InGaAs/InP single-photon detector gated at 1.3 GHz with 1.5% afterpulsing

We demonstrate a single-photon detector based on InGaAs/InP single-photon avalanche diodes (SPADs) sinusoidalgated at 1.3 GHz with very low afterpulsing (about 1.5%), high dynamic range (maximum count rate is 650 Mcount/s), high photon detection efficiency (>30% at 1550 nm), low noise (per-gate dark count rate is 2.2 x 10(-5)), and low timing jitter (<70 ps full-width at half-maximum). The SPAD is paired with a "dummy" structure that is biased in antiphase. The sinusoidal gating signals are cancelled by means of a common-cathode configuration and by adjusting the relative amplitude and phase of the signals biasing the two arms. This configuration allows us to adjust the gating frequency from 1 to 1.4 GHz and can be operated also in the so-called gate-free mode, with the gate sine-wave unlocked with respect to the light stimulus, resulting in a free-running equivalent operation of the InGaAs/InP SPAD with about 4% average photon detection efficiency at 1550 nm

InGaAs/InP SPAD with Monolithically Integrated Zinc-Diffused Resistor

Afterpulsing and optical crosstalk are significant performance limitations for applications employing near-infrared single-photon avalanche diodes (SPADs). In this paper, we describe an InGaAs/InP SPAD with monolithically integrated resistor that is fully compatible with the planar fabrication process and provides a significant reduction of the avalanche charge and, thus, of afterpulsing and optical crosstalk. In order to have a fast SPAD reset (<50 ns), we fabricated quenching resistors ranging from 10 to 200 k\Ω, smaller than what is available in the literature. The resistor, fabricated with the zinc diffusions already used for avoiding premature edge-breakdown, promptly reduces the avalanche current to a low value ∼ 100~ μ A in less than 1 ns, while an active circuit completes the quenching and enforces a well-defined hold-off. The proposed mixed-quenching approach guarantees an avalanche charge reduction of more than 20 times compared with similar plain SPADs, enough to reduce the hold-off time down to 1 μ s. Finally, a compact single-photon counting module based on this detector and featuring 70-ps photon-timing jitter is presented

Integrated Circuit for Subnanosecond Gating of InGaAs/InP SPAD

We present a novel integrated circuit for subnanosecond gating of InGaAs/InP single-photon avalanche diodes (SPADs). It enables the detector in well-defined time intervals (down to 500 ps) and strongly reduces the afterpulsing effect. It includes a fast pulser with rising/falling edge shorter than 300 ps (20%-80%), a wideband comparator and hold-off logic circuitry. The fast avalanche quenching reduces the charge flow in the SPAD, thus decreasing the afterpulsing, a detrimental effect that limits the maximum count rate of InGaAs/InP SPADs. The wideband SiGe comparator guarantees very low timing jitter of the acquired waveforms: <100 ps (FWHM) at 5 V excess bias voltage, when operated with InGaAs/InP SPAD, whereas we estimate that the time jitter of the circuit is < 30 ps

Design and verification of a micro wells turbine for Mediterranean operations

In the framework of the Poseidone Project we have designed a Wells turbine for Mediterranean operations. Here we present RANS computations carried out with OpenFOAM at different operating conditions. Rotor-stator interaction was synthetized with MRF approach and RANS closure relied on the cubic eddy viscosity closure of Lien et al. The virtual test rig reproduced the ISO conditions of the laboratory and was able to correctly predict torque and efficiency at different operations. Computations moreover allowed to acquire information on the threedimensional velocity and pressure field that develops inside the Wells turbine. The aim was to have an insight on the secondary motions and on the possible stall mechanism that characterize the device at low flow rates. Results were successfully validated against experimental measures

