63 research outputs found

    Distributed Time Delay Energy Model for Sustainable Economic Growth: some Remarks in the Spirit of Horizon 2020

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    Today the research into the basic principles for the modeling of economic growth is a new and topical challenge which has been the object of much investigation. Ever since 1862 Spencer has advocated that the economic growth of societies depends on their capability to exploit the increasing amounts of energy. Accordingly, the quantity of energy that a society consumes becomes an economic tool to measure its progress and thus the capital accumulation represents an important strategy for the growth process. In particular, the Solow model, which involves the aggregate production function, has made an important contribution to the economic growth theory especially because it is able to explain the differences between countries in GDP per worker. However, as discussed in Dalgaard and Strulik, the derivation of the law of movement of capital without recurring to the existence of an aggregate production function could be more appropriate. The main aim of this study is to shed light on what effects the delays can generate in an economy viewed as a transport network for energy where the law of the movement of capital occurs with a distributed delay. We have established a set of conditions in which a stationary state loses stability and oscillatory dynamics emerge through Hopf bifurcations.¬†Modello energetico con "ritardo" per una crescita economica sostenibile: alcune osservazioni nello spirito di Horizon 2020La ricerca dei principi di base per i modelli della crescita economica √® oggi una nuova e ardua sfida che √® stata oggetto di numerose indagini. Dal 1862 Spencer¬† ha sostenuto che la crescita economica delle societ√† dipende dalla loro capacit√† di sfruttare le crescenti quantit√† di energia. Di conseguenza, la quantit√† di energia che una societ√† consuma diventa uno strumento economico per misurare il suo progresso e quindi l'accumulazione di capitale rappresenta un'importante strategia per il processo di crescita. In particolare, il modello di Solow, che riguarda la funzione di produzione aggregata, ha dato un contributo importante alla teoria della crescita economica, soprattutto perch√© √® stato dimostrato che √® in grado di spiegare le differenze tra paesi del PIL per lavoratore. Tuttavia, come discusso in Dalgaard e Strulik, potrebbe essere pi√Ļ appropriata la derivazione di una legge del moto per il capitale senza ricorrere all'esistenza di una funzione di produzione aggregata. L'obiettivo principale di questo studio √® di fare luce su quali effetti possono produrre i ritardi in un'economia, considerata come una rete di trasporto per l'energia, in cui la legge del movimento del capitale si verifica con un ritardo distribuito. Con questo lavoro si individuano condizioni necessarie e sufficienti in base alle quali uno stato stazionario perde stabilit√† e le dinamiche oscillatorie emergono attraverso le biforcazioni Hopf.Today the research into the basic principles for the modeling of economic growth is a new and topical challenge which has been the object of much investigation. Ever since 1862 Spencer has advocated that the economic growth of societies depends on their capability to exploit the increasing amounts of energy. Accordingly, the quantity of energy that a society consumes becomes an economic tool to measure its progress and thus the capital accumulation represents an important strategy for the growth process. In particular, the Solow model, which involves the aggregate production function, has made an important contribution to the economic growth theory especially because it is able to explain the differences between countries in GDP per worker. However, as discussed in Dalgaard and Strulik, the derivation of the law of movement of capital without recurring to the existence of an aggregate production function could be more appropriate. The main aim of this study is to shed light on what effects the delays can generate in an economy viewed as a transport network for energy where the law of the movement of capital occurs with a distributed delay. We have established a set of conditions in which a stationary state loses stability and oscillatory dynamics emerge through Hopf bifurcations.¬†Modello energetico con "ritardo" per una crescita economica sostenibile: alcune osservazioni nello spirito di Horizon 2020La ricerca dei principi di base per i modelli della crescita economica √® oggi una nuova e ardua sfida che √® stata oggetto di numerose indagini. Dal 1862 Spencer¬† ha sostenuto che la crescita economica delle societ√† dipende dalla loro capacit√† di sfruttare le crescenti quantit√† di energia. Di conseguenza, la quantit√† di energia che una societ√† consuma diventa uno strumento economico per misurare il suo progresso e quindi l'accumulazione di capitale rappresenta un'importante strategia per il processo di crescita. In particolare, il modello di Solow, che riguarda la funzione di produzione aggregata, ha dato un contributo importante alla teoria della crescita economica, soprattutto perch√© √® stato dimostrato che √® in grado di spiegare le differenze tra paesi del PIL per lavoratore. Tuttavia, come discusso in Dalgaard e Strulik, potrebbe essere pi√Ļ appropriata la derivazione di una legge del moto per il capitale senza ricorrere all'esistenza di una funzione di produzione aggregata. L'obiettivo principale di questo studio √® di fare luce su quali effetti possono produrre i ritardi in un'economia, considerata come una rete di trasporto per l'energia, in cui la legge del movimento del capitale si verifica con un ritardo distribuito. Con questo lavoro si individuano condizioni necessarie e sufficienti in base alle quali uno stato stazionario perde stabilit√† e le dinamiche oscillatorie emergono attraverso le biforcazioni Hopf

