Probing the linearity and nonlinearity in the transitions of the atmospheric circulation

International audienceIn this paper, we apply the principles of information theory that relate to the definition of nonlinear predictability, which is a measure that describes both the linear and nonlinear components of a system. By comparing this measure to a measure of linear predictability, one can assess whether a given system has a strong nonlinear or a strong linear component. This provides insights as to whether the system should be modelled by a nonlinear model or by a linear model. We apply these ideas to a known dynamical system and to a time series that describe the transitions in atmospheric circulation

The effect of truncation and round-off on computer simulated chaotic trajectories

AbstractIn this short report I demonstrate that due to truncation and round-off, computer generated trajectories of chaotic dynamical systems eventually will become periodic

A discussion on chaos

In this paper I review some of the basis principles of the theory of dynamical systems. I introduce the reader to the definition of chaos and strange attractors and discuss their implications

A Comparative 2-Dimensional Gel Protein Database of the Intact and Regenerating Newt Limbs

In this paper we describe a two-dimensional gel database of the regenerating newt limb. Protein synthesis was compared in the intact limb, in the 1-week regenerating limb, representing the dedifferentiation stage, and in the 2-week regenerating limb, representing the formation of the blastema. This comparative database provided data on differential expression of about 800 proteins during the process of limb regeneration. In addition, a map has been generated for these proteins for future guidance in characterizing further new, unknown proteins. The overall expression patterns of the proteins indicated that the dedifferentiation stage was marked by down-regulation of most proteins, while the blastema formation was marked by the appearance of many new proteins. The potential use of such a database in isolating factors involved during limb regeneration is discussed

Empirically derived climate predictability over the extratropical northern hemisphere

International audienceA novel application of a technique developed from chaos theory is used in describing seasonal to interannual climate predictability over the Northern Hemisphere (NH). The technique is based on an empirical forecast scheme - local approximation in a reconstructed phase space - for time-series data. Data are monthly 500 hPa heights on a latitude-longitude grid covering the NH from 20° N to the equator. Predictability is estimated based on the linear correlation between actual and predicted heights averaged over a forecast range of one- to twelve.month lead. The method is capable of extracting the major climate signals on this time scale including ENSO and the North Atlantic Oscillation

Observing extreme events in incomplete state spaces with application to rainfall estimation from satellite images

International audienceReconstructing the dynamics of nonlinear systems from observations requires the complete knowledge of its state space. In most cases, this is either impossible or at best very difficult. Here, by using a toy model, we investigate the possibility of deriving useful insights about the variability of the system from only a part of the complete state vector. We show that while some of the details of the variability might be lost, other details, especially extreme events, are successfully recovered. We then apply these ideas to the problem of rainfall estimation from satellite imagery. We show that, while reducing the number of observables reduces the correlation between actual and inferred precipitation amounts, good estimates for extreme events are still recoverable

Patterns of Gene Expression in Microarrays and Expressed Sequence Tags from Normal and Cataractous Lenses

In this contribution, we have examined the patterns of gene expression in normal and cataractous lenses as presented in five different papers using microarrays and expressed sequence tags. The purpose was to evaluate unique and common patterns of gene expression during development, aging and cataracts

Identification of MicroRNAs and Other Small RNAs from the Adult Newt Eye

MicroRNAs (miRNAs) are capable of controlling gene expression by targeting complimentary sequences in many mRNAs. Thus, a small number of miRNAs are capable of regulating expression of many different genes. miRNAs have been found in all animals from Drosophila to human and they are highly conserved. This work was undertaken in order to identify such RNAs in the newt eye

The Impact of Multi-layered Data-blocks on Controller Performance

As a consequence of the push to increase National Airspace System capacity, air traffic control displays will not only have to show the increasing number of aircraft, but also all the associated data such as airspeed and altitude. The representation of aircraft data and associated relational information, often superimposed on a map, leads to cluttered displays, which could negatively affect controller performance, especially as aircraft numbers increase. To investigate these issues further, an experiment was conducted that examined the effect of increasing data-block lines on controller performance in an aircraft vectoring task. Data-block design, the primary factor, varied in the number of lines displayed (2-5). In addition a data-block information priority factor was examined that addressed the frequency of information access across data-block lines. Results demonstrated that while task load, measured as an increasing number of planes under control, negatively influenced reaction times and task accuracy, the number of lines in a data block was not statistically significant. However there was a trend towards reduced performance when data-blocks exceeded more than three lines on a base layer. In addition, the data blocks that contained prioritized information across levels promoted faster reaction times, but at a cost of lower situation awareness. This research demonstrated that the design of data-blocks should consider the balance between reduction in data-block interaction time against the need to allow enough interaction time to build situation awareness.Civil Aerospace Medical Institut

Patterns of coexisting superconducting and particle-hole condensates

We have studied systematically the influence of particle-hole symmetric and asymmetric kinetic terms on the ordered phases that we may observe competing or coexisting in a tetragonal system. We show that there are precise patterns of triplets of ordered phases that are accessible (i.e. it is impossible to observe two of them without the third one). We found a systematic way to predict these patterns of states and tested it by identifying at least 16 different patterns of three order parameters that necessarily coexist in the presence of the kinetic terms. We show that there are two types of general equations governing the competition of all these triplets of order parameters and we provide them.Comment: Published versio