A Wearable Wrist Band-Type System for Multimodal Biometrics Integrated with Multispectral Skin Photomatrix and Electrocardiogram Sensors

Multimodal biometrics are promising for providing a strong security level for personal authentication, yet the implementation of a multimodal biometric system for practical usage need to meet such criteria that multimodal biometric signals should be easy to acquire but not easily compromised. We developed a wearable wrist band integrated with multispectral skin photomatrix (MSP) and electrocardiogram (ECG) sensors to improve the issues of collectability, performance and circumvention of multimodal biometric authentication. The band was designed to ensure collectability by sensing both MSP and ECG easily and to achieve high authentication performance with low computation, efficient memory usage, and relatively fast response. Acquisition of MSP and ECG using contact-based sensors could also prevent remote access to personal data. Personal authentication with multimodal biometrics using the integrated wearable wrist band was evaluated in 150 subjects and resulted in 0.2% equal error rate ( EER ) and 100% detection probability at 1% FAR (false acceptance rate) ( PD . 1 ), which is comparable to other state-of-the-art multimodal biometrics. An additional investigation with a separate MSP sensor, which enhanced contact with the skin, along with ECG reached 0.1% EER and 100% PD . 1 , showing a great potential of our in-house wearable band for practical applications. The results of this study demonstrate that our newly developed wearable wrist band may provide a reliable and easy-to-use multimodal biometric solution for personal authentication.

Dopamine neurons learn relative chosen value from probabilistic rewards

Economic theories posit reward probability as one of the factors defining reward value. Individuals learn the value of cues that predict probabilistic rewards from experienced reward frequencies. Building on the notion that responses of dopamine neurons increase with reward probability and expected value, we asked how dopamine neurons in monkeys acquire this value signal that may represent an economic decision variable. We found in a Pavlovian learning task that reward probability-dependent value signals arose from experienced reward frequencies. We then assessed neuronal response acquisition during choices among probabilistic rewards. Here, dopamine responses became sensitive to the value of both chosen and unchosen options. Both experiments showed also the novelty responses of dopamine neurones that decreased as learning advanced. These results show that dopamine neurons acquire predictive value signals from the frequency of experienced rewards. This flexible and fast signal reflects a specific decision variable and could update neuronal decision mechanisms.

Unveiling modal parameters with forced response using SVD and QR during flutter flight testing

This article presents an algorithm for the identification of modal parameters during flutter flight testing when forced excitation is employed and the aircraft possesses several sensors for structural response acquisition. The main novelty of the method, when compared with other classical modal analysis methods, is that the analysis is carried out in intervals of time instead of in the whole duration of the excitation. It means that, even when the response signal is only partially available, some modal parameters may be still identified. Application to analytic signals as well as structural response of modern fighter aircraft using frequency-swept excitation is provided in order to demonstrate the effectiveness, robustness and noise immunity of the proposed method.

EFFECTS OF MALNUTRITION AND ENVIRONMENT ON THE ACQUISITION AND EXTICTION OF AVOIDANCE BEHAVIOR IN RATS

Twelve newborn rats were fed by mothers maintained on protein-deficient diet (12% casein, M) during lactation, and 12 rats fed by mothers maintained on a diet containing 25% casein were used as controls (C). After weaning, all animals were standard lab ration. Half of each group was housed individually (MI and CI), while the other half was allowed to live in pairs (MP and CP). When adult, all animals were trained to avoid footshocks by jumping onto a platform. Trainiing sessions consisted of 40 trials starting with a 20 sec light stimulus (CS) and followed by a 2 sec, 0.6 mA shock (US) with an average interval of 54 sec. When all animals displayed consistent avoidance behavior, the extinction phase was initiated. The produce was the same as for the training session except that shock generator was disconnected. Extinction continued until each animal showed a 50% reduction in avoidance performance. During acquisition, MI learned faster than CI and CI showed greater avoidance performance than CP, but no differences were observed between MP and CP. During extinction, group M responded more persistently than group C. The present acquisition results may explain the contradictory data reported in the literature with respect to the effects of malnutrition on avoidance performance, since environmental stimulation was shown to reduce the effects of early malnutrition. Individually housed animals showed greater avoidance performance during both phases. Keywords: Protein malnutrition, avoidance response, acquisition, extinction, environmental stimulation.