Covariant hamiltonian spin dynamics in curved space-time

The dynamics of spinning particles in curved space-time is discussed, emphasizing the hamiltonian formulation. Different choices of hamiltonians allow for the description of different gravitating systems. We give full results for the simplest case with minimal hamiltonian, constructing constants of motion including spin. The analysis is illustrated by the example of motion in Schwarzschild space-time. We also discuss a non-minimal extension of the hamiltonian giving rise to a gravitational equivalent of the Stern-Gerlach force. We show that this extension respects a large class of known constants of motion for the minimal case.Comment: 14 pages, accepted version for Phys Lett B, added a footnote and two reference

Spinning bodies in curved space-time

We study the motion of neutral and charged spinning bodies in curved space-time in the test-particle limit. We construct equations of motion using a closed covariant Poisson-Dirac bracket formulation which allows for different choices of the hamiltonian. We derive conditions for the existence of constants of motion and apply the formalism to the case of spherically symmetric space-times. We show that the periastron of a spinning body in a stable orbit in a Schwarzschild or Reissner-Nordstr{\o}m background not only precesses, but also varies radially. By analysing the stability conditions for circular motion we find the innermost stable circular orbit (ISCO) as a function of spin. It turns out that there is an absolute lower limit on the ISCOs for increasing prograde spin. Finally we establish that the equations of motion can also be derived from the Einstein equations using an appropriate energy-momentum tensor for spinning particles.Comment: 26 pages, 5 figures; v2: version accepted for publication; small changes in text and references adde

LAGRANGIANS FOR EQUATIONS OF PAINLEVÉ TYPE BY MEANS OF THE JACOBI LAST MULTIPLIER

We apply the method of Jacobi Last Multiplier to the fifty second-order ordinary differential equations of Painleve type as given in Ince in order to obtain a Lagrangian and consequently solve the inverse problem of Calculus of Variations for those equations. The easiness and straightforwardness of Jacobi's method is underlined

RE-CONNECTING VOICES. The (New) Strategic Role of Public Sector Communication After the Covid-19 crisis

This article aims to investigate the evolution of public sector communication before and after the Covid-19 crisis that has strongly impacted governmental institutions, public policy, contemporary society, and media ecologies. After a review of the main characteristics of public sector communication, the article proposes an interpretative and dynamic model to better understand the new challenges for public institutions. The model introduces ethics as the new, primary driver for public sector communication to surround all decisions, pointing out the need for transparent, authentic participation and dialogue to build trust. Focusing on two dimensions (trust/distrust, openness/closedness), the authors investigate the main trajectories of change for public sector communication, conceiving the three pillars of open government (transparency, participation and collaboration) as strategic values for improving the quality and efficacy of communication. In this time of uncertainty, the new trajectories of communication should fully embrace an ethical approach in order to become resilient, able to respond to citizens\u2019 needs and expectations, and to maintain responsible relationships with media, varied strategic publics, and a rapidly changing global community

Re-Connecting Voices. The (New) Strategic Role of Public Sector Communication After the Covid-19 Crisis

This article aims to investigate the evolution of public sector communication before and after the Covid-19 crisis that has strongly impacted governmental institutions, public policy, contemporary society, and media ecologies. After a review of the main characteristics of public sector communication, the article proposes an interpretative and dynamic model to better understand the new challenges for public institutions. The model introduces ethics as the new, primary driver for public sector communication to surround all decisions, pointing out the need for transparent, authentic participation and dialogue to build trust. Focusing on two dimensions (trust/distrust, openness/closedness), the authors investigate the main trajectories of change for public sector communication, conceiving the three pillars of open government (transparency, participation and collaboration) as strategic values for improving the quality and efficacy of communication. In this time of uncertainty, the new trajectories of communication should fully embrace an ethical approach in order to become resilient, able to respond to citizens' needs and expectations, and to maintain responsible relationships with media, varied strategic publics, and a rapidly changing global community

