treatments at 6000C ≤ T ≤ 8000C makes new FE sites appear, even from emission-free cathodes. These emission sites are predominantly carbon (graphite) and MoS2 particles. Experiments on artificially deposited graphite and MoS2 particles have shown that it is possible to locally create emitters which are similar to the natural emitters: field enhancement factors β of 100 and higher from micron size particles or submicron features can be obtained. Typical emitting particles of these materials have been found to reflect the two-dimensional crystal structure: they appear as thin, bright flakes under the SEM. 6 references

  15. Practical acoustic emission testing

    CERN Document Server

    2016-01-01

    This book is intended for non-destructive testing (NDT) technicians who want to learn practical acoustic emission testing based on level 1 of ISO 9712 (Non-destructive testing – Qualification and certification of personnel) criteria. The essential aspects of ISO/DIS 18436-6 (Condition monitoring and diagnostics of machines – Requirements for training and certification of personnel, Part 6: Acoustic Emission) are explained, and readers can deepen their understanding with the help of practice exercises. This work presents the guiding principles of acoustic emission measurement, signal processing, algorithms for source location, measurement devices, applicability of testing methods, and measurement cases to support not only researchers in this field but also and especially NDT technicians.

  16. Emission control system

    Science.gov (United States)

    Parrish, Clyde F. (Inventor); Chung, J. Landy (Inventor)

    2009-01-01

    Methods and apparatus utilizing hydrogen peroxide are useful to reduce SOx and mercury (or other heavy metal) emissions from combustion flue gas streams. The methods and apparatus may further be modified to reduce NOx emissions. Continuous concentration of hydrogen peroxide to levels approaching or exceeding propellant-grade hydrogen peroxide facilitates increased system efficiency. In this manner, combustion flue gas streams can be treated for the removal of SOx and heavy metals, while isolating useful by-products streams of sulfuric acid as well as solids for the recovery of the heavy metals. Where removal of NOx emissions is included, nitric acid may also be isolated for use in fertilizer or other industrial applications.

  17. Carbon emissions control strategies

    International Nuclear Information System (INIS)

    This study was undertaken to address a fundamental issue: the cost of slowing climate change. Experts in eight nations were asked to evaluate, using the best economic models available, the prospects for reducing fossil fuel-based carbon emissions in their respective nations. The nations selected as case studies include: the Soviet Union, Poland, the United States, Japan, Hungary, France, the United Kingdom, and Canada. As important contributors to the greenhouse effect, these industrialized nations must find ways to substantially reduce their emissions. This is especially critical given that developing nations' emissions are expected to rise in the coming decades in the search for economic development. Ten papers have been processed separately for inclusion in the appropriate data bases

  18. Emissivity of microstructured silicon.

    Science.gov (United States)

    Maloney, Patrick G; Smith, Peter; King, Vernon; Billman, Curtis; Winkler, Mark; Mazur, Eric

    2010-03-01

    Infrared transmittance and hemispherical-directional reflectance data from 2.5 to 25 microm on microstructured silicon surfaces have been measured, and spectral emissivity has been calculated for this wavelength range. Hemispherical-total emissivity is calculated for the samples and found to be 0.84 before a measurement-induced annealing and 0.65 after the measurement for the sulfur-doped sample. Secondary samples lack a measurement-induced anneal, and reasons for this discrepancy are presented. Emissivity numbers are plotted and compared with a silicon substrate, and Aeroglaze Z306 black paint. Use of microstructured silicon as a blackbody or microbolometer surface is modeled and presented, respectively. PMID:20197803

  19. Emission tomography: Physical aspects

    International Nuclear Information System (INIS)

    Two different approaches have been followed: i/ tomography by single gamma-photon counting (SPC), using either conventional scintillation cameras or specially designed detector arrays. These systems use radionuclides which are readily available commercially (99 mTc, 131 I, 201 Tl); ii/ positron-emission tomography (ACD) which relies on the simultaneous and colinear emission of two 511 keV gamma photons, permitting a higher detection efficiency and effective 'electronic collimation'. These factors give good spatial resolution and quantitative precision. The principal positron-emitting isotopes 11 C, 13 N, 150 O can also serve as tracers in a very wide range of biological processes. (orig./VJ)

  20. On the Limitations of the Anomalous Microwave Emission Emissivity

    OpenAIRE

    Roberta Paladini; Tibbs, Christopher T.; Clive Dickinson

    2012-01-01

    Many studies of anomalous microwave emission (AME) have computed an AME emissivity to compare the strength of the AME detected in different regions. Such a value is usually defined as the ratio between the intensity of the AME at 1 cm and the thermal dust emission at 100 \\mu m. However, as studies of Galactic dust emission have shown, the intensity of the thermal dust emission at 100 \\mu m is strongly dependent on the dust temperature, which has severe implications for the AME emissivity defi...

  1. Controlling spontaneous emission

    DEFF Research Database (Denmark)

    Lodahl, Peter

    dots (QDs) embedded in 3D photonic crystals consisting of air spheres in titanium dioxide. Performing time-resolved experiments, we show that the photonic crystals control the emission decay rate of excitons confined in the QDs1,2. By varying the lattice parameter of the photonic crystals, we...

  2. Generalized emissivity inverse problem.

    Science.gov (United States)

    Ming, DengMing; Wen, Tao; Dai, XianXi; Dai, JiXin; Evenson, William E

    2002-04-01

    Inverse problems have recently drawn considerable attention from the physics community due to of potential widespread applications [K. Chadan and P. C. Sabatier, Inverse Problems in Quantum Scattering Theory, 2nd ed. (Springer Verlag, Berlin, 1989)]. An inverse emissivity problem that determines the emissivity g(nu) from measurements of only the total radiated power J(T) has recently been studied [Tao Wen, DengMing Ming, Xianxi Dai, Jixin Dai, and William E. Evenson, Phys. Rev. E 63, 045601(R) (2001)]. In this paper, a new type of generalized emissivity and transmissivity inverse (GETI) problem is proposed. The present problem differs from our previous work on inverse problems by allowing the unknown (emissivity) function g(nu) to be temperature dependent as well as frequency dependent. Based on published experimental information, we have developed an exact solution formula for this GETI problem. A universal function set suggested for numerical calculation is shown to be robust, making this inversion method practical and convenient for realistic calculations.

  3. Emissions from urban waste

    International Nuclear Information System (INIS)

    Indiscriminate emission of gases and fumes from improper storage, transport systems and wastes disposals have polluted the environment especially surface and underground water and air. This has irreversibly affects on the environment some of which can be devastating to life.Some of the potential adverse effects on environment include the ozone depletion, acid rain,soil degradation and climate change

  4. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J;

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...

  5. Automotive Emission Control.

    Science.gov (United States)

    Lee, Billy D.; Ragazzi, Ronald

    This guide designed to assist teachers in improving instruction in the area of automotive emission control curriculum includes four areas. Each area consists of one or more units of instruction, with each instructional unit including some or all of the following basic components: Performance objectives, suggested activities for teacher and…

  6. Reaching peak emissions

    Science.gov (United States)

    Jackson, Robert B.; Canadell, Josep G.; Le Quéré, Corinne; Andrew, Robbie M.; Korsbakken, Jan Ivar; Peters, Glen P.; Nakicenovic, Nebojsa

    2016-01-01

    Rapid growth in global CO2 emissions from fossil fuels and industry ceased in the past two years, despite continued economic growth. Decreased coal use in China was largely responsible, coupled with slower global growth in petroleum and faster growth in renewables.

  7. Diesel emissions in Vienna

    Science.gov (United States)

    Horvath, H.; Kreiner, I.; Norek, C.; Preining, O.; Georgi, B.

    The aerosol in a non-industrial town normally is dominated by emissions from vehicles. Whereas gasoline-powered cars normally only emit a small amount of particulates, the emission by diesel-powered cars is considerable. The aerosol particles produced by diesel engines consist of graphitic carbon (GC) with attached hydrocarbons (HCs) including also polyaromatic HCs. Therefore the diesel particles can be carcinogenic. Besides diesel vehicles, all other combustion processes are also a source for GC; thus source apportionment of diesel emissions to the GC in the town is difficult. A direct apportionment of diesel emissions has been made possible by marking all the diesel fuel used by the vehicles in Vienna by a normally not occurring and easily detectable substance. All emitted diesel particles thus were marked with the tracer and by analyzing the atmospheric samples for the marking substance we found that the mass concentrations of diesel particles in the atmosphere varied between 5 and 23 μg m -3. Busy streets and calm residential areas show less difference in mass concentration than expected. The deposition of diesel particles on the ground has been determined by collecting samples from the road surface. The concentration of the marking substance was below the detection limit before the marking period and a year after the period. During the period when marked diesel fuel was used, the concentrations of the diesel particles settling to the ground was 0.012-0.07 g g -1 of collected dust. A positive correlation between the diesel vehicle density and the sampled mass of diesel vehicles exists. In Vienna we have a background diesel particle concentration of 11 μg m -3. This value increases by 5.5 μg m -3 per 500 diesel vehicles h -1 passing near the sampling location. The mass fraction of diesel particles of the total aerosol mass varied between 12.2 and 33%; the higher values were found in more remote areas, since diesel particles apparently diffuse easily

  8. Anthropogenic mercury emission inventory with emission factors and total emission in Korea

    Science.gov (United States)

    Kim, Jeong-Hun; Park, Jung-Min; Lee, Sang-Bo; Pudasainee, Deepak; Seo, Yong-Chil

    2010-07-01

    Mercury emissions concentrations, emission factors, and the total national emission from major anthropogenic sources in Korea for the year 2007 were estimated. Uncontrolled and controlled mercury emission factors and the total emission from each source types are presented. The annual national mercury emission from major anthropogenic sources for the year 2007, on average was 12.8 ton which ranged from 6.5 to 20.2 ton. Averaged emissions of elemental, oxidized, and particulate mercury were estimated at 8.25 ton, 3.69 ton, and 0.87 ton, respectively. Due to the removal of a major portion of particulate and oxidized mercury species, elemental mercury was dominant in stack emission. About 54.8% of mercury emission was contributed by industrial sources, 45.0% by stationary combustion sources and 0.02% by mobile sources. Thermal power plants, oil refineries, cement kilns and incinerators (municipal, industrial, medical, sewage sludge) were the major mercury emitters, contributing about 26%, 25%, 21% and 20%, respectively to the total mercury emission. Other sources (crematory, pulp and paper manufacturing, nonferrous metals manufacturing, glass manufacturing) contributed about 8% of the total emission. Priority should be given in controlling mercury emissions from coal-fired power plants, oil refineries, cement kilns and waste incinerators. More measurements including natural and re-emission sources are to be carried out in the future in order to have a clear scenario of mercury emission from the country and to apply effective control measures.

  9. On the Limitations of the Anomalous Microwave Emission Emissivity

    Directory of Open Access Journals (Sweden)

    Christopher T. Tibbs

    2012-01-01

    Full Text Available Many studies of anomalous microwave emission (AME have computed an AME emissivity to compare the strength of the AME detected in different regions. Such a value is usually defined as the ratio between the intensity of the AME at 1 cm and the thermal dust emission at 100 μm. However, as studies of Galactic dust emission have shown, the intensity of the thermal dust emission at 100 μm is strongly dependent on the dust temperature, which has severe implications for the AME emissivity defined in this way. In this work, we illustrate and quantify this effect and find that the AME emissivity decreases by a factor of 11.1 between dust temperatures of 20 and 30 K. We, therefore, conclude that computing the AME emissivity relative to the 100 μm emission does not allow for accurate comparisons between the AME observed in different environments. With this in mind, we investigate the use of other tracers of the dust emission with which to compute the AME emissivity and we ultimately conclude that, despite the difficulty in deriving its value, the column density of the dust would be the most suitable quantity with which to compute the AME emissivity.

  10. Danish emission inventories for agriculture

    DEFF Research Database (Denmark)

    Mikkelsen, Mette Hjorth; Albrektsen, Rikke; Gyldenkærne, Steen

    By regulations given in international conventions Denmark is obliged to work out an annual emission inventory and document the methodology. The National Environmental Research Institute (NERI) at Aarhus University (AU) in Denmark is responsible for calculating and reporting the emissions....... This report contains a description of the emissions from the agricultural sector from 1985 to 2009. Furthermore, the report includes a detailed description of methods and data used to calculate the emissions, which is based on national methodologies as well as international guidelines. For the Danish...... emissions calculations and data management an Integrated Database model for Agricultural emissions (IDA) is used. The emission from the agricultural sector includes emission of the greenhouse gases methane (CH4), nitrous oxide (N2O), ammonia (NH3), particulate matter (PM), non-methane volatile organic...

  11. Emission factors for passenger cars: application of instantaneous emission modeling

    Science.gov (United States)

    de Haan, Peter; Keller, Mario

    This paper discusses the use of 'instantaneous' high-resolution (1 Hz) emission data for the estimation of passenger car emissions during real-world driving. Extensive measurements of 20 EURO-I gasoline passenger cars have been used to predict emission factors for standard (i.e. legislative) as well as non-standard (i.e. real-world) driving patterns. It is shown that emission level predictions based upon chassis dynamometer tests over standard driving cycles significantly underestimate emission levels during real-world driving. The emission characteristics of modern passenger cars equipped with a three-way catalytic converter are a low, basic emission level on the one hand, and frequent emission 'peaks' on the other. For real-world driving, up to one-half of the entire emission can be emitted during these short-lasting peaks. Their frequency depends on various factors, including the level of 'dynamics' (speed variation) of the driving pattern. Because of this, the use of average speed as the only parameter to characterize emissions over a specific driving pattern is not sufficient. The instantaneous emissions approach uses an additional parameter representing engine load in order to resolve the differences between driving patterns with comparable average speeds but different levels of 'dynamics'. The paper includes an investigation of different statistical indicators and discusses methods to further improve the prediction capability of the instantaneous emission approach. The fundamental differences in emission-reduction strategies between different car manufacturers make the task of constructing a model valid for all catalyst passenger cars seemingly impossible, if the model is required to predict both fleet-averaged emission levels and emission factors for driving patterns of short duration for individual vehicles simultaneously.

  12. Forecasting carbon dioxide emissions.

    Science.gov (United States)

    Zhao, Xiaobing; Du, Ding

    2015-09-01

    This study extends the literature on forecasting carbon dioxide (CO2) emissions by applying the reduced-form econometrics approach of Schmalensee et al. (1998) to a more recent sample period, the post-1997 period. Using the post-1997 period is motivated by the observation that the strengthening pace of global climate policy may have been accelerated since 1997. Based on our parameter estimates, we project 25% reduction in CO2 emissions by 2050 according to an economic and population growth scenario that is more consistent with recent global trends. Our forecasts are conservative due to that we do not have sufficient data to fully take into account recent developments in the global economy.

  13. Field Emission in Vacuum Microelectronics

    CERN Document Server

    Fursey, George; Schwoebel, Paul

    2005-01-01

    Field emission is a phenomenon described by quantum mechanics. Its emission capability is millions times higher than that of any other known types of electron emission. Nowadays this phenomenon is experiencing a new life due to wonderful applications in the atomic resolution microscopy, in electronic holography, and in the vacuum micro- and nanoelectronics in general. The main field emission properties, and some most remarkable experimental facts and applications, are described in this book.

  14. Future Emissions from Railway Traffic

    DEFF Research Database (Denmark)

    Sorenson, Spencer C.

    1998-01-01

    In investigation of the expected development in factors which influence railway energy consumption and emissions. Traffic factors such as train speed, load, an occupancy were considered. Tehcnical factors such an emissions factors, fleet composition and train weight were also considered. An estim......In investigation of the expected development in factors which influence railway energy consumption and emissions. Traffic factors such as train speed, load, an occupancy were considered. Tehcnical factors such an emissions factors, fleet composition and train weight were also considered...

  15. Aircrafts' taxi noise emission

    OpenAIRE

    Asensio Rivera, César; Pagán Muñoz, Raúl; López Navarro, Juan Manuel

    2008-01-01

    During planning stages, when noisy activity has not been implanted or while evaluating operation changes, it is necessary to find an environmental noise mapping prediction tool for future scenarios. When an activity is already implanted, it is possible to measure noise emissions, but this is expensive, so prediction tools can also be useful. Because of these reasons, for the last 10 years, as a response to the increasing concern for noise pollution in developed countries, several simulation m...

  16. Acoustic emission source modeling

    Directory of Open Access Journals (Sweden)

    Hora P.

    2010-07-01

    Full Text Available The paper deals with the acoustic emission (AE source modeling by means of FEM system COMSOL Multiphysics. The following types of sources are used: the spatially concentrated force and the double forces (dipole. The pulse excitation is studied in both cases. As a material is used steel. The computed displacements are compared with the exact analytical solution of point sources under consideration.

  17. Positron-emission tomography

    International Nuclear Information System (INIS)

    Positron-emission tomography (PET) combines early biochemical assessment of pathology achieved by nuclear medicine with the precise localization achieved by computerized image reconstruction. In this technique a chemical compound with the desired biological activity is labeled with a radioactive isotope that decays by emitting a positron, or positive electron. With suitable interpretation PET images can provide a noninvasive, regional assessment of many biochemical processes that are essential to the functioning of the organ that is being visualized

  18. Emissivity modulating electrochromic device

    Science.gov (United States)

    Demiryont, Hulya; Shannon, Kenneth C., III; Sheets, Judd

    2009-05-01

    The IR-ECDTM (Infra-Red ElectroChromic Device) variable emitance device (VED) is an all-solid-state monolithic vacuum deposited thin film system with a unique metamaterial IR transparent-electrode system which functions as an electrically controlled dimmable mirror in the IR region. The maximum reflectance corresponding to the bleached condition of the system is around 90% (low-e condition, e=0.1). The minimum reflectance reaches nearly zero in the colored condition of the system (high emittance, e=1). The average emissivity modulation of the IRECDTM is 0.7 in the 8-12 micron region, and at 9.7 micron (room temperature) it reaches a value of 0.9. Half and full emissivity modulations occur within 2 and10 minutes respectively. Because of its light weight (5g/m2), low voltage requirement (+/- 1 Volts), extremely good emissivity control properties (from 0 to 0.9 at 300K) and highly repeatable deposition process, the IR-ECDTM technology is very attractive for satellite thermal control applications. The IR-ECDTM has been under evaluation in a real space environment since March 8, 2007. This paper presents recent achievements of the IR-ECDTM including space test results.

  19. Field emission in RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Bonin, B. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee

    1996-01-01

    Electron field emission limits the accelerating gradient in superconducting cavities. It is shown how and why it is an important problem. The phenomenology of field emission is then described, both in DC and RF regimes. Merits of a few plausible `remedies` to field emission are discussed. (author). 20 refs.

  20. Cleaning the Diesel Engine Emissions

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    This paper examines how technologies for cleaning of diesel emission from road vehicles can be supported by facilitating a technology push in the Danish automotive emission control industry. The European commission is at present preparing legislation for the euro 5 emission standard (to be enforced...

  1. Evaluation of aural manifestations in temporo-mandibular joint dysfunction.

    Science.gov (United States)

    Sobhy, O A; Koutb, A R; Abdel-Baki, F A; Ali, T M; El Raffa, I Z; Khater, A H

    2004-08-01

    Thirty patients with temporo-mandibular joint dysfunction were selected to investigate the changes in otoacoustic emissions before and after conservative treatment of their temporo-mandibular joints. Pure tone audiometry, transient-evoked otoacoustic emissions (TEOAE), distortion-product otoacoustic emissions (DPOAE) as well as a tinnitus questionnaire were administered to all patients before and after therapy. Therapy was conservative in the form of counselling, physiotherapy, anti-inflammatory agents, muscle relaxants, and occlusal splints. Results indicated insignificant changes in the TEOAEs, whereas there were significant increases in distortion product levels at most of the frequency bands. These results were paralleled to subjective improvement of tinnitus.

  2. Emission inventory for fugitive emissions from fuel in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2013. The inventory of fugitive emissions includes CO2, CH4, N2O, SO2, NOx, NMVOC, CO, particulate matter, Black carbon, heavy metals, dioxin and PAHs. In 2013 the total...... Danish emission of greenhouse gasses was 54 584 Gg CO2 equivalents. Fugitive emissions from fuels account for 387 Gg CO2 equivalents or approximately 1 %. The major part of the fugitive emissions are emitted as CO2 (61 %) mainly from flaring in upstream oil and gas production. The major source...... of fugitive CH4 emission is production of oil and gas in the North Sea, refining of oil and loading of oil onto ships both offshore and onshore. The fugitive emissions of NMVOC originate for the major part from oil and gas production, loading of ships, transmission and distribution of oil, and to a less...

  3. THz wave emission microscope

    Science.gov (United States)

    Yuan, Tao

    Sensing and imaging using Terahertz (THz) radiation has attracted more and more interest in the last two decades thanks to the abundant material 'finger prints' in the THz frequency range. The low photon energy also makes THz radiation an attractive tool for nondestructive evaluation of materials and devices, biomedical applications, security checks and explosive screening. Due to the long wavelength, the far-field THz wave optical systems have relatively low spatial resolution. This physical limitation confines THz wave sensing and imaging to mostly macro-size samples. To investigate local material properties or micro-size structures and devices, near-field technology has to be employed. In this dissertation, the Electro-Optical THz wave emission microscope is investigated. The basic principle is to focus the femtosecond laser to a tight spot on a thin THz emitter layer to produce a THz wave source with a similar size as the focus spot. The apparatus provides a method for placing a THz source with sub-wavelength dimension in the near-field range of the investigated sample. Spatial resolution to the order of one tenth of the THz wavelength is demonstrated by this method. The properties of some widely used THz wave emission materials under tight focused pump light are studied. As an important branch of THz time domain spectroscopy (THz-TDS), THz wave emission spectroscopy has been widely used as a tool to investigate the material physics, such as energy band structure, carrier dynamics, material nonlinear properties and dynamics. As the main work of this dissertation, we propose to combine the THz wave emission spectroscopy with scanning probe microscopy (SPM) to build a tip-assisted THz wave emission microscope (TATEM), which is a valuable extension to current SPM science and technology. Illuminated by a femtosecond laser, the biased SPM tip forms a THz wave source inside the sample beneath the tip. The source size is proportional to the apex size of the tip so

  4. Reducing emissions : 2000 emissions inventory and five year projections

    Energy Technology Data Exchange (ETDEWEB)

    Hillenbrand, D.M.; Paton, R.; Boivin, D.W.

    2001-11-01

    This report represents the ninth consecutive year that member companies of the Canadian Chemical Producer's Association (CCPA) summarize their overall environmental performance. In 2000, CCPA members reported a total emission reduction of 62 per cent or 169,000 tonnes since the the first report in 1992. The rate of reduction has outpaced the increase in chemical production. A unit of chemical product manufactured today has 67 per cent less chemical emissions than in 1992. Member companies expect that by 2005 emissions per unit of production will decline by 74 per cent based on 1992 volumes. Progress has been made regarding emissions to water (down 99.4 per cent from 1992), emissions of toxic substances (down 71 per cent), and emissions of ozone-depleting substances (down 39 per cent from 1992). Currently, greater emphasis is being placed on reducing emissions from combustion processes that account for 66 per cent of all emissions, including carbon dioxide, oxides of sulphur, oxides of nitrogen and carbon monoxide. Emissions of these substances have increased by 18 per cent since 1992 and are likely to increase another 5 per cent by 2005. Various emissions reduction projects were presented. This report was divided into several chapters dealing with toxic substances, smog, climate change, stratospheric ozone depletion, water quality, substances, waste and recoverables. A list of CCPA member companies and contacts was also included. tabs., figs.

  5. Positron Emission Tomography (PET)

    Science.gov (United States)

    Welch, M. J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET.

  6. Positron Emission Tomography (PET)

    Energy Technology Data Exchange (ETDEWEB)

    Welch, M.J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs.

  7. Positron emission tomography

    CERN Document Server

    Paans, A M J

    2006-01-01

    Positron Emission Tomography (PET) is a method for measuring biochemical and physiological processes in vivo in a quantitative way by using radiopharmaceuticals labelled with positron emitting radionuclides such as 11C, 13N, 15O and 18F and by measuring the annihilation radiation using a coincidence technique. This includes also the measurement of the pharmacokinetics of labelled drugs and the measurement of the effects of drugs on metabolism. Also deviations of normal metabolism can be measured and insight into biological processes responsible for diseases can be obtained. At present the combined PET/CT scanner is the most frequently used scanner for whole-body scanning in the field of oncology.

  8. Emission rate measuring device

    Science.gov (United States)

    Luckat, S.

    1980-09-01

    The development and application of an emission rate measuring device for gaseous components is explored. The device contains absorption fluid from a supply container that moistens a cylindrical paper sleeve. A newer model is provided with a direct current motor requiring less electricity than an older model. The hose pump is modified to avoid changing it and the filter sleeve is fastened more securely to the distributor head. Application of the measuring devices is discussed, particularly at the Cologne Cathedral, where damage to the stone is observed.

  9. Positron Emission Tomography (PET)

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs

  10. Emissivity compensated spectral pyrometry for varying emissivity metallic measurands

    International Nuclear Information System (INIS)

    A novel method for converting electromagnetic spectral radiance information into temperature measurements is presented. It allows for varying spectral emissivity of the metallic measurand during the course of the measurement. Such variations are due to, e.g., thermal oxidation or temperature dependent emissivity. Based on a requirement that emissivity changes with time and temperature are smooth, it is assumed that an emissivity estimate at one sample instance can be derived from the estimated emissivity found at the previous samples together with updated spectral information. This leads to successive recalculations of spectral emissivity together with corresponding temperature values. The proposed algorithm has been proven to give accurate temperature estimates from a measurement based on the data captured by a standard UV-Vis spectrophotometer even for an oxidizing Ti-6Al-4V specimen in a temperature range between 900 and 1400 K. The method however, is not limited to these wavelength or temperature ranges. (paper)

  11. Spinning dust emission from ultrasmall silicates: emissivity and polarization spectrum

    CERN Document Server

    Hoang, Thiem; Lan, Nguyen Quynh

    2016-01-01

    Anomalous microwave emission (AME) is an important Galactic foreground of Cosmic Microwave Background (CMB) radiation. It is believed that the AME arises from rotational emission by spinning polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM). In this paper, we assume that a population of ultrasmall silicate grains may exist in the ISM, and quantify rotational emissivity from these tiny particles and its polarization spectrum. We found that spinning silicate nanoparticles can produce strong rotational emission when those small grains follow a log-normal size distribution. The polarization fraction of spinning dust emission from tiny silicates increases with decreasing the dipole moment per atom ($\\beta$) and can reach $P\\sim 20\\%$ for $\\beta\\sim 0.1$D at grain temperature of 60 K. We identify a parameter space $(\\beta,Y_{Si})$ for silicate nanoparticles in which its rotational emission can adequately reproduce both the observed AME and the polarization of the AME, without violating the ob...

  12. GHG emissions due to deforestation

    International Nuclear Information System (INIS)

    An assessment was made for the magnitude of greenhouse gas emissions resulting from deforestation and forest degradation in tropical forests in Malaysia and Indonesia related to Dutch economic activities. Greenhouse gas emissions (GHG) are calculated in relation to (1) the emissions related to vegetation removal sec; and (2) the emissions related to removal and more long term effects related to assimilation of CO2 in forest regrowth and changes in organic material in soils. Emissions related to vegetation removal and aggregated emissions for both vegetation removal and long term effects are reported separately. Soil organic carbon stock changes are considered by Greenpeace as more uncertain, so the emphasis will be on the direct emissions. Changes in carbon stocks and N2O emissions and actually also changes in vegetation all are events that occur gradually, rather than immediately. Only removal of existing vegetation and possible burning of this vegetation and associated emissions related to both activities are immediate by nature. Carbon stocks and N2O emissions change to a new level within several decades after deforestation or forest degradation. Removed vegetation can grow back or be replaced eventually by other vegetation, thereby changing the net greenhouse gas (GHG) emissions related to deforestation or forest degradation. Vegetation extracted for commercial purposes such as timber or pulp will also take years or decades to become waste and be converted into CO2. In IPCC and LCA's all these emissions are taken into account - or at least all emissions occurring within a period of 20 years, as required by IPCC. Soil organic carbon stock changes are also considered by Greenpeace as more uncertain, so the emphasis will be on the direct emmissions.

