Cut-off and Escape Behaviors for Birth and Death Chains on Trees

We consider families of discrete time birth and death chains on trees, and show that in presence of a drift towards the root of the tree, the chains exhibit cut-off behavior along the drift and escape behavior in the opposite direction.Comment: 22 pages, 1 figure. This new version, written after referee's suggestions, is shorter and features a more clear presentation of the results. The previous proofs of Section 3, based on difference equations method, are now given in appendi

TFR VERSUS PREVIDENZA COMPLEMENTARE: UN' ANALISI QUANTITATIVA

I fenomeni dell’allungamento della vita media e il basso tasso di natalità hanno indotto il legislatore alla revisione del sistema di calcolo delle pensioni obbligatorie, col passaggio dal sistema retributivo e a ripartizione a quello contributivo. Naturale conseguenza di questa previsione è l’abbassamento del tenore di vita post-pensionamento. La recente riforma della previdenza complementare, dlgs n.252 5/12/2005, cerca invece di consentire il mantenimento di un tenore di vita adeguato attraverso una serie di incentivi e istituti volti ad aumentare i flussi di finanziamento alla previdenza complementare: di particolare importanza è l'istituto del conferimento del TFR alla previdenza complementare, incentivato con una serie di agevolazioni, di natura fiscale e contributiva. Scopo del nostro lavoro è condurre un'analisi prevalentemente quantitativa sui reali vantaggi che la previdenza complementare italiana offre rispetto alla situazione precedente la riforma, anche attraverso l'uso di simulazioni e confronti storici che possano chiarire quali sono le reali opportunità e gli ipotetici scenari futili, utili ai giovani per adottare una scelta consapevole per il loro futuro post-lavorativo

Identificazione di geni differenzialmente espressi nelle regioni medio-temporali del Sistema nervoso centrale di ratto in seguito a "contextual fear conditioning"

Questa tesi sperimentale fa parte di un progetto di ricerca finalizzato ad individuare i geni candidati ad essere differenzialmente espressi nell’amigdala e nell’ippocampo di ratti addestrati con il contextual fear conditioning. In questo test comportamentale,l’animale viene inserito nell’apparato di condizionamento(Skinner box) e sottoposto ad un training di 7 scosse elettriche(ciascuna dell’intensità di 1 mA e della durata di 1 secondo) intervallate 30 secondi l’una dall’altra. Gli animali addestrati mostrano una risposta di freezing ogni volta che sono inseriti nella Skinner box. E’ noto che il contextual fear conditioning richiede l’attivazione dell’amigdala e dell’ippocampo e provoca modificazioni dell’espressione genica a livello di queste due regioni. Per valutare tali modifiche del pattern di espressione genica si utilizza la tecnica dell’ibridazione sottrattiva soppressiva(suppression subtractive hybridisation,SSH).Questo metodo permette di ottenere l’isolamento delle sequenze differenzialmente espresse in seguito al trattamento in esame,tramite la costruzione di librerie sottrattive di cDNA. Inoltre,l’SSH è particolarmente efficiente nell’isolare sequenze poco espresse,non identificabili con altre tecniche che analizzano pattern di espressione genica. In questo lavoro sperimentale,abbiamo utilizzato un gruppo di ratti sottoposto a contextual fear conditioning ed un altro gruppo di controlli(animali mai entrati nell’apparato di condizionamento”naive”).A 48 ore di distanza dal condizionamento,sono stati sacrificati sia gli animali sperimentali,sia quelli di controllo;in seguito i loro cervelli sono stati estratti e sezionati ciascuno in tre parti:lobo anteriore,lobi medio-temporali e cervelletto. Abbiamo utilizzato solo i lobi medio-temporali,comprendenti ippocampo e amigdala,da cui poi è stato isolato l’RNA totale. Per una produzione efficiente di cDNA per l’allestimento di una libreria risulta molto utile purificare l’mRNA(1-5% del totale). L’utilizzo del PCR-SelectTM cDNA Subtraction kit permette di costruire una libreria forward ed una riverse rispettivamente costituite dai trascritti indotti,disattivati o modulati n seguito al contextual fear conditioning. Dopo aver valutato l’efficienza di sottrazione,i cDNA vengono clonati e sottoposti a screening. I cloni ottenuti vengono sequenziati per mezzo di un sequenziatore automatico e vengono successivamente identificati utilizzando le banche dati presenti in rete(programmi FASTA,BLASTX e BLASTIN).La reale espressione differenziale viene poi analizzata mediante Northern Blot e RT-PCR relativa

