Journal articles on the topic 'Inferior colliculus Computer simulation'
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1
Dean, Paul, John E. W. Mayhew, and Pat Langdon. "Learning and Maintaining Saccadic Accuracy: A Model of Brainstem–Cerebellar Interactions." Journal of Cognitive Neuroscience 6, no. 2 (April 1994): 117–38. http://dx.doi.org/10.1162/jocn.1994.6.2.117.
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Saccadic accuracy requires that the control signal sent to the motor neurons must be the right size to bring the fovea to the target, whatever the initial position of the eyes (and corresponding state of the eye muscles). Clinical and experimental evidence indicates that the basic machinery for generating saccadic eye movements, located in the brainstem, is not accurate: learning to make accurate saccades requires cerebellar circuitry located in the posterior vermis and fastigial nucleus. How do these two circuits interact to achieve adaptive control of saccades? A model of this interaction is described, based on Kawato's principle of feedback-error-learning. Its three components were (1) a simple controller with no knowledge of initial eye position, corresponding to the superior colliculus; (2) Robinson's internal feedback model of the saccadic burst generator, corresponding to preoculomotor areas in the brain-stem; and (3) Albus's Cerebellar Model Arithmetic Computer (CMK), a neural net model of the cerebellum. The connections between these components were (I) the simple feedback controller passed a (usually inaccurate) command to the pulse generator, and (2) a copy of this command to the CMAC; (3) the CMAC combined the copy with information about initial eye position to (4) alter the gain on the pulse generator's internal feedback loop, thereby adjusting the size of burst sent to the motor neurons. (5) If the saccade were inaccurate, an error signal from the feedback controller adjusted the weights in the CMAC. It was proposed that connection (2) corresponds to the mossy fiber projection from superior colliculus to oculomotor vermis via the nucleus reticularis tegmenti pontis, and connection (5) to the climbing fiber projection from superior colliculus to the oculomotor vermis via the inferior olive. Plausible initialization values were chosen so that the system produced hypometric saccades (as do human infants) at the start of learning, and position-dependent hypermetric saccades when the cerebellum was removed. Simulations for horizontal eye movements showed that accurate saccades from any starting position could be learned rapidly, even if the error signal conveyed only whether the initial saccade were too large or too small. In subsequent tests the model adapted realistically both to simulated weakening of the eye muscles, and to intrasaccadic displacement of the target, thereby mimicking saccadic plasticity in adults. The architecture of the model may therefore offer a functional explanation of hitherto mysterious tectocerebellar projections, and a framework for investigating in greater detail how the cerebellum adaptively controls saccadic accuracy.
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Peddicord, Richard. "Simulation of ILD sensitive neurons in the inferior colliculus of the barn owl." Hearing Research 123, no. 1-2 (September 1998): 111–24. http://dx.doi.org/10.1016/s0378-5955(98)00102-6.
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Hoshino, Osamu, and Kazuharu Kuroiwa. "Echo sound detection in the inferior colliculus for human echolocation." Neurocomputing 38-40 (June 2001): 1289–96. http://dx.doi.org/10.1016/s0925-2312(01)00482-9.
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Youn, Cha Kyung, Yonghyun Jun, Eu-Ri Jo, and Sung Il Cho. "Age-Related Hearing Loss in C57BL/6J Mice Is Associated with Mitophagy Impairment in the Central Auditory System." International Journal of Molecular Sciences 21, no. 19 (September 29, 2020): 7202. http://dx.doi.org/10.3390/ijms21197202.
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Aging is associated with functional and morphological changes in the sensory organs, including the auditory system. Mitophagy, a process that regulates the turnover of dysfunctional mitochondria, is impaired with aging. This study aimed to investigate the effect of aging on mitophagy in the central auditory system using an age-related hearing loss mouse model. C57BL/6J mice were divided into the following four groups based on age: 1-, 6-, 12-, and 18-month groups. The hearing ability was evaluated by measuring the auditory brainstem response (ABR) thresholds. The mitochondrial DNA damage level and the expression of mitophagy-related genes, and proteins were investigated by real-time polymerase chain reaction and Western blot analyses. The colocalization of mitophagosomes and lysosomes in the mouse auditory cortex and inferior colliculus was analyzed by immunofluorescence analysis. The expression of genes involved in mitophagy, such as PINK1, Parkin, and BNIP3 in the mouse auditory cortex and inferior colliculus, was investigated by immunohistochemical staining. The ABR threshold increased with aging. In addition to the mitochondrial DNA integrity, the mRNA levels of PINK1, Parkin, NIX, and BNIP3, as well as the protein levels of PINK1, Parkin, BNIP3, COX4, LC3B, mitochondrial oxidative phosphorylation (OXPHOS) subunits I–IV in the mouse auditory cortex significantly decreased with aging. The immunofluorescence analysis revealed that the colocalization of mitophagosomes and lysosomes in the mouse auditory cortex and inferior colliculus decreased with aging. The immunohistochemical analysis revealed that the expression of PINK1, Parkin, and BNIP3 decreased in the mouse auditory cortex and inferior colliculus with aging. These findings indicate that aging-associated impaired mitophagy may contribute to the cellular changes observed in an aged central auditory system, which result in age-related hearing loss. Thus, the induction of mitophagy can be a potential therapeutic strategy for age-related hearing loss.
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Sinex, Donal G., Hongzhe Li, and David S. Velenovsky. "Prevalence of Stereotypical Responses to Mistuned Complex Tones in the Inferior Colliculus." Journal of Neurophysiology 94, no. 5 (November 2005): 3523–37. http://dx.doi.org/10.1152/jn.01194.2004.
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The human auditory system has an exceptional ability to separate competing sounds, but the neural mechanisms that underlie this ability are not understood. Responses of inferior colliculus (IC) neurons to “mistuned” complex tones were measured to investigate possible neural mechanisms for spectral segregation. A mistuned tone is a harmonic complex tone in which the frequency of one component has been changed; that component may be heard as a separate sound source, suggesting that the mistuned tone engages the same mechanisms that contribute to the segregation of natural sounds. In this study, the harmonic tone consisted of eight harmonics of 250 Hz; in the mistuned tone, the frequency of the fourth harmonic was increased by 12% (120 Hz). The mistuned tone elicited a stereotypical discharge pattern, consisting of peaks separated by about 8 ms and a response envelope modulated with a period of 100 ms, which bore little resemblance to the discharge pattern elicited by the harmonic tone or to the stimulus waveform. Similar discharge patterns were elicited from many neurons with a range of characteristic frequencies, especially from neurons that exhibited short-latency sustained responses to pure tones. In contrast, transient and long-latency neurons usually did not exhibit the stereotypical discharge pattern. The discharge pattern was generally stable when the stimulus level or component phase was varied; the major effect of these manipulations was to shift the phase of the response envelope. Simulation of IC responses with a computational model suggested that off-frequency inhibition could produce discharge patterns with these characteristics.
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Hewitt, Michael J., and Ray Meddis. "A computer model of amplitude‐modulation sensitivity of single units in the inferior colliculus." Journal of the Acoustical Society of America 95, no. 4 (April 1994): 2145–59. http://dx.doi.org/10.1121/1.408676.
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Carlson, Nicole L., Vivienne L. Ming, and Michael Robert DeWeese. "Sparse Codes for Speech Predict Spectrotemporal Receptive Fields in the Inferior Colliculus." PLoS Computational Biology 8, no. 7 (July 12, 2012): e1002594. http://dx.doi.org/10.1371/journal.pcbi.1002594.
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Hoshino, Osamu, and Kazuharu Kuroiwa. "A neural network model of the inferior colliculus with modifiable lateral inhibitory synapses for human echolocation." Biological Cybernetics 86, no. 3 (March 1, 2002): 231–40. http://dx.doi.org/10.1007/s00422-001-0291-0.
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Litovsky, R. Y., and B. Delgutte. "Neural Correlates of the Precedence Effect in the Inferior Colliculus: Effect of Localization Cues." Journal of Neurophysiology 87, no. 2 (February 1, 2002): 976–94. http://dx.doi.org/10.1152/jn.00568.2001.