Glucocorticoid receptor signalling activates YAP in breast cancer

The Hippo pathway is an oncosuppressor signalling cascade that plays a major role in the control of cell growth, tissue homoeostasis and organ size. Dysregulation of the Hippo pathway leads to aberrant activation of the transcription co-activator YAP (Yes-associated protein) that contributes to tumorigenesis in several tissues. Here we identify glucocorticoids (GCs) as hormonal activators of YAP. Stimulation of glucocorticoid receptor (GR) leads to increase of YAP protein levels, nuclear accumulation and transcriptional activity in vitro and in vivo. Mechanistically, we find that GCs increase expression and deposition of fibronectin leading to the focal adhesion-Src pathway stimulation, cytoskeleton-dependent YAP activation and expansion of chemoresistant cancer stem cells. GR activation correlates with YAP activity in human breast cancer and predicts bad prognosis in the basal-like subtype. Our results unveil a novel mechanism of YAP activation in cancer and open the possibility to target GR to prevent cancer stem cells self-renewal and chemoresistance

InGaAs/InP single-photon detector with low noise, low timing jitter and high count rate

We present a new InGaAs/InP Single-Photon Avalanche Diode (SPAD) with high detection efficiency and low noise, which has been employed in a sinusoidal-gated setup to achieve very low afterpulsing probability and high count rate. The new InGaAs/InP SPAD has lower noise compared to previous generations thanks to the improvement of Zinc diffusion conditions and the optimization of the vertical structure. A detector with 25 μm active-area diameter, operated in gated-mode with ON time of tens of nanoseconds, has a dark count rate of few kilo-counts per second at 225 K and 5 V of excess bias, 30% photon detection efficiency at 1550 nm and a timing jitter of less than 90 ps (FWHM) at 7 V of excess bias. In order to reduce significantly the afterpulsing probability, these detectors were operated with a sinusoidal gate at 1.3 GHz. The extremely short gate ON time (less than 200 ps) reduces the charge flowing through the junction, thus reducing the number of trapped carriers and, eventually, lowering the afterpulsing probability. The resulting detection system achieves a maximum count rate higher than 650 Mcount/s with an afterpulsing probability of about 1.5%, a photon detection efficiency greater than 30% at 1550 nm and a temporal resolution of less than 90 ps (FWHM)

Anatomical theatre place of Knowledge – the pivotal role of anatomist in its realization

Human anatomy dissection represented a cornerstone in the evolution of medicine and modern scientific thought. The anatomical theatres, some of which are considered true masterpieces of architecture, are the place where concretely men learned to know themselves with a scientific method. Anatomists had a pivotal role in the buildings of anatomical theatres, using their knowledge in the research process of more functional architectures for demonstrative and experimental science. Antonio Scarpa (1752-1832) is an emblematic figure in this scenario. He studied anatomy at the University of Padua in the oldest permanent anatomical theatre of the world, originate in 1594 from a joint project conceived by Paolo Sarpi, scientist and church reformer, and Hieronymus Fabricius Ab Aquapendente, anatomist. In 1772, Scarpa became professor at the University of Modena. Bearing witness to the architectural value of the theatre in Padua is the fact that in 1774 Scarpa, involved in the planning for an anatomical theatre in Modena, had the professor of surgery in Padua, Girolamo Vandelli, send him a wooden model of the theatre there. Another project, less expensive, was selected instead. Later, in 1783, Scarpa was made professor of anatomy at the University of Pavia and promptly he promoted the building of an anatomical theatre there. The building was concluded in 1785, its semicircular layout is modeled on ancient theatres and the Palladian Olympic Theatre of Vicenza. Today, most of the anatomical theatres are lost or forgotten. The Thesa project will provide a census of anatomical theatres, both survived and not, which will allow us to identify connections among them, among the anatomists who studied there and the mutual influences that characterize their form. We believe the achievement of these objectives defines the essential conditions necessary to regain full awareness of the value of anatomical theatres in both the academic and popular contexts, thus creating a fertile cultural basis for new initiatives that can continue the quest for knowledge undertaken in the past in these places. From an architectural and evocative perspective, they are and will remain places where man puts himself at the centre and at the same time observes himself