Scattering Amplitude Recursion Relations in BV Quantisable Theories

Tree-level scattering amplitudes in Yang-Mills theory satisfy a recursion relation due to Berends and Giele which yields e.g. the famous Parke-Taylor formula for MHV amplitudes. We show that the origin of this recursion relation becomes clear in the BV formalism, which encodes a field theory in an $L_\infty$-algebra. The recursion relation is obtained in the transition to a smallest representative in the quasi-isomorphism class of that $L_\infty$-algebra, known as a minimal model. In fact, the quasi-isomorphism contains all the information about the scattering theory. As we explain, the computation of such a minimal model is readily performed in any BV quantisable theory, which, in turn, produces recursion relations for its tree-level scattering amplitudes.Comment: 33 pages, minor improvements, typos corrected, references added, published versio

Ion exchange in silicate glass: mass average interdiffusion coefficient determination

The mass average interdiffusion coefficient DM is an approximated constant value of the interdiffusion coefficient which is relevant in the kinetics of ion exchange in silicate glasses. In this study, it is presented a simple technique for its determination based on the weight change of a glass sample after ion exchange. The theoretical basis of the method is presented in detail together with the approximations assumed in considering the constancy of the DM . Experimental results are presented for soda-lime silicate glasses and it is demonstrated the correlation of DM with the ion exchange temperature following an Arrhenius-type equation with an energy activation barrier and a pre-exponential factor. The determination of the mass average interdiffusion coefficient allows the estimation of the compression layer depth when a stress profile is build-up as a consequence of ion exchange. The estimated values of the compression layer depth have been compared with the ones measured by an optical technique based on differential surface refractometry (DSR). Values have been found quite compatible with the uncertainty limits indicated by the DSR method.Comment: 12 pages, 3 figures, 4 tables, 27 equations, 16 reference

Finite symmetry groups and orbifolds of two-dimensional toroidal conformal field theories

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Ethanol from Sugarcane Lignocellulosic Residues - Opportunities for Process Improvement and Production Cost Reduction

Bioethanol from sugarcane is a sustainable alternative to fossil fuels, and the increasing demand for fuel ethanol has prompted studies on the use of the lignocellulosic residues of sugarcane, namely bagasse and leaves, as new feedstock. This thesis describes various process designs and the economic feasibility of producing second generation (2G) ethanol from bagasse and leaves via the enzymatic route in an integrated sugarcane biorefinery, where first-generation (1G) ethanol is produced from sugarcane sugar. Techno-economic analysis have been performed for the Brazilian context to evaluate the influence of several process designs and the main production factors on the 2G ethanol process, in terms of energy efficiency, 2G ethanol production cost(2G MESP) and profitability. The study of process design focused on ways to integrate the 1G and 2G ethanol processes, and on configurations to hydrolyse and ferment bagasse. The existing 1G ethanol process and the proposed 2G ethanol process were combined in a single plant by integration of thermal and material streams. The resulting synergies could improve the use of feedstock and reduce the 2G ethanol production cost. Simultaneous saccharification and fermentation (SSF)and time-separated hydrolysis and fermentation (tSHF) were the configurations investigated experimentally for the production of 2G ethanol from bagasse. In an attempt to increase the ethanol concentration before distillation, the fermented liquid of tSHF was also recirculated back to tSHF. The tSHF configurations showed a lower 2G MESP than SSF. Process options were also investigated considering the pentose use and the addition of leaves to the 1G+2G process. Pentoses can either be fermented to ethanol or anaerobically digested to produce electricity from biogas combustion, and in the former case the highest potential reduction in 2G MESP could be achieved. The addition of leaves could improve the overall profitability of the 1G+2G process. Residence time and water-insoluble solids (WIS) loading in hydrolysis were the main process conditions considered together with costing factors, such as enzyme, sugarcane and leaves costs. The selling price of electricity and ethanol were found to have relevant impacts on the profitability of the 1G+2G ethanol process. Among the numerous operating conditions studied for the 2G ethanol process, the cases showing the best trade-off between technical and economic feasibility were also tested experimentally on laboratory scale obtaining promising results. In fact, it was possible to achieve high concentrations of 2G ethanol (47 g/L) in short time (60 hours), overcoming the mixing problems by feeding repeatedly the pretreated bagasse up to 20% WIS