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The precedence effect (PE) is an auditory phenomenon involved in suppressing the perception of echoes in reverberant environments, and is thought to facilitate accurate localization of sound sources. We investigated physiological correlates of the PE in the inferior colliculus (IC) of anesthetized cats, with a focus on directional mechanisms for this phenomenon. We used a virtual space (VS) technique, where two clicks (a “lead” and a “lag”) separated by a brief time delay were each filtered through head-related transfer functions (HRTFs). For nearly all neurons, the response to the lag was suppressed for short delays and recovered at long delays. In general, both the time course and the directional patterns of suppression resembled those reported in free-field studies in many respects, suggesting that our VS simulation contained the essential cues for studying PE phenomena. The relationship between the directionality of the response to the lead and that of its suppressive effect on the lag varied a great deal among IC neurons. For a majority of units, both excitation produced by the lead and suppression of the lag response were highly directional, and the two were similar to one another. For these neurons, the long-lasting inhibitory inputs thought to be responsible for suppression seem to have similar spatial tuning as the inputs that determine the excitatory response to the lead. Further, the behavior of these neurons is consistent with psychophysical observations that the PE is strongest when the lead and the lag originate from neighboring spatial locations. For other neurons, either there was no obvious relationship between the directionality of the excitatory lead response and the directionality of suppression, or the suppression was highly directional whereas the excitation was not, or vice versa. For these neurons, the excitation and the suppression produced by the lead seem to depend on different mechanisms. Manipulation of the directional cues (such as interaural time and level differences) contained in the lead revealed further dissociations between excitation and suppression. Specifically, for about one-third of the neurons, suppression depended on different directional cues than did the response to the lead, even though the directionality of suppression was similar to that of the lead response when all cues were present. This finding suggests that the inhibitory inputs causing suppression may originate in part from subcollicular auditory nuclei processing different directional cues than the inputs that determine the excitatory response to the lead. Neurons showing such dissociations may play an important role in the PE when the lead and the lag originate from very different directions.
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Myers, Eugene N., Susumu Araki, Atsushi Kawano, H. Lee Seldon, Robert K. Shepherd, Sotaro Funasaka, and Graeme M. Clark. "Effects of intracochlear factors on spiral ganglion cells and auditory brain stem response after long-term electrical stimulation in deafened kittens." Otolaryngology–Head and Neck Surgery 122, no. 3 (March 2000): 425–33. http://dx.doi.org/10.1067/mhn.2000.93863.
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Using an animal model, we have studied the response of the auditory brain stem to cochlear implantation and the effect of intracochlear factors on this response. Neonatally, pharmacologically deafened cats (100 to more than 180 days old) were implanted with a 4-electrode array in both cochleas. Then, the left cochlea of each cat was electrically stimulated for total periods of up to 1000 hours. After a terminal 14C-2-deoxyglucose (2DG) experiment, the fraction of the right inferior colliculus with a significant accumulation of 2DG label was calculated. Using 3-dimensional computer-aided reconstruction, we examined the cochleas of these animals for spiral ganglion cell (SGC) survival and intracochlear factors such as electrode positions, degeneration of the organ of Corti, and the degree of fibrosis of the scala tympani. The distribution of each parameter was calculated along the organ of Corti from the basal end. There was a positive correlation between SGC survival and the level of fibrosis in the scala tympani, and a negative correlation between SGC survival and the degree of organ of Corti degeneration. Finally, there was a negative correlation between the 2DG-labeled inferior colliculus volume fraction and the degree of fibrosis, particularly in the 1-mm region nearest the pair of electrodes, and presumably in the basal turn.
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Myers, Eugene N., Susumu Araki, Atsushi Kawano, H. Lee Seldon, Robert K. Shepherd, Sotaro Funasaka, and Graeme M. Clark. "Effects of iNtracochlear Factors on Spiral Ganglion Cells and Auditory Brain Stem Response after Long-Term Electrical Stimulation in Deafened Kittens." Otolaryngology–Head and Neck Surgery 122, no. 3 (March 2000): 425–33. http://dx.doi.org/10.1016/s0194-5998(00)70060-x.
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Using an animal model, we have studied the response of the auditory brain stem to cochlear implantation and the effect of intracochlear factors on this response. Neonatally, pharmacologically deafened cats (100 to more than 180 days old) were implanted with a 4-electrode array in both cochleas. Then, the left cochlea of each cat was electrically stimulated for total periods of up to 1000 hours. After a terminal 14C-2-deoxyglucose (2DG) experiment, the fraction of the right inferior colliculus with a significant accumulation of 2DG label was calculated. Using 3-dimensional computer-aided reconstruction, we examined the cochleas of these animals for spiral ganglion cell (SGC) survival and intracochlear factors such as electrode positions, degeneration of the organ of Corti, and the degree of fibrosis of the scala tympani. The distribution of each parameter was calculated along the organ of Corti from the basal end. There was a positive correlation between SGC survival and the level of fibrosis in the scala tympani, and a negative correlation between SGC survival and the degree of organ of Corti degeneration. Finally, there was a negative correlation between the 2DG-labeled inferior colliculus volume fraction and the degree of fibrosis, particularly in the 1-mm region nearest the pair of electrodes, and presumably in the basal turn.
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Behrend, Oliver, Benjamin Dickson, Elizabeth Clarke, Craig Jin, and Simon Carlile. "Neural Responses to Free Field and Virtual Acoustic Stimulation in the Inferior Colliculus of the Guinea Pig." Journal of Neurophysiology 92, no. 5 (November 2004): 3014–29. http://dx.doi.org/10.1152/jn.00402.2004.
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Virtual auditory space (VAS) stimuli based on outer ear transfer functions became increasingly important in spatial hearing research. However, few studies have investigated the match between responses of auditory neurons to VAS and free-field (FF) stimulation. This study validates acoustic spatial receptive fields (SRFs) of 183 individual midbrain units using both VAS and FF stimuli. The first-spike latency, which varied systematically across SRFs, was 14.9 ± 8.3 (SD) ms in FF, and 15.1 ± 8.3 ms in VAS. Spike-count-based SRFs measured 0–20 dB above the neural threshold covered on average 44.5 ± 18.0% of the recorded sphere in FF and 45.5 ± 18.7% in VAS. The average deviation of the centroid position of SRFs using FF and VAS stimuli was 7.4° azimuth and 3.3° elevation. The average spike rate remained unchanged. The SRF overlap recorded using FF and VAS stimuli (mean: 71.3 ± 12.6%) or repeated FF stimuli (70.2 ± 14.2%) was high and strongly correlated ( r = 0.96; P < 0.05). The SRF match observed with FF and VAS stimuli was not significantly altered over a range of stimulus levels (paired t-test P = 0.51; n = 6). Randomized VAS barely affected SRF sizes, centroids, or maximum spike count but decreased the average minimum response to 59% compared with sequential stimulation (paired t-test; P = 0.05; n = 26). SRF recordings in VAS excluding the acoustic distortions of the recording equipment differed from those in VAS incorporating the equipment (paired t-test P = 0.01; n = 5). In conclusion, neurophysiological recordings demonstrate that individualized VAS stimuli provided a good simulation of a FF environment.
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Greenler, Robert G. "Laboratory simulation of inferior and superior mirages." Journal of the Optical Society of America A 4, no. 3 (March 1, 1987): 589. http://dx.doi.org/10.1364/josaa.4.000589.
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Malmierca, Manuel S., Theodor W. Blackstad, and Kirsten K. Osen. "Computer-assisted 3-D reconstructions of Golgi-impregnated neurons in the cortical regions of the inferior colliculus of rat." Hearing Research 274, no. 1-2 (April 2011): 13–26. http://dx.doi.org/10.1016/j.heares.2010.06.011.
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Borisyuk, Alla, Malcolm N. Semple, and John Rinzel. "Adaptation and Inhibition Underlie Responses to Time-Varying Interaural Phase Cues in a Model of Inferior Colliculus Neurons." Journal of Neurophysiology 88, no. 4 (October 1, 2002): 2134–46. http://dx.doi.org/10.1152/jn.2002.88.4.2134.
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A mathematical model was developed for exploring the sensitivity of low-frequency inferior colliculus (IC) neurons to interaural phase disparity (IPD). The formulation involves a firing-rate-type model that does not include spikes per se. The model IC neuron receives IPD-tuned excitatory and inhibitory inputs (viewed as the output of a collection of cells in the medial superior olive). The model cell possesses cellular properties of firing rate adaptation and postinhibitory rebound (PIR). The descriptions of these mechanisms are biophysically reasonable, but only semi-quantitative. We seek to explain within a minimal model the experimentally observed mismatch between responses to IPD stimuli delivered dynamically and those delivered statically ( McAlpine et al. 2000 ; Spitzer and Semple 1993 ). The model reproduces many features of the responses to static IPD presentations, binaural beat, and partial range sweep stimuli. These features include differences in responses to a stimulus presented in static or dynamic context: sharper tuning and phase shifts in response to binaural beats, and hysteresis and “rise-from-nowhere” in response to partial range sweeps. Our results suggest that dynamic response features are due to the structure of inputs and the presence of firing rate adaptation and PIR mechanism in IC cells, but do not depend on a specific biophysical mechanism. We demonstrate how the model's various components contribute to shaping the observed phenomena. For example, adaptation, PIR, and transmission delay shape phase advances and delays in responses to binaural beats, adaptation and PIR shape hysteresis in different ranges of IPD, and tuned inhibition underlies asymmetry in dynamic tuning properties. We also suggest experiments to test our modeling predictions: in vitro simulation of the binaural beat (phase advance at low beat frequencies, its dependence on firing rate), in vivo partial range sweep experiments (dependence of the hysteresis curve on parameters), and inhibition blocking experiments (to study inhibitory tuning properties by observation of phase shifts).
