Indexing the Event Calculus with Kd-trees to Monitor Diabetes

Personal Health Systems (PHS) are mobile solutions tailored to monitoring patients affected by chronic non communicable diseases. A patient affected by a chronic disease can generate large amounts of events. Type 1 Diabetic patients generate several glucose events per day, ranging from at least 6 events per day (under normal monitoring) to 288 per day when wearing a continuous glucose monitor (CGM) that samples the blood every 5 minutes for several days. This is a large number of events to monitor for medical doctors, in particular when considering that they may have to take decisions concerning adjusting the treatment, which may impact the life of the patients for a long time. Given the need to analyse such a large stream of data, doctors need a simple approach towards physiological time series that allows them to promptly transfer their knowledge into queries to identify interesting patterns in the data. Achieving this with current technology is not an easy task, as on one hand it cannot be expected that medical doctors have the technical knowledge to query databases and on the other hand these time series include thousands of events, which requires to re-think the way data is indexed. In order to tackle the knowledge representation and efficiency problem, this contribution presents the kd-tree cached event calculus (\ceckd) an event calculus extension for knowledge engineering of temporal rules capable to handle many thousands events produced by a diabetic patient. \ceckd\ is built as a support to a graphical interface to represent monitoring rules for diabetes type 1. In addition, the paper evaluates the \ceckd\ with respect to the cached event calculus (CEC) to show how indexing events using kd-trees improves scalability with respect to the current state of the art.Comment: 24 pages, preliminary results calculated on an implementation of CECKD, precursor to Journal paper being submitted in 2017, with further indexing and results possibilities, put here for reference and chronological purposes to remember how the idea evolve

Essays on firms, competition and public procurement

This thesis consists of three chapters that study the interaction between public procurement and firms’ behavior. Chapters 1 and 2 study the pharmaceutical market in Ecuador, where, as in many middle-income countries, large public and private sectors coexist. Since the same set of firms often serve both sectors, there are important dependencies in the firms’ decisions across sectors that can affect medicine supply. Using a novel dataset, in Chapter 1, I provide reduced-form evidence that firms’ pricing decisions in the public and private sectors, indeed, respond to cross-sector incentives. Motivated by this evidence, in Chapter 2, I develop and estimate a model in which firms compete in auctions in the public sector and in prices in the private market. I use the model to quantify the effects of increasing the number of participants in the auction, changing the reserve prices, and introducing local-preference rules in the auction on the supply decisions in both sectors. Chapter 3, co-authored with Felipe Brugués and Samuele Giambra, uses detailed ownership information of private firms in Ecuador and the identity of the universe of bureaucrats to provide evidence of the welfare consequences of the misallocation of public procurement contracts due to political connections. Using an event study design, we show that after establishing a political connection, firms are more likely to win government contracts and charge, on average, 7% higher prices than unconnected firms. Production function estimates reveal that politically connected firms are, on average, less efficient. We propose a framework to estimate the losses to society that derive from the under-provision of public services caused by price inflation and from the excess costs generated by the misallocation of government contracts

Non-relativistic strings and branes as non-linear realizations of Galilei groups

We construct actions for non-relativistic strings and membranes purely as Wess-Zumino terms of the underlying Galilei groups.Comment: references adde

A new empirical model of sea surface microwave emissivity for salinity remote sensing

SMOS (Soil Moisture and Ocean Salinity) is a European Space Agency mission that aims at generating global ocean salinity maps with an accuracy of 0.1 psu, at spatial and temporal resolution suitable for climatic studies. The satellite sensor is an L-band (1400-1427 MHz) aperture synthesis interferometric radiometer. Sea surface salinity (SSS) can be retrieved since the brightness temperature of sea water is dependent on the frequency, angle of observation, dielectric constant of sea water, sea surface temperature and sea surface state. This paper presents a new empirical sea water emissivity model at L-band in which surface roughness effects are parameterized in terms of wind speed and significant wave height. For the SMOS mission these parameters can be obtained from external measurements and model diagnostics. An analysis has been done on the effect on SSS retrieval of different sources for this auxiliary information. Copyright 2004 by the American Geophysical UnionThis study was funded by ESA-ESTEC under WISE (14188/00/NL/DC) and EuroSTARRS (15950/02/NL/SF) contracts, and by the Spanish National Program on Space Research under grant ESP2001-4523-PEPeer Reviewe

