Entropy theorems in classical mechanics, general relativity, and the gravitational two-body problem

In classical Hamiltonian theories, entropy may be understood either as a statistical property of canonical systems, or as a mechanical property, that is, as a monotonic function of the phase space along trajectories. In classical mechanics, there are theorems which have been proposed for proving the non-existence of entropy in the latter sense. We explicate, clarify and extend the proofs of these theorems to some standard matter (scalar and electromagnetic) field theories in curved spacetime, and then we show why these proofs fail in general relativity; due to properties of the gravitational Hamiltonian and phase space measures, the second law of thermodynamics holds. As a concrete application, we focus on the consequences of these results for the gravitational two-body problem, and in particular, we prove the non-compactness of the phase space of perturbed Schwarzschild-Droste spacetimes. We thus identify the lack of recurring orbits in phase space as a distinct sign of dissipation and hence entropy production.Comment: 39 pages, 3 figures; v2: version to appear in Phys. Rev. D, references adde

Genetic analysis of chromosomal regions 2q33, 7q32 and 19q13 in multiple sclerosis susceptibility

Multiple sclerosis (MS) is an immune-mediated demyelinating disorder of the central nervous system (CNS) affecting 0.1-0.2% of Northern European descent population. MS is considered to be a multifactorial disease, both environment and genetics play a role in its pathogenesis. Despite several decades of intense research, the etiological and pathogenic mechanisms underlying MS remain still largely unknown and no curative treatment exists. The genetic architecture underlying MS is complex with multiple genes involved. The strongest and the best characterized predisposing genetic factors for MS are located, as in other immune-mediated diseases, in the major histocompatibility complex (MHC) on chromosome 6. In humans MHC is called human leukocyte antigen (HLA). Alleles of the HLA locus have been found to associate strongly with MS and remained for many years the only consistently replicable genetic associations. However, recently other genes located outside the MHC region have been proposed as strong candidates for susceptibility to MS in several studies. In this thesis a new genetic locus located on chromosome 7q32, interferon regulatory factor 5 (IRF5), was identified in the susceptibility to MS. In particular, we found that common variation of the gene was associated with the disease in three different populations, Spanish, Swedish and Finnish. We also suggested a possible functional role for one of the risk alleles with impact on the expression of the IRF5 locus. Previous studies have pointed out a possible role played by chromosome 2q33 in the susceptibility to MS and other autoimmune disorders. The work described here also investigated the involvement of this chromosomal region in MS predisposition. After the detection of genetic association with 2q33 (article-1), we extended our analysis through fine-scale single nucleotide polymorphism (SNP) mapping to define further the contribution of this genomic area to disease pathogenesis (article-4). We found a trend (p=0.04) for association to MS with an intronic SNP located in the inducible T-cell co-stimulator (ICOS) gene, an important player in the co-stimulatory pathway of the immune system. Expression analysis of ICOS revealed a novel, previously uncharacterized, alternatively spliced isoform, lacking the extracellular domain that is needed for ligand binding. The stability of the newly-identified transcript variant and its subcellular localization were analyzed. These studies indicated that the novel isoform is stable and shows different subcellular localization as compared to full-length ICOS. The novel isoform might have a regulatory function, but further studies are required to elucidate its function. Chromosome 19q13 has been previously suggested as one of the genomic areas involved in MS predisposition. In several populations, suggestive linkage signals between MS predisposition and 19q13 have been obtained. Here, we analysed the role of allelic variation in 19q13 by family based association analysis in 782 MS families collected from Finland. In this dataset, we were not able to detect any statistically significant associations, although several previously suggested markers were included to the analysis. Replication of the previous findings on the basis of linkage disequilibrium between marker allele and disease/risk allele appears notoriously difficult because of limitations such as allelic heterogeneity. Re-sequencing based approaches may be required for elucidating the role of chromosome 19q13 with MS. This thesis has resulted in the identification of a new MS susceptibility locus (IRF5) previously associated with other inflammatory or autoimmune disorders, such as SLE. IRF5 is one of the mediators of interferons biological function. In addition to providing new insight in the possible pathogenetic pathway of the disease, this finding suggests that there might be common mechanisms between different immune-mediated disorders. Furthermore the work presented here has uncovered a novel isoform of ICOS, which may play a role in regulatory mechanisms of ICOS, an important mediator of lymphocyte activation. Further work is required to uncover its functions and possible involvement of the ICOS locus in MS susceptibility.Ei saatavill

