Transmittivity measurements by means of squeezed vacuum light

A method for measuring the transmittivity of optical samples by using squeezed--vacuum radiation is illustrated. A squeezed vacuum field generated by a below--threshold optical parametric oscillator is propagated through a nondispersive medium and detected by a homodyne apparatus. The variance of the detected quadrature is used for measuring the transmittivity. With this method it is drastically reduced the number of photons passing through the sample during the measurement interval. The results of some tests are reported.Comment: 14 pages, 8 figure

A 100-element planar Schottky diode grid mixer

The authors present a Schottky diode grid mixer suitable for mixing or detecting quasi-optical signals. The mixer is a planar bow-tie grid structure periodically loaded with diodes. A simple transmission line model is used to predict the reflection coefficient of the grid to a normally incident plane wave. The grid mixer power handling and dynamic range scales as the number of devices in the grid. A 10-GHz 100-element grid mixer has shown an improvement in dynamic range of 16.3 to 19.8 dB over an equivalent single-diode mixer. The conversion loss and noise figure of the grid are equal to those of a conventional mixer. The quasi-optical coupling of the input signals makes the grid mixer suitable for millimeter-wave and submillimeter-wave applications by eliminating waveguide sidewall losses and machining difficulties. The planar property of the grid potentially allows thousands of devices to be integrated monolithically

Failures in power-combining arrays

We derive a simple formula for the change in output when a device fails in a power-combining structure with identical matched devices. The loss is written in terms of the scattering coefficient of the failed device and reflection coefficient of an input port in the combining network. We apply this formula to several power combiners, including arrays in free space and enclosed waveguide structures. Our simulations indicate the output power degrades gracefully as devices fail, which is in agreement with previously published results

Detection of Zak phases and topological invariants in a chiral quantum walk of twisted photons

Topological insulators are fascinating states of matter exhibiting protected edge states and robust quantized features in their bulk. Here, we propose and validate experimentally a method to detect topological properties in the bulk of one-dimensional chiral systems. We first introduce the mean chiral displacement, and we show that it rapidly approaches a multiple of the Zak phase in the long time limit. Then we measure the Zak phase in a photonic quantum walk, by direct observation of the mean chiral displacement in its bulk. Next, we measure the Zak phase in an alternative, inequivalent timeframe, and combine the two windings to characterize the full phase diagram of this Floquet system. Finally, we prove the robustness of the measure by introducing dynamical disorder in the system. This detection method is extremely general, as it can be applied to all one-dimensional platforms simulating static or Floquet chiral systems.Comment: 10 pages, 7 color figures (incl. appendices) Close to the published versio

Quasi-optical solid-state microwave sources

Quasi-optical power-combining offers the most promising method for extracting large amounts of power from solid-state devices in the microwave and millimeter-wave range. This technique can be applied to a variety of devices. The difficulties associated with traditional waveguides power-combiners such as skin-effect losses are eliminated because the signals are combined in free-space. The solid-state devices are embedded in a two-dimensional grid configuration and placed in a Fabry-Perot cavity. In this respect, the quasi-optical power-combiner is analogous to a laser oscillator in which the active medium of the laser is replaced with an array of active devices. The grid presents a reflection coefficient to an incident plane wave which is larger than unity and the resonator provides feedback to couple the devices together. The two-dimensional structure of the grid is amenable to modern photolithographic processing and potentially allows thousands of devices to be integrated monolithically

