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The “Smile Curve”: where Value is Added along Supply Chains
No full textIn this paper we analyze where value is added along supply chains on a sample of more than 2
million of firms in the European Union. We detect a non-linear U-shaped relationship between the
value added generated by firms and their position on a productive sequence, for which tasks at the
top and at the bottom show higher value added. Our findings are in line with previous hypotheses
on the existence of a so-called 'smile curve', resumed by both business and economic studies and
discussed at length in international fora. Our results are robust to different empirical strategies for
flexible functional forms. As far as we know, ours is the first firm-level successful attempt to test
for value generation along supply chains. Further, we find empirical support for a phenomenon of
domestic retention of value added by MNEs, which may prefer keeping at home the tasks at higher
potential to safeguard present and future competitive advantages. By country, intermediate stages
of production are at higher value when performed by foreign as liates, whereas domestic producers
retain higher value at the very top and at the very bottom of the supply chain, organized either
as independent suppliers or as domestic affiliates. Although an economic theory is still missing
for explaining how and why value generation is non-linear along a typical technological sequence,
here we argue that a microfoundation with firm-level data is useful for understanding the growth
potential of countries' specialization patterns along different segments of supply chains
An extreme value analysis of the last century crises across industries in the U.S. economy
No full textAbstract The two large scale crises that hit the world economy in the last century, i.e. the Great Depression and the Great Recession, have similar outbreak and recovery patterns with respect to several macroeconomic variables. In particular, the largest depressions are likely to be accompanied by stock-market crashes. This study investigates the behavior of the U.S. stock market before, during and after deep downturns, focusing particularly on the tails of the return distribution. We develop two automatic procedures to identify multiple change-points in the tail of financial time series as well as in the co-crash and co-boom probabilities of different markets. We then apply our methodology to twelve time series representative of the sectors of the U.S. economy. We find that regime shifts in the lower tail of the distribution tend to co-occur before deep downturns. Our results contribute to a better understanding of the origin and systemic nature of large scale events to make policy interventions more timely and effective
In favor of the phonemic principle: a review of neurophysiological and neuroimaging explorations into the neural correlates of phonological competence
No full textIn the last thirty years, in vivo brain structural and functional exploration has sparked vivid light on the neural correlates of language. Along these lines, the study of phono- logical competence has offered a ‘neural view’ into the organization of basic speech- sensitive areas, improving the sensitivity of pre-surgical mapping and brain-computer interface-based communication. Nevertheless, only rarely the significance of these results has been recognized in the context of a century-long discussion around the theoretical, physical and cognitive consistency of the phoneme itself. Here we review recent investigations into speech perception, imagery and production at the segmen- tal level through neuroimaging and neurophysiological techniques, showing that phonemes are processed as discrete entities, which are categorized in cognition as unique products of their acoustic and articulatory features, despite the seamless flow of the speech signal. These results seem to expand the scope of the motor theory of speech perception
Spatial and sociomaterial interaction between an organized event and related informal practices: the case of temporary shops at Lucca Comics & Games
No full textEssentiality, conservation, evolutionary pressure and codon bias in bacterial genes
No full textEssential genes constitute the core of genes which cannot be mutated too much nor lost along the adaptive evolutionary history of a species. Natural selection is expected to be stricter on essential genes and on conserved (highly shared) genes, than on genes that are either nonessential or peculiar to a single or a few species. In order to further assess this expectation, we study here how essentiality of a gene is connected with its degree of conservation among several unrelated bacterial species, each one characterised by its own codon usage bias. Confirming previous results on E- Coli, we show the existence of a universal exponential correlation between gene essentiality and conservation in bacteria. Moreover, we show that, within each bacterial genome, there are at least two groups of functionally distinct genes, characterised by different levels of conservation and codon bias: i) a core of essential genes, mainly related to cellular information processing; ii) a set of less conserved genes with prevalent functions related to metabolism. The genes in the first group are more retained among species, are subject to a relatively purifying conservative selection and display a more selected choice of synonymous codons.The core of essential genes is close to the minimal bacterial genome, which is in the focus of recent studies in synthetic biology, though we confirm that othologues of genes that are essential in one species are not necessarily essential in other species. We also list a set of highly shared genes, which could constitute a reservoir of targets for new anti-microbial drugs
