Behavioral Thresholds Research Articles

Freely Suspended Semiflexible Chains in a Strong Aligning Field: Simple Closed‐Form Solutions for the Small‐Angle Approximation

AbstractA worm‐like chain model for a single, freely suspended semiflexible macromolecule with an aligning field of arbitrary coupling order is presented. Using a small‐angle approximation and Ginzburg–Landau theory, exact closed‐form solutions of the model are derived in the regime of a strong aligning field in arbitrary dimensions. Expressions for the mean cosine of the chain alignment angle, orientational order parameters, and the two‐point correlation function are found. As a corollary, the persistence length is confirmed as a valid threshold for rigid behavior of the chain. The theoretical results are validated with Monte Carlo simulations in two and three dimensions. It is shown that the solutions for the small‐angle approximation are within of the simulated values for the exact model for chain‐field alignment angles θ ≲ 20°. As a practical application, the findings are applied to carbon nanotubes in an aligning electric field.

Interaction Between Electric and Acoustic Stimulation Influences Speech Perception in Ipsilateral EAS Users.

Objectives:The aim of this study was to determine electric-acoustic masking in cochlear implant users with ipsilateral residual hearing and different electrode insertion depths and to investigate the influence on speech reception. The effects of different fitting strategies—meet, overlap, and a newly developed masking adjusted fitting (UNMASKfit)—on speech reception are compared. If electric-acoustic masking has a detrimental effect on speech reception, the individualized UNMASKfit map might be able to reduce masking and thereby enhance speech reception.Design:Fifteen experienced MED-EL Flex electrode recipients with ipsilateral residual hearing participated in a crosssover design study using three fitting strategies for 4 weeks each. The following strategies were compared: (1) a meet fitting, dividing the frequency range between electric and acoustic stimulation, (2) an overlap fitting, delivering part of the frequency range both acoustically and electrically, and (3) the UNMASKfit, reducing the electric stimulation according to the individual electric-on-acoustic masking strength. A psychoacoustic masking procedure was used to measure the changes in acoustic thresholds due to the presence of electric maskers. Speech reception was measured in noise with the Oldenburg Matrix Sentence test.Results:Behavioral thresholds of acoustic probe tones were significantly elevated in the presence of electric maskers. A maximum of masking was observed when the difference in location between the electric and acoustic stimulation was around one octave in place frequency. Speech reception scores and strength of masking showed a dependency on residual hearing, and speech reception was significantly reduced in the overlap fitting strategy. Electric- acoustic stimulation significantly improved speech reception over electric stimulation alone, with a tendency toward a larger benefit with the UNMASKfit map. In addition, masking was significantly inversely correlated to the speech reception performance difference between the overlap and the meet fitting.Conclusions:(1) This study confirmed the interaction between ipsilateral electric and acoustic stimulation in a psychoacoustic masking experiment. (2) The overlap fitting yielded poorer speech reception performance in stationary noise especially in subjects with strong masking. (3) The newly developed UNMASKfit strategy yielded similar speech reception thresholds with an enhanced acoustic benefit, while at the same time reducing the electric stimulation. This could be beneficial in the long-term if applied as a standard fitting, as hair cells are exposed to less possibly adverse electric stimulation. In this study, the UNMASKfit allowed the participants a better use of their natural hearing even after 1 month of adaptation. It might be feasible to transfer these results to the clinic, by fitting patients with the UNMASKfit upon their first fitting appointment, so that longer adaptation times can further improve speech reception.

Identifying Cochlear Implant Channels With Relatively Poor Electrode-Neuron Interfaces Using the Electrically Evoked Compound Action Potential.

