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Liu, Kaiyu. "Upper Cretaceous sequence stratigraphy, sea-level fluctuations and Oceanic Anoxic Events 2 and 3, Northeastern Gulf of Mexico." Stratigraphy 2, no. 2 (2005): 147–66. http://dx.doi.org/10.29041/strat.02.2.03.
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The relationship between Oceanic Anoxic Events (OAEs) and sea-level fluctuations can be determined by placing OAE sediments into an integrated sequence stratigraphic framework based on biostratigraphic age control, and regional seismic and well-log data. Two Upper Cretaceous black shale units in the northeastern Gulf of Mexico area, the Marine Tuscaloosa shale and the downdip Eutaw shale, are interpreted to be deposited in association with Late Cretaceous OAE 2 (Cenomanian–Turonian boundary event) and OAE3 (late Coniacian – early Santonian). TheMarine Tuscaloosa shale accumulated during the maximum flooding event of the UKI sequence (middle Cenomanian to upper Turonian); and the downdip Eutaw shale accumulated as the early transgressive systems tract of theUKII sequence (upperConiacian to upperCampanian). These OAEs can be classified into two categories according to their sequence stratigraphic positions. Type I OAE (e.g., OAE 2) occurred during a maximum flooding event, and the black shale associated with this type of event was deposited in an open shelf environment. Type II OAE (e.g., OAE 3) occurred during the early phase of a marine transgression that resulted in the inundation of large coastal areas and the formation of lagoons and estuaries, which acted to trap large quantities of terrestrial organic carbon.
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Ismail, Ahmed Aly. "A New Epistemological Insight of the Coniacian-Santonian Oceanic Anoxic Event (OAE3)." American Journal of BioScience 12, no. 1 (2024): 22–34. http://dx.doi.org/10.11648/j.ajbio.20241201.14.
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Eighteen planktic and eleven benthic foraminiferal species were recorded from the dark grey to black shale facies of the Matulla Formation in Abu Zeneima area, West-Central Sinai, Egypt. The faunal assemblage is dominated by cosmopolitan whiteinellids, marginotruncanids, Dicarinellids, Contusotruncanids and Heterohelicids. The planktic species with high taxonomic diversity were used to zone the Coniacian and Santonian stages, as well as define the Coniacian/ Santonian boundary, while benthic foraminifera is of minor contribution in age assignment. The stratigraphic analysis of the relations and ranges of these fauna led to the recognition of five biozones<i>; Dicarinella primitiva</i> or <i>Huberella huberi</i> or <i>Marginotruncana</i> <i>sinuosa</i> for the Coniacian, while <i>Dicarinella concavata</i> and <i>Dicarinella asymetrica</i> for the Santonian. Also, the Coniacian/Santonian boundary was delineated, considering the appearance of <i>Dicarinella</i> <i>concavata</i> and disappearance of <i>Huberella huberi</i>, as well as the<i> </i>increase of Marginotruncanids (<i>M. renzi, M. sigali, M. marginata, M. pseudolinneiana</i>….etc.). Furthermore, the black shales found in the middle part of the Matulla Formation were attributed to the Coniacian-Santonian Oceanic Anoxic Event (OAE3). The occurrence of black shales with planktic foraminifera during the Coniacian–Santonian interval in several countries belonging to five continents, was the main impetus to render this event a global event.
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Topper, R. P. M., J. Trabucho Alexandre, E. Tuenter, and P. Th Meijer. "A regional ocean circulation model for the mid-Cretaceous North Atlantic Basin: implications for black shale formation." Climate of the Past 7, no. 1 (2011): 277–97. http://dx.doi.org/10.5194/cp-7-277-2011.
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Abstract. High concentrations of organic matter accumulated in marine sediments during Oceanic Anoxic Events (OAEs) in the Cretaceous. Model studies examining these events invariably make use of global ocean circulation models. In this study, a regional model for the North Atlantic Basin during OAE2 at the Cenomanian-Turonian boundary has been developed. A first order check of the results has been performed by comparison with the results of a recent global Cenomanian CCSM3 run, from which boundary and initial conditions were obtained. The regional model is able to maintain tracer patterns and to produce velocity patterns similar to the global model. The sensitivity of the basin tracer and circulation patterns to changes in the geometry of the connections with the global ocean is examined with three experiments with different bathymetries near the sponges. Different geometries turn out to have little effect on tracer distribution, but do affect circulation and upwelling patterns. The regional model is also used to test the hypothesis that ocean circulation may have been behind the deposition of black shales during OAEs. Three scenarios are tested which are thought to represent pre-OAE, OAE and post-OAE situations. Model results confirm that Pacific intermediate inflow together with coastal upwelling could have enhanced primary production during OAE2. A low sea level in the pre-OAE scenario could have inhibited large scale black shale formation, as could have the opening of the Equatorial Atlantic Seaway in the post-OAE scenario.
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Topper, R. P. M., J. Trabucho Alexandre, E. Tuenter, and P. Th Meijer. "A regional ocean circulation model for the mid-Cretaceous North Atlantic Basin: implications for black shale formation." Climate of the Past Discussions 6, no. 5 (2010): 2371–421. http://dx.doi.org/10.5194/cpd-6-2371-2010.
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Abstract. High concentrations of organic matter accumulated in marine sediments during Oceanic Anoxic Events (OAEs) in the Cretaceous. Model studies examining these events invariably make use of global ocean circulation models. In this study, a regional model for the North Atlantic Basin during OAE2 at the Cenomanian-Turonian boundary is developed. A first order check of the results is performed by comparison with the results of a recent global Cenomanian CCSM3 run from which boundary and initial conditions were obtained. The regional model is able to maintain tracer patterns and to produce velocity patterns similar to the global model. The sensitivity of basin tracer and circulation patterns to changes in the geometry of the connections with the global ocean is examined with three experiments with different bathymetries near the sponges. Different geometries turn out to have little effect on tracer distribution, but do affect circulation and upwelling patterns. The regional model is also used to test the hypothesis that ocean circulation may be behind the deposition of black shales during OAEs. Three scenarios are tested which are thought to represent pre-OAE, OAE and post-OAE situations. Model results confirm that Pacific intermediate inflow together with coastal upwelling can have enhanced primary production during OAE2. A low sea level in the pre-OAE scenario can inhibit large scale black shale formation, as can the opening of the Equatorial Atlantic Seaway in the post-OAE scenario.
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Freymueller, Nicholas A., Jason R. Moore, and Corinne E. Myers. "An analysis of the impacts of Cretaceous oceanic anoxic events on global molluscan diversity dynamics." Paleobiology 45, no. 02 (2019): 280–95. http://dx.doi.org/10.1017/pab.2019.10.
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AbstractOceanic anoxic events (OAEs) are contemporaneous with 11 of the 18 largest Phanerozoic extinction events, but the magnitude and selectivity of their paleoecological impact remains disputed. OAEs are associated with abrupt, rapid warming and increased CO2flux to the atmosphere; thus, insights from this study may clarify the impact of current anthropogenic climate change on the biosphere. We investigated the influence of the Late Cretaceous Bonarelli event (OAE2; Cenomanian/Turonian stage boundary; ~94 Ma) on generic- and species-level molluscan diversity, extinction rates, and ecological turnover. Cenomanian/Turonian results were compared with changes across all Cretaceous stage boundaries, some of which are coincident with less severe OAEs. We found increased generic turnover, but not species-level turnover, associated with several Cretaceous OAEs. The absence of a species-level pattern may reflect species occurrence data that are too temporally coarse to robustly detect patterns. Five hypotheses of ecological selectivity relating anoxia to survivorship were tested across stage boundaries with respect to faunality, mobility, and diet using generalized linear models. Interestingly, benthic taxa were consistently selected against throughout the Cretaceous regardless of the presence or absence of OAEs. These results suggest that: (1) the Cenomanian/Turonian boundary (OAE2) was associated with a decline in molluscan diversity and increase in extinction rate that were significantly more severe than Cretaceous background levels; and (2) no differential ecological selectivity was associated with OAE-related diversity declines among the variables tested here.
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Aradhana, Aparna, Gadadhar Sarangi, Prasant Saboth, and Radha Tripathy. "Assessment of Hearing Impairment in NICU Graduates by Otoacoustic Emission and Brainstem Evoked Response Audiometry Tests." Journal of Neonatology 34, no. 3 (2020): 109–17. http://dx.doi.org/10.1177/0973217920951878.
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Objectives: To find out the incidence of hearing impairment in Neonatal Intensive Care Unit (NICU)-admitted newborns and to correlate between several risk factors. Design: Prospective observational study. Setting: In a tertiary teaching hospital of Odisha between October 2014 and October 2016. Study population: 100 newborns delivered in the institution and admitted in NICU with usual indications and risk factors that underwent otoacoustic emission 1 and 2 (OAE1, OAE2) and Brainstem Evoked Response Audiometry (BERA). Results: 84 babies in OAE1 and 86 babies in OAE2 got “pass” results. In BERA test, 92 babies got normal waveform. 7 (13.7%) of 51 premature babies, 5 (38.5%) of 13 very low birth weight babies, 7 (17.5%) of 40 babies receiving ototoxic medication for >5 days, 7 (31.8%) of 22 babies with hyperbilirubinemia, 6 (42.9%) of 14 babies with sepsis, 5 (20%) of 20 babies with birth asphyxia, 3 (60%) of 5 babies under mechanical ventilation for >5 days, 1 baby with ear abnormality, and 1 (50%) out of 2 babies with congenital infections had hearing impairment and statistically significant association with abnormal OAE and BERA test. Conclusion: There is high incidence of hearing loss in NICU-admitted newborns. OAE and BERA both should be performed for complete evaluation of hearing. Important risk factors are elaborated. Predischarge hearing assessment in NICU is most important.
