Lorenz System Parameter Determination and Application to Break the Security of Two-channel Chaotic Cryptosystems

This paper describes how to determine the parameter values of the chaotic Lorenz system used in a two-channel cryptosystem. The geometrical properties of the Lorenz system are used firstly to reduce the parameter search space, then the parameters are exactly determined, directly from the ciphertext, through the minimization of the average jamming noise power created by the encryption process.Comment: 5 pages, 5 figures Preprint submitted to IEEE T. Cas II, revision of authors name spellin

On hypercyclicity and linear chaos in a nonclassical sequence space and beyond

We analyze the hypercyclicity, chaoticity, and spectral structure of (bounded and unbounded) weighted backward shifts in a nonclassical sequence space, which the space $l_1$ of summable sequences is both isometrically isomorphic to and continuously and densely embedded into. Based on the weighted backward shifts, we further construct new bounded and unbounded linear hypercyclic and chaotic operators both in the nonclassical sequence space and the classical space $l_1$, including those that are hypercyclic but not chaotic.Comment: Refined estimates in Proposition 3.2 and Lemma 4.1, corresponding changes wherever pertinent, minor edits and readability improvements. There is a text overlap with arXiv:2106.09682, arXiv:2106.14872, and arXiv:2203.02032 in the Preliminaries section containing introductory information, definitions, and general remark

propnet: A Knowledge Graph for Materials Science

Discovering the ideal material for a new application involves determining its numerous properties, such as electronic, mechanical, or thermodynamic, to match those of its desired application. The rise of high-throughput computation has meant that large databases of material properties are now accessible to scientists. However, these databases contain far more information than might appear at first glance, since many relationships exist in the materials science literature to derive, or at least approximate, additional properties. propnet is a new computational framework designed to help scientists to automatically calculate additional information from their datasets. It does this by constructing a network graph of relationships between different materials properties and traversing this graph. Initially, propnet contains a catalog of over 100 property relationships but the hope is for this to expand significantly in the future, and contributions from the community are welcomed

Bioinspired snapping-claw apparatus to study hydrodynamic cavitation effects on the corrosion of metallic samples

A creative low-cost and compact mechanical device that mimics the rapid closure of the pistol shrimp claw was used to conduct electrochemical experiments, in order to study the effects of hydrodynamic cavitation on the corrosion of aluminum and steel samples. Current-time curves show significant changes associated with local variations in dissolved O2 concentration, cavitation-induced erosion and changes in the nature of the surface corrosion products

HLA e malária em quatro diferentes grupos étnicos da Colômbia

HLA antigens and their relationship with malaria infection were studied in four different ethnic groups in Colombia (South America): two groups of indians (Kunas and Katios), one of negroes and a group of mixed ancestry. A total of 965 persons were studied, 415 with malaria and 550 as controls. HLA-A,B, and C antigen frequencies in the four groups are reported. The association of each HLA antigen with malaria infection due to P. vivax and to P. falciparum was evaluated. Negroes, Kunas and Katios indians variously lack from 6 to 9 of the HLA antigens found in the mixed group. In the designated ethnic groups, antigens B5, B13, B15, Cw2 and Cw4 showed borderline association with malaria infection. However, in the mixed ethnic group, statistically significant associations were found with malaria infection and the presence of A9, Aw19, B17, B35, and Z98 (a B21-B45: crossreacting determinant) with few differences when P. vivax infection and P. falciparum infection were considered individually. This finding may represent a lack of general resistance to malaria in the group that harbors antigens of Caucasian origin. These individuals have been in direct and permanent contact with malaria only in the past 65 years. In contrast, indians, both Kunas and Katios, and Negroes have lived for centuries in malaria endemic areas, and it is possible that a natural selection system has developed through which only those individuals able to initiate an acute immune response to malaria have survived.Foram estudados os antigenos HLA e a relação destes com a infecção malárica em 4 diferentes grupos étnicos da Colômbia (América do Sul); dois grupos de índios (Kunas e Katios), um grupo de negros e um grupo que apresentava ancestrais mistos. Foram estudadas 965 pessoas, das quais 415 com malária e 550 como controles. A freqüência dos antígenos HLA-A, B e C foram determinados nos quatro grupos estudados. A associação de cada antígeno HLA com a infecção por P. vivax e P. falciparum foi avaliada. Os antígenos HLA 6-9 encontrados no grupo de ancestrais mistos, de um modo geral não foram observados nos grupos de negros e índios (Kunas e Katios). Nos grupos étnicos mencionados, os antigenos B5, B13, B15, Cw2 e Cw4 apresentaram uma associação limítrofe com a infecção por malária. Entretanto, no grupo étnico de ancestrais mistos foi observada uma associação estatisticamente significativa com a infecção malárica, sendo que a presença de A9, Aw19, B17, B35 e Z98 (B21-B45: determinantes de reação cruzada) mostrou poucas diferenças quando as infecções por P. vivax e P. falciparum foram consideradas individualmente. Esse achado pode representar, de um modo geral, uma falta de resistência a malária no grupo portador de antigenos de origem caucasiana, os quais tem tido um contacto direto e permanente com a malária somente nos últimos 65 anos. Em contraste, os índios (Kunas e Katios) e os negros tem vivido durante séculos em áreas endêmicas para malária, é possível que um sistema de seleção natural tenha sido desenvolvido permitindo que somente aqueles indivíduos capazes de iniciar uma resposta imune à malária sobrevivam

Defining and identifying communities in networks

The investigation of community structures in networks is an important issue in many domains and disciplines. This problem is relevant for social tasks (objective analysis of relationships on the web), biological inquiries (functional studies in metabolic, cellular or protein networks) or technological problems (optimization of large infrastructures). Several types of algorithm exist for revealing the community structure in networks, but a general and quantitative definition of community is still lacking, leading to an intrinsic difficulty in the interpretation of the results of the algorithms without any additional non-topological information. In this paper we face this problem by introducing two quantitative definitions of community and by showing how they are implemented in practice in the existing algorithms. In this way the algorithms for the identification of the community structure become fully self-contained. Furthermore, we propose a new local algorithm to detect communities which outperforms the existing algorithms with respect to the computational cost, keeping the same level of reliability. The new algorithm is tested on artificial and real-world graphs. In particular we show the application of the new algorithm to a network of scientific collaborations, which, for its size, can not be attacked with the usual methods. This new class of local algorithms could open the way to applications to large-scale technological and biological applications.Comment: Revtex, final form, 14 pages, 6 figure