The primary objective of this study was to quantify local (within ear) and global (between ear) variation in the cochlear implant (CI) electrode-neuron interface (ENI) using the electrically evoked compound action potential (ECAP). We tested the hypothesis that, within an ear, ECAP measures can be used to identify channels with presumed good and poor ENIs, which may be influenced by a combination of spiral ganglion neuron (SGN) density, electrode position, and cochlear resistivity. We also hypothesized that ECAP responses would reflect age-related differences in the global quality of the ENI between younger and older listeners who theoretically differ in SGN density. Data were obtained from 18 implanted ears (13 individuals) with Advanced Bionics HiRes 90K devices. Six participants (8 ears) were adolescents or young adults (age range: 14-32 years), and 7 participants (10 ears) were older adults (age range: 54-88 years). In each ear, single-channel auditory detection thresholds were measured on channels 2 through 15 in response to a spatially focused electrode configuration (steered quadrupolar; focusing coefficient = 0.9). ECAP amplitudes, amplitude growth function (AGF) slopes, and thresholds were assessed on a subset of channels in each ear in response to three interphase gaps (0, 7, and 30 µs). ECAP peak amplitudes were assessed on all channels between 2 and 15. AGFs and ECAP thresholds were measured on the two nonadjacent channels with the lowest and highest focused behavioral thresholds in each ear. ECAP responses were compared across low- and high-threshold channels and between younger and older CI listeners. Channels that were estimated to interface poorly with the auditory nerve (i.e., high-focused-threshold channels) had steeper ECAP AGF slopes, smaller dynamic ranges, and higher ECAP thresholds than channels with low focused thresholds. Younger listeners had steeper ECAP AGF slopes and larger ECAP peak amplitudes than older listeners. Moreover, younger listeners showed greater interphase gap sensitivity for ECAP amplitude than older listeners. ECAP responses may be used to quantify both local (within ear) and global (between ear) variation in the quality of the ENI. Results of this study support future investigation into the use of ECAP responses in site-selection CI programming strategies. The present results also support a growing body of evidence suggesting that adolescents and young adults with CIs may have denser populations of functional SGNs relative to older adults. Potential differences in global SGN integrity between younger and older listeners warrant investigation of optimal CI programming interventions based on their divergent hearing histories.

An integrative approach for pediatric auditory neuropathy spectrum disorders: revisiting etiologies and exploring the prognostic utility of auditory steady-state response

Auditory neuropathy is an important entity in childhood sensorineural hearing loss. Due to diverse etiologies and clinical features, the management is often challenging. This study used an integrative patient-history, audiologic, genetic, and imaging-based approach to investigate the etiologies and audiologic features of 101 children with auditory neuropathy. Etiologically, 48 (47.5%), 16 (15.8%), 11 (10.9%), and 26 (25.7%) children were categorized as having acquired, genetic, cochlear nerve deficiency-related, and indefinite auditory neuropathy, respectively. The most common causes of acquired and genetic auditory neuropathy were prematurity and OTOF mutations, respectively. Patients with acquired auditory neuropathy presented hearing loss earlier (odds ratio, 10.2; 95% confidence interval, 2.2–47.4), whereas patients with genetic auditory neuropathy had higher presence rate of distortion product otoacoustic emissions (odds ratio, 10.7; 95% confidence interval, 1.3–85.4). In patients with different etiologies or pathological sites, moderate to strong correlations (Pearson’s r = 0.51–0.83) were observed between behavioral thresholds and auditory steady-state response thresholds. In conclusion, comprehensive assessments can provide etiological clues in ~75% of the children with auditory neuropathy. Different etiologies are associated with different audiologic features, and auditory steady-state responses might serve as an objective measure for estimating behavioral thresholds.

Japanese quail (Coturnix japonica) audiogram from 16Hz to 8kHz.

The purpose of this study was to determine if the Japanese quail, a domesticated, gallinaceous bird, could detect infrasound. Behavioral thresholds were determined for three birds, two males and one female, ranging from 16Hz to 8kHz. The animals' hearing range, at a cutoff of 60dB SPL (re 20 μN/m2), covers 6.88 octaves, ranging from 59.5Hz to 7kHz. All animals had the greatest sensitivity to 2kHz, with an average threshold of 4.4dB SPL. Although the birds' threshold at 16Hz was equivalent to that of humans, at no frequency did the birds' sensitivity ever exceed that of humans. Therefore, the Japanese quail does not hear infrasound.