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Karakitsios, V., H. Tsikos, K. Agiadi - Katsiaouni, S. Dermitzoglou, and E. Chatziharalambous. "THE USE OF CARBON AND OXYGEN STABLE ISOTOPES IN THE STUDY OF GLOBAL PALAEOCEANOGRAPHIC CHANGES: EXAMPLES FROM THE CRETACEOUS SEDIMENT ROCKS OF WESTERN GREECE." Bulletin of the Geological Society of Greece 39, no. 1 (2006): 64. http://dx.doi.org/10.12681/bgsg.18445.
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In the present paper we examine the use of carbon and oxygen stable isotopes in the study of global palaeoceanographic changes, with special reference to the oceanic anoxic events (OAEs). The analysis of stable isotopes was applied to the examination of Cretaceous sediments from the Ionian and Pindos zones of Western Greece. In the Ionian zone the carbon and oxygen stable isotopes, combined with biostratigraphic data, record the palaeoenvironmental change corresponding to the anoxic events Bonarelli (Cenomanian/Turonian, OAE2) and Paquier (Lower Albian, OAE1b). In the Pindos zone, within the Cretaceous sediments, we observed two organic-carbon-rich levels. According to the biostratigraphic and isotopie analysis, the first level corresponds to an OAE of Santonian age. This local oceanic anoxic event is described for the first time. The second level, Aptian - Albian age, possibly correlates to either the Paquier event (OAE 1b) or the Selli event (OAE 1a), which in Greece were until now known only in the Ionian zone.
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Machado, M. C., F. Chemale, K. Kawashita, O. Rey, and C. A. V. Moura. "Isotope studies of carbonate rocks of La Luna Formation (Venezuela) to constrain the oceanic anoxic event 3 (OAE3)." Journal of South American Earth Sciences 72 (December 2016): 38–48. http://dx.doi.org/10.1016/j.jsames.2016.07.001.
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Lowery, Christopher M., R. Mark Leckie, and Bradley B. Sageman. "Micropaleontological evidence for redox changes in the OAE3 interval of the US Western Interior: Global vs. local processes." Cretaceous Research 69 (January 2017): 34–48. http://dx.doi.org/10.1016/j.cretres.2016.08.011.
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Abdala, Carolina, Tricia Benjamin, Samantha Stiepan, Ping Luo, and Christopher A. Shera. "Detection of mild sensory hearing loss using a joint reflection-distortion otoacoustic emission profile." Journal of the Acoustical Society of America 156, no. 4 (2024): 2220–36. http://dx.doi.org/10.1121/10.0030399.
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Measuring and analyzing both nonlinear-distortion and linear-reflection otoacoustic emissions (OAEs) combined creates what we have termed a “joint-OAE profile.” Here, we test whether these two classes of emissions have different sensitivities to hearing loss and whether our joint-OAE profile can detect mild-moderate hearing loss better than conventional OAE protocols have. 2f1-f2 distortion-product OAEs and stimulus-frequency OAEs were evoked with rapidly sweeping tones in 300 normal and impaired ears. Metrics included OAE amplitude for fixed-level stimuli as well as slope and compression features derived from OAE input/output functions. Results show that mild-moderate hearing loss impacts distortion and reflection emissions differently. Clinical decision theory was applied using OAE metrics to classify all ears as either normal-hearing or hearing-impaired. Our best OAE classifiers achieved 90% or better hit rates (with false positive rates of 5%–10%) for mild hearing loss, across a nearly five-octave range. In summary, results suggest that distortion and reflection emissions have distinct sensitivities to hearing loss, which supports the use of a joint-OAE approach for diagnosis. Results also indicate that analyzing both reflection and distortion OAEs together to detect mild hearing loss produces outstanding accuracy across the frequency range, exceeding that achieved by conventional OAE protocols.
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Hauser, Samantha, Michael G. Heinz, and Hari Bharadwaj. "Cross-species characterization of joint otoacoustic emission profiles in sensorineural hearing loss." Journal of the Acoustical Society of America 153, no. 3_supplement (2023): A161. http://dx.doi.org/10.1121/10.0018513.
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Current clinical assessment of otoacoustic emissions (OAEs) is typically limited to presence or absence of emissions to detect hearing loss, but recent work suggests advanced analyses and data collection methods have the potential to improve the diagnostic utility of OAEs. OAEs arise from two distinct mechanisms, nonlinear distortion and linear reflection, which are both sensitive to the health of outer hair cells but may reflect separate aspects of cochlear mechanical function. Joint distortion-reflection OAE profiles offer a non-invasive characterization of peripheral auditory physiology and dysfunction (Abdala and Kalluri, 2017). In this study, swept-tone distortion-product OAEs were separated into distortion and reflection components. Swept-tone stimulus-frequency OAEs, reflection-type emissions, were measured using a suppressor paradigm. Joint OAE profiles will be estimated for multiple pre-clinical chinchilla models of sensorineural hearing loss (SNHL) and in humans with either normal hearing or sensorineural hearing loss. In chinchillas, we expect SNHL models with distinct profiles of cochlear damage to yield separable joint OAE profiles. Findings in chinchillas will provide mechanistic insight into OAE profile clusters in humans. These data test the sensitivity of joint OAE profiles to specific cochlear dysfunctions and contribute to development of precision diagnostics for SNHL.
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Mishra, Srikanta K., and Michelle Hernandez. "Temporal Features of Otoacoustic Emissions." Perspectives of the ASHA Special Interest Groups 2, no. 2 (2017): 169–75. http://dx.doi.org/10.1044/persp2.sig2.169.
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The true power of otoacoustic emissions (OAEs) continues to be explored. OAE spectral characteristics are typically studied in research and applied in the clinic. However, OAE temporal aspects are relatively underexplored. Not using temporal features is similar to ignoring nearly half of the information that OAEs provide. Besides providing information related to the generation of OAEs and cochlear mechanics, the temporal characteristics have important clinical implications, such as for assessing frequency selectivity, characterizing the strength of the efferent auditory system. This review provides a general synopsis of the fundamental principles of OAE delay and latency and discusses some of the relevant applications in probing the strength of the efferent neural pathway and frequency selectivity. It is expected that the reader will gain an overview of the implications of the latency or phase behavior of OAEs.
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Singh, Abha, and Prem Raj Uddandam. "Mesozoic Oceanic Anoxic Events: Records from India and future scope." Journal of Palaeosciences 73, no. 2 (2024): 99–118. https://doi.org/10.54991/jop.2024.1888.
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This paper presents a review of the Mesozoic Oceanic Anoxic Event (OAE) studies, carried out from India. It also provides a summary of the researches pursued on biostratigraphic, isotopic, and organic geochemical proxies for establishing Oceanic Anoxic Events (OAEs) from the Mesozoic sedimentary sequences of the Indian Subcontinent. From Indian sedimentary basins, studies are available on OAE-1a, OAE-1b, OAE-1d, OAE-2, and OAE-3. From the Cauvery Basin records of OAE-1b, OAE-1d, OAE-2, and OAE-3 are available. From the Spiti Valley records are present on OAE-2 (Chikkim Formation) only, and the possibilities of late Valanginian Weissert Event (W-OAE), latest Hauterivian Faraoni Event (F-OAE) and OAE-1a are expected to be present in Giumal Formation. Nonetheless, the Black shale from Rudramata Shale, Jhuran Formation indicate possible late Jurassic OAE, based on the character of sedimentary facies and organic geochemical results. There is also, possibility of OAE-1a and OAE-1b in the Ukra and Upper member of the Bhuj Formation. This paper aims to provide a comprehensive introduction on global and regional OAEs records from the Indian subcontinent and a significant window on available knowledge of these events in India and supply significant attention for the future research possibilities from the Indian landmass.
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Rey, O., J. A. Simo (Toni), and M. A. Lorente. "A record of long- and short-term environmental and climatic change during OAE3: La Luna Formation, Late Cretaceous (Santonian–early Campanian), Venezuela." Sedimentary Geology 170, no. 1-2 (2004): 85–105. http://dx.doi.org/10.1016/j.sedgeo.2004.06.006.
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Beil, Sebastian, Wolfgang Kuhnt, Ann Holbourn, et al. "Cretaceous oceanic anoxic events prolonged by phosphorus cycle feedbacks." Climate of the Past 16, no. 2 (2020): 757–82. http://dx.doi.org/10.5194/cp-16-757-2020.
