1,721,033 research outputs found
ALFANI, F (ALFANI, F); CANTARELLA, L (CANTARELLA, L); CIRIELLI, G (CIRIELLI, G); GALLIFUOCO, A (GALLIFUOCO, A); CANTARELLA, M (CANTARELLA, M)
No full text#Portichiusi: the human costs of migrant deterrence in the Mediterranean
Full text linkUsing daily data on forced migration from the IOM, I compare trends in flows and mortality across three major migration routes in the Mediterranean, analysing the effects of the introduction of rescue-deterrence policies in Italy. Controlling for exogenous shocks which affect push and pull factors in mobility, along with sea state conditions and route-day fixed effects, I find that the reduction in refugee migration flows in the Central Mediterranean has been modest, at best. At the same time, these policies have generated a permanent increase in daily mortality rates in the Central Mediterranean, having grown by more than 4 deaths per day. Finally, I investigate whether variations in mortality are sufficient to offset migration flows. Increases in mortality rates, however, are only accompanied by a short-term negative displacement effect, as migration attempts are delayed by increases in absolute mortality, rather than being prevented
Task search and labour supply in the platform economy
Full text linkIn this paper, we study the wage elasticity of labour supply of platform workers by exploiting uncertainty in task search. Using a survey of on-location and online platform workers in Europe, we show that wage reductions due to task search are inversely related to increases in labour supply and that changes in earnings net of task search are also inversely related to labour supply. Our estimated backwards-bending labour supply curves are valid for all platform workers and are robust to a number of misspecification and endogeneity issues
Labour market effects of crowdwork in the US and EU: an empirical investigation
Full text linkIs it possible to estimate the real impact of micro-task crowdwork on wages and working conditions of platform workers? Do workers involved in micro-task outsourcing differ in their characteristics from traditional salaried workers of similar ability? Are micro-task crowdworkers similar or different in the United States and in Europe? In this paper, we address these questions by comparing wages and working conditions across onlineplatform workers and traditional workers in a quasi-experimental approach which exploits caregiving as an instrument for participation in crowdwork. We find evidence that, when controlling for workers’ observed and unobserved ability, traditional workers retain a significant premium in their earnings with respect to platform workers, though this effect is not as large as descriptive statistics may hint. Moreover, labour force in crowdworking arrangements appears to suffer from high levels of under-utilisation, relegating crowdworkers into a new category of idle workers whose human capital is neither fully utilised nor adequately compensated
Studying enzyme-catalyzed depolymerizations in continuous reactors
No full textThe models of Ohmine et al. and Sendra and Carbonell for the enzymatic breakdown of polymers in batch reactors were modified to describe the depolymerization in continuous reactors. The model equations give the time course of the product concentration in the reactor permeate and that of the total product. The model predictions were compared with the experimental results for the hydrolysis of polygalacturonic acid in ultrafiltration membrane reactors. The amount of enzyme in the reactor varied from 0.18 to 1.80 mg. The residence time (100 min), temperature (25 degreesC), and membrane molecular cutoff (30 kDa) were maintained constant in the experiments. The system response was sensitive to the kinetic pattern of the enzymatic attack and was in reasonable agreement only with the predictions of the model based on the kinetic assumption made by Sendra and Carbonell. An induction period and an asymptotic amount of product were detected, which cannot be explained by the model of Ohmine et al
Investigating the kinetics of the enzymatic depolymerization of polygalacturonic acid in continuous UF-membrane reactorss reactors
No full textA stirred tank membrane reactor is used to study the kinetics of polygalacturonic acid (PGA)
enzymatic hydrolysis. The reactor operates in semicontinuous configuration: the native
biopolymer is loaded at the initial time and the system is continuously fed with the buffer. The
effect of retention time (from 101 to 142 min) and membrane molecular weight cutoff (from 1
to 30 kDa) on the rate of permeable oligomers production is investigated. Reaction products are
clustered in two different classes, those sized below the membrane cutoff and those above. The
reducing power measured in the permeate is used as an estimate of total product concentration.
The characteristic breakdown times range from 40 to 100 min. The overall kinetics obeys a
first-order law with a characteristic time estimated to 24 min. New mathematical data handling
are developed and illustrated using the experimental data obtained. Finally, the body of the
experimental results suggests useful indications (reactor productivity, breakdown induction period)
for implementing the bioprocess at the industrial scale
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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