Robust moving horizon H∞ control of discrete time-delayed systems with interval time-varying delays

In this study, design of a delay-dependent type moving horizon state-feedback control (MHHC) is considered for a class of linear discrete-time system subject to time-varying state delays, norm-bounded uncertainties, and disturbances with bounded energies. The closed-loop robust stability and robust performance problems are considered to overcome the instability and poor disturbance rejection performance due to the existence of parametric uncertainties and time-delay appeared in the system dynamics. Utilizing a discrete-time Lyapunov-Krasovskii functional, some delay-dependent linear matrix inequality (LMI) based conditions are provided. It is shown that if one can find a feasible solution set for these LMI conditions iteratively at each step of run-time, then we can construct a control law which guarantees the closed-loop asymptotic stability, maximum disturbance rejection performance, and closed-loop dissipativity in view of the actuator limitations. Two numerical examples with simulations on a nominal and uncertain discrete-time, time-delayed systems, are presented at the end, in order to demonstrate the efficiency of the proposed method

Online Discrimination of Nonlinear Dynamics with Switching Differential Equations

How to recognise whether an observed person walks or runs? We consider a dynamic environment where observations (e.g. the posture of a person) are caused by different dynamic processes (walking or running) which are active one at a time and which may transition from one to another at any time. For this setup, switching dynamic models have been suggested previously, mostly, for linear and nonlinear dynamics in discrete time. Motivated by basic principles of computations in the brain (dynamic, internal models) we suggest a model for switching nonlinear differential equations. The switching process in the model is implemented by a Hopfield network and we use parametric dynamic movement primitives to represent arbitrary rhythmic motions. The model generates observed dynamics by linearly interpolating the primitives weighted by the switching variables and it is constructed such that standard filtering algorithms can be applied. In two experiments with synthetic planar motion and a human motion capture data set we show that inference with the unscented Kalman filter can successfully discriminate several dynamic processes online

Striations in the Taurus molecular cloud: Kelvin-Helmholtz instability or MHD waves?

The origin of striations aligned along the local magnetic field direction in the translucent envelope of the Taurus molecular cloud is examined with new observations of 12CO and 13CO J=2-1 emission obtained with the 10~m submillimeter telescope of the Arizona Radio Observatory. These data identify a periodic pattern of excess blue and redshifted emission that is responsible for the striations. For both 12CO and 13CO, spatial variations of the J=2-1 to J=1-0 line ratio are small and are not spatially correlated with the striation locations. A medium comprised of unresolved CO emitting substructures (cells) with a beam area filling factor less than unity at any velocity is required to explain the average line ratios and brightness temperatures. We propose that the striations result from the modulation of velocities and the beam filling factor of the cells as a result of either the Kelvin-Helmholtz instability or magnetosonic waves propagating through the envelope of the Taurus molecular cloud. Both processes are likely common features in molecular clouds that are sub-Alfvenic and may explain low column density, cirrus-like features similarly aligned with the magnetic field observed throughout the interstellar medium in far-infrared surveys of dust emission.Comment: 11 pages, 4 figures. Accepted for publication in MNRA

Interaction Between Motor Domains Can Explain the Complex Dynamics of Heterodimeric Kinesins

Motor proteins are active enzyme molecules that play a crucial role in many biological processes. They transform the chemical energy into the mechanical work and move unidirectionally along rigid cytoskeleton filaments. Single-molecule experiments suggest that motor proteins, consisting of two motor domains, move in a hand-over-hand mechanism when each subunit changes between trailing and leading positions in alternating steps, and these subunits do not interact with each other. However, recent experiments on heterodimeric kinesins suggest that the motion of motor domains is not independent, but rather strongly coupled and coordinated, although the mechanism of these interactions are not known. We propose a simple discrete stochastic model to describe the dynamics of homodimeric and heterodimeric two-headed motor proteins. It is argued that interactions between motor domains modify free energy landscapes of each motor subunit, and motor proteins still move via the hand-over-hand mechanism but with different transitions rates. Our calculations of biophysical properties agree with experimental observations. Several ways to test the theoretical model are proposed.Comment: To appear in New J. Phy