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Abstract. Oceanic anoxic events (OAEs) document major perturbations of the global carbon cycle with repercussions for the Earth's climate and ocean circulation that are relevant to understanding future climate trends. Here, we compare the onset and development of Cretaceous OAE1a and OAE2 in two drill cores with unusually high sedimentation rates from the Vocontian Basin (southern France) and Tarfaya Basin (southern Morocco). OAE1a and OAE2 exhibit remarkable similarities in the evolution of their carbon isotope (δ13C) records, with long-lasting negative excursions preceding the onset of the main positive excursions, supporting the view that both OAEs were triggered by massive emissions of volcanic CO2 into the atmosphere. However, there are substantial differences, notably in the durations of individual phases within the δ13C positive excursions of both OAEs. Based on analysis of cyclic sediment variations, we estimate the duration of individual phases within OAE1a and OAE2. We identify (1) a precursor phase (negative excursion) lasting ∼430 kyr for OAE1a and ∼130 kyr for OAE2, (2) an onset phase of ∼390 and ∼70 kyr, (3) a peak phase of ∼600 and ∼90 kyr, (4) a plateau phase of ∼1340 and ∼200 kyr, and (5) a recovery phase of ∼380 and ∼440 kyr. The total duration of the positive δ13C excursion is estimated at 2700 kyr for OAE1a and 790 kyr for OAE2, and that of the main carbon accumulation phase is estimated at 980 and 180 kyr. The long-lasting peak, plateau and recovery phases imply fundamental changes in global nutrient cycles either (1) by submarine basalt–seawater interactions, (2) through excess nutrient inputs to the oceans by increasing continental weathering and river discharge, or (3) through nutrient recycling from the marine sediment reservoir. We investigated the role of phosphorus in the development of carbon accumulation by analysing phosphorus speciation across OAE2 and the mid-Cenomanian Event (MCE) in the Tarfaya Basin. The ratios of organic carbon and total nitrogen to reactive phosphorus (Corg∕Preact and Ntotal∕Preact) prior to OAE2 and the MCE hover close to or below the Redfield ratio characteristic of marine organic matter. Decreases in reactive phosphorus resulting in Corg∕Preact and Ntotal∕Preact above the Redfield ratio during the later phase of OAE2 and the MCE indicate leakage from the sedimentary column into the water column under the influence of intensified and expanded oxygen minimum zones. These results suggest that a positive feedback loop, rooted in the benthic phosphorus cycle, contributed to increased marine productivity and carbon burial over an extended period of time during OAEs.
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Siedlecki, Tomasz, and Jakub Zielinski. "SPECTRAL KURTOSIS OF OTOACOUSTIC EMISSIONS USING THE HUSIMI TRANSFORM: A PILOT STUDY." Journal of Hearing Science 5, no. 4 (2015): 15–25. http://dx.doi.org/10.17430/896155.
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BackgroundTime-frequency distributions can help reveal resonant modes of OAEs. The Husimi transform is the time-frequency distribution of probability. The sound pressure probability density function for a given frequency can be derived from the Husimi transform. Using the Husimi transform as the weight function, it is possible to define the spectral kurtosis of OAEs.Material and MethodsThe Husimi transform was calculated numerically from OAE data recorded from subjects with normal hearing. We examined click-evoked OAEs (CEOAEs) and tone-burst-evoked OAEs (TBOAEs) with stimuli centered at 1, 2, and 4 kHz, and the presence of spontaneous OAEs (SOAEs) was also investigated. The aim of this study was to examine the statistical properties of otoacoustic emissions (OAEs) and relate them to resonant modes of the cochlea. Assuming that the probability of the sound pressure of an OAE at any time and frequency is given by a Husimi-type transform, we analyzed statistical features of the probability distribution, particularly spectral kurtosis.ResultsWith evoked OAEs, a minimum in kurtosis was found at frequencies close to SOAEs. With TBOAEs, three sorts of SOAEs were found: those with high positive kurtosis, those with small positive kurtosis, and those with negative kurtosis; in these cases, SOAEs appeared at the same frequency as the kurtosis minimum.ConclusionsThe kurtosis of evoked components of an OAE is strongly affected by the presence of an SOAE. The number of positive peaks and negative troughs of spectral kurtosis in a given frequency band seem to be characteristic of each subject. It is suggested that a new way of distinguishing types of OAEs may involve calculating the spectral kurtosis, and this may be diagnostically useful.
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Venancio, Igor M., Thiago P. Santos, Fellippe R. A. Bione, et al. "Preservation Factors during Cretaceous Oceanic Anoxic Events in the Espírito Santo Basin, Southeast Brazil." Geosciences 12, no. 10 (2022): 351. http://dx.doi.org/10.3390/geosciences12100351.
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The oceanic anoxic events (OAEs) are characterized by enhanced accumulation of organic matter in marine sediments. However, there is still an ongoing debate regarding the interplay between production and preservation during these events. Moreover, few studies provide quantitative estimations of primary productivity and/or the amount of carbon preserved during the OAEs. Here, we used geochemical data from multiple wells located at the Espírito Santo Basin that cover the intervals of events OAE1d and OAE2 to provide quantitative estimates of preservation factors. Our results show enhanced preservation during OAEs compared to modern conditions and a stronger preservation during OAE1d compared to OAE2 in the Espírito Santo Basin. The amount of preserved carbon could reach up to 8.6% during OAE1d, depending on the productivity of the system. In addition, we show that such improvement in preservation is linked to the bottom water with low-O2 concentrations and not due to fast burial caused by high sedimentation rates. Our findings are extremally relevant for organic carbon and source rock modelling studies since model simulations need quantitative estimations.
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Lewis, James D. "Model-based prediction of otoacoustic emission level, noise level, and signal-to-noise ratio during time-synchronous averaging." Journal of the Acoustical Society of America 154, no. 2 (2023): 709–20. http://dx.doi.org/10.1121/10.0020568.
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Although averaging is effective in reducing noise, its efficiency rapidly decreases beyond several hundred averages. Depending on environmental and patient noise levels, several hundred averages may be insufficient for informed clinical decision making. The predictable nature of the otoacoustic emission (OAE) and noise during time-synchronous averaging implicates the use of predictive modeling as an alternative to increased averaging when noise is high. Click-evoked OAEs were measured in 98, normal-hearing subjects. Average OAE and noise levels were calculated for subsets of the total number of averages and then fit using variants of a power function. The accuracy of the models was quantified as the difference between the measured value and model output. Models were used to predict the OAE signal-to-noise ratio (SNR) for a criterion noise level. Based on predictions, the OAE was categorized as present or absent. Model-based decisions were compared to decisions from direct measurements. Model accuracy improved as the number of averages (and SNR in the case of OAEs) from which the model was derived increased. Model-based classifications permitted correct categorization of the OAE status from fewer averages than measurement-based classifications. Furthermore, model-based predictions resulted in fewer false positives (i.e., absent OAE despite normal hearing).
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Bower, Charles M., and Patti F. Martin. "Universal Pediatric Hearing Screening." Otolaryngology–Head and Neck Surgery 112, no. 5 (1995): P149. http://dx.doi.org/10.1016/s0194-5998(05)80392-4.
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Nadon, Vincent, Annelies Bockstael, Dick Botteldooren, and Jérémie Voix. "Field Monitoring of Otoacoustic Emissions During Noise Exposure: Pilot Study in Controlled Environment." American Journal of Audiology 26, no. 3S (2017): 352–68. http://dx.doi.org/10.1044/2017_aja-17-0003.
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Purpose In spite of all the efforts to implement workplace hearing conservation programs, noise-induced hearing loss remains the leading cause of disability for North American workers. Nonetheless, an individual's susceptibility to noise-induced hearing loss can be estimated by monitoring changes in hearing status in relation to the level of ambient noise exposure. The purpose of this study was to validate an approach that could improve workplace hearing conservation practices. The approach was developed using a portable and robust system designed for noisy environments and consisted of taking continuous measurements with high temporal resolution of the health status of the inner ear using otoacoustic emissions (OAEs). Method A pilot study was conducted in a laboratory, exposing human subjects to industrial noise recordings at realistic levels. In parallel, OAEs were measured periodically using the designed OAE system as well as with a commercially available OAE system, used as a reference. Results Variations in OAE levels were analyzed and discussed along with the limitations of the reference and designed systems. Conclusions This study demonstrates that the monitoring of an individual's OAEs could be useful in monitoring temporary changes in hearing status induced by exposure to ambient noise and could be considered as a new tool for effective hearing conservation programs in the workplace.
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Papsin, Emily, Adrienne L. Harrison, Mattia Carraro, and Robert V. Harrison. "Contralateral Ear Occlusion for Improving the Reliability of Otoacoustic Emission Screening Tests." International Journal of Otolaryngology 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/248187.
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Newborn hearing screening is an established healthcare standard in many countries and testing is feasible using otoacoustic emission (OAE) recording. It is well documented that OAEs can be suppressed by acoustic stimulation of the ear contralateral to the test ear. In clinical otoacoustic emission testing carried out in a sound attenuating booth, ambient noise levels are low such that the efferent system is not activated. However in newborn hearing screening, OAEs are often recorded in hospital or clinic environments, where ambient noise levels can be 60–70 dB SPL. Thus, results in the test ear can be influenced by ambient noise stimulating the opposite ear. Surprisingly, in hearing screening protocols there are no recommendations for avoiding contralateral suppression, that is, protecting the opposite ear from noise by blocking the ear canal. In the present study we have compared transient evoked and distortion product OAEs measured with and without contralateral ear plugging, in environmental settings with ambient noise levels <25 dB SPL, 45 dB SPL, and 55 dB SPL. We found out that without contralateral ear occlusion, ambient noise levels above 55 dB SPL can significantly attenuate OAE signals. We strongly suggest contralateral ear occlusion in OAE based hearing screening in noisy environments.