Effect ranges of underwater noise from anchor vibration operations in the Wadden Sea

Anchor pipe vibration embedment operations during the construction of seed mussel collectors were performed in the Wadden Sea, a designated World Heritage Site by UNESCO in 2009. We recorded 200 min of underwater noise during the construction of seven anchor pipes. Underwater noise was recorded simultaneously at three positions with a water depth of 9 m with increasing distance to the construction site to assess the disturbance potential to the marine fauna. The recorded vibration embedment noise was a continuous sound with durations of 2–55 s, with most energy below 1 kHz and peak frequencies around 900 Hz. Background noise level at a distance of approximately 1 km increased around 13 dB at frequencies between 800 and 1000 Hz. We estimated the sound propagation by a non-linear logarithmic regression by means of the intercept, slope and attenuation factor, which allowed us to evaluate the received sound levels that reach an animal in certain distances from the construction site. The estimated sound exposure level (SEL) of the source was 148.2 dB re 1 μPa2s and the median SEL ranged from 120 to 99 dB re 1 μPa2s at distances between 394 and 2288 m, respectively. Behavioural thresholds for indigenous species of marine mammals in the Wadden Sea as well as representative fish species were used to determine effect radii of vibration embedment noise. Our study showed that the detected anchor pipe vibration embedment noise might exert a behavioural reaction on a local scale. Marine mammals could be affected by the construction operations up to a distance of 375 m and fish up to a distance of 766 m. These zones of responsiveness for vibration embedment operations are relatively small, compared to pile driving, which is regularly used during construction operations. Our study shows that it is important to monitor and assess any kind of noise introduction to verify, whether a sustainable human use with respect to the complied guidelines is ensured without affecting the marine fauna. That is the first step to maintain a good environmental status as implemented in the MSFD.

Decision making in the face of a deadly predator: high-amplitude behavioural thresholds can be adaptive for rainforest crickets under high background noise levels.

Many insect families have evolved ears that are adapted to detect ultrasonic calls of bats. The acoustic sensory cues indicating the presence of a bat are then used to initiate bat avoidance behaviours. Background noise, in particular at ultrasonic frequencies, complicates these decisions, since a response to the background may result in costly false alarms. Here, we quantify bat avoidance responses of small rainforest crickets (Gryllidae, Trigoniinae), which live under conditions of high levels of ultrasonic background noise. Their bat avoidance behaviour exhibits markedly higher thresholds than most other studied eared insects. Their responses do not qualitatively differ at suprathreshold amplitudes up to sound pressure levels of 105 dB. Moreover, they also exhibit evasive responses to single, high-frequency events and do not require the repetitive sequence of ultrasonic calls typical for the search phase of bat echolocation calls. Analysis of bat and katydid sound amplitudes and peak frequencies in the crickets' rainforest habitat revealed that the cricket's behavioural threshold would successfully reject the katydid background noise. Using measurements of the crickets' echo target strength for bat predators, we calculated the detection distances for both predators and prey. Despite their high behavioural threshold, the cricket prey still has a significant detection advantage at frequencies between 20 and 40 kHz. The low-amplitude bat calls they ignore are no predation threat because even much louder calls would be detected before the bat would hear the cricket echo. This leaves ample time for evasive actions. Thus, a simple decision criterion based on a high-amplitude behavioural threshold can be adaptive under the high background noise levels in nocturnal rainforests, in avoiding false alarms and only missing detection for bat calls too far away to pose a risk. This article is part of the theme issue 'Signal detection theory in recognition systems: from evolving models to experimental tests'.

The limitation of risk factors as a means of prognostication in auditory neuropathy spectrum disorder of perinatal onset

ObjectiveThe management of hearing loss due to auditory neuropathy spectrum disorder (ANSD) in neonates and infants is challenging because speech and language development prognosis cannot be directly inferred from early audiometric hearing thresholds. Consequently, appropriate intervention with hearing aids or cochlear implantation (CI) can be delayed. Our objective was to determine whether any features of patient history could be used to identify CI candidates with ANSD at an earlier age. MethodA database was maintained over 11 years to monitor cases of perinatal onset ANSD. Risk factors associated with the perinatal time period considered pertinent to hearing outcomes were assessed, including prematurity, birth weight, APGAR score, ototoxic drugs, and hyperbilirubinemia. Children with cochlear nerve aplasia and genetic mutations were excluded. Hearing outcome was determined according to mode of auditory rehabilitation beyond 30 months of age: A) no hearing device; B) hearing aid; C) CI. ResultsOf twenty-eight children with ANSD, nine (32%) had behavioural thresholds and language development sufficient to require no assistive device, 9 (32%) were fitted with hearing aids and 10 (36%) had CIs. The average age at CI (3.45 ± 2.07 years) was significantly older than the age at CI of other children in our program with prelingual hearing loss (2.05 ± 1.14 years; p = 0.01 Mann-Witney U Test). None of the putative risk factors for hearing loss reliably predicted the need for subsequent CI. ConclusionThe small sample size in this study is sufficient to confirm that clinical history alone does not reliably predict which young children with perinatal-onset ANSD will require CI. Consequently, timing for CI remains delayed in these children, potentially affecting speech and language outcome. The pathogenesis of perinatal-onset ANSD remains undetermined and novel means of assessment are required for prognostication in affected infants.