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Osses Vecchi, Alejandro, Léo Varnet, Laurel H. Carney, Torsten Dau, Ian C. Bruce, Sarah Verhulst, and Piotr Majdak. "A comparative study of eight human auditory models of monaural processing." Acta Acustica 6 (2022): 17. http://dx.doi.org/10.1051/aacus/2022008.
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A number of auditory models have been developed using diverging approaches, either physiological or perceptual, but they share comparable stages of signal processing, as they are inspired by the same constitutive parts of the auditory system. We compare eight monaural models that are openly accessible in the Auditory Modelling Toolbox. We discuss the considerations required to make the model outputs comparable to each other, as well as the results for the following model processing stages or their equivalents: Outer and middle ear, cochlear filter bank, inner hair cell, auditory nerve synapse, cochlear nucleus, and inferior colliculus. The discussion includes a list of recommendations for future applications of auditory models.
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Malmierca, Manuel S., Theodor W. Blackstad, Kirsten K. Osen, Tevfik Karagülle, and Roberto L. Molowny. "The central nucleus of the inferior colliculus in rat: A Golgi and computer reconstruction study of neuronal and laminar structure." Journal of Comparative Neurology 333, no. 1 (July 1, 1993): 1–27. http://dx.doi.org/10.1002/cne.903330102.
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Park, Sohyeon, Seung Hee Han, Byeong-Gon Kim, Myung-Whan Suh, Jun Ho Lee, Seung Ha Oh, and Moo Kyun Park. "Changes in microRNA Expression in the Cochlear Nucleus and Inferior Colliculus after Acute Noise-Induced Hearing Loss." International Journal of Molecular Sciences 21, no. 22 (November 20, 2020): 8792. http://dx.doi.org/10.3390/ijms21228792.
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Noise-induced hearing loss (NIHL) can lead to secondary changes that induce neural plasticity in the central auditory pathway. These changes include decreases in the number of synapses, the degeneration of auditory nerve fibers, and reorganization of the cochlear nucleus (CN) and inferior colliculus (IC) in the brain. This study investigated the role of microRNAs (miRNAs) in the neural plasticity of the central auditory pathway after acute NIHL. Male Sprague–Dawley rats were exposed to white band noise at 115 dB for 2 h, and the auditory brainstem response (ABR) and morphology of the organ of Corti were evaluated on days 1 and 3. Following noise exposure, the ABR threshold shift was significantly smaller in the day 3 group, while wave II amplitudes were significantly larger in the day 3 group compared to the day 1 group. The organ of Corti on the basal turn showed evidence of damage and the number of surviving outer hair cells was significantly lower in the basal and middle turn areas of the hearing loss groups relative to controls. Five and three candidate miRNAs for each CN and IC were selected based on microarray analysis and quantitative reverse transcription PCR (RT-qPCR). The data confirmed that even short-term acoustic stimulation can lead to changes in neuroplasticity. Further studies are needed to validate the role of these candidate miRNAs. Such miRNAs may be used in the early diagnosis and treatment of neural plasticity of the central auditory pathway after acute NIHL.
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Macías, Silvio, Jinhong Luo, and Cynthia F. Moss. "Natural echolocation sequences evoke echo-delay selectivity in the auditory midbrain of the FM bat, Eptesicus fuscus." Journal of Neurophysiology 120, no. 3 (September 1, 2018): 1323–39. http://dx.doi.org/10.1152/jn.00160.2018.
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Echolocating bats must process temporal streams of sonar sounds to represent objects along the range axis. Neuronal echo-delay tuning, the putative mechanism of sonar ranging, has been characterized in the inferior colliculus (IC) of the mustached bat, an insectivorous species that produces echolocation calls consisting of constant frequency and frequency modulated (FM) components, but not in species that use FM signals alone. This raises questions about the mechanisms that give rise to echo-delay tuning in insectivorous bats that use different signal designs. To investigate whether stimulus context may account for species differences in echo-delay selectivity, we characterized single-unit responses in the IC of awake passively listening FM bats, Eptesicus fuscus, to broadcasts of natural sonar call-echo sequences, which contained dynamic changes in signal duration, interval, spectrotemporal structure, and echo-delay. In E. fuscus, neural selectivity to call-echo delay emerges in a population of IC neurons when stimulated with call-echo pairs presented at intervals mimicking those in a natural sonar sequence. To determine whether echo-delay selectivity also depends on the spectrotemporal features of individual sounds within natural sonar sequences, we studied responses to computer-generated echolocation signals that controlled for call interval, duration, bandwidth, sweep rate, and echo-delay. A subpopulation of IC neurons responded selectively to the combination of the spectrotemporal structure of natural call-echo pairs and their temporal patterning within a dynamic sonar sequence. These new findings suggest that the FM bat’s fine control over biosonar signal parameters may modulate IC neuronal selectivity to the dimension of echo-delay. NEW & NOTEWORTHY Echolocating bats perform precise auditory temporal computations to estimate their distance to objects. Here, we report that response selectivity of neurons in the inferior colliculus of a frequency modulated bat to call-echo delay, or target range tuning, depends on the temporal patterning and spectrotemporal features of sound elements in a natural echolocation sequence. We suggest that echo responses to objects at different distances are gated by the bat’s active control over the spectrotemporal patterning of its sonar emissions.
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Chumak, Tetyana, Diana Tothova, Iva Filova, Zbynek Bures, Jiri Popelar, Gabriela Pavlinkova, and Josef Syka. "Overexpression of Isl1 under the Pax2 Promoter, Leads to Impaired Sound Processing and Increased Inhibition in the Inferior Colliculus." International Journal of Molecular Sciences 22, no. 9 (April 26, 2021): 4507. http://dx.doi.org/10.3390/ijms22094507.
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The LIM homeodomain transcription factor ISL1 is essential for the different aspects of neuronal development and maintenance. In order to study the role of ISL1 in the auditory system, we generated a transgenic mouse (Tg) expressing Isl1 under the Pax2 promoter control. We previously reported a progressive age-related decline in hearing and abnormalities in the inner ear, medial olivocochlear system, and auditory midbrain of these Tg mice. In this study, we investigated how Isl1 overexpression affects sound processing by the neurons of the inferior colliculus (IC). We recorded extracellular neuronal activity and analyzed the responses of IC neurons to broadband noise, clicks, pure tones, two-tone stimulation and frequency-modulated sounds. We found that Tg animals showed a higher inhibition as displayed by two-tone stimulation; they exhibited a wider dynamic range, lower spontaneous firing rate, longer first spike latency and, in the processing of frequency modulated sounds, showed a prevalence of high-frequency inhibition. Functional changes were accompanied by a decreased number of calretinin and parvalbumin positive neurons, and an increased expression of vesicular GABA/glycine transporter and calbindin in the IC of Tg mice, compared to wild type animals. The results further characterize abnormal sound processing in the IC of Tg mice and demonstrate that major changes occur on the side of inhibition.
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Pawlas, Zbyněk, Lev B. Klebanov, Viktor Beneš, Michaela Prokešová, Jiří Popelář, and Petr Lánský. "First-Spike Latency in the Presence of Spontaneous Activity." Neural Computation 22, no. 7 (July 2010): 1675–97. http://dx.doi.org/10.1162/neco.2010.11-09-1118.
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A new statistical method for the estimation of the response latency is proposed. When spontaneous discharge is present, the first spike after the stimulus application may be caused by either the stimulus itself, or it may appear due to the prevailing spontaneous activity. Therefore, an appropriate method to deduce the response latency from the time to the first spike after the stimulus is needed. We develop a nonparametric estimator of the response latency based on repeated stimulations. A simulation study is provided to show how the estimator behaves with an increasing number of observations and for different rates of spontaneous and evoked spikes. Our nonparametric approach requires very few assumptions. For comparison, we also consider a parametric model. The proposed probabilistic model can be used for both single and parallel neuronal spike trains. In the case of simultaneously recorded spike trains in several neurons, the estimators of joint distribution and correlations of response latencies are also introduced. Real data from inferior colliculus auditory neurons obtained from a multielectrode probe are studied to demonstrate the statistical estimators of response latencies and their correlations in space.