  13. GHG emissions due to deforestation

    Energy Technology Data Exchange (ETDEWEB)

    Croezen, H.; Van Valkengoed, M.

    2009-05-15

    An assessment was made for the magnitude of greenhouse gas emissions resulting from deforestation and forest degradation in tropical forests in Malaysia and Indonesia related to Dutch economic activities. Greenhouse gas emissions (GHG) are calculated in relation to (1) the emissions related to vegetation removal sec; and (2) the emissions related to removal and more long term effects related to assimilation of CO2 in forest regrowth and changes in organic material in soils. Emissions related to vegetation removal and aggregated emissions for both vegetation removal and long term effects are reported separately. Soil organic carbon stock changes are considered by Greenpeace as more uncertain, so the emphasis will be on the direct emissions. Changes in carbon stocks and N2O emissions and actually also changes in vegetation all are events that occur gradually, rather than immediately. Only removal of existing vegetation and possible burning of this vegetation and associated emissions related to both activities are immediate by nature. Carbon stocks and N2O emissions change to a new level within several decades after deforestation or forest degradation. Removed vegetation can grow back or be replaced eventually by other vegetation, thereby changing the net greenhouse gas (GHG) emissions related to deforestation or forest degradation. Vegetation extracted for commercial purposes such as timber or pulp will also take years or decades to become waste and be converted into CO2. In IPCC and LCA's all these emissions are taken into account - or at least all emissions occurring within a period of 20 years, as required by IPCC. Soil organic carbon stock changes are also considered by Greenpeace as more uncertain, so the emphasis will be on the direct emmissions.

  14. Spinning dust emission from ultrasmall silicates: emissivity and polarization spectrum

    OpenAIRE

    Hoang, Thiem; Vinh, Nguyen Anh; Lan, Nguyen Quynh

    2016-01-01

    Anomalous microwave emission (AME) is an important Galactic foreground of Cosmic Microwave Background (CMB) radiation. It is believed that the AME arises from rotational emission by spinning polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM). In this paper, we assume that a population of ultrasmall silicate grains may exist in the ISM, and quantify rotational emissivity from these tiny particles and its polarization spectrum. We found that spinning silicate nanoparticles...

  15. For sale: Sulfur emissions

    International Nuclear Information System (INIS)

    The allowance trading market has started a slow march to maturity. Competitive developers should understand the risks and opportunities now presented. The marketplace for sulfur dioxide (SO2) emissions allowances - the centerpiece of Title 4's acid rain reduction program - remains enigmatic 19 months after the Clean Air Act amendments of 1990 were passed. Yet it is increasingly clear that the emission allowance market will likely confound the gloom and doom of its doubters. The recently-announced $10 million dollar Wisconsin Power and Light allowance sales to Duquesne Light and the Tennessee Valley Authority are among the latest indications of momentum toward a stabilizing market. This trend puts additional pressure on independent developers to finalize their allowance strategies. Developers who understand what the allowance trading program is and what it is not, know the key players, and grasp the unresolved regulatory issues will have a new competitive advantage. The topics addressed in this article include the allowance marketplace, marketplace characteristics, the regulatory front, forward-looking strategies, and increasing marketplace activity

  16. Elastic emission polishing

    Energy Technology Data Exchange (ETDEWEB)

    Loewenthal, M.; Loseke, K.; Dow, T.A.; Scattergood, R.O.

    1988-12-01

    Elastic emission polishing, also called elastic emission machining (EEM), is a process where a stream of abrasive slurry is used to remove material from a substrate and produce damage free surfaces with controlled surface form. It is a noncontacting method utilizing a thick elasto-hydrodynamic film formed between a soft rotating ball and the workpiece to control the flow of the abrasive. An apparatus was built in the Center, which consists of a stationary spindle, a two-axis table for the workpiece, and a pump to circulate the working fluid. The process is controlled by a programmable computer numerical controller (CNC), which presently can operate the spindle speed and movement of the workpiece in one axis only. This apparatus has been used to determine material removal rates on different material samples as a function of time, utilizing zirconium oxide (ZrO{sub 2}) particles suspended in distilled water as the working fluid. By continuing a study of removal rates the process should become predictable, and thus create a new, effective, yet simple tool for ultra-precision mechanical machining of surfaces.

  17. Zero emission coal

    Energy Technology Data Exchange (ETDEWEB)

    Ziock, H.; Lackner, K.

    2000-08-01

    We discuss a novel, emission-free process for producing hydrogen or electricity from coal. Even though we focus on coal, the basic design is compatible with any carbonaceous fuel. The process uses cyclical carbonation of calcium oxide to promote the production of hydrogen from carbon and water. The carbonation of the calcium oxide removes carbon dioxide from the reaction products and provides the additional energy necessary to complete hydrogen production without additional combustion of carbon. The calcination of the resulting calcium carbonate is accomplished using the high temperature waste heat from solid oxide fuel cells (SOFC), which generate electricity from hydrogen fuel. Converting waste heat back to useful chemical energy allows the process to achieve very high conversion efficiency from fuel energy to electrical energy. As the process is essentially closed-loop, the process is able to achieve zero emissions if the concentrated exhaust stream of CO{sub 2} is sequestered. Carbon dioxide disposal is accomplished by the production of magnesium carbonate from ultramafic rock. The end products of the sequestration process are stable naturally occurring minerals. Sufficient rich ultramafic deposits exist to easily handle all the world's coal.

  18. Data analysis in emission tomography using emission-count posteriors

    Science.gov (United States)

    Sitek, Arkadiusz

    2012-11-01

    A novel approach to the analysis of emission tomography data using the posterior probability of the number of emissions per voxel (emission count) conditioned on acquired tomographic data is explored. The posterior is derived from the prior and the Poisson likelihood of the emission-count data by marginalizing voxel activities. Based on emission-count posteriors, examples of Bayesian analysis including estimation and classification tasks in emission tomography are provided. The application of the method to computer simulations of 2D tomography is demonstrated. In particular, the minimum-mean-square-error point estimator of the emission count is demonstrated. The process of finding this estimator can be considered as a tomographic image reconstruction technique since the estimates of the number of emissions per voxel divided by voxel sensitivities and acquisition time are the estimates of the voxel activities. As an example of a classification task, a hypothesis stating that some region of interest (ROI) emitted at least or at most r-times the number of events in some other ROI is tested. The ROIs are specified by the user. The analysis described in this work provides new quantitative statistical measures that can be used in decision making in diagnostic imaging using emission tomography.

  19. Fraud risks in emissions trading

    International Nuclear Information System (INIS)

    The system of emission trading is a complex composed entity with on the one hand a strong environmental component and on the other hand a financial world that hooked on this instrument. In chapter 2 an introduction is provided to the emission trading system. The subsequent chapters elaborate Types of Fraud (Chapter 3), Powers (Chapter 4), and Instruments (Chapter 5). The report shows that various forms of fraud are occurring in emission trading, such as VAT fraud and identity theft.

  20. Neutrino Emissivity of Dense Stars

    OpenAIRE

    Ghosh, Sanjay K.; Phatak, S. C.; P.K. Sahu

    1995-01-01

    The neutrino emissivity of compact stars is investigated in this work. We consider stars consisting of nuclear as well as quark matter for this purpose. Different models are used to calculate the composition of nuclear and quark matter and the neutrino emissivity. Depending on the model under consideration, the neutrino emissivity of nuclear as well as quark matter varies over a wide range. We find that for nuclear matter, the direct URCA processes are allowed for most of the relativistic mod...

  1. Greenhouse Gas Emissions: Quantifying Methane Emissions from Livestock

    Directory of Open Access Journals (Sweden)

    Rafiu O. Yusuf

    2012-01-01

    Full Text Available Problem statement: The rearing of animals for domestic consumption and export invariably lead to the production of methane as a product of digestion. This study investigated the emission of methane from Malaysian livestock between 1980 and 2008. Approach: Seven categories of animals identified were camel, buffalo, sheep, goats, horse, pigs and poultry. The estimation of methane was based on the IPCC Tier 1 and Tier 2 methods. Methane emission from cattle rose by 44% within the period from 45.61-65.57 Gg. Results: Buffalo recorded a drop in methane emission by 54% from 17.12-7.86 Gg while the methane emission from sheep initially rose by 350% in 1992 only to drop by another 56% by 2008. Goats emission only declined by 17% from 1.79 Gg in 1980-1.49 Gg by 2008. Methane emission from horse has been consistent at around 0.14 Gg. The decreasing stock of pigs has led to a drop in methane emission from these set of animals with most of the emission coming from manure management. Conclusion: The healthy export market for poultry has seen a rise in methane emission by 274% from 2.18 Gg in 1980-8.17 Gg by 2008. The overall increase in methane emission from all the livestock is 20% from 81.83 Gg in 1980-98.76 Gg in 2008. With the aggressive drive of government to boost cattle and goat production, there is the likelihood of an increase in methane emission in the future and mitigation options will have to be applied.

  2. The Emissions Gap Report 2014

    DEFF Research Database (Denmark)

    This fifth Emissions Gap report has a different focus from previous years. While it updates the 2020 emissions gap analysis, it gives particular attention to the implications of the global carbon dioxide emissions budget for staying within the 2 °C limit beyond 2020. It does so because countries...... are giving increasing attention to where they need to be in 2025, 2030 and beyond. Furthermore, this year’s update of the report benefits from the findings on the emissions budget from the latest series of Intergovernmental Panel on Climate Change (IPCC) reports...

  3. [Spectral emissivity of thin films].

    Science.gov (United States)

    Zhong, D

    2001-02-01

    In this paper, the contribution of multiple reflections in thin film to the spectral emissivity of thin films of low absorption is discussed. The expression of emissivity of thin films derived here is related to the thin film thickness d and the optical constants n(lambda) and k(lambda). It is shown that in the special case d-->infinity the emissivity of thin films is equivalent to that of the bulk material. Realistic numerical and more precise general numerical results for the dependence of the emissivity on d, n(lambda) and k(lambda) are given.

  4. OPIC Greenhouse Gas Emissions Inventory

    Data.gov (United States)

    Overseas Private Investment Corporation — Independent analysis details quantifying the greenhouse gas ("GHG") emissions directly attributable to projects to which the Overseas Private Investment Corporation...

  5. Positron Emission Mammography imaging

    Energy Technology Data Exchange (ETDEWEB)

    Moses, W.W. E-mail: wwmoses@lbl.gov

    2004-06-01

    This paper examines current trends in Positron Emission Mammography (PEM) instrumentation and the performance tradeoffs inherent in them. The most common geometry is a pair of parallel planes of detector modules. They subtend a larger solid angle around the breast than conventional PET cameras, and so have both higher efficiency and lower cost. Extensions to this geometry include encircling the breast, measuring the depth of interaction (DOI), and dual-modality imaging (PEM and X-ray mammography, as well as PEM and X-ray guided biopsy). The ultimate utility of PEM may not be decided by instrument performance, but by biological and medical factors, such as the patient to patient variation in radiotracer uptake or the as yet undetermined role of PEM in breast cancer diagnosis and treatment.

  6. Radio emission from novae

    International Nuclear Information System (INIS)

    The nature and measurement of radio emission from novae is discussed. The classical novae for which there are reported measurements of radio flux densities are listed. The three which have been studied most extensively are the slow nova HR Delta, the moderate speed nova FH Ser and the fast nova V1500 Cyg. Two different types of models have been used to model classical novae, the variable speed model and a Hubble flow model. V1500 Cyg has been observed in both radio and infrared spectra. The behaviour which explains this is discussed. Estimates of distance shell, mass and kinetic energy have been made from the data. Radioemissions from related objects and nova remnants are also discussed. (U.K.)

  7. Acoustic emission testing

    CERN Document Server

    Grosse, Christian U

    2008-01-01

    Acoustic Emission (AE) techniques have been studied in civil engineering for a long time. The techniques are recently going to be more and more applied to practical applications and to be standardized in the codes. This is because the increase of aging structures and disastrous damages due to recent earthquakes urgently demand for maintenance and retrofit of civil structures in service for example. It results in the need for the development of advanced and effective inspection techniques. Thus, AE techniques draw a great attention to diagnostic applications and in material testing. The book covers all levels from the description of AE basics for AE beginners (level of a student) to sophisticated AE algorithms and applications to real large-scale structures as well as the observation of the cracking process in laboratory specimen to study fracture processes.

  8. Positron emission mammography imaging

    Energy Technology Data Exchange (ETDEWEB)

    Moses, William W.

    2003-10-02

    This paper examines current trends in Positron Emission Mammography (PEM) instrumentation and the performance tradeoffs inherent in them. The most common geometry is a pair of parallel planes of detector modules. They subtend a larger solid angle around the breast than conventional PET cameras, and so have both higher efficiency and lower cost. Extensions to this geometry include encircling the breast, measuring the depth of interaction (DOI), and dual-modality imaging (PEM and x-ray mammography, as well as PEM and x-ray guided biopsy). The ultimate utility of PEM may not be decided by instrument performance, but by biological and medical factors, such as the patient to patient variation in radiotracer uptake or the as yet undetermined role of PEM in breast cancer diagnosis and treatment.

  9. Fission neutron statistical emission

    International Nuclear Information System (INIS)

    The statistical model approach FINESSE (FIssion NEutronS' Statistical Emission) for the description of fission neutron multiplicities, energy spectra and angular distributions is described. Based on an extended Weisskopf ansatz and on a realistic temperature distribution it provides a fragment mass number dependent description of fission neutron data. Model parameters (optical potential, n/γ competition) were fixed on the basis of the 252Cf(sf) (nuclear data standard). Combined with a phenomenological fission model for predicting relevant fragment data as function of asymmetry. FINESSE can be applied to any fission reaction of actinides in the Th-Cf region without further parameter adjustment. Results are presented for 252Cf(sf) and neutron induced fission of 235U, 239Pu, 232Th. Effects of multiple-chance fission are discussed for 232Th(n,xnf) reacation. (author). 46 refs, 11 figs

  10. Estimation of broadband surface emissivity from narrowband emissivities.

    Science.gov (United States)

    Tang, Bo-Hui; Wu, Hua; Li, Chuanrong; Li, Zhao-Liang

    2011-01-01

    This work analyzed and addressed the estimate of the broadband emissivities for the spectral domains 3-14μm (ε(3-14)) and 3-∞μm (ε(3-∞). Two linear narrow-to-broadband conversion models were proposed to estimate broadband emissivities ε(3-14) and ε(3-∞) using the Moderate Resolution Imaging Spectroradiometer (MODIS) derived emissivities in three thermal infrared channels 29 (8.4-8.7μm), 31 (10.78-11.28μm) and 32 (11.77-12.27μm). Two independent spectral libraries, the Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) spectral library and the MODIS UCSB (University of California, Santa Barbara) emissivity library, were used to calibrate and validate the proposed models. Comparisons of the estimated broadband emissivities using the proposed models and the calculated values from the spectral libraries, showed that the proposed method of estimation of broadband emissivity has potential accuracy and the Root Mean Square Error (RMSE) between estimated and calculated broadband emissivities is less than 0.01 for both ε(3-14) and ε(3-∞).

  11. Emissivity of condensed phases from the spontaneous emission spectrum

    International Nuclear Information System (INIS)

    The method of determining the temperature and spectral emissivity of substances unavailable for direct contact is described. Potentialities of the method were demonstrated using incandescent lamps with emitting filaments made of tungsten, rhenium and tantalum. Accuracy of determination of the temperature and spectral emissivity (in the range of spectrum 0.9-2.1 μm) made up 1 and 10% respectively

  12. Estimation of broadband surface emissivity from narrowband emissivities.

    Science.gov (United States)

    Tang, Bo-Hui; Wu, Hua; Li, Chuanrong; Li, Zhao-Liang

    2011-01-01

    This work analyzed and addressed the estimate of the broadband emissivities for the spectral domains 3-14μm (ε(3-14)) and 3-∞μm (ε(3-∞). Two linear narrow-to-broadband conversion models were proposed to estimate broadband emissivities ε(3-14) and ε(3-∞) using the Moderate Resolution Imaging Spectroradiometer (MODIS) derived emissivities in three thermal infrared channels 29 (8.4-8.7μm), 31 (10.78-11.28μm) and 32 (11.77-12.27μm). Two independent spectral libraries, the Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) spectral library and the MODIS UCSB (University of California, Santa Barbara) emissivity library, were used to calibrate and validate the proposed models. Comparisons of the estimated broadband emissivities using the proposed models and the calculated values from the spectral libraries, showed that the proposed method of estimation of broadband emissivity has potential accuracy and the Root Mean Square Error (RMSE) between estimated and calculated broadband emissivities is less than 0.01 for both ε(3-14) and ε(3-∞). PMID:21263556

  13. Emissivity measurement of high-emissivity black paint at CENAM

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas G, D., E-mail: dcardena@cenam.mx [Centro Nacional de Metrologia, Km 4.5 Carretera a los Cues, El Marques, 76246 Santiago de Queretaro, Queretaro (Mexico)

    2014-07-01

    To measure the temperature of the surface of an opaque object by radiation thermometry, it is necessary to know its surface emissivity. High emissivity black paint can be applied to the inner walls of a cavity to be used as a blackbody radiator. It can also be applied to some highly reflecting metals so that their temperature can be estimated by radiation thermometry. In this work, it is described the emissivity measurement of high-emissivity black paint that has been used for the two applications described above. The average emissivity of the measured paint in the 8 to 14 micrometers wavelength range was estimated as 0.972 ± 0.012. The results obtained may be of use for those using the paint at temperatures from 50 to 150 grades C. (Author)

  14. Emissivity measurement of high-emissivity black paint at CENAM

    International Nuclear Information System (INIS)

    To measure the temperature of the surface of an opaque object by radiation thermometry, it is necessary to know its surface emissivity. High emissivity black paint can be applied to the inner walls of a cavity to be used as a blackbody radiator. It can also be applied to some highly reflecting metals so that their temperature can be estimated by radiation thermometry. In this work, it is described the emissivity measurement of high-emissivity black paint that has been used for the two applications described above. The average emissivity of the measured paint in the 8 to 14 micrometers wavelength range was estimated as 0.972 ± 0.012. The results obtained may be of use for those using the paint at temperatures from 50 to 150 grades C. (Author)

  15. Laser-induced Field Emission from Tungsten Tip: Optical Control of Emission Sites and Emission Process

    OpenAIRE

    Yanagisawa, H.; Hafner, C; Doná, P; Klöckner, M; Leuenberger, D.; Greber, T.; Osterwalder, J; Hengsberger, M.

    2010-01-01

    Field-emission patterns from a clean tungsten tip apex induced by femtosecond laser pulses have been investigated. Strongly asymmetric field-emission intensity distributions are observed depending on three parameters: (i) the polarization of the light, (ii) the azimuthal, and (iii) the polar orientation of the tip apex relative to the laser incidence direction. In effect, we have realized an ultrafast pulsed field-emission source with site selectivity of a few tens of nanometers. Simulations ...

  16. Anthropogenic mercury emissions in China

    Science.gov (United States)

    Streets, David G.; Hao, Jiming; Wu, Ye; Jiang, Jingkun; Chan, Melissa; Tian, Hezhong; Feng, Xinbin

    An inventory of mercury emissions from anthropogenic activities in China is compiled for the year 1999 from official statistical data. We estimate that China's emissions were 536 (±236) t of total mercury. This value includes open biomass burning, but does not include natural sources or re-emission of previously deposited mercury. Approximately 45% of the Hg comes from non-ferrous metals smelting, 38% from coal combustion, and 17% from miscellaneous activities, of which battery and fluorescent lamp production and cement production are the largest. Emissions are heaviest in Liaoning and Guangdong Provinces, where extensive smelting occurs, and in Guizhou Province, where there is much small-scale combustion of high-Hg coal without emission control devices. Emissions are gridded at 30×30 min spatial resolution. We estimate that 56% of the Hg in China is released as Hg 0, 32% as Hg 2+, and 12% as Hg p. Particulate mercury emissions are high in China due to heavy burning of coal in residential and small industrial settings without PM controls. Emissions of Hg 2+ from coal-fired power plants are high due to the absence of flue-gas desulfurization units, which tend to dissolve the soluble divalent mercury. Metals smelting operations favor the production of elemental mercury. Much of the Hg is released from small-scale activities in rather remote areas, and therefore the activity levels are quite uncertain. Also, emissions test data for Chinese sources are lacking, causing uncertainties in Hg emission factors and removal efficiencies. Overall, we calculate an uncertainty level of ±44% (95% confidence interval) in the estimate of total emissions. We recommend field testing of coal combustors and smelters in China to improve the accuracy of these estimates.

  17. Carbon emissions and an equitable emission reduction criterion

    International Nuclear Information System (INIS)

    In 1995 the world-wide carbon emissions reached 5.8 billion metric tonnes per year (GTC/y). The Kyoto protocol calls for a reduction of carbon emissions from the developed countries (Annex I countries) of 6-8% below 1990 levels on the average, and unspecified commitments for the less developed (non-Annex I) countries. It is doubtful that the Kyoto agreement will be ratified by some parliaments, especially the USA Congress. Furthermore, it is shown that if the non-Annex I countries will not curtail their carbon emissions drastically, the global emissions will soar to huge levels by the middle of the next century. An equitable emission criterion is proposed which may lead to a sustainable rate of growth of carbon emissions, and be acceptable to all countries of the world. The criterion links the rate of growth of carbon emissions to the rate of growth of the Gross Domestic Product (GDP). A target criterion is proposed R = 0.15 KgC/SGDP, which is the current average for western European countries and Japan. This allows for both the growth of the GDP and carbon emissions. However, to reach the target in a reasonable time, the countries for which R≤ 0.3 would be allowed a carbon emission growth rate of 1%./y, and countries for which R≥ 0.3, 0.75%/y. It is shown that by 2050 the world-wide carbon emissions would reach about 10 GTC/y, which is about 3 times less than the Kyoto agreement would allow. (Author)

  18. Emission of formaldehyde from furniture

    DEFF Research Database (Denmark)

    Andersen, Helle Vibeke; Klinke, Helene B.; Funch, Lis Winther;

    The emission of formaldehyde from 20 pieces of furniture, representing a variety of types, was measured in climate chambers. Most tests show low emissions but certain scenarios of furnishing, including furniture with large surface areas in relation to room volume can emit formaldehyde resulting...

  19. The Emissions Gap Report 2015

    DEFF Research Database (Denmark)

    contributions from the Intended Nationally Determined Contributions (INDC) committed to by 1 October 2015, by the 146 countries that account for around 90 per cent of global emissions. It compares the 2030 emission levels that would result from these commitments with what science tells us would keep average...

  20. NORTRIP emission model user guide

    Energy Technology Data Exchange (ETDEWEB)

    Denby, Rolstad Bruce

    2012-07-01

    The NORTRIP emission model has been developed at NILU, in conjunction with other Nordic institutes, to model non-exhaust traffic induced emissions. This short summary document explains how to run the NORTRIP model from the MATLAB environment or by using the executable user interface version. It also provides brief information on input files and the model architecture.(Author)

  1. Deliberating emission reduction options

    Energy Technology Data Exchange (ETDEWEB)

    Dowd, A.M.; Rodriguez, M.; Jeanneret, T. [Commonwealth Scientific and Industrial Research Organisation CSIRO, 37 Graham Rd, Highett VIC 3190 (Australia); De Best-Waldhober, M.; Straver, K.; Mastop, J.; Paukovic, M. [Energy research Centre of the Netherlands ECN, Policy Studies, Amsterdam (Netherlands)

    2012-06-15

    For more than 20 years there has been a concerted international effort toward addressing climate change. International conventions, such as the United Nations Foreign Convention on Climate Change (UNFCCC; ratified in 1994), have been established by committed nations seeking to address global climate change through the reduction of greenhouse gases emitted into the Earth's atmosphere (Global CCS Institute, 2011). Long recognised as the most crucial of the greenhouse gases to impact global warming, the majority of carbon dioxide's anthropogenic global emissions are directly related to fuel combustion of which both Australia and the Netherlands' energy production is significantly reliant. Both these nations will need to consider many opinions and make hard decisions if alternative energy options are to be implemented at the scale that is required to meet international emission targets. The decisions that are required not only need to consider the many options available but also their consequences. Along with politicians, policy developers and industry, the general public also need to be active participants in deciding which energy options, and their subsequent consequences, are acceptable for implementation at the national level. Access to balanced and factual information is essential in establishing informed opinions on the many policy options available. Past research has used several methods to measure public perceptions and opinions yet for complex issues, such as emission reduction, some of these methods have shown to be problematic. For example, semi structured interviews can provide data that is flexible and context rich yet is does also come with the limitations such as it seldom provides a practical assessment that can be utilised from researcher to researcher, across disciplines and public participation techniques. Surveys on the other hand usually address these limitations but surveys that do not encourage comparison of information or ask

  2. Emission of formaldehyde from furniture

    DEFF Research Database (Denmark)

    Andersen, Helle Vibeke; Klinke, Helene B.; Funch, Lis Winther;

    2014-01-01

    The emission of formaldehyde from a variety of furniture was measured in climate chambers. Most tests show low emission of formaldehyde; however, there are a few exceptions. One product emitted significant amounts of formaldehyde, but according to the Danish Indoor Climate Labelling Criteria...... for furniture the impact on the formaldehyde concentration was low due to a small surface area in the standard room. One product led to a high concentration of formaldehyde in the standard room since both emission and material load were high. Even with a moderate area-specific emission rate of formaldehyde......, furniture with high material load in the standard room, such as bookcases, can have a significant impact on the indoor air. The results showed that furniture on the Danish market may have an emission of formaldehyde resulting in indoor concentrations above the WHO recommended limit of 0.1 mg m-3. Therefore...

  3. Low Temperature Emissivity Measurement System

    Directory of Open Access Journals (Sweden)

    Jignesh A. Patel

    2014-05-01

    Full Text Available The emissivity of a material is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. Knowledge about the low temperature emissivity of materials and coatings can be essential to the design of fusion cryoplants and in the thermal modeling for space satellite missions. The emittance of materials at cryogenics temperatures often cannot be predicted from room temperature data, but for computing radiative loads and infrared backgrounds this cryogenic data is often required. Measurement of the cryogenic emissivity of a highly reflective surface is a significant challenge: little thermal power is radiated from the sample, and the background radiation. However some researchers have measured emissivity at various low temperature ranges. Present work reports, the various emissivity measurement setup and their considerations.

  4. Nanoparticle emissions from combustion engines

    CERN Document Server

    Merkisz, Jerzy

    2015-01-01

     This book focuses on particulate matter emissions produced by vehicles with combustion engines. It describes the physicochemical properties of the particulate matter, the mechanisms of its formation and its environmental impacts (including those on human beings). It discusses methods for measuring particulate mass and number, including the state-of-the-art in Portable Emission Measurement System (PEMS) equipment for measuring the exhaust emissions of both light and heavy-duty vehicles and buses under actual operating conditions. The book presents the authors’ latest investigations into the relations between particulate emission (mass and number) and engine operating parameters, as well as their new findings obtained through road tests performed on various types of vehicles, including those using diesel particulate filter regeneration. The book, which addresses the needs of academics and professionals alike, also discusses relevant European regulations on particulate emissions and highlights selected metho...

