Timing verification in transaction modeling

Les systèmes Matériels/Logiciels deviennent indispensables dans tous les aspects de la vie quotidienne. La présence croissante de ces systèmes dans les différents produits et services incite à trouver des méthodes pour les développer efficacement. Mais une conception efficace de ces systèmes est limitée par plusieurs facteurs, certains d'entre eux sont: la complexité croissante des applications, une augmentation de la densité d'intégration, la nature hétérogène des produits et services, la diminution de temps d’accès au marché. Une modélisation transactionnelle (TLM) est considérée comme un paradigme prometteur permettant de gérer la complexité de conception et fournissant des moyens d’exploration et de validation d'alternatives de conception à des niveaux d’abstraction élevés. Cette recherche propose une méthodologie d’expression de temps dans TLM basée sur une analyse de contraintes temporelles. Nous proposons d'utiliser une combinaison de deux paradigmes de développement pour accélérer la conception: le TLM d'une part et une méthodologie d’expression de temps entre différentes transactions d’autre part. Cette synergie nous permet de combiner dans un seul environnement des méthodes de simulation performantes et des méthodes analytiques formelles. Nous avons proposé un nouvel algorithme de vérification temporelle basé sur la procédure de linéarisation des contraintes de type min/max et une technique d'optimisation afin d'améliorer l'efficacité de l'algorithme. Nous avons complété la description mathématique de tous les types de contraintes présentées dans la littérature. Nous avons développé des méthodes d'exploration et raffinement de système de communication qui nous a permis d'utiliser les algorithmes de vérification temporelle à différents niveaux TLM. Comme il existe plusieurs définitions du TLM, dans le cadre de notre recherche, nous avons défini une méthodologie de spécification et simulation pour des systèmes Matériel/Logiciel basée sur le paradigme de TLM. Dans cette méthodologie plusieurs concepts de modélisation peuvent être considérés séparément. Basée sur l'utilisation des technologies modernes de génie logiciel telles que XML, XSLT, XSD, la programmation orientée objet et plusieurs autres fournies par l’environnement .Net, la méthodologie proposée présente une approche qui rend possible une réutilisation des modèles intermédiaires afin de faire face à la contrainte de temps d’accès au marché. Elle fournit une approche générale dans la modélisation du système qui sépare les différents aspects de conception tels que des modèles de calculs utilisés pour décrire le système à des niveaux d’abstraction multiples. En conséquence, dans le modèle du système nous pouvons clairement identifier la fonctionnalité du système sans les détails reliés aux plateformes de développement et ceci mènera à améliorer la "portabilité" du modèle d'application.

Timing pubertaire et adaptation psychosociale à l'adolescence : le rôle des relations interpersonnelles et des vulnérabilités individuelles

