Abstract

Abstract

Abstract

Abstract
The class of subspace system identification algorithms is used here to derive new identification algorithms for 2-D causal, recursive, and separable-in-denominator (CRSD) state space systems in the Roesser form. The algorithms take a known deterministic input-output pair of 2-D signals and compute the system order (n) and system parameter matrices {A, B, C, D}. Since the CRSD model can be treated as two 1-D systems, the proposed algorithms first separate the vertical component from the state and output equations and then formulate a set of 1-D horizontal subspace equations. The solution to the horizontal subproblem contains all the information necessary to compute (n) and {A, B, C, D}. Four algorithms are presented for the identification of CRSD models directly from input-output data: an intersection algorithm, (N4SID), (MOESP), and (CCA). The intersection algorithm is distinguished from the rest in that it computes the state sequences, as well as the system parameters, whereas N4SID, MOESP, and CCA differ primarily in the way they compute the system parameter matrices {A1, C1}. The advantage of the intersection algorithm is that the identified model is in balanced coordinates, thus ideally suited for 2-D model reduction. However, it is computationally more expensive than the other algorithms. A comparison of all algorithms is presented.

Abstract
Despite the large number of studies on the phenomenon of imposex, the mechanism underlying the abnormal growth of male sexual characters onto females in numerous gastropod species is yet to be fully elucidated. Although several hypotheses have been raised over the years, a convincing body of evidence indicates that tributyltin-induced imposex involves the abnormal modulation of the retinoid X receptor (RXR). Here, we investigate the RXR gene transcription at different timings and tissues upon exposure to environmentally relevant concentrations of tributyltin (TOT) (100 ng Sn/L TBT) in both genders of the imposex susceptible gastropod Nucella lapillus. RXR gene transcription was determined at two time-points (i.e., before and after imposex initiation) by quantitative Real Time PCR in potential target tissues: the central nervous system (CNS), penis/penis forming area (PFA), gonads and digestive gland. TBT-exposure altered transcription of RXR gene in a tissue and sex specific manner. In the CNS, a significant down-regulation was observed in females both before and after imposex initiation (P <= 0.01 and P <= 0.05, respectively). A similar trend was observed in male CNS at the first time-point, although differences between control and the TBT-exposed group were just above significance (P=0.059). The penis/PFA showed no differences in transcription of RXR gene between control and TBT exposed female snails before imposex induction, or before and after imposex initiation for males. However, male penis showed higher transcription of RXR gene in comparison to the PFA of females. After imposex has been induced, a significant (P <= 0.001) increase in transcription of RXR gene was observed in penis of females with vas deference sequence index (VDS) levels of 3-4 in comparison with the PFA of both control and imposex females with VDS 1-2. At advanced stages of imposex, females displayed RXR transcription patterns in penis identical to those of males, which points to a functional role of RXR in the penis of both genders. In the other tissues, gonads and digestive gland. RXR gene transcription was not affected by TBT, at any of the analysed time-points. These patterns of RXR gene transcription upon TOT exposure highlight the pivotal involvement of the CNS in the mechanism of imposex induction. We integrate the results in a conceptual model, and discuss the central role of RXR and the retinoic acid signalling pathways in imposex and male genitalia formation in gastropods.

Abstract
FP7 ICT4Depression project aims at providing a set of tools to,further improve both patient outcome and increase of access to treatment of the patients suffering from major depression. This article describes the Information Systems (IS) architecture used in the project. ICT4Depression uses a service oriented architecture as means of bringing together different kinds of information concerning the patient, the therapeutic modules he is advised to follow and the sensors used to assess his status.