bluuebunny/crossref_metadata_2025 huggingface dataset:
Friction and wear behavior of different seal materials under water-lubricated conditions
Authors: Zhao Weigang , Zhang Guoyuan , Dong Guangneng
Published: August 2020

The shaft mechanical face seal in a high-speed turbopump of a liquid rocket engine often operates under extremely harsh conditions. For example, a low-temperature and low-viscosity fluid (such as liquid oxygen or liquid hydrogen) is used as a lubricant. The performance of the seal rings, especially the friction and wear behavior, directly determines whether the seal functions normal. In this study, the friction and wear behavior of several ring materials are tested using a pin-on-disk tribo-tester, and the wear morphology of the ring is investigated. The friction coefficients (COFs) and mass-wear rates under dry-friction and water-lubricated conditions, which are used to simulate low-viscosity conditions, are obtained. The results show that at a pressure-velocity (PV) value of 2.4 MPa·(m/s), the COF between the copper graphite (stator) and copper-chrome alloy disk (rotor) is low (with a value of 0.18) under the dry-friction conditions, and the 5-min wear mass of the copper graphite is approximately 2 mg. Under the water-lubricated conditions, compared with other materials (such as copper-chrome alloy, S07 steel, alumina ceramic coating, and nickel-based calcium fluoride), the S07 steel with a diamond-like carbon film is preferred for use in a high-speed turbopump under extreme conditions. The results of this study can provide theoretical and experimental guidance in the design of mechanical face seals in liquid rocket engines.
Topology dependence of on-demand ride-sharing
Authors: Manik Debsankha , Molkenthin Nora
Published: August 2020

Traffic is a challenge in rural and urban areas alike with negative effects ranging from congestion to air pollution. Ride-sharing poses an appealing alternative to personal cars, combining the traffic-reducing ride bundling of public transport with much of the flexibility and comfort of personal cars. Here we study the effects of the underlying street network topology on the viability of ride bundling analytically and in simulations. Using numerical and analytical approaches we find that system performance can be measured in the number of scheduled stops per vehicle. Its scaling with the request rate is approximately linear and the slope, that depends on the network topology, is a measure of the ease of ridesharing in that topology. This dependence is caused by the different growth of the route volume, which we compute analytically for the simplest networks served by a single vehicle.
Travel Time and Source Variation Explain the Molecular Transformation of Dissolved Organic Matter in an Alpine Stream Network
Authors: Peter H. , Singer G. , Ulseth A. J. , Dittmar T. , Prairie Y. T. , Battin T. J.
Published: August 2020

Streams and rivers are important components of the carbon cycle as they transport and transform dissolved organic matter (DOM). Using high‐resolution Fourier‐transform ion cyclotron resonance mass spectrometry, we studied the spatial distribution of DOM at the molecular level at more than 100 sites across a stream network during summer and winter baseflow. We developed a model approximating the time DOM spent in the fluvial network, a key constraint on the biogeochemical processing of DOM. Discharge‐weighted travel time explained the compositional changes of DOM, which differed markedly in summer and winter. We attribute these seasonal differences to variation in source material, putatively reflecting the dynamics of freshly produced DOM in summer and DOM with an imprint of leaf litter in winter. Hydrological mixing was an important driver of the spatial dynamics of DOM. From the convergence rate of DOM compound intensities to the network‐wide average, we inferred the spatial distribution of sources within the catchment. Finally, we estimated network‐wide apparent mass transfer coefficients (vf app) of individual DOM compounds, which describe the vertical velocity at which DOM compounds are removed by biotic and abiotic processes. We identified the oxidative state of carbon as an important factor explaining vf app, which we consequently attribute to biological uptake of thermodynamically favorable DOM compounds. This work contributes to our understanding of the spatial processes, temporal constraints, and chemical properties of DOM that regulate the transformation and diagenesis of DOM at the fluvial network scale.
Single Tests of Thermocline Dwelling Foraminifera Globorotalia inflata as Recorder of Upper Water Column Structure off Mauritania (NW Africa): Methodology and Paleoceanographic Use
Authors: Johnstone Heather J. H. , Kuhnert Henning , Bickert Torsten , Romero Oscar , Pälike Heiko
Published: August 2020

Thermocline‐dwelling foraminifera calcify over a depth range of several hundred meters; analysis of individual shells therefore allows insight to the hydrography of the upper water column. We analyzed δ18O, δ13C, and Mg/Ca of individual tests of the planktonic foraminifera Globorotalia inflata from a sediment core (GeoB7926‐2) obtained from 20°N in the eastern tropical Atlantic. To facilitate sample throughput, tests were cleaned before Mg/Ca analysis using a pipette robot. The eight samples came from five time periods with contrasting climate states. Median reconstructed temperatures were lowest during the warmth of the Bølling Allerød BA) (11.8°C), while highest temperatures (>14°C) were recorded during the cold periods of the Last Glacial Maximum (LGM), late Heinrich Stadial 1 (HS1), and the Younger Dryas (YD). Southward shift in the subtropical gyre during Northern Hemisphere cold periods and modulation by upwelling could explain the temperature change but not all of the salinity change. δ18Oseawater‐IVC indicated that salinity was higher than the global average during the LGM, with very high salinity excursions in HS1 and a smaller excursion in the YD. The upwelling signature was most strongly imprinted on range in δ13C. The large changes in salinity and δ13C between time slices cannot be explained by upwelling intensity but indicate the presence of a very saline water mass, with low δ13C, in the eastern North Atlantic subsurface during Northern Hemisphere cold periods.
Canada’s Rocky Mountain Forests Are on the Move
Authors: Johnson-Groh Mara
Published: August 2020