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Kobayashi, Naomi, Hyonmin Choe, Hiroyuki Ike, Shota Higashihira, Daigo Kobayashi, Shintaro Watanabe, So Kubota, and Yutaka Inaba. "Evaluation of anterior inferior iliac spine impingement after hip arthroscopic osteochondroplasty using computer simulation analysis." Journal of Orthopaedic Surgery 28, no. 2 (January 1, 2020): 230949902093553. http://dx.doi.org/10.1177/2309499020935533.
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Background: Anterior inferior iliac spine (AIIS) impingement is an important risk factor for revision hip arthroscopy. Although a morphological classification system is available, evaluating AIIS impingement with respect to joint kinematics remains a challenge. Purpose: To use computer simulation analysis to ascertain the prevalence of AIIS impingement before and after osteochondroplasty. Methods: A total of 35 joints from 30 cases (20 males and 10 females; average age: 43.3 ± 13.7 years) were analyzed. All joints had cam morphology and underwent hip arthroscopic osteochondroplasty. A three-dimensional model of each joint was constructed pre- and postoperatively. Joint kinematic simulation software (ZedHip®, Lexi, Tokyo) was used to identify the impingement point on the acetabular side and the incidence (expressed as a percentage) of AIIS impingement calculated. Radiographic and clinical evaluation was performed pre- and postoperatively. Results: AIIS impingement was observed postoperatively in six joints but preoperatively in only one joint. The rate of AIIS postoperative impingement was significantly higher than that of preoperative impingement. All impingement points were located on the inferior aspect of the AIIS apex. However, there were no significant differences between the AIIS impingement and non-impingement groups in terms of clinical outcome. Conclusion: The incidence of AIIS impingement after osteochondroplasty was 17% by computer simulation analysis. Osteochondroplasty may result in subsequent AIIS impingement.
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Nakamura, Shinichiro, Yoshihisa Tanaka, Shinichi Kuriyama, Kohei Nishitani, Hiromu Ito, Moritoshi Furu, and Shuichi Matsuda. "Superior-inferior position of patellar component affects patellofemoral kinematics and contact forces in computer simulation." Clinical Biomechanics 45 (June 2017): 19–24. http://dx.doi.org/10.1016/j.clinbiomech.2017.04.005.
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Lee, Heow Pueh, Revanth Reddy Garlapati, Vincent Fook Hin Chong, and De Yun Wang. "Comparison between effects of various partial inferior turbinectomy options on nasal airflow: a computer simulation study." Computer Methods in Biomechanics and Biomedical Engineering 16, no. 1 (January 2013): 112–18. http://dx.doi.org/10.1080/10255842.2011.609481.
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Gai, Yan, Janet L. Ruhland, and Tom C. T. Yin. "Behavior and modeling of two-dimensional precedence effect in head-unrestrained cats." Journal of Neurophysiology 114, no. 2 (August 2015): 1272–85. http://dx.doi.org/10.1152/jn.00214.2015.
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The precedence effect (PE) is an auditory illusion that occurs when listeners localize nearly coincident and similar sounds from different spatial locations, such as a direct sound and its echo. It has mostly been studied in humans and animals with immobile heads in the horizontal plane; speaker pairs were often symmetrically located in the frontal hemifield. The present study examined the PE in head-unrestrained cats for a variety of paired-sound conditions along the horizontal, vertical, and diagonal axes. Cats were trained with operant conditioning to direct their gaze to the perceived sound location. Stereotypical PE-like behaviors were observed for speaker pairs placed in azimuth or diagonally in the frontal hemifield as the interstimulus delay was varied. For speaker pairs in the median sagittal plane, no clear PE-like behavior occurred. Interestingly, when speakers were placed diagonally in front of the cat, certain PE-like behavior emerged along the vertical dimension. However, PE-like behavior was not observed when both speakers were located in the left hemifield. A Hodgkin-Huxley model was used to simulate responses of neurons in the medial superior olive (MSO) to sound pairs in azimuth. The novel simulation incorporated a low-threshold potassium current and frequency mismatches to generate internal delays. The model exhibited distinct PE-like behavior, such as summing localization and localization dominance. The simulation indicated that certain encoding of the PE could have occurred before information reaches the inferior colliculus, and MSO neurons with binaural inputs having mismatched characteristic frequencies may play an important role.
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Witczuk, Julia, and Stanisław Pagacz. "Evaluating Alternative Flight Plans in Thermal Drone Wildlife Surveys—Simulation Study." Remote Sensing 13, no. 6 (March 14, 2021): 1102. http://dx.doi.org/10.3390/rs13061102.
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The rapidly developing technology of unmanned aerial vehicles (drones) extends to the availability of aerial surveys for wildlife research and management. However, regulations limiting drone operations to visual line of sight (VLOS) seriously affect the design of surveys, as flight paths must be concentrated within small sampling blocks. Such a design is inferior to spatially unrestricted randomized designs available if operations beyond visual line of sight (BVLOS) are allowed. We used computer simulations to assess whether the VLOS rule affects the accuracy and precision of wildlife density estimates derived from drone collected data. We tested two alternative flight plans (VLOS vs. BVLOS) in simulated surveys of low-, medium- and high-density populations of a hypothetical ungulate species with three levels of effort (one to three repetitions). The population density was estimated using the ratio estimate and distance sampling method. The observed differences in the accuracy and precision of estimates from the VLOS and BVLOS surveys were relatively small and negligible. Only in the case of the low-density population (2 ind./100 ha) surveyed once was the VLOS design inferior to BVLOS, delivering biased and less precise estimates. These results show that while the VLOS regulations complicate survey logistics and interfere with random survey design, the quality of derived estimates does not have to be compromised. We advise testing alternative survey variants with the aid of computer simulations to achieve reliable estimates while minimizing survey costs.
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Skorek, Andrzej, Paweł Kłosowski, Łukasz Plichta, Dorota Raczyńska, Marcin Zmuda Trzebiatowski, and Paweł Lemski. "Posttraumatic Orbital Emphysema: A Numerical Model." Journal of Ophthalmology 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/231436.
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Orbital emphysema is a common symptom accompanying orbital fracture. The pathomechanism is still not recognized and the usually assumed cause, elevated pressure in the upper airways connected with sneezing or coughing, does not always contribute to the occurrence of this type of fracture. Observations based on the finite model (simulating blowout type fracture) of the deformations of the inferior orbital wall after a strike in its lower rim. Authors created a computer numeric model of the orbit with specified features—thickness and resilience modulus. During simulation an evenly spread 14400 N force was applied to the nodular points in the inferior rim (the maximal value not causing cracking of the outer rim, but only ruptures in the inferior wall). The observation was made from1·10-3to1·10-2second after a strike. Right after a strike dislocations of the inferior orbital wall toward the maxillary sinus were observed. Afterwards a retrograde wave of the dislocation of the inferior wall toward the orbit was noticed. Overall dislocation amplitude reached about 6 mm. Based on a numeric model of the orbit submitted to a strike in the inferior wall an existence of a retrograde shock wave causing orbital emphysema has been found.
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Gorman, Julia C., Oliver L. Tufte, Anna V. R. Miller, William M. DeBello, José L. Peña, and Brian J. Fischer. "Diverse processing underlying frequency integration in midbrain neurons of barn owls." PLOS Computational Biology 17, no. 11 (November 11, 2021): e1009569. http://dx.doi.org/10.1371/journal.pcbi.1009569.
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Emergent response properties of sensory neurons depend on circuit connectivity and somatodendritic processing. Neurons of the barn owl’s external nucleus of the inferior colliculus (ICx) display emergence of spatial selectivity. These neurons use interaural time difference (ITD) as a cue for the horizontal direction of sound sources. ITD is detected by upstream brainstem neurons with narrow frequency tuning, resulting in spatially ambiguous responses. This spatial ambiguity is resolved by ICx neurons integrating inputs over frequency, a relevant processing in sound localization across species. Previous models have predicted that ICx neurons function as point neurons that linearly integrate inputs across frequency. However, the complex dendritic trees and spines of ICx neurons raises the question of whether this prediction is accurate. Data from in vivo intracellular recordings of ICx neurons were used to address this question. Results revealed diverse frequency integration properties, where some ICx neurons showed responses consistent with the point neuron hypothesis and others with nonlinear dendritic integration. Modeling showed that varied connectivity patterns and forms of dendritic processing may underlie observed ICx neurons’ frequency integration processing. These results corroborate the ability of neurons with complex dendritic trees to implement diverse linear and nonlinear integration of synaptic inputs, of relevance for adaptive coding and learning, and supporting a fundamental mechanism in sound localization.
