Environmental Policy Analysis, Peer Reviewed: Assessing the Environmental Movement's Attitudes Toward Risk Assessment

Risk Assessment.     

Effect of non-erupted third molars on roots of approximal teeth. A radiographic, clinical and histologic study

This study was undertaken to evaluate clinically and histologically root resorption in extracted human second molars in close proximity to non-erupted third molars. The control group consisted of extracted second molars that were proximal to fully erupted third molars. Eight out of the 11 teeth in the study group presented different degrees of radiographic root resorption, nine presented clinical resorption, and all 11 had histologic evidence of root resorption. In the control group, no signs of root resorption were seen radiographically or clinically. Histologically, limited sites of resorption were identified in all teeth, which were partially repaired by cellular cementum. Histologic observation of study specimens revealed root surface resorption in 10 out of the 11 teeth, one showing replacement resorption as well. Inflammatory resorption was observed in the three most advanced cases in the study group. Reparative cementum partially lining resorbed areas was evident in all teeth with surface resorption. Within the limits of this study, radiographic identification of distal root resorption of second molars in close proximity to non-erupted third molars appears reliable. The findings may support the hypothesis that the presence of a non-erupted third molar in close proximity to the distal root of the second results in root resorption.     

Electric-field-assisted proton-exchanged optical waveguides in lithium niobate

We describe the fabrication of a broad stripe optical wave-guide in z-cut lithium niobate by electric-field-assisted thermal proton exchange in a benzoic acid melt. Electric fields of 5 × 104V/m to 105V/m were laterally applied by means of in-contact gold thin-film electrodes 1 mm apart, producing an asymmetric depth across the width of the stripe. Similar vertical fields, applied across the thickness of the wafer, increased the stripe depth in the region of applied field. Refractive index profiles are given for both cases.     

Toward an explanation of cultural differences in in-group favoritism: The role of individual versus collective primacy.

Previous research conducted on a Western sample has shown that people are less apt to exhibit in-group favoritism when they perform well individually while their in-group performs poorly. The authors evaluated whether this finding would be moderated by the cultural dimension of individual–collective primacy, which refers to whether people give more weight to their personal interests rather than their in-group's interests when forced to choose between the two. The authors hypothesized that relative to their counterparts from the United States, participants from the People's Republic of China would have more of a collective-primacy orientation and therefore would exhibit more in-group favoritism when they performed well individually while their in-group performed poorly. The results supported the hypothesis. Implications for the literatures on in-group favoritism and cross-cultural differences are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Secure Distributed Key Generation for Discrete-Log Based Cryptosystems

A Distributed Key Generation (DKG) protocol is an essential component of threshold cryptosystems required to initialize the cryptosystem securely and generate its private and public keys. In the case of discrete-log-based (dlog-based) threshold signature schemes (ElGamal and its derivatives), the DKG protocol is further used in the distributed signature generation phase to generate one-time signature randomizers (r = g^k). In this paper we show that a widely used dlog-based DKG protocol suggested by Pedersen does not guarantee a uniformly random distribution of generated keys: we describe an efficient active attacker controlling a small number of parties which successfully biases the values of the generated keys away from uniform. We then present a new DKG protocol for the setting of dlog-based cryptosystems which we prove to satisfy the security requirements from DKG protocols and, in particular, it ensures a uniform distribution of the generated keys. The new protocol can be used as a secure replacement for the many applications of Pedersen's protocol. Motivated by the fact that the new DKG protocol incurs additional communication cost relative to Pedersen's original protocol, we investigate whether the latter can be used in specific applications which require relaxed security properties from the DKG protocol. We answer this question affirmatively by showing that Pedersen's protocol suffices for the secure implementation of certain threshold cryptosystems whose security can be reduced to the hardness of the discrete logarithm problem. In particular, we show Pedersen's DKG to be sufficient for the construction of a threshold Schnorr signature scheme. Finally, we observe an interesting trade-off between security (reductions), computation, and communication that arises when comparing Pedersen's DKG protocol with ours.     

Magnetic resonance imaging and quantitative analysis of particle deposition in porous media

Measurements of particle deposition and mobilization in water-saturated porous columns were performed using nuclear magnetic resonance imaging (MRI). The use of MRI enabled the acquisition of detailed, noninvasive measurements that quantify spatial and temporal evolution of particle transport patterns and porosity changes due to particle deposition. Measurements indicate that for the considered particle sizes and flow conditions significant particle deposition occurs at some distance into the column. Because identification of unique parametrizations for processes of particle straining, deposition, and detachment is complex and nonunique, a simple phenomenological model of particle deposition and porosity reduction is suggested. This model captures the essential features of the experimental measurements on spatial and temporal flow and deposition patterns.     

Face-Specific Data Augmentation for Unconstrained Face Recognition

International Journal of Computer Vision - We identify two issues as key to developing effective face recognition systems: maximizing the appearance variations of training images and minimizing...