Towards a general theory of extremes for observables of chaotic dynamical systems

In this paper we provide a connection between the geometrical properties of the attractor of a chaotic dynamical system and the distribution of extreme values. We show that the extremes of so-called physical observables are distributed according to the classical generalised Pareto distribution and derive explicit expressions for the scaling and the shape parameter. In particular, we derive that the shape parameter does not depend on the cho- sen observables, but only on the partial dimensions of the invariant measure on the stable, unstable, and neutral manifolds. The shape parameter is negative and is close to zero when high-dimensional systems are considered. This result agrees with what was derived recently using the generalized extreme value approach. Combining the results obtained using such physical observables and the properties of the extremes of distance observables, it is possible to derive estimates of the partial dimensions of the attractor along the stable and the unstable directions of the flow. Moreover, by writing the shape parameter in terms of moments of the extremes of the considered observable and by using linear response theory, we relate the sensitivity to perturbations of the shape parameter to the sensitivity of the moments, of the partial dimensions, and of the Kaplan–Yorke dimension of the attractor. Preliminary numer- ical investigations provide encouraging results on the applicability of the theory presented here. The results presented here do not apply for all combinations of Axiom A systems and observables, but the breakdown seems to be related to very special geometrical configurations.

The economic theory of the firm as a foundation for international business theory

The economic theory of the firm is central to the theory of the multinational enterprise. Recent literature on multinationals, however, makes only limited reference to the economic theory of the firm. Multinationals play an important role in coordinating the international division of labour through internal markets. The paper reviews the economic principles that underlie this view. Optimal internalisation equates marginal benefits and costs. The benefits of internalisation stem mainly from the difficulties of licensing proprietary knowledge, reflecting the view that MNEs possess an ‘ownership’ or ‘firm-specific’ advantage. The costs of internalisation, it is argued, reflect managerial capability, and in particular the capability to manage a large firm. The paper argues that management capability is a complement to ownership advantage. Ownership advantage determines the potential of the firm, and management capability governs the fulfilment of this potential through overcoming barriers to growth. The analysis is applied to a variety of issues, including out-sourcing, geographical dispersion of production, and regional specialisation in marketing.

GM food purchase intentions: linking the theory of planned behaviour with consumer trust and stated choice

After the “European” experience of BSE and further food safety crises consumer trust is playing an increasingly important role in political and marketing decision making. This also relates to the area of consumer acceptance of GM food. This paper integrates consumer trust with the theory of planned behavior and a stated choice model to gain a more complete picture of consumer decision making. Preliminary results indicate that when GM products offer practical benefits to consumers acceptance may increase considerably. Furthermore, both trust and perceived benefits contribute significantly to explaining the level of acceptance.

The missing pillar: the creativity theory of knowledge spillover entrepreneurship

Knowledge spillover theory of entrepreneurship and the prevailing theory of economic growth treat opportunities as endogenous and generally focus on opportunity recognition by entrepreneurs. New knowledge created endogenously results in knowledge spillovers enabling inventors and entrepreneurs to commercialize it. This article discusses that knowledge spillover entrepreneurship depends not only on ordinary human capital, but more importantly also on creativity embodied in creative individuals and diverse urban environments that attract creative classes. This might result in self-selection of creative individuals into entrepreneurship or enable entrepreneurs to recognize creativity and commercialize it. This creativity theory of knowledge spillover entrepreneurship is tested utilizing data on European cities.

The transaction cost economics theory of the family firm: family-based human asset specificity and the bifurcation bias

We develop a transaction cost economics theory of the family firm, building upon the concepts of family-based asset specificity, bounded rationality, and bounded reliability. We argue that the prosperity and survival of family firms depend on the absence of a dysfunctional bifurcation bias. The bifurcation bias is an expression of bounded reliability, reflected in the de facto asymmetric treatment of family vs. nonfamily assets (especially human assets). We propose that absence of bifurcation bias is critical to fostering reliability in family business functioning. Our study ends the unproductive divide between the agency and stewardship perspectives of the family firm, which offer conflicting accounts of this firm type's functioning. We show that the predictions of the agency and stewardship perspectives can be usefully reconciled when focusing on how family firms address the bifurcation bias or fail to do so.

On the observability of turbulent transport rates by Argo: supporting evidence from an inversion experiment

Although estimation of turbulent transport parameters using inverse methods is not new, there is little evaluation of the method in the literature. Here, it is shown that extended observation of the broad scale hydrography by Argo provides a path to improved estimates of regional turbulent transport rates. Results from a 20 year ocean state estimate produced with the ECCO v4 non-linear inverse modeling framework provide supporting evidence. Turbulent transport parameter maps are estimated under the constraints of fitting the extensive collection of Argo profiles collected through 2011. The adjusted parameters dramatically reduce misfits to in situ profiles as compared with earlier ECCO solutions. They also yield a clear reduction in the model drift away from observations over multi-century long simulations, both for assimilated variables (temperature and salinity) and independent variables (bio-geochemical tracers). Despite the minimal constraints imposed specifically on the estimated parameters, their geography is physically plausible and exhibits close connections with the upper ocean ocean stratification as observed by Argo. The estimated parameter adjustments furthermore have first order impacts on upper-ocean stratification and mixed layer depths over 20 years. These results identify the constraint of fitting Argo profiles as an effective observational basis for regional turbulent transport rates. Uncertainties and further improvements of the method are discussed.

