311 research outputs found
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A possibilistic approach to latent structure analysis for symmetric fuzzy data.
No full textIn many situations the available amount of data is huge and can be
intractable. When the data set is single valued, latent structure models are recognized
techniques, which provide a useful compression of the information. This is done by
considering a regression model between observed and unobserved (latent) fuzzy
variables. In this paper, an extension of latent structure analysis to deal with fuzzy data
is proposed. Our extension follows the possibilistic approach, widely used both in the
cluster and regression frameworks. In this case, the possibilistic approach involves the
formulation of a latent structure analysis for fuzzy data by optimization. Specifically, a
non-linear programming problem in which the fuzziness of the model is minimized is
introduced. In order to show how our model works, the results of two applications are
[email protected]
The Role of Common Cyclical Features for Coincident and Leading Indexes Building
No full textIn this paper we propose a new methodology to build composite coincident and leading
indexes. Based on a formal definition which requires that the first difference of the leading
index is the best linear predictor of the first difference of the coincident index, we show
that the notion of polynomial serial correlation common features can be used to build these
composite variables. Concepts and methods are illustrated by an empirical investigation of
the US business cycle [email protected]
Average Labor Taxes and Unemployment: Evidence from Italian Regions
No full textBy focusing on the Italian experience, we ask whether the relationship between labor taxes and unemployment varies across regions. In spite of similar national labor market institutions, we show that this relationship is significantly stronger in the highly industrialized North than in the less developed South, where unemployment is much higher. An important source of variation in the regional responsiveness of unemployment originates from the fact that regional gross wages in the North increase more than in the South in response to a hike in labor [email protected]
Devaluation (levels versus rates) and balance of payments in a cash-in-advance economy
No full textThis paper investigates the consequences of the currency devalution, both in
levels and rates, on the balance of payments in a cash-in-advance economy with
finite horizons, endogenous capital accumulation and international capital immobility.
In this context, a once and for all currency devaluation induces a balance
of payments surplus, whereas a sustained increase in the rate of devaluation produces,
in principle, an ambiguous effect on the balance of payments. If however
non-restrictive assumptions on some structural parameters are made, an increase
in the devaluation rate leads to a balance of payments surplus, the exact opposite
of Calvo's result (1981)[email protected]
Common Shocks, Common Dynamics, and the International Business Cycle
No full textThis paper develops an econometric framework to understand whether co-movements observed
in the international business cycle are the consequences of common shocks or common
transmission mechanisms. Then we propose a new statistical measure of the importance of
domestic and foreign shocks over the national business cycle. We show how to decompose
the business cycle effects of permanent-transitory shocks into those due to their domestic
and foreign components. We apply our analysis to G7 [email protected]
Where Do Banks Expand Abroad? An Empirical Analysis
No full textThis paper investigates the determinants of the pattern of banks' foreign investment. We extended previous analyses in three directions. First, we use a unique database that includes information on 260 large banks from OECD countries and all their foreign branches and subsidiaries in each one of the other OECD countries. Second, we consider explicitly the role of institutional and regulatory characteristics. Third, we considered within a unified framework a wide set of variables that are likely to influence the pattern of bank internationalization. Consistent with previous research, we find that a high degree of integration between the home and the destination countries has an effect on the location choice of multinational banks. However, we also find that the marginal effect of integration is much lower than that of other explanatory variables. Profit opportunities resulting from a high expected economic growth and the prospect of competing with relatively less efficient banks appear to be a key factor affecting the expansion abroad, especially in the case of subsidiaries. Institutional characteristics of the destination country also play a crucial role. For example, financial centers attract branches of foreign banks, but not subsidiaries, while lower regulatory restrictions on banking activities are associated with a stronger presence of foreign subsidiaries, but not of [email protected]
Forecasting Industrial Production and the Early Detection of Turning Points
No full textIn this paper we propose a simple model to forecast industrial production in
Italy up to 6 months ahead. We show that the forecasts produced using the
model outperform some popular forecasts as well as those stemming from an
ARIMA model used as a benchmark and those from some single equation
alternative models. We show how the use of these forecasts can improve the
estimate of a cyclical indicator and the early detection of turning points for
the manufacturing sector. This is of paramount importance for short-term
economic [email protected]@unimol.itpublished in Empirical Economics, vol. 29, no. 3. pp. 647-671
Money, Endogenous Fertility and Economic Growth
No full textThis paper analyzes the issue of money superneutrality through an intertemporal
optimizing model of capital accumulation with endogenous fertility, i.e. endogenous
population growth. Two elements of this setup invalidate money superneutrality:
i) a demand for fertility that depends on real money balances,
and ii) an inverse relation between capital-labor ratio and population growth.
