Calling vs receiving party pays: market penetration and the importance of the call externality

In this paper we study how the access price affects the choice of the tariff regime taken by the network operators. We show that for high values of the access price, that is taken as a parameter by the firms, networks decide to charge only the callers. Otherwise, for low values of the access charge, networks charge also the receivers. Moreover, we compare market penetration and total welfare between the two price regimes. Our model suggests that, for high values of call externality, market penetration and total welfare are larger in Receiving Party Pays regime when the access charge is close to zero.

Eticket : gestió d'esdeveniments i venda d'entrades online

Avui dia, la gestió d’esdeveniments online i la seva promoció és un mercat creixent gràcies a l’evolució de la web 2.0 i a les xarxes socials. Ticketmaster és el referent, tot i així, no existeix una oferta clara per gestionar la venda d’entrades d’esdeveniments d’una mida petita o mitjana i que aprofiti les xarxes socials i la integració d’aplicacions que aquestes proporcionen. L’objectiu és realitzar una aplicació web on els usuaris (propis o de Facebook) puguin crear esdeveniments, publicar-los i promocionar-los a les xarxes socials, així com gestionar les tasques i característiques relacionades com la venda d’entrades i la llista de convidats.

Desenvolupament d'una aplicació Android per a Moodle

L'evolució que la tecnologia de les comunicacions sense fils ha experimentat en els darrers anys permet que avui en dia els dispositius mòbils proporcionin una resposta més que acceptable. Ja s'han superat molts dels problemes de mobilitat, d'infraestructura i d'ample de banda que fins ara dificultaven l'ús d'aquests dispositius. Aquest fet ha fomentat l'expansió de diferents sistemes dels que es pot destacar Android, iPhone OS i Windows Mobile/Windows Phone 7. Els dos primers són els que actualment es disputen el lideratge del mercat dels dispositius i aplicacions mòbils i és Android el que ha experimentat el major creixement els darrers anys. Paral·lelament, la constant introducció de programari d'e-learning destinat a activitats de formació no presencial basades en Internet ha permès arribar a milions d'usuaris en diferents àmbits, com ara universitats, empreses i institucions d'arreu del món. D'aquest conjunt de programari destaca Moodle, suite de codi obert que permet crear llocs web de formació en línia de forma senzilla i eficaç.Aquest Projecte de Final de Carrera, emmarcat en l'àrea de Xarxes de Computadors, conjugaaquests tres conceptes mitjançant el desenvolupament d'una aplicació per a dispositius mòbils Android que connecta a un servidor Moodle. La comunicació entre ells utilitza intensivament les xarxes sense fils i fa crides als serveis que aquest ofereix gràcies als Web Services, mètode de comunicacions composat d'un conjunt de protocols i de programari que permet la comunicació entre dos dispositius a través de la xarxa.

Bases de datos Multimedia

Aquest treball mira d'aproximar-se a la situació actual de les bases de dades multimèdia. Per a fer-ho, s'ha optat per un enfocament múltiple que té en compte diferents aspectes del producte multimèdia: els aspectes econòmics, és a dir, la situació del mercat (nombre de bases de dades, volum de negoci, creixement, etc.), els aspectes tècnics, és a dir, l'eina emprada, la seva evolució, les seves limitacions i problemes, i les seves aplicacions i serveis en diferents àrees (amb un interès especial en el camp de la documentació i la formació i la recerca).

Analysis of Pleistocene paleodrainage evolution in the Po Basin (Italy) by multivariate statistical techniques

In order to obtain a high-resolution Pleistocene stratigraphy, eleven continuouslycored boreholes, 100 to 220m deep were drilled in the northern part of the PoPlain by Regione Lombardia in the last five years. Quantitative provenanceanalysis (QPA, Weltje and von Eynatten, 2004) of Pleistocene sands was carriedout by using multivariate statistical analysis (principal component analysis, PCA,and similarity analysis) on an integrated data set, including high-resolution bulkpetrography and heavy-mineral analyses on Pleistocene sands and of 250 majorand minor modern rivers draining the southern flank of the Alps from West toEast (Garzanti et al, 2004; 2006). Prior to the onset of major Alpine glaciations,metamorphic and quartzofeldspathic detritus from the Western and Central Alpswas carried from the axial belt to the Po basin longitudinally parallel to theSouthAlpine belt by a trunk river (Vezzoli and Garzanti, 2008). This scenariorapidly changed during the marine isotope stage 22 (0.87 Ma), with the onset ofthe first major Pleistocene glaciation in the Alps (Muttoni et al, 2003). PCA andsimilarity analysis from core samples show that the longitudinal trunk river at thistime was shifted southward by the rapid southward and westward progradation oftransverse alluvial river systems fed from the Central and Southern Alps.Sediments were transported southward by braided river systems as well as glacialsediments transported by Alpine valley glaciers invaded the alluvial plain.Kew words: Detrital modes; Modern sands; Provenance; Principal ComponentsAnalysis; Similarity, Canberra Distance; palaeodrainage