  5. The Venus Emissivity Mapper

    Science.gov (United States)

    Helbert, Joern; Marcq, Emmanuel; Widemann, Thomas; Mueller, Nils; Kappel, David; Tsang, Constantine; Maturilli, Alessandro; Ferrari, Sabrina; D'Amore, Mario; Dyar, Melinda; Smrekar, Suzanne

    2016-10-01

    The permanent cloud cover of Venus prohibits observations of the surface with traditional imaging techniques over the entire visible spectral range. Fortunately, Venus' atmospheric gases are largely transparent in narrow spectral windows near 1 mm. Ground observers were the first to successfully use these windows, followed by spacecraft observations during the flyby of the Galileo mission on its way to Jupiter and most recently from Venus orbit by ESA's Venus Express with the VMC and VIRTIS instruments. Analyses of VIRTIS measurements have successfully demonstrated that surface information can be extracted from these windows, but the design of the instrument limited its use for more in-depth surface investigations.Based on experience gained from using VIRTIS to observe the surface of Venus and new high temperature laboratory experiments currently performed at the Planetary Spectroscopy Laboratory of DLR, we have designed the multi-spectral Venus Emissivity Mapper (VEM). Observations from VIRTIS have revealed surface emissivity variations correlated with geological features, but existing data sets contain only three spectral channels. VEM is optimized to map the surface composition and texture, and to search for active volcanism using the narrow atmospheric windows, building on lessons from prior instrumentation and methodology. It offers an opportunity to gain important information about surface mineralogy and texture by virtue of having six different channels for surface mapping.VEM is focused mainly on observing the surface, mapping in all near-IR atmospheric windows using filters with spectral characteristics optimized for the wavelengths and widths of those windows. It also observes bands necessary for correcting atmospheric effects; these bands also provide valuable scientific data on composition as well as altitude and size distribution of the cloud particles, and on H2O vapor abundance variations in the lowest 15 km of the atmosphere.In combination with a

  6. 40 CFR 61.32 - Emission standard.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Emission standard. 61.32 Section 61.32... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Beryllium § 61.32 Emission standard. (a) Emissions to the atmosphere from stationary sources subject to the provisions of this...

  7. 40 CFR 61.42 - Emission standard.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Emission standard. 61.42 Section 61.42... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Beryllium Rocket Motor Firing § 61.42 Emission standard. (a) Emissions to the atmosphere from rocket-motor test sites shall...

  8. 40 CFR 61.162 - Emission limits.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Emission limits. 61.162 Section 61.162... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Inorganic Arsenic Emissions From Glass Manufacturing Plants § 61.162 Emission limits. (a) The owner or operator of an...

  9. 40 CFR 61.52 - Emission standard.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Emission standard. 61.52 Section 61.52... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Mercury § 61.52 Emission standard. (a) Emissions to the atmosphere from mercury ore processing facilities and mercury cell...

  10. Emissions from RDF combustion

    International Nuclear Information System (INIS)

    The paper deals with the emissions from refuse derived fuel (RDF) combustion. The disposal of refuse has during the last years been a matter of increasing concern for many municipalities. The environment options for waste disposal has not been focusing much. This means that first the waste generation must be reduced. Then recycling of a portion of the waste must be considered before a solution with combustion of waste is chosen. Two methods are currently in use for the combustion of municipal solid waste (MSW) which are the mass burning of unprocessed MSW and RDF. The RDF product consists of the burnable organic fraction of raw MSW. In contrast to mass burning systems, the RDF-system is pre-processing the raw MSW to make a more homogeneous fuel product. By processing the MSW, it is possible to recover RDF and other materials. The RDF process is a low cost approach to resource recovery. RDF is a merchant fuel, and can be used in existing boilers alone or as a supplement to conventional fuels as oil and coal. It is important that the RDF processing technology and RDF quality matches the energy user requirements. The RDF-processing-systems is of great importance to the RDF quality. The paper shows the different steps in the RDF process. 4 refs., 15 figs

  11. Diffuse Microwave Emission Survey

    Science.gov (United States)

    Shafer, R. A.; Mather, J.; Kogut, A.; Fixsen, D. J.; Seiffert, M.; Lubin, P. M.; Levin, S. M.

    1996-12-01

    The Diffuse Microwave Emission Survey (DIMES) is a mission concept selected by NASA in 1995 to answer fundamental questions about the content and history of the universe. DIMES will use a set of absolutely calibrated cryogenic radiometers from a space platform to measure the frequency spectrum of the cosmic microwave background (CMB) at wavelengths 15--0.3 cm (frequency 2--100 GHz) to precision 0.1 mK or better. Measurements at centimeter wavelengths probe different physical processes than the COBE-FIRAS spectra at shorter wavelengths, and complement the anisotropy measurements from DMR, balloon and ground-based instruments, and the planned MAP and COBRAS/SAMBA satellites. DIMES will observe the free-free signal from early photoionization to establish the precise epoch of structure formation, and will measure or limit energy release at redshift 10(4) theory and allowed by current measurement limits; even an upper limit at the expected sensitivity 10(-5) MJy/sr will place important constraints on the matter content, structure, and evolution of the universe. Detecting these distortions or showing that they do not exist constitutes the last frontier of CMB observations.

  12. Methane emission from sewers.

    Science.gov (United States)

    Liu, Yiwen; Ni, Bing-Jie; Sharma, Keshab R; Yuan, Zhiguo

    2015-08-15

    Recent studies have shown that sewer systems produce and emit a significant amount of methane. Methanogens produce methane under anaerobic conditions in sewer biofilms and sediments, and the stratification of methanogens and sulfate-reducing bacteria may explain the simultaneous production of methane and sulfide in sewers. No significant methane sinks or methanotrophic activities have been identified in sewers to date. Therefore, most of the methane would be emitted at the interface between sewage and atmosphere in gravity sewers, pumping stations, and inlets of wastewater treatment plants, although oxidation of methane in the aeration basin of a wastewater treatment plant has been reported recently. Online measurements have also revealed highly dynamic temporal and spatial variations in methane production caused by factors such as hydraulic retention time, area-to-volume ratio, temperature, and concentration of organic matter in sewage. Both mechanistic and empirical models have been proposed to predict methane production in sewers. Due to the sensitivity of methanogens to environmental conditions, most of the chemicals effective in controlling sulfide in sewers also suppress or diminish methane production. In this paper, we review the recent studies on methane emission from sewers, including the production mechanisms, quantification, modeling, and mitigation. PMID:25889543

  13. Pricing hazardous substance emissions

    Energy Technology Data Exchange (ETDEWEB)

    Staring, Knut; Vennemo, Haakon

    1997-12-31

    This report discusses pricing of emissions to air of several harmful substances. It combines ranking indices for environmentally harmful substances with economic valuation data to yield price estimates. The ranking methods are discussed and a relative index established. Given the relative ranking of the substances, they all become valued by assigning a value to one of them, the `anchor` substance, for which lead is selected. Valuations are provided for 19 hazardous substances that are often subject to environmental regulations. They include dioxins, TBT, etc. The study concludes with a discussion of other categories of substances as well as uncertainties and possible refinements. When the valuations are related to CO, NOx, SOx and PM 10, the index system undervalues these pollutants as compared to other studies. The scope is limited to the outdoor environment and does not include global warming and eutrophication. The indices are based on toxicity and so do not apply to CO{sub 2} or other substances that are biologically harmless. The index values are not necessarily valid for all countries and should be considered as preliminary. 18 refs., 6 tabs.

  14. Emission-free valve

    Energy Technology Data Exchange (ETDEWEB)

    Koppe, W.; Prummer, R.

    1980-07-01

    a description is given of an emission-free valve, particularly a magnetically operated valve, for use in controlling the flow of fluids, especially poisonous, radioactive, aggressive and otherwise dangerous gases and fluids, comprising a housing including a housing member which has substantially spherical configuration and an internal surface surrounding a compartment for the respective fluid, said housing further including an annular valve seat member; a valve member movably mounted in said compartment and cooperating with said valve seat member to control the flow of the fluid through said compartment; and a plating layer of a corrosion-resistant material covering said internal surface of said housing member and also having a substantially spherical configuration corresponding to that of said housing member, said housing member and said plating layer obtaining their respective configurations during an explosion which not only simultaneously deforms initially cylindrical tubular and coaxially arranged housing member and plating layer preforms, but also welds said plating layer preform to said housing member preform so that said platinglayer is explosion-welded to said housing member.

  15. Monoterpene emission from ponderosa pine

    Science.gov (United States)

    Lerdau, Manual; Dilts, Stephen B.; Westberg, Hal; Lamb, Brian K.; Allwine, Eugene J.

    1994-01-01

    We explore the variability in monoterpene emissions from ponderosa pine beyond that which can be explained by temperature alone. Specifically, we examine the roles that photosynthesis and needle monoterpene concentrations play in controlling emissions. We measure monoterpene concentrations and emissions, photosynthesis, temperature, and light availability in the late spring and late summer in a ponderosa pine forest in central Oregon. We use a combination of measurements from cuvettes and Teflon bag enclosures to show that photosynthesis is not correlated with emissions in the short term. We also show that needle monoterpene concentrations are highly correlated with emissions for two compounds, alpha-pinene and beta-pinene, but that Delta-carene concentrations are not correlated with emissions. We suggest that direct effects of light and photosynthesis do not need to be included in emission algorithms. Our results indicate that the role of needle concentration bears further investigation; our results for alpha-pinene and beta-pinene are explainable by a Raoult's law relationship, but we cannot yet explain the cause of our results with Delta-carene.

  16. Advanced Collaborative Emissions Study (ACES)

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, Daniel; Costantini, Maria; Van Erp, Annemoon; Shaikh, Rashid; Bailey, Brent; Tennant, Chris; Khalek, Imad; Mauderly, Joe; McDonald, Jacob; Zielinska, Barbara; Bemis, Jeffrey; Storey, John; Hallberg, Lance; Clark, Nigel

    2013-12-31

    The objective of the Advanced Collaborative Emissions Study (ACES) was to determine before widespread commercial deployment whether or not the new, energy-efficient, heavy duty diesel engines (2007 and 2010 EPA Emissions Standards Compliant) may generate anticipated toxic emissions that could adversely affect the environment and human health. ACES was planned to take place in three phases. In Phase 1, extensive emissions characterization of four production-intent prototype engine and control systems designed to meet 2007 standards for nitrogen oxides (NOx) and particulate matter (PM) was conducted at an existing emissions characterization facility: Southwest Research Institute (SwRI). One of the tested engines was selected (at random, after careful comparison of results) for health testing in Phase 3. In Phase 2, extensive emission characterization of three production-intent prototype engine and control systems meeting the 2010 standards (including more advanced NOx controls to meet the more stringent 2010 NOx standards) was conducted at the same test facility. In Phase 3, one engine/aftertreatment system selected from Phase 1 was further characterized during health effects studies (at an existing inhalation toxicology laboratory: Lovelace Respiratory Research Institute, [LRRI]) to form the basis of the ACES safety assessment. The Department of Energy (DOE) award provided funding for emissions characterization in Phases 1 and 2 as well as exposure characterization in Phase 3. The main health analyses in Phase 3 were funded separately and are not reported here.

  17. Reducing ammonia emissions in Europe

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.

    2011-01-01

    The NEC directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries with the largest reductions since 1990...... to the high expectations at the outset. Despite this, the paper concludes that Denmark is likely to reduce emission by 50% from 1990 to 2020 and reach the likely 2020 NEC ceiling....

  18. Radio emission in Mercury magnetosphere

    OpenAIRE

    Varela, J.; Reville, V.; Brun, A. S.; Pantellini, F.; Zarka, P.

    2016-01-01

    Context: Active stars possess magnetized wind that has a direct impact on planets that can lead to radio emission. Mercury is a good test case to study the effect of the solar wind and interplanetary magnetic field on radio emission driven in the planet magnetosphere. Such studies could be used as proxies to characterize the magnetic field topology and intensity of exoplanets. Aims: The aim of this study is to quantify the radio emission in the Hermean magnetosphere. Methods: We use the MHD c...

  19. Zero emission city. Preliminary study; Null-Emissions-Stadt. Sondierungsstudie

    Energy Technology Data Exchange (ETDEWEB)

    Diefenbach, N.; Enseling, A.; Werner, P.; Flade, A.; Greiff, R.; Hennings, D.; Muehlich, E.; Wullkopf, U.; Sturm, P.; Kieslich, W.; Born, R.; Grossklos, M.; Hatteh, R.; Mueller, K.; Ratschow, A.; Valouch-Fornoff, C.

    2002-10-01

    The idea of a 'zero emission city' is investigated by the Institut Wohnen und Umwelt on behalf of the Federal Minister of Education and Research. After describing the current situation and defining the key parameters of a 'zero emission city', settlement structures, power supply, production processes and transportation are analyzed and linked with the communal action level to obtain a framework for research, activities and actions. The study ends with recommendations for a research programme 'zero emission city'. (orig.) [German] Die von den Staedten der Industrielaender ausgehenden Emissionen stellen im Hinblick auf die globalen Belastungen wie z.B. Treibhauseffekt, Ozonabbau und Versauerung das Hauptproblem dar. Aus diesem Grunde bietet es sich an, den Gedanken der 'Null-Emissions-Stadt', der Vision einer moeglichst emissionsfreien Stadt, aufzugreifen und auf seine Tragfaehigkeit fuer innovative Handlungsmodelle forschungsstrategisch zu ueberpruefen. Das Bundesministerium fuer Bildung und Forschung hat das Institut Wohnen und Umwelt beauftragt, in einer Sondierungsstudie dieser Fragestellung nachzugehen. Nach der Festlegung der Ausgangsbedingungen und Eckpunkte der Vision 'Null-Emissions-Stadt' und der Analyse der vier Handlungsfelder Siedlungsstrukturen, Energieversorgung, Produktionsprozesse (Kreislaufwirtschaft) und Verkehr werden diese aufgegriffen und mit der kommunalen Handlungsebene verknuepft und zu einem Forschungs-, Handlungs- und moeglichen Aktionsrahmen zusammengefuegt. Die Studie schliesst mit Hinweisen fuer die Gestaltung eines Forschungsprogramms 'Null-Emissions-Stadt'. (orig.)

  20. Properly designed emissions trading schemes do work!

    OpenAIRE

    Carmona, Rene; Fehr, Max; Hinz, Juri

    2009-01-01

    Emissions trading markets have been touted as the most efficient mechanism to achieve environmental goals at least cost. Whether in the form of voluntary markets or in a mandatory framework like in the first phase of the European Union (EU) Emission Trading Scheme (ETS), the regulator sets a cap on the emissions which can occur without penalty, and provides emissions allowances accordingly. The recipients are free to use these emission certificates to cover their emissions, or to sell them...

  1. The Effects of Differentiated Emission Taxes

    OpenAIRE

    Takeda, Shiro

    2001-01-01

    Extending the standard 2 x 2 Heckscher-Ohlin-Samuelson model to include emission as the third production factor, we consider the effects of emission taxes on outputs and the level of emission. The following results are derived. First, an increase in emission tax imposed on one industry may paradoxically increase the outputs of the industry. Second, an increase in emission tax imposed on one industry may raise the total level of emission.

  2. Danish emission inventory for particular matter (PM)

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, M.; Winther, M.; Illerup, J.B.; Hjort Mikkelsen, M.

    2003-11-01

    The first Danish emission inventory that was reported in 2002 was a provisional-estimate based on data presently available. This report documents methodology, emission factors and references used for an improved Danish emission inventory for particulate matter. Further results of the improved emission inventory for the year 2000 are shown. The particulate matter emission inventory includes TSP, PM,, and PM, The report covers emission inventories for transport and stationary combustion. An appendix covering emissions from agriculture is also included. For the transport sector, both exhaust and non-exhaust emission such as tyre and break wear and road abrasion are included. (au)

  3. Electrochromic Variable-Emissivity Surfaces

    Science.gov (United States)

    Rauh, R. David; Cogan, Stuart F.

    1988-01-01

    Temperature controlled by altering infrared radiative properties. Infrared emissivity of electrochromically active layer changed by applying voltage to insert or remove Li atoms electrochemically. Change reversible and continuously variable between specified limits of layered structure.

  4. Emissivity measurements on aeronautical alloys

    Energy Technology Data Exchange (ETDEWEB)

    Campo, L. del, E-mail: leire.del-campo@cnrs-orleans.f [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Perez-Saez, R.B., E-mail: raul.perez@ehu.e [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao (Spain); Gonzalez-Fernandez, L. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Esquisabel, X.; Fernandez, I. [Industria de Turbo Propulsores, S.A., Planta de Zamudio, Edificio 300, 48170 Zamudio, Bizkaia (Spain); Gonzalez-Martin, P. [Industria de Turbo Propulsores, S.A., Parque empresarial San Fernando, Avda. Castilla 2, 28830 San Fernando de Henares, Madrid (Spain); Tello, M.J. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao (Spain)

    2010-01-21

    The emissivity of three Ni and Co based aeronautical alloys is analyzed in this paper. These alloys are employed in high temperature environments whenever good corrosion resistance, high temperature resistance and high strength are essential. Thus, apart from the aeronautical industry, these alloys are also used in other technological applications, as for example, aerospace, nuclear reactors, and tooling. The results in this paper extend the emissivity data for these alloys available in the literature. Emissivity dependence on the radiation wavelength (2-22 {mu}m), sample temperature (200-650 {sup o}C) and emission angle (0-85{sup o}) has been investigated. In addition, the effect of surface finish and oxidation has also been taken into consideration. The data in this paper have several applications, as temperature measurement of a target by pyrometry, low observability of airplanes and thermal radiation heat transfer simulation in airplane nozzles or furnaces.

  5. Controlling radiated emissions by design

    CERN Document Server

    Mardiguian, Michel

    2014-01-01

    The 3rd edition of Controlling Radiated Emissions by Design has been updated to reflect the latest changes in the field. New to this edition is material related to technical advances, specifically super-fast data rates on wire pairs, with no increase in RF interference. Throughout the book, details are given to control RF emissions using EMC design techniques. This book retains the step-by-step approach for incorporating EMC into every new design from the ground up. It describes the selection of quieter IC technologies, their implementation into a noise-free printed circuit layout, and the gathering of these into a low emissions package. Also included is how to design an I/O filter, along with connectors and cable considerations. All guidelines are supported throughout with comprehensive calculated examples. Design engineers, EMC specialists, and technicians will benefit from learning about the development of more efficient and economical control of emissions.

  6. Advanced Emissions Control Development Program

    Energy Technology Data Exchange (ETDEWEB)

    A.P.Evans; K.E. Redinger; M.J. Holmes

    1998-04-01

    The objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W).

  7. Photon upconversion with directed emission

    Science.gov (United States)

    Börjesson, K.; Rudquist, P.; Gray, V.; Moth-Poulsen, K.

    2016-08-01

    Photon upconversion has the potential to increase the efficiency of single bandgap solar cells beyond the Shockley Queisser limit. Efficient light management is an important point in this context. Here we demonstrate that the direction of upconverted emission can be controlled in a reversible way, by embedding anthracene derivatives together with palladium porphyrin in a liquid crystalline matrix. The system is employed in a triplet-triplet annihilation photon upconversion scheme demonstrating controlled switching of directional anti Stokes emission. Using this approach an emission ratio of 0.37 between the axial and longitudinal emission directions and a directivity of 1.52 is achieved, reasonably close to the theoretical maximal value of 2 obtained from a perfectly oriented sample. The system can be switched for multiple cycles without any visible degradation and the speed of switching is only limited by the intrinsic rate of alignment of the liquid crystalline matrix.

  8. Emission Impacts of Electric Vehicles

    OpenAIRE

    Wang, Quanlu; DeLuchi, Mark A.; Sperling, Daniel

    1990-01-01

    Alternative vehicular fuels are proposed as a strategy to reduce urban air pollution. In this paper, we analyze the emission impacts of electric vehicles in California for two target years, 1995 and 2010. We consider a range of assumptions regarding electricity consumption of electric vehicles, emission control technologies for power plants, and the mix of primary energy sources for electricity generation. We find that, relative to continued use of gasoline-powered vehicles, the use of electr...

  9. Thermal emissivity of avian eggshells.

    Science.gov (United States)

    Björn, Lars Olof; Bengtson, Sven-Axel; Li, Shaoshan; Hecker, Christoph; Ullah, Saleem; Roos, Arne; Nilsson, Annica M

    2016-04-01

    The hypothesis has been tested that evolution has resulted in lower thermal emissivity of eggs of birds breeding openly in cold climates than of eggs of birds that nest under protective covering or in warmer climates. Directional thermal emissivity has been estimated from directional-hemispherical reflectance spectra. Due to several methodological difficulties the absolute emissivity is not accurately determined, but differences between species are obvious. Most notably, small waders of the genus Calidris, breeding in cold climates on the tundra, and in most cases with uniparental nest attendance, have low directional emissivity of their eggshells, about 0.92 when integration is carried out for wavelengths up to 16μm. Species belonging to Galloanserinae have the highest directional emissivity, about 0.96, of their eggs. No differences due to climate or breeding conditions were found within this group. Eggs of most other birds tested possess intermediate emissivity, but the values for Pica pica and Corvus corone cornix are as low as for Calidris. Large species-dependent differences in spectral reflectance were found at specific wavelengths. For instance, at 4.259μm the directional-hemispherical reflectance for galliforms range from 0.05 to 0.09, while for Fratercula arctica and Fulmarus glacialis it is about 0.3. The reflection peaks at 6.5 and 11.3μm due to calcite are differentially attenuated in different species. In conclusion, the hypothesis that evolution has resulted in lower thermal emissivity of bird eggs being exposed in cold climates is not supported by our results. The emissivity is not clearly related to nesting habits or climate, and it is unlikely that the small differences observed are ecologically important. The spectral differences between eggs that nevertheless exist should be taken into account when using infrared thermometers for estimating the surface temperature of avian eggs.

  10. Thermal emissivity of avian eggshells.

    Science.gov (United States)

    Björn, Lars Olof; Bengtson, Sven-Axel; Li, Shaoshan; Hecker, Christoph; Ullah, Saleem; Roos, Arne; Nilsson, Annica M

    2016-04-01

    The hypothesis has been tested that evolution has resulted in lower thermal emissivity of eggs of birds breeding openly in cold climates than of eggs of birds that nest under protective covering or in warmer climates. Directional thermal emissivity has been estimated from directional-hemispherical reflectance spectra. Due to several methodological difficulties the absolute emissivity is not accurately determined, but differences between species are obvious. Most notably, small waders of the genus Calidris, breeding in cold climates on the tundra, and in most cases with uniparental nest attendance, have low directional emissivity of their eggshells, about 0.92 when integration is carried out for wavelengths up to 16μm. Species belonging to Galloanserinae have the highest directional emissivity, about 0.96, of their eggs. No differences due to climate or breeding conditions were found within this group. Eggs of most other birds tested possess intermediate emissivity, but the values for Pica pica and Corvus corone cornix are as low as for Calidris. Large species-dependent differences in spectral reflectance were found at specific wavelengths. For instance, at 4.259μm the directional-hemispherical reflectance for galliforms range from 0.05 to 0.09, while for Fratercula arctica and Fulmarus glacialis it is about 0.3. The reflection peaks at 6.5 and 11.3μm due to calcite are differentially attenuated in different species. In conclusion, the hypothesis that evolution has resulted in lower thermal emissivity of bird eggs being exposed in cold climates is not supported by our results. The emissivity is not clearly related to nesting habits or climate, and it is unlikely that the small differences observed are ecologically important. The spectral differences between eggs that nevertheless exist should be taken into account when using infrared thermometers for estimating the surface temperature of avian eggs. PMID:27033033

  11. Methane Emissions from Upland Forests

    Science.gov (United States)

    Megonigal, Patrick; Pitz, Scott; Wang, Zhi-Ping

    2016-04-01

    Global budgets ascribe 4-10% of atmospheric methane sinks to upland soils and assume that soils are the sole surface for methane exchange between upland forests and the atmosphere. The dogma that upland forests are uniformly atmospheric methane sinks was challenged a decade ago by the discovery of abiotic methane production from plant tissue. Subsequently a variety of relatively cryptic microbial and non-microbial methane sources have been proposed that have the potential to emit methane in upland forests. Despite the accumulating evidence of potential methane sources, there are few data demonstrating actual emissions of methane from a plant surface in an upland forest. We report direct observations of methane emissions from upland tree stems in two temperate forests. Stem methane emissions were observed from several tree species that dominate a forest located on the mid-Atlantic coast of North America (Maryland, USA). Stem emissions occurred throughout the growing season while soils adjacent to the trees simultaneously consumed methane. Scaling fluxes by stem surface area suggested the forest was a net methane source during a wet period in June, and that stem emissions offset 5% of the soil methane sink on an annual basis. High frequency measurements revealed diurnal cycles in stem methane emission rates, pointing to soils as the methane source and transpiration as the most likely pathway for gas transport. Similar observations were made in an upland forest in Beijing, China. However, in this case the evidence suggested the methane was not produced in soils, but in the heartwood by microbial or non-microbial processes. These data challenge the concept that forests are uniform sinks of methane, and suggest that upland forests are smaller methane sinks than previously estimated due to stem emissions. Tree emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration.

  12. Reducing environmental emissions in tanneries.

    Science.gov (United States)

    van Groenestijn, J W; Langerwerf, J S A; Lucas, M

    2002-01-01

    Tanning, in particular chrome leather production, is still characterised by an inefficient use of raw material and the production of highly polluted wastewater and solid wastes. A part of the emissions can be prevented by introducing clean tanning technologies, the remaining emissions can be treated. Clean production technologies and waste (water) treatment technologies should have a designed complimentarity. Anaerobic wastewater treatment with recovery of sulfides, sulfur and energy (biogas) is a cornerstone in such integral clean chrome leather technology.

  13. Emissivity of rocket plume particulates.

    OpenAIRE

    Whisman, Curtis D.

    1992-01-01

    The optical properties of motor aluminum oxide are required inputs to current plume signature prediction codes, such as SIRRM. Accurate predictions are possible only if variations in the particle emissivity due to changes in particle size, contamination, and changing temperature, etc. , are known . This investigation demonstrated a simplified method for determination of the emissivity of rocket motor generated alumina. Plume particulate material was collected on ...

  14. Low Temperature Emissivity Measurement System

    OpenAIRE

    Jignesh A. Patel

    2014-01-01

    The emissivity of a material is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. Knowledge about the low temperature emissivity of materials and coatings can be essential to the design of fusion cryoplants and in the thermal modeling for space satellite missions. The emittance of materials at cryogenics temperatures often cannot be predicted f...

  15. Pollutant emissions from modern incinerators

    OpenAIRE

    Lima, R.; Bachmann, R

    2002-01-01

    Presently, emissions of dioxins are mainly from incinerators, domestic and industrial coal combustion, and traffic. However, the major public concern and research effort are associated with the emissions of organic micropollutants from waste incinerators. Therefore, this paper attempts to give a brief overview on the more recent research and development for the removal of dioxins and heavy metals from flue gas streams. Special attention is devoted to the origin and control of e...

  16. Estimating Emissions from Railway Traffic

    DEFF Research Database (Denmark)

    Jørgensen, Morten W.; Sorenson, Spencer C.

    1998-01-01

    Several parameters of importance for estimating emissions from railway traffic are discussed, and typical results presented. Typical emissions factors from diesel engines and electrical power generation are presented, and the effect of differences in national electrical generation sources...... illustrated as well as the degree of electrification for different countries. Traffic parameters such as passenger occupancy rates, per capita freight and passenger traffic are presented for European conditions. The relationship between average train speed and distance between stops is shown for a variety...

  17. Estimating emissions from railway traffic

    Energy Technology Data Exchange (ETDEWEB)

    Joergensen, M.W.; Sorenson, C.

