Rigorous simulation of nonlinear optomechanical coupling in micro- and nano-structured resonant cavities

A numerical method aimed to predict the optomechanical dynamics in micro- and nano-structured resonant cavities is introduced here. The rigorousness of it is ensured by exploiting the harmonic version of the transformation optics (TO) technique and by considering all the energytransduction contributions of electrostriction, radiation pressure, photoelasticity and moving boundaries. Since our full-wave approach implements a multi-modal analysis and also considers material losses, from both a mechanical and an optical point of view, a considerable step further has been made in respect to the standard optomechanical perturbative theory. The efficiency and the versatility of the strategy are tested by analysing the optomechanical behaviour of a corrugated Si-based nanobeam and comparing numerical results to experimental ones from the literatur

Advanced numerical investigation of the heat flux in an array of microbolometers

The investigation of the thermal properties of an array of microbolometers has been carried out by mean of two independent numerical analysis, respectively the Direct-Simulation Monte Carlo (DSMC) and the classic diffusive approach of the Fourier's equation. In particular, the thermal dissipation of a hot membrane placed in a low-pressure cavity has been studied for different values of the temperature of the hot body and for different values of the pressure of the environment. The results for the heat flux derived from the two approaches have then been compared and discussed

Gain enhancement of BiCMOS on-chip sub-THz antennas by mean of meta-cells

A MM-loaded sub-THz on-chip antenna with a narrow beamwidth, 9 dB gain and a simulated peak efficiency of 76% at the center frequency of 300 GHz is presented. By surrounding the antenna with a single MM-cell ring defined solely on the top metal of the back-end of line, an efficient suppression of the surface waves is obtained. The on-chip antenna has been designed using IHPs 130 nm SiGe BiCMOS technology with a 7-layer metallization stack, combined with the local backside etching process aimed to creating an air cavity which is then terminated by a reflective plane. By comparing the measured MM-loaded antenna performances to its non-MM-loaded counterpart, an enhanced integrity of the main lobe due to the MM-cells shielding effect can be observed. An excellent agreement between the simulated and measured performances has been found, which makes the MM-loaded antennas a valid alternative for the upcoming next-generation sub-THz transceivers

Effect of steady-state aerobic exercise intensity and duration on the relationship between reserves of heart rate and oxygen uptake

Background. The percentages of heart rate (%HRR) or oxygen uptake (%V̇O2R) reserve are used interchangeably for prescribing aerobic exercise intensity due to their assumed 1:1 relationship, although its validity is debated. This study aimed to assess if %HRR and %V̇O2R show a 1:1 relationship during steady-state exercise (SSE) and if exercise intensity and duration affect their relationship. Methods. Eight physically active males (age 22.6±1.2 years) were enrolled. Pre-exercise and maximal HR and V̇O2 were assessed on the first day. In the following 4 days, different SSEs were performed (running) combining the following randomly assigned durations and intensities: 15 min, 45 min, 60% HRR, 80% HRR. Post-exercise maximal HR and V̇O2 were assessed after each SSE. Using pre-exercise and post-exercise maximal values, the average HR and V̇O2 of the last 5 min of each SSE were converted into percentages of the reserves (%RES), which were computed in a 3-way RM-ANOVA (α=0.05) to assess if they were affected by the prescription parameter (HRR or V̇O2R), exercise intensity (60% or 80% HRR), and duration (15 or 45 min). Results. The %RES values were not affected by the prescription parameter (p=0.056) or its interactions with intensity (p=0.319) or duration and intensity (p=0.117), while parameter and duration interaction was significant (p=0.009). %HRRs and %V̇O2Rs did not differ in the 15-min SSEs (mean difference [MD]=0.7 percentage points, p=0.717), whereas %HRR was higher than %V̇O2R in the 45-min SSEs (MD=6.7 percentage points, p=0.009). Conclusion. SSE duration affects the %HRR-%V̇O2R relationship, with %HRRs higher than %V̇O2Rs in SSEs of longer duration

