Kinetic surface roughening for the Mullins-Herring equation

Using the linearity property of the Mullins-Herring equation when the velocity is zero with a Gaussian noise, we obtain an analytic form for the global mean-square surface width and height-height correlation function. This can be used to read the critical exponents in any dimension. In particular for d=1 we show that although the surface is super rough the system exhibits Family-Vicsek scaling behavior.Comment: 5 page

Chaotic behavior in Casimir oscillators: A case study for phase change materials

Casimir forces between material surfaces at close proximity of less than 200 nm can lead to increased chaotic behavior of actuating devices depending on the strength of the Casimir interaction. We investigate these phenomena for phase change materials in torsional oscillators, where the amorphous to crystalline phase transitions lead to transitions between high and low Casimir force and torque states respectively, without material compositions. For a conservative system bifurcation curve and Poincare maps analysis show the absence of chaotic behavior but with the crystalline phase (high force/torque state) favoring more unstable behavior and stiction. However, for a non-conservative system chaotic behavior can occur introducing significant risk for stiction, which is again more pronounced for the crystalline phase. The latter illustrates the more general scenario that stronger Casimir forces and torques increase the possibility for chaotic behavior. The latter is making impossible to predict whether stiction or stable actuation will occur on a long term basis, and it is setting limitations in the design of micro/nano devices operating at short range nanoscale separations.Comment: 30 pages, 13 figure

Aftermath Epidemics: Percolation on the Sites Visited by Generalized Random Walks

We study percolation on the sites of a finite lattice visited by a generalized random walk of finite length with periodic boundary conditions. More precisely, consider Levy flights and walks with finite jumps of length $>1$ (like knight's move random walks (RW) in 2 dimensions and generalized knight's move RW in 3d). In these walks, the visited sites do not form (as in ordinary RW) a single connected cluster, and thus percolation on them is non-trivial. The model essentially mimics the spreading of an epidemic in a population weakened by the passage of some devastating agent -- like diseases in the wake of a passing army or of a hurricane. Using the density of visited sites (or the number of steps in the walk) as a control parameter, we find a true continuous percolation transition in all cases except for the 2-d knight's move RW and Levy flights with Levy parameter $\sigma \geq 2$. For 3-d generalized knight's move RW, the model is in the universality class of Pacman percolation, and all critical exponents seem to be simple rationals, in particular $\beta=1$. For 2-d Levy flights with $0 <\sigma < 2$, scale invariance is broken even at the critical point, which leads at least to very large corrections in finite size scaling, and even very large simulations were unable to determine unambiguously the critical exponents.Comment: 11 pages, 14 figure

Dependence of chaotic actuation dynamics of Casimir oscillators on optical properties and electrostatic effects

With Casimir and electrostatic forces playing a crucial role for the performance and stability of microelectromechanical systems (MEMS), the presence of chaotic behavior, which is often unavoidable, leads to device malfunction due to stiction. Therefore, we investigate here how the optical properties of different materials influence the chaotic behavior of electrostatic torsional MEMS due to changes in magnitude of the Casimir forces and torques. We consider the materials Au, which is a good conductor, AIST, which is a phase change material being close to metal in the crystalline state, and finally doped SiC as a very poor conductor. For the conservative systems, there is no chaotic behavior and the analysis of phase portraits and bifurcation diagrams reveal the strong sensitivity of stable actuation dynamics on the material optical properties, while applied electrostatic potentials lead faster to instability and stiction for higher conductivity materials. For the driven systems, the Melnikov method is used to study the chaotic behavior. The results from this method are supported by the study of the contours of the transient time to stiction in the phase plane, which reveal a substantially increased chaotic behavior for higher conductivity materials, associated with stronger Casimir torques and applied electrostatic potentials

New elevator system constructed by multi-translator linear switched reluctance motor with enhanced motion quality

In this work, a new elevator system created by a linear switched reluctance motor is presented. Unlike conventional linear motors, the proposed linear motor has more than one translator. Each phase in a translator generates a pulsing force; hence, the total generated force has noticeable ripple making it difficult to soft motion. In order to solve this problem, similar phases in different translators have been located in positions with specified distances together. As a result, similar force pulses would be shifted so that they can compensate together. An appropriate control strategy has been designed for the system, which can control the current, force, speed, and position simultaneously. A conventional proportional-integral controller and an adaptive fuzzy controller have been used to control the speed. In order to have a precise study, a prototype elevator system along with its control unit has been made and the obtained results have been compared with the simulation results. These results confirm that the proposed structure can significantly produce force and speed ripples. The Institution of Engineering and Technology 2020.Scopus2-s2.0-8509165714

Adaptive control strategy for velocity control of a linear switched reluctance motor