The politics of the “EMU governance”. European Policy Brief No. 7, February 2012

On 6 February 2012, Yves Bertoncini participated in a conference on European economic governance organized by Egmont – Royal Institute for International Relations. This Policy Brief is based on his intervention at the conference. The author pleads for a more encompassing form of EMU governance, which should be accompanied by a clarification of its democratic dimension

A friend in need is a friend indeed: Ken Walibora's novel Kufa kuzikana

After being for a long time in the shadow of its Tanzanian counterpart, Kenyan fiction has recently come into the foreground with writers such as Kyallo Wadi Wamitila, Rocha Chi-merah, Mwenda Mbatiah and Ken Walibora. The paper deals with his second novel Kufa kuzikana. Although Kufa Kuzikana is a powerful accusation of how ruthless ethnic feelings still inform many people from the intellectuals and top politicians to the uneducated villagers, the novel does contain a positive message as well in that it shows how true friendship can overcome ethnic and other differences and survive even in the most adverse circumstances

Beyond the Utenzi: narrative poems by Theobald Mvungi

Some time ago I came across a tiny collection of poems called Chungu tamu by Theobald Mvungi. The author was born in Mwanga province (Kilimanjaro) probably in the Fifties, as he graduated from the University of Dar es Salaam in 1975 and gained his M.Ed. degree in Nigeria (Ibadan) in 1978. He published his first collection of poems, Raha karaha, in 1982 and his third one, Mashairiya Chekacheka, in 1995. All Mwangi`s poems deal with social problems, but only those of the second collection are formally innovative. Five of the twenty poems of this collection tell a story and I am going to investigate three of them. It is striking and quite unusual in Swahili poetry to present the narration itself as another story. However, it is not the first time that it occurs in modern Swahili poetry. In fact, for instance Kezilahabi´s poem Hadithiya kitoto (from the collection Kichomi, 1974) opens with the scene of the narrator - the grandfather - sitting close to a fire with his grandchildren who want to be told a story, while roasting birds and potatoes. The last two strophes contain grandfather´s comment, i.e. a moral message. Thus the narrative act itself is represented, as it often happens in prose fiction. But whereas in Kezilahabi it only opens or frames the main story, in Mvungi the narrator´s interferences are intermingled with the main story to such an extent that in fact two parallel stories are narrated. I will call them the frame story and the main story

Some remarks on Kithaka wa Mberia's poetry

Kithaka wa Mberia (b.1956) is one of the most innovative Kenyan poets. Until now he has published four collections of poems and three plays. His poems contain a strong political and social criticism, sometimes in the form of animal allegories. He condemns various acts of violence done to women, like rapes of schoolgirls or prostitution caused by poverty. Some compositions seem life-stories of real persons, others are overtly didactic and moralizing, but in all the theme of social justice is almost obsessive. Another group of poems highlights the author’s concern with his surroundings and with the “health conditions” of the Earth in general; thus, for instance, he denounces the devastation of Kenyan soil in order to get foreign currency. His love of nature makes him address affectionate verses to animals, insects and plants. Formally the poems have little in common with the poetic tradition of the Swahili coast as they are in free verse. Kithaka exhibits a rich vocabulary of botanical and zoological terms and is fond of various forms of word-playing like chiming and punning; an important role in his poetry is played by parallelism. Moreover, he introduces into Kiswahili visual poems where typography is relied upon to perform expressive effects. Kithaka wa Mberia, together with other East African contemporary poets, proves that Swahili poetry is able to express universal themes and can reach a high artistic value even without repeating traditional models

New tendencies in the Swahili drama.

One of the most striking charactetistics of contemporary drama is its denial of illusion. Modern playwrights do their best to convince the audience that what is presented on the stage is not a tranche de vie (as was the aspiration of naturalist writers), but a performance

Kenyan literary Kiswahili

Until the Eighties the regional character of Kenyan prose writing was far less marked than that of Zanzibari novels. Different was the situation in poetry; in fact, Kimvita and Kiamu have been used even in modern times (see, e.g., Ahmad Nassir Juma Bhalo, Abdilatif Abdalla and Ahmed Sheikh Nabhany; the last one is well-known for his endeavour in enriching and modernizing Swahili terminology, and a few of his proposed terms, e. g. runinga for `television`, have been accepted). Kenyan prose fiction, on the other hand, used to be much alike to the up-country Tanzanian literary production, written as it was in standard Swahili, sometimes with many colloquial features