Estimating Verdoorn law for Italian firms and regions

In empirical regional economics, returns to scale are typically estimated at the regional level in search for evidence on alternative theories of growth and agglomeration. However, returns to scale may also have a firm-level dimension. In this paper, we exploit micro level data and estimate the dynamic Verdoorn law in a multilevel-setting, where returns to scale are obtained simultaneously for the micro and the regional level. Using Italian firm-level data and the NUTS-3 level of aggregation, we estimate the classic and augmented versions of Verdoorn law for all sectors and separately for manufacturing. Our results show that increasing returns to scale co-exist at both levels, with some degree of regional heterogeneity across the Italian peninsula.Returns to scale, Verdoorn Law, Multilevel models, Italian firms

Influenza del clima ondoso e delle mareee sulla posizione della linea di riva: Lido Signorino (Marsala)

La conoscenza della posizione della linea di riva nel tempo è indispensabile per verificare la necessità di opere di difesa e per lo sviluppo di piani di gestione costiera. Essa rappresenta l’intersezione tra la superficie marina e quella terrestre, non è un’entità geometrica fissa, ma varia continuamente a causa del moto ondoso e delle fluttuazioni del livello marino ed è in continuo movimento a causa dei fenomeni di trasporto solido. La maggior difficoltà riscontrata nelle operazioni di rilievo è la determinazione esatta della sua posizione. Risulta pertanto necessaria la comprensione delle caratteristiche del moto ondoso (conoscenza delle mareggiate), dei livelli marini e del profilo trasversale della spiaggia al momento del rilievo. Questo lavoro di ricerca ha come principale obbiettivo l’analisi dell'influenza del clima ondoso e della marea sulla stima della posizione della linea di riva attraverso immagini telerilevate, inoltre viene proposta una nuova metodologia messa a punto su un caso di studio reale. La metodologia proposta ha carattere multi disciplinare, considera infatti, sia aspetti geomorfologici, sia aspetti idraulico marittimi e utilizza strumenti tipici del telerilevamento. Lo studio del clima ondoso è stato condotto a partire dalla mareggiata ordinaria fatta propagare nell'area in studio attraverso un modello di onda spettrale (SWAN: Simulating WAves Nearshore). Inoltre si sono considerate sia le oscillazioni mareali sia la massima altezza raggiunta dall’onda sulla spiaggia emersa (run-up). Il caso in studio ha messo in evidenza gli errori prodotti nella stima della posizione della linea di riva mediante la semplice individuazione della stessa attraverso ortofoto georiferite (1994, 2000, 2006) infatti in tal modo il tracciamento della linea di riva viene eseguito considerando solamente l'interfaccia "asciutto/bagnato". Riportando sulle ortofoto lo spostamento della linea di riva determinato dal clima ondoso associato all’ordinaria mareggiata e riportando anche le massime oscillazioni mareali, si è riscontrato che durante l’intervallo temporale analizzato l’errore aggiuntivo prodotto risulterebbe superiore a 15 m, inficiando l’attendibilità di uno studio diacronico dell'evoluzione della linea di riva

Estimating Verdoorn law for Italian firms and regions

In empirical regional economics, returns to scale are typically estimated at the regional level in search for evidence on alternative theories of growth and agglomeration. However, returns to scale may also have a firm-level dimension. In this paper, we exploit micro level data and estimate the dynamic Verdoorn law in a multilevel-setting, where returns to scale are obtained simultaneously for the micro and the regional level. Using Italian firm-level data and the NUTS-3 level of aggregation, we estimate the classic and augmented versions of Verdoorn law for all sectors and separately for manufacturing. Our results show that increasing returns to scale co-exist at both levels, with some degree of regional heterogeneity across the Italian peninsula

Smoking, health and ageing

On March 19, 2008 a Symposium on Pathophysiology of Ageing and Age-Related diseases was held in Palermo, Italy. Here, the lecture of V. Nicita-Mauro on Smoking, health and ageing is summarized. Smoking represents an important ageing accelerator, both directly by triggering an inflammatory responses, and indirectly by favoring the occurrence of several diseases where smoking is a recognized risk factor. Hence, non-smokers can delay the appearance of diseases and of ageing process, so attaining longevity

