Constant-Round Oblivious Transfer in the Bounded Storage Model

We present the first constant-round protocol for Oblivious Transfer in Maurer's bounded storage model. In this model, a long random string R is initially transmitted and each of the parties stores only a small portion of R. Even though the portions stored by the honest parties are small, security is guaranteed against any malicious party that remembers almost the entire string R (but not all of it). Previous constructions for oblivious transfer in the bounded storage model required polynomially many rounds of interaction. In contrast, our protocol uses only five messages. In addition we also improve other parameters, such as the number of bits transferred and the probability of immaturely aborting the protocol due to failure. Our techniques utilize explicit constructions from the theory of derandomization. In particular, we achieve the constant round complexity of our oblivious transfer protocol by constructing a novel four-message protocol for Interactive Hashing, in place of the well-known protocol by Naor et al. (known as the NOVY protocol) which involves many rounds of interaction. Our four-message interactive hashing protocol is constructed by use of t-wise independent permutations and may be of independent interest. For achieving constant-round complexity we also construct a new subset encoding scheme that is dense; namely, guarantees that almost every string in the image of the encoding function has a preimage. Other tools we employ include randomness extractors and averaging samplers.     

Guarding galleries and terrains

Let P be a polygon with n vertices. We say that two points of P see each other if the line segment connecting them lies inside (the closure of) P. In this paper we present efficient approximation algorithms for finding the smallest set G of points of P so that each point of P is seen by at least one point of G, and the points of G are constrained to be belong to the set of vertices of an arbitrarily dense grind. We also present similar algorithms for terrains and polygons with holes.     

“Soft” Considerations in Equipment Selection for Building Construction Projects

This paper raises the issue of “soft” considerations in the selection of equipment for building construction projects. The paper aims at increasing the awareness: (1) to the nature, variety, and richness of soft factors; (2) to their significant role and potential impact on the outcome of decision making; and (3) to the inherent difficulty of evaluating them and integrating them within a comprehensive selection process. Existing state-of-the-art equipment selection models were analyzed and found to be inadequate in terms of both considering soft factors and providing mechanisms for their systematic evaluation. Six cases of large-size, complex construction projects were investigated to obtain an extensive list of typical soft factors. This investigation revealed that the consideration of soft factors in current practices is essentially unstructured and is not integrated within the selection process in a systematic manner. A desirable selection process is outlined that generally responds to the needs identified in the study. The proposition of a specific method for the quantitative treatment of soft factors and their tradeoff with cost factors is the subject of another paper.     

Super-hydrophilic coatings based on silica nanoparticles

This work focuses on the use of silica nanoparticles for producing durable, transparent, and super-hydrophilic coatings on painted surfaces. Two methods were studied in detail: bottom-up approach using layer-by-layer (LbL) assemblies of hydroxylated SiO₂ nanoparticles, and top-down approach based on hybrid polymer/silica nanoparticles coatings. Of the two approaches studied, only the hybrid polymer/SiO₂ nanocomposite coatings containing 50–90%wt. SiO₂ exhibited durable super-hydrophilic surface properties less than 5° water contact and sliding angles. In the latter case, a unique micrometer-sized cracking pattern was developed. The LbL-assembled SiO₂ coatings showed a gradual degradation over time from the initial super-hydrophilic properties, indicated by the increase of the contact angles from less than 5^o to greater than 30^o after accelerated aging. To investigate the effect of environmental exposure on developing hydrophilicity, a variety of analytical methods were employed such as: atomic force microscopy, scanning electron microscopy, optical microscopy, and Fourier transform infrared. Experimental results and associated modeling indicated that the combination of micro- and nano-surface roughness and the surface chemical composition were the dominant factors affecting the durability of the hydrophilic attributes of the coatings containing silica nanoparticles.     

“Weighting for more”: Enhancing characteristic-function based ICA with asymptotically optimal weighting

The CHaracteristic-function-Enabled Source Separation (CHESS) method for independent component analysis (ICA) is based on approximate joint diagonalization (AJD) of Hessians of the observations' empirical log-characteristic-function, taken at selected off-origin “processing points”. As previously observed in other contexts, the AJD performance can be significantly improved by optimal weighting, using the inverse of the covariance matrix of all of the off-diagonal terms of the target-matrices. Fortunately, this apparently cumbersome weighting scheme takes a convenient form under the assumption that the mixture is already “nearly separated”, e.g., following some initial separation. We derive covariance expressions for the Sample-Hessian matrices, and show that under the near-separation assumption, the weight matrix takes a nearly block-diagonal form, conveniently exploited by the recently proposed WEighted Diagonalization using Gauss itErations (WEDGE) algorithm for weighted AJD. Using our expressions, the weight matrix can be estimated directly from the data—leading to our WeIghTed CHESS (WITCHESS) algorithm. Simulation results demonstrate how WITCHESS can lead to significant performance improvement, not only over unweighted CHESS, but also over other ICA methods.     