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Sachse, V. F., S. Heim, H. Jabour, et al. "Organic geochemical characterization of Santonian to Early Campanian organic matter-rich marls (Sondage No. 1 cores) as related to OAE3 from the Tarfaya Basin, Morocco." Marine and Petroleum Geology 56 (September 2014): 290–304. http://dx.doi.org/10.1016/j.marpetgeo.2014.02.004.
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Bergevin, Christopher, Geoffrey A. Manley, and Christine Köppl. "Salient features of otoacoustic emissions are common across tetrapod groups and suggest shared properties of generation mechanisms." Proceedings of the National Academy of Sciences 112, no. 11 (2015): 3362–67. http://dx.doi.org/10.1073/pnas.1418569112.
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Otoacoustic emissions (OAEs) are faint sounds generated by healthy inner ears that provide a window into the study of auditory mechanics. All vertebrate classes exhibit OAEs to varying degrees, yet the biophysical origins are still not well understood. Here, we analyzed both spontaneous (SOAE) and stimulus-frequency (SFOAE) otoacoustic emissions from a bird (barn owl, Tyto alba) and a lizard (green anole, Anolis carolinensis). These species possess highly disparate macromorphologies of the inner ear relative to each other and to mammals, thereby allowing for novel insights into the biomechanical mechanisms underlying OAE generation. All ears exhibited robust OAE activity, and our chief observation was that SFOAE phase accumulation between adjacent SOAE peak frequencies clustered about an integral number of cycles. Being highly similar to published results from human ears, we argue that these data indicate a common underlying generator mechanism of OAEs across all vertebrates, despite the absence of morphological features thought essential to mammalian cochlear mechanics. We suggest that otoacoustic emissions originate from phase coherence in a system of coupled oscillators, which is consistent with the notion of “coherent reflection” but does not explicitly require a mammalian-type traveling wave. Furthermore, comparison between SFOAE delays and auditory nerve fiber responses for the barn owl strengthens the notion that most OAE delay can be attributed to tuning.
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Nicholas, Sarah, Joseph Kei, Gail Woodyatt, and Bradley McPherson. "Otoacoustic Emission Findings in Rett Syndrome." Journal of the American Academy of Audiology 10, no. 08 (1999): 436–44. http://dx.doi.org/10.1055/s-0042-1748517.
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AbstractRett syndrome is a neurologic disorder affecting mainly females after a seemingly normal 6 to 18 months of life. The resulting developmental disabilities include apparent dementia and loss of acquired language, social skills, and purposeful hand use. The present investigation assessed 10 individuals with Rett syndrome and a control group matched for age and sex. The present study aimed to determine the clinical feasibility of obtaining otoacoustic emissions (OAEs) from the Rett syndrome group and to compare the characteristics of the transient evoked and distortion-product OAEs obtained from the two subject groups. Results indicated that OAE evaluation is a clinically feasible method of assessing individuals with Rett syndrome. The Rett syndrome group had less robust OAEs, especially in the higher frequencies, when compared to the control group. Seven of the Rett syndrome group were identified as having reduced or absent OAEs in at least one ear. These findings suggest a need for hearing screening at an early age and monitoring of hearing on a regular basis. Abbreviations: ABR = auditory brainstem response, DPOAEs = distortion-product otoacoustic emissions, LVR = late vertex response, MLR = middle latency response, OAE = otoacoustic emission, SNR = signal-to-noise ratio, TEOAEs = transient evoked otoacoustic emissions, VRA = visual reinforcement audiometry, WWR = whole-wave reproducibility
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Baldwin, Stacey M., Byron J. Gajewski, and Judith E. Widen. "An Evaluation of the Cross-Check Principle Using Visual Reinforcement Audiometry, Otoacoustic Emissions, and Tympanometry." Journal of the American Academy of Audiology 21, no. 03 (2010): 187–96. http://dx.doi.org/10.3766/jaaa.21.3.7.
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Background: Early intervention to reduce the effects of congenital hearing loss requires accurate description of hearing loss. In pediatric audiology, a cross-check principle is used to compare behavioral and physiological tests. Purpose: The purpose of this study was to investigate the correspondence of visual reinforcement audiometry (VRA) minimal response levels (MRLs), otoacoustic emissions (OAEs), tympanometry, and VRA test reliability to determine the odds of obtaining the expected cross-check results. We hypothesized that (1) when MRLs were within normal limits (WNL), OAEs would be present; (2) in the event of normal MRLs and absent OAEs, tympanograms would be abnormal; and (3) in the event of elevated MRLs and present OAEs, the tester's confidence in the MRLs would be judged to be only fair, rather than good. Research Design: This was a retrospective study. Study Sample: A previous study provided data from 993 infants who had diagnostic audiologic evaluations at 8–12 mo of age. Data Collection and Analysis: The data were analyzed to compare VRA MRLs with OAE signal-to-noise ratios at 1, 2, and 4 kHz. Odds ratios and 95% confidence intervals were calculated to test the three hypotheses related to the correspondence among MRLs, OAEs, tympanometry, and the reliability of MRLs. Results: The probability that OAEs would be present when MRLs were WNL varied from 12 to 26 to 1, depending on the test frequency. When OAEs were absent in the presence of normal MRLs, the odds of abnormal tympanometry varied from 5 to 10 to 1, depending on the test frequency. When MRLs were elevated (>20 dB HL), the odds suggested that examiners judged the MRLs at 1 and 2 kHz to lack reliability. Conclusion: The results suggest that the cross-check principle is effective when employing VRA, OAE, and tympanometry to rule out or determine the degree, type, and configuration of hearing loss in infants.
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Prauss, M. L. "Marine palynology of the Oceanic Anoxic Event 3 (OAE3, Coniacian – Santonian) at Tarfaya, Morocco, NW Africa – transition from preservation to production controlled accumulation of marine organic carbon." Cretaceous Research 53 (March 2015): 19–37. http://dx.doi.org/10.1016/j.cretres.2014.10.005.
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Crouwel, Femke, M. Meurs-Szojda, M. Klemt-Kropp, P. Fockens, and M. Grasman. "The diagnostic yield of open-access endoscopy of the upper gastrointestinal tract in the Netherlands." Endoscopy International Open 06, no. 04 (2018): E383—E394. http://dx.doi.org/10.1055/s-0043-123185.
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Abstract Background and study aims Since the introduction of open-access esophago-gastroduodenoscopy (OAE) there is an increase in the total number of performed OAEs whilst the frequency of clinical relevant findings has decreased. The aim of this study was to assess the appropriate use and the diagnostic yield of OAE in the Netherlands and to determine which patient variables are able to predict a malignant finding. Patients and methods A retrospective chart review of all referrals for diagnostic OAE between October 2012 and October 2016 at the Northwest Clinics was performed. The indications were recorded from the referral letter and were classified as “appropriate” or “inappropriate” according to the NHG guideline. Logistic regression was used to detect significant predictive variables for a malignancy. Results A total of 2006 patients were included, of whom 59.6 % had an ‘appropriate’ referral indication. The diagnostic yield of finding a clinical relevant finding was significantly higher for OAEs with an “appropriate” referral indication. Independent risk factors for malignancy were alarm symptoms, age and male gender with a combined AUC of 0.868. Conclusions Only 3.8 % of the malignancies would be missed by strict adherence to the guideline. This indicates that the open-access system in the Netherlands works well. Further improvement of the system can be achieved by only accepting appropriate indications for OAE and by treating patients under the age of 40 without OAE. We showed that a risk-prediction model based on the variables age, alarm symptoms and male gender is a good predictor of malignant finding.
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Gorga, Michael P., Kimberly Preissler, Jeff Simmons, Lisa Walker, and Brenda Hoover. "Some Issues Relevant to Establishing a Universal Newborn Hearing Screening Program." Journal of the American Academy of Audiology 12, no. 02 (2001): 101–12. http://dx.doi.org/10.1055/s-0042-1745585.
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AbstractThis article describes some of the factors relevant to the establishment of a universal newborn hearing screening (UNHS) program. First, the difficulty in providing precise estimates of test sensitivity and specificity are reviewed. This section is followed by hypothetical estimates of overall programmatic costs, first for a fixed number of babies to be screened and then as a function of the number of babies to be screened in a year. Included in these estimates are the costs for equipment, disposables, personnel, and follow-up testing. These estimates are provided for three different screening protocols: auditory brainstem response (ABR) alone, otoacoustic emission (OAE) alone, and OAE followed by ABR only for those babies who failed the OAE screening. If follow-up costs are not included, it is less expensive to screen newborns with OAEs compared with the other two protocols. However, once follow-up testing is included as part of the program costs and there are at least 400 births per year, procedures in which OAEs are performed first, followed by an ABR on those infants who do not pass the OAE test, result in the lowest costs. Hospitals with as few as 400 births per year should expect per-baby costs not exceeding $30, regardless of which protocol is used. For all three protocols, the unit costs decrease as the number of babies screened increases. The final section describes data from a local UNHS program in which all infants are screened first with an OAE test, followed by an ABR test on infants not passing the OAE screening. Idiosyncratic features to this program are described, including the fact that all screening tests are performed by audiologists, who are paid on a part-time basis, adding cost to the program. Even under these circumstances, the unit cost is under $30. These data lead us to conclude that all infants can be screened in a cost-effective manner. Abbreviations: ABR = auditory brainstem response, DPOAE = distortion product otoacoustic emission, NICU = neonatal intensive care unit, OAE = otoacoustic emission, UNHS = universal newborn hearing screening
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Chawla, Deeksha, Rohit Verma, Siddharth Bhargava, Manish Munjal, Anshuman Dhawan, and Udeyana Singh. "Screening for Hearing Loss in High-Risk Neonates Using Otoacoustic Emissions." Indian Journal of Otology 29, no. 2 (2023): 101–4. http://dx.doi.org/10.4103/indianjotol.indianjotol_55_23.