Using century-old surveying photos, scientists have mapped 100 years of change in the Canadian Rockies to document the climate-altered landscape.
Comparison of Vertical Surface Deformation Estimates Derived From Space‐Based Gravimetry, Ground‐Based GPS, and Model‐Based Hydrologic Loading Over Snow‐Dominated Watersheds in the United States
Authors: Yin Gaohong , Forman Barton A. , Loomis Bryant D. , Luthcke Scott B.
Published: August 2020

Spatiotemporal variability in Earth's terrestrial water storage (TWS) causes changes in surface deformation. The potential for using ground‐based Global Positioning System (GPS) vertical displacement observations for estimating TWS is explored through a comparison of vertical displacements derived from space‐based gravimetric retrievals, ground‐based GPS, and model‐based hydrologic estimates. The study presented here focuses on two snow‐dominated basins in the Western United States for the years 2003–2016. Seasonal variations are observed in the vertical displacements derived from all three data sets, and the variation is coherent with the changes in hydrologic loading. Good consistency is observed between any two of the three data sets with gravimetric retrievals and hydrologic model estimates providing the highest level of agreement (i.e., all examined stations with correlation coefficient R > 0.70). Vertical displacements derived from gravimetric retrievals and ground‐based GPS yielded R > 0.70 for more than 89% of the stations. In addition, it is found that both GPS‐derived and space‐based, gravimetry‐derived vertical displacements clearly reflected the impact of climate variation (i.e., heavy precipitation during 2010–2011 winter followed by prolonged drought). Vertical displacements derived from the hydrologic model highlighted the relatively large precipitation convergence phase during late 2010 to early 2011 at some stations but not the prolonged drought that followed. The results indicate that ground‐based GPS observations of vertical displacement have the capability to capture variations in TWS changes, which can be systematically merged in conjunction with Gravity Recovery and Climate Experiment (GRACE) into a land surface model to improve TWS estimates in a follow‐up study.
Supershear Frictional Ruptures Along Bimaterial Interfaces
Authors: Shlomai H. , Adda‐Bedia M. , Arias R. E. , Fineberg Jay
Published: August 2020

We experimentally and analytically explore supershear ruptures that are excited at the onset of frictional motion within “bimaterial interfaces,” frictional interfaces formed by contacting bodies having different elastic (or geometric) properties. Our experiments on PMMA blocks sliding on polycarbonate show that the structure, transition sequence, and range of existence of such supershear ruptures are highly dependent on their propagation direction relative to the slip direction in the softer of the two materials. These properties are characterized for both the positive (parallel) and negative (antiparallel) propagation directions. An analytic, fracture‐mechanics based description of supershear ruptures is derived. The theory quantitatively predicts both supershear structure and the allowed propagation range of supershear ruptures. The latter compares well with both the experimentally observed supershear ruptures in the negative direction as well as localized slip pulses in the positive direction, whose propagation speed lies between the shear velocities of both materials. Supershear ruptures in the positive direction, which are composed of trains of propagating slip pulses, evade this theoretical description.
A Moist Physics Parameterization Based on Deep Learning
Authors: Han Yilun , Zhang Guang J. , Huang Xiaomeng , Wang Yong
Published: August 2020

Current moist physics parameterization schemes in general circulation models (GCMs) are the main source of biases in simulated precipitation and atmospheric circulation. Recent advances in machine learning make it possible to explore data‐driven approaches to developing parameterization for moist physics processes such as convection and clouds. This study aims to develop a new moist physics parameterization scheme based on deep learning. We use a residual convolutional neural network (ResNet) for this purpose. It is trained with 1‐year simulation from a superparameterized GCM, SPCAM. An independent year of SPCAM simulation is used for evaluation. In the design of the neural network, referred to as ResCu, the moist static energy conservation during moist processes is considered. In addition, the past history of the atmospheric states, convection, and clouds is also considered. The predicted variables from the neural network are GCM grid‐scale heating and drying rates by convection and clouds, and cloud liquid and ice water contents. Precipitation is derived from predicted moisture tendency. In the independent data test, ResCu can accurately reproduce the SPCAM simulation in both time mean and temporal variance. Comparison with other neural networks demonstrates the superior performance of ResNet architecture. ResCu is further tested in a single‐column model for both continental midlatitude warm season convection and tropical monsoonal convection. In both cases, it simulates the timing and intensity of convective events well. In the prognostic test of tropical convection case, the simulated temperature and moisture biases with ResCu are smaller than those using conventional convection and cloud parameterizations.
Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization
Authors: Gastineau Guillaume , Lott François , Mignot Juliette , Hourdin Frederic
Published: August 2020