Cette thèse avait pour objectif d’examiner les liens longitudinaux entre le timing pubertaire et les problèmes de comportement intériorisés et extériorisés à l’adolescence, soit les problèmes de conduite et les symptômes dépressifs. Guidé par la perspective théorique biosociale et le modèle de vulnérabilité-stress, le rôle modérateur de l’environnement social et des vulnérabilités personnelles préexistantes était également évalué. Les hypothèses initiales étaient qu’un timing pubertaire précoce ou déviant de la norme (précoce et tardif) serait associé à des niveaux plus élevés de problèmes de conduite et de symptômes dépressifs, mais que ce lien serait accentué dans des contextes sociaux et interpersonnels plus à risque et en présence de vulnérabilités individuelles chez les adolescents. Pour vérifier ces hypothèses, des données provenant de l’Enquête Longitudinale Nationale sur les Enfants et les Jeunes (ELNEJ) ont été analysées. Gérée par Statistique Canada, l’ELNEJ est une enquête prospective biennale comportant différents échantillons représentatifs d’enfants et d’adolescents canadiens. Les mesures utilisées dans cette thèse ont été collectées à différents cycles de l’enquête, soit à 10–11 ans, 12–13 ans, 14–15 ans et 16–17 ans, directement auprès des adolescents et de leurs parents par le biais de questionnaires et d’entrevues. Le premier article de la thèse a vérifié si l’interaction entre le timing pubertaire et des caractéristiques du contexte social des pairs (c.-à-d. l’affiliation avec des pairs déviants et l’implication amoureuse en début d’adolescence) prédisait la présentation de problèmes de conduite avec et sans agressivité physique à l’adolescence. Les résultats ont montré que le contexte social des pairs modérait l’association entre le timing pubertaire et les problèmes de conduite. Une interaction significative entre le timing pubertaire et l’affiliation à des pairs déviants a indiqué qu’une puberté plus précoce était associée à des fréquences plus élevées de problèmes de conduite agressive seulement chez les filles et les garçons qui fréquentaient des pairs déviants. Autrement dit, parmi les adolescents s’affiliant à des pairs déviants en début d’adolescence, les adolescents pubères précoces tendaient à présenter plus de problèmes de conduite agressive deux ans plus tard, en comparaison à leurs pairs pubères dans les temps moyens ou tardifs. Une seconde interaction significative obtenue chez les filles a montré que la puberté plus précoce était prédictrice des problèmes de conduite non-agressive seulement en présence d’un engagement amoureux en début d’adolescence. En effet, dans un contexte d’implication amoureuse, les filles pubères précoces présentaient plus de problèmes de conduite non-agressive que leurs pairs. Le deuxième article de la thèse avait pour objectif d’évaluer le rôle modérateur des vulnérabilités individuelles à la dépression (présence de symptômes intériorisés à la fin de l’enfance), du contexte social des pairs (affiliation à des pairs déviants, expérience amoureuse précoce et perception de popularité auprès des pairs) et des relations parent-adolescent (perception de rejet de la part des parents) dans l’association longitudinale entre le timing pubertaire et les symptômes dépressifs en fin d’adolescence. Chez les filles, une interaction triple a révélé que la puberté plus précoce était liée à davantage de symptômes dépressifs, mais seulement chez celles qui présentaient des symptômes intériorisés à la fin de l’enfance et une implication amoureuse précoce. Chez les garçons, un effet curvilinéaire du timing pubertaire a été observé alors que la puberté précoce et tardive était associée à plus de symptômes dépressifs, mais seulement chez les garçons qui manifestaient des symptômes intériorisés à la fin de l’enfance. La puberté plus précoce était aussi liée à des niveaux plus élevés de symptômes dépressifs en présence d’affiliation à des pairs déviants (garçons) et de perceptions plus importantes de rejet parental (filles et garçons). En somme, la mise en évidence d’interactions significatives entre le timing pubertaire, les caractéristiques de l’environnement social et les vulnérabilités individuelles suscite différentes réflexions au plan théorique et pratique. Tout d’abord, les résultats suggèrent que le timing pubertaire en lui-même ne paraît pas représenter un facteur de risque généralisé des problèmes de comportement intériorisés et extériorisés à l’adolescence. Plus particulièrement, ces résultats soulignent l’importance de considérer l’environnement social et les facteurs de risque individuels préexistants afin de mieux comprendre l’effet de la transition pubertaire sur l’adaptation psychosociale des adolescents.

Incremental Verification of Timing Constraints for Real-Time Systems

Testing constraints for real-time systems are usually verified through the satisfiability of propositional formulae. In this paper, we propose an alternative where the verification of timing constraints can be done by counting the number of truth assignments instead of boolean satisfiability. This number can also tell us how “far away” is a given specification from satisfying its safety assertion. Furthermore, specifications and safety assertions are often modified in an incremental fashion, where problematic bugs are fixed one at a time. To support this development, we propose an incremental algorithm for counting satisfiability. Our proposed incremental algorithm is optimal as no unnecessary nodes are created during each counting. This works for the class of path RTL. To illustrate this application, we show how incremental satisfiability counting can be applied to a well-known rail-road crossing example, particularly when its specification is still being refined.

