Spin wave dispersion softening in the ferromagnetic Kondo lattice model for manganites

Spin dynamics is calculated in the ferromagnetic (FM) state of the generalized Kondo lattice model taking into account strong on-site correlations between e_g electrons and antiferromagnetic (AFM) exchange among t_{2g} spins. Our study suggests that competing FM double-exchange and AFM super-exchange interaction lead to a rather nontrivial spin-wave spectrum. While spin excitations have a conventional Dq^2 spectrum in the long-wavelength limit, there is a strong deviation from the spin-wave spectrum of the isotropic Heisenberg model close to the zone boundary. The relevance of our results to the experimental data are discussed.Comment: 6 RevTex pages, 3 embedded PostScript figure

The Dynamics of Hybrid Metabolic-Genetic Oscillators

The synthetic construction of intracellular circuits is frequently hindered by a poor knowledge of appropriate kinetics and precise rate parameters. Here, we use generalized modeling (GM) to study the dynamical behavior of topological models of a family of hybrid metabolic-genetic circuits known as "metabolators." Under mild assumptions on the kinetics, we use GM to analytically prove that all explicit kinetic models which are topologically analogous to one such circuit, the "core metabolator," cannot undergo Hopf bifurcations. Then, we examine more detailed models of the metabolator. Inspired by the experimental observation of a Hopf bifurcation in a synthetically constructed circuit related to the core metabolator, we apply GM to identify the critical components of the synthetically constructed metabolator which must be reintroduced in order to recover the Hopf bifurcation. Next, we study the dynamics of a re-wired version of the core metabolator, dubbed the "reverse" metabolator, and show that it exhibits a substantially richer set of dynamical behaviors, including both local and global oscillations. Prompted by the observation of relaxation oscillations in the reverse metabolator, we study the role that a separation of genetic and metabolic time scales may play in its dynamics, and find that widely separated time scales promote stability in the circuit. Our results illustrate a generic pipeline for vetting the potential success of a potential circuit design, simply by studying the dynamics of the corresponding generalized model

Prevalence and distribution of oral health knowledge according to sociodemographic, behavioural and clinical characteristics in selected coastal districts of Tanzania

Background: Having knowledge about health issues is necessary for making informed decisions related to practicing lifestyles conducive to good health. The aim of this study was to identify socio-demographic, behavioural and clinical covariates of knowledge related to the cause and prevention of oral diseases among older adults in Tanzania.Methods: A cross sectional household survey was conducted in two regions of Tanzania; Pwani and Dar es Salaam city. A total 1031 older adults aged 55 and above were personally interviewed, before undergoing a full mouth examination.Results: the proportion of older adults with knowledge (total knowledge score≥ 1) on dental caries and gum disease was 14.9% and 2.3%, respectively. Having low education level, belonging to a lower wealth quartile and lack of perceived need to see a dentist, were strongly associated with having no knowledge on dental caries. None of the covariates were significantly associated with knowledge on gum disease.Conclusion: Knowledge on the two oral diseases is low among older adults interviewed. Factors associated with knowledge demonstrate substantial socio economic disparities. Development of policies and health education programs that target behavioural and socio economic determinants is recommended

Feedback-based admission control for hard real-time task allocation under dynamic workload on many-core systems

In hard real-time systems, a computationally expensive schedulability analysis has to be performed for every task. Fulfilling this requirement is particularly tough when system workload and service capacity are not available a priori and thus the analysis has to be conducted at runtime. This paper presents an approach for applying controltheory-based admission control to predict the task schedulability so that the exact schedulability analysis is performed only to the tasks with positive prediction results. In case of a careful fine-tuning of parameters, the proposed approach can be successfully applied even to many-core embedded systems with hard real-time constraints and other time-critical systems. The provided experimental results demonstrate that, on average, only 62% of the schedulability tests have to be performed in comparison with the traditional, open-loop approach. The proposed approach is particularly beneficial for heavier workloads, where the number of executed tasks is almost unchanged in comparison with the traditional open-loop approach. By our approach, only 32% of exact schedulability tests have to be conducted. Moreover, for the analysed industrial workloads with dependent jobs, the proposed technique admitted and executed 11% more tasks while not violating any timing constraints