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Hwang, Bo-Yeon, Jae-Yeol Lee, Junho Jung, Joo-Young Ohe, Young-Gyu Eun, YoungChan Lee, and Jung-Woo Lee. "Computer-Assisted Preoperative Simulations and 3D Printed Surgical Guides Enable Safe and Less-Invasive Mandibular Segmental Resection: Tailor-Made Mandibular Resection." Applied Sciences 10, no. 4 (February 15, 2020): 1325. http://dx.doi.org/10.3390/app10041325.
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This study aimed to present and evaluate alternative lesion-specific mandibulectomy methods for preserving the mandibular anatomical structures as compared with the conventional virtual surgical plan. Fifteen patients who received segmental mandibulectomy were included in this study, and the following parameters were evaluated: (1) the disease-free bone margin, (2) the volume and surface between the tailor-made resection simulation and conventional resection simulation, and (3) the preserved mandibular anatomical structures. In all 15 patients, disease-free bone margins were confirmed by histopathology. Volumes of conventional resection simulation and tail-made resection simulation were 49,468.66 ± 14,007.96 mm3 and 52,610.01 ± 13,755.33 mm3 and the surfaces were 20,927.38 ± 4471.70 mm2 and 22,356.49 ± 4185.73 mm2, respectively; these were statistically significant (both, p < 0.001). Mandibular dentition was partially preserved in six patients. Twelve of the 15 patients had changes in defect classification with preservation of the mandibular inferior border. In conclusion, alternative lesion-specific mandibulectomy was a less invasive method for effectively removing mandibular lesions while preserving the important anatomical structures of the mandible.
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Tsai, Jeffrey J., Kanthaiah Koka, and Daniel J. Tollin. "Varying Overall Sound Intensity to the Two Ears Impacts Interaural Level Difference Discrimination Thresholds by Single Neurons in the Lateral Superior Olive." Journal of Neurophysiology 103, no. 2 (February 2010): 875–86. http://dx.doi.org/10.1152/jn.00911.2009.
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The lateral superior olive (LSO) is one of the earliest sites in the auditory pathway involved in processing acoustical cues to sound location. LSO neurons encode the interaural level difference (ILD) cue to azimuthal location. Here we investigated the effect of variations in the overall stimulus levels of sounds at the two ears on the sensitivity of LSO neurons to small differences in ILDs of pure tones. The neuronal firing rate versus ILD functions were found to depend greatly on the overall stimulus level, typically shifting along the ILD axis toward the excitatory ear and attaining greater maximal firing rates as stimulus level increased. Seventy-five percent of neurons showed significant shifts with changes in overall sound level. The range of ILDs corresponding to best neural acuity for ILDs shifted accordingly. In a simulation using the empirical data, when the overall stimulus level was randomly changed from one trial to the next, the neural discrimination thresholds for ILD, or ILD acuities, were worsened by 50–60% across the population of neurons relative to fixed stimulus levels whether ILD acuity was measured at the azimuthal midline or the ILD pedestal producing the best acuity. The impairment in ILD discrimination was attributed to the increased neural response variance imparted by varying the stimulus level. These results contrast to those observed in psychophysical studies where ILD discrimination thresholds under similar experimental conditions are invariant to overall changes in stimulus level. A simple computational model that incorporated the antagonistic inputs of bilateral LSO nuclei as well as the dorsal nuclei of the lateral lemniscus to the inferior colliculus produced a more robust encoding of ILD even in the setting of roving stimulus level. Testable predictions of this model and comparison to other computational models addressing stimulus invariance were considered.
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Li, Dong Song, Shu Qiang Li, Bo Cai, Chen Yang, and Jian Guo Liu. "Finite Element Analysis of Acetabular Medial Wall Displacement Osteotomy in Adult Acetabular Dysplasia." Applied Mechanics and Materials 152-154 (January 2012): 1353–58. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.1353.
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Objective To look for a suitable displacement range of acetabular medial wall following osteotomy by computer-aided design finite element analysis. Methods SolidWorks 2008 software was used to establish three-dimensional models of acetabular dysplasia pelvis. Acetabular medial wall displacement osteotomy was simulated to make acetabular medial wall bone displace from 2 mm bone contact to 7 mm bone contact in the pelvic cavity. One experimental group was set at 1 mm intervals, totally 10 experimental groups. The acetabulum in each group was split into four quadrants. The prosthesis acetabulum-bone interface in each group was analyzed by computer simulation contrast mechanics experiment. The Mises stress and shear stress values were measured between acetabular prosthesis and bone interface. Results In groups 1, 5, 6, 9 and 10, the Mises stress was unevenly distributed in posterior inferior, anterior superior and anterior inferior quadrants. In groups 2, 3, 4, 7 and 8, the Mises stress was evenly distributed in posterior inferior, anterior superior and anterior inferior quadrants. Of them, the stress was most even in the group 4. In groups 2, 3, 4, 7 and 8, the shear stress was evenly distributed in the above-mentioned three quadrants. The shear stress was lowest in the groups 7 and 8. These indicate that joint force in the acetabulum mainly focused in the posterior superior quadrant. With the displacement of acetabular cup, the contact area of acetabular cup and bone would gradually increase, which finally increased the Mises stress in the contact surface. However, shear stress decreased with displacement of acetabular medial wall. Conclusion the suitable displacement range of acetabular medial wall osteotomy is 1 mm away from the pelvic cavity and 1 mm complete embolism in the pelvic cavity. The optimal position was 1 mm complete embolism in the pelvic cavity.
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Stroylov, Victor, Maria Panova, and Philip Toukach. "Comparison of Methods for Bulk Automated Simulation of Glycosidic Bond Conformations." International Journal of Molecular Sciences 21, no. 20 (October 15, 2020): 7626. http://dx.doi.org/10.3390/ijms21207626.
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Six empirical force fields were tested for applicability to calculations for automated carbohydrate database filling. They were probed on eleven disaccharide molecules containing representative structural features from widespread classes of carbohydrates. The accuracy of each method was queried by predictions of nuclear Overhauser effects (NOEs) from conformational ensembles obtained from 50 to 100 ns molecular dynamics (MD) trajectories and their comparison to the published experimental data. Using various ranking schemes, it was concluded that explicit solvent MM3 MD yielded non-inferior NOE accuracy with newer GLYCAM-06, and ultimately PBE0-D3/def2-TZVP (Triple-Zeta Valence Polarized) Density Functional Theory (DFT) simulations. For seven of eleven molecules, at least one empirical force field with explicit solvent outperformed DFT in NOE prediction. The aggregate of characteristics (accuracy, speed, and compatibility) made MM3 dynamics with explicit solvent at 300 K the most favorable method for bulk generation of disaccharide conformation maps for massive database filling.
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Kobayashi, Naomi, Shota Higashihira, Haruna Kitayama, Emi Kamono, Yohei Yukizawa, Takayuki Oishi, Shu Takagawa, Hideki Honda, Hyonmin Choe, and Yutaka Inaba. "Effect of Decreasing the Anterior Pelvic Tilt on Range of Motion in Femoroacetabular Impingement: A Computer-Simulation Study." Orthopaedic Journal of Sports Medicine 9, no. 4 (April 1, 2021): 232596712199946. http://dx.doi.org/10.1177/2325967121999464.
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Background: The influence of pelvic tilt mobility, which can be reproduced in computer-simulation models, is an important subject to be addressed in the understanding of femoroacetabular impingement (FAI) pathophysiology. Purpose: To use computer-simulation models of FAI cases to evaluate the optimum improvement in hip range of motion (ROM) achieved by decreasing the anterior pelvic tilt and compare the results with the improvement in ROM achieved after cam resection surgery. Study Design: Controlled laboratory study. Methods: The pre- and postoperative computed tomography (CT) images from 28 patients with FAI treated with arthroscopic cam resection were evaluated. Using a dynamic computer-simulation program, 3-dimensional models with a 5° and a 10° decrease in anterior pelvic tilt from the supine functional pelvic plane (baseline) were created from the preoperative CT scans. Similar models were constructed for hips before (at baseline) and after cam resection. Improvements from baseline in maximum internal rotation at 45°, 70°, and 90° of flexion were assessed for the 5° change in pelvic tilt, 10° change in pelvic tilt, and cam resection models, and the results were compared for all conditions. Results: The combination of a 10° change in pelvic tilt and cam resection showed the largest ROM improvement from baseline ( P < .001). Improvement in internal rotation in the cam resection model was significantly higher compared with the 5° pelvic tilt change model ( P < .001), while there was no significant difference between the cam resection model and the 10° pelvic tilt change model. Conclusion: Decreasing anterior pelvic tilt by 10° in the preoperative computer simulation model resulted in an equivalent effect to cam resection, while a 5° change in pelvic tilt was inferior to cam resection in terms of ROM improvement. Clinical Relevance: Enough of a decrease in anterior pelvic tilt may contribute to ROM improvement that is as effective as that of cam resection surgery.
