On the throughput-WIP trade-off in queueing systems, diminishing returns and the threshold property: A linear programming approach

We present a new unifying framework for investigating throughput-WIP(Work-in-Process) optimal control problems in queueing systems,based on reformulating them as linear programming (LP) problems withspecial structure: We show that if a throughput-WIP performance pairin a stochastic system satisfies the Threshold Property we introducein this paper, then we can reformulate the problem of optimizing alinear objective of throughput-WIP performance as a (semi-infinite)LP problem over a polygon with special structure (a thresholdpolygon). The strong structural properties of such polygones explainthe optimality of threshold policies for optimizing linearperformance objectives: their vertices correspond to the performancepairs of threshold policies. We analyze in this framework theversatile input-output queueing intensity control model introduced byChen and Yao (1990), obtaining a variety of new results, including (a)an exact reformulation of the control problem as an LP problem over athreshold polygon; (b) an analytical characterization of the Min WIPfunction (giving the minimum WIP level required to attain a targetthroughput level); (c) an LP Value Decomposition Theorem that relatesthe objective value under an arbitrary policy with that of a giventhreshold policy (thus revealing the LP interpretation of Chen andYao's optimality conditions); (d) diminishing returns and invarianceproperties of throughput-WIP performance, which underlie thresholdoptimality; (e) a unified treatment of the time-discounted andtime-average cases.

The rise and decline of children's labour participation levels during the early stages of industrialisation. Catalonia (1850-1925)

This article aims to analyse the reasons for the intensive use of childlabour in the 19th century and its subsequent decline in the first thirdof the 20th century in the context of an economy with a highly flexiblelabour supply like that of Catalonia. During the second half of the 19thcentury,factors relating to family economies, such as numerous familiesand low wages for adults, along with the technologies of the time thatrequired manual labour resources, would appear to explain the intensiveuse of child labour to the detriment of schooling. The technologicalchanges that occurred during the first third of the 20th century, thedemographic transition and adult wage increase (for both men and women)explain the schooling of children up to the age of 15 and theconsequent practical abolition of child labour in that new era ofeconomic modernisation.

Entrepreneurial structure of the mercantile company in pre-industrial Catalonia

The mercantile company was the basic form of enterprise in pre-industrial Catalonia. The aim of this paper is to study the formation and development of the mercantile companies in Barcelona whose end was the wholesale and retail sale of textiles in the botigues de teles (textile retail shops) throughout the eighteenth century. These firms were officially registered before a notary and their deeds reveal how these establishments were administered and managed.The study covers a sample of 121 mercantile companies, and the articles and documentation that were put into effect by 32 notaries who were active in Barcelona in the 18th century have been consulted in their entirety. From an initial selection of documentation, a total of 228 deeds registering companies have been found, 107 of which (47%) relate to the creation of companies whose various activities were centred in taverns, textile manufacturing, braiding.... While the 121 companies, which make up our sample and which account for 53% of the deeds registered with the notaries mentioned above, focused exclusively on the management of textile retail shops located in the commercial heart of the city. Thus one point of interest that the documentation reveals is that the majority of the mercantile companies registered by Barcelona notaries throughout the 18th century were establishments which traded in textiles. The first part of the article focuses on the structural characteristics of these enterprises, the number and socio-professional status of the partners and the extent of each partner s involvement in the administration and management. The second part of the article examines the capital investment made by each partner, their rights and obligations agreed on, the sharing out of profits and possible losses and the duration of the companies. The final aim of the paper is to highlight the evolution of these companies through one specific case.

Socio-economic inequalities in health in Catalonia

In this paper we measure the degree of income related inequality in mental health as measured by the GHQ instrument and general health as measured by the EQOL-5D instrument for the Catalan population. We find that income is the main contributor to inequality, although the share of inequality in mental health that can be explained by income is much greater than the corresponding share of inequality in general health. We also find that the variation in demographic structure reduces income related inequality in mental health but increases income related inequality in general health. The regional variations in both instruments for health are striking, with the Barcelona districts faring relatively bad with respect to the rest of geographical areas and Lleida being the health region where, all else held equal, the population reports the greatest level of health. A big share of inequality in the two health measures, but specially mental health, is due to the favourable position in both health and income of those who enjoy an indefinite contract with respect to the rest of individuals. We also find that risky working conditions affect both health measures and are able to explain an important share of socio-economic inequality.

