Verifica dell'efficienza informativa del mercato. Metodologia dell'Event Study.

I mercati finanziari sono contraddistinti da una grande volatilità dei titoli quotati e scambiati. Questa volatilità la maggior parte delle volte deriva dell’andamento generale del mercato stesso, in altri casi, invece, scaturisce da fattori particolari che agiscono unicamente sul prezzo del singolo titolo. Lo scopo di tale lavoro è quello di comprendere se il mercato finanziario in esame, è un mercato efficiente in senso informativo, cioè se incorpora nel prezzo dei singoli titoli tutte le informazioni definite rilevanti che concernono questi ultimi. Nel corso dell’elaborato, verrà analizzato quale trend ci si attende da un titolo o quale evoluzione ha già avuto il titolo stesso in risposta ad un evento o ad una notizia price sensitive. Questi appena delineati, sono i fini che ci si prefigge di raggiungere nel momento in cui si decide di intraprendere un event study in finanza. Si tratta quindi di cercare una metodologia che consenta di comprendere queste reazioni dei prezzi; questo metodo è proprio l’Event Studies (ES). L’analisi quantitativa richiederà un’analisi storico-istituzionale del ciclo finanziario internazionale e una attenzione per le Unexpected News (UN), per misurarne l’impatto in una event window. Diversi sono i modelli di riferimento, e diverse sono le tecniche econometriche presenti nella letteratura sulla materia e utilizzate per l’analisi inferenziale. Saranno presentati modelli statici come il market model, ritenuto da molti studiosi, il modello che assicura le migliori performance e metodologie statistico-econometriche come il modello classico di regressione lineare (OLS) che assicura dei buoni risultati. Dopo la stima dei rendimenti mediante tale approccio, sarà svolta un’analisi di quelli direttamente imputabili all’evento considerato e che non rientrano nel normale andamento del titolo (Abnormal Returns). Su questi rendimenti anomali verranno poi condotti test statistici per la verifica della loro significatività

Exploiting the archive: and the animals came in two by two, 16mm, CD-ROM and BetaSp

This a post-print, author-produced version of an article accepted for publication in Area. Copyright © 1999 Wiley Blackwell. The definitive version is available at www3.interscience.wiley.comUsing an account of the construction and subsequent exploitation of the film archive at the BBC's Natural History Unit, this paper explores the ways in which animals are embedded in the different cultures of care, control and commodification in the zoo and the wildlife film-making unit. Network analysis is used to account for the similarities and tensions between these forms of animal exhibition, as revealed in the electronic zoo at Wildscreen World

Genetic screening and democracy: lessons from debating genetic screening criteria in the Netherlands

Recent decades have witnessed increasing possibilities for genetic testing and screening. In clinical genetics, the doctor’s office defined a secluded space for discussion of sensitive reproductive options in cases of elevated risk for genetic disorders in individuals or their offspring. When prenatal screening for all pregnant women became conceivable, the potential increase in scale made social and ethical concerns relevant for the whole of society. Whereas genetic testing in clinical genetic practice was widely accepted, prenatal screening at a population level met with unease. Concerns were raised regarding social pressure to screen: the sum of individual choice might result in a ‘collective eugenics’. The government’s involvement also raised suspicion: actively offering screening evoked associations with eugenic population policies from the first half of the 20th century. By reconstructing elements of policy and public debate on prenatal screening in the Netherlands from the past 30 years, this article discusses how the government has gradually changed its role in balancing the interest of the individual and the collective on genetic reproductive issues. Against a background of increasing knowledge about and demand for prenatal screening among the population, governmental policy changed from focusing on protection by banning screening toward facilitating screening in a careful and ethically sound way by providing adequate information, decision aids and quality assessment instruments. In the meanwhile, invigorating democracy in public debate may entail discussing concepts of ‘the good life’ in relation to living with or without impairments and dealing with genetic information about oneself or one’s offspring

The Staphylococcus aureus superantigen SElX is a bifunctional toxin that inhibits neutrophil function:SElX Inhibits Neutrophil Function

Bacterial superantigens (SAgs) cause Vβ-dependent T-cell proliferation leading to immune dysregulation associated with the pathogenesis of life-threatening infections such as toxic shock syndrome, and necrotizing pneumonia. Previously, we demonstrated that staphylococcal enterotoxin-like toxin X (SElX) from Staphylococcus aureus is a classical superantigen that exhibits T-cell activation in a Vβ-specific manner, and contributes to the pathogenesis of necrotizing pneumonia. Here, we discovered that SElX can also bind to neutrophils from human and other mammalian species and disrupt IgG-mediated phagocytosis. Site-directed mutagenesis of the conserved sialic acid-binding motif of SElX abolished neutrophil binding and phagocytic killing, and revealed multiple glycosylated neutrophil receptors for SElX binding. Furthermore, the neutrophil binding-deficient mutant of SElX retained its capacity for T-cell activation demonstrating that SElX exhibits mechanistically independent activities on distinct cell populations associated with acquired and innate immunity, respectively. Finally, we demonstrated that the neutrophil-binding activity rather than superantigenicity is responsible for the SElX-dependent virulence observed in a necrotizing pneumonia rabbit model of infection. Taken together, we report the first example of a SAg, that can manipulate both the innate and adaptive arms of the human immune system during S. aureus pathogenesis

Metingen over de verdampingssnelheid van ijs

Applied SciencesKramers Laboratorium voor Fysische Technologi