La condizione giuridica di Rom e Sinti in Italia

Il volume rappresenta un’assoluta novità nel panorama della letteratura giuridica italiana. Si tratta, infatti, della prima opera che cerca di fornire una visione completa, aggiornata e interdisciplinare dei problemi giuridici relativi alla condizione in Italia delle persone appartenenti alla minoranza dei Rom e dei Sinti. I capitoli fanno riferimento a molteplici aspetti con ricadute di rilievo tanto per la giurisprudenza costituzionale che per quella ordinaria, ma anche per il diritto dell’UE e la giurisprudenza della Corte europea dei diritti dell’uomo. Sono così approfonditi tutti gli aspetti della condizione delle singole persone (italiane, straniere o apolidi) e dello status della minoranza in sé, le norme statali e regionali rilevanti, le prassi istituzionali e i problemi di discriminazione, le raccomandazioni e le proposte emesse da organismi internazionali. Le analisi vanno a toccare il diritto costituzionale, pubblico e regionale, il diritto amministrativo e urbanistico, il diritto penale e processuale penale, il diritto civile, il diritto del lavoro, il diritto internazionale e dell’Unione europea. Sono presenti altresì riflessioni di diritto comparato (Francia, Spagna, Ungheria, Romania, Stati dell’ex-Jugoslavia), nonché analisi empiriche sulle prassi amministrative e giudiziarie. Oltre ad analisi svolte da giuristi accademici, l’opera contiene contributi di magistrati e avvocati, ma anche di sociologi, politologi, epidemiologi, antropologi e linguisti scelti tra coloro che più si sono distinti nello studio del mondo rom e sinto. Sono altresì presenti contributi di rappresentanti di istituzioni statali italiane, della Commissione europea, del Consiglio d’Europa e dell’OSCE, nonché testimonianze di rappresentanti dell'associazionismo rom e sinto. L’appendice contiene un’articolata bozza di progetto di legge elaborata dai curatori.Tomo I La condizione giuridica di Rom e Sinti in Italia: dall’ascolto e confronto alla proposta, di P. Bonetti, A. Simoni, T. Vitale. Saluto del Presidente della Repubblica Giorgio Napolitano. Sezione I - INTRODUZIONE. I nodi giuridici della condizione di Rom e Sinti in Italia, di P. Bonetti. Sezione II - ASPETTI GENERALI. Contributi di D. Halwachs, F. Palermo, S. Baldin, G. Loy, A. Simoni, T. Vitale, A.R. Calabrò. Sezione III - ASPETTI DI DIRITTO COMUNITARIO E INTERNAZIONALE E DI DIRITTO DEGLI STRANIERI. Contributi di M. Fornara, J. A. Goldston e C. Hermanin, D. Boni, G. Perin, G. Cousin e F. Mariani. Sezione IV - BREVE CASISTICA DI MODELLI EUROPEI. Contributi di F. Rey Martínez, K. Kelemen, S. Tanasescu, M. Dicosola, C. Le Berre. Sezione V - EGUAGLIANZA, DISCRIMINAZIONI E AZIONI LEGALI. Contributi di M. Barbera, T. Vettor, A. Maiorca, V. Vasey, A. Guariso, E. Rizzin e A. Bertellini, P. Tanzarella. Tomo II Sezione VI - INTEGRAZIONE, PARTECIPAZIONE E COMUNICAZIONE. Contributi di F. Furlan, N. Sigona, G. E. Vigevani. Sezione VII - I DIRITTI A CIRCOLARE, A SOGGIORNARE E AD ABITARE. Contributi di C. Corsi, A. Tosi, N. Bassi, E. Paciotti, G. Scappucci e R. Demiraj, L. Levak, F. Casavola, L. Neri. Sezione VIII - I DIRITTI LINGUISTICI, CULTURALI E DELL’ISTRUZIONE. Contributi di G. Poggeschi, V. Piergigli, E. Rozzi, D. Argiropoulos, E. Cimoli, G. Bezzecchi, M. Mapelli. Sezione IX - FAMIGLIA E DIRITTI DEI MINORI. Contributi di E. Lamarque, P. Morozzo della Rocca, C. Saletti Salza. Sezione X - IL DIRITTO ALLA SALUTE. Contributi di F. Motta e S. Geraci, L. Monasta. Sezione XI - ASPETTI PENALI E PROCESSUALI. Contributi di L. Masera, F. Viganò, G. Ubertis, L. Trucco, L. Laera, S. Tosi Cambini. Sezione XII - LE SFIDE PER IL FUTURO. Contributi di A. Mirga, M. Cermel, N. Gheorghe, M. Guet, T. Vitale e L. Caruso. Sezione XIII - VERSO UNA LEGGE ITALIANA PER IL RICONOSCIMENTO E LA TUTELA DELLA MINORANZA DEI ROM E DEI SINTI? Contributi di O. Marotti, M. Pagani, G. Perego. APPENDICE - UN’IPOTESI DI PROPOSTA DI LEGGE: NORME PER LA TUTELA E LE PARI OPPORTUNITÀ DELLA MINORANZA DEI ROM E DEI SINTI. Relazione generale e bozza dell’articolato di P. Bonetti, A. Simoni e T. Vitale