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Finlay, Dewar, Daniel Guldenring, Cathal Breen, and Raymond Bond. "Data Driven Computer Simulation to Analyse an ECG Limb Lead System Used in Connected Health Environments." Methods of Information in Medicine 55, no. 03 (2016): 258–65. http://dx.doi.org/10.3414/me15-01-0120.
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SummaryBackground: Recently under the Connected Health initiative, researchers and small-medium engineering companies have developed Electrocardiogram (ECG) monitoring devices that incorporate non-standard limb electrode positions, which we have named the Central Einthoven (CE) configuration.Objectives: The main objective of this study is to compare ECG signals recorded from the CE configuration with those recorded from the recommended Mason-Likar (ML) configuration.Methods: This study involved extracting two different sets of ECG limb leads from each patient to compare the difference in the signals. This was done using computer simulation that is driven by body surface potential maps. This simulator was developed to facilitate this experiment but it can also be used to test similar hypotheses. This study included, (a) 176 ECGs derived using the ML electrode positions and (b) the 176 corresponding ECGs derived using the CE electrode positions. The signals from these ECGs were compared using root mean square error (RMSE), Pearson product-moment correlation coefficient (r) and similarity coefficient (SC). We also investigated whether the CE configuration influences the calculated mean cardiac axis. The top 10 cases where the ECGs were significantly different between the two configurations were visually compared by an ECG interpreter.Results: We found that the leads aVL, III and aVF are most affected when using the CE configuration. The absolute mean difference between the QRS axes from both configurations was 28° (SD = 37°). In addition, we found that in 82% of the QRS axes calculated from the CE configuration was more rightward in comparison to the QRS axes derived from the ML configuration. Also, we found that there is an 18% chance that a misleading axis will be located in the inferior right quadrant when using the CE approach. Thus, the CE configuration can emulate right axis deviation. The clinician visually identified 6 out of 10 cases where the CE based ECG yielded clinical differences that could result in false positives.Conclusions: The CE configuration will not yield the same diagnostic accuracy for diagnosing pathologies that rely on current amplitude criteria. Conversely, rhythm lead II was not significantly affected, which supports the use of the CE approach for assessing cardiac rhythm only. Any computerised analysis of the CE based ECG will need to take these findings into consideration.
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Pal, Pralay. "Remaining Stock Computation for 3D-Machining in Parametric Regime." Journal of Manufacturing Science and Engineering 127, no. 4 (June 23, 2004): 801–9. http://dx.doi.org/10.1115/1.2034510.
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In manufacturing, it is often required to estimate uncut material shape between cutting stages in milling cycles. This may be useful to avoid undesired results like tool breakage, nonoptimized cutting time, and inferior surface finish besides other factors like improper feed-rate, large over-thickness, and inability of handling complex geometries. Current work discusses some strategy of ReSt (remaining stock) machining concept in CNC practices where machined and unmachined geometries are progressively computed and stored through different stages like roughing, semi-finishing, and finishing operations. The modeling of ReSt geometry in these stages is discussed with various possibilities in the parametric regime. The proposed algorithms are discussed with simulation results.
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Petkovšek, Marko, Mitja Nemec, and Peter Zajec. "Algorithm Execution Time and Accuracy of NTC Thermistor-Based Temperature Measurements in Time-Critical Applications." Mathematics 9, no. 18 (September 15, 2021): 2266. http://dx.doi.org/10.3390/math9182266.
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This paper addresses the challenges of selecting a suitable method for negative temperature coefficient (NTC) thermistor-based temperature measurement in electronic devices. Although measurement accuracy is of great importance, the temperature calculation time represents an even greater challenge since it is inherently constrained by the control algorithm executed in the microcontroller (MCU). Firstly, a simple signal conditioning circuit with the NTC thermistor is introduced, resulting in a temperature-dependent voltage UT being connected to the MCU’s analog input. Next, a simulation-based approximation of the actual temperature vs. voltage curve is derived, resulting in four temperature notations: for a look-up table principle, polynomial approximation, B equation and Steinhart–Hart equation. Within the simulation results, the expected temperature error of individual methods is calculated, whereas in the experimental part, performed on a DC/DC converter prototype, required prework and available MCU resources are evaluated. In terms of expected accuracy, the look-up table and the Steinhart–Hart equation offer superior results over the polynomial approximation and B equation, especially in the nominal temperature range of the NTC thermistor. However, in terms of required prework, the look-up table is inferior compared to the Steinhart–Hart equation, despite the latter having far more complex mathematical functions, affecting the overall MCU algorithm execution time significantly.
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Soto, David, Usman Ayub Sheikh, Ning Mei, and Roberto Santana. "Decoding and encoding models reveal the role of mental simulation in the brain representation of meaning." Royal Society Open Science 7, no. 5 (May 2020): 192043. http://dx.doi.org/10.1098/rsos.192043.
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How the brain representation of conceptual knowledge varies as a function of processing goals, strategies and task-factors remains a key unresolved question in cognitive neuroscience. In the present functional magnetic resonance imaging study, participants were presented with visual words during functional magnetic resonance imaging (fMRI). During shallow processing, participants had to read the items. During deep processing, they had to mentally simulate the features associated with the words. Multivariate classification, informational connectivity and encoding models were used to reveal how the depth of processing determines the brain representation of word meaning. Decoding accuracy in putative substrates of the semantic network was enhanced when the depth processing was high, and the brain representations were more generalizable in semantic space relative to shallow processing contexts. This pattern was observed even in association areas in inferior frontal and parietal cortex. Deep information processing during mental simulation also increased the informational connectivity within key substrates of the semantic network. To further examine the properties of the words encoded in brain activity, we compared computer vision models—associated with the image referents of the words—and word embedding. Computer vision models explained more variance of the brain responses across multiple areas of the semantic network. These results indicate that the brain representation of word meaning is highly malleable by the depth of processing imposed by the task, relies on access to visual representations and is highly distributed, including prefrontal areas previously implicated in semantic control.
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Gnambs, Timo, and Bernad Batinic. "Polytomous Adaptive Classification Testing." Educational and Psychological Measurement 71, no. 6 (January 28, 2011): 1006–22. http://dx.doi.org/10.1177/0013164410393956.
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Computer-adaptive classification tests focus on classifying respondents in different proficiency groups (e.g., for pass/fail decisions). To date, adaptive classification testing has been dominated by research on dichotomous response formats and classifications in two groups. This article extends this line of research to polytomous classification tests for two- and three-group scenarios (e.g., inferior, mediocre, and superior proficiencies). Results of two simulation experiments with generated and real responses ( N = 2,000) to established personality scales of different length (12, 20, or 29 items) demonstrate that adaptive item presentations significantly reduce the number of items required to make such classification decisions while maintaining a consistent classification accuracy. Furthermore, the simulations highlight the importance of the selected test termination criterion, which has a significant impact on the average test length.
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Bae, Jaesung, Hongsub Jee, Yongseob Park, and Jaehyeong Lee. "Simulation-Based Shading Loss Analysis of a Shingled String for High-Density Photovoltaic Modules." Applied Sciences 11, no. 23 (November 27, 2021): 11257. http://dx.doi.org/10.3390/app112311257.
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Shingled photovoltaic (PV) modules with increased output have attracted growing interest compared to conventional PV modules. However, the area per unit solar cell of shingled PV modules is smaller because these modules are manufactured by dividing and bonding solar cells, which means that shingled PV modules can easily have inferior shading characteristics. Therefore, analysis of the extent to which the shadow affects the output loss is essential, and the circuit needs to be designed accordingly. In this study, the loss resulting from the shading of the shingled string used to manufacture the shingled module was analyzed using simulation. A divided cell was modeled using a double-diode model, and a shingled string was formed by connecting the cell in series. The shading pattern was simulated according to the shading ratio of the vertical and horizontal patterns, and in the case of the shingled string, greater losses occurred in the vertical direction than the horizontal direction. In addition, it was modularized and compared with a conventional PV module and a shingled PV module. The results confirmed that the shingled PV module delivered higher shading output than the conventional PV module in less shade, and the result of the shading characteristic simulation of the shingled PV module was confirmed to be accurate within an error of 1%.