In climate models, the subgrid‐scale orography (SSO) parameterization imposes a blocked flow drag at low levels that is opposed to the local flow. In IPSL‐CM6A‐LR, an SSO lift force is also applied perpendicular to the local flow to account for the effect of locally blocked air in narrow valleys. Using IPSL‐CM6A‐LR sensitivity experiments, it is found that the tuning of both effects strongly impacts the atmospheric circulation. Increasing the blocking and reducing the lift lead to an equatorward shift of the Northern Hemisphere subtropical jet and a reduction of the midlatitude eddy‐driven jet speed. It also improves the simulated synoptic variability, with a reduced storm‐track intensity and increased blocking frequency over Greenland and Scandinavia. Additionally, it cools the polar lower troposphere in boreal winter. Transformed Eulerian Mean diagnostics also show that the low‐level eddy‐driven subsidence over the polar region is reduced consistent with the simulated cooling. The changes are amplified in coupled experiments when compared to atmosphere‐only experiments, as the low‐troposphere polar cooling is further amplified by the temperature and albedo feedbacks resulting from the Arctic sea ice growth. In IPSL‐CM6A‐LR, this corrects the warm winter bias and the lack of sea ice that were present over the Arctic before adjusting the SSO parameters. Our results, therefore, suggest that the adjustment of SSO parameterization alleviates the Arctic sea ice bias in this case. However, the atmospheric changes induced by the parametrized SSO also impact the ocean, with an equatorward shift of the Northern Hemisphere oceanic gyres and a weaker Atlantic meridional overturning circulation.
Structural and Thermochronologic Constraints on the Cenozoic Tectonic Development of the Northern Indo‐Burma Ranges
Authors: Haproff Peter J. , Odlum Margaret L. , Zuza Andrew V. , Yin An , Stockli Daniel F.
Published: August 2020

The ~1,500‐km‐long, north trending Eastern Flanking Belt of the Himalayan‐Tibetan orogenic system is located along the eastern margin of the Indian subcontinent. Although the belt is a key element of the Cenozoic India‐Asia collisional zone, its tectonic evolution remains poorly understood. This lack of knowledge has impacted our ability to differentiate between competing hypotheses for the evolution of the India‐Asia collision. To address this problem, we integrate constraints on the structural framework and magnitude of Cenozoic shortening strain with thermochronology of the northernmost segment of the belt located directly southeast of the eastern Himalayan syntaxis (i.e., the northern Indo‐Burma Ranges). The study area exposes a southwest directed thrust belt that is bounded by the Indian craton in the west and the right‐slip Jiali fault zone in the east. New and existing (U‐Th)/He and 40Ar/39Ar thermochronologic data indicate that thrust‐related cooling occurred from ~36 Ma in the northeast to ~5.6 Ma in the southwest. Episodes of out‐of‐sequence thrusting occurred at ~30–20, ~14–12, and ~11–6 Ma within the thrust belt. Restoration of the thrust belt yields a minimum horizontal shortening of ~280 km (~86%). These results combined with (1) the recorded local absence of several major Himalayan‐Tibetan lithologic units (i.e., Tethyan Himalayan Sequence, Greater Himalayan Sequence, and southern Gangdese batholith) and (2) the southward decrease in the thrust‐belt width (33–5 km) suggest a complex history of thrusting in the northern Indo‐Burma Ranges and an spatial increase in Cenozoic crustal shortening and/or continental underthrusting from west to east across the eastern Himalayan syntaxis.
A Mn(ii)–MOF with inherent missing metal-ion defects based on an imidazole-tetrazole tripodal ligand and its application in supercapacitors
Authors: Wang Jun , Deng Shu-Qi , Zhao Ting-Ting , Zheng Sheng-Run , Cai Song-Liang , Fan Jun , Zhang Wei-Guang
Published: August 2020

A 3D Mn(ii)–MOF containing unexpected inherent missing metal-ion defects was constructed, and its application on a supercapacitor was studied.
K+ modulated K+/vacancy disordered layered oxide for high-rate and high-capacity potassium-ion batteries
Authors: Xiao Zhitong , Meng Jiashen , Xia Fanjie , Wu Jinsong , Liu Fang , Zhang Xiao , Xu Linhan , Lin Xinming , Mai Liqiang
Published: August 2020

A K+/vacancy disordered structure has been obtained by simply modulating the K+ contents in a series of KxMn0.7Ni0.3O2 layered oxides, which exhibits outstanding rate performance.
Severe Hypocalcemia and Transient Hypoparathyroidism After
Hyperthermic Intraperitoneal Chemotherapy
Authors: Tharmalingam Senthuran , Reddy Sanjay , Sharda Pankaj , Koch Christian A.
Published: August 2020

Dear Editors,

Hypocalcemia is not unusual in patients hospitalized for critical illness and has
also been described after general surgery in addition to head and neck surgical
procedures 1
2
3. Hypocalcemic events commonly
occur in the setting of massive blood transfusion, albumin deficiency, vitamin D
deficiency, and/or hypomagnesemia. In the absence of these factors, only
slight decreases in calcium levels within the normal range have been reported during
surgical procedures 1. Cytoreductive surgery
with hyperthermic intraperitoneal chemotherapy (HIPEC) causing asymptomatic
hypocalcemia has only been reported in two previous studies 4
5.
The etiology is unclear. We here report a patient who developed severe symptomatic
hypocalcemia likely as a result of a profound inflammatory reaction with transient
hypoparathyroidism after HIPEC.
The Lateral Orbitotomy Approach for Intraorbital Lesions
Authors: Lee Ryan P. , Khalafallah Adham M. , Gami Abhishek , Mukherjee Debraj
Published: August 2020