Techno-economic evaluation of 2nd generation bioethanol production from sugar cane bagasse and leaves integrated with the sugar-based ethanol process

<p>Abstract</p> <p>Background</p> <p>Bioethanol produced from the lignocellulosic fractions of sugar cane (bagasse and leaves), i.e. second generation (2G) bioethanol, has a promising market potential as an automotive fuel; however, the process is still under investigation on pilot/demonstration scale. From a process perspective, improvements in plant design can lower the production cost, providing better profitability and competitiveness if the conversion of the whole sugar cane is considered. Simulations have been performed with AspenPlus to investigate how process integration can affect the minimum ethanol selling price of this 2G process (MESP-2G), as well as improve the plant energy efficiency. This is achieved by integrating the well-established sucrose-to-bioethanol process with the enzymatic process for lignocellulosic materials. Bagasse and leaves were steam pretreated using H₃PO₄as catalyst and separately hydrolysed and fermented.</p> <p>Results</p> <p>The addition of a steam dryer, doubling of the enzyme dosage in enzymatic hydrolysis, including leaves as raw material in the 2G process, heat integration and the use of more energy-efficient equipment led to a 37 % reduction in MESP-2G compared to the Base case. Modelling showed that the MESP for 2G ethanol was 0.97 US$/L, while in the future it could be reduced to 0.78 US$/L. In this case the overall production cost of 1G + 2G ethanol would be about 0.40 US$/L with an output of 102 L/ton dry sugar cane including 50 % leaves. Sensitivity analysis of the future scenario showed that a 50 % decrease in the cost of enzymes, electricity or leaves would lower the MESP-2G by about 20%, 10% and 4.5%, respectively.</p> <p>Conclusions</p> <p>According to the simulations, the production of 2G bioethanol from sugar cane bagasse and leaves in Brazil is already competitive (without subsidies) with 1G starch-based bioethanol production in Europe. Moreover 2G bioethanol could be produced at a lower cost if subsidies were used to compensate for the opportunity cost from the sale of excess electricity and if the cost of enzymes continues to fall.</p

Sulla validità del principio di identità degli indiscernibili in meccanica quantistica: verso una nuova discernibilità debole

Lo scopo di questa tesi di dottorato è quello di discutere la controversa questione sulla validità del principio di identità degli indiscernibili di Leibniz in meccanica quantistica. In particolare, si esporrà un anuova relazone di discernibilità debole (WD) per particelle quantistiche, con l'obiettivo di risolvere le critiche sollevate dal Bigaj (2015). Il pioniere della WD è certamente Simon Saunders (2003, 2006) che ha dimostrato come sia possibile distinguere le particelle in meccanica quantistica con metodi basati sull'utilizzo di predicati qualitativi. Egli ha dimostrato che la WD, può essere applicata a fermioni. Il secondo sostenitore della WD è stato F. A. Muller che ha risolto le critiche sollevate contro Saunders (2008). Muller e Saunders (2008) hanno messo a punto la tecnica della distinguibilità dei fermioni con l'uso delle proprietà categoriali (cioè non probabilistici). Muller e Seevinck (2009) hanno esteso la discernibilità debole per tutte le particelle quantistiche. Bigaj (2015) ha sollevato il problema che la proposta di WD di Muller, Saunders, Seevinck è affetta da circolarità, poiché la scelta dell'operatore, su cui si applica la WD, cambia se le particelle sono o meno la stessa. Se si accettano le critiche di Bigaj, sembra opportuno cercare una nuova discernibilità debole, conciliando le posizioni di Muller, Saunders e Seevinck con quella di Bigaj. Secondo Bigaj (2015), quello che sarebbe giusto dire è che, se la relazione R, su cui si basa la WD, contiene l'identità numerica come una componente essenziale, allora la discernibilità diventa banale e l'intera struttura è circolare. Sarebbe desiderabile, invece, avere lo stesso operatore o almeno la stessa operazione sia nel caso in cui le particelle, a e b, sono a priori diverse sia quando sono uguali. Ad esempio una corretta relazione con un unico operatore O sarebbe tale da potersi scrivere: dove xy. Una nuova relazione di discernibilità debole deriva dall' uso della matrice di Gram, seguendo il formalismo della seconda quantizzazione. Se due particelle sono uguali allora la matrice di Gram ha determinante diverso da zero, altrimenti la matrice di Gram ha determinante pari a zero. Indicando con l'operatore G, l’operazione “determinante della matrice di Gram” è possibile definire la relazione R in questo modo: . Questa relazione soddisfa i requisiti di Bigaj (2015). Inoltre, soddisfa anche il requisito di Muller e Saunders (2008) circa l'invarianza per permutazione (dimostrazione banale). L’unico svantaggio è rappresentato dal significativo fisico non particolarmente incisivo di questo particolare operatore. Questa relazione è valida non solo per fermioni, ma anche per qualsiasi tipo di particella quantistica, come i bosoni