A "semi-closed" recirculating system for the in situ study of feeding and respiration of benthic suspension feeders

Suspension feeding is one of the most widespread feeding strategies among benthic organisms. However, natural feeding ecology and energetics of benthic suspension feeders are poorly known. The scarcity of field methods, apparatus and protocols that facilitate obtention of reliable in situ data has contributed to this lack of knowledge. A detailed description of an improved semi-closed recirculating system as well as the experimental set up is provided for the study of energetics in benthic suspension feeders. The system, completely submersible and surface-independent, allows us to assess oxygen concentration changes and feeding rates under natural conditions. Methodological examinations are conducted to investigate: a) the circulation of the water within the chamber; b) the time required for the flushing pump to entirely renew the volume of water of the incubation chambers; c) the behavior of the species within the chambers; d) the time of acclimation to the chamber conditions for the different species; e) the maximum decrease in oxygen concentration without affecting respiration rate; f) the time required to detect changes in concentration of the natural food sources. The system and experimental protocol is tested with species from three representative phyla, Porifera, Cnidaria and TunicataThe manuscript was improved by the comments of Fenny Cox. We would like to thanks the assistance of Mikel Zabala, Josep-Maria Llenas and Loïc de Maissonneuve. Support for this work was provided by a RED research contract from the “Generalitat de Catalunya” to R.C., by a postdoctoral fellowship from the “Ministerio de Educación y Cultura” to M.R., by PETRI grant PTR94-0119, by DGICYT grant PB98-0456-C03-01 and by a LEA projectPeer reviewe

Knowledge sharing in the health scenario

The understanding of certain data often requires the collection of similar data from different places to be analysed and interpreted. Interoperability standards and ontologies, are facilitating data interchange around the world. However, beyond the existing networks and advances for data transfer, data sharing protocols to support multilateral agreements are useful to exploit the knowledge of distributed Data Warehouses. The access to a certain data set in a federated Data Warehouse may be constrained by the requirement to deliver another specific data set. When bilateral agreements between two nodes of a network are not enough to solve the constraints for accessing to a certain data set, multilateral agreements for data exchange are needed. We present the implementation of a Multi-Agent System for multilateral exchange agreements of clinical data, and evaluate how those multilateral agreements increase the percentage of data collected by a single node from the total amount of data available in the network. Different strategies to reduce the number of messages needed to achieve an agreement are also considered. The results show that with this collaborative sharing scenario the percentage of data collected dramaticaly improve from bilateral agreements to multilateral ones, up to reach almost all data available in the network.Peer ReviewedPostprint (published version

Magnon-Like Dispersion Relation from M-Theory

We investigate classical rotating membranes in two different backgrounds. First, we obtain membrane solution in $AdS_4\times S^7$ background, analogous to the solution obtained by Hofman and Maldacena in the case of string theory. We find a magnon type dispersion relation similar to that of Hofman and Maldacena and to the one found by Dorey for the two spin case. In the appendix of the paper, we consider membrane solutions in $AdS_7\times S^4$, which give new relations between the conserved charges.Comment: 16 pages, typos corrected; V3: New section and comments added, to appear in Nucl. Phys.

Galilean Superconformal Symmetries

We consider the non-relativistic c -> \infty contraction limit of the (N=2k)- extended D=4 superconformal algebra su(2,2;N), introducing in this way the non-relativistic (N=2k)-extended Galilean superconformal algebra. Such a Galilean superconformal algebra has the same number of generators as su(2,2|2k). The usp(2k) algebra describes the non-relativistic internal symmetries, and the generators from the coset u(2k)/usp(2k) become central charges after contraction.Comment: 15 pages; v3:2 reference added, misprints corrected. Version to appear in PL

N=2 superconformal Newton-Hooke algebra and many-body mechanics

A representation of the conformal Newton-Hooke algebra on a phase space of n particles in arbitrary dimension which interact with one another via a generic conformal potential and experience a universal cosmological repulsion or attraction is constructed. The minimal N=2 superconformal extension of the Newton-Hooke algebra and its dynamical realization in many-body mechanics are studied.Comment: v3: Discussion in sect. 2.1 extended, references added. The version to appear in PL