The Farm, the city, and the emergence of social security

We study the social, demographic and economic origins of social security. The data for the U.S. and for a cross section of countries suggest that urbanization and industrialization are associated with the rise of social insurance. We describe an OLG model in which demographics, technology, and social security are linked together in a political economy equilibrium. In the model economy, there are two locations (sectors), the farm (agricultural) and the city (industrial) and the decision to migrate from rural to urban locations is endogenous and linked to productivity differences between the two locations and survival probabilities. Farmers rely on land inheritance for their old age and do not support a pay-as-you-go social security system. With structural change, people migrate to the city, the land loses its importance and support for social security arises. We show that a calibrated version of this economy, where social security taxes are determined by majority voting, is consistent with the historical transformation in the United States.

Indoor localisation with Android devices

This project analyses WiFiSLAM, an indoor positioning system for mobile phones that tries to estimate the position by analysing WiFi signals.

The Security Blanket, September 2001, Vol.1, no.1

Newsletter for Information Technology Department

The Security Blanket, October 2001, Vol.1 , no.2

Newsletter for Information Technology Department

The Security Blanket, November 2001, Vol.1, no.3

Newsletter for Information Technology Department

The Security Blanket, May/June/July 2003, Issue 15

Newsletter for Information Technology Department

Optimization of floor cleaning coverage performance of a random path-planning mobile robot

Floor cleaning is a typical robot application. There are several mobile robots aviable in the market for domestic applications most of them with random path-planning algorithms. In this paper we study the cleaning coverage performances of a random path-planning mobile robot and propose an optimized control algorithm, some methods to estimate the are of the room, the evolution of the cleaning and the time needed for complete coverage.

Localització i control en temps real de PDA's basades en Windows Mobile mitjançant el sistema GPS

Desenvolupament d'un sistema consistent en un software per la recopilació de dades GPS per a Windows Mobile, un servidor de comunicacions, un server web i una plana web de consulta de les posicions en temps real de les PDA's.

Localització indoor a través de dispositius Android

Durant el projecte s'ha planificat i dut a terme la creació i verificació d'un APP que simula una aplicació comercial senzilla. S'ha seleccionat una localització, el centre comercial l'Illa Diagonal, s'ha calibrat seguint les instruccions de WiFiSLAM, s'ha creat un APP que integra la visualització de la posició sobre plànol basada en el SDK de WiFiSLAM amb funcions de càlcul de distàncies i s'han fet proves per acotar la fiabilitat de la solució, la seva exactitud i la seva precisió.

A-1A Supplemental Security Income Program, January 2004

Monthly report from the Iowa Department of Human Services on Supplemental Security Income Program (SSI).

A-1A Supplemental Security Income Program, February 2004

Monthly report from Iowa Department of Human Services on income.

A-1A Supplemental Security Income Program, March 2004

Monthly report from the Iowa Department of Human Services on Supplemental Security Income Program (SSI).

A-1A Supplemental Security Income Program, April 2004

Monthly report from the Iowa Department of Human Services on income.

A-1A Supplemental Security Income Program, May 2004

Monthly report from Iowa Department of Human Services on income.

Mobile or fixed bearing for total knee arthroplasty? Ambulatory gait analysis results

Background: Mobile-bearing knee replacements have some theoretical advantages over fixed-bearing devices. However, very few randomized controlled clinical trials have been published to date, and studies showed little clinical and subjective advantages for the mobile-bearing using traditional systems of scoring. The choice of the ideal outcome measure to assess total joint replacement remains a complex issue. However, gait analysis provides objective and quantifying evidences of treatment evaluation. Significant methodological advances are currently made in gait analysis laboratories and ambulatory gait devices are now available. The goal of this study was to provide gait parameters as a new objective method to assess total knee arthroplasty outcome between patients with fixed- and mobile-bearing, using an ambulatory device with minimal sensor configuration. This randomized controlled double-blind study included to date 14 patients: the gait signatures of four patients with mobile-bearing were compared to the gait signatures of nine patients with fixed-bearing pre-operatively and post-operatively at 6 weeks, 3 months and 6 months. Each participant was asked to perform two walking trials of 30m long at his/her preferred speed and to complete a EQ-5D questionnaire, a WOMAC and Knee Society Score (KSS). Lower limbs rotations were measured by four miniature angular rate sensors mounted respectively, on each shank and thigh. A new method for a portable system for gait analysis has been developed with very encouraging results regarding the objective outcome of total knee arthroplasty using mobile- and fixed-bearings.