The comparison of changes in hearing thresholds and insertion losses due to occlusion induced by ear impression in sound field assessment

Background and Aim: The methods of deter­mining the amount of sound attenuation by ear mold, earplug or any other foreign body that placed in or out of the ear canal, is divided in subjective and objective. Due to the contradic­tory results in the studies in this field, this study aimed to use more audiometric frequencies con­sidering the strengths and weaknesses of previ­ous studies. Methods: This study was conducted on 30 indi­viduals with normal hearing in the age range of 21-26-year-old. First the impression mold was prepared from both ears. The evaluating real ear unaided response and the real ear occluded res­ponse. In the next step, hearing thresholds were assessed by sound field with a precision of 1 dB, once in both open ear and once in both clo­sed ears. Finally, the insertion loss due to mold placement at each frequency was compared with the amount of behavioral threshold changes at the same frequency. Results: By using paired t-test at frequencies of 400, 500, 800, 1000, 1500, 1600, 2000, 2500, 3000, 4000, 5000, 6000, 6300 and 8000 Hz, the difference in behavioral hearing thresholds with and without molding was greater than the amo­unt of the insertion loss (p < 0.001). Conclusion: The insertion loss due to impre­ssion for behavioral assessment at all of the tes­ted frequencies were more than the attenuation in real ear evaluation (p < 0.001). In this regard, consequently the standard deviation of insertion loss due to impression in behavioral threshold condition was more than real ear measurement. Keywords: Sound field assessment; insertion loss; real ear occluded response; ear impression; probe microphone measurement; real ear measurement

Diagnostic accuracy of CE Chirp

ObjectiveThere has been an increase in the use of the CE-Chirp stimulus in automated auditory brainstem response (AABR) equipment for neonatal hearing screening. The purpose of this study is to evaluate the diagnostic accuracy of the LS CE-Chirp-evoked auditory brainstem response (ABR) compared to the click-evoked ABR for the identification of different degrees and configurations of sensorineural (SNHL) hearing loss. Method49 ears with mild to moderate SNHL were assessed: 16 ears with rising SNHL and 33 ears with sloping high frequency SNHL. Behavioural pure tone thresholds were obtained at 125–8000 Hz and ABR thresholds were measured using the click and LS CE-Chirp stimuli respectively. Click- and LS CE-Chirp-evoked thresholds were compared with each other and with behavioural pure tone average at 500, 1000, 2000 Hz (PTA), high frequency average at 2000, 4000, 8000 Hz (HFA) and low frequency average at 250, 500, 1000 Hz (LFA). Diagnostic accuracy of the two ABR stimuli was also compared by using ROC curves. ResultsDifferences between click- and LS CE Chirp-evoked ABR, and behavioural thresholds were not statistically significant (p > 0.05). The highest significant correlations for ABR using clicks to behavioural thresholds was found at 2000 and 4000 Hz, whereas, the highest correlation for LS CE-Chirp ABRs to behavioural thresholds was found at 1000, 2000 and 4000 Hz (r > 0.7, p < 0.001). A very strong, positive correlation was found between both click (r = 0.805, p < 0.001) and LS CE-Chirp (r = 0.825, p < 0.001) and the behavioural PTA. LS CE-Chirp ABR thresholds were closer to mid and low frequency thresholds than the click ABR while the click-evoked thresholds were in closer proximity to HFA. Sensitivity and specificity and false negative rates were identical. Diagnostic accuracy of the LS CE-Chirp ABR was equal to or better than click for low (area under the curve (AUC) = 0.83), mid (AUC = 0.89) and high frequency hearing losses (AUC = 0.73). However, scatterplots indicated more frequent underestimation of behavioural pure tone thresholds at mid and high frequencies with the LS CE-Chirp than for the click ABR. ConclusionThe diagnostic accuracy of the LS CE Chirp-evoked ABR is equivalent or better than the click-evoked ABR. The importance of ongoing surveillance and consideration of ABR screening protocols is consequently emphasized.

