"Is Wealth Becoming More Polarized in the United States?"

Recent work has documented a rising degree of wealth inequality in the United States between 1983 and 1998. In this paper we look at another dimension of the distribution: polarization. Using techniques developed by Esteban and Ray (1994) and extended by D'Ambrosia (2001), we examine whether a similar pattern exists with regard to trends in wealth polarization over this period. The approach followed provides a decomposition method, based on counterfactual distributions, that allows one to monitor which factors modified the entire distribution and precisely where on the distribution these factors had an effect. An index of polarization is provided, as are summary statistics of the observed movements and of distance and divergence among the estimated and the counterfactual distributions. The decomposition method is applied to U.S. data on the distribution of wealth between 1983 and 1998. We find that polarization between homeowners and tenants and among different educational groups continuously increased from 1983 to 1998, while polarization by income class continuously decreased. In contrast, polarization by racial group increased from 1983 to 1989 and then declined from 1989 to 1998, while polarization by age group followed the opposite pattern. We also find that most of the observed variation in the overall wealth density over the 1983-98 period can be attributed to changes in the within-group wealth densities rather than changes in household characteristics.

Is Wealth Becoming More Polarized in the United States?

Recent work has documented a rising degree of wealth inequality in the United States between 1983 and 1998. In this paper we look at another dimension of the distribution: polarization. Using techniques developed by Esteban and Ray (1994) and extended by D'Ambrosia (2001), we examine whether a similar pattern exists with regard to trends in wealth polarization over this period. The approach followed provides a decomposition method, based on counterfactual distributions, that allows one to monitor which factors modified the entire distribution and precisely where on the distribution these factors had an effect. An index of polarization is provided, as are summary statistics of the observed movements and of distance and divergence among the estimated and the counterfactual distributions. The decomposition method is applied to U.S. data on the distribution of wealth between 1983 and 1998. We find that polarization between homeowners and tenants and among different educational groups continuously increased from 1983 to 1998, while polarization by income class continuously decreased. In contrast, polarization by racial group increased from 1983 to 1989 and then declined from 1989 to 1998, while polarization by age group followed the opposite pattern. We also find that most of the observed variation in the overall wealth density over the 1983–98 period can be attributed to changes in the within-group wealth densities rather than changes in household characteristics.

Kaon decay interferometry as meson dynamics probes

We discuss the time dependent interferences between $K_L$ and $K_S$ in the decays in $3\pi$ and $\pi\pi\gamma$, to be studied at interferometry machines such as the $\phi$-factory and LEAR. We emphasize the possibilities and the advantages of using interferences, in comparison with width measurements, to obtain information both on $CP$ conserving and $CP$ violating amplitudes. Comparison with present data and suggestions for future experiments are made.Comment: 15 pages, in RevTex, Report INFNNA-IV-93-31, UTS-DFT-93-2

Strong rescattering in K-> 3pi decays and low-energy meson dynamics

We present a consistent analysis of final state interactions in ${K\rightarrow 3\pi}$ decays in the framework of Chiral Perturbation Theory. The result is that the kinematical dependence of the rescattering phases cannot be neglected. The possibility of extracting the phase shifts from future $K_S-K_L$ interference experiments is also analyzed.Comment: 14 pages in RevTex, 3 figures in postscrip

Numerical Analysis and Wind Tunnel Validation of Droplet Distribution in the Wake of an Unmanned Aerial Spraying System in Forward Flight

Recent developments in agriculture mechanization have generated significant challenges towards sustainable approaches to reduce the environmental footprint and improve food quality. This paper highlights the benefits of using unmanned aerial systems (UASs) for precision spraying applications of pesticides, reducing the environmental risk and waste caused by spray drift. Several unmanned aerial spraying system (UASS) operation parameters and spray system designs are examined to define adequate configurations for specific treatments. A hexarotor DJI Matrice 600 equipped with T-Motor “15 × 5” carbon fiber blades is tested numerically using computational fluid dynamics (CFD) and experimentally in a wind tunnel. These tests assess the aerodynamic interaction between the wake of an advancing multicopter and the fine droplets generated by atomizers traditionally used in agricultural applications. The aim of this research is twofold. First, we analyze the effects of parameters such as flight speed (0, 2, and 3 m·s (Formula presented.)), nozzle type (hollowcone and fan), and injection pressure (2–3 bar) on spray distribution. In the second phase, we use data from the experimental campaign to validate numerical tools for the simulation of rotor–droplet interactions necessary to predict spray’s ground footprint and to plan a precise guidance algorithm to achieve on-target deposition and reduce the well-known droplet drift problem

Automatic adjustment of tire inflation pressure through an intelligent CTIS: Effects on the vehicle lateral dynamic behavior

The paper investigates the effect of tire inflation pressure on the lateral dynamics of a passenger car, and presents a possible control-oriented methodology aimed at adapting tire pressure to the current vehicle loading condition targeting a reference characteristic. Starting from the tire characteristics at several inflation pressure levels, the paper investigates the effect of changing selectively tire pressure on each of the two axles, through theoretical calculation of the curvature gain based on the computation of the derivatives of stability, and compares the obtained sensitivity to the results of a multibody simulation model validated through on-track tests. Finally, the work presents a possible algorithm that could be implemented on-board vehicle ECU to provide, for the current loading condition of the vehicle, a tire pressure combination that targets a specific lateral dynamics characteristic. The algorithm is intended as part of the control logic of an intelligent Central Tire Inflation System (CTIS) able to adjust automatically tire pressure according to the actual vehicle working conditions

Physiology and Pathophysiology of Retinoid and Lipid Storage in Mouse Hepatic Stellate Cell Lipid Droplets

