Quantum noise in ideal operational amplifiers

We consider a model of quantum measurement built on an ideal operational amplifier operating in the limit of infinite gain, infinite input impedance and null output impedance and with a feddback loop. We evaluate the intensity and voltage noises which have to be added to the classical amplification equations in order to fulfill the requirements of quantum mechanics. We give a description of this measurement device as a quantum network scattering quantum fluctuations from input to output ports.Comment: 4 pages, 2 figures, RevTe

Back-action cancellation in interferometers by quantum locking

We show that back-action noise in interferometric measurements such as gravitational-waves detectors can be completely suppressed by a local control of mirrors motion. An optomechanical sensor with an optimized measurement strategy is used to monitor mirror displacements. A feedback loop then eliminates radiation-pressure effects without adding noise. This very efficient technique leads to an increased sensitivity for the interferometric measurement, which becomes only limited by phase noise. Back-action cancellation is furthermore insensitive to losses in the interferometer.Comment: 4 pages, 3 figures, RevTe

Quantum fluctuations for drag free geodesic motion

The drag free technique is used to force a proof mass to follow a geodesic motion. The mass is protected from perturbations by a cage, and the motion of the latter is actively controlled to follow the motion of the proof mass. We present a theoretical analysis of the effects of quantum fluctuations for this technique. We show that a perfect drag free operation is in principle possible at the quantum level, in spite of the back action exerted on the mass by the position sensor.Comment: 4 pages, 1 figure, RevTeX, minor change

Endoscopic management of gastrointestinal leaks and fistulae: What option do we have?

Gastrointestinal leaks and fistulae are serious, potentially life threatening conditions that may occur with a wide variety of clinical presentations. Leaks are mostly related to post-operative anastomotic defects and are responsible for an important share of surgical morbidity and mortality. Chronic leaks and long standing post-operative collections may evolve in a fistula between two epithelialized structures. Endoscopy has earned a pivotal role in the management of gastrointestinal defects both as first line and as rescue treatment. Endotherapy is a minimally invasive, effective approach with lower morbidity and mortality compared to revisional surgery. Clips and luminal stents are the pioneer of gastrointestinal (GI) defect endotherapy, whereas innovative endoscopic closure devices and techniques, such as endoscopic internal drainage, suturing system and vacuum therapy, has broadened the indications of endoscopy for the management of GI wall defect. Although several endoscopic options are currently used, a standardized evidence-based algorithm for management of GI defect is not available. Successful management of gastrointestinal leaks and fistulae requires a tailored and multidisciplinary approach based on clinical presentation, defect features (size, location and onset time), local expertise and the availability of devices. In this review, we analyze different endoscopic approaches, which we selected on the basis of the available literature and our own experience. Then, we evaluate the overall efficacy and procedural-specific strengths and weaknesses of each approach

Frontal brain asymmetries as effective parameters to assess the quality of audiovisual stimuli perception in adult and young cochlear implant users

How is music perceived by cochlear implant (CI) users? This question arises as "the next step" given the impressive performance obtained by these patients in language perception. Furthermore, how can music perception be evaluated beyond self-report rating, in order to obtain measurable data? To address this question, estimation of the frontal electroencephalographic (EEG) alpha activity imbalance, acquired through a 19-channel EEG cap, appears to be a suitable instrument to measure the approach/withdrawal (AW index) reaction to external stimuli. Specifically, a greater value of AW indicates an increased propensity to stimulus approach, and vice versa a lower one a tendency to withdraw from the stimulus. Additionally, due to prelingually and postlingually deafened pathology acquisition, children and adults, respectively, would probably differ in music perception. The aim of the present study was to investigate children and adult CI users, in unilateral (UCI) and bilateral (BCI) implantation conditions, during three experimental situations of music exposure (normal, distorted and mute). Additionally, a study of functional connectivity patterns within cerebral networks was performed to investigate functioning patterns in different experimental populations. As a general result, congruency among patterns between BCI patients and control (CTRL) subjects was seen, characterised by lowest values for the distorted condition (vs. normal and mute conditions) in the AW index and in the connectivity analysis. Additionally, the normal and distorted conditions were significantly different in CI and CTRL adults, and in CTRL children, but not in CI children. These results suggest a higher capacity of discrimination and approach motivation towards normal music in CTRL and BCI subjects, but not for UCI patients. Therefore, for perception of music CTRL and BCI participants appear more similar than UCI subjects, as estimated by measurable and not self-reported parameters

