Superconductivity Phase Diagram of Na(x)CoO(2).1.3H(2)O

Although the microscopic origin of the superconductivity in high Tc copper oxides remains the subject of active inquiry, several of their electronic characteristics are well established as universal to all the known materials, forming the experimental foundation that all theories must address. The most fundamental of those characteristics is the dependence of the superconducting transition temperature on the degree of electronic band filling. Since the discovery of cuprate superconductivity in 1986 (1), the search for other families of superconductors that might help shed light on the superconducting mechanism of the cuprates has been of great interest. The recent report of superconductivity near 4K in the triangular lattice, layered sodium cobalt oxyhydrate, Na0.35CoO2.1.3H2O, is the best indication that superconductors related to the cuprates may be found (2). Here we show that the superconducting transition temperature of this compound displays the same kind of band-filling behavior that is observed in the cuprates. Specifically, that the optimal superconducting Tc occurs in a narrow range of band filling, and decreases for both underdoped and overdoped materials, in dramatic analogy to the phase diagram of the cuprate superconductors. Our results suggest that characterization of the detailed electronic and magnetic behavior of these new materials may help establish which of the many special characteristics of the cuprates is fundamental to their high Tc superconductivity.Comment: revised, publication information adde

A genetic algorithm for the minimum weight triangulation

In this paper, a new method for the minimum weight triangulation of points on a plane, called genetic minimum weight triangulation (GMWT), is presented based on the rationale of genetic algorithms. Polygon crossover and its algorithm for triangulations are proposed. New adaptive genetic operators, or adaptive crossover and mutation operators, are introduced. It is shown that the new method for the minimum weight triangulation can obtain more optimal results of triangulations than the greedy algorithm.published_or_final_versio

Hormad1 mutation disrupts synaptonemal complex formation, recombination, and chromosome segregation in mammalian meiosis

Meiosis is unique to germ cells and essential for reproduction. During the first meiotic division, homologous chromosomes pair, recombine, and form chiasmata. The homologues connect via axial elements and numerous transverse filaments to form the synaptonemal complex. The synaptonemal complex is a critical component for chromosome pairing, segregation, and recombination. We previously identified a novel germ cell-specific HORMA domain encoding gene, Hormad1, a member of the synaptonemal complex and a mammalian counterpart to the yeast meiotic HORMA domain protein Hop1. Hormad1 is essential for mammalian gametogenesis as knockout male and female mice are infertile. Hormad1 deficient (Hormad1-/-) testes exhibit meiotic arrest in the early pachytene stage, and synaptonemal complexes cannot be visualized by electron microscopy. Hormad1 deficiency does not affect localization of other synaptonemal complex proteins, SYCP2 and SYCP3, but disrupts homologous chromosome pairing. Double stranded break formation and early recombination events are disrupted in Hormad1-/- testes and ovaries as shown by the drastic decrease in the γH2AX, DMC1, RAD51, and RPA foci. HORMAD1 co-localizes with cH2AX to the sex body during pachytene. BRCA1, ATR, and γH2AX co-localize to the sex body and participate in meiotic sex chromosome inactivation and transcriptional silencing. Hormad1 deficiency abolishes γH2AX, ATR, and BRCA1 localization to the sex chromosomes and causes transcriptional de-repression on the X chromosome. Unlike testes, Hormad1-/- ovaries have seemingly normal ovarian folliculogenesis after puberty. However, embryos generated from Hormad1-/- oocytes are hyper- and hypodiploid at the 2 cell and 8 cell stage, and they arrest at the blastocyst stage. HORMAD1 is therefore a critical component of the synaptonemal complex that affects synapsis, recombination, and meiotic sex chromosome inactivation and transcriptional silencing. © 2010 Shin et al

Graph Layout Performance Comparisons of Force-Directed Algorithms

© 2018 Totem Publisher, Inc. All rights reserved. Due to force-directed algorithms’ capabilities of producing aesthetically pleasing graph layouts, which follow metrics for graph drawing aesthetics, these layouts have become the most common methods in the practical data visualization area. However, evaluating the performance of relevant algorithms remains a challenge, since graph layout quality is largely relying on aspects such as human intuition, personal judgment and methods’ pre-setting parameters. In addition, most aesthetics criteria of graph drawing conflict with each other. This study evaluated the performance measurements of four force-directed algorithms in terms of seven commonly applied aesthetic criteria based on practical raw data collected, and demonstrated the experimental framework. The early outcomes compared twenty final graph layouts and gave empirical evidences; the study may assist with future detailed force-directed algorithms selection based on users’ specific requirements

Performance comparisons between force-directed algorithms on structured data analysis

© 2017 IEEE. Evaluation on the performance of relevant force-directed algorithms is still a challenge, since layout quality is largely relying on personal judgement and/or methods' input parameters, and most aesthetics criteria conflict with each other. This study conducts the performance measurements of four algorithms in terms of seven commonly applied aesthetic criteria and demonstrates the experimental framework

Visual clustering of spam emails for DDoS analysis

Networking attacks embedded in spam emails are increasingly becoming numerous and sophisticated in nature. Hence this has given a growing need for spam email analysis to identify these attacks. The use of these intrusion detection systems has given rise to other two issues, 1) the presentation and understanding of large amounts of spam emails, 2) the user-assisted input and quantified adjustment during the analysis process. In this paper we introduce a new analytical model that uses two coefficient vectors: 'density' and 'weight'for the analysis of spam email viruses and attacks. We then use a visual clustering method to classify and display the spam emails. The visualization allows users to interactively select and scale down the scope of views for better understanding of different types of the spam email attacks. The experiment shows that this new model with the clustering visualization can be effectively used for network security analysis. © 2011 IEEE

A Lightweight Authentication Scheme for Transport System Farecards

Proximity Integrated Circuit Cards (PICC) are widely used for public transport fare collection. The stored contents in the card can only be accessed or modified after the card is able to authenticate the Proximity Coupling Device (PCD) or reader using a shared secret key. We propose a new authentication scheme that is not based on shared secret keys. Instead, authentication is based on the card and reader being able to compute an identical pairwise key using their own private keying material obtained from the same source. The computation is done off-line and does not require the participation of a third party. It uses simple modular arithmetic operations over a small binary extension field, achieving fast computation speed using the limited resources in cards. In addition, should the keys be stolen from the cards or readers, the security of the other parts of the system cannot be compromised

Applying data visualization techniques for stock relationship analysis

© 2018, University of Nis. All rights reserved. Decision making in stock investment is often made based on current events in the market and the analysis of historical data on specific stocks. Besides, similar rates of price changing over a long-term period on different stocks may indicate potential connections between those listed corporations. The proposed methodology applies the force-directed algorithm and time-series chart to offer stakeholders capability to gain deeper insights initiative on potential relationships between stocks comes with less human interventions. Hence to assist in future decision making on stock investment via graph layouts