Regulation of Muscle Satellite Cell Activation and Chemotaxis by Angiotensin II

The role of angiotensin II (Ang II) in skeletal muscle is poorly understood. We report that pharmacological inhibition of Ang II signaling or ablation of the AT1a receptor significantly impaired skeletal muscle growth following myotrauma, in vivo, likely due to impaired satellite cell activation and chemotaxis. In vitro experiments demonstrated that Ang II treatment activated quiescent myoblasts as evidenced by the upregulation of myogenic regulatory factors, increased number of β-gal+, Myf5-LacZ myoblasts and the acquisition of cellular motility. Furthermore, exogenous treatment with Ang II significantly increased the chemotactic capacity of C2C12 and primary cells while AT1a−/− myoblasts demonstrated a severe impairment in basal migration and were not responsive to Ang II treatment. Additionally, Ang II interacted with myoblasts in a paracrine-mediated fashion as 4 h of cyclic mechanical stimulation resulted in Ang II-induced migration of cocultured myoblasts. Ang II-induced chemotaxis appeared to be regulated by multiple mechanisms including reorganization of the actin cytoskeleton and augmentation of MMP2 activity. Collectively, these results highlight a novel role for Ang II and ACE inhibitors in the regulation of skeletal muscle growth and satellite cell function

Il Nibbio reale Milvus milvus svernante in Italia, sintesi di cinque anni di monitoraggio

Beginning in December 2011, CISO has promoted a monitoring project for Red kite\u2019s wintering population in Italy. This paper shows the results of the first five survey seasons, ie from December 2011 to January 2016. The censuses, always done at sunset, covered the eleven Central-Southern regions for which winter roosts were already known. The number of actual kites censuses each winter varied between about 1500 and over 1700 individuals, with strong oscillations for single roosts. The population is mainly concentrated in Basilicata with more than 64% of the entire winter population. Interesting data were also been found in Lazio, Abruzzo and Molise, which altogether host about 25% of the national population. Encouraging data come from Tuscany where, following a reintroduction project, a wintering roost of about 80 units was found. Bad results are from censuses conducted in Campania, Calabria, Sicily and Sardinia, where the population seems to be greatly reduced

Association of Interleukin-6 Signalling with the Muscle Stem Cell Response Following Muscle-Lengthening Contractions in Humans

BACKGROUND: The regulation of muscle stem cells in humans in response to muscle injury remains largely undefined. Recently, interleukin-6 (IL-6) has been implicated in muscle stem cell (satellite cell)-mediated muscle hypertrophy in animals; however, the role of IL-6 in the satellite cell (SC) response following muscle-lengthening contractions in humans has not been studied. METHODOLOGY/PRINCIPAL FINDINGS: Eight subjects (age 22+/-1 y; 79+/-8 kg) performed 300 maximal unilateral lengthening contractions (3.14 rad.s(-1)) of the knee extensors. Blood and muscle samples were collected before and at 4, 24, 72, and 120 hours post intervention. IL-6, IL-6 receptor, IL-6R(alpha), cyclin D1, suppressor of cytokine signling-3 (SOCS3) mRNA were measured using quantitative RT-PCR and serum IL-6 protein was measured using an ELISA kit. JAK2 and STAT3 phosphorylated and total protein was measured using western blotting techniques. Immunohistochemical analysis of muscle cross-sections was performed for the quantification of SCs (Pax7(+) cells) as well as the expression of phosphorylated STAT3, IL-6, IL-6R(alpha), and PCNA across all time-points. The SC response, as defined by an amplification of Pax7(+) cells, was rapid, increasing by 24 h and peaking 72 h following the intervention. Muscle IL-6 mRNA increased following the intervention, which correlated strongly (R(2) = 0.89, p<0.002) with an increase in serum IL-6 concentration. SC IL-6R(alpha) protein was expressed on the fiber, but was also localized to the SC, and IL-6(+) SC increased rapidly following muscle-lengthening contractions and returned to basal levels by 72 h post-intervention, demonstrating an acute temporal expression of IL-6 with SC. Phosphorylated STAT3 was evident in SCs 4 h after lengthening contraction, and the downstream genes, cyclin D1 and SOCS3 were significantly elevated 24 hours after the intervention. CONCLUSIONS/SIGNIFICANCE: The increased expression of STAT3 responsive genes and expression of IL-6 within SCs demonstrate that IL-6/STAT3 signaling occurred in SCs, correlating with an increase in SC proliferation, evidenced by increased Pax7(+)/PCNA(+) cell number in the early stages of the time-course. Collectively, these data illustrate that IL-6 is an important signaling molecule associated with the SC response to acute muscle-lengthening contractions in humans