Development of novel Benzothiopyranoindole-based TDP1 inhibitors for anticancer therapy

DNA topoisomerases (Top) are established molecular targets of anticancer drugs. There are two major families of Top: Type I (Top1) and Type II (Top2) depending on whether they cleave only one or two DNA strands. A common feature of topoisomerases is their catalytic mechanism, which, in all cases, consists in a nucleophilic attack of a DNA phosphodiester bond by a catalytic tyrosyl residue from the topoisomerase. The resulting covalent attachment of the tyrosine to the DNA phosphate is either at the 3′-end of the broken DNA, in the case of Top1 enzymes (Top1 and Top1mt), or at the 5′-end of the broken DNA for Top2 ones. As result, a covalent complex was generated between the protein and DNA via a phosphotyrosyl bond (Top1cc and Top2cc). Under normal circumstances, the rate of religation is much faster than the rate of cleavage, which allows the Top1-DNA cleavage complexes to be a transitory intermediate event of the Top1 catalytic cycle. However, a variety of conditions have been shown to increase the frequency of Top1-DNA cleavage complexes by reducing or inhibiting the rate of the religation reaction. For example, Top1 inhibitors, such as camptothecin (CPT) and its clinically used derivatives, as well as several non-CPT Top1 inhibitors, including the indenoisoquinolines and the indolocarbazoles, selectively and reversibly bind to the Top1-DNA interface and slow the rate of Top1-mediated DNA religation. Tyrosyl-DNA phosphodiesterases (TDP1 and TDP2) were recently discovered and named based on the fact they process 3′- and 5′-DNA ends by excising irreversible protein tyrosyl-DNA complexes involving topoisomerases I and II, respectively. For this reason, TDP1 has been regarded as a potential co-target of Top1 for anticancer therapy, in that it seemingly counteracts the effects of Top1 inhibitors. Thus, Tdp1 inhibitors have the potential to augment the anticancer activity of Top1 inhibitors, by reducing the repair of Top1-DNA lesions. During my thesis project, a series of derivatives featuring the benzothiopyranoindole nucleus and hydroxylic groups at different position of the central scaffold were synthesized, in order to perform a structure-activity relationship (SAR) investigation and to obtain compounds with high TDP1 inhibitory activity

Sistemi quantistici con spettro singolarmente continuo

We study some quantum particles systems with singular continuous spectrum. In particular, we focus on one-dimensional quasicrystals, i.e. aperiodic structures with sharp diffraction images, and Bloch electrons in a periodic two-dimensional lattice subject to a perpendicular uniform magnetic field. The last part of the work is devoted to the study of the spectral properties of the almost Mathieu operator, which arises from the mathematical description of the latter system. Our main goal is to explore the many mathematical properties of the systems we consider and to give physical interpretations to them. We use notions and results from Measure Theory and Spectral Theory, which are summarized in the first Chapter.ope

A 32 mV/69 mV input voltage booster based on a piezoelectric transformer for energy harvesting applications

This paper presents a novel method for battery-less circuit start-up from ultra-low voltage energy harvesting sources. The approach proposes for the first time the use of a Piezoelectric Transformer (PT) as the key component of a step-up oscillator. The proposed oscillator circuit is first modelled from a theoretical point of view and then validated experimentally with a commercial PT. The minimum achieved start-up voltage is about 69 mV, with no need for any external magnetic component. Hence, the presented system is compatible with the typical output voltages of thermoelectric generators (TEGs). Oscillation is achieved through a positive feedback coupling the PT with an inverter stage made up of JFETs. All the used components are in perspective compatible with microelectronic and MEMS technologies. In addition, in case the use of a ∼40 μH inductor is acceptable, the minimum start-up voltage becomes as low as about 32 mV