Minimal basilar membrane motion in low-frequency hearing

Low-frequency hearing is critically important for speech and music perception, but no mechanical measurements have previously been available from inner ears with intact low-frequency parts. These regions of the cochlea may function in ways different from the extensively studied high-frequency regions, where the sensory outer hair cells produce force that greatly increases the sound-evoked vibrations of the basilar membrane. We used laser interferometry in vitro and optical coherence tomography in vivo to study the low-frequency part of the guinea pig cochlea, and found that sound stimulation caused motion of a minimal portion of the basilar membrane. Outside the region of peak movement, an exponential decline in motion amplitude occurred across the basilar membrane. The moving region had different dependence on stimulus frequency than the vibrations measured near the mechanosensitive stereocilia. This behavior differs substantially from the behavior found in the extensively studied high-frequency regions of the cochlea

Introducing a framework to assess newly created questions with Natural Language Processing

Statistical models such as those derived from Item Response Theory (IRT) enable the assessment of students on a specific subject, which can be useful for several purposes (e.g., learning path customization, drop-out prediction). However, the questions have to be assessed as well and, although it is possible to estimate with IRT the characteristics of questions that have already been answered by several students, this technique cannot be used on newly generated questions. In this paper, we propose a framework to train and evaluate models for estimating the difficulty and discrimination of newly created Multiple Choice Questions by extracting meaningful features from the text of the question and of the possible choices. We implement one model using this framework and test it on a real-world dataset provided by CloudAcademy, showing that it outperforms previously proposed models, reducing by 6.7% the RMSE for difficulty estimation and by 10.8% the RMSE for discrimination estimation. We also present the results of an ablation study performed to support our features choice and to show the effects of different characteristics of the questions' text on difficulty and discrimination.Comment: Accepted at the International Conference of Artificial Intelligence in Educatio

Effects of ferroelectric polarization and converse piezoelectric effect induced lattice strain on the electrical properties of La[sub 0.7]Sr[sub 0.3]MnO₃ thin films

Author name used in this publication: R. K. ZhengAuthor name used in this publication: J. WangAuthor name used in this publication: X. Y. ZhouAuthor name used in this publication: Y. WangAuthor name used in this publication: H. L. W. ChanAuthor name used in this publication: C. L. ChoyAuthor name used in this publication: H. S. Luo2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Control of the strain and magnetoresistance of LaMnO[sub 3+δ] thin films using the magnetostriction of Terfenol-D alloy

Author name used in this publication: Y. WangAuthor name used in this publication: H. L. W. ChanAuthor name used in this publication: C. L. ChoyAuthor name used in this publication: H. S. Luo2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Tuning the electrical properties of La[sub 0.75]Ca[sub 0.25]MnO₃ thin films by ferroelectric polarization, ferroelectric-field effect, and converse piezoelectric effect

2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

An Electrocorticographic Brain Interface in an Individual with Tetraplegia

Brain-computer interface (BCI) technology aims to help individuals with disability to control assistive devices and reanimate paralyzed limbs. Our study investigated the feasibility of an electrocorticography (ECoG)-based BCI system in an individual with tetraplegia caused by C4 level spinal cord injury. ECoG signals were recorded with a high-density 32-electrode grid over the hand and arm area of the left sensorimotor cortex. The participant was able to voluntarily activate his sensorimotor cortex using attempted movements, with distinct cortical activity patterns for different segments of the upper limb. Using only brain activity, the participant achieved robust control of 3D cursor movement. The ECoG grid was explanted 28 days post-implantation with no adverse effect. This study demonstrates that ECoG signals recorded from the sensorimotor cortex can be used for real-time device control in paralyzed individuals

Servant leadership as a driver of employee service performance: Test of a trickle-down model and its boundary conditions

Previous research has demonstrated the role of servant leadership, a leadership style emphasizing serving others, in promoting frontline employees’ service performance. It is unclear, however, how servant leadership by leaders at different organizational levels would exert such an influence. Integrating insights from both social learning theory and the trickle-down paradigm of leadership, we develop a cross-level model in which we argue that servant leadership by high-level managers could cascade downward through the organizational hierarchy to influence frontline employees’ service performance and that this trickle-down effect is contingent on the extent to which subordinates identify their leaders as embodying the organization. Using a matched sample of 92 supervisors and 568 frontline employees across 92 sub-branches of a large banking company, we found that servant leadership by high-level managers could indeed promote employees’ in-role and extra-role service performance through its effect on low-level supervisors’ servant leadership. We also found that this trickle-down effect was stronger when high-level managers and low-level supervisors were perceived by their subordinates as more fully embodying the organization. Implications, limitations and future directions are discussed

Hybrid-MST: A hybrid active sampling strategy for pairwise preference aggregation

In this paper we present a hybrid active sampling strategy for pairwise preference aggregation, which aims at recovering the underlying rating of the test candidates from sparse and noisy pairwise labelling. Our method employs Bayesian optimization framework and Bradley-Terry model to construct the utility function, then to obtain the Expected Information Gain (EIG) of each pair. For computational efficiency, Gaussian-Hermite quadrature is used for estimation of EIG. In this work, a hybrid active sampling strategy is proposed, either using Global Maximum (GM) EIG sampling or Minimum Spanning Tree (MST) sampling in each trial, which is determined by the test budget. The proposed method has been validated on both simulated and real-world datasets, where it shows higher preference aggregation ability than the state-of-the-art methods

Numerical Modeling of Fluid Flow in Solid Tumors

A mathematical model of interstitial fluid flow is developed, based on the application of the governing equations for fluid flow, i.e., the conservation laws for mass and momentum, to physiological systems containing solid tumors. The discretized form of the governing equations, with appropriate boundary conditions, is developed for a predefined tumor geometry. The interstitial fluid pressure and velocity are calculated using a numerical method, element based finite volume. Simulations of interstitial fluid transport in a homogeneous solid tumor demonstrate that, in a uniformly perfused tumor, i.e., one with no necrotic region, because of the interstitial pressure distribution, the distribution of drug particles is non-uniform. Pressure distribution for different values of necrotic radii is examined and two new parameters, the critical tumor radius and critical necrotic radius, are defined. Simulation results show that: 1) tumor radii have a critical size. Below this size, the maximum interstitial fluid pressure is less than what is generally considered to be effective pressure (a parameter determined by vascular pressure, plasma osmotic pressure, and interstitial osmotic pressure). Above this size, the maximum interstitial fluid pressure is equal to effective pressure. As a consequence, drugs transport to the center of smaller tumors is much easier than transport to the center of a tumor whose radius is greater than the critical tumor radius; 2) there is a critical necrotic radius, below which the interstitial fluid pressure at the tumor center is at its maximum value. If the tumor radius is greater than the critical tumor radius, this maximum pressure is equal to effective pressure. Above this critical necrotic radius, the interstitial fluid pressure at the tumor center is below effective pressure. In specific ranges of these critical sizes, drug amount and therefore therapeutic effects are higher because the opposing force, interstitial fluid pressure, is low in these ranges