The discrimination capabilities of Micromegas detectors at low energy

The latest generation of Micromegas detectors show a good energy resolution, spatial resolution and low threshold, which make them idoneous in low energy applications. Two micromegas detectors have been built for dark matter experiments: CAST, which uses a dipole magnet to convert axion into detectable x-ray photons, and MIMAC, which aims to reconstruct the tracks of low energy nuclear recoils in a mixture of CF4 and CHF3. These readouts have been respectively built with the microbulk and bulk techniques, which show different gain, electron transmission and energy resolutions. The detectors and the operation conditions will be described in detail as well as their discrimination capabilities for low energy photons will be discussed.Comment: To be published in the proceedings of the TIPP2011 conference (Physics Procedia

The hot core towards the intermediate mass protostar NGC7129 FIRS 2: Chemical similarities with Orion KL

NGC 7129 FIRS 2 (hereafter FIRS 2) is an intermediate-mass (2 to 8 Msun) protostar located at a distance of 1250 pc. High spatial resolution observations are required to resolve the hot core at its center. We present a molecular survey from 218200 MHz to 221800 MHz carried out with the IRAM Plateau de Bure Interferometer. These observations were complemented with a long integration single-dish spectrum taken with the IRAM 30m telescope. We used a Local Thermodynamic Equilibrium (LTE) single temperature code to model the whole dataset. The interferometric spectrum is crowded with a total of ~300 lines from which a few dozens remain unidentified yet. The spectrum has been modeled with a total of 20 species and their isomers, isotopologues and deuterated compounds. Complex molecules like methyl formate (CH3OCHO), ethanol (CH3CH2OH), glycolaldehyde (CH2OHCHO), acetone (CH3COCH3), dimethyl ether (CH3OCH3), ethyl cyanide (CH3CH2CN) and the aGg' conformer of ethylene glycol (aGg'-(CH2OH)_2) are among the detected species. The detection of vibrationally excited lines of CH3CN, CH3OCHO, CH3OH, OCS, HC3N and CH3CHO proves the existence of gas and dust at high temperatures. In fact, the gas kinetic temperature estimated from the vibrational lines of CH3CN, ~405 K, is similar to that measured in massive hot cores. Our data allow an extensive comparison of the chemistry in FIRS~2 and the Orion hot core. We find a quite similar chemistry in FIRS 2 and Orion. Most of the studied fractional molecular abundances agree within a factor of 5. Larger differences are only found for the deuterated compounds D2CO and CH2DOH and a few molecules (CH3CH2CN, SO2, HNCO and CH3CHO). Since the physical conditions are similar in both hot cores, only different initial conditions (warmer pre-collapse phase in the case of Orion) and/or different crossing time of the gas in the hot core can explain this behavior.Comment: 30 pages, 9 figure

Multisite international collaborative clinical trials in mania.

Multi-regional collaborative clinical trials include those conducted across heterogeneous areas of the world under common protocols. Such trials appear to be driven primarily to provide data required for regulatory approval or licensing of new drug products in a relatively rapid and presumably efficient and cost-effective manner. Commonly, they include underserved populations and areas where costs of trials are lower than in most developed countries. In addition, such studies can potentially make innovative treatments widely and rapidly available in vast, international markets. Other potential benefits to collaborating sites may include diffusion of knowledge and improvement of research skills, as well as improvement of treatment and a broader salutary impact on health services and perhaps on employment opportunities and economic growth (Demol +6; Weihrauch, 1997; Glickman et al. 2009; Gopal et al. 2005; Greco +6; Diniz, 2008; ICH Guideline, 2002; Smulevich et al. 2005; U.S. FDA, 1998). Successful conduct of international trials requires compliance with varying local and international laws, regulations and ethical requirements, and confronting a range of systems of review of ethical aspects of subject recruitment, compensation, consenting procedures, research protocols, and provision of aftercare – all which can add complexity. In addition, there is variance among regions, countries and cultures in levels of education, and in the nature of information, financial inducements, clinical care and aftercare provided to research subjects. Complexities arise also from culture-dependent conceptualizations of mental disorders, criteria for diagnosis, and efforts at validating, interpreting and scoring of symptom ratings designed to characterize changes during treatment, and methods for detecting adverse events. In the continuing quest to define core or universal features of psychiatric disorders, it is crucial to consider the anthropological and cultural context in which they develop and are modified (Karno +6; Jenkins, 1993; Lopez-Ibor, 2003;