Maria De Paola

An integrated centrifugation–ultrafiltration system in the treatment of olive mill wastewater

Abstract A novel approach in the treatment of olive mill wastewater is presented. Aim of the proposed process is both the reduction of pollution caused by the wastes and the selective separation of some useful products that are present (fats, sugars, polyphenols, etc.). The treatment consists in a preliminary centrifugation step, in which the suspended solids are removed, and in an actual selective separation phase, carried out by ultrafiltration (UF), of the centrifuge supernatant. The combination of centrifugation and ultrafiltration allows a COD reduction of about 90%. Moreover a complete separation of fats, completely rejected by the membrane, from salts, sugars and polyphenols, contained in the permeate, is attained. The present experimental study is directed to investigate the fluid-dynamic aspects related to the ultrafiltration of real olive mill wastewaters. It is based on a preliminary rheological characterization of the waste and on the evaluation of permeation efficiency that was analyzed as a function of several parameters such as the importance of pre-treating wastewater, the effects of localized turbulence, promoted by UF module geometry, and of the main operating variables (trans-membrane pressure and feed flow rate). UF experimental results, obtained in a lab-scale flat-sheet membrane module, are interpreted using both the cake-filtration and the resistance-in-series models, thus allowing the evaluation of Rf parameter that represents the effect of fouling on separation efficiency. An estimation of specific cake resistance, α, is, therefore, performed on the basis of the feed concentration of total non-water compounds present in the waste showing that pre-treated wastewaters give a lower α with respect to raw wastewaters by a factor of about 1000. Moreover, it is found that at the same TMP, lower values of α correspond to a greater Re and that higher local turbulence implies lower specific cake resistances. The results obtained in the present paper could give useful indications for a preliminary characterization of pilot and industrial modules utilized for olive mill wastewaters treatment aimed at a significant COD reduction and a selective separation of valuable compounds that are present in the waste.

PEER EFFECTS IN HIGHER EDUCATION: DOES THE FIELD OF STUDY MATTER?

Does the peer effect vary with the field of study? Using data from a middle-sized public university located in Southern Italy and exploiting the random assignment of first year students to college accommodation, we find that roommate peer effects for freshmen enrolled in the Hard Sciences are positive and significantly larger than for freshmen enrolled in the Humanities and Social Sciences. We present a simple theoretical model which suggests that the uncovered differences between fields in the size of the peer effect could plausibly be generated by between-field variation in labor market returns, which affect optimal student effort.

The Effects of Managerial Turnover Evidence from Coach Dismissals in Italian Soccer Teams

The authors use sports data to study the effects of manager replacement on firm performance. Using match results of the major Italian soccer league (“Serie A”), the effects of coach (manager) changes on team performance are analyzed. To control for the “Ashenfelter dip” and to compare similar teams facing similar opponents two alternative econometric strategies are undertaken: the estimation of a number of team-season fixed effects models and the use of a matching estimator. From team-season fixed effects estimates, it emerges that changing the coach does not produce a positive effect on team performance, with the exception of the number of goals scored. Matching estimates confirm that changing the coach does not affect team performance neither when considering as dependent variable the number of points per match nor when looking at the number of goals scored or conceded.

Absenteeism in the Italian Public Sector: The Effects of Changes in Sick Leave Policy

We analyze how the absence behavior of Italian public sector employees has been affected by a law, passed in June 2008, reducing sick leave compensation and increasing monitoring. We use micro data on 889 workers employed in public administration. We find that the employees’ probability of being absent diminishes and that the reduction is greater among employees suffering higher earnings losses. Employees are responsive to the monitoring intensity and to the announcement of policy changes. Females react more strongly. While the reform has increased the hazard of ending an absence spell for short durations, the hazard for long durations decreased.