    1997-07-01

    The report discusses methods that can be used to estimate the emissions from various kinds of railway traffic. The methods are based on the estimation of the energy consumption of the train, so that comparisons can be made between electric and diesel driven trains. Typical values are given for the necessary traffic parameters, emission factors, and train loading. Detailed models for train energy consumption are presented, as well as empirically based methods using average train speed and distance between stop. (au)

  18. Study Acoustic Emissions from Composites

    Science.gov (United States)

    Walker, James; Workman,Gary

    1998-01-01

    The purpose of this work will be to develop techniques for monitoring the acoustic emissions from carbon epoxy composite structures at cryogenic temperatures. Performance of transducers at temperatures ranging from ambient to cryogenic and the characteristics of acoustic emission from composite structures will be studied and documented. This entire effort is directed towards characterization of structures used in NASA propulsion programs such as the X-33.

  19. Reducing environmental emissions in tanneries.

    Science.gov (United States)

    van Groenestijn, J W; Langerwerf, J S A; Lucas, M

    2002-01-01

    Tanning, in particular chrome leather production, is still characterised by an inefficient use of raw material and the production of highly polluted wastewater and solid wastes. A part of the emissions can be prevented by introducing clean tanning technologies, the remaining emissions can be treated. Clean production technologies and waste (water) treatment technologies should have a designed complimentarity. Anaerobic wastewater treatment with recovery of sulfides, sulfur and energy (biogas) is a cornerstone in such integral clean chrome leather technology. PMID:12046670

  20. Emissions trading under market imperfections

    Energy Technology Data Exchange (ETDEWEB)

    Lappi, P.

    2013-08-15

    In this thesis we consider emissions trading under various market imperfections such as uncertainty over permit price, imperfect competition and noncompliance. First, we study the effects of uncertain permit price on the firms choice of emission intensive and clean inputs in an multi-input production process. We also assess the risk aversion factors of some Finnish heat and power producers. Second, we study imperfect competition in output and permit markets with a two-stage model, where output decision is made before permit trades. The emphasis is on the strategic interaction between firms and on the efficiency increasing regulation. Third, we turn back to uncertainty and analyse the welfare difference between emissions trading and emission tax, when some of the firms may be noncompliant. The main finding is that welfare is greater with emission tax than with emissions trading, when at least one firm is noncompliant. Finally, we extend some existing models of permit banking and borrowing to encompass also noncompliant behavior of firms. Here, we analyse the incentives of compliant firms to become noncompliant at some point in time and also the time paths of the choice variables. (orig.)

  1. Methane emissions in the Netherlands

    International Nuclear Information System (INIS)

    Methane is the most important greenhouse gas after carbon dioxide. Detailed national emission estimates are needed to narrow the gap between world emission estimates and budget results from atmospheric chemistry. These estimates have to be based on sound emission factors and better extrapolation of methane measurement results. The article identifies the most important sources of methane in the Netherlands as landfills, ruminants, manure and the production, distribution and combustion of gas. It explains that emissions from landfills will decrease as a result of policies to reduce landfilling. The encouragement of increased internal use of otherwise vented gas on oil and gas production platforms and the planned extra maintenance of destribution networks should further decrease emissions. Policies to reduce milk and beef surplus and the introduction of new types of stabling and manure handling systems will reduce emissions in the agriculture sector. These measures should produce a total reduction of methane of 20% in 2000 with respect to 1990 levels. 5 refs., 3 figs., 2 tabs

  2. Offsetting Ongoing Methane Emissions --- An Alternative to Emission Equivalence Metrics

    Science.gov (United States)

    Clisby, N.; Enting, I. G.; Lauder, A.; Carter, J.; Cowie, A.; Henry, B.; Raupach, M. R.

    2012-12-01

    The Global Warming Potential (GWP) has been widely adopted as a metric for comparing the climate impact of different greenhouse gases. As has been frequently noted, there are many problems with using GWPs to define emission equivalence in spite of the use of GWPs for this purpose in contexts such as the Kyoto Protocol. We propose that for methane, rather than define emission equivalence, the appropriate comparison is between ongoing emissions of 0.9 to 1.0 kg of CH4 per year and one-off emissions of 1 tonne of carbon. This approach represents an approximate solution to the inverse problem of defining a forcing equivalent index (FEI) that gives exact equivalence of radiative forcing over a range of timescales. In our approach, if ongoing methane emissions are offset by a one-off carbon removal that is built up with 40-year e-folding time, then the result is close to radiatively neutral over periods from years to centuries. In contrast, the GWP provides radiative equivalence (in integrated terms) only at a single time, with large discrepancies at other times. Our approach also follows from consideration of greenhouse gas stabilisation, since stabilising atmospheric CO2 requires an approximate cap on total emissions, while stabilising methane requires stabilisation of ongoing emissions. Our quantitative treatment recognises that, on time scales of centuries, removal of 1 tonne of carbon only lowers the atmospheric carbon content by 0.3 to 0.35 tonnes. We discuss the implications for rangeland grazing systems. In the absence of effective mitigation techniques for methane from rangeland systems, this approach may provide an attractive offset mechanism in spite of requiring that woody vegetation be established and maintained over about 15% of the landscape, or an equivalent amount of carbon storage in soil.

  3. ECO2, Emissions Trading Services, development project

    International Nuclear Information System (INIS)

    Emissions Trading started within EU at the beginning of 2005. It caused substantial changes to the business environment of energy companies and energy intensive industry. The planning of Emissions Trading is a complicated process and companies will need consulting, IT systems and other services. Emissions Trading introduces a new factor of production emission allowances, which are tradable commodities. In future, Emissions Trading emissions, emission allowances and the prices of emission allowances have to be considered during the fuel purchasing and the energy production planning. And the best possible knowledge of the own emissions balance and market situation has a monetary value when trading emission allowances. Allocation of emission allowances has done in each country according to National Allocation Plan (NAP), accepted by EU. Finland itself and thus also the Finnish companies will be net buyers of emission allowances in long run. That means commonly that the Finnish companies have to buy more allowances meaning some extra costs to the companies. That's why it is very important to develop and provide to the companies an innovatory emissions planning, follow-up, management and reporting systems. With good emission balance management the extra costs of Emissions Trading will be as low as possible. In ECO2 project, Empower together with Power-Deriva, developed Expert services, Emissions Balance Management and Reporting services and Risk Management services for Emissions Trading and needed software and tools for these services. (orig.)

  4. Martian Analogues Emissivity Spectra From the Berlin Emissivity Database (BED)

    Science.gov (United States)

    Maturilli, A.; Helbert, J.; Moroz, L.

    2006-12-01

    Remote sensing infrared spectroscopy is the principal field of investigation for planetary surfaces composition. Past, present and future missions to bodies in the solar system include in their payload instruments measuring the emerging radiation in the infrared range. For the interpretation of the measured data an emissivity spectral library of planetary analog materials is needed. The Berlin Emissivity Database (BED) currently contains emissivity spectra of plagioclase and potassium feldspars, low Ca and high Ca pyroxenes, olivine, elemental sulphur, and Martian analogue minerals, measured in the wavelength range from 7 to 22 microns as a function of particle size. For each sample we measured the spectra of four particle size separates ranging from 0 to 250 microns. The device we used is built at DLR (Berlin) and is coupled to a Fourier transform infrared spectrometer (Bruker IFS 88), purged with dry air and equipped with a cooled detector (MCT). All spectra were acquired with a spectral resolution of 4 cm-1. We present here the results of our analysis on well knew and characterized Martian analogue minerals: JSC Mars-1, Salten Skov, and Palagonite from Mauna Kea, Hawaii. We are currently working to upgrade our emissivity facility. A new spectrometer (Bruker VERTEX 80v) and new detectors will allow us to measure the emissivity of samples in the wavelength range from 1 to 50 microns, even in a vacuum environment.

  5. Austrian emission inventory for dust

    International Nuclear Information System (INIS)

    For the first time, Austrian emissions of anthropogenic particulate matter emissions to the atmosphere have been estimated. Results have been reported as total suspended particles (TSP) as well as for the fractions of particles smaller than 10 μm or 2.5 μm aerodynamic diameter (PM10, PM2.5), respectively. Base years for the inventory were 1990, 1995 and 1999. Excluded from this assessment is wind blown dust, which has been considered a natural source here. National statistics have been applied, specifically those also used previously in the Austrian air pollution inventory (OLI). Emission factors have been taken from literature compilations, only for exceptional cases specific Austrian assessments were performed or original literature on emission measurements was consulted. Resuspension of dust by road traffic emerged as the most important source. For the size fraction of PM10 this source contributed about half of the emissions, when applying the calculation scheme by the U.S. EPA. While this scheme is widely used and well documented, its validity is currently subject of intense scientific debate. As these results do not seem to coincide with ambient air measurements, resuspension of road dust is considered separately and not now included in the national total. The sum of all other sources increases from 75,000 t of TSP in 1990 and 1995 to 77,000 t in 1999, while both PM10 and PM2.5 exhibit decreasing tendency (at 45,000 t and 26,000 t in 1999, respectively). The increase in TSP derives from increasing traffic and friction related emissions (tire wear, break wear), decrease of the finer particulate matter is due to reductions in firewood consumption for domestic heating. Most important source sectors are fugitive emissions from material transfer in industry as well as the building industry and the tilling of agricultural land. Common to these sources is the high uncertainty of available data. Wood combustion is the most important of the non-fugitive emissions

  6. The Berlin emissivity database (BED)

    Science.gov (United States)

    Maturilli, A.; Helbert, J.; Moroz, L.

    2008-03-01

    Remote-sensing infrared spectroscopy is the principal field of investigation for planetary surfaces composition. Past, present and future missions to the solar system bodies include in their payload, instruments measuring the emerging radiation in the infrared range. Apart from measuring the reflected radiance, more and more spacecrafts are equipped with instruments measuring directly the emitted radiation from the planetary surface. The emitted radiation is not only a function of the composition of the material but also of its texture and especially the grain size distribution. For the interpretation of the measured data an emissivity spectral library of planetary analogue materials in grain size fractions appropriate for planetary surfaces is needed. The Berlin emissivity database (BED) presented here is focused on relatively fine-grained size separates, providing thereby a realistic basis for the interpretation of thermal emission spectra of planetary regoliths. The BED is therefore complimentary to existing thermal emission libraries, like the ASU library for example. BED currently contains emissivity spectra of plagioclase and potassium feldspars, low Ca and high Ca pyroxenes, olivine, elemental sulfur, Martian analogue minerals and volcanic soils, and a lunar highland soil sample measured in the wavelength range from 7 to 22 μm as a function of particle size. For each sample we measured the spectra of four particle size separates ranging from <25 to 250 μm. The device we used is built at DLR (Berlin) and is coupled to a Fourier-transform infrared spectrometer Bruker IFS 88 purged with dry air and equipped with a nitrogen-cooled MCT detector. All spectra were acquired with a spectral resolution of 4 cm -1. We are currently working on upgrading our emissivity facility. A new spectrometer (Bruker VERTEX 80 V) and new detectors will allow us to measure the emissivity of samples in the wavelength range from 1 to 50 μm in a vacuum environment. This will be

  7. Diffuse Galactic Emission from Spinning Dust Grains

    OpenAIRE

    Draine, B. T.; Lazarian, A.

    1997-01-01

    Spinning interstellar dust grains produce detectable rotational emission in the 10-100 GHz frequency range. We calculate the emission spectrum, and show that this emission can account for the ``anomalous'' Galactic background component which correlates with 100um thermal emission from dust. Implications for cosmic background studies are discussed.

  8. 40 CFR 89.119 - Emission tests.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Emission tests. 89.119 Section 89.119... EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Emission Standards and Certification Provisions § 89.119 Emission tests. (a) Manufacturer testing. (1) Upon completion of service...

  9. 47 CFR 24.133 - Emission limits.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Emission limits. 24.133 Section 24.133... SERVICES Narrowband PCS § 24.133 Emission limits. (a) The power of any emission shall be attenuated below... the lesser attenuation. (b) The measurements of emission power can be expressed in peak or...

  10. 40 CFR 63.112 - Emission standard.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Emission standard. 63.112 Section 63...) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES National Emission Standards... Process Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.112 Emission standard. (a)...

  11. Cooperative spontaneous emission in nonuniform media

    OpenAIRE

    Rudziński, Adam

    2010-01-01

    The subject of this paper is modification of cooperative spontaneous emission by a nonuniform medium, with nonuniform distributions of electromagnetic field. A brief analyzis is presented and it is postulated, that if spontaneous emission from an atom is strongly suppressed, cooperative emission with another atom may be a preferred emission channel and counteract the suppression.

  12. 40 CFR 63.802 - Emission limits.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Emission limits. 63.802 Section 63.802... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED) National Emission Standards for Wood Furniture Manufacturing Operations § 63.802 Emission limits. (a) Each owner or...

  13. Thermal Radio Emission as Incoherent Induced Radiation

    OpenAIRE

    Prigara, Fedor V.

    2001-01-01

    The synchrotron interpretation of radio emission from various astrophysical objects encounters the essential difficulties . These difficulties may be overcome in a new theory of thermal radio emission of non-uniform gas which is based on a stimulated character of thermal radio emission following from the relations between Einstein?s coefficients for spontaneous and induced emission of radiation .

  14. 40 CFR 61.123 - Emission testing.

    Science.gov (United States)

    2010-07-01

    ..., at its option, observe the test. (c) An emission test shall be conducted at each operational calciner or nodulizing kiln. If emissions from a calciner or nodulizing kiln are discharged through more than... calciner or kiln shall be the sum of the emission rates from each of the stacks. (d) Each emission...

  15. Isoprene emission from Indian trees

    Science.gov (United States)

    Varshney, C. K.; Singh, Abhai Pratap

    2003-12-01

    Isoprene is the most dominant non-methane volatile organic compound (NMVOC) emitted by plants. NMVOCs play an important role in regulating the composition of atmospheric trace gases including global concentration of tropospheric ozone. Our present knowledge about NMVOCs emission is mainly from studies on temperate tree species. So far information on biogenic NMVOCs emission from tropical tree species is limited. In this study, isoprene emission rates from 40 tropical Indian tree species belonging to 33 genera and 17 families were measured for the first time using a dynamic flow through enclosure chamber technique. The isoprene emission rate from plants (30°C and PAR 1000 μmolm-2s-1) ranged from undetectable to 81.5 μg g-1 h-1 and values were found to be comparable with other studies on tropical tree species. Tree species screened for isoprene emission in the present study may be grouped into the four categories, proposed by [2001], namely, 18 species were negligible or BDL isoprene emitting (Citrus limon Linn., Citrus reticulata Linn., Citrus sinensis Linn., Grevillea robusta A. Cunn., and Morus alba Linn., which were earlier reported as BDL or non isoprene emitters in US [, 1998; , 2001] were found to be appreciably high isoprene emitters (0.61-21.60 μg g-1 h-1) in the present study.

  16. Part III: Total Greenhouse Gas Emissions

    OpenAIRE

    OLIVIER Jos; Janssens-Maenhout, Greet

    2014-01-01

    CO2 emissions from fuel combustion represent the majority of anthropogenic GHG emissions. However, comprehensive analysis of emission trends considers other sources of CO2 as well as other gases, knowing that data on gases and sources other than CO2 from fuel combustion are much more uncertain. Country- specific estimates of CO2 from biomass burning and F-gas emissions are particularly difficult to ascertain. To complement work regarding the emissions of CO2 from fuel combustion, the IEA elec...

  17. Some properties of emission coordinates

    CERN Document Server

    Pozo, J M

    2006-01-01

    4 emitters broadcasting an increasing electromagnetic signal generate a system of relativistic coordinates for the space-time, called emission coordinates. Their physical realization requires an apparatus similar to the one of the Global Navigation Satellite Systems (GNSS). Several relativistic corrections are utilized for the current precisions, but the GNSS are conceived as classical (Newtonian) systems, which has deep implications in the way of operating them. The study of emission coordinates is an essential step in order to develop a fully relativistic theory of positioning systems. This talk presents some properties of emission coordinates. In particular, we characterize how any observer sees a configuration of satellites giving a degenerated system and show that the trajectories of the satellites select a unique privileged observer at each point and, for any observer, a set of 3 orthogonal spatial axes.

  18. High mobility emissive organic semiconductor

    Science.gov (United States)

    Liu, Jie; Zhang, Hantang; Dong, Huanli; Meng, Lingqiang; Jiang, Longfeng; Jiang, Lang; Wang, Ying; Yu, Junsheng; Sun, Yanming; Hu, Wenping; Heeger, Alan J.

    2015-12-01

    The integration of high charge carrier mobility and high luminescence in an organic semiconductor is challenging. However, there is need of such materials for organic light-emitting transistors and organic electrically pumped lasers. Here we show a novel organic semiconductor, 2,6-diphenylanthracene (DPA), which exhibits not only high emission with single crystal absolute florescence quantum yield of 41.2% but also high charge carrier mobility with single crystal mobility of 34 cm2 V-1 s-1. Organic light-emitting diodes (OLEDs) based on DPA give pure blue emission with brightness up to 6,627 cd m-2 and turn-on voltage of 2.8 V. 2,6-Diphenylanthracene OLED arrays are successfully driven by DPA field-effect transistor arrays, demonstrating that DPA is a high mobility emissive organic semiconductor with potential in organic optoelectronics.

  19. Enteric Methane Emission from Pigs

    DEFF Research Database (Denmark)

    Jørgensen, Henry; Theil, Peter Kappel; Knudsen, Knud Erik Bach

    2011-01-01

    per kg meat produced is increased (Fernández et al. 1983; Lekule et al. 1990). The present chapter will summarise our current knowledge concerning dietary and enteric fermentation that may influence the methane (CH4) emission in pigs. Enteric fermentation is the digestive process by which...... of the studies were specifically designed to investigate dietary or enteric pig factors that may influence the CH4 emission. The data used in the chapter is based on Danish pigs with reference to other European studies. In a global context Denmark’s 12 million pigs (FAOSTAT, 2009) contribute with 1.......3 % of the worlds pig population. The main number of pigs is in Asia (59.6 %) where the main pig population stay in China (47.8 % of the worlds pig population). The objective of the chapter is therefore: To obtain a general overview of the pigs’ contribution to methane emission. Where is the pigs’ enteric gas...

  20. New Double Soft Emission Theorems

    CERN Document Server

    Cachazo, Freddy; Yuan, Ellis Ye

    2015-01-01

    We study the behavior of the tree-level S-matrix of a variety of theories as two particles become soft. By analogy with the recently found subleading soft theorems for gravitons and gluons, we explore subleading terms in double soft emissions. We first consider double soft scalar emissions and find subleading terms that are controlled by the angular momentum operator acting on hard particles. The order of the subleading theorems depends on the presence or not of color structures. Next we obtain a compact formula for the leading term in a double soft photon emission. The theories studied are a special Galileon, DBI, Einstein-Maxwell-Scalar, NLSM and Yang-Mills-Scalar. We use the recently found CHY representation of these theories in order to give a simple proof of the leading order part of all these theorems

  1. Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory - Calendar Year 1998 Emissions Report

    Energy Technology Data Exchange (ETDEWEB)

    S. K. Zohner

    1999-10-01

    This report presents the 1998 calendar year update of the Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory (INEEL). The INEEL Air Emission Inventory documents sources and emissions of nonradionuclide pollutants from operations at the INEEL. The report describes the emission inventory process and all of the sources at the INEEL, and provides nonradiological emissions estimates for stationary sources.

  2. Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory - Calendar Year 1999 Emission Report

    Energy Technology Data Exchange (ETDEWEB)

    Zohner, S.K.

    2000-05-30

    This report presents the 1999 calendar year update of the Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory (INEEL). The INEEL Air Emission Inventory documents sources and emissions of nonradionuclide pollutants from operations at the INEEL. The report describes the emission inventory process and all of the sources at the INEEL, and provides nonradionuclide emissions estimates for stationary sources.

  3. Transportable Emissions Testing Laboratory for Alternative Vehicles Emissions Testing

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Nigel

    2012-01-31

    The overall objective of this project was to perform research to quantify and improve the energy efficiency and the exhaust emissions reduction from advanced technology vehicles using clean, renewable and alternative fuels. Advanced vehicle and alternative fuel fleets were to be identified, and selected vehicles characterized for emissions and efficiency. Target vehicles were to include transit buses, school buses, vocational trucks, delivery trucks, and tractor-trailers. Gaseous species measured were to include carbon monoxide, carbon dioxide, oxides of nitrogen, hydrocarbons, and particulate matter. An objective was to characterize particulate matter more deeply than by mass. Accurate characterization of efficiency and emissions was to be accomplished using a state-of-the-art portable emissions measurement system and an accompanying chassis dynamometer available at West Virginia University. These two units, combined, are termed the Transportable Laboratory. An objective was to load the vehicles in a real-world fashion, using coast down data to establish rolling resistance and wind drag, and to apply the coast down data to the dynamometer control. Test schedules created from actual vehicle operation were to be employed, and a specific objective of the research was to assess the effect of choosing a test schedule which the subject vehicle either cannot follow or can substantially outperform. In addition the vehicle loading objective was to be met better with an improved flywheel system.

  4. NMF on positron emission tomography

    DEFF Research Database (Denmark)

    Bödvarsson, Bjarni; Hansen, Lars Kai; Svarer, Claus;

    2007-01-01

    In positron emission tomography, kinetic modelling of brain tracer uptake, metabolism or binding requires knowledge of the cerebral input function. Traditionally, this is achieved with arterial blood sampling in the arm or as shown in (Liptrot, M, et al., 2004) by non-invasive K-means clustering....... We propose another method to estimate time-activity curves (TAC) extracted directly from dynamic positron emission tomography (PET) scans by non-negative matrix factorization (NMF). Since the scaling of the basis curves is lost in the NMF the estimated TAC is scaled by a vector alpha which...

  5. Ordering multiple soft gluon emissions

    CERN Document Server

    Ángeles-Martínez, René; Seymour, Michael H

    2016-01-01

    We present an expression for the QCD amplitude for a general hard scattering process with any number of soft gluon emissions, to one-loop accuracy. The amplitude is written in two different but equivalent ways: as a product of operators ordered in dipole transverse momentum and as a product of loop-expanded currents. We hope that these results will help in the development of an all-orders algorithm for multiple emissions that includes the full colour structure and both the real and imaginary contributions to the amplitude.

  6. Sonification of acoustic emission data

    Science.gov (United States)

    Raith, Manuel; Große, Christian

    2014-05-01

    While loading different specimens, acoustic emissions appear due to micro crack formation or friction of already existing crack edges. These acoustic emissions can be recorded using suitable ultrasonic transducers and transient recorders. The analysis of acoustic emissions can be used to investigate the mechanical behavior of different specimens under load. Our working group has undertaken several experiments, monitored with acoustic emission techniques. Different materials such as natural stone, concrete, wood, steel, carbon composites and bone were investigated. Also the experimental setup has been varied. Fire-spalling experiments on ultrahigh performance concrete and pullout experiments on bonded anchors have been carried out. Furthermore uniaxial compression tests on natural stone and animal bone had been conducted. The analysis tools include not only the counting of events but the analysis of full waveforms. Powerful localization algorithms and automatic onset picking techniques (based on Akaikes Information Criterion) were established to handle the huge amount of data. Up to several thousand events were recorded during experiments of a few minutes. More sophisticated techniques like moment tensor inversion have been established on this relatively small scale as well. Problems are related to the amount of data but also to signal-to-noise quality, boundary conditions (reflections) sensor characteristics and unknown and changing Greens functions of the media. Some of the acoustic emissions recorded during these experiments had been transferred into audio range. The transformation into the audio range was done using Matlab. It is the aim of the sonification to establish a tool that is on one hand able to help controlling the experiment in-situ and probably adjust the load parameters according to the number and intensity of the acoustic emissions. On the other hand sonification can help to improve the understanding of acoustic emission techniques for training

  7. Particles Emission from Gasoline Vehicles

    Institute of Scientific and Technical Information of China (English)

    WANG Jun-fang; GE Yun-shan; TAN Jian-wei; HE Chao; YOU Ke-wei; YOU Qiu-wen

    2009-01-01

    Number concentration and size distribution from gasoline cars are investigated at transient modes on the chassis dynamometers,which are measured using electrical low pressure impactor (ELPI) for the ECE15 and EUDC cycles.Results indicate that,during cold start,particle number emission is higher than that under hot start.It is found that the number of particles increases with the vehicle speeds.Furthermore,particles with diameter smaller than 200 nm constitute the predominant part of total emission in the entire cycle.In addition,the tentative information about composition of emitted particles is also discussed.

  8. NEC-2020 emission reduction scenarios

    DEFF Research Database (Denmark)

    Slentø, Erik; Nielsen, Ole-Kenneth; Hoffmann, Leif;

    The upcoming NEC-2020 EU directive sets up emission ceilings for NOX, SO2, NH3, NMVOC and PM in order to meet the environmental exposure targets of the Thematic Strategy. This report contains an assessment of intermediary emission reduction scenarios for Denmark, computed by the GAINS model 2007......, which serves as the basis for the pending negotiations in EU. The assessment is brought up to date by including a brief evaluation of the new reduction scenarios published in 2008, founding the European Commission NEC-2020 directive proposal....

  9. Particle emissions from biomass combustion

    Science.gov (United States)

    Chabadová, Jana; Papučík, Štefan; Nosek, Radovan

    2014-08-01

    The paper presents an analysis of the impact of fuel feed to power and emissions parameters of the automatic domestic boiler for combustion of wood pellets. For the analysis has been proposed an experimental methodology of boiler measuring. The investigated boiler is designed for operation in domestic heating system. It has heat power equal to 18 kW. Concentrations of flue gas species were registered at the exit the boiler and based on the measured parameters was carried out evaluation of the impact of the fuel feed to heat power and production of emissions.

  10. VOC emissions from beech, birch, and oak

    Science.gov (United States)

    Wildt, J.; Folkers, A.; Koch, N.; Kleist, E.

    2003-04-01

    VOC emissions from beech (Fagus sylvatica), birch (Betula pendula), and oak (Quercus robur) were studied in continuously stirred tank reactors. Oak emitted nearly exclusively isoprene. The dependence of these isoprene emissions on temperature and photosynthetic radiation (PAR) could quite well be described with existing algorithms and the emission factors were fairly constant. Beech and birch emitted mainly short chained oxygenated VOC and monoterpenes. Temperature and PAR dependence of monoterpene emissions were superimposed by a slow frequency modulation. Hence, descriptions of these emissions with existing algorithms were not successful. Moreover, in some cases the emission pattern switched drastically. For birch it was observed that the plant switched from a sesquiterpene emitter to a monoterpene emitter. emission pattern plants. Emissions of ethanol, acetaldehyde, and methanol were not affected by PAR. Here, the emission factors are determined by other factors not included in existing algorithms.

  11. Emission Trading under the Kyoto Protocol

    Energy Technology Data Exchange (ETDEWEB)

    Holtsmark, Bjart; Hagem, Cathrine

    1998-12-01

    This report discusses the potential gains from emission trading and raises some crucial questions. It shows that the total costs of the Kyoto Protocol could be reduced by about 95% through emission trading. Emission trading is an option also in the domestic arenas. The governments of the Annex B countries may allocate emission quotas to local enterprises as emission permits. Thus new markets for greenhouse gas emission quotas may emerge, domestically and internationally. It is emphasized that emission trading at the national and international levels must be discussed separately. The Nordic governments, for example, will find several good reasons for supporting emission trading at the international level if not necessarily domestically. The Nordic countries have already implemented domestic taxes on CO{sub 2} emissions and this tax policy could be sustained while these governments support and take part in emission trading at the international level.The report also considers a possible side effect of emission trading: free emission trading among Annex B countries could reduce the total abatement compared to a non-tradable policy as a consequence of the fact that some of the countries that are in transition to a market economy may be given emission limitations above their business-as-usual emissions. 40 refs., 7 figs., 4 tabs.

  12. Livestock and greenhouse gas emissions

    DEFF Research Database (Denmark)

    Herrero, M; Gerber, P; Vellinga, T;

    2011-01-01

    Estimates of global greenhouse gases (GHG) emissions attributable to livestock range from 8 to 51%. This variability creates confusion among policy makers and the public as it suggests that there is a lack of consensus among scientists with regard to the contribution of livestock to global GHG em...

