Face recognition technologies for evidential evaluation of video traces

Human recognition from video traces is an important task in forensic investigations and evidence evaluations. Compared with other biometric traits, face is one of the most popularly used modalities for human recognition due to the fact that its collection is non-intrusive and requires less cooperation from the subjects. Moreover, face images taken at a long distance can still provide reasonable resolution, while most biometric modalities, such as iris and fingerprint, do not have this merit. In this chapter, we discuss automatic face recognition technologies for evidential evaluations of video traces. We first introduce the general concepts in both forensic and automatic face recognition , then analyse the difficulties in face recognition from videos . We summarise and categorise the approaches for handling different uncontrollable factors in difficult recognition conditions. Finally we discuss some challenges and trends in face recognition research in both forensics and biometrics . Given its merits tested in many deployed systems and great potential in other emerging applications, considerable research and development efforts are expected to be devoted in face recognition in the near future

SEQUENCE CONTROL OF COMPLEX COACERVATION

Complex coacervation is a liquid-liquid phase separation driven by the complexation of oppositely charged polyelectrolytes. The resulting coacervate phase has been used for many applications, such as underwater adhesives, drug delivery, food and personal care products. There also has been increasing interest in coacervate-like droplets occurring in biological systems. The majority of these “membraneless organelles” involve a combination of intrinsically-disordered proteins and RNA, and phase separate due to long-range charge effects and short-range hydrophobic effects. While evolution has optimized the self-assembly of these types of biological polymers, our ability to design such materials remains limited, in part because the relevant interactions that occur over a wide range of different length scales. The goal of this research is to establish molecular-level design rules as to how chemical sequence can modulate the formation and properties of complex coacervates. While studies to date have focused on the effect of parameters such as the charge stoichiometry, temperature, pH, salt concentration, stereochemistry, polymer architecture, and the density of charges present, the ability to pattern the sequence of charges and other chemistries has been rarely studied. However, polypeptides represent a model platform for the synthesis and study of polyelectrolytes with precisely controlled polymer architecture and sequence patterning at the molecular level, while retaining relevance to a variety of biological, medical, and industrial applications. Experimental measures such as turbidimetry and optical microscopy, coupled with isothermal titration calorimetry were used to study how variations in the patterning and overall fraction of charged groups along the polymer affect coacervate phase behavior. Increasing the number of charged residues increased the salt resistance and the size of the two-phase region. More interestingly, a comparison between polypeptides with the same overall charge fraction, but different periodic repeating patterns of charged monomers showed an increase in coacervate stability with increasing charge block size. Thermodynamic data, coupled with insights from simulation showed that the increase in stability was entropic in nature, resulting from differences in the one-dimensional confinement of counterions along the patterned polymer. We have also explored arbitrary sequences, hydrophobicity, and the identity of salt, as well as the self-coacervation of polyampholytes

Multicell Coordinated Beamforming with Rate Outage Constraint--Part I: Complexity Analysis

This paper studies the coordinated beamforming (CoBF) design in the multiple-input single-output interference channel, assuming only channel distribution information given a priori at the transmitters. The CoBF design is formulated as an optimization problem that maximizes a predefined system utility, e.g., the weighted sum rate or the weighted max-min-fairness (MMF) rate, subject to constraints on the individual probability of rate outage and power budget. While the problem is non-convex and appears difficult to handle due to the intricate outage probability constraints, so far it is still unknown if this outage constrained problem is computationally tractable. To answer this, we conduct computational complexity analysis of the outage constrained CoBF problem. Specifically, we show that the outage constrained CoBF problem with the weighted sum rate utility is intrinsically difficult, i.e., NP-hard. Moreover, the outage constrained CoBF problem with the weighted MMF rate utility is also NP-hard except the case when all the transmitters are equipped with single antenna. The presented analysis results confirm that efficient approximation methods are indispensable to the outage constrained CoBF problem.Comment: submitted to IEEE Transactions on Signal Processin