Bulge properties and dark matter content of early-type barred galaxies

The dynamics of a barred galaxy depends on the pattern speed of its bar. The only direct method for measuring the pattern speed of a bar is the Tremaine-Weinberg technique. This method is best suited to the analysis of the distribution and dynamics of the stellar component. Therefore it has been mostly used for early-type barred galaxies. Most of them host a classical bulge. On the other hand, a variety of indirect methods, which are based on the analysis of the distribution and dynamics of the gaseous component, has been used to measure the bar pattern speed in late-type barred galaxies. Nearly all the measured bars are as rapidly rotating as they can be. By comparing this result with high-resolution numerical simulations of bars in dark matter halos, it is possible to conclude that these bars reside in maximal disks.Comment: 4 pages. To appear in the proceedings of IAU Symposium 245 "Formation and Evolution of Galaxy Bulges", M. Bureau, E. Athanassoula, and B. Barbuy, ed

Counter-Rotation in Disk Galaxies

Counter-rotating galaxies host two components rotating in opposite directions with respect to each other. The kinematic and morphological properties of lenticulars and spirals hosting counter-rotating components are reviewed. Statistics of the counter-rotating galaxies and analysis of their stellar populations provide constraints on the formation scenarios which include both environmental and internal processes.Comment: 10 pages, 2 figures. To appear in ASP Conf. Ser., Multi-Spin Galaxies, E. Iodice and E. M. Corsini (eds.

Direct measurements of bar pattern speeds

The dynamics of a barred galaxy depends on the angular velocity or pattern speed of its bar. Indeed, it is related to the location of corotation where gravitational and centrifugal forces cancel out in the rest frame of the bar. The only direct method for measuring the bar pattern speed is the Tremaine-Weinberg technique. This method is best suited to the analysis of the distribution and kinematics of the stellar component in absence of significant star formation and patchy dust obscuration. Therefore, it has been mostly used for early-type barred galaxies. The main sources of uncertainties on the directly-measured bar pattern speeds are discussed. There are attempts to overcome the selection bias of the current sample of direct measurements by extending the application of the Tremaine-Weinberg method to the gaseous component. Furthermore, there is a variety of indirect methods which are based on the analysis of the gas distribution and kinematics. They have been largely used to measure the bar pattern speed in late-type barred galaxies. Nearly all the bars measured with direct and indirect methods end close to their corotation radius, i.e., they are as rapidly rotating as they can be.Comment: 8 pages, 1 figure. To appear in "Tumbling, twisting, and winding galaxies: Pattern speeds along the Hubble sequence", E. M. Corsini and V. P. Debattista (eds.), Memorie della Societa` Astronomica Italian

The dark matter content of early-type barred galaxies

The dynamics of a barred galaxy depends on the pattern speed of its bar. The only direct method for measuring the pattern speed of a bar is the Tremaine-Weinberg technique. This method relies on the analysis of the distribution and dynamics of the stellar component. It is best suited to gas-poor galaxies and therefore it has been restricted to early-type barred galaxies. On the other hand, a variety of indirect methods, which are based on the analysis of the distribution and dynamics of the gaseous component, has been used to measure the bar pattern speed in late-type barred galaxies. The complete sample of galaxies for which the bar pattern speed has been directly measured with the Tremaine-Weinberg method is given. Nearly all the measured bars are as rapidly rotating as they can be. By comparing this result with recent high-resolution N-body simulations of bars in cosmologically-motivated dark matter halos, it is possible to conclude that these bars are not located inside centrally-concentrated halos.Comment: 5 pages. Proceedings of "Baryons in Dark Matter Halos". Novigrad, Croatia, 5-9 Oct 2004. Editors: R. Dettmar, U. Klein, P. Salucci. Published by SISS

Institutions, Technological Change and the Wage Differentials Between Skilled and Unskilled Workers: Theory and Evidence from Europe