Dynamical evolution of massive perturbers in realistic multi-component galaxy models I: implementation and validation

Galaxies are self-gravitating structures composed by several components encompassing spherical, axial and triaxial symmetry. Although real systems feature heterogeneous components whose properties are intimately connected, semi-analytical approaches often exploit the linearity of the Poisson's equation to represent the potential and mass distribution of a multi-component galaxy as the sum of the individual components. In this work, we expand the semi-analytical framework developed in Bonetti et al. (2020) by including both a detailed implementation of the gravitational potential of exponential disc (modelled with a ${\rm sech}^2$ and an exponential vertical profile) and an accurate prescription for the dynamical friction experienced by massive perturbers in composite galaxy models featuring rotating disc structures. Such improvements allow us to evolve arbitrary orbits either within or outside the galactic disc plane. We validate the results obtained by our numerical model against public semi-analytical codes as well as full N-body simulations, finding that our model is in excellent agreement to the codes it is compared with. The ability to reproduce the relevant physical processes responsible for the evolution of massive perturber orbits and its computational efficiency make our framework perfectly suited for large parameter-space exploration studies.Comment: 17 pages, 9 figures; accepted for publication in MNRA

Plasticizer design strategies enabling advanced applications of cellulose acetate

Plasticized cellulose acetate (CA) is one of the most applied bio-based polymers due to its structural properties and easy processing. Plasticizers are added to CA to increase workability, prevent degradation under processing conditions and ensure thermo-mechanical properties suitable for the intended final application. Moreover, inexpensive and non-toxic solvents enable its processing into fibers, films, and solid blocks. However, when incorporated in the polymer matrix, plasticizers are prone to migration. CA products can suffer embrittlement, cracking, warping, or discoloration during their life cycle, affecting the material’s integrity and durability. The design of new plasticizers compatible with the polymer at high concentrations, tailored to be effective in lowering the glass transition temperature, and with a low tendency to migration could considerably reduce material degradation over time. This review offers a perspective on the current plasticizers and comprehensively depicts the plasticization mechanisms in CA for internal and external plasticization. Understanding the plasticization mechanisms paves the way to identify a rationale for designing new plasticizers for this polymer