    Stability and Hopf bifurcation analysis of a distributed time delay energy model for sustainable economic growth

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    This paper examines the consequences of including distributed delays in an energy model. The stability behaviour of the resulting equilibrium for our dynamic system is analysed, including models with Dirac, weak and strong kernels. Applying the Hopf bifurcation theorem we determine conditions under which limit cycle motion is born in such models. The results indicate that distributed delays have an ambivalent impact on the dynamical behaviour of systems, either stabilizing or destabilizing them

    Differential Enzymatic Activity of Rat ADAR2 Splicing Variants Is Due to Altered Capability to Interact with RNA in the Deaminase Domain

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    In mammals, adenosine (A) to inosine (I) RNA editing is performed by adenosine deaminases acting on RNA (ADAR), ADAR1 and ADAR2 enzymes, encoded by mRNAs that might undergo splicing process. In rat, two splicing events produce several isoforms of ADAR2, called ADAR2a, ADAR2b, ADAR2e, and ADAR2f, but only ADAR2a and ADAR2b are translated into an active protein. In particular, they differ for ten amino acids located in the catalytic domain of ADAR2b. Here, we focused on these two isoforms, analyzing the splicing pattern and their different function during rat neuronal maturation. We found an increase of editing levels in cortical neurons overexpressing ADAR2a compared to those overexpressing ADAR2b. These results indicate ADAR2a isoform as the most active one, as reported for the homologous human short variant. Furthermore, we showed that the differential editing activity is not due to a different dimerization of the two isoforms; it seems to be linked to the ten amino acids loop of ADAR2b that might interfere with RNA binding, occupying the space volume in which the RNA should be present in case of binding. These data might shed light on the complexity of ADAR2 regulations

    Involvement of fractalkine and macrophage inflammatory protein-1 alpha in moderate-severe depression.

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    Moderate-severe depression (MSD) is linked to overexpression of proinflammatory cytokines and chemokines. Fractalkine (FKN) and macrophage inflammatory protein-1 alpha (MIP-1alpha) are, respectively, members of CX3C and C-C chemokines, and both are involved in recruiting and activating mononuclear phagocytes in the central nervous system. We analysed the presence of FKN and MIP-1alpha in sera of untreated MSD patients and healthy donors. High FKN levels were observed in all MSD patients as compared with values only detectable in 26% of healthy donors. MIP-1alpha was measurable in 20% of patients, while no healthy donors showed detectable chemokine levels. In conclusion, we describe a previously unknown involvement of FKN in the pathogenesis of MSD, suggesting that FKN may represent a target for a specific immune therapy of this disease

    Therapeutic strategies to prevent the recurrence of nasal polyps after surgical treatment: an update and in vitro study on growth inhibition of fibroblasts

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    Chronic rhinosinusitis with nasal polyps (CRSwNP) is the most bothersome phenotype of chronic rhinosinusitis, which is typically characterized by a Type 2 inflammatory reaction, comorbidities and high rates of nasal polyp recurrence, causing severe impact on quality of life. Nasal polyp recurrence rates, defined as the number of patients undergoing revision endoscopic sinus surgery, are 20% within a 5 year period after surgery. The cornerstone of CRSwNP management consists of anti-inflammatory treatment with local corticosteroids. We performed a literature review regarding the therapeutic strategies used to prevent nasal polyp recurrence after surgical treatment. Finally, we report an in vitro study evaluating the efficacy of lysine-acetylsalicylic acid and other non-steroidal anti-inflammatory drugs (ketoprofen and diclofenac) on the proliferation of fibroblasts, obtained from nasal polyp tissue samples. Our study demonstrates that diclofenac, even more so than lysine-acetylsalicylic acid, significantly inhibits fibroblast proliferation and could be considered a valid therapeutic strategy in preventing CRSwNP recurrence
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