Wealth Polarization and Pulverization in Fractal Societies.

In this paper we study the geometrical properties of the support of the limit distributions of income/wealth in economies with uninsurable individual risk, and how they are affected by technology and preference parameters and by policy variables. We work out two simple successive generation models with stochastic human capital accumulation and with R&D and we prove that intense technological progress makes the support of the wealth distribution converge to a fractal Cantor-like set. Such limit distribution implies the disappearance of the middle class, with a “gap” between two polarized wealth clusters that widens as the growth rate becomes higher. Hence, we claim that in a highly meritocratic world in which the payoff of the successful individuals is high enough, and in which social mobility is strong, societies tend to look highly “fractalized”. We also show that a redistribution scheme financed by proportional taxation does not help cure society’s disconnection/polarization; on the contrary, it might increase it. Finally we show that these results are not confined to our analytically worked out examples but are easily extended to a widely used class of macroeconomic and growth models.Inequality and Growth; Education; Technological Change; Wealth Polarization/ Pulverization; Iterated Function System; Attractor; Fractal; Cantor Set; Invariant Distribution

Günther Anders Dall’uomo senza mondo al mondo senza uomo.

Il lavoro si propone di ricostruire il percorso intellettuale di Günther Anders (1902-1992), un autore rimasto per lungo tempo ai margini della cultura filosofica del ‘900, analizzandone la ricca produzione saggistico-letteraria, attraverso la chiave interpretativa riassunta dal sottotitolo: “Dall’uomo senza mondo al mondo senza uomo”. Anders pone infatti al centro delle sue prime riflessioni la condizione di estraneità dell’uomo nel mondo. Questo tema è declinato sia attraverso un confronto con Heidegger (del quale critica la tendenza a privilegiare un rapporto esclusivamente speculativo, pseudo-concreto, con il mondo), sia attraverso l’analisi di alcuni autori della letteratura tedesca (Döblin e Kafka in particolare), sia soprattutto attraverso le riflessioni sul fenomeno della tecnica. Il senso complessivo degli effetti sulla vita dell’uomo delle straordinarie trasformazioni generate dalla tecnica si può riassumere infatti per Anders nell’idea di “perdita di esperienza”. Attraverso una pionieristica analisi del mezzo televisivo da un lato, della nuova forma che assumono il lavoro e l’agire all’interno del mondo tecnico (sintetizzata nel concetto di medialità) dall’altro, Anders verifica la progressiva perdita di rapporto con il mondo da parte dell’uomo. La tecnica diviene dunque il fulcro degli interessi teorici di Anders: in una serie di saggi (che andranno a comporre i due volumi di L’uomo è antiquato, forse il suo testo più significativo), egli analizza, con riflessioni dal sapore heideggeriano, la forza impositiva della tecnica, che diviene il vero soggetto della storia. Sulla base di queste considerazioni e soprattutto sull’onda dello shock dello scoppio della prima bomba atomica su Hiroshima, Anders si volge a quella che considera la ‘svolta’ della propria vita, il rovesciamento dell’originario tema: dall’uomo senza mondo al mondo senza uomo. La tecnica infatti, dopo aver resa superflua l’esperienza per l’uomo, minaccia, trasformatasi in un processo autonomo ed ineluttabile, di rendere superfluo l’uomo stesso: sia nel senso di esautorarne la soggettività, sia nel senso di minacciarne l’esistenza fisica attraverso la possibilità dell’olocausto nucleare. Sventare questa minaccia diventa dunque lo scopo della seconda parte della vita di Anders: ad esso dedica l’impegno militante a fianco del movimento antinucleare ( che culminerà con una discussa presa di posizione a favore dell’uso della violenza) ed una serie di riflessioni, che sfociano nella proposta di considerare il potenziamento della fantasia e dell’immaginazione come lo strumento principale a disposizione dell’uomo per superare quello stato di passività emotiva e di cecità che gli impedisce di comprendere la pericolosità di un mondo tecnicizzato e nuclearizzat