A new adaptive control strategy for a double-sided linear switched reluctance motor is proposed in this work. Switched reluctance motors inherently have non-linear dynamics that complicates their analysis and control. The Takagi-Sugeno fuzzy logic system has been used in this work to achieve an appropriate adaptive control system for the proposed linear motor. The fuzzy system has been heightened by non-linear rule consequences and a time-varying parameter. Updated laws have been designed to refresh the amount of the parameter consequently the suggested control system shows a stable performance in control of switched reluctance motors. The proposed control strategy is independent of the uncertainties of the motor dynamics and has an acceptable adaptability. This control method along with a conventional fuzzy logic based system have been studied on the proposed linear switched reluctance motor and their performances were compared in different performance conditions. An appropriate evaluation method has been used to compare the obtained results. The efficiency of the proposed method in different velocity commands has been examined and confirmed using appropriate simulation and experimental results. The Institution of Engineering and Technology 2020Scopus2-s2.0-8508983303

Effect of intermediate layer in photocurrent improvement of three-layer photoanodes using WO3 and Fe2O3

Sol–gel method was applied to synthesize WO3/Fe2O3 three-layer films in order to improve the generated photocurrent under UV–vis light irradiation. The films were deposited on FTO glass substrates through doctor bladding method. The samples were then calcined at 500 °C. The photocurrents of the synthesized photoanodes were evaluated by measuring the electric current and voltage under UV–vis light at room temperature. Scanning electron microscopy (SEM) revealed unique surface morphologies owing to the presence of the intermediate layers. At an applied potential of 1300 mV, the WO3\Fe2O3\WO3 and Fe2O3\WO3\Fe2O3 photoanodes exhibited photocurrent densities up to 0.1 mA/cm2 and 0.6 mA/cm2, respectively. It was found that porous films with easy accessibility to the inner surface reveal high photocurrents. The intermediate layer of WO3 demonstrated higher values of photocurrent due to roughness enhancement on the upper surface with columnar tree-growth particles. However, a compact state was observed on the cross section of Fe2O3 growth. A comparison was also drawn between the two and three-layer photoanodes using Fe2O3 andWO3. The films were characterized by XRD, SEM/EDX, and UV–vis irradiation to determine the photocurrent densities

Effects of a Designed Discharge Plan on Anxiety and Length of Hospital Stay in Patients Undergoing Heart Valve Replacement

Background & Objective: Anxiety is the most common issue in the candidates of surgical heart valve replacement. The length of hospital stay in these patients is economically and organizationally important as a predictor of their recovery from acute physical conditions. The present study aimed to assess the effects of a designed discharge plan on anxiety and length of hospital stay in patients undergoing heart valve replacement. Materials and Methods: This clinical trial was conducted on 65 candidates of heart valve replacement in Chamran Hospital in Isfahan, Iran, who were randomly divided into the intervention and control groups. In the intervention group, the designed discharge plan was implemented and continued one month after discharge via phone follow-up. Length of hospital stay and anxiety were analyzed before the intervention and one and three months after discharge in both groups in SPSS. Results: ANOVA indicated that the mean anxiety in the study groups was significantly different at different times (P0.05). Conclusion: The designed discharge plan reduced anxiety in the patients, while its effect on the length of hospital stay requires further investigation. Therefore, it is recommended that the discharge program be used as an effective approach to maintaining care in patients undergoing heart valve replacement. Keywords: Discharge Plan, Anxiety, Hospitalization, Heart Valve Replacemen

Structure of a Burkholderia pseudomallei Trimeric Autotransporter Adhesin Head

Pathogenic bacteria adhere to the host cell surface using a family of outer membrane proteins called Trimeric Autotransporter Adhesins (TAAs). Although TAAs are highly divergent in sequence and domain structure, they are all conceptually comprised of a C-terminal membrane anchoring domain and an N-terminal passenger domain. Passenger domains consist of a secretion sequence, a head region that facilitates binding to the host cell surface, and a stalk region.Pathogenic species of Burkholderia contain an overabundance of TAAs, some of which have been shown to elicit an immune response in the host. To understand the structural basis for host cell adhesion, we solved a 1.35 A resolution crystal structure of a BpaA TAA head domain from Burkholderia pseudomallei, the pathogen that causes melioidosis. The structure reveals a novel fold of an intricately intertwined trimer. The BpaA head is composed of structural elements that have been observed in other TAA head structures as well as several elements of previously unknown structure predicted from low sequence homology between TAAs. These elements are typically up to 40 amino acids long and are not domains, but rather modular structural elements that may be duplicated or omitted through evolution, creating molecular diversity among TAAs.The modular nature of BpaA, as demonstrated by its head domain crystal structure, and of TAAs in general provides insights into evolution of pathogen-host adhesion and may provide an avenue for diagnostics

Global, regional, and national burden of colorectal cancer and its risk factors, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Funding: F Carvalho and E Fernandes acknowledge support from Fundação para a Ciência e a Tecnologia, I.P. (FCT), in the scope of the project UIDP/04378/2020 and UIDB/04378/2020 of the Research Unit on Applied Molecular Biosciences UCIBIO and the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy i4HB; FCT/MCTES through the project UIDB/50006/2020. J Conde acknowledges the European Research Council Starting Grant (ERC-StG-2019-848325). V M Costa acknowledges the grant SFRH/BHD/110001/2015, received by Portuguese national funds through Fundação para a Ciência e Tecnologia (FCT), IP, under the Norma Transitória DL57/2016/CP1334/CT0006.proofepub_ahead_of_prin