A Single-Loop DC Motor Control System Design with a Desired Aperiodic Degree of Stability

The application of the original analytical approach for Pi-controller synthesis of a stable second-order plant is considered. This approach allows finding controller parameters without any intensive computing by using the direct expressions. The plant model is obtained on the basis of identification, which is based on the automated real-interpolation method. The results of natural experiments are given

Resilient Parameter-Invariant Control With Application to Vehicle Cruise Control

This work addresses the general problem of resilient control of unknown stochastic linear time-invariant (LTI) systems in the presence of sensor attacks. Motivated by a vehicle cruise control application, this work considers a first order system with multiple measurements, of which a bounded subset may be corrupted. A frequency-domain-designed resilient parameter-invariant controller is introduced that simultaneously minimizes the effect of corrupted sensors, while maintaining a desired closed-loop performance, invariant to unknown model parameters. Simulated results illustrate that the resilient parameter-invariant controller is capable of stabilizing unknown state disturbances and can perform state trajectory tracking

A method for the reconstruction of unknown non-monotonic growth functions in the chemostat

We propose an adaptive control law that allows one to identify unstable steady states of the open-loop system in the single-species chemostat model without the knowledge of the growth function. We then show how one can use this control law to trace out (reconstruct) the whole graph of the growth function. The process of tracing out the graph can be performed either continuously or step-wise. We present and compare both approaches. Even in the case of two species in competition, which is not directly accessible with our approach due to lack of controllability, feedback control improves identifiability of the non-dominant growth rate.Comment: expansion of ideas from proceedings paper (17 pages, 8 figures), proceedings paper is version v

Identification of single-input–single-output quantum linear systems

The purpose of this paper is to investigate system identification for single-input–single-output general (active or passive) quantum linear systems. For a given input we address the following questions: (1) Which parameters can be identified by measuring the output? (2) How can we construct a system realization from sufficient input-output data? We show that for time-dependent inputs, the systems which cannot be distinguished are related by symplectic transformations acting on the space of system modes. This complements a previous result of Guţă and Yamamoto [IEEE Trans. Autom. Control 61, 921 (2016)] for passive linear systems. In the regime of stationary quantum noise input, the output is completely determined by the power spectrum. We define the notion of global minimality for a given power spectrum, and characterize globally minimal systems as those with a fully mixed stationary state. We show that in the case of systems with a cascade realization, the power spectrum completely fixes the transfer function, so the system can be identified up to a symplectic transformation. We give a method for constructing a globally minimal subsystem direct from the power spectrum. Restricting to passive systems the analysis simplifies so that identifiability may be completely understood from the eigenvalues of a particular system matrix

Series-Parallel and Parallel Identification Schemes for a Class of Continuous Nonlinear Systems

Fig. 4(a) shows the parameter estimates under the existence of the measmable disturbance (di = 5, a\ = 0) with the parameter estimates under the ideal condition (di = a\ = 0) overlaid. Since the inserted DDR's remove the disturbance from the inputoutput relation, the disturbance does not slow down the identification speed. Fig. 4(6) shows the parameter estimates under the existence of the unmeasurable disturbance (di = 0, d 2 = 1) with the parameter estimates under the ideal condition (di = di = 0) overlaid. There exists no difference between the two cases as far as the identification speed is concerned. In the simulation, the step disturbances, di and d 2 , were injected to the plant at k = 0. Thus, strictly speaking, at k = 0, di(k) and d 2 (fc) did not satisfy equation V Conclusions Adverse effects of deterministic disturbances in linear identification have been pointed out, and a method to remove such effects has been presented. This method works for measurable and unmeasurable disturbances which can be regarded as the outputs of free systems with known dynamics. The unmeasurable disturbance must always be removed to achieve successful identification. When the disturbance is measurable, however, it does not have to be removed if it can provide a positive contribution to identification. A constant disturbance was shown to slow down the identification speed. The best results will be obtained if one selects a DDR which removes only undesirable disturbances. In this technical brief, discrete series-parallel and parallel identification schemes for single-input, single-output systems were considered. The same principle, however, can be extended to other situations including the continuous time case and multi-input, and multi-output case. References 1 Astrom, K. J., and Eykhoff, P., "System Identification -A Survey," Automatica, Vol. 7, 1971, pp. 123-16