Modeling Longevity Risk using Extreme Value Theory: An Empirical Investigation using Portuguese and Spanish Population Data

Extreme value theory (EVT) provides a framework to formalize the study of behaviour in the tails of a distribution. In this paper we use EVT to model the statistical behaviour of mortality rates over a given high threshold age and to estimate the significance of rare longevity risk in a given population. We adopt a piecewise approach in estimating the optimal threshold age using an iterative algorithm of maximum likelihood estimation.that statistically determines the cut-off between the central (Gompertz) part of the distribution and the upper tail modelled using the generalized Pareto distribution. The model is empirically tested using the most recent period mortality data for the total, male and female populations of Portugal and Spain. We use some classical results from EVT to estimate the evolution of the theoretical maximum life span over time and to derive confidence intervals for the central estimates. We then use time series methods to forecast the highest attained age. We observe a good fit of the model in all populations and subperiods analysed and on the whole life span considered. We estimate an increase in the theoretical maximum life span over time for all populations, more significant in the male subpopulations

An Overview of Transfer Conditions: Exploring Latino Community College Students in Texas

This paper begins exploring the transfer conditions for Latino community college students in Texas. We provide an overview of the high school schooling conditions for Latinos; the experiences of Latinos in the community college; and some models that can increase the transfer and graduation rates for Latina/o community college students.Educatio

Session summary: Language abstractions

© Real Sáez, J.| ACM, 2015. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in Adda Letters, http://dx.doi.org/10.1145/2870544.2870558Summary of discussion and conclusions of the IRTAW group around language abstractions.Wellings, A.; Real Sáez, JV. (2015). Session summary: Language abstractions. Ada Letters. 35(1):102-104. doi:10.1145/2870544.2870558S102104351P. Bernardi. Incorporating Cyclic Task Behaviour into Ada Tasks. Ada Letters, This issue, 2015.J. Real and A. Crespo. Incorporating Operating Modes to an Ada Real-Time Framework. Ada Letters, 30(1):73--85, April 2010.S. Sáez, J. Real, and A. Crespo. Implementation of Timing-Event Afinities in Ada/Linux. Ada Letters, This issue, 2015.S. Sáez, S. Terrasa, and A. Crespo. A Real-Time Framework for Multiprocessor Platforms Using Ada 2012. In S. Romanovsky and T. Vardanega, editors, 16th International Conference on Reliable Software technologies -- Ada-Europe 2011, volume 6652. Springer, June 2011.A. Wellings and A. Burns. Interrupts, Timing Events and Dispatching Domains. Ada Letters, This issue, 2015.A. J. Wellings and A. Burns. A Framework for Real-Time Utilities for Ada 2005. Ada Letters, XXVII(2), August 2007

Deferred and atomic setting of scheduling attributes for ada

© Sáez Barona, S.; Real Sáez, J.; Crespo, A. | ACM, 2015. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in Adda Letters, http://dx.doi.org/10.1145/2552999.2553010Deferred setting of scheduling attributes refers to a single operation that sets a new value for a scheduling attribute of a task at some future time. Although deferred setting of scheduling attributes is possible in Ada 2012, it is in a rather limited way: only deadline or CPU can be changed deferredly, either at a specified time or when the task is released from a suspension object. And only one of those two attributes at a time. Other scheduling attributes such as priority cannot have deferred setting by means of a single operation. This would be a convenient feature to have for schemes such as job partitioning, task splitting, or mode changes. Another issue is the absence of operations for atomically changing several parameters at a time, which would avoid scheduling issues specially on multiprocessors. In this paper we explore a proposal aimed at correcting these two drawbacks. On one hand, we want to be able to change more attributes, not only deadlines, deferredly or immediately. On the other hand, we want to atomically change (now or later) a set of attributes, thereby avoiding scheduling artifacts that arise from sequentially changing several attributes, specially when the CPU is one of them. Rather than providing a number of library operations for postponing the setting of a variety of scheduling attributes, we propose to encapsulate the scheduling attributes of each task i n a single t agged type that can be extended with more attributes for specific applications if neededSáez Barona, S.; Real Sáez, JV.; Crespo, A. (2013). Deferred and atomic setting of scheduling attributes for ada. Ada Letters. 33(2):97-108. doi:10.1145/2552999.2553010S9710833