We study the evolution of the wage differentials between graduate (skilled) and non graduate (unskilled) workers in several european countries in the period that range from the beginning of the nineties to the beginning of this century. The starting point is that all european countries show an increasing relative supply of skilled workers but different behaviours of the wage differentials. The standard explanation for non decreasing differentials in the face of rising relative supply is that technological progress is skill biased. This in turn would imply that technological progress differs in its magnitude and effects across Europe. Our finding shows that what is relevant in the determination of the differentials it is the pace and intensity at which technological progress takes place. We turn then to institutions and we build a model of imperfect competition and wage bargaining which relate the differentials to the technological progress but also to several labour market institutions. The empirical analysis on this aspect reveal that employment rates of different groups as well as the union density and the generosity of unemployment benefits are indeed important and help in explaining the evolution of the wage differentials between skilled and unskilled workers.Wage Differentials ; Technological Changes ; Labor Market Institutions

Unemployment Insurance Schemes, Liquidity Constraints and Re-employment: a three Country Comparison

We examine how unemployment schemes and liquidity constraints affect re-employment probabilities and unemployment duration. In particular we investigate to which extent those schemes, through employment services and search requirements, can offset the expected perverse effect of benefits on reservation wages and search effort. Similarly, given that liquidity constraints and financial pressure should also affect reservation wage and search effort we analyze whether better economic conditions of individuals actually increase duration. We perform the analysis on Finland, Italy and Poland, countries that displays significant differences both in the UI schemes generosity and eligibility criteria and in the overall degree of social wealth and economic prosperity. Using a sample of newly unemployed from these countries, we perform and estimation of Cox hazard models and assess what variables are important in determining unemployment duration. Our findings suggest that even correctly designed UI schemes have a mixed effect: initially they give incentive to increase search effort, as the eligibility criteria impose certain search requirements, but with time they simply reduces liquidity constraints and thus increase duration. As for the direct effect of liquidity constraints and financial pressure we found that in Italy and Poland they appear to reduce unemployment duration but they are not relevant in Finland, suggesting that these aspects are not so important in countries that are particularly rich and with a developed welfare system.Unemployment Insurance, Liquidity constraints, Re-employment, Unemployment Duration

Unsteady end-wall pressure measurements using near-field diy sensors on fouled fan rotor blade

The fouling is identifiable by the presence of dust on rotor and stator blades, and its main origin, in industrial turbomachinery, is the presence of a film of moist or lubricant driven to the trailing edge by the near-wall flow, or centrifuged toward the casing by impeller rotation. Solid particles pile up on them, leading to eccentricity and load unbalance. The formation of build-up results in performance reduction, and the chance of a deposit detachment while the impeller spun, may cause damages due to the impact on the machine parts. In industrial fans, the presence of fouling influences the characteristic curve and could anticipate stall when the flow rate is throttled. Rotating stall is an aerodynamic instability with a typical frequency about half the rotor frequency, acoustically identifiable from the changes in the emitted rotor noise, due to displacement from the stability. This work investigates rotating stall dynamics on an axial fan with fouled blades. The stall is identified with time-resolved pseudo-sound measurements in the end-wall region using DIY sensors. The signals have been analysed in frequency domain, and time domain using a phase space reconstruction technique. It is demonstrated a modification of the dynamic to stall and are identified diverse stall precursors

Optimal decisions on pension plans in the presence of financial literacy costs and income inequalities

Pension reforms are on the political agenda of many countries. Such reforms imply an increasing responsibility on individuals’ side in building an efficient portfolio for retirement. In this paper we provide a model describing workers’ choices on the allocation of retirement savings in presence of a) mandatory contribution; b) portfolio decision; c) financial literacy costs. In particular, we characterise the results both from a positive and normative standpoint, by highlighting the determinants of the individual’s choice, with special focus on financial literacy costs and wage level inequalities and by characterizing the optimal contribution rate to mandatory complementary pension schemes.Financial literacy; Choice on pension Plans; Optimal portfolio composition; Income inequality.