Reliability and Fault-Tolerance by Choreographic Design
No full textDistributed programs are hard to get right because they are required to be open, scalable, long-running, and tolerant to faults. In particular, the recent approaches to distributed software based on (micro-)services where different services are developed independently by disparate teams exacerbate the problem. In fact, services are meant to be composed together and run in open context where unpredictable behaviours can emerge. This makes it necessary to adopt suitable strategies for monitoring the execution and incorporate recovery and adaptation mechanisms so to make distributed programs more flexible and robust. The typical approach that is currently adopted is to embed such mechanisms in the program logic, which makes it hard to extract, compare and debug. We propose an approach that employs formal abstractions for specifying failure recovery and adaptation strategies. Although implementation agnostic, these abstractions would be amenable to algorithmic synthesis of code, monitoring and tests. We consider message-passing programs (a la Erlang, Go, or MPI) that are gaining momentum both in academia and industry. Our research agenda consists of (1) the definition of formal behavioural models encompassing failures, (2) the specification of the relevant properties of adaptation and recovery strategy, (3) the automatic generation of monitoring, recovery, and adaptation logic in target languages of interest
Experimental characterization and numerical simulation of humidity-induced damage in PV cells
No full textDiritto del patrimonio culturale
No full textIl volume, realizzato dai componenti della direzione della rivista «Aedon», offre un quadro completo e aggiornato dei dati normativi concernenti l'attività e l'organizzazione delle istituzioni pubbliche e dei privati in tema di patrimonio culturale. Fornisce inoltre una ricostruzione critica del contesto e dei presupposti che hanno accompagnato il sorgere e il consolidamento del sistema dei beni culturali e paesaggistici nel nostro Paese. Uno strumento di formazione per gli studenti e al tempo stesso di consultazione e aggiornamento per quanti operano professionalmente nel settor
A Behavioural Theory for Interactions in Collective-Adaptive Systems
Full text linkWe propose a process calculus, named AbC, to study the behavioural theory of interactions in collective-adaptive systems by relying on attribute-based communication. An AbC system consists of a set of parallel components each of which is equipped with a set of attributes. Communication takes place in an implicit multicast fashion, and interaction among components is dynamically established by taking into account "connections" as determined by predicates over their attributes. The structural operational semantics of AbC is based on Labeled Transition Systems that are also used to define bisimilarity between components. Labeled bisimilarity is in full agreement with a barbed congruence, defined by simple basic observables and context closure. The introduced equivalence is used to study the expressiveness of AbC in terms of encoding broadcast channel-based interactions and to establish formal relationships between system descriptions at different levels of abstraction
Numerical Optimal Control with Periodicity Constraints in the Presence of Invariants
No full textPeriodic optimal control problems (POCPs) based on dynamic models holding invariants are often problematic to treat using standard numerical methods. The difficulty stems from a failure of standard constraint qualifications and typically hinders the convergence of the numerical solver, or even defeats it. Optimisation problems having weak constraint qualifications can be treated using dedicated solvers, at the price of a more involved algorithmic. In this paper, we analyse the constraint qualification of POCPs holding invariants, and propose three simple and computationally inexpensive modifications of the formulation that allow for a recovery of Linear Independence Constraint Qualification (LICQ), while not affecting the Second-Order Sufficient Conditions (SOSC) for optimality. Hence, the resulting POCP can be tackled via standard solvers, without special treatment. The application of these approaches is detailed for the case of POCPs holding index-reduced Differential-Algebraic Equations and representations of the SO(3) Lie group