The lateral orbitotomy approach (LOA) was first described by Kronlein in 1888 and has since been subject to many modifications and variations. When considering orbital approaches, the location of the pathology is often more important in decision making than the type of pathology. The LOA is best suited for access to intraconal and extraconal lesions lateral to the optic nerve. Pathologies treated via the LOA include primary orbital tumors, extraorbital tumors with local extension into the orbit, and distantly metastatic lesions to the orbit. These all often initially manifest with vision loss, oculomotor deficits, or proptosis. The expertise of a multidisciplinary team is needed to execute safe and effective treatment. Collaboration between many specialties may be required, including ophthalmology, neurosurgery, otolaryngology, plastic surgery, oncology, and anesthesiology.

The modern technique involves either a lateral canthotomy or eyelid crease incision with removal of the lateral orbital wall. It affords many advantages over a pterional craniotomy, primarily a lower approach morbidity and superior cosmetic outcomes. Reconstruction is fairly simple and the rate of complications—vision loss and extraocular muscle palsy—are low and infrequently permanent. Deep orbital apex location and intracranial extension have traditionally been considered limitations of this approach. However, with increased surgeon comfort, modern technique, and the adoption of endoscopy, these limits have expanded to even include primarily intracranial pathologies. This review details the LOA, including the general technique, its indications and limitations, reconstruction considerations, complications, and recent data from case series. The focus is on microscopic access to intraorbital lesions.
Heterogeneity in Outcome Reporting in Endoscopic Endonasal Skull Base Reconstruction: A Systematic Review
Authors: Dorismond Christina , Santarelli Griffin D. , Thorp Brian D. , Kimple Adam J. , Ebert Charles S. , Zanation Adam M.
Published: August 2020

Objective Presently, there are no standards for reporting outcomes of endoscopic endonasal skull base reconstruction (ESBR). This is problematic as a lack of consistent reporting makes synthesizing findings in systematic reviews and meta-analysis challenging. Thus, the aim of this study was to systematically review and describe the patterns of reporting outcomes in ESBR as a foundation for developing reporting guidelines.

Study Design Present study is a systematic review.

Methods Embase, PubMed, CINAHL, Cochrane Library, and Web of Science were searched for all publications with ≥25 patients and a focus on ESBR. The reporting patterns of each study's variables and outcomes were assessed.

Results A total of 112 studies were included in the review. The most commonly reported demographic variables were the number of included patients (n = 112, 100%) and types of pathologies treated (n = 104, 92.9%). Meanwhile, the most routinely described preoperative variable was history of prior treatment (n = 48, 42.9%). Type of reconstruction was a commonly reported intraoperative variable (n = 110, 98.2%), though the rate of intraoperative cerebrospinal fluid (CSF) leak was noted in only 76 studies (67.9%). With regard to postoperative outcomes, postoperative CSF leak rate was routinely provided (n = 101, 90.2%), but reporting of other surgical complications was more inconsistent. Ultimately, of the 43 variables and outcomes reviewed, a median of 12 (range: 4–22) was reported in each study.

Conclusion There is significant heterogeneity in the outcomes reported in studies relating to ESBR. This highlights the need for the development of standard reporting guidelines to minimize bias and improve interstudy comparability.
Antioxidant Enzyme Levels Inversely Covary with Hearing Loss After Amikacin Treatment
Authors: Klemens James J. , Meech Robert P. , Hughes Larry F. , Somani Satu , Campbell Kathleen C.M.
Published: August 2020

This study's purpose was to determine if a correlation exists between cochlear antioxidant activity changes and auditory function after induction of aminoglycoside (AG) ototoxicity. Two groups of five 250-350 g albino guinea pigs served as subjects. For 28 days, albino guinea pigs were administered either 200 mg/kg/day amikacin, or saline subcutaneously. Auditory brainstem response testing was performed prior to the first injection and again before sacrifice, 28 days later. Cochleae were harvested and superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase activities and malondialdehyde levels were measured. All antioxidant enzymes had significantly lower activity in the amikacin group (p ≤ 0.05) than in the control group. The difference in cochlear antioxidant enzyme activity between groups inversely correlated significantly with the change in ABR thresholds. The greatest correlation was for the high frequencies, which are most affected by aminoglycosides. This study demonstrates that antioxidant enzyme activity and amikacin-induced hearing loss significantly covary.
The Effect of D-Methionine on Cochlear Oxidative State with and without Cisplatin Administration: Mechanisms of Otoprotection
Authors: Campbell Kathleen C.M. , Meech Robert P. , Rybak Leonard P. , Hughes Larry F.
Published: August 2020