Regional development and interregional collaboration in the growth of nanotechnology research in China

China is becoming a leading nation in terms of its share of the world??s publications in the emerging nanotechnology domain. This paper demonstrates that the international rise of China??s position in nanotechnology has been underwritten by the emergence of a series of regional hubs of nanotechnology R&D activity within the country. We develop a unique database of Chinese nanotechnology articles covering the period 1990 to mid-2006 to identify the regional distribution of nanotechnology research in China. To build this database, a new approach was developed to clean and standardize the geographical allocation of Chinese publication records. We then analyze the data to understand the regional development of nanotechnology research in China over our study period and to map interregional and international research collaboration linkages. We find that the geographical distribution of China??s domestic nanotechnology research is characterized by regional imbalance, with most of the leading regions located in eastern China, including not only Beijing and Shanghai but also a series of other new regional hubs. There is much less development of nanotechnology research in central and western China. Beijing, Shanghai, and Hong Kong are among the leading Chinese regions for international nanotechnology research collaboration. Other Chinese nanotechnology regions are less focused on international collaboration, although they have developed domestic interregional collaborations. Although new regional research hubs have emerged in the nanotechnology domain, the paper notes that their concentration in eastern China reinforces existing imbalances in science and technology capabilities in China, and in turn this may further reinforce the dominant position of eastern China in the commercialization of new technologies such as nanotechnology.     

Gene Variant of Barrier to Autointegration Factor 2 (Banf2w) Is Concordant with Female Determination in Cichlids

Oreochromis fishes exhibit variability of sex-determination (SD) genes whose characterization contributes to understanding of the sex differentiation network, and to effective tilapia farming, which requires all-male culture. However, O. niloticus (On) amh is the only master-key regulator (MKR) of SD that has been mapped (XY/XX SD-system on LG23). In O. aureus (Oa), LG3 controls a WZ/ZZ SD-system that has recently been delimited to 9.2 Mbp, with an embedded interval rich with female-specific variation, harboring two paics genes and banf2. Developing genetic markers within this interval and using a hybrid Oa stock that demonstrates no recombination repression in LG3, we mapped the critical SD region to 235 Kbp on the orthologous On physical map (p < 1.5 × 10⁻²⁶). DNA-seq assembly and peak-proportion analysis of variation based on Sanger chromatograms allowed the characterization of copy-number variation (CNV) of banf2. Oa males had three exons capable of encoding 90-amino-acid polypeptides, yet in Oa females, we found an extra copy with an 89-amino-acid polypeptide and three non-conservative amino acid substitutions, designated as banf2w. CNV analysis suggested the existence of two to five copies of banf2 in diploidic Cichlidae. Disrupting the Hardy–Weinberg equilibrium (p < 4.2 × 10⁻³), banf2w was concordant with female determination in Oa and in three cichlids with LG3 WZ/ZZ SD-systems (O. tanganicae, O. hornorum and Pelmatolapia mariae). Furthermore, exclusive RNA-seq expression in Oa females strengthened the candidacy of banf2w as the long-sought LG3 SD MKR. As banf genes mediate nuclear assembly, chromatin organization, gene expression and gonad development, banf2w may play a fundamental role inducing female nucleus formation that is essential for WZ/ZZ SD.     

Can art breach boundaries? Segregation and hierarchy at a fringe theatre festival in the Israeli mixed city of Acre

Abstract

This study explores the relationship between art and urban boundaries using the case study of a fringe theatre festival in the Israeli mixed-city of Acre. While mixed cities today are understood as agglomerations of enclaves, maintained and reinforced by boundaries, urban designers and artists have used art as a culture-led regeneration strategy through which these boundaries may be breached. This study undermines the shared assumption of both fields: that art has the power to breach boundaries, by juxtaposing a city’s artistic activity with its segregation patterns and boundaries. Using super-positioning, the findings of two research methods have been integrated: urban research and ethnographic field work. The article shows that although the artistic activity in question is rooted in an avant-garde radical desire to subvert socioeconomic structures, it actually produces new versions and interpretations of the same segregations and boundaries in both space and society.     

Time-domain analysis of bandgap characteristics of two-dimensional periodic structures by use of a source-model technique

We introduce a time-domain source-model technique for analysis of two-dimensional, transverse-magnetic, plane-wave scattering by a photonic crystal slab composed of a finite number of identical layers, each comprising a linear periodic array of dielectric cylinders. The proposed technique takes advantage of the periodicity of the slab by solving the problem within a unit cell of the periodic structure. A spectral analysis of the temporal behavior of the fields scattered by the slab shows a clear agreement between frequency bands where the spectral density of the transmitted energy is low and the bandgaps of the corresponding two-dimensionally infinite periodic structure. The effect of the bandwidth of the incident pulse and its center frequency on the manner it is transmitted through and reflected by the slab is studied via numerical examples.     

Study of single silicon quantum dots' band gap and single-electron charging energies by room temperature scanning tunneling microscopy

Scanning tunneling spectroscopy in the shell-filling regime was carried out at room temperature to investigate the size dependence of the band gap and single-electron charging energy of single Si quantum dots (QDs). The results are compared with model calculation. A 12-fold multiple staircase structure was observed for a QD of about 4.3 nm diameter, reflecting the degeneracy of the first energy level, as expected from theoretical calculations. The systematic broadening of the tunneling spectroscopy peaks with decreasing dot diameter is attributed to the reduced barrier height for smaller dot sizes and to the splitting of the first energy level.