Technological Revolutions and Economic Growth:The �Age of Steam� Reconsidered

revolution, economic growth, steam, technological

Technological revolutions and economic growth : the "age of steam" reconsidered

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Robust Attitude Control of an Agile Aircraft Using Improved Q-Learning

Attitude control of a novel regional truss-braced wing (TBW) aircraft with low stability characteristics is addressed in this paper using Reinforcement Learning (RL). In recent years, RL has been increasingly employed in challenging applications, particularly, autonomous flight control. However, a significant predicament confronting discrete RL algorithms is the dimension limitation of the state-action table and difficulties in defining the elements of the RL environment. To address these issues, in this paper, a detailed mathematical model of the mentioned aircraft is first developed to shape an RL environment. Subsequently, Q-learning, the most prevalent discrete RL algorithm, will be implemented in both the Markov Decision Process (MDP) and Partially Observable Markov Decision Process (POMDP) frameworks to control the longitudinal mode of the proposed aircraft. In order to eliminate residual fluctuations that are a consequence of discrete action selection, and simultaneously track variable pitch angles, a Fuzzy Action Assignment (FAA) method is proposed to generate continuous control commands using the trained optimal Q-table. Accordingly, it will be proved that by defining a comprehensive reward function based on dynamic behavior considerations, along with observing all crucial states (equivalent to satisfying the Markov Property), the air vehicle would be capable of tracking the desired attitude in the presence of different uncertain dynamics including measurement noises, atmospheric disturbances, actuator faults, and model uncertainties where the performance of the introduced control system surpasses a well-tuned Proportional–Integral–Derivative (PID) controller

Analytical Study of Sub-Wavelength Imaging by Uniaxial Epsilon-Near-Zero Metamaterial Slabs

We discuss the imaging properties of uniaxial epsilon-near-zero metamaterial slabs with possibly tilted optical axis, analyzing their sub-wavelength focusing properties as a function of the design parameters. We derive in closed analytical form the associated two-dimensional Green's function in terms of special cylindrical functions. For the near-field parameter ranges of interest, we are also able to derive a small-argument approximation in terms of simpler analytical functions. Our results, validated and calibrated against a full-wave reference solution, expand the analytical tools available for computationally-efficient and physically-incisive modeling and design of metamaterial-based sub-wavelength imaging systems.Comment: 25 pages, 9 figures (modifications in the text; two figures and several references added

Mode Confinement in Photonic Quasi-Crystal Point-Defect Cavities for Particle Accelerators

In this Letter, we present a study of the confinement properties of point-defect resonators in finite-size photonic-bandgap structures composed of aperiodic arrangements of dielectric rods, with special emphasis on their use for the design of cavities for particle accelerators. Specifically, for representative geometries, we study the properties of the fundamental mode (as a function of the filling fraction, structure size, and losses) via 2-D and 3-D full-wave numerical simulations, as well as microwave measurements at room temperature. Results indicate that, for reduced-size structures, aperiodic geometries exhibit superior confinement properties by comparison with periodic ones.Comment: 4 pages, 4 figures, accepted for publication in Applied Physics Letter