D-methionine (D-met) protects against cisplatin (CDDP) ototoxicity, but the mechanisms are not well understood. This study investigated D-met protection of cochlear oxidative state as measured by superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), and malondiadehyde (MDA) levels. The design comprised four groups of five rats each: (1) a saline control group, (2) a CDDP-only-treated group, (3) a CDDP group pretreated with D-met, and (4) a group receiving only D-met. Auditory brainstem response testing (ABR) was performed before and 3 days after injection. CDDP alone caused marked hearing loss; significantly reduced SOD, CAT, and GR levels; and increased MDA levels, but D-met pretreatment protected against these changes. These studies suggest that D-met protects cochlear antioxidant enzyme levels from CDDP-induced decrements. The excellent correlation of enzyme levels with hearing loss and weight loss suggests that antioxidant enzyme level protection may underlie, at least in part, D-met's otoprotective action.
Audiologic Monitoring for Potential Ototoxicity in a Phase I Clinical Trial of a New Glycopeptide Antibiotic
Authors: Campbell Kathleen C.M. , Kelly Ellen , Targovnik Nan , Hughes Larry , Van Saders Claudia , Gottlieb Alice Bendix , Beth Dorr Mary , Leighton Anton
Published: August 2020

This study describes audiologic methodology and results for evaluating potential ototoxicity in a phase I clinical trial of a new glycopeptide. This study was conducted under good clinical practices, which are regulated by the US Food and Drug Administration (FDA) (21 Code of Federal Regulations), and input from the FDA was sought prior to study implementation. Healthy, normal volunteers underwent extensive medical and audiologic assessments as part of this phase I dose- escalation study of dalbavancin, a new glycopeptide, to assess potential side effects. Audiologic monitoring included air-conduction thresholds in the conventional (0.25-8 kHz) and high-frequency (10-16 kHz) ranges. At baseline, subjects were also tested using word recognition, bone conduction testing if indicated, and tympanometry. Full testing was to be repeated if any subject met the American Speech-language-Hearing Association (ASHA) 1994 criteria for ototoxic change. However, no subjects demonstrated ototoxic change after receiving dalbavancin, nor were any false-positive results obtained.
Outcomes of Cochlear Implantation in Children with Auditory Neuropathy
Authors: Peterson Ann , Shallop Jon , Driscoll Colin , Breneman Alyce , Babb Julie , Stoeckel Ruth , Fabry Lee
Published: August 2020

Ten children who were diagnosed with auditory neuropathy were matched with ten children who were diagnosed with other etiologies. All twenty children received cochlear implants at the Mayo Clinic in Rochester, Minnesota. Various measures were used to compare the outcomes for the two groups. We compared the children's unaided and aided audiograms, and measures of threshold and comfort levels. Performance on age appropriate speech perception tests was measured. Electrically elicited auditory brainstem response, predicted Neural Response Telemetry thresholds, and visually detected electrical stapedius reflexes were compared. Parental report of cochlear implant benefit was evaluated using either the Meaningful Auditory Integration Scale or the Infant-Toddler Meaningful Auditory Integration Scale depending on the age of the child. We also compared educational placement and communication mode. The results of this study demonstrated that there were no important differences in cochlear implant benefit between the two groups. In light of these findings, we support the use of cochlear implants as a viable option for selected children with auditory neuropathy.
Autoimmune Inner Ear Disease: Diagnostic and Therapeutic Approaches in a Multidisciplinary Setting
Authors: Matteson Eric L. , Fabry David A. , Strome Scott E. , Driscoll Colin L. W. , Beatty Charles W. , McDonald Thomas J.
Published: August 2020

Autoimmune Inner Ear Disease (AIED) is a clinical syndrome of uncertain pathogenesis. It is associated with bilateral rapidly progressive hearing loss. The hearing loss may be associated with vestibular symptoms. Autoimmunity has been proposed as the pathogenesis of this sort of hearing loss, although the mechanism of the disease is poorly understood. It is well accepted that the endolymphatic sac is an immunocompetent organ and circulating autoantibodies against inner ear antigens have been reported, as have viral antigens in the endolymph, although the sensitivity, specificity, and roles of those antibodies in a disease process are poorly defined.

We will describe the clinical aspects of the disease, the histopathology, the immunologic indicators, the types of presentation, both from the audiologic and vestibular point of view, clinical trials for treatment and the follow-up. One of our conclusions is that many of these patients respond favorably to the treatment Methotrexate.
Agreement between Functional and Electrophysiologic Measures in Patients with Unilateral Peripheral Vestibular System Impairment
Authors: Jacobson Gary P. , McCaslin Devin L.
Published: August 2020

This investigation was conducted to determine whether there was congruence between "physiology-based" definitions of compensated and uncompensated unilateral peripheral vestibular system impairment and "functional" measures of self-perceived dizziness disability/handicap. A retrospective analysis was performed on data obtained from 122 patients evaluated in the Balance Function Laboratory at Henry Ford Hospital over a 4-year period. Both electronystagmography and rotational test data were tabulated. Additionally, results of a self-report measure of dizziness disability/handicap were tabulated. Patients were placed into four groups, with one group representing normal vestibulometric test results, one group representing compensated unilateral peripheral vestibular system impairment, and two groups representing increasing magnitudes of uncompensated unilateral peripheral vestibular system impairment. The total and subscale scores on the self-report measure served as the dependent variable. Results showed a lack of congruence between the physiologic and functional measures. We interpret these findings as evidence that factors other than semiobjective evidence of vestibular system compensation probably impact functional recovery following unilateral peripheral vestibular system impairment.
Localization of the P2Y4 Receptor in the Guinea Pig Organ of Corti
Authors: Parker Margarett S. , Onyenekwu Nkeiruka N. , Bobbin Richard P.
Published: August 2020

