385 research outputs found
Le magistrature in Bodin
No full textThis essay is based on a deepened analysis of the main political works of Jean Bodin and is a part of a collective investigation concerning the different patterns of “republican” magistracy and their evaluation in the history of western political thought. As the other scientific contributions collected in the monographic issue 2007-2 of the review “Il pensiero politico” (entitled Magistrature repubblicane. Modelli nella storia del pensiero politico), it was first presented as a paper during a Congress on the same subject (Perugia and Gubbio, autumn 2006) and was subsequently duly revised and increased in view of its publication. Its main attention concentrates on the pages of Bodin’s Methodus ad facilem historiarum cognitionem and République, in which the author, starting from his general conception of the magistrate’s power and duties and of their relationship to the summum imperium of the sovereign, to the subordinate public officers (lacking in imperium publicum), and to the simple subjects or cives, aimed to demonstrate the “scientific” worth of his original theory of the gubernatio: indeed, having recourse to an historical comparative method, he proved the rightness of his original distinction between State and government with reference to the political and institutional system of the most outstanding States in the world history, including Monarchies, and popular or aristocratic Republics. This effort is particularly evident in Methodus, where Bodin pointed out and put in comparison several historical political patterns, describing in detail the original characters and the evolution of their institutions and of their administrative and judicial organization, i.e. the proper field of the magistrate’s imperium legitimum and of its main functions: the legis actio and the judicis officium. From this point of view, Bodin did not make any difference between Monarchies and Republics and he did not hide, for instance, his admiration of the Roman republic’s equilibrated governmental system, or his great interest in the political institutions of other famous Republics. He was especially anxious to prove that, as well as in the Monarchies, in all “popular” States, and particularly in Rome, where its authority was very high, the Senate hadn’t had or still had not at the time, any share nor of the sovereignty, nor of the magistrate’s imperium legitimum: it was a consultative organism, indeed, accomplishing the political function of the consilium, which was and should remain quite distinct from the sovereign’s summum imperium and from the magistrate’s executio. In this way Bodin confuted the theory of the “mixed” State, tough he considered –at least ideally- the magistrate’s subordinate and “moderate” power being a factual moral moderating restraint to the sovereign’s power. Nevertheless, Bodin pointed out that his analysis of the republican magistracy was mainly based on the right institutional patterns as established by the constitutional rules of each republic considered by him, apart consequently from their real political and administrative praxis, which had been or still was very often corrupted and abusive. That’s why, with increased vehemence in République, he sharply criticized all kind of popular State, where inefficiency and corruption easily affected the magistrates and the public administration. Consequently, also from this point of view, Bodin could affirm the excellence of the monarchical regime. In this way, his “scientific” analysis of the republican magistracy, especially in the République, led directly to his peculiar monarchical ideology, based on an ideal of self-moderating absolute power of the Kings and on a program of social pluralism as regards the subject’s participation to the working of the governmental machine
Transient DNA‐Based Nanostructures Controlled by Redox Inputs
No full textSynthetic DNA has emerged as a powerful selfassembled material for the engineering of nanoscale supramolecular
devices and materials. Initial examples were focused on
thermodynamically driven self-assembly of DNA-based structures
with exquisite near-angstrom control of their geometry. More recently
dissipative self-assembly of DNA-based supramolecular structures
has emerged as a novel approach providing access to a new class
of kinetically-controlled DNA materials with unprecedented life-like
properties. In the examples reported so far, dissipative control has
been achieved using DNA-recognizing enzymes as energy
dissipating units. Although highly efficient, enzymes pose limits in
terms of long term stability and inhibition of enzyme activity by waste
products. Here we provide the first example of kinetically controlled
DNA nanostructures in which energy dissipation is achieved through
a non-enzymatic chemical reaction. More specifically, inspired by the
redox signalling employed by cells to control cellular processes, we
employ redox cycles of disulfide-bond formation/breakage to
kinetically control the assembly and disassembly of DNA tubular
nanostructures in a highly controllable and reversible fashion. To this
purpose, we have rationally designed disulfide DNA strands acting
as regulators for the assembly or disassembly of the DNA-based
structures. Upon reduction these strands loose their regulatory
function which causes the system to return to the basal nonassembled resting state. The exploitation of redox chemistry as a
new control mechanism will facilitate the implementation of fuelledDNA self-assembly processes in a synthetic context without the
limitations linked to the use of enzymatic reactions
Design of Specific Nucleic Acid‐Based Biosensors for Protein Binding Activity