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Context: The development and maturation of the hearing process begin in the fetal stage and progresses up to 6 months of age. Neonatal screening is therefore an essential method to screen for hearing loss at an early age. As there is a paucity of literature on the use of otoacoustic emissions (OAEs) and brainstem evoked response (BERA) tests for screening, hence we conducted a prospective observational study to screen the high-risk neonates admitted to neonatal intensive care unit (NICU) using OAE and further BERA (wherever indicated). Aims: The primary objective was to estimate the incidence of hearing loss in high-risk neonates admitted to NICU using OAEs as a screening tool. A secondary objective was to determine the risk factors predictive of hearing impairment in these neonates. Settings and Design: It was a prospective observational study conducted in a tertiary care hospital. Subjects and Methods: The study was conducted over a period of 1 year from April 1, 2021, to March 31, 2022. Fifty neonates with high-risk factors who fulfilled the inclusion criteria were enrolled and subjected to a two-staged OAE screening test and further BERA (in neonates where overall OAE result was REFER). Statistical Analysis Used: Continuous data variables were presented as means and standard deviations. Categorical data were presented as percentages and Chi-square test was used to derive comparisons. For all statistical testing, P < 0.05 was considered statistically significant. Results: Of 50 neonates enrolled in the study, 22 (44%) passed the Stage I OAE. The remaining 28 (56%) underwent Stage II OAE, out of which 17 (34%) passed the Stage II screening. Eleven neonates with overall OAE results as REFER were taken up for BERA. Three neonates (6%) had a hearing loss on BERA while in 8 (16%) BERA was normal. The overall incidence of hearing loss was 6%. The variables with a statistically significant correlation with the results of OAE were - APGAR score and perinatal asphyxia at a low APGAR score. Conclusions: The incidence of hearing loss in this study was 6%. APGAR score and perinatal asphyxia at a low APGAR score at 1 and 5 min had statistically significant correlation with the outcomes of OAE screening.
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S., Gangadhara K., Amrutha V. Bhat, and Sridhara S. "Application of otoacoustic emissions and brainstem evoked response audiometry in newborn hearing screening." International Journal of Otorhinolaryngology and Head and Neck Surgery 8, no. 1 (2021): 26. http://dx.doi.org/10.18203/issn.2454-5929.ijohns20214895.
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<p class="abstract"><strong>Background: </strong>Newborn hearing screening was conducted in a tertiary care hospital in a step by step manner using otoacoustic emissions (OAE) and brainstem evoked response audiometry (BERA) and details were recorded.</p><p class="abstract"><strong>Methods:</strong> A prospective institutional based study was conducted. All the newborns born in the hospital over a period of 18 months from December 2018 to May 2020 were considered in the study. Healthy newborns were screened bedside within 24 hours of delivery and NICU (Neonatal Intensive Care Unit) babies were screened in the NICU. Handheld OAE apparatus was used as the initial screening tool. A total of 3 OAEs were done for babies with a “refer” result in the OAEs, which were done 1 month apart. Babies with a “refer” in the third OAE were subjected for BERA.</p><p class="abstract"><strong>Results:</strong> A total of 14226 babies were screened at 24-48 hours of birth. Among them, 13,069 babies passed the first OAE screening in both ears. Remaining babies were referred for further follow-up. After subsequent follow-ups and successive testing, 11 babies were found to have hearing loss, which was diagnosed within 4-5 months of the child’s birth.</p><p class="abstract"><strong>Conclusions: </strong>Universal newborn hearing screening is the need of the day. OAE is an effective screening tool for newborn hearing loss. When complemented by BERA, majority of congenitally deaf babies can be diagnosed at a very early age. This helps in early intervention.</p>
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Hall, James W., Jane E. Baer, Patricia A. Chase, and Mitchell K. Schwaber. "Clinical Application of Otoacoustic Emissions: What do we Know about Factors Influencing Measurement and Analysis?" Otolaryngology–Head and Neck Surgery 110, no. 1 (1994): 22–38. http://dx.doi.org/10.1177/019459989411000103.
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Three electrophysiologic audiologic procedures-aural immittance measurement, auditory brainstem response (ABR), and otoacoustic emissions (OAE) — were first described in the 1970's. Immittance measurement and ABR have contributed importantly for years to the assessment of auditory function in children and adults, whereas OAEs have not yet been incorporated into the everyday audiology test battery. In this article, we argue that the transition from OAE measurement by hearing scientists in laboratory settings to routine application by audiologists in the clinic will be greatly facilitated by (1) comprehensive, large-scale studies of the effects of subject characteristics, such as gender and age (from infancy to advancing adulthood), on both transient evoked (TEOAE) and distortion product (DPOAE) otoacoustic emissions; (2) clinical investigations of TEOAE and DPOAE in sizeable patient populations with specific neurotologic diagnoses; (3) guidelines for OAE test protocols in clinical environments; and (4) clear criteria for OAE analysis in clinical populations.
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Jedrzejczak, W. Wiktor, Elżbieta Gos, Edyta Pilka, Piotr H. Skarzynski, Henryk Skarzynski, and Stavros Hatzopoulos. "Pitfalls in the Detection of Hearing Loss via Otoacoustic Emissions." Applied Sciences 11, no. 5 (2021): 2184. http://dx.doi.org/10.3390/app11052184.
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Otoacoustic emissions (OAEs) are currently used as a valuable audiological test or as a hearing screening tool. There are many commercially available OAE recording systems that are used both for clinical practice and for research. However, there is little information in the literature comparing their performance in detecting hearing loss. The purpose of this prospective, nonrandomized, and controlled study was to evaluate the screening performance obtained from recent and older versions of the Otometrics Accuscreen OAE screening device in comparison with the Otodynamics ILO-292 OAE system, which has been used as the gold standard. Testing included otoscopic assessment, pure tone audiometry, tympanometry, and transiently evoked OAE (TEOAE) recordings. There was about a 77% agreement between the two versions of the Accuscreen device. Agreement between the two Accuscreen devices and the ILO was approximately 70% for the old and 80% for the new. The newer version of Accuscreen seems to perform better than the old, being more consistent with the reference ILO system and with the audiometry profiles of the tested subjects. In order to set robust standards for OAE evaluation and analysis, additional studies comparing different OAE hearing screening systems are needed.
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Terpos, Evangelos, Maria Gavriatopoulou, Ioannis Ntanasis-Stathopoulos, et al. "Less Is More: Deciphering the Association between Ocular Adverse Events and Clinical Activity of Belantamab Mafodotin in Multiple Myeloma." Blood 144, Supplement 1 (2024): 3380. https://doi.org/10.1182/blood-2024-209915.
