Fear in horses

Fear is generally considered to be an undesirable emotional state that may reduce welfare, growth and reproductive performance in animals. Fear in horses is additionally problematic, because fear reactions can cause serious injury to both horse and human. Horses are primarily used for sports and leisure for a large number of children and young women. Unfortunately, horse riding ranks as one of the most dangerous sports in terms of the number and seriousness of accidents, and the ability of a horse to habituate to a range of otherwise frightening stimuli greatly increases safety in the horse-human relationship. However, there is a lack of research on fear reactions and no published research on basic habituation processes in horses. This licentiate project aimed to investigate the types of fear responses horses show towards novel stimuli acting on different senses, and to study how horses learn to be confident with an otherwise frightening stimulus using classical learning theory techniques. The experiments were conducted on two different groups of naïve stallions (n=24 and n=27). The first experiment showed that horses responded differently towards an olfactory stimulus compared to auditory and visual stimuli. The heart rate responses correlated between tests and probably reflected a non-differentiated activation of the sympathetic nervous system, while the behavioural responses were linked to the type of stimulus. The second experiment showed that gradual habituation was the most effective training method for horses to learn to react calmly to an otherwise frightening stimulus, compared to classic habituation and associative learning. Heart rate data revealed that horses may show physiological responses even when their behavioural response towards the stimulus has ceased. Choice of training method is likely to be especially important for the most fearful horses

On variational eigenvalue approximation of semidefinite operators

Eigenvalue problems for semidefinite operators with infinite dimensional kernels appear for instance in electromagnetics. Variational discretizations with edge elements have long been analyzed in terms of a discrete compactness property. As an alternative, we show here how the abstract theory can be developed in terms of a geometric property called the vanishing gap condition. This condition is shown to be equivalent to eigenvalue convergence and intermediate between two different discrete variants of Friedrichs estimates. Next we turn to a more practical means of checking these properties. We introduce a notion of compatible operator and show how the previous conditions are equivalent to the existence of such operators with various convergence properties. In particular the vanishing gap condition is shown to be equivalent to the existence of compatible operators satisfying an Aubin-Nitsche estimate. Finally we give examples demonstrating that the implications not shown to be equivalences, indeed are not.Comment: 26 page

Relaxing the Strict Exogeneity Assumption in a Dynamic Random Probit Model

This paper is relaxing the strict exogeneity assumption in a dynamic random probit model to allow for the possibility of feedback effects. We take an MLE approach and specify a marginal distribution for the not strictly exogenous variable in question. Using a log-likelihood function similar to Wooldridge (2000) we propose two estimation strategies depending on what the object of interest is. We show that the parameters can be estimated using either quadrature or simulated maximum likelihood if all we are interested in is the parameters of the model. Subsequently average partial effects can be estimated. However, if we are more interested in knowing the average partial effects and less interested in the parameter estimates themselves, then it is useful to considering the problem as a method of moment problem rather than a MLE. This will allow an easy estimation of the average partial effect and in particular the variance of the APE such that statistical inference is possible. The insight is applied to a large Danish register data set on employment transitions to address the question of true state dependence in unemployment transitions. Moreover, we rise the important question, that a major part of the results in the state dependence literature could be invalid due to ignoring violations of the strict exogeneity assumption.unobserved heterogeneity, dynamic random probit, feedback effects, initial condition, state dependence

Value Creation and Profit Optimization

The present paper develops a basic framework for evaluating and optimizing profits in a business operation. In developing a business we are often faced with an infinity of choices ranging from what products or services to sell and what customers to target to how to structure and manage the organization. To support the decision-making process a semi- quantitative dimension is here added to the traditional strategic scenario planning. It consists of a general-purpose seven-step evaluation process: (1) The starting point is a list of strategic options, as they may have been identified during conventional strategic planning. (2-3) The next steps are to identify who will influence the value creation process, and what value drivers each of them use to influence it. (4) For customers representative of different segments we can evaluate the value to the customer, the risk to the customer and the relative market power between buyer and seller. The paper explains how this can be related to the market price that each of these customers is likely to be willing to pay. (5) While the income is critical, so it the cost: the following step is to analyze the cost structure and understand how it scales with market size. (6) By combining the results from the two previous steps it is possible to find the optimal profit as a function of volume, value drivers and the other parameters. (7) In the final step the strategic implications of the various options are integrated with other knowledge to form the basis for selecting a winning business strategy. An example of a yet-to-be consumer product is used to illustrate the process.cost, customer specific cost, market power, pricing, profit optimization, profits, radical innovation, risk discount, strategic scenario planning, value chain, value creation, value drivers, value net

A test complex for Gorensteinness

Let $R$ be a commutative noetherian ring with a dualizing complex. By recent work of Iyengar and Krause, the difference between the category of acyclic complexes and its subcategory of totally acyclic complexes measures how far $R$ is from being Gorenstein. In particular, $R$ is Gorenstein if and only if every acyclic complex is totally acyclic. In this note we exhibit a specific acyclic complex with the property that it is totally acyclic if and only if $R$ is Gorenstein.Comment: Final version, 8 pp. To appear in Proc. Amer. Math. Soc. Also available from the authors' homepages at http://www.math.unl.edu/~lchristensen3/ and at http://www.math.utah.edu/~oveliche

Effect of control surface mass unbalance on the stability of a closed-loop active control system

The effects on stability of inertial forces arising from closed-loop activation of mass-unbalanced control surfaces are studied analytically using inertial energy approach, similar to the aerodynamic energy approach used for flutter suppression. The limitations of a single control surface like a leading-edge (LE) control or a trailing-edge (TE) control are demonstrated and compared to the superior combined LE-TE mass unbalanced system. It is shown that a spanwise section for sensor location can be determined which ensures minimum sensitivity to the mode shapes of the aircraft. It is shown that an LE control exhibits compatibility between inertial stabilization and aerodynamic stabilization, and that a TE control lacks such compatibility. The results of the present work should prove valuable, both for the purpose of flutter suppression using mass unbalanced control surfaces, or for the stabilization of structural modes of large space structures by means of inertial forces

Gorenstein dimension of modules over homomorphisms

Given a homomorphism of commutative noetherian rings R --> S and an S-module N, it is proved that the Gorenstein flat dimension of N over R, when finite, may be computed locally over S. When, in addition, the homomorphism is local and N is finitely generated over S, the Gorenstein flat dimension equals sup{m | Tor^R_m(E,N) \noteq 0} where E is the injective hull of the residue field of R. This result is analogous to a theorem of Andr\'e on flat dimension.Comment: 14 pp. To appear in J. Pure Appl. Algebra. Also available from http://www.math.unl.edu/~lchristensen3/index.htm