Classification results for biharmonic submanifolds in spheres

We classify biharmonic submanifolds with certain geometric properties in Euclidean spheres. For codimension 1, we determine the biharmonic hypersurfaces with at most two distinct principal curvatures and the conformally flat biharmonic hypersurfaces. We obtain some rigidity results for pseudo-umbilical biharmonic submanifolds of codimension 2 and for biharmonic surfaces with parallel mean curvature vector field. We also study the type, in the sense of B-Y. Chen, of compact proper biharmonic submanifolds with constant mean curvature in spheres.Comment: Dedicated to Professor Vasile Oproiu on his 65th birthday, 14 page

Collateral and risk sharing in group lending: evidence from an urban microcredit program

Empirical research on group lending is extensive, but without allowance for collateral to mitigate strategic default. Indeed, lack of credit access has motivated microcredit in rural areas of developing countries, where agents with collateral are very rare. As rural communities have tight-knit hierarchical structures information about borrowers is accessible and enforcement of social sanctions makes collateral superfluous. First, we illustrate in a model how collateral mitigates group default. Second, we study a group lending program in Cotonou, the largest city in Benin with 1.1 million inhabitants. Results show diversification within groups facilitating risk pooling but also increasing expected default costs for safe borrowers. Risky borrowers offset group-default negative spillovers default with collateral, and facilitate credit access to safe borrowers. We find joint liability to be a mechanism for risk sharing in a setting where poor households lack resources for collateral and insurance markets are missing

Some Econometric Issues In Convergence Regressions

Despite the abundance of different econometric techniques introduced in the empirical literature on convergence, it is usually assumed that shocks are uncorrelated across countries. This is surely unlikely for most of the datasets considered and we investigate a possibility so far ignored, namely the annual panel estimator where shocks are allowed to be correlated across countries. Our analysis is restricted to the case of more time periods than countries (T>N) which allows us to estimate by Maximum Likelihood with an unrestricted variance-covariance matrix of cross-country shocks. The paper examines by Monte Carlo robustness against certain possible mis-specifications, namely measurement error and heterogeneity of the convergence coefficients. Our analysis indicates that ML estimators are robust to plausible measurement error and variation of convergence rates across countries and are more efficient than conventional estimators for plausible values of cross-country error correlation. We consider in detail the relationship between the distribution of the ML estimator and the initial conditions. Applying our findings to a panel of OECD countries for the post-war period, we show that ML is effectively unbiased and more efficient than or conventional panel estimators OLS on a cross-section of countries. We argue the reason this estimators is so well behaved is that many OECD countries were far from their equilibrium values at the beginning of the period

Titolazioni chelometriche con EDTA: considerazioni sul grafico di Reilley

Theory and procedure on which Reilley curve is based are discussed; it defines the minimum pH for an effective metal titration with EDTA. This curve, widely reported in Analytical Chemistry textbooks, was originally presented in an implicit way by Reilley, who assumed a 106 conditional constant for 0.01 M metal concentration. We report here the conditional constants necessary for 99, 99.9 and 99.99 complex formation percentage at various analytical concentration. An updated Reilley plot is furthermore presented, which takes into consideration all formation constants at 20°C reported till 1998 for EDTA complexes

Il Caucaso, transizione politica ed economica. Una analisi transfrontaliera.

Southern Caucasus (Transcaucasia) is a dichotomous region. The states forming this area are characterized by deep dissimilarities, but at the same time they share part of their past and many of their future expectations. A common historical legacy, together with a particular people's Weltanschauung and a geographic contiguity render Georgja, Armenia and Azerbaijan a group of countries that are united in their several differences. The aim of this PhD Thesís is the study of the political and economic transition of Armenia, Georgia and Azerbaijan. On the basis of the potitical science, social studies, economic development and the transition scientific literature, some structural indicators have been chosen in order to elaborate a macro-analysis on their present level of democratic and economic development. As for the economic section, comparative analyses of the economic and financial performances have been adopted. The results of this studies and the analysis of the indicators have been submitted to the scrutiny of a group of scholars coming from Armenia, Georgia, Azerbaijan, Russian Federation and Europe, composing a so-called DELPHI Group. The main goal was to have an impartial and scientific opinion about the quality of the analysis. The results indicating the different level of the structural development (also summarised in a numerical coefficient) allowed giving the three countries a "democracy score", commonly used by the scientific community. The analysis alIowed to classify Georgia and Armenia as hybrid regimes, in which the potential for sustainable, liberal democracy is unclear, corruption is widespread and presents a major impediment to political and economic development. As for Azerbaijan it was defined as a semi-consolidated authoritarian regme, in which it failed to meet even the minimum standards of electoral democracy, State presence in the economic sector and widespread corruption represent an obstacle for development. Political and economic transition of Transcaucasian countries seems to have a checkered trend, because there are still too many systemic internal fractures characterizing in these countries and too many international components can act and/or dominate their individual choices

Associazione tra i polimorfismi dei geni NOD2/CARD15, TLR-4, IL23R e GVHD, infezioni e mortalità precoce nel trapianto allogenico di cellule staminali ematopoietiche nella popolazione pediatrica sarda talassemica, ampliamento del progetto con lo studio molecolare di altri geni candidati