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Tang, Bao-Jun, Kun-Ben Lin, Jing-Bo Huang, and Hung-Wen Lin. "The Hesitation of Anxious Traders in an Agent-Based Model." Complexity 2022 (October 14, 2022): 1–22. http://dx.doi.org/10.1155/2022/5302302.
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Anxiety prevails in financial markets. In accordance with psychological research, anxious traders’ hesitant behavior differs from the frequently dissected herding and speculative behaviors. This paper examines the interactions between agent anxiety and price inertia in an artificial financial market. We incorporate an evolutionary mechanism to analyze the strategic benefit of the boundedly rational anxious agent. According to our simulation results, deviations in asset prices from their fundamentals increase with the behavioral hesitation of the anxious agent. The investment rigidity from the anxious agent’s lack of confidence mitigates the possibility of price reversal. Moreover, the average strategic benefit of the anxious agent is close to zero. To ensure the reliability of our finding, we further include the irrationality of the anxious agent in our evolutionary setting. Such an endeavor again demonstrates that the strategic benefit of the fundamentalist agent is inferior to that of the anxious agent. Since the anxious agent is characterized by an intolerance for uncertainty, we also investigate the artificial market under various degrees of risk aversion. We perceive that it is less possible for price reversal to emerge when considering higher levels of hesitation. The behavioral hesitation of the anxious agent enables the agent to cleverly evade the risk raised by the speculator.
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Zhang, Xinyu, Zhe Zhao, Chunlei Niu, Zengbiao Ma, Jianlei Hou, Guanjun Wang, and Miao Tang. "Spinal Biomechanical Modelling in the Process of Lumbar Intervertebral Disc Herniation in Middle-Aged and Elderly." Journal of Healthcare Engineering 2021 (October 29, 2021): 1–12. http://dx.doi.org/10.1155/2021/2869488.
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Lumbar disc herniation is one of the common clinical diseases of the lower lumbar spine in orthopedics. The purpose is to remove the herniated disc nucleus pulposus tissue, remove the compressed part of the disease, and relieve symptoms, such as nerve pain. In the past, biomechanics research mostly relied on in vitro measurements, but the complicated internal environment of the human body prevented us from further measurement and research. However, with the development of computer technology, the use of computer CT scanning, software three-dimensional reconstruction, and displacement study three-dimensional spine biomechanics method makes the research of biomechanics into in vitro simulation stage and has gradually become the focus of current research. The postoperative biomechanics was simulated and the comparison model was established at the same time. At the same time, we combined the clinical follow-up data and studied the clinical data for the treatment of postoperative recurrence of lumbar disc herniation. We compared and analyzed the initial operation method and the experimental results and obtained the prevention of recurrence. The results showed that when one inferior articular process was removed, the lumbar spine appeared unstable to rotate to the opposite side; when one inferior articular process was completely removed, the movement of the lumbar spine in all directions was unstable. Better research on the biomechanical properties of the spine will help the diagnosis and treatment of clinical lumbar disc herniation. Therefore, when performing posterior lumbar spine surgery, not only should the exposure of the surgical field and thorough decompression be considered, but also the biomechanical properties of the lumbar spine should be comprehensively evaluated.
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Gu, Chonglin, Ansong Feng, Guozhan Wang, and Xiqing Liu. "Robot Path Planning of Improved Adaptive Ant Colony System Algorithm Based on Dijkstra." Journal of Robotics 2022 (December 15, 2022): 1–11. http://dx.doi.org/10.1155/2022/9229155.
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Path planning is one of the key technologies of robot. Aiming at the problems of slow convergence speed and inefficient search of traditional Ant Colony System Algorithm, an adaptive Ant Colony System Algorithm based on Dijkstra is proposed in the paper. Firstly, Dijkstra algorithm is applied to searching the initial path in the grid environment, constructing the initial path, optimizing the initial pheromone in the region, therefore, the Ant Colony System Algorithm avoid falling into blind search in the initial stage; In the transition probability, the disguised angle probability function and parameter adaptive pseudo-random proportion rule are introduced to improve the search efficiency and convergence speed of the algorithm, and eliminate the inferior ant path; Finally, B-spline interpolation curve is used to smooth the path. Compared with the traditional Ant Colony System Algorithm, the simulation results in the grid environment demonstrating its effectiveness to improve convergence speed and to enhance search efficiency are provided. The characteristics of the improved Ant Colony System Algorithm are faster convergence speed and better planning.
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Kapalova, Nursulu, Kairat Sakan, Kunbolat Algazy, and Dilmukhanbet Dyusenbayev. "Development and Study of an Encryption Algorithm." Computation 10, no. 11 (November 4, 2022): 198. http://dx.doi.org/10.3390/computation10110198.
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A new symmetric block cipher algorithm called AL02 has been developed. The algorithm scheme provides five-round encryption of 128-bit blocks, while the data size at the input and output of the S-box is 8 bits. The main transformation is the F transformation. The difference between the proposed algorithm and the classical scheme is that the F transformation provides the maximum possible dependence of the output vector bits on the input bits and is based on “modulo 2 addition” and a substitution S-box. To assess the strength of the AL02 algorithm, it was programmatically implemented in the C programming language. During the analysis, the cryptographic properties of the developed encryption algorithm were tested. The algorithm was tested for statistical security. For an experimental assessment, in order to ensure that the ciphertext is not inferior to a random sequence in its properties, the well-known sets of statistical tests by NIST (National Institute of Standards and Technology) and Donald Knuth were used. The property of the avalanche effect was also checked. The strength was evaluated using the methods of differential and linear cryptanalysis.
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Li, Xiaoyue, Chaoqun Zhou, Zilong Liang, Qiang Yu, Xiankai Chen, and Zhiyuan He. "UCB-Based Route and Power Selection Optimization for SDN-Enabled Industrial IoT in Smart Grid." Wireless Communications and Mobile Computing 2022 (March 20, 2022): 1–9. http://dx.doi.org/10.1155/2022/7424854.
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As an essential building block for smart grid, the industrial internet of things (IIoT) plays a significant role in providing powerful sensing capability and ubiquitous connectivity for differentiated power services. The rapid development of smart grid imposes higher data monitoring and transmission requirements in terms of delay and energy efficiency. However, due to the severe electromagnetic interference (EMI) caused by massive electrical equipment, the transmission performance of IIoT becomes inferior. The traditional single-hop transmission mode evolves towards a multihop cooperation mode to satisfy differentiated quality of service (QoS) requirements. In this paper, we propose an upper confidence bound- (UCB-) based joint route and power selection optimization algorithm to support multihop cooperation mode evolution, which adopts a software-defined networking- (SDN-) enabled IIoT network framework to simplify network configuration and management. Compared with existing local-side-information-based route selection (LSI-RS) and random route selection (RRS) algorithms, simulation results demonstrate that the proposed algorithm has superior performances in total delay, energy efficiency, and utility.
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FENG, HAIQUAN, KUN WANG, HONGRAN QIU, and DONG WANG. "RESEARCH ON BIOMECHANICS PROPERTIES AND HEMODYNAMICS PERFORMANCE OF THE CONVERTIBLE VENA CAVA FILTER." Journal of Mechanics in Medicine and Biology 17, no. 07 (November 2017): 1740022. http://dx.doi.org/10.1142/s021951941740022x.
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This paper reveals the biomechanical properties and hemodynamics performance of the convertible vena cava filter while it was in the process of implantation and conversion in the blood vessels. This paper uses the finite element method and computational fluid dynamics to analyze the interaction mechanism and influence of the convertible vena cava filter while the filter was in the process of implantation and conversion in the blood vessels. Additionally, six pigs were used as experimental samples to verify the effects of the filter in the blood vessels. The computer-aided simulation results showed that it was easier to cause damage to the vessel wall prior to the filter being converted into support. On the contrary, the stress, the peak value of the blood vessel’s stress, the outlet velocity, and the supporting stiffness were reduced after the conversion. Due to the intimal hyperplasia, the supporting element was easy to fix on the inner surface of the blood vessels, which was helpful for the correct positioning of the filter after the conversion. Meanwhile, the animal experiments proved that the surface of inferior vena cava wall was relatively smooth, and the filter did not cause vascular wall rupture. The computer-aided simulation and animal experiments proved the reasonability of the structure of the filter design, and that the filter has good biomechanical properties. The results will provide more scientific reference for the clinical treatment and design of the filter.
