Spectral Methods and Running Scales in Causal Dynamical Triangulations

The spectrum of the Laplace-Beltrami operator, computed on the spatial slices of Causal Dynamical Triangulations, is a powerful probe of the geometrical properties of the configurations sampled in the various phases of the lattice theory. We study the behavior of the lowest eigenvalues of the spectrum and show that this can provide information about the running of length scales as a function of the bare parameters of the theory, hence about the critical behavior around possible second order transition points in the CDT phase diagram, where a continuum limit could be defined.Comment: 5 pages, 6 figure

Non-equilibrium thermodynamics of the spin Seebeck and spin Peltier effects

We study the problem of magnetization and heat currents and their associated thermodynamic forces in a magnetic system by focusing on the magnetization transport in ferromagnetic insulators like YIG. The resulting theory is applied to the longitudinal spin Seebeck and the spin Peltier effects. By focusing on the specific geometry with one YIG layer and one Pt layer, we obtain the optimal conditions for generating large magnetization currents into Pt or large temperature effects in YIG. The theoretical predictions are compared with experiments from the literature permitting to derive the values of the thermomagnetic coefficients of YIG: the magnetization diffusion length $l_M \sim 0.4 \, \mu$m and the absolute thermomagnetic power coefficient $\epsilon_M \sim 10^{-2}$ TK$^{-1}$.Comment: accepted for publication on Physical Review

Non-equilibrium thermodynamics of the longitudinal spin Seebeck effect

In this paper we employ non equilibrium thermodynamics of fluxes and forces to describe magnetization and heat transport. By the theory we are able to identify the thermodynamic driving force of the magnetization current as the gradient of the effective field $\nabla H^*$. This definition permits to define the spin Seebeck coefficient $\epsilon_M$ which relates $\nabla H^*$ and the temperature gradient $\nabla T$. By applying the theory to the geometry of the longitudinal spin Seebeck effect we are able to obtain the optimal conditions for generating large magnetization currents. Furthermore, by using the results of recent experiments, we obtain an order of magnitude for the value of $\epsilon_{M} \sim 10^{-2}$ TK$^{-1}$ for yttrium iron garnet (Y$_3$Fe$_5$O$_{12}$).Comment: accepted for publication on Physics Procedi

Stationary entanglement in N-atom subradiant degenerate cascade systems

We address ultracold $N$-atom degenerate cascade systems and show that stationary subradiant states, already observed in the semiclassical regime, also exist in a fully quantum regime and for a small number of atoms. We explicitly evaluate the amount of stationary entanglement for the two-atom configuration and show full inseparability for the three-atom case. We also show that a continuous variable description of the systems is not suitable to detect entanglement due to the nonGaussianity of subradiant states.Comment: 4 figure

Spectral Methods in Causal Dynamical Triangulations

We show recent results of the application of spectral analysis in the setting of the Monte Carlo approach to Quantum Gravity known as Causal Dynamical Triangulations (CDT), discussing the behavior of the lowest lying eigenvalues of the Laplace-Beltrami operator computed on spatial slices. This kind of analysis provides information about running scales of the theory and about the critical behaviour around a possible second order transition in the CDT phase diagram, discussing the implications for the continuum limit.Comment: Proceeding of Science for parallel talk at the 37th International Symposium on Lattice Field Theory - Lattice2019, 16-22 June 2019, Wuhan, Chin

Family Business: Modelli di Governance ed Assetti Proprietari

L’attività di ricerca si è tesa ad analizzare le strategie di governo delle imprese familiari, ed ha avuto come obiettivo principale quello di poter costituire un contributo all’evidenziazione delle particolarità del family business nei processi di gestione e di creazione del valore, nonché ai rapporti tra patrimonio familiare ed azienda. Il family business è oggetto di attenzione da parte di operatori e studiosi d’impresa per ampiezza del fenomeno nel panorama imprenditoriale e per le ricorrenti criticità e instabilità che le analisi empiriche hanno evidenziato negli assetti organizzativi e strategici, in relazione alle modalità di esercizio del potere, nei rapporti interni e con stakeholders esterni. Gli effetti del carattere family nel governo dell’impresa, nell’ambito della ricerca effettuata, sono stati analizzati in chiave di sovrapposizione istituzionale: prendendo le mosse dalle specificità delle istituzioni coinvolte – famiglia e impresa – e dei rispettivi quadri etici di riferimento, tendendo ad imputare alla difficile conciliabilità di questi ultimi la causa di quelle criticità e instabilità. Infatti si è avuto modo di constatare che gli elementi tipici che contraddistinguono imprese family e da imprese non family possono considerarsi gli estremi di un continum all’interno del quale, a seconda della intensità della presenza della proprietà familiare, la qualità del controllo manageriale e le attese nel ricambio generazionale. Il tema degli assetti di governo nelle imprese familiari ha acquisito rilevanza nella vasta disciplina della corporate governance solo nell’ultimo ventennio, a dispetto di uno scarsissimo interesse mostrato dagli studiosi fino ad oltre la metà degli anni Ottanta. Rispetto alle imprese non familiari, i meccanismi di governance tipici di un family business tendono a disciplinare anche il rapporto tra impresa e famiglia, e, talvolta anche il difficile campo delle relazioni tra i soggetti della famiglia, influenzate di sovente dalle scelte operate in azienda. Dinanzi a tali esigenze si sono affermati meccanismi di governance anche informali, che vanno dai “ patti di famiglia” e i family office, che nell’ultimo lustro hanno trovato ampio consenso anche nella pratica, fino alle “kitchen tables” , cioè meeting familiari “ intorno al tavolo” , durante i quali vengono prese decisioni anche rilevanti per l’impresa. Gli assetti di governo delle imprese a conduzione familiare vengono definiti tendenzialmente stabili, o “inerziali”, perché una volta raggiunto un equilibrio condiviso dai diversi soggetti, è spesso necessario attendere eventi importanti, come la successione generazionale o un cambio nella proprietà ( per limitarsi ai due principali), per assistere ad una modifica sostanziale nei meccanismi di governance. Gli studi empirici sulla governance nelle imprese familiari italiane sono giunti a conclusioni fortemente contrastanti fra loro: mentre alcuni economisti hanno sottolineato in maniera molto critica la mancanza assoluta di meccanismi adeguati nelle imprese italiane, altri invece, hanno evidenziate come, almeno da un punto di vista formale, le imprese italiane siano in linea con quanto osservato negli Stati Uniti. La finalità del presente contributo è duplice: innanzitutto offrire un quadro sistematico dei meccanismi di governo nelle aziende di famiglia, partendo dall’idea che non esista un unico modello di governance sempre valido, ma che le mutevoli circostanze che caratterizzano la vita dell’impresa abbiano un effetto significativo anche sugli assetti proprietari e la forma di governo. Uno degli aspetti principali e tuttavia poco indagato dagli studiosi di corporate governance, è il “tipo di leadership esercitata”: una proprietà molto presente, poco disposta a delegare funzioni anche importanti all’interno dell’impresa, in grado di esercitare il proprio potere attraverso una leadership carismatica, comporta un appiattimento dell’intera struttura su una sola figura, svuotando di potere effettivo tutti gli altri organi decisionali. Al contrario, in presenza di una leadership condivisa, il coinvolgimento di più persone comporta lo sviluppo di una gestione più collegiale, meno legata alle intuizioni di uno solo o di gruppo ristretto di individui