Surface Pyrolysis of High Energy Materials

The Arrhenius zero-order phenomenological pyrolysis law, commonly used in conjunction with the Vieille ballistic law to study pressure-driven burning of energetic materials, is revisited. Motivated by experimental and theoretical work performed in 1984 in this Laboratory , a relationship among several interplaying parameters is found under steady-state conditions. This relationship corresponds to the Jacobian of the pyrolysis sensitivity parameters used in the Zeldovich-Novozhilov approach. The Arrhenius pyrolysis is still expressed in terms of a global surface activation energy, but consistency with the experimental ballistic law may require an explicit pressure dependence as well. This conclusion is supported by a variety of arguments drawn from different areas. The linear dependence of the pre-exponential factor on surface activation energy (known as kinetic compensation) is proved and extended to the pressure exponent, for any given experimental data set under steady burning. Experimental results are reported for about a dozen solid propellants of different nature. The effects of surface pyrolysis explicit pressure dependence, although modest on steady-state burning, are potentially far-reaching for unsteady regime and/or unstable burning. The paper is mainly focussed on pressure-driven burning and Arrhenius pyrolysis, but the implemented method is believed to apply in general. Thus, enforcing KTSS zero-order phenomenological pyrolysis with the Vieille ballistic law yields similar results and requires an explicit pressure dependence. In case, the Zeldovich ballistic law is enforced instead of the classical Vieille law, no explicit pressure dependence is required. The unifying concept for these different trends is the pyrolysis Jacobian as a consistency requirement between the implemented steady pyrolysis and ballistic laws.

Development of a Background-Oriented Schlieren Technique with Telecentric Lenses for Supersonic Flow

Background oriented schlieren (BOS) is a quantitative optical technique which exploits light deflection occurring in non-homogeneous transparent media. It allows to indirectly measure the density gradients by analysing the apparent displacement of features of a background pattern when imaged through the investigated flow. Thanks to its simple set-up and to the consolidated data reduction technique based on cross-correlation algorithms the BOS technique has progressively attracted the interest of the researchers. In this work a BOS system using a telecentric lens system has been set up in order to improve measurement accuracy and to avoid 3D effects arising from using conventional entocentric lenses. The design of the telecentric lens system is reported along with an analysis of its performance in term of spatial resolution. Some preliminary tests on a supersonic flows are also reported

Seasonal cycles of pH and carbonate system parameters in the southern Adriatic Sea during one year of VECTOR project

Within the VECTOR project (activity 8.1.2) the pH and other physical chemical parameters were acquired as seasonal time series from September 2007 to June 2008, at the AM1 station (in the centre of the Southern Adriatic Pit). The pH was measured by the spectrophotometric method (precision ? 0.003) and the results expressed on "total scale" at 25?C (pHT@25?C). In a few seasons also the total alkalinity (AT) was measured by potentiometric titration at 25?C (precision ? 3 Qmol/kg) and the results were checked against sea water certified as reference material (by dr. A.G. Dickson). The other derived parameters of the carbonate system (pCO2, DIC, lAr, lCa) were computed from pH, TA, salinity, temperature, SiO2, PO4 according to Lewis and Wallace 98. The pH seasonal variability was the highest in the upper layer (0-100 m), as clearly recognizable in fig 1a, b being the pH value mainly driven by biology during the productive seasons (from spring to late summer) or by mixing with deeper waters and exchange processes with atmosphere in winter. In the deeper layers (intermediate and bottom) the seasonal variability was lower but not negligible, probably driven by remineralization processes of dissolved and particulate organic matter locally produced, as suggested by Apparent Oxygen Utilization (AOU) and nitrate seasonal variabilities (fig. 1c, d, e, f). Generally, the highest differences of physical and biogeochemical properties can be observed in both the upper (0-100m ) and the intermediate (100-800 m) layers in September and June whereas during wintry season (January and February) variabilities were much lower. Through early to late summer season, the nutrients pH and dissolved inorganic carbon (TCO2) all suggest that both layers are strongly affected by biology (quite active primary production in the upper layer although in general the region has to be considered oligotrophic, and remineralisation processes in the intermediate layer). As confirmed by the good correlation with AOU and fluorescence. The vertical variabilities of such parameters are large, representing the 28 %, 0.4 %, -115 % of the total amount. Narrower changes can be observed passing from the intermediate to the bottom layer (800 - bottom) in January, February and June. A good correlation between changes of nutrients, pH, carbonate system and AOU is still observed, indicating the significant contribution of remineralisation processes to the final values. The physical and biogeochemical differences between the intermediate and the bottom layer further suggest that water masses of different origin filled these two layers. The persistence of inter layers variability through the year might suggest the absence of any abrupt change in the circulation scheme. The three forms of carbon dioxide in seawater (TCO2 aq, HCO3 -, CO3 = ) and the saturation states of calcite and aragonite were computed, from the experimental measures of pH and total alkalinity (reported in table 1) along the water column, in February June and October 2008. Values at surface show to be higher than the surface values of other oceanic regions, this is due to the higher alkalinity of the Mediterranean Sea, thus confirming peculiar characteristics of the carbonate system and the good saturation states of the Med Sea and southern Adriatic sea in particular