Anger in lineup identification and creation

SummaryAs an approach‐oriented emotion, anger appears to affect behavioral thresholds in a range of contexts. The current work consists of three experiments examining this in the context of eyewitness identification procedures. Experiments 1 and 2 examined the relationship between a witness' anger and identification reliability, and Experiment 3 examined the relationship between a lineup creator's anger and the quality of selected lineup fillers. Experiments 1 and 2 showed that anger during an identification procedure is associated with increased risk of false identifications and reduced confidence‐accuracy calibration. Experiment 3 showed that anger is associated with lower quality of fillers selected by lineup creators. Together, these experiments suggest that anger may undermine the quality of eyewitness evidence, even when the witnesses themselves are not the ones experiencing anger and even when anger is not directed at the perpetrator or suspect.

Hydrodynamic reception in the Australian water rat, Hydromys chrysogaster

The Australian water rat, Hydromys chrysogaster, preys on a wide variety of aquatic and semiaquatic arthropods and vertebrates, including fish. A frequently observed predatory strategy of Hydromys is sitting in wait at the water's edge with parts of its vibrissae submersed. Here we show that Hydromys can detect water motions with its whiskers. Behavioural thresholds range from 1.0 to 9.4 mm s−1 water velocity, based on maximal horizontal water velocity in the area covered by the whiskers. This high sensitivity to water motions would enable Hydromys to detect fishes passing by. No responses to surface waves generated by a vibrating rod and resembling the surface waves caused by struggling insects were found.

Is cortical automatic threshold estimation a feasible alternative for hearing threshold estimation with adults with dementia living in aged care?

Objective: This study explored the feasibility of cortical automatic threshold estimation (CATE), a fully automated late auditory evoked potential (AEP) test, as an alternative to pure-tone audiometry for hearing threshold estimation for adults with dementia living in aged care. Design: A single group cross-sectional study was conducted. Participants’ dementia severity was determined through the Clinical Dementia Rating scale. Hearing thresholds were obtained for four audiometric frequencies in at least one ear by using both pure-tone audiometry and CATE. Study sample: Sixteen participants enrolled in the study, of which 14 completed at least one of the hearing tests. Twelve ears, from six participants, were included in the final correlation analysis. Results: Pearson correlation coefficients were significant between CATE and pure-tone audiometry for all frequencies: r 2 = 0.52 (p = 0.008) for 500 Hz, r 2 = 0.79 (p = 0.0001) for 1000 Hz, r 2 = 0.71 (p = 0.0005) for 2000 Hz, and r 2 = 0.92 (p < 0.0001) for 4000 Hz. Cortical thresholds were within 10 dB of behavioural thresholds for all four frequencies. Conclusions: Findings are encouraging for the feasibility of CATE as an alternative diagnostic test to pure-tone audiometry for adults living with dementia in aged care.

Association Analysis of Candidate Gene Polymorphisms and Audiometric Measures of Noise-Induced Hearing Loss in Young Musicians.

This study aimed to investigate the association between candidate genetic variants and audiometric measures of noise-induced hearing loss (NIHL) in young musicians. The study analyzed a database by Phillips et al. (Feasibility of a bilateral 4000-6000 Hz notch as a phenotype for genetic association analysis. Int J Audiol 2015;54:645-52.) which included behavioral hearing thresholds, distortion-product otoacoustic emissions (DPOAE), tympanometric, and genetic data of 166 participants meeting the inclusion criteria. Nineteen single nucleotide polymorphisms (SNPs) in 13 cochlear genes previously associated with NIHL in factory workers were included in the present investigation. The average hearing threshold at 3000 and 4000 Hz (AHT) and average DPOAE signal to noise ratio (DPOAE SNR) in both ears were calculated. The regression analyses showed that two SNPs- one in KCNE1 (rs2070358) and the other in CAT (rs12273124) revealed a statistically significant relationship with DPOAE SNR in both ears. Two SNPs in MYH14 and one in GJB4 revealed a significant association with DPOAE SNR in the left ear. Two SNPs in HSP70, one in CDH23 and one in KCNJ10 showed significant association with DPOAE SNR in the right ear. None of the included SNPs showed association with AHT in both ears. A genetic variant in KCNE1 was associated with the strength of the cochlear amplifier as assessed by DPOAE SNR. Musicians carrying causal genetic variants to NIHL might exhibit changes in their auditory functions early in the lifespan even when most subjects had their hearing thresholds within normal limits. These participants are likely to show the clinical manifestation of NIHL in the future if no preventive measures are applied.