No full textNucleic acid-based biosensors for the detection of specific proteins combine the typical programmability of synthetic DNA systems with artificially controlled DNA-protein communication. The high-affinity interaction between a target protein and a specific ligand, such as an aptamer sequence, or a double stranded DNA domain, or a small peptide, is paired with a nature-mimicking molecular mechanism allowing for probing, processing, and translating protein binding activity into a measurable signal. In this Review, two main strategies developed in the context of protein-responsive nucleic acid-based biosensors are discussed. One is the design of proximity-based assays harnessing the spatial colocalization of functional probes within the volume of a multivalent protein. The other is the engineering of dynamic DNA structures that undergo a controlled conformational or structural change upon protein binding. Examples of applications from optical and electrochemical detection of antibodies in biofluids to fluorescence imaging of transcription factors in living cells are reported, and suggestions along with possible future directions in the field are discussed
Bellini Digital Correspondence
No full textBellini Digital Correspondence (BDC) è il nome assegnato al progetto software di edizione scientifica digitale relativo alle lettere autografe di Vincenzo Bellini. Il fondo è conservato presso il Museo Belliniano di Catania. Il carteggio comprende 40 unità testuali per 35 unità codicologiche. BDC implementa una piattaforma per la filologia digitale applicata al testo belliniano la cui base critica si regge sul lavoro realizzato dalla prof.ssa Graziella Seminara. L'edizione tiene conto di diverse tipologie di fruitori: specialisti, visitatori del museo, che usufruiscono dell'edizione all'interno del percorso museale. L’edizione digitale è stata realizzata in accordo con le linee guida della TEI e integra una fruizione via Web grazie al software EVT. BDC è completamente open source e open access. La piattaforma Web illustra con dovizia di particolari tutte le fasi del progetto di edizione, i principi editoriali, le scelte di rappresentazione digitale del testo e l'ampio gruppo di persone coinvolte
Dissipative Synthetic DNA-Based Receptors for the Transient Loading and Release of Molecular Cargo
No full textSupramolecular chemistry is moving into a direction
in which the composition of a chemical equilibrium is no
longer determined by thermodynamics but by the efficiency
with which kinetic states can be populated by energy consuming processes. Herein, we show that DNA is ideally suited for
programming chemically fueled dissipative self-assembly processes. Advantages of the DNA-based systems presented in this
study include a perfect control over the activation site for the
chemical fuel in terms of selectivity and affinity, highly selective
fuel consumption that occurs exclusively in the activated
complex, and a high tolerance for the presence of waste
products. Finally, it is shown that chemical fuels can be used to
selectively activate different functions in a system of higher
complexity embedded with multiple response pathway
An information ratchet improves selectivity in molecular recognition under non-equilibrium conditions
No full textMolecular recognition is essential for controlling chemical processes, passing molecular instructions to elicit responses including structure formation, signalling and replication. Usually, the selectivity of molecular recognition is under thermodynamic control; however, when a higher fidelity is required, nature improves recognition selectivity by an error correction mechanism under an energy-dissipating kinetic-control regime. Here, exploiting DNA hybridization as a model, we present an abiotic example of an information ratchet mechanism that increases selectivity for the ‘correct’ duplex from 2:1 at equilibrium to 6:1 under energy-dissipating conditions. Structural asymmetry in the DNA strands introduces kinetic asymmetry in the reaction network, enabling enrichment under non-equilibrium conditions. We quantify the free-energy cost associated with enhanced selectivity using Shannon entropy formalism, finding that an increase in information of 0.33 bits is associated with at least 3.0 kJ mol−1 of free energy. Moreover, the minimalistic structures of our error reduction system demonstrates that biomachinery is not necessary to increase molecular recognition fidelities above the thermodynamically expected values, thereby pointing a way towards solving Eigen’s paradox
Methodus (Methodice)
No full textThis essay was originally published in the book Il lessico della politica di Johannes Althusius, edited by F. Ingravalle and C. Malandrino (Firenze, Leo S. Olschki, 2005, pdf available). The present German version is edited by the same C. Malandrino and by D. Wieduckel. The essay focuses the meanings and the significance of the words methodus and methodice in the works of Johannes Althusius. The analysis of their presence in the Althusius’s books is preceded by a survey of their use from the ancient time to the 16th century, when the question of renewing the different sciences and their teaching by the use of a proper method became a main matter of discussion and excited every scholarly milieu. Cesare Vasoli and Guido Oldrini have pointed out the role played by Philipp Melanchton and Johannes Sturm in spreading the consciousness of the necessity to apply the methodus, conceived as ratio docendi, to all fields of knowledge, as well as the influence exerted by Sturm on his pupil Petrus Ramus, whose lectures and writings on method, in their turn, influenced fruitfully the works of Jean Bodin and Johannes Althusius.
Althusius assimilated the Ramus’s doctrine in Basel, where it had been propagated some years before by the law professor Johannes Freigius, and where it was still praised and taught by Theodor Zwinger and by Johannes Blistenius. Althusius’s first work, Juris romani libri duo, issued in Basel in 1586, explicitly aimed to apply the methodus ramea to the treatment of the roman law.