  13. Radio emission in Mercury magnetosphere

    CERN Document Server

    Varela, J; Brun, A S; Pantellini, F; Zarka, P

    2016-01-01

    Context: Active stars possess magnetized wind that has a direct impact on planets that can lead to radio emission. Mercury is a good test case to study the effect of the solar wind and interplanetary magnetic field on radio emission driven in the planet magnetosphere. Such studies could be used as proxies to characterize the magnetic field topology and intensity of exoplanets. Aims: The aim of this study is to quantify the radio emission in the Hermean magnetosphere. Methods: We use the MHD code PLUTO in spherical coordinates with an axisymmetric multipolar expansion for the Hermean magnetic field, to analyze the effect of the interplanetary magnetic field (IMF) orientation and intensity, as well as the hydrodynamic parameters of the solar wind (velocity, density and temperature), on the net power dissipated on the Hermean day and night side. We apply the formalism derived by Zarka [2001, 2007] to infer the radio emission level from the net dissipated power. We perform a set of simulations with different hydr...

  14. INFRARED EMISSIVITY OF CONDUCTING POLYMERS

    Institute of Scientific and Technical Information of China (English)

    WAN Meixiang; LI Suzhen; LI Junchao; DONG Haiou

    1991-01-01

    The infrared emissivity of conducting polymers in 8-20μm and at 50-150℃ in the direction of normal line has been measured as a function of wavelength, conductivity at room temperature,counterion, doping levels, measuring temperature and thickness of sample.

  15. Shell theorem for spontaneous emission

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Mortensen, Jakob Egeberg; Lodahl, Peter;

    2013-01-01

    and therefore is given exactly by the dipole approximation theory. This surprising result is a spontaneous emission counterpart to the shell theorems of classical mechanics and electrostatics and provides insights into the physics of mesoscopic emitters as well as great simplifications in practical calculations....

  16. Fiber optics spectrochemical emission sensors

    Science.gov (United States)

    Griffin, Jeffrey W.; Olsen, Khris B.

    1992-01-01

    A method of in situ monitoring of a body of a fluid stored in a tank or groundwater or vadose zone gases in a well for the presence of selected chemical species uses a probe insertable into the well or tank via a cable and having electrical apparatus for exciting selected chemical species in the body of fluid. The probe can have a pair of electrodes for initiating a spark or a plasma cell for maintaining a plasma to excite the selected chemical species. The probe also has optical apparatus for receiving optical emissions emitted by the excited species and optically transmitting the emissions via the cable to an analysis location outside the well. The analysis includes detecting a selected wavelength in the emissions indicative of the presence of the selected chemical species. A plurality of probes can be suspended at an end of a respective cable, with the transmitting and analyzing steps for each probe being synchronized sequentially for one set of support equipment and instrumentation to monitor at multiple test points. The optical apparatus is arranged about the light guide axis so that the selected chemical species are excited the fluid in alignment with the light guide axis and optical emissions are received from the excited chemical species along such axis.

  17. Recharging Emission-Free Cars

    Institute of Scientific and Technical Information of China (English)

    CORRIE; DOSH

    2008-01-01

    New York dealership begins sales of China-made electric vehicles In the 2006 documentary Who Killed the Electric Car?, Director Chris Paine showed how auto manufacturers, the oil industry, government officials and consumers suppressed the development of allelectric, emission-free vehicles. Now, with

  18. Fiber optics spectrochemical emission sensors

    Science.gov (United States)

    Griffin, J.W.; Olsen, K.B.

    1992-02-04

    A method is described of in situ monitoring of a body of a fluid stored in a tank or groundwater or vadose zone gases in a well for the presence of selected chemical species. The method uses a probe insertable into the well or tank via a cable and having an electrical apparatus for exciting selected chemical species in the body of fluid. The probe can have a pair of electrodes for initiating a spark or a plasma cell for maintaining a plasma to excite the selected chemical species. The probe also has an optical apparatus for receiving optical emissions emitted by the excited species and optically transmitting the emissions via the cable to an analysis location outside the well. The analysis includes detecting a selected wavelength in the emissions indicative of the presence of the selected chemical species. A plurality of probes can be suspended at an end of a respective cable, with the transmitting and analyzing steps for each probe being synchronized sequentially for one set of support equipment and instrumentation to monitor at multiple test points. The optical apparatus is arranged about the light guide axis so that the selected chemical species are excited in the fluid in alignment with the light guide axis. Optical emissions are received from the excited chemical species along such axis. 18 figs.

  19. Emissions Trading: Trends and Prospects

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    This paper provides the latest developments of announced, proposed and existing greenhouse gas emissions trading schemes (ETS) around the world since 2006. It also examines different potential design options for ETS (e.g. coverage, allocation mode, provision for offsets), and how these options are treated in the existing, announced or proposed schemes.

  20. Tradeable Emission Permits in Oligopoly

    NARCIS (Netherlands)

    Fershtman, C.; de Zeeuw, A.J.

    1996-01-01

    The paper considers an oligopolistic industry in which pollution is a by-product of production. Firms are assumed to have emission permits that restrict the amount that they pollute. These permits are assumed to be tradeable and the paper discusses a structure in which the same set of firms operates

  1. Primary particles in ship emissions

    Science.gov (United States)

    Fridell, Erik; Steen, Erica; Peterson, Kjell

    There is not much data available regarding particle emissions from ships. In this study the size distributions of particles in ship exhaust from three different ships in normal operational conditions were studied using a cascade impactor. The ships were equipped with slow- or medium-speed main engines and medium-speed auxiliary engines. The fuel was residual oil except for the auxiliary engines on one ship which used marine diesel. Large emissions and a dependence of the sulfur content in the fuel were observed. High amounts of relatively large particles (around 8 μm) were observed. These are attributed to re-entrained soot particles from walls in the engine systems. A strong variation between different ships was observed for the particle-size distribution and for the dependence on engine load. The particle emissions were found to be reduced to about half, over the whole size range, by an SCR system. The total particle emission, measured after dilution, varied between 0.3 and 3 g kW h -1 depending on load, fuel and engine.

  2. Evaluation and improvement of road vehicle pollutant emission factors based on instantaneous emissions data processing

    OpenAIRE

    Franco García, Vicente

    2014-01-01

    Introduction Current instrumentation makes it possible to measure vehicle emissions with high temporal resolution. But the increased resolution of emissions signals does not equate with increased accuracy. A prerequisite for the derivation of accurate emission factors from instantaneous vehicle emissions data is a fine allocation of measured mass emissions to recorded engine or vehicle states. This poses a technical challenge, because vehicle emission test facilities are not designed to su...

  3. Variable Emissivity Through MEMS Technology

    Science.gov (United States)

    Darrin, Ann Garrison; Osiander, Robert; Champion, John; Swanson, Ted; Douglas, Donya; Grob, Lisa M.; Powers, Edward I. (Technical Monitor)

    2000-01-01

    This paper discusses a new technology for variable emissivity (vari-e) radiator surfaces, which has significant advantages over traditional radiators and promises an alternative design technique for future spacecraft thermal control systems. All spacecraft rely on radiative surfaces to dissipate waste heat. These radiators have special coatings, typically with a low solar absorptivity and a high infrared-red emissivity, that are intended to optimize performance under the expected heat load and thermal sink environment. The dynamics of the heat loads and thermal environment make it a challenge to properly size the radiator and often require some means of regulating the heat rejection rate of the radiators in order to achieve proper thermal balance. Specialized thermal control coatings, which can passively or actively adjust their emissivity offer an attractive solution to these design challenges. Such systems would allow intelligent control of the rate of heat loss from a radiator in response to heat load and thermal environmental variations. Intelligent thermal control through variable emissivity systems is well suited for nano and pico spacecraft applications where large thermal fluctuations are expected due to the small thermal mass and limited electric resources. Presently there are three different types of vari-e technologies under development: Micro ElectroMechanical Systems (MEMS) louvers, Electrochromic devices, and Electrophoretic devices. This paper will describe several prototypes of micromachined (MEMS) louvers and experimental results for the emissivity variations measured on theses prototypes. It will further discuss possible actuation mechanisms and space reliability aspects for different designs. Finally, for comparison parametric evaluations of the thermal performances of the new vari-e technology and standard thermal control systems are presented in this paper.

  4. AIRFORCE. Aircraft emissions and radiative forcing from emissions

    Energy Technology Data Exchange (ETDEWEB)

    Meijer, E.W.; Kelder, H.; Velthoven, P.F.J. van; Wauben, W.M.F. [Royal Netherlands Meteorological Inst., De Bilt (Netherlands); Beck, J.P.; Velders, G.J.M. [National Inst. of Public Health and the Environment, Bilthoven (Netherlands); Lelieveld, J.; Scheeren, B.A. [Institute of Marine and Atmospheric Research Utrecht (Netherlands)

    1997-12-31

    The Dutch AIRFORCE project focuses on the effects of subsonic aircraft emissions on the chemical composition of the atmosphere and subsequent radiative forcing. It includes measurements in the tropopause region and the modelling of exhaust plumes and large-scale effects. An aircraft exhaust plume model has been developed to study plume processes. The results of the plume model are used in the global transport chemistry model CTMK to determine large-scale effects of plume processes. Due to the efficient conversion of NO{sub x} into HNO{sub 3} inside aircraft exhaust plumes, a decrease of about 25% of the O{sub 3} perturbation was found in the NAFC at 200 hPa in July. Measurements of hydrocarbons revealed a dominant role of the anthropogenic continental emissions of light hydrocarbons in the tropopause region. (author) 20 refs.

  5. Isoprene emission from wetland sedges

    Directory of Open Access Journals (Sweden)

    A. Ekberg

    2009-04-01

    Full Text Available High latitude wetlands play an important role for the surface-atmosphere exchange of carbon dioxide (CO2 and methane (CH4, but fluxes of biogenic volatile organic compounds (BVOC in these ecosystems have to date not been extensively studied. This is despite BVOC representing a measurable proportion of the total gaseous C fluxes at northern locations and in the face of the high temperature sensitivity of these systems that requires a much improved process understanding to interpret and project possible changes in response to climate warming. We measured emission of isoprene and photosynthetic gas exchange over two growing seasons (2005–2006 in a subarctic wetland in northern Sweden with the objective to identify the physiological and environmental controls of these fluxes on the leaf scale. The sedge species Eriophorum angustifolium and Carex rostrata were both emitters of isoprene. Springtime emissions were first detected after an accumulated diurnal mean temperature above 0°C of about 100 degree days. Maximum measured growing season standardized (basal emission rates (20°C, 1000 μmol m−2 s−1 were 1075 (2005 and 1118 (2006 μg C m−2 (leaf area h−1 in E. angustifolium, and 489 (2005 and 396 (2006 μg C m−2 h−1 in C. rostrata. Over the growing season, basal isoprene emission varied in response to the temperature history of the last 48 h. Seasonal basal isoprene emission rates decreased with leaf nitrogen (N, which may be explained by the typical growth and resource allocation pattern of clonal sedges as the leaves age. The observations were used to model emissions over the growing season, accounting for effects of temperature history, links to leaf assimilation rate and the light and temperature dependencies of the cold-adapted sedges.

  6. Methane emissions from MBT landfills

    Energy Technology Data Exchange (ETDEWEB)

    Heyer, K.-U., E-mail: heyer@ifas-hamburg.de; Hupe, K.; Stegmann, R.

    2013-09-15

    Highlights: • Compilation of methane generation potential of mechanical biological treated (MBT) municipal solid waste. • Impacts and kinetics of landfill gas production of MBT landfills, approach with differentiated half-lives. • Methane oxidation in the waste itself and in soil covers. • Estimation of methane emissions from MBT landfills in Germany. - Abstract: Within the scope of an investigation for the German Federal Environment Agency (“Umweltbundesamt”), the basics for the estimation of the methane emissions from the landfilling of mechanically and biologically treated waste (MBT) were developed. For this purpose, topical research including monitoring results regarding the gas balance at MBT landfills was evaluated. For waste treated to the required German standards, a methane formation potential of approximately 18–24 m{sup 3} CH{sub 4}/t of total dry solids may be expected. Monitoring results from MBT landfills show that a three-phase model with differentiated half-lives describes the degradation kinetics in the best way. This is due to the fact that during the first years of disposal, the anaerobic degradation processes still proceed relatively intensively. In addition in the long term (decades), a residual gas production at a low level is still to be expected. Most of the soils used in recultivation layer systems at German landfills show a relatively high methane oxidation capacity up to 5 l CH{sub 4}/(m{sup 2} h). However, measurements at MBT disposal sites indicate that the majority of the landfill gas (in particular at non-covered areas), leaves the landfill body via preferred gas emission zones (hot spots) without significant methane oxidation. Therefore, rather low methane oxidation factors are recommended for open and temporarily covered MBT landfills. Higher methane oxidation rates can be achieved when the soil/recultivation layer is adequately designed and operated. Based on the elaborated default values, the First Order Decay (FOD

  7. Air Emissions Sources, Charts and Maps

    Data.gov (United States)

    U.S. Environmental Protection Agency — Air Emissions provides (1) interactive charts supporting national, state, or county charts, (2) county maps of criteria air pollutant emissions for a state, and (3)...

  8. AP-42 Emissions Factors (WebFIRE)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Emissions factors have long been the fundamental tool in developing national, regional, state, and local emissions inventories for air quality management decisions...

  9. Neural networks for NOx-emission

    International Nuclear Information System (INIS)

    The government wants to restrict nitrogen oxide emissions. However, continuous measurement of these emissions is expensive and maintenance-sensitive. A prediction model based on the use of neural networks might be a reliable and efficient alternative

  10. Single Photon Emission Computed Tomography (SPECT)

    Science.gov (United States)

    ... Tools & Resources Stroke More Single Photon Emission Computed Tomography (SPECT) Updated:Sep 11,2015 What is a ... Heart Attack Myocardial Perfusion Imaging (MPI) Positron Emission Tomography (PET) Radionuclide Ventriculography, Radionuclide Angiography, MUGA Scan Heart ...

  11. Natural wetland emissions of methylated trace elements

    NARCIS (Netherlands)

    Vriens, B.; Lenz, M.; Charlet, L.; Berg, M.; Winkel, L.H.E.

    2014-01-01

    Natural wetlands are well known for their significant methane emissions. However, trace element emissions via biomethylation and subsequent volatilization from pristine wetlands are virtually unstudied, even though wetlands constitute large reservoirs for trace elements. Here we show that the averag

  12. Controlling nanowire emission profile using conical taper

    DEFF Research Database (Denmark)

    Gregersen, Niels; Nielsen, Torben Roland; Mørk, Jesper;

    2008-01-01

    The influence of a conical taper on nanowire light emission is studied. For nanowires with divergent output beams, the introduction of tapers improves the emission profile and increase the collection efficiency of the detection optics....

  13. Composite Fillers and their Influence on Emissivity

    Science.gov (United States)

    Mauer, Milan; Kalenda, Petr; Honner, Milan; Vacíková, Petra

    The research work presented in this paper shows influence of filler composition in inorganic composite on its emissivity. Development of system which will provide a very high emissivity (0.90 - 0.99) within a short wavelength range is the intention of our project. Active ingredients (Chromium Oxide, Iron powder, Kaolin, Silicon Carbide, Boron Carbide, Boron Nitride and Aluminum Nitride) were built in matrix of the composite. Furrier Transform Infra- Red (FTIR) Spectroscopy method was applied for measurement of spectral emissivity. Block hot plate was used for heating samples in relative emissivity measurement and laser beam in absolute emissivity measurement. These tests demonstrated that filler composition is able to influence emissive properties in range of short IR wavelength (1.5-4.0 μm) within 0.7 - 1.5 times (against the reference). Also influence of content of active ingredient in ceramic matrix on emissivity was measured. Content of active ingredients had no significant effect on emissivity.

  14. Danish emission inventories for stationary combustion plants

    DEFF Research Database (Denmark)

    Nielsen, Malene; Nielsen, Ole-Kenneth; Plejdrup, Marlene Schmidt;

    and the increased emission from lean-burn gas engines. The dioxin emission decreased since 1990 due to flue gas cleaning on waste incineration plants. However in recent years the emission has increased as a result of the increased combustion of wood in residential plants....... to structural changes in the Danish electricity market. The N2O emission was higher in 2007 than in 1990 but the fluctuations in the time-series are significant. A considerable decrease of the SO2, NOx and heavy metal emissions is mainly a result of decreased emissions from large power plants and waste...... incineration plants. The combustion of wood in residential plants has increased considerably in recent years resulting in increased emission of PAH, particulate matter and CO. The emission of NMVOC has increased since 1990 as a result of both the increased combustion of wood in residential plants...

  15. Danish emission inventories for stationary combustion plants

    DEFF Research Database (Denmark)

    Nielsen, Malene; Nielsen, Ole-Kenneth; Plejdrup, Marlene Schmidt;

    and the increased emission from lean-burn gas engines. The dioxin emission decreased since 1990 due to flue gas cleaning on waste incineration plants. However in recent years the emission has increased as a result of the increased combustion of wood in residential plants....... to structural changes in the Danish electricity market. The N2O emission was higher in 2008 than in 1990 but the fluctuations in the timeseries are significant. A considerable decrease of the SO2, NOx and heavy metal emissions is mainly a result of decreased emissions from large power plants and waste...... incineration plants. The combustion of wood in residential plants has increased considerably in recent years resulting in increased emission of PAH, particulate matter and CO. The emission of NMVOC has increased since 1990 as a result of both the increased combustion of wood in residential plants...

  16. Compliance and Emissions Data Reporting Interface (CEDRI)

    Data.gov (United States)

    U.S. Environmental Protection Agency — EPA regulations codified in 40 CFR Part 60 and 63 require affected sources to perform emissions source tests, conduct continuous emissions monitoring, and submit...

  17. Pollutants emission in power sector

    International Nuclear Information System (INIS)

    Fossil fuels, including coal, natural gas, petroleum, shale oil and bitumen, are the primary source of heat and electrical energy production and are responsible for emitting a large number and amount of pollutants into the atmosphere via exhaust gases from industry, power stations, residential heating systems and vehicles. During the combustion process, different pollutants such as CO2, SOX (including SO2 and SO3), NOX (including NO2, NO and N2O), fly ash, VOCs and mercury are emitted. These emissions cause big environmental and human health hazard. CO2, N2O, some VOCs, CH4 contribute to the global greenhouse effect, adding a new dimension to the environmental degradation resulting from the burning of fossil fuels. These problems regarding emissions inventory, their impact on the environment and human health, air pollution control technologies and costs, periods of fossil fuels depletion, role of renewable and nuclear energy in the further civilization development are briefly discussed. (author)

  18. Climate, energy and emissions trading

    International Nuclear Information System (INIS)

    The authors question the 4 main concerns that have arisen since the implementation of emission trade markets 3 years ago. First, the allowance policy was not accurate enough and has led to a surplus offer of CO2 allowances. Secondly, the impact on electricity prices of carbon emission costs was all the higher as it happened at the moment of the deregulation of electricity markets. Thirdly, the CO2 allowances whose price will near 14 euros a ton for the 2008-2012 period are accused of hindering the competitiveness of the European industrial sector. Fourth, the present allowance system that gives to new comers free CO2 allowances is not very conducive to the adoption by these new comers of technologies that are less CO2 emitting. Some ways of improvement are given. (A.C.)

  19. Integrated Emissivity And Temperature Measurement

    Science.gov (United States)

    Poulsen, Peter

    2005-11-08

    A multi-channel spectrometer and a light source are used to measure both the emitted and the reflected light from a surface which is at an elevated temperature relative to its environment. In a first method, the temperature of the surface and emissivity in each wavelength is calculated from a knowledge of the spectrum and the measurement of the incident and reflected light. In the second method, the reflected light is measured from a reference surface having a known reflectivity and the same geometry as the surface of interest and the emitted and the reflected light are measured for the surface of interest. These measurements permit the computation of the emissivity in each channel of the spectrometer and the temperature of the surface of interest.

  20. Evaluation of Emissions Bio diesel

    International Nuclear Information System (INIS)

    The generation of energy from vegetal products is one of the possibilities to our reach in order to reduce the atmospheric pollution. Particularly, the use of bio diesel in internal combustion engines can be one of the best options. The finest particles emitted by the combustion engines are easily breathable and on them different substances can be absorbed presumably toxic, between which it is possible to emphasize the polycyclic aromatic hydrocarbons (PAHs), by its demonstrated carcinogen character. In this work, it is studied on the one hand, the characteristics that can present the aerosol of emission in a diesel engine with a maximum power of 97 kW, working without load to 600 rpm, using as combustible mixtures of bio diesel and diesel in different proportions. On the other hand, the evolution that takes place in the concentration of PAHs in emission particles, according to the percentage of bio diesel used in the combustible mixture. (Author) 9 refs

  1. Spontaneous Emission in Nonlocal Materials

    CERN Document Server

    Ginzburg, Pavel; Nasir, Mazhar E; Olvera, Paulina Segovia; Krasavin, Alexey V; Levitt, James; Hirvonen, Liisa M; Wells, Brian; Suhling, Klaus; Richards, David; Podolskiy, Viktor A; Zayats, Anatoly V

    2016-01-01

    Light-matter interactions can be dramatically modified by the surrounding environment. Here we report on the first experimental observation of molecular spontaneous emission inside a highly nonlocal metamaterial based on a plasmonic nanorod assembly. We show that the emission process is dominated not only by the topology of its local effective medium dispersion, but also by the nonlocal response of the composite, so that metamaterials with different geometric parameters but the same local effective medium properties exhibit different Purcell factors. A record-high enhancement of a decay rate is observed, in agreement with the developed quantitative description of the Purcell effect in a nonlocal medium. An engineered material nonlocality introduces an additional degree of freedom into quantum electrodynamics, enabling new applications in quantum information processing, photo-chemistry, imaging, and sensing.

  2. Evaluation of Emissions Bio diesel

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Maroto, J. J.; Dorronsoro Arenal, J. L.; Rojas Garcia, E.; Perez Pastor, R.; Garcia Alonso, S.

    2007-09-27

    The generation of energy from vegetal products is one of the possibilities to our reach in order to reduce the atmospheric pollution. Particularly, the use of bio diesel in internal combustion engines can be one of the best options. The finest particles emitted by the combustion engines are easily breathable and on them different substances can be absorbed presumably toxic, between which it is possible to emphasize the polycyclic aromatic hydrocarbons (PAHs), by its demonstrated carcinogen character. In this work, it is studied on the one hand, the characteristics that can present the aerosol of emission in a diesel engine with a maximum power of 97 kW, working without load to 600 rpm, using as combustible mixtures of bio diesel and diesel in different proportions. On the other hand, the evolution that takes place in the concentration of PAHs in emission particles, according to the percentage of bio diesel used in the combustible mixture. (Author) 9 refs.

  3. Emission tax revenues in a growing economy

    OpenAIRE

    Pethig, Rüdiger

    1997-01-01

    This paper focuses on how emission tax revenues change relative to GNP, when a fixed environmental standard is implemented by an emission tax and when waste abatement, technical and structural change and capital accumulation is accounted for. One- and two-sector growth models are analyzed allowing for demand substitution and sectoral differences in emission intensities and elasticities of technical substitution. It turns out that the more difficult it is to reduce the emission of pollutants e...

  4. Marine Engines and Nitrogen Oxides Emissions

    OpenAIRE

    Corneliu Moroianu; Gheorghe Samoilescu

    2008-01-01

    Current international policy initiatives by the International Maritime Organization (IMO) to reduce emissions from ship propulsion systems (NOx and SOx, primarily) mark the first efforts to define a framework to address this issue. Oxides of nitrogen (NOx) emissions from ship engines are significant on a global level. NOx emissions participate in the formation of photochemical smog and acid rain. Marine sourced emissions have significant impact on air quality on land. The challenge is to cont...

  5. Silicon Array for Multi-particle Emission

    Institute of Scientific and Technical Information of China (English)

    XU; Xin-xing; LIN; Cheng-jian; SUN; Li-jie; BAO; Peng-fei; YANG; Lei; YANG; Feng; ZHANG; Huan-qiao; LIU; Zu-hua; JIA; Hui-ming; MA; Nan-ru

    2013-01-01

    Remarkable progress in the study of two-proton emission has been made in recent years.One of the next destinations is the realization of high-precision direct measurements of decay-energy and emission-angle correlations inβ-delayed two-proton(β2p)emission.We have studiedβ2p correlated emission of the ground state of 26P at the proton drip line with the direct measurement at the National

  6. Dust Emissivity in the Far-Infrared

    OpenAIRE

    Bianchi, Simone; Davies, Jonathan I.; Alton, Paul B.

    1999-01-01

    We have derived the dust emissivity in the Far-Infrared (FIR) using data available in the literature. We use two wavelength dependences derived from spectra of Galactic FIR emission (Reach et al. 1995). A value for the emissivity, normalised to the extinction efficiency in the V band, has been retrieved from maps of Galactic FIR emission, dust temperature and extinction (Schlegel et al. 1998). Our results are similar to other measurements in the Galaxy but only marginally consistent with the ...

  7. Legislators Urge Carbon Emissions Cuts

    Science.gov (United States)

    Kumar, Mohi

    2007-02-01

    Legislators from the world's largest carbon dioxide (CO2) emitting countries met on 14-15 February in Washington, D.C., to discuss the future of the global climate and strategies to mitigate temperature increases resulting from global warming. The world faces a ``double challenge-how to reduce damaging carbon emissions while still meeting the energy demand that the world's poor need to escape poverty,'' said World Bank President Paul Wolfowitz during a keynote talk.

  8. Trimethylamine emissions in animal husbandry

    Directory of Open Access Journals (Sweden)

    J. Sintermann

    2014-05-01

    Full Text Available Degradation of plant material by animals is an important transformation pathway in the nitrogen (N cycle. During the involved processes, volatile reduced alkaline nitrogen compounds, mainly ammonia (NH3 and aliphatic amines such as trimethylamine (TMA, are formed. Today, animal husbandry is estimated to constitute a main source of aliphatic amines into the atmosphere with TMA being the main emitted compound. Here, we show how the interaction between faeces and urine in animal production systems provides the primary source for agricultural TMA emissions. Excreted urine contains large quantities of urea and TMA-N-oxide, which are transformed into NH3 and TMA, respectively, via enzymatic processes provided by microbes present in faeces. TMA emissions from areas polluted with urine-faeces mixture are on average in the order of 10 to 50 nmol m−2s−1. Released amines promote secondary aerosol particle formation in the agricultural emission plume. The atmospheric lifetime of TMA, which was estimated to be in the order of 30 to 1000 s, is determined by the condensation on aerosol particles.

  9. Trimethylamine emissions in animal husbandry

    Science.gov (United States)

    Sintermann, J.; Schallhart, S.; Kajos, M.; Jocher, M.; Bracher, A.; Münger, A.; Johnson, D.; Neftel, A.; Ruuskanen, T.

    2014-09-01

    Degradation of plant material by animals is an important transformation pathway in the nitrogen (N) cycle. During the involved processes, volatile reduced alkaline nitrogen compounds, mainly ammonia (NH3) and aliphatic amines such as trimethylamine (TMA), are formed. Today, animal husbandry is estimated to constitute a main source of aliphatic amines in the atmosphere with TMA being the main emitted compound. Here, we show how the interaction between faeces and urine in animal production systems provides the primary source for agricultural TMA emissions. Excreted urine contains large quantities of urea and TMA-N-oxide, which are transformed into NH3 and TMA, respectively, via enzymatic processes provided by microbes present in faeces. TMA emissions from areas polluted with urine-faeces mixtures are on average of the order of 10 to 50 nmol m-2s-1. Released amines promote secondary aerosol particle formation in the agricultural emission plume. The atmospheric lifetime of TMA, which was estimated to be of the order of 30 to 1000 s, is determined by the condensation onto aerosol particles.