Fiscal rules: timing is everything. Bruegel Policy Brief 2012/02, September 2012

The strengthening of the European Union’s fiscal rules with the approval of the so-called ‘six-pack’, and the parallel worsening of economic conditions in Europe, re-opened the debate about the relationship between fiscal discipline and growth. Influential voices have argued against the EU’s perceived obsession with fiscal discipline, which risks being self-defeating in bad times. However, EU fiscal rules are not as rigid as commonly thought, but represent a sophisticated system of surveillance and ex-post control that provides sufficient room for manoeuvre under exceptional circumstances.

The timing of Quaternary calcrete development in semi-arid southeast Spain: Investigating the role of climate on calcrete genesis

Quaternary-aged calcrete horizons are common weathering products in arid and semi-arid regions. It is, however, unclear how calcrete forming processes respond to the major oscillations in climate that occur over the Quaternary period. This paper presents a U-series-based calcrete age database from the Sorbas basin, southeast Spain. The study constructs an age frequency distribution of these ages which is consequently compared to a range of palaeoenvironmental records from the Mediterranean. The age distribution presented here suggests that the formation of pedogenic calcrete horizons in the Sorbas basin primarily occurs during 'warm' isotope stages (MIS 1 and 5), with very few calcrete ages occurring during cold glacial/stadial stages (MIS 2, 3 and 4). It is suggested that this is a function of the environments that existed during 'warm' isotope stages being more conducive to calcrete development than those that existed during cold climate episodes. In a semi-arid region such as the Sorbas basin it is likely that increased aridity during glacial stages, coupled with reduced vegetation and accelerated landscape instability, was crucial in reducing rates of calcrete formation. In a semi-arid region such as southeast Spain, calcrete formation during the Quaternary, therefore, oscillates with climate change but is primarily a "warm" episode phenomenon. It is suggested that further studies are required to see how calcrete genesis responds to environmental change in more humid parts of the Mediterranean. (C) 2009 Elsevier B.V. All rights reserved.

Impulsiveness as a timing disturbance: neurocognitive abnormalities in attention-deficit hyperactivity disorder during temporal processes and normalization with methylphenidate.

We argue that impulsiveness is characterized by compromised timing functions such as premature motor timing, decreased tolerance to delays, poor temporal foresight and steeper temporal discounting. A model illustration for the association between impulsiveness and timing deficits is the impulsiveness disorder of attention-deficit hyperactivity disorder (ADHD). Children with ADHD have deficits in timing processes of several temporal domains and the neural substrates of these compromised timing functions are strikingly similar to the neuropathology of ADHD. We review our published and present novel functional magnetic resonance imaging data to demonstrate that ADHD children show dysfunctions in key timing regions of prefrontal, cingulate, striatal and cerebellar location during temporal processes of several time domains including time discrimination of milliseconds, motor timing to seconds and temporal discounting of longer time intervals. Given that impulsiveness, timing abnormalities and more specifically ADHD have been related to dopamine dysregulation, we tested for and demonstrated a normalization effect of all brain dysfunctions in ADHD children during time discrimination with the dopamine agonist and treatment of choice, methylphenidate. This review together with the new empirical findings demonstrates that neurocognitive dysfunctions in temporal processes are crucial to the impulsiveness disorder of ADHD and provides first evidence for normalization with a dopamine reuptake inhibitor.

A GCM study of the influence of equatorial winds on the timing of sudden stratospheric warmings

A full troposphere-stratosphere-mesosphere global circulation model is used in a set of idealised experiments to investigate the sensitivity of the Northern Hemisphere winter stratospheric flow to improvements in the equatorial zonal winds. The model shows significant sensitivity to variability in the upper equatorial stratosphere, the imposition of SAO and QBO like variability in this region advances the timing of midwinter sudden warmings by about one month. Perturbations to the lower equatorial stratosphere are mainly found to influence early winter polar variability. These results suggest that it is important to pay attention to the capability of models to simulate realistic variability in the upper equatorial stratosphere.