Higher monetary growth increases fertility, since it reduces its opportunity cost,
and hence diminishes capital intensity, and per capita output. This reverse Tobin
effect is matched by an increase in aggregate capital and output growth rates. In
this framework, the optimal monetary growth rule is a "distorted Friedman rule"[email protected]
Penal sequestrations of equity holdings
No full textLe organizzazioni criminali sempre di più investono in attività lecite proventi di attività illecite. Pertanto al fine di combattere la criminalità organizzata e non, le misure di carattere patrimoniali risultano spesso essere più efficaci di quelle personali. L’impresa mafiosa presenta una peculiarità rispetto alla tradizionale impresa illecita: sempre più di frequente ha un oggetto lecito e opera su mercato nel rispetto formale della legge. Per contrastare il fenomeno criminale, sia esso organizzato o meno, da un punto di vista economico, è necessario aggredire l’attività di impresa. D’altro canto, l’impresa è un’attività e come tale non è sottoponibile a sequestro. Pertanto, oggetto della tutela cautelare possono essere le partecipazioni sociali relative alla società che esercita un’attività finanziata con proventi illeciti o in alternativa l’azienda come complesso di beni di cui si avvale l’impresa. Data la particolarità dei beni, l’apposizione dei sequestri penali sulle partecipazioni sociali e sull’azienda comporta problemi di coordinamento tra le norme processuali e quelle proprie del diritto commerciale, oltre che la necessità di individuare gli effetti che i sequestri producono sull’organizzazione societaria.
In particolare, con riguardo alle partecipazioni, i relativi poteri di amministrazione spettano al custode alla stregua dell’art. 2352 c.c. che contiene principi generali applicabili in caso di sequestri di tali beni. Peraltro, si rende necessario l’adattamento della disposizione civilistica alle ipotesi in cui i sequestri siano di matrice penale, atteso che questi ultimi perseguono anche finalità di natura pubblicistica oltre che patrimoniale. Il presente lavoro giunge alla conclusione che all’amministratore giudiziario non può essere riconosciuta una posizione corporativa all’interno della società più penetrante di quella propria del custode delle partecipazioni sociali in sede civile, ossia l’esercizio dei diritti amministrativi incorporati nella partecipazione stessa. Ne consegue l’impossibilità di riconoscere ai sequestri penali l’effetto di determinare lo scavalcamento dell’organizzazione capitalistico-corporativa, tipica delle società di capitali.
