Decisive Markov Chains

We consider qualitative and quantitative verification problems for infinite-state Markov chains. We call a Markov chain decisive w.r.t. a given set of target states F if it almost certainly eventually reaches either F or a state from which F can no longer be reached. While all finite Markov chains are trivially decisive (for every set F), this also holds for many classes of infinite Markov chains. Infinite Markov chains which contain a finite attractor are decisive w.r.t. every set F. In particular, this holds for probabilistic lossy channel systems (PLCS). Furthermore, all globally coarse Markov chains are decisive. This class includes probabilistic vector addition systems (PVASS) and probabilistic noisy Turing machines (PNTM). We consider both safety and liveness problems for decisive Markov chains, i.e., the probabilities that a given set of states F is eventually reached or reached infinitely often, respectively. 1. We express the qualitative problems in abstract terms for decisive Markov chains, and show an almost complete picture of its decidability for PLCS, PVASS and PNTM. 2. We also show that the path enumeration algorithm of Iyer and Narasimha terminates for decisive Markov chains and can thus be used to solve the approximate quantitative safety problem. A modified variant of this algorithm solves the approximate quantitative liveness problem. 3. Finally, we show that the exact probability of (repeatedly) reaching F cannot be effectively expressed (in a uniform way) in Tarski-algebra for either PLCS, PVASS or (P)NTM.Comment: 32 pages, 0 figure

Kinetics of phase separation and thin film formation of multiresponsive polymers

In this thesis, we were interested in studying the deposition of layers formed by stimuli-responsive colloidal soft particles using a surface acoustic wave method: “Quartz Crystal Microbalance with Dissipation Monitoring, (QCM-D)”. This thesis is divided into four chapters: chapter 1 gives an introduction to the structural properties of polymers and glasses in solution and at interfaces, chapter 2 presents the principles of the QCM-D monitoring technique in terms of the physical meaning of its main output (the normalized resonance frequency shift Δfn/n and dissipation factor shift ΔDn) and important parameters to consider while carrying out our study (temperature and light control). Chapter 3 is dedicated to deposition control of soft layers formed out of dual stimuli-responsive colloidal particles of Poly (triethylene glycol acrylate-co-Spiropyran acrylate) (P(TEGA-co-SPA)). In this chapter, we examine the concomitant effect of light and temperature in order to manipulate the formation process of soft glassy films and their subsequent structural response. Chapter 4 presents the kinetics of the deposition of Poly(N-isopropylacrylamide) P(NIPAAm) soft glassy layers. In this chapter, we focus on the effect of temperature and concentration on the isothermal glass formation below and above the phase separation temperature using a twostep kinetic model. We also provide a subsequent analysis of the viscoelastic properties of the deposited layers in non-isothermal mode and compare it with their properties in isothermal mode. The present study extends the state of the art in two main disciplines. The first discipline is fundamental research in glass sciences and the second discipline is the research of multi stimuli-responsive polymers, where our findings would be of great interest for applications that need remote-controlled switching, especially in microfluidic chips and biomedical applications

Monopolizing force?: police legitimacy and public attitudes towards the acceptability of violence

Why do people believe that violence is acceptable? In this paper we study people’s normative beliefs about the acceptability of violence to achieve social control (as a substitute for the police, for self-protection and the resolution of disputes) and social change (through violent protests and acts to achieve political goals). Addressing attitudes towards violence among young men from various ethnic minority communities in London, we find that procedural justice is strongly correlated with police legitimacy, and that positive judgments about police legitimacy are associated with more negative views about the use of violence. We conclude with the idea that police legitimacy has an additional, hitherto unrecognized, empirical property – by constituting the belief that the police monopolise rightful force in society, legitimacy has a ‘crowding out’ effect on positive views of private violence

Gender gaps in English as a second foreign language attainment: some Oujda High Schools case study

Several studies and research have been conducted on the issue of gender gap attainment, most of which have concluded that female students are relatively higher achievers compared to males. This gap is attributed to different explanations depending on the angles from which it is viewed, amongst which is the average use of language learning strategies (LLS). Therefore, the current study attempts to find out and analyze the reasons why female and male students perform differently in the English classes in Oujda high schools. It also aims to discover who exploits LLS more in learning English as a foreign language. To effectively reach this goal, the researchers use a self-developed observation checklist to identify who outperforms the other and a structured interview to discern who uses LLS more effectively. As a result, two points emerged in this research paper. The current study attempts to find out about female-male differences in English attainment. Besides, it seeks explanations for male and female performance in the English classes in Oujda high schools. It also aims to discover who exploits LLS more in learning English as a foreign language. To fill this gap, a number of 960 students were observed, and 32 students were interviewed. The study is approached using the mixed-method of quantitative and qualitative design, where a descriptive approach is used. Data is gathered through both instruments observation and interviews in five high schools. To effectively reach this goal, the researchers use a self-developed observation checklist to identify who outperforms the other and a structured interview to discern who uses LLS more effectively. As a result, two points emerged in this research paper. First, this research paper proves that females outperform males in English classes. Second, females use more learning strategies than males. The researchers infer from the results that there is an attainment gap, namely, male students underachieve females

Improving Data Collection and Analysis Interface for the Data Acquisition Software of the Spin Laboratory at NASA Glenn Research Center

In jet engines, turbines spin at high rotational speeds. The forces generated from these high speeds make the rotating components of the turbines susceptible to developing cracks that can lead to major engine failures. The current inspection technologies only allow periodic examinations to check for cracks and other anomalies due to the requirements involved, which often necessitate entire engine disassembly. Also, many of these technologies cannot detect cracks that are below the surface or closed when the crack is at rest. Therefore, to overcome these limitations, efforts at NASA Glenn Research Center are underway to develop techniques and algorithms to detect cracks in rotating engine components. As a part of these activities, a high-precision spin laboratory is being utilized to expand and conduct highly specialized tests to develop methodologies that can assist in detecting predetermined cracks in a rotating turbine engine rotor. This paper discusses the various features involved in the ongoing testing at the spin laboratory and elaborates on its functionality and on the supporting data system tools needed to enable successfully running optimal tests and collecting accurate results. The data acquisition system and the associated software were updated and customized to adapt to the changes implemented on the test rig system and to accommodate the data produced by various sensor technologies. Discussion and presentation of these updates and the new attributes implemented are herein reporte

Controlling Growth of Poly (Triethylene Glycol Acrylate-Co-Spiropyran Acrylate) Copolymer Liquid Films on a Hydrophilic Surface by Light and Temperature

A quartz crystal microbalance with dissipation monitoring (QCM-D) was employed for in situ investigations of the effect of temperature and light on the conformational changes of a poly (triethylene glycol acrylate-co-spiropyran acrylate) (P (TEGA-co-SPA)) copolymer containing 12–14% of spiropyran at the silica–water interface. By monitoring shifts in resonance frequency and in acoustic dissipation as a function of temperature and illumination conditions, we investigated the evolution of viscoelastic properties of the P (TEGA-co-SPA)-rich wetting layer growing on the sensor, from which we deduced the characteristic coil-to-globule transition temperature, corresponding to the lower critical solution temperature (LCST) of the PTEGA part. We show that the coil-to-globule transition of the adsorbed copolymer being exposed to visible or UV light shifts to lower LCST as compared to the bulk solution: the transition temperature determined acoustically on the surface is 4 to 8 K lower than the cloud point temperature reported by UV/VIS spectroscopy in aqueous solution. We attribute our findings to non-equilibrium effects caused by confinement of the copolymer chains on the surface. Thermal stimuli and light can be used to manipulate the film formation process and the film’s conformational state, which affects its subsequent response behavior