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Publicações

Publicações por LIAAD

2006

Separating sequential equilibrium in a Bayesian international duopoly

Autores
Pinto, AA; Ferreira, FA; Ferreira, F;

Publicação
2006 IEEE International Conference on Computational Cybernetics, ICCC

Abstract
We consider two Cournot firms, one located in the home country and the other in the foreign country, producing substitute goods for consumption in a third country. We suppose that neither the home government nor the foreign firm know the costs of the home firm, while the foreign firm cost is common knowledge. We determine the separating sequential equilibrium outputs.

2006

Regulatory T cell adjustment of quorum growth thresholds and the control of local immune responses

Autores
Burroughs, NJ; de Oliveira, BMPM; Pinto, AA;

Publicação
JOURNAL OF THEORETICAL BIOLOGY

Abstract
The consequences of regulatory T cell (Treg) inhibition of interleukine 2 secretion is examined by mathematical modelling. We demonstrate that cytokine dependent growth exhibits a quorum T cell population threshold that determines if immune responses develop on activation. Secretion inhibition manipulates the growth dynamics and effectively increases the quorum threshold, i.e. to develop immune responses a higher number of T cells need to be activated. Thus Treg induced secretion inhibition can provide a mechanism for tissue specific regulation of the balance between suppression (control) and immune responses, a balance that can be varied at the local tissue level through the regulation of the local active Treg population size. However, nonspecific inhibition is prone to escape of initially controlled autoimmune T cells through cross reactivity to pathogens and bystander proliferation on unrelated immune responses.

2006

Stackelberg leadership with demand uncertainty in a differentiated duopoly

Autores
Ferreira, F; Ferreira, F; Pinto, A;

Publicação
PROCEEDINGS OF THE 25TH IASTED INTERNATIONAL CONFERENCE ON MODELLING, IDENTIFICATION, AND CONTROL

Abstract
On a symmetric differentiated Stackelberg duopoly model in which there is asymmetric demand information owned by leading and follower firms, we show that the leading firm does not necessarily have advantage over the following one. The reason for this is that the second mover can adjust its output level after observing the realized demand, while the first mover chooses its output level only with the knowledge of demand distribution.

2006

The circle and the solenoid

Autores
Pinto, AA; Sullivan, D;

Publicação
DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS

Abstract
In the paper, we discuss two questions about degree d smooth expanding circle maps, with d >= 2. (i) We characterize the sequences of asymptotic length ratios which occur for systems with Holder continuous derivative. The sequences of asymptotic length ratios are precisely those given by a positive Holder continuous function s (solenoid function) on the Cantor set C of d-adic integers satisfying a functional equation called the matching condition. In the case of the 2-adic integer Cantor set, the functional equation is s(2x + 1) = s(x)/s(2x) 1 + 1s(2x-1) -1. We also present a one-to-one correspondence between solenoid functions and affine classes of exponentially fast d-adic tilings of the real line that are fixed points of the d-amalgamation operator. (ii) We calculate the precise maximum possible level of smoothness for a representative of the system, up to diffeomorphic conjugacy, in terms of the functions s and cr(x) = (1 + s(x))/(1 + (s(x + 1))(-1)). For example, in the Lipschitz structure on C determined by s, the maximum smoothness is C1+alpha for 0 < alpha <= 1 if and only if s is alpha-Holder continuous. The maximum smoothness is C2+alpha for 0 < alpha <= 1 if and only if cr is (1 + alpha)-Holder. A curious connection with Mostow type rigidity is provided by the fact that s must be constant if it is alpha-Holder for alpha > 1.

2006

Goodness-of-fit methods for the bipolar Watson distribution defined on the hypersphere (vol 76, pg 142, 2006)

Autores
Figueiredo, A; Gomes, P;

Publicação
STATISTICS & PROBABILITY LETTERS

Abstract

2006

Goodness-of-fit methods for the bipolar Watson distribution defined on the hypersphere

Autores
Figueiredo, A; Gomes, P;

Publicação
STATISTICS & PROBABILITY LETTERS

Abstract
The Watson distribution is frequently used for modeling axial data. In this paper, we present goodness-of-fit methods for the bipolar Watson distribution defined on the hypersphere. We analyze by simulation some questions concerning these tests: the adequacy of the asymptotic chi-square distribution used in the tests and the adequacy of using the tabulated critical values for the Kolmogorov-Smirnov statistic when the parameters of the bipolar Watson distribution are unknown. We illustrate these techniques with simulated data from this distribution.

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