Time-series detection of perspiration as a liveness test in fingerprint devices

Fingerprint scanners may be susceptible to spoofing using artificial materials, or in the worst case, dismembered fingers. An anti-spoofing method based on liveness detection has been developed for use in fingerprint scanners. This method quantifies a specific temporal perspiration pattern present in fingerprints acquired from live claimants. The enhanced perspiration detection algorithm presented here improves our previous work by including other fingerprint scanner technologies; using a larger, more diverse data set; and a shorter time window. Several classification methods were tested in order to separate live and spoof fingerprint images. The dataset included fingerprint images from 33 live subjects, 33 spoofs created with dental material and Play-Doh, and fourteen cadaver fingers. Each method had a different performance with respect to each scanner and time window. However, all the classifiers achieved approximately 90% classification rate for all scanners, using the reduced time window and the more comprehensive training and test sets.     

On techniques for angle compensation in nonideal iris recognition.

The popularity of the iris biometric has grown considerably over the past two to three years. Most research has been focused on the development of new iris processing and recognition algorithms for frontal view iris images. However, a few challenging directions in iris research have been identified, including processing of a nonideal iris and iris at a distance. In this paper, we describe two nonideal iris recognition systems and analyze their performance. The word "nonideal" is used in the sense of compensating for off-angle occluded iris images. The system is designed to process nonideal iris images in two steps: 1) compensation for off-angle gaze direction and 2) processing and encoding of the rotated iris image. Two approaches are presented to account for angular variations in the iris images. In the first approach, we use Daugman's integrodifferential operator as an objective function to estimate the gaze direction. After the angle is estimated, the off-angle iris image undergoes geometric transformations involving the estimated angle and is further processed as if it were a frontal view image. The encoding technique developed for a frontal image is based on the application of the global independent component analysis. The second approach uses an angular deformation calibration model. The angular deformations are modeled, and calibration parameters are calculated. The proposed method consists of a closed-form solution, followed by an iterative optimization procedure. The images are projected on the plane closest to the base calibrated plane. Biorthogonal wavelets are used for encoding to perform iris recognition. We use a special dataset of the off-angle iris images to quantify the performance of the designed systems. A series of receiver operating characteristics demonstrate various effects on the performance of the nonideal-iris-based recognition system.     

Hemifield-specific visual recognition memory impairments in patients with unilateral temporal lobe removals

Recent evidence on visual neglect suggests that each hemisphere maintains a retinotopically organized representation of the visual world contralateral to the current fixation point and that this representation is based not only on analysis of the current retinal input but, equally importantly, on information retrieved from memory. This idea predicts that unilateral damage to memory systems should produce a lateralized impairment of memory for the retinotopically contralateral visual world. To test this prediction we examined visual recognition memory performance in the left and right visual hemifields of patients who had undergone partial unilateral temporal lobe removals for the relief of epilepsy, either in the left hemisphere (n = 5) or the right (n = 5). The patients were given complex artificial scenes to remember, constructed of independent left and right halves, and were then tested for recognition of the left and the right halves separately. Stimuli were exposed tachistoscopically throughout and fixation was maintained on a central position. Patients made significantly more errors with half-scenes in the hemifield contralateral to their removal than in the ipsilateral hemifield, an increase of 50% in the error rate on average. The effect was seen equally in patients with left and right removals. This finding supports the idea that visual memory retrieval is retinotopically organized.     

A 1.5 Gb/s link interface chipset for computer data transmission

The authors designed a set of four ICs to provide encoding, multiplexing, clock extraction/demultiplexing, and decoding for gigabit-rate serial data transmission. These chips form a high bandwidth data link for point-to-point communication. A new line code is implemented that provides DC balance, efficient encoding, framing, and simple clock extraction. Embedded in the code is a fixed transition used by the phase/frequency locked loop (PLL) for simple clock extraction and frame synchronization. Unlike other links, this PLL requires no trimming for data retiming, either in production or later. An on-chip voltage-controlled oscillator (VCO) with a tuning range of 1.1-1.6 GHz is available for use with the PLL. With this chip set the authors demonstrated a transmission rate of 16 bits in parallel at 75 MHz or, with encoding overhead, a serial rate of 1.5 Gb/s     

An image-rejecting mixer and vector filter with 55-dB imagerejection over process, temperature, and transistor mismatch

This paper describes an image-rejecting mixer and vector filter for use in radio systems with channel bandwidths in the range of 1 MHz. The circuit replaces the SAW filter and second downconverter commonly used in this style of radio. Because the output of the circuit is at an IF of 5 MHz, traditional demodulation methods including limiting and FM discrimination can still be used. The circuit is based on a quadrature mixer that guarantees good performance despite device mismatches and process variation. The circuit consumes 29 mA at 3.3 V,and achieves better than 55-dB image rejection despite device mismatches and process variation and is implemented in a single-poly triple metal 0.5 μm CMOS process with linear capacitor implants. The circuit is designed for input signals from 125 to 250 MHz. Input referred voltage noise is 900 μVrms. The in-band IP3 is 18 dBm. By changing an external reference frequency, the passband width of the filter can be varied from 3 to 0.5 MHz     

Pressure pouring steel slabs

The application of Controlled Pressure Pouring to the production of stainless as well as low-carbon steel slabs, with particular emphasis on economics. Included is a discussion by J. N. Hornak of U.S. Steel Corp., and Bruce M. Hamilton of Atlas Steels Co.     

Detection of mercury(II) by quantum dot/DNA/gold nanoparticle ensemble based nanosensor via nanometal surface energy transfer

An ultrasensitive fluorescent sensor based on the quantum dot/DNA/gold nanoparticle ensemble has been developed for detection of mercury(II). DNA hybridization occurs when Hg(II) ions are present in the aqueous solution containing the DNA-conjugated quantum dots (QDs) and Au nanoparticles. As a result, the QDs and the Au nanoparticles are brought into the close proximity, which enables the nanometal surface energy transfer (NSET) from the QDs to the Au nanoparticles, quenching the fluorescence emission of the QDs. This nanosensor exhibits a limit of detection of 0.4 and 1.2 ppb toward Hg(II) in the buffer solution and in the river water, respectively. The sensor also shows high selectivity toward the Hg(II) ions.