  10. Gold emissivities for hydrocode applications

    Science.gov (United States)

    Bowen, C.; Wagon, F.; Galmiche, D.; Loiseau, P.; Dattolo, E.; Babonneau, D.

    2004-10-01

    The Radiom model [M. Busquet, Phys Fluids B 5, 4191 (1993)] is designed to provide a radiative-hydrodynamic code with non-local thermodynamic equilibrium (non-LTE) data efficiently by using LTE tables. Comparison with benchmark data [M. Klapisch and A. Bar-Shalom, J. Quant. Spectrosc. Radiat. Transf. 58, 687 (1997)] has shown Radiom to be inaccurate far from LTE and for heavy ions. In particular, the emissivity was found to be strongly underestimated. A recent algorithm, Gondor [C. Bowen and P. Kaiser, J. Quant. Spectrosc. Radiat. Transf. 81, 85 (2003)], was introduced to improve the gold non-LTE ionization and corresponding opacity. It relies on fitting the collisional ionization rate to reproduce benchmark data given by the Averroès superconfiguration code [O. Peyrusse, J. Phys. B 33, 4303 (2000)]. Gondor is extended here to gold emissivity calculations, with two simple modifications of the two-level atom line source function used by Radiom: (a) a larger collisional excitation rate and (b) the addition of a Planckian source term, fitted to spectrally integrated Averroès emissivity data. This approach improves the agreement between experiments and hydrodynamic simulations.

  11. Gold emissivities for hydrocode applications

    International Nuclear Information System (INIS)

    The Radiom model [M. Busquet, Phys Fluids B 5, 4191 (1993)] is designed to provide a radiative-hydrodynamic code with non-local thermodynamic equilibrium (non-LTE) data efficiently by using LTE tables. Comparison with benchmark data [M. Klapisch and A. Bar-Shalom, J. Quant. Spectrosc. Radiat. Transf. 58, 687 (1997)] has shown Radiom to be inaccurate far from LTE and for heavy ions. In particular, the emissivity was found to be strongly underestimated. A recent algorithm, Gondor [C. Bowen and P. Kaiser, J. Quant. Spectrosc. Radiat. Transf. 81, 85 (2003)], was introduced to improve the gold non-LTE ionization and corresponding opacity. It relies on fitting the collisional ionization rate to reproduce benchmark data given by the Averroes superconfiguration code [O. Peyrusse, J. Phys. B 33, 4303 (2000)]. Gondor is extended here to gold emissivity calculations, with two simple modifications of the two-level atom line source function used by Radiom: (a) a larger collisional excitation rate and (b) the addition of a Planckian source term, fitted to spectrally integrated Averroes emissivity data. This approach improves the agreement between experiments and hydrodynamic simulations

  12. Trace element emissions from coal

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-09-15

    Trace elements are emitted during coal combustion. The quantity, in general, depends on the physical and chemical properties of the element itself, the concentration of the element in the coal, the combustion conditions and the type of particulate control device used, and its collection efficiency as a function of particle size. Some trace elements become concentrated in certain particle streams following combustion such as bottom ash, fly ash, and flue gas particulate matter, while others do not. Various classification schemes have been developed to describe this partitioning behaviour. These classification schemes generally distinguish between: Class 1: elements that are approximately equally concentrated in the fly ash and bottom ash, or show little or no fine particle enrichment, examples include Mn, Be, Co and Cr; Class 2: elements that are enriched in the fly ash relative to bottom ash, or show increasing enrichment with decreasing particle size, examples include As, Cd, Pb and Sb; Class 3: elements which are emitted in the gas phase (primarily Hg (not discussed in this review), and in some cases, Se). Control of class 1 trace elements is directly related to control of total particulate matter emissions, while control of the class 2 elements depends on collection of fine particulates. Due to the variability in particulate control device efficiencies, emission rates of these elements can vary substantially. The volatility of class 3 elements means that particulate controls have only a limited impact on the emissions of these elements.

  13. Neutron emission prior to fission

    International Nuclear Information System (INIS)

    In recent years, many groups have measured neutrons and light charged particles in coincidence with fission fragments in heavy ion reactions. In most cases, particles emitted with an energy spectrum and angular distribution characteristic of that of compound nucleus evaporation have been measured in excess of statistical model predictions. They have chosen to investigate this effect in detail by studying neutron emission in the 158Er composite system. The advantage of this system is that it can be produced by a variety of projectile target combinations. They have chosen four combinations which form 158Er with similar critical angular momenta but varying excitation energy. The rationale is to form the same system with different neutron emission times; if the enhanced neutrons are being emitted during the fission process, the different emission time scales might possibly be used to time the fission process. In addition, they impose an additional constraint - that they have a significant fission barrier for most of the partial waves involved in the fission process. The reactions they have selected are 16O + 142Nd (207 MeV beam energy), 24Mg + 134Ba (180 MeV), 32S + 126Te (180 MeV), 50Ti + 108Pd (216 MeV)

  14. Infrared emission from electronically excited biacetyl molecules

    NARCIS (Netherlands)

    Drent, E.; Kommandeur, J.

    1971-01-01

    The infrared emission of electronically excited biacetyl molecules in the gas phase at low pressure was observed. Some experimental details are given, and it is shown that the emission derives from biacetyl molecules in their triplet state. The emission is dependent on the wavelength of excitation.

  15. Statistical modeling of global soil NOx emissions

    Science.gov (United States)

    Yan, Xiaoyuan; Ohara, Toshimasa; Akimoto, Hajime

    2005-09-01

    On the basis of field measurements of NOx emissions from soils, we developed a statistical model to describe the influences of soil organic carbon (SOC) content, soil pH, land-cover type, climate, and nitrogen input on NOx emission. While also considering the effects of soil temperature, soil moisture change-induced pulse emission, and vegetation fire, we simulated NOx emissions from global soils at resolutions of 0.5° and 6 hours. Canopy reduction was included in both data processing and flux simulation. NOx emissions were positively correlated with SOC content and negatively correlated with soil pH. Soils in dry or temperate regions had higher NOx emission potentials than soils in cold or tropical regions. Needleleaf forest and agricultural soils had high NOx emissions. The annual NOx emission from global soils was calculated to be 7.43 Tg N, decreasing to 4.97 Tg N after canopy reduction. Global averages of nitrogen fertilizer-induced emission ratios were 1.16% above soil and 0.70% above canopy. Soil moisture change-induced pulse emission contributed about 4% to global annual NOx emission, and the effect of vegetation fire on soil NOx emission was negligible.

  16. Review Existing and Proposed Emissions Trading Systems

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-07-01

    This paper reviews key design features of mandatory emissions trading systems that had been established or were under consideration in 2010, with a particular focus on implications for the energy sector. Putting a price on greenhouse gas emissions is a cornerstone policy in climate change mitigation. To this end, many countries have implemented or are developing domestic emissions trading systems.

  17. Climate response: Strong warming at high emissions

    Science.gov (United States)

    Frölicher, Thomas L.

    2016-09-01

    The ratio of global temperature change to cumulative emissions is relatively constant up to two trillion tonnes of carbon emissions. Now a new modelling study suggests that the concept of a constant ratio is even applicable to higher cumulative carbon emissions, with important implications for future warming.

  18. Catalytic treatment of diesel engines, NOx emissions

    International Nuclear Information System (INIS)

    Some aspects of the operation of diesel engines are revised together with the pollutant emissions they produce, as well as the available catalytic technologies for the treatment of diesel emissions. Furthermore the performance of a catalyst developed in the environmental catalysis group for NOx reduction using synthetic gas mixtures simulating the emissions from diesel engines is presented

  19. 40 CFR 61.271 - Emission standard.

    Science.gov (United States)

    2010-07-01

    ... device requirements of 40 CFR 60.18. (3) The specifications and requirements listed in paragraphs (c)(1... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Emission standard. 61.271 Section 61...) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Benzene...

  20. 47 CFR 90.210 - Emission masks.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission masks. 90.210 Section 90.210... MOBILE RADIO SERVICES General Technical Standards § 90.210 Emission masks. Except as indicated elsewhere... emission masks outlined in this section. Unless otherwise stated, per paragraphs (d)(4), (e)(4), and (m)...

  1. 47 CFR 90.1323 - Emission limits.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission limits. 90.1323 Section 90.1323... MOBILE RADIO SERVICES Wireless Broadband Services in the 3650-3700 MHz Band § 90.1323 Emission limits. (a) The power of any emission outside a licensee's frequency band(s) of operation shall be...

  2. 47 CFR 22.357 - Emission types.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Emission types. 22.357 Section 22.357... Operational and Technical Requirements Technical Requirements § 22.357 Emission types. Any authorized station in the Public Mobile Services may transmit emissions of any type(s) that comply with the...

  3. 47 CFR 90.669 - Emission limits.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission limits. 90.669 Section 90.669... 896-901/935-940 Mhz Band § 90.669 Emission limits. (a) On any frequency in an MTA licensee's spectrum block that is adjacent to a non-MTA frequency, the power of any emission shall be attenuated below...

  4. CHARACTERIZATION OF EMISSIONS FROM BURNING INCENSE

    Science.gov (United States)

    The primary objective of this study was to improve the characterization of particulate matter emissions from burning incense. Emissions of particulate matter were measured for 23 different types of incense using a cyclone/filter method. Emission rates for PM2.5 (particulate matte...

  5. 40 CFR 92.8 - Emission standards.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Emission standards. 92.8 Section 92.8... Locomotives and Locomotive Engines § 92.8 Emission standards. (a) Exhaust standards. Exhaust emissions from..., shall comply with both the applicable line-haul duty-cycle standards, and the applicable switch...

  6. 40 CFR 52.2309 - Emissions inventories.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Emissions inventories. 52.2309 Section...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Texas § 52.2309 Emissions inventories. (a) The Governor of the State of Texas submitted the 1990 base year emission inventories for the...

  7. 40 CFR 52.384 - Emission inventories.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Emission inventories. 52.384 Section 52...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Connecticut § 52.384 Emission inventories. (a) The Governor's designee for the State of Connecticut submitted the 1990 base year emission inventories for...

  8. 40 CFR 52.348 - Emission inventories.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Emission inventories. 52.348 Section 52...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Colorado § 52.348 Emission inventories. (a) The Governor of the State of Colorado submitted the 1990 carbon monoxide base year emission inventories for...

  9. 40 CFR 52.1036 - Emission inventories.

    Science.gov (United States)

    2010-07-01

    ... Implementation Plan (SIP). The 2002 base year emission inventory requirement of 40 CFR 51.915 has been satisfied... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Emission inventories. 52.1036 Section...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Maine § 52.1036 Emission inventories. (a)...

  10. 40 CFR 52.2350 - Emission inventories.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Emission inventories. 52.2350 Section...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Utah § 52.2350 Emission inventories. (a) The Governor of the State of Utah submitted the 1990 base year emission inventory of ozone precursors,...

  11. 40 CFR 52.1125 - Emission inventories.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Emission inventories. 52.1125 Section...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1125 Emission inventories... emission inventories for the Springfield nonattainment area and the Massachusetts portion of the...

  12. 40 CFR 52.993 - Emissions inventories.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Emissions inventories. 52.993 Section...) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Louisiana § 52.993 Emissions inventories. (a) The Governor of the State of Louisiana submitted the 1990 base year emission inventories for the Baton...

  13. Competitiveness and linking of emission trading systems

    Energy Technology Data Exchange (ETDEWEB)

    Hausotter, Tobias; Steuwer, Sibyl; Taenzler, Dennis [adelphi, Berlin (Germany)

    2011-01-15

    The establishment of emission trading systems raises concerns among industries regarding international competitive disadvantages for the industries under an emissions cap. This study aims to assess competitiveness exposure of industrial sectors and presents policy measures to address these concerns. Moreover, the study provides a comparison of different existing approaches to competitiveness concerns proposed by regional emission trading systems. (orig.)

  14. Global anthropogenic mercury emission inventory for 2000

    NARCIS (Netherlands)

    Pacyna, Elisabeth G.; Pacyna, Jozef M.; Steenhuisen, Frits; Wilson, Simon

    2006-01-01

    The paper reviews the current state of knowledge regarding global emissions of mercury and presents a new inventory of global emissions of mercury to the atmosphere from anthropogenic sources for the year 2000. The largest emissions of Hg to the global atmosphere occur from combustion of fossil fuel

  15. An Instrument to Measure Aircraft Sulfate Particle Emissions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aircraft particle emissions contribute a modest, but growing, portion of the overall particle emissions budget. Characterizing aircraft particle emissions is...

  16. Light emission in tunneling processes

    International Nuclear Information System (INIS)

    We introduce a new method for mapping and analyzing (with atomic resolution) molecules adsorbed on surfaces. This method relies on the detection of fluorescence from molecules, electronically excited by inelastic tunneling in STM. It may combines the excellent spatial resolution of STM together with the specificity of fluorescence as an analytical tool. We propose to overcome this problem by choosing 'transparent conductors' (such as Indium Tin Oxides-lTO) as the STM substrate. ITO, characterized by a large optical gap, will not quench electronically excited molecules. We have tested our idea to enhance the quantum efficiency of molecular emission on surfaces by using transparent conductors in the tunneling junction. We have constructed large area tunnel-junctions by using the squeezable tunnel-Junction technique. The principle of this technique is to squeeze together smooth flat surfaces separated by a thin spacer. By applying a controlled force, junctions with surface area of thousands of square angstroms are made. We have recorded light emission from bare tunneling surfaces and from surfaces coated with molecules (DCA, DCM and COUMARINE), as a function of the bias voltage in the range of 0-5 volts. Typical tunneling currents are 50 nano ampere. Our main findings are: The bare ITO surface emits light at biasing voltages larger than 4.0 eV which corresponds to electron-hole excitation over the optical gap of ITO. ITO surfaces coated with chromophore molecules have shown enhanced light emission at a voltage bias which corresponds to the allowed excitations energies in the chromophore. A voltage bias of 2-5 V yielded light emission of 5 * 103 photon/μC. The corresponding metallic surfaces, bare or coated with a chromophore did not show any emission. In order to test the possibility of using this effect for imaging purposes we have replaced one electrode of junction with an ITO coated glass tip of 180 μm radius. such a tip yield an upper limit of tunneling area of

  17. 40 CFR 60.36b - Emission guidelines for municipal waste combustor fugitive ash emissions.

    Science.gov (United States)

    2010-07-01

    ... combustor fugitive ash emissions. 60.36b Section 60.36b Protection of Environment ENVIRONMENTAL PROTECTION... September 20, 1994 § 60.36b Emission guidelines for municipal waste combustor fugitive ash emissions. For approval, a State plan shall include requirements for municipal waste combustor fugitive ash emissions...

  18. Thermal radio emission : The brightness temperature and the spectral index of radio emission

    OpenAIRE

    Prigara, F. V.

    2001-01-01

    The condition of radio emission is proposed, on the base of which the theory of themal radio emission for gaseous disk is developed. This theory explains the radio emission spectra of known types of extended radio sources, located beyond the Solar planetary system. Besides, the thermal radio emission spectra of Venus and Jupiter are explained.

  19. Application of the emission inventory model TEAM: Uncertainties in dioxin emission estimates for central Europe

    NARCIS (Netherlands)

    Pulles, M.P.J.; Kok, H.; Quass, U.

    2006-01-01

    This study uses an improved emission inventory model to assess the uncertainties in emissions of dioxins and furans associated with both knowledge on the exact technologies and processes used, and with the uncertainties of both activity data and emission factors. The annual total emissions for the y

  20. Implications of diesel emissions control failures to emission factors and road transport NOx evolution

    Science.gov (United States)

    Ntziachristos, Leonidas; Papadimitriou, Giannis; Ligterink, Norbert; Hausberger, Stefan

    2016-09-01

    Diesel NOx emissions have been at the forefront of research and regulation scrutiny as a result of failures of late vehicle technologies to deliver on-road emissions reductions. The current study aims at identifying the actual emissions levels of late light duty vehicle technologies, including Euro 5 and Euro 6 ones. Mean NOx emission factor levels used in the most popular EU vehicle emission models (COPERT, HBEFA and VERSIT+) are compared with latest emission information collected in the laboratory over real-world driving cycles and on the road using portable emissions measurement systems (PEMS). The comparison shows that Euro 5 passenger car (PC) emission factors well reflect on road levels and that recently revealed emissions control failures do not call for any significant corrections. However Euro 5 light commercial vehicles (LCVs) and Euro 6 PCs in the 2014-2016 period exhibit on road emission levels twice as high as used in current models. Moreover, measured levels vary a lot for Euro 6 vehicles. Scenarios for future evolution of Euro 6 emission factors, reflecting different degree of effectiveness of emissions control regulations, show that total NOx emissions from diesel Euro 6 PC and LCV may correspond from 49% up to 83% of total road transport emissions in 2050. Unless upcoming and long term regulations make sure that light duty diesel NOx emissions are effectively addressed, this will have significant implications in meeting future air quality and national emissions ceilings targets.

  1. Five essays on emissions trading

    Energy Technology Data Exchange (ETDEWEB)

    Godal, Odd

    2005-03-01

    The thesis discusses energy, environmental and economic aspects of polluting emissions with emphasis on greenhouse gas trade and political measures. 5 papers are included with titles: 1) Carbon trading across sources and periods constrained by the Marrakesh Accords which examines examine the potential effects on permit prices and abatement costs of four compliance rules governing emissions trade across sources and periods in the Kyoto Protocol: The banking rule that allows excess permits to be used later; the restoration rate rule that penalizes borrowing; the commitment period reserve rule that limits sales; and finally, the suspension rule that restricts borrowing and sales. Our framework is a two-period model where parties may be out of compliance in the Kyoto period, but are assumed to comply at a later time. Under varying assumptions about market power and US participation, we find that the rules may have pronounced effects on individual costs, but overall efficiency is not severely affected. 2) Affine price expectations and equilibrium in strategic markets which considers equilibrium in imperfect markets, featuring agents who exchange property rights. Important cases include trade in emission permits of greenhouse gases, or exchange of catch quotas of fish. Some players act strategically while others are price-takers. The ''demand curve'' is endogenous, and it affects all parties. The resulting, reduced objectives need not be concave. Therefore, existence of equilibrium is a delicate matter. To simplify things, and to ensure availability of ''equilibria up to first order'', we presume that all strategic agents form affine price expectations. 3) Greenhouse gases, quota exchange and oligopolistic competition that discusses the problem how quotas can be shared in the ''emissions market'' and how can the agents reach as overall equilibrium in the product market. 4) Strategic markets in property rights

  2. Two-Photon Emission from Semiconductors

    CERN Document Server

    Hayat, A; Hayat, Alex; Orenstein, Meir

    2007-01-01

    We report, to the best of our knowledge, the first experimental observation of spontaneous two-photon emission from semiconductors. The overall two-photon emission power is only 4 orders of magnitude smaller than the fundamental one-photon emission power due to the continuous energy band structure of semiconductors. The measured wide-band two-photon emission spectrum is surprisingly blue-shifted in contrast to the two-photon emission from discrete-level atomic systems. This shift can be accounted for by the second-order matrix element k-dependence in semiconductors and the measured spectrum shape appears to be in good agreement with our calculations.

  3. Danish emission inventories for stationary combustion plants

    DEFF Research Database (Denmark)

    Nielsen, M.; Illerup, J. B.

    in stationary combustion has increased by 12% - the fossil fuel consumption however only by 6%. Despite the increased fuel consumption the emission of several pollutants have decreased due to the improved flue gas cleaning technology, improved burner technology and the change of fuel type used. A considerable...... decrease of the SO2, NOx and heavy metal emissions is mainly a result of decreased emissions from large power plants and waste incineration plants. The greenhouse gas emission has decreased 1,5% since 1990. The emission of CH4, however, has increased due to increased use of lean-burn gas engines in CHP...

  4. Danish emission inventories for stationary combustion plants

    DEFF Research Database (Denmark)

    Nielsen, M.; Illerup, J. B.

    in stationary combustion has increased by 14% - the fossil fuel consumption however only by 8%. Despite the increased fuel consumption the emission of several pollutants has decreased due to the improved flue gas cleaning technology, improved burner technology and the change of fuel type used. A considerable...... decrease of the SO2, NOX and heavy metal emissions is mainly a result of decreased emissions from large power plants and waste incineration plants. The greenhouse gas emission has decreased 1,3% since 1990. The emission of CH4, however, has increased due to increased use of lean-burn gas engines in CHP...

  5. Activation of silicon quantum dots for emission

    Institute of Scientific and Technical Information of China (English)

    Huang Wei-Qi; Miao Xin-Jian; Huang Zhong-Mei; Liu Shi-Rong; Qin Chao-Jian

    2012-01-01

    The emission of silicon quantum dots is weak when their surface is passivated well. Oxygen or nitrogen on the surface of silicon quantum dots can break the passivation to form localized electronic states in the band gap to generate active centers where stronger emission occurs.From this point of view,we can build up radiative matter for emission.Emissions of various wavelengths can be obtained by controlling the surface bonds of silicon quantum dots.Our experimental results demonstrate that annealing is important in the treatment of the activation,and stimulated emissions at about 600 and 700 nm take place on active silicon quantum dots.

  6. Marine Engines and Nitrogen Oxides Emissions

    Directory of Open Access Journals (Sweden)

    Corneliu Moroianu

    2008-10-01

    Full Text Available Current international policy initiatives by the International Maritime Organization (IMO to reduce emissions from ship propulsion systems (NOx and SOx, primarily mark the first efforts to define a framework to address this issue. Oxides of nitrogen (NOx emissions from ship engines are significant on a global level. NOx emissions participate in the formation of photochemical smog and acid rain. Marine sourced emissions have significant impact on air quality on land. The challenge is to control NOx emissions without increasing fuel consumption and smoke. Most engine manufacturers can meet the current IMO limits by engine tuning measures

  7. Greenhouse Gas Emissions from Agricultural Production

    DEFF Research Database (Denmark)

    Bennetzen, Eskild Hohlmann

    Global climate change is recognised as one of the major current challenges to humanity. At the same time, climate change is human induced and we hold the opportunity to react accordingly. While global greenhouse gas (GHG) emissions continue to rise, emissions from agriculture and land-use change......-production, respectively. Only emissions from energy use have increased more than production. Our projected BAU scenarios suggest that emissions may be further decoupled by 20 – 55% giving absolute agricultural emissions in the range of 8.2 to 14.5 Pg CO2-eq. yr-1 by 2050; lower than most other suggest from estimates...

  8. 2010 LANL radionuclide air emissions report /

    Energy Technology Data Exchange (ETDEWEB)

    Fuehne, David P.

    2011-06-01

    The emissions of radionuclides from Department of Energy Facilities such as Los Alamos National Laboratory (LANL) are regulated by the Amendments to the Clean Air Act of 1990, National Emissions Standards for Hazardous Air Pollutants (40 CFR 61 Subpart H). These regulations established an annual dose limit of 10 mrem to the maximally exposed member of the public attributable to emissions of radionuclides. This document describes the emissions of radionuclides from LANL and the dose calculations resulting from these emissions for calendar year 2010. This report meets the reporting requirements established in the regulations.

  9. 2008 LANL radionuclide air emissions report

    Energy Technology Data Exchange (ETDEWEB)

    Fuehne, David P.

    2009-06-01

    The emissions of radionuclides from Department of Energy Facilities such as Los Alamos National Laboratory (LANL) are regulated by the Amendments to the Clean Air Act of 1990, National Emissions Standards for Hazardous Air Pollutants (40 CFR 61 Subpart H). These regulations established an annual dose limit of 10 mrem to the maximally exposed member of the public attributable to emissions of radionuclides. This document describes the emissions of radionuclides from LANL and the dose calculations resulting from these emissions for calendar year 2008. This report meets the reporting requirements established in the regulations.

  10. 2009 LANL radionuclide air emissions report

    Energy Technology Data Exchange (ETDEWEB)

    Fuehne, David P.

    2010-06-01

    The emissions of radionuclides from Department of Energy Facilities such as Los Alamos National Laboratory (LANL) are regulated by the Amendments to the Clean Air Act of 1990, National Emissions Standards for Hazardous Air Pollutants (40 CFR 61 Subpart H). These regulations established an annual dose limit of 10 mrem to the maximally exposed member of the public attributable to emissions of radionuclides. This document describes the emissions of radionuclides from LANL and the dose calculations resulting from these emissions for calendar year 2009. This report meets the reporting requirements established in the regulations.

  11. Air emissions inventory for the Idaho National Engineering Laboratory -- 1995 emissions report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-01

    This report presents the 1995 update of the Air Emission Inventory for the Idaho National Engineering Laboratory (INEL). The INEL Air Emission Inventory documents sources and emissions of non-radionuclide pollutants from operations at the INEL. The report describes the emission inventory process and all of the sources at the INEL, and provides non-radionuclide emissions estimates for stationary sources. The air contaminants reported include nitrogen oxides, sulfur oxides, carbon monoxide, volatile organic compounds, particulates, and hazardous air pollutants (HAPs).

  12. Laser-induced ultrafast electron emission from a field emission tip

    OpenAIRE

    Barwick, Brett; Corder, Chris; Strohaber, James; Chandler-Smith, Nate; Uiterwaal, Cornelis; Batelaan, Herman

    2007-01-01

    We show that a field emission tip electron source that is triggered with a femtosecond laser pulse can generate electron pulses shorter than the laser pulse duration (~100 fs). The emission process is sensitive to a power law of the laser intensity, which supports an emission mechanism based on multiphoton absorption followed by over-the-barrier emission. Observed continuous transitions between power laws of different orders are indicative of field emission processes. We show that the source ...

  13. Estimation of vegetative mercury emissions in China

    Institute of Scientific and Technical Information of China (English)

    QUAN Jiannong; ZHANG Xiaoshan; Shang Gyoo SHIM

    2008-01-01

    Vegetative mercury emissions were estimated within the framework of Biogenic Emission Inventory System (BEIS3 V3.11). In this estimation, the 19 categories of U.S. Geological Survey landcover data were incorporated to generate the vegetation-specific mercury emissions in a 81-km Lambert Conformal model grid coveting the total Chinese continent. The surface temperature and cloud-corrected solar radiation from a Mesoscale Meteorological model (MMS) were retrieved and used for calculating the diurnal variation. The implemented emission factors were either evaluated from the measured mercury flux data for forest, agriculture and water, or assumed for other land fields without available flux data. Annual simulations using the MM5 data were performed to investigate the seasonal emission variation. From the sensitivity analysis using two sets of emission factors, the vegetative mercury emissions in China domain were estimated to range from a lower limit of 79×103 kg/year to an upper limit of 177×103 kg/year. The modeled vegetative emissions were mainly generated from the eastern and southern China. Using the estimated data, it is shown that mercury emissions from vegetation are comparable to that from anthropogenic sources during summer. However, the vegetative emissions decrease greatly during winter, leaving anthropogenic sources as the major sources of emission.

  14. Mitigating greenhouse gas emissions: Voluntary reporting

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-01

    The Voluntary Reporting Program, developed pursuant to Section 1605(b) of the Energy Policy Act of 1992, permits corporations, government agencies, households, and voluntary organizations to report on their emissions of greenhouse gases, and on actions taken that have reduced or avoided emissions or sequestered carbon, to the Energy Information Administration (EIA). This, the second annual report of the Voluntary Reporting Program, describes information provided by the participating organizations on their aggregate emissions and emissions reductions, as well as their emissions reduction or avoidance projects, through 1995. This information has been compiled into a database that includes reports from 142 organizations and descriptions of 967 projects that either reduced greenhouse gas emissions or sequestered carbon. Fifty-one reporters also provided estimates of emissions, and emissions reductions achieved, for their entire organizations. The projects described actions taken to reduce emissions of carbon dioxide from energy production and use; to reduce methane and nitrous oxide emissions from energy use, waste management, and agricultural processes; to reduce emissions of halocarbons, such as CFCs and their replacements; and to increase carbon sequestration.