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Introduction Belantamab mafodotin (belamaf; GSK2857916) has demonstrated important efficacy and tolerability in patients (pts) with relapsed/refractory multiple myeloma (MM). Ocular adverse events (OAEs; best corrected visual acuity [BCVA] change from baseline and keratopathy) are the most common adverse events (AEs) observed with belamaf and the main reason for dose holds and delays. However, the effect of OAE-related dose modifications on treatment efficacy has not been investigated. Herein, we present data from the BelaRd study, evaluating belamaf plus lenalidomide/dexamethasone (Rd) in transplant-ineligible pts with newly diagnosed MM, that offer insights on the association between OAEs and belamaf's clinical activity. Methods The ongoing phase 1/2 BelaRd study (NCT04808037) comprises 2 Parts. Part 1 evaluates the safety/tolerability of three different belamaf doses (2.5/1.9/1.4 mg/kg) plus Rd and established the recommended phase 2 dose (RP2D) of 1.9 mg/kg Q8W/Q12W. Part 2 assesses the safety/efficacy of RP2D in Groups A and B and evaluates two belamaf dosing guidelines for managing OAEs. In this trial, belamaf is initially administered Q8W and, depending on OAEs, dosing may be adjusted to Q12W. Ocular exams are performed by an ophthalmologist and include Snellen BCVA and slit-lamp corneal evaluation, while OAEs are graded with the Keratopathy Visual Acuity scale. In Part 1 and in Group A, belamaf dosing is permitted when OAEs are Gr0-1, while dosing is held at OAEs Gr2-4, until their resolution to Gr ≤1. In Group B, dosing is determined by the novel Vision-Related Anamnestic tool and the presence of Gr ≥3 OAEs identified in an ophthalmic exam. We present safety/efficacy results over an extensive follow-up period for both Parts (cut-off date 15/05/24). Results This analysis includes all pts from both Parts of the trial who have completed three cycles of treatment (n=65; median age: 74.0 years; male: 38 [58.5%]), of whom 49 (75.4%) are still on treatment and 16 (24.6%) discontinued (11 [16.9%] fatal events; 3 [4.6%] consent withdrawal; 2 [3.1%] progressive disease). By the clinical cut-off (CCO) date of this analysis, 52/65 (80%) pts have switched to the Q12W dosing schedule. The interval between the first belamaf dose and the first manifestation of a Gr≥2 OAE varied greatly among pts and can be used to divide them into two hypothetical groups. The first group consists of pts who had a Gr2-4 OAE within the first three months of treatment (Group 1; 19/65, 29.2%). The second group consists of pts who only had Gr0-1 OAEs during this time (Group 2; 46/65, 70.8%). By the CCO date, 68.4% of Group 1 pts had achieved a ≥CR response, while the respective proportion in Group 2 was 37.0%. Importantly, this trend was observed across all three dose levels of this analysis. The proportions of ≥CR responses were 100%, 57.2% and 100.0% for Group 1 and 57.2%, 28.6% and 45.5% for Group 2 for the dose levels of 2.5, 1.9 and 1.4 mg/kg, respectively. Additionally, for Groups 1 and 2, the median (range) from the 3-month landmark time to CR in months was 11.76 (4.37-13.90) and 23.29 (8.67-NR), respectively. The median (Q1-Q3) duration of the interval between belamaf doses was 13.1 (10.3-18.6)/11.9 (8.0-13.3) weeks for Groups 1 and 2, respectively, while the respective belamaf cumulative dose intensities were 0.543/0.625 mg/month. Finally, at a median follow-up of 19.8 months, all pts who achieved a ≥CR response had previously manifested Gr2-4 OAEs, while pts who only had Gr0-1 OAEs achieved ≤VGPR. Conclusions Our analyses highlight the complex association between OAEs and clinical activity, indicating the idiosyncratic nature of a patient's response to belamaf in terms of ocular toxicity and efficacy. Indeed, our data reveal that early manifestation of at least moderately severe OAEs (Gr≥2) correspond to early deep responses, a phenomenon observed across all dose levels. Additionally, dose intensity (DI) does not have a linear association with hematologic response, as pts with lower cumulative DI manifested deeper responses. Furthermore, an extended dosing interval due to OAEs is also a hallmark of better efficacy. Conclusively, OAEs, the most common AEs of belamaf that are responsible for dose modifications, may have a predictive and, potentially, also a prognostic role. Moving forward, the association between OAEs and efficacy warrants further investigation in larger sample sizes.
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Shera, Christopher. "The sing-song of old man human ear." Journal of the Acoustical Society of America 155, no. 3_Supplement (2024): A218. http://dx.doi.org/10.1121/10.0027357.
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Otoacoustic emissions evoked from the inner ear are the barely audible, signature by-product of the delicate hydromechanical amplifier that evolved within its bony walls. Compared to the sounds evoked from the ears of common laboratory animals, otoacoustic emissions (OAEs) from human ears have exceptionally long delays, typically exceeding those of cats, guinea pigs, and chinchillas by a factor of two to three. This presentation asks “Why are human OAE delays so long?” and reviews efforts to find answers in the mechanical frequency selectivity of the inner ear. The road to understanding species differences in OAE delay has led to the identification of new invariances and the emergence of new questions.
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Jedrzejczak, W. Wiktor, Rafal Milner, Malgorzata Ganc, Edyta Pilka, and Henryk Skarzynski. "No Change in Medial Olivocochlear Efferent Activity during an Auditory or Visual Task: Dual Evidence from Otoacoustic Emissions and Event-Related Potentials." Brain Sciences 10, no. 11 (2020): 894. http://dx.doi.org/10.3390/brainsci10110894.
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The medial olivocochlear (MOC) system is thought to be responsible for modulation of peripheral hearing through descending (efferent) pathways. This study investigated the connection between peripheral hearing function and conscious attention during two different modality tasks, auditory and visual. Peripheral hearing function was evaluated by analyzing the amount of suppression of otoacoustic emissions (OAEs) by contralateral acoustic stimulation (CAS), a well-known effect of the MOC. Simultaneously, attention was evaluated by event-related potentials (ERPs). Although the ERPs showed clear differences in processing of auditory and visual tasks, there were no differences in the levels of OAE suppression. We also analyzed OAEs for the highest magnitude resonant mode signal detected by the matching pursuit method, but again did not find a significant effect of task, and no difference in noise level or number of rejected trials. However, for auditory tasks, the amplitude of the P3 cognitive wave negatively correlated with the level of OAE suppression. We conclude that there seems to be no change in MOC function when performing different modality tasks, although the cortex still remains able to modulate some aspects of MOC activity.
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Prawanta, Ekkanat, Munhum Park, and Yuttana Roongthumskul. "Head-related transfer function for the measurements of otoacoustic emissions evoked by localized sound sources." Journal of Physics: Conference Series 2934, no. 1 (2025): 012031. https://doi.org/10.1088/1742-6596/2934/1/012031.
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Abstract Not one but two ears enable us to identify the location of a sound source by comparing the amplitudes and phases of acoustic signals. In this study, we explore the response of the inner ears to localized sounds by measuring otoacoustic emissions (OAEs) which refers to sounds produced by the inner ear in response to external sounds, thus governed by the activities of the acoustic receptors. OAEs were recorded simultaneously from both ears by fitting a small microphone-speaker probe into each ear canal. The binaural sounds used to evoke OAEs were designed to correspond to a localized sound source by using Head-related transfer functions (HRTFs) measured from a head-and-torso simulator. OAEs were elicited by bursts of pure tones originating from two virtual sound sources, one in front of the participants, and the other to their left ears. Our results demonstrated that, for tone bursts at 0.5 kHz, 1.0 kHz, and 2.0 kHz, the intensity and time differences of bilateral OAEs were enhanced by 3.57 dB – 6.70 dB when the virtual sound moved from 0 to 90 degrees. This was consistent with the amplitude and time differences of the stimuli. For tone bursts at 4.0 kHz, however, the average OAE amplitude difference was 20.11 dB, exceeding that of the stimuli at 7.78 dB. Our results demonstrate that bilateral OAEs directly reflect the amplitude and phase differences of the incoming signals and that the developed technique could be used for the investigations of OAEs during sound localization.
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CORS, JEAN, ULRICH HEIMHOFER, THIERRY ADATTE, PETER A. HOCHULI, STEFAN HUCK, and TELM BOVER-ARNAL. "Climatic evolution across oceanic anoxic event 1a derived from terrestrial palynology and clay minerals (Maestrat Basin, Spain)." Geological Magazine 152, no. 4 (2014): 632–47. http://dx.doi.org/10.1017/s0016756814000557.
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AbstractStudies dealing with the response of the continental biosphere to the environmental perturbations associated with Cretaceous oceanic anoxic events (OAEs) are comparatively rare. Here, a quantitative spore-pollen record combined with clay mineral data is presented, which covers the entire early Aptian OAE 1a interval (Forcall Formation, Maestrat basin, east Spain). The well-expressed OAE 1a carbon-isotope anomaly is paralleled by changes in the clay mineral assemblage and by a stepwise decline in the normalized frequency ofClassopollispollen (produced by xerophytic Cheirolepidiaceae) with lowest contents occurring during the positive δ13C shift. In contrast,AraucariacitesandInaperturopollenitespollen show a pronounced increase in relative abundance from low background values to become a significant component of the palynological assemblage during theClassopollisminimum. The observed changes in clay minerals and pollen distribution patterns are interpreted to reflect a major change in the composition of the hinterland vegetation of the Maestrat Basin, most probably due to short-lived but pronounced climatic cooling and changes in humidity. Temperature anomalies driven by organic carbon burial and associated CO2decline have been postulated for all major Mesozoic OAEs. The palynomorph record from the Iberian Maestrat basins indicates that the climax of this cooling episode was significantly delayed in comparison to the end of organic carbon-rich deposition in the world oceans.
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Bu, Xingkuan, Xiaolu Li, and Carlie Driscoll. "The Chinese Hearing Questionnaire for School Children." Journal of the American Academy of Audiology 16, no. 09 (2005): 687–97. http://dx.doi.org/10.3766/jaaa.16.9.6.
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Hearing loss is the most common of all disabilities in China, with three million of the 1.4 billion population affected. Recently, the release of an official neonatal hearing screening consensus has drawn attention to the importance of continued surveillance throughout childhood and the need for a system that is suited to the Chinese situation. The current research aimed to develop and evaluate a questionnaire for mass screening of school children in China. In Jiangsu Province, 317 rural students were screened using the Chinese Hearing Questionnaire for School Children (CHQS) and otoacoustic emissions (OAE). Test performance measures for the questionnaire method revealed average overall accuracy (A' = 0.54), while higher system accuracy was obtained for the OAEs (A' = 0.85). The OAE screening also produced very high efficiency and specificity values with reasonable sensitivity. Unlike the OAE protocol, the CHQS will require substantial modification to improve its sensitivity prior to utilization as a mass screening tool.
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Ruvalcaba Baroni, I., R. P. M. Topper, N. A. G. M. van Helmond, H. Brinkhuis, and C. P. Slomp. "Biogeochemistry of the North Atlantic during oceanic anoxic event 2: role of changes in ocean circulation and phosphorus input." Biogeosciences 11, no. 4 (2014): 977–93. http://dx.doi.org/10.5194/bg-11-977-2014.