Il lavoro con riferimento al sequestro di azienda sociale, apposto in virtù di provvedimento cautelare emesso nei confronti di uno o più soci, conclude, seppur in termini dubitativi, ritenendo che l’amministratore giudiziario nominato abbia un potere di custodia non esteso anche alla gestione societaria che resta in capo all’organo amministrativo della società. Pertanto, l’attività dell’amministratore giudiziario assume carattere prettamente conservativo, teso a evitare la dispersione dell’azienda. Qualora, il provvedimento cautelare colpisca direttamente la società, il sequestro di azienda si estende di diritto alle partecipazioni sociali, permettendo, quindi, all’amministratore giudiziario di incidere sull’organizzazione societaria mediante l’esercizio dei diritti corporativi.Criminal organizations invest incomes deriving from illegal activities in legal activities. To the scope to fight criminal organizations, patrimonial measures often are more effective than personal ones. The mafious enterprise presents a different feature than illegal one: often, it is a legal activity and, formally, operates in legal manner. To oppose Mafia and other criminal organizations, on the economic side, it is needed attack the enterprise. Nevertheless, the latter is an activity and, then, can not be sequestrable. Therefore, only equity holdings or business (in the sense of the whole of the assets used to carry out an enterprise) can be object of sequestration. Because of characteristic of the goods, the penal sequestration of equity holdings and of business shows problems concerning the coordination between procedural law and commercial law, and the need to identify the effects on company’s organization.
In case of sequestration of equity holdings, the official receiver has administration of these goods, by virtue of article 2352 of Italian Civil Code. This article, in the opinion of the author, contains general principles applicable to all kind of sequestrations of equity holdings. Nevertheless, this civil disposition must be adapted in case of penal sequestrations, because of the different purposes aimed by civil sequestrations and penal ones. Infact, the latter has both public and patrimonial purpose. The work concludes that penal official receiver can not have more incisive a position in the company than civil official receiver. Both can only exercise rights included in the sequestered equity holdings. So, penal sequestrations of equity holdings can not have the effect to overtaking the typological organization – capitalistic-corporative - of companies.
In case of sequestration of business, placed by virtue of protective order issued against one or more shareholders, the official receiver has not the powers to administrate the company, infact the administration of company remains to directors. So, officiale receiver can only take actions for the purpose of avoid lost of business. If, the protective order is issued against the company, the sequestration of business extends itself to equity holdings, allowing the penal official receiver to exercise corporative rights.Dottorato di ricerca in Diritto ed economia: interessi rilevanti e tutele (XXV ciclo
A biochemical approach for the study of the spermatic funcionality in boar: capacitation and mitochondria
No full textLo sperma è costituito da spermatozoi sospesi in un mezzo liquido chiamato plasma seminale. Gli spermatozoi sono le cellule germinali maschili presenti negli esseri viventi ed hanno il compito di raggiungere il gamete femminile, l’oocita, per fecondarlo durante la riproduzione sessuale. La capacità fecondante dello spermatozoo è funzione della integrità cromatinica e mitocondriale, entrambe sono necessarie alla cellula nemaspermica per realizzare l’evento fecondativo nel suo complesso. I mitocondri sono organuli presenti in quasi tutte le cellule eucariotiche in numero variabile da poche decine ad alcune migliaia. I mitocondri negli spermatozoi sono localizzati nel “midpiece”, ovvero nella parte che collega la testa al flagello. A conferma di quanto già riportato in letteratura ottenere mitocondri isolati accoppiati è attualmente impossibile: essi sono disposti in un arrangiamento ad elica nel “midpiece” e la loro separazione richiede la rottura dei ponti disolfuro e irreversibile danneggiamento degli organuli. Per ovviare a questo é necessario sottoporre gli spermatozoi ad un trattamento ipotonico così da ottenere una sospensione di cellule demembranate in cui i mitocondri sono completamente accessibili da substrati ed inibitori (Piasecka et al. 2003 – Ferramosca et al. 2008). Scopo della ricerca descritta in questa tesi è stato studiare la bioenergetica mitocondriale nella capacitazione e nel congelamento di spermatozoi di verro.
È stato trovato che nella capacitazione si ha aumento del potenziale di membrana dei mitocondri che non dipende dall’ attività del complesso IV della catena respiratoria.
Il potenziale di membrana è stato misurato anche dopo diversi “step” di congelamento e dopo lo scongelamento degli spermatozoi di verro trattati ipotonicamente. Quello che si è ottenuto è stato un decremento nella velocità e nell’extent del potenziale di membrana che è risultato statisticamente significativo dopo la fase dello scongelamento. È noto infatti che il seme congelato non ha le stesse caratteristiche e lo stesso tasso di fertilità del seme fresco.