  15. Soil emissivity and reflectance spectra measurements.

    Science.gov (United States)

    Sobrino, José A; Mattar, Cristian; Pardo, Pablo; Jiménez-Muñoz, Juan C; Hook, Simon J; Baldridge, Alice; Ibañez, Rafael

    2009-07-01

    We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 microm with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer.

  16. Emission system upgrades for older vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, R.R.; Finkenbiner, K.; Sommerville, R.J.

    1996-09-01

    Thirteen 1975--1980 model year vehicles were equipped with a set of components to upgrade their emission control systems. Each vehicle was tested before maintenance (as-received), after tune-up and correction of original equipment emission system defects (baseline), and after installation of the emission upgrade system (upgrade). Average emissions of non-methane hydrocarbons (NHMC), carbon monoxide (CO), and nitrogen oxides (NOx) with the emission upgrade system installed were reduced more than 60% from the baseline immediately after upgrade. Six of the vehicles accumulated 48,000 kilometers with the upgrade system. After 48,000 kilometers, average emissions of NMHC and NOx were still reduced approximately 50% compared to the baseline and average emissions of CO were reduced approximately 20%.

  17. Thermal emission by a subwavelength aperture

    Science.gov (United States)

    Joulain, Karl; Ezzahri, Younès; Carminati, Rémi

    2016-04-01

    We calculate, by means of fluctuational electrodynamics, the thermal emission of an aperture separating from the outside, vacuum or a material at temperature T. We show that thermal emission is very different whether the aperture size is large or small compared to the thermal wavelength. Subwavelength apertures separating vacuum from the outside have their thermal emission strongly decreased compared to classical blackbodies which have an aperture much larger than the wavelength. A simple expression of their emissivity can be calculated and their total emissive power scales as T8 instead of T4 for large apertures. Thermal emission of disk of materials with a size comparable to the wavelength is also discussed. It is shown in particular that emissivity of such a disk is increased when the material can support surface waves such as phonon polaritons.

  18. Uncertainties in emission data; Onzekerheden in emissiecijfers

    Energy Technology Data Exchange (ETDEWEB)

    Droege, R. [TNO, Nijmegen (Netherlands)

    2012-12-15

    Uncertainties in data of national emissions are in the order of 5% (greenhouse gases) and 10% (acidifying substances). Also recalculations of emissions show that the emission in the Netherlands is not an absolute number, but a range of possible emissions. In assessing emission reduction agreements an analysis was made whether or not the absolute emission meets the commitments, but the uncertainty aspect is not included. Data uncertainty analyses are particularly useful for prioritizing the various possibilities for improving the quality of the emission estimates [Dutch] Onzekerheden in nationale emissiecijfers zijn in de ordegrootte van 5% (broeikasgassen) en 10% (verzurende stoffen). Ook herberekeningen van emissies laten zien dat de emissie in Nederland geen absoluut getal is, maar een range van mogelijke emissies. Bij het beoordelen van emissiereductie afspraken wordt bekeken of de absolute emissie voldoet aan de afspraken en wordt de onzekerheid hierin niet meegenomen. Onzekerheidsanalyses zijn vooral bruikbaar voor het prioriteren van de verschillende mogelijkheden tot kwaliteitsverbetering van de emissieschatting.

  19. Danish emission inventories for stationary combustion plants

    DEFF Research Database (Denmark)

    Nielsen, Malene; Nielsen, Ole-Kenneth; Plejdrup, Marlene Schmidt

    of decreased emissions from large power plants and waste incineration plants. The combustion of wood in residential plants has increased considerably until 2007 resulting in increased emission of PAH and particulate matter. The emission of NMVOC has increased since 1990 as a result of both the increased...... combustion of wood in residential plants and the increased emission from lean-burn gas engines. The PCDD/F emission decreased since 1990 due to flue gas cleaning on waste incineration plants.......Emission inventories for stationary combustion plants are presented and the methodologies and assumptions used for the inventories are described. The pollutants considered are SO2, NOx, NMVOC, CH4, CO, CO2, N2O, NH3, particulate matter, heavy metals, PCDD/F, HCB and PAH. The CO2 emission in 2011...

  20. Emissions from tropical hydropower and the IPCC

    International Nuclear Information System (INIS)

    Highlights: • Tropical dams emit greenhouse gases, which are undercounted in IPCC guidelines. • IPCC comparisons with other energy sources undercount hydroelectric emissions. • GHG inventories must fully count emissions as a basis for negotiating national quotas. • The IPCC needs to reassess emissions from dams independent of the hydropower industry. - Abstract: Tropical hydroelectric emissions are undercounted in national inventories of greenhouse gases under the United Nations Framework Convention on Climate Change (UNFCCC), giving them a role in undermining the effectiveness of as-yet undecided emission limits. These emissions are also largely left out of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Renewable Energy Sources and Climate Change Mitigation, and have been excluded from a revision of the IPCC guidelines on wetlands. The role of hydroelectric dams in emissions inventories and in mitigation has been systematically ignored

  1. Inventories and scenarios of nitrous oxide emissions

    International Nuclear Information System (INIS)

    Effective mitigation for N2O emissions, now the third most important anthropogenic greenhouse gas and the largest remaining anthropogenic source of stratospheric ozone depleting substances, requires understanding of the sources and how they may increase this century. Here we update estimates and their uncertainties for current anthropogenic and natural N2O emissions and for emissions scenarios to 2050. Although major uncertainties remain, ‘bottom-up’ inventories and ‘top-down’ atmospheric modeling yield estimates that are in broad agreement. Global natural N2O emissions are most likely between 10 and 12 Tg N2O-N yr−1. Net anthropogenic N2O emissions are now about 5.3 Tg N2O-N yr−1. Gross anthropogenic emissions by sector are 66% from agriculture, 15% from energy and transport sectors, 11% from biomass burning, and 8% from other sources. A decrease in natural emissions from tropical soils due to deforestation reduces gross anthropogenic emissions by about 14%. Business-as-usual emission scenarios project almost a doubling of anthropogenic N2O emissions by 2050. In contrast, concerted mitigation scenarios project an average decline of 22% relative to 2005, which would lead to a near stabilization of atmospheric concentration of N2O at about 350 ppb. The impact of growing demand for biofuels on future projections of N2O emissions is highly uncertain; N2O emissions from second and third generation biofuels could remain trivial or could become the most significant source to date. It will not be possible to completely eliminate anthropogenic N2O emissions from agriculture, but better matching of crop N needs and N supply offers significant opportunities for emission reductions. (paper)

  2. Modeling of pesticide emissions from agricultural ecosystems

    Science.gov (United States)

    Li, Rong

    2012-04-01

    Pesticides are applied to crops and soils to improve agricultural yields, but the use of pesticides has become highly regulated because of concerns about their adverse effects on human health and environment. Estimating pesticide emission rates from soils and crops is a key component for risk assessment for pesticide registration, identification of pesticide sources to the contamination of sensitive ecosystems, and appreciation of transport and fate of pesticides in the environment. Pesticide emission rates involve processes occurring in the soil, in the atmosphere, and on vegetation surfaces and are highly dependent on soil texture, agricultural practices, and meteorology, which vary significantly with location and/or time. To take all these factors into account for simulating pesticide emissions from large agricultural ecosystems, this study coupled a comprehensive meteorological model with a dynamic pesticide emission model. The combined model calculates hourly emission rates from both emission sources: current applications and soil residues resulting from historical use. The coupled modeling system is used to compute a gridded (36 × 36 km) hourly toxaphene emission inventory for North America for the year 2000 using a published U.S. toxaphene residue inventory and a Mexican toxaphene residue inventory developed using its historical application rates and a cropland inventory. To my knowledge, this is the first such hourly toxaphene emission inventory for North America. Results show that modeled emission rates have strong diurnal and seasonal variations at a given location and over the entire domain. The simulated total toxaphene emission from contaminated agricultural soils in North America in 2000 was about 255 t, which compares reasonably well to a published annual estimate. Most emissions occur in spring and summer, with domain-wide emission rates in April, May and, June of 36, 51, and 35 t/month, respectively. The spatial distribution of emissions depends

  3. Learning from global emissions scenarios

    International Nuclear Information System (INIS)

    Scenarios of global greenhouse gas emissions have played a key role in climate change analysis for over twenty years. Currently, several research communities are organizing to undertake a new round of scenario development in the lead-up to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). To help inform this process, we assess a number of past efforts to develop and learn from sets of global greenhouse gas emissions scenarios. We conclude that while emissions scenario exercises have likely had substantial benefits for participating modeling teams and produced insights from individual models, learning from the exercises taken as a whole has been more limited. Model comparison exercises have typically focused on the production of large numbers of scenarios while investing little in assessing the results or the production process, perhaps on the assumption that later assessment efforts could play this role. However, much of this assessment potential remains untapped. Efforts such as scenario-related chapters of IPCC reports have been most informative when they have gone to extra lengths to carry out more specific comparison exercises, but in general these assessments do not have the remit or resources to carry out the kind of detailed analysis of scenario results necessary for drawing the most useful conclusions. We recommend that scenario comparison exercises build-in time and resources for assessing scenario results in more detail at the time when they are produced, that these exercises focus on more specific questions to improve the prospects for learning, and that additional scenario assessments are carried out separately from production exercises. We also discuss the obstacles to better assessment that might exist, and how they might be overcome. Finally, we recommend that future work include much greater emphasis on understanding how scenarios are actually used, as a guide to improving scenario production.

  4. Trace element emissions. Literature review

    International Nuclear Information System (INIS)

    Application of fossil fuels by various utilities results in the emission of trace elements to air, water and solid waste streams. Elements present in coal are released as particles or as vapours during coal combustion or gasification. Owing to the increased consumption of coal, especially for power generation, huge quantities of potentially hazardous trace elements are released into the atmosphere every year. It is necessary to evaluate the emissions of each trace element from coal-fired combustion or gasification systems, and their effects on the environment. Present research interests should be aimed at determining the sources, concentrations, and environmental impact of trace elements related with energy generation and relevant control technologies. Two of the emerging advanced coal gasification technologies, such as integrated gasification combined cycle (IGCC) and integrated gasification fuel cell (IGFC) are presently experiencing potential difficulties due to trace element emissions. In order to control the levels of these contaminants within regulatory limits and to ensure the efficient operation of fuel cells, it is necessary to determine the type and quantity of trace elements emitted from coal gasification-based systems as a function of system, operating conditions, and type of coal. The partitioning of the trace elements is influenced by the gasification conditions. In general, the following gasification conditions are expected to influence the distribution of trace elements between various product streams. (a) reducing and oxidizing environments (b) gas phase composition, pressure and temperature. The present report was aimed at finding and identifying gaps existing in the literature on the trace element transformations during gasification. Also included in the report is the modelling of relevant transformation mechanisms of the trace elements during gasification as a function of coal type and process conditions. 7 figs., 6 tabs., 69 refs

  5. Secondary emission monitor (SEM) grids.

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    A great variety of Secondary Emission Monitors (SEM) are used all over the PS Complex. At other accelerators they are also called wire-grids, harps, etc. They are used to measure beam density profiles (from which beam size and emittance can be derived) in single-pass locations (not on circulating beams). Top left: two individual wire-planes. Top right: a combination of a horizontal and a vertical wire plane. Bottom left: a ribbon grid in its frame, with connecting wires. Bottom right: a SEM-grid with its insertion/retraction mechanism.

  6. Electromagnetic emissions during rock blasting

    Science.gov (United States)

    O'Keefe, S. G.; Thiel, D. V.

    1991-05-01

    Radio emissions during quarry blasting have been recorded in the audio frequency band. Three distinct mechanisms are suggested to explain the observed results; rock fracture at the time of the explosion, charged rocks discharging on impact with the pit floor and micro-fracture of the remaining rock wall due to pressure adjustment of the bench behind the blast. The last mechanism was evident by a train of discrete impulses recorded for up to one minute after the blast. It is assumed that during this time the rock behind the blast was subjected to a significant change in pressure. This may be related to ELF observations during earthquakes.

  7. Emissivity Measurement of Semitransparent Textiles

    OpenAIRE

    Ferrarini, G.; G. Cadelano; A. Bortolin; P. Bison; Grinzato, E.

    2012-01-01

    In the textiles production industry it is more and more common to advertise new textiles, especially for sportswear, by claiming their ability to emit IR radiation in the long wave band at a higher degree with respect to normal clothes, that is highly beneficial to improve sporting performances. Three textiles are compared, one normal and two “special,” with Ag+ ions and carbon powder added, with different colors. The emissivity of the textiles has been measured to determine if it is increase...

  8. 47 CFR 87.137 - Types of emission.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Types of emission. 87.137 Section 87.137... Technical Requirements § 87.137 Types of emission. (a) The assignable emissions, corresponding emission designators and authorized bandwidths are as follows: Class of emission Emission designator...

  9. Dioxin air emission inventory 1990-2004

    Energy Technology Data Exchange (ETDEWEB)

    Capral Henriksen, T.; Illerup, J.B.; Nielsen, Ole-Kenneth [DMU, Dept. of Policy Analysis (Denmark)

    2006-12-15

    The present Danish dioxin air emission inventory shows that the emission has been reduced from 68.6 g I-TEQ in 1990 to 22.0 g I-TEQ in 2004, or about 68% over this period. Most of the significant reductions have been achieved in the industrial sector, where emissions have been reduced from 14.67 g I-TEQ in 1990 to 0.17 g I-TEQ in 2004; a reduction of almost 99%. Lower emissions from steel and aluminium reclamation industries form the major part of the reduction within industry. Emissions from waste incineration reduced from 32.5 g I-TEQ in 1990 to 2.1 g ITEQ in 2004; which is approx. 94%. This is due to installation of dioxin abatement equipment in incineration plants. The most important source of emission in 2004 is residential wood combustion, at 8.5 g I-TEQ, or around 40% of the total emission. In 2004, accidental fires, which are estimated to emit 6.1 g I-TEQ/year, are the second most important source, contributing with around 28% of the total emission. The present dioxin emission inventory for Denmark shows how emissions in 2004 come from sources other than waste incineration plants and industry, which were the largest sources in 1990. (au)

  10. Emissions of Greenhouse gases in the Netherlands

    Energy Technology Data Exchange (ETDEWEB)

    Evers, C.W.A. [Ministry of Housing, The Hague (Netherlands). Inspectorate for Environmental Protection; Berdowski, J.J.M.; Pulles, T.P.J. [TNO Inst. for Environmental Sciences, Delft (Netherlands)

    1995-12-31

    The Dutch emission inventory system enables the registration, analysis and localization of emission data of both industrial and non-industrial sources in the Netherlands. The results can be used to test the effectiveness of governmental environmental policy. These activities are part of the policy evaluation tasks of the Inspectorate General for Environmental Protection (IGEP) and of the Ministry of Transport, Public Works and Water Management. The emission inventory takes place in cycles of one year. Recently, the most relevant results of the Dutch emission inventory for 1992 have been published. In that cycle the emissions in 1992 to air and water from about 800 major companies have been registered. These 800 companies are the most important contributors to the total industrial emissions in the Netherlands. The emissions of these companies are registered within the individual inventory system. The emissions from the smaller enterprises and from diffuse non-industrial sources are stored in the collective emission inventory system. The data collected in the 1992 inventory have been established for the first time in close cooperation between the IGEP, TNO, the Central Bureau of Statistics and the National Institute of Public Health and Environmental Protection. This implies that the data presented here have to be considered as the official data for the emissions in the Netherlands for the year 1992. (author)

  11. Single-photon emission tomography.

    Science.gov (United States)

    Goffin, Karolien; van Laere, Koen

    2016-01-01

    Single-photon emission computed tomography (SPECT) is a functional nuclear imaging technique that allows visualization and quantification of different in vivo physiologic and pathologic features of brain neurobiology. It has been used for many years in diagnosis of several neurologic and psychiatric disorders. In this chapter, we discuss the current state-of-the-art of SPECT imaging of brain perfusion and dopamine transporter (DAT) imaging. Brain perfusion SPECT imaging plays an important role in the localization of the seizure onset zone in patients with refractory epilepsy. In cerebrovascular disease, it can be useful in determining the cerebrovascular reserve. After traumatic brain injury, SPECT has shown perfusion abnormalities despite normal morphology. In the context of organ donation, the diagnosis of brain death can be made with high accuracy. In neurodegeneration, while amyloid or (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) are the nuclear diagnostic tools of preference for early and differential diagnosis of dementia, perfusion SPECT imaging can be useful, albeit with slightly lower accuracy. SPECT imaging of the dopamine transporter system is widely available in Europe and Asia, but since recently also in the USA, and has been accepted as an important diagnostic tool in the early and differential diagnosis of parkinsonism in patients with unclear clinical features. The combination of perfusion SPECT (or FDG-PET) and DAT imaging provides differential diagnosis between idiopathic Parkinson's disease, Parkinson-plus syndromes, dementia with Lewy bodies, and essential tremor. PMID:27432669

  12. Directional spectral emissivity measurement system

    Science.gov (United States)

    Halyo, Nesim (Inventor); Pandey, Dhirendra K. (Inventor)

    1992-01-01

    Apparatus and process for determining the emissivity of a test specimen including an integrated sphere having two concentric walls with a coolant circulating therebetween, and disposed within a chamber which may be under ambient, vacuum or inert gas conditions. A reference sample is disposed within the sphere with a monochromatic light source in optical alignment therewith. A pyrometer is in optical alignment with the test sample for obtaining continuous test sample temperature measurements during a test. An arcuate slit port is provided through the spaced concentric walls of the integrating sphere with a movable monochromatic light source extending through and movable along the arcuate slit port. A detector system extends through the integrating sphere for continuously detecting an integrated signal indicative of all radiation within its field of view, as a function of the emissivity of the test specimen at various temperatures and various angle position of the monochromatic light source. A furnace for heating the test sample to approximately 3000 K. and control mechanism for transferring the heated sample from the furnace to the test sample port in the integrating sphere is also contained within the chamber.

  13. Greenhouse Gas Emissions From Cattle

    Directory of Open Access Journals (Sweden)

    Podkówka Zbigniew

    2015-03-01

    Full Text Available Cattle produce greenhouse gases (GHG which lead to changes in the chemical composition of the atmosphere. These gases which cause greenhouse effect include: methane (CH4, nitrous oxide (N2O, nitrogen oxides (NOx, sulphur dioxide (SO2, ammonia (NH3, dust particles and non-methane volatile organic compounds, commonly described as other than methane hydrocarbons. Fermentation processes taking place in the digestive tract produce ‘digestive gases’, distinguished from gases which are emitted during the decomposition of manure. Among these digestive gases methane and non-methane volatile organic compounds are of particular relevance importance. The amount of gases produced by cows can be reduced by choosing to rear animals with an improved genetically based performance. A dairy cow with higher production efficiency, producing milk with higher protein content and at the same time reduced fat content emits less GHG into the environment. Increasing the ratio of feed mixtures in a feed ration also reduces GHG emissions, especially of methane. By selection of dairy cows with higher production efficiency and appropriate nutrition, the farm's expected milk production target can be achieved while at the same time, the size of the herd is reduced, leading to a reduction of GHG emissions.

  14. Reducing emissions from uranium dissolving

    International Nuclear Information System (INIS)

    This study was designed to assess the feasibility of decreasing NOx emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NOx fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NOx emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO2 which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered

  15. Flare emission from Sagittarius A*

    CERN Document Server

    Eckart, A; Vogel, S N; Teuben, P; Morris, M R; Baganoff, F; Dexter, J; Schoedel, R; Witzel, G; Valencia-S., M; Karas, V; Kunneriath, D; Bremer, M; Straubmeier, C; Moser, L; Sabha, N; Buchholz, R; Zamaninasab, M; Muzic, K; Moultaka, J; Zensus, J A

    2012-01-01

    Based on Bremer et al. (2011) and Eckart et al. (2012) we report on simultaneous observations and modeling of the millimeter, near-infrared, and X-ray flare emission of the source Sagittarius A* (SgrA*) associated with the super-massive black hole at the Galactic Center. We study physical processes giving rise to the variable emission of SgrA* from the radio to the X-ray domain. To explain the statistics of the observed variability of the (sub-)mm spectrum of SgrA*, we use a sample of simultaneous NIR/X-ray flare peaks and model the flares using a synchrotron and SSC mechanism. The observations reveal flaring activity in all wavelength bands that can be modeled as the signal from adiabatically expanding synchrotron self-Compton (SSC) components. The model parameters suggest that either the adiabatically expanding source components have a bulk motion larger than v_exp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of SgrA*. For the bulk of the synchrotron and ...

  16. An Emission Saved is an Emission Earned: An Empirical Study of Emission Banking for Light-Duty Vehicle Manufacturers

    OpenAIRE

    Rubin, Jonathan D.; Kling, Catherine

    1993-01-01

    This paper presents results of an empirical study of emission banking for light-duty vehicle manufacturers. An intertemporal model of manufacturers' choices is combined with econometrically estimated abatement cost functions to simulate the cost savings and emission effects of an averaging, trading, and banking marketable permit system relative to command-and-control regulations. While the cost savings of such a system are estimated to be modest, the intertemporal emission effects may be siza...

  17. Allocation of CO2 emission allowances. Distribution of emission allowances in a European emissions trading scheme

    Energy Technology Data Exchange (ETDEWEB)

    Harmsen, H.; Van der Kolk, J. [KPMG Sustainability, Amstelveen (Netherlands); Kerssemeeckers, M.; De Beer, J. [Ecofys, Utrecht (Netherlands)

    2002-10-01

    The European Commission has submitted a draft directive on Emissions Trading on 23 October 2001. In this system, each Member State has to submit an allocation plan that describes the allowances that will be distributed, and how these will be distributed among the operators of each participating installation. In this study the possible allocation options and their consequences are investigated; the potential bottlenecks are assessed, which would occur if the Netherlands developed a national allocation plan; the criteria for national allocation plans are assessed (Annex III draft directive); and some possibilities for solutions are presented.

  18. Quantification of acetone emission from pine plants

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Acetone emission from pine plants (pinus sylvestris) is measured by continuously stirred tank reactor. Under a constant light intensity, acetone emission rates increase exponentially with leaf temperature. When leaf temperature is kept constant, acetone emission increases with light intensity. And acetone emission in darkness is also detected. Acetone emitted from pine is quickly labeled by 13C when the plants are exposed to air with 630 mg/m3 13CO2. However, no more than 20% of acetone is 13C labeled. Acetone emission from pine may be due to both leaf temperature- controlled process and light intensity-controlled process. Based on these understandings, an algorithm is used to describe the short term acetone emission rates from pine.

  19. Probing Field Emission from Boron Carbide Nanowires

    Institute of Scientific and Technical Information of China (English)

    TIAN Ji-Fa; GAO Hong-Jun; BAO Li-Hong; WANG Xing-Jun; HUI Chao; LIU Fei; LI Chen; SHEN Cheng-Min; WANG Zong-Li; GU Chang-Zhi

    2008-01-01

    High density boron carbide nanowires are grown by an improved carbon thermal reduction technique. Transmission electron microscopy and electron energy lose spectroscopy of the sample show that the synthesized nanowires are B4 C with good crystallization. The field emission measurement for an individual boron nanowire is performed by using a Pt tip installed in the focused ion beam system. A field emission current with enhancement factor of 106 is observed and the evolution process during emission is also carefully studied. Furthermore, a two-step field emission with stable emission current density is found from the high-density nanowire film. Our results together suggest that boron carbide nanowires are promising candidates for electron emission nanodevices.

  20. Thermal Emission by a Subwavelength Aperture

    CERN Document Server

    Joulain, Karl; Carminati, Rémi

    2015-01-01

    We calculate, by means of fluctuational electrodynamics, the thermal emission of an aperture filled by vacuum or a material at temperature T. We show that thermal emission is very different whether the aperture size is large or small compared to the thermal wavelength. Subwavelength apertures filled with vacuum (subwavelength blackbody) have their thermal emission strongly decreased compared to classical blackbodies. A simple expression of their emissivity can be calculated and their total emittance scales as T 8 instead of T 4 for large apertures. Thermal emission of disk of materials with a size comparable to the wavelength is also discussed. It is shown in particular that emissivity of such a disk is increased when the material can support surface waves such as phonon polaritons.

  1. An explanation of carbon emission markets

    International Nuclear Information System (INIS)

    After having outlined the necessity to drastically reduce anthropic carbon emissions, and discussed how to associate standards, taxes and quota markets, the authors describe how carbon emission markets have emerged: the Kyoto protocol, the emission trade scheme (ETS) of the European Union, other carbon markets (existing or in preparation). They introduce and present four pillars of carbon emission markets: the allocation process, the reliability of emission measurement and control, market records and transparency, and introduction of flexibility. They examine the possibility of success in the development of a greenhouse gas emission market. The authors discuss the problems raised by a design of carbon markets by government and their use by private actors, how to connect existing or future regional carbon markets, the integration of forest and agriculture through new compensatory mechanisms, how to face carbon leaks by widening carbon markets

  2. Anthropogenic sulfur dioxide emissions: 1850–2005

    Directory of Open Access Journals (Sweden)

    S. J. Smith

    2011-02-01

    Full Text Available Sulfur aerosols impact human health, ecosystems, agriculture, and global and regional climate. A new annual estimate of anthropogenic global and regional sulfur dioxide emissions has been constructed spanning the period 1850–2005 using a bottom-up mass balance method, calibrated to country-level inventory data. Global emissions peaked in the early 1970s and decreased until 2000, with an increase in recent years due to increased emissions in China, international shipping, and developing countries in general. An uncertainty analysis was conducted including both random and systemic uncertainties. The overall global uncertainty in sulfur dioxide emissions is relatively small, but regional uncertainties ranged up to 30%. The largest contributors to uncertainty at present are emissions from China and international shipping. Emissions were distributed on a 0.5° grid by sector for use in coordinated climate model experiments.

  3. Emissions of volatile organic compounds from wood

    OpenAIRE

    Granström, Karin

    2005-01-01

    The central aim of this thesis is to support the efforts to counteract certain environmental problems caused by emissions of volatile organic compounds. The purpose of this work was (1) to develop a method to establish the amount of emitted substances from dryers, (2) to determine the effect of drying medium temperature and end moisture content of the processed material on emissions of monoterpenes and other hydrocarbons, (3) to examine the emissions of monoterpenes during production of pelle...

  4. Arctic shipping emissions inventories and future scenarios

    OpenAIRE

    J. J. Corbett; D. A. Lack; J. J. Winebrake; Harder, S; J. A. Silberman; Gold, M.

    2010-01-01

    This paper presents 5 km×5 km Arctic emissions inventories of important greenhouse gases, black carbon and other pollutants under existing and future (2050) scenarios that account for growth of shipping in the region, potential diversion traffic through emerging routes, and possible emissions control measures. These high-resolution, geospatial emissions inventories for shipping can be used to evaluate Arctic climate sensitivity to black carbon (a short-lived climate forcing pollutant especial...

  5. Spontaneous emission of molecules in open resonators

    CERN Document Server

    Datsyuk, V V

    2002-01-01

    The formulas for the molecule and atoms spontaneous emission rate in the arbitrary open resonator in the weak bond approximation with an account of the emission absorption or increase through the resonator substance is obtained within the frames of the classical electrodynamics. The proposed formulas agrees well with the data on the microdrops luminescence. The effect of the spontaneous resonance emission rate suppression through the laser active medium is forecasted

  6. Matrix silicon microcathodes for field emission displays

    Directory of Open Access Journals (Sweden)

    Druzhynin А. A.

    2009-11-01

    Full Text Available The existing and perspective types of flat displays are analyzed. The structure of field emission display pixel cell, materials of microcathodes and technologies of their manufacturing are considered. Matrix silicon microcathodes for field emission displays are offered and the sequence of base operations of their manufacturing on SOI-substrate is developed. The density of field emission current of the matrix microcathode is calculated.