Quantitative visualization of oil-water mixture behind sudden expansion by high speed camera

The present work describes the application of an image processing technique to study the two phase flow of high viscous oil and water through a sudden expansion. Six different operating conditions were considered, depending on input volume fraction of phases, and all of them are resulting in a flow pattern of the type oil dispersion in continuous water flow. The objective is to use an optical diagnostic method, with a high speed camera, to give detailed information about the flow field and spatial distribution, such as instantaneous velocity and in situ phase fraction. Artificial tracer particles were not used due to the fact that oil drops can be easily distinguished from the continuous water phase and thus they can act as natural tracers. The pipe has a total length of 11 meters and the abrupt sudden expansion is placed at a distance equal to 6 meters from the inlet section, to ensure that the flow is fully developed when it reaches the singularity. Upstream and downstream pipes have 30 mm and 50 mm i.d., respectively. Velocity profiles, holdup and drop size distribution after the sudden expansion were analyzed and compared with literature models and results

Preliminary characterization of an expanding flow of siloxane vapor MDM

The early experimental results on the characterization of expanding flows of siloxane vapor MDM (C8H24O2Si3, octamethyltrisiloxane) are presented. The measurements were performed on the Test Rig for Organic VApors (TROVA) at the CREA Laboratory of Politecnico di Milano. The TROVA test-rig was built in order to investigate the non-ideal compressible-fluid behavior of typical expanding flows occurring within organic Rankine cycles (ORC) turbine passages. The test rig implements a batch Rankine cycle where a planar converging-diverging nozzle replaces the turbine and represents a test section. Investigations related to both fields of non-ideal compressible-fluid dynamics fundamentals and turbomachinery are allowed. The nozzle can be operated with different working fluids and operating conditions aiming at measuring independently the pressure, the temperature and the velocity field and thus providing data to verify the thermo-fluid dynamic models adopted to predict the behavior of these flows. The limiting values of pressure and temperature are 50 bar and 400 °C respectively. The early measurements are performed along the nozzle axis, where an isentropic process is expected to occur. In particular, the results reported here refer to the nozzle operated in adapted conditions using the siloxane vapor MDM as working fluid in thermodynamic regions where mild to medium non-ideal compressible-fluid effects are present. Both total temperature and total pressure of the nozzle are measured upstream of the test section, while static pressure are measured along the nozzle axis. Schlieren visualizations are also carried out in order to complement the pressure measurement with information about the 2D density gradient field. The Laser Doppler Velocimetry technique is planned to be used in the future for velocity measurements. The measured flow field has also been interpreted by resorting to the quasi-one-dimensional theory and two dimensional CFD viscous calculation. In both cases state-of-the-art thermodynamic models were applied

The importance of the fresh water outflow on a station situated in front of the Po river (Po di Goro)

The fractions of dissolved organic and inorganic nitrogen and phosphorus in sea water samples were monitored at the station S1, placed in front of the Po River mouth (44?44\u2770"N, 12?27\u2741"E). The aim was to extent our knowledge about the biochemical situation in an area that is highly influenced by fresh water loads by the .. 288 largest Italian river, and to estimate the portions of organic and inorganic nitrogen and phosphorus that were lost from the System due to physical and biochemical interactions. For this purpose, we chose to examine a sampling period with scarce river outflow (April 1995) and one with greater outflow (July 1995). Despite great nutrient loads in both sampling periods, our estimates revealed that almost the whole fraction of inorganic phosphorus (up to 92 % at April) and a part of the inorganic nitrogen (30 % at April and 42 % at July) was readily consumed at the station. Surprisingly the dissolved organic fraction of nitrogen (DON) was much greater at the station (up to 3120 % in April) than in the river water, and it constituted a conspicuous part of the total dissolved nitrogen in the study area. On the contrary, the dissolved organic fraction of phosphorus (DOP) did not accumulate in the coastal area, compared to the river water