Impaired Ca2+ sensitivity of a novel GCAP1 variant causes cone dystrophy and leads to abnormal synaptic transmission between photoreceptors and bipolar cells

Guanylate cyclase-activating protein 1 (GCAP1) is involved in the shutdown of the phototransduction cascade by regulating the enzymatic activity of retinal guanylate cyclase via a Ca2+/cGMP negative feedback. While the phototransduction-associated role of GCAP1 in the photoreceptor outer segment is widely established, its implication in synaptic transmission to downstream neurons remains to be clarified. Here, we present clinical and biochemical data on a novel isolate GCAP1 variant leading to a double amino acid substitution (p.N104K and p.G105R) and associated with cone dystrophy (COD) with an unusual phenotype. Severe alterations of the electroretinogram were observed under both scotopic and photopic conditions, with a negative pattern and abnormally attenuated b-wave component. The biochemical and biophysical analysis of the heterologously expressed N104K-G105R variant corroborated by molecular dynamics simulations highlighted a severely compromised Ca2+-sensitivity, accompanied by minor structural and stability alterations. Such differences reflected on the dysregulation of both guanylate cyclase isoforms (RetGC1 and RetGC2), resulting in the constitutive activation of both enzymes at physiological levels of Ca2+. As observed with other GCAP1-associated COD, perturbation of the homeostasis of Ca2+ and cGMP may lead to the toxic accumulation of second messengers, ultimately triggering cell death. However, the abnormal electroretinogram recorded in this patient also suggested that the dysregulation of the GCAP1-cyclase complex further propagates to the synaptic terminal, thereby altering the ON-pathway related to the b-wave generation. In conclusion, the pathological phenotype may rise from a combination of second messengers' accumulation and dysfunctional synaptic communication with bipolar cells, whose molecular mechanisms remain to be clarified

Genotype-phenotype characterization of novel variants in six Italian patients with familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy (FEVR) is a complex disorder characterized by incomplete development of the retinal vasculature. Here, we report the results obtained on the spectrum of genetic variations and correlated phenotypes found in a cohort of Italian FEVR patients. Eight probands (age range 7-19 years) were assessed by genetic analysis and comprehensive age-appropriate ophthalmic examination. Genetic testing investigated the genes most widely associated in literature with FEVR: FZD4, LRP5, TSPAN12, and NDP. Clinical and genetic evaluations were extended to relatives of probands positive to genetic testing. Six out of eight probands (75%) showed a genetic variation probably related to the phenotype. We identified four novel genetic variants, one variant already described in association with Norrie disease and one previously described linked to autosomal dominant FEVR. Pedigree analysis of patients led to the classification of four autosomal dominant cases of FEVR (caused by FZD4 and TSPAN12 variants) and two X-linked FEVR probands (NDP variants). None of the patients showed variants in the LRP5 gene. This study represents the largest cohort study in Italian FEVR patients. Our findings are in agreement with the previous literature confirming that FEVR is a clinically and genetically heterogeneous retinal disorder, even when it manifests in the same family

Génération et manipulation d'états photoniques de haute dimension avec des puces AlGaAs

