New perspectives on material mediation in language learner pedagogy. LaScotte, D. K., Mathieu, C. S., David, S. S. (Ed.) (2022). Springer, Cham, 286 pages, ISBN: 978-3-030-98115-0

Despite the ubiquity of materials in language classrooms, there remains a deficit in the research on materials use and the role of material mediation in foreign language teaching and learning. This edited volume New Perspectives on Material Mediation in Language Learner Pedagogy by LaScotte, Mathieu, and David is aimed to fill such a gap.Despite the ubiquity of materials in language classrooms, there remains a deficit in the research on materials use and the role of material mediation in foreign language teaching and learning. This edited volume New Perspectives on Material Mediation in Language Learner Pedagogy by LaScotte, Mathieu, and David is aimed to fill such a gap

Inferring Mobile Payment Passcodes Leveraging Wearable Devices

Mobile payment has drawn considerable attention due to its convenience of paying via personal mobile devices at anytime and anywhere, and passcodes (i.e., PINs) are the first choice of most consumers to authorize the payment. This work demonstrates a serious security breach and aims to raise the awareness of the public that the passcodes for authorizing transactions in mobile payments can be leaked by exploiting the embedded sensors in wearable devices (e.g., smartwatches). We present a passcode inference system, which examines to what extent the user's PIN during mobile payment could be revealed from a single wrist-worn wearable device under different input scenarios involving either two hands or a single hand. Extensive experiments with 15 volunteers demonstrate that an adversary is able to recover a user's PIN with high success rate within 5 tries under various input scenarios

Deformation Mechanisms in Pd Nanowhiskers

The reduced length scales inherent in nanoscale materials enable access to properties that are otherwise not achievable in bulk. The application of their novel structural and functional responses however is hindered by a lack of understanding of their mechanical behavior, which affects their assimilation into device fabrication as well as their reliability during performance. In contrast to bulk materials, nanoscale materials possess a non-negligible proportion of surface atoms, which can exert significant influence on the overall mechanical response. In addition, structures with small volumes can possess much lower defect densities, which could potentially be driven out of the volume instead of interacting and promoting traditional deformation behavior. Systematic experimental investigations will be crucial to developing the necessary understanding, although they remain challenging due to limited access to suitable test specimens and testing methodologies for directly extracting pertinent results. By employing a MEMS-based tensile testing system and a temperature-controlled cryostat configuration to test defect-free and -scarce Pd nanowhiskers, we have been able to systematically investigate some of the important deformation mechanisms in nanoscale single crystals. We first address the elastic behavior in nanoscale crystals, which is predicted to differ from bulk behavior due to the reduced coordination of surface atoms. We measured size-dependent deviations from bulk elastic behavior in nanowhiskers with diameters as small as ~30 nm. In addition to size-dependent variations in Young\u27s modulus in the small strain limit, we measured nonlinear elasticity at strains above ~1%. In addition to providing the first measurements of higher-order elasticity in Pd, our study shows that the elasticity response in Pd nanowhiskers can be attributed to higher-order elasticity in the bulk-like core upon being biased from its equilibrium configuration due to the role of surface stresses in small volumes. Comparison of the size-independent values of δ in our nanowhiskers with studies on bulk FCC metals lends further insight into the role of length scales on both elastic and plastic mechanical behavior. We then consider incipient plasticity in nanoscale Pd nanowhiskers, which is governed not by the initial motion of pre-existing dislocations but rather the nucleation of dislocations. Whereas nucleation strengths are weakly size- and strain-rate-dependent, strong temperature dependence is uncovered, corroborating predictions that nucleation is assisted by thermal fluctuations. We measure activation volumes as small as singular atomic volumes, which explain both the ultrahigh athermal strength as well as the temperature-dependent scatter, evident in our experiments and well captured by a thermal activation model. Our experiments highlight the pronounced probabilistic nature of surface dislocation nucleation, which is crucial input to device design using nanoscale building blocks. In total, this body of work demonstrates that distinctly different processes are responsible for the deformation behavior in small volumes and underscores the importance of comprehensive characterization of material properties at the relevant length scales

CardioCam: Leveraging Camera on Mobile Devices to Verify Users While Their Heart is Pumping

With the increasing prevalence of mobile and IoT devices (e.g., smartphones, tablets, smart-home appliances), massive private and sensitive information are stored on these devices. To prevent unauthorized access on these devices, existing user verification solutions either rely on the complexity of user-defined secrets (e.g., password) or resort to specialized biometric sensors (e.g., fingerprint reader), but the users may still suffer from various attacks, such as password theft, shoulder surfing, smudge, and forged biometrics attacks. In this paper, we propose, CardioCam, a low-cost, general, hard-to-forge user verification system leveraging the unique cardiac biometrics extracted from the readily available built-in cameras in mobile and IoT devices. We demonstrate that the unique cardiac features can be extracted from the cardiac motion patterns in fingertips, by pressing on the built-in camera. To mitigate the impacts of various ambient lighting conditions and human movements under practical scenarios, CardioCam develops a gradient-based technique to optimize the camera configuration, and dynamically selects the most sensitive pixels in a camera frame to extract reliable cardiac motion patterns. Furthermore, the morphological characteristic analysis is deployed to derive user-specific cardiac features, and a feature transformation scheme grounded on Principle Component Analysis (PCA) is developed to enhance the robustness of cardiac biometrics for effective user verification. With the prototyped system, extensive experiments involving 25 subjects are conducted to demonstrate that CardioCam can achieve effective and reliable user verification with over 99% average true positive rate (TPR) while maintaining the false positive rate (FPR) as low as 4%