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Agglomeration economies and growth. The case of Italian local labour systems, 1991-2001
Get PDFThe main objective of this paper is to assess the role of a large set of factors which potentially relate agglomeration economies to local growth. Such a relationship is analysed thanks to an ample database on the case of Italy which refers to 784 Local Labour Systems and 34 sectors (21 manufacturing and 13 services) over the period 1991-2001. Econometric results show that local growth in Italy is characterized by significant differences across sectors. It is worth mentioning the positive influence of diversity externalities, human and social capital and the negative influence of specialisation externalities and competition. Spatial association is also detected
Design of optimal measurement strategies for geometric tolerances control on coordinate measuring machines
Get PDFThis study is concerned with a vast industrial problem: the inspection of physical components and subsystems for checking their conformance to dimensional and geometric tolerance specifications. Although a number of non contact optical devices are being currently developed for such a task, Coordinate Measuring Machines (CMM) are still universally adopted thanks to their superiority in terms of accuracy in the measurement of point coordinates. However, their unsurpassed metrological quality for this basic operation is counterbalanced by a fundamental problem that is plaguing practitioners in the sector of industrial metrology. The problem is usually referred to as methods divergence and can be stated as follows. On one hand, the machines probe the part surface point-wise and economic constraints force the point sample to be small. On the other end, geometric errors, as defined by tolerance standards, depend heavily on extreme values of the form deviations over the related surface so that a full-field inspection is virtually required. For example, straightness error is the minimum distance between two parallel lines enclosing the actual feature. Thus extreme points are more important than the others in determining the straightness error. This problem, translated in statistical terms, means using a small sample of form deviations to make inference on a quantity dependent on extreme values of the population, thereby unlikely to be in the sample. Thus sample-based evaluation of geometric errors is naturally prone to be substantially biased and uncertain, especially when the surfaces exhibit systematic form deviations. In spite of this, common practice in industry is to probe very few points according to very simple sampling strategy (uniform, random, stratified). The software packages sold with the machines contain algorithms of computational geometry which are selected by purely economic criteria (easy to implement, fast to compute) regardless of their implications on measurement quality. Moreover, user awareness of the importance of evaluating measurement uncertainty in the inspection of geometric tolerances is exceedingly limited. This is no wonder if we consider that the ISO committees have been working for several years on different four methods for uncertainty evaluation in CMM measurement tasks (ISO 15530 family) and still now only one standard has been officially delivered (ISO 15530-3, march 2004). Uncertainty calculation using calibrated objects)
Trust responsiveness: on the dynamics of fiduciary interactions
Get PDFTrust and trustworthiness are key elements, both at the micro and macro level, in sustaining the working of modern economies and their institutions. However, despite its centrality, trust continues to be considered as a “conceptual bumblebee”, it works in practice but not in theory. In particular, its behavioural rationale still represents a puzzle for traditional rational choice theory and game theory. In this paper “trust responsiveness”, an alternative explanatory principle that can account for trustful and trustworthy behaviour, is proposed. Such principle assumes that people can be motivated to behave trustworthily by trustful actions. The paper discusses the philosophical roots, the historical development, as well as the relational nature of this principle as well as its theoretical implications
Tourism specialization and environmental sustainability in a dynamic economy
Get PDFThis study focuses on the dynamic behaviour of a small open economy specialized in tourism based on natural resources when tourist services are supplied to foreign tourists who are crowding-averse and care for the environment. We analyse the steady-state properties of the model and a unique locally saddle-point equilibrium is found for both the market and the central planner solution. Then we compare the effects of two policies aiming at improving the market solution: in the first the government poses a corective tax on residents'income and then redistributes the tax gains with lump-sum transfers while, in the second, the government taxes residents'income and employs the tax gains in pollution abatement technology. We find that the first policy is able to direct the economy towards its first-best dynamic path but the second policy, by relaxing the dynamic constraint on the environment, yields a higher steady-state utility when the externality effects and/or the natural regeneration rate of the environmental asset are low enough. Both policies, insofar they lead to an increase in tourists' willingness to pay, might work as an "implicit" tourist tax paid by tourists, with the difference that the first policy always leads to to this result, while the second obtains it only when tourists' aversion to crowding is not too high
Taxonomic revision of the Astragalus genargenteus complex (Fabaceae)
Get PDFWithin the Astragalus genargenteus complex three morphologically, ecologically and chorologically
well differentiated taxa are distinguished: A. genargenteus from siliceous substrate in the Gennargentu
massif (central Sardinia) and two species described as new to science, A. gennarii from limestone on
Monte Albo (NE Sardinia) and A. greuteri, widespread on siliceous substrate in the Corsican mountains.