Nella ricerca di questa tesi, inoltre, è stato provato che l’utilizzo della pentossifillina aumenta la velocità e l’extent nella creazione di potenziale del seme scongelato.
La misura del potenziale di membrana durante congelamento/scongelamento e in seguito a qualsiasi trattamento può rappresentare una misura relativamente semplice per la valutazione della qualità del seme, utile nella fisiologia della riproduzione.
Lo studio relativo alle caratteristiche dell’HTC ha confermato che il lattato è substrato energetico per gli spermatozoi. E’ importante sottolineare che fino a pochi anni or sono questo veniva considerato soltanto un prodotto di scarto del metabolismo, prodotto e riversato nello spazio extracellulare. Sono recenti invece ricerche (Passarella S. et al. 2008; de Bari L. 2004; Valenti D. 2002; Atlante A. 2007) in cui si ha evidenza che il lattato è capace di entrare nelle cellule, è ossidato nel citoplasma da parte della cLDH, e infine può essere anche metabolizzato a livello mitocondriale ad opera di una lattato deidrogenasi mitocondriale. I risultati riportati in questa tesi dimostrano che, come nelle cellule nervose e muscolari (Passarella S. et al. 2008), L-LAT aggiunto all’esterno può essere assunto e metabolizzato dalle HTC.Semen consists of spermatozoa suspended in a liquid medium called seminal plasma. Sperm are the male germ cell present in living things and have the task of reaching the female gamete, the oocyte to fertilize during sexual reproduction. The fertilizing ability of sperm is a function of chromatin and mitochondrial integrity, both are necessary for the sperm cell insemination to make the event as a whole.
Mitochondria are organelles found in nearly all eukaryotic cells their number varies from a few dozen to several thousand. The sperm mitochondria are located in the “midpiece”, or the part that connects the head to the tail. In support of what was shown in literature obtain coupled mitochondria isolated it is currently impossible: they are laid out in a propeller arranged to the “midpiece” and their separation require the rupture of disulphide bonds and irreversible damage of organelles.
To avoid this it is necessary to subject the sperm to a hypotonic treatment in order to obtain a cell suspension demembranate where mitochondria are fully accessible to substrates and inhibitors (Piasecka et al. 2003 - Ferramosca et al. 2008). The purpose of the research described in this thesis was to study mitochondrial bioenergetics in capacitation and the freezing of boar sperm. It was found that there is increase in the capacitation of the membrane potential of mitochondria that does not depend on “activities” of respiratory chain complex IV.
The membrane potential was measured after several "step" after freezing and thawing of boar sperm hypotonic treatment. We got a decrease in speed and in the extent of membrane potential that was statistically significant after the thawing phase.
It is known that frozen semen hasn’t the same features and the same rate of fertility of fresh semen; in pursuit of this thesis is also evidence that the use of pentoxifylline increases the speed and the extent creating potential of thawed semen.
The measurement of membrane potential during freezing and thawing and after any treatment can be a relatively simple measure for assessing the quality of semen, which is useful in the physiology of reproduction. The study on the characteristics of HTC has confirmed that lactate is an energy substrate for sperm. It’s important to note that until a few years ago it was seen as only a waste product of metabolism, produced and poured into the extracellular space.
However, there are recent studies (Passarella S. et al. 2008; de Bari L. 2004, 2002 D. Valenti, A. Atlante 2007) in which there is evidence that lactate is capable of entering cells, is oxidized in the cytoplasm by of cLDH and finally it can also be metabolized in the mitochondria by a mitochondrial lactate dehydrogenase. The results reported in this work show that, as in nerve and muscle cells (S. Passarella et al. 2008), L-LAT added can be taken outside and metabolized by HTC.Dottorato di ricerca in Biochimica e Chimica Applicate (XXI ciclo