Defective IGF-1 prohormone N-glycosylation and reduced IGF-1 receptor signaling activation in congenital disorders of glycosylation

none14sìThe insulin-like growth factor-1 (IGF-1) signaling pathway is crucial for the regulation of growth and development. The correct processing of the IGF-1Ea prohormone (proIGF-1Ea) and the IGF-1 receptor (IGF-1R) peptide precursor requires proper N-glycosylation. Deficiencies of N-linked glycosylation lead to a clinically heterogeneous group of inherited diseases called Congenital Disorders of Glycosylation (CDG). The impact of N-glycosylation defects on IGF-1/IGF-1R signaling components is largely unknown. In this study, using dermal fibroblasts from patients with different CDG [PMM2-CDG (n = 7); ALG3-CDG (n = 2); ALG8-CDG (n = 1); GMPPB-CDG (n = 1)], we analyzed the glycosylation pattern of the proIGF-1Ea, IGF-1 secretion efficiency and IGF-1R signaling activity. ALG3-CDG, ALG8-CDG, GMPPB-CDG and some PMM2-CDG fibroblasts showed hypoglycosylation of the proIGF-1Ea and lower IGF-1 secretion when compared with control (CTR). Lower IGF-1 serum concentration was observed in ALG3-CDG, ALG8-CDG and in some patients with PMM2-CDG, supporting our in vitro data. Furthermore, reduced IGF-1R expression level was observed in ALG3-CDG, ALG8-CDG and in some PMM2-CDG fibroblasts. IGF-1-induced IGF-1R activation was lower in most PMM2-CDG fibroblasts and was associated with decreased ERK1/2 phosphorylation as compared to CTR. In general, CDG fibroblasts showed a slight upregulation of Endoplasmic Reticulum (ER) stress genes compared with CTR, uncovering mild ER stress in CDG cells. ER-stress-related gene expression negatively correlated with fibroblasts IGF-1 secretion. This study provides new evidence of a direct link between N-glycosylation defects found in CDG and the impairment of IGF-1/IGF-1R signaling components. Further studies are warranted to determine the clinical consequences of reduced systemic IGF-1 availability and local activity in patients with CDG.openDi Patria, Laura; Annibalini, Giosuè; Morrone, Amelia; Ferri, Lorenzo; Saltarelli, Roberta; Galluzzi, Luca; Diotallevi, Aurora; Bocconcelli, Matteo; Donati, Maria Alice; Barone, Rita; Guerrini, Renzo; Jaeken, Jaak; Stocchi, Vilberto; Barbieri, ElenaDi Patria, Laura; Annibalini, Giosuè; Morrone, Amelia; Ferri, Lorenzo; Saltarelli, Roberta; Galluzzi, Luca; Diotallevi, Aurora; Bocconcelli, Matteo; Donati, Maria Alice; Barone, Rita; Guerrini, Renzo; Jaeken, Jaak; Stocchi, Vilberto; Barbieri, Elen

Dose-escalated pelvic radiotherapy for prostate cancer in definitive or postoperative setting

Purpose Given the absence of standardized planning approach for clinically node-positive (cN1) prostate cancer (PCa), we collected data about the use of prophylactic pelvic irradiation and nodal boost. The aim of the present series is to retrospectively assess clinical outcomes after this approach to compare different multimodal treatment strategies in this scenario. Methods Data from clinical records of patients affected by cN1 PCa and treated in six different Italian institutes with prophylactic pelvic irradiation and boost on pathologic pelvic lymph nodes detected with CT, MRI or choline PET/CT were retrospectively reviewed and collected. Clinical outcomes in terms of overall survival (OS) and biochemical relapse-free survival (b-RFS) were explored. The correlation between outcomes and baseline features (International Society of Urological Pathology-ISUP pattern, total dose to positive pelvic nodes 60 Gy, sequential or simultaneous integrated boost (SIB) administration and definitive vs postoperative treatment) was explored. Results ISUP pattern < 2 was a significant predictor of improved b-RFS (HR = 0.3, 95% CI 0.1220-0.7647, P = 0.0113), while total dose < 60 Gy to positive pelvic nodes was associated with worse b-RFS (HR = 3.59, 95% CI 1.3245-9.741, P = 0.01). Conversely, treatment setting (postoperative vs definitive) and treatment delivery technique (SIB vs sequential boost) were not associated with significant differences in terms of b-RFS (HR = 0.85, 95% CI 0.338-2.169, P = 0.743, and HR = 2.39, 95% CI 0.93-6.111, P = 0.067, respectively). Conclusion Results from the current analysis are in keeping with data from literature showing that pelvic irradiation and boost on positive nodes are effective approaches. Upfront surgical approach was not associated with better clinical outcomes