Desarrollo de sistema de navegación de robots basado en adquisición óptica

Este Trabajo Fin de Grado propone un nuevo sistema de localización en tiempo real sin precisar del uso de gps o balizas. La idea de este proyecto se basa en la patente 2566427, en la que se demuestra cómo es posible posicionar un dispositivo en una superficie heterogénea con la previa elaboración de un mapa mediante un barrido del área implicada. Para ello se ha construido un robot móvil a partir de una Raspberry Pi, propulsado por dos servomotores y manejado mediante control remoto, capaz de identificar las coordenadas en las que se encuentra sobre un área escaneada con la ayuda de una cámara. Se trata de un sistema innovador, puesto que se ayuda exclusivamente de un sensor óptico, evitando el uso de mediciones láseres o detectores de objetos como sí utilizan otros dispositivos del mercado. El prototipo construido es una muestra a pequeña escala del alcance de ésta premisa, dado que a pesar del reducido tamaño tanto del móvil como del mapa elaborado para las pruebas, el algoritmo codificado podría incorporarse a vehículos más robustos o incluso drones. El objetivo de este sistema es lograr obtener información sobre la situación de un robot en áreas con acceso restringido o circunstancias desfavorables, en las cuales los sistemas de posicionamiento existentes en la actualidad no funcionarían. Algunas de las situaciones en las que podría verse el potencial de este vehículo sería en la localización dentro de edificaciones o en zonas en las que existan inhibidores de señal

Ravenscar Support for Time-Triggered Scheduling

[EN] This position paper follows from a previous proposal to integrate a time-triggered scheduler in a prioritybased, preemptive scheduler such as that supported by Ada¿s task dispatching policy FIFO Within Priorities . The resulting combined scheduling carries the advantages of both time-triggered and priority-based scheduling, and helps mitigating their drawbacks. The paper presents a system model for the time-triggered subsystem that extends the original proposal, and describes a Ravenscar implementation of the scheduler at the run-time system level, in the form of a new package Ada.Dispatching.TTS. Multiple programming patterns can be implemented on top of this scheduler. With respect to the previously proposed full-Ada implementation, only patterns that implied the use of asynchronous transfer of control have been excluded. On the other hand, the extension of the original model enables new patterns, not supported in our previous proposal, using the new types of continuation and optional slots. We hold that bringing the time-triggered paradigm to Ravenscar is both feasible and convenient for the High-Integrity and Embedded application domains.This work has been partly supported by the Spanish Government’s project M2C2 (TIN2014-56158-C4-1-P-AR) and the European Commission’s projects ENABLE-S3 and AQUAS (ECSEL-JU, Contracts 692455 and 737475)Real Sáez, JV.; Sáez Barona, S.; Crespo, A. (2018). Ravenscar Support for Time-Triggered Scheduling. ACM SIGAda Ada Letters. 38(1):41-54. https://doi.org/10.1145/3241950.3241957S4154381M. Aldea and M. González-Harbour. MaRTE OS: An Ada Kernel for Real-Time Embedded Applications. Reliable Software Technologies - Ada Europe 2001, Lecture Notes in Computer Science, 2043:305-316, 2001.ISO/IEC-JTC1-SC22-WG9. Ada Reference Manual ISO/IEC 8652:2012(E). URL: http://www.ada-europe.org/manuals/LRM-2012.pdf, 2012.J. Leung and J. Whitehead. On the complexity of xed-priority scheduling of periodic, real-time tasks. Performance Evaluation (Netherlands), 2(4):237-250, 1982.C. Liu and J. Layland. Scheduling Algorithms for Multiprogramming in a Hard Real-Time Environment. Journal of the ACM, 20(1):46-61, 1973.J. Real and P. Rogers. Session Summary: Experience. Ada Letters, 36(1):101-102, June 2016.J. Real, S. Sáez, and A. Crespo. Combined scheduling of time-triggeed plans and priority scheduled task sets. Ada Letters, 36(1):68-76, June 2016.J. Real, S. Sáez, and A. Crespo. Combining time-triggered plans with priority scheduled task sets. In M. Bertogna and L. M. Pinho, editors, Reliable Software Technologies - Ada-Europe 2016, volume 9695 of Lecture Notes in Computer Science. Springer, June 2016.S. Sáez and J. Real. TTS Ravenscar runtime. https://doi.org/10.5281/zenodo.1168723, February 2018