The relationship of these species with the allied, spine cushion-like A. sirinicus and A. angustifolius
is examined. A key to the species and illustrations are given
Analisi molecolare in pazienti italiani con sindrome di Lowe
Get PDFThe oculocerebrorenal syndrome of Lowe (OCRL, also called OCRL1) is a rare X-linked disorder characterized by major abnormalities of eyes, nervous system, and kidneys. The gene responsible for OCRL encodes an inositol polyphosphate-5-phosphatase. We performed the molecular analysis in 20 Italian patients and we detected the mutations in all the examined patients. Sixteen mutations out of twenty consisted of truncating mutations (frameshift, nonsense, splice site and genomic deletion), and four were missense mutations. The mutations were distributed in the second half of the gene as previously described in other populations. Our results on the Italian population are similar to the data previously obtained in other populations. Herein, we also report a family with extremely skewed X inactivation that produced the full phenotype of Lowe syndrome in a female. The X chromosome inactivation studies detected an extremely skewed inactivation pattern with a ratio of 100:0 in the propositus as well as in five out of seven unaffected female relatives in four generations. The OCRL1 "de novo" mutation resides in the active paternally inherited X chromosome. X chromosome haplotype analysis suggests the presence of a locus for the familial skewed X inactivation in chromosome Xq25 most likely controlling X chromosome choice in X inactivation or cell proliferation
The effects of public capital on the productivy of the italian regions
Get PDFThis paper investigates on the role played by public capital in increasing the productivity levels in Italy. For the construction of the regional series for the public capital stock over the period 1996-2003, the study benefits from the use of the rich dataset on public expenditure, recently published by the Italian Ministry of Economy. We have estimated panel production functions with the inclusion of traditional factors and also intangible inputs like R&D expenditure, human capital and social capital. The results point out that public capital has a positive and significant effect on production. Moreover, the effects of all production factors vary considerably between the two macro-areas of the country, namely Centre-North and Mezzogiorno. More specifically, while private capital is more effective in the South, labour and public capital exhibits an elasticity much higher in the Centre-North with respect to the Mezzogiorno. The disaggregation of the public capital stock into economic categories indicates a significant different impact in the two macro-areas. When the analysis is carried out by distinguishing among government levels it turns out that the decentralized administrative bodies are much less efficient in the South in delivering public expenditure
Flora vascolare del Sulcis(Sardegna Sud-Occidentale, Italia)
Get PDFThe vascular flora of Sulcis (South-West Sardinia) has been studied. 1479 taxa have been found. 1235 were species, 210 subspecies, 24 varieties and 10 hybrids, belonging to 584 genera and 130 families. The Dicotyledones with 91 families, 429 genera and 1084 taxonomic units were dominant over the other systematic groups. The most represented families are: Fabaceae (153 taxonomic units), Poaceae (151), Asteraceae (146), Apiaceae (59), Caryophyllaceae (56)
and Brassicaceae (53). The most represented genera are: Trifolium (28), Ranunculus (22), Vicia (20), Juncus and Allium (19), Medicago and Carex (17), Silene and Ophrys (16), Euphorbia (15).The floristic richness indices have been determined and compared with those of other studied areas of Sulcis. An analysis of the biological spectrum showed the therophytes at 41.3% confirming the full Mediterranean character of the area, and the phanerophytes at 8.0%, showing a high level of forest area. Acomparison
