Bistability in sine-Gordon: the ideal switch

The sine-Gordon equation, used as the representative nonlinear wave equation, presents a bistable behavior resulting from nonlinearity and generating hysteresis properties. We show that the process can be understood in a comprehensive analytical formulation and that it is a generic property of nonlinear systems possessing a natural band gap. The approach allows to discover that sine-Gordon can work as an it ideal switch by reaching a transmissive regime with vanishing driving amplitude.Comment: Phys. Rev. E, (to be published, May 2005

Social desirability in virtual communities

As virtual worlds and social media in general become important settings for marketing actions, we need to know what is the weight of social norms within such contexts. To what degree can a researcher expect that the answers obtained within a virtual world \u2013 ultimately a social network \u2013 reflect real opinions and are not inflated by social desirability? Does the social context of an online community induce higher social desirability? This paper investigates whether social desirability is stronger within virtual world online communities than in the real world, observing same structural relationship among measured constructs but higher social desirability tendency in the virtual world compared to the real life. Since social networks and online communities will be more often used as research and communication platforms, increased attention needs to be paid to the social desirability tendency of the community members

Web navigation for individuals with dyslexia: An exploratory study

In this paper, we present an exploratory study of the web navigation experiences of dyslexic users. Findings indicate that dyslexics exhibit distinctive web navigation behaviour and preferences. We believe that the outcomes of this study add to our understanding of the particular needs of this web user population and have implications for the design of effective navigation structures

A systematic review of problematic video-game use in people with Autism Spectrum Disorders

Background: In recent years, an increasing number of studies documented potential links between gaming disorders (GD; including “digital-gaming” or “video-gaming”) and Autism Spectrum Disorders (ASD). Therefore, the aim of this systematic review was to summarize current research about problematic video game (PVG) use in people with ASD and identify specific factors associated with problematic video gaming behavior. Method: We searched for articles indexed in PubMed, Scopus, Web of Science, and EBSCOhost electronic databases; using a combination of expressions including “autism spectrum disorder” OR “autism” OR “ASD” AND “video games” OR “gaming disorder” OR “Internet Gaming Disorder” OR “game addiction”. Results: Twelve articles were included in this systematic review. The majority of them indicate that children, adolescents and adults with ASD may be at greater risk of PVG use than youths without ASD. Findings also suggested that several internal (sex, attention and oppositional behavior problems) and external factors (social aspects, access and time spent playing video, parental rules, and game genre) were significant predictors of problematic video game use in people with ASD. In addition, this review highlights the paucity of the literature on the consequences and individual effects of excessive video gaming in people with ASD. Conclusions: We discuss unanswered questions and future directions and provide recommendations for improving clinicians and parents’ engagement in the prevention and management of problematic video game use in people with ASD

Odd and Even Lidstone-type polynomial sequences. Part 1: basic topics

Abstract Two new general classes of polynomial sequences called respectively odd and even Lidstone-type polynomials are considered. These classes include classic Lidstone polynomials of first and second kind. Some characterizations of the two classes are given, including matrix form, conjugate sequences, generating function, recurrence relations, and determinant forms. Some examples are presented and some applications are sketched

Numerical Solution of High Order Bernoulli Boundary Value Problems

For the numerical solution of high order boundary value problems with special boundary conditions a general procedure to determine collocation methods is derived and studied. Computation of the integrals which appear in the coefficients is generated by a recurrence formula and no integrals are involved in the calculation. Several numerical examples are presented to demonstrate the practical usefulness of the proposed method

Coupling of Josephson flux-flow oscillators to an external RC load

We investigate by numerical simulations the behavior of the power dissipated in a resistive load capacitively coupled to a Josephson flux flow oscillator and compare the results to those obtained for a d.c. coupled purely resistive load. Assuming realistic values for the parameters R and C, both in the high- and in the low-Tc case the power is large enough to allow the operation of such a device in applications.Comment: uuencoded, gzipped tar archive containing 11 pages of REVTeX text + 4 PostScript figures. To appear in Supercond. Sci. Techno

New Antenna Deployment, Pointing and Supporting Mechanism

On ITALSAT Flight 2, the Italian telecommunications satellite, the two L-Ka antennas (Tx and Rx) use two large deployable reflectors (2000-mm diameter), whose deployment and fine pointing functions are accomplished by means of an innovative mechanism concept. The Antenna Deployment & Pointing Mechanism and Supporting Structure (ADPMSS) is based on a new configuration solution, where the reflector and mechanisms are conceived as an integrated, self-contained assembly. This approach is different from the traditional configuration solution. Typically, a rigid arm is used to deploy and then support the reflector in the operating position, and an Antenna Pointing Mechanism (APM) is normally interposed between the reflector and the arm for steering operation. The main characteristics of the ADPMSS are: combined implementation of deployment, pointing, and reflector support; optimum integration of active components and interface matching with the satellite platform; structural link distribution to avoid hyperstatic connections; very light weight and; high performance in terms of deployment torque margin and pointing range/accuracy. After having successfully been subjected to all component-level qualification and system-level acceptance tests, two flight ADPMSS mechanisms (one for each antenna) are now integrated on ITALSAT F2 and are ready for launch. This paper deals with the design concept, development, and testing program performed to qualify the ADPMSS mechanism

Economical Runge-Kutta methods

For the numerical solution of the Cauchy problem, this paper presents an elegant idea of saving one function call for a special class of Runge-Kutt methods by using information from the previous step. The stability analysis and practical error estimation by embedded formulas of order (3,2), (5,4) are studied. Numerical examples are, also, considered, which proved that these methods are in competition with the best methods now exist