Effect of type and timing of oil supplements to sows during pregnancy on the growth performance and endocrine profile of low and normal birth weight offspring

Eighty-eight multiparous sows were used to evaluate whether type and timing of oil supplementation during gestation influences the incidence of low birth weight (LBW). Sows were allocated (eight per treatment) commercial sow pellets (3 kg/d; control diet) or an experimental diet consisting of control diet plus 10 % extra energy in the form of excess pellets, palm oil, olive oil (OO), sunflower oil (SO) or fish oil; experimental diets were fed during either the first half (G1) or second half (G2) of gestation. Growth performance and endocrine profile of LBW ( < 1·09 kg) and normal birth weight (NBW; 1·46–1·64 kg) offspring were compared. Maternal dietary supplementation altered the distribution curve for piglet birth weight. SOG1 sows had a greater proportion of LBW piglets (P < 0·05), whilst it was reduced in the OOG1 group (P < 0·05). Growth rate of LBW piglets was lower compared with their NBW siblings (P < 0·05) when dietary supplementation was offered in G2 but were similar for G1. At birth, LBW offspring of supplemented animals possessed more fat compared with the control group (P < 0·05); LBW offspring of control animals exhibited a more rapid decline in fat free mass/kg prior to weaning. Plasma metabolites and insulin concentrations were influenced by maternal diet and birth weight. In conclusion, maternal dietary supplementation altered the distribution of piglet birth weights and improved the energy status of LBW piglets. Supplementation with MUFA during G1 reduced the incidence of LBW, whereas PUFA had the reverse effect.

The timing of eukaryotic evolution: Does a relaxed molecular clock reconcile proteins and fossils?

The use of nucleotide and amino acid sequences allows improved understanding of the timing of evolutionary events of life on earth. Molecular estimates of divergence times are, however, controversial and are generally much more ancient than suggested by the fossil record. The limited number of genes and species explored and pervasive variations in evolutionary rates are the most likely sources of such discrepancies. Here we compared concatenated amino acid sequences of 129 proteins from 36 eukaryotes to determine the divergence times of several major clades, including animals, fungi, plants, and various protists. Due to significant variations in their evolutionary rates, and to handle the uncertainty of the fossil record, we used a Bayesian relaxed molecular clock simultaneously calibrated by six paleontological constraints. We show that, according to 95% credibility intervals, the eukaryotic kingdoms diversified 950-1,259 million years ago (Mya), animals diverged from choanoflagellates 761-957 Mya, and the debated age of the split between protostomes and deuterostomes occurred 642-761 Mya. The divergence times appeared to be robust with respect to prior assumptions and paleontological calibrations. Interestingly, these relaxed clock time estimates are much more recent than those obtained under the assumption of a global molecular clock, yet bilaterian diversification appears to be approximate to100 million years more ancient than the Cambrian boundary.

Timing and the holding periods of institutional real estate

Literature on investors' holding periods for securities suggests that high transaction costs are associated with longer holding periods. Return volatility, by contrast, is associated with shorter holding periods. In real estate, high transaction costs and illiquidity imply longer holding periods. Research on depreciation and obsolescence suggests that there might be an optimal holding period. Sales rates and holding periods for U.K. institutional real estate are analyzed, using a proportional hazards model, over an 18-year period. The results show longer holding periods than those claimed by investors, with marked differences by type of property and over time. The results shed light on investor behavior.

Expressive versus receptive language skills in specific reading disorder

Despite ample research into the language skills of children with specific reading disorder no studies so far have investigated whether there may be a difference between expressive and receptive language skills in this population. Yet, neuro-anatomical models would predict that children who have specific reading disorder which is not associated with movement or attention difficulties, would have lower receptive language skills than expressive. This study investigates the difference between expressive and receptive language skills in a sample of 17 children with specific reading difficulty aged between 7 and 12 years. They were administered a battery of two receptive and two expressive language measures. The results showed that as the neuro-anatomical model would predict, the children scored significantly lower on tests of receptive than on tests of expressive language skills.