Structural, optical and thermal analysis of creatininium borate – A new semiorganic nlo single crystal

The main focus of this work is to synthesize creatininium borate (CRB) single crystal by using slow evaporation technique and to analyse the physiochemical properties. The grown single crystal is subjected to Single Crystal X-ray Diffraction analysis (SXRD) and the structural parameters were assigned. The various interactions present in the synthesized material have been visualized by Hirshfield surface analysis. The transmittance ability was studied by using UV Visible spectral analysis and the optical constants such as band gap energy, extinction coefficient and refractive index were calculated. HOMO-LUMO and MEP plots were successfully generated and analysed. The emission behaviour of creatininium borate was analysed by photoluminescence spectral analysis. Theoretical NLO calculations were performed to calculate the dipole moment, polarizability, first order hyperpolarizability and second order hyperpolarizability. Third order optical non linearity was confirmed by Z scan analysis. The second harmonic generation was confirmed by Kurtz and Perry powder technique. The optical limiting behaviour and laser damage threshold analysis suggests the material in laser assisted devices. Thermal behaviour of the material has been analysed by TG/DTA analysis.

Human Depth Sensitivity Is Affected by Object Plausibility.

Using behavioral and fMRI paradigms, we asked how the physical plausibility of complex 3-D objects, as defined by the object's congruence with 3-D Euclidean geometry, affects behavioral thresholds and neural responses to depth information. Stimuli were disparity-defined geometric objects rendered as random dot stereograms, presented in plausible and implausible variations. In the behavior experiment, observers were asked to complete (1) a noise-based depth task that involved judging the depth position of a target embedded in noise and (2) a fine depth judgment task that involved discriminating the nearer of two consecutively presented targets. Interestingly, results indicated greater behavioral sensitivities of depth judgments for implausible versus plausible objects across both tasks. In the fMRI experiment, we measured fMRI responses concurrently with behavioral depth responses. Although univariate responses for depth judgments were largely similar across cortex regardless of object plausibility, multivariate representations for plausible and implausible objects were notably distinguishable along depth-relevant intermediate regions V3 and V3A, in addition to object-relevant LOC. Our data indicate significant modulations of both behavioral judgments of and neural responses to depth by object context. We conjecture that disparity mechanisms interact dynamically with the object recognition problem in the visual system such that disparity computations are adjusted based on object familiarity.

Neuroprotective effects of isoquercitrin in diabetic neuropathy via Wnt/β-catenin signaling pathway inhibition.

Diabetic neuropathy is a peripheral nervous system disorder affecting both somatic and autonomic components of nervous system. A growing body of evidence have depicted that high glucose levels can induce activation of the Wnt/β-catenin pathway, however there are no studies targeting this pathway in DN. The intent of the present study was to investigate the effects of isoquercitrin (ISQ), a Wnt/β-catenin signaling pathway inhibitor, in diabetic neuropathy. Streptozotocin (50 mg/kg, i.p.) was used to induce diabetes in rats. 6-week diabetic rats were treated intrathecally with ISQ at 10 and 30 μM doses for 3 days. Furthermore, to confirm the results of the intrathecal study, a 2-week intraperitoneal treatment of ISQ was given to diabetic rats. After 6 weeks, diabetic rats developed neuropathy which was evident from reduced thermal and mechanical hyperalgesia thresholds and significant deterioration in motor nerve conduction velocity (MNCV), nerve blood flow (NBF). Sciatic nerves of diabetic neuropathy rats showed increased expression of Wnt pathway proteins namely β-catenin, c-myc and MMP2. Treatment with ISQ, both intrathecally (10 and 30 μM) and intraperitoneally (10 mg/kg), significantly ameliorated the alterations in behavioral pain thresholds and improved functional parameters in diabetic rats. Moreover, ISQ also downregulated the expression of Wnt/β-catenin pathway proteins significantly in diabetic rats as compared to vehicle-treated diabetic rats. Results of the present study suggest the neuroprotective potential of ISQ in the treatment of DN via inhibition of Wnt/β-catenin signaling pathway.