A hierarchical architecture for time- and event-triggered real-time systems

[EN] This paper proposes an architecture for combining the execution of time- and event-triggered real-time task sets. This makes it possible for the designer to choose the most appropriate mechanism depending on the role and nature of each task in the system. The proposed architecture allows one to choose the priority levels at which time- and event-triggered tasks are executed. This gives the designer an additional degree of freedom to make compromise decisions upon contradicting timing requirements, such as granting reduced jitter and at the same time providing prompt service to non-periodic events, for example. The proposed model is accompanied with a Ravenscar implementation of the time-triggered scheduler and a library of utilities for specifying time-triggered schedules and reusing time-triggered task patterns.This work has been partly supported by Spanish Government and FEDER funds (AEI/FEDER, UE) under grant (TIN2017-86520-C3-1-R) (PRECON-I4); and by European Commission project AQUAS (ECSEL-JU, Contract 737475).Real Sáez, JV.; Sáez Barona, S.; Crespo, A. (2019). A hierarchical architecture for time- and event-triggered real-time systems. Journal of Systems Architecture. 101:1-15. https://doi.org/10.1016/j.sysarc.2019.101652S11510

Delimiting the geographical background in species distribution modelling

[Aim]: The extent of the study area (geographical background, GB) can strongly affect the results of species distribution models (SDMs), but as yet we lack objective and practicable criteria for delimiting the appropriate GB. We propose an approach to this problem using trend surface analysis (TSA) and provide an assessment of the effects of varying GB extent on the performance of SDMs for four species. [Location]: Mainland Spain. [Methods]: Using data for four well known wild ungulate species and different GBs delimited with a TSA, we assessed the effects of GB extent on the predictive performance of SDMs: specifically on model calibration (Miller's statistic) and discrimination (area under the curve of the receiver operating characteristic plot, AUC; sensitivity and specificity), and on the tendency of the models to predict environmental potential when they are projected beyond their training area. [Results]: In the training area, discrimination significantly increased and calibration decreased as the GB was enlarged. In contrast, as GB was enlarged, both discriminatory power and calibration decreased when assessed in the core area of the species distributions. When models trained using small GBs were projected beyond their training area, they showed a tendency to predict higher environmental potential for the species than those models trained using large GBs. [Main conclusions]: By restricting GB extent using a geographical criterion, model performance in the core area of the species distribution can be significantly improved. Large GBs make models demonstrate high discriminatory power but are barely informative. By delimiting GB using a geographical criterion, the effect of historical events on model parameterization may be reduced. Thus purely environmental models are obtained that, when projected onto a new scenario, depict the potential distribution of the species. We therefore recommend the use of TSA in geographically delimiting the GB for use in SDMs.P.A. and A.J.-V. were supported by the Juan de la Cierva research program awarded by the Ministerio de Ciencia e Innovación – Fondo Social Europeo, and partly by the project CGL2009-11316/BOS – Fondos FEDER. P.A. is in Portugal thanks to a José Castillejo fellowship (2010–11) granted by the Ministerio de Ciencia e Innovación.Peer Reviewe