The effect of cleft lip and palate, and the timing of lip repair on mother-infant interactions and infant development

Background: Children with cleft lip and palate are at risk for psychological problems. Difficulties in mother-child interactions may be relevant, and could be affected by the timing of lip repair. Method: We assessed cognitive development, behaviour problems, and attachment in 94 infants with cleft lip (with and without cleft palate) and 96 non-affected control infants at 18 months; mother-infant interactions were assessed at two, six and 12 months. Index infants received either 'early', neonatal, lip repair, or 'late' repair (3-4 months). Results: Index infants did not differ from controls on measures of behaviour problems or attachment, regardless of timing of lip repair; however, infants having late lip repair performed worse on the Bayley Scales of Mental Development; the cognitive development of early repair infants was not impaired. Difficulties in early mother-infant interactions mediated the effects of late lip repair on infant cognitive outcome. Conclusions: Early interaction difficulties between mothers and infants having late repair of cleft lip are associated with poor cognitive functioning at 18 months. Interventions to facilitate mother-infant interactions prior to surgical lip repair should be explored.

Interceptive timing: prior knowledge matters

Fast interceptive actions, such as catching a ball, rely upon accurate and precise information from vision. Recent models rely on flexible combinations of visual angle and its rate of expansion of which the tau parameter is a specific case. When an object approaches an observer, however, its trajectory may introduce bias into tau-like parameters that render these computations unacceptable as the sole source of information for actions. Here we show that observer knowledge of object size influences their action timing, and known size combined with image expansion simplifies the computations required to make interceptive actions and provides a route for experience to influence interceptive action.

Infant Attachment Security and the Timing of Puberty: Testing an Evolutionary Hypothesis

Life-history theories of the early programming of human reproductive strategy stipulate that early rearing experience, including that reflected in infant-parent attachment security, regulates psychological, behavioral, and reproductive development. We tested the hypothesis that infant attachment insecurity, compared with infant attachment security, at the age of 15 months predicts earlier pubertal maturation. Focusing on 373 White females enrolled in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development, we gathered data from annual physical exams from the ages of 9½ years to 15½ years and from self-reported age of menarche. Results revealed that individuals who had been insecure infants initiated and completed pubertal development earlier and had an earlier age of menarche compared with individuals who had been secure infants, even after accounting for age of menarche in the infants’ mothers. These results support a conditional-adaptational view of individual differences in attachment security and raise questions about the biological mechanisms responsible for the attachment effects we discerned.

Valuation accuracy: reconciling the timing of the valuation and sale

Carsberg (2002) suggested that the periodic valuation accuracy studies undertaken by, amongst others, IPD/Drivers Jonas (2003) should be undertaken every year and be sponsored by the RICS, which acts as the self-regulating body for valuations in the UK. This paper does not address the wider issues concerning the nature of properties which are sold and whether the sale prices are influenced by prior valuations, but considers solely the technical issues concerning the timing of the valuation and sales data. This study uses valuations and sales data from the Investment Property Databank UK Monthly Index to attempt to identify the date that sale data is divulged to valuers. This information will inform accuracy studies that use a cut-off date as to the closeness of valuations to sales completion date as a yardstick for excluding data from the analysis. It will also, assuming valuers are informed quickly of any agreed sales, help to determine the actual sale agreed date rather than the completion date, which includes a period of due diligence between when the sale is agreed and its completion. Valuations should be updated to this date, rather than the formal completion date, if a reliable measure of valuation accuracy is to be determined. An accuracy study is then undertaken using a variety of updating periods and the differences between the results are examined. The paper concludes that the sale only becomes known to valuers in the month prior to the sale taking place and that this assumes either that sales due diligence procedures are shortening or valuers are not told quickly of agreed sale prices. Studies that adopt a four-month cut-off date for any valuations compared to sales completion dates are over cautious, and this could be reduced to two months without compromising the data.