The growth rate and dimension theory of beta-expansions

In a recent paper of Feng and Sidorov they show that for β∈(1,(1+5√)/2) the set of β-expansions grows exponentially for every x∈(0,1/(β−1)). In this paper we study this growth rate further. We also consider the set of β-expansions from a dimension theory perspective.

Toward a theory of semantic representation

We present an account of semantic representation that focuses on distinct types of information from which word meanings can be learned. In particular, we argue that there are at least two major types of information from which we learn word meanings. The first is what we call experiential information. This is data derived both from our sensory-motor interactions with the outside world, as well as from our experience of own inner states, particularly our emotions. The second type of information is language-based. In particular, it is derived from the general linguistic context in which words appear. The paper spells out this proposal, summarizes research supporting this view and presents new predictions emerging from this framework.

An example in Beurling's theory of generalised primes

In this paper we prove some connections between the growth of a function and its Mellin transform and apply these to study an explicit example in the theory of Beurling primes.

Biochemical characterization of serine transport in Leishmania (Leishmania) amazonensis

In addition to its role as a protein component in Leishmania, serine is also a precursor for the synthesis of both phosphatidylserine, which is a membrane molecule involved in parasite invasion and inactivation of macrophages, and sphingolipids, which are necessary for Leishmania to differentiate into its infective forms. We have characterized serine uptake in both promastigote and amastigote forms of Leishmania (Leishmania) amazonensis. In promastigotes, kinetic data show a single, saturable transport system, with a Km of 0.253 +/- 0.01 mM and a maximum velocity of 0.246 +/- 0.04 nmol/min per 107 cells. Serine transport increased linearly with temperature in the range from 20 degrees C to 45 degrees C, allowing the calculation of an activation energy of 7.09 kJ/mol. Alanine, cysteine, glycine, threonine, valine and ethanolamine competed with the substrate at a ten-fold excess concentration. Serine uptake was dependent on pH, with an optimum activity at pH 7.5. The characterization of the serine transport process in amastigotes revealed a transport system with a similar Km, energy of activation and pH response to that found in promastigotes, suggesting that the same transport system is active in both insect vector and mammalian host Leishmania stages. This could constitute an evolutionary mechanism that guarantees the provision of such an essential molecule during host change events, such as differentiation into amastigotes and macrophage invasion, as well as to ensure that the parasite maintains the infection in the mammalian host. (C) 2008 Elsevier B.V. All rights reserved.

A psychophysical and computational analysis of the spatio-temporal mechanisms underlying the flash-lag effect

Several accounts put forth to explain the flash-lag effect (FLE) rely mainly on either spatial or temporal mechanisms. Here we investigated the relationship between these mechanisms by psychophysical and theoretical approaches. In a first experiment we assessed the magnitudes of the FLE and temporal-order judgments performed under identical visual stimulation. The results were interpreted by means of simulations of an artificial neural network, that wits also employed to make predictions concerning the F LE. The model predicted that a spatio-temporal mislocalisation would emerge from two, continuous and abrupt-onset, moving stimuli. Additionally, a straightforward prediction of the model revealed that the magnitude of this mislocalisation should be task-dependent, increasing when the use of the abrupt-onset moving stimulus switches from a temporal marker only to both temporal and spatial markers. Our findings confirmed the model`s predictions and point to an indissoluble interplay between spatial facilitation and processing delays in the FLE.

Contributions to the theory of magnetorotational instability and waves in a rotating plasma

The one-fluid magnetohydrodynamic (MHD) theory of magnetorotational instability (MRI) in an ideal plasma is presented. The theory predicts the possibility of MRI for arbitrary 0, where 0 is the ratio of the plasma pressure to the magnetic field pressure. The kinetic theory of MRI in a collisionless plasma is developed. It is demonstrated that as in the ideal MHD, MRI can occur in such a plasma for arbitrary P. The mechanism of MRI is discussed; it is shown that the instability appears because of a perturbed parallel electric field. The electrodynamic description of MRI is formulated under the assumption that the dispersion relation is expressed in terms of the permittivity tensor; general properties of this tensor are analyzed. It is shown to be separated into the nonrotational and rotational parts. With this in mind, the first step for incorporation of MRI into the general theory of plasma instabilities is taken. The rotation effects on Alfven waves are considered.