Social spending and demographics: The role of public policies in the intergenerational redistribution of income. Empirical evidence from Spain and Catalonia

The demographic shift underway in Southern Europe requires a revision of some of thefundamental principles of the traditional welfare state. We analyze the evolution of several aspects of welfare and social expenditure over the last two decades. We find that in the context of the present demographic changes and real estate boom current social and pension policy leads to a new distribution of benefits and burdens which is highly intergenerationally unequal. We argue for a revised definition of public policy based on Musgrave's proposition as a possible rule for an intergenerationally fair distribution.

University admission marks in Catalonia: Some highlights from the empirical research

The results of the examinations taken by graduated high school studentswho want to enrol at a Catalan university are here studied. To do so,the authors address several issues related to the equity of the system:reliability of grading, difficulty and discrimination power of the exams.The general emphasis is put upon the concurrent research and empiricalevidence about the properties of the examination items and scores. Aftera discussion about the limitations of the exams' format and appropriatenessof the instruments used in the study, the article concludes with somesuggestions to improve such examinations.

Perceptual mapping of practical ethics along the value chain: A multiple correspondence analysis with industry and cultural indices as supplementary variables

This paper presents findings from a study investigating a firm s ethical practices along the value chain. In so doing we attempt to better understand potential relationships between a firm s ethical stance with its customers and those of its suppliers within a supply chain and identify particular sectoral and cultural influences that might impinge on this. Drawing upon a database comprising of 667 industrial firms from 27 different countries, we found that ethical practices begin with the firm s relationship with its customers, the characteristics of which then influence the ethical stance with the firm s suppliers within the supply chain. Importantly, market structure along with some key cultural characteristics were also found to exert significant influence on the implementation of ethical policies in these firms.

Managing by values in the next milenium: Cultural redesign for strategic organizational change

The system of beliefs and values, that shaped the model for management and organizations during the 20th century, is just not good enough today. In order to keep a business functioning well and competing successfully in markets that are increasingly more global, complex, professionally demanding, constantly changing and oriented towards quality and customer satisfaction a new model is needed. In this paper, we will propose that both Management by Instructions (MBI) and Management by Objectives (MBO) today give notoriously inadequate results. By contrast, description of a new approach labeled: Management by Values (MBV), seem to be emerging as a strategic leadership tool. The paper outlines this approach and discusses the implementation of MBV as a tool to redesign culture in organizations and prepare them for the next millenium.

Cultural differences on seeking information: an eye tracking study

The main goal of this research is to investigate how people with different cultural background differ in their interaction style and visual behavior on search engine results pages (SERP), more specifically between groups from the Middle Eastern region vs. Western Europe. We conducted a controlled eye-tracking experiment to explore and evaluate the visual behavior of Arabs and Spaniardusers when scanning through the first page of the search results in Google. Big differences can be observed in the 4 aspects studied: U.A.E. participants stayed on the SERPs for longer, they read more results and they read each snippet in a more complete way than Spaniards. In Spain, people tended to scan the SERP, reading less text on each snippet, and choose a result among the first top rankedones without hardly seeing those in bottom positions.