Coexistence of three EGFR mutations in an NSCLC patient: A brief report

The epidermal growth factor receptor (EGFR) represents a molecular target for tyrosine kinase inhibitors for non-small cell lung cancer (NSCLC) patients with a mutation in the EGFR gene. Mutations of the EGFR gene that occur at a single position in NSCLC tissue are found as single, whereas two or more mutations on the same allele are poorly detected and investigated

Non-equilibrium Thermodynamics of the Longitudinal Spin Seebeck Effect

In this paper we employ non equilibrium thermodynamics of fluxes and forces to describe magnetization and heat transport. By the theory we are able to identify the thermodynamic driving force of the magnetization current as the gradient of the effective field ▿H∗. This definition permits to define the spin Seebeck coefficient ϵM which relates ▿H∗ and the temperature gradient ▿T. By applying the theory to the geometry of the longitudinal spin Seebeck effect we are able to obtain the optimal conditions for generating large magnetization currents. Furthermore, by using the results of recent experiments, we obtain an order of magnitude for the value of ϵM ∼ 10-2 TK-1 for yttrium iron garnet (Y3Fe5O12)

On the potential and limitations of quantum extreme learning machines

Quantum reservoir computers (QRC) and quantum extreme learning machines (QELM) aim to efficiently post-process the outcome of fixed -- generally uncalibrated -- quantum devices to solve tasks such as the estimation of the properties of quantum states. The characterisation of their potential and limitations, which is currently lacking, will enable the full deployment of such approaches to problems of system identification, device performance optimization, and state or process reconstruction. We present a framework to model QRCs and QELMs, showing that they can be concisely described via single effective measurements, and provide an explicit characterisation of the information exactly retrievable with such protocols. We furthermore find a close analogy between the training process of QELMs and that of reconstructing the effective measurement characterising the given device. Our analysis paves the way to a more thorough understanding of the capabilities and limitations of both QELMs and QRCs, and has the potential to become a powerful measurement paradigm for quantum state estimation that is more resilient to noise and imperfections.Comment: 12 pages, 7 figures, comments welcom

Contaminant effect on cellular metabolic differential pressure curves.

The possibility of a pressure monitoring system by differential pressure sensors to detect contaminant effects on cellular cultures metabolic activity is discussed using Saccharomyces cerevisiae, lymphocyte, and AHH1 cell cultures. Metabolic (aerobic and anaerobic) processes in cells are accompanied by CO2 production that induces changes in pressure values when cells are cultured in sealed vessels. These values are subsequently converted in voltage units and plotted pressure dynamics versus time. This procedure leads to a standard curve, typical of the cellular line, which characterizes cellular metabolism when all parameters are controlled, such as temperature and nutrients. Different phases appear in the S. cerevisiae differential pressure curve: an initial growth up to a maximum, followed by a decrement that leads to a typical "depression" (pressure values inside the test-tubes are lower than the initial one) after about 35 h from the beginning. The S. cerevisiae differential pressure curve is successfully used to test the effects of chemical (Amuchina(R), trieline) and physical (UV radiation, blue light, magnetic fields) contaminants. The same technique is applied to lymphocytes and AHH1 cultures to investigate the effects generated by a 72-h exposure to a 50-Hz, 60-muT electromagnetic field. Lymphocyte samples, cultured in a PHA medium, grow less than control ones, but exhibit a greater metabolic activity: changes in the exposure system configuration influence neither sample growth differences nor metabolic response variations between control and irradiated samples, while all the other irradiation parameters remain constant. Control and irradiated lymphocyte samples, without PHA in culture medium, show the same behavior both during irradiation and metabolic test. AHH1 control and irradiated samples show no difference both in growth percentage during irradiation and in metabolic activity. Different cell cultures respond to the same stimulus in different manners. (C) 2004 Society of Photo-Optical Instrumentation Engineers