Software for Wearable Devices: Challenges and Opportunities

Wearable devices are a new form of mobile computer system that provides exclusive and user-personalized services. Wearable devices bring new issues and challenges to computer science and technology. This paper summarizes the development process and the categories of wearable devices. In addition, we present new key issues arising in aspects of wearable devices, including operating systems, database management system, network communication protocol, application development platform, privacy and security, energy consumption, human-computer interaction, software engineering, and big data.Comment: 6 pages, 1 figure, for Compsac 201

The hierarchy of higher order solutions of the derivative nonlinear Schr\"odinger equation

In this paper, we provide a simple method to generate higher order position solutions and rogue wave solutions for the derivative nonlinear Schr\"odinger equation. The formulae of these higher order solutions are given in terms of determinants. The dynamics and structures of solutions generated by this method are studied

The higher order Rogue Wave solutions of the Gerdjikov-Ivanov equation

We construct higher order rogue wave solutions for the Gerdjikov-Ivanov equation explicitly in term of determinant expression. Dynamics of both soliton and non-soliton solutions is discussed. A family of solutions with distinct structures are presented, which are new to the Gerdjikov-Ivanov equation

Decoding and Reprogramming Fungal Iterative Nonribosomal Peptide Synthetases

Nonribosomal peptide synthetases (NRPSs) assemble a large group of structurally and functionally diverse natural products. While the iterative catalytic mechanism of bacterial NRPSs is known, it remains unclear how fungal NRPSs create products of desired length. Here we show that fungal iterative NRPSs adopt an alternate incorporation strategy. Beauvericin and bassianolide synthetases have the same C1-A1-T1-C2-A2-MT-T2a-T2b-C3 domain organization. During catalysis, C3 and C2 take turns to incorporate the two biosynthetic precursors into the growing depsipeptide chain that swings between T1 and T2a/T2b with C3 cyclizing the chain when it reaches the full length. We reconstruct the total biosynthesis of beauvericin in vitro by reacting C2 and C3 with two SNAC-linked precursors and present a domain swapping approach to reprogramming these enzymes for peptides with altered lengths. These findings highlight the difference between bacterial and fungal NRPS mechanisms and provide a framework for the enzymatic synthesis of non-natural nonribosomal peptides

Get Tired of Socializing as Social Animal? An Empirical Explanation on Discontinuous Usage Behavior in Social Network Services

This research aims to explain users’ discontinuous usage behavior in social network context. With system features increasing, information flooding and personal network expanding of SNSs, users begin to emerge social network fatigue, and ultimately induce discontinuous usage intention. To explain this phenomenon, we develop a research model based on a cognition-affection-conation framework. This study examines the role of perceived overload (in terms of system feature overload, information overload and social overload) in influencing users’ negative affections of SNSs including social network fatigue and dissatisfaction, and the effects of such emotions on users’ discontinuous intention, which are validated through an empirical survey. The findings of this study contribute to a better understanding of the relationship among perceived overload, social network fatigue and users’ discontinuous usage behavior, and give some implications to SNSs providers to improve this situation

Understanding Why Fiscal Stimulus Can Fail through the Lens of the Survey of Professional Forecasters

This paper shows that fiscal policy in the U.S. has become ineffective due to lack of coordination between monetary and fiscal policy. We present a New Keynesian model that generates strong output effects of government spending shocks only when monetary policy coordinates well with fiscal policy. Employing the post-war U.S. data, we report strong stimulus effects of fiscal policy during the pre-Volcker era, which rapidly dissipate when we shift the sample period to the post-Volcker era. Finding a negligible role of the real interest rate in the propagation of government spending shocks, we propose an alternative explanation using a consumer sentiment channel. Employing the Survey of Professional Forecasters data, we show that forecasters tend to systematically over-estimate real GDP growth in response to positive innovations in government spending when policies coordinate well with each other. On the other hand, they are likely to formulate pessimistic forecasts when the monetary authority maintains a hawkish stance that conflicts with the fiscal stimulus. The fiscal stimulus, under such circumstances, may generate consumer pessimism, which decreases private spending and ultimately weakens the output effects of fiscal policy. We also provide statistical evidence that confirms an important role of the sentiment channel under different regimes of policy coordination

A redox conjugated polymer-based all-solid-state reference electrode

This work reports the design, synthesis, and characterization of a novel redox-active conjugated polyaniline containing quinone moiety as a solid state reference electrode. The union of electro-active quinone with π-conjugated polyaniline was created by the first chemical synthesis of para-dimethoxybenzene-functionalized aniline as a monomer using a palladium-mediated coupling. The successful polymerization of the as-prepared monomer was accomplished without acid additives. Its post-polymerization modification with strong Lewis acid boron tribromide furnished unique poly (aniline quinone/hydroquinone) with desired properties for all-solid-state reference electrode (RE) applications. The electrochemical responses from the conjugated polyaniline backbone in this unique polymer have been “suppressed” by the quinone pendant. The resulting poly (aniline quinone) showed a quasi-reversible redox process from the redox behavior of the pendant quinone. The stable electrode potential of this poly (aniline quinone/hydroquinone) suggested that it was a single phase in which the amounts of totally reduced and totally oxidized species could be maintained at a constant in various solvents and electrolytes. Its electrochemical stability was excellent with 95% peak current retention after continuous cyclic voltammetric testing. The aniline and quinone moieties in poly (aniline quinone/hydroquinone) render it to have both hydrophilic and hydrophobic compatibility. It showed excellent behavior as a reference electrode in aqueous and non-aqueous media and can be used in both non-zero current and zero-current conditions, providing a stable potential with a maximum potential drift of ~4.7 mV over ten consecutive days

Insight into the Desolvation of Quaternary Ammonium Cation with Acetonitrile as a Solvent in Hydroxyl-Flat Pores: A First-Principles Calculation

Supercapacitors have a wide range of applications in high-technology fields. The desolvation of organic electrolyte cations affects the capacity size and conductivity of supercapacitors. However, few relevant studies have been published in this field. In this experiment, the adsorption behavior of porous carbon was simulated with first-principles calculations using a graphene bilayer with a layer spacing of 4-10 Å as a hydroxyl-flat pore model. The reaction energies of quaternary ammonium cations, acetonitrile, and quaternary ammonium cationic complexes were calculated in a graphene bilayer with different interlayer spacings, and the desolvation behavior of TEA+ and SBP+ ions was described. The critical size for the complete desolvation of [TEA(AN)]+ was 4.7 Å, and the partial desolvation size ranged from 4.7 to 4.8 Å. The critical size for the complete desolvation of [SBP(AN)]+ was 5.2 Å, and the partial desolvation size ranged from 5.2 to 5.5 Å. As the ionic radius of the quaternary ammonium cation decreased, the desolvation size showed a positive trend. A density of states (DOS) analysis of the desolvated quaternary ammonium cations embedded in the hydroxyl-flat pore structure showed that the conductivity of the hydroxyl-flat pore was enhanced after gaining electrons. The results of this paper provide some help in selecting organic electrolytes to improve the capacity and conductivity of supercapacitors