Temporal changes in impedance of implanted adults for various cochlear segments

La prima valutazione oggettiva effettuata durante la procedura chirurgica e nel follow-up dei pazienti sottoposti ad impianto cocleare è la misura dellimpedenza degli elettrodi. Tale misura fornisce informazioni sia sullintegrità degli elettrodi sia sul mezzo circostante gli stessi ed è uno dei principali fattori responsabili dei consumi energetici dellimpianto cocleare. In questo studio abbiamo valutato in pazienti adulti con impianto cocleare e array perimodiolare, le variazioni nel tempo dellimpedenza degli elettrodi, valutando le differenze nelle varie partizioni cocleari (basale, medio e apicale) e correlandone i valori ai principali parametri psicoacustici del mappaggio: livelli di T e C. Abbiamo testato 28 pazienti adulti impiantati presso il nostro Dipartimento tra il 2009 e il 2014, tutti impiantati per via cocleostomica con un array perimodiolare completamente inserito, utilizzando la tecnica chirurgia soft surgery. Le impedenze medie sono state misurate in modalità common-ground e MP1+2 per i seguenti segmenti di array: basale (dallelettrodo n.1 al n.7); mediale (dal n.8 al n.14); apicale (dal n.15 al n.22). Lanalisi della varianza (ANOVA) è stata effettuata per valutare le tendenze nelle misure ripetute. Il livello di significatività accettato in tale studio è p<0.05 corretto con metodo Bonferroni. I risultati hanno mostrato una significativa riduzione globale delle impedenze dallattivazione fino a 1 mese e un valore più alto nel tempo dell impedenza nel segmento basale dellarray rispetto al segmento apicale e medio. Lanalisi statistica temporale della correlazione tra i valori dellimpedenza globale e i livelli di T e C ha mostrato una correlazione significativa fino a sei mesi sia per le impedenze registrate in common-ground che in modalità MP1+2. Lanalisi statistica dei vari segmenti cocleari ha mostrato inoltre una significativa correlazione dellimpedenza nel segmento basale e i parametri del fitting fino ad un anno di follow-up. In conclusione gli alti valori dell impedenza nel segmento basale nel tempo possono essere spiegati con la formazione di fibrosi endococleare dopo linserimento dellarray, fenomeno maggiore nel segmento basale della coclea, limitato invece nelle regioni apicali e medie. La correlazione lineare dei valori dellimpedenza con i livelli di T e C diventa infatti statisticamente non significativa dopo tre/sei mesi nei segmenti apicali e medi e resta significativa fino ad un anno per il tratto basale. Questo comportamento sottolinea limportanza nel tempo dellinfluenza dei fattori intra-cocleari sui parametri del fitting nella porzione cocleare basale

Microencapsulation of Phenolic Extracts from Cocoa Shells to Enrich Chocolate Bars

Cocoa bean shells were subjected to green extraction technologies, based on the absence of toxic organic solvents, to recover polyphenols; the extract was then encapsulated using a spray dryer and maltodextrin as coating agent. The best conditions observed in the spray drying tests (core-to-coating ratio 1:5; inlet temperature 150&nbsp;°C; flow rate 6&nbsp;ml&nbsp;min-1) were applied to produce the microcapsules used to enrich the same cocoa mass as the shells and processed for the preparation of the chocolate bars. Sensory analysis showed no significant differences between enriched chocolate bar and the unenriched reference one, except for the appearance. Both samples were then subjected to accelerated storage tests, at the end of which the polyphenols in the control chocolate bar (0.85&nbsp;g 100&nbsp;g-1) were reduced by about 50% (0.42&nbsp;g 100&nbsp;g-1), while in the enriched chocolate (1.17&nbsp;g 100&nbsp;g-1) by only 22% (0.97&nbsp;g 100&nbsp;g-1). The proposed process significantly enriched the chocolate bars with phenolic antioxidants recovered from cocoa waste without increasing the sensations of bitterness and astringency