  7. Biophoton Emission Induced by Heat Shock

    OpenAIRE

    Kobayashi, Katsuhiro; Okabe, Hirotaka; Kawano, Shinya; Hidaka, Yoshiki; Hara, Kazuhiro

    2014-01-01

    Ultraweak biophoton emission originates from the generation of reactive oxygen species (ROS) that are produced in mitochondria as by-products of cellular respiration. In healthy cells, the concentration of ROS is minimized by a system of biological antioxidants. However, heat shock changes the equilibrium between oxidative stress and antioxidant activity, that is, a rapid rise in temperature induces biophoton emission from ROS. Although the rate and intensity of biophoton emission was observe...

  8. Emission trading under the Kyoto Protocol

    OpenAIRE

    Holtsmark, Bjart; Hagem, Cathrine

    2003-01-01

    On 11 December 1997, delegates to the third conference of the Parties to the UN Framework Convention on Climate Change agreed upon the Kyoto Protocol. The protocol sets binding emission targets for developed nations (Annex B countries). The Protocol states that Annex B countries may participate in emission trading. The rules for emission trading are to be discussed at the fourth Conference of the Parties in November 1998. differentiation of targets among countries, but not in any system...

  9. SPATIAL VARIATIONS IN BIOGENIC EMISSIONS FOR LITHUANIA

    OpenAIRE

    Ulevičius, Vidmantas; Byčenkien, Svetlana; Senuta, Kestas

    2008-01-01

    Abstract: The numerical modelling of biogenic volatile organic compounds (BVOCs) monoterpene and isoprene was carried out using three-dimensional (3D) mesoscale meteorological and photochemical atmospheric models. Emission factors, combined with land cover data represented by the appropriate 11 Biogenic Emission Inventory System (BEIS) vegetation categories, along with environmental correction factors were used to derive emission fluxes of isoprene, monoterpene and other VOCs for Lit...

  10. Determinants and predictability of global wildfire emissions

    Directory of Open Access Journals (Sweden)

    W. Knorr

    2012-08-01

    Full Text Available Biomass burning is one of the largest sources of atmospheric trace gases and aerosols globally. These emissions have a major impact on the radiative balance of the atmosphere and on air quality, and are thus of significant scientific and societal interest. Several datasets have been developed that quantify those emissions on a global grid and offered to the atmospheric modelling community. However, no study has yet attempted to systematically quantify the dependence of the inferred pyrogenic emissions on underlying assumptions and input data. Such a sensitivity study is needed for understanding how well we can currently model those emissions and what the factors are that contribute to uncertainties in those emission estimates.

    Here, we combine various satellite-derived burned area products, a terrestrial ecosystem model to simulate fuel loads and the effect of fire on ecosystem dynamics, a model of fuel combustion, and various emission models that relate combusted biomass to the emission of various trace gases and aerosols. We carry out simulations with varying parameters for combustion completeness and fuel decomposition rates within published estimates, four different emissions models and three different global burned-area products. We find that variations in combustion completeness and simulated fuel loads have the largest impact on simulated global emissions for most species, except for some with highly uncertain emission factors. Variation in burned-area estimates also contribute considerably to emission uncertainties. We conclude that global models urgently need more field-based data for better parameterisation of combustion completeness and validation of simulated fuel loads, and that further validation and improvement of burned area information is necessary for accurately modelling global wildfire emissions. The results are important for chemical transport modelling studies, and for simulations of biomass burning impacts on the

  11. 47 CFR 95.631 - Emission types.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission types. 95.631 Section 95.631... SERVICES Technical Regulations Technical Standards § 95.631 Emission types. (a) A GMRS transmitter must transmit only emission types A1D, F1D, G1D, H1D, J1D, R1D, A3E, F3E, G3E, H3E, J3E or R3E. A...

  12. Emission Credit Trading and Regional Inequalities

    OpenAIRE

    Takatsuka, Hajime; Nakamura, Ryohei

    2010-01-01

    This paper examines how regional inequalities are affected by emission controls via credit trading and availability of absorption sources. We assume that homogeneous goods are costly traded without emission controls and that the rural areas have an advantage in terms of the availability of absorption sources. We especially focus on the long-term effects of firm relocation. Our two key findings are as follows. First, in the case where an emission control scheme is implemented without allowing ...

  13. Using emission standards under incomplete compliance.

    OpenAIRE

    Rousseau, Sandra

    2003-01-01

    Using the case study of water pollution in the Flemish textile industry, we discuss three empirical questions concerning the use of emission standards. Firstly, given a particular emission standard and the willingness to pay (WTP) for an environmental improvement, which monitoring and enforcement policy provides us with the highest welfare? Secondly, given the WTP, which combination of an emission standard and a monitoring and enforcement strategy gives the highest welfare level? Thirdly, if ...

  14. Linking GHG Emission Trading Systems and Markets

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    Several different types of links are possible between different GHG-mitigation systems. These include: Linking two or more emission trading schemes so that emissions trading can occur both within and between different schemes ('direct links'); and Linking emission trading systems to registries/mechanisms and systems that generate offsets from project based mechanisms or from direct purchases/transfers of AAUs ('indirect links').

  15. Continental anthropogenic primary particle number emissions

    Science.gov (United States)

    Paasonen, Pauli; Kupiainen, Kaarle; Klimont, Zbigniew; Visschedijk, Antoon; Denier van der Gon, Hugo A. C.; Amann, Markus

    2016-06-01

    Atmospheric aerosol particle number concentrations impact our climate and health in ways different from those of aerosol mass concentrations. However, the global, current and future anthropogenic particle number emissions and their size distributions are so far poorly known. In this article, we present the implementation of particle number emission factors and the related size distributions in the GAINS (Greenhouse Gas-Air Pollution Interactions and Synergies) model. This implementation allows for global estimates of particle number emissions under different future scenarios, consistent with emissions of other pollutants and greenhouse gases. In addition to determining the general particulate number emissions, we also describe a method to estimate the number size distributions of the emitted black carbon particles. The first results show that the sources dominating the particle number emissions are different to those dominating the mass emissions. The major global number source is road traffic, followed by residential combustion of biofuels and coal (especially in China, India and Africa), coke production (Russia and China), and industrial combustion and processes. The size distributions of emitted particles differ across the world, depending on the main sources: in regions dominated by traffic and industry, the number size distribution of emissions peaks in diameters range from 20 to 50 nm, whereas in regions with intensive biofuel combustion and/or agricultural waste burning, the emissions of particles with diameters around 100 nm are dominant. In the baseline (current legislation) scenario, the particle number emissions in Europe, Northern and Southern Americas, Australia, and China decrease until 2030, whereas especially for India, a strong increase is estimated. The results of this study provide input for modelling of the future changes in aerosol-cloud interactions as well as particle number related adverse health effects, e.g. in response to tightening

  16. Simple emission metrics for climate impacts

    Directory of Open Access Journals (Sweden)

    B. Aamaas

    2013-06-01

    Full Text Available In the context of climate change, emissions of different species (e.g., carbon dioxide and methane are not directly comparable since they have different radiative efficiencies and lifetimes. Since comparisons via detailed climate models are computationally expensive and complex, emission metrics were developed to allow a simple and straightforward comparison of the estimated climate impacts of emissions of different species. Emission metrics are not unique and variety of different emission metrics has been proposed, with key choices being the climate impacts and time horizon to use for comparisons. In this paper, we present analytical expressions and describe how to calculate common emission metrics for different species. We include the climate metrics radiative forcing, integrated radiative forcing, temperature change and integrated temperature change in both absolute form and normalised to a reference gas. We consider pulse emissions, sustained emissions and emission scenarios. The species are separated into three types: CO2 which has a complex decay over time, species with a simple exponential decay, and ozone precursors (NOx, CO, VOC which indirectly effect climate via various chemical interactions. We also discuss deriving Impulse Response Functions, radiative efficiency, regional dependencies, consistency within and between metrics and uncertainties. We perform various applications to highlight key applications of emission metrics, which show that emissions of CO2 are important regardless of what metric and time horizon is used, but that the importance of short lived climate forcers varies greatly depending on the metric choices made. Further, the ranking of countries by emissions changes very little with different metrics despite large differences in metric values, except for the shortest time horizons (GWP20.

  17. Correlating Engine NOx Emission with Biodiesel Composition

    Science.gov (United States)

    Jeyaseelan, Thangaraja; Mehta, Pramod Shankar

    2016-06-01

    Biodiesel composition comprising of saturated and unsaturated fatty acid methyl esters has a significant influence on its properties and hence the engine performance and emission characteristics. This paper proposes a comprehensive approach for composition-property-NOx emission analysis for biodiesel fuels and highlights the pathways responsible for such a relationship. Finally, a procedure and a predictor equation are developed for the assessment of biodiesel NOx emission from its composition details.

  18. Volatile organic compounds emission inventory of a petrochemical industry: tanks and fugitive emissions

    Directory of Open Access Journals (Sweden)

    Ana Claudia Camargo de Lima Tresmondi

    2006-12-01

    Full Text Available Paulínia, located in the state of São Paulo, has an important industrial center, and its industries represent the biggest source of volatile organic compounds (VOC emissions to the atmosphere. These compounds are emitted by fugitive emissions and some point sources and can present adverse effect in the environment and the health human being, besides exerting an important influence in the formation of photochemical oxidants, as ozone. The present work refers to a VOC emission inventory of a petrochemical industry located in the Paulínia petrochemical complex. The inventory was done based on emission factors and emission model from the United States Environmental Protection Agency (U.S.EPA. The emission critical points in manufacture were determined as well as fugitive emissions in equipments and emissions in some VOC storage tanks. The results show that the main emission source is due to fugitive emissions (99%, being flanges the responsible for the major emissions. After the results got from this inventory, the company knowing some of the main emission sources can monitor them to verify if the results are correct, and implement modifications when necessary maintenance, in order to minimize such emissions.

  19. Survey of emissivity measurement by radiometric methods.

    Science.gov (United States)

    Honner, M; Honnerová, P

    2015-02-01

    A survey of the state of the art in the field of spectral directional emissivity measurements by using radiometric methods is presented. Individual quantity types such as spectral, band, or total emissivity are defined. Principles of emissivity measurement by various methods (direct and indirect, and calorimetric and radiometric) are discussed. The paper is focused on direct radiometric methods. An overview of experimental setups is provided, including the design of individual parts such as the applied reference sources of radiation, systems of sample clamping and heating, detection systems, methods for the determination of surface temperature, and procedures for emissivity evaluation.

  20. Enteric methane emissions from German pigs

    DEFF Research Database (Denmark)

    Dämmgen, Ulrich; Schulz, Joachim; Klausing, Heinrich Kleine;

    2012-01-01

    Methane emissions from enteric fermentation of pigs are object of emission reporting. Hitherto they were treated as part of the energy balance of pigs, in accordance with IPCC guidance documents. They were calculated from the gross energy intake rate and a constant methane conversion ratio....... Meanwhile numerous experimental data on methane emissions from enteric fermentation is available in Germany and abroad; the results are compiled in this work. These results also allow for a description of transformation processes in the hind gut and a subsequent establishment of models that relate emissions...

  1. Biochar and soil nitrous oxide emissions

    Directory of Open Access Journals (Sweden)

    Carlos Francisco Brazão Vieira Alho

    2012-05-01

    Full Text Available The objective of this work was to evaluate the effect of biochar application on soil nitrous oxide emissions. The experiment was carried out in pots under greenhouse conditions. Four levels of ground commercial charcoal of 2 mm (biochar were evaluated in a sandy Albaqualf (90% of sand: 0, 3, 6, and 9 Mg ha-1. All treatments received 100 kg ha-1 of N as urea. A cubic effect of biochar levels was observed on the N2O emissions. Biochar doses above 5 Mg ha-1 started to mitigate the emissions in the evaluated soil. However, lower doses promote the emissions.

  2. Emissions control for ground power gas turbines

    Science.gov (United States)

    Rudney, R. A.; Priem, R. J.; Juhasz, A. J.; Anderson, D. N.; Mroz, T. S.; Mularz, E. J.

    1977-01-01

    The similarities and differences of emissions reduction technology for aircraft and ground power gas turbines is described. The capability of this technology to reduce ground power emissions to meet existing and proposed emissions standards is presented and discussed. Those areas where the developing aircraft gas turbine technology may have direct application to ground power and those areas where the needed technology may be unique to the ground power mission are pointed out. Emissions reduction technology varying from simple combustor modifications to the use of advanced combustor concepts, such as catalysis, is described and discussed.

  3. Cutting US sulphur emissions cost-effectively

    Energy Technology Data Exchange (ETDEWEB)

    Saile, Sharon [US Environmental Protection Agency, Washington, DC (United States)

    1999-09-01

    The requirements of the US Clean Air Act of 1990 are outlined and implementation steps summarised under the following headings: national emission limits; emission limits set for utility units; collection, verification and publication of emissions data; penalties for excess emissions. Achievements under the Act and figures for the cost of compliance are briefly summarised. The US Government Accounting Office has estimated that the SO2 reduction program will cost $2 billion dollars annually; $3 billion lower than initially estimated. There has also been a substantial drop in the allowance price. (UK)

  4. OPIC Greenhouse Gas Emissions Analysis Details

    Data.gov (United States)

    Overseas Private Investment Corporation — Summary project inventory with independent analysis to quantify the greenhouse gas ("GHG") emissions directly attributable to projects to which the Overseas Private...

  5. Survey of emissivity measurement by radiometric methods.

    Science.gov (United States)

    Honner, M; Honnerová, P

    2015-02-01

    A survey of the state of the art in the field of spectral directional emissivity measurements by using radiometric methods is presented. Individual quantity types such as spectral, band, or total emissivity are defined. Principles of emissivity measurement by various methods (direct and indirect, and calorimetric and radiometric) are discussed. The paper is focused on direct radiometric methods. An overview of experimental setups is provided, including the design of individual parts such as the applied reference sources of radiation, systems of sample clamping and heating, detection systems, methods for the determination of surface temperature, and procedures for emissivity evaluation. PMID:25967774

  6. Laser emission spectrography of rare earth elements

    International Nuclear Information System (INIS)

    Emission spectrography of rare earth elements in several matrixes is studied by using a Q-switched ruby laser as an exciting source for macro analysis. The emission intensities of rare earth elements are considerably affected by the matrixes. The emission intensities of rare earth elements are most intense in sodium chloride matrix, but fairly suppressed in sodium sulfate matrix. Scandium, yttrium, europium, and ytterbium, in sodium chloride matrix are detected down to concentrations of ppm order with one laser shot. The emission intensities of rare earth elements in refractory oxides, such as aluminum oxide or rate earth oxides, are about two orders of magnitude less than those in sodium chloride matrix. (auth.)

  7. Biophoton emission induced by heat shock.

    Directory of Open Access Journals (Sweden)

    Katsuhiro Kobayashi

    Full Text Available Ultraweak biophoton emission originates from the generation of reactive oxygen species (ROS that are produced in mitochondria as by-products of cellular respiration. In healthy cells, the concentration of ROS is minimized by a system of biological antioxidants. However, heat shock changes the equilibrium between oxidative stress and antioxidant activity, that is, a rapid rise in temperature induces biophoton emission from ROS. Although the rate and intensity of biophoton emission was observed to increase in response to elevated temperatures, pretreatment at lower high temperatures inhibited photon emission at higher temperatures. Biophoton measurements are useful for observing and evaluating heat shock.

  8. Mercury emission from crematories in Japan

    Science.gov (United States)

    Takaoka, M.; Oshita, K.; Takeda, N.; Morisawa, S.

    2010-04-01

    Anthropogenic sources of mercury emissions have a significant impact on global pollution. Therefore, finding uncharacterised sources and assessing the emissions from these sources are important. However, limited data are available worldwide on mercury emissions from crematories. In Japan, 99.9% of dead bodies are cremated, which is the highest percentage in the world, and more than 1600 crematories are in operation. We thus focused on emissions from crematories in Japan. The number of targeted facilities was seven, and we used continuous emission monitoring to measure the mercury concentrations and investigate mercury behaviour. The total mercury concentrations in stack gases were a few μg/Nm3 (normal cubic meters). Considering the time profile of mercury and its species in cremations, the findings confirmed that the mercury in stack gas originated from dental amalgam. The amount of mercury emissions was calculated using the total concentration and gas flow rate. Furthermore, the annual amount of mercury emission from crematories in Japan was estimated by using the total number of corpses. The emission amount was considerably lower than that estimated in the United Kingdom. From statistical analyses on population demographics and measurements, future total emissions from crematories were also predicted. As a result, the amount of mercury emitted by crematories will likely increase by 2.6-fold from 2007 to 2037.

  9. Mercury emission from crematories in Japan

    Directory of Open Access Journals (Sweden)

    M. Takaoka

    2010-04-01

    Full Text Available Anthropogenic sources of mercury emissions have a significant impact on global pollution. Therefore, finding uncharacterised sources and assessing the emissions from these sources are important. However, limited data are available worldwide on mercury emissions from crematories. In Japan, 99.9% of dead bodies are cremated, which is the highest percentage in the world, and more than 1600 crematories are in operation. We thus focused on emissions from crematories in Japan. The number of targeted facilities was seven, and we used continuous emission monitoring to measure the mercury concentrations and investigate mercury behaviour. The total mercury concentrations in stack gases were a few μg/Nm3 (normal cubic meters. Considering the time profile of mercury and its species in cremations, the findings confirmed that the mercury in stack gas originated from dental amalgam. The amount of mercury emissions was calculated using the total concentration and gas flow rate. Furthermore, the annual amount of mercury emission from crematories in Japan was estimated by using the total number of corpses. The emission amount was considerably lower than that estimated in the United Kingdom. From statistical analyses on population demographics and measurements, future total emissions from crematories were also predicted. As a result, the amount of mercury emitted by crematories will likely increase by 2.6-fold from 2007 to 2037.

  10. Exhaust emissions from high speed passenger ferries

    Science.gov (United States)

    Cooper, D. A.

    Exhaust emission measurements have been carried out on-board three high-speed passenger ferries (A, B and C) during normal service routes. Ship A was powered by conventional, medium-speed, marine diesel engines, Ship B by gas turbine engines and Ship C conventional, medium-speed, marine diesel engines equipped with selective catalytic reduction (SCR) systems for NO x abatement. All ships had similar auxiliary engines (marine diesels) for generating electric power on-board. Real-world emission factors of NOx, SO2, CO, CO 2, NMVOC, CH4, N2O, NH3, PM and PAH at steady-state engine loads and for complete voyages were determined together with an estimate of annual emissions. In general, Ship B using gas turbines showed favourable NO x, PM and PAH emissions but at the expense of higher fuel consumption and CO 2 emissions. Ship C with the SCR had the lowest NO x emissions but highest NH 3 emissions especially during harbour approaches and stops. The greatest PM and PAH specific emissions were measured from auxiliary engines operating at low engine loads during harbour stops. Since all ships used a low-sulphur gas oil, SO 2 emissions were relatively low in all cases.

  11. Single photon emission computerized tomography

    International Nuclear Information System (INIS)

    In this thesis two single-photon emission tomographic techniques are presented: (a) longitudinal tomography with a rotating slanting-hole collimator, and (b) transversal tomography with a rotating gamma camera. These methods overcome the disadvantages of conventional scintigraphy. Both detection systems and the image construction methods are explained and comparisons with conventional scintigraphy are drawn. One chapter is dedicated to the determination of system parameters like spatial resolution, contrast, detector uniformity, and size of the object, by phantom studies. In separate chapters the results are presented of detection of tumors and metastases in the liver and the liver hilus; skeletal diseases; various pathological aberrations of the brain; and myocardial perfusion. The possible use of these two ect's for other organs and body areas is discussed in the last chapter. (Auth.)

  12. Exhaust emission control and diagnostics

    Science.gov (United States)

    Mazur, Christopher John; Upadhyay, Devesh

    2006-11-14

    A diesel engine emission control system uses an upstream oxidation catalyst and a downstream SCR catalyst to reduce NOx in a lean exhaust gas environment. The engine and upstream oxidation catalyst are configured to provide approximately a 1:1 ratio of NO to NO2 entering the downstream catalyst. In this way, the downstream catalyst is insensitive to sulfur contamination, and also has improved overall catalyst NOx conversion efficiency. Degradation of the system is determined when the ratio provided is no longer near the desired 1:1 ratio. This condition is detected using measurements of engine operating conditions such as from a NOx sensor located downstream of the catalysts. Finally, control action to adjust an injected amount of reductant in the exhaust gas based on the actual NO to NO2 ratio upstream of the SCR catalyst and downstream of the oxidation catalyst.

  13. Decametric radio emission of Jupiter

    International Nuclear Information System (INIS)

    New results of high-sensitivity observations of the S-components in Jupiter's sporadic radio emission obtained with the UTR-2 telescope in the frequency range of 10 to 23 MHz are discussed. The correlation of S-bursts parameters (power, frequency, drift rate, upper frequencies), with magnetic field strength, angular and linear velocities of Io flux tube foot (IFTF) are studied vs Io flux tube joviographic meridian longitudes. The conclusion made that sources of the S-burst storms are located in the Southern polar region of Jupiter. We purpose that the transverse velocity of southern end of Io's flux tube with respect to magnetospheric plasma is among the principal factors controlling the generation and parameters of S-burst stroms. It has been detected that maxima of power, upper frequencies and drift rates are delayed by some 40 min against the longitudes of highest IFTF angular and linear velocities

  14. Radio emission from Supernova Remnants

    CERN Document Server

    Dubner, Gloria

    2015-01-01

    The explosion of a supernova releases almost instantaneously about 10^51 ergs of mechanic energy, changing irreversibly the physical and chemical properties of large regions in the galaxies. The stellar ejecta, the nebula resulting from the powerful shock waves, and sometimes a compact stellar remnant, constitute a supernova remnant (SNR). They can radiate their energy across the whole electromagnetic spectrum, but the great majority are radio sources. Almost 70 years after the first detection of radio emission coming from a SNR, great progress has been achieved in the comprehension of their physical characteristics and evolution. We review the present knowledge of different aspects of radio remnants, focusing on sources of the Milky Way and the Magellanic Clouds, where the SNRs can be spatially resolved. We present a brief overview of theoretical background, analyze morphology and polarization properties, and review and critical discuss different methods applied to determine the radio spectrum and distances....

  15. Instrumentation in positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a three-dimensional medical imaging technique that noninvasively measures the concentration of radiopharmaceuticals in the body that are labeled with positron emitters. With the proper compounds, PET can be used to measure metabolism, blood flow, or other physiological values in vivo. The technique is based on the physics of positron annihilation and detection and the mathematical formulations developed for x-ray computed tomography. Modern PET systems can provide three-dimensional images of the brain, the heart, and other internal organs with resolutions on the order of 4 to 6 mm. With the selectivity provided by a choice of injected compounds, PET has the power to provide unique diagnostic information that is not available with any other imaging modality. This is the first five reports on the nature and uses of PET that have been prepared for the American Medical Association's Council on Scientific Affairs by an authoritative panel

  16. Emissivity Measurement of Semitransparent Textiles

    Directory of Open Access Journals (Sweden)

    P. Bison

    2012-01-01

    Full Text Available In the textiles production industry it is more and more common to advertise new textiles, especially for sportswear, by claiming their ability to emit IR radiation in the long wave band at a higher degree with respect to normal clothes, that is highly beneficial to improve sporting performances. Three textiles are compared, one normal and two “special,” with Ag+ ions and carbon powder added, with different colors. The emissivity of the textiles has been measured to determine if it is increased in the “special” textiles with respect to the normal one. No substantial increase has been noticed. Nonetheless, the test implied some nonstandard procedures due to the semitransparent nature of the textiles, in comparison with the normal procedure that is commonly used on opaque surfaces.

  17. Radio Emission from Globular Clusters

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Radio emission of globular clusters is studied by analyzing the VLA radio survey data of the NVSS and FIRST. We find that 13 clusters have radio sources within their half-mass radii of clusters. Sources detected previously in NGC 7078and NGC 6440 are identified. Pulsars in NGC 6121, NGC 6440 and NGC 7078cannot be detected because of the insufficient survey sensitivity and resolution.There may be a pulsar in the core of Terzan 1. The nature of the extended radio source near the core of NGC 6440 remains unclear. In the core of a globular cluster,there may be many neutron stars or an intermediate mass black hole, but this cannot be clarified with the current radio observations.

  18. Positron emission tomography basic sciences

    CERN Document Server

    Townsend, D W; Valk, P E; Maisey, M N

    2003-01-01

    Essential for students, science and medical graduates who want to understand the basic science of Positron Emission Tomography (PET), this book describes the physics, chemistry, technology and overview of the clinical uses behind the science of PET and the imaging techniques it uses. In recent years, PET has moved from high-end research imaging tool used by the highly specialized to an essential component of clinical evaluation in the clinic, especially in cancer management. Previously being the realm of scientists, this book explains PET instrumentation, radiochemistry, PET data acquisition and image formation, integration of structural and functional images, radiation dosimetry and protection, and applications in dedicated areas such as drug development, oncology, and gene expression imaging. The technologist, the science, engineering or chemistry graduate seeking further detailed information about PET, or the medical advanced trainee wishing to gain insight into the basic science of PET will find this book...

  19. Modeling molecular hyperfine line emission

    CERN Document Server

    Keto, Eric

    2010-01-01

    In this paper we discuss two approximate methods previously suggested for modeling hyperfine spectral line emission for molecules whose collisional transitions rates between hyperfine levels are unknown. Hyperfine structure is seen in the rotational spectra of many commonly observed molecules such as HCN, HNC, NH3, N2H+, and C17O. The intensities of these spectral lines can be modeled by numerical techniques such as Lambda-iteration that alternately solve the equations of statistical equilibrium and the equation of radiative transfer. However, these calculations require knowledge of both the radiative and collisional rates for all transitions. For most commonly observed radio frequency spectral lines, only the net collisional rates between rotational levels are known. For such cases, two approximate methods have been suggested. The first method, hyperfine statistical equilibrium (HSE), distributes the hyperfine level populations according to their statistical weight, but allows the population of the rotationa...

  20. Kiln emissions and potters' exposures.

    Science.gov (United States)

    Hirtle, B; Teschke, K; van Netten, C; Brauer, M

    1998-10-01

    Some ten thousand British Columbia potters work in small private studios, cooperative facilities, educational institutions, or recreation centers. There has been considerable concern that this diffuse, largely unregulated activity may involve exposures to unacceptable levels of kiln emissions. Pottery kiln emissions were measured at 50 sites--10 from each of 5 categories: professional studios, recreation centers, elementary schools, secondary schools, and colleges. Area monitoring was done 76 cm from firing kilns and 1.6 m above the floor to assess breathing zone concentrations of nitrogen dioxide, carbon monoxide, sulfur dioxide, fluorides, aldehydes, aluminum, antimony, arsenic, barium, beryllium, boron, cadmium, chromium, cobalt, copper, gold, iron, lead, lithium, magnesium, manganese, mercury, nickel, selenium, silver, vanadium, and zinc. Personal exposures to the same metals were measured at 24 sites. Almost all measured values were well below permissible concentrations for British Columbia work sites and American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) with the following two exceptions. A single firing duration (495 minute) acrolein measurement adjacent to an electric kiln (0.109 ppm) exceeded these guidelines. One 15-minute sulfur dioxide measurement collected adjacent to a gas kiln (5.7 ppm) exceeded the ACGIH short-term exposure limit. The fact that concentrations in small, ventilated kiln rooms ranked among the highest measured gives rise to concern that unacceptable levels of contamination may exist where small kiln rooms remain unventilated. Custom designed exhaust hoods and industrial heating, ventilating, and air-conditioning systems were the most effective ventilation strategies. Passive diffusion and wall/window fans were least effective. PMID:9794068