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Mei, Youping, and Kim A. Stelson. "Lapping Control of Hard Disk Drive Heads." Journal of Dynamic Systems, Measurement, and Control 123, no. 3 (February 28, 2000): 439–48. http://dx.doi.org/10.1115/1.1386650.
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Bar lapping is a key process in fabricating computer hard disk drive heads. The purpose is to remove a small amount of material so that the transducer stripe height variation across the bar is minimized. In this article a method of simulating the material removal process is established. The Preston model is identified to be a reasonable constitutive relationship relating lapping rate to pressure and relative velocity. A pressure estimation method is established based on the modified beam on elastic foundation model (MBOEF) to incorporate the effect of surface shape. Simulation is conducted based on the proposed constitutive relationship and MBOEF. Results show good agreement with production observations. Hence the simulation model is used as a tool for identifying the structure of the lapping control model. The pressure dynamics of bar lapping is then identified. The process model is constructed based on the pressure dynamics and the Preston model. A controller is then designed using a trajectory following formulation. Simulation of the controller shows that it is robust to parameter uncertainties. This controller is implemented on a Seagate lapping system. Experiment results show that the proposed method is less sensitive than the existing method to the quality of the bar preparation processes prior to lapping. However, the gains should be appropriately adjusted for optimal performance. With good preparation processes and appropriate gains, performance of the proposed and existing methods are statistically comparable. Otherwise, the proposed method performs better. The proposed method is inferior to the existing method only when its gains are improperly adjusted.
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Wehsener, Sandra, Matthias Heinke, Robin Müssig, Johannes Hörth, Stefan Junk, and Steffen Schrock. "3d print of heart rhythm model with cryoballoon catheter ablation of pulmonary vein." Current Directions in Biomedical Engineering 5, no. 1 (September 1, 2019): 235–38. http://dx.doi.org/10.1515/cdbme-2019-0060.
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AbstractThe visualization of heart rhythm disturbance and atrial fibrillation therapy allows the optimization of new cardiac catheter ablations. With the simulation software CST (Computer Simulation Technology, Darmstadt) electromagnetic and thermal simulations can be carried out to analyze and optimize different heart rhythm disturbance and cardiac catheters for pulmonary vein isolation. Another form of visualization is provided by haptic, three-dimensional print models. These models can be produced using an additive manufacturing method, such as a 3d printer. The aim of the study was to produce a 3d print of the Offenburg heart rhythm model with a representation of an atrial fibrillation ablation procedure to improve the visualization of simulation of cardiac catheter ablation. The basis of 3d printing was the Offenburg heart rhythm model and the associated simulation of cryoablation of the pulmonary vein. The thermal simulation shows the pulmonary vein isolation of the left inferior pulmonary vein with the cryoballoon catheter Arctic Front AdvanceTM from Medtronic. After running through the simulation, the thermal propagation during the procedure was shown in the form of different colors. The three-dimensional print models were constructed on the base of the described simulation in a CAD program. Four different 3d printers are available for this purpose in a rapid prototyping laboratory at the University of Applied Science Offenburg. Two different printing processes were used and a final print model with additional representation of the esophagus and internal esophagus catheter was also prepared for printing. With the help of the thermal simulation results and the subsequent evaluation, it was possible to draw a conclusion about the propagation of the cold emanating from the catheter in the myocardium and the surrounding tissue. It was measured that just 3 mm from the balloon surface into the myocardium the temperature dropped to 25 °C. The simulation model was printed using two 3d printing methods. Both methods, as well as the different printing materials offer different advantages and disadvantages. All relevant parts, especially the balloon catheter and the conduction, are realistically represented. Only the thermal propagation in the form of different colors is not shown on this model. Three-dimensional heart rhythm models as well as virtual simulations allow very clear visualization of complex cardiac rhythm therapy and atrial fibrillation treatment methods. The printed models can be used for optimization and demonstration of cryoballoon catheter ablation in patients with atrial fibrillation.
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Das, Samadrita, Trupti Ranjan Lenka, Fazal Ahmed Talukdar, Ravi Teja Velpula, Barsha Jain, Hieu Pham Trung Nguyen, and Giovanni Crupi. "Effects of polarized-induced doping and graded composition in an advanced multiple quantum well InGaN/GaN UV-LED for enhanced light technology." Engineering Research Express 4, no. 1 (March 1, 2022): 015030. http://dx.doi.org/10.1088/2631-8695/ac4fb1.
Full textAbstract:
Abstract In this paper, a light-emitting diode in the ultra-violet range (UV-LED) with multiple-quantum wells (MQWs) of InGaN/GaN is designed and analyzed through Technology Computer-Aided Design (TCAD) simulations. The polarization effects in III-nitride heterojunction and the effects of graded composition in the electron blocking layer (EBL) are exploited to enhance the performance of the proposed UV-LED. It is observed that the effect of graded composition in the EBL helps to enhance the electrical and optical performance of the LED, thereby enabling the achievement of some promising results. The simulation-based results demonstrated that superior internal efficiency and an inferior leakage current are achieved by using a graded Al composition in the EBL rather than a uniform composition. The reported results also confirm the remarkable improvement of the light output power by 17% at ∼100 mA when using the graded composition and also show a reduction in series resistance leading to more current. Graded Al composition in the EBL results in the enhancement of electroluminescence spectra (i.e., an increase in the peak of the spectral density).
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Irawan, Addie, Mohammad Fadhil Abas, and Nurulfadzilah Hasan. "Robot Local Network Using TQS Protocol for Land-to-Underwater Communications." Journal of Telecommunications and Information Technology 1 (March 29, 2019): 23–30. http://dx.doi.org/10.26636/jtit.2019.125818.
Full textAbstract:
This paper presents a model and an analysis of the Tag QoS switching (TQS) protocol proposed for heterogeneous robots operating in different environments. Collaborative control is topic that is widely discussed in multirobot task allocation (MRTA) – an area which includes establishing network communication between each of the connected robots. Therefore, this research focuses on classifying, prioritizing and analyzing performance of the robot local network (RLN) model which comprises a point-to-point topology network between robot peers (nodes) in the air, on land, and under water. The proposed TQS protocol was inspired by multiprotocol label switching (MPLS), achieving a quality of service (QoS) where swapping and labeling operations involving the data packet header were applied. The OMNET++ discrete event simulator was used to analyze the percentage of losses, average access delay, and throughput of the transmitted data in different classes of service (CoS), in a line of transmission between underwater and land environments. The results show that inferior data transmission performance has the lowest priority with low bitrates and extremely high data packet loss rates when the network traffic was busy. On the other hand, simulation results for the highest CoS data forwarding show that its performance was not affected by different data transmission rates characterizing different mediums and environments.
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Zhang, Zane, and Jason S. Dunham. "A Simulation Study to Evaluate Survey Designs and Assessment Models for Estimation of Dungeness Crab (Cancer magister) Softshell Periods." Open Fish Science Journal 9, no. 1 (December 27, 2016): 57–74. http://dx.doi.org/10.2174/1874401x01609010057.
Full textAbstract:
Softshell Dungeness Crabs have inferior meat quality and are vulnerable to handling by harvesters; therefore, knowing when softshell periods occur is important for managing Dungeness Crab fisheries. A computer simulation was used to study the effectiveness of several survey designs and statistical models for estimating softshell periods which normally would be construed from crab shell condition data obtained from trap surveys. Survey designs varied in the number of years of data collection (1, 3, 5 or 10 years) and by the number and arrangement of sampling events per year. Three statistical models, including standardized catch-per-unit-effort (SCPUE), hierarchical, and generalized additive, were tested using catch-per-unit-effort data (CPUEs) or CPUE- transformed data. CPUEs were standardised by dividing CPUE estimates by the maximum CPUE obtained in the sample year, and then transformed using the complementary log-log function. In the hierarchical model, CPUEs were modelled using a lognormal distribution, assuming the expected logarithms of CPUEs are a quadratic function of days plus a random normal error. CPUE-transformed data were modelled using a normal distribution, assuming expected values are a quadratic function of days in the SCPUE model or a spline smooth function of days in the generalized additive model. Results suggest the best survey design requires a relatively high number (6 or 11) of sampling events during several key consecutive months which contain the softshell period, and fewer sampling events during those months when softshell crab abundance is low. A minimum 3 years of data collection is required to produce reliable outputs. The hierarchical model performs best, slightly better than the SCPUE model. Use of the generalized additive model is not recommended.