Semplificazione strutturale e razionalizzazione della regolazione

2014 - 2015This research wants to focalize its attention on the finance world, especially on the financial markets supervision in order to obtain their simplification and rationalisation. After the computer revolution, the world began a “global village” and most part of the economy has suffered a financialisation process; the decrese and the speed up of the economic exchanges in the space and time found its best expression in the speeding up of the financial exchanges. The current interexchanges have made the financial world more complex and in few years it took over politics. Particularly the categories, by which one used to study politics and States life, have no value anymore: the triad territory – state – nation has to be substituted by a sort of local, national, overnational and international interconnected networks. The crisis of the State moved the balance from the executive to the administrative and the legal certanty with the State monopoly has left the place to an interexchangeable sets of rules network. From here the independent authorities are born and they were succesful even thanks tothe process of liberalization-privatization of the economy. Above all in Italy these Authorities were born in a chaotic and no organic way, with a series of overlaps of competences that don’t let understand “who does what”: so it needs simplification and rationalisation. In the financial world, especially all after the crisis in 2007/2008, we understood that the world, as de Larosière report says, was in front of two ways: or to do chacun pour soi or to take again the destiny in its hands, i.e. to try to take back finance under the direction of politics. the UE chose the second hypothesis leaving Lamfalussy care (soft law) and moving to de Larosière care (hard law), as a doctor does towards ills people: he tries to prevent instead of caring. The European regulations in 2010 and the international institutions like G20, FSB, Basel Committee, IOSCO, IFAC, IASB and IAIS, by their standards, tried to put order again in the financial world and to prevent the socalled “systemic risks” (macroprudential supervision), including the microprudential supervision in the most important sectors of finance (banking, insurance, securities) too. So it is necessary to study and know better the international supervision sistems (coordinated inter se) especially the EU Authorities (EBA, ESMA, EIOPA). The UE needed to rationalise the sistem and imposed it by regulations on every member State; in other words the Bank of Italy, CONSOB, IVASS and COVIP (financial indipendent Authorities) began the longa manus of the European Authorities by introducing into the italian system some rules coming directly from Europe, without “passing” through government or parliament way. Considering that the other member States have more less adeguated their “organogram” of Authorities following the UE model, Italy is still late, no because it didn’t adopte the European binding rules, but because it persevered to retain a “set” of inadeguated Authorities for the financial markets challenge. There are a lot of overlaps – interferences of competences between CONSOB and the Bank of Italy, the Bank of Italy and AGCM, whithout considering the “financialisation” of the insurance sector; Germany faced questions like Bankassurance and Allfinanz by BaFin reform, Italy instead persists in a “mixed” model of supervision in which coexists the “pourpose” model (fixed by TUF) and the “sectorial” model (there are specific supervision Authorities in every sector). In the italian system, as Kant says, it is necessery a new criterion of truth that combines empiricism of the American approach (SEC and CFTC) with the organic system and the predictability of the European model. So it is strongly necessary a simplification – reduction of Authorities to two: one in the field of micropudential supervision (Bank of Italy – CONSOB) and one Authority for macroprudential supervision (like UE model); in this way we’ll have a regulation, with overnational legal standards, based on prefixed, general, abstract defined criterions that are possibly “waterproof” for private interests of strong big groups. [edited by Author]XIV n.s

Osteochondral Lesions of the Talus and Autologous Matrix-Induced Chondrogenesis: Is Age a Negative Predictor Outcome?

Purpose To assess and evaluate healing and functional outcomes after arthroscopic talus autologous matrix-induced chondrogenesis (AT-AMIC) in 2 age groups: patients older than 33 years versus patients 33 years or younger. Methods A total of 31 patients, of whom 17 were 33 years or younger (G 1 ) and 14 older than 33 years (G 2 ), were evaluated. All patients were treated with AT-AMIC repair for osteochondral talar lesion. Magnetic resonance imaging (MRI) and computed tomography (CT)-scan evaluations, as well as clinical evaluations measured by the visual analog scale (VAS) score for pain, American Orthopaedic Foot and Ankle Society Ankle and Hindfoot score (AOFAS), and Short Form-12, were performed preoperatively (T 0 ) and at 6 (T 1 ), 12 (T 2 ), and 24 (T 3 ) months postoperatively. Results G 1 consisted of 17 patients (mean age: 25 years, standard deviation: ±5), whereas G 2 consisted of 14 patients (mean age: 47 years, standard deviation: ±9). In both groups, we found a significant difference for clinical and radiological parameters with the analysis of variance for repeated measures through 4 time points ( P 1 , AOFAS improved significantly between T 0 and T 1 ( P = .025) and T 1 and T 2 ( P = .011); CT showed a significant decrease between T 1 and T 2 ( P = .003) and T 2 and T 3 ( P 2 , AOFAS improved between T 0 and T 1 ( P = .011) and T 2 and T 3 ( P = .018); CT decreased between T 1 and T 2 ( P = .025), whereas MRI showed a reduction between T 1 and T 2 ( P = .029) and T 2 and T 3 ( P = .006). AOFAS in G 1 was significantly higher at T 0 ( P = .017), T 2 ( P = .036), and T 3 ( P = .039) compared with G 2 . A negative linear correlation between AOFAS and VAS at T 1 ( R = −0.756), T 2 ( R = −0.637), and T 3 ( R = −0.728) was found in G 1 , whereas in G 2 , AOFAS was negatively correlated with VAS at T 1 ( R = −0.702). Conclusions The study revealed that osteochondral lesions of the talus were characterized by similar sizes and features, both in young and old patients. We conclude that AT-AMIC can be considered a safe and reliable procedure that allows effective healing, regardless of age, with a significant clinical improvement; in particular, clinical results are related to starting conditions of the ankle. Level of Evidence Level IV, therapeutic case series

O THEATRO SÃO PEDRO NO ESPAÇO DA CIDADE: MEMÓRIA SOCIAL E CONSUMO DE CULTURA

Ao estudarmos a história do teatro e o consumo de cultura, percebemos que este sempre se fez presente no nosso cotidiano, quer queiramos, quer não. E, quando consumimos cultura – leia-se teatro –, também consumimos sonhos. O teatro é, assim, um espaço em que pessoas compartilham vivências e convivências, experiências e sensações. Objetiva-se, dessa maneira, no presente artigo, mapear o lócus que o Theatro São Pedro ocupa na memória social da cidade e o modo como sua presença influi nos hábitos de consumo de bens e serviços culturais dos porto-alegrenses.Palavras-chave: Teatro. Brasil. Rio Grande do Sul. Memória social. Consumo de cultura