Exploring the role of utility-difference threshold in choice behavior: An empirical case study of bus service choice

Abstract This paper provides an empirical case study involving the concept of utility-difference threshold in the context of bus service choice, which aims to explore the role of utility-difference threshold in choice behavior. The underlying assumption is that consumers are unable to recognize a small utility difference between two alternatives, which may be either because they only have imperfect knowledge and limited perception ability or because they just simplify the choice task to save process efforts. Based on this assumption, a concept of utility-difference threshold is introduced to the model specification within which two alternatives are treated as the same. In this study, it is assumed that the utility-difference threshold could be a constant, a random term following a certain distribution or a function of some exogenous determinants, such as consumers’ socio-demographic characteristics. To test these assumptions, a stated choice experiment based on the rule of orthogonality was designed, in which two hypothetical kinds of bus service composing a choice set. A survey based on this design was carried out, in which 1784 valid observations were collected. The estimation results support the existence of utility-difference threshold as well as its observed and unobserved heterogeneity.

The effects of suspended sediments on the swimming behavior of the calanoid copepod, Acartia tonsa

Abstract Copepod swimming behavior is governed by chemical and hydro-mechanical cues. The environment of copepods, however, is frequently impacted by anthropogenic activities, in particular increased levels of suspended sediment due to coastal development. To better understand the effects of sediments on copepod behavior, we used video recordings to document free-swimming in Acartia tonsa under five sediment regimes, both with and without food. Results of the video analysis indicate that as sediment concentration increased, jumping increased and swimming paths became more convoluted. In the presence of prey, swimming trajectories became circular, as opposed to without prey, where paths were more erratic and slower. There was a reverse trend at higher sediment concentrations (120 and 200 mg l−1) for net velocity, turning rate and “spread of participation” index, which could indicate a behavioral threshold. Overall, greater motility with increasing sediment concentration suggests that the copepods were trying to transport themselves out of the sediment-affected area. In the absence of food, the energy cost of this behavior may affect the fitness of Acartia tonsa and, consequently, its predators.

The Association Between Physiological Noise Levels and Speech Understanding in Noise.

Traditionally, elevated hearing thresholds have been considered to be the main contributors to difficulty understanding speech in noise; yet, patients will often report difficulties with speech understanding in noise despite having audiometrically normal hearing. The purpose of this cross-sectional study was to critically evaluate the relationship of various metrics of auditory function (behavioral thresholds and otoacoustic emissions) on speech understanding in noise in a large sample of audiometrically normal-hearing individuals. Behavioral hearing thresholds, distortion product otoacoustic emission (DPOAE) levels, stimulus-frequency otoacoustic emission levels, and physiological noise (quantified using OAE noise floors) were measured from 921 individuals between 10 and 68 years of age with normal pure-tone averages. The quick speech-in-noise (QuickSIN) test outcome, quantified as the signal-to-noise ratio (SNR) loss, was used as the metric of speech understanding in noise. Principle component analysis (PCA) and linear regression modeling were used to evaluate the relationship between the measures of auditory function and speech in noise performance. Over 25% of participants exhibited mild or worse degree of SNR loss. PCA revealed DPOAE levels at 12.5 to 16 kHz to be significantly correlated with the variation in QuickSIN scores, although correlations were weak (R = 0.017). Out of all the metrics evaluated, higher levels of self-generated physiological noise accounted for the most variance in QuickSIN performance (R = 0.077). Higher levels of physiological noise were associated with worse QuickSIN performance in listeners with normal hearing sensitivity. We propose that elevated physiological noise levels in poorer speech in noise performers could diminish the effective SNR, thereby negatively impacting performance as seen by poorer QuickSIN scores.