Constraining Scalar-Tensor gravity models by S2 star orbits around the Galactic Center

The aim of our investigation is to derive a particular theory among the class of scalar-tensor(ST) theories of gravity, and then to test it by studying kinematics and dynamics of S-stars around supermassive black hole (BH) at Galactic Center (GC). We also discuss the Newtonian limit of this class of ST theories of gravity, as well as its parameters. We compare the observed orbit of S2 star with our simulated orbit which we obtained theoretically with the derived ST potential and constrained the parameters. Using the obtained best fit parameters we calculated orbital precession of S2 star in ST gravity,and found that it has the same direction as in General Relativity (GR), but causes much larger pericenter shift.Comment: 13 pages, 1 table, 6 figures. Accepted for publication in Facta Universitatis: Series Phys. Chem. Tech. (Invited lecture at Balkan Workshop 2018

Assessing Unemployment Traps in Belgium Using Panel Data Sample Selection Models

In this paper we investigate whether unemployment traps exist and are significant in the transition from unemployment into employment in Belgium. In order to assess them, we use panel data sample selection models. Specifically, we estimate a parametric random effects models composed by a wage equation and a selection equation by maximum likelihood techniques. The income ratios have been computed for every individual in the sample by using the predicted wages obtained from the estimation of the wage equation corrected for sample selectivity. The empirical analyses has exploited the data extracted from the waves 1993-1997 of the Panel Study of Belgian Household and has been led separately on (unbalanced) samples of men and women. The estimation results suggest significant differences in the behaviour of these two groups. The experience of long periods of unemployment in the past is particularly important: long-term unemployed people have difficulties in re-integrating the labour market and they obtain low salaries when they succeed in finding employment. Long unemployment spells are likely to have a ?scarring? effect on subsequent earnings. Moreover, the computation of income ratios for all individuals highlights the importance of unemployment traps for the women present in the sample. Indeed, their expected wage is often lower than their income while being unemployed. A significant proportion of the available samples (men and women) is shown to enter employment although this transition is accompanied by a substantial loss in their disposable income

Spray freeze dried large porous particles for nano drug delivery by inhalation

INTRODUCTION: Tuberculosis (TB) is a bacterial infection caused by Mycobaterium tuberculosis. TB has recently reemerged as a disease of interest for improved drug delivery, with a focus on leveraging the benefits of anti-tubercular drug nanoparticle formulation (1, 2). Drug nanoparticles can target infected cells and provide a large payload, but the optimal administration route remains uncertain (3). While oral formulations are most preferred, the passage of nanoparticles across the gastrointesintal tract is challenging. On the other hand, intravenous injection of nanosuspen…postprin

Wet electrostatic scrubbing for high efficiency submicron particle capture

Exposure to fine particulate matter has been associated with serious health effects, including respiratory and cardiovascular disease, and mortality. Very fine inhalable particles can remain suspended in the atmosphere for a long time, travel long distances from the emitting sources and, once inhaled, they can reach the deepest regions of the lungs and even enter in the circulatory system. Therefore, the smaller the particle size, the higher its toxicity. In typical combustion units used in process industry, the end-of-pipe technologies include trains of consecutive abatements devices. Nevertheless, the traditional particle abatement devices are mainly designed and optimized to treat particles with sizes above or around 1µm, and they are far less effective towards the submicron dimensions. Among the end-of-pipe technologies, the Wet Scrubbers (WS) are widely utilized in industry due to their capacity to capture simultaneously gaseous pollutants and particles. The main particle collection mechanisms involved in WS are those related to directional interception and inertial impact, which allow high particle abatement efficiency for particles in micrometric range. Both the mechanisms are instead ineffective in the submicron range, thus resulting in low collection efficiencies. It the past 40 years, it was demonstrated that the presence of electric charge of opposite polarities on the particles and the sprayed droplets can increase the capture efficiency due to Coulomb forces between the two phases. The presence of this additional contribution in a scrubber is an upgrade of the traditional wet scrubbing and the new process is commonly referred as Wet Electrostatic Scrubbing (WES). Experimental investigation of the pertinent literature confirmed the ability of WES to increase the particle capture efficiency respect to the classic wet scrubber, but submicron range is generally not directly investigated so that the best operating conditions to increase submicron particle abatement efficiency is still an unsolved problem. This optimization problem is mainly related to the difficulties to model wet electrostatic scrubbing process due to the high number of the variables involved, resulting in a complex experimental evaluation of the main collection mechanisms that are responsible of the particle capture. Above all, a significant hindrance to the assessment of a proper description of wet electrostatic scrubbing is the complexity of the electro-hydrodynamics of the charged water spray. In this work, a new experimental methodology was adopted to perform experiments in controlled conditions in order to allow an easier investigation of the effects of the main physical variables on the abatement of submicron particles emission. This experimental approach is based on the use of a lab scale batch reactor, in which charged particles produced by combustion are inserted. In the reactor, a train of uniform droplet size and charge is used to remove the suspended particles. This approach has the main advantages to make possible to investigate specific parameters (like the effect of droplet charge or its size) under well-defined conditions and therefore model the particle abatement process. Therefore, the objective of this work is the experimental analysis and the modeling of wet electrostatic scrubbing process for submicron particles with the new methodology developed and the evaluation of the influence of the main physical variables on the capture of submicron particles. The results obtained confirm that the particle abatement is significantly enhanced by charging both particles and droplets, and that the particle abatement rate is directly proportional to the particles and droplet charges and droplet concentration. Furthermore, tests with uncharged particles and charged droplets do not show any relevant increase in the scrubbing efficiency with respect to common wet scrubbing in the investigated conditions. The experimental results obtained were compared with the predictions of classical particle scavenging models valid for ambient temperature and humidity conditions. These models were rarely applied to submicron particles and found a reliable experimental support from the performed experiments. On the other hand, this comparison also confirm the reliability of the experimental methodology in the study of wet electrostatic scrubbing and encourage the development of further tests in experimental conditions more similar to that of industrial scrubbers