MICRORNA AND GENE EXPRESSION CHANGES UNDERLYING THE PATHOLOGY OF NEMALINE MYOPATHY

Nemaline myopathy (NM) is a clinically and genetically heterogeneous neuromuscular disorder characterized by muscle weakness and hypotonia due to sarcomeric disarray and the formation of rod-like "nemaline" bodies in the muscle fibers. The disease affects about 1 in 50.000 and is caused by mutations in nebulin and \u3b1-skeletal muscle actin, while mutations in \u3b1-tropomyosin, \u3b2-tropomyosin, troponin T1, and cofilin-2 are more rare. Currently no therapies or markers exist. Gene expression profiling has provided insights into the gene expression changes associated with NM in human patients. Furthermore, a number of microRNAs (miRs) have been shown to be specifically dysregulated in muscles from NM patients. Based on these findings, we hypothesized that unique regulatory mechanisms regulated by miRs may underlie the pathology of NM irrespective of the causative mutation. To study this, we took advantage of a transgenic knockin mouse model of NM, expressing a mutant form of \u3b1-skeletal actin (Acta1(H40Y)KI) (KI) that develops a severe form of the disease. Interestingly, while KI males exhibit a severe phenotype resulting in death from around 10 weeks of age, females are less severely affected and are fertile. The first aim of our study was to perform gene expression profiling on diaphragm (DIA) and tibialis anterior (TA) muscle of KI mouse and compare the results with previously published gene expression analyses of NM patients and the Tmslow(Met9Arg) Tg (Tg) mouse model of a mild form of NM. The second aim was to compare the gene expression profile of male and female KI mice to provide insights into the molecular basis for the different severity of the disease in males and females. The third aim was to investigate the miR expression profile in KI males at an early and late stage of the disease to study miR expression in relation to the development of the disease. The gene expression study was conducted on 3-week-old males and 10-week-old males and females. The highest number of dysregulated genes were found in 3-week-old males. Between muscles (DIA and TA) only few altered genes were in common, possibly due to a peculiar gene expression pattern of the DIA. Interestingly, 10-week-old females showed a gene expression pattern more similar to 3-week-old males than to 10-week-old males, reflecting a delay in the development of the phenotype. However, although the specific dysregulated genes were different, some pathways were commonly dysregulated under different conditions. The same pathways, i.e. metabolic pathways, were found to be dysregulated in KI and human NM patients, but not in Tg mice. Expression levels of selected miRs that are altered in human NM patients were also altered in KI mice, but not in Tg mice. MiR-381 was highly upregulated and two of its predicted targets were validated in vitro by a luciferase assay: the calcium channel protein TRPM7 and the ubiquitin-related protein Trim63/MURF1. The results of this study indicate that Acta1(H40Y)KI is a good model of NM that recapitulates NM disease from both a phenotypic and genetic point of view. It is a better model for NM than the Tg mouse, showing gene and miR expression patterns more similar to NM patients. The biological meaning of the altered gene expression patterns and their possible regulation by miRs remain to be investigated in more detail

On characterisations of the input to state stability properties for conformable fractional order bilinear systems

This paper proposes for the first time the theoretical requirements that a fractional-order bilinear system with conformable derivative has to fulfil in order to satisfy different input-to-state stability (ISS) properties. Variants of ISS, namely ISS itself, integral ISS, exponential integral ISS, small-gain ISS, and strong integral ISS for the general class of conformable fractional-order bilinear systems are investigated providing a set of necessary and sufficient conditions for their existence and then compared. Finally, the correctness of the obtained theoretical results is verified by numerical example

Evaluation of fiber-optic phase-gradient meta-tips for sensing applications

Recently, within the emerging framework of "lab-on-fiber" technologies, we successfully demonstrated the integration of phase-gradient plasmonic metasurfaces on the tip of an optical fiber. The res..

Theoretical status of Bs-mixing and lifetimes of heavy hadrons

We review the theoretical status of the lifetime ratios τB+/τBd, τBs/τBd, τΛb/τBd and τBc and of the mixing quantities ΔMs, ΔΓs and ϕs. ΔMs and ΔΓs suffer from large uncertainties due to the badly known decay constants, while the ratio ΔΓs/ΔMs can be determined with almost no non-perturbative uncertainties, therefore it can be used perfectly to find possible new physics contributions in the mixing parameters. We suggest a very clear method of visualizing the bounds on new physics and demonstrate this by combining the latest experimental numbers on the mixing quantities quantities with theory – one already gets some hints for new physics contributions, but more precise experimental numbers are needed to draw some definite conclusions. We conclude with a ranking list of all the discussed quantities according to their current theoretical uncertainties and point out possible improvements