Full-wave analysis and design of opto-mechanical systems

Le micro-cavità optomeccaniche (OM) sono oggetto di intenso studio, come possibile fonte di nuove funzionalità, concetti e opportunità che vanno oltre la tecnologia standardin termini di propagazione, generazione ed elaborazione dei fononi a microonde al micro e nanoscala. In questo framework, l'interazione OM non lineare è oggetto di indagini approfondite, Il tipo di ricerca sopra riportato è altamente interdisciplinare, e si sposta lungo la frontiera di molti campi, come ad esempio i filtri a microonde per onde acustiche di superficie (SAW), fotonica, elettronica ed, inoltre, nanofisica e ottica quantistica. In particolare, alcuni recenti risultati sul raffreddamento dello stato fondamentale OM promettono un controllo coerente del movimento quantico di risonatori meccanici. Un esempio pertinente è fornito dal recente accoppiamento di un qubit superconduttore alle vibrazioni meccaniche di un risonatore piezoelettrico, ovvero risuonatori meccanici a microonde operati al limite quantico. Meccanismi fondamentali dei sistemi OM, come la pressione di radiazione e la forza elettrostrittiva esercitata da campi elettromagnetici sulla materia e, al contrario, modulazione fotoelastica dei campi elettromagnetici, sono responsabili delle forti interazioni che si verificano nelle cavità risonanti. In effetti, pressioni enormi possono agire nella regione della cavità a causa del fattori Q elevati raggiungibili sia per le modalità ottiche che meccaniche che coesistono nella cavità. Il meccanismo sopra descritto produce utili trasduzioni e attuazioni vibrazionali ai livelli di potenza da µ- a m-watt. Inoltre porta potenzialmente allo sviluppo di fonon laser e rivelatori. È probabile che tale sviluppo consenta l'elaborazione del segnale fononico a temperatura ambiente e l'integrazione di elementi fonetici su una piattaforma di silicio, in grado di generare nuovi modi di elaborare le informazioni. L'obiettivo finale è l'utilizzo di fononi, invece di elettroni, come vettori di informazione e la costruzione di un chip che possa lavorare a temperatura ambiente, analogamente al funzionamento di dispositivi basati su SAW, per applicazioni di filtraggio e rilevamento. I vantaggi di questa nuova tecnologia sono dati, ad esempio, dal possibile funzionamento ad alta frequenza e dal basso consumo energetico. Inoltre, rispetto all'azionamento nanoelettromeccanico puro, l'approccio ottico è meno sensibile ai problemi di discrepanza capacitiva e di impedenza. Alla luce di quanto sopra, la prima parte di questa tesi tratta dell'interpretazione teorica del fenomeno OM che si verifica nelle µ-cavità ad alto Q, con l'obiettivo di fornire un approccio affidabile e rigoroso per massimizzare le prestazioni di un generatore coerente di fononi. Se si considerara il futuro sviluppo della circuiteria OM, avere un metodo in grado di fornire sia l'esatta popolazione fononica generata in una data cavità e la valutazione delle forze ottiche e meccaniche che giocano il loro ruolo nell'interazione tra le due fisiche sarà di fondamentale importanza. Insieme al modello numerico sopra descritto, è stata realizzata anche un'applicazione intuitiva. La seconda parte di questa tesi si concentra sull'eccitazione ottica del generatore di fononi, che propone un design fatto di una lastra di Si che viene prima miscelata e poi inciso selettivamente, in modo che la coda evanescente del campo elettrico possa essere migliorata e, di conseguenza, il trasferimento di energia EM tra tale lastra e la cavità OM può essere massimizzato. Questa soluzione non solo garantisce migliori prestazioni rispetto al approccio standard in fibra ottica, ma è anche adatto per l'integrazione su chip del generatore fononico, dato l'incremento della sua stabilità e affidabilità. Inoltre, sono stati compiuti sforzi per indagare i) l'estrazione del coerente fononi generati, con particolare attenzione all'equilibrio tra l'avere la necessità di un elevato fattore Q (essenziale per consentire il comportamento auto-pompato) insieme con la necessità di generare una perdita di energia meccanica e ii) la progettazione di una guida d'onda a bassa perdita, in grado di trasportare le informazioni fononiche lungo il chip. La terza parte della tesi introduce il SAW come soluzione valida per la lavorazione del fonone. Inizialmente, l'integrazione tra un launcher SAW generico (generalmente effettuata di una combinazione di InterDigitated Transciever (IDT), un materiale piezoelettrico sottile e un Si-substrato) e la cavitá OM é investigata. Un nuovo design in cui i terminali elettrici, ovvero dove viene generato il SAW, sono stati curvati radialmente per facilitare, dal punto di vista geometrico, il focus dell'onda meccanica verso una determinata regione è discusso. Successivamente, il problema di come modellare tale IDT curvo é affrontato. Addizionalmente, al fine di garantire una corretta calibrazione del SAW-launcher, un metodo numerico cha passa dalla sia rappresentazione di tipo Scattering Matrix (SM) sia dell'approccio