Construcción y redefinición de identidades, prácticas culturales yComunicación. Estudio de caso del Centro Cultural Comunitario de PlayaAncha (Valparaíso)

Esta investigación se enmarca en el estudio de la vida cotidiana de las personas y se pregunta específicamente por el proceso de construcción y redefinición de identidades, es decir los cambios en la vida de las personas. Un tema que podría ser demasiado general se encuadra en un caso concreto: El Centro Cultural Comunitario de Playa Ancha (CCPA)1.Entendemos todo proceso de construcción y redefinición identitaria como una experiencia de aprendizaje perceptual. En el marco específico del CCPA, los participantes han construido una comunidad de práctica a través de sus interacciones comunicativas recurrentes en el tiempo, prácticas comunicativas y significativas para los miembros del CCPA. Comparten una serie de repertorios simbólicos, relaciones de participación y cooperación, entre otras cosas. Aprendizaje que logrado que los integrantes del CCPA sean reconocidos por su entorno como practicantes y miembros del CCPA.Para explorar este proceso nos posicionamos desde un abordaje cualitativo. Por lo mismo, intentamos objetivar esta experiencia de aprendizaje perceptual desde las percepciones y las prácticas de los sujetos estudiados. Se contempla el desarrollo de un trabajo de campo de 6 meses que contempla un período de inmersión en la comunidad a través de la observación participante.Por medio de esta herramienta, se explorará en las formas que organizan su espacio, sus tiempos, sus prácticas y por ende, sus interacciones comunicativas. Es decir, como establecen y coordinan el vivir en común. Posteriormente, para objetivar el proceso de construcción y redefinición identitaria se realizarán 10 historias orales temáticas a los miembros más antiguos y experimentados del CCPA.

Ecología del paisaje y sistemas de información geográfica ante el cambio socioambiental en las áreas de la montaña mediterránea. Una aproximación metodológica al caso de los valles d'Hortmoier y Sant Aniol

Este artículo es una aproximación a los métodos utilizados para analizar, cuantificar y valorar los cambios en los usos y cubiertas del suelo en estos dos valles que forman parte del espacio natural protegido de la Alta Garrotxa. La dinámica vivida en este territorio es un claro ejemplo de los procesos acaecidos a lo largo del siglo XX en buena parte de las áreas de montaña mediterránea. Una dinámica caracterizada fundamentalmentepor un incremento de la superficie forestal en detrimento del espacio agrario. Así mismo se proponen pautas metodológicas para su adecuada cartografía, así como para determinar las áreas potencialmente recuperables de espacio agrario con el objetivo de mantener la diversidad paisajística, biológica y el patrimonio cultural con la ayuda de los SIG y la Ecología del Paisaje

El Paisatge

El concepce de paisatge ens permet una aproximació de síntesi al passat, present i a les tendències de futur dels territoris. En aquest sentit aquest concepte, entès com el conjunt de components de confereixen a un determinat espai unes característiques pròpies, és el reflex fidel d'evolució ambiental, econòmica, social, política i cultural que ha viscut un territori. En el cas concret de l'Alta Garrotxa el paisatge ha experinientat canvis radicals al llarg dels segles, i d'una manera molt especial en lesdarreres decades

The burden of musculoskeletal disorders in Catalonia

INTRODUCTION: Musculoskeletal disorders(MSDs)are extremely common and one of the major causes of disease burden around the world. The original Global Burden of Disease Study was commisioned by the World Bank in 1991 and established the DALY(Disability Ajusted Life Years) as an indicator of disease burden. The DALY calculation allows an assessment of not only mortality but also disability, in terms of time lived in health states worse than perfect health.OBJECTIVE: To estimate the burden of musculoskeletal disorders in Catalonia in 2010, through calculation of the DALY index.

Estudio petrológico de las aplitas de la zona comprendida entre el Cap Roig y el Faro de San Sebastián (Gerona)

Estudi de les estructures i característiques petrològiques de les aplites que es localitzen al litoral entre el Cap Roig i el Far de Sant Sebastià (Llafranc, Girona)

Sant Julià de Ramis y Puig Rom: dos ejemplos de yacimientos con armamento y equipamiento militar visigodo en el noreste peninsular

We present in this work a couple of weapons and objects related to the military equipment of early VIII century from two sites on Girona's province: the castellum of Sant Julià de Ramis (in the municipality of the same name), and the fort of Puig Rom (in Roses). The comparation of these materials has permitted to recompose a quite complete panoply with various types of knives and daggers, shield-handles, axes, spearheads and javelinheads, tips (regatones), arrowheads, belt-buckles and some buckles and horse harness elements