Cochleae of guinea pigs were evaluated for the presence of the metabotropic receptor, P2Y4. Evidence is presented that P2Y4 protein is expressed in the guinea pig cochleae using Western blot analysis. A single protein band of 35 kDa was detected with P2Y4 receptor-specific antibody. The cellular distribution of P2Y4 purinoceptor protein was determined by immunohistochemistry of the whole organ of Corti. Immunoreactive staining for P2Y4 was seen in most cells of the organ of Corti. Staining of Hensen's cells and Deiters' cells, especially the outer Deiters' cells, was more intense than staining of the outer hair cells, inner hair cells, and pillar cells. Staining intensity was greatest at the basal turn and progressively decreased in the upper turns with the apex showing the weakest staining pattern. This is the first demonstration of a metabotropic P2Y receptor in the guinea pig organ of Corti.
Patients with Auditory Neuropathy/Dys-synchrony Lack Efferent Suppression of Transient Evoked Otoacoustic Emissions
Authors: Hood Linda J. , Berlin Charles I. , Bordelon Jill , Rose Kelly
Published: August 2020

Function of the olivocochlear reflex, measured by suppression of transient evoked otoacoustic emissions, is assessed in nine patients with bilateral auditory neuropathy/dys-synchrony and compared to matched control subjects with normal auditory function. TEOAEs were acquired using 65 dB peak sound pressure linear clicks with and without the presence of broad-band noise presented binaurally, ipsilaterally, or contralaterally in a forward masking paradigm. Efferent suppression differed significantly between subject groups (p < .0001). Mean suppression was less than 0.22 dB across all suppressor noise conditions for the auditory neuropathy/dys-synchrony subjects. TEOAE suppression averaged 4.47 (binaural), 2.41 (ipsilateral), and 1.52 (contralateral) dB in the control subjects. Suppression characteristics across the three suppressor conditions were also assessed in one patient with unilateral auditory neuropathy/dys-synchrony. The results suggest that poor efferent responses are related to compromised afferent input to the OCR pathway and support the use of efferent suppression of otoacoustic emissions as a differential measure of auditory function in patients with auditory neuropathy/dys-synchrony.
Olivocochlear Efferent Suppression in Classical Musicians
Authors: Brashears Shanda M. , Morlet Thierry G. , Berlin Charles I. , Hood Linda J.
Published: August 2020

Suppression of transient-evoked otoacoustic emissions was recorded from 29 members of the Louisiana Philharmonic Orchestra and 28 non-musician control subjects matched for age and gender. Binaural broad band noise was used as the suppressor stimulus in a forward masking paradigm. Results showed musicians to have significantly more suppression than non-musicians for both the right and left ears. Two possible explanations for this functional difference between groups are that moderately loud music serves as a sound conditioning stimulus and that music can be a mechanism for strengthening central auditory pathways which may influence the olivocochlear reflex arc. Possible explanations for this are discussed and ear, gender, and age differences within each group are examined. Additionally, middle-ear muscle reflex thresholds were found to be higher in musicians than non-musicians at some frequencies in some conditions.
Active Hair Bundle Movements and the Cochlear Amplifier
Authors: Ricci Anthony
Published: August 2020

The “active process” is a term used to describe amplification and filtering processes that are essential for obtaining the exquisite sensitivity of hearing organs. Understanding the components of the active process is important both for our understanding of the normal physiology of hearing and because perturbations of the cochlear amplifier may lead to such maladies as threshold shifts (both temporary and permanent), tinnitus, sensorineural hearing loss and presbicusis. To date the cochlear amplifier has largely been attributed to outer hair cell electro motility; however, recent evidence suggests, that active properties of the hair bundle may also be important. Most likely both somatic motility and active hair bundle movements contribute to establishing the cochlear active process. This paper reviews recent evidence regarding known active processes in the hair bundle gating compliance, and fast and slow adaptation.
Development of Auditory Asymmetry in Transient Evoked Otoacoustic Emissions in Pre-Term Infants
Authors: Morlet Thierry , Durrant J. D. , Lapillonne A. , Putet G. , Collet L. , Duclaux R.
Published: August 2020

We previously reported that transient evoked otoacoustic emissions (TEOAEs) continue to develop after the onset of cochlear function in pre-term infants from 34 to 39 weeks of conceptional age (Morlet et al., 1996). The time-course of development differed between genders. Reported here are findings of further analysis of data from the study cohort, comprising 1020 ears of 510 pre-term neonates (conceptional age ranging from 34 to 39 weeks), demonstrating developmental differences between right and left ears. The left ear of female pre-term infants showed enhancement of TEOAE amplitude at low and medium frequencies with age, whereas differences were less dramatic in the right ear. In male infants, TEOAE amplitude decreased in several frequency bands at high frequencies, above 4 kHz, between 34 and 39 weeks conceptional age; most developmental differences were found to be more dramatic in the right than in the left ear. It is tempting to speculate that these developmental features underlie well-known inter-aural asymmetries that have been demonstrated in the adult human.
Hearing Aid Troubleshooting Based on Patients' Descriptions
Authors: Jenstad Lorienne M. , Van Tasell Dianne J. , Ewert Chiquita
Published: August 2020