TRL è stato sviluppato.Optomechanical (OM) micro-cavities are object of intense tudy, as a possible source of new functionalities, concepts, and opportunities beyond standard technology, with regard to microwave phonon propagation, generation, and processing at micro and nanoscale. In this framework, nonlinear OM interaction is being intensively investigated, with a view to advanced device modulation. The above kind of research is highly interdisciplinary, moving along the frontier of many fields, i.e. microwave Surface Acoustic Wave (SAW) filters, photonics, and electronics, and at the boundary between nanophysics and quantum optics. In particular, some recent achievements of OM ground state cooling promise coherent control of the quantum motion of mechanical resonators. A relevant example is provided by the recent coupling of a superconducting qubit to the mechanical vibrations of a piezoelectric resonator, i.e. microwave mechanical resonators operated at the quantum limit. Fundamental mechanisms of OM systems, such as the radiation pressure and the electrostrictive force exerted by electromagnetic fields on the matter, and, reversely, photoelastic modulation of electromagnetic fields, are responsible for strong interactions occurring in resonant cavities. In fact, huge pressures can act in the cavity region, owing to the high Q-factors achievable both for the optical and mechanical modes that coexist in the cavity. The above mechanism yields useful vibrational transduction and actuation at the µ- to m-watt power levels. Also it potentially leads to the development of phonon laser and detectors. Such development is likely to enable processing phonon signal at room temperature and integration of phononic elements on a silicon platform, capable of generating novel ways of information processing. The final objective is using phonons, instead of electrons, as vectors of information and building chips that work at room temperature, analogously to the operation of SAW-based devices, for filtering and sensing applications. Important advantages of this new technology are given, for example, by possible high frequency operation and low power consumption. In addition, comparing with pure nano-electromechanical actuation, the optical approach is less sensitive to capacitive and impedance mismatch issues. Given the above, the first part of this thesis deals with the theoretical interpretation of the OM phenomenon taking place in high-Q µ-cavities, having the aim of providing a reliable and rigorous approach for maximize the performances of a coherent phonon generator. If to consider the future development and progress of the OM circuitry, having a method capable of providing both the exact phononic population generated in a given cavity and the evaluation of the optical and mechanical forces that play their role in the interaction between the two physics, will be of fundamental importance. Together with the aforementioned numerical model, that has additionally been ported to a user-friendly application, original cavity designs exhibiting high degrees of confinement of both the optical and the mechanical resonating modes are given. The second part of this thesis focuses on the optical excitation of the coherent phonon generator, proposing a design made of a Si-slab that is first blended and then selectively etched, so that the evanescent tail of the E-field can be enhanced and, consequently, the EM energy transfer between such slab and the OM cavity can be maximized. This solution not only guarantees better performances in respect to the standard fiber-loop approach, but it is also suitable for an on-chip integration of the phononic generator, given its improved stability and reliability. Additionally, efforts are put in the investigation of i) the extraction of the coherent phonons generated in theOMcavity, with special focus on the balance between having the need of a high Q-factor (essential for enabling the self-pumped behavior) together with the necessity of generating some mechanical energy leak, and ii) the design of a low-loss waveguide, capable of carrying the phononic information along the chip. The third part of the thesis introduces the SAW as a valid solution for the phonon processing. At first, the integration between a generic SAW launcher (generally made of a combination of InterDigitated Transciever (IDT), a thin piezoelectric material and a Si-sustrate) and the targeted OM cavity is investigated. A novel design in which the electrical terminals, e.g. where the SAW is generated, have been radially curved for facilitating, from a geometrical point of view, the focus of the mechanical wave towards a certain region is given. Successively, the issue of modeling such curved IDT fingers is addressed. For ensuring a correct calibration of the SAW-launcher, aimed to isolate the latter from the rest of the OM circuitry, a numerical method making use of both the Scattering Matrix (SM) representation and the TRL approach is developed and tested against its analytic counterpart