Accurate Modeling and Analysis of Isolation Performance in Multiport Amplifiers

A Multiport Amplifier (MPA) is an implementation of the satellite power amplification section that allows sharing the payload RF power among several beams/ports and guarantees a highly efficient exploitation of the available DC satellite power. This feature is of paramount importance in multiple beam satellite systems where the use of MPAs allows reconfiguring the RF output power among the different service beams in order to handle unexpected traffic unbalances and traffic variations over time. This paper presents Monte Carlo simulations carried out by means of an ESA in-house simulator developed in Matlab environment. The objective of the simulations is to analyse how the MPA performance, in particular in terms of isolation at the MPA output ports, is affected by the amplitude and phase tracking errors of the high power amplifiers within the MPA

Duration Dependence and Timevarying Variables in Discrete Time Duration Models

This paper considers estimation of a dynamic discrete choice model with second order state dependence in the presence of strictly exogenous time-varying explanatory variables. We propose a new method for estimating such models, and a small Monte Carlo study suggests that the method performs well in practice. The method is used to test for duration dependence in labour market spells for young people in France. The novelty in the application is that we are able to control for time-varying explanatory variables. In a discrete time duration model, duration dependence will result in second order state dependence, and the paper therefore also adds to the literature on estimation of duration models with unobserved heterogeneity

Contratto di lavoro, tutela della professionalità e formazione

La ricerca analizza, da un punto di vista giuridico e di relazioni industriali, il contratto di lavoro subordinato con particolare riferimento alla tutela della professionalità del lavoratore e alla formazione.In particolare, sono state analizzate tutte quelle disposizioni costituzionali e di legge in materia di formazione e tutela della professionalità (art. 35 Cost., art. 2103 c.c., artt. 5-6 l. n. 53/2000, d.lgs. n. 13/2013, ecc.). Particolare attenzione è anche dedicata alla contrattazione collettiva e ai sistemi di classificazione e inquadramento del personale. A tal fine sono state analizzate, infatti, le soluzioni adottate nelle suddette materie dalla più recente contrattazione collettiva (2017-2018)

rotordynamic analysis of a centrifugal pump for automotive applications

Abstract A proper design of a high speed rotating machinery cannot be performed without a deep understanding of the rotor-dynamic aspects involved. The main purpose of the present work is to show how different methodologies can be adopted and integrated, in both preliminary and detailed design phases. The study focused on the dynamic analysis of a centrifugal pump for automotive applications, called purge pump, whose role is to take the air and gasoline vapor mix from the canister to the intake manifold of combustion chambers, in order to reduce emissions. It is quite small and rotates at a constant relatively high speed. The dynamic models were developed using commercial software widely used in companies and in the academic environment. First, an analytical model was devised with all the components assumed as rigid, except the supports. Then a 1-D Finite Element model of the shaft was created with lumped masses and finally a full flexible multibody model for transient analysis, which requires much more computational time with respect to all the other approaches but provides more information, was developed,. In addition to unbalance, localized defects in the pump ball bearings as source of vibration for the pump were investigated. In particular, a detailed 3-D model of faulty ball bearing was set up using a rigid multibody commercial code in order to simulate a localized defect and to evaluate the dynamic load produced. The presented set of methodologies can be a useful tool to understand the critical aspects of the design, as well as to predict the dynamic response and to suggest suitable modifications for a better rotor-dynamic behavior of the whole system reducing vibrations and consequently acoustic noise and improving structural reliability