with the biological spectra of other floras shows similar values, except for a higher value for the therophytes and hydrophytes (3%). The chorological spectrum shows the dominance of Mediterranean elements (74.2%), particularly
Steno-Mediterranean (30.5%) and Euro-Mediterranean (22.5%). The western-Mediterranean (11%), Atlantic-Mediterranean (6.4%) and the southern-Mediterranean (4.5%) components are important in identifying the biogeographic barycentre of the studied area. The contingent of endemics (138 taxonomic units) was 12.6% of the Mediterranean component which shows the dominance of Sardinian-Corsican (31.1%) and Sardinian (30.5%) elements, that together make up 61.6% of the total. This flora consists of 93 species, 32 subspecies, 10 varieties and 3 hybrids; belonging to 88 genera and 37 families. The most represented families are: Asteraceae (18), Orchidaceae (12), Fabaceae (11) and the Scrophulariaceae (10). The most represented genera are: Ophrys (10), Limonium (8) and Genista (7). The analysis of biological and chorological data highlighted the environmental peculiarities of Sulcis, shown by the local evolution of a rich floristic contingent. Eighteen exclusive endemics, together with a unique blend of geolithologic, geomorphologic, paleogeographic, bioclimatic and vegetation features, allow the attribution of the rank of biogeographic sector to the Sulcis-Iglesiente territory. The southern part, with seven exclusive endemics, Anchusa
formosa, Genista bocchierii, G. insularis subsp. insularis, Limonium carisae, L.malfatanicum, L. tigulianum, Silene martinolii, can be seen as the Sulcis subsector. A contribution regarding the phytotoponymy of the Sulcis area is presented here. 394 vegetal place names have been counted in a census, referring to 89 taxonomic units (8.8% of the Sulcis flora). Most of these are written in Campidanese dialect and the refer to entities frequently found in the territory. The most recurrent species are: Olea europaea s.l. (25), Arbutus unedo (18), Cistus
sp. pl. (18), Myrtus communis subsp. communis (17), Quercus suber (16) and Juniperus oxycedrus subsp. oxycedrus (9). The most represented species are shrubs (37.6%) and trees (35.9%) spontaneous and cultivated, most of them calcifuge. Only in the far western areas is it possible to find calcicole taxa linked to sedimentary substrata of a carbonated nature.From research carried out it appears that in the IGM plans, in scale 1:25.000, the greater number of
phytotoponymy are in Capoterra (68), Narcao (52), and the Santadi and Carbonia areas both with 39. For the emblematic tree, 42 plants (only 16 discovered in the past) have been
counted and studied. The most represented species are: Taxus baccata (7), Ceratonia siliqua (4), Eucalyptus camaldulensis (4), Juniperus oxycedrus subsp. oxycedrus (4) and Quercus ilex (4)
Caratterizzazione fisica e qualificazione geomeccanica dell'ammasso roccioso costituente il fronte di scavo di una miniera d'argillite a Sadali (Sarcidano, Sardegna centro-orientale)
Get PDFThe acquisition and analysis of the physical and mechanical properties and
geostructural character of the rocks, that constitute the excavation front of a argillite's
quarry for ceramics near to Sadali, has allowed the geomechanical characterization of
the dolomitic rocky mass and the argillitic formation below. The front is, at the moment,
potentially unstable, with the collapse of dolomitic rock's blocks on the squares of the
quarry. Instability has been certainly caused by a lack of basal support that interests
main part of the front extension. The analysis of the dolomitic rocky mass has been faced
applying the Classification of Bieniawski, in way to establish its geomechanical quality.
The optimal solution to put in safety the front is the restoration of the basal support,
through the realization of a terrace and a superficial drain system