Clinical audiologists were surveyed to determine the terms that their patients use to describe their reaction to hearing aid fitting problems. From this survey, a vocabulary of 40 frequently reported terms was developed. A second survey of hearing aid fitting experts was conducted to determine their methods of troubleshooting a hearing aid fitting when the patient reports one of the frequently reported terms. There was a high degree of agreement among the 24 experts. Principal components analysis resulted in ten components that explained 90.8% of the variance in the experts' responses. These results can be applied as an expert system for fine-tuning hearing aid fittings.
Norms for the International Outcome Inventory for Hearing Aids
Authors: Cox Robyn M. , Alexander Genevieve C. , Beyer Cynthia M.
Published: August 2020

The International Outcome Inventory for Hearing Aids (IOI-HA) is a seven-item survey that was developed for use in research settings to facilitate comparison of data across diverse investigations. The inventory also has potential applications in clinical evaluation of hearing aid fitting outcomes. This article reports the development of norms for the inventory that are suitable for use with group data in research applications, and individual data in a clinical setting. The normative group was defined as adults fitted bilaterally with analog, single-channel, single-memory, compression processing, in-the-ear hearing aids. There were 154 subjects. Associations between outcomes and demographic variables (e.g., gender, hearing loss, etc.) were explored, and several relationships were seen. Based on these data, two sets of norms were derived. The appropriate set will depend on the individual's reported subjective hearing problems without amplification.
Neuroelectric Correlates of Hemispheric Asymmetry: Spectral Discrimination and Stimulus Competition
Authors: Greenwald Ralf R. , Jerger James
Published: August 2020

In an effort to explore further the role of the right hemisphere in auditory processing, this study utilized brain event-related potentials (ERPs) to investigate hemispheric asymmetry for the processing of complex spectral tones. Subjects participated in two pitch discrimination tasks, one diotic, the other dichotic. ERP components were recorded from 28 electrodes on the scalp and analyzed via individual/group average area measurements. Results showed that ERPs recorded in response to the dichotic target pairs exhibited a larger P3 area when the target tone was presented to the left ear, while the N1 area showed no significant difference. ERPs recorded in the diotic condition showed a larger P3 area and smaller N1 area compared to the dichotic conditions. Finally, all experimental tasks showed that topographic hemispheric activation patterns were asymmetric to the right hemisphere. Findings support the notion that ERP topographic asymmetries may be dependent on specific cognitive task demands (e.g., diotic vs. dichotic modes of presentation). In addition, the data suggest that the P3 component may better reflect interaural advantages for complex tones than the N1 component and may, therefore, be a more sensitive indicator of hemispheric specialization.
Distortion Product Otoacoustic Emissions: Comparison of Sequential versus Simultaneous Presentation of Primary-Tone Pairs
Authors: Beattie Randall C.
Published: August 2020

This Grason-Stadler GSI-60 system for measuring distortion product otoacoustic emissions (DPOAEs) allows the examiner to present one set of primary-tone pairs at a time (i.e., sequential presentation), or to present as many as four sets of primary-tone pairs at a time (i.e., simultaneous presentation). The Sequential and Simultaneous protocols were used to compare administration times, DPOAEs, and noise floors (NFs) on normal-hearing subjects at three frequencies (f2 = 1000, 2000, and 4000 Hz) and eight intensities (L1 = 40–75 dB SPL in 5 dB steps; L2 = 30–65 dB SPL). The Simultaneous protocol was completed in less than half the time (mean = 2 minutes, 21 seconds) required for the Sequential protocol (mean = 5 minutes, 13 seconds). When stimulus intensity (L1) was <60 dB SPL, the Sequential and Simultaneous protocols yielded similar DPOAEs and NFs. However, at the higher L1 intensities, the NFs for the Simultaneous protocol were larger than those for the Sequential protocol. The higher Simultaneous NFs reflect the greater system distortion/noise generated by the GSI-60 instrumentation. Reliability was assessed using the standard error of measurement of the difference between two scores. The data revealed no significant differences between protocols, and suggest that differences between two DPOAEs are statistically significant if they exceed ~7 dB (95% confidence interval). Este sistema Grason-Stadler (GSI-60) para la medición de emisiones otoacústicas por productos de distorsión (DPOAE) permite al examinador la presentación de un juego de pares de tonos primarios al mismo tiempo (p.e., presentación secuencial), o presentar hasta cuatro juegos de pares de tonos primarios a la vez (p.e., presentación simultánea). Se utilizaron los protocolos Secuencial y Simultáneo para comparar los tiempos de administración, las DPOAE y los pisos de ruido (NF) en sujetos normo-oyentes, en tres frecuencias (f2 = 1000, 2000 y 4000 Hz) y ocho intensidades (L1 = 40-75 dB en pasos de 5 dB; L2 = 30-65 dB SPL). El protocolo Simultáneo se completó en menos de la mitad del tiempo (media = 2 minutos, 21 segundos) requerido por el protocolo Secuencial (media = 5 minutos, 13 segundos). Cuando la intensidad del estímulo (L1) fue £60 dB SPL, los protocolos Secuencial y Simultáneo rindieron DPOAE y NF similares. Sin embargo, en las intensidades L1 más altas, los NF para el protocolo Simultáneo fueron mayores que aquellas para el protocolo Secuencial. Los NF Simultáneos más altos reflejan la mayor distorsión/ruido del sistema, generado por la instrumentación del GSI-60. La confiabilidad fue evaluada utilizando el error estándar de medición de la diferencia entre los dos puntajes. Los datos revelaron que no había diferencias significativas entre los protocolos, y sugieren que las diferencias entre dos DPOAE son estadísticamente significativas si exceden ~7 dB (intervalo de confianza del 95%).
Asymmetry in Event-Related Potentials to Simulated Auditory Motion in Children, Young Adults, and Seniors
Authors: Jerger James , Estes Rebecca
Published: August 2020