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Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called the proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low-oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.
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Ruvalcaba-Baroni, I., R. P. M. Topper, N. A. G. M. van Helmond, H. Brinkhuis, and C. P. Slomp. "Was the North Atlantic Ocean well-ventilated during Oceanic Anoxic Event 2 in the mid-Cretaceous?" Biogeosciences Discussions 10, no. 8 (2013): 13231–76. http://dx.doi.org/10.5194/bgd-10-13231-2013.
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Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.
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De Groote, Evelien, Annelies Bockstael, Dick Botteldooren, Patrick Santens, and Miet De Letter. "The Effect of Parkinson's Disease on Otoacoustic Emissions and Efferent Suppression of Transient Evoked Otoacoustic Emissions." Journal of Speech, Language, and Hearing Research 64, no. 4 (2021): 1354–68. http://dx.doi.org/10.1044/2020_jslhr-20-00594.
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Purpose Several studies have demonstrated increased auditory thresholds in patients with Parkinson's disease (PD) based on subjective tonal audiometry. However, the pathophysiological mechanisms underlying auditory dysfunction in PD remain elusive. The primary aim of this study was to investigate cochlear and olivocochlear function in PD using objective measurements and to assess the effect of dopaminergic medication on auditory function. Method Eighteen patients with PD and 18 gender- and age-matched healthy controls (HCs) were included. Patients with PD participated in medication on and off conditions. Linear mixed models were used to determine the effect of PD on tonal audiometry, transient evoked and distortion product otoacoustic emissions (OAEs), and efferent suppression (ES). Results Tonal audiometry revealed normal auditory thresholds in patients with PD for their age across all frequencies. OAE signal amplitudes demonstrated a significant interaction effect between group (PD vs. HC) and frequency, indicating decreased OAEs at low frequencies and increased OAEs at high frequencies in patients with PD. No significant differences were found between patients with PD and HCs regarding ES. In addition, no significant effect of medication status was found on auditory measurements in patients with PD. Conclusions Altered OAEs support the hypothesis of cochlear alterations in PD. No evidence was found for the involvement of the medial olivocochlear system. Altogether, OAEs may provide an objective early indicator of auditory alterations in PD and should complement subjective tonal audiometry when assessing and monitoring auditory function in PD.
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Beksac, Meral, Hang Quach, Vania Hungria, et al. "Baseline ocular conditions and risk of ocular events in patients (pts) with relapsed/refractory multiple myeloma (RRMM) from the DREAMM-7 and DREAMM-8 trials of belantamab mafodotin (belamaf)." Journal of Clinical Oncology 43, no. 16_suppl (2025): 7544. https://doi.org/10.1200/jco.2025.43.16_suppl.7544.
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7544 Background: Belamaf combinations were evaluated for RRMM in the phase 3 DREAMM-7 (belamaf + bortezomib + dexamethasone [BVd]; NCT04246047) and DREAMM-8 (belamaf + pomalidomide + dexamethasone [BPd]; NCT04484623) trials, and significant progression-free survival benefits were reported over standard of care, with significant overall survival benefit reported for BVd. Ocular events (e.g., ocular adverse events [oAEs], blurred vision, dry eye) occurred with belamaf and most resolved with dose holds and modifications. We examined the baseline eye health of pts with RRMM receiving BVd or BPd, and whether baseline ocular conditions affected rates of treatment-emergent (TE) oAEs. Methods: Pts with ≥1 prior therapy were eligible for DREAMM-7/8; pts with ocular conditions were eligible except for corneal epithelial disease (mild punctate keratopathy was allowed). Mandatory ophthalmic examinations (best corrected visual acuity [BCVA], slit lamp, and funduscopic exams) were performed in both arms of the trials at baseline and routinely during treatment. oAEs were graded by Common Terminology Criteria for Adverse Events. Regardless of presence/absence of baseline ocular conditions, the same protocol-defined strategies were used for ocular event management during the studies. Results: In 392 pts treated with belamaf (n=242 DREAMM-7 and n=150 DREAMM-8), baseline ocular conditions were reported in 62% of pts (n=135 and 106); baseline conditions included cataract 50% (n=101 and 96), keratopathy 14% (n=33 and 23), dry eye 14% (n=31 and 24), visual acuity of 20/50 or worse 6% (n=18 and 7), glaucoma 6% (n=11 and 13), blepharitis 2% (n=4 and 3), age-related macular degeneration 1% (n=3 and 2), and diabetic retinopathy <1% (n=0 and 2). Any TE oAE was reported in 74% (n=100/135) and 87% (n=92/106) of pts with baseline ocular conditions in DREAMM-7 and DREAMM-8, respectively, compared with 79% (n=85/107) and 91% (n=40/44) of pts without baseline ocular conditions (Table). Conclusions: The safety profiles of belamaf combinations for oAEs were similar between patients with vs without baseline ocular conditions, suggesting that these baseline ocular conditions did not increase the risk of TE oAEs. The effect of each baseline ocular condition on TE oAEs, as well as TE corneal exam findings and visual acuity changes, will be presented. Clinical trial information: NCT04246047 , NCT04484623 . TE ocular events in patients receiving a belamaf combination in DREAMM-7/8. DREAMM-7 DREAMM-8 With any baseline ocular condition, n=135 No baseline ocular condition, n=107 With any baseline ocular condition, n=106 No baseline ocular condition, n=44 Any oAE, n (%) 100 (74) 85 (79) 92 (87) 40 (91)
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Farhadi, Afagh, Samantha Hauser, Andrew Sivaprakasam, and Michael G. Heinz. "Evaluation of efferent influences on neural coding using pre-clinical models of sensorineural hearing loss." Journal of the Acoustical Society of America 155, no. 3_Supplement (2024): A40. http://dx.doi.org/10.1121/10.0026729.
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The medial olivocochlear (MOC) efferent system is less explored than the ascending auditory pathway but likely contributes in important ways to neural coding and perception. These effects are thought to vary across stimulus configurations, anesthetic states, and subtypes of sensorineural hearing loss (SNHL). To explore effective assays of MOC effects on neural coding, we have recorded Interleaved otoacoustic emissions (OAEs) and envelope following responses (EFRs) from several pre-clinical SNHL chinchilla models. Our preliminary observations include increases in OAEs with inner-hair-cell loss and anesthesia, which may be due to reduced efferent strength. Additionally, we observed enhanced EFRs with an added noise masker, which also could be related to efferent effects. We are using sedated and awake OAE comparisons to develop a standard efferent assay for use in neural-coding studies. Interleaved recording of OAEs and EFRs track cochlear-gain and neural-coding changes during acoustic stimuli. A recently developed modeling framework (Farhadi et al., 2023 JASA) that includes different MOC projection pathways, including midbrain modulation-sensitive inputs, is used to guide most-effective stimulus selection. Ultimately, this model-guided experimental framework will provide unique guidance for testing MOC hypotheses related to neural coding.
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Zimatore, Giovanna, Piotr Henryk Skarzynski, Federica Di Berardino, et al. "Re-evaluating the scoring criteria of the Interacoustics Sera Neonatal Hearing Screener." Hearing Balance and Communication 22, no. 3 (2024): 100–109. http://dx.doi.org/10.4103/hbc.hbc_24_24.
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Abstract Introduction: Newborn hearing screeners via otoacoustic emissions (OAEs) have become the standard in audiological clinical practice. Despite the application of OAE protocols for more than 3 decades, there has been no consensus on the standardization of the recorded responses. Usually, manufacturers based the scoring criteria of the OAE responses on small scale samples and in many cases on data published in the literature. Since there are no standards in the OAE probe construction, the resulted OAE responses are quite different between OAE screeners. The project evaluated the scoring criteria used in the Interacoustics Sera OAE screener. Methods: Eight hundred and eleven infants were initially screened by the Accuscreen OAE screener for a Pass or a Fail outcome. Seven hundred and ninety-two infants resulted as Pass were re-evaluated with the Sera transient-evoked OAE (TEOAE) and distortion-product OAE (DPOAE) protocols. Results: In terms of screening efficiency, the DPOAE protocol performed better, showing results very similar to the Accuscreen performance (Fail %: 2.4 vs. 2.3). The data showed that the recordings of the TEOAE responses were more prone to noise corruption. Using 10th percentile normative distribution values, DPOAE-optimized scoring criteria were estimated as 3.1, 7.9, 9.9, and 8.9 dB for the tested frequencies of 2.0, 3.0, 4.0, and 5.0 kHz. Unfortunately, the TEOAE signal-to-noise (S/N) data resulted as too noisy (despite relatively large TEOAE responses); therefore, the TEOAE responses were considered as scoring criteria candidates. The latter were estimated as 4.61, 6.35, 7, 1 and 3, 35 dB at 1.4, 2.0, 2.8, 4.0 kHz. Conclusion: It is possible to improve the screening efficiency of the DPOAE Sera protocol using optimized scoring criteria, aiming the correct identification of at least 90% of all normal hearing subjects. The Sera TEOAE protocol needs further investigation to identify the source of the noise, which lowers significantly the reported S/N ratios. The collected OAE data confirm that there are differences among the responses obtained by various screeners; therefore, an OAE probe standardization is necessary.
