Microtiter spectrophotometric biofilm production assay analyzed with metrological methods and uncertainty evaluation

The microbial biofilm is a structure often developed by microorganisms when performing their harmful effects, both in the medical and industrial fields. Therefore, methods allowing identification and analysis of the biofilm play a fundamental role in determining the kind of intervention needed to avoid these effects. The microtiter spectrophotometric assay is recognized as the gold standard method to quantify a biofilm and to analyze the anti-biofilm activity of various substances. The aim of the present work is to validate this method through an uncertainty evaluation, covering eight different microbial species.     

Visuomotor optimality and its utility in parametrization of response

We present a method of characterizing visuomotor response by inferring subject-specific physiologically meaningful parameters within the framework of optimal control theory. The characterization of visuomotor response is of interest in the assessment of impairment and rehabilitation, the analysis of man--machine systems, and sensorimotor research. We model the visuomotor response as a linear quadratic Gaussian (LQG) controller, a Bayesian optimal state estimator in series with a linear quadratic regulator. Subjects used a modified computer mouse to attempt to keep a displayed cursor at a fixed desired location despite a Gaussian random disturbance and simple cursor dynamics. Nearly all subjects' behavior was consistent with the hypothesized optimality. Experimental data were used to fit an LQG model whose assumptions are simple and consistent with other sensorimotor work. The parametrization is parsimonious and yields quantities of clear physiological meaning: noise intensity, level of exertion, delay, and noise bandwidth. Significant variations in response were observed, consistent with signal-dependent noise and changes in exerted effort. This is a novel example of the role of optimal control theory in explaining variance in human visuomotor response. We also present technical improvements on the use of LQG in human operator modeling.     

Getting around in electric vehicles

The main problem facing the designer of electric vehicles for urban mobility is the large mass and volume taken by the energy sources (batteries or fuel cells plus storage elements) [1]. Moreover, accommodation of an electric propulsion system in two-wheel vehicles is usually intricate and the added devices may impair the driving features of the vehicles. Conversely, four-wheel vehicles are suited for accommodating an electric propulsion system but they have a larger track, which is a handicap in city traffic. Of course, the track can be shrunk, but its excessive reduction makes the vehicles prone to rollover especially at higher speeds.     

Securing fruit production: Opportunities from the elucidation of the molecular mechanisms of postharvest fungal infections

Fruit-based diets have been adopted by the public worldwide because of their nutritional value. Many advances have also been made in the elucidation of host–pathogen interaction in the postharvest phase of fruits, in the hope of improving the management of diseases caused by pathogenic molds. In this study, we presented the molecular mechanisms by which pathogenic mold infects fruit in the postharvest phase, and focused on the knowledge gained from recent molecular techniques such as differential analysis of gene expression, targeted insertion, and mutagenesis. Current postharvest pathogenic fungal control strategies were then examined on the basis of their mechanisms for altering the infection process in order to explore new perspectives for securing fruit production. We found that biotechnological advances have led to an understanding of the new basic molecular processes involved in fruit fungal infection and to the identification of new genes, proteins and key factors that could serve as ideal targets for innovative antifungal strategies. In addition, the most commonly used steps to evaluate an approach to disrupt the fruit fungal infection process are mainly based on the inhibition of mycelial growth, spore germination, disruption of Adenosine triphosphate (ATP) synthesis, induction of oxidative stress, cell wall membrane damage, and inhibition of key enzymes. Finally, the alteration of the molecular mechanisms of signaling and response pathways to infection stimulation should also guide the development of effective control strategies to ensure fruit production.     

ICT Governance: A Reference Framework

This article deals with information and communication technology (ICT) governance, a topic that has been discussed in the literature over the last 20 years. In order to offer a conceptualized view of the ICT governance models adopted by companies, a theoretical framework has been developed. A review of the available literature dealing with ICT governance, as well as a critical analysis of 27 case studies, was carried out, with the aim of highlighting the variables of the proposed framework.     

Limited benefit of joint estimation in multi‐agent iterative learning

This paper studies iterative learning control (ILC) in a multi‐agent framework, wherein a group of agents simultaneously and repeatedly perform the same task. Assuming similarity between the agents, we investigate whether exchanging information between the agents improves an individual's learning performance. That is, does an individual agent benefit from the experience of the other agents? We consider the multi‐agent iterative learning problem as a two‐step process of: first, estimating the repetitive disturbance of each agent; and second, correcting for it. We present a comparison of an agent's disturbance estimate in the case of (I) independent estimation, where each agent has access only to its own measurement, and (II) joint estimation, where information of all agents is globally accessible. When the agents are identical and noise comes from measurement only, joint estimation yields a noticeable improvement in performance. However, when process noise is encountered or when the agents have an individual disturbance component, the benefit of joint estimation is negligible. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

A UWB WBAN channel model based on a pseudo-dynamic measurement

In this paper, we expand the knowledge of the ultra-wideband (UWB) channel in the frequency range of 3.1?C10?GHz in close proximity of a human body. The channels under dynamic conditions due to the effect of body motions are studied through the pseudo-dynamic measurement method. Firstly, the first-order statistics of the channels, namely, amplitude distributions are investigated. Secondly, the dynamic features of the channels are also studied through the second-order statistics of the channels, namely, the good and bad channel durations as well as the LCR, which are important for a cross-layer design. Three strongest peaks capturing most of the energy of the channel are taken into account. Finally, a two-state alternating Weibull renewal process model is proposed. The model provides good usability with low complexity and can then be used to better design communication network protocols for WBANs. In addition, for the sake of designing a non-coherent receiver, the dynamic delay spread of the channel, which determines an energy collector detecting the signal energy over a time window, is investigated.     

Convex necessary and sufficient conditions for frequency domain model (in)validation under SLTV structured uncertainty

This paper deals with the problem of model (in)validation of discrete time, causal, linear time-invariant (LTI) stable models subject to slowly linear time-varying structured uncertainty, using frequency domain data corrupted by additive noise. It is well known that in the case of structured LTI uncertainty the problem is NP hard in the number of uncertainty blocks. The main contribution of this paper shows that, on the other hand, if one considers arbitrarily slowly time varying uncertainty and noise in L/sub 2/, then tractable, convex necessary and sufficient conditions for (in)validation can be obtained. Additional results include a discussion of the case where the noise is characterized in terms of the L/sub /spl infin// norm.     

Open-loop worst-case identification of nonSchur plants

This paper presents an LMI based algorithm for deterministic worst-case identification of nonSchur plants in an open-loop setting. Contrary to other approaches dealing with this problem, the proposed technique does not require prior knowledge of a stabilizing controller. The main result of the paper shows that, as the information is completed, the identified model converges, in the ?₂-induced topology, to the actual plant. Additional results include upper bounds on the worst-case identification error on the finite horizon. The usefulness of the proposed approach is illustrated with a practical example arising in the context of robust visual tracking.     

Full information and full control in a behavioral setting

In this paper, the concepts of Full Information and Full Control which arise in standard and control theory are extended to the behavioral framework. It is shown that the behavioral definitions are more fundamental than those given for the standard input/output case; in particular, the concept of state is not required and no a priori partition of the system variables into inputs and outputs needs to be performed. The interpretation of Full Information is to be able to reconstruct the error and disturbance variables from the control variables. The interpretation of Full Control is to be able to fully affect all the equations involving the error and the disturbance variables.