We studied auditory evoked responses to the apparent movement of a burst of noise in the horizontal plane. Event-related potentials (ERPs) were measured in three groups of participants: children in the age range from 9 to 12 years, young adults in the age range from 18 to 34 years, and seniors in the age range from 65 to 80 years. The topographic distribution of grand-averaged ERP activity was substantially greater over the right hemisphere in children and seniors but slightly greater over the left hemisphere in young adults. This finding may be related to age-related differences in the extent to which judgments of sound movement are based on displacement versus velocity information.
Observations on the Relations among Occlusion Effect, Compliance, and Vent Size
Authors: Carle Roberto , Laugesen Søren , Nielsen Claus
Published: August 2020

In a clinical experiment, it was found that there is a high correlation between the compliance measured by tympanometry and the minimum size of the earmold vent, which just solves the client's occlusion problem related to his/her own voice when using a hearing aid. For ears with sensorineural hearing losses, compliance explained 59 percent of the variation in vent size, whereas the average low-frequency hearing loss explained as little as 0.3 percent. In a laboratory experiment, the objective occlusion effect measured with the participants' own voices showed a similar relationship with compliance. Whereas the former relationship between compliance and vent size may be explained by a simple model, the latter relationship turns out to be the opposite of what a firstorder model predicts. Hence, compliance must be indicative of another aspect of the occlusion mechanism, which has a more profound influence on the observed occlusion effect than compliance itself.
A Test to Measure Subjective and Objective Speech Intelligibility
Authors: Saunders Gabrielle H. , Cienkowski Kathleen M.
Published: August 2020

Measurement of hearing aid outcome is particularly difficult because there are numerous dimensions to consider (e.g., performance, satisfaction, benefit). Often there are discrepancies between scores in these dimensions. It is difficult to reconcile these discrepancies because the materials and formats used to measure each dimension are so very different. We report data obtained with an outcome measure that examines both objective and subjective dimensions with the same test format and materials and gives results in the same unit of measurement (signal-to-noise ratio). Two variables are measured: a “performance” speech reception threshold and a “perceptual” speech reception threshold. The signal-to-noise ratio difference between these is computed to determine the perceptual-performance discrepancy (PPDIS). The results showed that, on average, 48 percent of the variance in subjective ratings of a hearing aid could be explained by a combination of the performance speech reception threshold and the PPDIS. These findings suggest that the measure is potentially a valuable clinical tool.
Temporally Jittered Speech Produces Performance Intensity, Phonetically Balanced Rollover in Young Normal-Hearing Listeners
Authors: Miranda Terence T. , Pichora-Fuller M. Kathleen
Published: August 2020

This study investigates whether temporally jittered stimuli will produce performance-intensity, phonetically balanced (PI-PB) rollover in young adults with normal hearing. Although not yet explicitly stated in the literature, there is clinical and theoretical evidence to suggest that PI-PB rollover, such as that found in cases of acoustic neuroma, is caused by neural dyssynchrony in the auditory system. Sixteen participants were tested with intact and temporally jittered word lists in quiet at 40, 55, 65, and uncomfortable listening level −5 dB HL. The results show significant rollover in the jittered but not the intact conditions. The results are consistent with the existing evidence that suggests that neural PI-PB rollover is caused by decreased neural synchrony and support the claim that temporal jitter simulates neural dyssynchrony. Furthermore, these results are consistent with the hypothesis that synchrony coding plays an important role in the perception of high-level speech.
Diagnostic Implications of Stimulus Polarity Effects on the Auditory Brainstem Response
Authors: Fowler Cynthia G. , Bauch Christopher D. , Olsen Wayne O.
Published: August 2020

The purpose of this study was to determine whether clicks presented in rarefaction or condensation modes produce more accurate diaghostic information. Subjects were 20 consecutive patients who were seen at the Mayo Clinic for unilateral acoustic neuromas. The nontumor ear served as a control to minimize intersubject variability in the latencies. A standard audio logic evaluation was followed by an auditory brainstem response (ABR) test for which the stimuli were rarefaction and condensation clicks. Responses were analyzed for the presence of waves I, III, and V; absolute latencies of waves I, III, and V; interpeak intervals I–III, III–V, and I–V; and interaurallatency difference for wave V. The results indicated that measures from both polarities were similar in this set of patients and that neither click polarity provided diagnostic advantages over the other. Recommendations are to collect ABRs to both click polarities individually to obtain the full complement of waves on which to base the diagnostic impression.