Retinoids are important mediators of many physiological processes in the body, including vision, reproduction, embryonic development, immunity and bone growth. Thus, the storage and metabolism of retinoids in the body has immediate implications for the overall health and metabolic homeostasis of the animal. This thesis research focused on two retinoid metabolites: retinyl ester, the form in which retinoids are stored, and retinoic acid, the transcriptionally active retinoid metabolite. Approximately 70% of retinoid in the body is stored in the liver, and, of this fraction, 80-90% is stored in the hepatic stellate cell (HSC) lipid droplets as retinyl ester. These lipid droplets are a distinguishing feature of the HSC, and they have recently been proposed to be specialized organelles for the storage of retinoid based on their unique retinoid content and responsiveness to dietary retinoid status. It is also known that the ability to synthesize and store retinyl ester in HSCs is necessary for the presence of HSC lipid droplets. Interestingly, it is well established that, with the progression of liver disease in human patients, there is a progressive loss of total hepatic retinoid content. As hepatic disease progresses, the HSCs transition from a quiescent to an activated phenotype, accompanied by the loss of their lipid droplet and retinoid content. The ultimate goal of this dissertation was to further elucidate the factors that regulate HSC retinoid storage as retinyl esters in lipid droplets and to define the factors that regulate HSC lipid droplet genesis and dissolution. The first aim of this research was to investigate the heterogeneity of HSCs and their lipid droplets in healthy, uninjured liver. Our observations suggest that the HSC population in a healthy, uninjured liver is heterogeneous. One subset of the total HSC population, which expresses early markers of HSC activation, may be primed and ready for rapid response to acute liver injury. We show that these "pre-activated" HSCs have: (i) increased expression of typical markers of HSC activation; (ii) decreased retinyl ester levels, accompanied by reduced expression of the enzyme needed for hepatic retinyl ester synthesis (LRAT); (iii) decreased triglyceride levels; (iv) increased expression of genes associated with lipid catabolism; and (v) an increase in expression of the retinoid-catabolizing cytochrome, CYP2S1. The second aim of this research was to investigate HSC lipid droplet formation and maintenance in healthy, but genetically-modified liver: specifically, we studied HSC lipid droplets in the LRAT KO mouse model, a system where HSC lipid droplets do not form. Our findings indicate that there are not global differences in retinoid-related gene expression, suggesting that the formation and maintenance of HSC lipid droplets is likely regulated entirely by the synthesis and storage of retinyl ester and not by more profound changes in retinoid metabolism. Our data also shows that the LRAT KO HSCs have significant differences in expression of genes related to lipid metabolism; overall, lipid biosynthesis is down-regulated and lipid catabolism is up-regulated in LRAT KO HSCs, which likely contributes to the complete absence of lipid droplets in the HSCs of these animals. Importantly, we show for the first time, to our knowledge, that the lipid droplet-associated proteins may be post-transcriptionally regulated. A final aim of this research was to investigate HSC lipid droplet dissolution in HSC activation and hepatic fibrosis, systems where HSC lipid droplets form, but are subsequently lost. We employed two standard models of HSC activation, the in vivo model of carbon tetrachloride (CCl4) treatment and the in vitro model, the culture of purified HSCs on plastic cell culture dishes. Additionally, we studied the effects of hypervitaminosis A since there is evidence in the literature that dietary vitamin A toxicity can cause hepatic fibrosis. Our studies suggest that, despite being unable to synthesize and store retinyl ester in lipid droplets, LRAT KO mice are not more susceptible than WT to the development of diet- or chemically-induced hepatic fibrosis. We found that, while the culture of HSCs on plastic results in the typical hallmark events of HSC activation, including the upregulation of Col1a1, the decrease in retinyl ester and the loss of lipid droplets, it does not regulate gene expression as HSC activation does in vivo. Thus, all future studies on HSC activation and its effects on retinoid storage should be conducted in vivo. We also present preliminary data on the alterations in the lipidome of activated HSCs, specifically with regard to the potent lipid signaling molecules, endocannabinoids, sphingolipids and ceramides. Our findings allow us to hypothesize that endocannabinoids and sphingolipids may function in activated HSCs as mediators of apoptosis. Importantly, this study demonstrates the ability to detect these lipids in very small aliquots of in vivo-activated HSCs and provides a strong foundation upon which all future studies may be built

Photonic polarization gears for ultra-sensitive angular measurements

Quantum metrology bears a great promise in enhancing measurement precision, but is unlikely to become practical in the near future. Its concepts can nevertheless inspire classical or hybrid methods of immediate value. Here, we demonstrate NOON-like photonic states of m quanta of angular momentum up to m=100, in a setup that acts as a "photonic gear", converting, for each photon, a mechanical rotation of an angle {\theta} into an amplified rotation of the optical polarization by m{\theta}, corresponding to a "super-resolving" Malus' law. We show that this effect leads to single-photon angular measurements with the same precision of polarization-only quantum strategies with m photons, but robust to photon losses. Moreover, we combine the gear effect with the quantum enhancement due to entanglement, thus exploiting the advantages of both approaches. The high "gear ratio" m boosts the current state-of-the-art of optical non-contact angular measurements by almost two orders of magnitude.Comment: 10 pages, 4 figures, + supplementary information (10 pages, 3 figures

Preliminary Design of a Remotely Piloted Aircraft System for Crop-Spraying on Vineyards

This paper describes the preliminary design of an innovative concept rotary-wing Unmanned Aircraft System (UAS) for precision agriculture and aerial spraying applications. Aerial spraying of plant protection products and pesticides shows open challenges in terms of performance and regulatory requirements. In particular*the focus here is on highlighting the advantages of the proposed solution in performing precise and expeditious interventions, coping with the spray drift problem (i.e. minimization of drift). Flight performances and agronomists' requirements are combined to define the mission and the aerial vehicle and spray system design