Recently single nucleotide polymorphisms (SNPs) of the genes NOD2-CARD15, IL23-R and TLR-4 have been showed to influence the risk for acute GvHD in patients who underwent to allogeneic hematopoietic stem cells (HSCs) transplantation. To investigate whether these genes play a role in the pathogenesis of GvHD also in the Sardinian population, 8 SNPs four for NOD2, two for TLR4 and two for IL23R in 86 recipients, their coupled donors and in 150 healthy Sardinians individualswere genotyped and the SNPs frequencies compared. The SNP rs2066842 of NOD2 gene was significantly increased in the group of patients who did not develop acute GvHD(p = 0.002). Our data, if confirmed in GvHD patients from other population, could suggest the inclusion of the non-HLA NOD2/CARD15 genes genotyping in the attribution of the immunological donor/recipient pre-transplant score

Stima della Domanda Turistica nel Parco Marino della Maddalena: un'Applicazione del Metodo della Valutazione Contingente

In questo lavoro si utilizza il metodo della valutazione contingente per stimare il potenziale incremento della domanda turistica nel territorio della Maddalena, in seguito alla creazione del Parco Marino. Dopo una discussione di alcuni aspetti metodologici, viene presentata l’analisi econometrica dei dati. Vengono stimate e testate diverse specificazioni di un modello generale di tipo Tobit. I risultati mostrano che, condizionatamente alla creazione di specifici servizi turistici, le potenzialità della domanda sono interessanti

Estimation of total factor productivity for regions and sectors in Italy. A panel cointegration approach

In this paper a complete set of estimates of long-run production functions for 20 regions and 17 sectors in Italy is provided over the period 1970-1994. Our approach features two important aspects. First, this paper represents the first attempt to provide such a comprehensive set of estimates for the Italian economy. Moreover, we allow the estimated production functions for heterogeneity across sectors and regions. This is particularly appropriate when analysing the Italian economy since the Italian regions have been experiencing fairly different and, in certain cases, divergent development paths. Secondly, on the basis of specific panel tests, we show that there is a considerable empirical evidence which suggests the presence of unit roots in our series; therefore, we apply panel cointegration tests to guard against the spurious regression problem and to detect long-run relationships. Evidence of long run relationships is found for most of the regions and the sectors on the basis of the cointegration tests; thus, the problem of spurious regressions is ruled out allowing us to offer rigorous inference on the estimation of regional production functions. We find that factor elasticities highly differ across regions and sectors. This is an important result since most previous studies by employing unique national elasticities introduce a serious bias in the productivity comparison

Indagine fitosociologica sulle praterie a Brachypodium Retusum (Pers.) beauv. della Sardegna

The grasslands characterized by the dominance of Brachypodium retusum occurring in Sardinia are examined. These communities, belonging to the Thero-Brachypodion ramosi alliance (Lygeo-Stipetea class), are quite widespread in the Island, where they usually grow on carbonate substrata from the sea level up to 1300 m of altitude. On the basis of several phytosociological relevés, it has been possible to recognize six associations well-differentiated from the floristic, ecological and syndynamic point of view. The autonomy of these associations is also supported by a numerical multivariate analysis based on quantitative data (dendrogram and P.C.A.). The associations surveyed are the following: Dorycnio suffruticosi-Stipetum offneri ass. nova, localized on summit plateaux at an altitude of 700-1200 m (CE Sardinia), Stipo bromoidis-Astragaletum verrucosi ass. nova, very rare and circumscribed to the coastal hills (W Sardinia), Triseto splendentis-Brachypodietum retusi ass. nova, colonizing more or less stabilized screes at 200-900 m of altitude (NE Sardinia), Asphodelo africani-Brachypodietum ramosi Biondi & Mossa 1992 corr., thermo-xerophilous community linked to coastal stands (S Sardinia), Ranunculo graminei-Brachypodietum retusi ass. nova, orophilous community growing on jointed rocky places at an altitude of 1100-1300 m (CE Sardinia), Melico ciliatae-Brachypodietum retusi ass. nova, found on the coastal screes of Figarolo islet (NE Sardinia). Besides, a floristic comparison among the hitherto known associations belonging to this alliance is given

Identificazione di una variante missenso nel gene RBM10 in una famiglia sarda con disabilità intellettiva X-linked

X-linked intellectual disability (XLID) is a heterogeneous disorder, and mutations causing monogenic XLID have now been reported in over 100 genes. We report a five-generation Sardinian family in which seven affected male family members had intellectual disability and craniofacial dysmorphisms. Large-scale next generation exome resequencing of X chromosome genes detected a rare missense variant (c.995G>A, p.Arg332His) located within a highly conserved domain in the RBM10 gene at Xp11.23. Sanger sequencing confirmed the presence of the variant in affected males and in their mothers. The variant was not present in non affected male family members, has not been reported in variant databases and is disease-causing according to a web-based prediction tool. RBM10 is an RNA binding protein involved in the regulation of transcription, alternative splicing and message stabilization. RBM10 nonsense and frameshift mutations are associated with TARP syndrome characterized by Talipes equinovarus, Atrial septal defect, Robin sequence and Persistence of the left superior vena cava and pre- or postnatal lethality in affected males. RBM10 has not been reported in XLID patients until now. Genic intolerance score suggested that RBM10 may be “intolerant” of functional mutations. Although our finding suggest that RBM10 is a reasonable candidate gene for XLID, functional studies and mutations screening in other patients are needed to prove a definite causal relationship between the variant and the phenotype