The German jurist did not develop any theoretic discussion about method. Its definition was no more a question at the time. He simply engaged himself in applying the ramistic method to the teaching fields which interested him as well as scholar, as university professor and as political thinker: the roman law, the general science of law, ethics and politics. His intention of proceeding “methodically” was declared in the titles of his books and in their prefaces: their author aimed to give a systematic rational order to the complex and chaotic matters he was going to treat; the observance of the “three rules” of the ramistic method should make his pupils and his readers able to proceed from the most general knowledge to every particular case and to ascribe every subject to its proper field.
The Althusius’s care to apply rightly the ramistic method to the political matter in order to make politics a true science, easy to be understood and learned, was openly stated in the preface of the first edition of the Politica methodice digesta. To this purpose –he wrote – it was necessary to distinguish the subjects pertaining to politics and to its aim (i.e. to the institution and preservation of the human society) from those pertaining to other human sciences, as law, ethics, theology and philosophy. Though the second edition of the work, in 1610, was clearly influenced by the new experience of the author as Syndikus of Emden and by his engagement in the religious and political ideology of this town, he did not cease to recall the rules of the ramistic method, and he was worry to demonstrate that the new subjects and exempla introduced in his book corresponded to their observance. In the edition of 1614, whose preface reproduced the preface of 1610, the lex methodi was recalled in the final pages, where Althusius justified the lack in his book of a chapter dedicated to the causes of destruction of the consociatio and refused other criticisms to his work. The care to observe the ramistic method’s rules did not leave Althusius along all his life; they have been indeed, according to his words, the “pole star” which oriented his way of passionate scholar, teacher and politician
DNA tile self-assembly guided by base excision repair enzymes
No full textWe demonstrate here the use of DNA repair enzymes to control the assembly of DNA-based structures. To do so, we employed uracil-DNA glycosylase (UDG) and formamidopyrimidine DNA glycosylase (Fpg), two enzymes involved in the base excision repair (BER) pathway. We designed two responsive nucleic acid modules containing mutated bases (deoxyuridine or 8-oxo-7,8-dihydroguanine recognized by UDG and Fpg, respectively) that, upon the enzyme repair activity, release a nucleic acid strand that induces the self-assembly of DNA tiles into tubular structures. The approach is programmable, specific and orthogonal and the two responsive modules can be used in the same solution without crosstalk. This allows to assemble structures formed by two different tiles in which the tile distribution can be accurately predicted as a function of the relative activity of each enzyme. Finally, we show that BER-enzyme inhibitors can also be used to control DNA-tile assembly in a specific and concentration-dependent manner
Autonomous and Programmable Reorganization of DNA‐Based Polymers Using Redox Chemistry**
No full textWe demonstrate here a strategy that allows the programmable and autonomous reorganization of self-assembled DNA polymers using redox chemistry. We have rationally designed different DNA monomers (tiles) that can co-assemble into tubular structures. The tiles can be orthogonally activated/deactivated with disulfide-linked DNA fuel strands that are degraded over time upon reduction because of the presence of a reducing agent in the system. The concentration of the disulfide fuels determines the activation kinetics of each DNA tile, which controls the degree of order/disorder in the formed co-polymer. The disulfide-reduction pathway can be employed together with enzymatic fuel-degradation pathways providing an additional level of control in the re-organization of DNA structures. Taking advantage of the different pH-sensitivities of disulfide-thiol and enzymatic reactions, we show that we can control the order in DNA-based co-polymers as a function of pH
Dynamic and Reversible Decoration of DNA‐Based Scaffolds
No full textAn approach to achieving dynamic and reversible decoration of DNA-based scaffolds is demonstrated here. To do this, rationally engineered DNA tiles containing enzyme-responsive strands covalently conjugated to different molecular labels are employed. These strands are designed to be recognized and degraded by specific enzymes (i.e., Ribonuclease H, RNase H, or Uracil DNA Glycosylase, UDG) inducing their spontaneous de-hybridization from the assembled tile and replacement by a new strand conjugated to a different label. Multiple enzyme-responsive strands that specifically respond to different enzymes allow for dynamic, orthogonal, and reversible decoration of the DNA structures. As a proof-of-principle of the strategy, the possibility to orthogonally control the distribution of different labels (i.e., fluorophores and small molecules) on the same scaffold without crosstalk is demonstrated. By doing so, DNA scaffolds that display different antibody recognition patterns are obtained. The approach offers the possibility to control the decoration of higher-order supramolecular assemblies (including origami) with several functional moieties to achieve functional biomaterials with improved adaptability, precision, and sensing capabilities
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