Peer Group Effects on the Academic Performance of Italian Students

We analyse peer effects among students of a middle-sized Italian public university. We explain students’ average grade in exams passed during their Second Level Degree course on the basis of their pre-determined measures of abilities, personal characteristics and peer group abilities. Thanks to a rich administrative data set, we are able to build a variety of definitions of peer groups, describing different kinds of students’ interaction, based on classes attended together or exams taken in the same session. Self-selection problems are handled through Two-Stage Least Squares estimations using as an instrument, the exogenous assignment of students to different teaching classes in the compulsory courses attended during their First Level Degree course. We find statistically significant positive peer group effects, which are robust to the different definitions of peer group and to different measures of abilities.

Monetary Incentives and Student Achievement in a Depressed Labor Market: Results from a Randomized Experiment

We evaluate the effectiveness of monetary incentives in enhancing student performance using a randomized experiment involving undergraduate students enrolled at a southern Italian University. Students were assigned to three different groups: a high-reward group, a low-reward group, and a control group. Rewards were given to the 30 best-performing students in each group. Financial rewards increase student performance. High-ability students react strongly whereas the effect is null for low-ability students. Large and small rewards produce very similar effects. These effects also persist in subsequent years, when the financial incentives are no longer in place. No types of crowding-out effects of the monetary incentives are found.

Height and subjective well-being in Italy

Using an Italian survey, we investigate the effect of height on individual happiness. We find that a large part of the effect of height on well-being is driven by a positive correlation between height and economic and health conditions. However, for young men the effect of height on happiness persists even after controlling for these variables, implying that height is associated with some psycho-social direct effects on well-being. Consistent with this hypothesis, we find that men care not only about their own height but also about the height of others in their reference group. Well-being is greater for individuals who are taller than other men in their reference group. Results are robust to different definitions of reference group and controlling for a number of other reference group characteristics.

The Determinants of Risk Aversion: The Role of Intergenerational Transmission

Abstract This article studies the relationship between risk attitudes and individual characteristics focusing on the intergenerational transmission of risk preferences. We use a dataset of a sample of Italyn students which allows us to build different measures of risk aversion based, respectively, on a survey asking students about their willingness to invest in a risky asset and about their preferences for job security and on the results of an entry test using explicit penalty points in the case of incorrect answers. In line with the findings highlighted by the existing literature, we find that women are more risk averse than men, more patient subjects are more risk averse, while high-ability students are less risk averse. As far as intergenerational transmission of preferences is concerned, it emerges that students whose fathers are entrepreneurs have a higher propensity to take risks, while students whose fathers are employed in the public sector are more risk averse. Only fathers matter with regards to their children’s risk attitudes. These results are robust to different measures of risk aversion and to different specifications of our model.

The Role of Family Ties in the Labour Market: An Interpretation Based on Efficiency Wage Theory

By casual empiricism, it seems that many firms take explicit account of the family ties connecting workers, often hiring individuals belonging to the same family or passing jobs on from parents to their children. This paper makes an attempt to explain this behaviour by introducing the assumption of altruism within the family and supposing that agents maximise a family utility function rather than an individual one. This hypothesis has been almost ignored in the analysis of the relationship between employers and employees. The implications of this assumption in the efficiency wage models are explored: by employing members of the same family, firms can use a (credible) harsher threat¬ – involving all the family’s members in case of one member’s shirking - that allows them to pay a lower efficiency wage. On the other hand, workers who accept this agreement exchange a reduction in wage with an increase in their probability of being employed: this can be optimal in situation of high unemployment. Moreover, the link between parents and children allows the firm to follow a strategy that solves the problem of an individual’s finite time horizon through family’s reputation.

The Costs of Early School Leaving in Europe

The reduction of early school leaving to less than 10 percent of the relevant population by 2020 is a headline target in the Europe 2020 strategy and one of the five benchmarks of the strategic framework for European cooperation in education and training. Designing adequate policies to combat early school leaving is a difficult task that requires both the identification of causal links and the measurement of costs and benefits. In this paper, we review the issues surrounding the measurement of the costs of early school leaving to individuals and societies and examine several implemented policies that are expected to affect early school leavers. These include broad policies – such as changes in minimum school leaving age, tracking and school resources – as well as more targeted policies. While our focus is mainly on Europe, we also consider important evidence from across the Atlantic.JEL ClassificationJ24.