Using problem-based learning for introducing producer theory and market structure in intermediate microeconomics

This paper shows how instructors can use the problem‐based learning method to introduce producer theory and market structure in intermediate microeconomics courses. The paper proposes a framework where different decision problems are presented to students, who are asked to imagine that they are the managers of a firm who need to solve a problem in a particular business setting. In this setting, the instructors’ role isto provide both guidance to facilitate student learning and content knowledge on a just‐in‐time basis

The allometry of non-employment. What can compositional data analysis tell us about labour market performance across the UK's regions?

The low levels of unemployment recorded in the UK in recent years are widely cited asevidence of the country’s improved economic performance, and the apparent convergence of unemployment rates across the country’s regions used to suggest that the longstanding divide in living standards between the relatively prosperous ‘south’ and the more depressed ‘north’ has been substantially narrowed. Dissenters from theseconclusions have drawn attention to the greatly increased extent of non-employment(around a quarter of the UK’s working age population are not in employment) and themarked regional dimension in its distribution across the country. Amongst these dissenters it is generally agreed that non-employment is concentrated amongst oldermales previously employed in the now very much smaller ‘heavy’ industries (e.g. coal,steel, shipbuilding).This paper uses the tools of compositiona l data analysis to provide a much richer picture of non-employment and one which challenges the conventional analysis wisdom about UK labour market performance as well as the dissenters view of the nature of theproblem. It is shown that, associated with the striking ‘north/south’ divide in nonemployment rates, there is a statistically significant relationship between the size of the non-employment rate and the composition of non-employment. Specifically, it is shown that the share of unemployment in non-employment is negatively correlated with the overall non-employment rate: in regions where the non-employment rate is high the share of unemployment is relatively low. So the unemployment rate is not a very reliable indicator of regional disparities in labour market performance. Even more importantly from a policy viewpoint, a significant positive relationship is found between the size ofthe non-employment rate and the share of those not employed through reason of sicknessor disability and it seems (contrary to the dissenters) that this connection is just as strong for women as it is for men

El Forment a la Barcelona baixmedieval: preus, mesures i fiscalitat (1283-1345)

A través de l'anàlisi de dos sèries de diferents llibres de comptabilitat de Barcelona, els procedents de la gestió dels molins reals i els redactats per una institució eclesiàstica, la Pia Almoina, vam començar a estudiar el mercat del blat a Barcelona durant l'edat mitjana. Hem analitzat anteriorment el valor de les mesures a Barcelona i, per poder qualificar el preu real del pa, també hem estudiat els diferents processos industrials per fer pa de blat. Després, hem analitzat el conjunt d'impostos que pesaven sobre la comercialització de cereals. A través de l'estudi de l'evolució dels preus, hem tractat de fer una primera aproximació de la primera etapa de la crisi baixmedieval, concretament entre 1283 i 1345, tenint en compte els contrastos amb els treballs ja coneguts sobre la base de les fonts on la noció de quantitat no va ser considerada. Finalment, hem comparat els nostres resultats amb alguns treballs referents a la Corona d'Aragó i el món mediterrani, a fi d'obtenir una idea més precisa de la cronologia de les crisis de subsistència

Compositional evolution with mass transfer in closed systems

Evolution of compositions in time, space, temperature or other covariates is frequentin practice. For instance, the radioactive decomposition of a sample changes its composition with time. Some of the involved isotopes decompose into other isotopes of thesample, thus producing a transfer of mass from some components to other ones, butpreserving the total mass present in the system. This evolution is traditionally modelledas a system of ordinary di erential equations of the mass of each component. However,this kind of evolution can be decomposed into a compositional change, expressed interms of simplicial derivatives, and a mass evolution (constant in this example). A rst result is that the simplicial system of di erential equations is non-linear, despiteof some subcompositions behaving linearly.The goal is to study the characteristics of such simplicial systems of di erential equa-tions such as linearity and stability. This is performed extracting the compositional differential equations from the mass equations. Then, simplicial derivatives are expressedin coordinates of the simplex, thus reducing the problem to the standard theory ofsystems of di erential equations, including stability. The characterisation of stabilityof these non-linear systems relays on the linearisation of the system of di erential equations at the stationary point, if any. The eigenvelues of the linearised matrix and theassociated behaviour of the orbits are the main tools. For a three component system,these orbits can be plotted both in coordinates of the simplex or in a ternary diagram.A characterisation of processes with transfer of mass in closed systems in terms of stability is thus concluded. Two examples are presented for illustration, one of them is aradioactive decay