This thesis is devoted to the development of novel integrated semiconductor devices and methods for the generation and manipulation of high-dimensional states of light. We report on the study of an AlGaAs waveguide implementing type-II spontaneous parametric down conversion process in a monochromatic pump regime, with a focus on the joint spectral amplitude of the emitted biphoton state. The source works at room temperature, emits photon pairs in the telecom range and is compliant with electrical injection. The generation of broadband biphoton states is experimentally demonstrated via the reconstruction of the joint spectral intensity and via a Hong-Ou-Mandel experiment indicating that signal and idler photons are emitted over a large bandwidth (170nm) and with a high degree of indistinguishability (V=0.86). Moreover, we show that the cavity effect due to waveguide facets reflectivity leads to the production of biphoton frequency-comb states. This platform is used to demonstrate an original method to generate and control the symmetry of biphoton frequency combs exploiting cavity effects and a delay between the two photons of each pair. More specifically, we show that a fine tuning of the pump frequency enables the generation of resonant and anti-resonant comb states allowing to manipulate the wavefunction symmetry. The method can be adapted and applied to a large variety of systems, either bulk or integrated, thus increasing their flexibility and the richness of the generated states in view of implementation of new quantum information protocols.In addition, we demonstrate the realization of an AlGaAs ridge waveguide for the generation of light beams with tailored phase and polarization distributions, carrying spin angular momentum, and present the design of a device for the generation of a twisted light beam, carrying first order orbital angular momentum.Cette thèse est consacrée au développement de nouveaux dispositifs semi-conducteurs intégrés et de méthodes pour la génération et la manipulation d'états lumineux de haute dimension. Nous présentons l'étude d'un guide d'onde AlGaAs utilisant un processus de conversion paramétrique spontanée de type II en régime de pompage monochromatique, s’intéressant en particulier à l'amplitude spectrale jointe de l'état émis. La source fonctionne à température ambiante, émet des paires de photons dans le domaine des télécommunications et est compatible avec l'injection électrique. La génération d'états biphotoniques à large bande est démontrée expérimentalement par la reconstruction de l'intensité spectrale jointe et par une expérience de Hong-Ou-Mandel indiquant que les photons signal et complémentaire sont émis sur une large bande spectrale (170 nm) et avec un haut degré d'indiscernabilité (V=0,86). De plus, nous montrons que l'effet de cavité dû à la réflectivité des facettes des guides d'onde conduit à la production de peignes de fréquence à deux photons. Cette plateforme est utilisée pour démontrer une méthode originale de génération et de contrôle de la symétrie des états peignes exploitant les effets de cavité et un retard imposé entre les deux photons de chaque paire. Plus spécifiquement, nous montrons qu'un réglage fin de la fréquence de la pompe permet de générer des états peignes résonnants et anti-résonants permettant de manipuler la symétrie de la fonction d'onde. La méthode peut être adaptée et appliquée à une grande variété de systèmes, massifs ou intégrés, augmentant ainsi leur flexibilité et la richesse des états générés en vue de la mise en œuvre de nouveaux protocoles d'information quantique. En outre, nous démontrons la réalisation d'un guide d'onde AlGaAs pour la génération de faisceaux lumineux portant un moment angulaire de spin et présentons la conception d'un dispositif pour la génération d'un faisceau lumineux portant un moment orbital angulaire de premier ordre

Early Propensity to Migrate: A Descriptive Analysis from A Survey of Schooled Teenagers in a Southern Italian City

The brain drain from the south of Italy is a well-known and unfortunately increasingly alarming phenomenon. In recent times, the demographic decline due to migration has been coupled by a worrying decrease in the average age at which this process starts. While most of the existing literature has looked at the problem looking at migrant workers, especially in relation to their level of schooling or education, here we look at the propensity to migrate at an earlier stage of life while people are still in their secondary school studies. Using a unique field survey conducted over a large sample of students in the city of Palermo we uncover that more than three quarters of the interviewed sample would consider moving far away from the family after completing their studies. We perform a simple descriptive analysis to look at how this propensity to migrate changes depending on some individual and family characteristics of the respondents

Estimating Verdoorn law for Italian firms and regions

In empirical regional economics, returns to scale are typically estimated at the regional level in search for evidence on alternative theories of growth and agglomeration. However, returns to scale may also have a firm-level dimension. In this paper, we exploit micro level data and estimate the dynamic Verdoorn law in a multilevel-setting, where returns to scale are obtained simultaneously for the micro and the regional level. Using Italian firm-level data and the NUTS-3 level of aggregation, we estimate the classic and augmented versions ofVerdoorn lawfor the manufacturing sector, and the rest of the economy for comparison. Our results show that increasing returns to scale co-exist at both levels, with some degree of regional heterogeneity across the Italian peninsula