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Spankovich, Christopher, Glenis R. Long, and Linda J. Hood. "Early Indices of Reduced Cochlear Function in Young Adults with Type-1 Diabetes Revealed by DPOAE Fine Structure." Journal of the American Academy of Audiology 30, no. 06 (2019): 459–71. http://dx.doi.org/10.3766/jaaa.17113.
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AbstractThe relationship between type-1 diabetes mellitus (DM) and cochlear dysfunction remains inconclusive.The purpose of this study was to examine otoacoustic emissions (OAEs) in normal-hearing young adults with type-1 DM as compared with matched controls and identify potential covariates influencing OAE findings.Cross-sectional study.N = 40 young adults aged 18–28 years including individuals with type-1 DM (n = 20) and age–gender matched controls (n = 20) with normal hearing sensitivity.Measures of pure-tone threshold sensitivity and OAEs, including distortion product otoacoustic emissions (DPOAEs), transient evoked OAEs, and DPOAE fine structure, were compared between groups. Covariates such as noise exposure and DM-related factors (e.g., duration of disease, glycated hemoglobin levels) were considered. Statistical analysis included analysis of variance and linear regression.Measures of hearing sensitivity and auditory function in both groups were comparable for all assays, except DPOAE fine structure. A reduced number of fine structure peaks and component amplitudes were found in the type-1 diabetes DM group with the primary difference in the reflection component.The results indicate that reduced cochlear function in young adults with type-1 DM can be revealed using DPOAE fine structure, suggesting potential clinical applications of DPOAE fine structure in early identification of cochlear pathology. Potential factors underlying these findings are discussed.
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Friedrich, Oliver, Silke Voigt, Tanja Kuhnt, and Mirjam C. Koch. "Repeated bottom-water oxygenation during OAE 2: timing and duration of short-lived benthic foraminiferal repopulation events (Wunstorf, northern Germany)." Journal of Micropalaeontology 30, no. 2 (2011): 119–28. http://dx.doi.org/10.1144/0262-821x11-011.
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Abstract. Published proxy data for Oceanic Anoxic Event 2 (OAE 2 or Cenomanian–Turonian Boundary Event) and other mid-Cretaceous OAEs indicate widespread anoxic bottom-water conditions. However, increasing evidence shows that anoxia was not permanent but subject to significant fluctuations. We have generated X-ray fluorescence elemental concentration and benthic foraminiferal assemblage records for a short section of OAE 2 black shales from Wunstorf, northern Germany. Two intervals of low sulphur elemental concentration are interpreted as periods of increased oxygenation of bottom waters. This is supported by benthic foraminiferal assemblage data showing repopulation events associated with these intervals. These repopulation events are characterized mainly by the occurrence of agglutinated taxa, with Lingulogavelinella globosa being the only abundant calcareous species. This observation is interpreted in terms of short-term interruptions of the otherwise anoxic bottom-water environment. Comparison with repopulation events during OAE 1b and Quaternary sapropels make it reasonable to speculate that short-term cooling and an associated increase in bottom-water ventilation at the NW European shelf sea are the main trigger mechanisms for the observed repopulation events at Wunstorf. As source area for benthic foraminifera, shallower parts of the Lower Saxony basin are proposed.
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Them, Theodore R., Benjamin C. Gill, Andrew H. Caruthers, et al. "Thallium isotopes reveal protracted anoxia during the Toarcian (Early Jurassic) associated with volcanism, carbon burial, and mass extinction." Proceedings of the National Academy of Sciences 115, no. 26 (2018): 6596–601. http://dx.doi.org/10.1073/pnas.1803478115.
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For this study, we generated thallium (Tl) isotope records from two anoxic basins to track the earliest changes in global bottom water oxygen contents over the Toarcian Oceanic Anoxic Event (T-OAE; ∼183 Ma) of the Early Jurassic. The T-OAE, like other Mesozoic OAEs, has been interpreted as an expansion of marine oxygen depletion based on indirect methods such as organic-rich facies, carbon isotope excursions, and biological turnover. Our Tl isotope data, however, reveal explicit evidence for earlier global marine deoxygenation of ocean water, some 600 ka before the classically defined T-OAE. This antecedent deoxygenation occurs at the Pliensbachian/Toarcian boundary and is coeval with the onset of initial large igneous province (LIP) volcanism and the initiation of a marine mass extinction. Thallium isotopes are also perturbed during the T-OAE interval, as defined by carbon isotopes, reflecting a second deoxygenation event that coincides with the acme of elevated marine mass extinctions and the main phase of LIP volcanism. This suggests that the duration of widespread anoxic bottom waters was at least 1 million years in duration and spanned early to middle Toarcian time. Thus, the Tl data reveal a more nuanced record of marine oxygen depletion and its links to biological change during a period of climatic warming in Earth’s past and highlight the role of oxygen depletion on past biological evolution.
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De Keyser, Kim, Miet De Letter, Evelien De Groote, et al. "Systematic Audiological Assessment of Auditory Functioning in Patients With Parkinson's Disease." Journal of Speech, Language, and Hearing Research 62, no. 12 (2019): 4564–77. http://dx.doi.org/10.1044/2019_jslhr-h-19-0097.
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Purpose Alterations in primary auditory functioning have been reported in patients with Parkinson's disease (PD). Despite the current findings, the pathophysiological mechanisms underlying these alterations remain unclear, and the effect of dopaminergic medication on auditory functioning in PD has been explored insufficiently. Therefore, this study aimed to systematically investigate primary auditory functioning in patients with PD by using both subjective and objective audiological measurements. Method In this case–control study, 25 patients with PD and 25 age-, gender-, and education-matched healthy controls underwent an audiological test battery consisting of tonal audiometry, short increment sensitivity index, otoacoustic emissions (OAEs), and speech audiometry. Patients with PD were tested in the on- and off-medication states. Results Increased OAE amplitudes were found when patients with PD were tested without dopaminergic medication. In addition, speech audiometry in silence and multitalker babble noise demonstrated higher phoneme scores for patients with PD in the off-medication condition. The results showed no differences in auditory functioning between patients with PD in the on-medication condition and healthy controls. No effect of disease stage or motor score was evident. Conclusions This study provides evidence for a top-down involvement in auditory processing in PD at both central and peripheral levels. Most important, the increase in OAE amplitude in the off-medication condition in PD is hypothesized to be linked to a dysfunction of the olivocochlear efferent system, which is known to have an inhibitory effect on outer hair cell functioning. Future studies may clarify whether OAEs may facilitate an early diagnosis of PD.
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Mazumder, Rajarshi, Samson Kamya Lubowa, Noriko Salamon, et al. "Comparison of Structural Changes in Nodding Syndrome and Other Epilepsies Associated WithOnchocerca volvulus." Neurology - Neuroimmunology Neuroinflammation 10, no. 2 (2022): e200074. http://dx.doi.org/10.1212/nxi.0000000000200074.
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Background and ObjectiveNodding syndrome (NS) is a unique childhood-onset epileptic disorder that occurs predominantly in several regions of sub-Saharan Africa. The disease has been associated withOnchocerca volvulus (Ov)–induced immune responses and possible cross-reactivity with host proteins. The aim of this study was to compare structural changes in the brain on MRI between NS and other forms of onchocerciasis-associated epilepsies (OAEs) and to relate structural changes to the Ov-induced immune responses and level of disability.MethodsThirty-nine children with NS and 14 age-matched participants with other forms of OAE from an endemic region in Uganda underwent detailed clinical examination, serologic evaluation (including Ov-associated antibodies to Ov-16 and Hu-leiomodin-1) and quantitative volumetric analysis of brain MRIs (1.5 T scanner) using Neuroreader, a cloud-based software.ResultsCerebral and cerebellar atrophy were the predominant features in both NS and OAE. On quantitative volumetric analysis, participants with NS had larger ventricular volumes compared with participants with OAE, indicative of increased global cortical atrophy (pcorr= 0.036). Among children with NS, severe disability correlated with higher degree of atrophy in the gray matter volume (pcorr= 0.009) and cerebellar volume (pcorr= 0.009). NS cases had lower anti-Ov-16 IgG signal-to-noise ratios than the OAE cases (p< 0.01), but no difference in the levels of the Hu-leiomodin-1 antibodies (p= 0.64). The levels of Ov-associated antibodies did not relate to the degree of cerebral or cerebellar atrophy in either NS or OAE cases.DiscussionThis is the first study to show that cerebral and cerebellar atrophy correlated with the severity of NS disability, providing an imaging marker for these endemic epileptic disorders that until now have remained poorly characterized. Both NS and OAE have cerebral and cerebellar atrophy, and the levels of Ov-associated antibodies do not seem to be related to the structural changes on MRI.
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Löhr, S. C., and M. J. Kennedy. "Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2." Biogeosciences Discussions 11, no. 5 (2014): 6815–44. http://dx.doi.org/10.5194/bgd-11-6815-2014.
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Abstract. Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE2 at Demerara Rise was controlled by co-occurrence of anoxic bottom-water, sufficient productivity to saturate available mineral surfaces and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2=0.92) occurs across a range of TOC values from 9–33%. X-ray diffraction data indicates intercalation of OC in smectite interlayers while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE2 at Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.