Photon Mass Limits from Fast Radio Bursts

The frequency-dependent time delays in fast radio bursts (FRBs) can be used to constrain the photon mass, if the FRB redshifts are known, but the similarity between the frequency dependences of dispersion due to plasma effects and a photon mass complicates the derivation of a limit on $m_\gamma$. The dispersion measure (DM) of FRB 150418 is known to $\sim 0.1$%, and there is a claim to have measured its redshift with an accuracy of $\sim 2$%, but the strength of the constraint on $m_\gamma$ is limited by uncertainties in the modelling of the host galaxy and the Milky Way, as well as possible inhomogeneities in the intergalactic medium (IGM). Allowing for these uncertainties, the recent data on FRB 150418 indicate that $m_\gamma \lesssim 1.8 \times 10^{-14}$eV c$^{-2}$ ($3.2 \times 10^{-50}$kg), if FRB 150418 indeed has a redshift $z = 0.492$ as initially reported. In the future, the different redshift dependences of the plasma and photon mass contributions to DM can be used to improve the sensitivity to $m_\gamma$ if more FRB redshifts are measured. For a fixed fractional uncertainty in the extra-galactic contribution to the DM of an FRB, one with a lower redshift would provide greater sensitivity to $m_\gamma$.Comment: 13 pages; 1 figure; dedicated to the memory of Lev Okun, an expert on photon mass; version accepted for publication in PL

Single boson exchange representation of the functional renormalization group for strongly interacting many-electron systems

We present a reformulation of the functional renormalization group (fRG) for many-electron systems, which relies on the recently introduced single boson exchange (SBE) representation of the parquet equations [Phys. Rev. B 100, 155149 (2019)]. The latter exploits a diagrammatic decomposition, which classifies the contributions to the full scattering amplitude in terms of their reducibility with respect to cutting one interaction line, naturally distinguishing the processes mediated by the exchange of a single boson in the different channels. We apply this idea to the fRG by splitting the one-loop fRG flow equations for the vertex function into SBE contributions and a residual four-point fermionic vertex. Similarly as in the case of parquet solvers, recasting the fRG algorithm in the SBE representation offers both computational and interpretative advantages: the SBE decomposition not only significantly reduces the numerical effort of treating the high-frequency asymptotics of the flowing vertices, but it also allows for a clear physical identification of the collective degrees of freedom at play. We illustrate the advantages of an SBE formulation of fRG-based schemes, by computing through the merger of dynamical mean-field theory and fRG the susceptibilities and the Yukawa couplings of the two-dimensional Hubbard model from weak to strong coupling, for which we also present an intuitive physical explanation of the results. The SBE formulation of the one-loop flow equations paves a promising route for future multiboson and multiloop extensions of fRG-based algorithms.Comment: 22 Pages, 18 figure

Graded-material Design based on Phase-field and Topology Optimization

In the present work we introduce a novel graded-material design based on phase-field and topology optimization. The main novelty of this work comes from the introduction of an additional phase-field variable in the classical single-material phase-field topology optimization algorithm. This new variable is used to grade the material properties in a continuous fashion. Two different numerical examples are discussed, in both of them we perform sensitivity studies to asses the effects of different model parameters onto the resulting structure. From the presented results we can observe that the proposed algorithm adds additional freedom in the design, exploiting the higher flexibility coming from additive manufacturing technology

Additive manufacturing graded-material design based on phase-field and topology optimization

In the present work we introduce a novel graded-material design for additive manufacturing based on phase-field and topology optimization. The main novelty of this work comes from the introduction of an additional phase-field variable in the classical single-material phase-field topology optimization algorithm. This new variable is used to grade the material properties in a continuous fashion. Two different numerical examples are discussed, in both of them we perform sensitivity studies to asses the effects of different model parameters onto the resulting structure. From the presented results we can observe that the proposed algorithm adds additional freedom in the design, exploiting the higher flexibility coming from additive manufacturing technology