Electromagnetic amplification of microwave phonons in nonlinear resonant microcavities

In this paper, we report on the numerical simulation of a multiphysic electromagnetic/mechanical problem, as a further step toward the development of microwave circuits based on phonon propagation at micro and nanoscale. In the future, this kind of circuits is likely to integrate optomechanically pumped phonon sources and detectors, as well as phonon processing components (waveguides, splitters, and memories) to process information by means of phonons. In particular, we propose a rigorous approach for the solution of the electromagnetic/mechanical system of equations governing light behavior in optomechanical cavities, with the help of the transformation optics method. Such a kind of calculation allows the development of an efficient generation of microwave coherent phonon sources, by engineering their propagation or coupling with phonon waveguide

Eustatic and Relative Sea Level Changes

Sea level changes can be driven by either variationsin the masses or volume of the oceans, or bychanges of the land with respect to the sea surface. Inthe first case, a sea level change is defined ‘eustatic’;otherwise, it is defined ‘relative’. Several techniques canbe used to observe changes in sea level, from satellite datato tide gauges to geological or archeological proxies.Regardless of the technique used, ‘eustasy’ cannot bemeasured directly, but only calculated after perturbingfactors of different origins are taken into account. In thispaper, we review the meaning and main processes thatcontribute to eustatic and relative sea level changes, andwe give an overview of the different techniques used toobserve them

Accurate analysis of plasmon propagation in metal and graphene nanostructures

We introduce an accurate analytical and numerical characterization of plasmonic propagation in meso- and nanoheterostructure for noble metal- and graphene-based device configurations. The method developes into three steps, i) the Kretschmann configuration technique, ii) the transfer matrices approach and iii) a full-wave multi-scale numerical simulation. The method is first tested by comparing theoretical results to experimental ones from the literature, and then applied to investigate plasmon propagation in graphene-based devices. The final aim is the full-wave design of plasmonic components/devices ranging from the THz to the optical range, involving both noble metals and energing 2D-materials, e.g. graphen